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Sample records for active tremor compensation

  1. Compact Sensing Design of a Handheld Active Tremor Compensation Instrument

    Latt, Win Tun; Tan, U-Xuan; Shee, Cheng Yap; Riviere, Cameron N.; Ang, Wei Tech

    2009-01-01

    Active physiological tremor compensation instruments have been under research and development recently. The sensing unit of the instruments provides information on three degrees-of-freedom (DOF) motion of the instrument tip using accelerations provided by accelerometers placed inside the instruments. A complete vector of angular acceleration of the instrument needs to be known to obtain information on three DOF motions of the tip. Sensing resolution of angular acceleration about the instrumen...

  2. FES-controlled Co-contraction Strategies for Pathological Tremor Compensation

    Bo, Antonio; Poignet, Philippe; Zhang, DingGuo; Ang, Wei Tech

    2009-01-01

    International audience In this paper, a strategy for pathological tremor compensation based on co-contraction of antagonist muscles induced by Functional Electrical Stimulation (FES) is presented. Although one of the simplest alternatives to apply FES for reducing the effects of tremor, the contribution of different co-contraction levels for joint motion and impedance must be accurately estimated, specially since tremor itself is highly time-varying. In this work, a detailed musculoskeleta...

  3. Concept for tremor compensation for a handheld OCT-laryngoscope

    Donner, Sabine; Deutsch, Stefanie; Bleeker, Sebastian; Ripken, Tammo; Krüger, Alexander

    2013-06-01

    Optical coherence tomography (OCT) is a non-invasive imaging technique which can create optical tissue sections, enabling diagnosis of vocal cord tissue. To take full advantage from the non-contact imaging technique, OCT was adapted to an indirect laryngoscope to work on awake patients. Using OCT in a handheld diagnostic device the challenges of rapid working distance adjustment and tracking of axial motion arise. The optical focus of the endoscopic sample arm and the reference-arm length can be adjusted in a range of 40 mm to 90 mm. Automatic working distance adjustment is based on image analysis of OCT B-scans which identifies off depth images as well as position errors. The movable focal plane and reference plane are used to adjust working distance to match the sample depth and stabilise the sample in the desired axial position of the OCT scans. The autofocus adjusts the working distance within maximum 2.7 seconds for the maximum initial displacement of 40 mm. The amplitude of hand tremor during 60 s handheld scanning was reduced to 50 % and it was shown that the image stabilisation keeps the position error below 0.5 mm. Fast automatic working distance adjustment is crucial to minimise the duration of the diagnostic procedure. The image stabilisation compensates relative axial movements during handheld scanning.

  4. Modulating basal ganglia and cerebellar activity to suppress parkinsonian tremor

    Heida, T.; Zhao, Yan; Wezel, van, H.B.

    2013-01-01

    Despite extensive research, the detailed pathophysiology of the parkinsonian tremor is still unknown. It has been hypothesized that the generation of parkinsonian tremor is related to abnormal activity within the basal ganglia. The cerebello-thalamic-cortical loop has been suggested to indirectly contribute to the expression of parkinsonian tremor. However, the observed tremor-related hyperactivity in the cerebellar loop may have a compensatory rather than a causal role in Parkinson's disease...

  5. Triggered tremors beneath the seismogenic zone of an active fault zone, Kyushu, Japan

    Miyazaki, Masahiro; Matsumoto, Satoshi; Shimizu, Hiroshi

    2015-11-01

    Non-volcanic tremors were induced by the surface waves of the 2012 Sumatra earthquake around the Hinagu fault zone in Kyushu, Japan. We inferred from dense seismic observation data that the hypocenters of these tremors were located beneath the seismogenic zone of the Hinagu fault. Focal mechanisms of the tremors were estimated using S-wave polarization angles. The estimated focal mechanisms show similarities to those of shallow earthquakes in this region. In addition, one of the nodal planes of the focal mechanisms is almost parallel to the strike direction of the Hinagu fault. These observations suggest that the tremors were triggered at the deeper extension of the active fault zone under stress conditions similar to those in the shallower seismogenic region. A low-velocity anomaly beneath the hypocentral area of the tremors might be related to the tremor activity.

  6. Multiple Seismic Array Observations for Tracing Deep Tremor Activity in Western Shikoku, Japan

    Takeda, T.; Matsuzawa, T.; Shiomi, K.; Obara, K.

    2011-12-01

    Deep non-volcanic tremors become very active during episodic slow-slip events in western Japan and Cascadia. The episodic tremor and slow-slip events in western Shikoku, Japan, occur at a typical interval of 6 months. Recently, it has been reported that tremor migration activity is complex and shows different migrating directions depending on time scales (Ghosh et al., 2010). Such characteristics of tremor are important to understand the mechanism of tremor and the relationship between tremor and SSEs. However it is difficult to determine the location of tremors with high accuracy because tremors show faint signals and make the identification of P/S-wave arrivals difficult. Seismic array analysis is useful to evaluate tremor activity, especially to estimate the arrival direction of seismic energy (e.g. Ueno et al., 2010, Ghosh et al., 2010), as it can distinguish multiple tremor sources occurring simultaneously. Here, we have conducted seismic array observation and analyzed seismic data during tremor activity by applying the MUSIC method to trace tremor location and its migration in western Shikoku. We have installed five seismic arrays in western Shikoku since January 2011. One of the arrays contains 30 stations with 3-component seismometers with a natural frequency of 2 Hz (Type-L array). The array aperture size is 2 km and the mean interval between stations is approximately 200 m. Each of the other arrays (Type-S array) contains 9 seismic stations with the same type of seismometers of the Type-L array, and is deployed surrounding the Type-L array. The small array aperture size is 800 m and its mean station interval is approximately 150 m. All array stations have recorded continuous waveform data at a sampling of 200Hz. In May 2011, an episodic tremor and a short-term slip event occurred for the first time during the observation period. We could retrieve the array seismic data during the whole tremor episode. The analysis of data from the type-L array confirms

  7. Cross-spectral analysis of physiological tremor and muscle activity; 2, Application to synchronized EMG

    Timmer, J; Pfleger, W; Deuschl, G

    1998-01-01

    We investigate the relationship between synchronized muscle activity and tremor time series in (enhanced) physiological tremor by cross-spectral analysis. Special attention is directed to the phase spectrum and its possibilities to clarify the contribution of reflex mechanisms to physiological tremor. The phase spectra are investigated under the assumptions that the EMG synchronization was caused by a reflex, respectively a central oscillator. In comparison of these results to phase spectra of measured data we found a significant contribution of reflexes. But reflexes only modify existing peaks in the power spectrum. The main agents of physiological tremor are an efferent pace and the resonant behavior of the biomechanical system.

  8. Along strike variation of tremor activities and thermal structures in various subduction zones

    Yabe, S.; Ide, S.; Yoshioka, S.

    2012-12-01

    A family of slow earthquakes, e.g., deep low frequency tremors, low frequency earthquakes (LFEs), very low frequency earthquakes (VLFs) and slow slip events (SSEs), are observed in various subduction zones. These phenomena represent shear slip on the plate interface, and they are thought to be related to brittle-ductile transition behavior on the plate interface because they are often located near the transition zones of interplate coupling estimated from GPS data. Such slip behavior along the plate interface would be controlled by temperature. Furthermore, tremors are considered to be related to fluid dehydrated from the subducting slab, through temperature dependent chemical reactions. Therefore, tremors occurrences are expected to be influenced by temperature, though some studies have questioned about the relationship between tremor activity and temperature. Here we investigate the source locations of deep tremor using an envelope correlation method and compare them with the temperature and shear strength profiles along the plate interface calculated using a numerical model (Yoshioka and Sanshadokoro, 2002). The study areas include New Zealand, southern Chile, and Mexico, where tremor behavior changes significantly along the strike of the plate interface. Investigating such along-strike variation in individual subduction zone may clarify the temperature dependence of tremor because environmental conditions affecting tremor occurrence are similar, unlike the comparison between different subduction zones. In the Hikurangi subduction zone beneath the North Island, New Zealand, the depth of SSE are quite different along the strike, e.g., deeper in the central region and shallower in the northern region (e.g. Wallace and Beavan, 2010). We reanalyze tremors detected by previous studies (Kim et al., 2011; Ide, 2012) to estimate their absolute depth and confirm that tremors in North Island are on the plate interface in both the central and the northern regions. Thermal

  9. Depth-dependent activity of non-volcanic tremor and other slow earthquake in the Nankai subduction zone

    Obara, K.

    2010-12-01

    In the Nankai subduction zone, some types of slow earthquakes have been detected by dense seismic/geodetic observation network. At the deeper part in the transition zone between the locked and stable sliding zones, the tremor is distributed within a narrow belt with a 600 km along the strike of the subducting Philippine Sea plate (Obara, 2002). The major tremor burst is often accompanied by the short-term slow slip event (Obara et al., 2004) and deep very low frequency earthquake (Ito et al., 2007). Between the belt-like tremor zone and locked zone, the long-term slow slip event occurs at eastern and western edges of the tremor belt-like zone. These slow earthquakes represent a clear depth-dependent property. The slip behavior in time is drastically different between the shallower long-term slow slip event and deeper coupling events. Within the tremor source area, the temporal behavior of tremor activity is different in depth. In western Shikoku and northeastern Kii where major tremor bursts associated with short-term slow slip events frequently occur, the tremor distribution is separated into double peaks at shallower and deeper edge in the dip direction (Obara et al., 2010). The updip tremor activity is modulated by the major tremor burst occurring at regular recurrence interval. On the other hand, the downdip tremor activity is composed of more frequent occurrence of minor burst. The nucleation of the tremor activity often occurs from the deeper part and migrates updip direction, then propagates along strike laterally. In Bungo channel between Shikoku and Kyushu islands at the western edge of the tremor source belt, the long-term slow slip event with duration from a half to one year occurs every 6 years in 1997, 2003 and 2010. The transient slip event strongly affect to the tremor activity. Especially, the updip part of the tremor activity in Bungo channel is clearly correlated to the GPS displacement caused by the long-term slow slip event; however, the downdip

  10. Volcanic tremor associated with eruptive activity at Bromo volcano

    E. Gottschämmer

    1999-06-01

    Full Text Available Three broadband stations were deployed on Bromo volcano, Indonesia, from September to December 1995. The analysis of the seismograms shows that the signals produced by the volcanic sources cover the frequency range from at least 25 Hz down to periods of several minutes and underlines, therefore, the importance of broadband recordings. Frequency analysis reveals that the signal can be divided into four domains. In the traditional frequency range of volcanic tremor (1-10 Hz sharp transitions between two distinct values of the tremor amplitude can be observed. Additional tremor signal including frequencies from 10 to 20 Hz could be found during late November and early December. Throughout the whole experiment signals with periods of some hundred seconds were observed which are interpreted as ground tilts. For these long-period signals a particle motion analysis was performed in order to estimate the source location. Depth and radius can be estimated when the source is modeled as a sudden pressure change in a sphere. The fourth frequency range lies between 0.1 and 1 Hz and is dominated by two spectral peaks which are due to marine microseism. The phase velocity and the direction of wave propagation of these signals could be determined using the tripartite-method.

  11. Cross-spectral analysis of physiological tremor and muscle activity; 1, Theory and application to unsynchronized EMG

    Timmer, J; Pfleger, W; Deuschl, G

    1998-01-01

    We investigate the relationship between the extensor electromyogram (EMG) and tremor time series in physiological hand tremor by cross-spectral analysis. Special attention is directed to the phase spectrum and the effects of observational noise. We calculate the theoretical phase spectrum for a second order linear stochastic process and compare the results to measured tremor data recorded from subjects who did not show a synchronized EMG activity in the corresponding extensor muscle. The results show that physiological tremor is well described by the proposed model and that the measured EMG represents a Newtonian force by which the muscle acts on the hand.

  12. Effect of Crocus sativus extracts and its active constituent safranal on the harmaline-induced tremor in mice

    Bahareh Amin

    2015-05-01

    Full Text Available Objective(s: Due to unsatisfactory response or intolerable side effects of current drugs, treatment of essential tremor remains inadequate. Thus, we aimed to investigate the protective and therapeutic effects of aqueous and ethanolic extracts of Crocus sativus (saffron, and its active consistent, safranal, on the harmaline-induced tremor in mice. Materials and Methods: To induce tremor, harmaline (30 mg/kg was injected intraperitoneally. Test groups were also given the aqueous and ethanolic extracts of saffron (40, 80, and 160 mg/kg as well as safranal (0.1, 0.3, and 0.5 ml/kg, intraperitoneally, 10 min before harmaline administration (prophylactic study or 10 min after the onset of tremors (curative study. The latency of onset, duration, and intensity of tremor were recorded. Results: The extracts (80 and160 mg/kg dose dependently attenuated duration of harmaline-induced tremors as did reference drug, propranolol (2 and 5 mg/kg. Only the highest dose of extracts (160 mg/kg attenuated intensity of harmaline-induced tremors throughout the study. Safranal at the doses of (0.1 and 0.3 ml/kg but not 0.5 ml/kg attenuated duration and intensity of tremor. Onset of tremor increased with the extracts (80 and 160 mg/kg in prophylactic study, as the effect observed with propranolol at the dose of 5 mg/kg. Safranal did not affect the latency of tremor. Conclusion: Both aqueous and ethanolic extracts of saffron and with a less effect, low doses of safranal, have relatively protective and suppressive effects on the harmaline-induced tremor and different constituents of extracts seem to participate in the protective effects against harmaline induced tremor.

  13. Activity regimes inferred from automatic classification of volcanic tremor at Mt. Etna, Italy

    Masotti, Matteo; Falsaperla, Susanna; Langer, Horst; Spampinato, Salvatore; Campanini, Renato

    2007-01-01

    A renewal of eruptive activity at Mt Etna started from the Southeast Crater on 14 July 2006, about 16 months after the end of the last effusive episode. This new eruption reiterated the importance of continuous volcanic monitoring as well as the need of automatic processing and classification of those signals which might be used to disclose such impending eruptive stages. Among seismic signals, volcanic tremor - the persistent background radiation continuously recorded on open ...

  14. Action Tremor Associated with Lamotrigine Monotherapy

    Ji-Hye Yang

    2010-05-01

    Full Text Available Lamotrigine (LTG is associated with a tremor when given in combination with valproic acid; however, a tremor associated with lamotrigine monotherapy is rare. Here, we report a case of positional and action tremor associated with lamotrigine use. Based on the temporal relationship, it is conceivable that lamotrigine increases serotonin transmission or affects basal ganglia dopamine activity, thereby causing the tremor.

  15. Suppression of enhanced physiological tremor via stochastic noise: initial observations.

    Carlos Trenado

    Full Text Available Enhanced physiological tremor is a disabling condition that arises because of unstable interactions between central tremor generators and the biomechanics of the spinal stretch reflex. Previous work has shown that peripheral input may push the tremor-related spinal and cortical systems closer to anti-phase firing, potentially leading to a reduction in tremor through phase cancellation. The aim of the present study was to investigate whether peripherally applied mechanical stochastic noise can attenuate enhanced physiological tremor and improve motor performance. Eight subjects with enhanced physiological tremor performed a visuomotor task requiring the right index finger to compensate a static force generated by a manipulandum to which Gaussian noise (3-35 Hz was applied. The finger position was displayed on-line on a monitor as a small white dot which the subjects had to maintain in the center of a larger green circle. Electromyogram (EMG from the active hand muscles and finger position were recorded. Performance was measured by the mean absolute deviation of the white dot from the zero position. Tremor was identified by the acceleration in the frequency range 7-12 Hz. Two different conditions were compared: with and without superimposed noise at optimal amplitude (determined at the beginning of the experiment. The application of optimum noise reduced tremor (accelerometric amplitude and EMG activity and improved the motor performance (reduced mean absolute deviation from zero. These data provide the first evidence of a significant reduction of enhanced physiological tremor in the human sensorimotor system due to application of external stochastic noise.

  16. Risk compensation behaviours in construction workers' activities.

    Feng, Yingbin; Wu, Peng

    2015-01-01

    The purpose of this study was to test whether the construction workers have the tendency of engaging in risk compensation behaviours, and identify the demographic variables, which may influence the extent to which the construction workers may show risk compensation behaviours. Both quantitative (survey) and qualitative (interviews) approaches were used in this study. A questionnaire survey was conducted with all the construction workers on three building construction sites of a leading construction company in Australia. Semi-structured interviews were then conducted to validate the findings of the quantitative research. The findings indicate that workers tend to show risk compensation behaviours in the construction environment. The workers with more working experience, higher education, or having never been injured at work before have a higher tendency to show risk compensation in their activities than the others. The implication is that contractors need to assess the potential influence of workers' risk compensation behaviours when evaluating the effect of risk control measures. It is recommended that supervisors pay more attention to the behavioural changes of those workers who have more experience, higher education, and have never been injured before after the implementation of new safety control measures on construction site. PMID:24134314

  17. Active tremor cancellation by a “Smart” handheld vitreoretinal microsurgical tool using swept source optical coherence tomography

    Song, Cheol; Gehlbach, Peter L.; Kang, Jin U.

    2012-01-01

    Abstract: Microsurgeons require dexterity to make precise and stable maneuvers to achieve surgical objectives and to minimize surgical risks during freehand procedures. This work presents a novel, common path, swept source optical coherence tomography-based “smart” micromanipulation aided robotic-surgical tool (SMART) that actively suppresses surgeon hand tremor. The tool allows enhanced tool tip stabilization, more accurate targeting and the potential to lower surgical risk. Freehand perform...

  18. Unusual Forehead Tremor in Four Patients with Essential Tremor

    Jordi Gascón-Bayarri

    2012-01-01

    Full Text Available Forehead tremor has only been reported in two patients with essential tremor, one with rhythmic tremor and the other with dystonic tremor. We report 4 new patients with essential tremor who present a 4–6 Hz frontal tremor registered by electromyography and unusual features like frontal tremor preceding limb tremor or unilateral involvement. Frontal tremor is present in some patients with essential tremor, sometimes preceding limb tremor. Treatment with botulinum toxin may be useful.

  19. Active Wireline Heave Compensation for Ocean Drilling

    Goldberg, D.; Liu, T.; Swain, K.; Furman, C.; Iturrino, G. J.

    2014-12-01

    The up-and-down heave motion of a ship causes a similar motion on any instruments tethered on wireline cable below it. If the amplitude of this motion is greater than a few tens of cm, significant discrepancy in the depth below the ship is introduced, causing uncertainty in the acquired data. Large and irregular cabled motions also increase the risk of damaging tethered instruments, particularly those with relatively delicate sensors. In 2005, Schlumberger and Deep Down, Inc built an active wireline heave compensator (AHC) system for use onboard the JOIDES Resolution to compensate for heave motion on wireline logging tools deployed in scientific drill holes. The goals for the new AHC system were to (1) design a reliable heave compensation system; and (2) devise a robust and quantitative methodology for routine assessment of compensation efficiency (CE) during wireline operations. Software programs were developed to monitor CE and the dynamics of logging tools in real-time, including system performance under variable parameters such as water depth, sea state, cable length, logging speed and direction. We present the CE results from the AHC system on the JOIDES Resolution during a 5-year period of recent IODP operations and compare the results to those from previous compensation systems deployed during ODP and IODP. Based on new data under heave conditions of ±0.2-2.0 m and water depths of 300-4,800 m in open holes, the system reduces 65-80% of downhole tool displacement under stationary conditions and 50-60% during normal logging operations. Moreover, down/up tool motion at low speeds (300-600 m/h) reduces the system's CE values by 15-20%, and logging down at higher speeds (1,000-1,200 m/h) reduces CE values by 55-65%. Furthermore, the system yields slightly lower CE values of 40-50% without tension feedback of the downhole cable while logging. These results indicate that the new system's compensation efficiency is comparable to or better than previous systems

  20. Essential Tremor Is More Than a Tremor

    Full Text Available ... in new window) Click to email this to a friend (Opens in new window) Click to print ( ... in new window) Essential Tremor is More Than a Tremor Providing a voice for people with essential ...

  1. Essential Tremor Is More Than a Tremor

    Full Text Available ... Essential Tremor > Video Video Click to share on Facebook (Opens in new window) Click to share on ... woman shares story of living with Essential Tremor Disorder Raving Fan Home About the IETF Volunteer For ...

  2. Multistation alarm system for eruptive activity based on the automatic classification of volcanic tremor: specifications and performance

    Langer, Horst; Falsaperla, Susanna; Messina, Alfio; Spampinato, Salvatore

    2015-04-01

    With over fifty eruptive episodes (Strombolian activity, lava fountains, and lava flows) between 2006 and 2013, Mt Etna, Italy, underscored its role as the most active volcano in Europe. Seven paroxysmal lava fountains at the South East Crater occurred in 2007-2008 and 46 at the New South East Crater between 2011 and 2013. Month-lasting lava emissions affected the upper eastern flank of the volcano in 2006 and 2008-2009. On this background, effective monitoring and forecast of volcanic phenomena are a first order issue for their potential socio-economic impact in a densely populated region like the town of Catania and its surroundings. For example, explosive activity has often formed thick ash clouds with widespread tephra fall able to disrupt the air traffic, as well as to cause severe problems at infrastructures, such as highways and roads. For timely information on changes in the state of the volcano and possible onset of dangerous eruptive phenomena, the analysis of the continuous background seismic signal, the so-called volcanic tremor, turned out of paramount importance. Changes in the state of the volcano as well as in its eruptive style are usually concurrent with variations of the spectral characteristics (amplitude and frequency content) of tremor. The huge amount of digital data continuously acquired by INGV's broadband seismic stations every day makes a manual analysis difficult, and techniques of automatic classification of the tremor signal are therefore applied. The application of unsupervised classification techniques to the tremor data revealed significant changes well before the onset of the eruptive episodes. This evidence led to the development of specific software packages related to real-time processing of the tremor data. The operational characteristics of these tools - fail-safe, robustness with respect to noise and data outages, as well as computational efficiency - allowed the identification of criteria for automatic alarm flagging. The

  3. Seismic wave triggering of nonvolcanic tremor, episodic tremor and slip, and earthquakes on Vancouver Island

    Rubinstein, Justin L.; Gomberg, Joan; Vidale, John E.; Wech, Aaron G.; Kao, Honn; Creager, Kenneth C.; Rogers, Garry

    2009-02-01

    We explore the physical conditions that enable triggering of nonvolcanic tremor and earthquakes by considering local seismic activity on Vancouver Island, British Columbia during and immediately after the arrival of large-amplitude seismic waves from 30 teleseismic and 17 regional or local earthquakes. We identify tremor triggered by four of the teleseismic earthquakes. The close temporal and spatial proximity of triggered tremor to ambient tremor and aseismic slip indicates that when a fault is close to or undergoing failure, it is particularly susceptible to triggering of further events. The amplitude of the triggering waves also influences the likelihood of triggering both tremor and earthquakes such that large amplitude waves triggered tremor in the absence of detectable aseismic slip or ambient tremor. Tremor and energy radiated from regional/local earthquakes share the same frequency passband so that tremor cannot be identified during these smaller, more frequent events. We confidently identify triggered local earthquakes following only one teleseism, that with the largest amplitude, and four regional or local events that generated vigorous aftershock sequences in their immediate vicinity. Earthquakes tend to be triggered in regions different from tremor and with high ambient seismicity rates. We also note an interesting possible correlation between large teleseismic events and episodic tremor and slip (ETS) episodes, whereby ETS events that are "late" and have built up more stress than normal are susceptible to triggering by the slight nudge of the shaking from a large, distant event, while ETS events that are "early" or "on time" are not.

  4. Tremor in the elderly

    Deuschl, Günther; Petersen, Inge; Lorenz, Delia;

    2015-01-01

    Isolated tremor in the elderly is commonly diagnosed as essential tremor (ET). The prevalence of tremor increases steeply with increasing age, whereas hereditary tremor is becoming less common. Moreover, late-manifesting tremor seems to be associated with dementia and earlier mortality. We...... hypothesize that different entities underlie tremor in the elderly. Two thousand four hundred forty-eight subjects from the Longitudinal Study of Aging Danish Twins older than 70 y answered screening questions for ET in 2001. Two thousan fifty-six (84%) participants drew Archimedes spirals to measure their...

  5. Drug-induced tremor

    ... tremor include the following: Cancer medicines such as thalidomide and cytarabine Seizure medicines such as valproic acid ( ... eyelids. In rare cases, the lower body is affected. The tremor may not affect both sides of ...

  6. Tremor (Beyond the Basics)

    ... finger, or to show a sample of your handwriting. Seeing how the tremor changes under these circumstances ... normal. Likewise, people whose tremor is caused by Parkinson disease sometimes improve when they begin treatment for ...

  7. Tremor - self-care

    ... habits if you have problems sleeping. Stress and anxiety can also make your tremor worse. These things may lower your stress level: Meditation, deep relaxation, or breathing exercises Reducing your caffeine intake Alcohol use can also cause tremors. If ...

  8. Infrasonic tremor in the diffraction zone

    Fee, David; Garcés, Milton

    2007-08-01

    Volcanic tremor signals recorded by an infrasound array ~12.5 km from the active vent of Kīlauea Volcano show clear diurnal amplitude variations and originate from a well defined direction pointing to the active Pu`u `Ō`ō crater complex. Spectral amplitudes between 0.02-0.3 Hz, a proxy for wind speed, increase when the wind speeds increase during the daytime. Spectral amplitudes between 0.5-3 Hz, where infrasonic tremor is concentrated, increase when the wind speeds decrease at night. Power spectrum analysis shows that when ambient noise levels drop, infrasonic tremor amplitudes rise. Array processing confirms this relationship and reveals tremor detections and amplitudes decrease during the day. These changes in infrasonic tremor spectral amplitude and coherence are most likely due to diurnal variations in atmospheric boundary layers affecting infrasonic propagation within the diffraction zone. Recognition of these regional atmospheric patterns is necessary to permit robust infrasonic remote sensing of volcanic processes.

  9. Active noise compensation for multichannel magnetocardiography in an unshielded environment

    Aarnink, W.A.M.; Bosch, van den, G.; Roelofs, T.-M.; Verbiesen, M.; Holland, H.J.; Brake, ter, H.J.M.; Rogalla, H.

    1995-01-01

    A multichannel high-T/sub c/-SQUID-based heart scanner for unshielded environments is under development, Outside a magnetically shielded room, sensitive SQUID measurements are possible using gradiometers. However, it is difficult to realize large-baseline gradiometers in high-T/sub c/ materials, Therefore, the authors developed two active noise compensation techniques. In the Total Field Compensation technique, a Helmholtz type coil set is placed around the sensors. One magnetometer is used a...

  10. Cerebral causes and consequences of parkinsonian resting tremor: a tale of two circuits?

    Helmich, Rick C.; Hallett, Mark; Deuschl, Günther; Toni, Ivan; Bloem, Bastiaan R.

    2012-01-01

    Tremor in Parkinson's disease has several mysterious features. Clinically, tremor is seen in only three out of four patients with Parkinson's disease, and tremor-dominant patients generally follow a more benign disease course than non-tremor patients. Pathophysiologically, tremor is linked to altered activity in not one, but two distinct circuits: the basal ganglia, which are primarily affected by dopamine depletion in Parkinson's disease, and the cerebello-thalamo-cortical circuit, which is ...

  11. The effects of isometric resistance training on stretch reflex induced tremor in the knee extensor muscles.

    Durbaba, Rade; Cassidy, Angela; Budini, Francesco; Macaluso, Andrea

    2013-06-15

    This study examines the effect of 4 wk of high-intensity isometric resistance training on induced tremor in knee extensor muscles. Fourteen healthy volunteers were assigned to either the training group (n = 7) or the nontraining control group (n = 7). Induced tremor was assessed by measuring force fluctuations during anisometric contractions against spring loading, whose compliance was varied to allow for preferential activation of the short or long latency stretch reflex components. Effects of high-intensity isometric resistance training on induced tremor was assessed under two contraction conditions: relative force matching, where the relative level of activity was equal for both pre- and post-training sessions, set at 30% maximum voluntary contraction (MVC), and absolute force matching, where the level of activity was set to 30% pretrained MVC. The training group experienced a 26.5% increase in MVC in contrast to the 0.8% for the control group. For relative force-matching contractions, induced tremor amplitude and frequency did not change in either the training or control group. During absolute force-matching contractions, induced tremor amplitude was decreased by 37.5% and 31.6% for the short and long components, respectively, with no accompanying change in frequency, for the training group. No change in either measure was observed in the control group for absolute force-matching contractions. The results are consistent with high-intensity isometric resistance training induced neural changes leading to increased strength, coupled with realignment of stretch reflex automatic gain compensation to the new maximal force output. Also, previous reported reductions in anisometric tremor following strength training may partly be due to changed stretch reflex behavior. PMID:23580599

  12. Widespread Triggered Tremor In Japan Following the 2012 Mw8.6 Sumatra Earthquake

    Chao, K.; Obara, K.

    2012-12-01

    Deep "non-volcanic" tremor has been observed at many major plate-boundary faults around the Pacific Rim. Recent studies have shown that the tremor triggered by the surface waves of teleseismic earthquake occurs on the same fault patches as the ambient tremor (i.e., those occurring spontaneously). The observations suggest that the triggered tremor can be used as a proxy to estimate the background tremor activity. Triggered and ambient tremors have been well studied along the Nankai subduction zone in southwest Japan. Recently, new identified triggered tremor sources were found in Hokkaido in northernmost Japan (Obara, 2012, submitted manuscript), suggesting, contrary to previous beliefs, that tremor can be observed in various tectonic environments. Here, we systematically search for triggered tremor on the main islands of Japan (i.e., Kyushu, Shikoku, Honshu, and Hokkaido) following the 2012/04/11 Mw 8.6 Sumatra earthquake. We examined a total of about 1300 seismic stations from the Hi-net operated by NIED (National Research Institute for Earth Science and Disaster Prevention) and other arrays operated by universities and other organizations. We first identified triggered tremor as a high-frequency, non-impulsive signal in phase with the large-amplitude teleseismic waves and then located the triggered tremor sources using a standard envelope cross-correlation technique. We also compared the tremor triggering potential with Love and Rayleigh waves by shifting the seismograms of tremor and surface waves back to the best tremor source. We observed clear triggered tremor following the 2012 Sumatra mainshock in Shikoku, Kii, and Tokai, where ambient tremors are very active and triggered tremors have been identified previously. Moreover, we successfully detected new triggered tremor sources in Hokkaido, Kyushu, and Kanto. In central Hokkaido, tremor triggered by the 2012 Sumatra earthquake was located at the same place where tremor was triggered by the 2004 Sumatra

  13. Essential Tremor Is More Than a Tremor

    Full Text Available IETF > About Essential Tremor > Video Video Click to share on Facebook (Opens in new window) Click to share on Twitter (Opens in new window) Click to share ... of this life-altering neurological condition. Meet our video volunteers: Recent News FDA approves first MRI-guided ...

  14. Essential Tremor Is More Than a Tremor

    Full Text Available IETF > About Essential Tremor > Video Video Click to share on Facebook (Opens in new window) Click to share on Twitter (Opens in new window) Click to share ... of this life-altering neurological condition. Meet our video volunteers: Recent News Essential Networking FDA approves first ...

  15. Adaptive Compensation of Reactive Power With Shunt Active Power Filters

    Blaabjerg, Frede; Asiminoaei, Lucian; Hansen, Steffan;

    2008-01-01

    This paper describes an adaptive method for compensating the reactive power with an active power filter (APF), which is initially rated for mitigation of only the harmonic currents given by a nonlinear industrial load. It is proven that, if the harmonic currents do not load the APF at the rated...

  16. Volcanic tremor at Volcán de Colima, México recorded during May 2002 and its interactions with the seismic signals produced by low-energy explosive activity and rockfalls

    Zobin, Vyacheslav M.; Reyes, Gabriel A.; Bretón, Mauricio

    2016-05-01

    The May 2002 eruption episode at Volcán de Colima, México represented the transition period between two stages of effusive activity which were characterized by the formation of lava flows. The short-period seismic signals, recorded during May 2002 at a distance of 1.6 km from the crater, were represented by volcanic tremor and the signals produced by low-energy explosions and rockfalls. Two types of volcanic tremor were recognized: harmonic with two fundamental spectral frequencies of 1.2-1.4 Hz and 1.6-1.7 Hz and non-harmonic. The existence of two fundamental frequencies of volcanic tremor may indicate a two-vent magmatic conduit. No clear relationship between the variations in the spectral content of tremor and occurrence of explosions was observed. The waveforms of the signals, produced by low-energy explosions and rockfalls and recorded on the background of volcanic tremor, were strongly modulated by the low-frequency harmonic tremor signals, forming, in this manner, pseudo-long period events. Fourier analysis of the seismic signals associated with low-energy explosions and rockfalls but recorded on the background of regular seismic noise indicated their high-frequency sources characterized by dominant frequencies within 2-3 Hz and 3-4.5 Hz, respectively.

  17. Best-basis analysis of broadband tremor signals

    P. Steffen

    1999-06-01

    Full Text Available Active volcanoes usually generate highly non-stationary broadband tremor signals. Short-time shock events with a frequency content of several decades are superimposed on a stationary narrow band continuous tremor. Tremor signals of this type can be observed in the near field of many active volcanoes. In this paper we will demonstrate the analysis of such signals using a specific tremor signal of Mt. Stromboli (Sicily. We used the Best-Basis Algorithm (BBA in order to compute a spectrogram which is adapted to signal properties on highly different scales. It turns out that the BBA can reveal better fitting properties of the tremor in the time-frequency plane compared to standard methods like Short-Time Fourier Transformation (STFT. Moreover, this very effective algorithm can be used for real time monitoring in the time-frequency plane, for data compression or for de-noising of the tremor signals.

  18. Treatment of Essential Tremor

    ... essential tremor. Neurologists from the American Academy of Neurology are doctors who identify and treat diseases of ... an educational service of the American Academy of Neurology. It is based on an assessment of current ...

  19. Pharmacotherapy of essential tremor.

    Hedera, Peter; Cibulčík, František; Davis, Thomas L

    2013-01-01

    Essential tremor (ET) is a common movement disorder but its pathogenesis remains poorly understood. This has limited the development of effective pharmacotherapy. The current therapeutic armamentaria for ET represent the product of careful clinical observation rather than targeted molecular modeling. Here we review their pharmacokinetics, metabolism, dosing, and adverse effect profiles and propose a treatment algorithm. We also discuss the concept of medically refractory tremor, as therapeutic trials should be limited unless invasive therapy is contraindicated or not desired by patients. PMID:24385718

  20. Pharmacotherapy of Essential Tremor

    Peter Hedera; František Cibulcík; Davis, Thomas L.

    2013-01-01

    Essential tremor (ET) is a common movement disorder but its pathogenesis remains poorly understood. This has limited the development of effective pharmacotherapy. The current therapeutic armamentaria for ET represent the product of careful clinical observation rather than targeted molecular modeling. Here we review their pharmacokinetics, metabolism, dosing, and adverse effect profiles and propose a treatment algorithm. We also discuss the concept of medically refractory tremor, as therapeuti...

  1. Triggered tremor in inland region in Japan (Invited)

    Obara, K.; Chao, K.

    2013-12-01

    Episodic activity of nonvolcanic ambient tremor accompanied by short-term slow slip event observed in Nankai and Cascadia subduction zones reflects stick slip at the transition zone along the plate interface as one of the subduction process. On the other hand, tremor is sometimes activated temporally by surface wave from teleseismic large event. The triggered tremor has the same properties in frequency content and source location as those of ambient tremor. Therefore the detection of triggered tremor suggests the existence of ambient tremor, which might reflect slow slip event. Ambient tremor activity has been detected not only in the subduction zone but also along the strike slip fault system like as San Andreas Fault. Therefore, even in Japan, there is a possibility to detect tremor associated with the active fault system in inland region. Here we tried to search the triggered tremor during propagation of large amplitude surface wave from M8 class teleseismic large events. All Hi-net stations operated by the National Research Institute for Earth Science and Disaster Prevention were used in this analysis. We compared the envelope trace for the bandpass filtered seismogram (2-8 Hz) with the long-period surface wave with the passband between 0.02 and 0.05 Hz. The envelope pattern characterized by a periodic enhancement at an interval of about a few 10 s correlating to the surface wave is recognized as triggered tremor. So far, we newly detected triggered tremor in some inland regions in Japan in addition to subduction tremor. In central Hokkaido, the tremor at a depth of around 10-20 km coincides with active seismicity linked to previously known, deep low-frequency microearthquakes related to volcanic activity. In northernmost Hokkaido, where there are no known active faults, volcanoes, or microearthquake seismicity, the triggered tremor is located near the ground surface. It would be possible that the tremor is related to fluid pressure change within a limestone

  2. Compensation guidelines respecting damages relating to offshore petroleum activity

    These guidelines described the many compensation sources available to potential claimants for loss or damage associated with offshore petroleum activity in the province of Newfoundland and Labrador and the province of Nova Scotia. Offshore petroleum exploration and production in these two provinces are regulated by the Canada-Newfoundland Offshore Petroleum Board (CNOPB) and the Canada-Nova Scotia Offshore Petroleum Board (CNSOPB). The Canada-Newfoundland Atlantic Accord Implementation Act and the Canada-Nova Scotia Offshore Petroleum Resources Accord Implementation Act are the authorities that deal with matters of compensation. In particular, the compensation guidelines described in this report refer to damages that may occur as a result of spills or of debris left on the ocean floor. They are especially important along Canada's east coast where fishing is a major factor in the economy. The CNOPB and the CNSOPB each have a mandate that allows property owners and fishermen to recover economic loss resulting from an oil spill or debris that was caused by an oil company. Also, the petroleum industry and the fishing industry have both voluntarily established a fisheries compensation strategy for damages resulting from seafloor debris for those instances where a responsible party cannot be identified. The guidelines outline the regulatory and administrative roles which the Boards uses for payments for actual loss or damage directly caused by offshore operators. This document replaces the original edition of these Guidelines published in September 1991. 1 fig

  3. Tremor suppression in ECG

    Mihov Georgy S

    2008-11-01

    Full Text Available Abstract Background Electrocardiogram recordings are very often contaminated by high-frequency noise usually power-line interference and EMG disturbances (tremor. Specific method for interference cancellation without affecting the proper ECG components, called subtraction procedure, was developed some two decades ago. Filtering out the tremor remains a priori partially successful since it has a relatively wide spectrum, which overlaps the useful ECG frequency band. Method The proposed method for tremor suppression implements the following three procedures. Contaminated ECG signals are subjected to moving averaging (comb filter with linear phase characteristic with first zero set at 50 Hz to suppress tremor and PL interference simultaneously. The reduced peaks of QRS complexes and other relatively high and steep ECG waves are then restored by an introduced by us procedure called linearly-angular, so that the useful high frequency components are preserved in the range specified by the embedded in the ECG instrument filter, usually up to 125 Hz. Finally, a Savitzky-Golay smoothing filter is applied for supplementary tremor suppression outside the QRS complexes. Results The results obtained show a low level of the residual EMG disturbances together with negligible distortion of the wave shapes regardless of rhythm and morphology changes.

  4. Anterior Cruciate Ligament Injury: Compensation during Gait using Hamstring Muscle Activity

    Catalfamo, Paola Formento; Aguiar, Gerardo; Curi, Jorge; Braidot, Ariel

    2010-01-01

    Previous research has shown that an increase in hamstring activation may compensate for anterior tibial transalation (ATT) in patients with anterior cruciate ligament deficient knee (ACLd); however, the effects of this compensation still remain unclear. The goals of this study were to quantify the activation of the hamstring muscles needed to compensate the ATT in ACLd knee during the complete gait cycle and to evaluate the effect of this compensation on quadriceps activation and joint contac...

  5. Tremor due to sodium valproate.

    Hyman, N M; Dennis, P D; Sinclair, K G

    1979-08-01

    Four patients developed postural tremor after ingestion of sodium valproate. The tremor was recorded by a variable-capacitance transducer and was of the "benign essential" type. The dosages of sodium valproate varied between 1000 mg and 2000 mg daily and serum levels were between 34.9 microgram per milliliter and 154.3 microgram per milliliter. Tremor was ameliorated in two cases when the dosage was reduced. In only one case was the serum level in the toxic range for our laboratory. The pharmacology of essential tremor is unknown; production of a similar tremor by a drug could serve as a biochemical model. PMID:379690

  6. Triggered tectonic tremor in various types of fault systems of Japan following the 2012 Mw8.6 Sumatra earthquake

    Chao, Kevin; Obara, Kazushige

    2016-01-01

    Tectonic tremor, an extremely stress-sensitive seismic phenomenon occurring in the brittle-ductile transition section of a fault, is associated with the shearing mechanism of slow slip. Observations of triggered tremor can facilitate the evaluation of the existence of background ambient tremor and slow-slip events. This paper presents widespread triggered tremor sources in Japan initiated by the surface waves of the 2012 Mw8.6 Sumatra earthquake on strike-slip and thrust faults, in the deep volcanic low-frequency earthquake active area, in the shallow tectonic tremor and very low frequency earthquake active regions, and in the subduction zone. In most regions, the amplitudes of triggered tremor are generally logarithmically proportional to the dynamic stress caused by various triggering earthquakes. Our observations suggest that triggered tremor in the newly discovered sources is the result of a more rapid rate of background ambient tremor, and evidence has suggested the existence of ambient tremor in some regions.

  7. 77 FR 56710 - Proposed Information Collection (Veteran's Application for Compensation and/or Pension) Activity...

    2012-09-13

    ... AFFAIRS Proposed Information Collection (Veteran's Application for Compensation and/or Pension) Activity..., for compensation and/or pension benefit sought. DATES: Written comments and recommendations on the... Compensation and/or Pension, VA Form 21-526. b. Veteran's Supplemental Claim Application, VA Form 21-526b....

  8. Hypothetical membrane mechanisms in essential tremor

    Ramat Stefano

    2008-11-01

    Full Text Available Abstract Background Essential tremor (ET is the most common movement disorder and its pathophysiology is unknown. We hypothesize that increased membrane excitability in motor circuits has a key role in the pathogenesis of ET. Specifically, we propose that neural circuits controlling ballistic movements are inherently unstable due to their underlying reciprocal innervation. Such instability is enhanced by increased neural membrane excitability and the circuit begins to oscillate. These oscillations manifest as tremor. Methods Postural limb tremor was recorded in 22 ET patients and then the phenotype was simulated with a conductance-based neuromimetic model of ballistic movements. The model neuron was Hodgkin-Huxley type with added hyperpolarization activated cation current (Ih, low threshold calcium current (IT, and GABA and glycine mediated chloride currents. The neurons also featured the neurophysiological property of rebound excitation after release from sustained inhibition (post-inhibitory rebound. The model featured a reciprocally innervated circuit of neurons that project to agonist and antagonist muscle pairs. Results Neural excitability was modulated by changing Ih and/or IT. Increasing Ih and/or IT further depolarized the membrane and thus increased excitability. The characteristics of the tremor from all ET patients were simulated when Ih was increased to ~10× the range of physiological values. In contrast, increasing other membrane conductances, while keeping Ih at a physiological value, did not simulate the tremor. Increases in Ih and IT determined the frequency and amplitude of the simulated oscillations. Conclusion These simulations support the hypothesis that increased membrane excitability in potentially unstable, reciprocally innervated circuits can produce oscillations that resemble ET. Neural excitability could be increased in a number of ways. In this study membrane excitability was increased by up-regulating Ih and IT. This

  9. Pharmacological and physiological characterization of the tremulous jaw movement model of parkinsonian tremor: potential insights into the pathophysiology of tremor

    Lyndsey E. Collins-Praino

    2011-07-01

    Full Text Available Tremor is a cardinal symptom of parkinsonism, occurring early on in the disease course and affecting more than 70% of patients. Parkinsonian resting tremor occurs in a frequency range of 3-7Hz and can be resistant to available pharmacotherapy. Despite its prevalence, and the significant decrease in quality of life associated with it, the pathophysiology of parkinsonian tremor is poorly understood. The tremulous jaw movement (TJM model is an extensively validated rodent model of tremor. TJMs are induced by conditions that also lead to parkinsonism in humans (i.e. striatal DA depletion, DA antagonism and cholinomimetic activity and reversed by several antiparkinsonian drugs (i.e. DA precursors, DA agonists, anticholinergics and adenosine A2A antagonists. TJMs occur in the same 3-7 Hz frequency range seen in parkinsonian resting tremor, a range distinct from that of dyskinesia (1-2 Hz and postural tremor (8-14 Hz. Overall, these drug-induced TJMs share many characteristics with human parkinsonian tremor, but do not closely resemble tardive dyskinesia. The current review discusses recent advances in the validation of the tremulous jaw movement model, and illustrates how this model is being used to develop novel therapeutic strategies, both surgical and pharmacological, for the treatment of parkinsonian resting tremor.

  10. Precise location of San Andreas Fault tremors near Cholame, California using seismometer clusters: Slip on the deep extension of the fault?

    Shelly, D.R.; Ellsworth, W.L.; Ryberg, T.; Haberland, C.; Fuis, G.S.; Murphy, J.; Nadeau, R.M.; Burgmann, R.

    2009-01-01

    We examine a 24-hour period of active San Andreas Fault (SAF) tremor and show that this tremor is largely composed of repeated similar events. Utilizing this similarity, we locate the subset of the tremor with waveforms similar to an identified low frequency earthquake (LFE) "master template," located using P and S wave arrivals to be ???26 km deep. To compensate for low signal-to-noise, we estimate event-pair differential times at "clusters" of nearby stations rather than at single stations. We find that the locations form a near-linear structure in map view, striking parallel to the SAF and near the surface trace. Therefore, we suggest that at least a portion of the tremor occurs on the deep extension of the fault, likely reflecting shear slip, similar to subduction zone tremor. If so, the SAF may extend to the base of the crust, ???10 km below the deepest regular earthquakes on the fault. ?? 2009 by the American Geophysical Union.

  11. Voluntary driven elbow orthosis with speed controlled tremor suppression

    Gil eHerrnstadt

    2016-03-01

    Full Text Available Robotic technology is gradually becoming commonplace in the medical sector and in the service of patients. Medical conditions that have benefited from significant technological development include stroke, for which rehabilitation with robotic devices is administered, and surgery assisted by robots. Robotic devices have also been proposed for assistance of movement disorders. Pathological tremor, among the most common movement disorders, is such one example. In practice, the dissemination and availability of tremor suppression robotic systems has been limited. Devices in the marketplace tend to either be non-ambulatory or to target specific functions such as eating and drinking.We have developed a one degree-of-freedom (DOF elbow orthosis that could be worn by an individual with tremor. A speed controlled voluntary driven suppression approach is implemented with the orthosis. Typically tremor suppression methods estimate the tremor component of the signal and produce a canceling counterpart signal. The suggested approach, instead estimates the voluntary component of the motion. A controller then actuates the orthosis based on the voluntary signal while simultaneously rejecting the tremorous motion.In this work, we tested the suppressive orthosis using a 1 DOF robotic system that simulates the human arm. The suggested suppression approach does not require a model of the human arm. Moreover, the human input along with the orthosis forearm gravitational forces, of nonlinear nature, are considered as part of the disturbance to the suppression system. Therefore, the suppression system can be modeled linearly. Nevertheless, the orthosis forearm gravitational forces can be compensated by the suppression system.The electromechanical design of the orthosis is presented, and data from an Essential Tremor patient is used as the human input. Velocity tracking results demonstrate an RMS error of 0.31 rad/s, and a power spectral density shows a reduction of

  12. Quantification of sound instability in embouchure tremor based on the time-varying fundamental frequency.

    Lee, André; Voget, Jakob; Furuya, Shinichi; Morise, Masanori; Altenmüller, Eckart

    2016-05-01

    Task-specific tremor in musicians is an involuntary oscillating muscular activity mostly of the hand or the embouchure, which predominantly occurs while playing the instrument. In contrast to arm or hand tremors, which have been examined and objectified based on movement kinematics and muscular activity, embouchure tremor has not yet been investigated. To quantify and describe embouchure tremor we analysed sound production and investigated the fluctuation of the time-varying fundamental frequency of sustained notes. A comparison between patients with embouchure tremor and healthy controls showed a significantly higher fluctuation of the fundamental frequency for the patients in the high pitch with a tremor frequency range between 3 and 8 Hz. The present findings firstly provide further information about a scarcely described movement disorder and secondly further evaluate a new quantification method for embouchure tremor, which has recently been established for embouchure dystonia. PMID:27023201

  13. Finger tremor in Parkinson's disease.

    Lakie, M; Mutch, W J

    1989-01-01

    Finger tremor was investigated in 20 patients (age range 54-88 yr) diagnosed as suffering from idiopathic Parkinson's disease and six controls of a similar age and no known neurological abnormality. In nine of the patients tremor was not clinically obvious. When the tremor of these patients was recorded immediately after voluntary movement and subjected to instrumental analysis there were consistently observable differences from the controls. Such analysis may have diagnostic potential when t...

  14. A neuroprothesis for tremor management

    Gallego Abella, Juan Álvaro

    2013-01-01

    Tremor is the most common movement disorder, affecting ∼ 15 % of people over 50 years old according to some estimates. It appears due to a number of syndromes, being essential tremor and Parkinson's disease the most prevalent among them. None of these conditions is fully understood. Tremor is currently treated through drugs or neurosurgery, but unfortunately, it is not managed effectively in ∼25 % of the patients. Therefore, it constitutes a major cause of loss of independence and quality of ...

  15. Activity compensation and activity synergy in British 8-13 year olds

    Goodman, A.; Mackett, R.L.; Paskins, J.

    2011-01-01

    Objectives. To examine whether children compensate for participating in physically active behaviors by reducing activity at other times (the 'activitystat' hypothesis); or alternatively become more active at other times (activity synergy).Methods. In 2002-2006, 345 British children (8-13 years) completed activity diaries and wore accelerometers. This generated 1077 days of data which we analyzed between-children (comparing all days) and within-child (comparing days from the same child).Result...

  16. Compensation of Disturbed Load Currents Using Active Power Filter and Generalized Non-active Power Theory

    Lettl, J.; Šimek, Petr; Valouch, Viktor

    Prague: Electromagnetics Academy, 2015, s. 2500-2505. ISSN 1559-9450. [Progress In Electromagnetics Research Symposium Proceedings. Prague (CZ), 06.07.2015-09.07.2015] Institutional support: RVO:61388998 Keywords : disturbed load * GNP (Generalized Non-active Power) * parallel compensation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering www.piers.org

  17. An approach to source characterization of tremor signals associated with eruptions and lahars

    Kumagai, Hiroyuki; Mothes, Patricia; Ruiz, Mario; Maeda, Yuta

    2015-11-01

    Tremor signals are observed in association with eruption activity and lahar descents. Reduced displacement ( D R) derived from tremor signals has been used to quantify tremor sources. However, tremor duration is not considered in D R, which makes it difficult to compare D R values estimated for different tremor episodes. We propose application of the amplitude source location (ASL) method to characterize the sources of tremor signals. We used this method to estimate the tremor source location and source amplitude from high-frequency (5-10 Hz) seismic amplitudes under the assumption of isotropic S-wave radiation. We considered the source amplitude to be the maximum value during tremor. We estimated the cumulative source amplitude ( I s) as the offset value of the time-integrated envelope of the vertical seismogram of tremor corrected for geometrical spreading and medium attenuation in the 5-10-Hz band. For eruption tremor signals, we also estimated the cumulative source pressure ( I p) from an infrasonic envelope waveform corrected for geometrical spreading. We studied these parameters of tremor signals associated with eruptions and lahars and explosion events at Tungurahua volcano, Ecuador. We identified two types of eruption tremor at Tungurahua: noise-like inharmonic waveforms and harmonic oscillatory signals. We found that I s increased linearly with increasing source amplitude for lahar tremor signals and explosion events, but I s increased exponentially with increasing source amplitude for inharmonic eruption tremor signals. The source characteristics of harmonic eruption tremor signals differed from those of inharmonic tremor signals. We found a linear relation between I s and I p for both explosion events and eruption tremor. Because I p may be proportional to the total mass involved during an eruption episode, this linear relation suggests that I s may be useful to quantify eruption size. The I s values we estimated for inharmonic eruption tremor were

  18. Essential tremor: electrophysiological and pharmacological evidence for a subdivision.

    Deuschl, G; Lücking, C H; Schenck, E

    1987-01-01

    Forty five patients with essential tremor have been investigated by means of clinical examination, polygraphic EMG records and testing of long-latency reflexes. Clinically there were no differences between the patients, whereas the electrophysiological investigations suggested two subtypes. One group of patients may be characterised by normal long-latency reflexes and synchronous tremor bursts in antagonists or activity of the antigravity muscle alone. The second group had abnormal long-laten...

  19. Searching for Tectonic Tremor on the North Anatolian Fault

    Pfohl, A.; Warren, L. M.; Sit, S. M.; Brudzinski, M. R.

    2012-12-01

    Tectonic tremor, a relatively newly-discovered seismologic phenomenon, has been helpful in increasing our understanding of fault evolution and slip. Tectonic tremor was first identified in subduction zones, such as Cascadia and Japan. More recently, tremor was discovered on a transform boundary, the San Andreas Fault (SAF) in California. The North Anatolian Fault (NAF) in Turkey is also a transform boundary and has a similar slip rate to the SAF but is younger. Because tremor has not previously been identified on the NAF, our search was designed to identify signals with characteristics similar to those of tremor found in previous studies. In our search for tremor, we analyzed data from the North Anatolian Fault Passive Seismic Experiment that was deployed along the NAF in central Turkey from 2005 to 2008. This experiment included 39 broadband stations, some of which were located within a few kilometers of the NAF or its major splays. In other regions, tremor has been triggered by the surface waves of large earthquakes so we first checked if this was also the case for the NAF. For the 22 earthquakes of M ≥ 5.5 in or around Turkey during the time period of the experiment, we filtered the seismograms between 2-8 Hz, the dominant tremor passband for other regions. We inspected the filtered records but did not see any tremor triggered by surface waves. We then focused on identifying ambient tremor along the NAF using a frequency ratio scanning method. Since different types of seismic signals have peak amplitudes in different frequency bands, time periods with increased tremor activity may be identified by an increase in amplitude in the appropriate frequency band. In this step of the analysis, data from all stations were filtered from 2-5 Hz, 10-15, and 0.02-0.1 Hz to differentiate tremor, local earthquakes, and surface waves, respectively, and the amplitude was computed for 5-minute-long windows for each passband. We more closely investigated time periods with

  20. 77 FR 70210 - Agency Information Collection (Veteran's Application for Compensation and/or Pension): Activity...

    2012-11-23

    ... AFFAIRS Agency Information Collection (Veteran's Application for Compensation and/or Pension): Activity... Pension, VA Form 21-526. b. Veteran's Supplemental Claim Application, VA Form 21-526b. c. Authorization.... Veterans complete VA Form 21-526 to initially apply for compensation and/or pension benefits. b....

  1. Postural and intention tremors: Detailed clinical study of essential tremor vs. Parkinson’s disease

    Eliezer J Sternberg

    2013-05-01

    Full Text Available ABSTRACTBackground: An estimated 30-50% of essential tremor diagnoses are incorrect, and the true diagnosis in those patients is often Parkinson’s disease or other tremor disorders. There are general statements about the tremor in these essential tremor and Parkinson’s disease, but published data on the more subtle characteristics of tremor are surprisingly limited. Postural tremor may occur in both disorders, adding to the difficulty. There are several anecdotal impressions regarding specific features of postural tremor in essential tremor vs. Parkinson’s disease, including joint distribution (e.g., phalanges, metacarpal-phalangeal joints, wrist, tremor directionality (e.g., flexion-extension vs. pronation-supination, and presence of intention tremor. However, there is little data to support these impressions.Methods: In this cross-sectional study, 100 patients (essential tremor, 50 Parkinson’s disease underwent detailed videotaped neurological examinations. Arm tremor was rated by a movement disorder neurologist who assessed severity and directionality across multiple joints. Results: During sustained arm extension, essential tremor patients exhibited more wrist than metacarpal-phalangeal and phalangeal joint tremor than did Parkinson’s disease patients (p<0.001, and more wrist flexion-extension tremor than wrist pronation-supination tremor (p<0.001. During the finger-nose-finger maneuver, intention tremor was present in approximately one in four (28% essential tremor patients vs. virtually none (4% of the Parkinson’s patients (p<0.001.Conclusions: We evaluated the location, severity, and directionality of postural tremor in essential tremor and Parkinson’s disease, and the presence of intention tremor, observing several clinical differences. We hope that detailed phenomenological data on tremor in essential tremor and Parkinson’s disease will help practicing physicians delineate the two diseases.

  2. Employing of Minimum Active Power Injection Strategy to Compensate Voltage Sag by DVR

    A. D. Falehi

    2011-09-01

    Full Text Available In this paper, voltage sag is compensated by the DVR (Dynamic Voltage Restorer in distribution systems. This device is applied between the sensitive load and the supply in order to inject voltage in series to correct the voltage sag. Subsequently, all the other various DVR compensation techniques in the distribution system are explained. Due to the restriction of the energy storage in DVR’s capacitors, it is essential to minimize the active power injected by the DVR. Thus, a minimum active power injection method is proposed to compensate the voltage sag. Performance of this method is evaluated under balanced and unbalance voltage sag in a distribution system.

  3. Accuracy of forecast of mine tremors location

    DRZEWIECKI Jan

    2009-01-01

    The Upper Silesian Coal Basin is one of the most active mining areas in the world in respect of seismicity. Underground mining in this area takes place in a special environment with a high degree of risk of unpredictable event occurrence. Especially dangerous are phenomena that occur during the extraction of deposits at great depths in the environment of compact rocks. Deep underground mining violates the balance of these rocks and induces dynamic phenomena at the longwall life (in terms of distance) referred to as mine tremors. The sources of these tremors are located in layers characterised by high strength, especially in thick sandstone strata occurring in the roof of the mined seam. In the paper a discussion is presented about the influence of mining inten-sity (longwall face speed) on the location of mine tremor sources, both in the direction of longwall life (in terms of distance) and towards the surface. The presented material has been prepared basing on the results of tests and measurements carried out at the Central Mining Institute.

  4. FDI activity and worker compensation: evidence from U.S. non-manufacturing industries

    Eren, Ozlem; Peoples, James

    2009-01-01

    This study examines worker compensation effects of foreign direct investment (FDI) activity in US non-manufacturing industry sectors. A clustered standard error correction is used when estimating wage and non-wage compensation equations, with special attention given to FDI’s effect by worker educational attainment and union status. Wage findings reveal that FDI activity is associated with a wage premium for highly educated non-union workers and with union rent erosion for all educational-gend...

  5. Active temperature compensation design of sensor with fiber gratings

    Xingfa Dong(董兴法); Yonglin Huang(黄勇林); Li Jiang(姜莉); Guiyun Kai(开桂云); Xiaoyi Dong(董孝义)

    2004-01-01

    A technique for compensation of temperature effects in fiber grating sensors is reported. For strain sensors and other sensors related to strain such as electromagnetic sensors, a novel structure is designed, which uses two fiber Bragg gratings (FBGs) as strain differential sensor and has temperature effects cancelled. Using this technique, the stress sensitivity has been amplified and gets up to 0.226 nm/N, the total variation in wavelength difference within the range of 3-45 ℃ is 0.03 nm, 1/14 of the uncompensated FBG.The structure can be used in the temperature-insensitive static strain measurement and minor-vibration measurement.

  6. Movement induced tremor in musicians and non-musicians reflects adaptive brain plasticity

    Lee, André; Schoonderwaldt, Erwin; Chadde, Mareike; Altenmüller, Eckart

    2014-01-01

    Evidence exists that motor dexterity is associated with a higher tremor amplitude of physiological tremor. Likewise, lower frequencies are associated with motor control. So far only case reports of a higher amplitude of physiological tremor in musicians exist. Moreover, no study has investigated lower frequencies during a finger movement task in musicians who can be regarded as a model of motor expertise. We developed a model and derived three hypotheses which we investigated in this study: (1) Tremor amplitude is higher in the range of physiological tremor and (2) higher for frequency ranges of dystonic tremor in musicians compared to non-musicians; (3) there is no difference in tremor amplitude at frequencies below 4 Hz. We measured tremor during a finger flexion-extension movement in 19 musicians (age 26.5 ± 8.2 years) and 24 age matched non-musicians (age 26.5 ± 8.7). By using empirical mode decomposition in combination with a Hilbert transform we obtained the instantaneous frequency and amplitude, allowing to compare tremor amplitudes throughout the movement at various frequency ranges. We found a significantly higher tremor amplitude in musicians for physiological tremor and a tendency toward a higher amplitude during most of the movement in the frequency range of 4–8 Hz, which, however, was not significant. No difference was found in the frequency range below 4 Hz for the flexion and for almost the entire extension movement. Our results corroborate findings that the 8–12 Hz oscillatory activity plays a role in motor dexterity. However, our results do not allow for the conclusion that tremor at the frequency range of 4–8 Hz is related to either plasticity induced changes that are beneficial for motor skill development nor to maladaptive changes as, e.g., focal dystonia. PMID:25120522

  7. Movement induced tremor in musicians and non-musicians reflects adaptive brain plasticity

    André eLee

    2014-07-01

    Full Text Available Evidence exists that motor dexterity is associated with a higher tremor amplitude of physiological tremor. Likewise, lower frequencies are associated with motor control. So far only case reports of a higher amplitude of physiological tremor in musicians exist. Moreover, no study has investigated lower frequencies during a finger movement task in musicians who can be regarded as a model of motor expertise. We developed a model and derived 3 hypotheses which we investigated in this study: 1 Tremor amplitude is higher in the range of physiological tremor and 2 higher for frequency ranges of dystonic tremor in musicians compared to non-musicians; 3 there is no difference in tremor amplitude at frequencies below 4Hz. We measured tremor during a finger flexion-extension movement in 19 musicians (age 26.5±8.2 years and 24 age matched non-musicians (age 26.5±8.7. By using empirical mode decomposition in combination with a Hilbert transform we obtained the instantaneous frequency and amplitude, allowing to compare tremor amplitudes throughout the movement at various frequency ranges. We found a significantly higher tremor amplitude in musicians for physiological tremor and a tendency towards a higher amplitude during most of the movement in the frequency range of 4-8Hz , which however was not significant. No difference was found in the frequency range below 4Hz for the flexion and for almost the entire extension movement. Our results corroborate findings that the 8-12Hz oscillatory activity plays a role in motor dexterity. However, our results do not allow for the conclusion that tremor at the frequency range of 4-8Hz is related to either plasticity induced changes that are beneficial for motor skill development nor to maladaptive changes as e.g. focal dystonia.

  8. Permanent tremor reduction during thalamic stimulation in Multiple Sclerosis

    Thevathasan, Wesley; Schweder, Patrick; Joint, Carole; Ray, Nicola; Pretorius, Pieter; Gregory, Ralph; Aziz, Tipu

    2010-01-01

    Abstract Background: Unlike thalamic lesioning, thalamic stimulation is considered a reversible treatment for tremor. However, tremor in Multiple Sclerosis (MS) can sometimes permanently improve during thalamic stimulation. Such 'permanent tremor reduction' (PTR) has been attributed to limb weakness preventing tremor expression. In this study, eleven consecutive patients with MS tremor treated with thalamic stimulation were assessed for PTR. Eighteen upper limbs had tremor, of ...

  9. Loss compensation in Metamaterials through embedding of active transistor based negative differential resistance circuits

    Xu, Wangren; Padilla, Willie J.; Sonkusale, Sameer

    2012-01-01

    This paper presents an all-electronic approach for loss compensation in metamaterials. This is achieved by embedding active-transistors based negative differential resistance (NDR) circuits in each unit cell of the metamaterial lattice. NDR circuits provide tunable loss compensation over a broad frequency range limited only by the maximum operating frequency of transistors that is reaching terahertz values in newer semiconductor processes. Design, simulation and experimental results of metama...

  10. Factors Influencing Compensation Demanded for Environmental Impacts Generated by Different Economic Activities

    Virna Vaneza Gutiérrez; Luis Abdón Cifuentes; Nicolás C. Bronfman

    2015-01-01

    This work advances the understanding of compensation demanded for environmental impacts on atmosphere, lakes and rivers, soil, and ocean generated by mining, urban, fishing and agriculture activities. Our aims are to determine whether compensation demanded depends on the standard variables used in the field of risk perception (as perceived risk, public acceptability and trust in regulating authorities), and to explore whether these relationships depend on the environment affected and on the e...

  11. Heterogeneity of tremor mechanisms assessed by tremor-related cortical potential in mice

    Park, Young-Gyun; Choi, Jee Hyun; Lee, Chungki; Kim, Sehyun; Kim, Youngsoo; Chang, Ki-Young; Paek, Sun Ha; Kim, Daesoo

    2015-01-01

    Background Identifying a neural circuit mechanism that is differentially involved in tremor would aid in the diagnosis and cure of such cases. Here, we demonstrate that tremor-related cortical potential (TRCP) is differentially expressed in two different mouse models of tremor. Results Hybrid tremor analysis of harmaline-induced and genetic tremor in mice revealed that two authentic tremor frequencies for each type of tremor were conserved and showed an opposite dependence on CaV3.1 T-type Ca...

  12. Holmes' tremor caused by midbrain cavernoma

    ZHONG Jun; LI Shi-ting; XU Shun-qing; WAN Liang

    2007-01-01

    @@ Holmes' tremor has been postulated as a syndrome attributed to those lesions that interrupt the dentatethalamic and the nigrostriatal tracts thus causing both an action and a rest tremor.1 It may arise from various underlying structural disorders including multiple sclerosis, stroke, or tumors. So far, to our knowledge, few studies on Holmes' tremor secondary to cavernoma have been reported.2 Here we report a case of disabling tremor,who harbored a cavernoma in the midbrain.

  13. The Clinical Evaluation of Parkinson's Tremor

    Zach, H.; Dirkx, M.; Bloem, B.R.; Helmich, R.C.

    2015-01-01

    Parkinson's disease harbours many different tremors that differ in distribution, frequency, and context in which they occur. A good clinical tremor assessment is important for weighing up possible differential diagnoses of Parkinson's disease, but also to measure the severity of the tremor as a basi

  14. High order single step time delay compensation algorithm for structural active control

    王焕定; 耿淑伟; 王伟

    2002-01-01

    The optimal instantaneous high order single step algorithm for active control is first discussed andthen, the n + 1 time step controlling force vector of the instantaneous optimal algorithm is derived from way of ntime state vector. An estimating algorithm, is developed from this to solve the problem of active control withtime delay compensation. The estimating algorithm based on this high order single step β method (HSM) foun-dation, is proven by simulation and experiment analysis, to be a valid solution to problem of active control withtime delay compensation.

  15. Repeating tectonic tremors on a middle-aged oceanic plate: Kyushu, Japan & North Island, New Zealand

    Yabe, S.; Ide, S.

    2011-12-01

    Tectonic tremors and low-frequency earthquakes (LFEs) are observed in many subduction zones, where typically young and warm oceanic plate is subducting. Here we report the discovery of tectonic tremor in Kyushu, Japan and the North Island of New Zealand, where a middle-aged oceanic plate (>50Ma) is subducting. Generally, old oceanic plate is considered incapable of supplying water near the Moho discontinuity of the overriding plate, where tectonic tremor occurs in warm subduction zones, This is probably because dehydration reaction is delayed by the low temperature of old subducting plate, but the limit of the age or temperature for tremor generation has not been clear yet. Thus the discovery of tremor in middle-aged subduction zones helps to constrain the condition for tremor generation. We apply the envelope correlation method of Ide et al. (2010) to continuous records of Hi-net NIED for Kyushu and Geo-Net for the North Island. In both data sets, we find characteristic waveforms of tectonic tremors, which are dominant in frequency range at 2-8 Hz, with detectable S-wave arrivals and obscure P-waves, and successive for a long time. However, waveforms have very small amplitude, which makes low signal to noise ratio and has prevented detection. In Kyushu, we identify eight tremor episodes repeated almost every eight month, from April 2004 to September 2009. S-P times measured by cross-correlating envelopes between vertical and horizontal components indicate that these tremors occurred at 35-45 km depth, which might be a little shallower than the plate interface, since a receiver function study estimated the local depth of the plate interface as about 50 km (Abe et al., 2011). The distribution of tectonic tremors is limited in a small area, unlike wide and dense tremor activities in the Nankai subduction zone next to Kyushu. Beneath the North Island, Kim et al., (2011) discovered tectonic tremor near the northern end of the island and Fry et al. (2011) detected

  16. Vertical Position Control for Top Tensioned Riser with Active Heave Compensator

    Leira, Bernt J.; Fang, Shaoji; Blanke, Mogens

    2011-01-01

    The top and bottom angles of a marine riser are of crucial importance during e.g. drilling and workover operations. A ver- tical position control with active heave compensator (AHC) is proposed to maintain the safety of the riser when subjected to environmental excitations. The possibility of...... reducing the maxi- mum angular response level by adjusting the vertical rod position by means of an active heave compensator is investigated with a positioning algorithm based on adaptive backstepping. Riser top and bottom angles are dealt with by the algorithm in order to minimize both angles....

  17. Factors Influencing Compensation Demanded for Environmental Impacts Generated by Different Economic Activities

    Virna Vaneza Gutiérrez

    2015-07-01

    Full Text Available This work advances the understanding of compensation demanded for environmental impacts on atmosphere, lakes and rivers, soil, and ocean generated by mining, urban, fishing and agriculture activities. Our aims are to determine whether compensation demanded depends on the standard variables used in the field of risk perception (as perceived risk, public acceptability and trust in regulating authorities, and to explore whether these relationships depend on the environment affected and on the economic activity generating the impacts. General Linear Models were used to analyze survey responses from 427 citizens of Santiago, Chile. Results showed that compensation demanded depends on perceived risk, acceptability, and on the economic activity, but not on the environment affected. Acceptability depends on trust in authorities, on perceived risk and on the economic activity. Perceived risk depends on trust, the economic activity and the environment affected. Overall, environmental impacts from the mining industry are perceived as riskier, less acceptable, and have a higher compensation demanded than those generated by the other sectors. These results suggest that to achieve sustainable development, regulations should consider not only environmental impacts but also the economic activity originating them.

  18. Actively compensation of low order aberrations by refractive shaping system for high power slab lasers

    Xue, Zheng-wei; Guo, Ya-ding; Chen, Zhong-zheng; Li, Shuai; Xu, Yi-ting; Xu, Jian; Wang, Bao-shan; Gong, Ke-ling; Gao, Hong-wei; Bo, Yong; Peng, Qin-jun; Cui, Da-fu; Xu, Zu-yan

    2015-12-01

    We present a compact refractive shaping system for actively compensating low order aberrations of high power slab lasers. The shaping system includes three spherical lenses and two cylindrical lenses. Both theoretical and experimental investigations were performed to evaluate the compensation capability of the refractive shaping system. For a typical input beam with large low order aberrations of peak-to-valley (PV)=66.10λ and root-mean-square (RMS)=16.05λ, adjusting the distance between lenses, the wavefront aberrations are reduced to PV=0.48λ, RMS=0.10λ for the theoretical simulation and PV=0.50λ, RMS=0.11λ for the experimental result, respectively. It indicates that the main low order aberrations of defocus and 0° astigmatism can be significantly compensated by actively adjusting the distance between lenses and the experimental result agree well with the theoretical simulation.

  19. Nonlinear interactions in the thalamocortical loop in essential tremor: A model-based frequency domain analysis.

    He, F; Sarrigiannis, P G; Billings, S A; Wei, H; Rowe, J; Romanowski, C; Hoggard, N; Hadjivassilliou, M; Rao, D G; Grünewald, R; Khan, A; Yianni, J

    2016-06-01

    There is increasing evidence to suggest that essential tremor has a central origin. Different structures appear to be part of the central tremorogenic network, including the motor cortex, the thalamus and the cerebellum. Some studies using electroencephalogram (EEG) and magnetoencephalography (MEG) show linear association in the tremor frequency between the motor cortex and the contralateral tremor electromyography (EMG). Additionally, high thalamomuscular coherence is found with the use of thalamic local field potential (LFP) recordings and tremulous EMG in patients undergoing surgery for deep brain stimulation (DBS). Despite a well-established reciprocal anatomical connection between the thalamus and cortex, the functional association between the two structures during "tremor-on" periods remains elusive. Thalamic (Vim) LFPs, ipsilateral scalp EEG from the sensorimotor cortex and contralateral tremor arm EMG recordings were obtained from two patients with essential tremor who had undergone successful surgery for DBS. Coherence analysis shows a strong linear association between thalamic LFPs and contralateral tremor EMG, but the relationship between the EEG and the thalamus is much less clear. These measurements were then analyzed by constructing a novel parametric nonlinear autoregressive with exogenous input (NARX) model. This new approach uncovered two distinct and not overlapping frequency "channels" of communication between Vim thalamus and the ipsilateral motor cortex, defining robustly "tremor-on" versus "tremor-off" states. The associated estimated nonlinear time lags also showed non-overlapping values between the two states, with longer corticothalamic lags (exceeding 50ms) in the tremor active state, suggesting involvement of an indirect multisynaptic loop. The results reveal the importance of the nonlinear interactions between cortical and subcortical areas in the central motor network of essential tremor. This work is important because it demonstrates

  20. Using Portable Transducers to Measure Tremor Severity

    Elble, Rodger J.; McNames, James

    2016-01-01

    Background Portable motion transducers, suitable for measuring tremor, are now available at a reasonable cost. The use of these transducers requires knowledge of their limitations and data analysis. The purpose of this review is to provide a practical overview and example software for using portable motion transducers in the quantification of tremor. Methods Medline was searched via PubMed.gov in December 2015 using the Boolean expression “tremor AND (accelerometer OR accelerometry OR gyroscope OR inertial measurement unit OR digitizing tablet OR transducer).” Abstracts of 419 papers dating back to 1964 were reviewed for relevant portable transducers and methods of tremor analysis, and 105 papers written in English were reviewed in detail. Results Accelerometers, gyroscopes, and digitizing tablets are used most commonly, but few are sold for the purpose of measuring tremor. Consequently, most software for tremor analysis is developed by the user. Wearable transducers are capable of recording tremor continuously, in the absence of a clinician. Tremor amplitude, frequency, and occurrence (percentage of time with tremor) can be computed. Tremor amplitude and occurrence correlate strongly with clinical ratings of tremor severity. Discussion Transducers provide measurements of tremor amplitude that are objective, precise, and valid, but the precision and accuracy of transducers are mitigated by natural variability in tremor amplitude. This variability is so great that the minimum detectable change in amplitude, exceeding random variability, is comparable for scales and transducers. Research is needed to determine the feasibility of detecting smaller change using averaged data from continuous long-term recordings with wearable transducers. PMID:27257514

  1. 34 CFR 222.22 - How does the Secretary treat compensation from Federal activities for purposes of determining...

    2010-07-01

    ... 34 Education 1 2010-07-01 2010-07-01 false How does the Secretary treat compensation from Federal activities for purposes of determining eligibility and payments? 222.22 Section 222.22 Education Regulations....22 How does the Secretary treat compensation from Federal activities for purposes of...

  2. Physical activity compensates for increased mortality risk among oder people with poor muscle strength

    Portegijs, Erja; Rantanen, Taina; Sipilä, Sarianna; Laukkanen, Piia; Heikkinen, Eino

    2007-01-01

    The aim of the study was to determine whether habitual physical activity can compensate for the increased mortality risk among older people with poor muscle strength. Mortality was followed up for 10 years after laboratory examination in 558 community dwelling 75- and 80-year-old men and women. Maximal isometric strength of five muscle groups was measured and tertile cut-off points were used to categorize participants. Participants, who reported moderate physical activity for at least 4 h a w...

  3. Repeating deep tremors on the plate interface beneath Kyushu, southwest Japan

    Yabe, Suguru; Ide, Satoshi

    2013-01-01

    In the subduction zone south of Kyushu Island, at the western extension of the Nankai subduction zone, southwest Japan, the age of the oceanic crust increases toward the south across the subducting Kyushu-Palau ridge. While tremor activity is very high in Nankai, tectonic tremors have only recently been discovered in Kyushu. In this study, we examined tremors beneath Kyushu using an improved version of the envelope correlation method. In doing so, we distinguished tremors from normal earthquakes and background noise using the criteria of source duration and the spectrum ratio between low and high frequencies. Accurate measurement of S- P times, using cross-correlation between vertical and horizontal seismograms, constrains the tremor depth precisely. Tremor activity is low and within a small region in southern Kyushu, where thick crust of the Kyushu-Palau ridge is being subducted, at depths between 35 and 45 km (i.e., shallower than intra-slab earthquakes by about 20 km), which is consistent with the location of the plate interface within uncertainties proposed in previous studies. Establishing precise depth estimates for tectonic tremors beneath Kyushu, which results from shear slip along the plate interface, is useful in defining the plate interface within the Nankai subduction zone.

  4. Differences in striatal dopamine transporter density between tremor dominant and non-tremor Parkinson's disease

    Parkinson's disease (PD) can manifest with a tremor-dominant or a non-tremor (akinetic-rigid) phenotype. Although the tremor-dominant subtype may show a better prognosis, there is limited information on the phenotypic differences regarding the level of striatal dopamine transmission. The present study investigated striatal dopamine transporter (DAT) binding characteristics in a large sample of patients with and without tremor. [123I]FP-CIT SPECT scans of 231 patients with a clinical diagnosis of PD and abnormal FP-CIT binding (157 with tremor, 74 without tremor) and 230 control patients with normal FP-CIT binding (148 with tremor, 82 without tremor) were analysed using an automated region-of-interest analysis of the scans (BRASS). Specific striatal binding ratios were compared between phenotypes and groups using age, sex, and symptom duration, predominant side of symptoms, dopaminergic medications and scanner as covariates. Patients with PD had 28.1 - 65.0 % lower binding in all striatal regions compared to controls (p < 0.001). The mean FP-CIT caudate nucleus uptake and the left caudate nucleus uptake were higher in PD patients with tremor than in PD patients without tremor (mean 9.0 % higher, left 10.5 % higher; p < 0.05), whereas there were no differences between tremor and non-tremor control patients. No significant effects of tremor on DAT binding were observed in the anterior or posterior putamen. The motor phenotype is associated with the extent of caudate dopamine terminal loss in PD, as dopamine function is relatively more preserved in tremor patients. Symptom type is related to caudate dopamine function only in association with Parkinsonian dopaminergic degeneration, not in intact dopamine systems in patients with non-PD tremor. (orig.)

  5. Active power compensator of the current harmonics based on the instantaneous power theory

    Marian GAICEANU

    2005-12-01

    Full Text Available The quality of the electrical current becomes a major concern. The proliferation of the power electronic converters, which are used extensively to control electrical apparatus in industrial and commercial applications (dc and ac variable speed motor drives, induction furnaces, power line conditioners, and industrial power supplies, is at the origin of the AC current distribution network pollution and the reactive power demand. These power electronic converters typically draw non-sinusoidal currents from the utility, causing interference with adjacent sensitive loads and limit the utilization of the available electrical supply. The quality of the electrical current thus becomes a significant concern for the distributors of energy and their customers. Recent progress as regards technology of the power electronics brings a capacity of compensation and correction of the harmonic distortion generated by the nonlinear loads. In this paper a parallel active filter prototype capable of reducing the total harmonic distortion in the supply for most current source or adjustable speed drive type loads is presented. A 33 kVA active power filter was developed for harmonic and reactive power compensation based on the instantaneous power theory. The active filter configuration requires the measurement of both the load and filter currents. Experimental results from a prototype active power filter confirm the suitability of the proposed approach. The actual 33kVA prototype converter has been built and tested in the SIEI S.p.A. (Italy laboratory under the Marie Curie Post Doctoral research. The active power compensator is controlled by a high performance DSP platform, resulting in the following active filter features: source current reduction up to the 25th harmonic, 10% THD achievable for current source type loads, efficiency above 97%, does not cause resonance with other loads, operation in the presence of unbalanced loads, reactive power and harmonics

  6. Electrocorticography reveals beta desynchronization in the basal ganglia-cortical loop during rest tremor in Parkinson's disease.

    Qasim, Salman E; de Hemptinne, Coralie; Swann, Nicole C; Miocinovic, Svjetlana; Ostrem, Jill L; Starr, Philip A

    2016-02-01

    The pathophysiology of rest tremor in Parkinson's disease (PD) is not well understood, and its severity does not correlate with the severity of other cardinal signs of PD. We hypothesized that tremor-related oscillatory activity in the basal-ganglia-thalamocortical loop might serve as a compensatory mechanism for the excessive beta band synchronization associated with the parkinsonian state. We recorded electrocorticography (ECoG) from the sensorimotor cortex and local field potentials (LFP) from the subthalamic nucleus (STN) in patients undergoing lead implantation for deep brain stimulation (DBS). We analyzed differences in measures of network synchronization during epochs of spontaneous rest tremor, versus epochs without rest tremor, occurring in the same subjects. The presence of tremor was associated with reduced beta power in the cortex and STN. Cortico-cortical coherence and phase-amplitude coupling (PAC) decreased during rest tremor, as did basal ganglia-cortical coherence in the same frequency band. Cortical broadband gamma power was not increased by tremor onset, in contrast to the movement-related gamma increase typically observed at the onset of voluntary movement. These findings suggest that the cortical representation of rest tremor is distinct from that of voluntary movement, and support a model in which tremor acts to decrease beta band synchronization within the basal ganglia-cortical loop. PMID:26639855

  7. Observations of volcanic tremor during January-February 2005 eruption of Mt. Veniaminof, Alaska

    De Angelis, Slivio; McNutt, Stephen R.

    2007-01-01

    Mt. Veniaminof, Alaska Peninsula, is a stratovolcano with a summit ice-filled caldera containing a small intracaldera cone and active vent. From January 2 to February 21, 2005, Mt. Veniaminof erupted. The eruption was characterized by numerous small ash emissions (VEI 0 to 1) and accompanied by low-frequency earthquake activity and volcanic tremor. We have performed spectral analyses of the seismic signals in order to characterize them and to constrain their source. Continuous tremor has durations of minutes to hours with dominant energy in the band 0.5– 4.0 Hz, and spectra characterized by narrow peaks either irregularly (non-harmonic tremor) or regularly spaced (harmonic tremor). The spectra of non-harmonic tremor resemble those of low-frequency events recorded simultaneously with surface ash explosions, suggesting that the source mechanisms might be similar or related. We propose that non-harmonic tremor at Mt. Veniaminof results from the coalescence of gas bubbles while low-frequency events are related to the disruption of large gas pockets within the conduit. Harmonic tremor, characterized by regular and quasisinusoidal waveforms, has duration of hours. Spectra containing up to five harmonics suggest the presence of a resonating source volume that vibrates in a longitudinal acoustic mode. An interesting feature of harmonic tremor is that frequency is observed to change over time; spectral lines move towards higher or lower values while the harmonic nature of the spectra is maintained. Factors controlling the variable characteristics of harmonic tremor include changes in acoustic velocity at the source and variations of the effective size of the resonator.

  8. A Novel Frequency Compensation Technique in Three Stage Amplifiers with Active Feedback

    Farshid Raissi

    2010-03-01

    Full Text Available This paper presents a dual-active capacitance in reversed nested Miller compensation (DACRNMC technique for low-voltage and large capacitive load amplifiers. The frequency bandwidth of the DACRNMC amplifier has been improved due to the usage of active compensation capacitors. The amplifier's die area is reduced in compare to the existing techniques in the RNMC scheme. The architecture also generates two left half plane zeros to increase the phase margin. The simulation for the proposed DACRNMC amplifier with a 0.18µm standard CMOS process reveals a unity gain bandwidth of 17.4MHz and phase margin of 64 degrees , while 500 pF load is driven from a single 1.5V power supply.

  9. An Active Compensation System for Robot Vision in Rough Environment Based on Bionic Eye

    Jun Luo

    2011-12-01

    Full Text Available Motion targets tracking techniques is one of the most important aspects in the fields of mobile robot research under unknown environments. To solve the problem of unstable vision resulted from the uncertainties, a method of active compensation for robot visual was proposed based on the principle of bionic eye movements. According to oculomotor neural circuits, an adaptive oculomotor control model of eye movements was established, and the model includes that VOR, smooth purisuit and compound eye movements. In order to verify the model’s performance, some simulation experiments ware conducted in different environment. Simulation results show that the model can be active compensation of visual error caused by the dynamic variation of the robot attitude and the tracking target location. Finally, physical robot experiments results also confirm the effectiveness of the control model. Compared with the conventional camera, this new one can solve the problem of unstable vision.

  10. A High Power Density Integrated Charger for Electric Vehicles with Active Ripple Compensation

    Liwen Pan; Chengning Zhang

    2015-01-01

    This paper suggests a high power density on-board integrated charger with active ripple compensation circuit for electric vehicles. To obtain a high power density and high efficiency, silicon carbide devices are reported to meet the requirement of high-switching-frequency operation. An integrated bidirectional converter is proposed to function as AC/DC battery charger and to transfer energy between battery pack and motor drive of the traction system. In addition, the conventional H-bridge cir...

  11. Compensating active power imbalances in power system with large-scale wind power penetration

    Basit, Abdul; Anca Daniela HANSEN; Altin, Müfit; Sørensen, Poul Ejnar; Gamst, Mette

    2016-01-01

    Large-scale wind power penetration can affectthe supply continuity in the power system. This is a matterof high priority to investigate, as more regulating reservesand specified control strategies for generation control arerequired in the future power system with even more highwind power penetration. This paper evaluates the impact oflarge-scale wind power integration on future power systems.An active power balance control methodology is usedfor compensating the power imbalances between thede...

  12. Analysis of Generalized Non-Active Power Theory for Compensation of Non-Periodic Disturbances

    Tlustý, J.; Švec, J.; Sedra, J. B.; Valouch, Viktor

    Santiago de Compostela: EA4EPQ, 2012, s. 1-6. ISBN 978-84-615-6648-8. [International Conference on Renewable Energies and Power Quality (ICREPQ 12). Santiago de Compostela (ES), 28.03.2012-30.03.2012] Institutional research plan: CEZ:AV0Z20570509 Keywords : generalized non-active power theory * electric power system * parallel compensation Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  13. An Active Compensation System for Robot Vision in Rough Environment Based on Bionic Eye

    Jun Luo; Hengyu Li; Jinbo Chen; Chao Li; Shaorong Xie

    2011-01-01

    Motion targets tracking techniques is one of the most important aspects in the fields of mobile robot research under unknown environments. To solve the problem of unstable vision resulted from the uncertainties, a method of active compensation for robot visual was proposed based on the principle of bionic eye movements. According to oculomotor neural circuits, an adaptive oculomotor control model of eye movements was established, and the model includes that VOR, smooth purisuit and compound e...

  14. The Nature of Essential and Parkinsonian Tremors

    Gao, J. B.; Tung, Wen-wen

    2003-08-01

    Tremor denotes an involuntary, approximately rhythmic, and roughly sinusoidal movement of parts of the body. Pathological tremors result from disorders of the central nervous system and peripheral nervous system. In this paper we study the two most common pathological tremors, essential and Parkinsonian, using dynamical systems theory. We show that pathological tremors can be characterized as diffusional processes. The time scale range for the diffusional scaling law to be valid starts from about one to several tens of the mean oscillation period. This time scale range contrasts sharply with the predictable time scale for deterministic chaos, which is usually only a small fraction of the mean oscillation period. The mechanism for pathological tremors is also discussed, based on fractal and bifurcation theory.

  15. TYPES OF TREMOR IN PATIENTS WITH CEREBROVASCULAR DISEASES AND CARDIOVASCULAR EVENTS

    Petrov Igor

    2016-03-01

    Full Text Available Introduction: Tremor can occur as a part of the clinical feature of cerebrovascular diseases. Many patients with cerebral stroke have cardiovascular diseases as a comorbidity or complication of stroke; sometimes cardiovascular events can lead to embolic stroke. Aim: To present types of tremor in patients with cerebrovascular diseases and cardiovascular events and diabetes mellitus type 2, clinical characteristics of tremor and investigations used. Material and methods: In our study we included 36 patients, 24 men and 12 women, that were examined and followed for 3 years, from 2012-2015. All patients were subjected to the following investigations: neurological examination, laboratory analysis, computerized tomography of brain, magnetic resonance imaging and electroencephalography. In cardiovascular patients we also performed Doppler sonography of carotid arteries, electrocardiography, cardiac ultrasound. The patients were examined and treated by cardiologists. Results: Of all patients 22% had cerebral infarction, 41% atherosclerosis, 36% multiple lacunar infarctions and 28% diabetes mellitus type 2. Three patients with cerebral infarction had chorea, hemiballismus, dystonia and dystonic tremor, three had postural tremor and two cerebellar intention tremor. Atherosclerotic patients had atherosclerotic action tremor, while diabetic patients predominantly presented with action-type tremor. Electroencephalography showed irritative basic brain activity with slow waves, while carotid arteries stenosis was diagnosed by Doppler sonography. Computerized tomography of the brain and magnetic resonance imaging revealed cerebrovascular diseases in certain areas. Patients with cardiomyopathy, rhythm disorders, high blood pressure, hyperlipidemia was investigated and medically treated by a cardiologist. Conclusion: In cerebrovascular diseases different types of tremor can occur as the result of the damage of the extrapyramidal system.

  16. Beta-adrenergic modulation of tremor and corticomuscular coherence in humans.

    Mark R Baker

    Full Text Available Coherence between the bioelectric activity of sensorimotor cortex and contralateral muscles can be observed around 20 Hz. By contrast, physiological tremor has a dominant frequency around 10 Hz. Although tremor has multiple sources, it is partly central in origin, reflecting a component of motoneuron discharge at this frequency. The motoneuron response to ~20 Hz descending input could be altered by non-linear interactions with ~10 Hz motoneuron firing. We investigated this further in eight healthy human subjects by testing the effects of the beta-adrenergic agents propranolol (non-selective β-antagonist and salbutamol (β(2-agonist, which are known to alter the size of physiological tremor. Corticomuscular coherence was assessed during an auxotonic precision grip task; tremor was quantified using accelerometry during index finger extension. Experiments with propranolol used a double-blind, placebo-controlled crossover design. A single oral dose of propranolol (40 mg significantly increased beta band (15.3-32.2 Hz corticomuscular coherence compared with placebo, but reduced tremor in the 6.2-11.9 Hz range. Salbutamol (2.5 mg was administered by inhalation. Whilst salbutamol significantly increased tremor amplitude as expected, it did not change corticomuscular coherence. The opposite direction of the effects of propranolol on corticomuscular coherence and tremor, and the fact that salbutamol enhances tremor but does not affect coherence, implies that the magnitude of corticomuscular coherence is little influenced by non-linear interactions with 10 Hz oscillations in motoneurons or the periphery. Instead, we suggest that propranolol and salbutamol may affect both tremor and corticomuscular coherence partly via a central site of action.

  17. An interferometric calibration system for various linear artefacts using active compensation of angular motion errors

    A calibration system for linear-dimension artefacts was developed, which employed a multi-axis laser interferometer for direct metrological traceability and active compensation of angular motion errors. It can calibrate various end and line standards by changing probes (contact and optical probe). We designed the system as a moving probe type with a cantilever structure to reduce overall size and increase efficiency in calibration. A stage part including a two-axis tilt stage provides precise linear motion of a probing part over the range of 2000 mm with nanometric resolution. The three-axis interferometer measuring linear and rotational motions of the stage enables us to obtain probing position and compensate angular motion errors precisely. It was also arranged to minimize the Abbe offset, and so the Abbe error can be reduced remarkably combining the active compensation of angular motion errors. The overall system was installed in a temperature-controlled chamber to decrease thermal variation during measurements. The measurement uncertainty of the calibration system was analysed by considering the performance of the main components. We measured several long gauge blocks and a precision line scale, and compared the measured values with the reference ones and also checked their stabilities. Their deviations were less than 100 nm and existed within the expanded measurement uncertainty (k = 2)

  18. High Performance Current Controller for Selective Harmonic Compensation in Active Power Filters

    Lascu, Cristian; Asiminoaei, Lucian; Boldea, I.;

    2007-01-01

    A new current control scheme for selective harmonic compensation is proposed for shunt active power filters. The method employs an array of resonant current controllers, one for the fundamental, and one for each harmonic, implemented in fundamental reference frame in order to reduce the overall...... computational effort. The proposed controller design is based on the pole-zero cancellation technique, taking into account the load transfer function at each harmonic frequency. Two design methods are provided, which give controller transfer functions with superior frequency response. The complete current...... is supported by experimental results on a 7.6-kVA laboratory filter, indicating a reduction in current THD factor from 34% to 2%, while the highest harmonic compensated is the 37th harmonic current....

  19. Active compensation of the magnetic field surrounding a new nEDM apparatus

    Full text: A non-zero neutron electric dipole moment (nEDM) violates time and parity reversal symmetry. Its detection would be a major discovery, but also improving the current upper limit of 2.9.10-26 e.cm constrains theories beyond the Standard Model of Particle Physics, such as super-symmetry. An apparatus has been set up at the Paul Scherrer Institut (PSI) in order to improve the current sensitivity by one and a half orders of magnitude. This shall be achieved by increasing statistics with PSI's new powerful ultracold neutron source, and by an improved control on systematics. Of particular interest are changes of magnetic field inside the experimental volume. These are partly introduced from the environment and are actively compensated for by a surrounding field compensation (SFC) coil system. The currents in these coils are dynamically controlled by feedback algorithms. In this talk the performance of the SFC will be presented. (author)

  20. Study on a Mechanical Semi-Active Heave Compensation System of Drill String for Use on Floating Drilling Platform

    Liu, Qingyou; Tang, Yang; Huang, Chongjun; Xie, Chong

    2015-01-01

    There are some disadvantages for existing heave compensation systems of drill string used for the Floating Drilling Platform (FDP), including high energy consumption, large and complex structure, and expensive manufacturing and maintenance costs. In view of the above, we present a streamlined mechanical semi-active heave compensation system (MSAHC) in this study. This system consists of active compensation part with the pinion and rack and passive compensation part. In order to evaluate system performance of the MSAHC, we establish its simulation model with AMEsim software. In the process of simulation, displacement of rotary hook and energy consumption is regarded as performance parameters of the system. And the change rule of two performance parameters are analyzed by changing these design parameters including gear radius of the pinion and rack, scale coefficient of PID, rotary hook load, heave height and heave period of the FDP, and accumulator volume. Then, based on the simulation results of the MSAHC system performance, we have selected out a best set of design parameters from them. Moreover, the feasibility of the design scheme of the MSAHC is effectively verified by comparison with the existing three heave compensation system. The result shows that the energy consumption of the MSAHC is lower than the active heave compensation system (AHC) and the semi-active heave compensation system (SAHC) when achieving a same compensation effect as well as the accumulator volume of MSAHC is half of the passive heave compensation system (PHC). Therefore, the new designed MSAHC not only ensure compensation effect but also lower energy consumption, and its structure is simplified by adopting the simple mechanical structure to decrease manufacturing cost, maintenance cost and floor space. PMID:26186620

  1. Complex behavior and source model of the tremor at Arenal volcano, Costa Rica

    Lesage, Philippe; Mora, Mauricio M.; Alvarado, Guillermo E.; Pacheco, Javier; Métaxian, Jean-Philippe

    2006-09-01

    related to variations of the pressure in the conduit, which modify the gas fraction, the wave velocity and, possibly, the length of the resonator. Moreover, several observations suggest that two seismic sources, associated with two magmatic conduits, are active in Arenal volcano. They could explain in particular the apparent independence of tremor and explosions and the episodes of tremor displaying two simultaneous systems of spectral peaks.

  2. Electrophysiologic characteristics of tremor in Parkinson?s disease and essential tremor

    Ederson Cichaczewski

    2014-04-01

    Full Text Available Tremor in essential tremor (ET and Parkinson’s disease (PD usually present specific electrophysiologic profiles, however amplitude and frequency may have wide variations. Objective: To present the electrophysiologic findings in PD and ET. Method: Patients were assessed at rest, with posture and action. Seventeen patients with ET and 62 with PD were included. PD cases were clustered into three groups: predominant rest tremor; tremor with similar intensity at rest, posture and during kinetic task; and predominant kinetic tremor. Results: Patients with PD presented tremors with average frequency of 5.29±1.18 Hz at rest, 5.79±1.39 Hz with posture and 6.48±1.34 Hz with the kinetic task. Tremor in ET presented with an average frequency of 5.97±1.1 Hz at rest, 6.18±1 Hz with posture and 6.53±1.2 Hz with kinetic task. Seven (41.2% also showed rest tremor. Conclusion: The tremor analysis alone using the methodology described here, is not sufficient to differentiate tremor in ET and PD.

  3. Tremor

    ... the eye and may be heightened by strong emotion (such as anxiety or fear), physical exhaustion, hypoglycemia, hyperthyroidism, heavy metal poisoning, stimulants, alcohol withdrawal, caffeine, or fever. It can occur in ...

  4. Compensation for Adolescents’ School Mental Load by Physical Activity on Weekend Days

    Michal Kudláček

    2016-03-01

    Full Text Available Introduction and objective: Increasing mental load and inadequate stress management significantly affect the efficiency, success and safety of the educational/working process in adolescents. The objective of this study is to determine the extent that adolescents compensate for their school mental load by physical activity (PA on weekend days and, thus, to contribute to the objective measurement of mental load in natural working conditions. Methods: A cross-sectional study was conducted between September 2013 and April 2014. A set of different methods was employed—self-administered questionnaire (IPAQ-long questionnaire, objective measurements—pedometers, and accelerometers (ActiTrainers. They was distributed to 548 students from 17 high schools. Participants’ mental load was assessed based on the difference between PA intensity and/or physical inactivity and heart rate range. Results: The participants with the highest mental load during school lessons do not compensate for this load by PA on weekend days. Conclusions: Adolescents need to be encouraged to be aware of their subjective mental load and to intentionally compensate for this load by PA on weekend days. It is necessary to support the process of adopting habits by sufficient physical literacy of students, as well as teachers, and by changes in the school program.

  5. Migrating tremor off southern Kyushu as evidence for slow slip of a shallow subduction interface

    Yamashita, Y.; Yakiwara, H.; Asano, Y.; Shimizu, H.; Uchida, K.; Hirano, S.; Umakoshi, K.; Miyamachi, H.; Nakamoto, M.; Fukui, M.; Kamizono, M.; Kanehara, H.; Yamada, T.; Shinohara, M.; Obara, K.

    2015-05-01

    Detection of shallow slow earthquakes offers insight into the near-trench part of the subduction interface, an important region in the development of great earthquake ruptures and tsunami generation. Ocean-bottom monitoring of offshore seismicity off southern Kyushu, Japan, recorded a complete episode of low-frequency tremor, lasting for 1 month, that was associated with very-low-frequency earthquake (VLFE) activity in the shallow plate interface. The shallow tremor episode exhibited two migration modes reminiscent of deep tremor down-dip of the seismogenic zone in some other subduction zones: a large-scale slower propagation mode and a rapid reversal mode. These similarities in migration properties and the association with VLFEs strongly suggest that both the shallow and deep tremor and VLFE may be triggered by the migration of episodic slow slip events.

  6. Geophysics. Migrating tremor off southern Kyushu as evidence for slow slip of a shallow subduction interface.

    Yamashita, Y; Yakiwara, H; Asano, Y; Shimizu, H; Uchida, K; Hirano, S; Umakoshi, K; Miyamachi, H; Nakamoto, M; Fukui, M; Kamizono, M; Kanehara, H; Yamada, T; Shinohara, M; Obara, K

    2015-05-01

    Detection of shallow slow earthquakes offers insight into the near-trench part of the subduction interface, an important region in the development of great earthquake ruptures and tsunami generation. Ocean-bottom monitoring of offshore seismicity off southern Kyushu, Japan, recorded a complete episode of low-frequency tremor, lasting for 1 month, that was associated with very-low-frequency earthquake (VLFE) activity in the shallow plate interface. The shallow tremor episode exhibited two migration modes reminiscent of deep tremor down-dip of the seismogenic zone in some other subduction zones: a large-scale slower propagation mode and a rapid reversal mode. These similarities in migration properties and the association with VLFEs strongly suggest that both the shallow and deep tremor and VLFE may be triggered by the migration of episodic slow slip events. PMID:25954006

  7. Model of deep non-volcanic tremor part II: episodic tremor and slip

    Gershenzon, Naum I

    2014-01-01

    Bursts of tremor accompany a moving slip pulse in Episodic Tremor and Slip (ETS) events. The sources of this non-volcanic tremor (NVT) are largely unknown. We have developed a model describing the mechanism of NTV generation. According to this model, NTV is a reflection of resonant-type oscillations excited in a fault at certain depth ranges. From a mathematical viewpoint, tremor (phonons) and slip pulses (solitons) are two different solutions of the sine-Gordon equation describing frictional processes inside a fault. In an ETS event, a moving slip pulse generates tremor due to interaction with structural heterogeneities in a fault and to failures of small asperities. Observed tremor parameters, such as central frequency and frequency attenuation curve, are associated with fault parameters and conditions, such as elastic modulus, effective normal stress, penetration hardness and friction. Model prediction of NTV frequency content is consistent with observations. In the framework of this model it is possible t...

  8. Quantification of a Secondary Task-Specific Tremor in a Violinist after a Temporal Lobectomy

    André eLee

    2014-07-01

    Full Text Available Task-specific tremors occur mainly during certain tasks and may be highly disabling. In this case study, we report on a 66-year-old violinist who developed a task-specific tremor of the right arm only while playing the violin four weeks after a temporal lobectomy, which had been performed as a result of his temporal lobe epilepsy. Since a similar case, to our knowledge, has not been reported so far, our aim was to quantitatively assess and describe the tremor by measuring (a the electromyography (EMG activity of the wrist flexor and extensor as well as (b an accelerometer signal of the hand. We found a tremor-related frequency of about 7 Hz. Furthermore, at a similar frequency of about 7 Hz, there was coherence between the tremor acceleration and EMG-activity of the wrist flexor and extensor as well as between the tremor acceleration and coactivation. The tremorgenesis remains unclear, and possible explanations can only be speculative.

  9. Modeling, simulation and design optimization of a hoisting rig active heave compensation system

    Gu, Peter; Walid, Ahmed Ahmed; Iskandarani, Yousef; Karimi, Hamid Reza

    2013-01-01

    The objective of this paper is to present an approach in developing a virtual active heave compensation system for a draw-works on a hoisting rig. A virtual system enables quicker overall product development time of a physical system as well as flexibility in optimizing the design parameters. Development of the virtual system started with the modelling of the draw-works and hoisting rig dynamics. Simulations of this model were run in two operational modes while subject to a sinusoidal wave: h...

  10. EVALUATING DEGREE OF ACTIVE POWER LOSSES REDUCTION IN THE ELECTRIC POWER LINES WITH REACTIVE POWER COMPENSATION

    V. N. Radkevich

    2016-01-01

    Full Text Available The paper considers evaluation procedure for the degree of active power losses reduction in the power transmission lines under 1 kV and 6–10 kV of the systems of electric power supply of industrial enterprises with compensating installations mounted at the side of the customer. The capacitor installations conform to the applied voltage level and factor in dielectric losses in the capacitors. The voltage at the compensating device terminal changes from 0.95 to 1.05 of the capacitors nominal voltage. The study did not account for reactive power losses in the line, nor did it for its charge capacity, conditioned by relative shortness of the cable lines generally operating in the mains of industrial enterprises. For this reason, the quantities of reactive power being consumed and generated by the transmission line are negligible and do not significantly affect the reactive power flux. The researchers obtain functional relations that allow estimating the degree of power loss reduction in the transmission line factoring in its explicit initial data. They perform mathematical analysis of the obtained functional relations and study the function by means of derivatives. The function extremum points are found as well as the intervals of its increment and decrement. A graphical research of the obtained functional relation is performed. It is ascertained that reduction of the active power losses is contingent on the line and the capacitor-installation engineering factors, the electrical energy consumer reactive load value as well as the voltage applied to the capacitor installation. The functional relations presented in the article can be employed in scoping calculation necessary for decision making on the reactive power compensation in systems of the industrial facilities electric power supply. Their account will allow a more accurate estimate of technical and economic effect of the capacitor bank installation in the electrical mains under 1 kV and 6

  11. Essential Tremor as a Neuropsychiatric Disorder

    Louis, Elan D.

    2009-01-01

    The traditional view of essential (ET) tremor is as a mono-symptomatic condition characterized by action tremor. Over the past decade, researchers have learned that this picture is an over-simplification. First, it is clear that many patients also have other motor manifestations (e.g., ataxic gait). Second, the presence of a variety of non-motor features, both cognitive and psychiatric, is now appreciated. Mild cognitive changes (esp. executive dysfunction) have been documented in several stu...

  12. Slow earthquakes and low frequency tremor along the Apennines, Italy

    F. Tronca

    2008-06-01

    Full Text Available This paper reviews the main observations on slow earthquakes and low frequency tremor made along the Apennines, the main seismic active zone of Italy. These observations have been made using a geodetic interferometer system operating since 1994 in the underground tunnel of Gran Sasso, central Italy, and an underground seismic array (UNDERSEIS operating since 2002 in the same environment. The observations made in recent years indicate that both phenomena are quite rare and apparently uncorrelated. Slow earthquakes, mainly recorded in 1997 and occasionally later, have probably been caused by the activity of a shallow fault system located near the interferometers. Until now only one tremor episode characterized by low frequency content and duration of several hours has been detected in January 2004, without any correlations with the occurrence of slow or regular earthquakes. The signal to noise ratio of this event is very low, but the results of our detailed analysis show that its frequency contents and wave field characteristics are compatible with a low frequency non volcanic tremor.

  13. Electrophysiologic Assessments of Involuntary Movements: Tremor and Myoclonus

    Hyun-Dong Park

    2009-05-01

    Full Text Available Tremor is defined as a rhythmical, involuntary oscillatory movement of a body part. Although neurological examination reveals information regarding its frequency, regularity, amplitude, and activation conditions, the electrophysiological investigations help in confirming the tremor, in differentiating it from other hyperkinetic disorders like myoclonus, and may provide etiological clues. Accelerometer with surface electromyogram (EMG can be used to document the dominant frequency of a tremor, which may be useful as certain frequencies are more characteristic of specific etiologies than others hyperkinetic disorders. It may show rhythmic bursts, duration and activation pattern (alternating or synchronous. Myoclonus is a quick, involuntary movement. Electrophysiological studies may helpful in the evaluation of myoclonus, not only for confirming the clinical diagnosis but also for understanding the underlying physiological mechanisms. Electroencephalogram (EEG-EMG correlates can give us important information about myoclonus. Jerk-locked back-averaging and evoked potentials with recording of the long-latency, long-loop reflexes are currently available to study the pathophysiology of myoclonus.

  14. Triggered creep as a possible mechanism for delayed dynamic triggering of tremor and earthquakes

    Shelly, D.R.; Peng, Z.; Hill, D.P.; Aiken, C.

    2011-01-01

    The passage of radiating seismic waves generates transient stresses in the Earth's crust that can trigger slip on faults far away from the original earthquake source. The triggered fault slip is detectable in the form of earthquakes and seismic tremor. However, the significance of these triggered events remains controversial, in part because they often occur with some delay, long after the triggering stress has passed. Here we scrutinize the location and timing of tremor on the San Andreas fault between 2001 and 2010 in relation to distant earthquakes. We observe tremor on the San Andreas fault that is initiated by passing seismic waves, yet migrates along the fault at a much slower velocity than the radiating seismic waves. We suggest that the migrating tremor records triggered slow slip of the San Andreas fault as a propagating creep event. We find that the triggered tremor and fault creep can be initiated by distant earthquakes as small as magnitude 5.4 and can persist for several days after the seismic waves have passed. Our observations of prolonged tremor activity provide a clear example of the delayed dynamic triggering of seismic events. Fault creep has been shown to trigger earthquakes, and we therefore suggest that the dynamic triggering of prolonged fault creep could provide a mechanism for the delayed triggering of earthquakes. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  15. Effect of mental fatigue on induced tremor in human knee extensors.

    Budini, Francesco; Lowery, Madeleine; Durbaba, Rade; De Vito, Giuseppe

    2014-06-01

    In this study, the effects of mental fatigue on mechanically induced tremor at both a low (3-6Hz) and high (8-12Hz) frequency were investigated. The two distinct tremor frequencies were evoked using two springs of different stiffness, during 20s sustained contractions of the knee extensor muscles at 30% maximum voluntary contraction (MVC) before and after 100min of a mental fatigue task, in 12 healthy (29±3.7years) participants. Mental fatigue resulted in a 6.9% decrease in MVC and in a 9.4% decrease in the amplitude of the agonist muscle EMG during sustained 30% MVC contractions in the induced high frequency only. Following the mental fatigue task, the coefficient of variation and standard deviation of the force signal decreased at 8-12Hz induced tremor by 31.7% and 35.2% respectively, but not at 3-6Hz induced tremor. Similarly, the maximum value and area underneath the peak in the power spectrum of the force signal decreased by 55.5% and 53.1% respectively in the 8-12Hz range only. In conclusion, mental fatigue decreased mechanically induced 8-12Hz tremor and had no effect on induced 3-6Hz tremor. We suggest that the reduction could be attributed to the decreased activation of the agonist muscles. PMID:24613661

  16. Deep Tectonic Tremor in Haiti triggered by the 2010/02/27 Mw8.8 Maule, Chile earthquake

    Aiken, C.; Peng, Z.; Douilly, R.; Calais, E.; Deschamps, A.; Haase, J. S.

    2013-05-01

    Tectonic tremors have been observed along major plate-boundary faults around the world. In most of these regions, tremors occur spontaneously (i.e. ambient) or as a result of small stress perturbations from passing surface waves (i.e. triggered). Because tremors are located below the seismogenic zone, a detailed study of their behavior could help to better understand how tectonic movement is accommodated in the deep root of major faults, and the relationship with large earthquakes. Here, we present evidence of triggered tremor in southern Haiti around the aftershock zone of the 2010/01/12 Mw7.0 Haiti earthquake. Following the January mainshock, several groups have installed land and ocean bottom seismometers to record aftershock activity (e.g., De Lepinay et al., 2011). In the following month, the 2010/02/27 Mw8.8 Maule, Chile earthquake occurred and was recorded in the southern Haiti region by these seismic stations. We apply a 5-15 Hz band-pass filter to all seismograms to identify local high-frequency signals during the Chile teleseismic waves. Tremor is identified as non-impulsive bursts with 10-20 s durations that is coherent among different stations and is modulated by surface waves. We also convert the seismic data into audible sounds and use them to distinguish between local aftershocks and deep tremor. We locate the source of the tremor bursts using an envelope cross-correlation method based on travel time differences. Because tremor depth is not well constrained with this method, we set it to 20 km, close to the recent estimate of Moho depth in this region (McNamara et al., 2012). Most tremors are located south of the surface expression of the Enriquillo-Plantain Garden Fault (EPGF), a high-angle southward dipping left-lateral strike-slip fault that marks the boundary between the Gonave microplate and the Caribbean plate, although the location errors are large. Tremor peaks are mostly modulated by Love wave velocity, which is consistent with left

  17. Physiological tremor and control of limb position in 1 and 0 G.

    Gallasch, E; Rafolt, D; Kenner, T; Konev, A; Kozlovskaya, I B

    1994-05-01

    Muscle and skeletal mechanoreceptors play an important role for the regulation of muscular tone and the genesis of normal Physiological Tremor (PT). For example if a big limb as the arm or leg is kept against the gravity vector, the la afferent spindle discharges continuously control the load bearing flexor in a negative feedback manner in order to compensate the gravity vector and to the stabilize arm position. This servo-like action, denoted as 'stretch reflex', not only increases static postural stability (tonic stretch reflex) but also counteracts against external disturbances by dynamically increasing the muscle tone. Muscle spindles are very sophisticated sensory organs. They have an own innervation and the endings of the nuclear bag fibres are highly sensitive for small microstretches. EMG and microneurografic studies showed their importance in the mechanism of the 8-12 Hz component for PT. In a 0 G a limb becomes position controlled. In contrast to 1g, where control of limb position is a subordinated function of force compensation in the load bearing muscle, an antagonistic control scheme is necessary in 0 G to compensate the arm against positional drifts. As a consequence there is a shift from load dependent (muscular) to position dependent (skeletal) mechanoreceptors that become involved in the neural control process. As the control process is reflected in the tremor pattern, we investigated arm tremor in a constant limb position in 1 and 0 G. PMID:11538761

  18. Model of deep non-volcanic tremor part I: ambient and triggered tremor

    Gershenzon, Naum I

    2013-01-01

    There is evidence of triggering of tremor by seismic waves emanating from distant large earthquakes. The frequency contents of triggered and ambient tremor are largely identical, suggesting that tremor does not depend directly on the nature of the source. We show here that the model of plate dynamics developed earlier by us is an appropriate tool for describing the onset of tremor. In the framework of this model, tremor is an internal response of a fault to a failure triggered by external disturbances. The model predicts generation of radiation in a frequency range defined by the fault parameters. Other specific features predicted are: the upper limit of the size of the emitting area is a few dozen km; tremor accompanies earthquakes and aseismic slip; the frequency content of tremor depends on the type of failure. The model also explains why a tremor has no clear impulsive phase, in contrast to earthquakes. A comparatively small effective normal stress (hence a high fluid pressure) is required to make the mod...

  19. Active and recreative power control in the presence of types of static VAR compensators (SVC)

    Tobnaghi, Davoud Mostafa [Department of Electrical Engineering, Parsabad Moghan Branch, Islamic Azad University (Iran, Islamic Republic of)], email: dmostafa@iaupmogan.ac.ir; Najafi, Atabak; Sadeghi Nasrabadi, Jafar [Department of Electrical Engineering, Germi Branch, Islamic Azad University (Iran, Islamic Republic of)], email: Jafarsadegi64@gmail.com, email: atabak_najafi@yahoo.com; Karimi, Mohammad; Farhadi, Payam [Department of Electrical Engineering, Parsabad Moghan Branch, Islamic Azad University (Iran, Islamic Republic of)], email: mohammadkarimi62@gmail.com, email: pfarhadi@iaupmogan.ac.ir

    2011-07-01

    This paper investigates the effects of various types of Static Var Compensators, a particular sort of FACTS (Flexible AC Transmission System), on active and reactive power flow control with the purpose of increasing the capacity of existing electrical transmission systems rather than having to build new ones. The prime reasons are both economic and environmental: deregulation in the electrical market increases the need to be competitive while ensuring security and operating within various physical limitations related to thermal capacity and stability of voltage in transmission lines. The development of high power semiconductor devices makes it now possible to use these in power systems. After an overall review of SVCs, six were selected, analysed, and classified in order from lowest to highest power flow control range. It was also concluded that with the use of SVCs there is more fluctuation in reactive power control and almost no oscillation in active power control.

  20. Ambient Tremor Triggered by the 24 August 2014, M6.0 South Napa Earthquake in the Parkfield-Cholame region of California

    Nadeau, R. M.

    2014-12-01

    The rate of ambient tremor activity in the Parkfield-Cholame area of California increased by a factor of ~10 beginning between 11 and 12 hours after August 24, 2014 M6.0 S. Napa earthquake and lasted for ~ 48 hours. Over the subsequent 26 days, rates diminished but remained elevated, and on Sept. 22, 2014, rates increased again to levels comparable to those immediately following the South Napa event. This second episode has continued through the end of the analysis period (Sept. 24). The proportion of tremors beneath Monarch Peak (NW of Parkfield-Cholame) also increased during this second episode, suggesting a migration of tremor deep slow-slip to the northwest. The rate of tremor since the Napa earthquake is the largest observed in the Parkfield-Cholame area since the ambient tremor triggered by the 2004 Parkfield M6 earthquake and is approximately as energetic. This is in spite of the fact that the South Napa earthquake was over 300 km further away from the Parkfield-Cholame tremor zone. This suggests a heightened sensitivity to stress change in the Parkfield-Cholame tremor zone and that significant changes in conditions within the deep SAF may have taken place. The increased rates of tremor and the general association of changing tremor rates with deformational transients and slow-slip also suggest that the South Napa event may have triggered a large, deep slow-slip episode at a great distance and along a critical section of the San Andreas Fault (i.e., where the 1857 Ft. Tejon M7.8 earthquake apparently nucleated). This presentation will include monitoring results tracking the ongoing unusual tremor activity up through the week prior to the Fall AGU meeting and will compare this tremor evolution with ongoing seismicity and another delayed ambient tremor episode in the Bitterwater area of the SAF that was apparently triggered by the 1998 San Juan Baustista M5.1 earthquake.

  1. Migration Episode of Shallow Low-frequency Tremor at the Nankai Trough Subduction Zone: Seismological Evidence for Episodic Slow Slip Event Occurring at the Shallow Transition Zone

    Yamashita, Y.; Yakiwara, H.; Shimizu, H.; Uchida, K.; Hirano, S.; Miyamachi, H.; Umakoshi, K.; Nakamoto, M.; Fukui, M.; Kamizono, M.; Kanehara, H.; Yamada, T.; Shinohara, M.; Obara, K.

    2014-12-01

    To understand the shallow part of plate interface between megathrust seismogenic zone and trench axis is very important for development of huge earthquake rupture and generation of tsunami. Monitoring of offshore seismicity near the Nankai trough by temporal ocean bottom seismographic observation in 2013 revealed that low-frequency tremor occurred associated with shallow very-low-frequency earthquakes (VLFEs) in the shallow part of plate interface. The shallow tremor episode lasted for approximately 1 month, which is almost consistent with the shallow VLFE activity observed from land broad-band seismic stations [Asano, 2014]. The horizontal location of shallow tremor estimate by envelope correlation method [Obara, 2002] shows a belt-like distribution along trench strike with narrow width than the deep tremor. The most remarkable feature of the shallow tremor activity is migration. There are two migration modes including diffusive slower migration and rapid tremor reversal (RTR), which are very similar to the deep tremor as a part of the ETS. This strongly indicates a possibility of the occurrence of episodic slow slip event in the shallow transition zone. That is to say, the migration of shallow tremor is supposed to be caused by migrating rupture front of SSE. In addition, the migration was detouring around the subducted Kyushu-Palau ridge. This suggests that the occurrence of tremor is sensitive to change in the shape of plate interface and seeks to propagate along almost the same depth range, in other word, a specified temperature and pressure condition. The narrow width distribution of shallow tremor also indicates that the shallow tremor is strongly related to dehydration process of a specified mineral under a narrow limited range of temperature and pressure condition compared to the deep tremor.

  2. Environmental Epidemiology of Essential Tremor

    Louis, Elan D.

    2008-01-01

    Background Essential tremor (ET) is one of the most common neurological disorders. Despite this, the disease mechanisms and etiology are not well understood. While susceptibility genotypes undoubtedly underlie many ET cases, no ET genes have been identified thus far. As with many other progressive, degenerative neurological disorders, it is likely that environmental factors contribute to the etiology of ET. Environmental epidemiology is the study in specific populations or communities of the effect on human health of physical, biologic and chemical factors in the external environment. The purpose of this article is to review current knowledge with regards to the environmental epidemiology of ET. Results As will be discussed, a series of preliminary case-control studies in recent years has begun to explore several candidate toxins/exposures, including harmane (1-methyl-9H-pyrido[3,4-b]indole), lead and agricultural exposures/pesticides. Conclusions While several initial results are promising, as will be discussed, additional studies are needed to more definitively establish whether these exposures are associated with ET and if they are of etiological importance. PMID:18716411

  3. Intention tremor after head injury

    Eight cases of intention tremor as a late complication of head injury were investigated. The patients ranged in age from 3 to 24 years. All received severe head injuries and lapsed into coma immediately afterward (Glasgow Coma Scale scores ≤8). Six patients exhibited decerebration or decortication. Hemiparesis was present in six cases and oculomotor nerve palsy in four. In the chronic stage, all patients displayed some degree of impairment of higher cortical function and five had dysarthria and/or ataxia. Initial computed tomography (CT) scans within 3 hours after the injury were obtained in five cases, of which four showed a hemorrhagic lesion in the midbrain or its surroundings. Other CT findings were diffuse cerebral swelling (four cases), intraventricular hemorrhage (three), and multiple hemorrhagic lesions (two). In the chronic stage, generalized cortical atrophy or ventricular enlargement was noted in five cases. These clinical features and CT findings indicate diffuse brain damage as well as midbrain damage and may reflect shearing injury. (author)

  4. Design of an active magnetic field compensation system for MiniCLEAN

    MiniCLEANis a single-phase noble liquid scintillator experiment designed to detect nuclear recoils due to weakly interacting massive particles hypothesized to constitute the dark matter. The principle of the detector is to monitor scintillation light resulting from ionizing radiation using 92 photomultiplier tubes surrounding a spherical target. Photomultiplier tube response is known to be affected by sub-Gauss magnetic fields, so that the Earth's magnetic field has a non-negligible effect on the photomultiplier tube efficiency. In this experiment, the crucial nuclear recoil energy threshold depends on the ability to detect very small amounts of scintillation light; high photomultiplier tube efficiency is critical. Therefore, the MiniCLEAN collaboration has designed active compensation coils to mitigate the Earth's local magnetic field. Two features of the experimental environment make this situation unique: first, the underground laboratory (SNOLAB) is located in a nickel mine, so that direct measurement of the potentially distorted geomagnetic field is mandatory. Second, the close proximity of another experiment based on photomultiplier tubes (DEAP-3600) makes the compensating field outside our detector a concern. An additional complication is that MiniCLEANis surrounded by a steel water tank needed for shielding and a muon veto composed of four strings of 12 photomultipliers suspended in the water. We describe our design based on these considerations, survey data, field calculations and simulations of the photomultiplier tube response.

  5. Active compensation of the magnetic field surrounding a new nEDM apparatus

    A non-zero neutron electric dipole moment (nEDM) would violate time and parity reversal symmetry. Its detection would be a major discovery, but also improving the current upper limit of 2.9.10-26 e.cm constrains theories beyond the Standard Model of Particle Physics, such as supersymmetry. An apparatus is being set up at the Paul Scherrer Institut in Switzerland in order to improve the current sensitivity by two orders of magnitude. This shall be achieved by increasing statistics with a new powerful ultracold neutron source, and by improving control on systematics. The main sources for systematic errors are fluctuations of magnetic field inside the experimental volume. These might be introduced from the environment and shall be actively compensated for by implementing a surrounding field compensation (SFC) coil system. In this talk the working principle of the SFC and its commissioning are presented. First results on the investigation of the magnetic environment of the experiment and the effect of the SFC on it are included.

  6. Characterization of a Tremor Patch Downdip from Earthquakes in the Central Oregon Locked Zone

    Williams, M. C.; Trehu, A. M.

    2009-12-01

    Episodic tremor and slip (ETS) was first detected in northern Cascadia in 2001, and has since been observed along the entire margin of the subduction zone. However, the spatial behavior and recurrence patterns of these episodes vary along strike. During periods of tremor and slip, there is a distinct “patch” of tremor occurring near Alsea, OR, between 44N and 45N. This patch is located directly downdip from a series of earthquakes which occurred at the plate boundary in the nominally locked part of the subduction zone from 2003-2008. This patch is of interest due to its along-strike spatial correlation with this recent seismicity and with a number of structural changes in the forearc. The tremor patch occurs within the amphibious Central Oregon Locked Zone Array (COLZA), deployed from 2007-2009 to observe offshore seismicity. COLZA includes instruments from EarthScope’s USArray-FA as well as ocean bottom seismometers from the OBSIP. With seismic waveforms from COLZA and Pacific Northwest regional stations, we located individual tremor arrivals during the 2008 episode on this patch, using a 1-sec power envelope of the tremor signal, in a 2-9 Hz passband. We manually identified peaks in the tremor, and produced event arrival times relative to station ALS0 based on time lags from cross-correlation, requiring a clear correlation of 0.7 or greater. These pseudo-events were then located using genloc (a user-contributed Antelope generalized inverse location program), assuming S-wave velocities. Some tremor occurrences are located (with RMS station near Alsea, OR, indicating the patch is tightly clustered underneath or adjacent to ALS0. We will compare the activity on this tremor patch in time and space to ETS along the rest of the margin as well as to the occurrence time of low-angle thrust earthquakes updip from the tremor on the plate boundary. We will also present an updated velocity model to better constrain topography of the subducted plate and the relationship

  7. Active Head Motion Compensation of TMS Robotic System Using Neuro-Fuzzy Estimation

    Wan Zakaria W.N.

    2016-01-01

    Full Text Available Transcranial Magnetic Stimulation (TMS allows neuroscientist to study human brain behaviour and also become an important technique for changing the activity of brain neurons and the functions they sub serve. However, conventional manual procedure and robotized TMS are currently unable to precisely position the TMS coil because of unconstrained subject’s head movement and excessive contact force between the coil and subject’s head. This paper addressed this challenge by proposing an adaptive neuro-fuzzy force control to enable low contact force with a moving target surface. A learning and adaption mechanism is included in the control scheme to improve position disturbance estimation. The results show the ability of the proposed force control scheme to compensate subject’s head motions while maintaining desired contact force, thus allowing for more accurate and repeatable TMS procedures.

  8. The 2011 unrest at Katla volcano: characterization and interpretation of the tremor sources

    Sgattoni, Giulia; Einarsson, Páll; Lucchi, Federico; Li, Ka Lok; Sadeghisorkhani, Hamzeh; Roberts, Roland; Tryggvason, Ari

    2016-01-01

    A 23 hour tremor burst was recorded on July 8-9th 2011 at the Katla subglacial volcano, one of the most active and hazardous volcanoes in Iceland. This was associated with deepening of cauldrons on the ice cap and a glacial flood that caused damage to infrastructure. Increased earthquake activity within the caldera started a few days before and lasted for months afterwards and new seismic activity started on the south flank. No visible eruption broke the ice and the question arose as to whether this episode relates to a minor subglacial eruption with the tremor being generated by volcanic processes, or by the flood. The tremor signal consisted of bursts with varying amplitude and duration. We have identified and described three different tremor phases, based on amplitude and frequency features. A tremor phase associated with the flood was recorded only at stations closest to the river that flooded, correlating in time with rising water level observed at gauging stations. Using back-projection of double cross-...

  9. Fragile X-Associated Tremor and Ataxia Syndrome (FXTAS)

    ... Resources and Publications Fragile X-Associated Tremor and Ataxia Syndrome (FXTAS): Overview Skip sharing on social media ... this: Page Content Fragile X-associated tremor and ataxia syndrome (FXTAS) is a late-onset condition (occurs ...

  10. Tremor da escrita: relato de caso

    Denise Hack Nicaretta

    1994-03-01

    Full Text Available O tremor da escrita é distúrbio precipitado por atividade motora específica, geralmente a escrita. Analisamos este caso sob o ponto de vista clínico e terapêutico. O paciente apresentava tremor ao escrever tomando sua letra ilegível; sem qualquer outra alteração neurológica. Não havia antecedentes familiares, metabólicos, endócrinos, iatrogênicos, tóxicos ou traumáticos. No manuseio terapêutico não ocorreu resposta satisfatória ao propranolol, sendo discreta à primidona. A introdução de anticolinérgicos (tri-hexifenidil evidenciou certa melhora na sintomatologia, com redução do tremor no momento da escrita.

  11. Improvement of the matrix effect compensation in active neutron measurement by simulated annealing algorithm (June 2009)

    Active neutron measurements such as the Differential Die-Away (DDA) technique involving pulsed neutron generator, are widely applied to determine the fissile content of waste packages. Unfortunately, the main drawback of such techniques is coming from the lack of knowledge of the waste matrix composition. Thus, the matrix effect correction for the DDA measurement is an essential improvement in the field of fissile material content determination. Different solutions have been developed to compensate the effect of the matrix on the neutron measurement interpretation. In this context, this paper describes an innovative matrix correction method we have developed with the goal of increasing the accuracy of the matrix effect correction and reducing the measurement time. The implementation of this method is based on the analysis of the raw signal with an optimisation algorithm called the simulated annealing algorithm. This algorithm needs a reference data base of Multi-Channel Scaling (MCS) spectra, to fit the raw signal. The construction of the MCS library involves a learning phase to define and acquire the DDA signals. This database has been provided by a set of active signals from experimental matrices (mock-up waste drums of 118 litres) recorded in a specific device dedicated to neutron measurement research and development of the Nuclear Measurement Laboratory of CEA-Cadarache, called PROMETHEE 6. The simulated annealing algorithm is applied to make use of the effect of the matrices on the total active signal of DDA measurement. Furthermore, as this algorithm is directly applied to the raw active signal, it is very useful when active background contributions can not be easily estimated and removed. Most of the cases tested during this work which represents the feasibility phase of the method, are within a 4% agreement interval with the expected experimental value. Moreover, one can notice that without any compensation of the matrix effect, the classical DDA prompt

  12. Correlation between essential tremor and migraine headache.

    Biary, N; Koller, W; Langenberg, P

    1990-01-01

    The relationship between essential tremor (ET) and migraine was investigated in a prospective study. In a group of 74 ET patients 36.5% had migraine compared with 17.7% of 102 control subjects without tremor. In a group of 58 patients with migraine 17.2% had ET compared with 1.2% of 85 controls without migraine. The prevalence of ET in migraine controls was greater than controls without migraine (22% compared with 1%; p = 0.002). It is concluded that there is an association between essential ...

  13. New hybrid active power filter for harmonic current suppression and reactive power compensation

    Biricik, Samet; Cemal Ozerdem, Ozgur; Redif, Soydan; Sezai Dincer, Mustafa

    2016-08-01

    In the case of undistorted and balanced grid voltages, low ratio shunt active power filters (APFs) can give unity power factors and achieve current harmonic cancellation. However, this is not possible when source voltages are distorted and unbalanced. In this study, the cost-effective hybrid active power filter (HAPF) topology for satisfying the requirements of harmonic current suppression and non-active power compensation for industry is presented. An effective strategy is developed to observe the effect of the placement of power capacitors and LC filters with the shunt APF. A new method for alleviating the negative effects of a nonideal grid voltage is proposed that uses a self-tuning filter algorithm with instantaneous reactive power theory. The real-time control of the studied system was achieved with a field-programmable gate array (FPGA) architecture, which was developed using the OPAL-RT system. The performance result of the proposed HAPF system is tested and presented under nonideal supply voltage conditions.

  14. Slow slip event within a gap between tremor and locked zones in the Nankai subduction zone

    Takagi, Ryota; Obara, Kazushige; Maeda, Takuto

    2016-02-01

    We report on two small long-term slow slip events (SSEs) within a gap between tremor and locked zones in the Nankai subduction zone, southwest Japan. The SSEs were detected by subtracting the steady state component and postseismic effects of large earthquakes from long-term and high-density Global Navigation Satellite System data. Both SSEs occurred in adjacent regions of the Bungo channel following long-term SSEs in the Bungo channel in 2003 and 2010. The estimated slip was 1-5 cm/year that lasted at least 1-2 years after 2004 and 2011, partly accommodating plate convergence. As the low-frequency tremor in the downdip region is activated at the same time as the Bungo channel long-term SSE, a spatiotemporal correlation was observed between the detected SSEs and long-term tremor activity in the downdip region. This correlation indicates along-dip interaction of the slips on the subducting plate interface.

  15. Unilateral rubral tremors in Wilson′s disease treated with dimercaprol

    Rahul T Chakor

    2015-01-01

    Full Text Available Tremors are reported as the most frequent neurological manifestation of Wilson′s disease (WD in some series. Postural tremors, rest tremors, action tremors and wing-beating (rubral tremors are the different types of tremors seen in WD. We report a patient of WD with unilateral rubral tremors refractory to 1-year therapy with Penicillamine and anti-tremor medications. The tremors decreased considerably after adding chelation therapy with dimercaprol. Combination of Penicillamine and dimercaprol is an effective decoppering measure in rubral tremors of WD.

  16. Ambient Tremor, But No Triggered Tremor at the Northern Costa Rica Subduction Zone

    Swiecki, Z.; Schwartz, S. Y.

    2010-12-01

    Non-volcanic tremor (NVT) has been found to be triggered during the passage of surface waves from various teleseismic events in locations around the world including Cascadia, Southwest Japan, Taiwan, and California. In this study we examine the northern Costa Rica subduction zone for evidence of triggered tremor. The Nicoya Peninsula segment of the northern Costa Rica margin experiences both slow-slip and tremor and is thus a prime candidate for triggered tremor observations. Eleven teleseismic events with magnitudes (Mw) greater than 8 occurring between 2006 and 2010 were examined using data from both broadband and short period sensors deployed on the Nicoya Peninsula, Costa Rica. Waveforms from several large regional events were also considered. The largest teleseismic and regional events (27 February 2010 Chile, Mw 8.8 and 28 May 2009 Honduras, Mw 7.3) induced peak ground velocities (PGV) at the NIcoya stations of ~2 and 6 mm/s, respectively; larger than PGVs in other locations that have triggered tremor. Many of the earthquakes examined occurred during small episodes of background ambient tremor. In spite of this, no triggered tremor was observed during the passage of seismic waves from any event. This is significant because other studies have demonstrated that NVT is not triggered everywhere by all events above some threshold magnitude, indicating that unique conditions are required for its occurrence. The lack of triggered tremor at the Costa Rica margin can help to better quantify the requisite conditions and triggering mechanisms. An inherent difference between the Costa Rica margin and the other subduction zones where triggered tremor exists is its erosional rather than accretionary nature. Its relatively low sediment supply likely results in a drier, lower pore fluid pressure, stronger and less compliant thrust interface that is less receptive to triggering tremor from external stresses generated by teleseismic or strong local earthquakes. Another

  17. A Self-Consistent Model to Explain Shallow Volcanic Tremor

    Girona, T.; Caudron, C.; Costa Rodriguez, F.; Taisne, B.

    2015-12-01

    Volcanic tremor sourced at shallow depths (~ hundreds of meters) is one of the most characteristic seismic signals recorded at active volcanoes and yet to be fully understood. It typically appears preceding many impending volcanic eruptions. However, the origin of this seismic signal remains unclear, which limits our understanding of the sub-surface processes during volcanic unrest. In this study, we propose that the shallow volcanic tremor emerges from pressure oscillations occurring beneath volcanic craters as consequence of continuous degassing. To test this hypothesis, we have coupled a new three-dimensional two-phase flow agent-based model that simulates the bubble dynamics in a magma conduit, a lumped-parameter model for the evolution of the gas pressure beneath the crater, and a lumped-parameter model to simulate the permeable transfer of volcanic gases to the atmosphere. Our numerical experiments reveal that pressure oscillations beneath volcanic craters can explain the main features of shallow volcanic tremor, namely, the direct correlation with gas emissions, the increase of amplitude of the ground vibrations when an eruption approaches, the broadband character of the dominant frequencies (in the range ~ 0.5 - 5 Hz), the frequency gliding towards higher values when the volcanic activity increases, and the power law distribution in the very high-frequency range of the spectra (from the dominant peaks till ~ 10 - 15 Hz). Our model also predicts that the exponent of the power law of the frequency spectra changes systematically with the physical parameters that are thought to vary during the onset of an unrest episode.

  18. Differences in striatal dopamine transporter density between tremor dominant and non-tremor Parkinson's disease

    Kaasinen, Valtteri; Kinos, Maija; Joutsa, Juho [University of Turku and Turku University Hospital, Division of Clinical Neurosciences, Turku (Finland); University of Turku and Turku University Hospital, Turku PET Centre, Turku (Finland); Seppaenen, Marko [University of Turku and Turku University Hospital, Turku PET Centre, Turku (Finland); University of Turku and Turku University Hospital, Department of Clinical Physiology and Nuclear Medicine, Turku (Finland); Noponen, Tommi [University of Turku and Turku University Hospital, Department of Clinical Physiology and Nuclear Medicine, Turku (Finland)

    2014-10-15

    Parkinson's disease (PD) can manifest with a tremor-dominant or a non-tremor (akinetic-rigid) phenotype. Although the tremor-dominant subtype may show a better prognosis, there is limited information on the phenotypic differences regarding the level of striatal dopamine transmission. The present study investigated striatal dopamine transporter (DAT) binding characteristics in a large sample of patients with and without tremor. [{sup 123}I]FP-CIT SPECT scans of 231 patients with a clinical diagnosis of PD and abnormal FP-CIT binding (157 with tremor, 74 without tremor) and 230 control patients with normal FP-CIT binding (148 with tremor, 82 without tremor) were analysed using an automated region-of-interest analysis of the scans (BRASS). Specific striatal binding ratios were compared between phenotypes and groups using age, sex, and symptom duration, predominant side of symptoms, dopaminergic medications and scanner as covariates. Patients with PD had 28.1 - 65.0 % lower binding in all striatal regions compared to controls (p < 0.001). The mean FP-CIT caudate nucleus uptake and the left caudate nucleus uptake were higher in PD patients with tremor than in PD patients without tremor (mean 9.0 % higher, left 10.5 % higher; p < 0.05), whereas there were no differences between tremor and non-tremor control patients. No significant effects of tremor on DAT binding were observed in the anterior or posterior putamen. The motor phenotype is associated with the extent of caudate dopamine terminal loss in PD, as dopamine function is relatively more preserved in tremor patients. Symptom type is related to caudate dopamine function only in association with Parkinsonian dopaminergic degeneration, not in intact dopamine systems in patients with non-PD tremor. (orig.)

  19. Discriminating Simulated Vocal Tremor Source Using Amplitude Modulation Spectra

    Carbonell, Kathy M.; Lester, Rosemary A.; Story, Brad H.; Lotto, Andrew J.

    2014-01-01

    Objectives/Hypothesis Sources of vocal tremor are difficult to categorize perceptually and acoustically. This paper describes a preliminary attempt to discriminate vocal tremor sources through the use of spectral measures of the amplitude envelope. The hypothesis is that different vocal tremor sources are associated with distinct patterns of acoustic amplitude modulations. Study Design Statistical categorization methods (discriminant function analysis) were used to discriminate signals from simulated vocal tremor with different sources using only acoustic measures derived from the amplitude envelopes. Methods Simulations of vocal tremor were created by modulating parameters of a vocal fold model corresponding to oscillations of respiratory driving pressure (respiratory tremor), degree of vocal fold adduction (adductory tremor) and fundamental frequency of vocal fold vibration (F0 tremor). The acoustic measures were based on spectral analyses of the amplitude envelope computed across the entire signal and within select frequency bands. Results The signals could be categorized (with accuracy well above chance) in terms of the simulated tremor source using only measures of the amplitude envelope spectrum even when multiple sources of tremor were included. Conclusions These results supply initial support for an amplitude-envelope based approach to identify the source of vocal tremor and provide further evidence for the rich information about talker characteristics present in the temporal structure of the amplitude envelope. PMID:25532813

  20. Sequence-specific targeting of dosage compensation in Drosophila favors an active chromatin context.

    Artyom A Alekseyenko

    Full Text Available The Drosophila MSL complex mediates dosage compensation by increasing transcription of the single X chromosome in males approximately two-fold. This is accomplished through recognition of the X chromosome and subsequent acetylation of histone H4K16 on X-linked genes. Initial binding to the X is thought to occur at "entry sites" that contain a consensus sequence motif ("MSL recognition element" or MRE. However, this motif is only ∼2 fold enriched on X, and only a fraction of the motifs on X are initially targeted. Here we ask whether chromatin context could distinguish between utilized and non-utilized copies of the motif, by comparing their relative enrichment for histone modifications and chromosomal proteins mapped in the modENCODE project. Through a comparative analysis of the chromatin features in male S2 cells (which contain MSL complex and female Kc cells (which lack the complex, we find that the presence of active chromatin modifications, together with an elevated local GC content in the surrounding sequences, has strong predictive value for functional MSL entry sites, independent of MSL binding. We tested these sites for function in Kc cells by RNAi knockdown of Sxl, resulting in induction of MSL complex. We show that ectopic MSL expression in Kc cells leads to H4K16 acetylation around these sites and a relative increase in X chromosome transcription. Collectively, our results support a model in which a pre-existing active chromatin environment, coincident with H3K36me3, contributes to MSL entry site selection. The consequences of MSL targeting of the male X chromosome include increase in nucleosome lability, enrichment for H4K16 acetylation and JIL-1 kinase, and depletion of linker histone H1 on active X-linked genes. Our analysis can serve as a model for identifying chromatin and local sequence features that may contribute to selection of functional protein binding sites in the genome.

  1. High-contrast imaging with an arbitrary aperture: Active compensation of aperture discontinuities

    We present a new method to achieve high-contrast images using segmented and/or on-axis telescopes. Our approach relies on using two sequential deformable mirrors (DMs) to compensate for the large amplitude excursions in the telescope aperture due to secondary support structures and/or segment gaps. In this configuration the parameter landscape of DM surfaces that yield high-contrast point-spread functions is not linear, and nonlinear methods are needed to find the true minimum in the optimization topology. We solve the highly nonlinear Monge-Ampere equation that is the fundamental equation describing the physics of phase-induced amplitude modulation. We determine the optimum configuration for our two sequential DM system and show that high-throughput and high-contrast solutions can be achieved using realistic surface deformations that are accessible using existing technologies. We name this process Active Compensation of Aperture Discontinuities (ACAD). We show that for geometries similar to the James Webb Space Telescope, ACAD can attain at least 10–7 in contrast and an order of magnitude higher for both the future extremely large telescopes and on-axis architectures reminiscent of the Hubble Space Telescope. We show that the converging nonlinear mappings resulting from our DM shapes actually damp near-field diffraction artifacts in the vicinity of the discontinuities. Thus, ACAD actually lowers the chromatic ringing due to diffraction by segment gaps and struts while not amplifying the diffraction at the aperture edges beyond the Fresnel regime. This outer Fresnel ringing can be mitigated by properly designing the optical system. Consequently, ACAD is a true broadband solution to the problem of high-contrast imaging with segmented and/or on-axis apertures. We finally show that once the nonlinear solution is found, fine tuning with linear methods used in wavefront control can be applied to further contrast by another order of magnitude. Generally speaking, the

  2. Resistance of Cancer Cells to Targeted Therapies Through the Activation of Compensating Signaling Loops.

    von Manstein, Viktoria; Yang, Chul Min; Richter, Diane; Delis, Natalia; Vafaizadeh, Vida; Groner, Bernd

    2013-12-01

    The emergence of low molecular weight kinase inhibitors as "targeted" drugs has led to remarkable advances in the treatment of cancer patients. The clinical benefits of these tumor therapies, however, vary widely in patient populations and with duration of treatment. Intrinsic and acquired resistance against such drugs limits their efficacy. In addition to the well studied mechanisms of resistance based upon drug transport and metabolism, genetic alterations in drug target structures and the activation of compensatory cell signaling have received recent attention. Adaptive responses can be triggered which counteract the initial dependence of tumor cells upon a particular signaling molecule and allow only a transient inhibition of tumor cell growth. These compensating signaling mechanisms are often based upon the relief of repression of regulatory feedback loops. They might involve cell autonomous, intracellular events or they can be mediated via the secretion of growth factor receptor ligands into the tumor microenvironment and signal induction in an auto- or paracrine fashion. The transcription factors Stat3 and Stat5 mediate the biological functions of cytokines, interleukins and growth factors and can be considered as endpoints of multiple signaling pathways. In normal cells this activation is transient and the Stat molecules return to their non-phosphorylated state within a short time period. In tumor cells the balance between activating and de-activating signals is disturbed resulting in the persistent activation of Stat3 or Stat5. The constant activation of Stat3 induces the expression of target genes, which cause the proliferation and survival of cancer cells, as well as their migration and invasive behavior. Activating components of the Jak-Stat pathway have been recognized as potentially valuable drug targets and important principles of compensatory signaling circuit induction during targeted drug treatment have been discovered in the context of kinase

  3. The Dynamics of Voluntary Force Production in Afferented Muscle Influence Involuntary Tremor.

    Laine, Christopher M; Nagamori, Akira; Valero-Cuevas, Francisco J

    2016-01-01

    Voluntary control of force is always marked by some degree of error and unsteadiness. Both neural and mechanical factors contribute to these fluctuations, but how they interact to produce them is poorly understood. In this study, we identify and characterize a previously undescribed neuromechanical interaction where the dynamics of voluntary force production suffice to generate involuntary tremor. Specifically, participants were asked to produce isometric force with the index finger and use visual feedback to track a sinusoidal target spanning 5-9% of each individual's maximal voluntary force level. Force fluctuations and EMG activity over the flexor digitorum superficialis (FDS) muscle were recorded and their frequency content was analyzed as a function of target phase. Force variability in either the 1-5 or 6-15 Hz frequency ranges tended to be largest at the peaks and valleys of the target sinusoid. In those same periods, FDS EMG activity was synchronized with force fluctuations. We then constructed a physiologically-realistic computer simulation in which a muscle-tendon complex was set inside of a feedback-driven control loop. Surprisingly, the model sufficed to produce phase-dependent modulation of tremor similar to that observed in humans. Further, the gain of afferent feedback from muscle spindles was critical for appropriately amplifying and shaping this tremor. We suggest that the experimentally-induced tremor may represent the response of a viscoelastic muscle-tendon system to dynamic drive, and therefore does not fall into known categories of tremor generation, such as tremorogenic descending drive, stretch-reflex loop oscillations, motor unit behavior, or mechanical resonance. Our findings motivate future efforts to understand tremor from a perspective that considers neuromechanical coupling within the context of closed-loop control. The strategy of combining experimental recordings with physiologically-sound simulations will enable thorough exploration

  4. Seismic Wave Attenuation Estimated from Tectonic Tremor and Radiated Energy in Tremor for Various Subduction Zones

    Yabe, S.; Baltay, A.; Ide, S.; Beroza, G. C.

    2013-12-01

    Ground motion prediction is an essential component of earthquake hazard assessment. Seismic wave attenuation with distance is an important, yet difficult to constrain, factor for such estimation. Using the empirical method of ground motion prediction equations (GMPEs), seismic wave attenuation with distance, which includes both the effect of anelastic attenuation and scattering, can be estimated from the distance decay of peak ground velocity (PGV) or peak ground acceleration (PGA) of ordinary earthquakes; however, in some regions where plate-boundary earthquakes are infrequent, such as Cascadia and Nankai, there are fewer data with which to constrain the empirical parameters. In both of those subduction zones, tectonic tremor occurs often. In this study, we use tectonic tremor to estimate the seismic wave attenuation with distance, and in turn use the attenuation results to estimate the radiated seismic energy of tremor. Our primary interest is in the variations among subduction zones. Ground motion attenuation and the distribution of released seismic energy from tremors are two important subduction zone characteristics. Therefore, it is very interesting to see whether there are variations of these parameters in different subduction zones, or regionally within the same subduction zone. It is also useful to estimate how much energy is released by tectonic tremor from accumulated energy to help understand subduction dynamics and the difference between ordinary earthquakes and tremor. We use the tectonic tremor catalog of Ide (2012) in Nankai, Cascadia, Mexico and southern Chile. We measured PGV and PGA of individual tremor bursts at each station. We assume a simple GMPE relationship and estimate seismic attenuation and relative site amplification factors from the data. In the Nankai subduction zone, there are almost no earthquakes on the plate interface, but intra-slab earthquakes occur frequently. Both the seismic wave attenuation with distance and the site

  5. Functional MRI for immediate monitoring stereotactic thalamotomy in a patient with essential tremor

    The effect of stereotactic thalamotomy was assessed with pre- and postoperative functional magnetic resonance imaging (fMRI) under motor stimulation. A patient with unilateral essential tremor (ET) of the left arm underwent stereotactically guided thalamotomy of the right ventral intermediate thalamic nucleus (VIM). FMRI was done directly before and after surgery on a 1.5-Tesla scanner. The stimulation paradigm was maintainance of the affected arm in an extended position and hand clenching being performed in a block design manner. Statistical analysis was done with Brain Voyager 2000. After thalamotomy the tremor diminished completely. As a difference between the pre- and postoperative fMRI, a significant activation was found in the VIM contralateral to the activation site, adjacent to the inferior olivary nucleus contralateral to the activation site and in the dorsal cingulum. In conclusion, fMRI can detect the functional effect of thalamotomy for tremor treatment. Direct postoperative fMRI provides a sufficient method for estimating the effect of thalamotomy immediately after intervention. The importance of the intermediate thalamic nucleus and the olivary nucleus in tremor generation is supported by our findings. (orig.)

  6. Eye movements between saccades: Measuring ocular drift and tremor.

    Ko, Hee-Kyoung; Snodderly, D Max; Poletti, Martina

    2016-05-01

    Intersaccadic periods of fixation are characterized by incessant retinal motion due to small eye movements. While these movements are often disregarded as noise, the temporal modulations they introduce to retinal receptors are significant. However, analysis of these input modulations is challenging because the intersaccadic eye motion is close to the resolution limits of most eyetrackers, including widespread pupil-based video systems. Here, we analyzed in depth the limits of two high-precision eyetrackers, the Dual-Purkinje Image and the scleral search coil, and compared the intersaccadic eye movements of humans to those of a non-human primate. By means of a model eye we determined that the resolution of both techniques is sufficient to reliably measure intersaccadic ocular activity up to approximately 80Hz. Our results show that the characteristics of ocular drift are remarkably similar in the two species; a clear deviation from a scale-invariant spectrum occurs in the range between 50 and 100Hz, generally attributed to ocular tremor, leading to intersaccadic retinal speeds as high as 1.5deg/s. The amplitude of this deviation differs on the two axes of motion. In addition to our experimental observations, we suggest basic guidelines to evaluate the performance of eyetrackers and to optimize experimental conditions for the measurement of ocular drift and tremor. PMID:27068415

  7. Brittle and ductile friction and the physics of tectonic tremor

    Daub, E.G.; Shelly, D.R.; Guyer, R.A.; Johnson, P.A.

    2011-01-01

    Observations of nonvolcanic tremor provide a unique window into the mechanisms of deformation and failure in the lower crust. At increasing depths, rock deformation gradually transitions from brittle, where earthquakes occur, to ductile, with tremor occurring in the transitional region. The physics of deformation in the transition region remain poorly constrained, limiting our basic understanding of tremor and its relation to earthquakes. We combine field and laboratory observations with a physical friction model comprised of brittle and ductile components, and use the model to provide constraints on the friction and stress state in the lower crust. A phase diagram is constructed that characterizes under what conditions all faulting behaviors occur, including earthquakes, tremor, silent transient slip, and steady sliding. Our results show that tremor occurs over a range of ductile and brittle frictional strengths, and advances our understanding of the physical conditions at which tremor and earthquakes take place. Copyright ?? 2011 by the American Geophysical Union.

  8. Action tremor in Parkinson's disease.

    Teräväinen, H; Calne, D. B.

    1980-01-01

    Electromyographic activity of the biceps muscle was examined in 38 parkinsonian patients and 33 normal subjects during (i) rapidly alternating pronation-supination movements (RAM) of the forearm, and (ii) single pronation or supination movements in response to visual (light) or to kinesthetic signals (displacements of the hand). Biceps electromyography (EMG) displayed rhythmic activity over the supination phase of RAM in the majority of the parkinsonian patients, whereas continuous activity w...

  9. An elderly man with progressive ataxia and palatal tremor presenting with dizziness and oculopalatal tremor.

    Tsukahara, Yuka; Suzuki, Keisuke; Kokubun, Norito; Nakamura, Toshiki; Takekawa, Hidehiro; Hirata, Koichi

    2016-08-31

    A 74-year-old man was referred to our department for dizziness and progressive unsteady gait over 6 years. His family history was unremarkable. Neurological examination showed dysarthria, saccadic eye movement, palatal tremor (1.7 Hz)-synchronous with rotational ocular movement, and truncal ataxia. T2-weighted magnetic resonance imaging (MRI) of the brain revealed hyperintense and hypertrophic bilateral inferior olivary nuclei at the medulla and mild cerebellar atrophy. On the basis of neurological findings of oculopalatal tremor and cerebellar ataxia with brain MRI findings, the diagnosis of progressive ataxia and palatal tremor (PAPT) was made. PAPT should be included in differential diagnosis of dizziness observed in elderly individuals. PMID:27477579

  10. Ondansetron, a 5-HT3 antagonist, improves cerebellar tremor.

    Rice, G P; Lesaux, J; Vandervoort, P.; Macewan, L; Ebers, G C

    1997-01-01

    It has been previously shown that ondansetron, a 5-HT3 antagonist, can ameliorate vertigo in patients with acute brainstem disorders. A coincidental benefit was the improvement of cerebellar tremor in some patients with both vertigo and tremor. To further evaluate this effect, a placebo controlled, double blind, crossover study was conducted of a single dose of intravenous ondansetron in 20 patients with cerebellar tremor caused by multiple sclerosis, cerebellar degeneration, or drug toxicity...

  11. Analysis of tremor at the San Andreas Fault at Parkfield

    Horstmann, Tobias

    2013-01-01

    Emergent phase arrivals, low amplitude waveforms, and variable event durations make detection and location of tectonic tremor a non-trivial task. In this work I employ a new method to identify tremor in large datasets using a semi-automated technique, which is comprised of an envelope cross-correlation and a Self-Organizing Map (SOM) algorithm to identify and classify event types. Furthermore, I present a new tremor localization method based on time-reversal imaging techniques.

  12. Failure to transmit disease from gray tremor mutant mice.

    Carlson, G A; Banks, S; Lund,D.; Reichert, C. (rapporteur); Groth, D; Torchia, M; DeArmond, S J; Prusiner, S B

    1997-01-01

    Mice homozygous for mutant alleles at the gray tremor (gt) locus develop a marked non-intention tremor beginning at 8 days of age. Most homozygous mice die by 3 months. Homozygotes exhibit intense vacuolation of the central nervous system gray matter and vacuolation and hypomyelination of some white matter tracts. Based on neuropathological similarities with scrapie, other investigators inoculated wild-type mice with gray tremor brain homogenates to test the hypothesis of transmissibility. Pu...

  13. Volcanic tremor at Mt Vesuvius associated with low frequency shear failures

    La Rocca, Mario; Galluzzo, Danilo

    2016-05-01

    Mt Vesuvius has been dormant since the eruption occurred in 1944, after which the conduit closed and the volcano entered a quiescent state. Only a minor seismic activity, characterized by low magnitude volcano-tectonic (VT) earthquakes, testifies that the magmatic system is still active. In this paper we report the fist quantitative analysis of volcanic tremor discovered at Vesuvius through the analysis of array data. A seismic array installed in 2012 improved the monitoring performance of the local network, permitting the identification of low amplitude coherent signals. Many of such coherent signals recorded during the last few years have been classified as volcanic tremor. We selected 22 tremor events based on their amplitude and on the number of available stations, and performed detailed analysis aimed at location and characterization of the source. They are characterized by low frequency, duration of a few minutes, and the strongest episodes are recorded at distance up to 90 km from the volcano. In many cases we could identify P-S wave pairs in the seismograms that allowed a precise location of the source depth, which is in the range between 5 km and 6.5 km below the crater. Waveform features, spectral analysis, and comparison with VT earthquakes located at the same depth indicate that the source mechanism of the Vesuvius non-eruptive tremor is a sequence of low frequency shear failures.

  14. Polymer structure and the compensation effect of the diffusion pre-exponential factor and activation energy of a permeating solute.

    Zheng, Ju-Meng; Qiu, Jun; Madeira, Luis M; Mendes, Adélio

    2007-03-22

    In the present work, the relation between the pre-exponential factor and the apparent activation energy of diffusion, ln D(0) = alpha + betaE(D), so-called compensation effect, is re-examined and critically discussed for diffusion of gases in rubbery and glassy polymers. In principle, the above equation could be derived from the enthalpy-entropy compensation in the framework of the transition state theory. However, one should consider the influence of the jump length term contained in the pre-exponential factor, which may be affected by permeating species and polymer properties. We found that parameter alpha depends on penetrant size and polymer properties, such as local chain mobility and free volume. This can be interpreted by the fact that the jump length is affected by both penetrant and polymer properties. Finally, methods for estimating the jump length are discussed. PMID:17316040

  15. Observations of volcanic earthquakes and tremor at Deception Island - Antarctica

    J. Morales

    1999-06-01

    Full Text Available Deception Island - South Shetlands, Antarctica is site of active volcanism. Since 1988 field surveys have been carried out with the aim of seismic monitoring, and in 1994 a seismic array was set up near the site of the Spanish summer base in order to better constrain the source location and spectral properties of the seismic events related to the volcanic activity. The array was maintained during the Antarctic summer of 1995 and the last field survey was carried out in 1996. Data show the existence of three different groups (or families of seismic events: 1 long period events, with a quasi-monochromatic spectral content (1-3 Hz peak frequency and a duration of more than 50 s, often occurring in small swarms lasting from several minutes to some day; 2 volcanic tremor, with a spectral shape similar to the long period events but with a duration of several minutes (2-10; 3 hybrid events, with a waveform characterised by the presence of a high frequency initial phase, followed by a low frequency phase with characteristics similar to those of the long period events. The high frequency phase of the hybrid events was analysed using polarisation techniques, showing the presence of P waves. This phase is presumably located at short epicentral distances and shallow source depth. All the analysed seismic events show back-azimuths between 120 and 330 degrees from north (corresponding to zones of volcanic activity showing no seismic activity in the middle of the caldera. Particle motion, Fourier spectral and spectrogram analysis show that the low frequency part of the three groups of the seismic signals have similar patterns. Moreover careful observations show that the high frequency phase which characterises the hybrid events is present in the long period and in the tremor events, even with lower signal to noise ratios. This evidence suggests that long period events are events in which the high frequency part is simply difficult to observe, due to a very

  16. Design and preliminary testing of a handheld antagonistic SMA actuator for cancellation of human tremor

    Pathak, Anupam; Brei, Diann; Luntz, Jonathan

    2009-03-01

    Essential Tremor is a debilitating disorder that in the US alone is estimated to affect up to ten million people. Unfortunately current treatments (i.e. drug therapy and surgical procedures), are limited in effectiveness and often pose a risk of adverse side-effects. In response to this problem, this paper describes an active cancellation device based on a hand-held Shape Memory Alloy (SMA) actuated stabilization platform. The assistive device is designed to hold and stabilize various objects (e.g. eating utensils, tools, pointing implements, etc.) by sensing the user's tremor and moving the object in an opposite direction using SMA actuators configured in biologically inspired antagonistic pairs. To aid in the design, performance prediction and control of the device, a device model is described that accounts for the device kinematics, SMA thermo-mechanics, and the heat transfer resulting from electrical heating and convective cooling. The system of differential equations in this device model coupled with the controller gain can be utilized to design the operation given a frequency range and power requirement. To demonstrate this, a prototype was built and experimentally tested under external disturbances in the range of 1-5 Hz, resulting in amplitude reduction of up to 80%. The extent of cancellation measured for both single-frequencies and actual human tremor disturbances demonstrate the promise of this approach as a broadly used assistive device for the multitudes afflicted by tremor.

  17. Control of transient vibrations due to stage movements in 6-dof active pneumatic table by inertial force compensation

    Sun, Jong-Oh; Kim, Kwang-joon

    2013-10-01

    Passive pneumatic tables are popularly used in precision measurements or processes for isolation of ground vibrations over frequency ranges higher than resonance frequencies of a few Hz typically. Recently, active pneumatic tables are also used often because the passive systems are liable to table excitations in the low resonance frequency ranges, causing long settling times. In studies on the active tables, disturbances onto the tables were often regarded to be unknown and, hence, feedback control algorithms were implemented. However, the disturbances are mostly due to inertial forces due to movement of equipment on the table, e.g., x-y stages. Such a movement is given relative to the table as command inputs. Since absolute motion of the table is normally measured in an active isolation table, absolute motion of the equipment can be easily estimated for calculation of the inertial force exerted onto the table by the moving equipment. Consequently, by compensating dynamic pressure inside the pneumatic chamber to counteract with the inertia force due to the equipment motion, resultant forces acting onto the table can be made zero. In this paper, how to apply the proposed feed-forward control algorithm to a 6-degree of freedom active pneumatic table with time-delay pneumatic control is presented. Performance of the inertial force compensation control evaluated through experiments is also discussed.

  18. The plumbing of Old Faithful Geyser revealed by hydrothermal tremor

    Vandemeulebrouck, J.; Roux, P.; Cros, E.

    2013-05-01

    Faithful Geyser in Yellowstone National Park (USA) has attracted numerous scientific investigations for over two centuries to better understand its geological structure, the physics of its eruptions, and the controls of its intermittency. Using data acquired with a seismic array in 1992, we track the sources of hydrothermal tremor produced by boiling and cavitation inside the geyser. The location of seismic sources identifies a previously unknown lateral cavity at 15 m below the surface, on the SW side of the vent, and connected to the conduit. This reservoir is activated at the beginning of each geyser eruption cycle and plays a major role in the oscillatory behavior of the water level in the conduit before each eruption.

  19. Evaluation of a screening instrument for essential tremor

    Lorenz, Delia; Papengut, Frank; Frederiksen, Henrik; Kopper, Florian; Klebe, Stephan; Christensen, Kaare; Schreiber, Stefan; Deuschl, Günther

    2008-01-01

    To evaluate a screening instrument for essential tremor (ET) consisting of a seven-item questionnaire and a spiral drawing. A total of 2,448 Danish twins aged 70 years or more and a second sample aged 60 years or more (n = 1,684) from a population-based northern German cross-sectional study (Pop...... significantly with higher spiral scores and more positive items. More patients were identified by spiral drawing in all tremor groups. The interrater and intrarater reliability for spirals ranged from 0.7 to 0.8 using intraclass coefficient. A cluster analysis revealed that the questionnaire can be reduced to...... three items, about uncontrollable tremor in any body part, tremor while drinking or pouring and other family members with tremor, without loosing efficacy. We present an easy to use and reliable screening instrument that is effective to identify patients with ET but not able to exclude patients with...

  20. Correlation between deep fluids, tremor and creep along the central San Andreas fault

    Becken, M.; Ritter, O.; Bedrosian, P.A.; Weckmann, U.

    2011-01-01

    The seismicity pattern along the San Andreas fault near Parkfield and Cholame, California, varies distinctly over a length of only fifty kilometres. Within the brittle crust, the presence of frictionally weak minerals, fault-weakening high fluid pressures and chemical weakening are considered possible causes of an anomalously weak fault northwest of Parkfield. Non-volcanic tremor from lower-crustal and upper-mantle depths is most pronounced about thirty kilometres southeast of Parkfield and is thought to be associated with high pore-fluid pressures at depth. Here we present geophysical evidence of fluids migrating into the creeping section of the San Andreas fault that seem to originate in the region of the uppermost mantle that also stimulates tremor, and evidence that along-strike variations in tremor activity and amplitude are related to strength variations in the lower crust and upper mantle. Interconnected fluids can explain a deep zone of anomalously low electrical resistivity that has been imaged by magnetotelluric data southwest of the Parkfield-Cholame segment. Near Cholame, where fluids seem to be trapped below a high-resistivity cap, tremor concentrates adjacent to the inferred fluids within a mechanically strong zone of high resistivity. By contrast, subvertical zones of low resistivity breach the entire crust near the drill hole of the San Andreas Fault Observatory at Depth, northwest of Parkfield, and imply pathways for deep fluids into the eastern fault block, coincident with a mechanically weak crust and the lower tremor amplitudes in the lower crust. Fluid influx to the fault system is consistent with hypotheses of fault-weakening high fluid pressures in the brittle crust. ?? 2011 Macmillan Publishers Limited. All rights reserved.

  1. Radical advancement in multi-spectral imaging for autonomous vehicles (UAVs, UGVs, and UUVs) using active compensation.

    Clark, Brian F.; Bagwell, Brett E.; Wick, David Victor

    2007-01-01

    The purpose of this LDRD was to demonstrate a compact, multi-spectral, refractive imaging systems using active optical compensation. Compared to a comparable, conventional lens system, our system has an increased operational bandwidth, provides for spectral selectivity and, non-mechanically corrects aberrations induced by the wavelength dependent properties of a passive refractive optical element (i.e. lens). The compact nature and low power requirements of the system lends itself to small platforms such as autonomous vehicles. In addition, the broad spectral bandwidth of our system would allow optimized performance for both day/night use, and the multi-spectral capability allows for spectral discrimination and signature identification.

  2. An advanced static var compensator based on a three level IGBT inverter modelling analysis and active power filtering

    Draou, Azeddine

    2012-12-01

    This paper presents the dynamic performance analysis of an Advanced Static Var Compensator (ASVC) using three-level neutral point-clamped voltage source inverter. The paper presents the principles of operating and the method of reference currents generation. The dynamic behaviour of the system is further analysed using Matlab/Simulink with SimPower Systems toolbox through a set of simulation tests. The results obtained have been applied to an active power filter which might lead to the design of a robust controller for current harmonics and reactive power applications

  3. Influence of gravity compensation on kinematics and muscle activation patterns during reach and retrieval in subjects with cervical spinal cord injury: An explorative study

    Marieke G . M. Kloosterman, PT, MSc

    2010-09-01

    Full Text Available Many interventions in upper-limb rehabilitation after cervical spinal cord injury (CSCI use arm support (gravity compensation; however, its specific effects on kinematics and muscle activation characteristics in subjects with a CSCI are largely unknown. We conducted a cross-sectional explorative study to study these effects. Nine subjects with a CSCI performed two goal-directed arm movements (maximal reach, reach and retrieval with and without gravity compensation. Angles at elbow and shoulder joints and muscle activation were measured and compared. Seven subjects reduced elbow extension (range 1.8°-4.5° during the maximal reaching task with gravity compensation. In the reach and retrieval task with gravity compensation, all subjects decreased elbow extension (range 0.1°-11.0°. Eight subjects executed movement closer to the body. Regarding muscle activation, gravity compensation did not influence timing; however, the amplitude of activation decreased, especially in antigravity muscles, namely mean change +/- standard deviation of descending part of trapezius (18.2% +/- 37.5%, anterior part of deltoid (37.7% +/- 16.7%, posterior part of deltoid (32.0% +/- 13.9%, and long head biceps (49.6% +/- 20.0%. Clinical implications for the use of gravity compensation in rehabilitation (during activities of daily living or exercise therapy should be further investigated with a larger population.

  4. Influence of gravity compensation on kinematics and muscle activation patterns during reach and retrieval in subjects with cervical spinal cord injury: an explorative study.

    Kloosterman, Marieke G M; Snoek, Govert J; Kouwenhoven, Mirjam; Nene, Anand V; Jannink, Michiel J A

    2010-01-01

    Many interventions in upper-limb rehabilitation after cervical spinal cord injury (CSCI) use arm support (gravity compensation); however, its specific effects on kinematics and muscle activation characteristics in subjects with a CSCI are largely unknown. We conducted a cross-sectional explorative study to study these effects. Nine subjects with a CSCI performed two goal-directed arm movements (maximal reach, reach and retrieval) with and without gravity compensation. Angles at elbow and shoulder joints and muscle activation were measured and compared. Seven subjects reduced elbow extension (range 1.8°-4.5°) during the maximal reaching task with gravity compensation. In the reach and retrieval task with gravity compensation, all subjects decreased elbow extension (range 0.1°-11.0°). Eight subjects executed movement closer to the body. Regarding muscle activation, gravity compensation did not influence timing; however, the amplitude of activation decreased, especially in antigravity muscles, namely mean change +/- standard deviation of descending part of trapezius (18.2% +/- 37.5%), anterior part of deltoid (37.7% +/- 16.7%), posterior part of deltoid (32.0% +/- 13.9%), and long head biceps (49.6% +/- 20.0%). Clinical implications for the use of gravity compensation in rehabilitation (during activities of daily living or exercise therapy) should be further investigated with a larger population. PMID:21110258

  5. Cosmic signatures in earth's seismic tremor?

    Mulargia, Francesco

    2016-01-01

    Even in absence of earthquakes, each site on earth experiences continuous elastic vibrations which are mostly traced to the non-linear interactions of sea waves. However, the fine structure of the spectrum at mHz frequencies shows hundreds of highly significant narrow bandwidth peaks, with a persistence and a coincidence with solar acoustic eigenmodes which are incompatible with any geophysical origin. The feasibility of a common cosmic origin is evaluated through an estimate of the gravitational wave cross-section of the earth, combined with its elastic response and with the stochastic amplification produced by the interference of the cosmic signal with tremor of oceanic origin. The measured spectral peaks appear compatible with a gravitational monochromatic illumination at strains $h \\gtrsim 10^{-20} $. We analize in detail the band around 2.614 mHz, where the binary white dwarf J0651+2844 - which is the second strongest known gravitational stellar source - is expected to emit. Compatible spectral tremor pe...

  6. Compensated activation of coagulation in patients with abdominal aortic aneurysm: effects of heparin treatment prior to elective surgery.

    Jelenska, Maria Magdalena; Szmidt, Jacek; Bojakowski, Krzystof; Grzela, Tomasz; Palester-Chlebowczyk, Magorzata

    2004-11-01

    Elective surgery of abdominal aortic aneurysm (AAA) sometimes leads to excessive bleeding and disseminated intravascular coagulation (DIC), even in patients with normal preoperative coagulation parameters. Coagulation screen, performed routinely before surgery is of limited value in the assessment of compensated activation of the haemostatic system. In this study, we used a number of additional tests (D-dimer, prothrombin fragment 1+2, antithrombin, and activation of fibrinolysis in the platelet poor plasma) for the diagnosis of compensated activation of the haemostatic system in AAA-patients. D-dimer and marker of thrombin generation (prothrombin fragment 1+2) positively correlated with each other (r = 0.768, P D-dimer and prothrombin fragment 1+2 decreased significantly) and resulted in the increase of platelet number and fibrinogen concentration, indicating their previous consumption. Despite differences in aneurysm diameters between the groups of 15 LMWH treated patients (mean 70.9 +/- 16 mm) and the reference group of 20 untreated AAA patients (mean 52.3 +/- 8.0 mm), intraoperative parameters (operation time, blood loss and transfusion demands) were similar. PMID:15543326

  7. Analysis and active compensation of microphonics in continuous wave narrow-bandwidth superconducting cavities

    Neumann, A.; Anders, W.; Kugeler, O.; Knobloch, J.

    2010-08-01

    Many proposals for next generation light sources based on single pass free electron lasers or energy recovery linac facilities require a continuous wave (cw) driven superconducting linac. The effective beam loading in such machines is very small and in principle the cavities can be operated at a bandwidth of a few Hz and with less than a few kW of rf power. However, a power reserve is required to ensure field stability. A major error source is the mechanical microphonics detuning of the niobium cavities. To understand the influence of cavity detuning on longitudinal beam stability, a measurement program has been started at the horizontal cavity test facility HoBiCaT at HZB to study TESLA-type cavities. The microphonics detuning spectral content, peak detuning values, and the driving terms for these mechanical oscillations have been analyzed. In combination with the characterization of cw-adapted fast tuning systems based on the piezoelectric effect this information has been used to design a detuning compensation algorithm. It has been shown that a compensation factor between 2-7 is achievable, reducing the typical detuning of 2-3 Hz rms to below 0.5 Hz rms. These results were included in rf-control simulations of the cavities, and it was demonstrated that a phase stability below 0.02° can be achieved.

  8. Dynamical tools for the analysis of long term evolution of volcanic tremor at Stromboli

    M. Di Cecca

    1999-06-01

    Full Text Available Stromboli is characterized by persistent seismic activity, both in terms of tremor and of discrete events associated with moderate explosions defining the so-called "Strombolian activity". This kind of permanent activity suggests the probable existence of a dynamical system governing the volcano. The purpose of this paper is to extract information on the "Stromboli dynamical system" from the seismic recordings. The analysis is carried out using the theory of non-linear dynamical systems and the delayed coordinates phase-space reconstruction. Several methods are presented and discussed in order to analyze volcanic tremor data in this framework; finally the time evolution of the computed parameters, both in the long term and close in time to paroxysmal phases, is presented and discussed. Evidence for a strong deterministic component in the dynamics of the volcano is shown.

  9. Photovoltaic power converter system with a controller configured to actively compensate load harmonics

    de Rooij, Michael Andrew; Steigerwald, Robert Louis; Delgado, Eladio Clemente

    2008-12-16

    Photovoltaic power converter system including a controller configured to reduce load harmonics is provided. The system comprises a photovoltaic array and an inverter electrically coupled to the array to generate an output current for energizing a load connected to the inverter and to a mains grid supply voltage. The system further comprises a controller including a first circuit coupled to receive a load current to measure a harmonic current in the load current. The controller includes a second circuit to generate a fundamental reference drawn by the load. The controller further includes a third circuit for combining the measured harmonic current and the fundamental reference to generate a command output signal for generating the output current for energizing the load connected to the inverter. The photovoltaic system may be configured to compensate harmonic currents that may be drawn by the load.

  10. Tremors in the Bayou: The Events on the Napoleonville Salt Dome, Louisiana

    Ellsworth, W. L.; Horton, S.; Benz, H.; Hickman, S.; Leeds, A.; Leith, W. S.; Meremonte, M.; Rubinstein, J. L.; Withers, M. M.; Herrmann, R. B.

    2012-12-01

    Beginning in early June, 2012, an extended series of earth tremors were reported by residents of Bayou Corne in Assumption Parish, Louisiana, and at well control facilities on the nearby Napoleonville salt dome. The salt dome contains numerous caverns resulting from solution mining; some are used to store LPG and natural gas while others produce saltwater brine. Residents also reported natural gas bubbling at nearby locations in Bayou Corne and Grand Bayou. Some of the tremors were large enough to produce "cracks in sheet rock and foundations" (The Advocate, Baton Rouge, July 5, 2012). It was thus quite surprising to find that no earthquakes were detected in this region by either the USGS NEIC or the USArray Array Network Facility despite the presence of Transportable Array station 544A only 10 km from Bayou Corne. Careful inspection of the seismograms at 544A did reveal multiple events characterized by virtually no body wave energy and strong surface waves at the times of reported tremors. In response to a request for assistance from the State of Louisiana six temporary seismic stations with Trillium broad band sensors were deployed in the immediate epicentral region by the USGS and University of Memphis starting on July 12. Seismograms recorded by the temporary stations revealed a variable rate of tremor activity, with several hundred events registered on active days. Even at very close distance (S-P < 0.5 s) the body waves are weak and surface waves prominent, indicating a very shallow source depth. Precise location of the events is complicated by the presence of the high-seismic velocity and steep-sided Napoleonville salt dome that reaches to within 220 m of the surface and is overlain and surrounded by very low velocity sediments. Following several repositionings of the seismic network we have determined that the source region lies on the western edge of the salt dome top at very shallow depth and in the vicinity of an abandoned brine supply cavern. Tremor

  11. Tremor reveals stress shadowing, deep postseismic creep, and depth-dependent slip recurrence on the lower-crustal San Andreas fault near Parkfield

    Shelly, David R.; Johnson, Kaj M.

    2011-01-01

    The 2003 magnitude 6.5 San Simeon and the 2004 magnitude 6.0 Parkfield earthquakes induced small, but significant, static stress changes in the lower crust on the central San Andreas fault, where recently detected tectonic tremor sources provide new constraints on deep fault creep processes. We find that these earthquakes affect tremor rates very differently, consistent with their differing transferred static shear stresses. The San Simeon event appears to have cast a "stress shadow" north of Parkfield, where tremor activity was stifled for 3-6 weeks. In contrast, the 2004 Parkfield earthquake dramatically increased tremor activity rates both north and south of Parkfield, allowing us to track deep postseismic slip. Following this event, rates initially increased by up to two orders of magnitude for the relatively shallow tremor sources closest to the rupture, with activity in some sources persisting above background rates for more than a year. We also observe strong depth dependence in tremor recurrence patterns, with shallower sources generally exhibiting larger, less-frequent bursts, possibly signaling a transition toward steady creep with increasing temperature and depth. Copyright 2011 by the American Geophysical Union.

  12. Observations of rapid-fire event tremor at Lascar volcano, Chile

    H. Rademacher

    1996-06-01

    Full Text Available During the Proyecto de Investigaciòn Sismològica de la Cordillera Occidental (PISCO '94 in the Atacama desert of Northern Chile, a continuously recording broadband seismic station was installed to the NW of the currently active volcano, Lascar. For the month of April, 1994, an additional network of three, short period, three-component stations was deployed around the volcano to help discriminate its seismic signals from other local seismicity. During the deployment, the volcanic activity at Lascar appeared to be limited mainly to the emission of steam and SO2. Tremor from Lascar is a random, «rapid-fire» series of events with a wide range of amplitudes and a quasi-fractal structure. The tremor is generated by an ensemble of independent elementary sources clustered in the volcanic edifice. In the short-term, the excitation of the sources fluctuates strongly, while the long-term power spectrum is very stationary.

  13. Losses compensation; Compensation des pertes

    NONE

    2001-07-01

    One mission of RTE (Electric Power Transportation), is to watch over the losses compensation resulting from the power transport on the electric power network. Since january 2001, RTE makes good the electric losses by the purchase of energy. To choose the marketers, a consultation has been realized by RTE. This document presents the rules concerning these losses compensation. (A.L.B.)

  14. 半主动式钻柱升沉补偿系统补偿机理分析%Analysis of the Compensating Mechanism of Semi-active Drill String Heaving Compensation System

    张萌; 胡小东; 李波

    2012-01-01

    Applying the d'Alembert principle and referring to the movement law of drill string, the parallel and serial dynamic models of semi-active drill string heaving compensation device were established. The compensating mechanism of the parallel and serial semi-active drill string heaving compensation systems were analyzed and com- pared. The findings show that the function of the passive compensation part in the system is to support most of the mass of drill string and that of the active compensation part is to compensate the variation of various forces. The hy- draulic system of the parallel structure is quite complex due to the fact that there are more executing components in parallel structure than in serial structure. However, when the generated displacement of the hull is remarkable and the compensation load required by subsea drilling is relatively large, parallel structure is better than serial struc- ture. The parallel drill string heaving compensation can only reach the control goal through the output force of the control compensation system when the control goal is to keep downhole drilling pressure unchanged in normal drill- ing conditions. But the serial structure can reach the control goal through controlling the output pressure or keeping constant output force of the compensation system.%运用达朗伯原理,结合钻柱的运动规律,分别建立了并联和串联2种形式的半主动式钻柱升沉补偿装置力学模型,分析比较这2种半主动式升沉补偿装置的补偿机理。结果表明,在半主动式升沉补偿系统中,被动补偿部分所起的作用是支撑钻柱的大部分质量,主动补偿部分只是用来补偿各种力的变化量;由于并联式结构比串联式结构的执行原件多,所以其液压系统相对复杂,但当船体升沉位移较大和深海钻进所需的补偿负载较大时,并联式结构又优于串联式结构;在正常钻进工况下,当控制目标为控制井底钻压不变时,并联式钻

  15. A capacitor-free CMOS LDO regulator with AC-boosting and active-feedback frequency compensation

    A capacitor-free CMOS low-dropout (LDO) regulator for system-on-chip (SoC) applications is presented. By adopting AC-boosting and active-feedback frequency compensation (ACB-AFFC), the proposed LDO regulator, which is independent of an off-chip capacitor, provides high closed-loop stability. Moreover, a slew rate enhancement circuit is adopted to increase the slew rate and decrease the output voltage dips when the load current is suddenly switched from low to high. The LDO regulator is designed and fabricated in a 0.6 μm CMOS process. The active silicon area is only 770 x 472 μm2. Experimental results show that the total error of the output voltage due to line variation is less than ±0.197%. The load regulation is only 0.35 mV/mA when the load current changes from 0 to 100 mA.

  16. Deep Brain Stimulation for Essential Vocal Tremor: A Technical Report.

    Ho, Allen L; Choudhri, Omar; Sung, C Kwang; DiRenzo, Elizabeth E; Halpern, Casey H

    2015-03-01

    Essential vocal tremor (EVT) is the presence of a tremulous voice that is commonly associated with essential tremor. Patients with EVT often report a necessary increase in vocal effort that significantly worsens with stress and anxiety and can significantly impact quality of life despite optimal medical and behavioral treatment options. Deep brain stimulation (DBS) has been proposed as an effective therapy for vocal tremor, but very few studies exist in the literature that comprehensively evaluate the efficacy of DBS for specifically addressing EVT. We present a technical report on our multidisciplinary, comprehensive operative methodology for treatment of EVT with frameless, awake deep brain stimulation (DBS). PMID:26180680

  17. Healthy eating at school to compensate for the activity-related obesigenic lifestyle in children and adolescents: the Quebec experience.

    Tremblay, Angelo; Arguin, Hélène

    2011-03-01

    In this article, we describe the Quebec experience about the determinants of childhood obesity and the search for solutions, which are well adapted to the constraints of the current lifestyle. As expected, it is likely that a decrease in physical fitness and its related sedentariness as well as suboptimal food habits have contributed to the increase in overweight prevalence that was observed between 1980 and 2000. Our research experience suggests that other less suspected activity related factors have also played an important role in the occurrence of the obesity epidemic. This is particularly the case for short sleeping and demanding mental work, which are features of our modern lifestyle. Because there is no foreseeable prospect for a change in sleep and mental work habits, we argue that compensations in other factors may be necessary to prevent weight gain in this new context. We thus developed a concept of food design aiming at the maximization of the satiating properties of a food or a meal course. In this context, we were successful in the design of healthy lunch bags for students of a school located in a low socioeconomic area. Indeed, for a majority of menus, an optimal compromise seemed to be reached between nutrient composition, satiating potential, palatability, and financial accessibility. In summary, the Quebec experience reveals that childhood obesity is a complex problem that partly results from unsuspected environmental factors that deserve creative solutions to at least partly compensate for their effect. PMID:22332048

  18. The Impact of Model Uncertainty on Spatial Compensation in Active Structural Acoustic Control

    Cabell, Randolph H.; Gibbs, Gary P.; Sprofera, Joseph D.; Clark, Robert L.

    2004-01-01

    Turbulent boundary layer (TBL) noise is considered a primary factor in the interior noise experienced by passengers aboard commercial airliners. There have been numerous investigations of interior noise control devoted to aircraft panels; however, practical realization is a challenge since the physical boundary conditions are uncertain at best. In most prior studies, pinned or clamped boundary conditions have been assumed; however, realistic panels likely display a range of varying boundary conditions between these two limits. Uncertainty in boundary conditions is a challenge for control system designers, both in terms of the compensator implemented and the location of actuators and sensors required to achieve the desired control. The impact of model uncertainties, uncertain boundary conditions in particular, on the selection of actuator and sensor locations for structural acoustic control are considered herein. Results from this research effort indicate that it is possible to optimize the design of actuator and sensor location and aperture, which minimizes the impact of boundary conditions on the desired structural acoustic control.

  19. 1979 national survey of compensation. Paid scientists and engineers engaged in research and development activities

    None

    1979-12-01

    This survey of compensation uses the maturity of age-wage approach, in which salary data are related to years since receipt of degree or chronological age. This report gives the results of the twelfth annual survey, conducted in 1979. Introductory material is given on the sampling plan (survey universe listing, sampling frame, sampling procedures, structure of sample), basic data for survey analysis (establishment data, employee data), entrance rates, trend analysis, geographic analysis, analysis of data (editing of raw data, use of varying axes, arithmetic formulas, median curves), important qualifications concerning survey results, and computation of approximate confidence limits. The bulk of the report contains salary tables of the following types: total survey tables; Bachelor's degree; Master's degree; Doctorate degree; professional degrees; median, curves-supervisory level by degree level, YSBD; nondegreed employees, age; working-as occupation, YSBD; sex, nonsupervisory employees, Bachelor's degree, working-as occupation; trend analysis-five-year identical-company comparisons, median curves; and standard metropolitan statistical area size by establishment size, median curves and census district curves. Employer questionnaire forms are appended. (RWR)

  20. Resting State fMRI Demonstrates a Disturbance of the Cerebello-Cortical Circuit in Essential Tremor.

    Yin, Wenjie; Lin, Wei; Li, Wenbo; Qian, Shusen; Mou, Xin

    2016-05-01

    Individuals with essential tremor (ET) have postural and active movement abnormalities. Disturbances in the cerebello-thalamo-cortical circuit may contribute to the several motor symptoms of ET. Resting state fMRI provides a valuable, noninvasive tool to study intrinsic activation in the human brain, particularly in the brains of individuals with neuropsychiatric diseases. To investigate the low frequency oscillation features of intrinsic activation in ET in this study, we performed a resting state fMRI analysis in 24 patients with ET and 23 healthy controls. The amplitudes of low frequency fluctuation (ALFF) were analyzed. When compared with healthy controls, patients showed significantly enhanced ALFF in the bilateral cerebral cortex, which is related to motor function, including the pre- and post-central gyrus, supplementary motor area and paracentral lobule. The larger ALFF value in the right precentral gyrus is related to a longer duration of tremor. The decreased ALFF in the bilateral cerebellum was also observed in patients. In addition, aberrant ALFF in the right cerebellar tonsil was negatively associated with the duration of tremor. Our findings suggest that abnormalities exist in the intrinsic activation of brain regions in patients with ET. These findings provide noninvasive evidence that supports the hypothesis that the abnormality of intrinsic activity in the cerebello-cerebral cortex pathway could be associated with the motor-related symptoms of ET. Furthermore, the duration of a tremor might relate to the severity of the alterations to the motor system of ET. PMID:26868003

  1. Time-reversal imaging techniques applied to tremor waveforms near Cholame, California to locate tectonic tremor

    Horstmann, T.; Harrington, R. M.; Cochran, E. S.

    2012-12-01

    Frequently, the lack of distinctive phase arrivals makes locating tectonic tremor more challenging than locating earthquakes. Classic location algorithms based on travel times cannot be directly applied because impulsive phase arrivals are often difficult to recognize. Traditional location algorithms are often modified to use phase arrivals identified from stacks of recurring low-frequency events (LFEs) observed within tremor episodes, rather than single events. Stacking the LFE waveforms improves the signal-to-noise ratio for the otherwise non-distinct phase arrivals. In this study, we apply a different method to locate tectonic tremor: a modified time-reversal imaging approach that potentially exploits the information from the entire tremor waveform instead of phase arrivals from individual LFEs. Time reversal imaging uses the waveforms of a given seismic source recorded by multiple seismometers at discrete points on the surface and a 3D velocity model to rebroadcast the waveforms back into the medium to identify the seismic source location. In practice, the method works by reversing the seismograms recorded at each of the stations in time, and back-propagating them from the receiver location individually into the sub-surface as a new source time function. We use a staggered-grid, finite-difference code with 2.5 ms time steps and a grid node spacing of 50 m to compute the rebroadcast wavefield. We calculate the time-dependent curl field at each grid point of the model volume for each back-propagated seismogram. To locate the tremor, we assume that the source time function back-propagated from each individual station produces a similar curl field at the source position. We then cross-correlate the time dependent curl field functions and calculate a median cross-correlation coefficient at each grid point. The highest median cross-correlation coefficient in the model volume is expected to represent the source location. For our analysis, we use the velocity model of

  2. Vocal tremor and vibrato in the same person: acoustic and electromyographic differences.

    Dromey, Christopher; Smith, Marshall E

    2008-09-01

    The goal of this case study was to measure and describe differences between vocal vibrato and essential tremor of the voice in one individual who exhibited both types of modulation. Recordings of spoken and sung vowels produced by the same individual at three effort levels were examined via analysis of acoustic and laryngeal electromyographic (LEMG) signals. Modulation rate, periodicity, and spectral measures of both audio and muscle activation signals revealed generally slower, more prominent, and more regular patterns in sung than in spoken conditions. There was not always a clear correspondence between LEMG and acoustic measures, but both showed differences between the vibrato and tremor of this individual, suggesting differences in the neural bases of these modulations. PMID:17280819

  3. Rare association of central pontine myelinolysis with infantile tremor syndrome.

    Datta, Kalpana; Datta, Supratim; Dutta, Indranil

    2012-01-01

    Central pontine myelinolysis (CPM) is an acute demyelination within the central basis pontis. Though exact mechanism is not known it is seen commonly with rapid correction of hyponatremia and also with pontine ischemia or infarction, demyelinating diseases, pontine neoplasm and different metabolic diseases. We report a rare association of CPM in a patient of Infantile Tremor Syndrom (ITS). ITS is a syndrome of tremor, mental and physical retardation, pigmentary changes of hair and skin and anemia in malnourished children. Though first reported in Indian subcontinent many identical cases were reported from around the world. Our case is a 15 month old child with generalized tremor, mild hepatosplenomegaly with features of grade II malnutrition including skin and hair changes. All the signs and symtoms of tremor improved after treatment with the World Health Organization (WHO) protocol for protein energy malnutrition (PEM) and administration of propranolol without any side effects. PMID:22412274

  4. Rare association of central pontine myelinolysis with infantile tremor syndrome

    Kalpana Datta

    2012-01-01

    Full Text Available Central pontine myelinolysis (CPM is an acute demyelination within the central basis pontis. Though exact mechanism is not known it is seen commonly with rapid correction of hyponatremia and also with pontine ischemia or infarction, demyelinating diseases, pontine neoplasm and different metabolic diseases. We report a rare association of CPM in a patient of Infantile Tremor Syndrom (ITS. ITS is a syndrome of tremor, mental and physical retardation, pigmentary changes of hair and skin and anemia in malnourished children. Though first reported in Indian subcontinent many identical cases were reported from around the world. Our case is a 15 month old child with generalized tremor, mild hepatosplenomegaly with features of grade II malnutrition including skin and hair changes. All the signs and symtoms of tremor improved after treatment with the World Health Organization (WHO protocol for protein energy malnutrition (PEM and administration of propranolol without any side effects.

  5. Quality parameters for a multimodal EEG/EMG/kinematic brain-computer interface (BCI) aiming to suppress neurological tremor in upper limbs.

    Grimaldi, Giuliana; Manto, Mario; Jdaoudi, Yassin

    2013-01-01

    Tremor is the most common movement disorder encountered during daily neurological practice. Tremor in the upper limbs causes functional disability and social inconvenience, impairing daily life activities. The response of tremor to pharmacotherapy is variable. Therefore, a combination of drugs is often required. Surgery is considered when the response to medications is not sufficient. However, about one third of patients are refractory to current treatments. New bioengineering therapies are emerging as possible alternatives. Our study was carried out in the framework of the European project "Tremor" (ICT-2007-224051). The main purpose of this challenging project was to develop and validate a new treatment for upper limb tremor based on the combination of functional electrical stimulation (FES; which has been shown to reduce upper limb tremor) with a brain-computer interface (BCI). A BCI-driven detection of voluntary movement is used to trigger FES in a closed-loop approach. Neurological tremor is detected using a matrix of EMG electrodes and inertial sensors embedded in a wearable textile. The identification of the intentionality of movement is a critical aspect to optimize this complex system. We propose a multimodal detection of the intentionality of movement by fusing signals from EEG, EMG and kinematic sensors (gyroscopes and accelerometry). Parameters of prediction of movement are extracted in order to provide global prediction plots and trigger FES properly. In particular, quality parameters (QPs) for the EEG signals, corticomuscular coherence and event-related desynchronization/synchronization (ERD/ERS) parameters are combined in an original algorithm which takes into account the refractoriness/responsiveness of tremor. A simulation study of the relationship between the threshold of ERD/ERS of artificial EEG traces and the QPs is also provided. Very interestingly, values of QPs were much greater than those obtained for the corticomuscular module alone. PMID

  6. Alumina Encapsulated Strain Gage Not Mechanically Attached To The Substrate, Used to Temperature Compensate an Active High Temperature Gage In A Half-Bridge Configuration

    Piazza, Anthony (Inventor)

    2001-01-01

    A temperature compensation element for a high-temperature strain gage and the method of fabricating the same. Preferably, the element is a "dummy" strain gage not mechanically attached to the substrate. The element is encapsulated in an insulative material and used to compensate an active high-temperature strain gage and wired in a half-bridge configuration. The temperature compensation element and high-temperature strain gage are fabricated using the method of the present invention. This method includes temporarily adhering the element to a heat sink, encapsulated in an insulative material and then removed from the heat sink. Next, the element is either stacked or placed near the active gage. Ideally, the element and the active gage have substantially similar heat transfer and electrical properties.

  7. Influence of a voltage compensation type active superconducting fault current limiter on the transient stability of power system

    Chen, L.; Tang, Y. J.; Shi, J.; Chen, N.; Song, M.; Cheng, S. J.; Hu, Y.; Chen, X. S.

    2009-10-01

    We have proposed a voltage compensation type active superconducting fault current limiter (SFCL). In this paper, the influence of the SFCL on the transient stability of power system is investigated. For the typical one-machine infinite-bus system, the power-angle characteristics of generator with SFCL are studied in different working conditions, and the transient physical process is analyzed. Using MATLAB SIMULINK, the power-angle swing curves are simulated under different current-limiting modes, fault types and fault clearance times. The results show that the proposed SFCL can effectively reduce the transient swing amplitude of rotor and extend the critical clearance time under mode 1, compared with mode 2 and mode 3 having few effects on enhancing the transient stability.

  8. Influence of a voltage compensation type active superconducting fault current limiter on the transient stability of power system

    Chen, L., E-mail: stclchen1982@yahoo.com.c [R and D Center of Applied Superconductivity, Huazhong University of Science and Technology, Wuhan 430074 (China); Tang, Y.J.; Shi, J.; Chen, N.; Song, M.; Cheng, S.J. [R and D Center of Applied Superconductivity, Huazhong University of Science and Technology, Wuhan 430074 (China); Hu, Y.; Chen, X.S. [State Grid Electric Power Research Institute, Wuhan 430074 (China)

    2009-10-15

    We have proposed a voltage compensation type active superconducting fault current limiter (SFCL). In this paper, the influence of the SFCL on the transient stability of power system is investigated. For the typical one-machine infinite-bus system, the power-angle characteristics of generator with SFCL are studied in different working conditions, and the transient physical process is analyzed. Using MATLAB SIMULINK, the power-angle swing curves are simulated under different current-limiting modes, fault types and fault clearance times. The results show that the proposed SFCL can effectively reduce the transient swing amplitude of rotor and extend the critical clearance time under mode 1, compared with mode 2 and mode 3 having few effects on enhancing the transient stability.

  9. Influence of a voltage compensation type active superconducting fault current limiter on the transient stability of power system

    We have proposed a voltage compensation type active superconducting fault current limiter (SFCL). In this paper, the influence of the SFCL on the transient stability of power system is investigated. For the typical one-machine infinite-bus system, the power-angle characteristics of generator with SFCL are studied in different working conditions, and the transient physical process is analyzed. Using MATLAB SIMULINK, the power-angle swing curves are simulated under different current-limiting modes, fault types and fault clearance times. The results show that the proposed SFCL can effectively reduce the transient swing amplitude of rotor and extend the critical clearance time under mode 1, compared with mode 2 and mode 3 having few effects on enhancing the transient stability.

  10. Rare association of central pontine myelinolysis with infantile tremor syndrome

    Kalpana Datta; Supratim Datta; Indranil Dutta

    2012-01-01

    Central pontine myelinolysis (CPM) is an acute demyelination within the central basis pontis. Though exact mechanism is not known it is seen commonly with rapid correction of hyponatremia and also with pontine ischemia or infarction, demyelinating diseases, pontine neoplasm and different metabolic diseases. We report a rare association of CPM in a patient of Infantile Tremor Syndrom (ITS). ITS is a syndrome of tremor, mental and physical retardation, pigmentary changes of hair and skin and an...

  11. Clinical features, assessment and treatment of essential tremor.

    Panicker, J N; Pal, P K

    2003-01-01

    Essential tremor is the most common of the movement disorders, being 20 times more common than Parkinson's Disease. It is characterised by postural and kinetic tremor which maximally affects the hands. It can be assessed by physiological techniques, subjective clinical methods, objective clinical methods and handicap/disability scales. Accelerometry, spirography and handwriting assessment, volumetry and handicap/disability questionnaires are commonly used methods. Primidone and propranolol ar...

  12. Epidemiology and treatment of 23 musicians with task specific tremor

    Lee, André; Furuya, Shinichi; Altenmüller, Eckart

    2014-01-01

    Background Task specific tremors in musicians have been mainly described as primary bowing tremor in string instrumentalists in relatively small sample sizes. Our aim was to describe epidemiology, risk factors, phenomenology and treatment options of this disorder in 23 musicians of different instruments. Methods We included 23 professional musicians (4 female, 19 male; mean age 51.5 ± 11.4 years) with a TSTM. During anamnesis, clinical examination, by mail or via telephone patients were asked...

  13. Effect of BVSI in Static Synchronous Series Compensator (SSSC for the Control of Active Power Flow in a Transmission Line

    Emad Ali Daood

    2013-05-01

    Full Text Available In present a new Static Synchronous Series Compensator (SSSC for the control of active power flow in a transmission line is proposed and its effectiveness is investigated. The new SSSC is based on injecting a voltage in a given line to counter or augment the voltage {&} Power produced by the inductive reactance of the line. The resulting compensator, therefore, emulates the control of transmission line reactance and thus, it assists in control by the power transmission capacity. The voltage to be injected in a line is produced by a Binary Voltage Source Inverter (BVSI. BVSI is an attractive recently proposed Voltage Source Inverter. Its output contains very little harmonics and it utilizes very few dc sources unlike conventional multi-level VSIs. The %phase output of the BVSI is synchronized to the line frequency and its phase is arranged to be in or out of phase with the line reactance drop. The proposed BVSI-SSSC is realized by using three binary proportioned dc sources, which may be appropriately dimensioned capacitors. The resulting output of a BVSI-SSSC is a 15-step ac voltage waveform. The BVSI-SSSC has a sophisticated set of coordinated controlled which ensure: BVSI frequency is in synchronism with the system frequency, firing pulses are regulated for inverter valves to ensure minimum harmonic content, the selection of Modulation Index and arrangement regulates an appropriate phase relationship to create the desired change in the power flow, and adjustment of firing angles to ensure that the capacitors creating dc binary proportioned sources maintain desired charge on them. Armillary controls may be added to create positive system damping through active power control and voltage dependent controllers may be added to limit over and under voltage (charging of capacitors during fault conditions

  14. Nonlinear Mr Model Inversion for Semi-Active Control Enhancement With Open-Loop Force Compensation

    Reader, Daniel Martin

    2009-01-01

    The increased prevalence of semi-active control systems is largely due to the emergence of cost effective commercially available controllable damper technology such as Magneto-Rheological (MR) devices. Unfortunately, MR dampers exhibit highly nonlinear behavior, thus presenting an often over-looked complexity to the control system designer. With regards to controlling dampers, the well-known Skyhook Damping control algorithm has enjoyed great success for both fully active and semi-active co...

  15. Mental Status Test Scores are Inversely Correlated with Tremor Severity: A Study of 161 Elderly Essential Tremor Cases

    Louis, Elan D.; Viner, Amanda S.; Gillman, Arthur

    2012-01-01

    Background There is an increasing awareness that patients with essential tremor (ET) may exhibit non-motor features, including cognitive dysfunction. Yet there are surprisingly few data in ET on the association, if any, between cognitive dysfunction and motor dysfunction (i.e., tremor severity). Establishing links between the cognitive and motor features of ET would imply that the two share a common underlying pathogenic process. Recent neuroimaging data support this notion. Methods ET cases ...

  16. Long-period events and tremor at Popocatepetl volcano (1994-2000) and their broadband characteristics

    Arciniega-Ceballos, A.; Chouet, B.; Dawson, P.

    2003-01-01

    Following an initial phreatic eruption on 21 December 1994, activity at Popocatepetl has been dominated by fumarolic emissions interspersed with more energetic emissions of ashes and gases. A phase of repetitive dome-building and dome-destroying episodes began in March 1996 and is still ongoing at present. We describe the long-period (LP) seismicity accompanying eruptive activity at Popocatepetl from December 1994 through May 2000, using data from a three-component broadband seismometer located 5 km from the summit crater. The broadband records display a variety of signals, with periods ranging in the band 0.04-90 s. Long-period events and tremor with typical dominant periods in the range 0.3-2.0 s are the most characteristic signals observed at Popocatepetl. These signals appear to reflect volumetric sources driven by pressure fluctuations associated with the unsteady transport of gases beneath the crater. Very-long-period (VLP) signals are also observed in association with LP events and tremor. The VLP signals which accompany LP events display Ricker-like wavelets with periods near 36 s, whereas VLP signals associated with tremor waveforms typically show sustained oscillations at periods ranging up to 90 s. The spectra and particle motion patterns remain similar from event to event for the majority of LP and tremor signals analyzed during the time span of this study, suggesting a repeated, non-destructive activation of a common source. Hypocenters determined by phase pick analyses of selected LP events recorded by the seven-station, permanent Popocatepetl short-period network suggest that the majority of these events are confined to a source region in the top 1.5 km below the crater floor. The repetitive occurrences of VLP signals with closely matched waveform characteristics are consistent with a non-destructive reactivation of at least two sources. One source appears to coincide with the main source region of LP seismicity, whereas the second is a deeper source

  17. The Power Quality Compensation Strategy for Power Distribution System Based on Hybrid Parallel Active Power Filters

    Rachid DEHINI

    2010-12-01

    Full Text Available In this paper, the main aim is to confront the performance of shunt active power filter (SAPF and the shunt hybrid active power filter (SHAPF to achieve flexibility and reliability of the filter devices. Both of the two devices used the classical proportional-integral controller for pulse generation to trigger the inventers MOSFET’s. In the adopted hybrid active filter there is a passive power filter with high power rating to filter the low order harmonies and one active filter with low power rating to filter the other high order harmonies. In order to investigate the effectiveness of (SHAPF, the studies have been accomplished using simulation with the MATLAB-SIMULINK. The results show That (SHAPF is more effective than (SAPF, and has lower cost.

  18. Alpha band cortico-muscular coherence occurs in healthy individuals during mechanically-induced tremor.

    Budini, Francesco; McManus, Lara M; Berchicci, Marika; Menotti, Federica; Macaluso, Andrea; Di Russo, Francesco; Lowery, Madeleine M; De Vito, Giuseppe

    2014-01-01

    The present work aimed at investigating the effects of mechanically amplified tremor on cortico-muscular coherence (CMC) in the alpha band. The study of CMC in this specific band is of particular interest because this coherence is usually absent in healthy individuals and it is an aberrant feature in patients affected by pathological tremors; understanding its mechanisms is therefore important. Thirteen healthy volunteers (23±4 years) performed elbow flexor sustained contractions both against a spring load and in isometric conditions at 20% of maximal voluntary isometric contraction (MVC). Spring stiffness was selected to induce instability in the stretch reflex servo loop. 64 EEG channels, surface EMG from the biceps brachii muscle and force were simultaneously recorded. Contractions against the spring resulted in greater fluctuations of the force signal and EMG amplitude compared to isometric conditions (pspring load, CMC in the alpha band was observed in 12 out of 13 volunteers. Partial directed coherence (PDC) revealed an increased information flow in the EMG to EEG direction in the alpha band (p<.05). Therefore, coherence in the alpha band between the sensory-motor cortex and the biceps brachii muscle can be systematically induced in healthy individuals by mechanically amplifying tremor. The increased information flow in the EMG to EEG direction may reflect enhanced afferent activity from the muscle spindles. These results may contribute to the understanding of the presence of alpha band CMC in tremor related pathologies by suggesting that the origin of this phenomenon may not only be at cortical level but may also be affected by spinal circuit loops. PMID:25514444

  19. Alpha band cortico-muscular coherence occurs in healthy individuals during mechanically-induced tremor.

    Francesco Budini

    Full Text Available The present work aimed at investigating the effects of mechanically amplified tremor on cortico-muscular coherence (CMC in the alpha band. The study of CMC in this specific band is of particular interest because this coherence is usually absent in healthy individuals and it is an aberrant feature in patients affected by pathological tremors; understanding its mechanisms is therefore important. Thirteen healthy volunteers (23±4 years performed elbow flexor sustained contractions both against a spring load and in isometric conditions at 20% of maximal voluntary isometric contraction (MVC. Spring stiffness was selected to induce instability in the stretch reflex servo loop. 64 EEG channels, surface EMG from the biceps brachii muscle and force were simultaneously recorded. Contractions against the spring resulted in greater fluctuations of the force signal and EMG amplitude compared to isometric conditions (p<.05. During isometric contractions CMC was systematically found in the beta band and sporadically observed in the alpha band. However, during the contractions against the spring load, CMC in the alpha band was observed in 12 out of 13 volunteers. Partial directed coherence (PDC revealed an increased information flow in the EMG to EEG direction in the alpha band (p<.05. Therefore, coherence in the alpha band between the sensory-motor cortex and the biceps brachii muscle can be systematically induced in healthy individuals by mechanically amplifying tremor. The increased information flow in the EMG to EEG direction may reflect enhanced afferent activity from the muscle spindles. These results may contribute to the understanding of the presence of alpha band CMC in tremor related pathologies by suggesting that the origin of this phenomenon may not only be at cortical level but may also be affected by spinal circuit loops.

  20. Automatic Assessing of Tremor Severity Using Nonlinear Dynamics, Artificial Neural Networks and Neuro-Fuzzy Classifier

    GEMAN, O.

    2014-02-01

    Full Text Available Neurological diseases like Alzheimer, epilepsy, Parkinson's disease, multiple sclerosis and other dementias influence the lives of patients, their families and society. Parkinson's disease (PD is a neurodegenerative disease that occurs due to loss of dopamine, a neurotransmitter and slow destruction of neurons. Brain area affected by progressive destruction of neurons is responsible for controlling movements, and patients with PD reveal rigid and uncontrollable gestures, postural instability, small handwriting and tremor. Commercial activity-promoting gaming systems such as the Nintendo Wii and Xbox Kinect can be used as tools for tremor, gait or other biomedical signals acquisitions. They also can aid for rehabilitation in clinical settings. This paper emphasizes the use of intelligent optical sensors or accelerometers in biomedical signal acquisition, and of the specific nonlinear dynamics parameters or fuzzy logic in Parkinson's disease tremor analysis. Nowadays, there is no screening test for early detection of PD. So, we investigated a method to predict PD, based on the image processing of the handwriting belonging to a candidate of PD. For classification and discrimination between healthy people and PD people we used Artificial Neural Networks (Radial Basis Function - RBF and Multilayer Perceptron - MLP and an Adaptive Neuro-Fuzzy Classifier (ANFC. In general, the results may be expressed as a prognostic (risk degree to contact PD.

  1. Control strategy for three-phase four-wire PWM converter of integrated voltage compensation type active SFCL

    The integrated voltage compensation type active superconducting fault current limiter (SFCL) is composed of three air-core superconducting transformers and a three-phase four-wire PWM converter. In order to realize the current-limiting characteristics of the integrated active SFCL, it is needed to control the three-phase four-wire PWM converter flexibly and reasonably. Thereby, the control strategy for the converter is analyzed in this paper. In dq0 reference frame, the mathematical model of the converter is founded. The double-loop control strategy, consisting of voltage outer loop and current inner loop, is presented. Moreover, the voltage balance control for the split DC link capacitors is also considered. Using MATLAB, the simulation model of the integrated active SFCL is built. According to the simulation results, it is known that, the presented control strategy is feasible and valid, and the converter can work well under unsymmetrical and symmetrical fault conditions, and then the fault current can be limited quickly and effectively.

  2. Aborted eruptions at Mt. Etna (Italy) in spring 2007 unveiled by an integrated study of gas emission and volcanic tremor

    Falsaperla, S.; Behncke, B.; Giammanco, S.; Neri, M.; Langer, H.; Pecora, E.; Salerno, G.

    2012-04-01

    In spring 2007, a sequence of paroxysmal episodes took place at the Southeast Crater of Mt. Etna, Italy. Eruptive activity, characterised by Strombolian explosions, lava fountains, emission of lava flows and tephra, were all associated with an outstanding increase in the amplitude of volcanic tremor. In periods of quiescence between the eruptive episodes, recurring phases of seismic unrest were observed in forms of small temporary enhancements of the volcanic tremor amplitude, even though none of them culminated in eruptive activity. Here, we present the results of an integrated geophysical and geochemical data analysis encompassing records of volcanic tremor, thermal data, plume SO2 flux and radon over two months. We conclude that between February and April 2007, magma triggered repeated episodes of gas pulses and rock fracturing, but failed to reach the surface. Our multidisciplinary study allowed us to unveil these 'aborted' eruptions by investigating the long-temporal evolution of gas measurements along with seismic radiation. Short-term changes were additionally highlighted using a method of pattern classification based on Kohonen Maps and Fuzzy Clustering applied to volcanic tremor and radon data.

  3. Non-volcanic tremor in Cascadia: Segmented along strike, anti-correlated with earthquakes, and offset from the locked zone

    Boyarko, D. C.; Brudzinski, M. R.; Allen, R. M.; Porritt, R. W.

    2009-12-01

    Episodic tremor and slip (ETS), the spatial and temporal correlation of slow slip events monitored by GPS observations and non-volcanic tremor (NVT) monitored by seismic signals, is a recently discovered type of deformation thought to occur immediately down-dip from the seismogenic zone along several subduction margins. Owing to the wealth of geodetic and seismic observatories in Washington and Vancouver Island, ETS in northern Cascadia has been the subject of numerous studies over the last half-decade, while the rest of the margin has received considerably less attention. We will present a comprehensive review of tremor activity along the southern Cascadia margin between 2005 and 2007 using both semi-automated and fully-automated source location routines. We will also utilize the fully-automated routine to expand the scope to include the entire Cascadia margin and episodes after 2007, including the great 2008 ETS episode which spans nearly the entire length of the margin. The along-strike length of activity of an individual episode varies between 30 to 900 km, evolving in a very complex manner with periods of steady and halting migration and frequent along-strike jumps (30-600 km). The initiation and termination points of laterally-continuous tremor activity appear to be repeatable features between NVT episodes which support the hypothesis of segmentation within the ETS zone. The distribution of tremor epicenters occur within a narrow band confined by the surface projections of the 30 and 40 km contours of the subducting plate interface. We find the tremor zone is spatially offset by as much as 50 km down-dip from the thermally- and geodetically-defined transition zone, which may decrease the efficiency of stress transmission and slip propagation during either transient or seismogenic deformation episodes. Intriguingly, NVT activity is spatially anti-correlated with local seismicity, suggesting the two processes occur mutually exclusive of one another. We propose

  4. 78 FR 68780 - Treatment of Income From Indian Fishing Rights-Related Activity as Compensation

    2013-11-15

    ... Internal Revenue Service 26 CFR Part 1 RIN-1545-BL61 Treatment of Income From Indian Fishing Rights-Related... adopted before passage of the Federal income tax, they often do not expressly address the question of whether income derived by Indians and ITGs from protected fishing activities is exempt from taxation....

  5. Questioning Compensation

    2011-01-01

    Transparent management and open information needed for the fund set up to compensate victims of the 2008 Sanlu milk scandal Almost three years after the Sanlu milk scandal that caused thousands of infants in China to develop urinary disease after drinking melamine

  6. Active Agents, Passive Principals: Does High-Powered CEO Compensation Really Improve Incentives

    Dow, James; Raposo, Clara

    2002-01-01

    In this Paper we use agency theory to study the active role of the CEO in the formulation of corporate strategy. We allow the agent (CEO) to play a role in defining the parameters of the agency problem, in an incomplete contracting model in which the agent can be rewarded based only on financial performance. Contracts can be renegotiated depending on the proposed strategy. We argue that CEOs will have an incentive to propose difficult, ambitious strategies for change. The principal (the share...

  7. HARMONIC CURRENT COMPENSATION IN SELF EXCITED INDUCTION GENERATOR USING ACTIVE FILTER

    K, Premalatha

    2015-01-01

    The Self-Excited Induction Generator (SEIG) is more suitable for wind energy conversion systems in remotely located areas. The system consists of squirrel cage induction machine coupled with wind turbine through a gear box, Voltage Source Converter (VSC) as active power filter, fixed capacitor bank and diode rectifier with RL load.  SEIG feeding nonlinear load causes current harmonics in the generator current. This paper focuses on minimizing the current harmonics to some extent using shunt A...

  8. Driving Method for Compensating Reliability Problem of Hydrogenated Amorphous Silicon Thin Film Transistors and Image Sticking Phenomenon in Active Matrix Organic Light-Emitting Diode Displays

    Shin, Min-Seok; Jo, Yun-Rae; Kwon, Oh-Kyong

    2011-03-01

    In this paper, we propose a driving method for compensating the electrical instability of hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs) and the luminance degradation of organic light-emitting diode (OLED) devices for large active matrix OLED (AMOLED) displays. The proposed driving method senses the electrical characteristics of a-Si:H TFTs and OLEDs using current integrators and compensates them by an external compensation method. Threshold voltage shift is controlled a using negative bias voltage. After applying the proposed driving method, the measured error of the maximum emission current ranges from -1.23 to +1.59 least significant bit (LSB) of a 10-bit gray scale under the threshold voltage shift ranging from -0.16 to 0.17 V.

  9. Gradient Descent Learning for Utility Current Compensation using Active Regenerative PWM Filter

    R. Balamurugan

    2011-01-01

    Full Text Available Problem statement: Harmonic analysis is a primary matter of power quality assessment. Its main intention is to check the utility whether it is delivering the loads without any deviations in voltages and currents. The problem is due to proliferation of Electronic converters and power electronics which gave birth to numerous new applications, offering unmatched comfort to the customers. Approach: Harmonics should be maintained within the limits said in standards like IEEE 519 and others such as IEEE 1159 for safeguarding the utility. This was provided by many mitigation technologies like passive, shunt and series filtering, active conditioners, but they were lack of some demerits like huge cost, many controllers and circuit components. So for controlling the harmonic loads the converter with four quadrant characteristics was implemented and this converter act as shunt active filter as well as rectifier simultaneously without any additional circuitry. For having better harmonic reduction in addition, many controllers like p-q Theorem based controller, Fuzzy and gradient descent based neural network is also used. Results: The simulation results gives the compared source current wave forms for various controllers with individual harmonic mitigations. Conclusion: The pure utility current is obtained by using this intelligent neural filter without any additional components and without any extra controllers than the conventional methods.

  10. Linking Essential Tremor to the Cerebellum: Clinical Evidence.

    Benito-León, Julián; Labiano-Fontcuberta, Andrés

    2016-06-01

    Essential tremor (ET) might be a family of diseases unified by the presence of kinetic tremor, but also showing etiological, pathological, and clinical heterogeneity. In this review, we will describe the most significant clinical evidence, which suggests that ET is linked to the cerebellum. Data for this review were identified by searching PUBMED (January 1966 to May 2015) crossing the terms "essential tremor" (ET) and "cerebellum," which yielded 201 entries, 11 of which included the term "cerebellum" in the article title. This was supplemented by articles in the author's files that pertained to this topic. The wide spectrum of clinical features of ET that suggest that it originates as a cerebellar or cerebellar outflow problem include the presence of intentional tremor, gait and balance abnormalities, subtle features of dysarthria, and oculomotor abnormalities, as well as deficits in eye-hand coordination, motor learning deficits, incoordination during spiral drawing task, abnormalities in motor timing and visual reaction time, impairment of social abilities, improvement in tremor after cerebellar stroke, efficacy of deep brain stimulation (which blocks cerebellar outflow), and cognitive dysfunction. It is unlikely, however, that cerebellar dysfunction, per se, fully explains ET-associated dementia, because the cognitive deficits that have been described in patients with cerebellar lesions are generally mild. Overall, a variety of clinical findings suggest that in at least a sizable proportion of patients with ET, there is an underlying abnormality of the cerebellum and/or its pathways. PMID:26521074

  11. Genetics Home Reference: fragile X-associated tremor/ataxia syndrome

    ... Home Health Conditions FXTAS fragile X-associated tremor/ataxia syndrome Enable Javascript to view the expand/collapse ... All Close All Description Fragile X-associated tremor/ataxia syndrome ( FXTAS ) is characterized by problems with movement ...

  12. Space active optics: in situ compensation of lightweight primary mirrors' deformations

    Laslandes, M.; Ferrari, M.; Hugot, E.; Lemaitre, G.

    2010-12-01

    The need for both high quality images and light structures is a constant concern in the conception of space telescopes. The goal here is to determine how an active optics system could be embarked on a satellite in order to correct the wave front deformations of the optical train. The optical aberrations appearing in a space environment are due to mirrors' deformations, with three main origins: the thermal variations, the weightlessness conditions and the use of large weightlighted primary mirrors. We are developing a model of deformable mirror as minimalist as possible, especially in term of number of actuators, which is able to correct the first Zernike polynomials in a specified range of amplitude and precision. Flight constraints as weight, volume and power consumption are considered. Firstly, such a system is designed according to the equations from the elasticity theory: we determine the geometrical and mechanical characteristics of the mirror, the location of the forces to be applied and the way to apply them. Then the concept is validated with a Finite Element Analysis, allowing to optimize the system by taking into account parameters absent from the theory. At the end, the mirror will be realized and characterized in a representative optical configuration.

  13. Tremor irregularity, torque steadiness and rate of force development in Parkinson's disease

    Rose, Martin Høyer; Løkkegaard, Annemette; Sonne-Holm, Stig;

    2013-01-01

    idiopathic PD and 15 neurologically healthy matched controls performed isometric maximal contractions (extension/flexion) as well as steady submaximal and powerful isometric knee extensions. The patients with PD showed decreased isometric tremor irregularity. Torque steadiness was reduced in PD and the...... patients had increased muscle co-activation. A markedly lower RFD was found in PD and the decreased RFD correlated with reduced agonist muscle activation. Furthermore, patient RFD correlated with the Movement-Disorder-Society-Unified-Parkinson's-Disease-Rating-Scale 3 (motor part) scores. We concluded that...

  14. Neural network compensation of semi-active control for magneto-rheological suspension with time delay uncertainty

    This study presents a new intelligent control method, human-simulated intelligent control (HSIC) based on the sensory motor intelligent schema (SMIS), for a magneto-rheological (MR) suspension system considering the time delay uncertainty of MR dampers. After formulating the full car dynamic model featuring four MR dampers, the HSIC based on eight SMIS is derived. A neural network model is proposed to compensate for the uncertain time delay of the MR dampers. The HSIC based on SMIS is then experimentally realized for the manufactured full vehicle MR suspension system on the basis of the dSPACE platform. Its performance is evaluated and compared under various road conditions and presented in both time and frequency domains. The results show that significant gains are made in the improvement of vehicle performance. Results include a reduction of over 35% in the acceleration peak-to-peak value of a sprung mass over a bumpy road and a reduction of over 24% in the root-mean-square (RMS) sprung mass acceleration over a random road as compared to passive suspension with typical original equipment (OE) shock absorbers. In addition, the semi-active full vehicle system via HSIC based on SMIS provides better isolation than that via the original HSIC, which can avoid the effect of the time delay uncertainty of the MR dampers

  15. Dynamic Variability of Isometric Action Tremor in Precision Pinching

    Tim Eakin

    2012-01-01

    Full Text Available Evolutionary development of isometric force impulse frequencies, power, and the directional concordance of changes in oscillatory tremor during performance of a two-digit force regulation task was examined. Analyses compared a patient group having tremor confounding volitional force regulation with a control group having no neuropathological diagnosis. Dependent variables for tremor varied temporally and spatially, both within individual trials and across trials, across individuals, across groups, and between digits. Particularly striking findings were magnitude increases during approaches to cue markers and shifts in the concordance phase from pinching toward rigid sway patterns as the magnitude increased. Magnitudes were significantly different among trace line segments of the task and were characterized by differences in relative force required and by the task progress with respect to cue markers for beginning, reversing force change direction, or task termination. The main systematic differences occurred during cue marker approach and were independent of trial sequence order.

  16. Essential Palatal Tremor Managed by Cognitive Behavioral Therapy

    Tomohisa Kitamura

    2015-01-01

    Full Text Available Background. Essential palatal tremor is a disorder of unknown etiology involving involuntary movement of the uvula and soft palate. Treatment attempts including drugs or surgery have been conducted to cease the rhythmical movement. Case Report. A 55-year-old female visited our department complaining of a sudden, noticeable, intermittent, and rhythmical clicking noise in her throat for five years. Oral examination revealed rhythmical contractions of the soft palate with clicking at the frequency of 120 per min. Magnetic resonance imaging (MRI examination of the brain performed after consulting with the department of neuropathic internal medicine showed no abnormalities. Thus, essential palatal tremor was diagnosed. The symptoms improved with cognitive behavioral therapy without drugs or surgical treatments. The patient is now able to stop the rhythmical movement voluntarily. Discussion. Cognitive behavioral therapy might be suitable as first-line therapy for essential palatal tremor because the therapy is noninvasive.

  17. Central beta-adrenoceptors can modulate 5-hydroxytryptamine-induced tremor in rats.

    Hallberg, H.

    1986-01-01

    The effects of two beta 2-adrenoceptor agonists with different lipophilicities were studied on tremor induced by L-5-hydroxytryptophan (L-5-HTP) in pargyline- and carbidopa-pretreated rats. Tremor was recorded and analysed by an objective method based on accelerometry. Clenbuterol, a lipophilic beta 2-selective agonist, dose-dependently enhanced tremor intensity, whereas the hydrophilic beta 2-agonist terbutaline had no effect. The clenbuterol-induced enhancement of tremor was completely abol...

  18. The approximate entropy of the electromyographic signals of tremor correlates with the osmotic fragility of human erythrocytes

    Penha-Silva Nilson

    2010-06-01

    Full Text Available Abstract Background The main problem of tremor is the damage caused to the quality of the life of patients, especially those at more advanced ages. There is not a consensus yet about the origins of this disorder, but it can be examined in the correlations between the biological signs of aging and the tremor characteristics. Methods This work sought correlations between the osmotic fragility of erythrocytes and features extracted from electromyographic (EMG activity resulting from physiological tremor in healthy patients (N = 44 at different ages (24-87 years. The osmotic fragility was spectrophotometrically evaluated by the dependence of hemolysis, provided by the absorbance in 540 nm (A54o, on the concentration of NaCl. The data were adjusted to curves of sigmoidal regression and characterized by the half transition point (H50, amplitude of lysis transition (dx and values of A540 in the curve regions that characterize the presence of lysed (A1 and preserved erythrocytes (A2. The approximate entropy was estimated from EMG signals detected from the extensor carpi ulnaris muscle during the movement of the hand of subjects holding up a laser pen towards an Archimedes spiral, fixed in a whiteboard. The evaluations were carried out with the laser pen at rest, at the center of the spiral, and in movement from the center to the outside and from outside to the center. The correlations among the parameters of osmotic fragility, tremor and age were tested. Results Negative correlations with age were found for A1 and dx. With the hand at rest, a positive correlation with H50 was found for the approximate entropy. Negative correlations with H50 were found for the entropy with the hand in movement, as from the center to the outside or from the outside to the center of the spiral. Conclusion In healthy individuals, the increase in the erythrocyte osmotic fragility was associated with a decrease in the approximate entropy for rest tremor and with an increase

  19. Laryngoscopy evaluation protocol for the differentiation of essential and dystonic voice tremor

    Bruno Teixeira de Moraes

    2016-02-01

    Full Text Available ABSTRACT INTRODUCTION: Although syndromes that cause voice tremor have singular characteristics, the differential diagnosis of these diseases is a challenge because of the overlap of the existing signs and symptoms. OBJECTIVE: To develop a task-specific protocol to assess voice tremor by means of nasofibrolaryngoscopy and to identify those tasks that can distinguish between essential and dystonic tremor syndromes. METHODS: Cross-sectional study. The transnasal fiberoptic laryngoscopy protocol, which consisted of the assessment of palate, pharynx and larynx tremor during the performance of several vocal and non-vocal tasks with distinct phenomenological characteristics, was applied to 19 patients with voice tremor. Patients were diagnosed with essential or dystonic tremor according to the phenomenological characterization of each group. Once they were classified, the tasks associated with the presence of tremor in each syndrome were identified. RESULTS: The tasks that significantly contributed to the differential diagnosis between essential and dystonic tremor were /s/ production, continuous whistling and reduction of tremor in falsetto. These tasks were phenomenologically different with respect to the presence of tremor in the two syndromes. CONCLUSION: The protocol of specific tasks by means of transnasal fiberoptic laryngoscopy is a viable method to differentiate between essential and dystonic voice tremor syndromes through the following tasks: /s/ production, continuous whistling and reduction of tremor in falsetto.

  20. TYPES OF TREMOR IN PATIENTS WITH CEREBROVASCULAR DISEASES AND CARDIOVASCULAR EVENTS

    Petrov Igor; Mulic Mersudin; Antonio Georgiev

    2016-01-01

    Introduction: Tremor can occur as a part of the clinical feature of cerebrovascular diseases. Many patients with cerebral stroke have cardiovascular diseases as a comorbidity or complication of stroke; sometimes cardiovascular events can lead to embolic stroke. Aim: To present types of tremor in patients with cerebrovascular diseases and cardiovascular events and diabetes mellitus type 2, clinical characteristics of tremor and investigations used. Materia...

  1. Sliding mode controller for four leg shunt active power filter to eliminating zero sequence current, compensating harmonics and reactive power with fixed switching frequency

    Chebabhi Ali

    2015-01-01

    Full Text Available In this paper, the four leg inverter controlled by the three dimensional space vector modulation (3D SVM is used as the shunt active power filter (SAPF for compensating the three phase four wire electrical network, by using the four leg inverter with 3D SVM advantages to eliminated zero sequence current, fixed switching frequency of inverter switches, and reduced switching losses. This four leg inverter is employed as shunt active power filter to minimizing harmonic currents, reducing magnitude of neutral wire current, eliminating zero sequence current caused by nonlinear single phase loads and compensating reactive power, and a nonlinear sliding mode control technique (SMC is proposed for harmonic currents and DC bus voltage control to improve the performances of the three phase four wire four leg shunt active power filter based on Synchronous Reference Frame (SRF theory in the dq0 axes, and to decoupling the four leg SAPF mathematical model.

  2. Intracellular shunting of O2− contributes to charge compensation and preservation of neutrophil respiratory burst in the absence of voltage-gated proton channel activity

    Proton efflux via voltage-gated proton channels (Hv1) is considered to mediate the charge compensation necessary to preserve NADPH oxidase activity during the respiratory burst. Using the Hv1 inhibitor Zn2+, we found that the PMA-induced respiratory burst of human neutrophils is inhibited when assessed as extracellular production of O2− and H2O2, in accordance with literature studies, but, surprisingly, unaffected when measured as oxygen consumption or total (extracellular plus intracellular) H2O2 production. Furthermore, we show that inhibiting Hv1 with Zn2+ results in an increased production of intracellular ROS. Similar results, i.e. decreased extracellular and increased intracellular ROS production, were obtained using a human granulocyte-like cell line with severely impaired Hv1 expression. Acidic extracellular pH, which dampens proton efflux, also augmented intracellular production of H2O2. Zinc caused an increase in the rate but not in the extent of depolarization and cytosolic acidification indicating that mechanisms other than proton efflux take part in charge compensation. Our results suggest a hitherto unpredicted mechanism of charge compensation whereby, in the absence of proton efflux, part of O2− generated within gp91phox in the plasma membrane is shunted intracellularly down electrochemical gradient to dampen excessive depolarization. This would preserve NADPH oxidase activity under conditions such as the inflammatory exudate in which the acidic pH hinders charge compensation by proton efflux. Highlights: • Neutrophils’ respiratory burst is not inhibited by the H+ channel inhibitor Zn2+. • Intracellular production of O2− and H2O2 is increased in the presence of Zn2+. • Intracellular H2O2 production is increased in H+ channels knock-down cells. • Zn2+ increases the rate but not the extent of depolarization and pHi decrease. • Intracellular shunting of O2− contributes to charge compensation in neutrophils

  3. Deep brain stimulation for vocal tremor: a comprehensive, multidisciplinary methodology.

    Ho, Allen L; Erickson-Direnzo, Elizabeth; Pendharkar, Arjun V; Sung, Chih-Kwang; Halpern, Casey H

    2015-06-01

    Tremulous voice is a characteristic feature of a multitude of movement disorders, but when it occurs in individuals diagnosed with essential tremor, it is referred to as essential vocal tremor (EVT). For individuals with EVT, their tremulous voice is associated with significant social embarrassment and in severe cases may result in the discontinuation of employment and hobbies. Management of EVT is extremely difficult, and current behavioral and medical interventions for vocal tremor result in suboptimal outcomes. Deep brain stimulation (DBS) has been proposed as a potential therapeutic avenue for EVT, but few studies can be identified that have systematically examined improvements in EVT following DBS. The authors describe a case of awake bilateral DBS targeting the ventral intermediate nucleus for a patient suffering from severe voice and arm tremor. They also present their comprehensive, multidisciplinary methodology for definitive treatment of EVT via DBS. To the authors' knowledge, this is the first time comprehensive intraoperative voice evaluation has been used to guide microelectrode/stimulator placement, as well as the first time that standard pre- and post-DBS assessments have been conducted, demonstrating the efficacy of this tailored DBS approach. PMID:26030706

  4. A Novel LTPS-TFT Pixel Circuit to Compensate the Electronic Degradation for Active-Matrix Organic Light-Emitting Diode Displays

    Ching-Lin Fan; Fan-Ping Tseng; Hui-Lung Lai; Bo-Jhang Sun; Kuang-Chi Chao; Yi-Chiung Chen

    2013-01-01

    A novel pixel driving circuit for active-matrix organic light-emitting diode (AMOLED) displays with low-temperature polycrystalline-silicon thin-film transistors (LTPS-TFTs) is studied. The proposed compensation pixel circuit is driven by voltage programming scheme, which is composed of five TFTs and one capacitor, and has been certified to provide uniform output current by the Automatic Integrated Circuit Modeling Simulation Program with Integrated Circuit Emphasis (AIM-SPICE) simulator. The...

  5. Pattern classification of volcanic tremor data related to the 2007-2012 Mt. Etna (Italy) eruptive episodes

    Spampinato, Salvatore; Falsaperla, Susanna; Langer, Horst; Messina, Alfio

    2013-04-01

    From March 2007 to April 2012 one of the main craters of Mt. Etna volcano, the South East Crater, was frequently active with spectacular, even though low dangerous, eruptions mainly in form of lava fountains. Thirty-three eruptive episodes occurred at that crater, encompassing thirty-two paroxysmal lava fountains (seven in 2007-2008 and twenty-five in 2011-2012), and a lava emission, started on 13 May 2008 and ended on 6 July 2009, along the upper eastern flank of the volcano. From the seismic point of view, the onset of all these eruptions was heralded by changes in the spectral characteristics of volcanic tremor recorded by digital broadband stations, which permanently monitor the volcanic region. On the basis of the tremor data collected between 2007 and 2009, some of us (Messina and Langer) developed a software which, combining unsupervised classification methods based on Kohonen Maps and the fuzzy cluster analysis, allows to identify transitions from pre-eruptive to eruptive activity through the classification of the tremor characteristics (i.e., amplitude and frequency content). Since 2010 an on-line version of this software is adopted at the Osservatorio Etneo as one of the automatic alerting tools to identify early stages of eruptive events. The software carries out the analysis of the continuous data stream of two key seismic stations, for which reference datasets were elaborated taking into account the tremor data recorded during the eruptive episodes from 2007 to 2009. The numerous paroxysmal eruptions occurred in 2011-2012 and the improved network density, in particular on the summit crater area, after 2009, lead us to extend the application of automatic volcanic tremor classification by using a larger number of stations at different elevation and distance from the summit craters. Datasets have been formed for the new stations, while for the previous key stations, the reference datasets were updated adding new patterns of the tremor signal. We discuss

  6. Seismic tremor associated with the degassing of the Gorely volcano in 2013-2014

    Abramenkov, Sergey; Shapiro, Nikolai; Koulakov, Ivan; Abkadyirov, Ilyas; Frank, William; Jakovlev, Andrey

    2016-04-01

    We present observation of seismic activity associated with the strong degassing episode occurred in Gorely volcano (Kamchatka, Russia) in 2013-2014. We use the data of a temporary network of 21 broadband seismographs that operated on this volcano during one year. During the considered period, the volcanic activity mainly consisted of sustained gas emission that produced strong volcanic tremor well recorded by seismic stations. A close analysis of this tremor revealed that it was composed of many very frequent pulses of seismic energy. The corresponding signals had an emergent character without clear arrivals of P and S waves, which is typical for burst of Long Period (LP) events on many volcanoes. We developed a source-scanning algorithm based on summation of seismogram envelopes for automatic detection and location of these LP events. With the help of this method, numerous events originated from the vicinity of the main crater were detected. In a next step, we cross-correlated the waveforms of the detected LP events and found that a large part of them can be regrouped in families of seismic multiplets. This indicates that the increased pressure produced by the volcanic degassing activates a set of non-destructive shallow seismic sources in vicinity of the main volcanic conduit. The developed analysis of continuous seismic records was used to characterize the spatio-temporal evolution of these sources.

  7. Listening carefully: unique observations of harmonic tremor at Lascar volcano, Chile

    M. Hellweg

    1999-06-01

    Full Text Available During the deployment of Proyecto de Investigación Sismológica de la Cordillera Occidental 94 (PISCO'94 in the Atacama Desert of Northern Chile, a broadband seismic station and a network of three short-period three-component stations were installed around the active volcano Lascar. The resulting data set includes a sequence of harmonic tremor with a fundamental at about 0.63 Hz and up to 30 overtones lasting 18 h. Power spectra and spectrograms of Lascar's harmonic tremor from the various stations demonstrate that the frequencies recorded cannot be explained as path effects, and must therefore be attributed to mechanisms at or near the source. The polarization of the wavefield cannot simply be explained as the propagation of any of the classical types of seismic waves, thus we apply new methods to the data to investigate the narrowband signals of the harmonic peaks. While the amplitude characteristics of these signals cannot be correlated across the network, frequency characteristics of the harmonic wavefield are consistent across stations and components. The tremor's fundamental frequency changes at the same time at all stations, indicating that such changes must be caused at the source. In addition, a change in the frequency of the fundamental, f1, is reflected exactly in the frequencies of the overtones, nf1 and peak-broadening in the power spectrum is the result of shifts in the fundamental frequency. It is therefore unlikely that the overtones are produced as resonances. This spectral behavior indicates rather that the source is some resonance at a single frequency within the magma, magma/gas or gas parts of the volcano whose amplitude exceeds the range for which the assumptions of linear acoustics are valid.

  8. Seed reserves partition and light compensation point of mahogany (Swietenia macrophylla King seedlings growth under low photosynthetic active radiation

    José Pires de Lemos Filho

    1998-01-01

    Full Text Available The aim of this study was to verify the dry mass partition of the seed reserves during the initial growth of Swietenia macrophylla seedlings, in the dark, and at low levels of photosynthetically active radiation: 0.125; 3.12 and 52 µ mol.m-2.s-1. After 50 days, the dry mass of the seed reserves did not differ with treatments, but the total dry mass and leaf area were higher in the seedlings under higher light treatment. No difference in root/shoot ratio was observed between treatments, but the leaf area ratio was lower at higher light. Only the seedlings grown at 52 µ mol.m-2.s-1 showed a positive dry mass increase in relation to the mobilized seed reserves. With the values of the net increase of the seedling mass, a linear equation was adjusted in relation to the light levels, permitting to determine 3.76 µ mol.m-2.s-1 as the seedling light compensation point. These results explain the shade tolerance of the S. macrophylla seedlings.O objetivo deste estudo foi verificar a partição da massa seca das reservas das sementes durante o crescimento de plântulas de Sietenia macrophylla , no escuro e sob baixos níveis de radiação fotossintéticamente ativa: 0,125; 3,12 e 52µ mol.m-2.s-1. Após 50 dias a massa seca das reservas das sementes não diferiram com os diferentes tratamentos de luz. Não foi observado diferenças na razão raíz/parte aérea, mas a razão área foliar foi menor no maior nível de luz. Somente as plântulas crescidas a 52 µ mol.m-2.s-1 mostraram um incremento positivo na massa seca em relação às reservas mobilizadas da semente. Uma equação linear foi ajustada entre o incremento líquido de massa seca das plântulas e níveis de luz, permitindo determinar 3,76 µ mol.m-2.s-1 como ponto de compensação de luz das plântulas. Esses resultados explicam a tolerância à sombra das plântulas de S. macrophylla

  9. Characteristics of volcanic tremor accompanying the September 24th, 1986 explosive eruption of Mt. Etna (Italy

    R. Cristofolini

    1996-06-01

    Full Text Available Features of the volcanic tremor recorded before, during and after the eruptive event which occurred at Mt. Etna on September 24th 1986, are described. The whole eruption was particularly short in time (about eight hours and characterized by an extremely violent explosive activity with lava fountains a few hundred meters high. As the complete record of the seismic signals generated during the whole eruptive episode was available, a detailed spectral analysis of the volcanic tremor recorded at four stations, located at increasing distance from the summit of the volcano, was carried out. Fourier analysis, that was performed using temporal windows of about 11 min in duration, pointed to some large fluctuations of the overall spectral amplitude, as well as some frequency variations of the dominant spectral peaks. The ratio of the overall spectral amplitude recorded at the highest station and at the peripheral ones, was calculated in the two spectral bands 1.0-2.5 and 2.6-6.0 Hz, respectively. The significant contribution of energy at low frequency values supports the hypothesis of a subvertical planar source, which was active during the paroxysmal stage of the eruption. Such results are also supported by the analysis of the attenuation function of the spectral amplitude.

  10. Using active power filter to compensate the current component of asymmetrical non-linear load in the four wire network

    Власенко, Руслан Володимирович; Бялобржеський, Олексій Володимирович

    2016-01-01

    Electricity quality improving is extremely relevant nowadays. With such industrial loads as induction motors, induction furnaces, welding machines, controlled or uncontrolled rectifiers, frequency converters and others reactive power, harmonics and unbalance are generated in power grid. Reactive power, higher harmonic currents and asymmetry loads influence the functioning of electric devices and electrical mains. An effective technical solution is the use of new compensating devices, that is ...

  11. Regular and stochastic behavior of Parkinsonian pathological tremor signals

    Yulmetyev, R M; Panischev, O Y; Hänggi, P; Timashev, S F; Vstovsky, G V; Yulmetyev, Renat M.; Demin, Sergey A.; Panischev, Oleg Yu.; H\\"anggi, Peter; Timashev, Serge F.; Vstovsky, Grigoriy V.

    2006-01-01

    Regular and stochastic behavior in the time series of Parkinsonian pathological tremor velocity is studied on the basis of the statistical theory of discrete non-Markov stochastic processes and flicker-noise spectroscopy. We have developed a new method of analyzing and diagnosing Parkinson's disease (PD) by taking into consideration discreteness, fluctuations, long- and short-range correlations, regular and stochastic behavior, Markov and non-Markov effects and dynamic alternation of relaxation modes in the initial time signals. The spectrum of the statistical non-Markovity parameter reflects Markovity and non-Markovity in the initial time series of tremor. The relaxation and kinetic parameters used in the method allow us to estimate the relaxation scales of diverse scenarios of the time signals produced by the patient in various dynamic states. The local time behavior of the initial time correlation function and the first point of the non-Markovity parameter give detailed information about the variation of p...

  12. S-wave triggering of tremor beneath the Parkfield, California, section of the San Andreas fault by the 2011 Tohoku, Japan earthquake: observations and theory

    Hill, David P.; Peng, Zhigang; Shelly, David R.; Aiken, Chastity

    2013-01-01

    The dynamic stresses that are associated with the energetic seismic waves generated by the Mw 9.0 Tohoku earthquake off the northeast coast of Japan triggered bursts of tectonic tremor beneath the Parkfield section of the San Andreas fault (SAF) at an epicentral distance of ∼8200  km. The onset of tremor begins midway through the ∼100‐s‐period S‐wave arrival, with a minor burst coinciding with the SHSH arrival, as recorded on the nearby broadband seismic station PKD. A more pronounced burst coincides with the Love arrival, followed by a series of impulsive tremor bursts apparently modulated by the 20‐ to 30‐s‐period Rayleigh wave. The triggered tremor was located at depths between 20 and 30 km beneath the surface trace of the fault, with the burst coincident with the S wave centered beneath the fault 30 km northwest of Parkfield. Most of the subsequent activity, including the tremor coincident with the SHSH arrival, was concentrated beneath a stretch of the fault extending from 10 to 40 km southeast of Parkfield. The seismic waves from the Tohoku epicenter form a horizontal incidence angle of ∼14°, with respect to the local strike of the SAF. Computed peak dynamic Coulomb stresses on the fault at tremor depths are in the 0.7–10 kPa range. The apparent modulation of tremor bursts by the small, strike‐parallel Rayleigh‐wave stresses (∼0.7  kPa) is likely enabled by pore pressure variations driven by the Rayleigh‐wave dilatational stress. These results are consistent with the strike‐parallel dynamic stresses (δτs) associated with the S, SHSH, and surface‐wave phases triggering small increments of dextral slip on the fault with a low friction (μ∼0.2). The vertical dynamic stresses δτd do not trigger tremor with vertical or oblique slip under this simple Coulomb failure model.

  13. Clonazepam in the treatment of essential palatal tremors

    Aditya A Pandurangi; Nayak, Raghavendra B.; Govind S Bhogale; Patil, Nanasaheb M.; Sameeran S Chate; Sunny Chattopadhaya

    2012-01-01

    Essential Palatal tremor (EPT) is a rare disorder presenting as unilateral or bilateral rhythmic involuntary movements of the soft palate. There is mention of the utility of benzodiazepines like clonazepam probably because of their gamma amino butyric acid (GABA) agonistic property. But no reports are available for the same. Here we report a 30-year old married female patient who presented with the complaints of pain in the lower part of face, behind the ears, back side of neck and clicking s...

  14. Relationship Between Essential Tremor and Cerebellar Dysfunction According to Age

    Lim, Eui-Seong; Seo, Man-Wook; Woo, Seong-Ryong; Jeong, Suk-Young; Jeong, Seul-Ki

    2005-01-01

    Background The cerebellum and its neural circuitry have been assumed to play a major role in the pathophysiology of essential tremor (ET). In this study, we sought to find associations between ET and cerebellar dysfunction. Methods We performed tandem gait test in 41 ET patients and 44 age-matched controls. Investigators assessed tandem gait by counting the number of missteps during ten-step tandem walk and each subject repeated the trial three times. Results ET patients had a higher average ...

  15. Nosography of the “essential”: Volitional palatal tremor

    Biller, Jose; Espay, Alberto J.

    2013-01-01

    A 19-year-old heavy metal singer with a history of congenital micrognathia, post-traumatic stress disorder, and anxiety developed isolated movements of the soft palate after lower mandible corrective surgery (osteotomy and genioplasty). He endorsed ear clicks and control over the movements. On examination, there were rhythmic movements of the distal soft palate, characteristic of essential palatal tremor (EPT). However, their change in frequency and amplitude on command (video on the Neurolog...

  16. Essential Palatal Tremor Managed by Cognitive Behavioral Therapy

    Tomohisa Kitamura; Tsuyoshi Sato; Naoki Hayashi; Yosuke Fukushima; Tetsuya Yoda

    2015-01-01

    Background. Essential palatal tremor is a disorder of unknown etiology involving involuntary movement of the uvula and soft palate. Treatment attempts including drugs or surgery have been conducted to cease the rhythmical movement. Case Report. A 55-year-old female visited our department complaining of a sudden, noticeable, intermittent, and rhythmical clicking noise in her throat for five years. Oral examination revealed rhythmical contractions of the soft palate with clicking at the frequen...

  17. RBF-based technique for statistical demodulation of pathological tremor.

    Gianfelici, Francesco

    2013-10-01

    This paper presents an innovative technique based on the joint approximation capabilities of radial basis function (RBF) networks and the estimation capability of the multivariate iterated Hilbert transform (IHT) for the statistical demodulation of pathological tremor from electromyography (EMG) signals in patients with Parkinson's disease. We define a stochastic model of the multichannel high-density surface EMG by means of the RBF networks applied to the reconstruction of the stochastic process (characterizing the disease) modeled by the multivariate relationships generated by the Karhunen-Loéve transform in Hilbert spaces. Next, we perform a demodulation of the entire random field by means of the estimation capability of the multivariate IHT in a statistical setting. The proposed method is applied to both simulated signals and data recorded from three Parkinsonian patients and the results show that the amplitude modulation components of the tremor oscillation can be estimated with signal-to-noise ratio close to 30 dB with root-mean-square error for the estimates of the tremor instantaneous frequency. Additionally, the comparisons with a large number of techniques based on all the combinations of the RBF, extreme learning machine, backpropagation, support vector machine used in the first step of the algorithm; and IHT, empirical mode decomposition, multiband energy separation algorithm, periodic algebraic separation and energy demodulation used in the second step of the algorithm, clearly show the effectiveness of our technique. These results show that the proposed approach is a potential useful tool for advanced neurorehabilitation technologies that aim at tremor characterization and suppression. PMID:24808594

  18. Dopa Responsive Slow Orthostatic Tremor in Parkinson’s Disease

    Suk Yoon Lee

    2011-10-01

    Full Text Available Slow orthostatic tremor (OT occurred to longer and lower frequency regular rhythmic bursts in leg muscle upon standing. The slow OT was often able to clinically confused with orthostatic myoclonus. We described a Parkinson’s disease patient with levodopa responsive slow OT. She showed abnormal movements of more regular rhythms and stable frequency on both legs on standing. These symptoms were aggravated at off state and improved by increasing levodopa.

  19. Dehydration-induced porosity waves and episodic tremor and slip

    Skarbek, Rob M.; Rempel, Alan W.

    2016-02-01

    Episodic tremor and slip (ETS) along the subduction interface takes place where there is abundant evidence for elevated, near-lithostatic pore pressures, at sufficiently great depths (30-45 km) that chemical dehydration reactions must act as their dominant source. We simulate fluid and heat flow while tracking the location of a vertically oriented, one-dimensional column of material as it subducts through the slow slip and tremor zone. The material in the column is transformed through a pressure-dependent and temperature-dependent dehydration reaction that we describe with a generalized nonlinear kinetic rate law. Column deformation is largely dominated by viscous creep, with a closure rate that depends linearly on porosity. This behavior causes the dehydration reaction to generate traveling porosity waves that transport increased fluid pressures within the slow slip region. To explore the possibility that the observed periodicity of slow slip and tremor in subduction zones can be explained by the migration of such porosity waves, we derive a dispersion relation that accurately describes our numerical results. We also obtain an expression for how the thickness of the dehydrating layer is expected to vary as a function of the parameters in the reaction rate law. Although the amplitudes of pore pressure perturbations rival those that are produced by known external forcings (e.g., tides or passing surface waves), our analysis suggests that given reasonable estimates of rock viscosity, permeabilities in the range 6.5×10-15 to 5×10-10 m2 are required for porosity wave trains to form at periods comparable to those of slow slip and tremor.

  20. Compensation effects and relation between the activation energy of spin transition and the hysteresis loop width for an iron(ii) complex.

    Bushuev, Mark B; Pishchur, Denis P; Nikolaenkova, Elena B; Krivopalov, Viktor P

    2016-06-22

    The enthalpy-entropy compensation was observed for the cooperative → spin transition (the phase is a mononuclear complex [FeL2](BF4)2, L is 4-(3,5-dimethyl-1H-pyrazol-1-yl)-2-(pyridin-2-yl)-6-methylpyrimidine). The physical origin of this effect is the fact that the → spin transition is the first order phase transition accompanied by noticeable variations in the Tonset↑, ΔH and ΔS values. Higher ΔH and ΔS values are correlated with higher Tonset↑ values. The higher the enthalpy and entropy of the spin transition, the wider the hysteresis loop. The kinetic compensation effect, i.e. a linear relationship between ln A and Ea, was observed for the → spin transition. Moreover, an isokinetic relationship was detected in this system: the Arrhenius lines (ln k vs. 1/T) obtained from magnetochemical data for different samples of the phase undergoing the → transition show a common point of intersection (Tiso = 490 ± 2 K, ln kiso = -6.0 ± 0.2). The validity of this conclusion was confirmed by the Exner-Linert statistical method. This means that the isokinetic relationship and the kinetic compensation effect (ln A vs. Ea) in this system are true ones. The existence of a true kinetic compensation effect is supported independently by the fact that the hysteresis loop width for the cooperative spin transition ↔ increases with increasing activation barrier height. Estimating the energy of excitations for the phase with Tiso ∼ 490 K yields wavenumbers of ca. 340 cm(-1) corresponding to the frequencies of the stretching vibrations of the Fe(LS)-N bonds, i.e. the bonds directly involved in the mechanism of the spin transition. This is the first observation of the kinetic compensation effect (ln A vs. Ea) and the isokinetic relationship for a cooperative spin crossover system showing thermal hysteresis. Our results provide the first experimental evidence that the higher the activation barrier for the spin transition, the wider the hysteresis loop for a

  1. The Role of β-Carboline Alkaloids in the Pathogenesis of Essential Tremor.

    Laviță, Svetlana Iuliana; Aro, Rania; Kiss, Béla; Manto, Mario; Duez, Pierre

    2016-06-01

    Essential tremor (ET) is one of the most prevalent neurological disorders in the world. Environmental factors have been implicated in the pathogenesis of ET. In particular, epidemiological studies have suggested that neurotoxic agents, especially β-carboline alkaloids (βCAs), might be generated through Maillard-type reaction. βCAs are molecules which are members of a large group of heterocyclic amines (HCAs, the so-called products of cooking meat). βCAs are highly tremorogenic in animals, producing a marked generalized action tremor soon after systemic administration in a wide range of laboratory animals such as mice, rats and monkeys. Administration of βCAs remains currently the main experimental model of ET. We review the pathogenesis of ET, with a focus on the biochemistry of βCAs, their occurrence and biological activity, their endogenous biosynthesis, their formation in food, their toxicokinetics and their neurotoxicity. We highlight open questions regarding the effects of βCAs in humans. PMID:26634934

  2. Visual dysfunction in patients with Parkinson's disease and essential tremor.

    Štenc Bradvica, Ivanka; Bradvica, Mario; Matić, Suzana; Reisz-Majić, Patricia

    2015-02-01

    The aim of this study was to determine the specificity and sensitivity of the Pelli-Robson and Ishihara diagnostic methods in differing Parkinson's disease from essential tremor compared to DaTSCAN (dopamine transporter scan) findings. The intention was to investigate whether visual dysfunction appears in the early state of Parkinson's disease. Therefore, we included patients with the symptomatology of parkinsonism lasting between 6 and 12 months. The study included 164 patients of which 59 (36.0%) suffered from Parkinson's disease, 51 (31.1%) from essential tremor, and 54 (32.9%) healthy patients which presented the control group. The specificity of Pelli-Robson test in confirming Parkinson's disease was 53% and the sensitivity 81.4%. The specificity of Ishihara test in confirming Parkinson's disease was 88.2%, and sensitivity 55.9%. We found that the colour and contrast dysfunction are present as the earliest symptoms of Parkinson's disease. In this study the Pelli-Robson test is highly sensitive and the Ishihara tables are highly specific in the differential diagnosis between Parkinson's disease and essential tremor, but neither of these methods fulfils the criteria for the validity of a test. We suggest performing both of these methods to evaluate which patients are indicated for DaTSCAN. PMID:25164787

  3. Joint observation of long period tremor signals with broadband seismometer, tiltmeter and gravimeter

    ZHANG Yan-bin; JIANG Jun; LIAO Ying-chun; LI Sheng-le; ZHONG Tie-tao

    2008-01-01

    We report here the observation result of joint observation of long period tremor signals with broadband seismometer, tiltmeter and gravimeter at the HUST (Huazhong University of Science and Technology) station. The observed data were compared and analyzed. Since 2005, the several tens of abnormal tremor signals which are weak, complex and duration of 2 to 3 days have been synchronously recorded by the different instruments. The tremor signals have the periodic domain in the range of 3 to 5 minutes, 20 to 30 minutes and even more than 1 hour. The observation shows such tremors are a physical existence. The analysis indicates that a part of the tremors caused by the typhoon from the western Pacific Ocean. These tremors have a close relationship with wind velocity of typhoon and distance between the typhoon center and the station. Except these, the cause of others is still unclear.

  4. Introduction to special section on phenomenology, underlying processes, and hazard implications of aseismic slip and nonvolcanic tremor

    Gomberg, Joan

    2010-01-01

    This paper introduces the special section on the "phenomenology, underlying processes, and hazard implications of aseismic slip and nonvolcanic tremor" by highlighting key results of the studies published in it. Many of the results indicate that seismic and aseismic manifestations of slow slip reflect transient shear displacements on the plate interface, with the outstanding exception of northern Cascadia where tremor sources have been located on and above the plate interface (differing models of the plate interface there also need to be reconciled). Slow slip phenomena appear to result from propagating deformation that may develop with persistent gaps and segment boundaries. Results add to evidence that when tectonic deformation is relaxed via slow slip, most relaxation occurs aseismically but with seismic signals providing higher-resolution proxies for the aseismic slip. Instead of two distinct slip modes as suggested previously, lines between "fast" and "slow" slip more appropriately may be described as blurry zones. Results reported also show that slow slip sources do not coincide with a specific temperature or metamorphic reaction. Their associations with zones of high conductivity and low shear to compressional wave velocity ratios corroborate source models involving pore fluid pressure buildup and release. These models and spatial anticorrelations between earthquake and tremor activity also corroborate a linkage between slow slip and frictional properties transitional between steady state and stick-slip. Finally, this special section highlights the benefits of global and multidisciplinary studies, which demonstrate that slow phenomena are not confined to beneath the locked zone but exist in many settings.

  5. Orthostatic tremor: Report of a case and review of the literature

    Bhattacharyya K

    2003-01-01

    Full Text Available Orthostatic tremor is a rare movement disorder characterized by tremulousness of the lower limbs on standing that disappears on walking, sitting or on lying down and a distinctive electromyographic burst of 14 to 16 Hz. On inspection, fine ripples can sometimes be seen over the quadriceps on standing. The tremor has a tendency to reappear even in the supine posture if the lower limb muscles are put to an isometric contraction state, indicating thereby that in spite of the fact that the tremor occurs on standing, it is essentially 'orthostasis independent' and the central factor is the contraction of the muscles. As a matter of fact, the tremor is abolished if the subject is suspended by harness, thus relieving him of muscle contraction. Doubts are being cast whether it is a variant of essential tremor since a number of families are being reported to be suffering from this disease as well. Positron emission tomography reveals hyperactivity of cerebellum in orthostatic tremor as it shows in essential tremor, therefore lending credence to such a hypothesis. However, lack of response to alcohol, propranolol and primidone in orthostatic tremor stands out as a serious challenge to such a view. Lack of positive family history, synchrony of contracting group of muscles and negative `reseting' of the tremor by increasing peripheral load-phenomena consistently observed in orthostatic tremor and not in essential tremor, are other features that often help to distinguish between the two conditions. We report a case of orthostatic tremor that presented with the classical clinical and eletromyographic features. Relevant literature in this regard is also being reviewed.

  6. Parkinson's disease and essential tremor in families of patients with early-onset Parkinson's disease.

    Marttila, R J; Rinne, U K

    1988-01-01

    The occurrence of Parkinson's disease and of essential tremor was examined in the parents and siblings of 52 Parkinson's disease patients with onset before the age of 45 years. The expected numbers of cases with Parkinson's disease or essential tremor were calculated according to the age and sex specific incidence rates of Parkinson's disease and essential tremor in the general population. Among the parents, there was one case of Parkinson's disease (expected 1.2), and 10 cases of essential t...

  7. Measures of fine motor skills in people with tremor disorders: appraisal and interpretation

    Norman, Kathleen E.; Héroux, Martin E.

    2013-01-01

    People with Parkinson’s disease, essential tremor, or other movement disorders involving tremor have changes in fine motor skills that are among the hallmarks of these diseases. Numerous measurement tools have been created and other methods devised to measure such changes in fine motor skills. Measurement tools may focus on specific features – e.g., motor skills or dexterity, slowness in movement execution associated with parkinsonian bradykinesia, or magnitude of tremor. Less obviously, some...

  8. Measures of Fine Motor Skills in People with Tremor Disorders: Appraisal and Interpretation

    Norman, Kathleen E.; Héroux, Martin E.

    2013-01-01

    People with Parkinson’s disease, essential tremor, or other movement disorders involving tremor have changes in fine motor skills that are among the hallmarks of these diseases. Numerous measurement tools have been created and other methods devised to measure such changes in fine motor skills. Measurement tools may focus on specific features – e.g., motor skills or dexterity, slowness in movement execution associated with parkinsonian bradykinesia, or magnitude of tremor. Less obviously, some...

  9. Cannabinoid receptor agonism suppresses tremor, cognition disturbances and anxiety-like behaviors in a rat model of essential tremor.

    Abbassian, Hassan; Esmaeili, Parisa; Tahamtan, Mahshid; Aghaei, Iraj; Vaziri, Zohreh; Sheibani, Vahid; Whalley, Benjamin J; Shabani, Mohammad

    2016-10-01

    Cognitive and motor disturbances are serious consequences of tremor induced by motor disorders. Despite a lack of effective clinical treatment, some potential therapeutic agents have been used to alleviate the cognitive symptoms in the animal models of tremor. In the current study, the effects of WIN55, 212-2 (WIN), a cannabinoid receptor (CBR) agonist, on harmaline-induced motor and cognitive impairments were studied. Adult rats were treated with WIN (0.5mg/kg; i.p.) 15min before harmaline administration (10mg/kg; ip) after which exploratory and anxiety related behaviors, and cognitive function were assessed using open-field behavior and shuttle box tests. Rats that received harmaline only exhibited a markedly reduced number of central square entries when compared to harmaline vehicle-treated controls, whereas those treated with WIN and harmaline showed a significant increase in central square entries, compared to harmaline only treated. The passive avoidance memory impairments observed in harmaline treated rats, was reversed somewhat by administration of WIN. The neuroprotective and anxiolytic effects of WIN demonstrated in the current study can be offered cannabinoid receptor (CBR) agonism as a potential neuroprotective agent in the treatment of patients with tremor that manifest mental dysfunctions. PMID:27317835

  10. Load-induced changes in older individual's hand-finger tremor are ameliorated with targeting.

    Kavanagh, Justin J; Cross, Troy J; Newell, Karl M; Morrison, Steven

    2014-04-15

    The purpose of this study was to investigate hand-finger tremor dynamics when a load was applied to the finger in a group of healthy older adults. Moreover, we sought to determine if projecting a representation of the subject's finger tremor on a target was capable of overcoming the effects of loading so that hand-finger interactions returned to a state that was similar to normal tremor. Eight healthy older males (67 ± 1 year) performed a postural pointing task, where tremor was assessed using lightweight accelerometers attached to the hand and finger. Tremor was then assessed when a laser pointer was attached to the finger and switched off (the load), and then with the laser pointer attached and switched on pointing at targets of 40 mm and 20mm in diameter. The main findings of this study were that 1) loading the finger resulted in a reduction in finger tremor amplitude and increased finger tremor regularity, but no change in hand tremor, 2) loading caused increased hand-finger 8-12 Hz cross wavelet coherence and phase synchrony, and 3) pointing at different targets while the finger was loaded resulted in an increase in finger tremor amplitude, and changes in inter-segmental coupling to the extent that hand-finger dynamics reflected normal unloaded conditions. Overall, these results illustrate that the damping effects of limb loading can be offset, in part, by altering the accuracy demands of the task to make the pointing action more challenging. PMID:24503237