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Sample records for nonlinear transient evoked

  1. Transient evoked otoacoustic emissions in rock musicians.

    Science.gov (United States)

    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.

  2. Investigating the periodicity of transient-evoked otoacoustic emission envelopes

    DEFF Research Database (Denmark)

    Verhulst, Sarah

    2011-01-01

    This study investigates the cochlear origin of the multiple temporal lobes that are often observed in the transient-evoked otoacoustic emission (TEOAE) envelope. This "waxing and waning" of the OAE amplitude can be observed in tone-burst (TB) OAEs and sometimes also in click-evoked (CE) OAEs. TBOAE...... and the middle-ear boundary may contribute to the TBOAE envelope periodicity, but were not the main modulation component in waxing and waning of the investigated TBOAEs....

  3. Nonlinear Diffusion and Transient Osmosis

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    Akira, Igarashi; Lamberto, Rondoni; Antonio, Botrugno; Marco, Pizzi

    2011-08-01

    We investigate both analytically and numerically the concentration dynamics of a solution in two containers connected by a narrow and short channel, in which diffusion obeys a porous medium equation. We also consider the variation of the pressure in the containers due to the flow of matter in the channel. In particular, we identify a phenomenon, which depends on the transport of matter across nano-porous membranes, which we call “transient osmosis". We find that nonlinear diffusion of the porous medium equation type allows numerous different osmotic-like phenomena, which are not present in the case of ordinary Fickian diffusion. Experimental results suggest one possible candidate for transiently osmotic processes.

  4. Nonlinear Diffusion and Transient Osmosis

    Institute of Scientific and Technical Information of China (English)

    Akira Igarashi; Lamberto Rondon; Antonio Botrugno; Marco Pizzi

    2011-01-01

    We investigate both analytically and numerically the concentration dynamics of a solution in two containers connected by a narrow and short channel, in which diffusion obeys a porous medium equation. We also consider the variation of the pressure in the containers due to the flow of matter in the channel. In particular, we identify a phenomenon, which depends on the transport of matter across nano-porous membranes, which we call "transient osmosis". We find that nonlinear diffusion of the porous medium equation type allows numerous different osmotic-like phenomena, which are not present in the case of ordinary Fickian diffusion. Experimental results suggest one possible candidate for transiently osmotic processes.

  5. Modeling auditory evoked brainstem responses to transient stimuli

    DEFF Research Database (Denmark)

    Rønne, Filip Munch; Dau, Torsten; Harte, James

    2012-01-01

    A quantitative model is presented that describes the formation of auditory brainstem responses (ABR) to tone pulses, clicks and rising chirps as a function of stimulation level. The model computes the convolution of the instantaneous discharge rates using the “humanized” nonlinear auditory...... of tone-pulse evoked wave-V latency with frequency but underestimates the level dependency of the tone-pulse as well as click-evoked latency values. Furthermore, the model correctly predicts the nonlinear wave-V amplitude behavior in response to the chirp stimulation both as a function of chirp sweeping...... rate and level. Overall, the results support the hypothesis that the pattern of ABR generation is strongly affected by the nonlinear and dispersive processes in the cochlea....

  6. Application of transient evoked otoacoustic emissions to pediatric populations.

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    Norton, S J

    1993-02-01

    Transient evoked otoacoustic emissions (TEOAEs) occur after presentation of brief acoustic stimuli such as clicks and tone pips. They represent physiological activity from within the cochlea, specifically from normal functioning outer hair cells. TEOAEs are frequency specific in that their spectra are determined by the spectra of the evoking stimulus and the audiometric configuration. TEOAEs are sensitive to mild to moderate degrees of cochlear hearing loss up to about 40 to 50 dB HL. They can be measured rapidly and noninvasively in infants and children. Among the potential applications in pediatric audiology are screening for hearing impairment in neonates, separating peripheral hearing loss and central auditory dysfunction, and monitoring cochlear status in children receiving ototoxic drugs.

  7. Changes of Transient Visual Evoked Potentials in Dyslexic Children

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    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.

  8. Transient Evoked and Distortion Product Otoacoustic Emissions in a Group of Neonates

    Science.gov (United States)

    Silva, Giovanna Cesar; Delecrode, Camila Ribas; Kemp, Adriana Tahara; Martins, Fabiana; Cardoso, Ana Claudia Vieira

    2015-01-01

    Introduction The most commonly used method in neonatal hearing screening programs is transient evoked otoacoustic emissions in the first stage of the process. There are few studies comparing transient evoked otoacoustic emissions with distortion product, but some authors have investigated the issue. Objective To correlate the results of transient evoked and distortion product otoacoustic emissions in a Brazilian maternity hospital. Methods This is a cross-sectional, comparative, and prospective study. The study included 579 newborns, ranging from 6 to 54 days of age, born in a low-risk maternity hospital and assessed for hearing loss. All neonates underwent hearing screening by transient evoked and distortion product otoacoustic emissions. The results were analyzed using the Spearman correlation test to relate the two procedures. Results The pass index on transient evoked otoacoustic emissions was 95% and on distortion product otoacoustic emissions was 91%. The comparison of the two procedures showed that 91% of neonates passed on both procedures, 4.5% passed only on transient evoked otoacoustic emissions, 0.5% passed only on distortion product otoacoustic emissions, and 4% failed on both procedures. The inferential analysis showed a significant strong positive relationship between the two procedures. Conclusion The failure rate was higher in distortion product otoacoustic emissions when compared with transient evoked; however, there was correlation between the results of the procedures. PMID:26157501

  9. Nonlinear transient analysis of joint dominated structures

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    Chapman, J. M.; Shaw, F. H.; Russell, W. C.

    1987-01-01

    A residual force technique is presented that can perform the transient analyses of large, flexible, and joint dominated structures. The technique permits substantial size reduction in the number of degrees of freedom describing the nonlinear structural models and can account for such nonlinear joint phenomena as free-play and hysteresis. In general, joints can have arbitrary force-state map representations but these are used in the form of residual force maps. One essential feature of the technique is to replace the arbitrary force-state maps describing the nonlinear joints with residual force maps describing the truss links. The main advantage of this replacement is that the incrementally small relative displacements and velocities across a joint are not monitored directly thereby avoiding numerical difficulties. Instead, very small and 'soft' residual forces are defined giving a numerically attractive form for the equations of motion and thereby permitting numerically stable integration algorithms. The technique was successfully applied to the transient analyses of a large 58 bay, 60 meter truss having nonlinear joints. A method to perform link testing is also presented.

  10. Transiently Evoked Otoacoustic Emissions in Children with Otitis Media with Effusion

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    Dimitris G. Balatsouras

    2012-01-01

    Full Text Available Introduction. Otitis media with effusion is a common pediatric disease whose diagnosis is based on pneumatic otoscopy, pure-tone audiometry, and tympanometry. The aim of this study was to evaluate transiently evoked otoacoustic emissions in the diagnosis of otitis media with effusion as compared to tympanometry. Patients and Methods. 38 children with bilateral otitis media with effusion were studied. 40 normal children of similar age and sex were used as controls. All subjects underwent pneumatic otoscopy, standard pure-tone audiometry, tympanometry, and transiently evoked otoacoustic emissions. Results. In the group of children with bilateral otitis media, transiently evoked otoacoustic emissions were absent in 51 ears (67%. In the remaining 25 ears (33% the mean emission amplitude was reduced, as compared to the mean value of the control group. Conclusions. Transiently evoked otoacoustic emissions should be included in the diagnostic workup of otitis media with effusion because it is a fast, reliable, and objective test. Transiently evoked otoacoustic emissions should always be used in conjunction with tympanometry, because a more meaningful interpretation of transiently evoked otoacoustic emissions measures is possible.

  11. Nonlinear damping identification from transient data

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    Smith, Clifford B.; Wereley, Norman M.

    1999-06-01

    To study new damping augmentation methods for helicopter rotor systems, accurate and reliable nonlinear damping identification techniques are needed. For example, current studies on applications of magnetorheological (MR) dampers for rotor stability augmentation suggest that a strong Coulomb damping characteristic will be manifested as the field applied to the MR fluid is maximized. Therefore, in this work, a single degree of freedom (SDOF) system having either nonlinear Coulomb or quadratic damping is considered. This paper evaluates three analyses for identifying damping from transient test data; an FFT-based moving block analysis, an analysis based on a periodic Fourier series decomposition, and a Hilbert transform based technique. Analytical studies are used to determine the effects of block length, noise, and error in identified modal frequency on the accuracy of the identified damping level. The FFT-based moving block has unacceptable performance for systems with nonlinear damping. These problems were remedied in the Fourier series based analysis and acceptable performance is obtained for nonlinear damping identification from both this technique and the Hilbert transform based method. To more closely simulate a helicopter rotor system test, these techniques were then applied to a signal composed of two closely spaced modes. This data was developed to simulate a response containing the first lag and 1/rev modes. The primary mode of interest (simulated lag mode) had either Coulomb or quadratic damping, and the close mode (1/rev) was either undamped or had a specified viscous damping level. A comprehensive evaluation of the effects of close mode amplitude, frequency, and damping level was performed. A classifier was also developed to identify the dominant damping mechanism in a signal of 'unknown' composition. This classifier is based on the LMS error of a fit of the analytical envelope expression to the experimentally identified envelope signal. In most

  12. Numerical study of transient nonlinear harbor resonance

    Institute of Scientific and Technical Information of China (English)

    2010-01-01

    It is generally accepted that nonlinear wave-wave interactions play an important role in harbor resonance. Nevertheless it is not clear how waves take part in those interactions. The aim of this paper is to investigate those processes for a rectangular harbor at transient phases. Long-period oscillations excited by bichromatic waves are simulated by the Boussinesq model. The simulations start from calm conditions for the purpose of studying the response process. The internal wavemaker stops working after the oscillations have reached a quasi-steady state, and it is used to simulate the damp process. In order to analyze temporary features of wave-wave interactions in different states, the wavelet-based bispectrum is employed. The influence of the short wave frequencies on long-period oscillations is investigated, and reasons are tried to be given from nonlinear triad interactions between different wave components and the interaction of short waves and the bay entrance. Finally, the response time and the damp time are estimated by a simple method.

  13. Formalin evokes calcium transients from the endoplasmatic reticulum.

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    Michael J M Fischer

    Full Text Available The formalin test is the most widely used behavioral screening test for analgesic compounds. The cellular mechanism of action of formaldehyde, inducing a typically biphasic pain-related behavior in rodents is addressed in this study. The chemoreceptor channel TRPA1 was suggested as primary transducer, but the high concentrations used in the formalin test elicit a similar response in TRPA1 wildtype and knockout animals. Here we show that formaldehyde evokes a dose-dependent calcium release from intracellular stores in mouse sensory neurons and primary keratinocytes as well as in non-neuronal cell lines, and independent of TRPA1. The source of calcium is the endoplasmatic reticulum and inhibition of the sarco/endoplasmic reticulum calcium-ATPase has a major contribution. This TRPA1-independent mechanism may underlie formaldehyde-induced pan-neuronal excitation and subsequent inflammation.

  14. Transient visual evoked neuromagnetic responses: Identification of multiple sources

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    Aine, C.; George, J.; Medvick, P.; Flynn, E.; Bodis-Wollner, I.; Supek, S.

    1989-01-01

    Neuromagnetic measurements and associated modeling procedures must be able to resolve multiple sources in order to localize and accurately characterize the generators of visual evoked neuromagnetic activity. Workers have identified at least 11 areas in the macaque, throughout occipital, parietal, and temporal cortex, which are primarily or entirely visual in function. The surface area of the human occipital lobe is estimated to be 150--250cm. Primary visual cortex covers approximately 26cm/sup 2/ while secondary visual areas comprise the remaining area. For evoked response amplitudes typical of human MEG data, one report estimates that a two-dipole field may be statistically distinguishable from that of a single dipole when the separation is greater than 1--2 cm. Given the estimated expanse of cortex devoted to visual processes, along with this estimate of resolution limits it is likely that MEG can resolve sources associated with activity in multiple visual areas. Researchers have noted evidence for the existence of multiple sources when presenting visual stimuli in a half field; however, they did not attempt to localize them. We have examined numerous human MEG field patterns resulting from different visual field placements of a small sinusoidal grating which suggest the existence of multiple sources. The analyses we have utilized for resolving multiple sources in these studies differ depending on whether there was evidence of (1) synchronous activation of two spatially discrete sources or (2) two discrete asynchronous sources. In some cases we have observed field patterns which appear to be adequately explained by a single source changing its orientation and location across time. 4 refs., 2 figs.

  15. Visual evoked potentials monitoring in a case of transient post-operative visual loss

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    Marie Capon

    2016-01-01

    Full Text Available Post-operative visual loss (POVL is a rare, albeit potentially serious complication of general anaesthesia. This report describes the case of a 54-year-old woman who developed transient POVL after general anaesthesia following a left posterior parietal meningioma surgery in the prone position and discusses the usefulness of visual evoked potentials monitoring in such situations.

  16. Analysis of nonlinear transient responses of piezoelectric resonators.

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    Hagiwara, Manabu; Takahashi, Seita; Hoshina, Takuya; Takeda, Hiroaki; Tsurumi, Takaaki

    2011-09-01

    The electric transient response method is an effective technique to evaluate material constants of piezoelectric ceramics under high-power driving. In this study, we tried to incorporate nonlinear piezoelectric behaviors in the analysis of transient responses. As a base for handling the nonlinear piezoelectric responses, we proposed an assumption that the electric displacement is proportional to the strain without phase lag, which could be described by a real and constant piezoelectric e-coefficient. Piezoelectric constitutive equations including nonlinear responses were proposed to calculate transient responses of a piezoelectric resonator. The envelopes and waveforms of current and vibration velocity in transient responses observed in some piezoelectric ceramics could be fitted with the calculation including nonlinear responses. The procedure for calculation of mechanical quality factor Q(m) for piezoelectric resonators with nonlinear behaviors was also proposed.

  17. Transmitter modulation of spike-evoked calcium transients in arousal related neurons

    DEFF Research Database (Denmark)

    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...

  18. Effects of changes in dynamic characteristics of the middle ear on transient-evoked otoacoustic emissions

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    Špirić Sanja

    2011-01-01

    Full Text Available Transient-evoked otoacoustic emissions are transmitted through the middle ear. The purpose of this study was to investigate the effects of dynamic properties of the transmission system on the measurability of transient otoacoustic emissions. The authors analyzed the presence of transient otoacoustic emissions in 48 children with serous otitis media regarding the tympanogram, presence and type of effusion and pure tone average findings. The results obtained in this research show the predominant absence of transient otoacoustic emissions in patients with type B tympanogram (69.1% especially if the effusion is mucoid (77.5% with the hearing loss of 15 decibel hearing level. This research shows that disorders in dynamic characteristics of the middle ear in patients with serous otitis obstruct the transmission of acoustic energy and affect the measurability of transient otoacoustic emissions, especially if the effusion is mucoid and hearing loss of 15 decibel hearing level.

  19. Photonic Nonlinear Transient Computing with Multiple-Delay Wavelength Dynamics

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    Martinenghi, Romain; Rybalko, Sergei; Jacquot, Maxime; Chembo, Yanne K.; Larger, Laurent

    2012-06-01

    We report on the experimental demonstration of a hybrid optoelectronic neuromorphic computer based on a complex nonlinear wavelength dynamics including multiple delayed feedbacks with randomly defined weights. This neuromorphic approach is based on a new paradigm of a brain-inspired computational unit, intrinsically differing from Turing machines. This recent paradigm consists in expanding the input information to be processed into a higher dimensional phase space, through the nonlinear transient response of a complex dynamics excited by the input information. The computed output is then extracted via a linear separation of the transient trajectory in the complex phase space. The hyperplane separation is derived from a learning phase consisting of the resolution of a regression problem. The processing capability originates from the nonlinear transient, resulting in nonlinear transient computing. The computational performance is successfully evaluated on a standard benchmark test, namely, a spoken digit recognition task.

  20. Newborn hearing screening by transient evoked otoacoustic emissions: analysis of response as a function of risk factors.

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    De Capua, B; De Felice, C; Costantini, D; Bagnoli, F; Passali, D

    2003-02-01

    Hearing loss can be considered as the most common birth defect. Early detection of hearing loss by screening at, or shortly after, birth and appropriate intervention are critical to speech, language and cognitive development. In the present study, the characteristics of Transient Evoked Otoacoustic Emissions have been evaluated as a function of known pre- and perinatal risk factors for hearing loss. All newborns were screened for hearing loss using a physiologic test of hearing function, the Transient Evoked Otoacoustic Emissions. A total of 532 consecutive newborn infants received binaural Transient Evoked Otoacoustic Emission testing (262 males, 270 females; mean gestational age 39.2 +/- 2.1 weeks, range 26-43; birth weight: 3,240 +/- 550 g, range 910-4,780). The population examined comprised 448 control infants and 84 high-risk for hearing loss infants (Joint Committee on Infant Hearing 1994 criteria). All Transient Evoked Otoacoustic Emission recordings were performed at comparable postconceptional ages. Audiological screening by Transient Evoked Otoacoustic Emission recording showed an overall 100% sensitivity, 99.02% specificity, with negative and positive predictive values of 100% and 62.5%, respectively. As compared to controls, high-risk infants showed: 1. increased rates of Fail-1 (Transient Evoked Otoacoustic Emissions absent at first examination, 21.4% vs 9.8%, p = 0.004), Fail-2 (Transient Evoked Otoacoustic Emissions absent on retesting: 8.64% vs 1.37%, p = 0.0014), false positives (Transient Evoked Otoacoustic Emissions absent/V wave present: 3.7% vs 0.46%, p = 0.029) and true positives (Transient Evoked Otoacoustic Emissions absent, V wave absent: 2.47% or 24.5 per 1,000 live births vs 0.22% or 2.2 per 1,000 live births, p = 0.013); 2. significantly reduced Transient Evoked Otoacoustic Emission intensity in the 0.7-1 kHz (right side) and 1-2 kHz (left side) frequency ranges. Multivariate logistic regression analysis showed a significant positive

  1. A hybrid transfinite element approach for nonlinear transient thermal analysis

    Science.gov (United States)

    Tamma, Kumar K.; Railkar, Sudhir B.

    1987-01-01

    A new computational approach for transient nonlinear thermal analysis of structures is proposed. It is a hybrid approach which combines the modeling versatility of contemporary finite elements in conjunction with transform methods and classical Bubnov-Galerkin schemes. The present study is limited to nonlinearities due to temperature-dependent thermophysical properties. Numerical test cases attest to the basic capabilities and therein validate the transfinite element approach by means of comparisons with conventional finite element schemes and/or available solutions.

  2. On Constructing the Minimal Seed of Turbulence: Nonlinear Transient Growth

    CERN Document Server

    Pringle, Chris C T

    2010-01-01

    Linear transient growth analysis is commonly used to suggest the structure of disturbances which are particularly efficient in triggering transition to turbulence in shear flows. We demonstrate that the addition of nonlinearity to the analysis can substantially change the prediction made in pipe flow from simple 2 dimensional streamwise rolls to a spanwise and cross-stream localised 3 dimensional state. This new nonlinear optimal is demonstrably more efficient in triggering turbulence than the linear optimal indicating that there are better ways to design perturbations to achieve transition.

  3. Calcium transient evoked by nicotine in isolated rat vagal pulmonary sensory neurons.

    Science.gov (United States)

    Xu, Jennings; Yang, Wenbin; Zhang, Guangfan; Gu, Qihai; Lee, Lu-Yuan

    2007-01-01

    It has been shown that inhaled cigarette smoke activates vagal pulmonary C fibers and rapidly adapting receptors (RARs) in the airways and that nicotine contained in the smoke is primarily responsible. This study was carried out to determine whether nicotine alone can activate pulmonary sensory neurons isolated from rat vagal ganglia; the response of these neurons was determined by fura-2-based ratiometric Ca(2+) imaging. The results showed: 1) Nicotine (10(-4) M, 20 s) evoked a transient increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) in 175 of the 522 neurons tested (Delta[Ca(2+)](i) = 142.2 +/- 12.3 nM); the response was reproducible, with a small reduction in peak amplitude in the same neurons when the challenge was repeated 20 min later. 2) A majority (59.7%) of these nicotine-sensitive neurons were also activated by capsaicin (10(-7) M). 3) 1,1-Dimethyl-4-phenylpiperazinium iodide (DMPP; 10(-4) M, 20 s), a selective agonist of the neuronal nicotinic acetylcholine receptors (NnAChRs), evoked a pattern of response similar to that of nicotine. 4) The responses to nicotine and DMPP were either totally abrogated or markedly attenuated by hexamethonium (10(-4) M). 5) In anesthetized rats, right atrial bolus injection of nicotine (75-200 mug/kg) evoked an immediate (latency <1-2 s) and intense burst of discharge in 47.8% of the pulmonary C-fiber endings and 28.6% of the RARs tested. In conclusion, nicotine exerts a direct stimulatory effect on vagal pulmonary sensory nerves, and the effect is probably mediated through an activation of the NnAChRs expressed on the membrane of these neurons.

  4. Measurement of elastic nonlinearity of soft solid with transient elastography

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    Catheline, S.; Gennisson, J.-L.; Fink, M.

    2003-12-01

    Transient elastography is a powerful tool to measure the speed of low-frequency shear waves in soft tissues and thus to determine the second-order elastic modulus μ (or the Young's modulus E). In this paper, it is shown how transient elastography can also achieve the measurement of the nonlinear third-order elastic moduli of an Agar-gelatin-based phantom. This method requires speed measurements of polarized elastic waves measured in a statically stressed isotropic medium. A static uniaxial stress induces a hexagonal anisotropy (transverse isotropy) in solids. In the special case of uniaxially stressed isotropic media, the anisotropy is not caused by linear elastic coefficients but by the third-order nonlinear elastic constants, and the medium recovers its isotropic properties as soon as the uniaxial stress disappears. It has already been shown how transient elastography can measure the elastic (second-order) moduli in a media with transverse isotropy such as muscles. Consequently this method, based on the measurement of the speed variations of a low-frequency (50-Hz) polarized shear strain waves as a function of the applied stress, allows one to measure the Landau moduli A, B, C that completely describe the third-order nonlinearity. The several orders of magnitude found among these three constants can be justified from the theoretical expression of the internal energy.

  5. Measurement of elastic nonlinearity of soft solid with transient elastography.

    Science.gov (United States)

    Catheline, S; Gennisson, J L; Fink, M

    2003-12-01

    Transient elastography is a powerful tool to measure the speed of low-frequency shear waves in soft tissues and thus to determine the second-order elastic modulus mu (or the Young's modulus E). In this paper, it is shown how transient elastography can also achieve the measurement of the nonlinear third-order elastic moduli of an Agar-gelatin-based phantom. This method requires speed measurements of polarized elastic waves measured in a statically stressed isotropic medium. A static uniaxial stress induces a hexagonal anisotropy (transverse isotropy) in solids. In the special case of uniaxially stressed isotropic media, the anisotropy is not caused by linear elastic coefficients but by the third-order nonlinear elastic constants, and the medium recovers its isotropic properties as soon as the uniaxial stress disappears. It has already been shown how transient elastography can measure the elastic (second-order) moduli in a media with transverse isotropy such as muscles. Consequently this method, based on the measurement of the speed variations of a low-frequency (50-Hz) polarized shear strain waves as a function of the applied stress, allows one to measure the Landau moduli A, B, C that completely describe the third-order nonlinearity. The several orders of magnitude found among these three constants can be justified from the theoretical expression of the internal energy.

  6. Nonlinear transient and chaotic interactions in disc brake squeal

    Science.gov (United States)

    Oberst, S.; Lai, J. C. S.

    2015-04-01

    In automotive disc-brake squeal, most numerical studies have been focussed on the prediction of unstable vibration modes in the frequency domain using the complex eigenvalue analysis. However, the magnitude of the positive real part of a complex eigenvalue is an unreliable indicator of squeal occurrence. Although nonlinearities have been shown to play a significant role in brake squeal, transient nonlinear time domain analyses have rarely been applied owing to high computational costs. Here the complex eigenvalue analysis, the direct steady-state analysis and the transient nonlinear time domain analysis are applied to an isotropic pad-on-disc finite element model representing a simple model of a brake system. While in this investigation, in-plane pad-mode instabilities are not detected by the complex eigenvalue analysis, the dissipated energy obtained by the direct steady-state analysis of the model subjected to harmonic contact pressure excitation is negative at frequencies of pad modes, indicating a potential for instabilities. Transient nonlinear time domain analysis of the pad and disc dynamics reveal that in-plane pad vibrations excite a dominant out-of-plane disc mode. For intermittently chaotic pad motion, the disc dynamics is quasi-periodic; and for chaotic motion of the pad, a toroidal attractor is found for the disc's out-of-plane motion. Nonlinear interactions between the pad and the disc highlight that different parts in a brake system display different dynamic behaviour and need to be analysed separately. The type II intermittency route to chaos could be the cause for the experimentally observed instantaneous mode squeal.

  7. Contralateral acoustic suppression of transient evoked otoacoustic emissions: Activation of the medial olivocochlear system

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    Komazec Zoran

    2003-01-01

    Full Text Available Medial olivocochlear pathway represents the final part of efferent acoustic pathway which comes from the superior olivary complex ending at outer hair cells. Activation of medial olivocochlear system (MOCS alters the cochlear output decreasing the travelling wave within cochlea. Stimulation of MOCS provides protection against moderate levels of noise, encoding noise signals as well as selecting hearing attention. Activation of MOCS can be performed using contralateral acoustic stimulation. The principal result of presentation of contralateral acoustic stimulation during screening of transient evoked otoacoustic emission (TEOAE is an attenuation of the TEOAE amplitude. Thirty-eight ears were examined in this study: twenty-eight ears from 14 normal-hearing adults and 10 patients with unilateral deafness. Healthy subjects were exposed to contralateral broad-band noise of various intensities (40, 30, 20 and 10 dB SL, as well as 30 dB SL pure tone stimulation (1 kHz and 4 kHz. A decrease of TEOAE amplitudes during contralateral stimulation with 40 and 30 dB SL broad-band noise and pure tones was established. This effect was a result of MOCS activation. A greater intensity of contralateral stimulation evoked greater decrease of TEOAE amplitude; stimulation with broad-band noise caused greater attenuation than with pure tone stimulation. Contralateral stimulation of deaf ears in the group with unilateral deafness was also performed. Statistically significant difference between TEOAE amplitude before and during contralateral stimulation was not established. This circumstance explains that activation of MOCS and consequent reduction of outer hair cells motility is very possibly caused by contralateral acoustic stimulation. Apart from studying physiological significance of efferent auditory system, results of this and similar studies can be used for production of hearing aids improving speech discrimination in noisy environment.

  8. Multi-variant analysis of otoacoustic emissions and estimation of hearing thresholds: transient evoked otoacoustic emissions.

    Science.gov (United States)

    Vinck, B M; Van Cauwenberge, P B; Corthals, P; De Vel, E

    1998-01-01

    Evaluation of cochlear hearing loss by means of transiently evoked otoacoustic emissions is already established in clinical practice. However, accurate prediction of pure-tone thresholds is still questioned and is still regarded as troublesome. Both click- and tone-burst-evoked otoacoustic emissions at several intensity levels were measured and analysed in 157 ears from normally hearing and 432 ears from patients with different degrees of pure sensory hearing loss using the ILO88/92 equipment. Results of otoacoustic emissions (OAE), elicited by clicks and tone-bursts at centre frequencies from 1 to 5 kHz, were analysed using two different statistical methods. Both multivariate discriminant analysis and forward multiple regression analysis were used to determine which OAE variables were most discriminating and best at predicting hearing thresholds. We found that a limited set of variables obtained from both tone-burst and click measurements can accurately predict and categorize hearing loss levels up to a limit of 60 dB HL. We found correct classification scores of pure-tone thresholds between 500 and 4000 Hz up to 100 per cent when using combined click and tone-burst otoacoustic measurements. Prediction of pure-tone thresholds was correct with a maximum estimation error of 10 dB for audiometric octave frequencies between 500 and 4000 Hz. Measurements of multiple tone-bursts OAEs have a significant clinical advantage over the use of clicks alone for clinical applications, and a good classification and prediction of pure-tone thresholds with otoacoustic emissions is possible.

  9. A nonlinear analytic function expansion nodal method for transient calculations

    Energy Technology Data Exchange (ETDEWEB)

    Joo, Han Gyn; Park, Sang Yoon; Cho, Byung Oh; Zee, Sung Quun [Korea Atomic Energy Research Institute, Taejon (Korea, Republic of)

    1998-12-31

    The nonlinear analytic function expansion nodal (AFEN) method is applied to the solution of the time-dependent neutron diffusion equation. Since the AFEN method requires both the particular solution and the homogeneous solution to the transient fixed source problem, the derivation of the solution method is focused on finding the particular solution efficiently. To avoid complicated particular solutions, the source distribution is approximated by quadratic polynomials and the transient source is constructed such that the error due to the quadratic approximation is minimized, In addition, this paper presents a new two-node solution scheme that is derived by imposing the constraint of current continuity at the interface corner points. The method is verified through a series of application to the NEACRP PWR rod ejection benchmark problems. 6 refs., 2 figs., 1 tab. (Author)

  10. Discrete oscillator design linear, nonlinear, transient, and noise domains

    CERN Document Server

    Rhea, Randall W

    2014-01-01

    Oscillators are an essential part of all spread spectrum, RF, and wireless systems, and today's engineers in the field need to have a firm grasp on how they are designed. Presenting an easy-to-understand, unified view of the subject, this authoritative resource covers the practical design of high-frequency oscillators with lumped, distributed, dielectric and piezoelectric resonators. Including numerous examples, the book details important linear, nonlinear harmonic balance, transient and noise analysis techniques. Moreover, the book shows you how to apply these techniques to a wide range of os

  11. Probabilistic finite elements for transient analysis in nonlinear continua

    Science.gov (United States)

    Liu, W. K.; Belytschko, T.; Mani, A.

    1985-01-01

    The probabilistic finite element method (PFEM), which is a combination of finite element methods and second-moment analysis, is formulated for linear and nonlinear continua with inhomogeneous random fields. Analogous to the discretization of the displacement field in finite element methods, the random field is also discretized. The formulation is simplified by transforming the correlated variables to a set of uncorrelated variables through an eigenvalue orthogonalization. Furthermore, it is shown that a reduced set of the uncorrelated variables is sufficient for the second-moment analysis. Based on the linear formulation of the PFEM, the method is then extended to transient analysis in nonlinear continua. The accuracy and efficiency of the method is demonstrated by application to a one-dimensional, elastic/plastic wave propagation problem. The moments calculated compare favorably with those obtained by Monte Carlo simulation. Also, the procedure is amenable to implementation in deterministic FEM based computer programs.

  12. Time-frequency analysis of transient-evoked otoacoustic emissions in children exposed to carboplatin chemotherapy.

    Science.gov (United States)

    Bhagat, Shaum; Bass, Johnnie; Qaddoumi, Ibrahim; Brennan, Rachel; Wilson, Matthew; Wu, Jianrong; Galindo, Carlos-Rodriguez; Paglialonga, Alessia; Tognola, Gabriella

    2013-01-01

    The aims of this study were to characterize and quantify time-frequency changes in transient-evoked otoacoustic emissions (TEOAEs) recorded in children diagnosed with retinoblastoma who were receiving carboplatin chemotherapy. A signal processing technique, the wavelet transform (WT), was used to analyze TEOAE waveforms in narrow-band frequency components. Ten children (aged 3-72 months) diagnosed with unilateral or bilateral retinoblastoma were enrolled in the study. TEOAEs were acquired from the children with linear sequences of 70 dB peak equivalent SPL clicks. After WT analysis, TEOAE energy, latency and normalized energy in the narrow-band frequency components were compared before and during carboplatin chemotherapy treatment (average dose 1693 mg/m2). On a group basis, no significant differences (p>0.05) in the TEOAE energy, latency or normalized energy before and after carboplatin treatment were observed. There were decreases in normalized energy on an individual basis in 10 out of 18 ears in the sample. Exposure to carboplatin chemotherapy did not cause significant changes in TEOAE energy, latency and normalized energy during treatment. However, long-term monitoring of hearing with measurements of TEOAEs is warranted, given the risks of delayed hearing loss in some children receiving carboplatin chemotherapy.

  13. Normal and dichromatic color discrimination measured with transient visual evoked potential.

    Science.gov (United States)

    Gomes, Bruno D; Souza, Givago S; Rodrigues, Anderson R; Saito, Cézar A; Silveira, Luiz Carlos L; da Silva Filho, Manoel

    2006-01-01

    It would be informative to have an electrophysiological method to study, in an objective way, the effects of mercury exposure and other neurotoxics on human color vision performance. The purpose of the present work was to study human color discrimination by measuring chromatic difference thresholds with visual evoked potential (VEP). Six young normal trichromats (24 +/- 1 years old) and one deutan (26 years old) were tested. The stimuli consisted of sinusoidal isoluminant chromatic gratings made from chromaticity pairs located along four different color directions centered on two reference points. Heterochromatic flicker photometry (HFP) protocol was used to obtain the isoluminance condition for every subject and for all chromaticity pairs. Spatial frequency was 2 cycles/deg. Presentation mode comprised onset (300 ms)/offset (700 ms) periods. As previously described, we found a negative deflection in the VEP which was related to the chromatic difference: as chromatic difference increased, amplitude increased and latency decreased. VEP response amplitude was plotted against distance in the CIE 1976 color space between the grating chromaticities and fitted with a regression line. We found color thresholds by extrapolating the fitting to null amplitude values. The thresholds were plotted in the CIE 1976 color space as MacAdam ellipses. In normal trichromats the ellipses had small size, low ellipticity, and were vertically oriented. In the deutan subject, the ellipses had large size, high ellipticity, and were oriented towards the deutan copunctal locus. The VEP thresholds were similar to those obtained using grating stimuli and psychophysical procedures, however smaller than those obtained using pseudoisochromatic stimuli (Mollon-Reffin method). We concluded that transient VEP amplitude as a function of contrast can be reliably used in objective studies of chromatic discrimination performance in normal and altered human subjects.

  14. Rapid and Objective Assessment of Neural Function in Autism Spectrum Disorder Using Transient Visual Evoked Potentials

    Science.gov (United States)

    Siper, Paige M.; Zemon, Vance; Gordon, James; George-Jones, Julia; Lurie, Stacey; Zweifach, Jessica; Tavassoli, Teresa; Wang, A. Ting; Jamison, Jesslyn; Buxbaum, Joseph D.; Kolevzon, Alexander

    2016-01-01

    Objective There is a critical need to identify biomarkers and objective outcome measures that can be used to understand underlying neural mechanisms in autism spectrum disorder (ASD). Visual evoked potentials (VEPs) offer a noninvasive technique to evaluate the functional integrity of neural mechanisms, specifically visual pathways, while probing for disease pathophysiology. Methods Transient VEPs (tVEPs) were obtained from 96 unmedicated children, including 37 children with ASD, 36 typically developing (TD) children, and 23 unaffected siblings (SIBS). A conventional contrast-reversing checkerboard condition was compared to a novel short-duration condition, which was developed to enable objective data collection from severely affected populations who are often excluded from electroencephalographic (EEG) studies. Results Children with ASD showed significantly smaller amplitudes compared to TD children at two of the earliest critical VEP components, P60-N75 and N75-P100. SIBS showed intermediate responses relative to ASD and TD groups. There were no group differences in response latency. Frequency band analyses indicated significantly weaker responses for the ASD group in bands encompassing gamma-wave activity. Ninety-two percent of children with ASD were able to complete the short-duration condition compared to 68% for the standard condition. Conclusions The current study establishes the utility of a short-duration tVEP test for use in children at varying levels of functioning and describes neural abnormalities in children with idiopathic ASD. Implications for excitatory/inhibitory balance as well as the potential application of VEP for use in clinical trials are discussed. PMID:27716799

  15. Chaos and transient chaos in an experimental nonlinear pendulum

    Science.gov (United States)

    de Paula, Aline Souza; Savi, Marcelo Amorim; Pereira-Pinto, Francisco Heitor Iunes

    2006-06-01

    Pendulum is a mechanical device that instigates either technological or scientific studies, being associated with the measure of time, stabilization devices as well as ballistic applications. Nonlinear characteristic of the pendulum attracts a lot of attention being used to describe different phenomena related to oscillations, bifurcation and chaos. The main purpose of this contribution is the analysis of chaos in an experimental nonlinear pendulum. The pendulum consists of a disc with a lumped mass that is connected to a rotary motion sensor. This assembly is driven by a string-spring device that is attached to an electric motor and also provides torsional stiffness to the system. A magnetic device provides an adjustable dissipation of energy. This experimental apparatus is modeled and numerical simulations are carried out. Free and forced vibrations are analyzed showing that numerical results are in close agreement with those obtained from experimental data. This analysis shows that the experimental pendulum has a rich response, presenting periodic response, chaos and transient chaos.

  16. Adaptive filter based two-probe noise suppression system for transient evoked otoacoustic emission detection.

    Science.gov (United States)

    Subotić, Miško; Šarić, Zoran; Jovičić, Slobodan T

    2012-03-01

    Transient otoacoustic emission (TEOAE) is a method widely used in clinical practice for assessment of hearing quality. The main problem in TEOAE detection is its much lower level than the level of environmental and biological noise. While the environmental noise level can be controlled, the biological noise can be only reduced by appropriate signal processing. This paper presents a new two-probe preprocessing TEOAE system for suppression of the biological noise by adaptive filtering. The system records biological noises in both ears and applies a specific adaptive filtering approach for suppression of biological noise in the ear canal with TEOAE. The adaptive filtering approach includes robust sign error LMS algorithm, stimuli response summation according to the derived non-linear response (DNLR) technique, subtraction of the estimated TEOAE signal and residual noise suppression. The proposed TEOAE detection system is tested by three quality measures: signal-to-noise ratio (S/N), reproducibility of TEOAE, and measurement time. The maximal TEOAE detection improvement is dependent on the coherence function between biological noise in left and right ears. The experimental results show maximal improvement of 7 dB in S/N, improvement in reproducibility near 40% and reduction in duration of TEOAE measurement of over 30%.

  17. Transient, nonlinear rheology of reversible colloidal gels by dynamic simulation

    Science.gov (United States)

    Landrum, Benjamin; Russel, William; Zia, Roseanna

    2014-11-01

    We study the nonlinear rheology of reversible colloidal gels via dynamic simulation as they undergo age- and flow-induced structural evolution, with a view toward understanding and predicting transient behaviors such as multi-step and delayed yield. The gel is formed from 750,000 Brownian spheres interacting via hard-sphere repulsion and O(kT) short-range attraction, where thermal fluctuations are strong enough to allow continued structural rearrangement in the absence of flow. During startup of imposed strain rate, the transition to steady state is characterized by one or more ``overshoots'' in the stress which suggest initial yield, formation of a stronger gel, and subsequent yield of the new gel. When subjected to step-shear stress, the microstructure undergoes limited creep, followed by viscous flow. This macroscopic ``delayed flow'' is consistent with previously proposed models of competition between breakage and formation of particle bonds among static load-bearing structures. Our findings suggest, however, that the load-bearing structures evolve, and that the gel's resistance to delayed failure depends upon this structural evolution and reinforcement. We put forth a micro-mechanical model of stress gradient-driven particle transport that captures this macroscopic behavior.

  18. A nonlinear small-deformation theory for transient droplet electrohydrodynamics

    CERN Document Server

    Das, Debasish

    2016-01-01

    The deformation of a viscous liquid droplet suspended in another liquid and subject to an applied electric field is a classic multiphase flow problem best described by the Melcher-Taylor leaky dielectric model. The main assumption of the model is that any net charge in the system is concentrated on the interface between the two liquids as a result of the jump in Ohmic currents from the bulk. Upon application of the field, the drop can either attain a steady prolate or oblate shape with toroidal circulating flows both inside and outside arising from tangential stresses on the interface due to action of the field on the surface charge distribution. Since the pioneering work of \\cite{taylor1966}, there have been numerous computational and theoretical studies to predict the deformations measured in experiments. Most existing theoretical models, however, have either neglected transient charge relaxation or nonlinear charge convection by the interfacial flow. In this work, we develop a novel small-deformation theor...

  19. Imaging and analysis of evoked excitatory-postsynaptic-calcium-transients by individual presynaptic-boutons of cultured Aplysia sensorimotor synapse.

    Science.gov (United States)

    Malkinson, Guy; Spira, Micha E

    2010-04-01

    The use of the sensory-motor (SN-MN) synapse of the Aplysia gill withdrawal reflex has contributed immensely to the understanding of synaptic transmission, learning and memory acquisition processes. Whereas the majority of the studies focused on analysis of the presynaptic mechanisms, recent studies indicated that as in mammalian synapses, long term potentiation (LTP) formed by Aplysia SN-MN synapse depends on elevation of the postsynaptic free intracellular calcium concentration ([Ca2+](i)). Consistently, injection of the fast calcium chelator BAPTA to the MN prevents the formation of serotonin-induced LTP. Nevertheless, currently there are no published reports that directly examine and document whether evoked synaptic transmission is associated with transient increase in the postsynaptic [Ca2+](i). In the present study we imaged, for the first time, alterations in the postsynaptic [Ca2+](i) in response to presynaptic stimulation and analyzed the underlying mechanisms. Using live imaging of the postsynaptic [Ca2+](i) while monitoring the EPSP, we found that evoked transmitter release generates excitatory postsynaptic calcium concentration transients (EPSCaTs) by two mechanisms: (a) activation of DNQX-sensitive postsynaptic receptors-gated calcium influx and (b) calcium influx through nitrendipine-sensitive voltage-gated calcium channels (VGCCs). Concomitant confocal imaging of presynaptic boutons and EPSCaTs revealed that approximately 86% of the presynaptic boutons are associated with functional synapses.

  20. A Taylor-Galerkin finite element algorithm for transient nonlinear thermal-structural analysis

    Science.gov (United States)

    Thornton, E. A.; Dechaumphai, P.

    1986-01-01

    A Taylor-Galerkin finite element method for solving large, nonlinear thermal-structural problems is presented. The algorithm is formulated for coupled transient and uncoupled quasistatic thermal-structural problems. Vectorizing strategies ensure computational efficiency. Two applications demonstrate the validity of the approach for analyzing transient and quasistatic thermal-structural problems.

  1. Model for nonlinear transient burning of hydrazinium nitroformate

    NARCIS (Netherlands)

    Louwers, J.; Gadiot, G.M.H.J.L.

    1999-01-01

    Transient burning of solid propellants is a topic that still contains a large number of questions. The transient burning of neat hydrazinium nitroformate is calculated within the quasi-steady gas-phase, homogeneous one-dimensional condensed phase approach. We focus on the effect of the condensed pha

  2. [New method for analysis and visualization of the fine temporal structure of the transient evoked otoacoustic emission signal].

    Science.gov (United States)

    Belov, O A; Alekseeva, N N; Tavartkiladze, G A

    2014-01-01

    We have developed the new method for the analysis and visualization of the fine temporal structure of the transient evoked otoacoustic emission signal. The method consists of the presentation of the signal in the form of a set of tone components with a rapidly changing amplitude and relatively stable frequency. It is based on the combination of three spectrograms differing in frequency and temporal resolution by means of fuzzy logic amplitude estimation with subsequent frequency refining with the use of the least square procedure, reduction of the number of the insignificant components, and final re-ordering of the results for the simplification of further data processing. The new method was named Pitch Envelope Analysis (PEA). For data representation, a new type of diagram named componentogram was designed. The proposed method can be used for the real time processing of the continuous data stream especially for speech processing.

  3. Separating medial olivocochlear from acoustic reflex effects on transient evoked otoacoustic emissions in unanesthetized mice

    Science.gov (United States)

    Xu, Yingyue; Cheatham, Mary Ann; Siegel, Jonathan

    2015-12-01

    Descending neural pathways in the mammalian auditory system are believed to modulate the function of the peripheral auditory system [3, 8, 10]. These pathways include the medial olivocochlear (MOC) efferent innervation to the cochlear outer hair cells (OHCs) and the acoustic reflex pathways mediating middle ear muscle (MEM) contractions. The MOC effects can be monitored noninvasively using otoacoustic emissions (OAEs) [5, 6], which are acoustic byproducts of cochlear function [7]. In this study, we applied a sensitive method to determine when and to what degree contralateral MEM suppression contaminated MOC efferent effects on TEOAEs in unanesthetized mice. The lowest contralateral broadband noise evoking MEM contractions varied across animals. Examples of potential MOC-mediated TEOAE suppression with contralateral noise below MEM contraction thresholds were seen, but this behavior did not occur in the majority of cases.

  4. Fractal Dimension Analysis of Transient Visual Evoked Potentials: Optimisation and Applications

    Science.gov (United States)

    Boon, Mei Ying; Henry, Bruce Ian; Chu, Byoung Sun; Basahi, Nour; Suttle, Catherine May; Luu, Chi; Leung, Harry; Hing, Stephen

    2016-01-01

    Purpose The visual evoked potential (VEP) provides a time series signal response to an external visual stimulus at the location of the visual cortex. The major VEP signal components, peak latency and amplitude, may be affected by disease processes. Additionally, the VEP contains fine detailed and non-periodic structure, of presently unclear relevance to normal function, which may be quantified using the fractal dimension. The purpose of this study is to provide a systematic investigation of the key parameters in the measurement of the fractal dimension of VEPs, to develop an optimal analysis protocol for application. Methods VEP time series were mathematically transformed using delay time, τ, and embedding dimension, m, parameters. The fractal dimension of the transformed data was obtained from a scaling analysis based on straight line fits to the numbers of pairs of points with separation less than r versus log(r) in the transformed space. Optimal τ, m, and scaling analysis were obtained by comparing the consistency of results using different sampling frequencies. The optimised method was then piloted on samples of normal and abnormal VEPs. Results Consistent fractal dimension estimates were obtained using τ = 4 ms, designating the fractal dimension = D2 of the time series based on embedding dimension m = 7 (for 3606 Hz and 5000 Hz), m = 6 (for 1803 Hz) and m = 5 (for 1000Hz), and estimating D2 for each embedding dimension as the steepest slope of the linear scaling region in the plot of log(C(r)) vs log(r) provided the scaling region occurred within the middle third of the plot. Piloting revealed that fractal dimensions were higher from the sampled abnormal than normal achromatic VEPs in adults (p = 0.02). Variances of fractal dimension were higher from the abnormal than normal chromatic VEPs in children (p = 0.01). Conclusions A useful analysis protocol to assess the fractal dimension of transformed VEPs has been developed. PMID:27598422

  5. Stimulus-evoked calcium transients in somatosensory cortex are temporarily inhibited by a nearby microhemorrhage.

    Directory of Open Access Journals (Sweden)

    Flor A Cianchetti

    Full Text Available Although microhemorrhages are common in the brain of the elderly, the direct impact of these lesions on neural function remains unclear. In this work, we used femtosecond laser irradiation to rupture the wall of single arterioles in the brain of anesthetized rodents, producing a hematoma of ∼100-µm diameter. Our objective was to study the impact of these microhemorrhages on cortical activity using cell-resolved two-photon imaging of bulk-loaded calcium-sensitive dye. We monitored peripheral sensory stimulus-induced calcium transients from individual neuronal cell bodies, regions of neuropil, and astrocytes at different distances from the microhemorrhage before and 0.5, 2, and 4 hours after the creation of the lesion. We found that immediately after the hemorrhage the average amplitude of the stimulus-induced calcium response was reduced to about half within 150 µm from the hematoma. Beyond 300 µm, there was little effect on cell response, with a smooth increase in response amplitude from 150 µm to 300 µm from the lesion. Cortical function gradually improved with time and by four hours after the lesion the response from neurons and astrocytes had recovered to baseline everywhere but within 150 µm from the hematoma. To assess whether the cells closest to the microhemorrhage recovered over a longer timeframe, we developed a re-openable chronic cranial window preparation that allowed reinjection of calcium-sensitive fluorescent dye. We found that the response largely recovered by one day after the microhemorrhage even within 150 µm from the hematoma. This work suggests that neuronal and astrocyte function is transiently lost near a microhemorrhage, but recovers within one day after the lesion.

  6. TRANSIENT ANALYSIS OF NONUNIFORM TRANSMISSION LINES WITH NONLINEAR TERMINAL NETWORKS

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    A semi-analytical method in time domain is presented for analysis of the transient response of nonuniform transmission lines. In this method, the telegraph equations in time domain is differenced in space domain first, and is transformed into a set of first-order differential equations of voltage and current with respect to time. By integrating these differential equations with respect to time, and precise computation, the solution of these differential equations can be obtained. This method can solve the transient response of various kinds of transmission lines with arbitrary terminal networks. Particularly, it can analyze the nonuniform lines with initial conditions, for which there is no existing effective method to analyze the time response so far. The results obtained with this method are stable and accurate. Two examples are given to illustrate the application of this method.

  7. Introduction to the Explicit Finite Element Method for Nonlinear Transient Dynamics

    CERN Document Server

    Wu, Shen R

    2012-01-01

    A systematic introduction to the theories and formulations of the explicit finite element method As numerical technology continues to grow and evolve with industrial applications, understanding the explicit finite element method has become increasingly important, particularly in the areas of crashworthiness, metal forming, and impact engineering. Introduction to the Explicit FiniteElement Method for Nonlinear Transient Dynamics is the first book to address specifically what is now accepted as the most successful numerical tool for nonlinear transient dynamics. The book aids readers in master

  8. Equivalent circuit simulation of HPEM-induced transient responses at nonlinear loads

    Directory of Open Access Journals (Sweden)

    M. Kotzev

    2017-09-01

    Full Text Available In this paper the equivalent circuit modeling of a nonlinearly loaded loop antenna and its transient responses to HPEM field excitations are investigated. For the circuit modeling the general strategy to characterize the nonlinearly loaded antenna by a linear and a nonlinear circuit part is pursued. The linear circuit part can be determined by standard methods of antenna theory and numerical field computation. The modeling of the nonlinear circuit part requires realistic circuit models of the nonlinear loads that are given by Schottky diodes. Combining both parts, appropriate circuit models are obtained and analyzed by means of a standard SPICE circuit simulator. It is the main result that in this way full-wave simulation results can be reproduced. Furthermore it is clearly seen that the equivalent circuit modeling offers considerable advantages with respect to computation speed and also leads to improved physical insights regarding the coupling between HPEM field excitation and nonlinearly loaded loop antenna.

  9. Transient stability improvement by nonlinear controllers based on tracking

    Energy Technology Data Exchange (ETDEWEB)

    Ramirez, Juan M. [Centro de Investigacion y Estudios Avanzados, Guadalajara, Mexico. Av. Cientifica 1145. Col. El Bajio. Zapopan, Jal. 45015 (Mexico); Arroyave, Felipe Valencia; Correa Gutierrez, Rosa Elvira [Universidad Nacional de Colombia, Sede Medellin. Facultad de Minas, Escuela de Mecatronica (Colombia)

    2011-02-15

    This paper deals with the control problem in multi-machine electric power systems, which represent complex great scale nonlinear systems. Thus, the controller design is a challenging problem. These systems are subjected to different perturbations, such as short circuits, connection and/or disconnection of loads, lines, or generators. Then, the utilization of controllers which guarantee good performance under those perturbations is required in order to provide electrical energy to the loads with admissible stability margins. The proposed controllers are based on a systematic strategy, which calculate nonlinear controllers for generating units in a power plant, both for voltage and velocity regulation. The formulation allows designing controllers in a multi-machine power system without intricate calculations. Results on a power system of the open research indicate the proposition's suitability. The problem is formulated as a tracking problem. The designed controllers may be implemented in any electric power system. (author)

  10. Transient response of an active nonlinear sandwich piezolaminated plate

    Science.gov (United States)

    Oveisi, Atta; Nestorović, Tamara

    2017-04-01

    In this paper, the dynamic modelling and active vibration control of a piezolaminated plate with geometrical nonlinearities are investigated using a semi-analytical approach. For active vibration control purposes, the core orthotropic elastic layer is assumed to be perfectly bonded with two piezo-layers on its top and bottom surfaces which act as sensor and actuator, respectively. In the modelling procedure, the piezo-layers are assumed to be connected via a proportional derivative (PD) feedback control law. Hamilton's principle is employed to acquire the strong form of the dynamic equation in terms of additional higher order strain expressions by means of von Karman strain-displacement correlation. The obtained nonlinear partial differential equation (NPDE) is converted to a system of nonlinear ordinary differential equations (NODEs) by engaging Galerkin method and using the orthogonality of shape functions for the simply supported boundary conditions. Then, the resulting system of NODEs is solved numerically by employing the built-in Mathematica function, "NDSolve". Next, the vibration attenuation performance is evaluated and sensitivity of the closed-loop system is investigated for several control parameters and the external disturbance parameters. The proposed solution in open loop configuration is validated by finite element (FE) package ABAQUS both in the spatial domain and for the time-/frequency-dependent response.

  11. Calcium transient evoked by TRPV1 activators is enhanced by tumor necrosis factor-{alpha} in rat pulmonary sensory neurons.

    Science.gov (United States)

    Hu, Youmin; Gu, Qihai; Lin, Ruei-Lung; Kryscio, Richard; Lee, Lu-Yuan

    2010-10-01

    TNFα, a proinflammatory cytokine known to be involved in the pathogenesis of allergic asthma, has been shown to induce hyperalgesia in somatic tissue via a sensitizing effect on dorsal root ganglion neurons expressing transient receptor potential vanilloid type 1 receptor (TRPV1). Because TRPV1-expressing pulmonary sensory neurons play an important role in regulating airway function, this study was carried out to determine whether TNFα alters the sensitivity of these neurons to chemical activators. Responses of isolated nodose and jugular ganglion neurons innervating the rat lungs were determined by measuring the transient increase in intracellular Ca(2+) concentration ([Ca(2+)](i)). Our results showed the following. 1) A pretreatment with TNFα (50 ng/ml) for ∼24 h increased significantly the peak Δ[Ca(2+)](i) evoked by capsaicin (Cap) in these neurons. A pretreatment with the same concentration of TNFα for a longer duration (∼48 h) did not further increase the response, but pretreatment for a shorter duration (1 h) or with a lower concentration (25 ng/ml, 24 h) failed to enhance the Cap sensitivity. 2) The same TNFα pretreatment also induced similar but less pronounced and less uniform increases in the responses to acid (pH 6.5-5.5), 2-aminoethoxydiphenyl borate (2-APB), a common activator of TRPV1, V2, and V3 channels, and allyl isothiocyanate (AITC), a selective activator of TRPA1 channel. 3) In sharp contrast, the responses to ATP, ACh, and KCl were not affected by TNFα. 4) The TNFα-induced hypersensitivity to Cap was not prevented by pretreatment with indomethacin (30 μM). 5) The immunoreactivity to both TNF receptor types 1 and 2 were detected in rat vagal pulmonary sensory neurons. In conclusion, prolonged treatment with TNFα induces a pronounced potentiating effect on the responses of isolated pulmonary sensory neurons to TRPV1 activators. This action of TNFα may contribute in part to the airway hyperresponsiveness induced by this cytokine.

  12. The relationship between ultra-high frequency thresholds and transient evoked otoacoustic emissions in adults with tinnitus.

    Science.gov (United States)

    Omidvar, Shaghayegh; Jafari, Zahra; Mahmoudian, Saeid; Khabazkhoob, Mehdi; Ahadi, Mohsen; Yazdani, Nasrin

    2016-01-01

    Background: The possible role of cochlear function in tinnitus generation is still a matter of debate. To assess the role of outer hair cell dysfunction in tinnitus and its possible relationship with ultra-high frequency (UHF) hearing sensitivity, transient evoked otoacoustic emissions (TEOAE) and UHF hearing thresholds were investigated in normal hearing individuals with and without tinnitus. Methods: Eighteen individuals with tinnitus and 22 without tinnitus participated in this study. TEOAE was recorded with click stimulus at 80 dBpeSPL. UHF pure tone audiometry was performed at 10, 12.5, 16, and 18 kHz. Results: TEOAE was significantly abnormal in 72.2% of the tinnitus, and 18.2% of the control groups (p=0.001). The individuals with tinnitus had significantly poorer UHF hearing sensitivity compared to the control group at 12.5 and 18 kHz (p≤0.048). There was a stronger correlation between increasing UHFs hearing threshold and decreasing SNRs of TEOAEs in the tinnitus group compared to the controls. Conclusion: Our study revealed poorer UHF hearing thresholds and more TEOAE abnormalities in normal hearing individuals with tinnitus compared to the controls. Perhaps the alterations in the basal cochlea, following a decrease in UHF hearing sensitivity, affect OAEs that are originated from more apical cochlear parts in tinnitus ears more than non-tinnitus ears.

  13. The relationship between ultra-high frequency thresholds and transient evoked otoacoustic emissions in adults with tinnitus

    Science.gov (United States)

    Omidvar, Shaghayegh; Jafari, Zahra; Mahmoudian, Saeid; Khabazkhoob, Mehdi; Ahadi, Mohsen; Yazdani, Nasrin

    2016-01-01

    Background: The possible role of cochlear function in tinnitus generation is still a matter of debate. To assess the role of outer hair cell dysfunction in tinnitus and its possible relationship with ultra-high frequency (UHF) hearing sensitivity, transient evoked otoacoustic emissions (TEOAE) and UHF hearing thresholds were investigated in normal hearing individuals with and without tinnitus. Methods: Eighteen individuals with tinnitus and 22 without tinnitus participated in this study. TEOAE was recorded with click stimulus at 80 dBpeSPL. UHF pure tone audiometry was performed at 10, 12.5, 16, and 18 kHz. Results: TEOAE was significantly abnormal in 72.2% of the tinnitus, and 18.2% of the control groups (p=0.001). The individuals with tinnitus had significantly poorer UHF hearing sensitivity compared to the control group at 12.5 and 18 kHz (p≤0.048). There was a stronger correlation between increasing UHFs hearing threshold and decreasing SNRs of TEOAEs in the tinnitus group compared to the controls. Conclusion: Our study revealed poorer UHF hearing thresholds and more TEOAE abnormalities in normal hearing individuals with tinnitus compared to the controls. Perhaps the alterations in the basal cochlea, following a decrease in UHF hearing sensitivity, affect OAEs that are originated from more apical cochlear parts in tinnitus ears more than non-tinnitus ears. PMID:28210614

  14. Transient and Steady-State Responses of an Asymmetric Nonlinear Oscillator

    Directory of Open Access Journals (Sweden)

    Alex Elías-Zúñiga

    2013-01-01

    oscillator that describes the motion of a damped, forced system supported symmetrically by simple shear springs on a smooth inclined bearing surface. We also use the percentage overshoot value to study the influence of damping and nonlinearity on the transient and steady-state oscillatory amplitudes.

  15. Nonlinear explicit transient finite element analysis on the Intel Delta

    Energy Technology Data Exchange (ETDEWEB)

    Plaskacz, E.J. [Argonne National Lab., IL (United States); Ramirez, M.R.; Gupta, S. [Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Civil Engineering

    1993-03-01

    Many large scale finite element problems are intractable on current generation production supercomputers. High-performance computer architectures offer effective avenues to bridge the gap between computational needs and the power of computational hardware. The biggest challenge lies in the substitution of the key algorithms in an application program with redesigned algorithms which exploit the new architectures and use better or more appropriate numerical techniques. A methodology for implementing nonlinear finite element analysis on a homogeneous distributed processing network is discussed. The method can also be extended to heterogeneous networks comprised of different machine architectures provided that they have a mutual communication interface. This unique feature has greatly facilitated the port of the code to the 8-node Intel Touchstone Gamma and then the 512-node Intel Touchstone Delta. The domain is decomposed serially in a preprocessor. Separate input files are written for each subdomain. These files are read in by local copies of the program executable operating in parallel. Communication between processors is addressed utilizing asynchronous and synchronous message passing. The basic kernel of message passing is the internal force exchange which is analogous to the computed interactions between sections of physical bodies in static stress analysis. Benchmarks for the Intel Delta are presented. Performance exceeding 1 gigaflop was attained. Results for two large-scale finite element meshes are presented.

  16. Nonlinear explicit transient finite element analysis on the Intel Delta

    Energy Technology Data Exchange (ETDEWEB)

    Plaskacz, E.J. (Argonne National Lab., IL (United States)); Ramirez, M.R.; Gupta, S. (Johns Hopkins Univ., Baltimore, MD (United States). Dept. of Civil Engineering)

    1993-01-01

    Many large scale finite element problems are intractable on current generation production supercomputers. High-performance computer architectures offer effective avenues to bridge the gap between computational needs and the power of computational hardware. The biggest challenge lies in the substitution of the key algorithms in an application program with redesigned algorithms which exploit the new architectures and use better or more appropriate numerical techniques. A methodology for implementing nonlinear finite element analysis on a homogeneous distributed processing network is discussed. The method can also be extended to heterogeneous networks comprised of different machine architectures provided that they have a mutual communication interface. This unique feature has greatly facilitated the port of the code to the 8-node Intel Touchstone Gamma and then the 512-node Intel Touchstone Delta. The domain is decomposed serially in a preprocessor. Separate input files are written for each subdomain. These files are read in by local copies of the program executable operating in parallel. Communication between processors is addressed utilizing asynchronous and synchronous message passing. The basic kernel of message passing is the internal force exchange which is analogous to the computed interactions between sections of physical bodies in static stress analysis. Benchmarks for the Intel Delta are presented. Performance exceeding 1 gigaflop was attained. Results for two large-scale finite element meshes are presented.

  17. Transient evoked oto-acoustic emission screening in newborns in Bogotá, Colombia: a retrospective study.

    Science.gov (United States)

    Rojas, Jorge A; Bernal, Jaime E; García, Mary A; Zarante, Ignacio; Ramírez, Natalia; Bernal, Constanza; Gelvez, Nancy; Tamayo, Marta L

    2014-10-01

    The aim of this study was to investigate the characteristics and performance of transient evoked oto-acoustic emission (TEOAE) hearing screening in newborns in Colombia, and analyze all possible variables and factors affecting the results. An observational, descriptive and retrospective study with bivariate analysis was performed. The study population consisted of 56,822 newborns evaluated at the private institution, PREGEN. TEOAE testing was carried out as a pediatric hearing screening test from December 2003 to March 2012. The database from PREGEN was revised, and the protocol for evaluation included the same screening test performed twice. Demographic characteristics were recorded and the newborn's background was evaluated. Basic statistics of the qualitative and quantitative variables, and statistical analysis were obtained using the chi-square test. Of the 56,822 records examined, 0.28% were classed as abnormal, which corresponded to a prevalence of 1 in 350. In the screened newborns, 0.08% had a major abnormality or other clinical condition diagnosed, and 0.29% reported a family history of hearing loss. A prevalence of 6.7 in 10,000 was obtained for microtia, which is similar to the 6.4 in 10,000 previously reported in Colombia (database of the Latin-American Collaborative Study of Congenital Malformations - ECLAMC). Statistical analysis demonstrated an association between presenting with a major anomaly and a higher frequency of abnormal results on both TEOAE tests. Newborns in Colombia do not currently undergo screening for the early detection of hearing impairment. The results from this study suggest TEOAE screening tests, when performed twice, are able to detect hearing abnormalities in newborns. This highlights the need to improve the long-term evaluation and monitoring of patients in Colombia through diagnostic tests, and to provide tests that are both sensitive and specific. Furthermore, the use of TEOAE screening is justified by the favorable cost

  18. Homogeneous shear turbulence - bypass concept via interplay of linear transient growth and nonlinear transverse cascade

    Science.gov (United States)

    Mamatsashvili, George; Dong, Siwei; Khujadze, George; Chagelishvili, George; Jiménez, Javier; Foysi, Holger

    2016-04-01

    We performed direct numerical simulations of homogeneous shear turbulence to study the mechanism of the self-sustenance of subcritical turbulence in spectrally stable (constant) shear flows. For this purpose, we analyzed the turbulence dynamics in Fourier/wavenumber/spectral space based on the simulation data for the domain aspect ratio 1 : 1 : 1. Specifically, we examined the interplay of linear transient growth of Fourier harmonics and nonlinear processes. The transient growth of harmonics is strongly anisotropic in spectral space. This, in turn, leads to anisotropy of nonlinear processes in spectral space and, as a result, the main nonlinear process appears to be not a direct/inverse, but rather a transverse/angular redistribution of harmonics in Fourier space referred to as the nonlinear transverse cascade. It is demonstrated that the turbulence is sustained by the interplay of the linear transient, or nonmodal growth and the transverse cascade. This course of events reliably exemplifies the wellknown bypass scenario of subcritical turbulence in spectrally stable shear flows. These processes mainly operate at large length scales, comparable to the box size. Consequently, the central, small wavenumber area of Fourier space (the size of which is determined below) is crucial in the self-sustenance and is labeled the vital area. Outside the vital area, the transient growth and the transverse cascade are of secondary importance - Fourier harmonics are transferred to dissipative scales by the nonlinear direct cascade. The number of harmonics actively participating in the self-sustaining process (i.e., the harmonics whose energies grow more than 10% of the maximum spectral energy at least once during evolution) is quite large - it is equal to 36 for the considered box aspect ratio - and obviously cannot be described by low-order models.

  19. Finite element analysis of steady and transiently moving/rolling nonlinear viscoelastic structure. I - Theory

    Science.gov (United States)

    Padovan, Joe

    1987-01-01

    In a three-part series of papers, a generalized finite element analysis scheme is developed to handle the steady and transient response of moving/rolling nonlinear viscoelastic structure. This paper considers the development of the moving/rolling element strategy, including the effects of large deformation kinematics and viscoelasticity modeled by fractional integrodifferential operators. To improve the solution strategy, a special hierarchical constraint procedure is developed for the case of steady rolling/translating, as well as a transient scheme involving the use of a Grunwaldian representation of the fractional operator.

  20. High-Accuracy Pneumatic Position Control by Applying Nonlinear Control and Arranging Transient Process

    Institute of Scientific and Technical Information of China (English)

    WANG Yan-bo; BAO Gang

    2008-01-01

    By applying a nonlinear control and arranging a transient process, the initiative error of the pneumatic servo positioning system is reduced largely, and a larger gain of the controller is used to improve the responding speed of the system at the same damping ratio. Therefore, a compromise is made among the responding speed, overshoot, robustness, adaptability and stability. In addition, a dynamic output feedback controller, including position velocity and acceleration (PVA) feedback, is designed to improve the performance of the system. And a nonlinear controller is reconstructed based on the linear output feedback controller to decrease noises and disturbances. The dynamic responses of the system are simulated and tested. Results show that the error is kept within 0.02 mm under different mass loads and the positioning transient process is smooth, without overshoot and speedy.

  1. Optical nonlinearity of organic dyes as studied by Z-scan and transient grating techniques

    Indian Academy of Sciences (India)

    Umakanta Tripathy; R Justin Rajesh; Prem B Bisht; A Subrahamanyam

    2002-12-01

    The excited state absorption cross-section of 5,5′-dichloro-11-diphenylamino- 3,3′-diethyl-10,12-ethylinethiatricarbocyanine perchlorate (IR140) have been measured by using a single beam transmission technique. Z-scan experiments have been used to find out a few nonlinear parameters. The excited state relaxation times have also been measured by using laser induced transient grating (LITG) technique.

  2. Non-linear and transient absorption spectroscopy of magnesium(II)-tetrabenzoporphyrin in solution

    Science.gov (United States)

    Stiel, H.; Volkmer, A.; Rückmann, I.; Zeug, A.; Ehrenberg, B.; Röder, B.

    1998-10-01

    The excited state properties of magnesium(II)-tetrabenzoporphyrin (Mg-TBP) were studied by using intensity dependent transmission (non-linear absorption), ps-transient absorption and time resolved luminescence spectroscopy. It was found that there is a strong excited absorption in the region around 500 nm. Because there is no or little ground state absorption in this region the dye is suitable as an optical limiter.

  3. Finite element analysis of steady and transiently moving/rolling nonlinear viscoelastic structure. Part 1: Theory

    Science.gov (United States)

    Padovan, Joe

    1986-01-01

    In a three part series of papers, a generalized finite element analysis scheme is developed to handle the steady and transient response of moving/rolling nonlinear viscoelastic structure. This paper considers the development of the moving/rolling element strategy, including the effects of large deformation kinematics and viscoelasticity modelled by fractional integro-differential operators. To improve the solution strategy, a special hierarchical constraint procedure is developed for the case of steady rolling/translating as well as a transient scheme involving the use of a Grunwaldian representation of the fractional operator. In the second and third parts of the paper, 3-D extensions are developed along with transient contact strategies enabling the handling of impacts with obstructions. Overall, the various developments are benchmarked via comprehensive 2- and 3-D simulations. These are correlated with experimental data to define modelling capabilities.

  4. Modeling human auditory evoked brainstem responses based on nonlinear cochlear processing

    DEFF Research Database (Denmark)

    Harte, James; Rønne, Filip Munch; Dau, Torsten

    2010-01-01

    (ABR) to transient sounds and frequency following responses (FFR) to tones. The model includes important cochlear processing stages (Zilany and Bruce, 2006) such as basilar-membrane (BM) tuning and compression, inner hair-cell (IHC) transduction, and IHC auditory-nerve (AN) synapse adaptation...

  5. Pseudo-transient Continuation Based Variable Relaxation Solve in Nonlinear Magnetohydrodynamic Simulations

    Energy Technology Data Exchange (ETDEWEB)

    Jin Chen

    2009-12-07

    Efficient and robust Variable Relaxation Solver, based on pseudo-transient continuation, is developed to solve nonlinear anisotropic thermal conduction arising from fusion plasma simulations. By adding first and/or second order artificial time derivatives to the system, this type of method advances the resulting time-dependent nonlinear PDEs to steady state, which is the solution to be sought. In this process, only the stiffness matrix itself is involved so that the numerical complexity and errors can be greatly reduced. In fact, this work is an extension of integrating efficient linear elliptic solvers for fusion simulation on Cray XIE. Two schemes are derived in this work, first and second order Variable Relaxations. Four factors are observed to be critical for efficiency and preservation of solution's symmetric structure arising from periodic boundary condition: refining meshes in different coordinate directions, initializing nonlinear process, varying time steps in both temporal and spatial directions, and accurately generating nonlinear stiffness matrix. First finer mesh scale should be taken in strong transport direction; Next the system is carefully initialized by the solution with linear conductivity; Third, time step and relaxation factor are vertex-based varied and optimized at each time step; Finally, the nonlinear stiffness matrix is updated by just scaling corresponding linear one with the vector generated from nonlinear thermal conductivity.

  6. On high-continuity transfinite element formulations for linear-nonlinear transient thermal problems

    Science.gov (United States)

    Tamma, Kumar K.; Railkar, Sudhir B.

    1987-01-01

    This paper describes recent developments in the applicability of a hybrid transfinite element methodology with emphasis on high-continuity formulations for linear/nonlinear transient thermal problems. The proposed concepts furnish accurate temperature distributions and temperature gradients making use of a relatively smaller number of degrees of freedom; and the methodology is applicable to linear/nonlinear thermal problems. Characteristic features of the formulations are described in technical detail as the proposed hybrid approach combines the major advantages and modeling features of high-continuity thermal finite elements in conjunction with transform methods and classical Galerkin schemes. Several numerical test problems are evaluated and the results obtained validate the proposed concepts for linear/nonlinear thermal problems.

  7. Transient photoconductivity and femtosecond nonlinear optical properties of a conjugated polymer-graphene oxide composite

    Energy Technology Data Exchange (ETDEWEB)

    Nalla, Venkatram; Ji Wei [Department of Physics, National University of Singapore, Singapore 117542 (Singapore); Polavarapu, Lakshminarayana; Manga, Kiran Kumar; Goh, Bee Min; Loh, Kian Ping; Xu Qinghua, E-mail: chmxqh@nus.edu.sg, E-mail: phyjiwei@nus.edu.sg [Department of Chemistry, National University of Singapore, Singapore 117543 (Singapore)

    2010-10-15

    A water soluble conjugated thiophene polymer, sodium salt of poly[2-(3-thienyl)ethoxy-4-butylsulfonate] (TPP), and graphene oxide (GO) composite film (GO-TPP) device was prepared. Transient photoconductivity measurements were carried out on the GO-TPP composite film using 150 ns laser pulses of 527 nm wavelength. Highly efficient photocurrent generation was observed from the GO-TPP film. The relationships of the film photoconductivity, photocurrent decay time and electron decay times with the incident light intensity were investigated. The photoconductive gain of the film was determined to be greater than 40% and to be independent of the light intensity. Furthermore, the femtosecond nonlinear optical properties of the GO-TPP film were measured using 800 nm femtosecond laser pulses and the composite film exhibited high nonlinear absorption and nonlinear refraction coefficients.

  8. Transient Vibration Prediction for Rotors on Ball Bearings Using Load-dependent Non-linear Bearing Stiffness

    Science.gov (United States)

    Fleming, David P.; Poplawski, J. V.

    2002-01-01

    Rolling-element bearing forces vary nonlinearly with bearing deflection. Thus an accurate rotordynamic transient analysis requires bearing forces to be determined at each step of the transient solution. Analyses have been carried out to show the effect of accurate bearing transient forces (accounting for non-linear speed and load dependent bearing stiffness) as compared to conventional use of average rolling-element bearing stiffness. Bearing forces were calculated by COBRA-AHS (Computer Optimized Ball and Roller Bearing Analysis - Advanced High Speed) and supplied to the rotordynamics code ARDS (Analysis of Rotor Dynamic Systems) for accurate simulation of rotor transient behavior. COBRA-AHS is a fast-running 5 degree-of-freedom computer code able to calculate high speed rolling-element bearing load-displacement data for radial and angular contact ball bearings and also for cylindrical and tapered roller beatings. Results show that use of nonlinear bearing characteristics is essential for accurate prediction of rotordynamic behavior.

  9. Modeling of Propagation and Transformation of Transient Nonlinear Waves on A Current

    Institute of Scientific and Technical Information of China (English)

    Wojciech Sulisz; Maciej Paprota

    2013-01-01

    A novel theoretical approach is applied to predict the propagation and transformation of transient nonlinear waves on a current. The problem was solved by applying an eigenfunction expansion method and the derived semi-analytical solution was employed to study the transformation of wave profile and the evolution of wave spectrum arising from the nonlinear interactions of wave components in a wave train which may lead to the formation of very large waves. The results show that the propagation of wave trains is significantly affected by a current. A relatively small current may substantially affect wave train components and the wave train shape. This is observed for both opposing and following current. The results demonstrate that the application of the nonlinear model has a substantial effect on the shape of a wave spectrum. A train of originally linear and very narrow-banded waves changes its one-peak spectrum to a multi-peak one in a fairly short distance from an initial position. The discrepancies between the wave trains predicted by applying the linear and nonlinear models increase with the increasing wavelength and become significant in shallow water even for waves with low steepness. Laboratory experiments were conducted in a wave flume to verify theoretical results. The free-surface elevations recorded by a system of wave gauges are compared with the results provided by the nonlinear model. Additional verification was achieved by applying a Fourier analysis and comparing wave amplitude spectra obtained from theoretical results with experimental data. A reasonable agreement between theoretical results and experimental data is observed for both amplitudes and phases. The model predicts fairly well multi-peak spectra, including wave spectra with significant nonlinear wave components.

  10. NONLINEAR TRANSIENT RESPONSE OF STAY CABLE WITH VISCOELASTICITY DAMPER IN CABLE-STAYED BRIDGE

    Institute of Scientific and Technical Information of China (English)

    陈水生; 孙炳楠; 冯义卿

    2004-01-01

    Taking the bending stiffness,static sag,and geometric non-linearity into consideration,the space nonlinear vibration partial differential equations were derived.The partical differential equations were discretized in space by finite center difference approximation,then the nonlinear ordinal differential equations were obtained.A hybrid method involving the combination of the Newmark method and the pseudo-force strategy was proposed to analyze the nonlinear transient response of the inclined cable-dampers system subjected to arbitrary dynamic loading.As an example,two typical stay cables were calculated by the present method.The results reveal both the validity and the deficiency of the viscoelasticity damper for vibration control of stay cables.The efficiency and accuracy of the proposed method is also verified by comparing the results with those obtained by using Runge-Kutta direct integration technique.A new time history analysis method is provided for the research on the stay cable vibration control.

  11. Evoked response denoising using nonlinear diffusion filtering of single-trial matrix representations.

    Science.gov (United States)

    Mustaffa, Izadora; Trenado, Carlos; Schwerdtfeger, Karsten; Strauss, Daniel J

    2008-01-01

    Recent progress in mathematical image processing shows a remarkable success when applying numerical methods to ill-posed partial differential equations (PDE). In particular, nonlinear diffusion filtering (NDF)process is an approach that belongs to such family of differential equations. It has been successfully applied in many recent methods for image processing and computer vision areas, particularly in denoising, smoothing, segmentation, and restoration. In this paper we focus on a novel NDF application, namely denoising of single-trials of auditory brainstem responses (ABRs) and the analysis of transcranial magnetic stimulation (TMS) responses.We show that by applying NDF on a matrix-form image of single-trials, we were able to denoise the single-trials, resulting in a better extraction of information over the ongoing experiment; morphology, eg. the latency of the single-trials according to different stimuli paradigms at different stimulation intensity levels. It is concluded that NDF represents a novel and useful approach for the analysis of single-trials in brain imaging.

  12. Polaronic quasiparticle picture for generation dynamics of coherent phonons in semiconductors: Transient and nonlinear Fano resonance

    Science.gov (United States)

    Watanabe, Yohei; Hino, Ken-ichi; Hase, Muneaki; Maeshima, Nobuya

    2017-01-01

    We examine generation dynamics of coherent phonons in both polar and nonpolar semiconductors, such as GaAs and Si, based on a polaronic-quasiparticle (PQ) model. In this model, the PQ operator is composed of two kinds of operators: one is a quasiboson operator, defined as a linear combination of a set of pairs of electron operators, and the other is a longitudinal optical (LO) phonon operator. In particular, the problem of transient and nonlinear Fano resonance (FR) is tackled, where the vestige of this quantum interference effect was observed exclusively in lightly n -doped Si immediately after carriers were excited by an ultrashort pulse laser [M. Hase et al., Nature (London) 426, 51 (2003), 10.1038/nature02044], although not observed yet in GaAs. The PQ model enables us to show straightforwardly that the phonon energy state is embedded in continuum states formed by a set of adiabatic eigenstates of the quasiboson; this energy configuration is a necessary condition of the manifestation of the transient FR in the present optically nonlinear system. Numerical calculations are done for photoemission spectra relevant to the retarded longitudinal dielectric function of transient photoexcited states and for power spectra relevant to the LO-phonon displacement function of time. The photoemission spectra show that in undoped Si, an asymmetric spectral profile characteristic of FR comes into existence immediately after the instantaneous carrier excitation to fade out gradually, whereas in undoped GaAs, no asymmetry in spectra appears in the whole temporal region. The similar results are also obtained in the power spectra. These results are in harmony with the reported experimental results. It is found that the obtained difference in spectral profile between undoped Si and GaAs is attributed to a phase factor of an effective interaction between the LO phonon and the quasiboson. More detailed discussion of the FR dynamics is made in the text.

  13. Selective potentiation of (α4)3(β2)2 nicotinic acetylcholine receptors augments amplitudes of prefrontal acetylcholine- and nicotine-evoked glutamatergic transients in rats.

    Science.gov (United States)

    Grupe, Morten; Paolone, Giovanna; Jensen, Anders A; Sandager-Nielsen, Karin; Sarter, Martin; Grunnet, Morten

    2013-11-15

    Prefrontal glutamate release evoked through activation of α4β2* nicotinic acetylcholine receptors (nAChRs) situated on thalamic glutamatergic afferents mediates cue detection processes and thus contributes to attentional performance. However, little is known about the respective contributions of the high sensitivity and low sensitivity (LS) stoichiometries of the α4β2 nAChR, (α4)2(β2)3 and (α4)3(β2)2, to these processes. In the present study we employed glutamate-sensitive microelectrodes and the (α4)3(β2)2-selective positive allosteric modulator (PAM) NS9283 to investigate the importance of the LS α4β2 nAChR for glutamate release in the rat medial prefrontal cortex (mPFC). Firstly, the signaling evoked by physiologically relevant ACh concentrations through the (α4)3(β2)2 nAChR in HEK293 cells was potentiated by NS9283, consistent with the classification of NS9283 as a PAM. In urethane-anesthetized rats, intra-prefrontal pressure ejections of NS9283 evoked glutamatergic transients. Importantly, this glutamate release was attenuated by removal of cholinergic projections to the recording area. This finding indicates that the effects of NS9283 depend on endogenous ACh, again consistent with effects of a PAM. We then conducted microdialysis to demonstrate the presence of extracellular ACh in urethane-anesthetized control rats. While detectable, those levels were significantly lower than in awake rats. Finally, the amplitudes of glutamatergic transients evoked by local pressure ejections of a low concentration of nicotine were significantly augmented following systemic administration of NS9283 (3.0mg/kg). In conclusion, our results indicate that a LS α4β2 nAChR PAM such as NS9283 may enhance the cholinergic modulation of glutamatergic neurotransmission in the cortex, thereby perhaps alleviating the attentional impairments common to a range of brain disorders. Copyright © 2013 Elsevier Inc. All rights reserved.

  14. Nonlinear modeling and dynamic analysis of a hydro-turbine governing system in the process of sudden load increase transient

    Science.gov (United States)

    Li, Huanhuan; Chen, Diyi; Zhang, Hao; Wang, Feifei; Ba, Duoduo

    2016-12-01

    In order to study the nonlinear dynamic behaviors of a hydro-turbine governing system in the process of sudden load increase transient, we establish a novel nonlinear dynamic model of the hydro-turbine governing system which considers the elastic water-hammer model of the penstock and the second-order model of the generator. The six nonlinear dynamic transfer coefficients of the hydro-turbine are innovatively proposed by utilizing internal characteristics and analyzing the change laws of the characteristic parameters of the hydro-turbine governing system. Moreover, from the point of view of engineering, the nonlinear dynamic behaviors of the above system are exhaustively investigated based on bifurcation diagrams and time waveforms. More importantly, all of the above analyses supply theoretical basis for allowing a hydropower station to maintain a stable operation in the process of sudden load increase transient.

  15. Minimal seeds for shear flow turbulence: using nonlinear transient growth to touch the edge of chaos

    CERN Document Server

    Pringle, Chris C T; Kerswell, Rich R

    2011-01-01

    We propose a general strategy for determining the minimal finite amplitude isturbance to trigger transition to turbulence in shear flows. This involves constructing a variational problem that searches over all disturbances of fixed initial amplitude, which respect the boundary conditions, incompressibility and the Navier--Stokes equations, to maximise a chosen functional over an asymptotically long time period. The functional must be selected such that it identifies turbulent velocity fields by taking significantly enhanced values compared to those for laminar fields. We illustrate this approach using the ratio of the final to initial perturbation kinetic energies (energy growth) as the functional and the energy norm to measure amplitudes in the context of pipe flow. Our results indicate that the variational problem yields a smooth converged solution providing the amplitude is below the threshold amplitude for transition. This optimal is the nonlinear analogue of the well-studied (linear) transient growth opt...

  16. Transient and Steady-State Analysis of Nonlinear RF and Microwave Circuits

    Directory of Open Access Journals (Sweden)

    Zhu Lei(Lana

    2006-01-01

    Full Text Available This paper offers a review of simulation methods currently available for the transient and steady-state analysis of nonlinear RF and microwave circuits. The most general method continues to be the time-marching approach used in Spice, but more recent methods based on multiple time dimensions are particularly effective for RF and microwave circuits. We derive nodal formulations for the most widely used multiple time dimension methods. We put special emphasis on methods for the analysis of oscillators based in the warped multitime partial differential equations (WaMPDE approach. Case studies of a Colpitts oscillator and a voltage controlled Clapp-Gouriet oscillator are presented and discussed. The accuracy of the amplitude and phase of these methods is investigated. It is shown that the exploitation of frequency-domain latency reduces the computational effort.

  17. Transient evolution of a photon gas in the nonlinear QED vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Wu, S Q; Hartemann, F V

    2011-10-04

    Thermally induced vacuum polarization stemming from QED radiative corrections to the electromagnetic field equations is studied. The physical behavior of thermal radiation, in the nonlinear QED vacuum first described by Heisenberg and Euler, is a problem of some theoretical importance in view of its relation to the cosmic microwave background (CMB), early universe evolution, and Hawking-Unruh radiation. The questions of evolution toward equilibrium, stability, and invariance of thermal radiation under such conditions are of great interest. Our analysis presents novel aspects associated with photon-photon scattering in a photon gas in the framework of quantum kinetic theory. Within the context of the Euler-Heisenberg theory, we show that a homogeneous, isotropic photon gas with arbitrary spectral distribution function evolves toward an equilibrium state with a Bose-Einstein distribution. The transient evolution toward equilibrium of a gas of photons undergoing photon-photon scattering is studied in detail via the Boltzmann transport equation.

  18. Nonlinear Transient Dynamics of Photoexcited Silicon Nanoantenna for Ultrafast All-Optical Signal Processing

    CERN Document Server

    Baranov, Denis G; Milichko, Valentin A; Kudryashov, Sergey I; Krasnok, Alexander E; Belov, Pavel A

    2016-01-01

    Optically generated electron-hole plasma in high-index dielectric nanostructures was demonstrated as a means of tuning of their optical properties. However, until now an ultrafast operation regime of such plasma driven nanostructures has not been attained. Here, we perform pump-probe experiments with resonant silicon nanoparticles and report on dense optical plasma generation near the magnetic dipole resonance with ultrafast (about 2.5 ps) relaxation rate. Basing on experimental results, we develop an analytical model describing transient response of a nanocrystalline silicon nanoparticle to an intense laser pulse and show theoretically that plasma induced optical nonlinearity leads to ultrafast reconfiguration of the scattering power pattern. We demonstrate 100 fs switching to unidirectional scattering regime upon irradiation of the nanoparticle by an intense femtosecond pulse. Our work lays the foundation for developing ultracompact and ultrafast all-optical signal processing devices.

  19. An implicit meshless scheme for the solution of transient non-linear Poisson-type equations

    KAUST Repository

    Bourantas, Georgios

    2013-07-01

    A meshfree point collocation method is used for the numerical simulation of both transient and steady state non-linear Poisson-type partial differential equations. Particular emphasis is placed on the application of the linearization method with special attention to the lagging of coefficients method and the Newton linearization method. The localized form of the Moving Least Squares (MLS) approximation is employed for the construction of the shape functions, in conjunction with the general framework of the point collocation method. Computations are performed for regular nodal distributions, stressing the positivity conditions that make the resulting system stable and convergent. The accuracy and the stability of the proposed scheme are demonstrated through representative and well-established benchmark problems. © 2013 Elsevier Ltd.

  20. Transient Receptor Potential Vanilloid 4 Ion Channel Functions as a Pruriceptor in Epidermal Keratinocytes to Evoke Histaminergic Itch.

    Science.gov (United States)

    Chen, Yong; Fang, Quan; Wang, Zilong; Zhang, Jennifer Y; MacLeod, Amanda S; Hall, Russell P; Liedtke, Wolfgang B

    2016-05-06

    TRPV4 ion channels function in epidermal keratinocytes and in innervating sensory neurons; however, the contribution of the channel in either cell to neurosensory function remains to be elucidated. We recently reported TRPV4 as a critical component of the keratinocyte machinery that responds to ultraviolet B (UVB) and functions critically to convert the keratinocyte into a pain-generator cell after excess UVB exposure. One key mechanism in keratinocytes was increased expression and secretion of endothelin-1, which is also a known pruritogen. Here we address the question of whether TRPV4 in skin keratinocytes functions in itch, as a particular form of "forefront" signaling in non-neural cells. Our results support this novel concept based on attenuated scratching behavior in response to histaminergic (histamine, compound 48/80, endothelin-1), not non-histaminergic (chloroquine) pruritogens in Trpv4 keratinocyte-specific and inducible knock-out mice. We demonstrate that keratinocytes rely on TRPV4 for calcium influx in response to histaminergic pruritogens. TRPV4 activation in keratinocytes evokes phosphorylation of mitogen-activated protein kinase, ERK, for histaminergic pruritogens. This finding is relevant because we observed robust anti-pruritic effects with topical applications of selective inhibitors for TRPV4 and also for MEK, the kinase upstream of ERK, suggesting that calcium influx via TRPV4 in keratinocytes leads to ERK-phosphorylation, which in turn rapidly converts the keratinocyte into an organismal itch-generator cell. In support of this concept we found that scratching behavior, evoked by direct intradermal activation of TRPV4, was critically dependent on TRPV4 expression in keratinocytes. Thus, TRPV4 functions as a pruriceptor-TRP in skin keratinocytes in histaminergic itch, a novel basic concept with translational-medical relevance. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  1. Transient Receptor Potential Vanilloid 4 Ion Channel Functions as a Pruriceptor in Epidermal Keratinocytes to Evoke Histaminergic Itch*

    Science.gov (United States)

    Chen, Yong; Fang, Quan; Wang, Zilong; Zhang, Jennifer Y.; MacLeod, Amanda S.; Hall, Russell P.; Liedtke, Wolfgang B.

    2016-01-01

    TRPV4 ion channels function in epidermal keratinocytes and in innervating sensory neurons; however, the contribution of the channel in either cell to neurosensory function remains to be elucidated. We recently reported TRPV4 as a critical component of the keratinocyte machinery that responds to ultraviolet B (UVB) and functions critically to convert the keratinocyte into a pain-generator cell after excess UVB exposure. One key mechanism in keratinocytes was increased expression and secretion of endothelin-1, which is also a known pruritogen. Here we address the question of whether TRPV4 in skin keratinocytes functions in itch, as a particular form of “forefront” signaling in non-neural cells. Our results support this novel concept based on attenuated scratching behavior in response to histaminergic (histamine, compound 48/80, endothelin-1), not non-histaminergic (chloroquine) pruritogens in Trpv4 keratinocyte-specific and inducible knock-out mice. We demonstrate that keratinocytes rely on TRPV4 for calcium influx in response to histaminergic pruritogens. TRPV4 activation in keratinocytes evokes phosphorylation of mitogen-activated protein kinase, ERK, for histaminergic pruritogens. This finding is relevant because we observed robust anti-pruritic effects with topical applications of selective inhibitors for TRPV4 and also for MEK, the kinase upstream of ERK, suggesting that calcium influx via TRPV4 in keratinocytes leads to ERK-phosphorylation, which in turn rapidly converts the keratinocyte into an organismal itch-generator cell. In support of this concept we found that scratching behavior, evoked by direct intradermal activation of TRPV4, was critically dependent on TRPV4 expression in keratinocytes. Thus, TRPV4 functions as a pruriceptor-TRP in skin keratinocytes in histaminergic itch, a novel basic concept with translational-medical relevance. PMID:26961876

  2. Spine calcium transients induced by synaptically-evoked action potentials can predict synapse location and establish synaptic democracy.

    Directory of Open Access Journals (Sweden)

    David C Sterratt

    Full Text Available CA1 pyramidal neurons receive hundreds of synaptic inputs at different distances from the soma. Distance-dependent synaptic scaling enables distal and proximal synapses to influence the somatic membrane equally, a phenomenon called "synaptic democracy". How this is established is unclear. The backpropagating action potential (BAP is hypothesised to provide distance-dependent information to synapses, allowing synaptic strengths to scale accordingly. Experimental measurements show that a BAP evoked by current injection at the soma causes calcium currents in the apical shaft whose amplitudes decay with distance from the soma. However, in vivo action potentials are not induced by somatic current injection but by synaptic inputs along the dendrites, which creates a different excitable state of the dendrites. Due to technical limitations, it is not possible to study experimentally whether distance information can also be provided by synaptically-evoked BAPs. Therefore we adapted a realistic morphological and electrophysiological model to measure BAP-induced voltage and calcium signals in spines after Schaffer collateral synapse stimulation. We show that peak calcium concentration is highly correlated with soma-synapse distance under a number of physiologically-realistic suprathreshold stimulation regimes and for a range of dendritic morphologies. Peak calcium levels also predicted the attenuation of the EPSP across the dendritic tree. Furthermore, we show that peak calcium can be used to set up a synaptic democracy in a homeostatic manner, whereby synapses regulate their synaptic strength on the basis of the difference between peak calcium and a uniform target value. We conclude that information derived from synaptically-generated BAPs can indicate synapse location and can subsequently be utilised to implement a synaptic democracy.

  3. Spine Calcium Transients Induced by Synaptically-Evoked Action Potentials Can Predict Synapse Location and Establish Synaptic Democracy

    Science.gov (United States)

    Meredith, Rhiannon M.; van Ooyen, Arjen

    2012-01-01

    CA1 pyramidal neurons receive hundreds of synaptic inputs at different distances from the soma. Distance-dependent synaptic scaling enables distal and proximal synapses to influence the somatic membrane equally, a phenomenon called “synaptic democracy”. How this is established is unclear. The backpropagating action potential (BAP) is hypothesised to provide distance-dependent information to synapses, allowing synaptic strengths to scale accordingly. Experimental measurements show that a BAP evoked by current injection at the soma causes calcium currents in the apical shaft whose amplitudes decay with distance from the soma. However, in vivo action potentials are not induced by somatic current injection but by synaptic inputs along the dendrites, which creates a different excitable state of the dendrites. Due to technical limitations, it is not possible to study experimentally whether distance information can also be provided by synaptically-evoked BAPs. Therefore we adapted a realistic morphological and electrophysiological model to measure BAP-induced voltage and calcium signals in spines after Schaffer collateral synapse stimulation. We show that peak calcium concentration is highly correlated with soma-synapse distance under a number of physiologically-realistic suprathreshold stimulation regimes and for a range of dendritic morphologies. Peak calcium levels also predicted the attenuation of the EPSP across the dendritic tree. Furthermore, we show that peak calcium can be used to set up a synaptic democracy in a homeostatic manner, whereby synapses regulate their synaptic strength on the basis of the difference between peak calcium and a uniform target value. We conclude that information derived from synaptically-generated BAPs can indicate synapse location and can subsequently be utilised to implement a synaptic democracy. PMID:22719238

  4. Dynamic acousto-elastic test using continuous probe wave and transient vibration to investigate material nonlinearity.

    Science.gov (United States)

    Eiras, J N; Vu, Q A; Lott, M; Payá, J; Garnier, V; Payan, C

    2016-07-01

    This study demonstrates the feasibility of the dynamic acousto-elastic effect of a continuous high frequency wave for investigating the material nonlinearity upon transient vibration. The approach is demonstrated on a concrete sample measuring 15×15×60cm(3). Two ultrasonic transducers (emitter and receiver) are placed at its middle span. A continuous high frequency wave of 500kHz propagates through the material and is modulated with a hammer blow. The position of the hammer blow on the sample is configured to promote the first bending mode of vibration. The use of a continuous wave allows discrete time extraction of the nonlinear behavior by a short-time Fourier transform approach, through the simultaneous comparison of a reference non-modulated signal and an impact-modulated signal. The hammer blow results in phase shifts and variations of signal amplitude between reference and perturbed signals, which are driven by the resonant frequency of the sample. Finally, a comprehensive analysis of the relaxation mechanisms (modulus and attenuation recovery) is conducted to untangle the coupled fast and slow hysteretic effects. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Discrete homotopy analysis for optimal trading execution with nonlinear transient market impact

    Science.gov (United States)

    Curato, Gianbiagio; Gatheral, Jim; Lillo, Fabrizio

    2016-10-01

    Optimal execution in financial markets is the problem of how to trade a large quantity of shares incrementally in time in order to minimize the expected cost. In this paper, we study the problem of the optimal execution in the presence of nonlinear transient market impact. Mathematically such problem is equivalent to solve a strongly nonlinear integral equation, which in our model is a weakly singular Urysohn equation of the first kind. We propose an approach based on Homotopy Analysis Method (HAM), whereby a well behaved initial trading strategy is continuously deformed to lower the expected execution cost. Specifically, we propose a discrete version of the HAM, i.e. the DHAM approach, in order to use the method when the integrals to compute have no closed form solution. We find that the optimal solution is front loaded for concave instantaneous impact even when the investor is risk neutral. More important we find that the expected cost of the DHAM strategy is significantly smaller than the cost of conventional strategies.

  6. Emergence of nonlinearity and plausible turbulence in accretion disks via hydromagnetic transient growth faster than magnetorotational instability

    CERN Document Server

    Nath, Sujit K

    2016-01-01

    We investigate the evolution of hydromagnetic perturbations in a small section of accretion disks. It is known that molecular viscosity is negligible in accretion disks. Hence, it has been argued that Magnetorotational Instability (MRI) is responsible for transporting matter in the presence of weak magnetic field. However, there are some shortcomings, which question effectiveness of MRI. Now the question arises, whether other hydromagnetic effects, e.g. transient growth (TG), can play an important role to bring nonlinearity in the system, even at weak magnetic fields. Otherwise, whether MRI or TG, which is primarily responsible to reveal nonlinearity to make the flow turbulent? Our results prove explicitly that the flows with high Reynolds number (Re), which is the case of realistic astrophysical accretion disks, exhibit nonlinearity by best TG of perturbation modes faster than that by best modes producing MRI. For a fixed wavevector, MRI dominates over transient effects, only at low Re, lower than its value ...

  7. PRONTO3D users` instructions: A transient dynamic code for nonlinear structural analysis

    Energy Technology Data Exchange (ETDEWEB)

    Attaway, S.W.; Mello, F.J.; Heinstein, M.W.; Swegle, J.W.; Ratner, J.A. [Sandia National Labs., Albuquerque, NM (United States); Zadoks, R.I. [Univ. of Texas, El Paso, TX (United States)

    1998-06-01

    This report provides an updated set of users` instructions for PRONTO3D. PRONTO3D is a three-dimensional, transient, solid dynamics code for analyzing large deformations of highly nonlinear materials subjected to extremely high strain rates. This Lagrangian finite element program uses an explicit time integration operator to integrate the equations of motion. Eight-node, uniform strain, hexahedral elements and four-node, quadrilateral, uniform strain shells are used in the finite element formulation. An adaptive time step control algorithm is used to improve stability and performance in plasticity problems. Hourglass distortions can be eliminated without disturbing the finite element solution using either the Flanagan-Belytschko hourglass control scheme or an assumed strain hourglass control scheme. All constitutive models in PRONTO3D are cast in an unrotated configuration defined using the rotation determined from the polar decomposition of the deformation gradient. A robust contact algorithm allows for the impact and interaction of deforming contact surfaces of quite general geometry. The Smooth Particle Hydrodynamics method has been embedded into PRONTO3D using the contact algorithm to couple it with the finite element method.

  8. Three-wave mixing of ordinary and backward electromagnetic waves: extraordinary transients in the nonlinear reflectivity and parametric amplification.

    Science.gov (United States)

    Slabko, Vitaly V; Popov, Alexander K; Tkachenko, Viktor A; Myslivets, Sergey A

    2016-09-01

    Three-wave mixing of ordinary and backward electromagnetic waves in a pulsed regime is investigated in the metamaterials that enable the coexistence and phase-matching of such waves. It is shown that the opposite direction of phase velocity and energy flux in backward waves gives rise to extraordinary transient processes due to greatly enhanced optical parametric amplification and frequency up- and down-shifting nonlinear reflectivity. The differences are illustrated through comparison with the counterparts in ordinary, co-propagating settings.

  9. NON-LINEAR TRANSIENT HEAT CONDUCTION ANALYSIS OF INSULATION WALL OF TANK FOR TRANSPORTATION OF LIQUID ALUMINUM

    OpenAIRE

    Miroslav M Živković; Aleksandar V Nikolić; Radovan B Slavković; Fatima T Živić

    2010-01-01

    This paper deals with transient nonlinear heat conduction through the insulation wall of the tank for transportation of liquid aluminum. Tanks designed for this purpose must satisfy certain requirements regarding temperature of loading and unloading, during transport. Basic theoretical equations are presented, which describe the problem of heat conduction finite element (FE) analysis, starting from the differential equation of energy balance, taking into account the initial and boundary condi...

  10. NON-LINEAR TRANSIENT HEAT CONDUCTION ANALYSIS OF INSULATION WALL OF TANK FOR TRANSPORTATION OF LIQUID ALUMINUM

    Directory of Open Access Journals (Sweden)

    Miroslav M Živković

    2010-01-01

    Full Text Available This paper deals with transient nonlinear heat conduction through the insulation wall of the tank for transportation of liquid aluminum. Tanks designed for this purpose must satisfy certain requirements regarding temperature of loading and unloading, during transport. Basic theoretical equations are presented, which describe the problem of heat conduction finite element (FE analysis, starting from the differential equation of energy balance, taking into account the initial and boundary conditions of the problem. General 3D problem for heat conduction is considered, from which solutions for two- and one-dimensional heat conduction can be obtained, as special cases. Forming of the finite element matrices using Galerkin method is briefly described. The procedure for solving equations of energy balance is discussed, by methods of resolving iterative processes of nonlinear transient heat conduction. Solution of this problem illustrates possibilities of PAK-T software package, such as materials properties, given as tabular data, or analytical functions. Software also offers the possibility to solve nonlinear and transient problems with incremental methods. Obtained results for different thicknesses of the tank wall insulation materials enable its comparison in regards to given conditions

  11. Assessment of ship manoeuvrability by using a coupling between a nonlinear transient manoeuvring model and mathematical programming techniques

    Institute of Scientific and Technical Information of China (English)

    2013-01-01

    In this paper, a numerical method based on a coupling between a mathematical model of nonlinear transient ship manoeu-vring motion in the horizontal plane and Mathematical Programming (MP) techniques is proposed. The aim of the proposed proce-dure is an efficient estimation of optimal ship hydrodynamic parameters in a dynamic model at the early design stage. The proposed procedure has been validated through turning circle and zigzag manoeuvres based on experimental data of sea trials of the 190 000-dwt oil tanker. Comparisons between experimental and computed data show a good agreement of overall tendency in manoeuvring trajectories.

  12. Application of multilevel scheme and two level discretization for POD based model order reduction of nonlinear transient heat transfer problems

    Science.gov (United States)

    Gaonkar, A. K.; Kulkarni, S. S.

    2015-01-01

    In the present paper, a method to reduce the computational cost associated with solving a nonlinear transient heat conduction problem is presented. The proposed method combines the ideas of two level discretization and the multilevel time integration schemes with the proper orthogonal decomposition model order reduction technique. The accuracy and the computational efficiency of the proposed methods is discussed. Several numerical examples are presented for validation of the approach. Compared to the full finite element model, the proposed method significantly reduces the computational time while maintaining an acceptable level of accuracy.

  13. Transient and chaotic low-energy transfers in a system with bistable nonlinearity

    Energy Technology Data Exchange (ETDEWEB)

    Romeo, F., E-mail: francesco.romeo@uniroma1.it [Department of Structural and Geotechnical Engineering, SAPIENZA University of Rome, Rome (Italy); Manevitch, L. I. [Institute of Chemical Physics, RAS, Moscow (Russian Federation); Bergman, L. A.; Vakakis, A. [College of Engineering, University of Illinois at Urbana–Champaign, Champaign, Illinois 61820 (United States)

    2015-05-15

    The low-energy dynamics of a two-dof system composed of a grounded linear oscillator coupled to a lightweight mass by means of a spring with both cubic nonlinear and negative linear components is investigated. The mechanisms leading to intense energy exchanges between the linear oscillator, excited by a low-energy impulse, and the nonlinear attachment are addressed. For lightly damped systems, it is shown that two main mechanisms arise: Aperiodic alternating in-well and cross-well oscillations of the nonlinear attachment, and secondary nonlinear beats occurring once the dynamics evolves solely in-well. The description of the former dissipative phenomenon is provided in a two-dimensional projection of the phase space, where transitions between in-well and cross-well oscillations are associated with sequences of crossings across a pseudo-separatrix. Whereas the second mechanism is described in terms of secondary limiting phase trajectories of the nonlinear attachment under certain resonance conditions. The analytical treatment of the two aformentioned low-energy transfer mechanisms relies on the reduction of the nonlinear dynamics and consequent analysis of the reduced dynamics by asymptotic techniques. Direct numerical simulations fully validate our analytical predictions.

  14. Quantum Generation Dynamics of Coherent Phonon in Semiconductors: Transient and Nonlinear Fano Resonance

    Science.gov (United States)

    Watanabe, Yohei; Hino, Ken-Ichi; Hase, Muneaki; Maeshima, Nobuya

    The coherent phonon (CP) generation is one of the representative phenomena induced by ultrashort pulsed laser. In particular, in the initial stage of the CP generation in lightly n-doped Si, the vestige of Fano resonance (FR) manifested in a flash was observed in time-resolved spectroscopy experiments, in which it was speculated that this phenomenon results from the birth of transient polaronic quasiparticles composed of electrons and phonons strongly interacting each other. This study is aimed at constructing a fully-quantum-mechanical model for the CP generation and tracking the origin of the transient FR. We calculate two physical quantities in both of polar and non-polar semiconductors such as GaAs and undoped Si. One is a retarded longitudinal susceptibility which allows one to calculate a transient induced photoemission spectrum. The other is the Fourier-transform of LO-phonon displacement into frequency domain. We have succeeded in showing that the transient FR is exclusively caused in Si in harmony with the experiments, though, not observed in GaAs.

  15. Nonlinear predictive control for the damping of multimachine power system transients using FACTS devices

    Energy Technology Data Exchange (ETDEWEB)

    Rajkumar, V. [ABB Transmission Technology Institute, Raleigh, NC (United States); Mohler, R.R. [Oregon State Univ., Corvallis, OR (United States)

    1994-12-31

    This paper presents a framework for the development of discrete-time, nonlinear predictive controllers using thyristor-controlled-series-capacitors and phasor measurements of bus voltage magnitude and angle, for the stabilization and rapid damping of multimachine power systems which are subjected to large disturbances. When the faults of concern are large, the nonlinear predictive controllers are used to return the power system state to a small region about the post-fault equilibrium. In this region, linear controllers provide local asymptotic stability and rapid damping. Simulation results are provided on a sample four-machine power system.

  16. Solution of transient optimization problems by using an algorithm based on nonlinear programming

    Science.gov (United States)

    Teren, F.

    1977-01-01

    A new algorithm is presented for solution of dynamic optimization problems which are nonlinear in the state variables and linear in the control variables. It is shown that the optimal control is bang-bang. A nominal bang-bang solution is found which satisfies the system equations and constraints, and influence functions are generated which check the optimality of the solution. Nonlinear optimization (gradient search) techniques are used to find the optimal solution. The algorithm is used to find a minimum time acceleration for a turbofan engine.

  17. Solution of transient optimization problems by using an algorithm based on nonlinear programming

    Science.gov (United States)

    Teren, F.

    1977-01-01

    A new algorithm is presented for solution of dynamic optimization problems which are nonlinear in the state variables and linear in the control variables. It is shown that the optimal control is bang-bang. A nominal bang-bang solution is found which satisfies the system equations and constraints, and influence functions are generated which check the optimality of the solution. Nonlinear optimization (gradient search) techniques are used to find the optimal solution. The algorithm is used to find a minimum time acceleration for a turbofan engine.

  18. Consideration of Transient Stream/Aquifer Interaction with the Nonlinear Boussinesq Equation using HPM

    DEFF Research Database (Denmark)

    Ganji, S. S.; Barari, Amin; Sfahani, M. G.

    2011-01-01

    of time. The differential equations were solved using the method of Homotopy Perturbation. The simplicity and accuracy of the approximation are compared with “exact” solution and illustrated numerically and graphically. The results reveal that the HPM is very effective and simple and provides highly...... accurate solutions for nonlinear differential equations....

  19. Approximation for Transient of Nonlinear Circuits Using RHPM and BPES Methods

    Directory of Open Access Journals (Sweden)

    H. Vazquez-Leal

    2013-01-01

    Full Text Available The microelectronics area constantly demands better and improved circuit simulation tools. Therefore, in this paper, rational homotopy perturbation method and Boubaker Polynomials Expansion Scheme are applied to a differential equation from a nonlinear circuit. Comparing the results obtained by both techniques revealed that they are effective and convenient.

  20. Nonlinear optical response of C60 in solvents: picosecond transient grating experiments

    Science.gov (United States)

    Khudyakov, Dmitriy V.; Rubtsov, Igor V.; Lobach, Anatolii S.; Nadtochenko, Victor A.

    1996-05-01

    Time-resolved resonant nonlinear optical response of C60 in a chlorobenzene solution was measured for 528 nm excitation and 1055, 528, and 351 nm probing for zzzz and zzyy configurations. The slow part of the signal (8 +/- 2 ps) was attributed to the orientational motion of C60 excited molecules.

  1. Nonlinear denoising of transient signals with application to event related potentials

    CERN Document Server

    Effern, A; Schreiber, T; Grunwald, T; David, P; Elger, C E

    2000-01-01

    We present a new wavelet based method for the denoising of {\\it event related potentials} ERPs), employing techniques recently developed for the paradigm of deterministic chaotic systems. The denoising scheme has been constructed to be appropriate for short and transient time sequences using circular state space embedding. Its effectiveness was successfully tested on simulated signals as well as on ERPs recorded from within a human brain. The method enables the study of individual ERPs against strong ongoing brain electrical activity.

  2. Localized infusions of the partial alpha 7 nicotinic receptor agonist SSR180711 evoke rapid and transient increases in prefrontal glutamate release

    DEFF Research Database (Denmark)

    Bortz, D M; Mikkelsen, J D; Bruno, J P

    2013-01-01

    The ability of local infusions of the alpha 7 nicotinic acetycholine receptor (α7 nAChR) partial agonist SSR180711 to evoke glutamate release in prefrontal cortex was determined in awake rats using a microelectrode array. Infusions of SSR180711 produced dose-dependent increases in glutamate level...

  3. EXACT SOLUTIONS FOR NONLINEAR TRANSIENT FLOW MODEL INCLUDING A QUADRATIC GRADIENT TERM

    Institute of Scientific and Technical Information of China (English)

    曹绪龙; 同登科; 王瑞和

    2004-01-01

    The models of the nonlinear radial flow for the infinite and finite reservoirs including a quadratic gradient term were presented. The exact solution was given in real space for flow equation including quadratic gradiet term for both constant-rate and constant pressure production cases in an infinite system by using generalized Weber transform. Analytical solutions for flow equation including quadratic gradient term were also obtained by using the Hankel transform for a finite circular reservoir case. Both closed and constant pressure outer boundary conditions are considered. Moreover, both constant rate and constant pressure inner boundary conditions are considered. The difference between the nonlinear pressure solution and linear pressure solution is analyzed. The difference may be reached about 8% in the long time. The effect of the quadratic gradient term in the large time well test is considered.

  4. An exact explicit solution for one-dimensional, transient, nonlinear Richards' equation for modeling infiltration with special hydraulic functions

    Science.gov (United States)

    Hayek, Mohamed

    2016-04-01

    This work develops a simple exact and explicit solution of the one-dimensional transient and nonlinear Richards' equation for soils in a special case of exponential water retention curve and power law hydraulic conductivity. The exact solution is obtained as traveling wave based on the approach proposed by Philip (1957, 1967) and adopted by Zlotnik et al. (2007). The obtained solution is novel, and it expresses explicitly the water content as function of the depth and time. It can be useful to model infiltration into semi-infinite soils with time-dependent boundary conditions and infiltration with constant boundary condition but space-dependent initial condition. A complete analytical inverse procedure based on the proposed analytical solution is presented which allows the estimation of hydraulic parameters. The proposed exact solution is also important for the verification of numerical schemes as well as for checking the implementation of time-dependent boundary conditions.

  5. A discontinuous Galerkin method for solving transient Maxwell equations with nonlinear material properties

    KAUST Repository

    Sirenko, Kostyantyn

    2014-07-01

    Discontinuous Galerkin time-domain method (DGTD) has been used extensively in computational electromagnetics for analyzing transient electromagnetic wave interactions on structures described with linear constitutive relations. DGTD expands unknown fields independently on disconnected mesh elements and uses numerical flux to realize information exchange between fields on different elements (J. S. Hesthaven and T. Warburton, Nodal Discontinuous Galerkin Method, 2008). The numerical flux of choice for \\'linear\\' Maxwell equations is the upwind flux, which mimics accurately the physical behavior of electromagnetic waves on discontinuous boundaries. It is obtained from the analytical solution of the Riemann problem defined on the boundary of two neighboring mesh elements.

  6. Unidirectionally Coupled Map Lattices with Nonlinear Coupling: Unbinding Transitions and Superlong Transients

    DEFF Research Database (Denmark)

    Marschler, Christian; Vollmer, Jürgen

    2014-01-01

    , the Reynolds number for pipe flow, and with transitions from bounded chaotic patches to an invasion of space of irregular motion. Dynamical systems models are unique tools in this respect because they can provide insight into the origin of the very long lifetime of puffs, and the dynamical mechanism leading......Recently, highly resolved experiments and simulations have provided detailed insight into the dynamics of turbulent pipe flow. This has revived the interest in identifying mechanisms that generate chaotic transients with superexponential growth of lifetime as a function of a control parameter...... to the transition from puffs to slugs in pipe flow. The present paper contributes to this enterprise by introducing a unidirectionally coupled map lattice. It mimics three of the salient features of pipe-flow turbulence: (i) the transition from laminar flow to puffs, (ii) a superexponential scaling of puff lifetime...

  7. Unidirectionally Coupled Map Lattices with Non-Linear Coupling: Unbinding Transitions and Super-Long Transients

    CERN Document Server

    Marschler, Christian

    2014-01-01

    Recently, highly resolved experiments and simulations have provided detailed insight into the dynamics of turbulent pipe flow. This has revived the interest to identify mechanisms that generate chaotic transients with super-exponential growth of lifetime as a function of a control parameter, the Reynolds number for pipe flow, and with transitions from bounded chaotic patches to an invasion of space of irregular motion. Dynamical systems models are unique tools in this respect because they can provide insight into the origin of the very long life time of puffs, and the dynamical mechanism leading to the transition from puffs to slugs in pipe flow. The present paper contributes to this enterprise by introducing a unidirectionally coupled map lattice. It mimics three of the salient features of pipe-flow turbulence: (i) the transition from laminar flow to puffs, (ii) a super-exponential scaling of puff lifetime, and (iii) the transition from puffs to slugs by an unbinding transition in an intermittency scenario. ...

  8. Spatially Nonuniform Heating and the Nonlinear Transient Response of Elastomeric Photomechanical Actuators

    Directory of Open Access Journals (Sweden)

    Robert W. Cohn

    2016-06-01

    Full Text Available Recently various nanomaterials, such as carbon nanotubes and graphene, have been added to rubbery elastomers, such as poly dimethyl siloxane (PDMS, to enable generation of stress and displacement in response to remote illumination. While the response is primarily due to heat-induced generation of stress; i.e., the thermoelastic effect in rubbers, illuminated samples have shown unexpected deviations between the transient waveforms of sample temperature and induced stress. In this report we have created a new and simple lumped element model to explain the stress behavior of these photomechanical nanocomposites. The model consists of two parameters that describe the spatially averaged steady state temperature rise due to optical absorption of the structure (typically a long strip of pre-strained elastomer and the spatially averaged convective cooling rate of the strip, together with a time-varying function that effectively represents the temperature distribution and thermal convection along the length of the strip. The model is used to compare two actuators that each have a thin embedded layer of carbon nanotubes, in which the one film consists of randomly aligned nanotubes and the other has a much more ordered alignment. The model not only fits both transient responses, but the differences between the parameters suggests that the ordered film conducts heat across the strip more rapidly than the disordered film, leading to it more rapidly reaching the steady state level of maximum stress. This model should be helpful in future experimental studies that work to observe, delineate and identify possible nanoscale and molecular contributions to photomechanical stress.

  9. On the effect of a two-rocks boundary on the propagation of nonlinear transients of temperature and pressure in deformable porous rocks

    CERN Document Server

    Salusti, E; Garra, R

    2016-01-01

    We here analyze the propagation of transients of fluid-rock temperature and pressure through a thin boundary layer, where a steady trend is present, between two adjacent homogeneous rocks. We focus on the effect of convection on transients crossing such thin layer. In comparison with early models where this boundary was assumed a sharp mathematical plane separating the two rocks, here we show a realistic analysis of such boundary layer that implies a novel nonlinear model. Its solutions describe large amplitude, quick and sharp transients characterized by a novel drift and variations of the signal amplitude, leading to a nonlinear wave propagation. Possible applications are in volcanic, hydrologic, hydrothermal systems as well as for deep oil drilling. In addition, this formalism could easily be generalized for the case of a signal arriving in a rock characterized by a steady trend of pressure and/or temperature. These effects, being proportional to the initial conditions, can also give velocity variations no...

  10. Transfinite element methodology for nonlinear/linear transient thermal modelling/analysis - Progress and recent advances

    Science.gov (United States)

    Tamma, Kumar K.; Railkar, Sudhir B.

    1988-01-01

    The 'transfinite element method' (TFEM) proposed by Tamma and Railkar (1987 and 1988) for the analysis of linear and nonlinear heat-transfer problems is described and demonstrated. The TFEM combines classical Galerkin and transform approaches with state-of-the-art FEMs to obtain a flexible hybrid modeling scheme. The fundamental principles of the TFEM and the derivation of the governing equations are reviewed, and numerical results for sample problems are presented in extensive graphs and briefly characterized. Problems analyzed include a square plate with a hole, a rectangular plate with natural and essential boundary conditions and varying thermal conductivity, the Space Shuttle thermal protection system, a bimaterial plate subjected to step temperature variations, and solidification in a semiinfinite liquid slab.

  11. Transient and stability analysis of large scale rotor-bearing system with strong nonlinear elements by the mode summation-transfer matrix method

    Science.gov (United States)

    Gu, Zhiping

    This paper extends Riccati transfer matrix method to the transient and stability analysis of large scale rotor-bearing systems with strong nonlinear elements, and proposes a mode summation-transfer matrix method, in which the field transfer matrix of a distributed mass uniform shaft segment is obtained with the aid of the idea of mode summation and Newmark beta formulation, and the Riccati transfer matrix method is adopted to stablize the boundary value problem of the nonlinear systems. In this investigation, the real nonlinearity of the strong nonlinear elements is considered, not linearized, and the advantages of the Riccati transfer matrix are retained. So, this method is especially applicable to analyze the transient response and stability of large-scale rotor-bear systems with strong nonlinear elements. One example, a single-spool rotating system with strong nonlinear elements, is given. The obtained results show that this method is superior to that of Gu and Chen (1990) in accuracy, stability, and economy.

  12. A non-linear induced polarization effect on transient electromagnetic soundings

    Science.gov (United States)

    Hallbauer-Zadorozhnaya, Valeriya Yu.; Santarato, Giovanni; Abu Zeid, Nasser; Bignardi, Samuel

    2016-10-01

    In a TEM survey conducted for characterizing the subsurface for geothermal purposes, a strong induced polarization effect was recorded in all collected data. Surprisingly, anomalous decay curves were obtained in part of the sites, whose shape depended on the repetition frequency of the exciting square waveform, i.e. on current pulse length. The Cole-Cole model, besides being not directly related to physical parameters of rocks, was found inappropriate to model the observed distortion, due to induced polarization, because this model is linear, i.e. it cannot fit any dependence on current pulse. This phenomenon was investigated and explained as due to the presence of membrane polarization linked to constrictivity of (fresh) water-saturated pores. An algorithm for mathematical modeling of TEM data was then developed to fit this behavior. The case history is then discussed: 1D inversion, which accommodates non-linear effects, produced models that agree quite satisfactorily with resistivity and chargeability models obtained by an electrical resistivity tomography carried out for comparison.

  13. Comparative efficiencies of three parallel algorithms for nonlinear implicit transient dynamic analysis

    Indian Academy of Sciences (India)

    A Rama Mohan Rao; T V S R Appa Rao; B Dattaguru

    2004-02-01

    The work reported in this paper is motivated by the need to develop portable parallel processing algorithms and codes which can run on a variety of hardware platforms without any modifications. The prime aim of the research work reported here is to test the portability of the parallel algorithms and also to study and understand the comparative efficiencies of three parallel algorithms developed for implicit time integration technique. The standard message passing interface (MPI) is used to develop parallel algorithms for computing nonlinear dynamic response of large structures employing implicit time-marching scheme. The parallel algorithms presented in this paper are developed under the broad framework of non-overlapped domain decomposition technique. Numerical studies indicate that the parallel algorithm devised employing the conventional form of Newmark time integration algorithm is faster than the predictor–corrector form. It is also accurate and highly adaptive to fine grain computations. The group implicit algorithm is found to be extremely superior in performance when compared to the other two parallel algorithms. This algorithm is better suited for large size problems on coarse grain environment as the resulting submeshes will obviously be large and thus permit larger time steps without losing accuracy.

  14. A Nonlinear System Model of Wall Turbulence Generation Under Active Suppression and Enhancement of Streak Transient Growth Instability

    Science.gov (United States)

    Midya, Samaresh; Duong, Alan; Thomas, Flint; Corke, Thomas

    2016-11-01

    Schoppa and Hussain (1998, 2002) demonstrated streak transient growth (STG) as the dominant streamwise coherent structure generation mechanism required for wall turbulence production. A novel, flush surface-mounted pulsed-DC plasma actuator was recently developed at the University of Notre Dame to actively intervene in STG. In recent high Reynolds number, zero pressure gradient turbulent boundary layer experiments, drag reduction of up to 68% was achieved. This is due to a plasma-induced near-wall, spanwise mean flow sufficient in magnitude to prevent the lift-up of low-speed streaks. This limits their flanking wall-normal component vorticity-a critical parameter in STG. Experiments also show that sufficiently large plasma-induced spanwise flow can exacerbate STG and increase drag by 80%. The ability to significantly increase or decrease drag by near-wall actuation provides an unprecedented new tool for clarifying the open questions regarding the interaction between near-wall coherent structures and those in the logarithmic region. In the reported experiments this interaction is experimentally characterized by a second-order Volterra nonlinear system model under both active suppression and enhancement of STG. Supported by NASA Langley under NNX16CL27C.

  15. Role of transient receptor potential ion channels and evoked levels of neuropeptides in a formaldehyde-induced model of asthma in BALB/c mice.

    Directory of Open Access Journals (Sweden)

    Yang Wu

    Full Text Available OBJECTIVE: Asthma is a complex pulmonary inflammatory disease characterized by the hyper-responsiveness, remodeling and inflammation of airways. Formaldehyde is a common indoor air pollutant that can cause asthma in people experiencing long-term exposure. The irritant effect and adjuvant effect are the two possible pathways of formaldehyde promoted asthma. METHODOLOGY/PRINCIPAL FINDINGS: To explore the neural mechanisms and adjuvant effect of formaldehyde, 48 Balb/c mice in six experimental groups were exposed to (a vehicle control; (b ovalbumin; (c formaldehyde (3.0 mg/m(3; (d ovalbumin+formaldehyde (3.0 mg/m(3; (e ovalbumin+formaldehyde (3.0 mg/m(3+HC-030031 (transient receptor potential ankyrin 1 antagonist; (f ovalbumin+formaldehyde (3.0 mg/m(3+ capsazepine (transient receptor potential vanilloid 1 antagonist. Experiments were conducted after 4 weeks of combined exposure and 1-week challenge with aerosolized ovalbumin. Airway hyper-responsiveness, pulmonary tissue damage, eosinophil infiltration, and increased levels of interleukin-4, interleukin-6, interleukin-1β, immunoglobulin E, substance P and calcitonin gene-related peptide in lung tissues were found in the ovalbumin+formaldehyde (3.0 mg/m(3 group compared with the values seen in ovalbumin -only immunized mice. Except for interleukin-1β levels, other changes in the levels of biomarker could be inhibited by HC-030031 and capsazepine. CONCLUSIONS/SIGNIFICANCE: Formaldehyde might be a key risk factor for the rise in asthma cases. Transient receptor potential ion channels and neuropeptides have important roles in formaldehyde promoted-asthma.

  16. Calcium Transients in Dendrites of Neocortical Neurons Evoked by Single Subthreshold Excitatory Postsynaptic Potentials via Low-Voltage-Activated Calcium Channels

    Science.gov (United States)

    Markram, Henry; Sakmann, Bert

    1994-05-01

    Simultaneous recordings of membrane voltage and concentration of intracellular Ca2+ ([Ca2+]_i) were made in apical dendrites of layer 5 pyramidal cells of rat neocortex after filling dendrites with the fluorescent Ca2+ indicator Calcium Green-1. Subthreshold excitatory postsynaptic potentials (EPSPs), mediated by the activation of glutamate receptor channels, caused a brief increase in dendritic [Ca2+]_i. This rise in dendritic [Ca2+]_i was mediated by the opening of low-voltage-activated Ca2+ channels in the dendritic membrane. The results provide direct evidence that dendrites do not function as passive cables even at low-frequency synaptic activity; rather, a single subthreshold EPSP changes the dendritic membrane conductance by opening Ca2+ channels and generating a [Ca2+]_i transient that may propagate towards the soma. The activation of these Ca2+ channels at a low-voltage threshold is likely to influence the way in which dendritic EPSPs contribute to the electrical activity of the neuron.

  17. Nonlinear transient heat transfer and thermoelastic analysis of thick-walled FGM cylinder with temperature-dependent material properties using Hermitian transfinite element

    Energy Technology Data Exchange (ETDEWEB)

    Azadi, Mohammad [Sharif University of Technology, Tehran (Iran, Islamic Republic of); Azadi, Mahboobeh [Shiraz University, Shiraz (Iran, Islamic Republic of)

    2009-10-15

    Nonlinear transient heat transfer and thermoelastic stress analyses of a thick-walled FGM cylinder with temperature dependent materials are performed by using the Hermitian transfinite element method. Temperature-dependency of the material properties has not been taken into account in transient thermoelastic analysis, so far. Due to the mentioned dependency, the resulting governing FEM equations of transient heat transfer are highly nonlinear. Furthermore, in all finite element analysis performed so far in the field, Lagrangian elements have been used. To avoid an artificial local heat source at the mutual boundaries of the elements, Hermitian elements are used instead in the present research. Another novelty of the present paper is simultaneous use of the transfinite element method and updating technique. Time variations of the temperature, displacements, and stresses are obtained through a numerical Laplace inversion. Finally, results obtained considering the temperature-dependency of the material properties are compared with those derived based on temperature independency assumption. Furthermore, the temperature distribution and the radial and circumferential stresses are investigated versus time, geometrical parameters and index of power law. Results reveal that the temperature-dependency effect is significant

  18. Nonlinear rheology of glass-forming colloidal dispersions: transient stress-strain relations from anisotropic mode coupling theory and thermosensitive microgels

    Science.gov (United States)

    Amann, C. P.; Siebenbürger, M.; Ballauff, M.; Fuchs, M.

    2015-05-01

    Transient stress-strain relations close to the colloidal glass transition are obtained within the integration through transients framework generalizing mode coupling theory to flow driven systems. Results from large-scale numerical calculations are quantitatively compared to experiments on thermosensitive microgels, which reveals that theory captures the magnitudes of stresses semi-quantitatively even in the nonlinear regime, but overestimates the characteristic strain where plastic events set in. The former conclusion can also be drawn from flow curves, while the latter conclusion is supported by a comparison to single particle motion measured by confocal microscopy. The qualitative picture, as previously obtained from simplifications of the theory in schematic models, is recovered by the quantitative solutions of the theory for Brownian hard spheres.

  19. Nonlinear rheology of glass-forming colloidal dispersions: transient stress-strain relations from anisotropic mode coupling theory and thermosensitive microgels.

    Science.gov (United States)

    Amann, C M; Siebenbürger, M; Ballauff, M; Fuchs, M

    2015-05-20

    Transient stress-strain relations close to the colloidal glass transition are obtained within the integration through transients framework generalizing mode coupling theory to flow driven systems. Results from large-scale numerical calculations are quantitatively compared to experiments on thermosensitive microgels, which reveals that theory captures the magnitudes of stresses semi-quantitatively even in the nonlinear regime, but overestimates the characteristic strain where plastic events set in. The former conclusion can also be drawn from flow curves, while the latter conclusion is supported by a comparison to single particle motion measured by confocal microscopy. The qualitative picture, as previously obtained from simplifications of the theory in schematic models, is recovered by the quantitative solutions of the theory for Brownian hard spheres.

  20. Suppression of Nonlinear Patterning Effect in Wavelength Conversion Based on Transient Cross-Phase Modulation in Semiconductor Optical Amplifier Assisted with a Detuning Filter

    Institute of Scientific and Technical Information of China (English)

    ZHOU En-Bo; ZHANG Xin-Liang; YU Yu; HUANG De-Xiu

    2009-01-01

    Nonlinear patterning (NLP) effect in wavelength conversion based on transient cross-phase modulation (XPM) in semiconductor optical amplifier (SOA) assisted with a detuning filter is theoretically investigated.A nonadiabatic model is used to estimate the ultrafast dynamics o[ gain,phase and electron temperature in the SOA.Simulation results show that the NLP can be greatly suppressed by introducing an assist light,especially for the probe wavelength distant from gain peak.Furthermore,the results also indicate that the improvement is more evident for long wavelength probe light and assist light in counter-propagating configuration.

  1. Wavelength-Dependent Transient Characteristics Caused by Gain Saturation in Highly Nonlinear Fiber-Based Raman Amplifiers

    Institute of Scientific and Technical Information of China (English)

    Shinobu; Tamaoki; Tetsufumi; Tsuzaki; Motoki; Kakui; Masayuki; Shigematsu

    2003-01-01

    We have investigated the transient characteristics of discrete Raman Amplifiers and found that the response time caused by gain saturation is dependent upon the wavelength, which corresponds to the effective length of the pump light.

  2. Analysis of transient otoacoustic emissions and brainstem evoked auditory potentials in neonates with hyperbilirubinemia Análise das emissões otoacústicas transientes e dos potenciais evocados auditivos do tronco encefálico em neonatos com hiperbilirrubinemia

    Directory of Open Access Journals (Sweden)

    Daniela Polo Camargo da Silva

    2009-06-01

    Full Text Available Hyperbilirubinemia is toxic to the auditory pathways and to the central nervous system, leaving sequelae such as hearing loss and encephalopathy. AIM: to assess the hearing of neonates with hyperbilirubinemia, using transient evoked otoacoustic emissions (TOAEs and brainstem evoked auditory potentials (BEAP. Prospective study. MATERIALS AND METHODS: we had two groups: GI (n-25, neonates with hyperbilirubinemia; GII (n-22, neonates without hyperbilirubinemia and without risk factors for hearing loss. All the neonates had up to 60 days of life and were submitted to TOAE and BEAP. RESULTS: 12 neonates from GI and 10 from GII were girls and 13 from GI and 12 from GII were boys. TOAEs were present in all the children, however with lower amplitudes in GI, especially in the frequencies of 2 and 3KHz (p A hiperbilirrubinemia é tóxica às vias auditivas e ao sistema nervoso central, deixando sequelas como surdez e encefalopatia. OBJETIVOS: avaliar a audição de neonatos portadores de hiperbilirrubinemia, utilizando-se a pesquisa das emissões otoacústicas evocadas transientes (EOAET e dos potenciais evocados auditivos do tronco encefálico (PEATE. Estudo prospectivo. CASUÍSTICA E MÉTODOS: Constituíram-se dois grupos: GI (n-25, neonatos com hiperbilirrubinemia; GII (n-22, neonatos sem hiperbilirrubinemia e sem fatores de risco para surdez. Todos os neonatos tinham até 60 dias de vida e foram submetidos à EOAET e ao PEATE. RESULTADOS: 12 neonatos de GI e 10 de GII eram meninas e 13 de GI e 12 de GII eram meninos. As EOAET estavam presentes em todas as crianças, porém com amplitudes menores em GI, especialmente nas frequências de 2 e 3KHz (p < 0,05. No PEATE, observou-se discreto prolongamento de PV e de LI-V em GI. As alterações observadas nesses testes não se correlacionaram aos níveis séricos da bilirrubinemia. CONCLUSÕES: Em neonatos portadores de hiperbilirrubinemia, menores amplitudes das EOAET e discreto prolongamento de PV e de LI

  3. Investigation of scaling characteristics for defining design environments due to transient ground winds and near-field, nonlinear acoustic fields

    Science.gov (United States)

    Shih, C. C.

    1973-01-01

    In order to establish a foundation of scaling laws for the highly nonlinear waves associated with the launch vehicle, the basic knowledge of the relationships among the paramaters pertinent to the energy dissipation process associated with the propagation of nonlinear pressure waves in thermoviscous media is required. The problem of interest is to experimentally investigate the temporal and spacial velocity profiles of fluid flow in a 3-inch open-end pipe of various lengths, produced by the propagation of nonlinear pressure waves for various diaphragm burst pressures of a pressure wave generator. As a result, temporal and spacial characteristics of wave propagation for a parametric set of nonlinear pressure waves in the pipe containing air under atmospheric conditions were determined. Velocity measurements at five sections along the pipes of up to 210 ft. in length were made with hot-film anemometers for five pressure waves produced by a piston. The piston was derived with diaphragm burst pressures at 20, 40, 60, 80 and 100 psi in the driver chamber of the pressure wave generator.

  4. Adaptive actuator failure compensation control based on MMST grouping for a class of MIMO nonlinear systems with guaranteed transient performance

    Science.gov (United States)

    Zhang, Shao-Jie; Qiu, Xiang-Wei; Jiang, Bin; Liu, Chun-Sheng

    2015-03-01

    This paper presents a new adaptive compensation control approach for a class of multi-input multi-output (MIMO) nonlinear systems with actuator failures. In order to enlarge the set of compensable actuator failures, an actuators grouping scheme based on multiple model switching and tuning (MMST) is proposed for the nonlinear MIMO minimum-phase systems with multiple actuator failures. Then, an adaptive compensation scheme based on prescribed performance bound (PPB) which characterises the convergence rate and maximum overshoot of the tracking error is designed for the systems to ensure closed-loop signal boundedness and asymptotic output tracking despite unknown actuator failures. Simulation results are given to show the effectiveness of the control design.

  5. Inverse analysis of thermal conductivities in transient non-homogeneous and non-linear heat conductions using BEM based on complex variable differentiation method

    Science.gov (United States)

    Yu, XiaoChun; Bai, YuGuang; Cui, Miao; Gao, XiaoWei

    2013-05-01

    This paper presents a new inverse analysis approach to sensitivity analysis and material property identification in transient non-homogeneous and non-linear heat conduction Boundary Element Method (BEM) analysis based on Complex Variable Differentiation Method (CVDM). In this approach, the material properties are taken as the optimization variables, and the sensitivity coefficients are computed by CVDM. The advantages of using CVDM are that the computation of partial derivatives of an implicit function is reduced to function calculation in a complex domain, and the parameter sensitivity coefficients can be determined in a more accurate way than the traditional Finite Difference Method (FDM). Based on BEM and CVDM in evaluation of the sensitivity matrix of heat flux, the parameter such as thermal conductivity can be accurately identified. Six numerical examples are given to demonstrate the potential of the proposed approach. The results indicate that the presented method is efficient for identifying the thermal conductivity with single or multiple parameters.

  6. A nonlinear Hermitian transfinite element method for transient behavior analysis of hollow functionally graded cylinders with temperature-dependent materials under thermo-mechanical loads

    Energy Technology Data Exchange (ETDEWEB)

    Shariyat, M. [Faculty of Mechanical Engineering, K.N. Toosi University of Technology, Tehran (Iran, Islamic Republic of)], E-mail: m_shariyat@yahoo.com

    2009-04-15

    In the present paper, an algorithm for nonlinear transient behavior analysis of thick functionally graded cylindrical vessels or pipes with temperature-dependent material properties under thermo-mechanical loads is presented. In contrast to researches presented so far, a Hermitian transfinite element method is proposed to improve the accuracy and to prevent artificial interference or cohesion formation at the mutual boundaries of the elements. Time variations of the temperatures, displacements, and stresses are obtained through a numerical Laplace inversion. Another novelty of the present research is using the transfinite element method to solve nonlinear problems. A sensitivity analysis includes investigating effects of the volume fraction index, dimensions, and temperature-dependency of the material properties is performed. Results confirm the efficiency of the present algorithm and reveal the significant effects of the temperature-dependency of the material properties and the elastic wave reflections and interferences on the responses. In comparison to other techniques, the present technique may be used to obtain relatively accurate and stable results in a less computational time.

  7. Optical suppression of drug-evoked phasic dopamine release.

    Science.gov (United States)

    McCutcheon, James E; Cone, Jackson J; Sinon, Christopher G; Fortin, Samantha M; Kantak, Pranish A; Witten, Ilana B; Deisseroth, Karl; Stuber, Garret D; Roitman, Mitchell F

    2014-01-01

    Brief fluctuations in dopamine concentration (dopamine transients) play a key role in behavior towards rewards, including drugs of abuse. Drug-evoked dopamine transients may result from actions at both dopamine cell bodies and dopamine terminals. Inhibitory opsins can be targeted to dopamine neurons permitting their firing activity to be suppressed. However, as dopamine transients can become uncoupled from firing, it is unknown whether optogenetic hyperpolarization at the level of the soma is able to suppress dopamine transients. Here, we used in vivo fast-scan cyclic voltammetry to record transients evoked by cocaine and raclopride in nucleus accumbens (NAc) of urethane-anesthetized rats. We targeted halorhodopsin (NpHR) specifically to dopamine cells by injecting Cre-inducible virus into ventral tegmental area (VTA) of transgenic rats that expressed Cre recombinase under control of the tyrosine hydroxylase promoter (TH-Cre(+) rats). Consistent with previous work, co-administration of cocaine and raclopride led to the generation of dopamine transients in NAc shell. Illumination of VTA with laser strongly suppressed the frequency of transients in NpHR-expressing rats, but not in control rats. Laser did not have any effect on amplitude of transients. Thus, optogenetics can effectively reduce the occurrence of drug-evoked transients and is therefore a suitable approach for studying the functional role of such transients in drug-associated behavior.

  8. Optical suppression of drug-evoked phasic dopamine release

    Directory of Open Access Journals (Sweden)

    James Edgar Mccutcheon

    2014-09-01

    Full Text Available Brief fluctuations in dopamine concentration (dopamine transients play a key role in behavior towards rewards, including drugs of abuse. Drug-evoked dopamine transients may result from actions at both dopamine cell bodies and dopamine terminals. Inhibitory opsins can be targeted to dopamine neurons permitting their firing activity to be suppressed. However, as dopamine transients can become uncoupled from firing, it is unknown whether optogenetic hyperpolarization at the level of the soma is able to suppress dopamine transients. Here, we used in vivo fast-scan cyclic voltammetry to record transients evoked by cocaine and raclopride in nucleus accumbens (NAc of urethane-anesthetized rats. We targeted halorhodopsin (NpHR specifically to dopamine cells by injecting Cre-inducible virus into ventral tegmental area (VTA of transgenic rats that expressed Cre recombinase under control of the tyrosine hydroxylase promoter (TH-Cre+ rats. Consistent with previous work, co-administration of cocaine and raclopride led to the generation of dopamine transients in NAc shell. Illumination of VTA with laser strongly suppressed the frequency of transients in NpHR-expressing rats, but not in control rats. Laser did not have any effect on amplitude of transients. Thus, optogenetics can effectively reduce the occurrence of drug-evoked transients and is therefore a suitable approach for studying the functional role of such transients in drug-associated behavior.

  9. Proprioceptive evoked gamma oscillations

    DEFF Research Database (Denmark)

    Arnfred, Sidse M; Hansen, Lars Kai; Parnas, Josef;

    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...

  10. Multiple Color Stimulus Induced Steady State Visual Evoked Potentials

    Science.gov (United States)

    2007-11-02

    evoked potentials, multiple color, FFT, bispectrum I. INTRODUCTION Visual evoked potential ( VEP ) is the electrical response of...brain under visual stimulation, which can be recorded from the scalp over the visual cortex of the brain. A distinction is made between transient VEP ...and steady-state VEP (SSVEP) based on the stimulation frequencies. The former arises when the stimulation frequencies are less than 2 Hz. However

  11. The joy of transient chaos

    Energy Technology Data Exchange (ETDEWEB)

    Tél, Tamás [Institute for Theoretical Physics, Eötvös University, and MTA-ELTE Theoretical Physics Research Group, Pázmány P. s. 1/A, Budapest H-1117 (Hungary)

    2015-09-15

    We intend to show that transient chaos is a very appealing, but still not widely appreciated, subfield of nonlinear dynamics. Besides flashing its basic properties and giving a brief overview of the many applications, a few recent transient-chaos-related subjects are introduced in some detail. These include the dynamics of decision making, dispersion, and sedimentation of volcanic ash, doubly transient chaos of undriven autonomous mechanical systems, and a dynamical systems approach to energy absorption or explosion.

  12. Evoked acoustic emission

    DEFF Research Database (Denmark)

    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 onl...

  13. Evoked acoustic emission

    DEFF Research Database (Denmark)

    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...

  14. Proprioceptive evoked gamma oscillations

    DEFF Research Database (Denmark)

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

    2007-01-01

    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...

  15. Selecting and evoking innovators

    DEFF Research Database (Denmark)

    Kanstrup, Anne Marie; Christiansen, Ellen

    2006-01-01

    The practical undertaking of selecting users to work as innovators and of evoking their creative potential is crucial, but underexposed in the literature on user involvement in design. This paper reports findings from a recent case of user-driven innovation, the FEEDBACK-project, where the authors...... prepared for and conducted selection of and collaboration with innovators. The outcome was successful in the sense that the innovators produced excellent foundation for conceptual interaction design by creating mock-ups and explanations incarnating their preferences, attitudes and habits. By referring...... to theories of learning we try to explain how our way of working with selection and evoking of innovators has contributed to this positive result and how our approach to user-driven innovation can be regarded as a way to combine democracy and creativity in design....

  16. International Evoked Potentials Symposium

    CERN Document Server

    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...

  17. Evoked acoustic emission

    DEFF Research Database (Denmark)

    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 onl...... reveals presence of a true emission from all ears tested. It is concluded that the cochlear echo can be recorded in normal-hearing newborns with an extremely low rate of type I errors.......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...... a minor effect on the power spectra, i.e. the maximum jumps from one spectral peak to another. Experiments with deconvolution demonstrate that the emission generating system at least at a fixed intensity can be regarded as being linear and characterized by its impulse response which is similar...

  18. Evoked potentials in multiple sclerosis.

    Science.gov (United States)

    Kraft, George H

    2013-11-01

    Before the development of magnetic resonance imaging (MRI), evoked potentials (EPs)-visual evoked potentials, somatosensory evoked potentials, and brain stem auditory evoked responses-were commonly used to determine a second site of disease in patients being evaluated for possible multiple sclerosis (MS). The identification of an area of the central nervous system showing abnormal conduction was used to supplement the abnormal signs identified on the physical examination-thus identifying the "multiple" in MS. This article is a brief overview of additional ways in which central nervous system (CNS) physiology-as measured by EPs-can still contribute value in the management of MS in the era of MRIs.

  19. Music evokes vivid autobiographical memories.

    Science.gov (United States)

    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.

  20. Adjective metaphors evoke negative meanings.

    Science.gov (United States)

    Sakamoto, Maki; Utsumi, Akira

    2014-01-01

    Previous metaphor studies have paid much attention to nominal metaphors and predicative metaphors, but little attention has been given to adjective metaphors. Although some studies have focused on adjective metaphors, they only examined differences in the acceptability of various types of adjective metaphors. This paper explores the cognitive effects evoked by adjective metaphors. Three psychological experiments revealed that (1) adjective metaphors, especially those modified by color adjectives, tend to evoke negative effect; (2) although the meanings of metaphors are basically affected by the meanings of their vehicles, when a vehicle has a neutral meaning, negative meanings are evoked most frequently for adjective metaphors compared to nominal and predicative metaphors; (3) negative meanings evoked by adjective metaphors are related to poeticness, and poetic metaphors evoke negative meanings more easily than less poetic metaphors. Our research sheds new light on studies of the use of metaphor, which is one of the most basic human cognitive abilities.

  1. Achieving Presence through Evoked Reality

    Directory of Open Access Journals (Sweden)

    Jayesh S. ePillai

    2013-02-01

    Full Text Available The sense of ‘Presence’ (evolving from ‘telepresence’ has always been associated with virtual reality research and is still an exceptionally mystifying constituent. Now the study of presence clearly spans over various disciplines associated with cognition. This paper attempts to put forth a concept that argues that it’s an experience of an 'Evoked Reality’ (illusion of reality that triggers an ‘Evoked Presence’ (sense of presence in our minds. A Three Pole Reality Model is proposed to explain this phenomenon. The poles range from Dream Reality to Simulated Reality with Primary (Physical Reality at the center. To demonstrate the relationship between Evoked Reality and Evoked Presence, a Reality-Presence Map is developed. We believe that this concept of Evoked Reality and the proposed model may have significant applications in the study of presence, and in exploring the possibilities of not just virtual reality but also what we call ‘reality’.

  2. An Approach for Electromagnetic Transient Simulation of Power Transformers With Nonlinear Exciting Branch%考虑变压器励磁非线性的电磁暂态仿真算法

    Institute of Scientific and Technical Information of China (English)

    朱翊; 房大中; 王庆平

    2012-01-01

    A model for electromagnetic transient simulation of power transformer containing nonlinear exciting branch is built and the inrush current of power transformer under no-load switching is simulated by a simple simulation circuit. Applying piece-wise linearization the nonlinear phenomenon appeared in exciting branch of power transformer is processed and by means of simulation results under various simulation step lengths the overshoot appeared due to long step length adopted in piece-wise linearization is explained. The overshoot can be effectively limited by decreasing the step length, however the time for the simulation is evidently increased. On the basis of piece-wise linearization a predictor-corrector method is proposed to ameliorate the overshoot. A predictor-corrector module is added into the electromagnetic transient simulation program for power transformer, thus without changing step length the overshoot is overcome and the simulation process is accelerated. Simulation results verify the correctness and effectiveness of the proposed transformer model and the predictor-corrector method.%建立了一种含有非线性励磁支路的变压器电磁暂态仿真模型。通过简单的仿真线路,仿真了变压器空载合闸时发生励磁涌流的现象。应用分段线性化的方法处理变压器励磁支路的非线性问题,并通过不同仿真步长下励磁电流的仿真结果,说明了分段线性化在大步长下出现的过冲现象。减小仿真步长可有效抑制过冲,但是仿真时间明显增加。在分段线性化方法的基础上提出了预测校正法改善过冲问题。在变压器电磁暂态仿真的程序设计中加入了预测校正模块,在不改变步长的情况下,解决了过冲问题,加快了仿真的计算速度。最后通过仿真结果验证了变压器模型及预测校正方法的正确性和有效性。

  3. Speech Evoked Auditory Brainstem Response in Stuttering

    Directory of Open Access Journals (Sweden)

    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.

  4. Transient filament stretching rheometer II

    DEFF Research Database (Denmark)

    Kolte, Mette Irene; Rasmussen, Henrik K.; Hassager, Ole

    1997-01-01

    The Lagrangian sspecification is used to simulate the transient stretching filament rheometer. Simulations are performed for dilute PIB-solutions modeled as a four mode Oldroyd-B fluid and a semidilute PIB-solution modeled as a non-linear single integral equation. The simulations are compared...

  5. Nonlinear characteristics of the rotating exciter system of power plant generators in case of electricity accidents; Transientes Verhalten des rotierenden Erregersystems von Kraftwerksgeneratoren bei elektrischen Stoerfaellen

    Energy Technology Data Exchange (ETDEWEB)

    Ataei, Nader

    2006-05-09

    Different types of exciter are used for voltage supply to the synchronous generators of power stations depending on the required power and design. The exciter system of the generator, which as a rule consists syncronous motors and commutators, is commonly modeled in conventional models by control units with nonlinear characteristics which do not give an accurate picture of the dynamic processes inside the exciter motor. It was not possible to assess the component loads of the exciter components and the physical characteristics within the exciter system. In this study, a brushless exciter for the grid-connected synchronous generator was investigated which consists of two synchronous motors as primary and secondary exciter and two commutator bridges. A dynamic simulation model was developed for calculating the interactions between the grid, generator and exciter unit in consideration of electromagnetic and galvanic coupling. For this, the normal control units were replaced by physical components of the exciter system, i.e. electric exciter motors and commutators. The study was carried out using an enhanced version of the Siemens NETOMAC software, which provided information on the loads on the exciter components in case of internal and external failures. In particular, loads in coils and commutators were calculated that could not be measured before. The findings enable more accurate dimensioning of the exciter unit making it more fail-safe, and the protective systems can be adjusted more accurately. One important result of the investigation was the identification of all dynamic processes going on between the exciter motors, commutators, generator and grid induced by external and internal failures. (orig.) [German] Zur Spannungsversorgung der Synchrongeneratoren in Kraftwerken werden je nach Leistungsanforderung und Baukonzept unterschiedliche Erregereinrichtungen verwendet. Das Erregersystem des Generators, das in der Regel aus Erregersynchronmaschinen und

  6. Transient osteoporosis.

    Science.gov (United States)

    Korompilias, Anastasios V; Karantanas, Apostolos H; Lykissas, Marios G; Beris, Alexandros E

    2008-08-01

    Transient osteoporosis is characterized primarily by bone marrow edema. The disease most commonly affects the hip, knee, and ankle in middle-aged men. Its cause remains unknown. The hallmark that separates transient osteoporosis from other conditions presenting with a bone marrow edema pattern is its self-limited nature. Laboratory tests usually do not contribute to the diagnosis. Plain radiographs may reveal regional osseous demineralization. Magnetic resonance imaging is used primarily for early diagnosis and monitoring disease progression. Early differentiation from more aggressive conditions with long-term sequelae is essential to avoid unnecessary treatment. Clinical entities such as transient osteoporosis of the hip and regional migratory osteoporosis are spontaneously resolving conditions. However, early differential diagnosis and surgical treatment are crucial for the patient with osteonecrosis of the hip or knee.

  7. Evoked emotions predict food choice.

    Science.gov (United States)

    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. Evoked emotions predict food choice.

    Directory of Open Access Journals (Sweden)

    Jelle R Dalenberg

    Full Text Available 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.

  9. Resource Letter NO-1: Nonlinear Optics

    Science.gov (United States)

    Garmire, Elsa

    2011-03-01

    This Resource Letter provides a guide to the literature on nonlinear optics. Books, journals, and websites are introduced that cover the general subject. Journal articles and websites are cited covering the following topics: second-order nonlinearities in transparent media including second-harmonic generation and optical parametric oscillation, third-order and higher nonlinearities, nonlinear refractive index, absorptive nonlinearities such as saturable absorption and multiphoton absorption, and scattering nonlinearities such as stimulated Raman scattering and stimulated Brillouin scattering. Steady-state and transient phenomena, fiber optics, solitons, nonlinear wave mixing, optical phase conjugation, nonlinear spectroscopy, and multiphoton microscopy are all outlined.

  10. [Evoked potentials and inhalation anesthetics].

    Science.gov (United States)

    Thiel, A; Russ, W; Hempelmann, G

    1988-01-01

    Intraoperative monitoring of evoked potentials can be affected by various factors including volatile anaesthetics. These effects have to be considered in order to give correct interpretations of the obtained data. Visual evoked potentials (VEP) and auditory evoked potentials (AEP) will show strong alterations under general anaesthesia whereas brainstem auditory evoked potentials (BAEP) are slightly affected. The effects of nitrous oxide, halothane, enflurane, and isoflurane on somatosensory evoked potentials (SEP) after median nerve stimulation were studied in 35 healthy adult patients. pCO2 and tympanic membrane temperature were held constant. Simultaneous cervical and cortical SEP recording was performed using surface electrodes. After induction of anaesthesia SEP were recorded during normoventilation with 100% oxygen and after inhalation of 66.6% nitrous oxide. 10 patients received halothane at inspired concentrations of 0.5, 1.0, 1.5, and 2.0%. After nitrous oxide had been replaced by oxygen, halothane was reduced in steps of 0.5%. SEP were recorded at the end of each period (15 min). Equipotent doses of enflurane or isoflurane were administered to 15 and 10 patients, respectively. Nitrous oxide depressed early cortical SEP amplitude. Halothane, enflurane, and isoflurane caused dose dependent increases of latencies. Reduction of amplitude was most pronounced with isoflurane. Using high doses of enflurane in oxygen cortical SEP showed unusual high amplitudes associated with marked increases of latencies. Even under high concentrations of volatile anaesthetics cervical SEP were minimally affected. The effects of anaesthetic gases have to be considered when SEP are recorded intraoperatively.

  11. Brainstem auditory evoked potentials in children with lead exposure

    Directory of Open Access Journals (Sweden)

    Katia de Freitas Alvarenga

    2015-02-01

    Full Text Available Introduction: Earlier studies have demonstrated an auditory effect of lead exposure in children, but information on the effects of low chronic exposures needs to be further elucidated. Objective: To investigate the effect of low chronic exposures of the auditory system in children with a history of low blood lead levels, using an auditory electrophysiological test. Methods: Contemporary cross-sectional cohort. Study participants underwent tympanometry, pure tone and speech audiometry, transient evoked otoacoustic emissions, and brainstem auditory evoked potentials, with blood lead monitoring over a period of 35.5 months. The study included 130 children, with ages ranging from 18 months to 14 years, 5 months (mean age 6 years, 8 months ± 3 years, 2 months. Results: The mean time-integrated cumulative blood lead index was 12 µg/dL (SD ± 5.7, range:2.433. All participants had hearing thresholds equal to or below 20 dBHL and normal amplitudes of transient evoked otoacoustic emissions. No association was found between the absolute latencies of waves I, III, and V, the interpeak latencies I-III, III-V, and I-V, and the cumulative lead values. Conclusion: No evidence of toxic effects from chronic low lead exposures was observed on the auditory function of children living in a lead contaminated area.

  12. Leak detection in pipelines based on inverse transient analysis and mixed integer nonlinear programming[Includes the CSCE forum on professional practice and career development : 1. international engineering mechanics and materials specialty conference : 1. international/3. coastal, estuarine and offshore engineering specialty conference : 2. international/8. construction specialty conference

    Energy Technology Data Exchange (ETDEWEB)

    Shamloo, H.; Haghighi, A. [K.N. Toosi Univ. of Technology, Tehran (Iran, Islamic Republic of). Dept. of Civil Engineering

    2009-07-01

    The flow properties of pipes are affected by leaks. Leak detection methods based on hydraulic modelling and real data records aim to find a pipe's leak parameters including their number, location and size. Inverse Transient Analysis (ITA), generally in time domain, is a powerful approach to develop leak detection methods with considerable benefits. This paper introduced an ITA based leak detection method along with a numerical model developed for direct transient analysis of leaks in pipes using method of characteristics (MOC). Transient state flow was generated in pipe and the pressure fluctuations were sampled only at the end valve location. To minimize the effects of unsteadiness and uncertainties due to the numerical modeling and also practical problems caused by water hammer, the downstream end valve was considered to be closed gradually within a long enough time. Then, using the sampled data and a direct transient analysis model, a mixed integer nonlinear program was developed. A mixed genetic algorithm was used in which the binary chromosomes were decoded as mixed integer leak locations and real leak areas. In order to find unknown leak parameters in a pipe, an objective function was defined using the least squares criterion of differences between observed and calculated pressure heads at the valve location. The genetic algorithm was found to be a powerful and easy to use optimization tool to solve complicated mixed integer nonlinear program (MINLP) problems in leak detection. 24 refs., 1 tab., 7 figs.

  13. Average Transient Lifetime and Lyapunov Dimension for Transient Chaos in a High-Dimensional System

    Institute of Scientific and Technical Information of China (English)

    陈洪; 汤建新; 唐少炎; 向红; 陈新

    2001-01-01

    The average transient lifetime of a chaotic transient versus the Lyapunov dimension of a chaotic saddle is studied for high-dimensional nonlinear dynamical systems. Typically the average lifetime depends upon not only the system parameter but also the Lyapunov dimension of the chaotic saddle. The numerical example uses the delayed feedback differential equation.

  14. Raised Intracellular Calcium Contributes to Ischemia-Induced Depression of Evoked Synaptic Transmission.

    Directory of Open Access Journals (Sweden)

    Shirin Jalini

    Full Text Available Oxygen-glucose deprivation (OGD leads to depression of evoked synaptic transmission, for which the mechanisms remain unclear. We hypothesized that increased presynaptic [Ca2+]i during transient OGD contributes to the depression of evoked field excitatory postsynaptic potentials (fEPSPs. Additionally, we hypothesized that increased buffering of intracellular calcium would shorten electrophysiological recovery after transient ischemia. Mouse hippocampal slices were exposed to 2 to 8 min of OGD. fEPSPs evoked by Schaffer collateral stimulation were recorded in the stratum radiatum, and whole cell current or voltage clamp recordings were performed in CA1 neurons. Transient ischemia led to increased presynaptic [Ca2+]i, (shown by calcium imaging, increased spontaneous miniature EPSP/Cs, and depressed evoked fEPSPs, partially mediated by adenosine. Buffering of intracellular Ca2+ during OGD by membrane-permeant chelators (BAPTA-AM or EGTA-AM partially prevented fEPSP depression and promoted faster electrophysiological recovery when the OGD challenge was stopped. The blocker of BK channels, charybdotoxin (ChTX, also prevented fEPSP depression, but did not accelerate post-ischemic recovery. These results suggest that OGD leads to elevated presynaptic [Ca2+]i, which reduces evoked transmitter release; this effect can be reversed by increased intracellular Ca2+ buffering which also speeds recovery.

  15. Evoked Potentials and Human Intelligence.

    Science.gov (United States)

    Ertl, John P.; Schafer, Edward W. P.

    Evidence of a relationship between the electrical responses of the human brain and psychometric measure of intelligence is presented. These involuntary cortical responses, known as average evoked potentials are considered to be the electrical signs of information processing by the brain. The time delays of these responses from presentation of a…

  16. Evoked Emotions Predict Food Choice

    NARCIS (Netherlands)

    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.

  17. Evoked Emotions Predict Food Choice

    NARCIS (Netherlands)

    Dalenberg, J.R.; Gutjar, S.; Horst, ter G.J.; Graaf, de C.; Renken, R.; Jager, G.

    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. Th

  18. Prestimulus amplitudes modulate P1 latencies and evoked traveling alpha waves

    Directory of Open Access Journals (Sweden)

    Nicole Alexandra Himmelstoss

    2015-05-01

    Full Text Available Traveling waves have been well documented in the ongoing, and more recently also in the evoked EEG. In the present study we investigate what kind of physiological process might be responsible for inducing an evoked traveling wave. We used a semantic judgment task which already proved useful to study evoked traveling alpha waves that coincide with the appearance of the P1 component. We found that the P1 latency of the leading electrode is significantly correlated with prestimulus amplitude size and that this event is associated with a transient change in alpha frequency. We assume that cortical background excitability, as reflected by an increase in prestimulus amplitude, is responsible for the observed change in alpha frequency and the initiation of an evoked traveling trajectory.

  19. Vestibular-evoked myogenic potentials.

    Science.gov (United States)

    Colebatch, J G; Rosengren, S M; Welgampola, M S

    2016-01-01

    The vestibular-evoked myogenic potential (VEMP) is a short-latency potential evoked through activation of vestibular receptors using sound or vibration. It is generated by modulated electromyographic signals either from the sternocleidomastoid muscle for the cervical VEMP (cVEMP) or the inferior oblique muscle for the ocular VEMP (oVEMP). These reflexes appear to originate from the otolith organs and thus complement existing methods of vestibular assessment, which are mainly based upon canal function. This review considers the basis, methodology, and current applications of the cVEMP and oVEMP in the assessment and diagnosis of vestibular disorders, both peripheral and central. © 2016 Elsevier B.V. All rights reserved.

  20. Achieving Presence through Evoked Reality.

    Science.gov (United States)

    Pillai, Jayesh S; Schmidt, Colin; Richir, Simon

    2013-01-01

    The sense of "Presence" (evolving from "telepresence") has always been associated with virtual reality research and is still an exceptionally mystifying constituent. Now the study of presence clearly spans over various disciplines associated with cognition. This paper attempts to put forth a concept that argues that it's an experience of an "Evoked Reality (ER)" (illusion of reality) that triggers an "Evoked Presence (EP)" (sense of presence) in our minds. A Three Pole Reality Model is proposed to explain this phenomenon. The poles range from Dream Reality to Simulated Reality with Primary (Physical) Reality at the center. To demonstrate the relationship between ER and EP, a Reality-Presence Map is developed. We believe that this concept of ER and the proposed model may have significant applications in the study of presence, and in exploring the possibilities of not just virtual reality but also what we call "reality."

  1. Time Perception and Evoked Potentials

    Science.gov (United States)

    1988-07-01

    ARI Research Note 88-69 0 MitnS.Ktohe U.0 ... Ann-r (. Time Perception and Evoked Potentials Paul FraisseDT ( Lfniversit6 Rene Descartes E LECTE...JOHNSON 00L, [N Technical Dicctojr Cmad Research accomplished under contract for the Department of the Army C. Universite Rene Descartes , Paris )r...ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT. PROJECT. TASK Labrato-ire de Psychologie Experimental AREA• WORK UNIT NUMBERS Universite Rene Descartes

  2. Transient pupil response is modulated by contrast-based saliency.

    Science.gov (United States)

    Wang, Chin-An; Boehnke, Susan E; Itti, Laurent; Munoz, Douglas P

    2014-01-08

    The sudden appearance of a novel stimulus in the environment initiates a series of orienting responses that include coordinated shifts of gaze and attention, and also transient changes in pupil size. Although numerous studies have identified a significant effect of stimulus saliency on shifts of gaze and attention, saliency effects on pupil size are less understood. To examine salience-evoked pupil responses, we presented visual, auditory, or audiovisual stimuli while monkeys fixated a central visual spot. Transient pupil dilation was elicited after visual stimulus presentation regardless of target luminance relative to background, and auditory stimuli also evoked similar pupil responses. Importantly, the evoked pupil response was modulated by contrast-based saliency, with faster and larger pupil responses following the presentation of more salient stimuli. The initial transient component of pupil dilation was qualitatively similar to that evoked by weak microstimulation of the midbrain superior colliculus. The pupil responses elicited by audiovisual stimuli were well predicted by a linear summation of each modality response. Together, the results suggest that the transient pupil response, as one component of orienting, is modulated by contrast-based saliency, and the superior colliculus is likely involved in its coordination.

  3. Amplitude and phase equalization of stimuli for click evoked auditory brainstem responses.

    Science.gov (United States)

    Beutelmann, Rainer; Laumen, Geneviève; Tollin, Daniel; Klump, Georg M

    2015-01-01

    Although auditory brainstem responses (ABRs), the sound-evoked brain activity in response to transient sounds, are routinely measured in humans and animals there are often differences in ABR waveform morphology across studies. One possible reason may be the method of stimulus calibration. To explore this hypothesis, click-evoked ABRs were measured from seven ears in four Mongolian gerbils (Meriones unguiculatus) using three common spectrum calibration strategies: Minimum phase filter, linear phase filter, and no filter. The results show significantly higher ABR amplitude and signal-to-noise ratio, and better waveform resolution with the minimum phase filtered click than with the other strategies.

  4. Transient Ischemic Attack

    Medline Plus

    Full Text Available Transient Ischemic Attack TIA , or transient ischemic attack, is a "mini stroke" that occurs when a blood ... The only difference between a stroke and TIA is that with TIA the blockage is transient (temporary). ...

  5. Transient global amnesia mimics: Transient epileptic amnesia

    Directory of Open Access Journals (Sweden)

    Nicolas Nicastro

    2014-01-01

    Full Text Available We describe the case of a 79-year-old patient referred for suspected transient global amnesia, after an episode of anterograde amnesia which lasted 90 min. An EEG, performed after the episode, showed bilateral temporal electrographic seizures, orienting the diagnosis toward a transient epileptic amnesia. Transient epileptic amnesia is defined by temporal lobe epilepsy characterized by recurrent transient amnestic episodes of 30–90 min in duration, sometimes associated with olfactory hallucinations or oral automatisms. Response to antiepileptic drugs is excellent. We would like to raise awareness toward this epileptic amnesia when facing atypical or recurrent transient amnestic episodes.

  6. Cervical intraspinal microstimulation evokes robust forelimb movements before and after injury

    Science.gov (United States)

    Sunshine, Michael D.; Cho, Frances S.; Lockwood, Danielle R.; Fechko, Amber S.; Kasten, Michael R.; Moritz, Chet T.

    2013-06-01

    Objective. Intraspinal microstimulation (ISMS) is a promising method for reanimating paralyzed limbs following neurological injury. ISMS within the cervical and lumbar spinal cord is capable of evoking a variety of highly-functional movements prior to injury, but the ability of ISMS to evoke forelimb movements after cervical spinal cord injury is unknown. Here we examine the forelimb movements and muscles activated by cervical ISMS both before and after contusion injury. Approach. We documented the forelimb muscles activated and movements evoked via systematic stimulation of the rodent cervical spinal cord both before injury and three, six and nine weeks following a moderate C4/C5 lateralized contusion injury. Animals were anesthetized with isoflurane to permit construction of somatotopic maps of evoked movements and quantify evoked muscle synergies between cervical segments C3 and T1. Main results. When ISMS was delivered to the cervical spinal cord, a variety of responses were observed at 68% of locations tested, with a spatial distribution that generally corresponded to the location of motor neuron pools. Stimulus currents required to achieve movement and the number of sites where movements could be evoked were unchanged by spinal cord injury. A transient shift toward extension-dominated movements and restricted muscle synergies were observed at three and six weeks following injury, respectively. By nine weeks after injury, however, ISMS-evoked patterns were similar to spinally-intact animals. Significance. The results demonstrate the potential for cervical ISMS to reanimate hand and arm function following spinal cord injury. Robust forelimb movements can be evoked both before and during the chronic stages of recovery from a clinically relevant and sustained cervical contusion injury.

  7. Spike-triggered dendritic calcium transients depend on synaptic activity in the cricket giant interneurons.

    Science.gov (United States)

    Ogawa, Hiroto; Baba, Yoshichika; Oka, Kotaro

    2002-02-15

    The relationship between electrical activity and spike-induced Ca2+ increases in dendrites was investigated in the identified wind-sensitive giant interneurons in the cricket. We applied a high-speed Ca2+ imaging technique to the giant interneurons, and succeeded in recording the transient Ca2+ increases (Ca2+ transients) induced by a single action potential, which was evoked by presynaptic stimulus to the sensory neurons. The dendritic Ca2+ transients evoked by a pair of action potentials accumulated when spike intervals were shorter than 100 ms. The amplitude of the Ca2+ transients induced by a train of spikes depended on the number of action potentials. When stimulation pulses evoking the same numbers of action potentials were separately applied to the ipsi- or contra-lateral cercal sensory nerves, the dendritic Ca2+ transients induced by these presynaptic stimuli were different in their amplitude. Furthermore, the side of presynaptic stimulation that evoked larger Ca2+ transients depended on the location of the recorded dendritic regions. This result means that the spike-triggered Ca2+ transients in dendrites depend on postsynaptic activity. It is proposed that Ca2+ entry through voltage-dependent Ca2+ channels activated by the action potentials will be enhanced by excitatory synaptic inputs at the dendrites in the cricket giant interneurons.

  8. Current interruption transients calculation

    CERN Document Server

    Peelo, David F

    2014-01-01

    Provides an original, detailed and practical description of current interruption transients, origins, and the circuits involved, and how they can be calculated Current Interruption Transients Calculationis a comprehensive resource for the understanding, calculation and analysis of the transient recovery voltages (TRVs) and related re-ignition or re-striking transients associated with fault current interruption and the switching of inductive and capacitive load currents in circuits. This book provides an original, detailed and practical description of current interruption transients, origins,

  9. Diagnostic accuracy of evoked potentials for functional impairment after contusive spinal cord injury in adult rats.

    Science.gov (United States)

    Thirumala, Parthasarathy; Zhou, James; Krishnan, Rohan; Manem, Nihita; Umredkar, Shreya; Hamilton, D K; Balzer, Jeffrey R; Oudega, Martin

    2016-03-01

    Iatrogenic spinal cord injury (SCI) is a cause of potentially debilitating post-operative neurologic complications. Currently, intra-operative neurophysiological monitoring (IONM) via somatosensory evoked potentials and motor-evoked potentials is used to detect and prevent impending SCI. However, no empirically validated interventions exist to halt the progression of iatrogenic SCI once it is detected. This is in part due to the lack of a suitable translational model that mimics the circumstances surrounding iatrogenic SCI detected via IONM. Here, we evaluate a model of simulated contusive iatrogenic SCI detected via IONM in adult female Sprague-Dawley rats. We show that transient losses of somatosensory evoked potentials responses are 88.24% sensitive (95% confidence interval [CI] 63.53-98.20) and 80% specific (95% CI 51.91-95.43) for significant functional impairment following simulated iatrogenic SCI. Similarly, we show that transient losses in motor-evoked potentials responses are 70.83% sensitive (95% CI 48.91-87.33) and 100% specific (95% CI 62.91-100.00) for significant functional impairment following simulated iatrogenic SCI. These results indicate that our model is a suitable replica of the circumstances surrounding clinical iatrogenic SCI.

  10. Do film soundtracks contain nonlinear analogues to influence emotion?

    OpenAIRE

    Daniel T. Blumstein; Davitian, Richard; Kaye, Peter D.

    2010-01-01

    A variety of vertebrates produce nonlinear vocalizations when they are under duress. By their very nature, vocalizations containing nonlinearities may sound harsh and are somewhat unpredictable; observations that are consistent with them being particularly evocative to those hearing them. We tested the hypothesis that humans capitalize on this seemingly widespread vertebrate response by creating nonlinear analogues in film soundtracks to evoke particular emotions. We used lists of highly rega...

  11. Prony Analysis for Power System Transient Harmonics

    Directory of Open Access Journals (Sweden)

    Qi Li

    2007-01-01

    Full Text Available Proliferation of nonlinear loads in power systems has increased harmonic pollution and deteriorated power quality. Not required to have prior knowledge of existing harmonics, Prony analysis detects frequencies, magnitudes, phases, and especially damping factors of exponential decaying or growing transient harmonics. In this paper, Prony analysis is implemented to supervise power system transient harmonics, or time-varying harmonics. Further, to improve power quality when transient harmonics appear, the dominant harmonics identified from Prony analysis are used as the harmonic reference for harmonic selective active filters. Simulation results of two test systems during transformer energizing and induction motor starting confirm the effectiveness of the Prony analysis in supervising and canceling power system transient harmonics.

  12. CHAOTIC TRANSIENTS IN A CURVED FLUID CONVEYING TUBE

    Institute of Scientific and Technical Information of China (English)

    Ni Qiao; Wang Lin; Qian Qin

    2005-01-01

    The chaotic transients of a curved fluid conveying tube subjected to a nonlinear foundation are investigated. The assumption of the inextensibility of the tube is applied to derive the nonlinear differential equation of motion via the Newtonian approach, with the differential quadrature method used to discretize the curved tube model in the spatial domain. And the nonlinear dynamic motion equation is obtained. The numerical analysis shows that, the final steady states are sensitive to the initial system conditions in a large parameter region of the fluid speed. This phenomenon of chaotic transients is infrequent for fluid conveying tubes.

  13. Study on Nonlinear Dynamic Coefficients and Transient Vibration Response for a Non--contact Mechanical Seal%非接触机械密封的非线性动特性系数及瞬态振动响应分析

    Institute of Scientific and Technical Information of China (English)

    王技德; 张国渊

    2012-01-01

    Considering the tilt of a seal ring, the transient vibration response analysis model of a non--contact mechanical seal was presented. The model was consisted of transient Reynolds equation, motion equation and equation for solving the second--order nonlinear dynamic coefficients of the seal. With Euler method, the characteristic parameters of the transient vibration response were obtained, which included the axial vibration displacements and the angle--swing of the static ring. 14 nonlinear forces and 14 nonlinear overturning moment dynamic coefficients for the non--contact mechanical seal were calculated. The results show that the influences of the damping effects of the sealed fluid between the seal gaps on the axial vibration displacements and the angle--swing are linear. The film thickness distribution changes with the axial vibration of seal, which will lead to static ring swing, and the swing can also cause the axial vibration of the seal.%建立了考虑倾斜情况的弹性补偿单元支撑的非接触机械密封瞬态振动响应分析模型,该模型包括了瞬态Reynolds方程、运动方程以及二阶非线性动特性系数求解方程等。采用Euler法求解获得了非接触机械密封在轴向振动位移和静环倾角随时间变化时的瞬态振动响应特性。计算得到瞬态油膜力作用下的密封轴向力和倾覆力矩相关的14个动特性系数。结果表明:密封间隙内流体阻尼对密封副和摆动的影响是线性的;密封副瞬态振动影响油膜厚度分布,从而引起油膜压力分布发生变化,结果导致密封环发生摆动;密封副摆动同样也会引起密封轴向振动。

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

    Science.gov (United States)

    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.

  15. Stimulus-evoked outer segment changes in rod photoreceptors

    Science.gov (United States)

    Zhao, Xiaohui; Thapa, Damber; Wang, Benquan; Lu, Yiming; Gai, Shaoyan; Yao, Xincheng

    2016-06-01

    Rod-dominated transient retinal phototropism (TRP) has been recently observed in freshly isolated mouse and frog retinas. Comparative confocal microscopy and optical coherence tomography revealed that the TRP was predominantly elicited from the rod outer segment (OS). However, the biophysical mechanism of rod OS dynamics is still unknown. Mouse and frog retinal slices, which displayed a cross-section of retinal photoreceptors and other functional layers, were used to test the effect of light stimulation on rod OSs. Time-lapse microscopy revealed stimulus-evoked conformational changes of rod OSs. In the center of the stimulated region, the length of the rod OS shrunk, while in the peripheral region, the rod OS swung toward the center region. Our experimental observation and theoretical analysis suggest that the TRP may reflect unbalanced rod disc-shape changes due to localized visible light stimulation.

  16. Regulation of nerve-evoked contractions of rabbit vas deferens by acetylcholine.

    Science.gov (United States)

    Wallace, Audrey; Gabriel, Deborah; McHale, Noel G; Hollywood, Mark A; Thornbury, Keith D; Sergeant, Gerard P

    2015-09-01

    Stimulation of intramural nerves in the vas deferens of many species yields a classical biphasic contraction comprised of an initial fast component, mediated by P2X receptors and a second slower component, mediated by α1-adrenoceptors. It is also recognized that sympathetic nerve-mediated contractions of the vas deferens can be modulated by acetylcholine (Ach), however there is considerable disagreement in the literature regarding the precise contribution of cholinergic nerves to contraction of the vas deferens. In this study we examined the effect of cholinergic modulators on electric field stimulation (EFS)-evoked contractions of rabbit vas deferens and on cytosolic Ca(2+) levels in isolated vas deferens smooth muscle cells (VDSMC). The sustained component of EFS-evoked contractions was inhibited by atropine and by the selective M3R antagonist, 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP). EFS-evoked contractions were potentiated by Ach, carbachol (Cch), and neostigmine. The sustained phase of the EFS-evoked contraction was inhibited by prazosin, an α1-adrenoceptor antagonist and guanethidine, an inhibitor of noradrenaline release, even in the continued presence of Ach, Cch or neostigmine. The soluble guanylate cyclase (sGC) inhibitor, 1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one enhanced the amplitude of EFS-evoked contractions and reduced the inhibitory effects of 4-DAMP. Isolated VDSMC displayed spontaneous Ca(2+) oscillations, but did not respond to Cch. However, the α1-adrenoceptor agonist, phenylephrine, evoked a Ca(2+) transient and contracted the cells. These data suggest that EFS-evoked contractions of the rabbit vas deferens are potentiated by activation of M3 receptors and reduced by activation of a sGC-dependent inhibitory pathway.

  17. EVOKED CAVERNOUS ACTIVITY: NEUROANATOMIC IMPLICATIONS

    Science.gov (United States)

    Yilmaz, Ugur; Vicars, Brenda; Yang, Claire C.

    2013-01-01

    We investigated the autonomic innervation of the penis by using evoked cavernous activity (ECA). We recruited 7 males with thoracic spinal cord injury (SCI) and sexual dysfunction and 6 males who were scheduled to have pelvic surgery (PS), specifically non-nerve-sparing radical cystoprostatectomy. In the PS subjects, ECA was performed both pre- and postoperatively. The left median nerve was electrically stimulated and ECA was recorded with two concentric electromyography needles placed into the right and left cavernous bodies. We simultaneously recorded hand and foot sympathetic skin responses (SSRs) as controls. In the SCI group, all but one subject had reproducible hand SSRs. None of these subjects had ECA or foot SSRs. All the PS subjects had reproducible ECA and SSRs, both preoperatively and postoperatively. There was no difference in the latency and amplitude measurements of ECA and SSRs in the postoperative compared to the preoperative period (p>0.05). In conclusion, ECA is absent in men with SCI above the sympathetic outflow to the genitalia. In men following radical pelvic surgery, ECA is preserved, indicating the preservation of sympathetic fibers. PMID:19609298

  18. Ocular Vestibular Evoked Myogenic Potentials

    Directory of Open Access Journals (Sweden)

    Felipe, Lilian

    2014-01-01

    Full Text Available Introduction Diagnostic testing of the vestibular system is an essential component of treating patients with balance dysfunction. Until recently, testing methods primarily evaluated the integrity of the horizontal semicircular canal, which is only a portion of the vestibular system. Recent advances in technology have afforded clinicians the ability to assess otolith function through vestibular evoked myogenic potential (VEMP testing. VEMP testing from the inferior extraocular muscles of the eye has been the subject of interest of recent research. Objective To summarize recent developments in ocular VEMP testing. Results Recent studies suggest that the ocular VEMP is produced by otolith afferents in the superior division of the vestibular nerve. The ocular VEMP is a short latency potential, composed of extraocular myogenic responses activated by sound stimulation and registered by surface electromyography via ipsilateral otolithic and contralateral extraocular muscle activation. The inferior oblique muscle is the most superficial of the six extraocular muscles responsible for eye movement. Therefore, measurement of ocular VEMPs can be performed easily by using surface electrodes on the skin below the eyes contralateral to the stimulated side. Conclusion This new variation of the VEMP procedure may supplement conventional testing in difficult to test populations. It may also be possible to use this technique to evaluate previously inaccessible information on the vestibular system.

  19. [Intraoperative Visual Evoked Potential Monitoring].

    Science.gov (United States)

    Hayashi, Hironobu; Kawaguchi, Masahiko

    2015-05-01

    Visual evoked potential (VEP) is recorded from the back of the head, which is elicited by retinal stimulation transmitted through optic nerve, optic chiasm, optic tract lateral geniculate body, optic radiation and finally cortical visual area. VEP monitoring did not prevail since 1990s because marked intra-individual difference and instability of VEP recording limited the clinical usefulness under inhalation anesthetic management and techniques of VEP monitoring at the time. However, recent advances in techniques including a new light-stimulating device consisting of high-luminosity LEDs and induction of electroretinography to ascertain the arrival of the stimulus at the retina provided better conditions for stable VEP recording under general anesthesia. In addition, the introduction of total intravenous anesthesia using propofol is important for the successful VEP recordings because inhaled anesthetics have suppressive effect on VEP waveform. Intraoperative VEP has been considered to monitor the functional integrity of visual function during neurosurgical procedures, in which the optic pathway is at a risk of injury. Intraoperative VEP monitoring may allow us to detect reversible damage to the visual pathway intraoperatively and enable us to prevent permanent impairment.

  20. A Note on Transients in the SRO and ASRO Long-Period Data

    Science.gov (United States)

    Peterson, Jon

    1982-01-01

    Data users have occasionally observed pulse-like transients in the long-period waveforms recorded at the Seismic Research Observatories (SRO) and at the Modified High-Gain Long-Period (ASRO) stations. In a recent paper, Dziewonski et al (1981) reported transients associated with earthquake signals record at some SRO stations, and the authors ascribed these transients to an unpredictable nonlinear system response. While some transients in the SRO and ASRO data are indeed generated by a nonlinear response (clipping), others are the result of linear processes. All event-associated transients are predictable in the sense that they are produced by large impulsive body-wave signals.

  1. Nonlinear optics

    CERN Document Server

    Bloembergen, Nicolaas

    1996-01-01

    Nicolaas Bloembergen, recipient of the Nobel Prize for Physics (1981), wrote Nonlinear Optics in 1964, when the field of nonlinear optics was only three years old. The available literature has since grown by at least three orders of magnitude.The vitality of Nonlinear Optics is evident from the still-growing number of scientists and engineers engaged in the study of new nonlinear phenomena and in the development of new nonlinear devices in the field of opto-electronics. This monograph should be helpful in providing a historical introduction and a general background of basic ideas both for expe

  2. Fast relaxation transients in a kicked damped oscillator

    Energy Technology Data Exchange (ETDEWEB)

    Urquizu, Merce [Laboratori d' Estudis Geofisics ' Eduard Fontsere' , IEC, Barcelona (Spain); Correig, Antoni M. [Departament d' Astronomical i Meteorologia, Laboratori d' Estudis Geofisics Eduard Fontsere, UB Marti Franques 1, E-08028 Barcelona (Spain) and Laboratori d' Estudis Geofisics ' Eduard Fontsere' , IEC, Barcelona (Spain)]. E-mail: ton.correig@am.ub.es

    2007-08-15

    Although nonlinear relaxation transients are very common in nature, very few studies are devoted to its characterization, mainly due to its short time duration. In this paper, we present a study about the nature of relaxation transients in a kicked damped oscillator, in which transients are generated in terms of continuous fast changes in the parameters of the system. We have found that transient dynamics can be described, rather than in terms of bifurcation dynamics, in terms of instantaneous stretching factors, which are related to the stability of fixed points of the corresponding stroboscopic maps.

  3. Peripheral nerve injury increases glutamate-evoked calcium mobilization in adult spinal cord neurons

    Directory of Open Access Journals (Sweden)

    Doolen Suzanne

    2012-07-01

    Full Text Available Abstract Background Central sensitization in the spinal cord requires glutamate receptor activation and intracellular Ca2+ mobilization. We used Fura-2 AM bulk loading of mouse slices together with wide-field Ca2+ imaging to measure glutamate-evoked increases in extracellular Ca2+ to test the hypotheses that: 1. Exogenous application of glutamate causes Ca2+ mobilization in a preponderance of dorsal horn neurons within spinal cord slices taken from adult mice; 2. Glutamate-evoked Ca2+ mobilization is associated with spontaneous and/or evoked action potentials; 3. Glutamate acts at glutamate receptor subtypes to evoked Ca2+ transients; and 4. The magnitude of glutamate-evoked Ca2+ responses increases in the setting of peripheral neuropathic pain. Results Bath-applied glutamate robustly increased [Ca2+]i in 14.4 ± 2.6 cells per dorsal horn within a 440 x 330 um field-of-view, with an average time-to-peak of 27 s and decay of 112 s. Repeated application produced sequential responses of similar magnitude, indicating the absence of sensitization, desensitization or tachyphylaxis. Ca2+ transients were glutamate concentration-dependent with a Kd = 0.64 mM. Ca2+ responses predominantly occurred on neurons since: 1 Over 95% of glutamate-responsive cells did not label with the astrocyte marker, SR-101; 2 62% of fura-2 AM loaded cells exhibited spontaneous action potentials; 3 75% of cells that responded to locally-applied glutamate with a rise in [Ca2+]i also showed a significant increase in AP frequency upon a subsequent glutamate exposure; 4 In experiments using simultaneous on-cell recordings and Ca2+ imaging, glutamate elicited a Ca2+ response and an increase in AP frequency. AMPA/kainate (CNQX- and AMPA (GYKI 52466-selective receptor antagonists significantly attenuated glutamate-evoked increases in [Ca2+]i, while NMDA (AP-5, kainate (UBP-301 and class I mGluRs (AIDA did not. Compared to sham controls, peripheral nerve injury

  4. Evoked potentials in neuroinfections in children

    Directory of Open Access Journals (Sweden)

    V. N. Komantsev

    2013-01-01

    Full Text Available We present the results of the neurophysiological study in which 95 children with viral encephalitis and 30 children with meningitis (age from 2 up to 17 years undergo evoked potentials investigation. Some specific features of evoked potentials in neuroinfections have been shown to correlate with the course of disease and the age of the patients. We give a description of a logistic model of predicting outcomes in such patients by complex diagnostic method. We have found that evoked potentials may be successfully implemented in correcting the therapeutic strategies. Study of evoked potentials in neuroinfections in children can define the severity and extent of lesions and help to identify subclinical dysfunction and monitor the recovery processes under the therapy.

  5. Visual Evoked Potentials in Rett Syndrome

    Directory of Open Access Journals (Sweden)

    J. Gordon Millichap

    2015-11-01

    Full Text Available Investigators from the Boston Children's Hospital recorded pattern-reversal visual evoked potentials (VEPs in Mecp2 heterozygous female mice and in 34 girls with Rett syndrome (RTT.

  6. Transient drainage summary report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1996-09-01

    This report summarizes the history of transient drainage issues on the Uranium Mill Tailings Remedial Action (UMTRA) Project. It defines and describes the UMTRA Project disposal cell transient drainage process and chronicles UMTRA Project treatment of the transient drainage phenomenon. Section 4.0 includes a conceptual cross section of each UMTRA Project disposal site and summarizes design and construction information, the ground water protection strategy, and the potential for transient drainage.

  7. Nonlinear supratransmission

    Energy Technology Data Exchange (ETDEWEB)

    Geniet, F; Leon, J [Physique Mathematique et Theorique, CNRS-UMR 5825, 34095 Montpellier (France)

    2003-05-07

    A nonlinear system possessing a natural forbidden band gap can transmit energy of a signal with a frequency in the gap, as recently shown for a nonlinear chain of coupled pendulums (Geniet and Leon 2002 Phys. Rev. Lett. 89 134102). This process of nonlinear supratransmission, occurring at a threshold that is exactly predictable in many cases, is shown to have a simple experimental realization with a mechanical chain of pendulums coupled by a coil spring. It is then analysed in more detail. First we go to different (nonintegrable) systems which do sustain nonlinear supratransmission. Then a Josephson transmission line (a one-dimensional array of short Josephson junctions coupled through superconducting wires) is shown to also sustain nonlinear supratransmission, though being related to a different class of boundary conditions, and despite the presence of damping, finiteness, and discreteness. Finally, the mechanism at the origin of nonlinear supratransmission is found to be a nonlinear instability, and this is briefly discussed here.

  8. Do ambient urban odors evoke basic emotions?

    OpenAIRE

    Sandra Theresia Weber-Glass; Elisabeth eLingg; Eva eHeuberger

    2014-01-01

    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 respons...

  9. Practical Nonlinearities

    Science.gov (United States)

    2016-07-01

    Advanced Research Projects Agency (DARPA) Dynamics-Enabled Frequency Sources (DEFYS) program is focused on the convergence of nonlinear dynamics and...Early work in this program has shown that nonlinear dynamics can provide performance advantages. However, the pathway from initial results to...dependent nonlinear stiffness observed in these devices. This work is ongoing, and will continue through the final period of this program . Reference 9

  10. Nonlinear oscillations

    CERN Document Server

    Nayfeh, Ali Hasan

    1995-01-01

    Nonlinear Oscillations is a self-contained and thorough treatment of the vigorous research that has occurred in nonlinear mechanics since 1970. The book begins with fundamental concepts and techniques of analysis and progresses through recent developments and provides an overview that abstracts and introduces main nonlinear phenomena. It treats systems having a single degree of freedom, introducing basic concepts and analytical methods, and extends concepts and methods to systems having degrees of freedom. Most of this material cannot be found in any other text. Nonlinear Oscillations uses sim

  11. Nonlinear Science

    CERN Document Server

    Yoshida, Zensho

    2010-01-01

    This book gives a general, basic understanding of the mathematical structure "nonlinearity" that lies in the depths of complex systems. Analyzing the heterogeneity that the prefix "non" represents with respect to notions such as the linear space, integrability and scale hierarchy, "nonlinear science" is explained as a challenge of deconstruction of the modern sciences. This book is not a technical guide to teach mathematical tools of nonlinear analysis, nor a zoology of so-called nonlinear phenomena. By critically analyzing the structure of linear theories, and cl

  12. Nonlinear analysis

    CERN Document Server

    Nanda, Sudarsan

    2013-01-01

    "Nonlinear analysis" presents recent developments in calculus in Banach space, convex sets, convex functions, best approximation, fixed point theorems, nonlinear operators, variational inequality, complementary problem and semi-inner-product spaces. Nonlinear Analysis has become important and useful in the present days because many real world problems are nonlinear, nonconvex and nonsmooth in nature. Although basic concepts have been presented here but many results presented have not appeared in any book till now. The book could be used as a text for graduate students and also it will be useful for researchers working in this field.

  13. Tracking controller for robot manipulators via composite nonlinear feedback law

    Institute of Scientific and Technical Information of China (English)

    Peng Wendong; Su Jianbo

    2009-01-01

    A composite nonlinear feedback tracking controller for motion control of robot manipulators is de-scribed. The structure of the controller is composed of a composite nonlinear feedback law plus full robot nonlinear dynamics compensation. The stability is carried out in the presence of friction. The controller takes advantage of varying damping ratios induced by the composite nonlinear feedback control, so the transient performance of the closed-loop is remarkably improved. Simulation results demonstrate the feasibility of the proposed method.

  14. Exploring infrared neural stimulation with multimodal nonlinear imaging (Conference Presentation)

    Science.gov (United States)

    Adams, Wilson R.; Mahadevan-Jansen, Anita

    2017-02-01

    Infrared neural stimulation (INS) provides optical control of neural excitability using near to mid-infrared (mid-IR) light, which allows for spatially selective, artifact-free excitation without the introduction of exogenous agents or genetic modification. Although neural excitability is mediated by a transient temperature increase due to water absorption of IR energy, the molecular nature of IR excitability in neural tissue remains unknown. Current research suggests that transient changes in local tissue temperature give rise to a myriad of cellular responses that have been individually attributed to IR mediated excitability. To further elucidate the underlying biophysical mechanisms, we have begun work towards employing a novel multimodal nonlinear imaging platform to probe the molecular underpinnings of INS. Our imaging system performs coherent anti-Stokes Raman scattering (CARS), stimulated Raman scattering (SRS), two-photon excitation fluorescence (TPEF), second-harmonic generation (SHG) and thermal imaging into a single platform that allows for unprecedented co-registration of thermal and biochemical information in real-time. Here, we present our work leveraging CARS and SRS in acute thalamocortical brain slice preparations. We observe the evolution of lipid and protein-specific Raman bands during INS and electrically evoked activity in real-time. Combined with two-photon fluorescence and second harmonic generation, we offer insight to cellular metabolism and membrane dynamics during INS. Thermal imaging allows for the coregistration of acquired biochemical information with temperature information. Our work previews the versatility and capabilities of coherent Raman imaging combined with multiphoton imaging to observe biophysical phenomena for neuroscience applications.

  15. Characterization of music-evoked autobiographical memories.

    Science.gov (United States)

    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.

  16. Transient Voltage Recorder

    Science.gov (United States)

    Medelius, Pedro J. (Inventor); Simpson, Howard J. (Inventor)

    2002-01-01

    A voltage transient recorder can detect lightning induced transient voltages. The recorder detects a lightning induced transient voltage and adjusts input amplifiers to accurately record transient voltage magnitudes. The recorder stores voltage data from numerous monitored channels, or devices. The data is time stamped and can be output in real time, or stored for later retrieval. The transient recorder, in one embodiment, includes an analog-to-digital converter and a voltage threshold detector. When an input voltage exceeds a pre-determined voltage threshold, the recorder stores the incoming voltage magnitude and time of arrival. The recorder also determines if its input amplifier circuits clip the incoming signal or if the incoming signal is too low. If the input data is clipped or too low, the recorder adjusts the gain of the amplifier circuits to accurately acquire subsequent components of the lightning induced transients.

  17. Steady-state visual-evoked response to upright and inverted geometrical faces: a magnetoencephalography study.

    Science.gov (United States)

    Tsuruhara, Aki; Inui, Koji; Kakigi, Ryusuke

    2014-03-01

    The face is one of the most important visual stimuli in human life, and inverted faces are known to elicit different brain responses than upright faces. This study analyzed steady-state visual-evoked magnetic fields (SSVEFs) in eleven healthy participants when they viewed upright and inverted geometrical faces presented at 6Hz. Steady-state visual-evoked responses are useful measurements and have the advantages of robustness and a high signal-to-noise ratio. Spectrum analysis revealed clear responses to both upright and inverted faces at the fundamental stimulation frequency (6 Hz) and harmonics, i.e. SSVEFs. No significant difference was observed in the SSVEF amplitude at 6 Hz between upright and inverted faces, which was different from the transient visual-evoked response, N170. On the other hand, SSVEFs were delayed with the inverted face in the right temporal area, which was similar to N170 and the results of previous steady-state visual-evoked potentials studies. These results suggest that different mechanisms underlie the larger amplitude and delayed latency observed with face inversion, though further studies are needed to fully elucidate these mechanisms. Our study revealed that SSVEFs, which have practical advantages for measurements, could provide novel findings in human face processing.

  18. TRANSIENT ELECTRONICS CATEGORIZATION

    Science.gov (United States)

    2017-08-24

    definitions of what it means to be transient. The purpose of this technical report is to provide a background of the issues related to transient...In this section, we will attempt to identify these parameters and provide preliminary definitions for categories of transience behavior. Transient...programmable lifetimes. Ideally , such materials with expiration dates will deconstruct themselves into harmless and invisible remnants. The technology base

  19. Coupling capacitor voltage transformer: A model for electromagnetic transient studies

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, D.; Neves, W.L.A. [Department of Electrical Engineering, Federal University of Campina Grande, Av. Aprigio Veloso, 882 Bodocongo, 58.109-970 Campina Grande, PB (Brazil); Vasconcelos, J.C.A. [Companhia Hidro Eletrica do Sao Francisco, Rua Delmiro Gouveia, 333 Bongi, 50.761-901 Recife, PE (Brazil)

    2007-02-15

    In this work, an accurate coupling capacitor voltage transformer (CCVT) model for electromagnetic transient studies is presented. The model takes into account linear and nonlinear elements. A support routine was developed to compute the linear 230kV CCVT parameters (resistances, inductances and capacitances) from frequency response data. The magnetic core and surge arrester nonlinear characteristics were estimated from laboratory measurements as well. The model is used in connection with the electromagnetic transients program (EMTP) to predict the CCVT performance when it is submitted to transient overvoltages, as are the cases of voltages due to the ferroresonance phenomenon and circuit breaker switching. The difference between simulated and measured results is fairly small. Simulations had shown that transient overvoltages produced inside the CCVT, when a short circuit is cleared at the CCVT secondary side, are effectively damped out by the ferroresonance suppression circuit and the protection circuit. (author)

  20. The Zwicky Transient Facility

    CERN Document Server

    Bellm, Eric C

    2014-01-01

    The Zwicky Transient Facility (ZTF) is a next-generation optical synoptic survey that builds on the experience and infrastructure of the Palomar Transient Factory (PTF). Using a new 47 deg$^2$ survey camera, ZTF will survey more than an order of magnitude faster than PTF to discover rare transients and variables. I describe the survey and the camera design. Searches for young supernovae, fast transients, counterparts to gravitational-wave detections, and rare variables will benefit from ZTF's high cadence, wide area survey.

  1. Brain correlates of music-evoked emotions.

    Science.gov (United States)

    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.

  2. Evoking prescribed spike times in stochastic neurons

    Science.gov (United States)

    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.

  3. Animation of natural scene by virtual eye-movements evokes high precision and low noise in V1 neurons.

    Science.gov (United States)

    Baudot, Pierre; Levy, Manuel; Marre, Olivier; Monier, Cyril; Pananceau, Marc; Frégnac, Yves

    2013-01-01

    Synaptic noise is thought to be a limiting factor for computational efficiency in the brain. In visual cortex (V1), ongoing activity is present in vivo, and spiking responses to simple stimuli are highly unreliable across trials. Stimulus statistics used to plot receptive fields, however, are quite different from those experienced during natural visuomotor exploration. We recorded V1 neurons intracellularly in the anaesthetized and paralyzed cat and compared their spiking and synaptic responses to full field natural images animated by simulated eye-movements to those evoked by simpler (grating) or higher dimensionality statistics (dense noise). In most cells, natural scene animation was the only condition where high temporal precision (in the 10-20 ms range) was maintained during sparse and reliable activity. At the subthreshold level, irregular but highly reproducible membrane potential dynamics were observed, even during long (several 100 ms) "spike-less" periods. We showed that both the spatial structure of natural scenes and the temporal dynamics of eye-movements increase the signal-to-noise ratio by a non-linear amplification of the signal combined with a reduction of the subthreshold contextual noise. These data support the view that the sparsening and the time precision of the neural code in V1 may depend primarily on three factors: (1) broadband input spectrum: the bandwidth must be rich enough for recruiting optimally the diversity of spatial and time constants during recurrent processing; (2) tight temporal interplay of excitation and inhibition: conductance measurements demonstrate that natural scene statistics narrow selectively the duration of the spiking opportunity window during which the balance between excitation and inhibition changes transiently and reversibly; (3) signal energy in the lower frequency band: a minimal level of power is needed below 10 Hz to reach consistently the spiking threshold, a situation rarely reached with visual dense

  4. Nonlinear flow model for well production in an underground formation

    Directory of Open Access Journals (Sweden)

    J. C. Guo

    2013-05-01

    Full Text Available Fluid flow in underground formations is a nonlinear process. In this article we modelled the nonlinear transient flow behaviour of well production in an underground formation. Based on Darcy's law and material balance equations, we used quadratic pressure gradients to deduce diffusion equations and discuss the origins of nonlinear flow issues. By introducing an effective-well-radius approach that considers skin factor, we established a nonlinear flow model for both gas and liquid (oil or water. The liquid flow model was solved using a semi-analytical method, while the gas flow model was solved using numerical simulations because the diffusion equation of gas flow is a stealth function of pressure. For liquid flow, a series of standard log-log type curves of pressure transients were plotted and nonlinear transient flow characteristics were analyzed. Qualitative and quantitative analyses were used to compare the solutions of the linear and nonlinear models. The effect of nonlinearity upon pressure transients should not be ignored. For gas flow, pressure transients were simulated and compared with oil flow under the same formation and well conditions, resulting in the conclusion that, under the same volume rate production, oil wells demand larger pressure drops than gas wells. Comparisons between theoretical data and field data show that nonlinear models will describe fluid flow in underground formations realistically and accurately.

  5. Spatial luminance contrast sensitivity measured with transient VEP: comparison with psychophysics and evidence of multiple mechanisms.

    Science.gov (United States)

    Souza, Givago S; Gomes, Bruno D; Saito, Cézar A; da Silva Filho, Manoel; Silveira, Luiz Carlos L

    2007-07-01

    To compare the spatial luminance contrast sensitivity function (CSF) obtained with transient visual evoked potentials (VEPs) with that obtained with psychophysical measurements. The stimuli consisted of horizontal luminance gratings. In the VEP experiments, 0.4, 0.8, 2, 4, 8, and 10 cpd of spatial frequency were used, at 1 Hz square-wave contrast-reversal mode. Eight to 10 Michelson contrasts were used at each spatial frequency. Contrast thresholds were estimated from extrapolation of contrast response functions. Psychophysical sensitivities were obtained with spatial gratings of 0.4, 0.8, 1, 2, 4, 6, 8, and 10 cpd and presented at 1 Hz square-wave contrast-reversal or stationary mode (dynamic and static presentation, respectively). CSF tuning was estimated by calculating the ratio between peak sensitivity and the sensitivity at 0.4 cpd. In all subjects tested (n = 6), VEP contrast-response functions showed nonlinearities-namely, amplitude saturation and double-slope amplitude functions that occurred at low and medium-to-high spatial frequencies, respectively. Mean electrophysiological and psychophysical CSFs peaked at 2 cpd. CSF tuning for electrophysiology and dynamic and static psychophysics were, respectively, 1.08, 1.11, and 1.31. Correlation coefficients (r(2)) between electrophysiological CSF and dynamic or static psychophysical CSF were, respectively, 0.81 and 0.45. Electrophysiological and psychophysical CSFs correlated more positively when temporal presentation was similar. Spatial frequencies higher than 2 cpd showed that at least two visual pathways sum their activities at high contrasts. At low contrast levels, the results suggest that the transient VEP is dominated by the magnocellular (M) pathway.

  6. [Effect of sleep deprivation on visual evoked potentials and brain stem auditory evoked potentials in epileptics].

    Science.gov (United States)

    Urumova, L T; Kovalenko, G A; Tsunikov, A I; Sumskiĭ, L I

    1984-01-01

    The article reports on the first study of the evoked activity of the brain in epileptic patients (n = 20) following sleep deprivation. An analysis of the data obtained has revealed a tendency to the shortening of the peak latent intervals of visual evoked potentials in the range of 100-200 mu sec and the V component and the interpeak interval III-V of evoked auditory trunk potentials in patients with temporal epilepsy. The phenomenon may indicate the elimination of stabilizing control involving the specific conductive pathways and, possibly, an accelerated conduction of a specific sensor signal.

  7. Nonlinear Reconstruction

    CERN Document Server

    Zhu, Hong-Ming; Pen, Ue-Li; Chen, Xuelei; Yu, Hao-Ran

    2016-01-01

    We present a direct approach to non-parametrically reconstruct the linear density field from an observed non-linear map. We solve for the unique displacement potential consistent with the non-linear density and positive definite coordinate transformation using a multigrid algorithm. We show that we recover the linear initial conditions up to $k\\sim 1\\ h/\\mathrm{Mpc}$ with minimal computational cost. This reconstruction approach generalizes the linear displacement theory to fully non-linear fields, potentially substantially expanding the BAO and RSD information content of dense large scale structure surveys, including for example SDSS main sample and 21cm intensity mapping.

  8. Nonlinear optics

    CERN Document Server

    Boyd, Robert W

    2013-01-01

    Nonlinear Optics is an advanced textbook for courses dealing with nonlinear optics, quantum electronics, laser physics, contemporary and quantum optics, and electrooptics. Its pedagogical emphasis is on fundamentals rather than particular, transitory applications. As a result, this textbook will have lasting appeal to a wide audience of electrical engineering, physics, and optics students, as well as those in related fields such as materials science and chemistry.Key Features* The origin of optical nonlinearities, including dependence on the polarization of light* A detailed treatment of the q

  9. Color Evoked Potentials in Adults and Infants.

    Science.gov (United States)

    White, Carroll T.; And Others

    This paper discusses recent studies of the adult visual evoked potential (VEP) which have indicated that specific components of the complex waveform obtained are related to the three basic color processes, and that these components interact in ways that seem to agree with opponent-colors phenomena. The components identified as being related to the…

  10. Transient cognitive dynamics, metastability, and decision making.

    Directory of Open Access Journals (Sweden)

    Mikhail I Rabinovich

    2008-05-01

    Full Text Available The idea that cognitive activity can be understood using nonlinear dynamics has been intensively discussed at length for the last 15 years. One of the popular points of view is that metastable states play a key role in the execution of cognitive functions. Experimental and modeling studies suggest that most of these functions are the result of transient activity of large-scale brain networks in the presence of noise. Such transients may consist of a sequential switching between different metastable cognitive states. The main problem faced when using dynamical theory to describe transient cognitive processes is the fundamental contradiction between reproducibility and flexibility of transient behavior. In this paper, we propose a theoretical description of transient cognitive dynamics based on the interaction of functionally dependent metastable cognitive states. The mathematical image of such transient activity is a stable heteroclinic channel, i.e., a set of trajectories in the vicinity of a heteroclinic skeleton that consists of saddles and unstable separatrices that connect their surroundings. We suggest a basic mathematical model, a strongly dissipative dynamical system, and formulate the conditions for the robustness and reproducibility of cognitive transients that satisfy the competing requirements for stability and flexibility. Based on this approach, we describe here an effective solution for the problem of sequential decision making, represented as a fixed time game: a player takes sequential actions in a changing noisy environment so as to maximize a cumulative reward. As we predict and verify in computer simulations, noise plays an important role in optimizing the gain.

  11. Methylglyoxal evokes pain by stimulating TRPA1.

    Directory of Open Access Journals (Sweden)

    David A Andersson

    Full Text Available Diabetic neuropathy is a severe complication of long-standing diabetes and one of the major etiologies of neuropathic pain. Diabetes is associated with an increased formation of reactive oxygen species and the electrophilic dicarbonyl compound methylglyoxal (MG. Here we show that MG stimulates heterologously expressed TRPA1 in CHO cells and natively expressed TRPA1 in MDCK cells and DRG neurons. MG evokes [Ca(2+]i-responses in TRPA1 expressing DRG neurons but is without effect in neurons cultured from Trpa1(-/- mice. Consistent with a direct, intracellular action, we show that methylglyoxal is significantly more potent as a TRPA1 agonist when applied to the intracellular face of excised membrane patches than to intact cells. Local intraplantar administration of MG evokes a pain response in Trpa1(+/+ but not in Trpa1(-/- mice. Furthermore, persistently increased MG levels achieved by two weeks pharmacological inhibition of glyoxalase-1 (GLO-1, the rate-limiting enzyme responsible for detoxification of MG, evokes a progressive and marked thermal (cold and heat and mechanical hypersensitivity in wildtype but not in Trpa1(-/- mice. Our results thus demonstrate that TRPA1 is required both for the acute pain response evoked by topical MG and for the long-lasting pronociceptive effects associated with elevated MG in vivo. In contrast to our observations in DRG neurons, MG evokes indistinguishable [Ca(2+]i-responses in pancreatic β-cells cultured from Trpa1(+/+ and Trpa1(-/- mice. In vivo, the TRPA1 antagonist HC030031 impairs glucose clearance in the glucose tolerance test both in Trpa1(+/+ and Trpa1(-/- mice, indicating a non-TRPA1 mediated effect and suggesting that results obtained with this compound should be interpreted with caution. Our results show that TRPA1 is the principal target for MG in sensory neurons but not in pancreatic β-cells and that activation of TRPA1 by MG produces a painful neuropathy with the behavioral hallmarks of diabetic

  12. Nonlinear optimization

    CERN Document Server

    Ruszczynski, Andrzej

    2011-01-01

    Optimization is one of the most important areas of modern applied mathematics, with applications in fields from engineering and economics to finance, statistics, management science, and medicine. While many books have addressed its various aspects, Nonlinear Optimization is the first comprehensive treatment that will allow graduate students and researchers to understand its modern ideas, principles, and methods within a reasonable time, but without sacrificing mathematical precision. Andrzej Ruszczynski, a leading expert in the optimization of nonlinear stochastic systems, integrates t

  13. External QX-314 inhibits evoked cranial primary afferent synaptic transmission independent of TRPV1.

    Science.gov (United States)

    Hofmann, Mackenzie E; Largent-Milnes, Tally M; Fawley, Jessica A; Andresen, Michael C

    2014-12-01

    The cell-impermeant lidocaine derivative QX-314 blocks sodium channels via intracellular mechanisms. In somatosensory nociceptive neurons, open transient receptor potential vanilloid type 1 (TRPV1) receptors provide a transmembrane passageway for QX-314 to produce long-lasting analgesia. Many cranial primary afferents express TRPV1 at synapses on neurons in the nucleus of the solitary tract and caudal trigeminal nucleus (Vc). Here, we investigated whether QX-314 interrupts neurotransmission from primary afferents in rat brain-stem slices. Shocks to the solitary tract (ST) activated highly synchronous evoked excitatory postsynaptic currents (ST-EPSCs). Application of 300 μM QX-314 increased the ST-EPSC latency from TRPV1+ ST afferents, but, surprisingly, it had similar actions at TRPV1- ST afferents. Continued exposure to QX-314 blocked evoked ST-EPSCs at both afferent types. Neither the time to onset of latency changes nor the time to ST-EPSC failure differed between responses for TRPV1+ and TRPV1- inputs. Likewise, the TRPV1 antagonist capsazepine failed to prevent the actions of QX-314. Whereas QX-314 blocked ST-evoked release, the frequency and amplitude of spontaneous EPSCs remained unaltered. In neurons exposed to QX-314, intracellular current injection evoked action potentials suggesting a presynaptic site of action. QX-314 acted similarly at Vc neurons to increase latency and block EPSCs evoked from trigeminal tract afferents. Our results demonstrate that QX-314 blocked nerve conduction in cranial primary afferents without interrupting the glutamate release mechanism or generation of postsynaptic action potentials. The TRPV1 independence suggests that QX-314 either acted extracellularly or more likely entered these axons through an undetermined pathway common to all cranial primary afferents.

  14. Perturbation analysis of transient population dynamics using matrix projection models

    DEFF Research Database (Denmark)

    Stott, Iain

    2016-01-01

    Non-stable populations exhibit short-term transient dynamics: size, growth and structure that are unlike predicted long-term asymptotic stable, stationary or equilibrium dynamics. Understanding transient dynamics of non-stable populations is important for designing effective population management...... strategies, predicting the responses of populations to environmental change or disturbance, and understanding population processes and life-history evolution in variable environments. Transient perturbation analyses are vital tools for achieving these aims. They assess how transient dynamics are affected...... of model being analysed, the perturbation structure, the population response of interest, nonlinear response to perturbation, standardization for asymptotic dynamics, the initial population structure, and the time frame of interest. I discuss these with reference to the application of transient...

  15. Global Transient Stability and Voltage Regulation for Multimachine Power Systems

    DEFF Research Database (Denmark)

    Gordon, Mark; Hill, David J.

    2008-01-01

    This paper addresses simultaneously the major fundamental and difficult issues of nonlinearity, uncertainty, dimensionality and globality to derive performance enhancing power system stability control. The main focus is on simultaneous enhancement of transient stability and voltage regulation...... law is implemented to coordinate transient stabilizer and voltage regulator for each machine. Digital simulation studies show that global control scheme achieves unified transient stability and voltage regulation in the presence of parametric uncertainties and significant sudden changes in the network...... of power systems. This problem arises from the practical concern that both frequency and voltage control are important indices of power system control and operation but they are ascribed to different stages of system operation, i.e. the transient and post transient period respectively. The Direct Feedback...

  16. Nonlinear channelizer

    Science.gov (United States)

    In, Visarath; Longhini, Patrick; Kho, Andy; Neff, Joseph D.; Leung, Daniel; Liu, Norman; Meadows, Brian K.; Gordon, Frank; Bulsara, Adi R.; Palacios, Antonio

    2012-12-01

    The nonlinear channelizer is an integrated circuit made up of large parallel arrays of analog nonlinear oscillators, which, collectively, serve as a broad-spectrum analyzer with the ability to receive complex signals containing multiple frequencies and instantaneously lock-on or respond to a received signal in a few oscillation cycles. The concept is based on the generation of internal oscillations in coupled nonlinear systems that do not normally oscillate in the absence of coupling. In particular, the system consists of unidirectionally coupled bistable nonlinear elements, where the frequency and other dynamical characteristics of the emergent oscillations depend on the system's internal parameters and the received signal. These properties and characteristics are being employed to develop a system capable of locking onto any arbitrary input radio frequency signal. The system is efficient by eliminating the need for high-speed, high-accuracy analog-to-digital converters, and compact by making use of nonlinear coupled systems to act as a channelizer (frequency binning and channeling), a low noise amplifier, and a frequency down-converter in a single step which, in turn, will reduce the size, weight, power, and cost of the entire communication system. This paper covers the theory, numerical simulations, and some engineering details that validate the concept at the frequency band of 1-4 GHz.

  17. Transient Ischemic Attack

    Medline Plus

    Full Text Available ... TIA , or transient ischemic attack, is a "mini stroke" that occurs when a blood clot blocks an ... a short time. The only difference between a stroke and TIA is that with TIA the blockage ...

  18. Transient Ischemic Attack

    Medline Plus

    Full Text Available ... TIA , or transient ischemic attack, is a "mini stroke" that occurs when a blood clot blocks an ... a short time. The only difference between a stroke and TIA is that with TIA the blockage ...

  19. Searches for radio transients

    CERN Document Server

    Bhat, N D R

    2011-01-01

    Exploration of the transient Universe is an exciting and fast-emerging area within radio astronomy. Known transient phenomena range in time scales from sub-nanoseconds to years or longer, thus spanning a huge range in time domain and hinting a rich diversity in their underlying physical processes. Transient phenomena are likely locations of explosive or dynamic events and they offer tremendous potential to uncover new physics and astrophysics. A number of upcoming next-generation radio facilities and recent advances in computing and instrumentation have provided a much needed impetus for this field which has remained a relatively uncharted territory for the past several decades. In this paper we focus mainly on the class of phenomena that occur on very short time scales (i.e. from $\\sim$ milliseconds to $\\sim$ nanoseconds), known as {\\it fast transients}, the detections of which involve considerable signal processing and data management challenges, given the high time and frequency resolutions required in the...

  20. Transient Ischemic Attack

    Medline Plus

    Full Text Available ... Ischemic Attack TIA , or transient ischemic attack, is a "mini stroke" that occurs when a blood clot blocks an artery for a short time. The only difference between a stroke ...

  1. Transient receptor potential ankyrin 1 channel localized to non-neuronal airway cells promotes non-neurogenic inflammation

    DEFF Research Database (Denmark)

    Nassini, Romina; Pedretti, Pamela; Moretto, Nadia;

    2012-01-01

    The transient receptor potential ankyrin 1 (TRPA1) channel, localized to airway sensory nerves, has been proposed to mediate airway inflammation evoked by allergen and cigarette smoke (CS) in rodents, via a neurogenic mechanism. However the limited clinical evidence for the role of neurogenic...... and fibroblasts, acrolein and CS extract evoked IL-8 release, a response selectively reduced by TRPA1 antagonists. Capsaicin, agonist of the transient receptor potential vanilloid 1 (TRPV1), a channel co-expressed with TRPA1 by airway sensory nerves, and acrolein or CS (TRPA1 agonists), or the neuropeptide...

  2. Transient multivariable sensor evaluation

    Energy Technology Data Exchange (ETDEWEB)

    Vilim, Richard B.; Heifetz, Alexander

    2017-02-21

    A method and system for performing transient multivariable sensor evaluation. The method and system includes a computer system for identifying a model form, providing training measurement data, generating a basis vector, monitoring system data from sensor, loading the system data in a non-transient memory, performing an estimation to provide desired data and comparing the system data to the desired data and outputting an alarm for a defective sensor.

  3. Transient multivariable sensor evaluation

    Science.gov (United States)

    Vilim, Richard B.; Heifetz, Alexander

    2017-02-21

    A method and system for performing transient multivariable sensor evaluation. The method and system includes a computer system for identifying a model form, providing training measurement data, generating a basis vector, monitoring system data from sensor, loading the system data in a non-transient memory, performing an estimation to provide desired data and comparing the system data to the desired data and outputting an alarm for a defective sensor.

  4. Early visual evoked potentials in callosal agenesis.

    Science.gov (United States)

    Barr, Melodie S; Hamm, Jeff P; Kirk, Ian J; Corballis, Michael C

    2005-11-01

    Three participants with callosal agenesis and 12 neurologically normal participants were tested on a simple reaction time task, with visual evoked potentials collected using a high-density 128-channel system. Independent-components analyses were performed on the averaged visual evoked potentials to isolate the components of interest. Contrary to previous research with acallosals, evidence of ipsilateral activation was present in all 3 participants. Although ipsilateral visual components were present in all 4 unilateral conditions in the 2 related acallosal participants, in the 3rd, these were present only in the crossed visual field-hand conditions and not in the uncrossed conditions. Suggestions are made as to why these results differ from earlier findings and as to the neural mechanisms facilitating this ipsilateral activation.

  5. Changes of brainstem auditory and somatosensory evoked

    Institute of Scientific and Technical Information of China (English)

    Yang Jian

    2000-01-01

    Objective: to investigate the characteristics and clinical value of evoked potentials in late infantile form of metachromatic leukodystrophy. Methods: Brainstem auditory, and somatosensory evoked potentials were recorded in 6 patients, and compared with the results of CT scan. Results: All of the 6 patients had abnormal results of BAEP and MNSEP. The main abnormal parameters in BAEP were latency prolongation in wave I, inter-peak latency prolongation in Ⅰ-Ⅲ and Ⅰ-Ⅴ. The abnormal features of MNSEP were low amplitude and absence of wave N9, inter-Peak latency prolongation in Ng-N13 and N13-N20, but no significant change of N20 amplitude. The results also revealed that abnormal changes in BAEP and MNSEP were earlier than that in CT. Conclusion: The detection of BAEP and MNSEP in late infantile form of metachromatic leukodystrophy might early reveal the abnormality of conductive function in nervous system and might be a useful method in diagnosis.

  6. Modeling auditory evoked potentials to complex stimuli

    DEFF Research Database (Denmark)

    Rønne, Filip Munch

    The auditory evoked potential (AEP) is an electrical signal that can be recorded from electrodes attached to the scalp of a human subject when a sound is presented. The signal is considered to reflect neural activity in response to the acoustic stimulation and is a well established clinical...... clinically and in research towards using realistic and complex stimuli, such as speech, to electrophysiologically assess the human hearing. However, to interpret the AEP generation to complex sounds, the potential patterns in response to simple stimuli needs to be understood. Therefore, the model was used...... to simulate auditory brainstem responses (ABRs) evoked by classic stimuli like clicks, tone bursts and chirps. The ABRs to these simple stimuli were compared to literature data and the model was shown to predict the frequency dependence of tone-burst ABR wave-V latency and the level-dependence of ABR wave...

  7. Thought-evoking approaches in engineering problems

    CERN Document Server

    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’,...

  8. Nonlinear Spectroscopy.

    Science.gov (United States)

    1985-03-20

    Genack and R. G. Brewer, Physical Review B17 , 2821 (1978). 3. Optical Coherent Transients by Laser Frequency Switching: Subnanosecond Studies R. G...field as witnessed in previous studies. 12 13 By contour integration, the Doppler integral of Bt(t) is * 21 6 T, 4 ei A <Bl(t)> r -- Ng w el[ _A ?-0/2

  9. Nonlinear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Turchetti, G. (Bologna Univ. (Italy). Dipt. di Fisica)

    1989-01-01

    Research in nonlinear dynamics is rapidly expanding and its range of applications is extending beyond the traditional areas of science where it was first developed. Indeed while linear analysis and modelling, which has been very successful in mathematical physics and engineering, has become a mature science, many elementary phenomena of intrinsic nonlinear nature were recently experimentally detected and investigated, suggesting new theoretical work. Complex systems, as turbulent fluids, were known to be governed by intrinsically nonlinear laws since a long time ago, but received purely phenomenological descriptions. The pioneering works of Boltzmann and Poincare, probably because of their intrinsic difficulty, did not have a revolutionary impact at their time; it is only very recently that their message is reaching a significant number of mathematicians and physicists. Certainly the development of computers and computer graphics played an important role in developing geometric intuition of complex phenomena through simple numerical experiments, while a new mathematical framework to understand them was being developed.

  10. Auditory evoked potentials and multiple sclerosis

    OpenAIRE

    Carla Gentile Matas; Sandro Luiz de Andrade Matas; Caroline Rondina Salzano de Oliveira; Isabela Crivellaro Gonçalves

    2010-01-01

    Multiple sclerosis (MS) is an inflammatory, demyelinating disease that can affect several areas of the central nervous system. Damage along the auditory pathway can alter its integrity significantly. Therefore, it is important to investigate the auditory pathway, from the brainstem to the cortex, in individuals with MS. OBJECTIVE: The aim of this study was to characterize auditory evoked potentials in adults with MS of the remittent-recurrent type. METHOD: The study comprised 25 individuals w...

  11. Brain stem evoked response audiometry A Review

    OpenAIRE

    Balasubramanian Thiagarajan

    2015-01-01

    Brain stem evoked response audiometry (BERA) is a useful objective assessement of hearing. Major advantage of this procedure is its ability to test even infants in whom conventional audiometry may not be useful. This investigation can be used as a screening test for deafness in high risk infants. Early diagnosis and rehabilitation will reduce disability in these children. This article attempts to review the published literature on this subject. Methadology: Internet search using goog...

  12. Evoked Effective Connectivity of the Human Neocortex

    OpenAIRE

    Entz, László; Tóth, Emília; Keller, Corey J.; Bickel, Stephan; Groppe, David M.; Fabó, Dániel; Kozák, Lajos R.; Eroőss, Loránd; Ulbert, István; Mehta, Ashesh D.

    2014-01-01

    The role of cortical connectivity in brain function and pathology is increasingly being recognized. While in vivo magnetic resonance imaging studies have provided important insights into anatomical and functional connectivity, these methodologies are limited in their ability to detect electrophysiological activity and the causal relationships that underlie effective connectivity. Here, we describe results of cortico-cortical evoked potential (CCEP) mapping using single pulse electrical stimul...

  13. Evoked Brain Activity and Personnel Performance

    Science.gov (United States)

    1987-10-01

    Eysenck and Barrett (1985) reviewed at considerable length this error rate theory , as well as other proposed interactions of psychophysiology and...Include Security CItuification) EVOKED BRAIN ACTIVITY AND PERSONNEL PERFORMANCE 12 PERSONAL AUTHOR(S) Lewis, G. W., and Sorenson, R. C. 13a. TYPE...aptitude tests and the MM PI and other personality tests were developed along with tests designed for military purposes. The latter include the Armed

  14. Brainstem auditory evoked response: application in neurology

    Directory of Open Access Journals (Sweden)

    Carlos A. M. Guerreiro

    1982-03-01

    Full Text Available The tecnique that we use for eliciting brainstem auditory evoked responses (BAERs is described. BAERs are a non-invasive and reliable clinical test when carefully performed. This test is indicated in the evaluation of disorders which may potentially involve the brainstem such as coma, multiple sclerosis posterior fossa tumors and others. Unsuspected lesions with normal radiologic studies (including CT-scan can be revealed by the BAER.

  15. Simulation of transients of high amplitude in pipe systems

    NARCIS (Netherlands)

    Boersma, J.M.; Looijmans, K.N.H.

    1999-01-01

    Fast high-amplitude transients ask for a non-linear modelling approach in which large density variations and heat exchange can be considered. Operation of safety-valves, relief valves, the occurrence of valve failure and the start-up or shutdown of rotating equipment in industrial pipe systems can l

  16. Pressure-induced basilar membrane position shifts and the stimulus-evoked potentials in the low-frequency region of the guinea pig cochlea

    NARCIS (Netherlands)

    Fridberger, A; vanMaarseveen, JTPW; Scarfone, E; Ulfendahl, M; Flock, B; Flock, A

    1997-01-01

    We have used the guinea pig isolated temporal bone preparation to investigate changes in the nonlinear properties of the tone-evoked cochlear potentials during reversible step displacements of the basilar membrane towards either the scala tympani or the scala vestibuli. The position shifts were prod

  17. Steady and transient least square solvers for thermal problems

    Science.gov (United States)

    Padovan, Joe

    1987-01-01

    This paper develops a hierarchical least square solution algorithm for highly nonlinear heat transfer problems. The methodology's capability is such that both steady and transient implicit formulations can be handled. This includes problems arising from highly nonlinear heat transfer systems modeled by either finite-element or finite-difference schemes. The overall procedure developed enables localized updating, iteration, and convergence checking as well as constraint application. The localized updating can be performed at a variety of hierarchical levels, i.e., degree of freedom, substructural, material-nonlinear groups, and/or boundary groups. The choice of such partitions can be made via energy partitioning or nonlinearity levels as well as by user selection. Overall, this leads to extremely robust computational characteristics. To demonstrate the methodology, problems are drawn from nonlinear heat conduction. These are used to quantify the robust capabilities of the hierarchical least square scheme.

  18. Individual cochlear delays measured with tone-burst-evoked otoacoustic emissions

    DEFF Research Database (Denmark)

    Pigasse, Gilles; Harte, James; Dau, Torsten

    averages. This work aims to assess the individual variability in cochlear delay. Tone-burst evoked otoacoustic emissions (TBOAEs) are used in this study to estimate cochlear delay. The OAE is analysed by separating the non-linear components of cochlear origin, and the linear reflection in the time domain....... The observed latencies as a function of frequency are qualitatively similar across subjects. For the individual subjects, the delay for each tone-burst frequency is reproducible. Defining OAE latency as the time between the onset of the stimulus and the peak of the first OAE burst yields results in agreement...

  19. Nonlinear Systems.

    Science.gov (United States)

    Seider, Warren D.; Ungar, Lyle H.

    1987-01-01

    Describes a course in nonlinear mathematics courses offered at the University of Pennsylvania which provides an opportunity for students to examine the complex solution spaces that chemical engineers encounter. Topics include modeling many chemical processes, especially those involving reaction and diffusion, auto catalytic reactions, phase…

  20. Transient Serotonin Toxicity Evoked by Combination of Electroconvulsive Therapy and Fluoxetine

    DEFF Research Database (Denmark)

    Klysner, René; Bjerg Bendsen, Birgitte; Hansen, Maja Soon

    2014-01-01

    The serotonin syndrome has been described only in rare instances for electroconvulsive therapy combined with an antidepressant medication. We describe a case of serotonin toxicity induced by electroconvulsive therapy in combination with fluoxetine.......The serotonin syndrome has been described only in rare instances for electroconvulsive therapy combined with an antidepressant medication. We describe a case of serotonin toxicity induced by electroconvulsive therapy in combination with fluoxetine....

  1. Transient Serotonin Toxicity Evoked by Combination of Electroconvulsive Therapy and Fluoxetine

    Directory of Open Access Journals (Sweden)

    René Klysner

    2014-01-01

    Full Text Available The serotonin syndrome has been described only in rare instances for electroconvulsive therapy combined with an antidepressant medication. We describe a case of serotonin toxicity induced by electroconvulsive therapy in combination with fluoxetine.

  2. A STUDY ON NEONATAL HEARING LOSS USING TRANSIENT EVOKED OTOACOUSTIC EMISSIONS

    Directory of Open Access Journals (Sweden)

    Jayaprabha

    2016-02-01

    Full Text Available Deafness is an invisible disability that may often go undetected until school age, especially in children with no additional disabilities. It affects the social, emotional and cognitive development of an individual. However, this can be overcome through early identification and intervention, for which a screening programme is mandatory. But choosing any option needs realistic assessment of the magnitude of the problem in terms of prevalence as well as the risk factors operating in that specific context. So this study was performed to plan future neonatal screening programmes at Medical College Hospital, Thiruvananthapuram. The study was conducted on 402 babies born at SAT Hospital, Medical College, Thiruvananthapuram. The prevalence of neonatal hearing loss was found to be 0.8%. Craniofacial anomalies, family history of permanent childhood hearing loss and congenital infections were found to be the significant risk factors for hearing loss.

  3. Wavelet neural network based fault diagnosis in nonlinear analog circuits

    Institute of Scientific and Technical Information of China (English)

    Yin Shirong; Chen Guangju; Xie Yongle

    2006-01-01

    The theories of diagnosing nonlinear analog circuits by means of the transient response testing are studied. Wavelet analysis is made to extract the transient response signature of nonlinear circuits and compress the signature dada. The best wavelet function is selected based on the between-category total scatter of signature. The fault dictionary of nonlinear circuits is constructed based on improved back-propagation(BP) neural network. Experimental results demonstrate that the method proposed has high diagnostic sensitivity and fast fault identification and deducibility.

  4. State-variable analysis of non-linear circuits with a desk computer

    Science.gov (United States)

    Cohen, E.

    1981-01-01

    State variable analysis was used to analyze the transient performance of non-linear circuits on a desk top computer. The non-linearities considered were not restricted to any circuit element. All that is required for analysis is the relationship defining each non-linearity be known in terms of points on a curve.

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

    Directory of Open Access Journals (Sweden)

    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

  6. Normalization of Pain-Evoked Neural Responses Using Spontaneous EEG Improves the Performance of EEG-Based Cross-Individual Pain Prediction

    Science.gov (United States)

    Bai, Yanru; Huang, Gan; Tu, Yiheng; Tan, Ao; Hung, Yeung Sam; Zhang, Zhiguo

    2016-01-01

    An effective physiological pain assessment method that complements the gold standard of self-report is highly desired in pain clinical research and practice. Recent studies have shown that pain-evoked electroencephalography (EEG) responses could be used as a readout of perceived pain intensity. Existing EEG-based pain assessment is normally achieved by cross-individual prediction (i.e., to train a prediction model from a group of individuals and to apply the model on a new individual), so its performance is seriously hampered by the substantial inter-individual variability in pain-evoked EEG responses. In this study, to reduce the inter-individual variability in pain-evoked EEG and to improve the accuracy of cross-individual pain prediction, we examined the relationship between pain-evoked EEG, spontaneous EEG, and pain perception on a pain EEG dataset, where a large number of laser pulses (>100) with a wide energy range were delivered. Motivated by our finding that an individual's pain-evoked EEG responses is significantly correlated with his/her spontaneous EEG in terms of magnitude, we proposed a normalization method for pain-evoked EEG responses using one's spontaneous EEG to reduce the inter-individual variability. In addition, a nonlinear relationship between the level of pain perception and pain-evoked EEG responses was obtained, which inspired us to further develop a new two-stage pain prediction strategy, a binary classification of low-pain and high-pain trials followed by a continuous prediction for high-pain trials only, both of which used spontaneous-EEG-normalized magnitudes of evoked EEG responses as features. Results show that the proposed normalization strategy can effectively reduce the inter-individual variability in pain-evoked responses, and the two-stage pain prediction method can lead to a higher prediction accuracy. PMID:27148028

  7. GABAA receptors modulate cannabinoid-evoked hypothermia.

    Science.gov (United States)

    Rawls, S M; Tallarida, R J; Kon, D A; Geller, E B; Adler, Martin W

    2004-05-01

    Cannabinoids evoke hypothermia by stimulating central CB(1) receptors. GABA induces hypothermia via GABA(A) or GABA(B) receptor activation. CB(1) receptor activation increases GABA release in the hypothalamus, a central locus for thermoregulation, suggesting that cannabinoid and GABA systems may be functionally linked in body temperature regulation. We investigated whether GABA receptors modulate the hypothermic actions of [4,5-dihydro-2-methyl-4(4-morpholinylmethyl)-1-(1-naphthalenyl-carbonyl)-6H-pyrrolo[3,2,1ij]quinolin-6-one] (WIN 55212-2), a selective cannabinoid agonist, in male Sprague-Dawley rats. WIN 55212-2 (2.5 mg/kg im) produced a rapid hypothermia that peaked 45-90 min postinjection. The hypothermia was attenuated by bicuculline (2 mg/kg ip), a GABA(A) antagonist. However, SCH 50911 (1-10 mg/kg ip), a GABA(B) blocker, did not antagonize the hypothermia. Neither bicuculline (2 mg/kg) nor SCH 50911 (10 mg/kg) by itself altered body temperature. We also investigated a possible role for CB(1) receptors in GABA-generated hypothermia. Muscimol (2.5 mg/kg ip), a GABA(A) agonist, or baclofen (5 mg/kg ip), a GABA(B) agonist, evoked a significant hypothermia. Blockade of CB(1) receptors with SR141716A (2.5 mg/kg im) did not antagonize muscimol- or baclofen-induced hypothermia, indicating that GABA-evoked hypothermia does not contain a CB(1)-sensitive component. Our results implicate GABA(A) receptors in the hypothermic actions of cannabinoids and provide further evidence of a functional link between cannabinoid and GABA systems.

  8. Do ambient urban odors evoke basic emotions?

    Science.gov (United States)

    Glass, Sandra T; Lingg, Elisabeth; Heuberger, Eva

    2014-01-01

    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 (SCR) 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 SCR 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. Do ambient urban odors evoke basic emotions?

    Directory of Open Access Journals (Sweden)

    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.

  10. Mechanism of action of magnesium on acetylcholine-evoked secretory responses in isolated rat pancreas.

    Science.gov (United States)

    Francis, L P; Lennard, R; Singh, J

    1990-09-01

    This study investigates the effects of magnesium (Mg2+) on acetylcholine (ACh)-evoked secretory responses and calcium (Ca2+) mobilization in the isolated rat pancreas. ACh induced marked dose-dependent increases in total protein output and amylase release from superfused pancreatic segments in zero, normal (1 x 1 mM) and elevated (10 mM) extracellular Mg2+. Elevated Mg2+ attenuated the ACh-evoked secretory responses compared to zero and normal Mg2+. In the absence of extracellular Ca2+, but presence of 1 mM-EGTA (ethylene glycol bis(beta-aminoethylether)-N,N,N',N''-tetraacetic acid), ACh elicited a small transient release of protein from pancreatic segments compared to a larger and more sustained secretion in the absence of both Ca2+ and Mg2+. Incubation of pancreatic segments with 45Ca2+ resulted in time-dependent uptake with maximum influx of 45Ca2+ occurring after 20 min of incubation period. ACh stimulated markedly the 45Ca2+ uptake compared to control tissues. In elevated extracellular Mg2+ the ACh-induced 45Ca2+ influx was significantly (P less than 0.001) reduced compared to zero and normal Mg2+. ACh also evoked dose-dependent increases in cytosolic free Ca2+ concentrations ([Ca2+]i) in pancreatic acinar cells loaded with the fluorescent dye Fura-2 AM. In elevated Mg2+ the ACh-induced cytosolic [Ca2+]i was significantly (P less than 0.001) reduced compared to zero and normal Mg2+. These results indicate that Mg2+ can influence ACh-evoked secretory responses possibly by controlling both Ca2+ influx and release in pancreatic acinar cells.

  11. Somatosensory evoked response: application in neurology

    Directory of Open Access Journals (Sweden)

    Carlos A. M. Guerreiro

    1982-03-01

    Full Text Available One technique used for short-latency somatosensory evoked response (SER is described. SER following nerve stimulation is a unique non-invasive, clinical test used to evaluate the somatosensory pathways. It tests the physiological function of the median nerve, the brachial plexus, the C6-7 cervical roots, cervical spinal cord, the cuneate nuclei, the medial lemniscus, the thalamus, and the contralateral sensory cortex. It has been shown to be a reliable and useful clinical test partiicularly in multiple sclerosis and comatose patients. The promising technique of SER following peroneal nerve stimulation is mentioned.

  12. Nonlinear PDEs

    OpenAIRE

    2015-01-01

    From the Back Cover: The emphasis throughout the present volume is on the practical application of theoretical mathematical models helping to unravel the underlying mechanisms involved in processes from mathematical physics and biosciences. It has been conceived as a unique collection of abstract methods dealing especially with nonlinear partial differential equations (either stationary or evolutionary) that are applied to understand concrete processes involving some important applications re...

  13. Synaptic responses evoked by tactile stimuli in Purkinje cells in mouse cerebellar cortex Crus II in vivo.

    Directory of Open Access Journals (Sweden)

    Chun-Ping Chu

    Full Text Available BACKGROUND: Sensory stimuli evoke responses in cerebellar Purkinje cells (PCs via the mossy fiber-granule cell pathway. However, the properties of synaptic responses evoked by tactile stimulation in cerebellar PCs are unknown. The present study investigated the synaptic responses of PCs in response to an air-puff stimulation on the ipsilateral whisker pad in urethane-anesthetized mice. METHODS AND MAIN RESULTS: Thirty-three PCs were recorded from 48 urethane-anesthetized adult (6-8-week-old HA/ICR mice by somatic or dendritic patch-clamp recording and pharmacological methods. Tactile stimulation to the ipsilateral whisker pad was delivered by an air-puff through a 12-gauge stainless steel tube connected with a pressurized injection system. Under current-clamp conditions (I = 0, the air-puff stimulation evoked strong inhibitory postsynaptic potentials (IPSPs in the somata of PCs. Application of SR95531, a specific GABA(A receptor antagonist, blocked IPSPs and revealed stimulation-evoked simple spike firing. Under voltage-clamp conditions, tactile stimulation evoked a sequence of transient inward currents followed by strong outward currents in the somata and dendrites in PCs. Application of SR95531 blocked outward currents and revealed excitatory postsynaptic currents (EPSCs in somata and a temporal summation of parallel fiber EPSCs in PC dendrites. We also demonstrated that PCs respond to both the onset and offset of the air-puff stimulation. CONCLUSIONS: These findings indicated that tactile stimulation induced asynchronous parallel fiber excitatory inputs onto the dendrites of PCs, and failed to evoke strong EPSCs and spike firing in PCs, but induced the rapid activation of strong GABA(A receptor-mediated inhibitory postsynaptic currents in the somata and dendrites of PCs in the cerebellar cortex Crus II in urethane-anesthetized mice.

  14. Transient from crystallization to fractal growth observed in both boar bile and SnI sub 2 vapour

    CERN Document Server

    Zhang Ji Zhong; Xie An Jian

    2003-01-01

    A visual transient of the growth mechanism from crystallization to fractal growth was observed clearly in a drop of boar bile. The growing crystals were replaced by treelike fractal structures during solidification of the sample. It is fascinating to compare the transient with the result observed in SnI sub 2 vapour. They were completely identical, and revealed that under certain conditions a linear growth could be transferred spontaneously into nonlinear growth. It may be possible to consider the transient as a 'bridge' between linear and nonlinear growth, and to develop a quantitative expression of transient dynamics.

  15. Transient lingual papillitis.

    Science.gov (United States)

    Kornerup, Ida M; Senye, Mireya; Peters, Edmund

    2016-01-01

    A case of recurrent, clinically innocuous, but painful papules involving the tongue dorsum of a 25-year-old man is presented. The lesions were interpreted to represent a transient lingual papillitis. This a poorly understood, but benign and self-limited condition involving the tongue fungiform papillae, which does not appear to be widely recognized.

  16. Transient Heat Conduction

    DEFF Research Database (Denmark)

    Rode, Carsten

    1998-01-01

    Analytical theory of transient heat conduction.Fourier's law. General heat conducation equation. Thermal diffusivity. Biot and Fourier numbers. Lumped analysis and time constant. Semi-infinite body: fixed surface temperature, convective heat transfer at the surface, or constant surface heat flux...

  17. Transient tachypnea - newborn

    Science.gov (United States)

    ... or reabsorbing it. The first few breaths a baby takes after delivery fill the lungs with air and help to ... goes away within 24 to 48 hours after delivery. In most cases, babies who have had transient tachypnea have no further ...

  18. On Detecting Transients

    CERN Document Server

    Belanger, G

    2013-01-01

    Transient phenomena are interesting and potentially highly revealing of details about the processes under observation and study that could otherwise go unnoticed. It is therefore important to maximise the sensitivity of the method used to identify such events. In this article we present a general procedure based on the use of the likelihood function for identifying transients that is particularly suited for real-time applications because it requires no grouping or pre-processing of the data. The method is optimal in the sense that all the information that is available in the data is used in the statistical decision making process, and is suitable for a wide range of applications. We here consider those most common in astrophysics which involve searching for transient sources, events or features in images, time series, energy spectra and power spectra, and demonstrate the use of the method in the cases of a transient in a time series or in a power spectrum. We derive a fit statistic that is ideal for fitting a...

  19. The LOFAR Transients Pipeline

    NARCIS (Netherlands)

    Swinbank, J.; Staley, T.; Molenaar, G.; Rol, E.; Rowlinson, A.; Scheers, L.H.A.; Spreeuw, H.; Bell, M.E.; Broderick, J.; Carbone, D.; Garsden, H.; Horst, A. van der; Law, C.J.; Wise, M.W.; Breton, R.P.; Cendes, Y.; Corbel, S.; Eisloeffel, J.; Falcke, H.; Fender, R.P.; Griessmeier, J.-M.; Hessels, J.W.T.; Stappers, B.W.; Stewart, A.; Wijers, R.A.M.J.; Wijnands, R.; Zarka, P.

    2015-01-01

    Current and future astronomical survey facilities provide a remarkably rich opportunity for transient astronomy, combining unprecedented fields of view with high sensitivity and the ability to access previously unexplored wavelength regimes. This is particularly true of LOFAR, a recently-commissione

  20. Efficient Finite Element Methods for Transient Nonlinear Analysis of Shells.

    Science.gov (United States)

    1983-08-01

    governing equations for a beam based on shallow shell theory and the variational formulations which pertain in this context to displacement, hybrid, and...functions, respectively. Because the curvature is treated by shallow - shell theory , cf. Eqs. (1), all terms were integrated over the straight x-axis. Only

  1. Evoked potentials in pediatric cerebral malaria

    Directory of Open Access Journals (Sweden)

    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.

  2. Long Latency Auditory Evoked Potentials during Meditation.

    Science.gov (United States)

    Telles, Shirley; Deepeshwar, Singh; Naveen, Kalkuni Visweswaraiah; Pailoor, Subramanya

    2015-10-01

    The auditory sensory pathway has been studied in meditators, using midlatency and short latency auditory evoked potentials. The present study evaluated long latency auditory evoked potentials (LLAEPs) during meditation. Sixty male participants, aged between 18 and 31 years (group mean±SD, 20.5±3.8 years), were assessed in 4 mental states based on descriptions in the traditional texts. They were (a) random thinking, (b) nonmeditative focusing, (c) meditative focusing, and (d) meditation. The order of the sessions was randomly assigned. The LLAEP components studied were P1 (40-60 ms), N1 (75-115 ms), P2 (120-180 ms), and N2 (180-280 ms). For each component, the peak amplitude and peak latency were measured from the prestimulus baseline. There was significant decrease in the peak latency of the P2 component during and after meditation (Pmeditation facilitates the processing of information in the auditory association cortex, whereas the number of neurons recruited was smaller in random thinking and non-meditative focused thinking, at the level of the secondary auditory cortex, auditory association cortex and anterior cingulate cortex.

  3. New perspectives on vestibular evoked myogenic potentials.

    Science.gov (United States)

    Rosengren, Sally M; Kingma, Herman

    2013-02-01

    Although the vestibular evoked myogenic potential (VEMP) measured from the cervical muscles (cVEMP, cervical VEMP) is well described and has documented clinical utility, its analogue recorded from the extraocular muscles (oVEMP, ocular VEMP) has been described only recently and is currently emerging as an additional test of otolith function. This review will, therefore, summarize recent developments in VEMP research with a focus on the oVEMP. Recent studies suggest that the oVEMP is produced by otolith afferents in the superior vestibular nerve division, whereas the cVEMP evoked by sound is thought to be an inferior vestibular nerve reflex. Correspondingly, the oVEMP correlates better with caloric and subjective visual vertical tests than sound-cVEMPs. cVEMPs are more complicated than often thought, as shown by the presence of crossed responses and conflicting results of recent vibration studies. Altered inner ear mechanics produced by the vestibular diseases superior semicircular canal dehiscence and Ménière's disease lead to changes in the preferred frequency of the oVEMP and cVEMP. The oVEMP provides complementary diagnostic information to the cVEMP and is likely to be a useful addition to the diagnostic test battery in neuro-otology.

  4. Auditory evoked potentials in postconcussive syndrome.

    Science.gov (United States)

    Drake, M E; Weate, S J; Newell, S A

    1996-12-01

    The neuropsychiatric sequelae of minor head trauma have been the source of controversy. Most clinical and imaging studies have shown no alteration after concussion, but neuropsychological and neuropathological abnormalities have been reported. Some changes in neurophysiologic diagnostic tests have been described in postconcussive syndrome. We recorded middle latency auditory evoked potentials (MLR) and slow vertex responses (SVR) in 20 individuals with prolonged cognitive difficulties, behavior changes, dizziness, and headache after concussion. MLR is utilized alternating polarity clicks presented monaurally at 70 dB SL at 4 per second, with 40 dB contralateral masking. Five hundred responses were recorded and replicated from Cz-A1 and Cz-A2, with 50 ms. analysis time and 20-1000 Hz filter band pass. SVRs were recorded with the same montage, but used rarefaction clicks, 0.5 Hz stimulus rate, 500 ms. analysis time, and 1-50 Hz filter band pass. Na and Pa MLR components were reduced in amplitude in postconcussion patients. Pa latency was significantly longer in patients than in controls. SVR amplitudes were longer in concussed individuals, but differences in latency and amplitude were not significant. These changes may reflect posttraumatic disturbance in presumed subcortical MLR generators, or in frontal or temporal cortical structures that modulate them. Middle and long-latency auditory evoked potentials may be helpful in the evaluation of postconcussive neuropsychiatric symptoms.

  5. Interaural difference values of vestibular evoked myogenic.

    Directory of Open Access Journals (Sweden)

    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.

  6. Compressive Transient Imaging

    KAUST Repository

    Sun, Qilin

    2017-04-01

    High resolution transient/3D imaging technology is of high interest in both scientific research and commercial application. Nowadays, all of the transient imaging methods suffer from low resolution or time consuming mechanical scanning. We proposed a new method based on TCSPC and Compressive Sensing to achieve a high resolution transient imaging with a several seconds capturing process. Picosecond laser sends a serious of equal interval pulse while synchronized SPAD camera\\'s detecting gate window has a precise phase delay at each cycle. After capturing enough points, we are able to make up a whole signal. By inserting a DMD device into the system, we are able to modulate all the frames of data using binary random patterns to reconstruct a super resolution transient/3D image later. Because the low fill factor of SPAD sensor will make a compressive sensing scenario ill-conditioned, We designed and fabricated a diffractive microlens array. We proposed a new CS reconstruction algorithm which is able to denoise at the same time for the measurements suffering from Poisson noise. Instead of a single SPAD senor, we chose a SPAD array because it can drastically reduce the requirement for the number of measurements and its reconstruction time. Further more, it not easy to reconstruct a high resolution image with only one single sensor while for an array, it just needs to reconstruct small patches and a few measurements. In this thesis, we evaluated the reconstruction methods using both clean measurements and the version corrupted by Poisson noise. The results show how the integration over the layers influence the image quality and our algorithm works well while the measurements suffer from non-trival Poisson noise. It\\'s a breakthrough in the areas of both transient imaging and compressive sensing.

  7. Transients from Initial Conditions A Perturbative Analysis

    CERN Document Server

    Scoccimarro, R

    1998-01-01

    The standard procedure to generate initial conditions (IC) in numerical simulations is to use the Zel'dovich approximation (ZA). Although the ZA correctly reproduces the linear growing modes of density and velocity perturbations, non-linear growth is inaccurately represented because of the ZA failure to conserve momentum. This implies that it takes time for the actual dynamics to establish the correct statistical properties of density and velocity fields. We extend perturbation theory (PT) to include transients as non-linear excitations of decaying modes caused by the IC. We focus on higher-order statistics of the density contrast and velocity divergence, characterized by the S_p and T_p parameters. We find that the time-scale of transients is determined, at a given order p, by the spectral index n. The skewness factor S_3 (T_3) attains 10% accuracy only after a=6 (a=15) for n=0, whereas higher (lower) n demands more (less) expansion away from the IC. These requirements become much more stringent as p increas...

  8. (−)-Englerin A-evoked Cytotoxicity Is Mediated by Na+ Influx and Counteracted by Na+/K+-ATPase*

    Science.gov (United States)

    Ludlow, Melanie J.; Gaunt, Hannah J.; Rubaiy, Hussein N.; Musialowski, Katie E.; Blythe, Nicola M.; Vasudev, Naveen S.; Muraki, Katsuhiko; Beech, David J.

    2017-01-01

    (−)-Englerin A ((−)-EA) has a rapid and potent cytotoxic effect on several types of cancer cell that is mediated by plasma membrane ion channels containing transient receptor potential canonical 4 (TRPC4) protein. Because these channels are Ca2+-permeable, it was initially thought that the cytotoxicity arose as a consequence of Ca2+ overload. Here we show that this is not the case and that the effect of (−)-EA is mediated by a heteromer of TRPC4 and TRPC1 proteins. Both TRPC4 and TRPC1 were required for (−)-EA cytotoxicity; however, although TRPC4 was necessary for the (−)-EA-evoked Ca2+ elevation, TRPC1 was not. TRPC1 either had no role or was a negative regulator of Ca2+ entry. By contrast, both TRPC4 and TRPC1 were necessary for monovalent cation entry evoked by (−)-EA, and (−)-EA-evoked cell death was dependent upon entry of the monovalent cation Na+. We therefore hypothesized that Na+/K+-ATPase might act protectively by counteracting the Na+ load resulting from sustained Na+ entry. Indeed, inhibition of Na+/K+-ATPase by ouabain potently and strongly increased (−)-EA-evoked cytotoxicity. The data suggest that (−)-EA achieves cancer cell cytotoxicity by inducing sustained Na+ entry through heteromeric TRPC1/TRPC4 channels and that the cytotoxic effect of (−)-EA can be potentiated by Na+/K+-ATPase inhibition. PMID:27875305

  9. Transient birefringence effects in electromagnetically induced transparency

    Energy Technology Data Exchange (ETDEWEB)

    Parshkov, O M [Yuri Gagarin State Technical University of Saratov, Saratov (Russian Federation)

    2015-11-30

    We report the results of numerical modelling of transient birefringence that arises as a result of electromagnetically induced transparency on degenerate quantum transitions between the states with J = 0, 1 and 2 in the presence of the Doppler broadening of spectral lines. It is shown that in the case of a linearly polarised control field, the effect of transient birefringence leads to a decay of the input circularly polarised probe pulse into separate linearly polarised pulses inside a medium. In the case of a circularly polarised control field, the effect of transient birefringence manifests itself in a decay of the input linearly polarised probe pulse into separate circularly polarised pulses. It is shown that the distance that a probe pulse has to pass in a medium before decaying into subpulses is considerably greater in the first case than in the second. The influence of the input probe pulse power and duration on the process of spatial separation into individual pulses inside a medium is studied. A qualitative analysis of the obtained results is presented. (nonlinear optical phenomena)

  10. Dynamics of Transiently Chaotic Neural Network and Its Application to Optimization

    Institute of Scientific and Technical Information of China (English)

    YANG Li-Jiang; CHEN Tian-Lun; HUANG Wu-Qun

    2001-01-01

    Through adding a nonlinear self-feedback term in the evolution equations of neural network, we introduced a transiently chaotic neural network model. In order to utilize the transiently chaotic dynamics mechanism in optimization problem efficiently, we have analyzed the dynamical procedure of the transiently chaotic neural network rnodel and studied the function of the crucial bifurcation parameter which governs the chaotic behavior of the system. Based on the dynamical analysis of the transiently chaotic neural network model, chaotic annealing algorithm is also examined and improved. As an example, we applied chaotic annealing method to the traveling salesman problem and obtained good results.``

  11. Coherent Transient Systems Evaluation

    Science.gov (United States)

    1993-06-17

    manuscript is submitted for publication with the understanding that the United States Government is authorized to reproduce and distribute reprints...for governmental purposes. 1.0 Introduction The continuous optical correlator presented here is based on the phenomena of coherent transients, also...Gating the Continuous Processor Programming the continuous processor is accomplished by illuminati , n, the material with ,.’ modulated light pulses: a

  12. The Rapid Transient Surveyor

    Science.gov (United States)

    Baranec, Christoph; Tonry, John; Wright, Shelley; Tully, R. Brent; Lu, Jessica R.; Takamiya, Marianne Y.; Hunter, Lisa

    2016-01-01

    The next decade of astronomy will be dominated by large area surveys (see the detailed discussion in the Astro-2010 Decadal survey and NRC's recent OIR System Report). Ground-based optical transient surveys, e.g., LSST, ZTF and ATLAS and space-based exoplanet, supernova, and lensing surveys such as TESS and WFIRST will join the Gaia all-sky astrometric survey in producing a flood of data that will enable leaps in our understanding of the universe. There is a critical need for further characterization of these discoveries through high angular resolution images, deeper images, spectra, or observations at different cadences or periods than the main surveys. Such follow-up characterization must be well matched to the particular surveys, and requires sufficient additional observing resources and time to cover the extensive number of targets.We describe plans for the Rapid Transient Surveyor (RTS), a permanently mounted, rapid-response, high-cadence facility for follow-up characterization of transient objects on the U. of Hawai'i 2.2-m telescope on Maunakea. RTS will comprise an improved robotic laser adaptive optics system, based on the prototype Robo-AO system (formerly at the Palomar 1.5-m and now at the Kitt Peak 2.2-m telescope), with simultaneous visible and near-infrared imagers as well as a near-infrared integral field spectrograph (R~100, λ = 850 - 1830 nm, 0.15″ spaxels, 8.7″×6.0″ FoV). RTS will achieve an acuity of ~0.07″ in visible wavelengths and automated detection and characterization of astrophysical transients during a sustained observing campaign will yield the necessary statistics to precisely map dark matter in the local universe.

  13. Transient Astrophysics Probe

    Science.gov (United States)

    Camp, Jordan

    2017-08-01

    Transient Astrophysics Probe (TAP), selected by NASA for a funded Concept Study, is a wide-field high-energy transient mission proposed for flight starting in the late 2020s. TAP’s main science goals, called out as Frontier Discovery areas in the 2010 Decadal Survey, are time-domain astrophysics and counterparts of gravitational wave (GW) detections. The mission instruments include unique imaging soft X-ray optics that allow ~500 deg2 FoV in each of four separate modules; a high sensitivity, 1 deg2 FoV soft X-ray telescope based on single crystal silicon optics; a passively cooled, 1 deg2 FoV Infrared telescope with bandpass 0.6-3 micron; and a set of ~8 small NaI gamma-ray detectors. TAP will observe many events per year of X-ray transients related to compact objects, including tidal disruptions of stars, supernova shock breakouts, neutron star bursts and superbursts, and high redshift Gamma-Ray Bursts. Perhaps most exciting is TAP’s capability to observe X-ray and IR counterparts of GWs involving stellar mass black holes detected by LIGO/Virgo, and possibly X-ray counterparts of GWs from supermassive black holes, detected by LISA and Pulsar Timing Arrays.

  14. Visual evoked potentials in rubber factory workers.

    Science.gov (United States)

    Tandon, O P; Kumar, V

    1997-01-01

    Pattern reversal visual evoked potentials (pVEP) were studied in 39 male rubber factory workers in the age range of 18-55 years and 20 control subjects (aged 18-46 years) not exposed to the rubber factory environment. Results revealed that 20 (51%) rubber factory workers had abnormal latencies of wave P1 (dominant component of pVEP) as per accepted criteria of 99% tolerance limit set for the control group (i.e. any value above mean +3 SD of control was considered abnormal). The section-wise per cent distribution of abnormalities was vulcanization (83%), tubing (75%), calendering (60%), loading (38%) and mixing (14%). This study provides electrophysiological evidence that rubber factory environments affect the conduction processes in optical pathways from their origin in the retina to striate cortex. However, this study has its limitations in not identifying the specific chemical(s) causing these changes in VEP.

  15. Music evokes vicarious emotions in listeners.

    Science.gov (United States)

    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.

  16. Bayesian analysis of MEG visual evoked responses

    Energy Technology Data Exchange (ETDEWEB)

    Schmidt, D.M.; George, J.S.; Wood, C.C.

    1999-04-01

    The authors developed a method for analyzing neural electromagnetic data that allows probabilistic inferences to be drawn about regions of activation. The method involves the generation of a large number of possible solutions which both fir the data and prior expectations about the nature of probable solutions made explicit by a Bayesian formalism. In addition, they have introduced a model for the current distributions that produce MEG and (EEG) data that allows extended regions of activity, and can easily incorporate prior information such as anatomical constraints from MRI. To evaluate the feasibility and utility of the Bayesian approach with actual data, they analyzed MEG data from a visual evoked response experiment. They compared Bayesian analyses of MEG responses to visual stimuli in the left and right visual fields, in order to examine the sensitivity of the method to detect known features of human visual cortex organization. They also examined the changing pattern of cortical activation as a function of time.

  17. Resting Heart Rate and Auditory Evoked Potential

    Directory of Open Access Journals (Sweden)

    Simone Fiuza Regaçone

    2015-01-01

    Full Text Available The objective of this study was to evaluate the association between rest heart rate (HR and the components of the auditory evoked-related potentials (ERPs at rest in women. We investigated 21 healthy female university students between 18 and 24 years old. We performed complete audiological evaluation and measurement of heart rate for 10 minutes at rest (heart rate monitor Polar RS800CX and performed ERPs analysis (discrepancy in frequency and duration. There was a moderate negative correlation of the N1 and P3a with rest HR and a strong positive correlation of the P2 and N2 components with rest HR. Larger components of the ERP are associated with higher rest HR.

  18. RECORDING OF VESTIBULAR EVOKED MYOGENIC POTENTIALS

    Directory of Open Access Journals (Sweden)

    A. A. Sazgar

    2006-05-01

    Full Text Available It has been shown recently that loud clicks evoke myogenic potentials in the tonically contracting sternocleidomastoid muscles. Studies have suggested that these potentials are of vestibular origin, especially of the saccule and inferior vestibular nerve. A pilot study was undertaken in our hospital to record vestibular evoked myogenic potentials (VEMP for the first time in Iran. Eighteen healthy volunteers (32 ears without history of otologic or vestibular disorders were subjected to the VEMP test. Twenty-one patients (26 ears with unilateral (6 patients and bilateral (5 patients high frequency sensorineural hearing loss with unknown etiology, acoustic neuroma (1 patient, Meniere’s disease (4 patients and unilateral low frequency sensorineural hearing loss without vestibular complaint (5 patients were also enrolled in this study. VEMP response to clicks was obtained from 84.4% of ears of healthy subjects. These subjects demonstrated short latency waves to click stimuli during tonic neck flexor activation. Mean latencies of first positive (p13 and first negative (n23 potentials in healthy subjects were 12.45 ± 1.9 ms and 20.8 ± 3.5 ms, respectively. Median latencies of these two potentials were 12.1 and 19.3 ms, respectively. We could record VEMP in 5 patients with unilateral and all patients with high and low frequency sensorineural hearing loss without vestibular complaint. In the patient with acoustic neuroma VEMP was absent on the affected side. This technique may offer a new method to evaluate otolith and sacculocollic pathways in human.

  19. Mind games : the effects of diazepam on Evoked Potentials

    NARCIS (Netherlands)

    Jongsma, Marie-Louise Albertien

    2000-01-01

    The electroencephalogram (EEG) represents the electrical activity of the brain. Evoked Potentials (EPs) are small voltage fluctuations in the EEG resulting from sensory, cognitive or motor evoked neural activity. Variations in the EP waveform may be caused by several factors. 1. By employing differe

  20. 21 CFR 882.1870 - Evoked response electrical stimulator.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Evoked response electrical stimulator. 882.1870... electrical stimulator. (a) Identification. An evoked response electrical stimulator is a device used to apply an electrical stimulus to a patient by means of skin electrodes for the purpose of measuring...

  1. Auditory evoked potentials in peripheral vestibular disorder individuals

    Directory of Open Access Journals (Sweden)

    Matas, Carla Gentile

    2011-07-01

    Full Text Available Introduction: The auditory and vestibular systems are located in the same peripheral receptor, however they enter the CNS and go through different ways, thus creating a number of connections and reaching a wide area of the encephalon. Despite going through different ways, some changes can impair both systems. Such tests as Auditory Evoked Potentials can help find a diagnosis when vestibular alterations are seen. Objective: describe the Auditory Evoked Potential results in individuals complaining about dizziness or vertigo with Peripheral Vestibular Disorders and in normal individuals having the same complaint. Methods: Short, middle and long latency Auditory Evoked Potentials were performed as a transversal prospective study. Conclusion: individuals complaining about dizziness or vertigo can show some changes in BAEP (Brainstem Auditory Evoked Potential, MLAEP (Medium Latency Auditory Evoked Potential and P300.

  2. Multimodal evoked potential abnormalities in patients with Wilson's disease

    Directory of Open Access Journals (Sweden)

    Ilić Tihomir V.

    2005-01-01

    Full Text Available The aim of this study was to investigate the involvement of the following functional systems: somatosensory evoked potentials (SSEP, visual evoked potentials (VEP, and event related potentials (ERP, in twenty patients with Wilson's disease (WD. VEP and SSEP abnormalities were discovered in S patients respectively (40%, whereas ERP were either absent or, in the case of 10 patients (50%, had significantly prolonged P-300 latencies. Taken together, at least one evoked potential abnormality was discovered in 17 patients (85%]. Only in 3 patients (15%, involving either the isolated hepatic type of disease or short illness duration of the neurological type, were normal evoked potential findings observed. Our findings suggest the usefulness of multimodal evoked potential abnormalities in the evaluation of subclinical manifestations in patients with WD.

  3. Chirp-modulated visual evoked potential as a generalization of steady state visual evoked potential

    Science.gov (United States)

    Tu, Tao; Xin, Yi; Gao, Xiaorong; Gao, Shangkai

    2012-02-01

    Visual evoked potentials (VEPs) are of great concern in cognitive and clinical neuroscience as well as in the recent research field of brain-computer interfaces (BCIs). In this study, a chirp-modulated stimulation was employed to serve as a novel type of visual stimulus. Based on our empirical study, the chirp stimuli visual evoked potential (Chirp-VEP) preserved frequency features of the chirp stimulus analogous to the steady state evoked potential (SSVEP), and therefore it can be regarded as a generalization of SSVEP. Specifically, we first investigated the characteristics of the Chirp-VEP in the time-frequency domain and the fractional domain via fractional Fourier transform. We also proposed a group delay technique to derive the apparent latency from Chirp-VEP. Results on EEG data showed that our approach outperformed the traditional SSVEP-based method in efficiency and ease of apparent latency estimation. For the recruited six subjects, the average apparent latencies ranged from 100 to 130 ms. Finally, we implemented a BCI system with six targets to validate the feasibility of Chirp-VEP as a potential candidate in the field of BCIs.

  4. Nonlinear resonances

    CERN Document Server

    Rajasekar, Shanmuganathan

    2016-01-01

    This introductory text presents the basic aspects and most important features of various types of resonances and anti-resonances in dynamical systems. In particular, for each resonance, it covers the theoretical concepts, illustrates them with case studies, and reviews the available information on mechanisms, characterization, numerical simulations, experimental realizations, possible quantum analogues, applications and significant advances made over the years. Resonances are one of the most fundamental phenomena exhibited by nonlinear systems and refer to specific realizations of maximum response of a system due to the ability of that system to store and transfer energy received from an external forcing source. Resonances are of particular importance in physical, engineering and biological systems - they can prove to be advantageous in many applications, while leading to instability and even disasters in others. The book is self-contained, providing the details of mathematical derivations and techniques invo...

  5. Nonlinear Dynamics

    Institute of Scientific and Technical Information of China (English)

    1996-01-01

    3.1 A Unified Nonlinear Feedback Functional Method for Study Both Control and Synchronization of Spatiotemporal Chaos Fang Jinqing Ali M. K. (Department of Physics, The University of Lethbridge,Lethbridge, Alberta T1K 3M4,Canada) Two fundamental questions dominate future chaos control theories.The first is the problem of controlling hyperchaos in higher dimensional systems.The second question has yet to be addressed:the problem of controlling spatiotemporal chaos in a spatiotemporal system.In recent years, control and synchronization of spatiotemporal chaos and hyperchaos have became a much more important and challenging subject. The reason for this is the control and synchronism of such behaviours have extensive and great potential of interdisciplinary applications, such as security communication, information processing, medicine and so on. However, this subject is not much known and remains an outstanding open.

  6. Nonlinear terahertz spectroscopy of semiconductor nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Luo, C. [Department of Electrophysics, National Chiao Tung University, Hsinchu (Taiwan); Reimann, K.; Woerner, M.; Elsaesser, T. [Max-Born-Institut fuer Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Str. 2A, 12489, Berlin (Germany)

    2004-03-01

    Nonlinear frequency conversion and electro-optic sampling allow for the generation and phase-resolved characterization of few-cycle pulses in the frequency range up to 50 THz. Electric field transients with amplitudes of up to several MV/cm are applied to study coherent nonlinear excitations of low-dimensional semiconductors. We report the first observation of Rabi oscillations on intersubband transitions of electrons in GaAs/AlGaAs quantum wells. Frequency and phase of such oscillations are controlled in the 0.3- to 2.5-THz range via the strength and shape of the mid-infrared driving pulse. (orig.)

  7. SUBOPTIMAL NONLINEAR CONTROL OF PACKAGING MACHINERY DRIVE

    OpenAIRE

    Kudin, V. F.; Toropov, A.V.

    2013-01-01

    This paper deals with the procedure of synthesis of a nonlinear position controller for the «feeder» of packaging mechanism. The mathematical model of «feeder» drive with regard to the restriction on the control output of external PLC. Linearization of nonlinear characteristic by the «secants» method is implemented and selected functional quality that defines the minimal time of transients is selected. Quality functional in the form of a quadratic functional with a variable weighting factor i...

  8. Distinct features of auditory steady-state responses as compared to transient event-related potentials.

    Directory of Open Access Journals (Sweden)

    Li Zhang

    Full Text Available Transient event-related potentials (ERPs and steady-state responses (SSRs have been popularly employed to investigate the function of the human brain, but their relationship still remains a matter of debate. Some researchers believed that SSRs could be explained by the linear summation of successive transient ERPs (superposition hypothesis, while others believed that SSRs were the result of the entrainment of a neural rhythm driven by the periodic repetition of a sensory stimulus (oscillatory entrainment hypothesis. In the present study, taking auditory modality as an example, we aimed to clarify the distinct features of SSRs, evoked by the 40-Hz and 60-Hz periodic auditory stimulation, as compared to transient ERPs, evoked by a single click. We observed that (1 SSRs were mainly generated by phase synchronization, while late latency responses (LLRs in transient ERPs were mainly generated by power enhancement; (2 scalp topographies of LLRs in transient ERPs were markedly different from those of SSRs; (3 the powers of both 40-Hz and 60-Hz SSRs were significantly correlated, while they were not significantly correlated with the N1 power in transient ERPs; (4 whereas SSRs were dominantly modulated by stimulus intensity, middle latency responses (MLRs were not significantly modulated by both stimulus intensity and subjective loudness judgment, and LLRs were significantly modulated by subjective loudness judgment even within the same stimulus intensity. All these findings indicated that high-frequency SSRs were different from both MLRs and LLRs in transient ERPs, thus supporting the possibility of oscillatory entrainment hypothesis to the generation of SSRs. Therefore, SSRs could be used to explore distinct neural responses as compared to transient ERPs, and help us reveal novel and reliable neural mechanisms of the human brain.

  9. Blade loss transient dynamics analysis, volume 1. Task 2: TETRA 2 theoretical development

    Science.gov (United States)

    Gallardo, Vincente C.; Black, Gerald

    1986-01-01

    The theoretical development of the forced steady state analysis of the structural dynamic response of a turbine engine having nonlinear connecting elements is discussed. Based on modal synthesis, and the principle of harmonic balance, the governing relations are the compatibility of displacements at the nonlinear connecting elements. There are four displacement compatibility equations at each nonlinear connection, which are solved by iteration for the principle harmonic of the excitation frequency. The resulting computer program, TETRA 2, combines the original TETRA transient analysis (with flexible bladed disk) with the steady state capability. A more versatile nonlinear rub or bearing element which contains a hardening (or softening) spring, with or without deadband, is also incorporated.

  10. ROLE OF NMDA, NICOTINIC, AND GABA RECEPTORS IN THE STEADY STATE VISUAL EVOKED POTENTIAL IN RATS.

    Science.gov (United States)

    This manuscript characterizes the receptor pathways involved in pattern-evoked potential generation in rats" NMDA and nicotinic acetylcholine receptors appear to be involved in the generation of the steady-state pattern evoked response in vivo." The pattern evok...

  11. Recruitment properties and significance of short latency reflexes in neck and eye muscles evoked by brief lateral head accelerations.

    Science.gov (United States)

    Colebatch, James G; Dennis, Danielle L; Govender, Sendhil; Chen, Peggy; Todd, Neil P McAngus

    2014-09-01

    Short lateral head accelerations were applied to investigate the recruitment properties of the reflexes underlying the earliest ocular and cervical electromyographic reflex responses to these disturbances. Components of both reflexes are vestibular dependent and have been termed "ocular vestibular evoked myogenic potentials" and "cervical vestibular evoked myogenic potentials", respectively. Previous investigations using a unilateral vestibular stimulus have indicated that some but not all these vestibular-dependent reflexes show a simple power law relationship to stimulus intensity. In particular, crossed otolith-ocular reflexes showed evidence of an inflection separating two types of behaviour. The present stimulus acts bilaterally, and only the earliest crossed otolith-ocular reflex, previously shown to have a strictly unilateral origin, showed evidence of an inflection. Reflex changes in ocular torsion could, in principle, correct for the changes associated with translation for an elevated eye, but our findings indicated that the responses were consistent with previous reports of tilt-type reflexes. For the neck, both vestibular and segmental (muscle spindle) reflexes were evoked and followed power law relationships, without any clear separation in sensitivity. Our findings are consistent with previous evidence of "tilt-like" reflexes evoked by lateral acceleration and suggest that the departure from a power law occurs as a consequence of a unilateral crossed pathway. For the neck, responses to transients are likely to always consist of both vestibular and non-vestibular (segmental) components. Most of the translation-evoked ocular and cervical reflexes appear to follow power law relationship to stimulus amplitude over a physiological range.

  12. Transient calcium-dependent potassium current in magnocellular neurosecretory cells of the rat supraoptic nucleus.

    Science.gov (United States)

    Bourque, C W

    1988-03-01

    1. Magnocellular neurosecretory neurones were impaled in the supraoptic nucleus of perfused explants of rat hypothalamus. Membrane currents were studied at 35 degrees C using the single-microelectrode voltage-clamp technique. 2. Depolarizing voltage steps applied from -100 mV evoked a transient outward current (TOC) from a threshold of -75 mV. From this potential, the amplitude of the current increased non-linearly with voltage. 3. Following its activation TOC reached a peak within 7 ms and subsequently decayed monotonically with a time constant of 30 ms. This time constant did not vary significantly with voltage between -75 and -55 mV. 4. The TOC showed complete steady-state inactivation at potentials positive to -55 mV. Inactivation was removed by hyperpolarization, with a mid-point near -80 mV. The removal of inactivation followed a complex time course with distinct fast (tens of milliseconds) and slow (hundreds of milliseconds) components. 5. Tail current measurements revealed that the TOC equilibrium potential (ETOC) lies near -97 mV in the presence of 3 mM [K+]o. Increasing [K+]o caused a decrease of TOC amplitude and a shift in ETOC of 57 mV/log [K+]o. The TOC is therefore predominantly a K+ current. 6. The TOC was unaffected by tetraethylammonium (up to 12 mM) but was reversibly reduced by 4-aminopyridine (ca. 50% block at 1.0 mM) and dendrotoxin (ca. 50% block at 4 nM). 7. The TOC was strongly inhibited (greater than 70%) by adding Co2+ or Mn2+ (1-3 mM) or Cd2+ (50-400 microM) to Ca-containing solutions, or by removal of Ca2+ from the perfusate. These effects were not accompanied by detectable changes in threshold voltage. The amplitude of TOC was also depressed by the organic Ca2+ channel blocker methoxyverapamil (D600). Finally replacement of Ca2+ by Ba2+ in the perfusate completely and reversibly abolished the TOC. 8. These findings suggest that neurosecretory neurones of the rat supraoptic nucleus display a transient K+ current which is strongly

  13. Thermal transient anemometer

    Science.gov (United States)

    Bailey, James L.; Vresk, Josip

    1989-01-01

    A thermal transient anemometer having a thermocouple probe which is utilized to measure the change in temperature over a period of time to provide a measure of fluid flow velocity. The thermocouple probe is located in the fluid flow path and pulsed to heat or cool the probe. The cooling of the heated probe or the heating of the cooled probe from the fluid flow over a period of time is measured to determine the fluid flow velocity. The probe is desired to be locally heated near the tip to increase the efficiency of devices incorporating the probe.

  14. DSN Transient Observatory

    Science.gov (United States)

    Kuiper, T. B. H.; Monroe, R. M.; White, L. A.; Garcia Miro, C.; Levin, S. M.; Majid, W. A.; Soriano, M.

    2016-11-01

    The Deep Space Network (DSN) Transient Observatory (DTO) is a signal processing facility that can monitor up to four DSN downlink bands for astronomically interesting signals. The monitoring is done commensally with reception of deep space mission telemetry. The initial signal processing is done with two CASPERa ROACH1 boards, each handling one or two baseband signals. Each ROACH1 has a 10 GBe interface with a GPU-equipped Debian Linux workstation for additional processing. The initial science programs include monitoring Mars for electrostatic discharges, radio spectral lines, searches for fast radio bursts and pulsars and SETI. The facility will be available to the scientific community through a peer review process.

  15. Nonlinear dynamics new directions models and applications

    CERN Document Server

    Ugalde, Edgardo

    2015-01-01

    This book, along with its companion volume, Nonlinear Dynamics New Directions: Theoretical Aspects, covers topics ranging from fractal analysis to very specific applications of the theory of dynamical systems to biology. This second volume contains mostly new applications of the theory of dynamical systems to both engineering and biology. The first volume is devoted to fundamental aspects and includes a number of important new contributions as well as some review articles that emphasize new development prospects. The topics addressed in the two volumes include a rigorous treatment of fluctuations in dynamical systems, topics in fractal analysis, studies of the transient dynamics in biological networks, synchronization in lasers, and control of chaotic systems, among others. This book also: ·         Develops applications of nonlinear dynamics on a diversity of topics such as patterns of synchrony in neuronal networks, laser synchronization, control of chaotic systems, and the study of transient dynam...

  16. Ultrafast Structure Switching through Nonlinear Phononics

    Science.gov (United States)

    Juraschek, D. M.; Fechner, M.; Spaldin, N. A.

    2017-02-01

    We describe a mechanism by which nonlinear phononics allows ultrafast coherent and directional control of transient structural distortions. With ErFeO3 as a model system, we use density functional theory to calculate the structural properties as input into an anharmonic phonon model that describes the response of the system to a pulsed optical excitation. We find that the trilinear coupling of two orthogonal infrared-active phonons to a Raman-active phonon causes a transient distortion of the lattice. In contrast to the quadratic-linear coupling that has been previously explored, the direction of the distortion is determined by the polarization of the exciting light, introducing a novel mechanism for nonlinear phononic switching. Since the occurrence of the coupling is determined by the symmetry of the system we propose that it is a universal feature of orthorhombic and tetragonal perovskites.

  17. Ultrafast Degenerate Transient Lens Spectroscopy in Semiconductor Nanosctructures

    Directory of Open Access Journals (Sweden)

    Leontyev A.V.

    2015-01-01

    Full Text Available We report the non-resonant excitation and probing of the nonlinear refractive index change in bulk semiconductors and semiconductor quantum dots through degenerate transient lens spectroscopy. The signal oscillates at the center laser field frequency, and the envelope of the former in quantum dots is distinctly different from the one in bulk sample. We discuss the applicability of this technique for polarization state probing in semiconductor media with femtosecond temporal resolution.

  18. Nonlinear Materials Characterization Facility

    Data.gov (United States)

    Federal Laboratory Consortium — The Nonlinear Materials Characterization Facility conducts photophysical research and development of nonlinear materials operating in the visible spectrum to protect...

  19. Electroretinography and Visual Evoked Potentials in Childhood Brain Tumor Survivors.

    Science.gov (United States)

    Pietilä, Sari; Lenko, Hanna L; Oja, Sakari; Koivisto, Anna-Maija; Pietilä, Timo; Mäkipernaa, Anne

    2016-07-01

    This population-based cross-sectional study evaluates the clinical value of electroretinography and visual evoked potentials in childhood brain tumor survivors. A flash electroretinography and a checkerboard reversal pattern visual evoked potential (or alternatively a flash visual evoked potential) were done for 51 survivors (age 3.8-28.7 years) after a mean follow-up time of 7.6 (1.5-15.1) years. Abnormal electroretinography was obtained in 1 case, bilaterally delayed abnormal visual evoked potentials in 22/51 (43%) cases. Nine of 25 patients with infratentorial tumor location, and altogether 12 out of 31 (39%) patients who did not have tumors involving the visual pathways, had abnormal visual evoked potentials. Abnormal electroretinographies are rarely observed, but abnormal visual evoked potentials are common even without evident anatomic lesions in the visual pathway. Bilateral changes suggest a general and possibly multifactorial toxic/adverse effect on the visual pathway. Electroretinography and visual evoked potential may have clinical and scientific value while evaluating long-term effects of childhood brain tumors and tumor treatment.

  20. Cortical evoked potentials recorded from the guinea pig without averaging.

    Science.gov (United States)

    Walloch, R A

    1975-01-01

    Potentials evoked by tonal pulses and recorded with a monopolar electrode on the pial surface over the auditory cortex of the guinea pig are presented. These potentials are compared with average potentials recorded in previous studies with an electrode on the dura. The potentials recorded by these two techniques have similar waveforms, peak latencies and thresholds. They appear to be generated within the same region of the cerebral cortex. As can be expected, the amplitude of the evoked potentials recorded from the pial surface is larger than that recorded from the dura. Consequently, averaging is not needed to extract the evoked potential once the dura is removed. The thresholds for the evoked cortical potential are similar to behavioral thresholds for the guinea pig at high frequencies; however, evoked potential thresholds are eleveate over behavioral thresholds at low frequencies. The removal of the dura and the direct recording of the evoked potential appears most appropriate for acute experiments. The recording of an evoked potential with dura electrodes empploying averaging procedures appears most appropriate for chronic studies.

  1. Analysis of nonlinear damping properties of carbon

    Science.gov (United States)

    Kazakova, Olga I.; Smolin, Igor Yu.; Bezmozgiy, Iosif M.

    2016-11-01

    This paper describes research results of nonlinear damping properties of carbon fiber reinforced plastics. The experimental and computational research is performed on flat composite specimens with the gradual structure complication (from 1 to 12 layers). Specimens are subjected to three types of testing which are modal, harmonic and transient analyses. Relationships between the amplitude response and damping ratio are obtained by means of the analysis of variance as the result of this research.

  2. Transient regional osteoporosis

    Directory of Open Access Journals (Sweden)

    F. Trotta

    2011-09-01

    Full Text Available Transient osteoporosis of the hip and regional migratory osteoporosis are uncommon and probably underdiagnosed bone diseases characterized by pain and functional limitation mainly affecting weight-bearing joints of the lower limbs. These conditions are usually self-limiting and symptoms tend to abate within a few months without sequelae. Routine laboratory investigations are unremarkable. Middle aged men and women during the last months of pregnancy or in the immediate post-partum period are principally affected. Osteopenia with preservation of articular space and transitory edema of the bone marrow provided by magnetic resonance imaging are common to these two conditions, so they are also known by the term regional transitory osteoporosis. The appearance of bone marrow edema is not specific to regional transitory osteoporosis but can be observed in several diseases, i.e. trauma, reflex sympathetic dystrophy, avascular osteonecrosis, infections, tumors from which it must be differentiated. The etiology of this condition is unknown. Pathogenesis is still debated in particular the relationship with reflex sympathetic dystrophy, with which regional transitory osteoporosis is often identified. The purpose of the present review is to remark on the relationship between transient osteoporosis of the hip and regional migratory osteoporosis with particular attention to the bone marrow edema pattern and relative differential diagnosis.

  3. Transient Black Hole Binaries

    CERN Document Server

    Belloni, T M

    2016-01-01

    The last two decades have seen a great improvement in our understand- ing of the complex phenomenology observed in transient black-hole binary systems, especially thanks to the activity of the Rossi X-Ray Timing Explorer satellite, com- plemented by observations from many other X-ray observatories and ground-based radio, optical and infrared facilities. Accretion alone cannot describe accurately the intricate behavior associated with black-hole transients and it is now clear that the role played by different kinds of (often massive) outflows seen at different phases of the outburst evolution of these systems is as fundamental as the one played by the accretion process itself. The spectral-timing states originally identified in the X-rays and fundamentally based on the observed effect of accretion, have acquired new importance as they now allow to describe within a coherent picture the phenomenology observed at other wave- length, where the effects of ejection processes are most evident. With a particular focu...

  4. Characterizing Nanoscale Transient Communication.

    Science.gov (United States)

    Chen, Yifan; Anwar, Putri Santi; Huang, Limin; Asvial, Muhamad

    2016-04-01

    We consider the novel paradigm of nanoscale transient communication (NTC), where certain components of the small-scale communication link are physically transient. As such, the transmitter and the receiver may change their properties over a prescribed lifespan due to their time-varying structures. The NTC systems may find important applications in the biomedical, environmental, and military fields, where system degradability allows for benign integration into life and environment. In this paper, we analyze the NTC systems from the channel-modeling and capacity-analysis perspectives and focus on the stochastically meaningful slow transience scenario, where the coherence time of degeneration Td is much longer than the coding delay Tc. We first develop novel and parsimonious models to characterize the NTC channels, where three types of physical layers are considered: electromagnetism-based terahertz (THz) communication, diffusion-based molecular communication (DMC), and nanobots-assisted touchable communication (TouchCom). We then revisit the classical performance measure of ϵ-outage channel capacity and take a fresh look at its formulations in the NTC context. Next, we present the notion of capacity degeneration profile (CDP), which describes the reduction of channel capacity with respect to the degeneration time. Finally, we provide numerical examples to demonstrate the features of CDP. To the best of our knowledge, the current work represents a first attempt to systematically evaluate the quality of nanoscale communication systems deteriorating with time.

  5. Language related differences of the sustained response evoked by natural speech sounds.

    Science.gov (United States)

    Fan, Christina Siu-Dschu; Zhu, Xingyu; Dosch, Hans Günter; von Stutterheim, Christiane; Rupp, André

    2017-01-01

    In tonal languages, such as Mandarin Chinese, the pitch contour of vowels discriminates lexical meaning, which is not the case in non-tonal languages such as German. Recent data provide evidence that pitch processing is influenced by language experience. However, there are still many open questions concerning the representation of such phonological and language-related differences at the level of the auditory cortex (AC). Using magnetoencephalography (MEG), we recorded transient and sustained auditory evoked fields (AEF) in native Chinese and German speakers to investigate language related phonological and semantic aspects in the processing of acoustic stimuli. AEF were elicited by spoken meaningful and meaningless syllables, by vowels, and by a French horn tone. Speech sounds were recorded from a native speaker and showed frequency-modulations according to the pitch-contours of Mandarin. The sustained field (SF) evoked by natural speech signals was significantly larger for Chinese than for German listeners. In contrast, the SF elicited by a horn tone was not significantly different between groups. Furthermore, the SF of Chinese subjects was larger when evoked by meaningful syllables compared to meaningless ones, but there was no significant difference regarding whether vowels were part of the Chinese phonological system or not. Moreover, the N100m gave subtle but clear evidence that for Chinese listeners other factors than purely physical properties play a role in processing meaningful signals. These findings show that the N100 and the SF generated in Heschl's gyrus are influenced by language experience, which suggests that AC activity related to specific pitch contours of vowels is influenced in a top-down fashion by higher, language related areas. Such interactions are in line with anatomical findings and neuroimaging data, as well as with the dual-stream model of language of Hickok and Poeppel that highlights the close and reciprocal interaction between

  6. Habituation of evoked responses is greater in patients with familial hemiplegic migraine than in controls

    DEFF Research Database (Denmark)

    Hansen, Jakob Møller; Bolla, M; Magis, D

    2011-01-01

    Familial hemiplegic migraine (FHM) is a rare, dominantly inherited subtype of migraine with transient hemiplegia during the aura phase. Mutations in at least three different genes can produce the FHM phenotype. The mutated FHM genes code for ion transport proteins that animal and cellular studies...... have associated with disturbed ion homeostasis, altered cellular excitability, neurotransmitter release, and decreased threshold for cortical spreading depression. The common forms of migraine are characterized interictally by a habituation deficit of cortical and subcortical evoked responses that has...... been attributed to neuronal dysexcitability. FHM and the common forms of migraine are thought to belong to a spectrum of migraine phenotypes with similar pathophysiology, and we therefore examined whether an abnormal habituation pattern would also be found in FHM patients....

  7. ATP inhibits Ins(1,4,5)P3-evoked Ca2+ release in smooth muscle via P2Y1 receptors.

    Science.gov (United States)

    MacMillan, D; Kennedy, C; McCarron, J G

    2012-11-01

    Adenosine 5'-triphosphate (ATP) mediates a variety of biological functions following nerve-evoked release, via activation of either G-protein-coupled P2Y- or ligand-gated P2X receptors. In smooth muscle, ATP, acting via P2Y receptors (P2YR), may act as an inhibitory neurotransmitter. The underlying mechanism(s) remain unclear, but have been proposed to involve the production of inositol 1,4,5-trisphosphate [Ins(1,4,5)P(3)] by phospholipase C (PLC), to evoke Ca(2+) release from the internal store and stimulation of Ca(2+)-activated potassium (K(Ca)) channels to cause membrane hyperpolarization. This mechanism requires Ca(2+) release from the store. However, in the present study, ATP evoked transient Ca(2+) increases in only ∼10% of voltage-clamped single smooth muscle cells. These results do not support activation of K(Ca) as the major mechanism underlying inhibition of smooth muscle activity. Interestingly, ATP inhibited Ins(1,4,5)P(3)-evoked Ca(2+) release in cells that did not show a Ca(2+) rise in response to purinergic activation. The reduction in Ins(1,4,5)P(3)-evoked Ca(2+) release was not mimicked by adenosine and therefore, cannot be explained by hydrolysis of ATP to adenosine. The reduction in Ins(1,4,5)P(3)-evoked Ca(2+) release was, however, also observed with its primary metabolite, ADP, and blocked by the P2Y(1)R antagonist, MRS2179, and the G protein inhibitor, GDPβS, but not by PLC inhibition. The present study demonstrates a novel inhibitory effect of P2Y(1)R activation on Ins(1,4,5)P(3)-evoked Ca(2+) release, such that purinergic stimulation acts to prevent Ins(1,4,5)P(3)-mediated increases in excitability in smooth muscle and promote relaxation.

  8. Effective Path Towards Relativistic Transients at Millimeter Wavelengths

    CERN Document Server

    Carbajo, Sergio; Cankaya, Huseyin; Alcorta, Paula; Ravi, Koustuban; Ahr, Frederike; Wu, Xiaojun; Fallahi, Arya; Kärtner, Franz X

    2016-01-01

    We refine the method towards extraction of sub-cycle transients in the 0.1-1 THz frequency (mm-wavelength) range from optical rectification in lithium niobate using tilted pulse fronts. Our scheme exploits previously unexplored spatio-temporal shaping of the pump pulses, resulting in highly efficient and near diffraction-limited sub-THz transients reaching 0.2 GV/m electric field strengths in free-space using only mJ-level optical ps-pulses. We address experimentally and theoretically the means to producing above-GV/m relativistic sub-THz transients with proper beam confinement and under moderate pumping conditions, thereby bringing widespread access to strong-field and nonlinear terahertz applications and devices.

  9. Self Referencing Heterodyne Transient Grating Spectroscopy with Short Wavelength

    Directory of Open Access Journals (Sweden)

    Jakob Grilj

    2015-04-01

    Full Text Available Heterodyning by a phase stable reference electric field is a well known technique to amplify weak nonlinear signals. For short wavelength, the generation of a reference field in front of the sample is challenging because of a lack of suitable beamsplitters. Here, we use a permanent grating which matches the line spacing of the transient grating for the creation of a phase stable reference field. The relative phase among the two can be changed by a relative translation of the permanent and transient gratings in direction orthogonal to the grating lines. We demonstrate the technique for a transient grating on a VO2 thin film and observe constructive as well as destructive interference signals.

  10. Transient Performance of Electrical System in a Military Vehicle

    Directory of Open Access Journals (Sweden)

    Zang Kemao

    2004-01-01

    Full Text Available Electrical system in a military vehicle is a low voltage (28 V dc system which is an unsymmetrical and nonlinear system made up of silicon-rectifying generator and a battery in parallel. Studies have been carried out using numerical method to calculate its transient performance. State variable and coordinate transformation have been adopted to express the functional modes and its transfer law of the silicon-rectifying generator; the battery is expressed as a simplified equivalent circuit according to its characteristics during transient process: Consequently, the general mathematical model of electrical system in a military vehicle is presented. Examples of electrical systems in somemilitary vehicles have been taken to carry out the calculation of transient performance and the findings have been compared with the test results of an actual vehicle to show that the numerical method designed works.

  11. Switching Tracking Control for Planar Systems with Transient Performance Constraints

    Institute of Scientific and Technical Information of China (English)

    SU Qing-Yu; SUN Xi-Ming; ZHAO Jun

    2013-01-01

    This paper studies the output tracking problem for a class of planar systems with some given transient performance constraints which are determined by the overshoot and the settling time.The problem of switched static output feedback tracking with output constraints (SSOFTOC) is proposed and solved for the first time.The static output feedback controllers and a so-called conic switching law are designed under which the output of the closed-loop switched system can track the step signal asymptotically without violating the transient performance constraints.Furthermore,an optimal weighted transient performance is obtained by.solving a nonlinear programming problem.Finally,a numerical example and an application to aircraft turbofan engine are given to illustrate the effectiveness and the applicability of the proposed method.

  12. Nonlinear optical properties of metal nanoparticle composites for optical applications

    Energy Technology Data Exchange (ETDEWEB)

    Takeda, Y. E-mail: takeda.yoshihiko@nims.go.jp; Kishimoto, N

    2003-05-01

    Optical absorption and nonlinear optical response were investigated for nanoparticle composites in amorphous SiO{sub 2} fabricated by negative Ta ion implantation at 60 keV. X-ray photoelectron spectroscopy was used to identify Ta and the oxide formation in the matrix. Optical absorption clearly indicated a surface plasmon peak at 2.2 eV and the peak resulted from formation of nanoparticles embedded in the matrix. The measured absorption was compared with calculated ones, evaluated by Maxwell-Garnett theory. Nonlinear absorption was measured with a pump-probe method using a femtosecond laser system. The pumping laser transiently bleached the surface plasmon band and lead to the nonlinearity. The transient response recovered in several picoseconds and behaved in terms of electron dynamics in metallic nanoparticles. The Ta nanoparticle composite is one of the promising candidates for nonlinear optical materials with good thermal stability.

  13. Receptor-like activity evoked by extracellular ADP in Arabidopsis root epidermal plasma membrane.

    Science.gov (United States)

    Demidchik, Vadim; Shang, Zhonglin; Shin, Ryoung; Colaço, Renato; Laohavisit, Anuphon; Shabala, Sergey; Davies, Julia M

    2011-07-01

    Extracellular purine nucleotides are implicated in the control of plant development and stress responses. While extracellular ATP is known to activate transcriptional pathways via plasma membrane (PM) NADPH oxidase and calcium channel activation, very little is known about signal transduction by extracellular ADP. Here, extracellular ADP was found to activate net Ca(2+) influx in roots of Arabidopsis (Arabidopsis thaliana) and transiently elevate cytosolic free Ca(2+) in root epidermal protoplasts. An inward Ca(2+)-permeable conductance in root epidermal PM was activated within 1 s of ADP application and repeated application evoked a smaller current. Such response speed and densitization are consistent with operation of equivalents to animal ionotropic purine receptors, although to date no equivalent genes for such receptors have been identified in higher plants. In contrast to ATP, extracellular ADP did not evoke accumulation of intracellular reactive oxygen species. While high concentrations of ATP caused net Ca(2+) efflux from roots, equivalent concentrations of ADP caused net influx. Overall the results point to a discrete ADP signaling pathway, reliant on receptor-like activity at the PM.

  14. Receptor-Like Activity Evoked by Extracellular ADP in Arabidopsis Root Epidermal Plasma Membrane1

    Science.gov (United States)

    Demidchik, Vadim; Shang, Zhonglin; Shin, Ryoung; Colaço, Renato; Laohavisit, Anuphon; Shabala, Sergey; Davies, Julia M.

    2011-01-01

    Extracellular purine nucleotides are implicated in the control of plant development and stress responses. While extracellular ATP is known to activate transcriptional pathways via plasma membrane (PM) NADPH oxidase and calcium channel activation, very little is known about signal transduction by extracellular ADP. Here, extracellular ADP was found to activate net Ca2+ influx in roots of Arabidopsis (Arabidopsis thaliana) and transiently elevate cytosolic free Ca2+ in root epidermal protoplasts. An inward Ca2+-permeable conductance in root epidermal PM was activated within 1 s of ADP application and repeated application evoked a smaller current. Such response speed and densitization are consistent with operation of equivalents to animal ionotropic purine receptors, although to date no equivalent genes for such receptors have been identified in higher plants. In contrast to ATP, extracellular ADP did not evoke accumulation of intracellular reactive oxygen species. While high concentrations of ATP caused net Ca2+ efflux from roots, equivalent concentrations of ADP caused net influx. Overall the results point to a discrete ADP signaling pathway, reliant on receptor-like activity at the PM. PMID:21562328

  15. Hearing outcomes after loss of brainstem auditory evoked potentials during microvascular decompression.

    Science.gov (United States)

    Thirumala, Parthasarathy D; Krishnaiah, Balaji; Habeych, Miguel E; Balzer, Jeffrey R; Crammond, Donald J

    2015-04-01

    The primary aim of this paper is to study the pre-operative characteristics, intra-operative changes and post-operative hearing outcomes in patients after complete loss of wave V of the brainstem auditory evoked potential. We retrospectively analyzed the brainstem auditory evoked potential data of 94 patients who underwent microvascular decompression for hemifacial spasm at our institute. Patients were divided into two groups - those with and those without loss of wave V. The differences between the two groups and outcomes were assessed using t-test and chi-squared tests. In our study 23 (24%) patients out of 94 had a complete loss of wave V, with 11 (48%) patients experiencing transient loss and 12 (52%) patients experiencing permanent loss. The incidence of hearing loss in patients with no loss of wave V was 5.7% and 26% in patients who did experience wave V loss. The incidence of hearing change in patients with no loss of wave V was 12.6% and 30.43% in patients who did experience wave V loss. Loss of wave V during the procedure or at the end of procedure significantly increases the odds of hearing loss. Hearing change is a significant under-reported clinical condition after microvascular decompression in patients who have loss of wave V.

  16. Mechanical Stimulation by Postnasal Drip Evokes Cough.

    Directory of Open Access Journals (Sweden)

    Toshiyuki Iwata

    Full Text Available Cough affects all individuals at different times, and its economic burden is substantial. Despite these widespread adverse effects, cough research relies on animal models, which hampers our understanding of the fundamental cause of cough. Postnasal drip is speculated to be one of the most frequent causes of chronic cough; however, this is a matter of debate. Here we show that mechanical stimuli by postnasal drip cause chronic cough. We distinguished human cough from sneezes and expiration reflexes by airflow patterns. Cough and sneeze exhibited one-peak and two-peak patterns, respectively, in expiratory airflow, which were also confirmed by animal models of cough and sneeze. Transgenic mice with ciliary dyskinesia coughed substantially and showed postnasal drip in the pharynx; furthermore, their cough was completely inhibited by nasal airway blockade of postnasal drip. We successfully reproduced cough observed in these mice by injecting artificial postnasal drip in wild-type mice. These results demonstrated that mechanical stimulation by postnasal drip evoked cough. The findings of our study can therefore be used to develop new antitussive drugs that prevent the root cause of cough.

  17. Mechanical Stimulation by Postnasal Drip Evokes Cough.

    Science.gov (United States)

    Iwata, Toshiyuki; Ito, Isao; Niimi, Akio; Ikegami, Koji; Marumo, Satoshi; Tanabe, Naoya; Nakaji, Hitoshi; Kanemitsu, Yoshihiro; Matsumoto, Hisako; Kamei, Junzo; Setou, Mitsutoshi; Mishima, Michiaki

    2015-01-01

    Cough affects all individuals at different times, and its economic burden is substantial. Despite these widespread adverse effects, cough research relies on animal models, which hampers our understanding of the fundamental cause of cough. Postnasal drip is speculated to be one of the most frequent causes of chronic cough; however, this is a matter of debate. Here we show that mechanical stimuli by postnasal drip cause chronic cough. We distinguished human cough from sneezes and expiration reflexes by airflow patterns. Cough and sneeze exhibited one-peak and two-peak patterns, respectively, in expiratory airflow, which were also confirmed by animal models of cough and sneeze. Transgenic mice with ciliary dyskinesia coughed substantially and showed postnasal drip in the pharynx; furthermore, their cough was completely inhibited by nasal airway blockade of postnasal drip. We successfully reproduced cough observed in these mice by injecting artificial postnasal drip in wild-type mice. These results demonstrated that mechanical stimulation by postnasal drip evoked cough. The findings of our study can therefore be used to develop new antitussive drugs that prevent the root cause of cough.

  18. [Intraoperative monitoring of visual evoked potentials].

    Science.gov (United States)

    Sasaki, Tatsuya; Ichikawa, Tsuyoshi; Sakuma, Jun; Suzuki, Kyouichi; Matsumoto, Masato; Itakura, Takeshi; Kodama, Namio; Murakawa, Masahiro

    2006-03-01

    Our success rate of intraoperative monitoring of visual evoked potential (VEP) had been approximately 30% in the past. In order to improve recording rate of intraoperative VEP, we developed a new stimulating device using high power light emitting diodes. Electroretinogram was simultaneously recorded to understand whether flash stimulation reached the retina. In addition, total venous anesthesia with propofol was used to avoid the adverse effect of inhalation anesthesia. We report the results after introduction of these improvements. Intraoperative monitoring of VEP was attempted in 35 cases. We evaluated success rate of VEP recording, correlation between VEP findings and postoperative visual function, and reasons why recording was not successful. Stable and reproducible waveforms were obtained in 59 sides (84%). Two cases, whose VEP deteriorated intraoperatively, developed postoperative visual disturbance: In 11 sides (16%), stable waveforms were not obtained. There were two main causes. In 8 sides out of 11, the cause was attributed to pre-existing severe visual disturbance. In these 8 sides, VEP in the awake state was not recordable or was recordable, but with very low amplitudes under 1 microV. In the other 3 sides, the cause was attributed to movement of a stimulating device by reflecting the fronto-temporal scalp flap. In conclusion, the successful recording rate was increased to 84% from approximately 30%, after introduction of various trials. We need further improvement in recording intraoperative VEP to establish a reliable intraoperative monitoring method for VEP.

  19. Nonlinear dynamic analysis of traveling wave-type ultrasonic motors.

    Science.gov (United States)

    Nakagawa, Yosuke; Saito, Akira; Maeno, Takashi

    2008-03-01

    In this paper, nonlinear dynamic response of a traveling wave-type ultrasonic motor was investigated. In particular, understanding the transient dynamics of a bar-type ultrasonic motor, such as starting up and stopping, is of primary interest. First, the transient response of the bar-type ultrasonic motor at starting up and stopping was measured using a laser Doppler velocimeter, and its driving characteristics are discussed in detail. The motor is shown to possess amplitude-dependent nonlinearity that greatly influences the transient dynamics of the motor. Second, a dynamical model of the motor was constructed as a second-order nonlinear oscillator, which represents the dynamics of the piezoelectric ceramic, stator, and rotor. The model features nonlinearities caused by the frictional interface between the stator and the rotor, and cubic nonlinearity in the dynamics of the stator. Coulomb's friction model was employed for the interface model, and a stick-slip phenomenon is considered. Lastly, it was shown that the model is capable of representing the transient dynamics of the motor accurately. The critical parameters in the model were identified from measured results, and numerical simulations were conducted using the model with the identified parameters. Good agreement between the results of measurements and numerical simulations is observed.

  20. Nonlinear singular vectors and nonlinear singular values

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    A novel concept of nonlinear singular vector and nonlinear singular value is introduced, which is a natural generalization of the classical linear singular vector and linear singular value to the nonlinear category. The optimization problem related to the determination of nonlinear singular vectors and singular values is formulated. The general idea of this approach is demonstrated by a simple two-dimensional quasigeostrophic model in the atmospheric and oceanic sciences. The advantage and its applications of the new method to the predictability, ensemble forecast and finite-time nonlinear instability are discussed. This paper makes a necessary preparation for further theoretical and numerical investigations.

  1. Theory of strong-field attosecond transient absorption

    Science.gov (United States)

    Wu, Mengxi; Chen, Shaohao; Camp, Seth; Schafer, Kenneth J.; Gaarde, Mette B.

    2016-03-01

    Attosecond transient absorption is one of the promising new techniques being developed to exploit the availability of sub-femtosecond extreme ultraviolet (XUV) pulses to study the dynamics of the electron on its natural time scale. The temporal resolution in a transient absorption setup comes from the control of the relative delay and coherence between pump and probe pulses, while the spectral resolution comes from the characteristic width of the features that are being probed. In this review we focus on transient absorption scenarios where an attosecond pulse of XUV radiation creates a broadband excitation that is subsequently probed by a few cycle infrared (IR) laser. Because the attosecond XUV pulses are locked to the IR field cycle, the exchange of energy in the laser-matter interaction can be studied with unprecedented precision. We focus on the transient absorption by helium atoms of XUV radiation around the first ionization threshold, where we can simultaneoulsy solve the time-dependent Schrödinger equation for the single atom response and the Maxwell wave equation for the collective response of the nonlinear medium. We use a time-domain method that allows us to treat on an equal footing all the different linear and nonlinear processes by which the medium can exchange energy with the fields. We present several simple models, based on a few-level system interacting with a strong IR field, to explain many of the novel features found in attosecond transient absorption spectrograms. These include the presence of light-induced states, which demonstrate the ability to probe the dressed states of the atom. We also present a time-domain interpretation of the resonant pulse propagation features that appear in absorption spectra in dense, macroscopic media. We close by reviewing several recent experimental results that can be explained in terms of the models we discuss. Our aim is to present a road map for understanding future attosecond transient absorption

  2. Calculating transient rates from surveys

    CERN Document Server

    Carbone, Dario; Wijers, Ralph A M J; Rowlinson, Antonia

    2016-01-01

    We have developed a method to determine the transient surface density and transient rate for any given survey, using Monte-Carlo simulations. This method allows us to determine the transient rate as a function of both the flux and the duration of the transients in the whole flux-duration plane rather than one or a few points as currently available methods do. It is applicable to every survey strategy that is monitoring the same part of the sky, regardless the instrument or wavelength of the survey, or the target sources. We have simulated both top-hat and Fast Rise Exponential Decay light curves, highlighting how the shape of the light curve might affect the detectability of transients. Another application for this method is to estimate the number of transients of a given kind that are expected to be detected by a survey, provided that their rate is known.

  3. Calculating transient rates from surveys

    Science.gov (United States)

    Carbone, D.; van der Horst, A. J.; Wijers, R. A. M. J.; Rowlinson, A.

    2017-03-01

    We have developed a method to determine the transient surface density and transient rate for any given survey, using Monte Carlo simulations. This method allows us to determine the transient rate as a function of both the flux and the duration of the transients in the whole flux-duration plane rather than one or a few points as currently available methods do. It is applicable to every survey strategy that is monitoring the same part of the sky, regardless the instrument or wavelength of the survey, or the target sources. We have simulated both top-hat and Fast Rise Exponential Decay light curves, highlighting how the shape of the light curve might affect the detectability of transients. Another application for this method is to estimate the number of transients of a given kind that are expected to be detected by a survey, provided that their rate is known.

  4. [Brainstem auditory evoked potentials and somatosensory evoked potentials in Chiari malformation].

    Science.gov (United States)

    Moncho, Dulce; Poca, María A; Minoves, Teresa; Ferré, Alejandro; Rahnama, Kimia; Sahuquillo, Juan

    2013-06-16

    Introduccion. La malformacion de Chiari (MC) incluye una serie de anomalias congenitas que tienen como comun denominador la ectopia de las amigdalas del cerebelo por debajo del foramen magno, lo que puede condicionar fenomenos compresivos del troncoencefalo, la medula espinal alta y los nervios craneales, alterando las respuestas de los potenciales evocados auditivos del tronco cerebral (PEATC) y de los potenciales evocados somatosensoriales (PESS). Sin embargo, las indicaciones de ambas exploraciones en las MC han sido motivo de estudio en un numero limitado de publicaciones, centradas en series cortas y heterogeneas de pacientes. Objetivo. Revisar los hallazgos de los PEATC y los PESS en los estudios publicados en pacientes con MC tipo 1 (MC-1) o tipo 2 (MC-2), y su indicacion en el diagnostico, tratamiento y seguimiento, especialmente en la MC-1. Desarrollo. Es un estudio de revision realizado mediante analisis de los estudios publicados en Medline desde 1966, localizados mediante PubMed, utilizando combinaciones de las palabras clave 'Chiari malformation', 'Arnold-Chiari malformation', 'Chiari type 1 malformation', 'Arnold-Chiari type 1 malformation', 'evoked potentials', 'brainstem auditory evoked potentials' y 'somatosensory evoked potentials', asi como informacion de pacientes con MC-1 valorados en los servicios de neurocirugia y neurofisiologia clinica del Hospital Universitari Vall d'Hebron. Conclusiones. Los hallazgos mas comunes de los PESS son la reduccion en la amplitud cortical para el nervio tibial posterior, la reduccion o ausencia del potencial cervical del nervio mediano y el aumento del intervalo N13-N20. En el caso de los PEATC, los hallazgos mas frecuentes descritos son el aumento del intervalo I-V y la alteracion periferica o coclear.

  5. Decoupling of Double Extraction Turbo-Unit by Nonlinear Multivariable Inverse System Method

    Institute of Scientific and Technical Information of China (English)

    黎浩荣; 李立勤; 李东海; 宋兆星; 王伟

    2001-01-01

    A multivariable inverse nonlinear control scheme is developed to decouple the strongly nonlinear double extraction steam turbo-unit, improving the transient stability of the power and heating system. Computer simulation tests show that not only does the control scheme achieve satisfactory decoupling of the high and low pressure turbines and the electric power, remarkably improving the transient stability, but also the design is very intuitive and concise.

  6. Transient Analysis of a Magnetic Heat Pump

    Science.gov (United States)

    Schroeder, E. A.

    1985-01-01

    An experimental heat pump that uses a rare earth element as the refrigerant is modeled using NASTRAN. The refrigerant is a ferromagnetic metal whose temperature rises when a magnetic field is applied and falls when the magnetic field is removed. The heat pump is used as a refrigerator to remove heat from a reservoir and discharge it through a heat exchanger. In the NASTRAN model the components modeled are represented by one-dimensional ROD elements. Heat flow in the solids and fluid are analyzed. The problem is mildly nonlinear since the heat capacity of the refrigerant is temperature-dependent. One simulation run consists of a series of transient analyses, each representing one stroke of the heat pump. An auxiliary program was written that uses the results of one NASTRAN analysis to generate data for the next NASTRAN analysis.

  7. Transient transport processes in deformable porous media

    Institute of Scientific and Technical Information of China (English)

    Cs. Mészáros; (A). Bálint

    2011-01-01

    The basic partial differential equations relevant for convection-diffusion and convection-diffusion-wave phenomena are presented and solved analytically by using the MAPLE symbolic computer algebra system.The possible general nonlinear character of the constitutive equation of the convection-discussion process is replaced by a direct posteriori stochastic refinement of its solution represented for Dirichlet-type boundary conditions.A thermodynamic analysis is performed for connecting the relaxation time constants and Jacobi-determinants of deformations at transient transport processes.Finally,a new procedure for general description of coupled transport processes on the basis of the formalism originally developed for convection-free phenomena is presented by matrix analysis methods in the Fourier space.

  8. The Zwicky Transient Facility

    Science.gov (United States)

    Kulkarni, Shrinivas R.

    2016-01-01

    The Zwicky Transient Facility (ZTF) has been designed with a singular focus: a systematic exploration of the night sky at a magnitude level well suited for spectral classification and follow up with the existing class of 4-m to 10-m class telescopes. ZTF is the successor to the Palomar Transient Factory (PTF). The discovery engine for ZTF is a 47 square degree camera (realized through 16 e2V monolithic CCDs) that fills the entire focal plane of the 48-inch Oschin telescope of the Palomar Observatory. Single 30-s epoch sensitivity is about 20.5 in g and R bands. The Infarared Processing & Analysis Center (IPAC) is the data center for ZTF. ZTF is a public-private partnership with equal contributions from a consortium of world-wide partners and an NSF MSIP grant. Forty percent of ZTF time is set aside for two major community surveys: a 3-day cadence survey of high latitudes (to mimic LSST) and a time domain survey of the entire Northern Galactic plane. We expect first light in February 2017 and begin a 3-year survey starting summer of 2017. The first year will be spent on building up deep reference images of the sky (a must for transient surveys). During the second year IPAC will deliver near archival quality photometric products within 12 hours of observations. By comparison to reference images photometric alerts will be sent out. Year 3 will see the near real-time release of image differencing products. A Community Science Advisory Committee (CSAC), chaired by S. Ridgway (NOAO), has been set up to both advise the PI and to ensure that the US community's interests are well served. Astronomers interested in getting a head start on ZTF may wish to peruse the data releases from PTF. Young people (or young at heart) may wish to attend the annual summer school on PTF/ZTF (August, Caltech campus). The Principal Investigator (PI) for the project is S. Kulkarni and the Project Scientist is Eric Bellm.For further details please consult http://www.ptf.caltech.edu/ztf

  9. Evoked potentials and head injury. 1. Rating of evoked potential abnormality.

    Science.gov (United States)

    Rappaport, M; Hall, K; Hopkins, H K; Belleza, T

    1981-10-01

    This paper describes a method for rating the degree of abnormality of auditory, visual and somatosensory evoked potential patterns in head injury (HI) patients. Criteria for judging degree of EP abnormality are presented that allow assessment of the extent and severity of subcortical and cortical dysfunction associated with traumatic brain damage. Interrater reliability data based upon blind ratings of normal and HI patients are presented and shown to be highly significant. Tables of normative values of peak latencies and amplitudes are given and illustrations of EP patterns of different degrees of abnormality are presented.

  10. Transient osteoporosis of pregnancy.

    Science.gov (United States)

    Maliha, George; Morgan, Jordan; Vrahas, Mark

    2012-08-01

    Transient osteoporosis of pregnancy (TOP) is a rare yet perhaps under-reported condition that has affected otherwise healthy pregnancies throughout the world. The condition presents suddenly in the third trimester of a usually uneventful pregnancy and progressively immobilizes the mother. Radiographic studies detect drastic loss of bone mass, elevated rates of turnover in the bone, and oedema in the affected portion. Weakness of the bone can lead to fractures during delivery and other complications for the mother. Then, within weeks of labour, symptoms and radiological findings resolve. Aetiology is currently unknown, although neural, vascular, haematological, endocrine, nutrient-deficiency, and other etiologies have been proposed. Several treatments have also been explored, including simple bed rest, steroids, bisphosphonates, calcitonin, induced termination of pregnancy, and surgical intervention. The orthopedist plays an essential role in monitoring the condition (and potential complications) as well as ensuring satisfactory outcomes for both the mother and newborn.

  11. Transient Detection and Classification

    CERN Document Server

    Becker, Andrew C

    2008-01-01

    I provide an incomplete inventory of the astronomical variability that will be found by next-generation time-domain astronomical surveys. These phenomena span the distance range from near-Earth satellites to the farthest Gamma Ray Bursts. The surveys that detect these transients will issue alerts to the greater astronomical community; this decision process must be extremely robust to avoid a slew of ``false'' alerts, and to maintain the community's trust in the surveys. I review the functionality required of both the surveys and the telescope networks that will be following them up, and the role of VOEvents in this process. Finally, I offer some ideas about object and event classification, which will be explored more thoroughly by other articles in these proceedings.

  12. Stability of Ignition Transients

    Directory of Open Access Journals (Sweden)

    V.E. Zarko

    1991-07-01

    Full Text Available The problem of ignition stability arises in the case of the action of intense external heat stimuli when, resulting from the cut-off of solid substance heating, momentary ignition is followed by extinction. Physical pattern of solid propellant ignition is considered and ignition criteria available in the literature are discussed. It is shown that the above mentioned problem amounts to transient burning at a given arbitrary temperature distribution in the condensed phase. A brief survey of published data on experimental and theoretical studies on ignition stability is offered. The comparison between theory and experiment is shown to prove qualitatively the efficiency of the phenomenological approach in the theory. However, the methods of mathematical simulation as well as those of experimental studying of ignition phenomenon, especially at high fluxes, need to be improved.

  13. Transient heliosheath modulation

    Science.gov (United States)

    Quenby, J. J.; Webber, W. R.

    2015-10-01

    Voyager 1 has explored the solar wind-interstellar medium interaction region between the terminal shock and heliopause, following the intensity distribution of Galactic cosmic ray protons above 200 MeV energy. Before this component reached the expected galactic flux level at 121.7 au from the Sun, four episodes of rapid intensity change occurred with a behaviour similar to that found in Forbush Decreases in the inner Solar system, rather than that expected from a mechanism related to models for the long-term modulation found closer to the Sun. Because the mean solar wind flow is both expected and observed to be perpendicular to the radial direction close to the heliopause, an explanation is suggested in terms of transient radial flows related to possible heliopause boundary flapping. It is necessary that the radial flows are of the order either of the sound speed found for conditions downstream of the terminal shock or of the fluctuations found near the boundary by the Voyager 1 Low Energy Charged Particle detector and that the relevant cosmic ray diffusion perpendicular to the mean field is controlled by `slab' fluctuations accounting for about 20 per cent of the total power in the field variance. However, additional radial drift motion related to possible north to south gradients in the magnetic field may allow the inclusion of some diffusion according to the predictions of a theory based upon the presence of 2D turbulence. The required field gradients may arise due to field variation in the field carried by solar plasma flow deflected away from the solar equatorial plane. Modulation amounting to a total 30 per cent drop in galactic intensity requires explanation by a combination of transient effects.

  14. Multimodality evoked responses in the neurological assessment of the newborn.

    Science.gov (United States)

    Mercuri, E; von Siebenthal, K; Daniëls, H; Guzzetta, F; Casaer, P

    1994-09-01

    In recent years increased attention has been devoted to evoked potentials (EP) in newborns. This paper reviews the literature and data from our research group in an attempt to assess the diagnostic and prognostic value of evoked responses in the first weeks of life and their use in different age-specific clinical conditions. The results show that EP are a very sensitive measure of the integrity of the sensory pathways. They make it possible to follow normal physiological maturation and the abnormalities of development resulting from neurological lesions. Repeated measurements of visual evoked potentials and somatosensorial evoked potential are prognostically useful in term infants, but seem much more limited in preterm newborns in predicting neurodevelopmental outcome.

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

    Science.gov (United States)

    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.

  16. Identification of causal relations between haemodynamic variables, auditory evoked potentials and isoflurane by means of fuzzy logic

    DEFF Research Database (Denmark)

    Jensen, E W; Nebot, A; Caminal, P;

    1999-01-01

    The aim of this study was to identify a possible relationship between haemodynamic variables, auditory evoked potentials (AEP) and inspired fraction of isoflurane (ISOFl). Two different models (isoflurane and mean arterial pressure) were identified using the fuzzy inductive reasoning (FIR......) methodology. A fuzzy model is able to identify non-linear and linear components of a causal relationship by means of optimization of information content of available data. Nine young female patients undergoing hysterectomy under general anaesthesia were included. Mean arterial pressure (MAP), heart rate (HR...

  17. Tree-wave mixing of ordinary and backward electromagnetic waves: extraordinary transients

    CERN Document Server

    Slabko, Vitaly V; Tkachenko, Viktor A; Myslivets, Sergey A

    2016-01-01

    Three-wave mixing of ordinary and backward electromagnetic waves in pulsed regime is investigated in the metamaterials, which enable co-existence and phase matching of such waves. It is shown that opposite direction of phase velocity and energy flux in backward waves gives rise to extraordinary transient processes in greatly enhanced optical parametric amplification and in frequency up or down shifting nonlinear reflectivity. The discovered transients resemble slowed response of an oscillator on pulsed excitation in the vicinity of its resonance

  18. Laser evoked potentials in carpal tunnel syndrome.

    Science.gov (United States)

    de Tommaso, Marina; Libro, Giuseppe; Difruscolo, Olimpia; Sardaro, Michele; Serpino, Claudia; Calabrese, Rita; Vecchio, Eleonora; Livrea, Paolo

    2009-02-01

    The aim of this study was to evaluate the function of Adelta fibers at the hand level in patients with clinical symptoms of Carpal Tunnel Syndrome (CTS) using CO(2) laser evoked potentials (LEPs), in light of the intensity and distribution of sensory symptoms and pain. Thirty-four CTS outpatients (62 hands) were compared to 23 sex- and age-matched control subjects (46 hands). The periungueal skin of the first, second, third and fifth fingers, and the dorsum of the hands were stimulated in random order. The latency and amplitude of the N2, P2 and N1 components were evaluated with respect to the Nerve Conduction Study (NCS) data, clinical scales, pain intensity and glove-like symptoms distribution. The amplitude of the N2-P2 complex was significantly reduced in CTS hands compared to normal hands after stimulation of the second and third fingers, even in patients with mild nerve conduction impairment. No significant fifth finger LEP abnormalities were found in patients with glove-like distribution symptoms. The N2-P2 amplitude at the second and third fingers was positively correlated with the severity of sensory symptoms. The involvement of median nerve Adelta fibers in CTS seems to be an early phenomenon, which concurs with the impairment of large motor and sensory afferents and is linked to the severity of the disease. The finding of reduced sensory symptoms in patients with severe thin afferents damage, may suggest a slight expression of central sensitisation phenomena in the advanced stage of CTS syndrome.

  19. Pudendal somatosensory evoked potentials in normal women

    Directory of Open Access Journals (Sweden)

    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.

  20. Transient Go: A Mobile App for Transient Astronomy Outreach

    Science.gov (United States)

    Crichton, D.; Mahabal, A.; Djorgovski, S. G.; Drake, A.; Early, J.; Ivezic, Z.; Jacoby, S.; Kanbur, S.

    2016-12-01

    Augmented Reality (AR) is set to revolutionize human interaction with the real world as demonstrated by the phenomenal success of `Pokemon Go'. That very technology can be used to rekindle the interest in science at the school level. We are in the process of developing a prototype app based on sky maps that will use AR to introduce different classes of astronomical transients to students as they are discovered i.e. in real-time. This will involve transient streams from surveys such as the Catalina Real-time Transient Survey (CRTS) today and the Large Synoptic Survey Telescope (LSST) in the near future. The transient streams will be combined with archival and latest image cut-outs and other auxiliary data as well as historical and statistical perspectives on each of the transient types being served. Such an app could easily be adapted to work with various NASA missions and NSF projects to enrich the student experience.

  1. Inferring sparse networks for noisy transient processes

    Science.gov (United States)

    Tran, Hoang M.; Bukkapatnam, Satish T. S.

    2016-02-01

    Inferring causal structures of real world complex networks from measured time series signals remains an open issue. The current approaches are inadequate to discern between direct versus indirect influences (i.e., the presence or absence of a directed arc connecting two nodes) in the presence of noise, sparse interactions, as well as nonlinear and transient dynamics of real world processes. We report a sparse regression (referred to as the -min) approach with theoretical bounds on the constraints on the allowable perturbation to recover the network structure that guarantees sparsity and robustness to noise. We also introduce averaging and perturbation procedures to further enhance prediction scores (i.e., reduce inference errors), and the numerical stability of -min approach. Extensive investigations have been conducted with multiple benchmark simulated genetic regulatory network and Michaelis-Menten dynamics, as well as real world data sets from DREAM5 challenge. These investigations suggest that our approach can significantly improve, oftentimes by 5 orders of magnitude over the methods reported previously for inferring the structure of dynamic networks, such as Bayesian network, network deconvolution, silencing and modular response analysis methods based on optimizing for sparsity, transients, noise and high dimensionality issues.

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

    Science.gov (United States)

    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.

  3. Auditory evoked potentials and vestibular evoked myogenic potentials in evaluation of brainstem lesions in multiple sclerosis.

    Science.gov (United States)

    Ivanković, Anita; Nesek Mađarić, Vesna; Starčević, Katarina; Krbot Skorić, Magdalena; Gabelić, Tereza; Adamec, Ivan; Habek, Mario

    2013-05-15

    The aim of this study was to determine the roles of magnetic resonance imaging (MRI), auditory evoked potentials (AEP) and vestibular evoked myogenic potentials (VEMP) in the evaluation of brainstem involvement in multiple sclerosis (MS). Altogether 32 patients with the diagnosis of MS participated in the study. The following data was collected from all patients: age, gender, Expanded Disability Status Scale (EDSS) score, brainstem functional system score (BSFS) (part of the EDSS evaluating brainstem symptomatology), and involvement of the brainstem on the brain MRI. AEP and ocular VEMP (oVEMP) and cervical VEMP (cVEMP) were studied in all patients. BSFS, MRI, AEP, oVEMP and cVEMP involvement of the brainstem was evident in 9 (28.1%), 14 (43.8%), 7 (21.9%), 12 (37.5%) and 10 (31.0%) patients, respectively. None of the tests used showed statistically significant advantage in the detection of brainstem lesions. When combining oVEMP and cVEMP 18 (56.3%) patients showed brainstem involvement. This combination showed brainstem involvement in greater percentage than BSFS or AEP, with statistical significance (p=0.035 and p=0.007, respectively). VEMP is a reliable method in detection of brainstem involvement in MS. It is comparable with MRI, but superior to clinical examination or AEP. Copyright © 2013 Elsevier B.V. All rights reserved.

  4. Direct observation of the transient thermal-lensing effect using the phase-object Z-scan technique.

    Science.gov (United States)

    Yang, Junyi; Song, Yinglin

    2009-01-15

    A phase-object (PO) Z-scan technique, which can conveniently distinguish the transient thermal-lensing effect from the third-order nonlinear refraction, is described. The PO Z-scan trace of the transient thermal-lensing effect shows a valley-peak shape that is very different from the single-valley (peak) shape of the pure negative (positive) third-order nonlinearity. The nonlinear refraction of the C(70)/toluene solution is investigated by using the PO Z scan with 8 ns pulses at 532 nm wavelength as a test.

  5. 3D TRANSIENT COUPLED THERMO-ELASTIC-PLASTIC CONTACT SEALING ANALYSIS OF REACTOR PRESSURE VESSEL

    Institute of Scientific and Technical Information of China (English)

    Du Xuesong; Li Runfang; Lin Tengjiao

    2005-01-01

    Sealing analysis of sealing system in reactor pressure vessels is relevant with multiple nonlinear coupled-field effects, so even large-scale commercial finite element software cannot finish the complicated analysis. A fmite element method of 3D transient coupled thermo-elastic-plastic contact sealing analysis for reactor pressure vessels is presented, in which the surface nonlinearity,material nonlinearity, transient heat transfer nonlinearity and multiple coupled effect are taken into account and the sealing equation is coupling solved in iterative procedure. At the same time, a computational analysis program is developed, which is applied in the sealing analysis of experimental reactor pressure vessel, and the numerical results are in good coincidence with the experimental results. This program is also successful in analyzing the practical problem in engineering.

  6. NONLINEAR EXPECTATIONS AND NONLINEAR MARKOV CHAINS

    Institute of Scientific and Technical Information of China (English)

    PENG SHIGE

    2005-01-01

    This paper deals with nonlinear expectations. The author obtains a nonlinear generalization of the well-known Kolmogorov's consistent theorem and then use it to construct filtration-consistent nonlinear expectations via nonlinear Markov chains. Compared to the author's previous results, i.e., the theory of g-expectations introduced via BSDE on a probability space, the present framework is not based on a given probability measure. Many fully nonlinear and singular situations are covered. The induced topology is a natural generalization of Lp-norms and L∞-norm in linear situations.The author also obtains the existence and uniqueness result of BSDE under this new framework and develops a nonlinear type of von Neumann-Morgenstern representation theorem to utilities and present dynamic risk measures.

  7. The MWA Transients Survey (MWATS).

    Science.gov (United States)

    Bell, M.; Murphy, T.; Kaplan, D. L.; Croft, S. D.; Hancock, P.; Rowlinson, A.; Wayth, R.; Gaensler, B.; Hurley-Walker, N.; Offringa, A.; Loi, C.; Bannister, K.; Trott, C.; Marquart, J.

    2017-01-01

    We propose the continuation of the MWA transients survey to search for and monitor low frequency transient and variable radio sources in the southern sky. This proposal is aimed at commensally utilising data from the GLEAM-X (G0008) project in semester 2017-A. The aim of this commensal data acquisition is to commission long baseline observations for transient science. In particular this will involve studying the impact of the ionosphere on calibration and imaging, and developing the techniques needed to produce science quality data products. The proposed drift scans with LST locking (see G0008 proposal) are particularly exciting as we can test image subtraction for transient and variable identification. This survey is targeted at studying objects such as AGN (intrinsic and extrinsic variability), long duration synchrotron emitters, pulsars and transients of unknown origin. The maps generated from this survey will be analysed with the Variables and Slow Transients (VAST) detection pipeline. The motivation for this survey is as follows: (i) To obtain temporal data on an extremely large and robust sample of low frequency sources to explore and quantify both intrinsic and extrinsic variability; (ii) To search and find new classes of low frequency radio transients that previously remained undetected and obscured from multi-wavelength discovery; (iii) To place rigorous statistics on the occurrence of both transients and variables prior to the Australian SKA era.

  8. Evoked Culture and Evoked Nature: The Promise of Gene-Culture Co-Evolution Theory for Sociology

    OpenAIRE

    Walsh, Anthony; Yun, Ilhong

    2016-01-01

    The traditional sociological view of culture has been almost exclusively that of transmitted culture decoupled from biology. The concept of evoked culture brings biology “back in” since it identifies ecological challenges that evoked certain practices based on evolutionary imperatives. The practices are then passed on to subsequent generations as normative, and individuals best suited to these normative practices will enjoy greater fitness benefits than those less suited. In other words, prac...

  9. Eugenol and carvacrol excite first- and second-order trigeminal neurons and enhance their heat-evoked responses.

    Science.gov (United States)

    Klein, A H; Joe, C L; Davoodi, A; Takechi, K; Carstens, M I; Carstens, E

    2014-06-20

    Eugenol and carvacrol from clove and oregano, respectively, are agonists of the warmth-sensitive transient receptor potential channel TRPV3 and the irritant-sensitive transient receptor potential ankyrin (TRPA)-1. Eugenol and carvacrol induce oral irritation that rapidly desensitizes, accompanied by brief enhancement of innocuous warmth and heat pain in humans. We presently investigated if eugenol and carvacrol activate nociceptive primary afferent and higher order trigeminal neurons and enhance their heat-evoked responses, using calcium imaging of cultured trigeminal ganglion (TG) and dorsal root ganglion (DRG) neurons, and in vivo single-unit recordings in trigeminal subnucleus caudalis (Vc) of rats. Eugenol and carvacrol activated 20-30% of TG and 7-20% of DRG cells, the majority of which additionally responded to menthol, mustard oil and/or capsaicin. TG cell responses to innocuous (39°) and noxious (42 °C) heating were enhanced by eugenol and carvacrol. We identified dorsomedial Vc neurons responsive to noxious heating of the tongue in pentobarbital-anesthetized rats. Eugenol and carvacrol dose-dependently elicited desensitizing responses in 55% and 73% of heat-sensitive units, respectively. Responses to noxious heat were briefly enhanced by eugenol and carvacrol. Many eugenol- and carvacrol-responsive units also responded to menthol, cinnamaldehyde and capsaicin. These data support a peripheral site for eugenol and carvacrol to enhance warmth- and noxious heat-evoked responses of trigeminal neurons, and are consistent with the observation that these agonists briefly enhance warmth and heat pain on the human tongue.

  10. Spatiotemporal analysis of the cortical sources of the steady-state visual evoked potential.

    Science.gov (United States)

    Di Russo, Francesco; Pitzalis, Sabrina; Aprile, Teresa; Spitoni, Grazia; Patria, Fabiana; Stella, Alessandra; Spinelli, Donatella; Hillyard, Steven A

    2007-04-01

    This study aimed to characterize the neural generators of the steady-state visual evoked potential (SSVEP) to repetitive, 6 Hz pattern-reversal stimulation. Multichannel scalp recordings of SSVEPs and dipole modeling techniques were combined with functional magnetic resonance imaging (fMRI) and retinotopic mapping in order to estimate the locations of the cortical sources giving rise to the SSVEP elicited by pattern reversal. The time-varying SSVEP scalp topography indicated contributions from two major cortical sources, which were localized in the medial occipital and mid-temporal regions of the contralateral hemisphere. Colocalization of dipole locations with fMRI activation sites indicated that these two major sources of the SSVEP were located in primary visual cortex (V1) and in the motion sensitive (MT/V5) areas, respectively. Minor contributions from mid-occipital (V3A) and ventral occipital (V4/V8) areas were also considered. Comparison of SSVEP phase information with timing information collected in a previous transient VEP study (Di Russo et al. [2005] Neuroimage 24:874-886) suggested that the sequence of cortical activation is similar for steady-state and transient stimulation. These results provide a detailed spatiotemporal profile of the cortical origins of the SSVEP, which should enhance its use as an efficient clinical tool for evaluating visual-cortical dysfunction as well as an investigative probe of the cortical mechanisms of visual-perceptual processing.

  11. Somatosensory Evoked Potential Findings in Ankylosing Spondylitis

    Science.gov (United States)

    Cidem, Muharrem; Sahin, Zerrin; Aydin, Teoman; Aysal, Fikret

    2014-01-01

    Objective: Somatosensory evoked potential (SSEP) abnormalities were reported in patients with ankylosing spondylitis (AS). This study aimed to investigate SSEP abnormalities and its relation with clinical findings in AS patients. Materials and Methods: The study included 26 patients with AS and 17 age-matched health volunteers (Control for SSEP). Median nerve SSEP findings were normal in all AS cases. Results: However, delayed latency and/or very low amplitude of tibial nerve SSEP was found in 20 (76.9%) AS patients. There were significant correlations between tibial SSEP latency and disease duration (R=0.433 to 0.635). There was also an inverse correlation between tibial SSEP amplitude and disease duration (R=−0.429, p=0.047). Serum estradiol level, hip total bone mineral density, The Bath Ankylosing Spondylitis Functional Index (BASFI) score and Beck depression score were significantly lower in AS patients with SSEP abnormalities (37.3±10.8 pg/mL, 0.916±0.123 g/cm2, 35.0±27.9, 12.8±8.4, respectively) than in AS patients without SSEP abnormalities (53.7±12.3 pg/mL, 1.103±0.197 g/cm2, 64.8±15.5, 24.8±10.1, respectively). Conclusion: Significant inverse correlations between SSEP latencies and dehydroepiandrosterone sulphate (DHEAS) levels were found (R=−0.400 to −0.713). There were also significant inverse correlation between SSEP latencies and DHEAS/oestrogen index (R=−0.596 to −0.868), and between SSEP latencies and DHEAS/Progesterone index (R=−0.467 to −0.685). As a conclusion, this study indicates that tibial nerve SSEP abnormalities are common in patients with AS and there are significant correlations between clinical findings of AS and SSEP abnormalities. PMID:25610293

  12. Transient regional osteoporosis.

    Science.gov (United States)

    Cano-Marquina, Antonio; Tarín, Juan J; García-Pérez, Miguel-Ángel; Cano, Antonio

    2014-04-01

    Transient regional osteoporosis (TRO) is a disease that predisposes to fragility fracture in weight bearing joints of mid-life women and men. Pregnant women may also suffer the process, usually at the hip. The prevalence of TRO is lower than the systemic form, associated with postmenopause and advanced age, but may be falsely diminished by under-diagnosis. The disease may be uni- or bilateral, and may migrate to distinct joints. One main feature of TRO is spontaneous recovery. Pain and progressive limitation in the functionality of the affected joint(s) are key symptoms. In the case of the form associated with pregnancy, difficulties in diagnosis derive from the relatively young age at presentation and from the clinical overlapping with the frequent aches during gestation. Densitometric osteoporosis in the affected region is not always present, but bone marrow edema, with or without joint effusion, is detected by magnetic resonance. There are not treatment guidelines, but the association of antiresorptives to symptomatic treatment seems to be beneficial. Surgery or other orthopedic interventions can be required for specific indications, like hip fracture, intra-medullary decompression, or other.

  13. Applied hydraulic transients

    CERN Document Server

    Chaudhry, M Hanif

    2014-01-01

    This book covers hydraulic transients in a comprehensive and systematic manner from introduction to advanced level and presents various methods of analysis for computer solution. The field of application of the book is very broad and diverse and covers areas such as hydroelectric projects, pumped storage schemes, water-supply systems, cooling-water systems, oil pipelines and industrial piping systems. Strong emphasis is given to practical applications, including several case studies, problems of applied nature, and design criteria. This will help design engineers and introduce students to real-life projects. This book also: ·         Presents modern methods of analysis suitable for computer analysis, such as the method of characteristics, explicit and implicit finite-difference methods and matrix methods ·         Includes case studies of actual projects ·         Provides extensive and complete treatment of governed hydraulic turbines ·         Presents design charts, desi...

  14. The Rapid Transient Surveyor

    CERN Document Server

    Baranec, Christoph; Wright, Shelley A; Tonry, John; Tully, R Brent; Szapudi, István; Takamiya, Marianne; Hunter, Lisa; Riddle, Reed; Chen, Shaojie; Chun, Mark

    2016-01-01

    The Rapid Transient Surveyor (RTS) is a proposed rapid-response, high-cadence adaptive optics (AO) facility for the UH 2.2-m telescope on Maunakea. RTS will uniquely address the need for high-acuity and sensitive near-infrared spectral follow-up observations of tens of thousands of objects in mere months by combining an excellent observing site, unmatched robotic observational efficiency, and an AO system that significantly increases both sensitivity and spatial resolving power. We will initially use RTS to obtain the infrared spectra of ~4,000 Type Ia supernovae identified by the Asteroid Terrestrial-Impact Last Alert System over a two year period that will be crucial to precisely measuring distances and mapping the distribution of dark matter in the z < 0.1 universe. RTS will comprise an upgraded version of the Robo-AO laser AO system and will respond quickly to target-of-opportunity events, minimizing the time between discovery and characterization. RTS will acquire simultaneous-multicolor images with a...

  15. The rapid transient surveyor

    Science.gov (United States)

    Baranec, C.; Lu, J. R.; Wright, S. A.; Tonry, J.; Tully, R. B.; Szapudi, I.; Takamiya, M.; Hunter, L.; Riddle, R.; Chen, S.; Chun, M.

    2016-07-01

    The Rapid Transient Surveyor (RTS) is a proposed rapid-response, high-cadence adaptive optics (AO) facility for the UH 2.2-m telescope on Maunakea. RTS will uniquely address the need for high-acuity and sensitive near-infrared spectral follow-up observations of tens of thousands of objects in mere months by combining an excellent observing site, unmatched robotic observational efficiency, and an AO system that significantly increases both sensitivity and spatial resolving power. We will initially use RTS to obtain the infrared spectra of 4,000 Type Ia supernovae identified by the Asteroid Terrestrial-Impact Last Alert System over a two year period that will be crucial to precisely measuring distances and mapping the distribution of dark matter in the z efficiency prism integral field unit spectrograph: R = 70-140 over a total bandpass of 840-1830nm with an 8.7" by 6.0" field of view (0.15" spaxels). The AO correction boosts the infrared point-source sensitivity of the spectrograph against the sky background by a factor of seven for faint targets, giving the UH 2.2-m the H-band sensitivity of a 5.7-m telescope without AO.

  16. Tool for Turbine Engine Closed-Loop Transient Analysis (TTECTrA) Users' Guide

    Science.gov (United States)

    Csank, Jeffrey T.; Zinnecker, Alicia M.

    2014-01-01

    The tool for turbine engine closed-loop transient analysis (TTECTrA) is a semi-automated control design tool for subsonic aircraft engine simulations. At a specific flight condition, TTECTrA produces a basic controller designed to meet user-defined goals and containing only the fundamental limiters that affect the transient performance of the engine. The purpose of this tool is to provide the user a preliminary estimate of the transient performance of an engine model without the need to design a full nonlinear controller.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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.

  1. Conditioning effect of transcranial magnetic stimulation evoking motor-evoked potential on V-wave response.

    Science.gov (United States)

    Grosprêtre, Sidney; Martin, Alain

    2014-12-01

    The aim of this study was to examine the collision responsible for the volitional V-wave evoked by supramaximal electrical stimulation of the motor nerve during voluntary contraction. V-wave was conditioned by transcranial magnetic stimulation (TMS) over the motor cortex at several inter-stimuli intervals (ISI) during weak voluntary plantar flexions (n = 10) and at rest for flexor carpi radialis muscle (FCR; n = 6). Conditioning stimulations were induced by TMS with intensity eliciting maximal motor-evoked potential (MEPmax). ISIs used were ranging from -20 to +20 msec depending on muscles tested. The results showed that, for triceps surae muscles, conditioning TMS increased the V-wave amplitude (~ +250%) and the associated mechanical response (~ +30%) during weak voluntary plantar flexion (10% of the maximal voluntary contraction -MVC) for ISIs ranging from +6 to +18 msec. Similar effect was observed at rest for the FCR with ISI ranging from +6 to +12 msec. When the level of force was increased from 10 to 50% MVC or the conditioning TMS intensity was reduced to elicit responses of 50% of MEPmax, a significant decrease in the conditioned V-wave amplitude was observed for the triceps surae muscles, linearly correlated to the changes in MEP amplitude. The slope of this correlation, as well as the electro-mechanical efficiency, was closed to the identity line, indicating that V-wave impact at muscle level seems to be similar to the impact of cortical stimulation. All these results suggest that change in V-wave amplitude is a great index to reflect changes in cortical neural drive addressed to spinal motoneurons.

  2. Helioseismic Effects of Energetic Transients

    Indian Academy of Sciences (India)

    Ashok Ambastha

    2008-03-01

    Photospheric and chromospheric signatures related to large, energetic transients such as flares and CMEs, have been extensively reported during the last several years. In addition, energetic solar transients are expected to cause helioseismic effects. Some of the recent results are reviewed here; in particular, the helioseismic effects of the powerful flares in superactive region, NOAA 10486, including the 4B/X17 superflare of October 28, 2003. We also examine the temporal variations of power in low- modes during the period May 1995–October 2005, and compare with daily, disk-integrated flare- and CME-indices to infer the effect of transients on the scale of whole solar disk.

  3. Electromagnetic transients in power cables

    CERN Document Server

    da Silva, Filipe Faria

    2013-01-01

    From the more basic concepts to the most advanced ones where long and laborious simulation models are required, Electromagnetic Transients in Power Cables provides a thorough insight into the study of electromagnetic transients and underground power cables. Explanations and demonstrations of different electromagnetic transient phenomena are provided, from simple lumped-parameter circuits to complex cable-based high voltage networks, as well as instructions on how to model the cables.Supported throughout by illustrations, circuit diagrams and simulation results, each chapter contains exercises,

  4. Linear and nonlinear propagation of water wave groups

    Science.gov (United States)

    Pierson, W. J., Jr.; Donelan, M. A.; Hui, W. H.

    1992-01-01

    Results are presented from a study of the evolution of waveforms with known analytical group shapes, in the form of both transient wave groups and the cloidal (cn) and dnoidal (dn) wave trains as derived from the nonlinear Schroedinger equation. The waveforms were generated in a long wind-wave tank of the Canada Centre for Inland Waters. It was found that the low-amplitude transients behaved as predicted by the linear theory and that the cn and dn wave trains of moderate steepness behaved almost as predicted by the nonlinear Schroedinger equation. Some of the results did not fit into any of the available theories for waves on water, but they provide important insight on how actual groups of waves propagate and on higher-order effects for a transient waveform.

  5. Vestibular receptors contribute to cortical auditory evoked potentials.

    Science.gov (United States)

    Todd, Neil P M; Paillard, Aurore C; Kluk, Karolina; Whittle, Elizabeth; Colebatch, James G

    2014-03-01

    Acoustic sensitivity of the vestibular apparatus is well-established, but the contribution of vestibular receptors to the late auditory evoked potentials of cortical origin is unknown. Evoked potentials from 500 Hz tone pips were recorded using 70 channel EEG at several intensities below and above the vestibular acoustic threshold, as determined by vestibular evoked myogenic potentials (VEMPs). In healthy subjects both auditory mid- and long-latency auditory evoked potentials (AEPs), consisting of Na, Pa, N1 and P2 waves, were observed in the sub-threshold conditions. However, in passing through the vestibular threshold, systematic changes were observed in the morphology of the potentials and in the intensity dependence of their amplitude and latency. These changes were absent in a patient without functioning vestibular receptors. In particular, for the healthy subjects there was a fronto-central negativity, which appeared at about 42 ms, referred to as an N42, prior to the AEP N1. Source analysis of both the N42 and N1 indicated involvement of cingulate cortex, as well as bilateral superior temporal cortex. Our findings are best explained by vestibular receptors contributing to what were hitherto considered as purely auditory evoked potentials and in addition tentatively identify a new component that appears to be primarily of vestibular origin.

  6. A Comprehensive Review on Methodologies Employed for Visual Evoked Potentials.

    Science.gov (United States)

    Kothari, Ruchi; Bokariya, Pradeep; Singh, Smita; Singh, Ramji

    2016-01-01

    Visual information is fundamental to how we appreciate our environment and interact with others. The visual evoked potential (VEP) is among those evoked potentials that are the bioelectric signals generated in the striate and extrastriate cortex when the retina is stimulated with light which can be recorded from the scalp electrodes. In the current paper, we provide an overview of the various modalities, techniques, and methodologies which have been employed for visual evoked potentials over the years. In the first part of the paper, we cast a cursory glance on the historical aspect of evoked potentials. Then the growing clinical significance and advantages of VEPs in clinical disorders have been briefly described, followed by the discussion on the earlier and currently available methods for VEPs based on the studies in the past and recent times. Next, we mention the standards and protocols laid down by the authorized agencies. We then summarize the recently developed techniques for VEP. In the concluding section, we lay down prospective research directives related to fundamental and applied aspects of VEPs as well as offering perspectives for further research to stimulate inquiry into the role of visual evoked potentials in visual processing impairment related disorders.

  7. Linear superposition of sensory-evoked and ongoing cortical hemodynamics

    Directory of Open Access Journals (Sweden)

    Mohamad Saka

    2010-08-01

    Full Text Available Modern non-invasive brain imaging techniques utilise changes in cerebral blood flow, volume and oxygenation that accompany brain activation. However, stimulus-evoked hemodynamic responses display considerable inter-trial variability even when identical stimuli are presented and the sources of this variability are poorly understood. One of the sources of this response variation could be ongoing spontaneous hemodynamic fluctuations. To investigate this issue, 2-dimensional optical imaging spectroscopy was used to measure cortical hemodynamics in response to sensory stimuli in anaesthetised rodents Pre-stimulus cortical hemodynamics displayed spontaneous periodic fluctuations and as such, data from individual stimulus presentation trials were assigned to one of four groups depending on the phase angle of pre-stimulus hemodynamic fluctuations and averaged. This analysis revealed that sensory evoked cortical hemodynamics displayed distinctive response characteristics and magnitudes depending on the phase angle of ongoing fluctuations at stimulus onset. To investigate the origin of this phenomenon, ‘null-trails’ were collected without stimulus presentation. Subtraction of phase averaged ‘null trials’ from their phase averaged stimulus-evoked counterparts resulted in four similar time series that resembled the mean stimulus-evoked response. These analyses suggest that linear superposition of evoked and ongoing cortical hemodynamic changes may be a property of the structure of inter-trial variability.

  8. Transient human auditory cortex activation during volitional attention shifting.

    Science.gov (United States)

    Uhlig, Christian Harm; Gutschalk, Alexander

    2017-01-01

    While strong activation of auditory cortex is generally found for exogenous orienting of attention, endogenous, intra-modal shifting of auditory attention has not yet been demonstrated to evoke transient activation of the auditory cortex. Here, we used fMRI to test if endogenous shifting of attention is also associated with transient activation of the auditory cortex. In contrast to previous studies, attention shifts were completely self-initiated and not cued by transient auditory or visual stimuli. Stimuli were two dichotic, continuous streams of tones, whose perceptual grouping was not ambiguous. Participants were instructed to continuously focus on one of the streams and switch between the two after a while, indicating the time and direction of each attentional shift by pressing one of two response buttons. The BOLD response around the time of the button presses revealed robust activation of the auditory cortex, along with activation of a distributed task network. To test if the transient auditory cortex activation was specifically related to auditory orienting, a self-paced motor task was added, where participants were instructed to ignore the auditory stimulation while they pressed the response buttons in alternation and at a similar pace. Results showed that attentional orienting produced stronger activity in auditory cortex, but auditory cortex activation was also observed for button presses without focused attention to the auditory stimulus. The response related to attention shifting was stronger contralateral to the side where attention was shifted to. Contralateral-dominant activation was also observed in dorsal parietal cortex areas, confirming previous observations for auditory attention shifting in studies that used auditory cues.

  9. Nonlinear Analyses of the Dynamic Properties of Hydrostatic Bearing Systems

    Institute of Scientific and Technical Information of China (English)

    LIU Wei(刘伟); WU Xiujiang(吴秀江); V.A. Prokopenko

    2003-01-01

    Nonlinear analyses of hydrostatic bearing systems are necessary to adequately model the fluid-solid interaction. The dynamic properties of linear and nonlinear analytical models of hydrostatic bearings are compared in this paper. The analyses were based on the determination of the aperiodic border of transient processes with external step loads. The results show that the dynamic properties can be most effectively improved by increasing the hydrostatic bearing crosspiece width and additional pocket volume in a bearing can extend the load range for which the transient process is aperiodic, but an additional restrictor and capacitor (RC) chain must be introduced for increasing damping. The nonlinear analyses can also be used to predict typical design parameters for a hydrostatic bearing.

  10. Three-dimensional nonlinear acoustical holography

    Science.gov (United States)

    Niu, Yaying

    Nearfield Acoustical Holography (NAH) is an acoustic field visualization technique that can be used to reconstruct three-dimensional (3-D) acoustic fields by projecting two-dimensional (2-D) data measured on a hologram surface. However, linear NAH algorithms developed and improved by many researchers can result in significant reconstruction errors when they are applied to reconstruct 3-D acoustic fields that are radiated from a high-level noise source and include significant nonlinear components. Here, planar, nonlinear acoustical holography procedures are developed that can be used to reconstruct 3-D, nonlinear acoustic fields radiated from a high-level noise source based on 2-D acoustic pressure data measured on a hologram surface. The first nonlinear acoustic holography procedure is derived for reconstructing steady-state acoustic pressure fields by applying perturbation and renormalization methods to nonlinear, dissipative, pressure-based Westervelt Wave Equation (WWE). The nonlinear acoustic pressure fields radiated from a high-level pulsating sphere and an infinite-size, vibrating panel are used to validate this procedure. Although the WWE-based algorithm is successfully validated by those two numerical simulations, it still has several limitations: (1) Only the fundamental frequency and its second harmonic nonlinear components can be reconstructed; (2) the application of this algorithm is limited to mono-frequency source cases; (3) the effects of bent wave rays caused by transverse particle velocities are not included; (4) only acoustic pressure fields can be reconstructed. In order to address the limitations of the steady-state, WWE-based procedure, a transient, planar, nonlinear acoustic holography algorithm is developed that can be used to reconstruct 3-D nonlinear acoustic pressure and particle velocity fields. This procedure is based on Kuznetsov Wave Equation (KWE) that is directly solved by using temporal and spatial Fourier Transforms. When compared

  11. Advances in nonlinear optics

    CERN Document Server

    Chen, Xianfeng; Zeng, Heping; Guo, Qi; She, Weilong

    2015-01-01

    This book presents an overview of the state of the art of nonlinear optics from weak light nonlinear optics, ultrafast nonlinear optics to electro-optical theory and applications. Topics range from the fundamental studies of the interaction between matter and radiation to the development of devices, components, and systems of tremendous commercial interest for widespread applications in optical telecommunications, medicine, and biotechnology.

  12. Distributed nonlinear optical response

    DEFF Research Database (Denmark)

    Nikolov, Nikola Ivanov

    2005-01-01

    The purpose of the research presented here is to investigate basic physical properties in nonlinear optical materials with delayed or nonlocal nonlinearity. Soliton propagation, spectral broadening and the influence of the nonlocality or delay of the nonlinearity are the main focusses in the work...

  13. Noncommutative Nonlinear Supersymmetry

    CERN Document Server

    Nishino, H; Nishino, Hitoshi; Rajpoot, Subhash

    2002-01-01

    We present noncommutative nonlinear supersymmetric theories. The first example is a non-polynomial Akulov-Volkov-type lagrangian with noncommutative nonlinear global supersymmetry in arbitrary space-time dimensions. The second example is the generalization of this lagrangian to Dirac-Born-Infeld lagrangian with nonlinear supersymmetry realized in dimensions D=2,3,4 and 6 (mod 8).

  14. Fiber Nonlinearities: A Tutorial

    Institute of Scientific and Technical Information of China (English)

    Govind P. Agrawal

    2003-01-01

    Fiber nonlinearities have long been regarded as being mostly harmful for fiber-optic communication systems. Over the last few years, however, the nonlinear effects are increasingly being used for practical telecommunications applications,the Raman amplification being only one of the recent examples. In this tutorial I review the vario us nonlinear effects occurring in optical fibers from both standpoints..

  15. Fiber Nonlinearities: A Tutorial

    Institute of Scientific and Technical Information of China (English)

    Govind; P.; Agrawal

    2003-01-01

    Fiber nonlinearities have long been regarded as being mostly harmful for fiber-optic communication systems. Over the last few years, however, the nonlinear effects are increasingly being used for practical telecommunications applications, the Raman amplification being only one of the recent examples. In this tutorial I review the various nonlinear effects occurring in optical fibers from both standpoints..

  16. Transient or permanent fisheye views

    DEFF Research Database (Denmark)

    Jakobsen, Mikkel Rønne; Hornbæk, Kasper

    2012-01-01

    , about the benefits and limitations of transient visualizations. We describe an experiment that compares the usability of a fisheye view that participants could call up temporarily, a permanent fisheye view, and a linear view: all interfaces gave access to source code in the editor of a widespread......Transient use of information visualization may support specific tasks without permanently changing the user interface. Transient visualizations provide immediate and transient use of information visualization close to and in the context of the user’s focus of attention. Little is known, however...... programming environment. Fourteen participants performed varied tasks involving navigation and understanding of source code. Participants used the three interfaces for between four and six hours in all. Time and accuracy measures were inconclusive, but subjective data showed a preference for the permanent...

  17. Transient heating of moving objects

    Directory of Open Access Journals (Sweden)

    E.I. Baida

    2014-06-01

    Full Text Available A mathematical model of transient and quasistatic heating of moving objects by various heat sources is considered. The mathematical formulation of the problem is described, examples of thermal calculation given.

  18. Horizontal vestibuloocular reflex evoked by high-acceleration rotations in the squirrel monkey. I. Normal responses

    Science.gov (United States)

    Minor, L. B.; Lasker, D. M.; Backous, D. D.; Hullar, T. E.; Shelhamer, M. J. (Principal Investigator)

    1999-01-01

    The horizontal angular vestibuloocular reflex (VOR) evoked by high-frequency, high-acceleration rotations was studied in five squirrel monkeys with intact vestibular function. The VOR evoked by steps of acceleration in darkness (3,000 degrees /s(2) reaching a velocity of 150 degrees /s) began after a latency of 7.3 +/- 1.5 ms (mean +/- SD). Gain of the reflex during the acceleration was 14.2 +/- 5.2% greater than that measured once the plateau head velocity had been reached. A polynomial regression was used to analyze the trajectory of the responses to steps of acceleration. A better representation of the data was obtained from a polynomial that included a cubic term in contrast to an exclusively linear fit. For sinusoidal rotations of 0.5-15 Hz with a peak velocity of 20 degrees /s, the VOR gain measured 0.83 +/- 0.06 and did not vary across frequencies or animals. The phase of these responses was close to compensatory except at 15 Hz where a lag of 5.0 +/- 0.9 degrees was noted. The VOR gain did not vary with head velocity at 0.5 Hz but increased with velocity for rotations at frequencies of >/=4 Hz (0. 85 +/- 0.04 at 4 Hz, 20 degrees /s; 1.01 +/- 0.05 at 100 degrees /s, P < 0.0001). No responses to these rotations were noted in two animals that had undergone bilateral labyrinthectomy indicating that inertia of the eye had a negligible effect for these stimuli. We developed a mathematical model of VOR dynamics to account for these findings. The inputs to the reflex come from linear and nonlinear pathways. The linear pathway is responsible for the constant gain across frequencies at peak head velocity of 20 degrees /s and also for the phase lag at higher frequencies being less than that expected based on the reflex delay. The frequency- and velocity-dependent nonlinearity in VOR gain is accounted for by the dynamics of the nonlinear pathway. A transfer function that increases the gain of this pathway with frequency and a term related to the third power of head

  19. Temporal resolution in the hearing system and auditory evoked potentials

    DEFF Research Database (Denmark)

    Miller, Lee; Beedholm, Kristian

    2008-01-01

    3pAB5. Temporal resolution in the hearing system and auditory evoked potentials. Kristian Beedholm Institute of Biology,University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark, beedholm@mail.dk, Lee A. Miller Institute of Biology,University of Southern Denmark, Campusvej 55, 5230...... Odense M, Denmark, lee@biology.sdu.dkA popular type of investigation with auditory evoked potentials AEP consists of mapping the dependency of the envelope followingresponse to the AM frequency. This results in what is called the modulation rate transfer function MRTF. The physiologicalinterpretation...... of the MRTF is not straight forward, but is often used as a measure of the ability of the auditory system to encodetemporal changes. It is, however, shown here that the MRTF must depend on the waveform of the click-evoked AEP ceAEP, whichdoes not relate directly to temporal resolution. The theoretical...

  20. Stimulator with arbitrary waveform for auditory evoked potentials

    Energy Technology Data Exchange (ETDEWEB)

    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.

  1. Neuronal Rac1 is required for learning-evoked neurogenesis

    DEFF Research Database (Denmark)

    Haditsch, Ursula; Anderson, Matthew P; Freewoman, Julia

    2013-01-01

    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...

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

    Science.gov (United States)

    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.

  3. PBH tests for nonlinear systems

    NARCIS (Netherlands)

    Kawano, Yu; Ohtsuka, Toshiyuki

    2017-01-01

    Recently, concepts of nonlinear eigenvalues and eigenvectors are introduced. In this paper, we establish connections between the nonlinear eigenvalues and nonlinear accessibility/observability. In particular, we provide a generalization of Popov- Belevitch-Hautus (PBH) test to nonlinear accessibilit

  4. Analysis of transients in advanced heavy water reactor using lumped parameter models

    Energy Technology Data Exchange (ETDEWEB)

    Manmohan Pandey; Venkata Ramana Eaga; Sankar Sastry, P. [Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati (India); Gupta, S.K.; Lele, H.G.; Chatterjee, B. [Reactor Safety Division, Bhabha Atomic Research Centre, Mumbai (India)

    2005-07-01

    Full text of publication follows: Analysis of transients occurring in nuclear power plants, arising from the complex interplay between core neutronics and thermal-hydraulics, is important for their operation and safety. Numerical simulations of such transients can be carried out extensively at very low computational cost by using lumped parameter mathematical models. The Advanced Heavy Water Reactor (AHWR), being developed in India, is a vertical pressure tube type reactor cooled by boiling light water under natural circulation, using thorium as fuel and heavy water as moderator. In the present work, nonlinear and linear lumped parameter dynamic models for AHWR have been developed and validated with a distributed parameter model. The nonlinear lumped model is based on point reactor kinetics equations and one-dimensional homogeneous equilibrium model of two-phase flow. The distributed model is built with RELAP5/MOD3.2 code. Various types of transients have been simulated numerically, using the lumped model as well as RELAP5. The results have been compared and parameters tuned to make the lumped model match the distributed model (RELAP5) in terms of steady state as well as dynamic behaviour. The linear model has been derived by linearizing the nonlinear model for small perturbations about the steady state. Numerical simulations of transients using the linear model have been compared with results obtained from the nonlinear model. Thus, the range of validity of the linear model has been determined. Stability characteristics of AHWR have been investigated using the lumped parameter models. (authors)

  5. Nonlinear Integral Sliding Mode Control for a Second Order Nonlinear System

    Directory of Open Access Journals (Sweden)

    Xie Zheng

    2015-01-01

    Full Text Available A nonlinear integral sliding-mode control (NISMC scheme is proposed for second order nonlinear systems. The new control scheme is characterized by a nonlinear integral sliding manifold which inherits the desired properties of the integral sliding manifold, such as robustness to system external disturbance. In particular, compared with four kinds of sliding mode control (SMC, the proposed control scheme is able to provide better transient performances. Furthermore, the proposed scheme ensures the zero steady-state error in the presence of a constant disturbance or an asymptotically constant disturbance is proved by Lyapunov stability theory and LaSalle invariance principle. Finally, both the theoretical analysis and simulation examples demonstrate the validity of the proposed scheme.

  6. The Transient MHD Flow Generated by a PeriodicWall Motion in a Porous Space

    Directory of Open Access Journals (Sweden)

    Mohammed Abdulhameed

    2016-01-01

    Full Text Available The problem of transient flow of incompressible third grade fluid on the two-dimensional magnetohydrodynamic (MHD flow in a porous space is analyzed. The flow is generated due to the motion of the plate in its plane with a periodic velocity. Under the flow assumptions, the governing nonlinear partial differential equation is transformed into steady-state and transient nonlinear equations. The reduced equation for the transient flow is solved analytically using symmetry approach while the nonlinear steady-state equation is solved using a modified version of He’s homotopy perturbation method. The effect of several operating parameters on the flow hydromagnetic is discussed. The results indicated that for the considered case, t = 1:5 is the moment after which the time-dependent transient motion of the fluid can be approximated with the steady-state motion, described by the steady-state solution. It is clear that, after this value of time t the time-dependent transient solution can be neglected.

  7. [Speech evoked auditory brainstem response and cognitive disorders].

    Science.gov (United States)

    Zhou, M; Wang, N Y

    2016-12-07

    Speech evoked auditory brainstem response(s-ABR)is evoked by compound syllable, and those stimulus are similar to the daily language which convey both semantic information and non-semantic information. Speech coding program can take place at brainstem. As a new method, s-ABR may reveal the mystery of speech coding program. Many tests have proved that s-ABR is somehow related to cognitive ability. We mainly illustrated the possibility of grading the cognitive ability using s-ABR, the abnormal test result from those cognitive disorders, and the family factors that contribute to cognitive disorder.

  8. [Evoked potentials in intracranial operations: current status and our experiences].

    Science.gov (United States)

    Nau, H E; Hess, W; Pohlen, G; Marggraf, G; Rimpel, J

    1987-03-01

    Intraoperative neuromonitoring, especially evoked potential monitoring, has gained interest in recent years for both the anesthesiologist evaluating cerebral function and the neurosurgeon wishing to avoid neuronal lesions during intracranial operations. Before evoked potential monitoring can be introduced as a routine method of intraoperative management, experience with this method particularly in intensive care units, is imperative. We recorded evoked potentials with the Compact Four (Nicolet) and Basis 8000 (Schwarzer Picker International) computer systems. Preoperative derivations should be done with the same apparatus used intraoperatively and parameters of peri- and intraoperative derivations should not be changed. The patient's head must be fixed in a Mayfield clamp in order to avoid artefacts during trepanation. The possible artefacts due to apparatus, patient, or anesthesia are summarized in the tables. The derivations of evoked potentials should be supervised by a person who is not involved in the anesthesia or the surgical procedure; this condition may change in the future with full automatization of the recording technique and alarms. Good communication between surgeon, anesthesiologist, and neurophysiological assistant is a prerequisite. The modality is chosen in accordance with the affected neuronal system: visual-evoked potential (VEP) monitoring in the management of processes affecting the visual pathway, brain stem auditory-(BAER) and somatosensory-evoked potential (SSEP) monitoring in lesions affecting these pathways, in particular space-occupying lesions of the posterior fossa. VEP monitoring may be useful, but we observed alterations of the responses without changes in the level of anesthesia or manipulation of the visual pathways. In space-occupying processes of the cerebellopontine angle, BAER could not be developed in nearly all cases because the large underlying tumor had caused the disappearance of waves II-V. In these cases SSEP monitoring

  9. Nonlinear dynamics and complexity

    CERN Document Server

    Luo, Albert; Fu, Xilin

    2014-01-01

    This important collection presents recent advances in nonlinear dynamics including analytical solutions, chaos in Hamiltonian systems, time-delay, uncertainty, and bio-network dynamics. Nonlinear Dynamics and Complexity equips readers to appreciate this increasingly main-stream approach to understanding complex phenomena in nonlinear systems as they are examined in a broad array of disciplines. The book facilitates a better understanding of the mechanisms and phenomena in nonlinear dynamics and develops the corresponding mathematical theory to apply nonlinear design to practical engineering.

  10. Gaia transient detection efficiency: hunting for nuclear transients

    CERN Document Server

    Blagorodnova, Nadejda; Harrison, Diana L; Koposov, Sergey; Mattila, Seppo; Campbell, Heather; Walton, Nicholas A; Wyrzykowski, Lukasz

    2015-01-01

    We present a study of the detectability of transient events associated with galaxies for the Gaia European Space Agency astrometric mission. We simulated the on-board detections, and on-ground processing for a mock galaxy catalogue to establish the properties required for the discovery of transient events by Gaia, specifically tidal disruption events (TDEs) and supernovae (SNe). Transients may either be discovered by the on-board detection of a new source or by the brightening of a previously known source. We show that Gaia transients can be identified as new detections on-board for offsets from the host galaxy nucleus of 0.1--0.5,arcsec, depending on magnitude and scanning angle. The Gaia detection system shows no significant loss of SNe at close radial distances to the nucleus. We used the detection efficiencies to predict the number of transients events discovered by Gaia. For a limiting magnitude of 19, we expect around 1300 SNe per year: 65% SN Ia, 28% SN II and 7% SN Ibc, and ~20 TDEs per year.

  11. Blade loss transient dynamics analysis, volume 2. Task 2: TETRA 2 user's manual

    Science.gov (United States)

    Black, Gerald; Gallardo, Vincente C.

    1986-01-01

    This is the user's manual for the TETRA 2 Computer Code, a program developed in the NASA-Lewis Blade Loss Program. TETRA 2 calculates a turbine engine's dynamic structural response from applied stimuli. The calculation options are: (1) transient response; and (2) steady state forced response. Based on the method of modal syntheses, the program allows the use of linear, as well as nonlinear connecting elements. Both transient and steady state options can include: flexible Bladed Disk Module, and Nonlinear Connecting Elements (including deadband, hardening/softening spring). The transient option has the additional capability to calculate response with a squeeze film bearing module. TETRA 2 output is summarized in a plotfile which permits post processing such as FFT or graphical animation with the proper software and computer equipment.

  12. Probing Transient Electron Dynamics Using Ultrafast X Rays

    Science.gov (United States)

    Bucksbaum, Philip

    2016-05-01

    Linear x-ray absorption in atoms or molecules creates highly excited multi-electron quantum systems, which relax rapidly by fluorescence or Auger emission. These relaxation rates are usually less than a few femtoseconds in duration, and so they can reveal transient elecronic states in molecules as they undergo photo-induced transformations. I will show recent results from femtosecond x-ray experiments that display this phenomenon. There are efforts underway to push the temporal resolving power of ultrafast x-ray pulses into the attosecond regime, using stronger fields to initiate nonlinear absorption processes such as transient stimulated electronic Raman scattering. I will discuss current progress and future prospects for research in this area. This research is supported through Stanford PULSE Institute, SLAC National Accelerator Lab by the U.S. Department of Energy, Office of Basic Energy Sciences, Atomic, Molecular, and Optical Science Program.

  13. Harnessing quantum transport by transient chaos.

    Science.gov (United States)

    Yang, Rui; Huang, Liang; Lai, Ying-Cheng; Grebogi, Celso; Pecora, Louis M

    2013-03-01

    Chaos has long been recognized to be generally advantageous from the perspective of control. In particular, the infinite number of unstable periodic orbits embedded in a chaotic set and the intrinsically sensitive dependence on initial conditions imply that a chaotic system can be controlled to a desirable state by using small perturbations. Investigation of chaos control, however, was largely limited to nonlinear dynamical systems in the classical realm. In this paper, we show that chaos may be used to modulate or harness quantum mechanical systems. To be concrete, we focus on quantum transport through nanostructures, a problem of considerable interest in nanoscience, where a key feature is conductance fluctuations. We articulate and demonstrate that chaos, more specifically transient chaos, can be effective in modulating the conductance-fluctuation patterns. Experimentally, this can be achieved by applying an external gate voltage in a device of suitable geometry to generate classically inaccessible potential barriers. Adjusting the gate voltage allows the characteristics of the dynamical invariant set responsible for transient chaos to be varied in a desirable manner which, in turn, can induce continuous changes in the statistical characteristics of the quantum conductance-fluctuation pattern. To understand the physical mechanism of our scheme, we develop a theory based on analyzing the spectrum of the generalized non-Hermitian Hamiltonian that includes the effect of leads, or electronic waveguides, as self-energy terms. As the escape rate of the underlying non-attracting chaotic set is increased, the imaginary part of the complex eigenenergy becomes increasingly large so that pointer states are more difficult to form, making smoother the conductance-fluctuation pattern.

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

    Science.gov (United States)

    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.

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

    Directory of Open Access Journals (Sweden)

    Jorge Arrubla

    Full Text Available 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.

  16. Fast, transient cardiac accelerations and decelerations during fear conditioning in rats.

    Science.gov (United States)

    Knippenberg, J M J; Barry, R J; Kuniecki, M J; van Luijtelaar, G

    2012-02-01

    The current study reports on a number of heart rate responses observed in rats subjected to a discriminatory Pavlovian fear conditioning procedure. Rats learned that a series of six auditory pips was followed by a footshock when presented alone, but not when the pip series was preceded by a visual safety signal. Each auditory pip in the series evoked a fast transient (transient decelerations are similar to the human Evoked Cardiac Response 1 (ECR1), a brief modest deceleration evoked by simple sensory stimuli that is thought to reflect an early process of stimulus registration. Immediately following these pip-evoked decelerations, modest fast accelerations were observed. These accelerations were larger when the pip series was followed by shock than when it was not followed by shock. We propose a potential linkage between these accelerations and the human acceleratory ECR2 component, which is associated with more elaborate processing following stimulus registration; something likely to take place when the pip series predicts an aversive event. Both the ECR1- and ECR2-like responses were embedded within a slow, gradual heart rate increase across the entire pip series. This tonic increase was significantly larger on trials with footshock and is therefore probably associated with anticipatory fear of the upcoming shock. An additional special type of cardiac response was found to the first pip in the series not preceded by the safety signal; here, a much larger and more sustained deceleration was apparent. This response appears relatable to the prolonged deceleration reported in humans in response to aversive picture content. We discuss the cardiac responses found in rats in the current study in the context of heart rate responses known in the human literature.

  17. Nonlinear Elliptic Differential Equations with Multivalued Nonlinearities

    Indian Academy of Sciences (India)

    Antonella Fiacca; Nikolaos Matzakos; Nikolaos S Papageorgiou; Raffaella Servadei

    2001-11-01

    In this paper we study nonlinear elliptic boundary value problems with monotone and nonmonotone multivalued nonlinearities. First we consider the case of monotone nonlinearities. In the first result we assume that the multivalued nonlinearity is defined on all $\\mathbb{R}$. Assuming the existence of an upper and of a lower solution, we prove the existence of a solution between them. Also for a special version of the problem, we prove the existence of extremal solutions in the order interval formed by the upper and lower solutions. Then we drop the requirement that the monotone nonlinearity is defined on all of $\\mathbb{R}$. This case is important because it covers variational inequalities. Using the theory of operators of monotone type we show that the problem has a solution. Finally in the last part we consider an eigenvalue problem with a nonmonotone multivalued nonlinearity. Using the critical point theory for nonsmooth locally Lipschitz functionals we prove the existence of at least two nontrivial solutions (multiplicity theorem).

  18. Detection of phase randomly distributed weak transient signal using chaos

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    In practical communication and radar system s, the phase of the received signal is random, the arrival time is unknown, the lasting time is limited and the SNR is often very low. In order to realize the detection of the signal, the method of using a group of nonlinear differential equations is presented. The theory of this chaos-based detection is analyzed. Computer simulation indicates that the shortest lasting time of the transient signal that can be detected out is 12 periods, the detection error of arrival time is less than 7/8 signal's period, the detection characteristics are got using Monte-Carlo simulation.

  19. Large-signal transient response of a switching regulator

    Science.gov (United States)

    Harada, K.; Nabeshima, T.

    Analytical and experimental considerations on the large-signal transient-responses of the buck-type switching regulator are described. The behaviour under the large-signal operation is different from the case of small signal because of the saturation characteristics of the PWM feedback controller. The effect of this nonlinearity is analyzed by dividing its operation into three modes. As a result, the maximum peak values of the inrush current and output voltage are obtained analytically both for the start-up and for the step change of the load current.

  20. Influence of Hepes- and CO2/HCO(3-)-buffer on Ca2+ transients induced by TRH and elevated K+ in rat pituitary GH4C1 cells.

    Science.gov (United States)

    Törnquist, K; Päällysaho, J; Heinonen, E; Kaila, K

    1995-07-01

    The influence of two buffer systems (Hepes and CO2/HCO3-) on intracellular Ca2+ ([Ca2+]i) transients evoked by TRH and by elevated K+ were studied in single, and small clusters of, clonal rat pituitary GH4C1 cells using Fura 2. The steady-state level of [Ca2+]i was virtually identical in Hepes and CO2/HCO3-. In both buffers, addition of TRH induced a transient increase in [Ca2+]i which attained a significantly higher peak in Hepes (357 +/- 43 nM) when compared with values measured in the presence of CO2/HCO3- (184 +/- 21 nM). In Hepes, the basal IP3-level was higher than in CO2/HCO3-. The TRH-evoked increase in IP3 was higher in magnitude in Hepes than in CO2/HCO3-, although the stimulated/basal ratio was not different between the two buffers. The buffer composition had no effect on the specific binding of 3H-TRH to the cells. Furthermore, the amplitude of the increase in [Ca2+]i evoked by 50 mM K+ was identical in both buffers. TRH and K+ had no effect on pHi in either buffer. The present results indicate that HCO3- has an influence on TRH-induced Ca2+ transient, at least in part by modifying the TRH-evoked production of IP3.

  1. Recent development of transient electronics

    Directory of Open Access Journals (Sweden)

    Huanyu Cheng

    2016-01-01

    Full Text Available Transient electronics are an emerging class of electronics with the unique characteristic to completely dissolve within a programmed period of time. Since no harmful byproducts are released, these electronics can be used in the human body as a diagnostic tool, for instance, or they can be used as environmentally friendly alternatives to existing electronics which disintegrate when exposed to water. Thus, the most crucial aspect of transient electronics is their ability to disintegrate in a practical manner and a review of the literature on this topic is essential for understanding the current capabilities of transient electronics and areas of future research. In the past, only partial dissolution of transient electronics was possible, however, total dissolution has been achieved with a recent discovery that silicon nanomembrane undergoes hydrolysis. The use of single- and multi-layered structures has also been explored as a way to extend the lifetime of the electronics. Analytical models have been developed to study the dissolution of various functional materials as well as the devices constructed from this set of functional materials and these models prove to be useful in the design of the transient electronics.

  2. Value of transcranial motor evoked potentials during spinal operations

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    @@ To the Editor: We read the interesting recent article by Ding et al1 concerning the value of somatosensory evoked potentials (SEPs) in the diagnosis and prognosis of cervical spondylotic myelopathy, as well as the usefulness of monitoring intraoperative potentials in terms of safety and predictive factors.

  3. Evaluation of Evoked Potentials to Dyadic Tones after Cochlear Implantation

    Science.gov (United States)

    Sandmann, Pascale; Eichele, Tom; Buechler, Michael; Debener, Stefan; Jancke, Lutz; Dillier, Norbert; Hugdahl, Kenneth; Meyer, Martin

    2009-01-01

    Auditory evoked potentials are tools widely used to assess auditory cortex functions in clinical context. However, in cochlear implant users, electrophysiological measures are challenging due to implant-created artefacts in the EEG. Here, we used independent component analysis to reduce cochlear implant-related artefacts in event-related EEGs of…

  4. Recording and assessment of evoked potentials with electrode arrays.

    Science.gov (United States)

    Miljković, N; Malešević, N; Kojić, V; Bijelić, G; Keller, T; Popović, D B

    2015-09-01

    In order to optimize procedure for the assessment of evoked potentials and to provide visualization of the flow of action potentials along the motor systems, we introduced array electrodes for stimulation and recording and developed software for the analysis of the recordings. The system uses a stimulator connected to an electrode array for the generation of evoked potentials, an electrode array connected to the amplifier, A/D converter and computer for the recording of evoked potentials, and a dedicated software application. The method has been tested for the assessment of the H-reflex on the triceps surae muscle in six healthy humans. The electrode array with 16 pads was positioned over the posterior aspect of the thigh, while the recording electrode array with 16 pads was positioned over the triceps surae muscle. The stimulator activated all the pads of the stimulation electrode array asynchronously, while the signals were recorded continuously at all the recording sites. The results are topography maps (spatial distribution of evoked potentials) and matrices (spatial visualization of nerve excitability). The software allows the automatic selection of the lowest stimulation intensity to achieve maximal H-reflex amplitude and selection of the recording/stimulation pads according to predefined criteria. The analysis of results shows that the method provides rich information compared with the conventional recording of the H-reflex with regard the spatial distribution.

  5. Cortical Auditory Evoked Potentials in Unsuccessful Cochlear Implant Users

    Science.gov (United States)

    Munivrana, Boska; Mildner, Vesna

    2013-01-01

    In some cochlear implant users, success is not achieved in spite of optimal clinical factors (including age at implantation, duration of rehabilitation and post-implant hearing level), which may be attributed to disorders at higher levels of the auditory pathway. We used cortical auditory evoked potentials to investigate the ability to perceive…

  6. SOMATOSENSORY EVOKED-POTENTIALS IN CEREBRAL ANEURYSM SURGERY

    NARCIS (Netherlands)

    BUCHTHAL, A; BELOPAVLOVIC, M

    1992-01-01

    Monitoring of median nerve somatosensory evoked potentials (SSEP) during surgery for a basilar artery aneurysm under moderate hypothermia revealed an unexpected loss of the first cortical peak. This was due to compression of the middle cerebral artery under the retractor during the surgical approach

  7. Cortical Variability in the Sensory-Evoked Response in Autism

    Science.gov (United States)

    Haigh, Sarah M.; Heeger, David J.; Dinstein, Ilan; Minshew, Nancy; Behrmann, Marlene

    2015-01-01

    Previous findings have shown that individuals with autism spectrum disorder (ASD) evince greater intra-individual variability (IIV) in their sensory-evoked fMRI responses compared to typical control participants. We explore the robustness of this finding with a new sample of high-functioning adults with autism. Participants were presented with…

  8. Asymmetric vestibular evoked myogenic potentials in unilateral Meniere patients

    NARCIS (Netherlands)

    Kingma, C. M.; Wit, H. P.

    2011-01-01

    Vestibular evoked myogenic potentials (VEMPs) were measured in 22 unilateral MeniSre patients with monaural and binaural stimulation with 250 and 500 Hz tone bursts. For all measurement situations significantly lower VEMP amplitudes were on average measured at the affected side compared to the unaff

  9. Analysis and Treatment of Problem Behavior Evoked by Music

    Science.gov (United States)

    Buckley, Scott D.; Newchok, Debra K.

    2006-01-01

    The present study investigated the effects of differential negative reinforcement of other behavior (DNRO) on problem behavior evoked by music in a 7-year-old child with pervasive developmental disorder. Following an auditory stimulus assessment, DNRO was used to reduce problem behavior to near-zero levels. Results are discussed in terms of…

  10. Cortical Auditory Evoked Potentials in Unsuccessful Cochlear Implant Users

    Science.gov (United States)

    Munivrana, Boska; Mildner, Vesna

    2013-01-01

    In some cochlear implant users, success is not achieved in spite of optimal clinical factors (including age at implantation, duration of rehabilitation and post-implant hearing level), which may be attributed to disorders at higher levels of the auditory pathway. We used cortical auditory evoked potentials to investigate the ability to perceive…

  11. Thermal grill conditioning: Effect on contact heat evoked potentials

    Science.gov (United States)

    Jutzeler, Catherine R.; Warner, Freda M.; Wanek, Johann; Curt, Armin; Kramer, John L. K.

    2017-01-01

    The ‘thermal grill illusion’ (TGI) is a unique cutaneous sensation of unpleasantness, induced through the application of interlacing warm and cool stimuli. While previous studies have investigated optimal parameters and subject characteristics to evoke the illusion, our aim was to examine the modulating effect as a conditioning stimulus. A total of 28 healthy control individuals underwent three testing sessions on separate days. Briefly, 15 contact heat stimuli were delivered to the right hand dorsum, while the left palmar side of the hand was being conditioned with either neutral (32 °C), cool (20 °C), warm (40 °C), or TGI (20/40 °C). Rating of perception (numeric rating scale: 0–10) and evoked potentials (i.e., N1 and N2P2 potentials) to noxious contact heat stimuli were assessed. While cool and warm conditioning decreased cortical responses to noxious heat, TGI conditioning increased evoked potential amplitude (N1 and N2P2). In line with other modalities of unpleasant conditioning (e.g., sound, visual, and olfactory stimulation), cortical and possibly sub-cortical modulation may underlie the facilitation of contact heat evoked potentials. PMID:28079118

  12. The computation of evoked heart rate and blood pressure

    NARCIS (Netherlands)

    Koers, G.; Mulder, L.J.M.; van der Veen, F.M.

    1999-01-01

    For many years psychophysiologists have been interested in stimulus related changes in heart rate and blood pressure. To represent these evoked heart rate and blood pressure patterns, heart rate and blood pressure data have to be transformed into equidistant time series. This paper presents an

  13. Multichannel recording of tibial-nerve somatosensory evoked potentials

    NARCIS (Netherlands)

    de Wassenberg, W. J. G. van; Kruizinga, W. J.; van der Hoeven, J. H.; Leenders, K. L.; Maurits, N. M.

    2008-01-01

    Study aims. -The topography of the peaks of tibial.-nerve somatosensory evoked potential (SEP) varies among healthy subjects, most likely because of differences in position and orientation of their cortical generator(s). Therefore, amplitude estimation with a standard one- or two-channel derivation

  14. Discriminating thermal effect in nonlinear-ellipse-rotation-modified Z-scan measurements.

    Science.gov (United States)

    Liu, Zhi-Bo; Shi, Shuo; Yan, Xiao-Qing; Zhou, Wen-Yuan; Tian, Jian-Guo

    2011-06-01

    We report that a modified Z-scan method by nonlinear ellipse rotation (NER) can be used to discriminate true nonlinear refraction from thermal effect in the transient regime and steady state. The combination of Z-scan and NER allows us to measure the third-order nonlinear susceptibility component without the influence of thermal-optical nonlinearity. The experimental results of pure CS(2) and CS(2) solutions of nigrosine verify that the transient thermal effect can be successfully eliminated from the NER-modified Z-scan measurements. This method is also extended to the case in which thermal-optical nonlinearities depend on a high repetition rate of femtosecond laser pulses for the N,N-dimethylmethanamide solutions of graphene oxide. © 2011 Optical Society of America

  15. A Precision and High-Speed Behavioral Simulation Method for Transient Response and Frequency Characteristics of Switching Converters

    Science.gov (United States)

    Sai, Toru; Sugimoto, Shoko; Sugimoto, Yasuhiro

    We propose a fast and precise transient response and frequency characteristics simulation method for switching converters. This method uses a behavioral simulation tool without using a SPICE-like analog simulator. The nonlinear operation of the circuit is considered, and the nonlinear function is realized by defining the nonlinear formula based on the circuit operation and by applying feedback. To assess the accuracy and simulation time of the proposed simulation method, we designed current-mode buck and boost converters and fabricated them using a 0.18-µm high-voltage CMOS process. The comparison in the transient response and frequency characteristics among SPICE, the proposed program on a behavioral simulation tool which we named NSTVR (New Simulation Tool for Voltage Regulators) and experiments of fabricated IC chips showed good agreement, while NSTVR was more than 22 times faster in transient response and 85 times faster in frequency characteristics than SPICE in CPU time in a boost converter simulation.

  16. Internal Decoupling in Nonlinear Process Control

    Directory of Open Access Journals (Sweden)

    Jens G. Balchen

    1988-07-01

    Full Text Available A simple method has been investigated for the total or partial removal of the effect of non-linear process phenomena in multi-variable feedback control systems. The method is based upon computing the control variables which will drive the process at desired rates. It is shown that the effect of model errors in the linearization of the process can be partly removed through the use of large feedback gains. In practice there will be limits on how large gains can he used. The sensitivity to parameter errors is less pronounced and the transient behaviour is superior to that of ordinary PI controllers.

  17. Visual evoked potentials in patients after methanol poisoning

    Directory of Open Access Journals (Sweden)

    Pavel Urban

    2016-06-01

    Full Text Available Objectives: We report the results of the visual evoked potentials (VEP examination in patients after severe poisoning by methanol. Material and Methods: 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. Results: 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. Conclusions: 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.

  18. Electromagnetic Transients in Power Cables

    DEFF Research Database (Denmark)

    Silva, Filipe Faria Da; Bak, Claus Leth

    of electromagnetic phenomena associated to their operation, among them electromagnetic transients, increased as well. Transient phenomena have been studied since the beginning of power systems, at first using only analytical approaches, which limited studies to more basic phenomena; but as computational tools became...... concerning HVAC cables. An important topic that is not covered in this book is measurements protocols/ methods. The protocols used when performing measurements on a cable depend on what is to be measured, the available equipment and accessibility. Readers interested in the topic are referred to search....... The chapter ends by proposing a systematic method that can be used when doing the insulation co-ordination study for a line, as well as the modelling requirements, both modelling depth and modelling detail of the equipment, for the study of the different types of transients followed by a step-by-step generic...

  19. Transient Faults in Computer Systems

    Science.gov (United States)

    Masson, Gerald M.

    1993-01-01

    A powerful technique particularly appropriate for the detection of errors caused by transient faults in computer systems was developed. The technique can be implemented in either software or hardware; the research conducted thus far primarily considered software implementations. The error detection technique developed has the distinct advantage of having provably complete coverage of all errors caused by transient faults that affect the output produced by the execution of a program. In other words, the technique does not have to be tuned to a particular error model to enhance error coverage. Also, the correctness of the technique can be formally verified. The technique uses time and software redundancy. The foundation for an effective, low-overhead, software-based certification trail approach to real-time error detection resulting from transient fault phenomena was developed.

  20. Cohabitation Duration and Transient Domesticity.

    Science.gov (United States)

    Golub, Andrew; Reid, Megan; Strickler, Jennifer; Dunlap, Eloise

    2013-01-01

    Research finds that many impoverished urban Black adults engage in a pattern of partnering and family formation involving a succession of short cohabitations yielding children, a paradigm referred to as transient domesticity. Researchers have identified socioeconomic status, cultural adaptations, and urbanicity as explanations for aspects of this pattern. We used longitudinal data from the 2001 Survey of Income and Program Participation to analyze variation in cohabitation and marriage duration by race/ethnicity, income, and urban residence. Proportional hazards regression indicated that separation risk is greater among couples that are cohabiting, below 200% of the federal poverty line, and Black but is not greater among urban dwellers. This provides empirical demographic evidence to support the emerging theory of transient domesticity and suggests that both socioeconomic status and race explain this pattern. We discuss the implications of these findings for understanding transient domesticity and make recommendations for using the Survey of Income and Program Participation to further study this family formation paradigm.

  1. Vestibular-dependent inter-stimulus interval effects on sound evoked potentials of central origin.

    Science.gov (United States)

    Todd, N P M; Govender, S; Colebatch, J G

    2016-11-01

    Todd et al. (2014ab) have recently demonstrated the presence of vestibular-dependent contributions to auditory evoked potentials (AEPs) when passing through the vestibular threshold as determined by vestibular evoked myogenic potentials (VEMPs), including a particular deflection labeled as an N42/P52 prior to the long-latency AEPs N1 and P2. In this paper we report the results of an experiment to determine the effect of inter-stimulus interval (ISI) and regularity on potentials recorded above and below VEMP threshold. Five healthy, right-handed subjects were recruited and evoked potentials were recorded to binaurally presented sound stimulation, above and below vestibular threshold, at seven stimulus rates with ISIs of 212, 300, 424, 600, 848, 1200 and 1696 ms. The inner five intervals, i.e. 300, 424, 600, 848, 1200 ms, were presented twice in both regular and irregular conditions. ANOVA on the global field power (GFP) were conducted for each of four waves, N42, P52, N1 and P2 with factors of intensity, ISI and regularity. Both N42 and P52 waves showed significant ANOVA effects of intensity but no other main effects or interactions. In contrast both N1 and P2 showed additional effects of ISI, as well as intensity, and evidence of non-linear interactions between ISI and intensity. A source analysis was carried out consistent with prior work suggesting that when above vestibular threshold, in addition to bilateral superior temporal cortex, ocular, cerebellar and cingulate sources are recruited. Further statistical analysis of the source currents indicated that the origin of the interactions with intensity may be the ISI sensitivity of the vestibular-dependent sources. This in turn may reflect a specific vestibular preference for stimulus rates associated with locomotion, i.e. rates close to 2 Hz, or ISIs close to 500 ms, where saccular afferents show increased gain and the corresponding reflexes are most sensitive.

  2. Nonlinear Dirac Equations

    Directory of Open Access Journals (Sweden)

    Wei Khim Ng

    2009-02-01

    Full Text Available We construct nonlinear extensions of Dirac's relativistic electron equation that preserve its other desirable properties such as locality, separability, conservation of probability and Poincaré invariance. We determine the constraints that the nonlinear term must obey and classify the resultant non-polynomial nonlinearities in a double expansion in the degree of nonlinearity and number of derivatives. We give explicit examples of such nonlinear equations, studying their discrete symmetries and other properties. Motivated by some previously suggested applications we then consider nonlinear terms that simultaneously violate Lorentz covariance and again study various explicit examples. We contrast our equations and construction procedure with others in the literature and also show that our equations are not gauge equivalent to the linear Dirac equation. Finally we outline various physical applications for these equations.

  3. Transient osteoporosis of the hip.

    Science.gov (United States)

    Mirza, Rabeea; Ishaq, Saliha; Amjad, Hira

    2012-02-01

    Transient Osteoporosis of Hip (TOH) is an uncommon disorder of idiopathic nature, particularly in the Asian population. It has been described to mostly occur in middle aged men and women in their third trimester of pregnancy. A distinctive hallmark of this condition is that it is self limiting and resolves in a few months. The patient presents to the physician with pain on movement and impaired mobility of the affected joint, developing without any history of trauma. MRI is the main diagnostic tool. We report herein a case of a forty five year old male, who developed transient osteoporosis of the hip, and was managed conservatively.

  4. Facilitating neuronal connectivity analysis of evoked responses by exposing local activity with principal component analysis preprocessing: simulation of evoked MEG.

    Science.gov (United States)

    Gao, Lin; Zhang, Tongsheng; Wang, Jue; Stephen, Julia

    2013-04-01

    When connectivity analysis is carried out for event related EEG and MEG, the presence of strong spatial correlations from spontaneous activity in background may mask the local neuronal evoked activity and lead to spurious connections. In this paper, we hypothesized PCA decomposition could be used to diminish the background activity and further improve the performance of connectivity analysis in event related experiments. The idea was tested using simulation, where we found that for the 306-channel Elekta Neuromag system, the first 4 PCs represent the dominant background activity, and the source connectivity pattern after preprocessing is consistent with the true connectivity pattern designed in the simulation. Improving signal to noise of the evoked responses by discarding the first few PCs demonstrates increased coherences at major physiological frequency bands when removing the first few PCs. Furthermore, the evoked information was maintained after PCA preprocessing. In conclusion, it is demonstrated that the first few PCs represent background activity, and PCA decomposition can be employed to remove it to expose the evoked activity for the channels under investigation. Therefore, PCA can be applied as a preprocessing approach to improve neuronal connectivity analysis for event related data.

  5. Nonlinear Cross Gramians

    Science.gov (United States)

    Ionescu, Tudor C.; Scherpen, Jacquelien M. A.

    We study the notion of cross Gramians for nonlinear gradient systems, using the characterization in terms of prolongation and gradient extension associated to the system. The cross Gramian is given for the variational system associated to the original nonlinear gradient system. We obtain linearization results that correspond to the notion of a cross Gramian for symmetric linear systems. Furthermore, first steps towards relations with the singular value functions of the nonlinear Hankel operator are studied and yield promising results.

  6. Nonlinear functional analysis

    Directory of Open Access Journals (Sweden)

    W. L. Fouché

    1983-03-01

    Full Text Available In this article we discuss some aspects of nonlinear functional analysis. It included reviews of Banach’s contraction theorem, Schauder’s fixed point theorem, globalising techniques and applications of homotopy theory to nonlinear functional analysis. The author emphasises that fundamentally new ideas are required in order to achieve a better understanding of phenomena which contain both nonlinear and definite infinite dimensional features.

  7. Nonlinear Electrodynamics and QED

    OpenAIRE

    2003-01-01

    The limits of linear electrodynamics are reviewed, and possible directions of nonlinear extension are explored. The central theme is that the qualitative character of the empirical successes of quantum electrodynamics must be used as a guide for understanding the nature of the nonlinearity of electrodynamics at the subatomic level. Some established theories of nonlinear electrodynamics, namely, those of Mie, Born, and Infeld are presented in the language of the modern geometrical and topologi...

  8. Nonlinearities and synchronization in musical acoustics and music psychology

    CERN Document Server

    Bader, Rolf

    2013-01-01

    Nonlinearities are a crucial and founding principle in nearly all musical systems, may they be musical instruments, timbre or rhythm perception and production, or neural networks of music perception. This volume gives an overview about present and past research in these fields. In Musical Acoustics, on the one hand the nonlinearities in musical instruments often produce the musically interesting features. On the other, musical instruments are nonlinear by nature, and tone production is the result of synchronization and self-organization within the instruments. Furthermore, as nearly all musical instruments are driven by impulses an Impulse Pattern Formulation (IPF) is suggested, an iterative framework holding for all musical instruments. It appears that this framework is able to reproduce the complex and perceptionally most salient initial transients of musical instruments. In Music Psychology, nonlinearities are present in all areas of musical features, like pitch, timbre, or rhythm perception. In terms of r...

  9. Nonlinear Physics of Plasmas

    CERN Document Server

    Kono, Mitsuo

    2010-01-01

    A nonlinearity is one of the most important notions in modern physics. A plasma is rich in nonlinearities and provides a variety of behaviors inherent to instabilities, coherent wave structures and turbulence. The book covers the basic concepts and mathematical methods, necessary to comprehend nonlinear problems widely encountered in contemporary plasmas, but also in other fields of physics and current research on self-organized structures and magnetized plasma turbulence. The analyses make use of strongly nonlinear models solved by analytical techniques backed by extensive simulations and available experiments. The text is written for senior undergraduates, graduate students, lecturers and researchers in laboratory, space and fusion plasmas.

  10. Nonlinear magnetic metamaterials.

    Science.gov (United States)

    Shadrivov, Ilya V; Kozyrev, Alexander B; van der Weide, Daniel W; Kivshar, Yuri S

    2008-12-08

    We study experimentally nonlinear tunable magnetic metamaterials operating at microwave frequencies. We fabricate the nonlinear metamaterial composed of double split-ring resonators where a varactor diode is introduced into each resonator so that the magnetic resonance can be tuned dynamically by varying the input power. We demonstrate that at higher powers the transmission of the metamaterial becomes power-dependent and, as a result, such metamaterial can demonstrate various nonlinear properties. In particular, we study experimentally the power-dependent shift of the transmission band and demonstrate nonlinearity-induced enhancement (or suppression) of wave transmission. (c) 2008 Optical Society of America

  11. Organic nonlinear optical materials

    Science.gov (United States)

    Umegaki, S.

    1987-01-01

    Recently, it became clear that organic compounds with delocalized pi electrons show a great nonlinear optical response. Especially, secondary nonlinear optical constants of more than 2 digits were often seen in the molecular level compared to the existing inorganic crystals such as LiNbO3. The crystallization was continuously tried. Organic nonlinear optical crystals have a new future as materials for use in the applied physics such as photomodulation, optical frequency transformation, opto-bistabilization, and phase conjugation optics. Organic nonlinear optical materials, e.g., urea, O2NC6H4NH2, I, II, are reviewed with 50 references.

  12. Nonlinearity-reduced interferometer

    Science.gov (United States)

    Wu, Chien-ming

    2007-12-01

    Periodic nonlinearity is a systematic error limiting the accuracy of displacement measurements at the nanometer level. It results from many causes such as the frequency mixing, polarization mixing, polarization-frequency mixing, and the ghost reflections. An interferometer having accuracy in displacement measurement of less than one-nanometer is necessary in nanometrology. To meet the requirement, the periodic nonlinearity should be less than deep sub-nanometer. In this paper, a nonlinearity-reduced interferometry has been proposed. Both the linear- and straightness-interferometer were tested. The developed interferometer demonstrated of a residual nonlinearity less than 25 pm.

  13. 2D-local existence and uniqueness of a transient state of a coupled radiative-conductive heat transfer problem

    OpenAIRE

    Ghattassi, Mohamed; Roche, Jean Rodolphe; Schmitt, Didier; Boutayeb, Mohamed

    2016-01-01

    This paper deals with local existence and uniqueness results for a transient two-dimensional combined nonlinear radiative-conductive system. This system describes the heat transfer for a grey, semi-transparent and non-scattering medium with homogeneous Dirichlet boundary conditions. We reformulate the full transient state system as a fixed-point problem. The existence and uniqueness proof rests upon the Banach fixed-point Theorem assuming the initial data T 0 is non-negative and sufficiently ...

  14. Regulation by L channels of Ca(2+)-evoked secretory responses in ouabain-treated chromaffin cells.

    Science.gov (United States)

    De Pascual, Ricardo; Colmena, Inés; Ruiz-Pascual, Lucía; Baraibar, Andrés Mateo; Egea, Javier; Gandía, Luis; García, Antonio G

    2016-10-01

    It is known that the sustained depolarisation of adrenal medullary bovine chromaffin cells (BCCs) with high K(+) concentrations produces an initial sharp catecholamine release that subsequently fades off in spite depolarisation persists. Here, we have recreated a sustained depolarisation condition of BCCs by treating them with the Na(+)/K(+) ATPase blocker ouabain; in doing so, we searched experimental conditions that permitted the development of a sustained long-term catecholamine release response that could be relevant during prolonged stress. BCCs were perifused with nominal 0Ca(2+) solution, and secretion responses were elicited by intermittent application of short 2Ca(2+) pulses (Krebs-HEPES containing 2 mM Ca(2+)). These pulses elicited a biphasic secretory pattern with an initial 30-min period with secretory responses of increasing amplitude and a second 30-min period with steady-state, non-inactivating responses. The initial phase was not due to gradual depolarisation neither to gradual increases of the cytosolic calcium transients ([Ca(2+)]c) elicited by 2Ca(2+) pulses in BBCs exposed to ouabain; both parameters increased soon after ouabain addition. Νifedipine blocked these responses, and FPL64176 potentiated them, suggesting that they were triggered by Ca(2+) entry through non-inactivating L-type calcium channels. This was corroborated by nifedipine-evoked blockade of the L-type Ca(2+) channel current and the [Ca(2+)]c transients elicited by 2Ca(2+) pulses. Furthermore, the plasmalemmal Na(+)/Ca(2+) exchanger (NCX) blocker SEA0400 caused a mild inhibition followed by a large rebound increase of the steady-state secretory responses. We conclude that these two phases of secretion are mostly contributed by Ca(2+) entry through L calcium channels, with a minor contribution of Ca(2+) entry through the reverse mode of the NCX.

  15. A transient, quadratic nodal method for triangular-Z geometry

    Energy Technology Data Exchange (ETDEWEB)

    DeLorey, T.F.

    1993-06-01

    Many systematically-derived nodal methods have been developed for Cartesian geometry due to the extensive interest in Light Water Reactors. These methods typically model the transverse-integrated flux as either an analytic or low order polynomial function of position within the node. Recently, quadratic nodal methods have been developed for R-Z and hexagonal geometry. A static and transient quadratic nodal method is developed for triangular-Z geometry. This development is particularly challenging because the quadratic expansion in each node must be performed between the node faces and the triangular points. As a consequence, in the 2-D plane, the flux and current at the points of the triangles must be treated. Quadratic nodal equations are solved using a non-linear iteration scheme, which utilizes the corrected, mesh-centered finite difference equations, and forces these equations to match the quadratic equations by computing discontinuity factors during the solution. Transient nodal equations are solved using the improved quasi-static method, which has been shown to be a very efficient solution method for transient problems. Several static problems are used to compare the quadratic nodal method to the Coarse Mesh Finite Difference (CMFD) method. The quadratic method is shown to give more accurate node-averaged fluxes. However, it appears that the method has difficulty predicting node leakages near reactor boundaries and severe material interfaces. The consequence is that the eigenvalue may be poorly predicted for certain reactor configurations. The transient methods are tested using a simple analytic test problem, a heterogeneous heavy water reactor benchmark problem, and three thermal hydraulic test problems. Results indicate that the transient methods have been implemented correctly.

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

    NARCIS (Netherlands)

    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 e

  17. Stationary and Transient Response Statistics

    DEFF Research Database (Denmark)

    Madsen, Peter Hauge; Krenk, Steen

    1982-01-01

    The covariance functions for the transient response of a linear MDOF-system due to stationary time limited excitation with an arbitrary frequency content are related directly to the covariance functions of the stationary response. For rational spectral density functions closed form expressions...

  18. Dynamic and Transient Infinite Elements

    CERN Document Server

    Zhao, Chongbin

    2009-01-01

    Intends to provide the theory and the application of dynamic and transient infinite elements for simulating the far fields of infinite domains involved in many of scientific and engineering problems, based on the author's own work over the years. This title is suitable for computational geoscientists, geotechnical engineers, and civil engineers.

  19. Audiovisual integration of stimulus transients

    DEFF Research Database (Denmark)

    Andersen, Tobias; Mamassian, Pascal

    2008-01-01

    leaving only unsigned stimulus transients as the basis for audiovisual integration. Facilitation of luminance detection occurred even with varying audiovisual stimulus onset asynchrony and even when the sound lagged behind the luminance change by 75 ms supporting the interpretation that perceptual...

  20. Simulation Model of a Transient

    DEFF Research Database (Denmark)

    Jauch, Clemens; Sørensen, Poul; Bak-Jensen, Birgitte

    2005-01-01

    This paper describes the simulation model of a controller that enables an active-stall wind turbine to ride through transient faults. The simulated wind turbine is connected to a simple model of a power system. Certain fault scenarios are specified and the turbine shall be able to sustain operation...

  1. Atmospheric pressure plasma jet treatment evokes transient oxidative stress in HaCaT keratinocytes and influences cell physiology.

    Science.gov (United States)

    Wende, Kristian; Straßenburg, Susanne; Haertel, Beate; Harms, Manuela; Holtz, Sarah; Barton, Annemarie; Masur, Kai; von Woedtke, Thomas; Lindequist, Ulrike

    2014-04-01

    Modern non-thermal atmospheric pressure plasma sources enable controllable interaction with biological systems. Their future applications - e.g. wound management - are based on their unique mixture of reactive components sparking both stimulatory as well as inhibitory processes. To gain detailed understanding of plasma-cell interaction and with respect to risk awareness, key mechanisms need to be identified. This study focuses on the impact of an argon non-thermal atmospheric pressure plasma jet (kINPen 09) on human HaCaT keratinocytes. With increasing duration, cell viability decreased. In accordance, cells accumulated in G2/M phase within the following 24 h. DNA single-strand breaks were detected immediately after treatment and receded in the aftermath, returning to control levels after 24 h. No directly plasma-related DNA double-strand breaks were detected over the same time. Concurrently, DNA synthesis decreased. Coincident with treatment time, an increase in intracellular 2',7'-dichlorodihydrofluorescein diacetate (H(2)DCFDA) conversion increased reactive oxygen species (ROS) levels. The radical scavenging activity of culture medium crucially influenced these effects. Thus, ROS changed DNA integrity, and the effectiveness of cellular defence mechanisms characterises the interaction of non-thermal plasma and eukaryotic cells. Effects were time-dependent, indicating an active response of the eukaryotic cells. Hence, a stimulation of eukaryotic cells using short-term non-thermal plasma treatment seems possible, eg in the context of chronic wound care. Long-term plasma treatments stopped in cell proliferation and apoptosis, which might be relevant in controlling neoplastic conditions.

  2. Do film soundtracks contain nonlinear analogues to influence emotion?

    Science.gov (United States)

    Blumstein, Daniel T; Davitian, Richard; Kaye, Peter D

    2010-12-23

    A variety of vertebrates produce nonlinear vocalizations when they are under duress. By their very nature, vocalizations containing nonlinearities may sound harsh and are somewhat unpredictable; observations that are consistent with them being particularly evocative to those hearing them. We tested the hypothesis that humans capitalize on this seemingly widespread vertebrate response by creating nonlinear analogues in film soundtracks to evoke particular emotions. We used lists of highly regarded films to generate a set of highly ranked action/adventure, dramatic, horror and war films. We then scored the presence of a variety of nonlinear analogues in these film soundtracks. Dramatic films suppressed noise of all types, contained more abrupt frequency transitions and musical sidebands, and fewer noisy screams than expected. Horror films suppressed abrupt frequency transitions and musical sidebands, but had more non-musical sidebands, and noisy screams than expected. Adventure films had more male screams than expected. Together, our results suggest that film-makers manipulate sounds to create nonlinear analogues in order to manipulate our emotional responses.

  3. Effects of continuous conditioning noise and light on the auditory- and visual-evoked potentials of the guinea pig.

    Science.gov (United States)

    Goksoy, Cuneyt; Demirtas, Serdar; Ates, Kahraman

    2005-11-01

    Neurophysiological studies aiming to explore how the brain integrates information from different brain regions are increasing in the literature. The aim of the present study is to explore intramodal (binaural, binocular) and intermodal (audio-visual) interactions in the guinea pig brain through the observation of changes in evoked potentials by generalized continuous background activity. Seven chronically prepared animals were used in the study and the recordings were made as they were awake. Epidural electrodes were implanted to the skulls by using stereotaxic methods. Continuous light for retinal or continuous white noise for cochlear receptors were used as continuous conditioning stimuli for generalized stimulation. To evoke auditory or visual potentials, click or flash were used as transient imperative stimuli. The study data suggest that (a) white noise applied to one ear modifies the response to click in the contralateral ear which is a binaural interaction; (b) continuous light applied to one eye modifies the response to flash applied to the contralateral eye which is interpreted as a binocular interaction; (c) regardless of the application side, white noise similarly modified the response to flash applied to the either eye connoting a nonspecific effect of white noise on vision, independent from spatial hearing mechanisms; (d) on the other hand, continuous light, in either eye, did not affect the response to click applied to any ear, reminding a 'one-way' interaction that continuous aural stimulation affects visual response.

  4. THE PRESSURE TRANSIENT ANALYSIS OF DEFORMATION OF FRACTAL MEDIUM

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yi-gen; TONG Deng-ke

    2008-01-01

    The assumption of constant rock properties in pressure-transient analysis of stress-sensitive reservoirs can cause significant errors in the estimation of temporal and spatial variation of pressure. In this article, the pressure transient response of the fractal medium in stress-sensitive reservoirs was studied by using the self-similarity solution method and the regular perturbation method. The dependence of permeability on pore pressure makes the flow equation strongly nonlinear. The nonlinearities associated with the governing equation become weaker by using the logarithm transformation. The perturbation solutions for a constant pressure production and a constant rate production of a linear-source well were obtained by using the self-similarity solution method and the regular perturbation method in an infinitely large system, and inquire into the changing rule of pressure when the fractal and deformation parameters change. The plots of typical pressure curves were given in a few cases, and the results can be applied to well test analysis.

  5. Instantaneous Frequency and Damping from Transient Ring-Down Data

    Energy Technology Data Exchange (ETDEWEB)

    Kuether, Robert J.; Brake, Matthew Robert

    2015-10-01

    Broadband impact excitation in structural dynamics is a common technique used to detect and characterize nonlinearities in mechanical systems since it excites many frequencies of a structure at once and can be applied with a variety of boundary conditions. Non-stationary time signals from transient ring-down measurements require time-frequency analysis tools to observe variations in frequency and energy dissipation as the response evolves. This work uses the short-time Fourier transform to estimate the instantaneous frequency and damping ratio from either measured or simulated transient ring-down data. By combining the discrete Fourier transform with an expanding or contracting window function that moves along the time axis, the resulting spectrum is used to estimate the instantaneous frequencies, damping and complex Fourier coefficients. This method is demonstrated on a multi-degree-of-freedom beam with a cubic spring attachment, and investigates the amplitudefrequency dependence in connection to the undamped nonlinear normal modes. A second example shows the results from experiment ring-down response on a beam with a lap joint, and reveals how the system behaves as energy dissipates.

  6. Speaking modifies voice-evoked activity in the human auditory cortex.

    Science.gov (United States)

    Curio, G; Neuloh, G; Numminen, J; Jousmäki, V; Hari, R

    2000-04-01

    The voice we most often hear is our own, and proper interaction between speaking and hearing is essential for both acquisition and performance of spoken language. Disturbed audiovocal interactions have been implicated in aphasia, stuttering, and schizophrenic voice hallucinations, but paradigms for a noninvasive assessment of auditory self-monitoring of speaking and its possible dysfunctions are rare. Using magnetoencephalograpy we show here that self-uttered syllables transiently activate the speaker's auditory cortex around 100 ms after voice onset. These phasic responses were delayed by 11 ms in the speech-dominant left hemisphere relative to the right, whereas during listening to a replay of the same utterances the response latencies were symmetric. Moreover, the auditory cortices did not react to rare vowel changes interspersed randomly within a series of repetitively spoken vowels, in contrast to regular change-related responses evoked 100-200 ms after replayed rare vowels. Thus, speaking primes the human auditory cortex at a millisecond time scale, dampening and delaying reactions to self-produced "expected" sounds, more prominently in the speech-dominant hemisphere. Such motor-to-sensory priming of early auditory cortex responses during voicing constitutes one element of speech self-monitoring that could be compromised in central speech disorders.

  7. Frontostriatal Circuit Dynamics Correlate with Cocaine Cue-Evoked Behavioral Arousal during Early Abstinence.

    Science.gov (United States)

    Smith, Wesley C; Rosenberg, Matthew H; Claar, Leslie D; Chang, Victoria; Shah, Sagar N; Walwyn, Wendy M; Evans, Christopher J; Masmanidis, Sotiris C

    2016-01-01

    It is thought that frontostriatal circuits play an important role in mediating conditioned behavioral responses to environmental stimuli that were previously encountered during drug administration. However, the neural correlates of conditioned responses to drug-associated cues are not well understood at the level of large populations of simultaneously recorded neurons, or at the level of local field potential (LFP) synchrony in the frontostriatal network. Here we introduce a behavioral assay of conditioned arousal to cocaine cues involving pupillometry in awake head-restrained mice. After just 24 h of drug abstinence, brief exposures to olfactory stimuli previously paired with cocaine injections led to a transient dilation of the pupil, which was greater than the dilation effect to neutral cues. In contrast, there was no cue-selective change in locomotion, as measured by the rotation of a circular treadmill. The behavioral assay was combined with simultaneous recordings from dozens of electrophysiologically identified units in the medial prefrontal cortex (mPFC) and ventral striatum (VS). We found significant relationships between cocaine cue-evoked pupil dilation and the proportion of inhibited principal cells in the mPFC and VS. Additionally, LFP coherence analysis revealed a significant correlation between pupillary response and synchrony in the 25-45 Hz frequency band. Together, these results show that pupil dilation is sensitive to drug-associated cues during acute stages of abstinence, and that individual animal differences in this behavioral arousal response can be explained by two complementary measures of frontostriatal network activity.

  8. [Neonatal screening of deafness: evoked otoacoustic emissions or acoustic distortion products?].

    Science.gov (United States)

    Roman, S; Mondain, M; Triglia, J M; Uziel, A

    2001-01-01

    Transiently evoked otoacoustic emissions (TEOAE) allows an auditory screening in neonates above 30 dB and between 2 kHz to 4 kHz. Another type of otoacoustic emissions, the distortion product (DP) allows a similar screening and provides more specific frequency information over a broader frequency range, including frequencies below 2 kHz and above 4 kHz. The goal of this study was to determine 1) the interest of distortion product in comparison with TEOAE in a auditory screening program in neonates; 2) The predictive value of information extracted from otoacoustic emissions recordings, on frequential parameters of distortion product (DP). In this prospective study, TEOAE and DP were successively recorded in 20 neonates (34 ears) with risk of hearing impairment, using the ILO92 software and hardware. When TEOAs were no detectable (9/34), the DPs were no detectable neither (10/34). When TEOAs were detectable, the Dps carried more specific frequency information above 1 kHz in 52 to 80% of the patients. DP amplitudes have been quantitatively correlated with TEOA energy bands. Correlations between DP and TEOA have been objectivized for DP2.5 and DP4 with OE2, and for DP4 and DP6 with OE5. The correlation predictive value was above 85%. In conclusion, this study demonstrated that analysis of TEOA spectrums procures frequential information without requiring DP recordings.

  9. Gender Disparities in Speech-evoked Auditory Brainstem Response in Healthy Adults.

    Science.gov (United States)

    Jalaei, Bahram; Zakaria, Mohd Normani; Mohd Azmi, Mohd Hafiz Afifi; Nik Othman, Nik Adilah; Sidek, Dinsuhaimi

    2017-04-01

    Gender disparities in speech-evoked auditory brainstem response (speech-ABR) outcomes have been reported, but the literature is limited. The present study was performed to further verify this issue and determine the influence of head size on speech-ABR results between genders. Twenty-nine healthy Malaysian subjects (14 males and 15 females) aged 19 to 30 years participated in this study. After measuring the head circumference, speech-ABR was recorded by using synthesized syllable /da/ from the right ear of each participant. Speech-ABR peaks amplitudes, peaks latencies, and composite onset measures were computed and analyzed. Significant gender disparities were noted in the transient component but not in the sustained component of speech-ABR. Statistically higher V/A amplitudes and less steeper V/A slopes were found in females. These gender differences were partially affected after controlling for the head size. Head size is not the main contributing factor for gender disparities in speech-ABR outcomes. Gender-specific normative data can be useful when recording speech-ABR for clinical purposes.

  10. Sensory-evoked and spontaneous gamma and spindle bursts in neonatal rat motor cortex.

    Science.gov (United States)

    An, Shuming; Kilb, Werner; Luhmann, Heiko J

    2014-08-13

    Self-generated neuronal activity originating from subcortical regions drives early spontaneous motor activity, which is a hallmark of the developing sensorimotor system. However, the neural activity patterns and role of primary motor cortex (M1) in these early movements are still unknown. Combining voltage-sensitive dye imaging (VSDI) with simultaneous extracellular multielectrode recordings in postnatal day 3 (P3)-P5 rat primary somatosensory cortex (S1) and M1 in vivo, we observed that tactile forepaw stimulation induced spindle bursts in S1 and gamma and spindle bursts in M1. Approximately 40% of the spontaneous gamma and spindle bursts in M1 were driven by early motor activity, whereas 23.7% of the M1 bursts triggered forepaw movements. Approximately 35% of the M1 bursts were uncorrelated to movements and these bursts had significantly fewer spikes and shorter burst duration. Focal electrical stimulation of layer V neurons in M1 mimicking physiologically relevant 40 Hz gamma or 10 Hz spindle burst activity reliably elicited forepaw movements. We conclude that M1 is already involved in somatosensory information processing during early development. M1 is mainly activated by tactile stimuli triggered by preceding spontaneous movements, which reach M1 via S1. Only a fraction of M1 activity transients trigger motor responses directly. We suggest that both spontaneously occurring and sensory-evoked gamma and spindle bursts in M1 contribute to the maturation of corticospinal and sensorimotor networks required for the refinement of sensorimotor coordination.

  11. Lasers for nonlinear microscopy.

    Science.gov (United States)

    Wise, Frank

    2013-03-01

    Various versions of nonlinear microscopy are revolutionizing the life sciences, almost all of which are made possible because of the development of ultrafast lasers. In this article, the main properties and technical features of short-pulse lasers used in nonlinear microscopy are summarized. Recent research results on fiber lasers that will impact future instruments are also discussed.

  12. Nonlinear optical materials.

    Science.gov (United States)

    Eaton, D F

    1991-07-19

    The current state of materials development in nonlinear optics is summarized, and the promise of these materials is critically evaluated. Properties and important materials constants of current commercial materials and of new, promising, inorganic and organic molecular and polymeric materials with potential in second- and third-order nonlinear optical applications are presented.

  13. Estimating nonlinear models

    Science.gov (United States)

    Billings, S. A.

    1988-03-01

    Time and frequency domain identification methods for nonlinear systems are reviewed. Parametric methods, prediction error methods, structure detection, model validation, and experiment design are discussed. Identification of a liquid level system, a heat exchanger, and a turbocharge automotive diesel engine are illustrated. Rational models are introduced. Spectral analysis for nonlinear systems is treated. Recursive estimation is mentioned.

  14. Nonlinear Cross Gramians

    NARCIS (Netherlands)

    Ionescu, T. C.; Scherpen, J. M. A.; Korytowski, A; Malanowski, K; Mitkowski, W; Szymkat, M

    2009-01-01

    We study the notion of cross Gramians for nonlinear gradient systems, using the characterization in terms of prolongation and gradient extension associated to the system. The cross Gramian is given for the variational system associated to the original nonlinear gradient system. We obtain

  15. Engineered nonlinear lattices

    DEFF Research Database (Denmark)

    Clausen, Carl A. Balslev; Christiansen, Peter Leth; Torner, L.

    1999-01-01

    We show that with the quasi-phase-matching technique it is possible to fabricate stripes of nonlinearity that trap and guide light like waveguides. We investigate an array of such stripes and find that when the stripes are sufficiently narrow, the beam dynamics is governed by a quadratic nonlinear...

  16. Controllability in nonlinear systems

    Science.gov (United States)

    Hirschorn, R. M.

    1975-01-01

    An explicit expression for the reachable set is obtained for a class of nonlinear systems. This class is described by a chain condition on the Lie algebra of vector fields associated with each nonlinear system. These ideas are used to obtain a generalization of a controllability result for linear systems in the case where multiplicative controls are present.

  17. Nonlinear Maneuver Autopilot

    Science.gov (United States)

    Menon, P. K. A.; Badgett, M. E.; Walker, R. A.

    1992-01-01

    Trajectory-control laws based on singular-perturbation theory and nonlinear dynamical modeling. Nonlinear maneuver autopilot commands flight-test trajectories of F-15 airplane. Underlying theory of controller enables separation of variables processed in fast and slow control loops, reducing amount of computation required.

  18. Denoising of single-trial matrix representations using 2D nonlinear diffusion filtering.

    Science.gov (United States)

    Mustaffa, I; Trenado, C; Schwerdtfeger, K; Strauss, D J

    2010-01-15

    In this paper we present a novel application of denoising by means of nonlinear diffusion filters (NDFs). NDFs have been successfully applied for image processing and computer vision areas, particularly in image denoising, smoothing, segmentation, and restoration. We apply two types of NDFs for the denoising of evoked responses in single-trials in a matrix form, the nonlinear isotropic and the anisotropic diffusion filters. We show that by means of NDFs we are able to denoise the evoked potentials resulting in a better extraction of physiologically relevant morphological features over the ongoing experiment. This technique offers the advantage of translation-invariance in comparison to other well-known methods, e.g., wavelet denoising based on maximally decimated filter banks, due to an adaptive diffusion feature. We compare the proposed technique with a wavelet denoising scheme that had been introduced before for evoked responses. It is concluded that NDFs represent a promising and useful approach in the denoising of event related potentials. Novel NDF applications of single-trials of auditory brain responses (ABRs) and the transcranial magnetic stimulation (TMS) evoked electroencephalographic responses denoising are presented in this paper.

  19. Ritual relieved axial dystonia triggered by gaze-evoked amaurosis.

    Science.gov (United States)

    Jacome, D E

    1997-11-01

    A woman with chronic posttraumatic axial lateropulsion cervical dystonia ("belly dancer's head") found relief of her spontaneous dystonic spasms by the sequential performance of an elaborate motor ritual. During an episode of left optic papillitis caused by central retinal vein occlusion, gaze-evoked amaurosis of the left eye developed, preceded by achromatopsia, during left lateral gaze. Gaze-evoked amaurosis triggered axial dystonia, which was followed by her unique, stereotyped, dystonia-relieving ritual that simulated a slow dance. Visual symptoms improved progressively in 1 year. Eventually, she was unable to trigger her dystonia by eye movements. Spontaneous dystonia remained otherwise unchanged from before the episode of papillitis and was still relieved by her unique ritual.

  20. Evoked potentials and head injury. 2. Clinical applications.

    Science.gov (United States)

    Rappaport, M; Hopkins, H K; Hall, K; Belleza, T

    1981-10-01

    The method of rating abnormality of evoked brain potential patterns and assessing the extent and severity of cortical and subcortical brain dysfunction in head injury patients described in Part I is applied in a clinical context. Evoked potential abnormality (EPA) scores are found to be significantly correlated both with admission and outcome disability approximately one year after head injury. Correlations increase with the increase in the number of sensory modalities tested. Correlations between EPA scores and clinical disability (measured by the Disability Rating Scale) decrease with time after injury. Significant correlations, however, persist for about 60 days after onset of injury. It was found that EP pattern abnormalities can reflect specific sensory (and at times motor) deficits in noncommunicative patients and thereby contribute significantly to early treatment and rehabilitation planning.

  1. Evoked response audiometry used in testing auditory organs of miners

    Energy Technology Data Exchange (ETDEWEB)

    Malinowski, T.; Klepacki, J.; Wagstyl, R.

    1980-01-01

    The evoked response audiometry method of testing hearing loss is presented and the results of comparative studies using subjective tonal audiometry and evoked response audiometry in tests of 56 healthy men with good hearing are discussed. The men were divided into three groups according to age and place of work: work place without increased noise; work place with noise and vibrations (at drilling machines); work place with noise and shocks (work at excavators in surface coal mines). The ERA-MKII audiometer produced by the Medelec-Amplaid firm was used. Audiometric threshhold curves for the three groups of tested men are given. At frequencies of 500, 1000 and 4000 Hz mean objective auditory threshhold was shifted by 4-9.5 dB in comparison to the subjective auditory threshold. (21 refs.) (In Polish)

  2. Temporal resolution in the hearing system and auditory evoked potentials

    DEFF Research Database (Denmark)

    Miller, Lee; Beedholm, Kristian

    2008-01-01

    3pAB5. Temporal resolution in the hearing system and auditory evoked potentials. Kristian Beedholm Institute of Biology,University of Southern Denmark, Campusvej 55, 5230 Odense M, Denmark, beedholm@mail.dk, Lee A. Miller Institute of Biology,University of Southern Denmark, Campusvej 55, 5230...... of the MRTF is not straight forward, but is often used as a measure of the ability of the auditory system to encodetemporal changes. It is, however, shown here that the MRTF must depend on the waveform of the click-evoked AEP ceAEP, whichdoes not relate directly to temporal resolution. The theoretical...... of 0.5 ms Hann weighted130 kHz tone pips presented at an increasing rate chirped over a time span of 32 ms. The results reveal that the system's responsivenessdeclines roughly exponentially as a function of click rate with a rate constant of about -0.7 kHz and appears more rate limited thanimplied...

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

    DEFF Research Database (Denmark)

    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...

  4. [Long-latency auditory evoked potentials in cochlear implants].

    Science.gov (United States)

    Mata, J J; Jiménez, J M; Pérez, J; Postigo, A; Roldán, B

    1999-01-01

    Cortical evoked potentials were evaluated in patients with cochlear implants. In a group of 8 adults of different ages, the lingual state before implantation and during rehabilitation were evaluated. Using cortical evoked potentials, the results of the P300 wave in response to two tones, one frequent (1,000 Hz) and the other infrequent (2,000 Hz), presented at 70 and 80 dB HL were studied. Results were analyzed and compared in relation to locutive state, rehabilitation stage, and intensity of stimulus. Absolute latencies did not differ significantly. However, latency values in relation to reaction time were significantly longer in prelingual than in postlingual patients (p test). The results confirmed the normality of central cognitive processes in patients with cochlear implants in objective assessment of P300 latency. The results suggest differences between prelingual and postlingual patients in relation to central signal processing.

  5. The transfer of avoidance evoking functions through stimulus equivalence classes.

    Science.gov (United States)

    Augustson, E M; Dougher, M J

    1997-09-01

    Recent research in the area of stimulus equivalence suggests that transfer of function via members of stimulus equivalence classes may have relevance to human emotional responding and the development and generalization of certain psychological disorders. This study investigated the transfer of avoidance evoking functions through equivalence classes. Eight subjects were trained in the necessary relations for two-four member stimulus equivalence classes to emerge. Next, using an on-baseline classical conditioning procedure, one member of one class was paired with shock while one member of the other class was presented without shock. Then, while subjects engaged a key-press task, a differential, signalled avoidance task was introduced wherein shock was avoided if a response occurred to the stimulus previously associated with shock. The remaining stimuli from both classes were then presented. The behavior of all eight subjects showed the differential transfer of the avoidance evoking function. The clinical and theoretical implications of the results are discussed.

  6. Short latency vestibular evoked potentials in the chicken embryo

    Science.gov (United States)

    Jones, S. M.; Jones, T. A.

    1996-01-01

    Electrophysiological responses to pulsed linear acceleration stimuli were recorded in chicken embryos incubated for 19 or 20 days (E19/E20). Responses occurred within the first 16 ms following the stimulus onset. The evoked potentials disappeared following bilateral labyrinthectomy, but persisted following cochlear destruction alone, thus demonstrating that the responses were vestibular. Approximately 8 to 10 response peaks could be identified. The first 4 positive and corresponding negative components (early peaks with latencies embryos was -15.9dBre 1.0 g/ms, which was significantly higher (P embryos and 2-week-old animals, but amplitude/intensity functions for embryos were significantly shallower than those for 2-week-old birds (P embryo and, as such, the method shows promise as an investigative tool. The results of the present study form the definitive basis for using vestibular evoked potentials in the detailed study of avian vestibular ontogeny and factors that may influence it.

  7. Visual evoked potentials in a patient with prosopagnosia.

    Science.gov (United States)

    Small, M

    1988-01-01

    Visual evoked potentials (VEPs) were recorded from a 53-year-old man with prosopagnosia during presentation of slides of known and unknown faces and under two control conditions. ANOVA comparisons with a normal male group showed no differences in P100 amplitude, P300 amplitude or P300 latency. There were no significant evoked potential differences between the patient and controls specifically related to the face conditions. There was, however, a significant delay in the latency of P100 from both hemispheres during all types of stimuli. This prolonged latency was asymmetrical, showing a right sided emphasis with the control conditions: pattern reversal and slides of geometric designs. This finding, of a dissociation in the interhemispheric delay, provides physiological evidence of stimulus-specific organisation at an early, sensory level. The fact that the P100 component showed a marked delay, yet P300 fell within normal limits for amplitude and latency, suggests that this patient's problem lies at a perceptual level.

  8. Nonlinear analysis of NPP safety against the aircraft attack

    Energy Technology Data Exchange (ETDEWEB)

    Králik, Juraj, E-mail: juraj.kralik@stuba.sk [Faculty of Civil Engineering, STU in Bratislava, Radlinského 11, 813 68 Bratislava (Slovakia); Králik, Juraj, E-mail: kralik@fa.stuba.sk [Faculty of Architecture, STU in Bratislava, Námestie Slobody 19, 812 45 Bratislava (Slovakia)

    2016-06-08

    The paper presents the nonlinear probabilistic analysis of the reinforced concrete buildings of nuclear power plant under the aircraft attack. The dynamic load is defined in time on base of the airplane impact simulations considering the real stiffness, masses, direction and velocity of the flight. The dynamic response is calculated in the system ANSYS using the transient nonlinear analysis solution method. The damage of the concrete wall is evaluated in accordance with the standard NDRC considering the spalling, scabbing and perforation effects. The simple and detailed calculations of the wall damage are compared.

  9. Nonlinear analysis of NPP safety against the aircraft attack

    Science.gov (United States)

    Králik, Juraj; Králik, Juraj

    2016-06-01

    The paper presents the nonlinear probabilistic analysis of the reinforced concrete buildings of nuclear power plant under the aircraft attack. The dynamic load is defined in time on base of the airplane impact simulations considering the real stiffness, masses, direction and velocity of the flight. The dynamic response is calculated in the system ANSYS using the transient nonlinear analysis solution method. The damage of the concrete wall is evaluated in accordance with the standard NDRC considering the spalling, scabbing and perforation effects. The simple and detailed calculations of the wall damage are compared.

  10. Effect of cromakalim and glibenclamide on spontaneous and evoked motility of the guinea-pig isolated renal pelvis and ureter.

    Science.gov (United States)

    Maggi, C A; Giuliani, S; Santicioli, P

    1994-03-01

    1. We have investigated the effect of the potassium (K) channel opener, cromakalim, on the spontaneous myogenic activity of the guinea-pig isolated renal pelvis and on myogenic contractions evoked by direct electrical stimulation of the guinea-pig isolated ureter. 2. In the presence of Bay K 8644 (1 microM), electrical stimulation of the guinea-pig ureter (10 Hz for 1 s, pulse width 5 ms, 60 V) produced regular tetrodotoxin-(1 microM) resistant phasic contractions which were suppressed by 3 microM cromakalim. Glibenclamide (0.1-3 microM), 4-aminopyridine (4-AP, 0.1-2 mM) and tetraethylammonium (TEA, 1-10 mM) produced a concentration-dependent inhibition of the effect of cromakalim with the rank order of potency (EC50 in parentheses): glibenclamide (0.64 microM) > 4-AP (1.11 mM) > TEA (6.6 mM). Apamin (0.1-0.3 microM) was without effect. 3. Cromakalim (0.1-10 microM) produced concentration-dependent inhibition and suppression of spontaneous contractions of the guinea-pig isolated renal pelvis and of evoked contractions of the ureter with EC50 values of 0.71 and 0.47 microM, respectively. 4. Glibenclamide (1 microM) produced a rightward shift of the concentration-response curve to cromakalim in both the renal pelvis and ureter, without producing depression of the maximal inhibitory effect. Glibenclamide did not affect the spontaneous activity of the renal pelvis while it produced a slight enhancement (10-15% increase) of evoked contractions of the ureter. Glibenclamide did not affect the inhibitory action of the adenylate cyclase activator, forskolin, in the renal pelvis or ureter. 5. In electrophysiological experiments (sucrose gap), cromakalim (0.3 and 1 microM) produced hyperpolarization of ureter smooth muscle. Cromakalim also produced a transient suppression of action potentials and accompanying phasic contractions evoked by electrical stimulation. Before suppression of evoked contractions, a shortening of action potential duration was observed concomitant with

  11. Nonlinear optics and photonics

    CERN Document Server

    He, Guang S

    2015-01-01

    This book provides a comprehensive presentation on most of the major topics in nonlinear optics and photonics, with equal emphasis on principles, experiments, techniques, and applications. It covers many major new topics including optical solitons, multi-photon effects, nonlinear photoelectric effects, fast and slow light , and Terahertz photonics. Chapters 1-10 present the fundamentals of modern nonlinear optics, and could be used as a textbook with problems provided at the end of each chapter. Chapters 11-17 cover the more advanced topics of techniques and applications of nonlinear optics and photonics, serving as a highly informative reference for researchers and experts working in related areas. There are also 16 pages of color photographs to illustrate the visual appearances of some typical nonlinear optical effects and phenomena. The book could be adopted as a textbook for both undergraduates and graduate students, and serve as a useful reference work for researchers and experts in the fields of physics...

  12. Nonlinear optical systems

    CERN Document Server

    Lugiato, Luigi; Brambilla, Massimo

    2015-01-01

    Guiding graduate students and researchers through the complex world of laser physics and nonlinear optics, this book provides an in-depth exploration of the dynamics of lasers and other relevant optical systems, under the umbrella of a unitary spatio-temporal vision. Adopting a balanced approach, the book covers traditional as well as special topics in laser physics, quantum electronics and nonlinear optics, treating them from the viewpoint of nonlinear dynamical systems. These include laser emission, frequency generation, solitons, optically bistable systems, pulsations and chaos and optical pattern formation. It also provides a coherent and up-to-date treatment of the hierarchy of nonlinear optical models and of the rich variety of phenomena they describe, helping readers to understand the limits of validity of each model and the connections among the phenomena. It is ideal for graduate students and researchers in nonlinear optics, quantum electronics, laser physics and photonics.

  13. Computer Processing of Visual Evoked Potentials Utilizing Digital Filtering Techniques

    OpenAIRE

    Vigorito, A.; Stephens, G.; Louis, H; Cinotti, A.; Michelson, L.; E. Stephens

    1981-01-01

    Recording of the VER (Visual Evoked Response) and the ERG (ElectroRetinoGram) in our laboratory is done with stimulation, using a fixed checkerboard pattern or a reversible checkerboard pattern. Questionable data frames are eliminated from the signal averaging process by means of a semiautomatic electronic analyzer or by means of a computer program. This special computer software, with flexible format constraints, is utilized on an off-line basis to remove residual artifacts and noise from av...

  14. Brain stem auditory evoked responses in chronic alcoholics.

    OpenAIRE

    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...

  15. Cerebral oxygen delivery and consumption during evoked neural activity

    Directory of Open Access Journals (Sweden)

    Alberto L Vazquez

    2010-06-01

    Full Text Available Increases in neural activity evoke increases in the delivery and consumption of oxygen. Beyond observations of cerebral tissue and blood oxygen, the role and properties of cerebral oxygen delivery and consumption during changes in brain function are not well understood. This work overviews the current knowledge of functional oxygen delivery and consumption and introduces recent and preliminary findings to explore the mechanisms by which oxygen is delivered to tissue as well as the temporal dynamics of oxygen metabolism. Vascular oxygen tension measurements have shown that a relatively large amount of oxygen exits pial arterioles prior to capillaries. Additionally, increases in cerebral blood flow (CBF induced by evoked neural activation are accompanied by arterial vasodilation and also by increases in arteriolar oxygenation. This increase contributes not only to the down-stream delivery of oxygen to tissue, but also to delivery of additional oxygen to extra-vascular spaces surrounding the arterioles. On the other hand, the changes in tissue oxygen tension due to functional increases in oxygen consumption have been investigated using a method to suppress the evoked CBF response. The functional decreases in tissue oxygen tension induced by increases in oxygen consumption are slow to evoked changes in CBF under control conditions. Preliminary findings obtained using flavoprotein autofluorescence imaging suggest cellular oxidative metabolism changes at a faster rate than the average changes in tissue oxygen. These issues are important in the determination of the dynamic changes in tissue oxygen metabolism from hemoglobin-based imaging techniques such as blood oxygenation-level dependent functional magnetic resonance imaging (fMRI.

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

    DEFF Research Database (Denmark)

    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. The ...... phenomenologically using compression or expansion of the system output. This was obtained by shifting the operating-point on the input-output-characteristic in relation to the ICI....

  17. [Visual evoked potentials (VEP) in anesthesia and intensive care].

    Science.gov (United States)

    Russ, W; Krumholz, W; Hempelmann, G

    1984-03-01

    Methodological considerations and different stimulation techniques of visual evoked potentials (VEP) are described. VEP can provide information about neurological function during anaesthesia, surgery and in the unconscious patient after head injury. The feasibility of the method for intraoperative monitoring in neuro- and cardiac surgery and the influence of general anaesthetics and other contributing factors such as temperature, paCO2, pO2, part are discussed.

  18. Pattern shift visual evoked response: application in neurology

    Directory of Open Access Journals (Sweden)

    Carlos A. M. Guerreiro

    1982-03-01

    Full Text Available The technique that we use for pattern shift visual evoked response (PSVER is described. PSVER is a non-invasive, practical and reliable clinical test in detecting anterior visual pathways lesions even when asymptomatic. The ability to find unsuspected lesions in multiple sclerosis, making possible an early diagnosis, is underscored. We also discuss some pathophysiologic aspects and the findings of the PSVER in some neurologic disorders with visual system involvement.

  19. Semi-global output regulation for linear systems with input saturation by composite nonlinear feedback control

    Science.gov (United States)

    Wang, Chongwen; Yu, Xiao; Lan, Weiyao

    2014-10-01

    To improve transient performance of output response, this paper applies composite nonlinear feedback (CNF) control technique to investigate semi-global output regulation problems for linear systems with input saturation. Based on a linear state feedback control law for a semi-global output regulation problem, a state feedback CNF control law is constructed by adding a nonlinear feedback part. The extra nonlinear feedback part can be applied to improve the transient performance of the closed-loop system. Moreover, an observer is designed to construct an output feedback CNF control law that also solves the semi-global output regulation problem. The sufficient solvability condition of the semi-global output regulation problem by CNF control is the same as that by linear control, but the CNF control technique can improve the transient performance. The effectiveness of the proposed method is illustrated by a disturbance rejection problem of a translational oscillator with rotational actuator system.

  20. Exploring the Optical Transient Sky with the Palomar Transient Factory

    CERN Document Server

    Rau, Arne; Law, Nicholas M; Bloom, Joshua S; Ciardi, David; Djorgovski, George S; Fox, Derek B; Gal-Yam, Avishay; Grillmair, Carl C; Kasliwal, Mansi M; Nugent, Peter E; Ofek, Eran O; Quimby, Robert M; Reach, William T; Shara, Michael; Bildsten, Lars; Cenko, S Bradley; Drake, Andrew J; Filippenko, Alexei V; Helfand, David J; Helou, George; Howell, D Andrew; Poznanski, Dovi; Sullivan, Mark

    2009-01-01

    The Palomar Transient Factory (PTF) is a wide-field experiment designed to investigate the optical transient and variable sky on time scales from minutes to years. PTF uses the CFH12k mosaic camera, with a field of view of 7.9 deg^2 and a plate scale of 1 asec/pixel, mounted on the the Palomar Observatory 48-inch Samuel Oschin Telescope. The PTF operation strategy is devised to probe the existing gaps in the transient phase space and to search for theoretically predicted, but not yet detected, phenomena, such as fallback supernovae, macronovae, .Ia supernovae and the orphan afterglows of gamma-ray bursts. PTF will also discover many new members of known source classes, from cataclysmic variables in their various avatars to supernovae and active galactic nuclei, and will provide important insights into understanding galactic dynamics (through RR Lyrae stars) and the Solar system (asteroids and near-Earth objects). The lessons that can be learned from PTF will be essential for the preparation of future large sy...

  1. Vestibular-evoked myogenic potentials in miniature pigs

    Institute of Scientific and Technical Information of China (English)

    Xi Shi; Yan Zhang; Ya Li; Shiwei Qiu; Shili Zhang; Yaohan Li; Na Yuan; Yuehua Qiao; Shiming Yang

    2016-01-01

    Objective:To report detection of vestibular-evoked myogenic potentials (VEMPs) in the miniature pig. Methods:Potentials evoked by 1000 Hz tone bursts were recorded from neck extensor muscles and the masseter muscles in normal adult Bama miniature pigs anesthetized with 3%pentobarbital sodium and Carbachol II. Results:The latency of the first positive wave P from neck extensor muscles was 7.65 ± 0.64 ms, with an amplitude of 1.66 ± 0.34 uv and a rate of successful induction of 75%at 80 dB SPL. The latency of potentials evoked from the masseter muscles was 7.60 ± 0.78 ms, with an amplitude of 1.31 ± 0.28 uv and a rate successful induction of 66%at 80 dB SPL. Conclusion:The latencies and thresholds of VEMPs recorded from the neck extensor muscle and the masseter muscle appear to be comparable in normal adult Bama miniature pigs, although the amplitude recorded from the neck extensor muscle seems to be higher than that from the masseter muscle. However, because of their usually relatively superficial and easily accessible location, as well as their large volume and strong contractions, masseter muscles may be better target muscles for recording myogenic potentials.

  2. Submillisecond unmasked subliminal visual stimuli evoke electrical brain responses.

    Science.gov (United States)

    Sperdin, Holger F; Spierer, Lucas; Becker, Robert; Michel, Christoph M; Landis, Theodor

    2015-04-01

    Subliminal perception is strongly associated to the processing of meaningful or emotional information and has mostly been studied using visual masking. In this study, we used high density 256-channel EEG coupled with an liquid crystal display (LCD) tachistoscope to characterize the spatio-temporal dynamics of the brain response to visual checkerboard stimuli (Experiment 1) or blank stimuli (Experiment 2) presented without a mask for 1 ms (visible), 500 µs (partially visible), and 250 µs (subliminal) by applying time-wise, assumption-free nonparametric randomization statistics on the strength and on the topography of high-density scalp-recorded electric field. Stimulus visibility was assessed in a third separate behavioral experiment. Results revealed that unmasked checkerboards presented subliminally for 250 µs evoked weak but detectable visual evoked potential (VEP) responses. When the checkerboards were replaced by blank stimuli, there was no evidence for the presence of an evoked response anymore. Furthermore, the checkerboard VEPs were modulated topographically between 243 and 296 ms post-stimulus onset as a function of stimulus duration, indicative of the engagement of distinct configuration of active brain networks. A distributed electrical source analysis localized this modulation within the right superior parietal lobule near the precuneus. These results show the presence of a brain response to submillisecond unmasked subliminal visual stimuli independently of their emotional saliency or meaningfulness and opens an avenue for new investigations of subliminal stimulation without using visual masking. © 2014 Wiley Periodicals, Inc.

  3. Evoked otoacoustic emissions in workers exposed to noise: A review

    Directory of Open Access Journals (Sweden)

    Alcarás, Patrícia Arruda de Souza

    2012-01-01

    Full Text Available Introduction: The otoacoustic emissions test is an essential tool in the evaluation of auditory function, since it allows the early detection of cochlear damage of occupational origin. Objective: To present a review of the literature and analyze the effectiveness of the clinical application of the otoacoustic emissions test in workers exposed to noise. Methods: A bibliographical search covering a period of 10 years was performed in the Virtual Health Library including published articles in national and international journals indexed in the internationally recognized databases for the health sciences, LILACS, SCIELO, and MEDLINE, using the terms "otoacoustic emissions" and "occupational exposure." The type of published article (national/international, the type and intensity of the stimulus most commonly used for the evoked otoacoustic emissions, the gender and age of the subjects, and the conclusions from the retrospective studies were all taken into consideration. Results and Conclusions: A total of 19 articles were analyzed, 7 national and 12 international, covering subjects from 17 to 77 years of age, mostly men. The type of stimulus most commonly used for the evoked otoacoustic emissions was the distortion method (12. Through this review, we have concluded that testing of evoked otoacoustic emissions in workers exposed to noise is an important tool in the early diagnosis of noise-induced cochlear hearing disorders.

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

    Science.gov (United States)

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

    2015-11-01

    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.

  5. Cervical and ocular vestibular evoked myogenic potentials in Behcet's disease.

    Science.gov (United States)

    Bayram, Ali; Doğan, Murat; Koç, Ali; Kalkan, Mehmet; Akçadağ, Alper; Özcan, İbrahim

    2015-01-01

    To investigate vestibular evoked myogenic potentials combined with audiologic status in Behcet's disease (BD) and to compare the results with normal healthy subjects. Cervical vestibular evoked myogenic potential (cVEMP) test, ocular vestibular evoked myogenic potential (oVEMP) test, Dix-Hallpike test, conventional pure tone audiometry (cPTA) and high frequency audiometry (HFA), and 226 and 1000Hz tympanometry were performed to each subject of the study. Cranial magnetic resonance imaging (MRI) with contrast enhancement was also performed to evaluate the central nervous system (CNS) in patients with BD. VEMP parameters including the mean peak latencies of p13-n23 and n10-p15, AR values and thresholds were not statistically different both in cVEMP and oVEMP between the BD and control groups. Except for 250Hz, mean audiological thresholds were significantly higher in the BD group. Five of the 20 patients had pathological cranial MRI findings that may be compatible with central nervous system involvement. To our knowledge, the present study is the first report investigating oVEMP and cVEMP responses combined with MRI findings in patients with BD. The presence of high frequency hearing loss is a common finding in BD and HFA may help early detection of hearing loss in patients with BD when combined with cPTA. Copyright © 2015 Elsevier Inc. All rights reserved.

  6. Somatosensory evoked magnetic fields in patients with stroke.

    Science.gov (United States)

    Maclin, E L; Rose, D F; Knight, J E; Orrison, W W; Davis, L E

    1994-12-01

    We used magnetoencephalography to evaluate areas of sensory cortex in patients with ischemic strokes involving the somatomotor system. We measured somatosensory evoked magnetic fields using a 7-channel neuromagnetometer and estimated the location of cortical responses to median nerve stimulation in 5 patients with cortical or subcortical strokes involving the somatomotor system. All patients underwent quantitative neurological examinations and a high resolution volumetric magnetic resonance imaging. The estimated current dipoles were localized onto the patient's own MRI scan in all patients with measurable responses. The location of the estimated dipole was always in non-infarcted tissue in the anatomical region of the somatosensory cortex. In 1 patient the somatosensory dipole localized to a peninsula of cortex flanked by infarcted tissue. Single photon emission computed tomography found the localized area of cortex to have significant blood flow. The estimated current dipole strengths of somatosensory evoked fields from median nerve stimulation correlated significantly (r = 0.95, P graphesthesia). The combination of evoked magnetic field recording and magnetic resonance imaging is a promising non-invasive technology for studying brain function in patients with cerebrovascular disease.

  7. Baroreceptor activation attenuates attentional effects on pain-evoked potentials.

    Science.gov (United States)

    Gray, Marcus A; Minati, Ludovico; Paoletti, Giulia; Critchley, Hugo D

    2010-12-01

    Focused attention typically enhances neural nociceptive responses, reflected electroencephalographically as increased amplitude of pain-evoked event-related potentials (ERPs). Additionally, pain-evoked ERPs are attenuated by hypertension and baroreceptor activity, through as yet unclear mechanisms. There is indirect evidence that these two effects may interact, suggesting that baroreceptor-related modulation of nociception is more than a low-level gating phenomenon. To address this hypothesis, we explored in a group of healthy participants the combined effects of cue-induced expectancy and baroreceptor activity on the amplitude of pain-evoked ERPs. Brief nociceptive skin stimuli were delivered during a simple visual task; half were preceded by a visual forewarning cue, and half were unpredictable. Nociceptive stimuli were timed to coincide either with systole (maximum activation of cardiac baroreceptors) or with diastole (minimum baroreceptor activation). We observed a strong interaction between expectancy and cardiac timing for the amplitude of the P2 ERP component; no effects were observed for the N2 component. Cued stimuli were associated with larger P2 amplitude, but this effect was abolished for stimuli presented during baroreceptor activation. No cardiac timing effect was observed for un-cued stimuli. Taken together, these findings suggest a close integration of cognitive-affective aspects of expectancy and baroreceptor influences on pain, and as such may cast further light on mechanisms underlying mental and physiological contributions to clinical pain.

  8. Brainstem auditory evoked potential abnormalities in type 2 diabetes mellitus

    Directory of Open Access Journals (Sweden)

    Sharat Gupta

    2013-01-01

    Full Text Available Background: Diabetes mellitus represents a syndrome complex in which multiple organ systems, including the central nervous system, are affected. Aim: The study was conducted to determine the changes in the brainstem auditory evoked potentials in type 2 diabetes mellitus. Materials and Methods: A cross sectional study was conducted on 126 diabetic males, aged 35-50 years, and 106 age-matched, healthy male volunteers. Brainstem auditory evoked potentials were recorded and the results were analyzed statistically using student′s unpaired t-test. The data consisted of wave latencies I, II, III, IV, V and interpeak latencies I-III, III-V and I-V, separately for both ears. Results: The latency of wave IV was significantly delayed only in the right ear, while the latency of waves III, V and interpeak latencies III-V, I-V showed a significant delay bilaterally in diabetic males. However, no significant difference was found between diabetic and control subjects as regards to the latency of wave IV unilaterally in the left ear and the latencies of waves I, II and interpeak latency I-III bilaterally. Conclusion: Diabetes patients have an early involvement of central auditory pathway, which can be detected with fair accuracy with auditory evoked potential studies.

  9. STUDY ON EVOKED POTENTIALS IN TYPE 2 DIABETIC PATIENTS

    Institute of Scientific and Technical Information of China (English)

    陈薇; 陈慎仁; 陈璇; 吴静珊; 刘兴材

    2003-01-01

    The aim of this study is to explore the changes of visual evoked potentiaK VEP), brainstem auditory evoked potential (BAEP), Somatosensory e-voked potential (SEP), event-related potential(ERP) of patients with type 2 diabetes mellitus(DM).Methods VEP, BAEP, SEP, ERP were measured in 30 cases with type 2 DM (DM group) and in 30 age- and sex-matched healthy volunteers (Control group) by using Nicolet Viking Ⅳ EMG/EP instrument. The numerical values of VEP, BAEP, SEP and ERP were recorded and analyzed by SPSS.Results Abnormalities were found as follows: VEP in 20(66.7%), BAEP in 18(60%), MNSEP in 20(66.7%),PTNSEP in 22(73.3%), and ERP in 11 (36.67%) diabetic patients, including the disappearance of wave, prolonged wave latency and decreased wave amplitude. Compared with control group, the P100 latency of VEP, the latencies of wave Ⅰ and Ⅴ, amplitude of wave Ⅴ, the interpeak latencies (IPL) of each wave in BAEP, the latencies and wave amplitudes in N9 to P20 of MNSEP and in N9 to P38 of PTNSEP, as well a

  10. Mathematical impairment associated with high-contrast abnormalities in change detection and magnocellular visual evoked response.

    Science.gov (United States)

    Jastrzebski, Nicola R; Crewther, Sheila G; Crewther, David P

    2015-10-01

    The cause of developmental dyscalculia, a specific deficit in acquisition of arithmetic skills, particularly of enumeration, has never been investigated with respect to the patency of the visual magnocellular system. Here, the question of dysfunction of the afferent magnocellular cortical input and its dorsal stream projections was tested directly using nonlinear analysis of the visual evoked potential (VEP) and through the psychophysical ability to rapidly detect visual change. A group of young adults with self-reported deficiencies of arithmetical ability, showed marked impairment in magnitude estimation and enumeration performance-though not in lexical decision reaction times when compared with an arithmetically capable group controlled for age and handedness. Multifocal nonlinear VEPs were recorded at low (24 %) and high (96 %) contrast. First- and second-order VEP kernels were comparable between groups at low contrast, but not at high contrast. The mathematically impaired group showed an abnormal lack of contrast saturation in the shortest latency first-order peak (N60) and a delayed P100 positivity in the first slice of the second-order kernel. Both features have previously been argued to be physiological markers of magnocellular function. Mathematically impaired participants also performed worse on a gap paradigm change detection for digit task showing increased reaction times for high-contrast stimuli but not for low-contrast stimuli compared with controls. The VEP results give direct evidence of abnormality in the occipital processing of magnocellular information in those with mathematical impairment. The anomalous high visual contrast physiological and psychophysical performance suggests an abnormality in the inhibitory processes that normally result in saturation of contrast gain in the magnocellular system.

  11. Law of nonlinear flow in saturated clays and radial consolidation

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    It was derived that micro-scale amount level of average pore radius of clay changed from 0.01 to 0.1 micron by an equivalent concept of flow in porous media. There is good agreement between the derived results and test ones. Results of experiments show that flow in micro-scale pore of saturated clays follows law of nonlinear flow. Theoretical analyses demonstrate that an interaction of solid-liquid interfaces varies inversely with permeability or porous radius. The interaction is an important reason why nonlinear flow in saturated clays occurs. An exact mathematical model was presented for nonlinear flow in micro-scale pore of saturated clays. Dimension and physical meanings of parameters of it are definite. A new law of nonlinear flow in saturated clays was established. It can describe characteristics of flow curve of the whole process of the nonlinear flow from low hydraulic gradient to high one. Darcy law is a special case of the new law. A mathematical model was presented for consolidation of nonlinear flow in radius direction in saturated clays with constant rate based on the new law of nonlinear flow. Equations of average mass conservation and moving boundary, and formula of excess pore pressure distribution and average degree of consolidation for nonlinear flow in saturated clay were derived by using an idea of viscous boundary layer, a method of steady state in stead of transient state and a method of integral of an equation. Laws of excess pore pressure distribution and changes of average degree of consolidation with time were obtained. Results show that velocity of moving boundary decreases because of the nonlinear flow in saturated clay. The results can provide geology engineering and geotechnical engineering of saturated clay with new scientific bases. Calculations of average degree of consolidation of the Darcy flow are a special case of that of the nonlinear flow.

  12. Transient response of finned-tube condenser in household refrigerators

    Energy Technology Data Exchange (ETDEWEB)

    Porkhial, S. [Technical Department, Karaj Branch, Islamic Azad University, Tehran (Iran); Khastoo, B. [Mechanical Engineering Department, Amirkabir University, Tehran (Iran); Modarres Razavi, M.R. [Mechanical Engineering Department, Ferdowsi University, Mashhad (Iran)

    2006-10-15

    A distributed parameter model for prediction of the transient performance of a condenser is presented. The model is capable of predicting the refrigerant temperature distribution, tube wall temperature, quality of refrigerant, inventory mass of refrigerant as a function of position and time. An efficient two-level iteration method is proposed to obtain the numerical solution of the model without solving a large set of non-linear equations simultaneously. A finned tube condenser of 12ft{sup 3} refrigerator with R12 as working fluid was chosen as a sample and some tests were carried out to determine its transient response. The examination of results indicates that the theoretical model provides a reasonable prediction of dynamic response compared to the experimental data. Transient behavior of temperature, pressure, mass flow rate, mass of liquid and vapor of refrigerant, quality, heat transfer in household refrigerators have been presented. Also time-dependent displacement of interface between saturated and superheated regions has been shown. Extensive examinations of theoretical and experimental results show that with utilization of a controllable compressor, power consumption can be reduced. (author)

  13. An analytical description of transient thermal processes in harmonic crystals

    Science.gov (United States)

    Kuzkin, V. A.; Krivtsov, A. M.

    2017-05-01

    We consider two transient thermal processes in uniformly heated harmonic crystals: (i) equalibration of kinetic and potential energies and (ii) redistribution of the kinetic energy among the spatial directions. Equations describing these two processes in two-dimensional and three-dimensional crystals are derived. Analytical solutions of these equations for the square and triangular lattices are obtained. It is shown that the characteristic time of the transient processes is of the order of ten periods of atomic vibrations. The difference between the kinetic and potential energies oscillates in time. For the triangular lattice, amplitude of the oscillations decays inversely proportional to time, while for the square lattice it decays inversely proportional to the square root of time. In general, there is no equipartition of the kinetic energy among spatial directions, i.e. the kinetic temperature demonstrates tensor properties. In addition, the covariance of velocities of different particles is nonzero even at the steady state. The analytical results are supported by numerical simulations. It is also shown that the obtained solutions accurately describe the transient thermal processes in weakly nonlinear crystals at short times.

  14. Prognosis in prolonged coma patients with diffuse axonal injury assessed by somatosensory evoked potential

    Institute of Scientific and Technical Information of China (English)

    Xiujue Zheng; Mantao Chen; Jingqi Li; Fei Cao

    2013-01-01

    A total of 43 prolonged coma patients with diffuse axonal injury received the somatosensory evoked potential examination one month after injury in the First Affiliated Hospital, School of Medicine, Zhejiang University in China. Somatosensory evoked potentials were graded as normal, abnormal or absent (grades I–III) according to N20 amplitude and central conduction time. The outcome in patients with grade III somatosensory evoked potential was in each case unfavorable. The prognostic accuracy of grade III somatosensory evoked potential for unfavorable and non-awakening outcome was 100% and 80%, respectively. The prognostic accuracy of grade I somatosensory evoked potential for favorable and wakening outcome was 86% and 100%, respectively. These results suggest that somatosensory evoked potential grade is closely correlated with coma severity and degree of recovery. Somatosensory evoked potential is a valuable diagnostic tool to assess prognosis in prolonged coma patients with diffuse axonal injury.

  15. A joint sparse representation-based method for double-trial evoked potentials estimation.

    Science.gov (United States)

    Yu, Nannan; Liu, Haikuan; Wang, Xiaoyan; Lu, Hanbing

    2013-12-01

    In this paper, we present a novel approach to solving an evoked potentials estimating problem. Generally, the evoked potentials in two consecutive trials obtained by repeated identical stimuli of the nerves are extremely similar. In order to trace evoked potentials, we propose a joint sparse representation-based double-trial evoked potentials estimation method, taking full advantage of this similarity. The estimation process is performed in three stages: first, according to the similarity of evoked potentials and the randomness of a spontaneous electroencephalogram, the two consecutive observations of evoked potentials are considered as superpositions of the common component and the unique components; second, making use of their characteristics, the two sparse dictionaries are constructed; and finally, we apply the joint sparse representation method in order to extract the common component of double-trial observations, instead of the evoked potential in each trial. A series of experiments carried out on simulated and human test responses confirmed the superior performance of our method.

  16. Identification of causal relations between haemodynamic variables, auditory evoked potentials and isoflurane by means of fuzzy logic

    DEFF Research Database (Denmark)

    Jensen, E W; Nebot, A; Caminal, P;

    1999-01-01

    ) methodology. A fuzzy model is able to identify non-linear and linear components of a causal relationship by means of optimization of information content of available data. Nine young female patients undergoing hysterectomy under general anaesthesia were included. Mean arterial pressure (MAP), heart rate (HR......The aim of this study was to identify a possible relationship between haemodynamic variables, auditory evoked potentials (AEP) and inspired fraction of isoflurane (ISOFl). Two different models (isoflurane and mean arterial pressure) were identified using the fuzzy inductive reasoning (FIR...... the depth of anaesthesia index (DAI) normalized to 100 when the patient was awake and descending to an average of 25 during loss of consciousness. The FIR methodology identified those variables among the input variables (MAP, HR, CO2ET, DAI or ISOFl) that had the highest causal relation with the output...

  17. Transient stability of LHC strands

    CERN Document Server

    Baynham, D Elwyn; Coombs, R C; Bauer, P; Wolf, R

    1999-01-01

    The Large Hadron Collider (LHC) machine will operate at 1.9 K in order to achieve the high bending fields required in the dipole magnets. The cable and coil matrix is designed to be 'porous' in order to allow the He II coolant to $9 penetrate within the cable for stability enhancement. This paper describes transient stability measurements and theoretical modelling carried out on single strands from the LHC cable. The experimental work has been carried out at the $9 Rutherford Appleton Laboratory under an agreement with CERN. The aim of the experimental work has been to measure the influence of the strand surface treatment on the quench energy. The surface treatment, oxidized copper, tin-silver, $9 nickel etc., determines the transient heat transfer coefficients to the He II under high heat flux, short timescale (approximately 20 microseconds) conditions. The test equipment, based on an inductive heating technique, is described $9 and quench energy measurements presented. The experimental results are compared ...

  18. Transient Ablation of Teflon Hemispheres

    Science.gov (United States)

    Arai, Norio; Karashima, Kei-ichi; Sato, Kiyoshi

    1997-01-01

    For high-speed entry of space vehicles into atmospheric environments, ablation is a practical method for alleviating severe aerodynamic heating. Several studies have been undertaken on steady or quasi-steady ablation. However, ablation is a very complicated phenomenon in which a nonequilibrium chemical process is associated with an aerodynamic process that involves changes in body shape with time. Therefore, it seems realistic to consider that ablation is an unsteady phenomenon. In the design of an ablative heat-shield system, since the ultimate purpose of the heat shield is to keep the internal temperature of the space vehicle at a safe level during entry, the transient heat conduction characteristics of the ablator may be critical in the selection of the material and its thickness. This note presents an experimental study of transient ablation of Teflon, with particular emphasis on the change in body shape, the instantaneous internal temperature distribution, and the effect of thermal expansion on ablation rate.

  19. Transient stability and emergency control

    Institute of Scientific and Technical Information of China (English)

    2009-01-01

    Comparability of emergency control strategies with different instability modes is the key issue to decide which control strategy to be implemented. This paper considers that the essential factor causing instability should be used to form a unified standard to assess the effectiveness of control strategies with different instability modes. Thus a switching control stabilization principle was proposed based on elimination of the unbalanced energy between mechanical and electrical energies of generator sets. Along this way, the difficulty of seeking a Lyapunov function was circumvented. According to the principle, an emergency control algorithm framework was established to handle transient stability assessment, control location selection and control amount evaluation. Within the framework, this paper studied instability mode transition, then proposed an algorithm based on prediction function and a new approach to normalized stability margin stemmed from static EEAC method, which can increase comparability of various control locations. The simulations on the New-England System verified the proposed emergency control method for stabilizing transient stability.

  20. Computer Aided Transient Stability Analysis

    Directory of Open Access Journals (Sweden)

    Nihad M. Al-Rawi

    2007-01-01

    Full Text Available A program for handling and improving the transient stability of the Iraqi Super Grid electrical network was developed. The idea was demonstrated by applying it to the outages of the main generating units. The methodology was built upon a state of increasing power transfer through the healthy portion of network during disturbances. There were three parts concerned; the first part was the developing of the load flow program using fast decoupled method and the transient stability program using Modified Euler’s method in the step by step solution, the second part was the engagement between the two programs, the third part was the application of the new program on the Iraqi supper grid network (400 kV.