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Sample records for volcanic tremor amplitude

  1. Time variation in amplitude-frequency distribution of deep non-volcanic tremors in the Bungo Channel region, southwest Japan

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    Hanakawa, Y.; Suda, N.

    2009-12-01

    Magnitude-frequency distribution of earthquakes follows the Gutenberg-Richter law. The slope of this law, b value, represents the relative occurrence of large and small earthquakes. Since magnitude is defined as corrected logarithmic amplitude, amplitude-frequency distribution of earthquakes is linear on log-log graph. On the other hand, that of non-volcanic tremors is linear on semi-log graph, indicating that it follows the exponential distribution, not the power-law distribution [Hiramatsu et al., 2008]. Thus the slope of amplitude-frequency distribution for tremors is equivalent to b value for earthquakes. In this study, we investigated time variation in the slope of amplitude-frequency distribution from analyses of tremor activities in the Bungo Channel region, where long-term slow slip events occurred in 1997 and 2003. We analyzed vertical-component records from Hi-net and the seismic networks of Japan Meteorological Agency and universities for the five-year period between 2004 and 2008. We also used records from the temporal seismic station in Hiburi Island installed by us in the period after Sept. 2004. In the Bungo Channel region, tremor activity occurs with a recurrence interval of approximately two months. We observed a total of 35 activities including small ones in the analysis period. To detect tremors and determine their hypocenters, we used the same software as Automatic Tremor Monitoring System (ATMOS) [Suda et al., in press]. We obtained frequency distribution of reduced displacements (RDs) for each tremor activity. RD is RMS amplitude of ground displacement corrected with hypocentral distance [Aki and Koyanagi, 1981], and it is proportional to seismic moment rate. The observed slopes of RD-frequency distribution for active swarms were approximately constant in the period between 2004 and 2006, but they declined in 2007. At the end of 2008, the slopes decreased bellow half the values between 2004 and 2006. As well as b value, the slope represents

  2. Tremor and its duration-amplitude distribution at Popocatépetl volcano, Mexico

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    Arámbula-Mendoza, R.; Valdés-González, C.; Varley, N.; Reyes-Pimentel, T. A.; Juárez-García, B.

    2016-09-01

    The duration-amplitude distribution was calculated for the tremor observed at Popocatépetl volcano during episodes of activity in 2000 and 2012-2014. An exponential function was used to obtain a good fit for the duration-amplitude distribution, and the source of volcanic tremor is probably generated by the transportation of magmatic fluids and its coupling with the host rock within the volcanic conduit. In particular, harmonic tremor has shown large amplitudes, durations, and mean values of amplitude, more than spasmodic or pulsating tremor. This is due to different generation mechanisms: in the case of harmonic tremor, it is produced during magma ascent and lava dome growth, while spasmodic and pulsating tremors are associated with fragmentation of the lava dome and gas emissions. This paper presents the duration-amplitude distribution as a method to estimate the intensity of the tremor at Popocatépetl, a volcano with the major risk in all Mexico.

  3. Volcanic tremor and plume height hysteresis from Pavlof Volcano, Alaska.

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    Fee, David; Haney, Matthew M; Matoza, Robin S; Eaton, Alexa R; Cervelli, Peter; Schneider, David J; Iezzi, Alexandra M

    2017-01-06

    The March 2016 eruption of Pavlof Volcano, Alaska, produced an ash plume that caused the cancellation of more than 100 flights in North America. The eruption generated strong tremor that was recorded by seismic and remote low-frequency acoustic (infrasound) stations, including the EarthScope Transportable Array. The relationship between the tremor amplitudes and plume height changes considerably between the waxing and waning portions of the eruption. Similar hysteresis has been observed between seismic river noise and discharge during storms, suggesting that flow and erosional processes in both rivers and volcanoes can produce irreversible structural changes that are detectable in geophysical data. We propose that the time-varying relationship at Pavlof arose from changes in the tremor source related to volcanic vent erosion. This relationship may improve estimates of volcanic emissions and characterization of eruption size and intensity.

  4. Evaluation of Non-Volcanic Tremor Detection Techniques

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    Sit, S. M.; Brudzinski, M. R.; Kao, H.

    2009-12-01

    Non-volcanic tremor (NVT) is a subduction zone process often associated with the transition from stick-slip to stable sliding on the plate interface. In Northern Cascadia, NVT episodes lasting multiple weeks have been correlated spatially and temporally with slow slip episodes at a regular recurrence interval of 15±2 months. However, NVT across the entire Cascadia margin varies widely in recurrence and duration, while still other subduction zones (Japan, Mexico) observe separate cases of tremor and GPS-detected slip. Multiple identification and location techniques exist, but we will focus on techniques that can identify NVT at single stations to accommodate searching outside a dense network of instruments. This study evaluates these techniques in several regions along the entire Cascadia margin and in the Oaxaca segment of the Middle America Subduction Zone. Tremor signals are collected from a mixture of seismometers including those of temporary deployments targeting NVT, the EarthScope Transportable Array, the Canadian National Seismograph Network, and a few other regional networks that span the subduction zones. We compare existing techniques that scan moving averages, scintillation index, and hourly mean amplitudes with a new tremor frequency scanning technique that bandpass filters seismic data into three categories, 10-15 Hz, 2-5 Hz, and 0.2-0.5 Hz, where we expect prominent signals from microseismicity, NVT, and surface waves, respectively. Applying these techniques to episodes over the last few years finds that each technique can identify large, multi-week tremor events associated with GPS recorded slow slip. However, different techniques result in different totals of tremor hours detected per episode, as well as variable numbers of additional smaller episodes identified. Based on previous research that finds the amount of tremor correlated to the amount of slip from geodetic inversions, we are working towards a consensus single station approach that is

  5. Comparing Moment Release and Tremor Amplitudes in Cascadia ETS Events

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    Hall, K.; Schmidt, D. A.; Houston, H.

    2016-12-01

    A proposed relationship between the moment release of ETS and tremor duration. [Aguiar et al., 2009] compared moment from static inversions of slip with the overall duration of the entire ETS, finding a linear relationship between moment release and tremor duration. There is a logical relationship between the processes that generate slip and those that generate tremor. Spatially, we have seen that slip may occur up-dip of tremor [Houston, 2012] and [Hall and Houston, 2014] in Northern Cascadia. On the other hand, Bartlow et al. [2011] did not resolve a spatio-temporal difference between tremor and slow slip for the 2009 ETS in mid-Cascadia. This raises the possibility that there could be an as-yet-unrecognized regional difference. In order to explore spatio-temporal relationships between tremor and slow slip, I used the Extended Network Inversion Filter (ENIF) [Segall and Matthews, 1997] together with PNSN tremor locations. Preliminary results for the 2010 ETS event yield a M6.8 event that begins near Seattle on August 8th and propagates mainly to the north with some smaller slip to the south, following the propagation of the tremor, a pattern consistent with our static inversion results. The slip-pulse nature of the ETS process is clearly imaged, with some fault patches continuing to slip for several days after tremor has passed through, but not for the entire duration of the event. I then looked at tremor amplitudes [Ulberg and Creager, AGU Abs, 2013], which represent the amount of energy released in a five-minute tremor window. Because the tremor catalog has much finer temporal resolution than the GPS data, I sum the daily tremor amplitudes and compare to daily moment-rates from the time-dependent inversion, obtaining a correlation between moment-rate and tremor amplitude rate. This suggests that the energy released by tremor may be a direct proxy for energy released by slip.

  6. Volcanic tremor associated with eruptive activity at Bromo volcano

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    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.

  7. Non-Volcanic Tremor Observed in Guerrero, Mexico

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    Payero, J.; Kostoglodov, V.; Shapiro, N.; Mikumo, T.; Iglesias, A.; Perez, X.; Clayton, R.

    2007-12-01

    Non-volcanic tremor (NVT) activity is clearly identified as episodes of higher spectral amplitude in the range of 1-8 Hz in daily spectrograms from the continuous records at broad band seismic stations in the Guerrero state, Mexico. The analyzed data cover a period of 2001-2007 when in 2001-2002 a large slow slip event (SSE) had occurred in the Guerrero-Oaxaca region, and then followed by a steady-state interseismic epoch of 2003-2005 and a new large SSE occurred in 2006. The tremor signals in Mexico are very similar to those obtained in Cascadia subduction zone. An average tremor burst remains for 10-60 min and is dominated by S-waves. More than 100 strong NVT bursts were recorded by the most of the Meso-American Subduction Experiment (MASE 2005-2007) seismic stations with the majority of epicenters clustered in the narrow band of ~40 x 150 km2 to the south of Iguala city and in parallel to the coastline. Depths of NVT hypocenters are poorly constrained but mostly scattered in the continental crust between 5 and 45 km depth. Tremor activity is significantly higher during the 2001-2002 and 2006 SSE compared with that for the "quiet" period of 2003-2005. Very low NVT occurrence for the period of about 2 months right after the SSE is apparent in 2002 and 2006. Similar to the Japan and Cascadia subduction zones, the main tremor activity in Mexico develops in the area close to the mantle wedge. In Mexico it is located at approximately 200 km inland from the trench. While conductivity pattern obtained from the magnetotelluric profile in Guerrero does not correlate directly with the NVT distribution, gravity and magnetic anomalies modeling favors a hypothesis that the NVT is apparently related to the dehydration and serpentinization processes.

  8. Model of Deep Non-Volcanic Tremor in Episodic Tremor and Slip Events

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    Gershenzon, N. I.; Bambakidis, G.

    2014-12-01

    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 (see Figure). 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 to explain the complicated pattern of tremor migration, including rapid tremor propagation and reverse tremor migration. Migration along the strike direction is associated with movement of the slip pulse. Rapid tremor propagation in the slip-parallel direction is associated with movement of kinks along a 2D slip pulse. A slip pulse, pinned in some places, can fragment into several pulses, causing tremor associated with some of these pulse fragments to move opposite to the main propagation direction. The model predicts that the frequency content of tremor during an ETS event is slightly different from the frequency content of ambient tremor and tremor triggered by earthquakes. Figure 1. The slip velocity w of a slip pulse in time-space (x-t) coordinates moving in (a) ideal substrate and (b) substrate with a structural heterogeneity. Pulse is driven by constant external shear stress. Figure 1(b) shows that the pulse oscillates about an obstacle

  9. Volcanic tremors: Good indicators of change in plumbing systems during volcanic eruptions

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    Tárraga, Marta; Martí, Joan; Abella, Rafael; Carniel, Roberto; López, Carmen

    2014-03-01

    Geophysical and geochemical signals recorded during episodes of unrest preceding volcanic eruptions provide information on movements of magma inside the lithosphere and on how magma prepares to reach the surface. When the eruption ensues continuous volcanic monitoring can reveal the nature of changes occurring in the volcano's plumbing system, which may be correlated with changes in both eruption behaviour and products. During the 2011-2012 submarine eruption of El Hierro (Canary Islands), the seismic signal, surface deformation, a broad stain on the sea surface of the eruption site, and the occasional appearance of floating lava balloons and pyroclastic fragments were the main observable signs. A strong continuous tremor in the vent accompanied the eruption and varied significantly in amplitude, frequency and dynamical parameters. We analysed these variations and correlated them with changes in the distribution of earthquakes and in the petrology of the erupting magma. This enabled us to relate variations in tremors to changes in the (i) stress conditions of the plumbing system, (ii) dimensions of the conduit and vent, (iii) intensity of the explosive episodes, and (iv) rheological changes in the erupting magma. The results obtained show how the tremor signal was strongly influenced by stress changes in the host rock and in the rheological variations in the erupting magma. We conclude that the tracking of real-time syn-eruptive tremor signals via the observation of variations in plumbing systems and magma physics is a potentially effective tool for interpreting eruption dynamics, and suggest that similar variations observed in pre-eruptive tremors will have a similar origin.

  10. Model for triggering of non-volcanic tremor by earthquakes

    CERN Document Server

    Gershenzon, Naum I

    2012-01-01

    There is evidence of tremor triggering by seismic waves emanating from distant large earthquakes. The frequency content of both triggered and ambient tremor are largely identical, suggesting that this property 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 tremor triggering. 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. Thus, although the amplitude and duration of a tremor burst may reflect the "personality" of the source, the frequency content does not. The model also explains why a tremor has no clear impulsive phase, in contrast to earthquakes. The relationship between tremor and low frequency earthquakes is discussed.

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

    CERN Document Server

    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...

  12. Non-volcanic tremor driven by large transient shear stresses.

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    Rubinstein, Justin L; Vidale, John E; Gomberg, Joan; Bodin, Paul; Creager, Kenneth C; Malone, Stephen D

    2007-08-01

    Non-impulsive seismic radiation or 'tremor' has long been observed at volcanoes and more recently around subduction zones. Although the number of observations of non-volcanic tremor is steadily increasing, the causative mechanism remains unclear. Some have attributed non-volcanic tremor to the movement of fluids, while its coincidence with geodetically observed slow-slip events at regular intervals has led others to consider slip on the plate interface as its cause. Low-frequency earthquakes in Japan, which are believed to make up at least part of non-volcanic tremor, have focal mechanisms and locations that are consistent with tremor being generated by shear slip on the subduction interface. In Cascadia, however, tremor locations appear to be more distributed in depth than in Japan, making them harder to reconcile with a plate interface shear-slip model. Here we identify bursts of tremor that radiated from the Cascadia subduction zone near Vancouver Island, Canada, during the strongest shaking from the moment magnitude M(w) = 7.8, 2002 Denali, Alaska, earthquake. Tremor occurs when the Love wave displacements are to the southwest (the direction of plate convergence of the overriding plate), implying that the Love waves trigger the tremor. We show that these displacements correspond to shear stresses of approximately 40 kPa on the plate interface, which suggests that the effective stress on the plate interface is very low. These observations indicate that tremor and possibly slow slip can be instantaneously induced by shear stress increases on the subduction interface-effectively a frictional failure response to the driving stress.

  13. Seismic Tremors and Magma Wagging During Explosive Volcanism

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    Jellinek, M.; Bercovici, D.

    2010-12-01

    Volcanic tremor is a ubiquitous feature of explosive eruptions. This ground oscillation persists for minutes to weeks and is characterized by a remarkably narrow band of frequencies (i.e., ~0.5 - 7 Hz). Prior to major eruptions, tremor can occur in concert with ground deformation probably related to a buildup of magmatic gas. Volcanic tremor is, thus, of particular value for eruption forecasting. Most models for volcanic tremor rely on specific properties of the geometry, structure and constitution of volcanic conduits as well as the gas content of the erupting magma. Because neither the initial structure nor the evolution of the magma-conduit system will be the same from one volcano to the next, it is surprising that tremor characteristics are so consistent among different volcanoes. Indeed, this universality of tremor properties remains a major enigma. Here we employ the contemporary view that silicic magma rises in the conduit as a columnar plug surrounded by a highly vesicular annulus of sheared bubbles. We demonstrate that, for most geologically relevant conditions, the magma column will oscillate or "wag" against the restoring "gas-spring" force of the annulus at observed tremor frequencies. In contrast to previous models, the magma wagging oscillation is relatively insensitive to the conduit structure and geometry, thereby predicting the narrow band of tremor frequencies observed around the world. Moreover, the model predicts that as an eruption proceeds there will be an upward drift in both the maximum frequency and the total signal frequency bandwidth, the nature of which depends on the explosivity of the eruption, as observed.

  14. The radiation of surface wave energy: Implications for volcanic tremor

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    Haney, M. M.; Denolle, M.; Lyons, J. J.; Nakahara, H.

    2015-12-01

    The seismic energy radiated by active volcanism is one common measurement of eruption size. For example, the magnitudes of individual earthquakes in volcano-tectonic (VT) swarms can be summed and expressed in terms of cumulative magnitude, energy, or moment release. However, discrepancies exist in current practice when treating the radiated energy of volcano seismicity dominated by surface waves. This has implications for volcanic tremor, since eruption tremor typically originates at shallow depth and is made up of surface waves. In the absence of a method to compute surface wave energy, estimates of eruption energy partitioning between acoustic and seismic waves typically assume seismic energy is composed of body waves. Furthermore, without the proper treatment of surface wave energy, it is unclear how much volcanic tremor contributes to the overall seismic energy budget during volcanic unrest. To address this issue, we derive, from first principles, the expression of surface wave radiated energy. In contrast with body waves, the surface wave energy equation is naturally expressed in the frequency domain instead of the time domain. We validate our result by reproducing an analytical solution for the radiated power of a vertical force source acting on a free surface. We further show that the surface wave energy equation leads to an explicit relationship between energy and the imaginary part of the surface wave Green's tensor at the source location, a fundamental property recognized within the field of seismic interferometry. With the new surface wave energy equation, we make clear connections to reduced displacement and propose an improved formula for the calculation of surface wave reduced displacement involving integration over the frequency band of tremor. As an alternative to reduced displacement, we show that reduced particle velocity squared is also a valid physical measure of tremor size, one based on seismic energy rate instead of seismic moment rate. These

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

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    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.

  16. Neural networks and dynamical system techniques for volcanic tremor analysis

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    R. Carniel

    1996-06-01

    Full Text Available A volcano can be seen as a dynamical system, the number of state variables being its dimension N. The state is usually confined on a manifold with a lower dimension f, manifold which is characteristic of a persistent «structural configuration». A change in this manifold may be a hint that something is happening to the dynamics of the volcano, possibly leading to a paroxysmal phase. In this work the original state space of the volcano dynamical system is substituted by a pseudo state space reconstructed by the method of time-delayed coordinates, with suitably chosen lag time and embedding dimension, from experimental time series of seismic activity, i.e. volcanic tremor recorded at Stromboli volcano. The monitoring is done by a neural network which first learns the dynamics of the persistent tremor and then tries to detect structural changes in its behaviour.

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

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    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.

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

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    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.

  19. Alarm systems detect volcanic tremor and earthquake swarms during Redoubt eruption, 2009

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    Thompson, G.; West, M. E.

    2009-12-01

    We ran two alarm algorithms on real-time data from Redoubt volcano during the 2009 crisis. The first algorithm was designed to detect escalations in continuous seismicity (tremor). This is implemented within an application called IceWeb which computes reduced displacement, and produces plots of reduced displacement and spectrograms linked to the Alaska Volcano Observatory internal webpage every 10 minutes. Reduced displacement is a measure of the amplitude of volcanic tremor, and is computed by applying a geometrical spreading correction to a displacement seismogram. When the reduced displacement at multiple stations exceeds pre-defined thresholds and there has been a factor of 3 increase in reduced displacement over the previous hour, a tremor alarm is declared. The second algorithm was to designed to detect earthquake swarms. The mean and median event rates are computed every 5 minutes based on the last hour of data from a real-time event catalog. By comparing these with thresholds, three swarm alarm conditions can be declared: a new swarm, an escalation in a swarm, and the end of a swarm. The end of swarm alarm is important as it may mark a transition from swarm to continuous tremor. Alarms from both systems were dispatched using a generic alarm management system which implements a call-down list, allowing observatory scientists to be called in sequence until someone acknowledged the alarm via a confirmation web page. The results of this simple approach are encouraging. The tremor alarm algorithm detected 26 of the 27 explosive eruptions that occurred from 23 March - 4 April. The swarm alarm algorithm detected all five of the main volcanic earthquake swarm episodes which occurred during the Redoubt crisis on 26-27 February, 21-23 March, 26 March, 2-4 April and 3-7 May. The end-of-swarm alarms on 23 March and 4 April were particularly helpful as they were caused by transitions from swarm to tremor shortly preceding explosive eruptions; transitions which were

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

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    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

  1. Short-term spasmodic switching of volcanic tremor source activation in a conduit of the 2011 Kirishima eruption

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    Matsumoto, S.; Shimizu, H.; Matsushima, T.; Uehira, K.; Yamashita, Y.; Nakamoto, M.; Miyazaki, M.; Chikura, H.

    2012-04-01

    Volcanic tremors are seismic indicators providing clues for magma behavior, which is related to volcanic eruptions and activity. Detection of spatial and temporal variations of volcanic tremors is important for understanding the mechanism of volcanic eruptions. However, temporal variations of tremor activity in short-term than a minute have not been previously detected by seismological observations around volcanoes. Here, we show that volcanic tremor sources were activated at the top of the conduit (i.e. the crater) and at its lower end by analyzing seismograms from a dense seismic array during the 2011 Kirishima eruption. We observed spasmodic switching in the seismic ray direction during a volcanic tremor sequence. Such fine volcanic tremor structure suggests an interaction between tremor sources located in both deep and shallow depths. Our result suggests that seismic array observations can monitor the magma behavior and contribute to the evaluation of the activity's transition.

  2. Relationship between volcanic ash fallouts and seismic tremor: quantitative assessment of the 2015 eruptive period at Cotopaxi volcano, Ecuador

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    Bernard, Benjamin; Battaglia, Jean; Proaño, Antonio; Hidalgo, Silvana; Vásconez, Francisco; Hernandez, Stephen; Ruiz, Mario

    2016-11-01

    Understanding the relationships between geophysical signals and volcanic products is critical to improving real-time volcanic hazard assessment. Thanks to high-frequency sampling campaigns of ash fallouts (15 campaigns, 461 samples), the 2015 Cotopaxi eruption is an outstanding candidate for quantitatively comparing the amplitude of seismic tremor with the amount of ash emitted. This eruption emitted a total of 1.2E + 9 kg of ash ( 8.6E + 5 m3) during four distinct phases, with masses ranging from 3.5E + 7 to 7.7E + 8 kg of ash. We compare the ash fallout mass and the corresponding cumulative quadratic median amplitude of the seismic tremor and find excellent correlations when the dataset is divided by eruptive phase. We use scaling factors based on the individual correlations to reconstruct the eruptive process and to extract synthetic Eruption Source Parameters (daily mass of ash, mass eruption rate, and column height) from the seismic records. We hypothesize that the change in scaling factor through time, associated with a decrease in seismic amplitudes compared to ash emissions, is the result of a more efficient fragmentation and transport process. These results open the possibility of feeding numerical models with continuous geophysical data, after adequate calibration, in order to better characterize volcanic hazards during explosive eruptions.

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

    CERN Document Server

    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...

  4. Feasibility study of spectral pattern recognition reveals distinct classes of volcanic tremor

    Science.gov (United States)

    Unglert, K.; Jellinek, A. M.

    2017-04-01

    Systematic investigations of the similarities and differences among volcanic tremor at a range of volcano types may hold crucial information about the plausibility of inferred source mechanisms, which, in turn, may be important for eruption forecasting. However, such studies are rare, in part because of an intrinsic difficulty with identifying tremor signals within very long time series of volcano seismic data. Accordingly, we develop an efficient tremor detection algorithm and identify over 12,000h of volcanic tremor on 24 stations at Kīlauea, Okmok, Pavlof, and Redoubt volcanoes. We estimate spectral content over 5-minute tremor windows, and apply a novel combination of Principal Component Analysis (PCA) and hierarchical clustering to identify patterns in the tremor spectra. Analyzing several stations from a given volcano together reveals different styles of tremor within individual volcanic settings. In addition to identifying tremor properties common to all stations in a given network, we find localized tremor signals including those related to processes such as lahars or dike intrusions that are only observed on some of the stations within a network. Subsequent application of our analysis to a combination of stations from the different volcanoes reveals that at least three main tremor classes can be detected across all settings. Whereas a regime with a ridge of high power distributed over 1-2Hz and a gradual decay of spectral power towards higher frequencies is observed dominantly at three volcanoes (Kīlauea, Okmok, Redoubt) with magma reservoirs centered at less than 5km below sea level (b.s.l.), a spectrum with a steeper slope and a narrower peak at 1-2Hz is observed only in association with open vents (Kīlauea and Pavlof). A third regime with a peak at approximately 3Hz is confined to two stratovolcanoes (Pavlof and Redoubt). These observations suggest generic relationships between the spectral character of the observed signals and volcano

  5. Non-Volcanic Tremor Near Parkfield, CA Systematically Excited by Teleseismic Waves

    Science.gov (United States)

    Peng, Z.; Vidale, J. E.; Rubinstein, J. L.; Gomberg, J.

    2007-12-01

    Non-volcanic tremor triggered by teleseismic waves was discovered recently along the subduction zones in Japan and Cascadia, and along the transform plate boundary in CA. Here we summarize non-volcanic tremor along the San Andreas fault (SAF) near Parkfield, CA triggered by the surface waves of regional and teleseismic events. We analyze 10 M ≥ 8.0 earthquakes since 2001, the M6.7 Nenana Mountain and M7.9 Denali, Alaska earthquakes in 2002 and the 2005 M7.2 Mendocino, California earthquake. We identify triggered tremor as bursts of high-frequency (~ 3-15 Hz), non-impulsive seismic energy that is coherent among many stations, and has a significant component in phase with the passing of the surface waves. We qualitatively judge the clarity of tremor observations and find the strongest, most coherent examples for the M7.9 Denali, M8.3 Hokkaido, M9.1 Sumatra, and M8.1 Kuril Islands earthquakes. The M6.7 Nenana Mountain earthquake did not trigger visible tremor, and the evidence for triggered tremor for the remaining 8 events is equivocal. The identification of tremor does not correlate strongly with peak ground velocity, but may correlate with cumulative energy density for long- period (≥ 30 s) surface waves. The observations suggest that longer-period waves may be a more effective trigger, most likely due to a better penetration to depth where tremors occur. Our observation, in concert with those of Gomberg et al., Vidale et al., and Rubinstein et al. [this meeting], suggests that non-volcanic tremor triggered by teleseismic waves is much more widespread than previously thought, and the effective stress, or the frictional coefficient is very low at depth along the SAF near Parkfield.

  6. Tremor

    Science.gov (United States)

    ... beta blockers (such as nadolol) and primidone, an anticonvulsant drug. Dystonic tremor may respond to clonazepam, anticholinergic ... beta blockers (such as nadolol) and primidone, an anticonvulsant drug. Dystonic tremor may respond to clonazepam, anticholinergic ...

  7. Volcanic tremors and magma wagging: gas flux interactions and forcing mechanism

    Science.gov (United States)

    Bercovici, David; Jellinek, A. Mark; Michaut, Chloé; Roman, Diana C.; Morse, Robert

    2013-11-01

    Volcanic tremor is an important precursor to explosive eruptions and is ubiquitous across most silicic volcanic systems. Oscillations can persist for days and occur in a remarkably narrow frequency band (i.e. 0.5-7 Hz). The recently proposed magma-wagging model of Jellinek & Bercovici provides a basic explanation for the emergence and frequency evolution of tremor that is consistent with observations of many active silicic and andesitic volcanic systems. This model builds on work suggesting that the magma column rising in the volcanic conduit is surrounded by a permeable vesicular annulus of sheared bubbles. The magma-wagging model stipulates that the magma column rattles within the spring like foam of the annulus, and predicts oscillations at the range of observed tremor frequencies for a wide variety of volcanic environments. However, the viscous resistance of the magma column attenuates the oscillations and thus a forcing mechanism is required. Here we provide further development of the magma-wagging model and demonstrate that it implicitly has the requisite forcing to excite wagging behaviour. In particular, the extended model allows for gas flux through the annulus, which interacts with the wagging displacements and induces a Bernoulli effect that amplifies the oscillations. This effect leads to an instability involving growing oscillations at the lower end of the tremor frequency spectrum, and that drives the system against viscous damping of the wagging magma column. The fully non-linear model displays tremor oscillations associated with pulses in gas flux, analogous to observations of audible `chugging'. These oscillations also occur in clusters or envelopes that are consistent with observations of sporadic tremor envelopes. The wagging model further accurately predicts that seismic signals on opposite sides of a volcano are out of phase by approximately half a wagging or tremor period. Finally, peaks in gas flux occur at the end of the growing instability

  8. Precise tremor source locations and amplitude variations along the lower-crustal central San Andreas Fault

    Science.gov (United States)

    Shelly, David R.; Hardebeck, Jeanne L.

    2010-01-01

    We precisely locate 88 tremor families along the central San Andreas Fault using a 3D velocity model and numerous P and S wave arrival times estimated from seismogram stacks of up to 400 events per tremor family. Maximum tremor amplitudes vary along the fault by at least a factor of 7, with by far the strongest sources along a 25 km section of the fault southeast of Parkfield. We also identify many weaker tremor families, which have largely escaped prior detection. Together, these sources extend 150 km along the fault, beneath creeping, transitional, and locked sections of the upper crustal fault. Depths are mostly between 18 and 28 km, in the lower crust. Epicenters are concentrated within 3 km of the surface trace, implying a nearly vertical fault. A prominent gap in detectible activity is located directly beneath the region of maximum slip in the 2004 magnitude 6.0 Parkfield earthquake.

  9. 'Failed' eruptions revealed by integrated analysis of gas emission and volcanic tremor data at Mt. Etna, Italy

    Science.gov (United States)

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

    2013-12-01

    Mt Etna in Sicily is among the most intensely monitored and studied volcanoes on Earth due to its very frequent activity, and its location in a densely populated area. Through a sophisticated monitoring system run by the Istituto Nazionale di Geofisica e Vulcanologia - Osservatorio Etneo (INGV-OE), scientists are gaining every day and in real time a picture of the state of volcanic activity of Etna. During the spring of 2007, various episodes of paroxysmal activity occurred at the South-East Crater, one of the four summit craters of Mt Etna. These episodes were always associated with a sharp increase in the amplitude of the volcanic tremor as well as changes in the spectral characteristics of this signal. Eruptive activity ranged from strong Strombolian explosions to lava fountains coupled with copious emission of lava flows and tephra. During inter-eruptive periods, recurrent seismic unrest episodes were observed in form of both temporary enhancements of the volcanic tremor amplitude as well as changes of spectral characteristics. These changes often triggered the automatic alert systems in the operation room of the INGV-OE, even though not being followed by manifest eruptive activity at the surface. The influence of man-made or meteorologically induced noise could be ruled out as a cause for the alarms. We therefore performed a multi-parametric analysis of these inter-eruptive periods by integrating seismic volcanic tremor, in-soil radon, plume SO2 flux and thermal data, discussing the potential volcano-dependent source of these episodes. Short-term changes were investigated applying pattern classification, in particular Kohonen Maps and fuzzy clustering, simultaneously on volcanic tremor, radon and ambient parameters (pressure and temperature). The well established SO2 flux and thermal radiation data were used as the 'smoking gun', for certifying that the observed changes in seismic and in radon data can be considered as volcanogenic. Our results unveil ';failed

  10. Volcano Monitoring and Early Warning on MT Etna, Italy, Using Volcanic Tremor - Methods and Technical Aspects

    Science.gov (United States)

    D'Agostino, Marcello; Di Grazia, Giuseppe; Ferrari, Ferruccio; Langer, Horst; Messina, Alfio; Reitano, Danilo; Spampinato, Salvatore

    2013-04-01

    Recent activity on Mt Etna was characterized by 25 lava fountains occurred on Mt Etna in 2011 and the first semester of 2012. In summer 2012 volcanic activity in a milder form was noticed within the Bocca Nuova crater, before it came to an essential halt in August 2012. Together with previous unrests (e. g., in 2007-08) these events offer rich material for testing automatic data processing and alert issue in the context of volcano monitoring. Our presentation focuses on the seismic background radiation - volcanic tremor - which has a key role in the surveillance of Mt Etna. From 2006 on a multi-station alert system exploiting STA/LTA ratios, has been established in the INGV operative centre of Catania. Besides, also the frequency content has been found to change correspondingly to the type of volcanic activity, and can thus be exploited for warning purposes. We apply Self Organizing Maps and Fuzzy Clustering which offer an efficient way to visualize signal characteristics and its development with time. These techniques allow to identify early stages of eruptive events and automatically flag a critical status before this becomes evident in conventional monitoring techniques. Changes of tremor characteristics are related to the position of the source of the signal. Given the dense seismic network we can base the location of the sources on distribution of the amplitudes across the network. The locations proved to be extremely useful for warning throughout both a flank eruption in 2008 as well as the 2011 lava fountains. During all these episodes a clear migration of tremor sources towards the eruptive centres was revealed in advance. The location of the sources completes the picture of an imminent volcanic unrest and corroborates early warnings flagged by the changes of signal characteristics. Automatic real time data processing poses high demands on computational efficiency, robustness of the methods and stability of data acquisition. The amplitude based multi

  11. Detection and Classification of Volcanic Earthquakes/Tremors in Central Anatolian Volcanic Province

    Science.gov (United States)

    Kahraman, Metin; Arda Özacar, A.; Bülent Tank, S.; Uslular, Göksu; Kuşcu, Gonca; Türkelli, Niyazi

    2017-04-01

    Central Anatolia has been characterized by active volcanism since 10 Ma which created the so called Central Anatolia Volcanic Province (CAVP) where a series of volcanoes are located along the NE-SW trend. The petrological investigations reveal that the magma source in the CAVP has both subduction and asthenospheric signature possibly due to tearing of ongoing northward subduction of African plate along Aegean and Cyprus arcs. Recently, a temporary seismic array was deployed within the scope of Continental Dynamics: Central Anatolian Tectonics (CD-CAT) project and provided a unique opportunity to study the deep seismic signature of the CAVP. Passive seismic imaging efforts and magnetotellurics (MT) observations revealed low velocity and high conductivity zones supporting the presence of localized partial melt bodies beneath the CAVP at varying depths, especially around Mt. Hasan which exhibits both geological and archeological evidences for its eruption around 7500 B.C. In Central Anatolia, local seismicity detected by the CD-CAT array coincides well with the active faults zones. However, active or potentially active volcanoes within CAVP are characterized by the lack of seismic activity. In this study, seismic data recorded by permanent stations of Regional Earthquake-Tsunami Monitoring Center were combined with temporary seismic data collected by the CD-CAT array to improve sampling density across the CAVP. Later, the continuous seismic waveforms of randomly selected time intervals were manually analyzed to identify initially undetected seismic sources which have signal characters matching to volcanic earthquakes/tremors. For candidate events, frequency spectrums are constructed to classify the sources according to their physical mechanisms. Preliminary results support the presence of both volcano-tectonic (VT) and low-period (LT) events within the CAVP. In the next stage, the spectral and polarization analyses techniques will be utilized to the entire seismic

  12. Global survey of earthquakes and non-volcanic tremor triggered by the 2008 Mw7.9 Wenchuan earthquake

    Science.gov (United States)

    Jiang, T.; Peng, Z.; Wang, W.; Chen, Q.

    2008-12-01

    We perform a global survey of triggered earthquakes and non-volcanic tremor by the 2008 Mw7.9 Wenchuan earthquake. The analyzed data is obtained from the Global Seismic Network and various local and regional seismic networks around the world. We identify triggered earthquakes as impulsive seismic energies with clear P and S arrivals on 5 Hz high-pass-filtered three-component velocity seismograms, and triggered tremor as bursts of high-frequency, non-impulsive seismic energies that are coherent among many stations and during the passage of teleseismic body and surface waves. We find wide-spread triggering of regular earthquakes within mainland China and elsewhere in the world. The triggered earthquakes mostly occur in tectonically active regions in northwest and northeast China. However, we also find clear evidence of triggered earthquakes in southeast China that is not tectonically active. Our observations are consistent with previous studies of earthquake triggering (e.g., Gomberg et al., 2004; Velasco et al., 2008), indicating that dynamic triggering of earthquakes is ubiquitous and independent of the tectonic environments. In comparison, clear triggered tremor associated with the Wenchuan earthquake is found in the Taiwan Island (Chao and Peng, 2008), southwest Japan, Cascadia (Vidale et al., 2008), and around the Parkfield section of the San Andreas fault (Peng et al., 2008), where regular and/or triggered tremor has been found before. So far we have not found clear evidence of triggered tremor within mainland China. At least part of the reason could be due to severe clippings of the broadband waveforms during large-amplitude surface waves for many stations within 2000 km of the epicenter. Updated results will be presented at the meeting.

  13. Tremor

    Science.gov (United States)

    ... interferes with your daily activities or causes embarrassment. Treatment depends on the cause. Tremor caused by a medical condition, such as hyperthyroidism, will likely get better when the condition is ...

  14. Tremor

    Science.gov (United States)

    ... physical activity, travel, and social engagements to avoid embarrassment or other consequences. The symptoms of essential tremor ... on the treatment or care of an individual patient should be obtained through consultation with a physician ...

  15. The physics of non-volcanic tremor: insights from laboratory-scale earthquakes

    Science.gov (United States)

    di Toro, G.; Meredith, P.

    2012-04-01

    Due to his extensive early experience in field structural geology, Luigi Burlini's experimental research was always aimed at using laboratory techniques and simulations to improve our understanding of the physics of natural rock deformation. Here we present an example of collaborative work from the later part of his scientific career in which the main goal was unravelling the physics of non-volcanic tremor in subduction zones. This was achieved by deforming typical source rocks (serpentinites) under conditions (300 MPa and 600oC) that approach those expected in nature (up to 1 GPa and 500oC). The main technical challenge was to capture deformation-induced microseismicity (in the form of acoustic emissions) released under such extreme conditions by means of in-situ transducers designed to work at only modest temperatures (up to 200oC). The main scientific challenges were (1) to link the acoustic emission output to specific physical processes, such as cracking, fluid flow or fluid-crack interactions, by means of waveform and microstructural analysis; and (2) to extrapolate the laboratory acoustic emission signals (kHz to MHz frequency) associated with mm to cm-scale processes, to natural seismicity (0.1-1 Hz frequency) associated with km-scale rock volumes by means of frequency scaling (Aki and Richards, 1980). Episodic tremor and slip (ETS) has been correlated with rupture phenomena in subducting oceanic lithosphere at 30 to 45 km depth, where high Vp/Vs ratios, suggestive of high-fluid pressure, have also been observed. ETS, by accommodating slip in the down-dip portion of the subduction zone, may trigger megathrust earthquakes up-dip in the locked section. In our experiments we measured the output of acoustic emissions during heating of serpentinite samples to beyond their equilibrium dehydration temperature. Experiments were performed on cores samples 15 mm in diameter by 30 mm long under hydrostatic stresses of 200 or 300 MPa in a Paterson high

  16. Non-Volcanic Tremors beneath the Southern Central Range in Taiwan

    Science.gov (United States)

    Sun, W.; Lin, C.; Peng, Z.; Chao, K.

    2011-12-01

    Deep non-volcanic tremors (NVT) triggered by teleseismic surface waves have been systematically observed in the Central Range in Taiwan recently. The discovery of NVT in Taiwan, as an arc-continental type collision environment, would provide us better understanding of critical conditions related to tremor occurrence and of the fault mechanics at the bottom of the seismogenic layer. Aiming to capture more NVT events, we have further installed two dense 36-element, small-aperture seismic arrays in the Liouguei and Lidao areas. Two arrays are respectively located about 20 km in southwest and northeast to the tremor sources reported at the southern Central Range of Taiwan. In each array, the short-period, vertical-channel GS-11D sensors with 4.5Hz natural frequency were laid out on the relatively flat parts of the mountain areas in a grid of approximately 100 by 80 meters. We had successfully recorded nine sets of continuous seismic data for totally 4034 hours among the first half year of 2011. Among those data, as we expected, the two arrays recorded clear tremors triggered by the great Tohoku earthquake (Mw=8.9) on 2011/03/11. Based on the beamforming results of the western and eastern arrays, the possible tremor sources come from N60E and just beneath it, respectively. Therefore, we believe the possible source of triggered tremors were nearby the Lidao area. Since the array analysis is able to significantly increase the level of tremor detection, we are examining other possible NVT events during the deployed period and the possible conditions related to NVT events, such as the passing seismic waves from other large regional earthquakes.

  17. Linear stability of plane Poiseuille flow in an infinite elastic medium and volcanic tremors

    Science.gov (United States)

    Sakuraba, Ataru; Yamauchi, Hatsuki

    2014-12-01

    The linear stability of a plane compressible laminar (Poiseuille) flow sandwiched between two semi-infinite elastic media was investigated with the aim of explaining the excitation of volcanic tremors. Our results show that there are several regimes of instability, and the nature of stability significantly depends on the symmetry of oscillatory fluid and solid motion. It has been shown that long-wave symmetric instability occurs at a very small value of the Reynolds number, but it is unlikely that this is the cause of volcanic tremors. We show that antisymmetric (flexural) instability also occurs, involving two parallel Rayleigh waves traveling against the Poiseuille flow, but the critical flow speed is faster than that of symmetric instability. However, if the basic flow profile is nonparabolic because of a nonuniform driving force or nonuniform viscosity, the critical flow speed of antisymmetric instability can be considerably slower than that of symmetric instability. Based on numerical calculations and analytical consideration, we conclude that this anomalous antisymmetric instability is possibly produced by a basaltic magma flow of a few meters per second through a dike with thickness of 1 m and extending for several kilometers; this origin can explain some of the characteristics of volcanic tremors.

  18. Locating non-volcanic tremor along the San Andreas Fault using a multiple array source imaging technique

    Science.gov (United States)

    Ryberg, T.; Haberland, C.H.; Fuis, G.S.; Ellsworth, W.L.; Shelly, D.R.

    2010-01-01

    Non-volcanic tremor (NVT) has been observed at several subduction zones and at the San Andreas Fault (SAF). Tremor locations are commonly derived by cross-correlating envelope-transformed seismic traces in combination with source-scanning techniques. Recently, they have also been located by using relative relocations with master events, that is low-frequency earthquakes that are part of the tremor; locations are derived by conventional traveltime-based methods. Here we present a method to locate the sources of NVT using an imaging approach for multiple array data. The performance of the method is checked with synthetic tests and the relocation of earthquakes. We also applied the method to tremor occurring near Cholame, California. A set of small-aperture arrays (i.e. an array consisting of arrays) installed around Cholame provided the data set for this study. We observed several tremor episodes and located tremor sources in the vicinity of SAF. During individual tremor episodes, we observed a systematic change of source location, indicating rapid migration of the tremor source along SAF. ?? 2010 The Authors Geophysical Journal International ?? 2010 RAS.

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

    Science.gov (United States)

    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

  20. Physical modeling of volcanic tremor as repeating stick-slip earthquakes

    Science.gov (United States)

    Dmitrieva, K.; Dunham, E. M.

    2011-12-01

    One proposed explanation for volcanic tremor is the occurrence of repeating earthquakes, leading to a quasi-periodic signal on seismograms. A constant time interval between events leads, through the Dirac comb effect, to spectral peaks in the frequency domain, with the fundamental frequency given by the reciprocal of the interevent time. Gliding harmonic tremor, in which the frequencies of the spectral peaks vary with time, was observed before the 2009 eruption of Redoubt Volcano in Alaska [A. Hotovec, S. Prejean, J. Vidale and J. Gomberg, J. Volc. Geotherm. Res., submitted]. The fundamental frequency grew from 1 to over 20 Hz over the few minutes prior to the explosions, with seismicity then ceasing for 10 s before each explosion. We investigate the viability of the repeating earthquakes theory, using well-established physical models of earthquake cycles on frictional faults. Hotovec et al. locate the repeating earthquakes near the conduit about 1 km depth below the vent. They estimate a source dimension 10-100 m, assuming typical earthquake magnitude scaling laws. We analyze the fault mechanics with a spring-slider model with stiffness κ μ/R, where μ is the shear modulus and R is the fault dimension. The fault obeys a rate-and-state friction law. In response to a constant shear stressing rate α, the fault can either slide at constant velocity V=α/κ or undergo stick-slip oscillations. We perform a stability analysis on this system to determine the critical values of the parameters governing stick-slip and stable-sliding regimes. At high stressing rates it is necessary to consider inertial effects, captured here through the radiation damping approximation. Radiation damping stabilizes the system at sufficiently high α, namely α>αcr=κ2Lq/η, where q=σ(b-a)/(κL)-1, η=μ/c is the radiation damping parameter, c is the shear wave velocity, L is the state evolution distance, σ is the normal stress, and a and b are the usual rate and state friction

  1. Characteristics and interactions between non-volcanic tremor and related slow earthquakes in the Nankai subduction zone, southwest Japan

    Science.gov (United States)

    Obara, Kazushige

    2011-10-01

    Non-volcanic tremor and related slow earthquakes in subduction zones are one of the most significant and exciting geophysical discoveries of the 21st century. In Japan, some types of slow earthquakes associated with subduction of the Philippine Sea Plate have been detected by dense seismic and geodetic observation networks equipped with continuous data-recording systems. At the deepest part of the transition between the Nankai megathrust seismogenic zone and the deep stable sliding zone, short-term slow slip events (SSE) occur on the plate interface with durations of days, accompanied by tremor and deep very-low-frequency (VLF) earthquakes resulting from interplate shear stick-slip motions. Along-strike source regions of tremor are divided into segments where these three coupling phenomena (tremor, short-term SSEs, and deep VLF earthquakes) occur at regular recurrence intervals, with durations of 2-6 months. On the updip side of the tremor zone, long-term SSEs with durations of years occur at intervals of 5-10 yrs and trigger tremor at the downdip part of the source region of long-term slip. Near the Nankai trough, shallow VLF earthquakes occur in the accretionary prism. At the eastern edge of the subducting Philippine Sea Plate, short-term SSEs recur every 6 yrs, associated with active earthquake swarms. Some of these slow earthquakes have been detected in other subduction zones; however, the properties of each constituent member of slow earthquakes are different in each subduction zone. Slow earthquakes represent transient shear slip around the seismogenic portion of major interplate megathrust faults; therefore, monitoring the relationship between slow earthquakes and interplate megathrust earthquakes is important for intermediate- and long-term predictions of the next major earthquake.

  2. Possible Non-volcanic Tremor Discovered in the Reelfoot Fault Zone, Northern Tennessee

    Science.gov (United States)

    Langston, C. A.; Williams, R. A.; Magnani, M.; Rieger, D. M.

    2007-12-01

    A swarm of ~80 microearthquakes was fortuitously detected in 20, 14 second-duration long-offset vibroseis shotgathers collected for a seismic reflection experiment near Mooring, TN, directly over the Reelfoot fault zone on the afternoon of 16 November 2006. These natural events show up in the shotgathers as near-vertically incident P waves with a dominant frequency of 10-15 Hz. The reflection line was 715m in length consisting of 144 channels with a sensor spacing of 5m, 8Hz vertical geophones, and recording using a Geometrics 24bit Geode seismograph. Small variations in event moveout across the linear array indicate that the seismicity was not confined to the same hypocenter and probably occurred at depths of approximately 10 km. The largest events in the series are estimated to have local magnitudes of ~-1 if at 10 km distance from the array. This is about 2.5 magnitude units lower than the threshold for local events detected and located by the CERI cooperative network in the area. The seismicity rate was ~1000 events per hour based on the total time duration of the shotgathers. The expected number of earthquakes of ML greater than or equal to -1 for the entire central United States is only 1 per hour. This detection of microseismic swarms in the Reelfoot fault zone indicates active physical processes that may be similar to non-volcanic tremor seen in the Cascadia and San Andreas fault zones and merits long-term monitoring to understand its source.

  3. Discriminating Tectonic Tremor from Magmatic Processes in Observationally Challenging Environments

    Science.gov (United States)

    Brown, J. R.; Beroza, G. C.

    2011-12-01

    Deep tectonic tremor is a long-duration, low amplitude signal that has been shown to consist of low frequency earthquakes (LFEs) on the plate interface in subduction zones. Detecting LFEs from tremor-like signals in subduction settings can be challenging due to the combination of volcanic seismicity and sparse station geometry. This is particularly true for island arcs such as the Alaska-Aleutian subduction zone where the islands are small and noise levels are high. We have detected and located LFEs within tremor signals along the Alaska-Aleutian Arc in four locations: Kodiak Island, Alaska Peninsula, eastern Aleutians, and the Andreanof Islands. In all areas, the LFEs are located 10-40 km trenchward of the volcanic chain at depths ranging from 45-70 km. Location errors are significant (+/- 20 km in depth) due to sparse station geometry such that there is the possibility that the tremor could be associated with nearby volcanoes. Since most documented volcanic tremor is located in the shallow crust, it can often be discriminated from tectonic tremor simply based on location. However, deep volcanic tremor has been documented in Hawaii to depths of 40 km and could be more widespread. In the Aleutian arc, deep long period events (DLPs), which are thought to result from the movement of magma and volatiles, have been located as deep as 45 km and sometimes resemble tremor-like signals. The spectral character is another potential discriminant. We compare the cepstra (Fourier transform of the logarithmic power spectrum of a time series) of the tectonic tremor-like signals/LFEs and DLPs associated with volcanoes. Source characteristics of DLPs (non-shear slip) and tectonic tremor/LFEs (shear slip) are distinct and should be noticeable in the cepstral domain. This approach of using tremor locations and cepstral analysis could be useful for detecting and differentiating tectonic tremor from deep volcanic processes in other island arcs as well.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  6. Polarization analysis of non-volcanic tremor at Guerrero subduction zone (Mexico)

    Science.gov (United States)

    Palo, M.; Capuano, P.

    2012-04-01

    Since its first observation occurred about ten years ago in Japan, non-volcanis tremor (NVT) has been observed in many areas worldwide. NVT is generally associated with fluid movements in the lithosphere and, together with the slow-slip events, are considered a key factor to understand the stress state and stress transfer in tectonic frameworks, especially in subduction zones. Here, we analyze the polarization properties of the NVTs recorded at Guerrero subduction segment of the Cocos plate (Mexico). The Guerrero subduction segment represents a very important case study for its seismic gap. Indeed, there is an absence of large earthquakes in this part of the subducting plate for the last hundred years, and this segment is expected to be able to originate an earthquake of magnitude 8. NVT at Guerrero is a long-duration, low-amplitude, nonimpulsive seismic radiation with most energy concentrated in the frequency range 1-8 Hz. These events have been located at a depth of 20-50 km mainly in correspondence of the tip of the mantle wedge [Payero et al., 2008; Kostoglodov et al., 2010]. Data-set is composed of one year (2006) long continuous seismic recordings of five three-component broad-band stations belonging to the seismic network installed during MASE experiment (available on IRIS website). We apply the Kanasewich algorithm to the continuous seismic recordings. This algorithm performs the diagonalization of the covariance matrix constructed using the three ground motion components and provides three parameters describing the polarization properties: the azimuth and dip angles constrain the direction of oscillation in a Cartesian reference frame, whereas the rectilinearity indicates if the oscillation is circular, elliptical or linear. We find that the NVT events can be detected looking at the time pattern of the polarization parameters. In detail, during NVT the dispersion of all the parameters decreases, the dip angle focuses on high values (indicating shallow

  7. Characteristics of seismic waves composing Hawaiian volcanic tremor and gas-piston events observed by a near-source array

    Science.gov (United States)

    Ferrazzini, Valerie; Aki, Keiiti; Chouet, Bernard

    1991-04-01

    A correlation method, specifically designed for describing the characteristics of a complex wave field, is applied to volcanic tremor and gas-piston events recorded by a semicircular array of GEOS instruments set at the foot of the Puu Oo crater on the east rift of Kilauea volcano, Hawaii. The spatial patterns of correlation coefficients obtained as functions of frequency for the three components of motion over the entire array are similar for gas-piston events and tremor, and clearly depict dispersive waves propagating across the array from the direction of Puu Oo. The wave fields are composed of comparable amounts of Rayleigh and Love waves propagating with similar and extremely slow phase velocities ranging from 700 m/s at 2 Hz to 300 m/s at 8 Hz. The highly cracked solidified lava flow on which the array was deployed, and subjacent structure of alternating lava and ash layers formed during repeated eruptions of Puu Oo since 1983, appear to be responsible for the low velocities observed. The results from Puu Oo stand in sharp contrast to those obtained in an experiment conducted in 1976 on the partially solidified lava lake of Kilauea Iki. Rayleigh waves were not observed in Kilauea Iki, but well-developed trains of Love waves were seen to propagate there with velocities twice as high as those observed near Puu Oo. These differences in the propagation characteristics of surface waves at the two sites may be attributed to the presence of a soft horizontal layer of molten rock in Kilauea Iki, which may have lowered the phase velocity of Rayleigh waves more drastically than that of Love waves, resulting in severe scattering of the Rayleigh wave mode. On the other hand, the thin superficial pahoehoe flow under our array at Puu Oo may have favored the development of vertical columnar joints more extensively at this location than at Kilauea Iki, which may have reduced the shear moduli controlling the Love wave mode. The average phase velocities in the frequency band

  8. Episodic tremor and slip in Northern Sumatra subduction zone

    Science.gov (United States)

    Sianipar, Dimas; Subakti, Hendri

    2017-07-01

    The first reported observation of non-volcanic tremor in Sunda Arc in Sumbawa, Indonesia open a possibility of discovery of episodic tremor and slip (ETS) from out of Pacific Rim. Non-volcanic tremor gives some important information about dynamic of plate boundaries. The characteristics of these tremors are visually as non-impulsive, high frequency, long-duration and low-amplitude signals. Tectonic tremor occurred in a transition part of brittle-ductile of a fault and frequently associated with the shearing mechanism of slow slip. Tectonic tremor is a seismic case that also very interested, because it shows strong sensitivity to stress changes. Deep non-volcanic tremor is usually associated with episodic slow-slip events. Tectonic tremor is found in close association with geodetically observed slow-slip events (SSE) in subduction zones. One research found that there is possibility of SSE occurrence on Banyak Islands, North Sumatra revealed from coral observation. The SSE occurred on the Banyak Islands portion of the megathrust at 30-55 km depth, within the downdip transition zone. We do a systematic search of episodic tremor and its possible relationship with slow-slip phenomena in Northern Sumatra subduction zone. The spectrogram analysis is done to analyze the potential tremor signals. We use three component broadband seismic stations with 20, 25, and 50 sampling per second (BH* and SH* channels). We apply a butterworth 5 Hz highpass filter to separate the signal as local tremor and teleseismic/regional earthquakes. Before computing spectrogram to avoid high-frequency artifacts to remote triggering, we apply a 0.5 Hz filter. We also convert the binary seismic data into sound waves to make sure that these events meet the tectonic tremor criterion. We successfully examine 3 seismic stations with good recording i.e. GSI, SNSI and KCSI. We find there are many evidences of high frequency episodic tremor like signals. This include an analysis of potential triggered

  9. Approach to a tremor patient

    Directory of Open Access Journals (Sweden)

    Soumya Sharma

    2016-01-01

    Full Text Available Tremors are commonly encountered in clinical practice and are the most common movement disorders seen. It is defined as a rhythmic, involuntary oscillatory movement of a body part around one or more joints. In the majority of the population, tremor tends to be mild. They have varying etiology; hence, classifying them appropriately helps in identifying the underlying cause. Clinically, tremor is classified as occurring at rest or action. They can also be classified based on their frequency, amplitude, and body part involved. Parkinsonian tremor is the most common cause of rest tremor. Essential tremor (ET and enhanced physiological tremor are the most common causes of action tremor. Isolated head tremor is more likely to be dystonic rather than ET. Isolated voice tremor could be considered to be a spectrum of ET. Psychogenic tremor is not a diagnosis of exclusion; rather, demonstration of various clinical signs is needed to establish the diagnosis. Severity of tremor and response to treatment can be assessed using clinical rating scales as well as using electrophysiological measurements. The treatment of tremor is symptomatic. Medications are effective in half the cases of essential hand tremor and in refractory patients; deep brain stimulation is an alternative therapy. Midline tremors benefit from botulinum toxin injections. It is also the treatment of choice in dystonic tremor and primary writing tremor.

  10. Systematic Search of Remotely Triggered Tremor in Northern and Southern California

    Science.gov (United States)

    Fabian, A.; Ojha, L.; Peng, Z.; Chao, K.

    2009-12-01

    Non-volcanic tremor is a seismic signal observed away from volcanoes, and is characterized with long durations and no clear body wave arrivals. Recent studies have found that non-volcanic tremor can be triggered instantaneously during the surface waves of large teleseismic events in Central California, Japan, Cascadia, and Taiwan. However, it is still not clear how widespread the triggering phenomenon is, and what are the necessary conditions for tremor to occur. Here we conduct a systematic search of remotely triggered tremor in Northern and Southern California, focusing on the following regions with dense instrumentations: the Central Calaveras fault, the Northern Hayward fault, the San Jacinto fault near Hemet and the Simi Valley, and the San Gabriel Mountains. Out of the 30 large teleseismic events with Mw ≥ 7.5 since 2001, our visual inspection shows that only the 2002 Mw7.8 Denali Fault earthquake has triggered tremor in these regions, including the San Gabriel Mountains where neither triggered nor ambient tremor has been observed before. The tremor observed near the Calaveras fault and San Jacinto fault appears to be initiated by Love waves, and becomes intensified during the large amplitude Rayleigh waves. The tremor triggered in Simi Valley and San Gabriel Mountains only shows weak correlations with the Rayleigh waves. Our results suggest a lack of widespread triggering in Northern and Southern California, which is in contrast with the finding of multiple events that triggered tremor in Central California, Japan, Cascadia, and Taiwan. However, such observation is consistent with a general lack of ambient tremor activities in these regions. Possible reasons for a lack of widespread triggering in Northern and Southern California include: elevated background noises for surface stations that may hide weak triggered tremor signals, different ambient tremor rate, or different tremor triggering threshold in different regions. Updated results will be presented

  11. Simulation of Complex Tremor Migration Patterns

    Science.gov (United States)

    Luo, Y.; Ampuero, J. P.

    2012-12-01

    The discovery of slow-slip events (SSE) and non-volcanic tremors has greatly enriched the spectrum of earthquake behavior and offers a unique window into the mechanics of the deeper portion of the seismogenic zone of active faults, an uncharted region of great importance in the nucleation of large earthquakes. In Northern Cascadia, tremors show an intriguing hierarchy of migration patterns: large-scale tremor migrating along-strike at about 10 km/day, sparsely distributed swarms that propagate 10 times faster in the opposite direction ('rapid tremor reversals' or RTRs) and even 10 times faster swarms that propagate along-dip. Moreover, during the initial phase of ETS (Episodic Tremor and Slip) the tremor source amplitude shows a linear growth and up-dip propagation. We have proposed a model to reproduce these observations based on interaction of brittle asperities (frictionally unstable, velocity-weakening patches) embedded in a relatively stable fault, mediated by creep transients. We continue quantitative studies of this model through numerical simulations of heterogeneous rate-and-state faults under the Quasi-DYNamic approximation (open-source software project QDYN, hosted online at http://code.google.com/p/qdyn/). We performed both 2D and 3D simulations and successfully reproduced all the major phenomena of complex tremor migration patterns (forward migration, RTRs and along-dip swarms). We will show a complete analysis of friction properties and geometrical settings (i.e. asperity size, distance, etc.) that affects spatial-temporal distribution and migration velocity of tremors. Our study shows that by decreasing the distance between asperities or by increasing the value of (a-b)*sigma inside them, both RTR migration velocity and distance increase positively correlated, and the proportion of moment released seismically during the ETS increases, while the ratio of RTR versus forward tremor migration speed remains mostly the same. While the density of these deep

  12. Observations of two special kinds of tremor at Galeras volcano, Colombia(1989-1991

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    F. Gil-Cruz

    1999-06-01

    Full Text Available Since the reactivation of Galeras volcano in 1988 its seismic activity has been dominated by a variety of LP waveforms and tremor events. Some of these signals occurred as a response to volcanic activity. Among them, two kinds of tremor deserve special attention, Flute tremor and Spasmodic tremor. Flute tremor has a spectrum of equally spaced peaks and is associated with a quasi-steady degassing process at the top of the lava dome. It is accompanied by a flute-like sound. Its spectral features and the correlation with field observations are consistent with a model generation indicating that a crack or set of cracks are excited to resonance by the release and flow of gas through the lava dome. Spasmodic tremor is composed of several distinct LP-like events joined together by a continuous signal with lower amplitudes. Two types of spasmodic tremor may be distinguished on the basis of their spectral characteristics and field observations. Spasmodic tremor type I is apparently dominated by a mix of P, SH and Rayleigh waves as determined from preliminary polarization analysis. The source appears to be located, in a region west of the active crater. As a first approximation, Spasmodic tremor type I could be associated with magmatic intrusion process occurred in 1989-1991.

  13. Essential Tremor

    Science.gov (United States)

    ... propranolol or other beta blockers and primidone, an anticonvulsant drug. Eliminating tremor "triggers" such as caffeine and ... propranolol or other beta blockers and primidone, an anticonvulsant drug. Eliminating tremor "triggers" such as caffeine and ...

  14. Megathrust Earthquake Swarms Contemporaneous to Slow Slip and Non-Volcanic Tremor in Southern Mexico, Detected and Analyzed through a Template Matching Approach

    Science.gov (United States)

    Holtkamp, S.; Brudzinski, M. R.; Cabral-Cano, E.; Arciniega-Ceballos, A.

    2012-12-01

    An outstanding question in geophysics is the degree to which the newly discovered types of slow fault slip are related to their destructive cousin - the earthquake. Here, we utilize a local network along the Oaxacan segment of the Middle American subduction zone to investigate the potential relationship between slow slip, non-volcanic tremor (NVT), and earthquakes along the subduction megathrust. We have developed a multi-station "template matching" waveform cross correlation technique which is able to detect and locate events several orders of magnitude smaller than would be possible using more traditional techniques. Also, our template matching procedure is capable of consistently locate events which occur during periods of increased background activity (e.g., during productive NVT, loud cultural noise, or after larger earthquakes) because the multi-station detector is finely tuned to events with similar hypocentral location and focal mechanism. The local network in the Oaxaca region allows us to focus on documented megathrust earthquake swarms, which we focus on because slow slip is hypothesized to be the cause for earthquake swarms in some tectonic environments. We identify a productive earthquake swarm in July 2006 (~600 similar earthquakes detected), which occurred during a week-long episode of productive tremor and slow slip. Families of events in this sequence were also active during larger and longer slow slip events, which provides a potential link between slow slip in the transition zone and earthquakes at the downdip end of the seismogenic portion of the megathrust. Because template matching techniques only detect similar signals, detected waveforms can be stacked together to produce higher signal to noise ratios or cross correlated against each other to produce precise relative phase arrival times. We are using the refined signals to look for evidence of expansion or propagation of hypocenters during these earthquake swarms, which could be used as a

  15. The Clinical Evaluation of Parkinson's Tremor.

    Science.gov (United States)

    Zach, Heidemarie; Dirkx, Michiel; Bloem, Bastiaan R; Helmich, Rick 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 basis for further tailored treatment. This can be challenging, because Parkinson's tremor amplitude is typically very variable and context-dependent. Here, we outline how we investigate Parkinson's tremor in the clinic. We describe a simple set of clinical tasks that can be used to constrain tremor variability (cognitive and motor co-activation, several specific limb postures). This may help to adequately characterize the tremor(s) occurring in a patient with Parkinson's disease.

  16. Seismic moulin tremor

    Science.gov (United States)

    Roeoesli, Claudia; Walter, Fabian; Ampuero, Jean-Paul; Kissling, Edi

    2016-08-01

    Through glacial moulins, meltwater is routed from the glacier surface to its base. Moulins are a main feature feeding subglacial drainage systems and thus influencing basal motion and ice dynamics, but their geometry remains poorly known. Here we show that analysis of the seismic wavefield generated by water falling into a moulin can help constrain its geometry. We present modeling results of hour-long seimic tremors emitted from a vertical moulin shaft, observed with a seismometer array installed at the surface of the Greenland Ice Sheet. The tremor was triggered when the moulin water level exceeded a certain height, which we associate with the threshold for the waterfall to hit directly the surface of the moulin water column. The amplitude of the tremor signal changed over each tremor episode, in close relation to the amount of inflowing water. The tremor spectrum features multiple prominent peaks, whose characteristic frequencies are distributed like the resonant modes of a semiopen organ pipe and were found to depend on the moulin water level, consistent with a source composed of resonant tube waves (water pressure waves coupled to elastic deformation of the moulin walls) along the water-filled moulin pipe. Analysis of surface particle motions lends further support to this interpretation. The seismic wavefield was modeled as a superposition of sustained wave radiation by pressure sources on the side walls and at the bottom of the moulin. The former was found to dominate the wave field at close distance and the latter at large distance to the moulin.

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

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    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-...

  18. Treatment of patients with essential tremor.

    Science.gov (United States)

    Deuschl, Günther; Raethjen, Jan; Hellriegel, Helge; Elble, Rodger

    2011-02-01

    Essential tremor is a common movement disorder. Tremor severity and handicap vary widely, but most patients with essential tremor do not receive a diagnosis and hence are never treated. Furthermore, many patients abandon treatment because of side-effects or poor efficacy. A newly developed algorithm, based on the logarithmic relation between tremor amplitude and clinical tremor ratings, can be used to compare the magnitude of effect of available treatments. Drugs with established efficacy (propranolol and primidone) produce a mean tremor reduction of about 50%. Deep brain stimulation (DBS) in the thalamic nucleus ventrointermedius or neighbouring subthalamic structures reduces tremor by about 90%. However, no controlled trials of DBS have been done, and the best target is still uncertain. Better drugs are needed, and controlled trials are required to determine the safety and efficacy of DBS in the nucleus ventrointermedius and neighbouring subthalamic structures. Copyright © 2011 Elsevier Ltd. All rights reserved.

  19. The 2011 unrest at Katla volcano: Characterization and interpretation of the tremor sources

    Science.gov (United States)

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

    2017-05-01

    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 southern 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-correlations, two other phases have been located near the active ice cauldrons and are interpreted to be caused by volcanic or hydrothermal processes. The greatly increased seismicity and evidence of rapid melting of the glacier may be explained by a minor sub-glacial eruption. A less plausible interpretation is that the tremor was generated by hydrothermal boiling and/or explosions with no magma involved. This may have been induced by pressure drop triggered by the release of water when the glacial flood started. All interpretations require an increase of heat released by the volcano.

  20. A phase coherence approach to identifying co-located earthquakes and tremor

    Science.gov (United States)

    Hawthorne, J. C.; Ampuero, J.-P.

    2017-01-01

    We present and use a phase coherence approach to identify seismic signals that have similar path effects but different source time functions: co-located earthquakes and tremor. The method used is a phase coherence-based implementation of empirical matched field processing, modified to suit tremor analysis. It works by comparing the frequency-domain phases of waveforms generated by two sources recorded at multiple stations. We first cross-correlate the records of the two sources at a single station. If the sources are co-located, this cross-correlation eliminates the phases of the Green's function. It leaves the relative phases of the source time functions, which should be the same across all stations so long as the spatial extent of the sources are small compared with the seismic wavelength. We therefore search for cross-correlation phases that are consistent across stations as an indication of co-located sources. We also introduce a method to obtain relative locations between the two sources, based on back-projection of inter-station phase coherence. We apply this technique to analyze two tremor-like signals that are thought to be composed of a number of earthquakes. First, we analyze a 20-second-long seismic precursor to a M 3.9 earthquake in central Alaska. The analysis locates the precursor to within 2 km of the mainshock, and it identifies several bursts of energy-potentially foreshocks or groups of foreshocks-within the precursor. Second, we examine several minutes of volcanic tremor prior to an eruption at Redoubt Volcano. We confirm that the tremor source is located close to repeating earthquakes identified earlier in the tremor sequence. The amplitude of the tremor diminishes about 30 seconds before the eruption, but the phase coherence results suggest that the tremor may persist at some level through this final interval.

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    Asch, Guenter; Wylegalla, K.; Hellweg, M.; Seidl, D.; Rademacher, H.

    1996-01-01

    During the Proyecto de Investigacio??n Sismolo??gica 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.

  3. Unusual Forehead Tremor in Four Patients with Essential Tremor

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    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.

  4. The Clinical Evaluation of Parkinson’s Tremor

    Science.gov (United States)

    Zach, Heidemarie; Dirkx, Michiel; Bloem, Bastiaan R.; Helmich, Rick C.

    2015-01-01

    Abstract 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 basis for further tailored treatment. This can be challenging, because Parkinson’s tremor amplitude is typically very variable and context-dependent. Here, we outline how we investigate Parkinson’s tremor in the clinic. We describe a simple set of clinical tasks that can be used to constrain tremor variability (cognitive and motor co-activation, several specific limb postures). This may help to adequately characterize the tremor(s) occurring in a patient with Parkinson’s disease. PMID:26406126

  5. Essential Tremor Is More Than a Tremor

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    Full Text Available Home About the IETF Volunteer For Healthcare Providers Giving Options Donate Prev Next IETF > About Essential Tremor > ... Parkinson’s disease and essential tremor symptoms Raving Fan Home About the IETF Volunteer For Healthcare Providers Giving ...

  6. Essential Tremor Is More Than a Tremor

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    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 ...

  7. Essential Tremor Is More Than a Tremor

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    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 ...

  8. Dopamine controls Parkinson's tremor by inhibiting the cerebellar thalamus.

    Science.gov (United States)

    Dirkx, Michiel F; den Ouden, Hanneke E M; Aarts, Esther; Timmer, Monique H M; Bloem, Bastiaan R; Toni, Ivan; Helmich, Rick C

    2017-01-09

    Parkinson's resting tremor is related to altered cerebral activity in the basal ganglia and the cerebello-thalamo-cortical circuit. Although Parkinson's disease is characterized by dopamine depletion in the basal ganglia, the dopaminergic basis of resting tremor remains unclear: dopaminergic medication reduces tremor in some patients, but many patients have a dopamine-resistant tremor. Using pharmacological functional magnetic resonance imaging, we test how a dopaminergic intervention influences the cerebral circuit involved in Parkinson's tremor. From a sample of 40 patients with Parkinson's disease, we selected 15 patients with a clearly tremor-dominant phenotype. We compared tremor-related activity and effective connectivity (using combined electromyography-functional magnetic resonance imaging) on two occasions: ON and OFF dopaminergic medication. Building on a recently developed cerebral model of Parkinson's tremor, we tested the effect of dopamine on cerebral activity associated with the onset of tremor episodes (in the basal ganglia) and with tremor amplitude (in the cerebello-thalamo-cortical circuit). Dopaminergic medication reduced clinical resting tremor scores (mean 28%, range -12 to 68%). Furthermore, dopaminergic medication reduced tremor onset-related activity in the globus pallidus and tremor amplitude-related activity in the thalamic ventral intermediate nucleus. Network analyses using dynamic causal modelling showed that dopamine directly increased self-inhibition of the ventral intermediate nucleus, rather than indirectly influencing the cerebello-thalamo-cortical circuit through the basal ganglia. Crucially, the magnitude of thalamic self-inhibition predicted the clinical dopamine response of tremor. Dopamine reduces resting tremor by potentiating inhibitory mechanisms in a cerebellar nucleus of the thalamus (ventral intermediate nucleus). This suggests that altered dopaminergic projections to the cerebello-thalamo-cortical circuit have a role

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

    Directory of Open Access Journals (Sweden)

    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.

  10. Polarization of Tremor Wave-field Before and During The July-august 2001 Mt. Etna Eruption

    Science.gov (United States)

    Ferrari, F.; Patanè, D.; del Pezzo, E.; Gresta, S.; Ibanez, J.; Saccarotti, G.; Scarfi, L.

    One of the most important lateral eruptive events in the last 30 years started in July 2001, which has been characterized by an unusual eruptive style, with lava flow emis- sions at different quotes along a complex fracture system, frequent and power strom- bolian explosions sometimes culminating in lava fountains and abundant gas emis- sions. Apart from tectonic seismicity, volcanic tremor had a key role in monitoring the evolution of the eruption. Paroxysmal phases such as lava fountains and power- ful strombolian activity were associated with remarkable increments in the amplitude of tremor. Although with some fluctuation, high amplitude values maintained after the opening of the eruptive fractures, reaching a maximum on July 25. An inversion of this trend started in the late morning on July 31, when a sudden decrease in the amplitude of tremor occurred. In this work, polarization of the tremor wave-field, recorded simultaneously at 12 three-component digital stations, equipped with short period (1s) or broad-band (20s) sensors, is analyzed by use of a polarization filter. Spectrograms show predominant energy into 1-6ÿ7 Hz frequency band. Before and during the July-August 2001 Mt. Etna eruption, significant variations with time of direction of polarization, incidence angle and linear content of the tremor wave-field are found mainly on the broad-band recordings at frequencies lower than ca. 1.5 Hz. This is in agreement with temporal modifications of the activity observed during the pre- and the eruptive period. Moreover, we observe that the tremor shows steady hor- izontal, near-linear, ca. west-east pattern, at several stations (TDF, MNT, ESP, ERS, EC11). Such a behaviour excludes confinement of the source to the only active vents and suggests the possibility that a vertical extended source with overall north-south alignment might radiate SH waves, in the direction normal to the source.

  11. Real-Time Estimation of Pathological Tremor Parameters from Gyroscope Data

    Directory of Open Access Journals (Sweden)

    José L. Pons

    2010-03-01

    Full Text Available This paper presents a two stage algorithm for real-time estimation of instantaneous tremor parameters from gyroscope recordings. Gyroscopes possess the advantage of providing directly joint rotational speed, overcoming the limitations of traditional tremor recording based on accelerometers. The proposed algorithm first extracts tremor patterns from raw angular data, and afterwards estimates its instantaneous amplitude and frequency. Real-time separation of voluntary and tremorous motion relies on their different frequency contents, whereas tremor modelling is based on an adaptive LMS algorithm and a Kalman filter. Tremor parameters will be employed to drive a neuroprosthesis for tremor suppression based on biomechanical loading.

  12. Mapping Yakutat Subduction with Tectonic Tremor

    Science.gov (United States)

    Wech, A.

    2015-12-01

    Subduction of the Yakutat microplate (YAK) in south-central Alaska may be responsible for regional high topography, large slip during the 1964 earthquake, and the anomalous gap in arc volcanism, but the exact geodynamics and its relationship with the underlying Pacific Plate (PP) are not fully understood. Refraction data support distinct subducting layers, and both GPS and body wave tomography suggest the YAK extends from the Cook Inlet volcanoes in the west to the Wrangell volcanic field in the east. Earthquakes, however, are limited to normal faulting within the PP with an abrupt eastern boundary 80 km west of the inferred YAK edge, and more recent active source seismic data suggest subduction of one homogenous thickened oceanic plateau. Here, I perform a search for tectonic tremor to investigate the role of tremor and slow slip in the system. I scan continuous waveforms from 2007-2015 using all available data from permanent and campaign seismic stations in south-central Alaska. Using envelope cross-correlation, I detect and locate ~9,000 tectonic tremor epicenters, providing a map of the transition zone downdip of the 1964 earthquake. Tremor epicenters occur downdip of discrete slow slip events, and tremor rates do not correlate temporally with slow slip behavior. Depth resolution is poor, but horizontal locations are well constrained and spatially correlate with the velocity images of the YAK. Likewise, tremor extends 80 km further east than intraslab seismicity. Tremor swarms occur intermittently and manifest as ambient tremor. I interpret tremor to mark slow, semi-continuous slip occurring at the boundary between the YAK and North American plates, whose interface continues beyond the eastern edge of the PP. In this model, the YAK is welded to the underlying PP in the west, but extends past the eastern terminus of the PP. This geometry explains the correlation between tremor and the YAK, the discrepancy between deep seismicity and tremor, and the paucity of

  13. Seismic Tremor Generated by Multiple Processes, Vatnajökull Glacier, Iceland

    Science.gov (United States)

    Eibl, E. P. S.; Bean, C. J.; Vogfjord, K. S.

    2014-12-01

    Vatnajökull glacier in eastern Iceland covers five volcanic systems in which Bárdarbunga and Grimsvötn are the most active volcanoes. Whilst fluctuating ice cover mitigates against year-round near-field monitoring of the volcanoes, important information can be gleaned from stations deployed at the glacier's edge. Glacial cover significantly increases the complexity of and the solution space for observed seismic signals. For example tremor can be caused by magmatic activity, intra-glacier interactions, melt water flow or hydrothermal boiling. A better understanding of hazard requires a more indepth understanding of the signals generated by these processes at Vatnajökull. We augmented the sparse network in the region with two seven-element broad band seismometer arrays west of Vatnajökull, in Jökulheimar and near Laki respectively. Observed seismic tremor-like transients (< 2 Hz) originating from two cauldrons west of Grimsvötn are directly associated with small flooding events (jökulhaups), as subsequently confirmed by radar and hydrological observations. For larger longer duration floods dominant harmonic tremor frequencies of 2 to 4 Hz are observed, but they change in amplitude and frequency with time, likely reflecting variable feed and flow rates, associated with a moving source. Our aim is to 'fingerprint' these events such that they can be distinguished from seismic tremor signals associated with magmatic activity.

  14. The phenomenology of parkinsonian tremor.

    Science.gov (United States)

    Deuschl, Günther; Papengut, Frank; Hellriegel, Helge

    2012-01-01

    The definition of Parkinsonian tremor covers all different forms occurring in Parkinson's disease. The most common form is rest tremor, labelled as typical Parkinsonian tremor. Other variants cover also postural and action tremors. Data support the notion that suppression of rest tremor may be more specific for PD tremors. Several differential diagnoses like rest tremor in ET, dystonic tremor, psychogenic tremor and Holmes' tremor may be misinterpreted as PD-tremor. Tests and clinical clues to separate them are presented. Copyright © 2011 Elsevier Ltd. All rights reserved.

  15. Quantifying tectonic tremor in southern Mexico and its curious relationship to slow slip and other tremor triggers

    Science.gov (United States)

    Sit, S. M.; Brudzinski, M. R.

    2011-12-01

    The discoveries of tectonic tremor along with slow slip provide exciting new insights into fault deformation at major tectonic boundaries. Tremor and slip were first recorded in Cascadia, but have now been observed in a variety of other subduction zones. Recent studies in Oaxaca, Mexico reveal both slow slip and tectonic tremor, but analysis of the most prominent tremor finds it occurs over a short time period of 2-10 days and recurs as often as every 2-3 months, while slow slip occurs much less frequently on the order of 12-24 months. This result was surprising considering that tremor and slip are so well correlated in Cascadia that a linear relationship exists between the number of tremor hours recorded and the moment of concurrent slow slip. In contrast, the first study of tremor in Oaxaca found prominent tremor episodes were only slightly more common during the 2-month slow slip event than the 6 months before or after. However, tremor is more difficult to detect in Oaxaca than Cascadia considering the frequent regional seismicity, seasonal storms, and limited seismic network. Here, we use our detection algorithm to investigate the prevalence of short period tremor, which may have gone undetected by the original processing of scanning 4-day average absolute amplitudes in the tremor passband. As an alternative, we utilize a recently developed technique for detecting tremor that takes advantage of the narrow frequency content by calculating the ratio of amplitudes in the tremor passband relative to amplitudes in higher and lower frequency passbands where regional seismicity and surface waves are more common, respectively. Results from this frequency ratio method are in good agreement with the original tremor detections and locations in Oaxaca and additionally, detect several previously unidentified low amplitude, short duration inter-ETS tremor events. Moreover, this detection technique will provide a more thorough estimate of tremor prevalence over time to test

  16. Bilateral primary writing tremor.

    Science.gov (United States)

    Jimenez-Jimenez; Cabrera-Valdivia; Orti-Pareja; Gasalla; Tallon-Barranco; Zurdo

    1998-11-01

    Primary writing tremor is a task-specific tremor that is considered to be unilateral. We report a 59-year-old man with a 5-year history of a typical primary writing tremor in the right hand who developed similar symptoms in the left hand. Copyright 1998 Lippincott Williams & Wilkins

  17. Phenomenology of tremor-like signals observed over hydrocarbon reservoirs

    NARCIS (Netherlands)

    Dangel, S.; Schaepman, M.E.; Stoll, E.P.; Carniel, R.; Barzandji, O.; Rode, E.D.; Singer, J.M.

    2003-01-01

    We have observed narrow-band, low-frequency (1.5-4 Hz, amplitude 0.01-10 mum/s) tremor signals on the surface over hydrocarbon reservoirs (oil, gas and water multiphase fluid systems in porous media) at currently 15 sites worldwide. These 'hydrocarbon tremors' possess remarkably similar spectral and

  18. Phenomenology of tremor-like signals observed over hydrocarbon reservoirs

    NARCIS (Netherlands)

    Dangel, S.; Schaepman, M.E.; Stoll, E.P.; Carniel, R.; Barzandji, O.; Rode, E.D.; Singer, J.M.

    2003-01-01

    We have observed narrow-band, low-frequency (1.5-4 Hz, amplitude 0.01-10 mum/s) tremor signals on the surface over hydrocarbon reservoirs (oil, gas and water multiphase fluid systems in porous media) at currently 15 sites worldwide. These 'hydrocarbon tremors' possess remarkably similar spectral and

  19. Tremor in the elderly

    DEFF Research Database (Denmark)

    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...... patients did not show an increased but rather a lower mortality rate although it was not statistically significant. Consistent with a slower than normal aging, they were also physically and cognitively better functioning than controls. Because incident tremors beyond 70 y of age show worse aging parameters...

  20. Study of Tectonic Tremor in Depth: Triggering Stress Observation and Model of the Triggering Mechanism

    Science.gov (United States)

    Wang, Tien-Huei

    Non-volcanic tremor (NVT) has been discovered in recent years due to advances in seismic instruments and increased density of seismic networks. The NVT is a special kind of seismic signal indicative of the physical conditions and the failure mechanism on the source on the fault where NVT occurs. The detection methods used and the sensitivity of them relies on the density, distance and instrumentation of the station network available. How accurately the tremor is identified in different regions varies greatly among different studies. Therefore, there has not been study that rigorously documents tectonic tremors in different regions under limited methods and data. Meanwhile, many incidences of NVTs are observed during or after small but significant strain change induced by teleseismic, regional or local earthquake. The understanding of the triggering mechanisms critical for tremor remains unclear. In addition, characteristics of the triggering of NVT in different regions are rarely compared because of the short time frame after the discovery of the triggered NVTs. We first explore tectonic tremor based on observations to learn about its triggering, frequency of occurrence, location and spectral characteristics. Then, we numerically model the triggering of instability on the estimated tremor-source, under assumptions fine-tuned according to previous studies (Thomas et al., 2009; Miyazawa et al., 2005; Hill, 2008; Ito, 2009; Rubinstein et al., 2007; Peng and Chao, 2008). The onset of the slip reveals that how and when the external loading triggers tremor. It also holds the information to the background stress conditions under which tremor source starts with. We observe and detect tremor in two regions: Anza and Cholame, along San Jacinto Fault (SJF) and San Andreas Fault (SAF) respectively. These two sections of the faults, relative to general fault zone on which general earthquakes occur, are considered transition zones where slip of slow rates occurs. Slip events

  1. Tremor frequency characteristics in Parkinson's disease under resting-state and stress-state conditions.

    Science.gov (United States)

    Lee, Hong Ji; Lee, Woong Woo; Kim, Sang Kyong; Park, Hyeyoung; Jeon, Hyo Seon; Kim, Han Byul; Jeon, Beom S; Park, Kwang Suk

    2016-03-15

    Tremor characteristics-amplitude and frequency components-are primary quantitative clinical factors for diagnosis and monitoring of tremors. Few studies have investigated how different patient's conditions affect tremor frequency characteristics in Parkinson's disease (PD). Here, we analyzed tremor characteristics under resting-state and stress-state conditions. Tremor was recorded using an accelerometer on the finger, under resting-state and stress-state (calculation task) conditions, during rest tremor and postural tremor. The changes of peak power, peak frequency, mean frequency, and distribution of power spectral density (PSD) of tremor were evaluated across conditions. Patients whose tremors were considered more than "mild" were selected, for both rest (n=67) and postural (n=25) tremor. Stress resulted in both greater peak powers and higher peak frequencies for rest tremor (pcharacteristics, namely a lower frequency as amplitude increases, are different in stressful condition. Patient's conditions directly affect neural oscillations related to tremor frequencies. Therefore, tremor characteristics in PD should be systematically standardized across patient's conditions such as attention and stress levels.

  2. Variations on tremor parameters

    Science.gov (United States)

    Boose, A.; Jentgens, Ch.; Spieker, S.; Dichgans, J.

    1995-03-01

    This paper describes our analysis procedure for long-term tremor EMG recordings, as well as three examples of applications. The description of the method focuses on how characteristics of the tremor (e.g. frequency, intensity, agonist-antagonist interaction) can be defined and calculated based on surface EMG data. The resulting quantitative characteristics are called ``tremor parameters.'' We discuss sinusoidally modulated, band-limited white noise as a model for pathological tremor-EMG, and show how the basic parameters can be extracted from this class of signals. The method is then applied to (1) estimate tremor severity in clinical studies, (2) quantify agonist-antagonist interaction, and (3) investigate the variations of the tremor parameters using simple methods from time-series analysis.

  3. Transducer-based evaluation of tremor.

    Science.gov (United States)

    Haubenberger, Dietrich; Abbruzzese, Giovanni; Bain, Peter G; Bajaj, Nin; Benito-León, Julián; Bhatia, Kailash P; Deuschl, Günther; Forjaz, Maria João; Hallett, Mark; Louis, Elan D; Lyons, Kelly E; Mestre, Tiago A; Raethjen, Jan; Stamelou, Maria; Tan, Eng-King; Testa, Claudia M; Elble, Rodger J

    2016-09-01

    The International Parkinson and Movement Disorder Society established a task force on tremor that reviewed the use of transducer-based measures in the quantification and characterization of tremor. Studies of accelerometry, electromyography, activity monitoring, gyroscopy, digitizing tablet-based measures, vocal acoustic analysis, and several other transducer-based methods were identified by searching PubMed.gov. The availability, use, acceptability, reliability, validity, and responsiveness were reviewed for each measure using the following criteria: (1) used in the assessment of tremor; (2) used in published studies by people other than the developers; and (3) adequate clinimetric testing. Accelerometry, gyroscopy, electromyography, and digitizing tablet-based measures fulfilled all three criteria. Compared to rating scales, transducers are far more sensitive to changes in tremor amplitude and frequency, but they do not appear to be more capable of detecting a change that exceeds random variability in tremor amplitude (minimum detectable change). The use of transducer-based measures requires careful attention to their limitations and validity in a particular clinical or research setting. © 2016 International Parkinson and Movement Disorder Society.

  4. Tectonic tremor and slow slip along the northwestern section of the Mexico subduction zone

    Science.gov (United States)

    Brudzinski, Michael R.; Schlanser, Kristen M.; Kelly, Nicholas J.; DeMets, Charles; Grand, Stephen P.; Márquez-Azúa, Bertha; Cabral-Cano, Enrique

    2016-11-01

    The southwestern coast of Mexico is marked by active subduction of the Rivera and Cocos plates, producing megathrust earthquakes that tend to recur every 50-100 yr. Herein, we use seismic and GPS data from this region to investigate the potential relationship between earthquakes, tectonic (non-volcanic) tremor, and transient slip along the westernmost 200 km of the Mexico subduction zone. Visual examination of seismograms and spectrograms throughout the 18-month-long MARS seismic experiment reveals clear evidence for frequent small episodes of tremor along the Rivera and Cocos subduction zones beneath the states of Jalisco, Colima, and Michoacán. Using a semi-automated process that identifies prominent energy bursts in envelope waveforms of this new data, analyst-refined relative arrival times are inverted for source locations using a 1-D velocity model. The resulting northwest-southeast trending linear band of tremor is located downdip from the rupture zones of the 1995 Mw 8.0 Colima-Jalisco and 2003 Mw 7.2 Tecoman subduction-thrust earthquakes and just below the regions of afterslip triggered by these earthquakes. Despite the close proximity between tremor and megathrust events, there is no evidence that the time since the last great earthquake influences the spatial or temporal pattern of tremor. A well-defined gap in the tremor beneath the western Colima Graben appears to mark a separation along the subducted Rivera-Cocos plate boundary. From the position time series of 19 continuous GPS sites in western Mexico, we present the first evidence that slow slip events occur on the Rivera plate subduction interface. Unlike the widely-recorded, large-amplitude, slow slip events on the nearly horizontal Cocos plate subduction interface below southern Mexico, slow slip events below western Mexico have small amplitudes and are recorded at relatively few, mostly coastal stations. The smaller slow slip beneath western Mexico may be due to the steeper dip, causing a

  5. Automated detection and characterization of harmonic tremor in continuous seismic data

    Science.gov (United States)

    Roman, Diana C.

    2017-06-01

    Harmonic tremor is a common feature of volcanic, hydrothermal, and ice sheet seismicity and is thus an important proxy for monitoring changes in these systems. However, no automated methods for detecting harmonic tremor currently exist. Because harmonic tremor shares characteristics with speech and music, digital signal processing techniques for analyzing these signals can be adapted. I develop a novel pitch-detection-based algorithm to automatically identify occurrences of harmonic tremor and characterize their frequency content. The algorithm is applied to seismic data from Popocatepetl Volcano, Mexico, and benchmarked against a monthlong manually detected catalog of harmonic tremor events. During a period of heightened eruptive activity from December 2014 to May 2015, the algorithm detects 1465 min of harmonic tremor, which generally precede periods of heightened explosive activity. These results demonstrate the algorithm's ability to accurately characterize harmonic tremor while highlighting the need for additional work to understand its causes and implications at restless volcanoes.

  6. Motor imagery evokes increased somatosensory activity in Parkinson's disease patients with tremor.

    Science.gov (United States)

    Helmich, Rick C; Bloem, Bastiaan R; Toni, Ivan

    2012-08-01

    Parkinson's disease (PD) is surprisingly heterogeneous: some patients have a prominent resting tremor, while others never develop this symptom. Here we investigate whether the functional organization of the voluntary motor system differs between PD patients with and without resting tremor, and whether these differences relate to the cerebral circuit producing tremor. We compared 18 PD patients with marked tremor, 20 PD patients without tremor, and 19 healthy controls. Subjects performed a controlled motor imagery task during fMRI scanning. We quantified imagery-related cerebral activity by contrasting imagery of biomechanically difficult and easy movements. Tremor-related activity was identified by relating cerebral activity to fluctuations in tremor amplitude, using electromyography during scanning. PD patients with tremor had better behavioral performance than PD patients without tremor. Furthermore, tremulous PD patients showed increased imagery-related activity in somatosensory area 3a, as compared with both healthy controls and to nontremor PD patients. This effect was independent from tremor-related activity, which was localized to the motor cortex, cerebellum, and thalamic ventral intermediate nucleus (VIM). The VIM, with known projections to area 3a, was unique in showing both tremor- and imagery-related responses. We conclude that parkinsonian tremor influences motor imagery by modulating central somatosensory processing through the VIM. This mechanism may explain clinical differences between PD patients with and without tremor.

  7. Genetics Home Reference: essential tremor

    Science.gov (United States)

    ... tremor that results from other disorders or known causes, such as Parkinson disease or head trauma. Essential tremor usually occurs ... tremor occurs. Severe cases are often misdiagnosed as Parkinson disease . Related Information What information ... causes of essential tremor are unknown. Researchers are studying ...

  8. Essential Tremor Is More Than a Tremor

    Medline Plus

    Full Text Available ... 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 on Google+ (Opens in new window) Click to email this to a friend (Opens in new window) Click to print (Opens ...

  9. Arm tremor and precision of hand force control in a short and long term flight on the Mir-Space-Station

    Science.gov (United States)

    Gallasch, E.; Kozlovskaya, I.; Löscher, W. N.; Konev, A.; Kenner, T.

    To determine whether long and short time exposure of man in 0g alters normal physiological tremor patterns we recorded arm tremor using an accelerometer as well as hand forces and tremor during constant isometric contraction using a load cell. Arm tremor was decreased during both flights in amplitude and frequency. Shortly after the long term flight arm tremor amplitude was increased, indicating adaptive changes in the tonic reflex loop. Isometric hand tremor remained unchanged during the long and short time flight demonstrating that the contractile properties of hand muscles remained constant. Precision of hand force was decreased until the half duration of the long term flight.

  10. Dome/Conduit inflation-deflation at Volcan de Fuego, Colima: evidence from seismic and geodetic data

    Science.gov (United States)

    Arciniega-Ceballos, A.; Cabral-Cano, E.; Castaneda, E.; Salazar-Tlaczani, L.; DeMets, C.; Marquez-Azua, B.

    2013-12-01

    Volcan de Fuego is a strato-volcano (3860 m high) in Colima Mexico, which has been presenting high explosive activity from small to large explosive events, occasionally accompanied by pyroclastic flows, periodic dome growth and destructive phases, intense fumarole activity and degassing, during the last decade. Since June 2011 a broadband seismic and geodetic network has been operating at radial distances ranging between 1.5 and 4 km from the crater. Five stations are equipped with a Nanometrics 120 s Trillium seismometer and Trimble NetR9 GPS receiver, from which three of them include a MiniDOAS gas detection system. During the period of study eruptive activity of Volcan de Fuego has been dominated by dome growth, degassing and occasional large explosions. These events are associated with the partial dome destruction and frequent ash emissions. Preliminary analyses of two-year continuous records of broadband seismic and geodesy data have revealed dome/conduit inflation-deflation phases related to conspicuous VLP tremor in the 1-20 s period band. VLP tremor has been detected in several periods since 2011 in all stations of the network. VLP tremor may be spasmodic or a persistent signal that fluctuates both in amplitude and time. Since in volcanic areas microseismicity may cover a period range of 5 to 20 s, we analyze and characterize the noise levels considering the relative amplitude with respect to the average amplitude of microseismic noise at each station. We evaluate temporal and frequency variations of volcanic activity with respect the microseismic levels. Our results indicate that the energy of the wave field in the 1-20 s period band is dominated by volcanic activity, especially in cases associated with large eruptive events. The presence of VLP tremor correlates well with inflation-deflation phases observed in the GPS time series, with total vertical displacements of 20-40 mm. This behavior is most evident in the COPN, COPE and COLW stations, which are

  11. Tremor - self-care

    Science.gov (United States)

    ... your provider about how you can change your sleep 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 ...

  12. Hypothetical membrane mechanisms in essential tremor

    Directory of Open Access Journals (Sweden)

    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

  13. Searching for Tectonic Tremor on the North Anatolian Fault

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    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.

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

    Science.gov (United States)

    Trenado, Carlos; Amtage, Florian; Huethe, Frank; Schulte-Mönting, Jürgen; Mendez-Balbuena, Ignacio; Baker, Stuart N; Baker, Mark; Hepp-Reymond, Marie-Claude; Manjarrez, Elias; Kristeva, Rumyana

    2014-01-01

    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. One central oscillatory drive is compatible with experimental motor unit behaviour in essential and Parkinsonian tremor

    Science.gov (United States)

    Dideriksen, Jakob L.; Gallego, Juan A.; Holobar, Ales; Rocon, Eduardo; Pons, Jose L.; Farina, Dario

    2015-08-01

    Objective. Pathological tremors are symptomatic to several neurological disorders that are difficult to differentiate and the way by which central oscillatory networks entrain tremorogenic contractions is unknown. We considered the alternative hypotheses that tremor arises from one oscillator (at the tremor frequency) or, as suggested by recent findings from the superimposition of two separate inputs (at the tremor frequency and twice that frequency). Approach. Assuming one central oscillatory network we estimated analytically the relative amplitude of the harmonics of the tremor frequency in the motor neuron output for different temporal behaviors of the oscillator. Next, we analyzed the bias in the relative harmonics amplitude introduced by superimposing oscillations at twice the tremor frequency. These findings were validated using experimental measurements of wrist angular velocity and surface electromyography (EMG) from 22 patients (11 essential tremor, 11 Parkinson’s disease). The ensemble motor unit action potential trains identified from the EMG represented the neural drive to the muscles. Main results. The analytical results showed that the relative power of the tremor harmonics in the analytical models of the neural drive was determined by the variability and duration of the tremor bursts and the presence of the second oscillator biased this power towards higher values. The experimental findings accurately matched the analytical model assuming one oscillator, indicating a negligible functional role of secondary oscillatory inputs. Furthermore, a significant difference in the relative power of harmonics in the neural drive was found across the patient groups, suggesting a diagnostic value of this measure (classification accuracy: 86%). This diagnostic power decreased substantially when estimated from limb acceleration or the EMG. Signficance. The results indicate that the neural drive in pathological tremor is compatible with one central network

  17. Collateral variations between the concentrations of mercury and other water soluble ions in volcanic ash samples and volcanic activity during the 2014-2016 eruptive episodes at Aso volcano, Japan

    Science.gov (United States)

    Marumoto, Kohji; Sudo, Yasuaki; Nagamatsu, Yoshizumi

    2017-07-01

    During 2014-2016, the Aso volcano, located in the center of the Kyushu Islands, Japan, erupted and emitted large amounts of volcanic gases and ash. Two episodes of the eruption were observed; firstly Strombolian magmatic eruptive episodes from 25 November 2014 to the middle of May 2015, and secondly phreatomagmatic and phreatic eruptive episodes from September 2015 to February 2016. Bulk chemical analyses on total mercury (Hg) and major ions in water soluble fraction in volcanic ash fall samples were conducted. During the Strombolian magmatic eruptive episodes, total Hg concentrations averaged 1.69 ± 0.87 ng g- 1 (N = 33), with a range from 0.47 to 3.8 ng g- 1. In addition, the temporal variation of total Hg concentrations in volcanic ash varied with the amplitude change of seismic signals. In the Aso volcano, the volcanic tremors are always observed during eruptive stages and quiet interludes, and the amplitudes of tremors increase at eruptive stages. So, the temporal variation of total Hg concentrations could provide an indication of the level of volcanic activity. During the phreatomagmatic and phreatic eruptive episodes, on the other hand, total Hg concentrations in the volcanic ash fall samples averaged 220 ± 88 ng g- 1 (N = 5), corresponding to 100 times higher than those during the Strombolian eruptive episode. Therefore, it is possible that total Hg concentrations in volcanic ash samples are largely varied depending on the eruptive type. In addition, the ash fall amounts were also largely different among the two eruptive episodes. This can be also one of the factors controlling Hg concentrations in volcanic ash.

  18. 19th-century American contributions to the recording of tremors.

    Science.gov (United States)

    Lanska, D J

    2000-07-01

    Studies of tremor in the 19th century were based initially on simple observation and later on the use of crude graphic recording devices that had been modified from instruments developed for other purposes. Like several European contemporaries, American investigators studying tremor used and adapted various existing instruments, including tambours and sphygmographs. A tambour used a drum-shaped pneumatic mechanism to transmit movements to a recording instrument, whereas the sphygmograph was a nonpneumatic mechanical device initially used to record the pulse. 19th-century American neurologists who used such devices included Frederick Peterson, Hobart Amory Hare, Charles Loomis Dana, and Augustus A. Eshner. Their measurements of tremor frequency were generally consistent with modern estimates for various types of tremor. Eshner, in particular, was frustrated by the overlap of frequency domains for tremors in different diseases, because this precluded use of tremor frequency alone as a differentiating feature for diagnosis. Peterson and Dana recognized the variation in tremor frequency in different body parts resulting from different natural resonance frequencies of these parts as a function of weight and elastic properties. Peterson, Dana, and Eshner also recognized that tremor amplitude and frequency are inversely related. Finally, these 19th-century investigators recognized that the tremor of Parkinson's disease is a relatively low-frequency rest tremor, suppressed by action, and generally synchronous in symmetric body parts, but varying in amplitude and frequency in different body parts or over time.

  19. The pathophysiology of essential tremor and Parkinson's tremor

    NARCIS (Netherlands)

    Helmich, R.C.G.; Toni, I.; Deuschl, G.; Bloem, B.R.

    2013-01-01

    We review recent evidence about the pathophysiology of essential tremor and tremor in Parkinson's disease. We believe that a network perspective is necessary to understand this common neurological symptom, and that knowledge of cerebral network dysfunction in tremor disorders will help to develop ne

  20. The Pathophysiology of Essential Tremor and Parkinson's Tremor

    NARCIS (Netherlands)

    Helmich, R.C.G.; Toni, I.; Deuschl, G.; Bloem, B.R.

    2013-01-01

    We review recent evidence about the pathophysiology of essential tremor and tremor in Parkinson's disease. We believe that a network perspective is necessary to understand this common neurological symptom, and that knowledge of cerebral network dysfunction in tremor disorders will help to develop ne

  1. Evaluating machine learning algorithms estimating tremor severity ratings on the Bain-Findley scale

    Science.gov (United States)

    Yohanandan, Shivanthan A. C.; Jones, Mary; Peppard, Richard; Tan, Joy L.; McDermott, Hugh J.; Perera, Thushara

    2016-12-01

    Tremor is a debilitating symptom of some movement disorders. Effective treatment, such as deep brain stimulation (DBS), is contingent upon frequent clinical assessments using instruments such as the Bain-Findley tremor rating scale (BTRS). Many patients, however, do not have access to frequent clinical assessments. Wearable devices have been developed to provide patients with access to frequent objective assessments outside the clinic via telemedicine. Nevertheless, the information they report is not in the form of BTRS ratings. One way to transform this information into BTRS ratings is through linear regression models (LRMs). Another, potentially more accurate method is through machine learning classifiers (MLCs). This study aims to compare MLCs and LRMs, and identify the most accurate model that can transform objective tremor information into tremor severity ratings on the BTRS. Nine participants with upper limb tremor had their DBS stimulation amplitude varied while they performed clinical upper-extremity exercises. Tremor features were acquired using the tremor biomechanics analysis laboratory (TREMBAL). Movement disorder specialists rated tremor severity on the BTRS from video recordings. Seven MLCs and 6 LRMs transformed TREMBAL features into tremor severity ratings on the BTRS using the specialists’ ratings as training data. The weighted Cohen’s kappa ({κ\\text{w}} ) defined the models’ rating accuracy. This study shows that the Random Forest MLC was the most accurate model ({κ\\text{w}}   =  0.81) at transforming tremor information into BTRS ratings, thereby improving the clinical interpretation of tremor information obtained from wearable devices.

  2. Contribution of inter-muscular synchronization in the modulation of tremor intensity in Parkinson's disease.

    Science.gov (United States)

    He, Xin; Hao, Man-Zhao; Wei, Ming; Xiao, Qin; Lan, Ning

    2015-12-01

    Involuntary central oscillations at single and double tremor frequencies drive the peripheral neuromechanical system of muscles and joints to cause tremor in Parkinson's disease (PD). The central signal of double tremor frequency was found to correlate more directly to individual muscle EMGs (Timmermann et al. 2003). This study is aimed at investigating what central components of oscillation contribute to inter-muscular synchronization in a group of upper extremity muscles during tremor in PD patients. 11 idiopathic, tremor dominant PD subjects participated in this study. Joint kinematics during tremor in the upper extremity was recorded along with EMGs of six upper arm muscles using a novel experimental apparatus. The apparatus provided support for the upper extremity on a horizontal surface with reduced friction, so that resting tremor in the arm can be recorded with a MotionMonitor II system. In each subject, the frequencies of rhythmic firings in upper arm muscles were determined using spectral analysis. Paired and pool-averaged coherence analyses of EMGs for the group of muscles were performed to correlate the level of inter-muscular synchronization to tremor amplitudes at shoulder and elbow. The phase shift between synchronized antagonistic muscle pairs was calculated to aid coherence analysis in the muscle pool. Recorded EMG revealed that rhythmic firings were present in most recorded muscles, which were either synchronized to form phase-locked bursting cycles at a subject specific frequency, or unsynchronized with a random phase distribution. Paired coherence showed a stronger synchronization among a subset of recorded arm muscles at tremor frequency than that at double tremor frequency. Furthermore, the number of synchronized muscles in the arm was positively correlated to tremor amplitudes at elbow and shoulder. Pool-averaged coherence at tremor frequency also showed a better correlation with the amplitude of resting tremor than that of double tremor

  3. Tremor in multiple sclerosis

    NARCIS (Netherlands)

    Koch, Marcus; Mostert, Jop; Heersema, Dorothea; De Keyser, Jacques

    2007-01-01

    Tremor is estimated to occur in about 25 to 60 percent of patients with multiple sclerosis (MS). This symptom, which can be severely disabling and embarrassing for patients, is difficult to manage. Isoniazid in high doses, carbamazepine, propranolol and gluthetimide have been reported to provide som

  4. Is localised dehydration and vein generation the tremor-generating mechanism in subduction zones?

    Science.gov (United States)

    Fagereng, Ake; Meneghini, Francesca; Diener, Johann; Harris, Chris

    2017-04-01

    The phenomena of tectonic, non-volcanic, tremor was first discovered at the down-dip end of the seismogenic zone in Japan early this millennium. Now this low amplitude, low frequency, noise-like seismic signal has been observed at and/or below the deep limit of interseismic coupling along most well-instrumented subduction thrust interfaces. Data and models from these examples suggest a link between tremor and areas of elevated fluid pressure, or at least fluid presence. Tremor locations appear to also correlate with margin-specific locations of metamorphic fluid release, determined by composition and thermal structure. We therefore hypothesise that: (i) tremor on the deep subduction thrust interface is related to localised fluid release; and (ii) accretionary complex rocks exhumed from appropriate pressure - temperature conditions should include a record of this process, and allow a test for the hypothesis. Hydrothermal veins are a record of mineral precipitation at non-equilibrium conditions, commonly caused by fracture, fluid influx, and precipitation of dissolved minerals from this fluid. Quartz veins are ubiquitous in several accretionary complexes, including the Chrystalls Beach Complex, New Zealand, and the Kuiseb Schist of the Namibian Damara Belt. In both locations, representing temperatures of deformation of < 300 and < 600 °C respectively, there are networks of foliation-parallel and oblique veins, which developed incrementally and record a combination of shear and dilation. Required to have formed at differential stresses less than four times the tensile strength, and at fluid pressures exceeding the least compressive stress, these veins are consistent with tremorgenic conditions of low effective stress and mixed-mode deformation kinematically in agreement with shear on the plate interface. We have analysed the oxygen isotope composition of syntectonic quartz veins in both Chrystalls Beach Complex and Kuiseb Schist accretionary complexes, to unravel the

  5. How typical are 'typical' tremor characteristics? : Sensitivity and specificity of five tremor phenomena

    NARCIS (Netherlands)

    van der Stouwe, A. M. M.; Elting, J. W.; van der Hoeven, J. H.; van Laar, T.; Leenders, K. L.; Maurits, N. M.; Tijssen, M. Aj.

    2016-01-01

    Introduction: Distinguishing between different tremor disorders can be challenging. Some tremor disorders are thought to have typical tremor characteristics: the current study aims to provide sensitivity and specificity for five 'typical' tremor phenomena. Methods: Retrospectively, we examined 210 t

  6. The pathophysiology of essential tremor and Parkinson's tremor.

    Science.gov (United States)

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

    2013-09-01

    We review recent evidence about the pathophysiology of essential tremor and tremor in Parkinson's disease. We believe that a network perspective is necessary to understand this common neurological symptom, and that knowledge of cerebral network dysfunction in tremor disorders will help to develop new therapies. Both essential tremor and Parkinson's tremor are associated with increased activity in the cerebellothalamocortical circuit. However, different pathophysiological mechanisms lead to tremulous activity within this circuit. In Parkinson's disease, evidence suggests that dopaminergic dysfunction of the pallidum triggers increased activity in the cerebellothalamocortical circuit. In essential tremor, GABAergic dysfunction of the cerebellar dentate nucleus and brain stem, possibly caused by neurodegeneration in these regions, may lead to tremulous activity within the cerebellothalamocortical circuit. In both disorders, network parameters such as the strength and directionality of interregional coupling are crucially altered. Exciting new research uses these network parameters to develop network-based therapies, such as closed-loop deep brain stimulation and transcranial magnetic or direct current stimulation.

  7. Episodic tremor triggers small earthquakes

    Science.gov (United States)

    Balcerak, Ernie

    2011-08-01

    It has been suggested that episodic tremor and slip (ETS), the weak shaking not associated with measurable earthquakes, could trigger nearby earthquakes. However, this had not been confirmed until recently. Vidale et al. monitored seismicity in the 4-month period around a 16-day episode of episodic tremor and slip in March 2010 in the Cascadia region. They observed five small earthquakes within the subducting slab during the ETS episode. They found that the timing and locations of earthquakes near the tremor suggest that the tremor and earthquakes are related. Furthermore, they observed that the rate of earthquakes across the area was several times higher within 2 days of tremor activity than at other times, adding to evidence of a connection between tremor and earthquakes. (Geochemistry, Geophysics, Geosystems, doi:10.1029/2011GC003559, 2011)

  8. Extending Alaska's plate boundary: tectonic tremor generated by Yakutat subduction

    Science.gov (United States)

    Wech, Aaron G.

    2016-01-01

    The tectonics of the eastern end of the Alaska-Aleutian subduction zone are complicated by the inclusion of the Yakutat microplate, which is colliding into and subducting beneath continental North America at near-Pacific-plate rates. The interaction among these plates at depth is not well understood, and further east, even less is known about the plate boundary or the source of Wrangell volcanism. The drop-off in Wadati-Benioff zone (WBZ) seismicity could signal the end of the plate boundary, the start of aseismic subduction, or a tear in the downgoing plate. Further compounding the issue is the possible presence of the Wrangell slab, which is faintly outlined by an anemic, eastward-dipping WBZ beneath the Wrangell volcanoes. In this study, I performed a search for tectonic tremor to map slow, plate-boundary slip in south-central Alaska. I identified ∼11,000 tremor epicenters, which continue 85 km east of the inferred Pacific plate edge marked by WBZ seismicity. The tremor zone coincides with the edges of the downgoing Yakutat terrane, and tremors transition from periodic to continuous behavior as they near the aseismic Wrangell slab. I interpret tremor to mark slow, semicontinuous slip occurring at the interface between the Yakutat and North America plates. The slow slip region lengthens the megathrust interface beyond the WBZ and may provide evidence for a connection between the Yakutat slab and the aseismic Wrangell slab.

  9. Modeling noisy time series Physiological tremor

    CERN Document Server

    Timmer, J

    1998-01-01

    Empirical time series often contain observational noise. We investigate the effect of this noise on the estimated parameters of models fitted to the data. For data of physiological tremor, i.e. a small amplitude oscillation of the outstretched hand of healthy subjects, we compare the results for a linear model that explicitly includes additional observational noise to one that ignores this noise. We discuss problems and possible solutions for nonlinear deterministic as well as nonlinear stochastic processes. Especially we discuss the state space model applicable for modeling noisy stochastic systems and Bock's algorithm capable for modeling noisy deterministic systems.

  10. Parkinsonian tremor loses its alternating aspect during non-REM sleep and is inhibited by REM sleep.

    Science.gov (United States)

    Askenasy, J J; Yahr, M D

    1990-01-01

    Non-REM sleep transforms the waking alternating Parkinsonian tremor into subclinical repetitive muscle contractions whose amplitude and duration decrease as non-REM sleep progresses from stages I to IV. During REM sleep Parkinsonian tremor disappears while the isolated muscle events increase significantly. PMID:2246656

  11. Parkinsonian tremor loses its alternating aspect during non-REM sleep and is inhibited by REM sleep.

    OpenAIRE

    Askenasy, J. J.; Yahr, M D

    1990-01-01

    Non-REM sleep transforms the waking alternating Parkinsonian tremor into subclinical repetitive muscle contractions whose amplitude and duration decrease as non-REM sleep progresses from stages I to IV. During REM sleep Parkinsonian tremor disappears while the isolated muscle events increase significantly.

  12. Blinded placebo crossover study of gabapentin in primary orthostatic tremor.

    Science.gov (United States)

    Rodrigues, Julian P; Edwards, Dylan J; Walters, Susan E; Byrnes, Michelle L; Thickbroom, Gary W; Stell, Rick; Mastaglia, Frank L

    2006-07-01

    Primary orthostatic tremor (OT) is a rare but disabling condition characterized by leg tremor and feelings of instability during stance. Previous studies have reported a reduction in OT symptoms with gabapentin treatment. In this study, we report on the benefits of gabapentin treatment in a double-blind placebo-controlled crossover study of 6 OT patients. First, the maximally effective gabapentin dosage (600-2,700 mg/day) for each patient was determined during an initial dose-titration phase. Patients were then studied 7 days after drug withdrawal and again after two 2-week periods of treatment with either gabapentin or placebo, using force platform posturography to quantify postural sway and tremor. Other medications for OT were continued unchanged. Symptomatic response was assessed by a patient-rated severity scale and quality of life (QOL) questionnaire. All patients reported an increase in symptoms during the washout phase and symptom reduction (50%-75%) during gabapentin treatment. Tremor amplitude was reduced to 79% +/- 11% and sway area to 71% +/- 11% of the placebo state. QOL improved in all patients, no adverse drug effects were noted, and symptomatic benefit was maintained at follow-up (mean = 19 months). The findings confirm that gabapentin is an effective treatment for OT, reducing both tremor and postural instability and improving quality of life, and support its use as add-on or first-line therapy for OT.

  13. 21 CFR 882.1950 - Tremor transducer.

    Science.gov (United States)

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Tremor transducer. 882.1950 Section 882.1950 Food... DEVICES NEUROLOGICAL DEVICES Neurological Diagnostic Devices § 882.1950 Tremor transducer. (a) Identification. A tremor transducer is a device used to measure the degree of tremor caused by certain diseases...

  14. Activation and tremor of the shoulder muscles to the demands of an archery task.

    Science.gov (United States)

    Lin, Jiu-Jenq; Hung, Cheng-Ju; Yang, Ching-Ching; Chen, Hsing-Yu; Chou, Feng-Ching; Lu, Tung-Wu

    2010-02-01

    Physiological tremor and strength during the maintenance of shoulder position occur during a precision aiming task, such as archery. It is unclear how positions for precision demands affect physiological tremor and associated muscular activities. The purpose of this study was to assess the tremor amplitude and muscular activities of the shoulder between the various positions for precision demands. Ten males (age 21.9 +/- 2.0 years) participated in the study. Electromyography (EMG) was quantified on eight humeral/scapular muscles. The tremor was measured by the acceleration component of a motion tracking sensor in the 3-7 Hz and 8-12 Hz frequency bands. Participants simulated six preparatory archery shooting positions (3 arm angles x 2 arm draw positions) and performed isometric contractions. The relative root mean square (RMS) amplitudes of the shoulder muscles were significantly greater for the full drawing position compared with the partial position (humeral muscles: P = 0.011; scapular muscles: P = 0.026). In the full drawing position, increased humeral/scapular muscle EMG amplitude was moderately associated with an increased power spectrum of 8-12/3-7 Hz tremor in humerus/scapula motion (R = 0.43-0.57). To minimize fluctuations in high strength muscle performance, 90 degrees of elevation in the full drawing position may be a suitable position for demands in archery. In addition, scapular muscle amplitude is important for stability to reduce humerus tremor during archery performance.

  15. Widespread triggering of nonvolcanic tremor in California.

    Science.gov (United States)

    Gomberg, Joan; Rubinstein, Justin L; Peng, Zhigang; Creager, Kenneth C; Vidale, John E; Bodin, Paul

    2008-01-11

    We identified seven locations on or near the transform plate boundary in California where nonvolcanic tremor was triggered by the 2002 Denali earthquake. This result implies that the conditions essential for nonvolcanic tremor exist in a range of tectonic environments. Models explaining tremor typically require conditions endemic to subduction zones, that is, high temperatures and fluid pressures, because previously tremor was nearly exclusively documented in subduction zones. The absence of tremor in geothermal areas is inconsistent with such models. Additionally, we found no correlation between creeping or locked faults and tremor, contrary to predictions of frictional models of tremor.

  16. Hereditary chin tremor in Parkinson's disease.

    Science.gov (United States)

    Erer, Sevda; Jankovic, Joseph

    2007-11-01

    Hereditary chin tremor (HCT) is characterized by rhythmical, involuntary movements of the chin muscles usually inherited in an autosomal dominant pattern. We describe a 74-year old man with familial, childhood-onset chin tremor, and a 3-year history of progressive hand tremor, gait difficulty, and other parkinsonian features. Since chin tremor often occurs in Parkinson's disease (PD), a coexistent HCT may not be recognized unless past and family history of tremor is carefully explored.

  17. Tremor, the curious third wheel of fault motion (Invited)

    Science.gov (United States)

    Vidale, J. E.

    2009-12-01

    The known universe of tectonic fault behavior has gained a new neighborhood in the last few years. Before, faults were considered to either conform to the reasonably well-understood earthquake cycle or else slide steadily. In the earthquake cycle, a fault stays locked for the years while stress is accumulating, then cracks and slides, releasing about 0.1-10 MPa of the stress on the fault. The crack spreads across the fault at roughly the shear wave velocity, kilometers per second. Sliding across the crack occurs at rates on the order of a meter per second. Deeper than the locked portion, faults were assumed to move stealthily and steadily. Disrupting this orderly bipartite universe has been tremor - a prolonged, noise-like, 1-10 Hz rumbling that has been spotted below the locked portion of a variety of faults. In subduction zones, often tremor is coincident with slow and low-stress-drop slip that takes many orders of magnitude longer to complete than garden-variety earthquakes, with the rupture progression estimated in km per day rather than per second. The so-called episodic tremor and slip (ETS) is seen to strike at much more regular intervals than old-fashioned quakes. Speculation and disjoint observations abound. Probably the observations represent just the most easily observed portions of a process that moves with power at all frequencies. The spectrum of tremor radiation is less “red” than that of earthquakes for periods shorter than their duration. Near-lithostatic pore pressure may play an important role in lubricating ETS activity. ETS activity appears generally restricted to only some major faults. Strong passing surface waves from distant great earthquakes trigger pulsations of tremor. Strong nearby earthquakes can cause weeks of stronger than normal tremor. The ebb and flow of diurnal tides cause a rise and fall in tremor amplitude. Tremor can contain earthquake-like short bursts of energy, even dozens of discrete pops, all with the less red spectra

  18. Decreased Cerebellar Fiber Density in Cortical Myoclonic Tremor but Not in Essential Tremor

    NARCIS (Netherlands)

    Buijink, Arthur W. G.; Caan, Matthan W. A.; Tijssen, Marina A. J.; Hoogduin, Johannes M.; Maurits, Natasha M.; van Rootselaar, Anne-Fleur

    Pathophysiology of tremor generation remains uncertain in 'familial cortical myoclonic tremor with epilepsy' (FCMTE) and essential tremor (ET). In both disorders, imaging and pathological studies suggest involvement of the cerebellum and its projection areas. MR diffusion tensor imaging allows

  19. Decreased Cerebellar Fiber Density in Cortical Myoclonic Tremor but Not in Essential Tremor

    NARCIS (Netherlands)

    Buijink, Arthur W. G.; Caan, Matthan W. A.; Tijssen, Marina A. J.; Hoogduin, Johannes M.; Maurits, Natasha M.; van Rootselaar, Anne-Fleur

    2013-01-01

    Pathophysiology of tremor generation remains uncertain in 'familial cortical myoclonic tremor with epilepsy' (FCMTE) and essential tremor (ET). In both disorders, imaging and pathological studies suggest involvement of the cerebellum and its projection areas. MR diffusion tensor imaging allows estim

  20. Strongly gliding harmonic tremor during the 2009 eruption of Redoubt Volcano

    Science.gov (United States)

    Hotovec, Alicia J.; Prejean, Stephanie G.; Vidale, John E.; Gomberg, Joan S.

    2013-01-01

    During the 2009 eruption of Redoubt Volcano, Alaska, gliding harmonic tremor occurred prominently before six nearly consecutive explosions during the second half of the eruptive sequence. The fundamental frequency repeatedly glided upward from < 1 Hz to as high as 30 Hz in less than 10 min, followed by a relative seismic quiescence of 10 to 60 s immediately prior to explosion. High frequency (5 to 20 Hz) gliding returned during the extrusive phase, and lasted for 20 min to 3 h at a time. Although harmonic tremor is not uncommon at volcanoes, tremor at such high frequencies is a rare observation. These frequencies approach or exceed the plausible upper limits of many models that have been suggested for volcanic tremor. We also analyzed the behavior of a swarm of repeating earthquakes that immediately preceded the first instance of pre-explosion gliding harmonic tremor. We find that these earthquakes share several traits with upward gliding harmonic tremor, and favor the explanation that the gliding harmonic tremor at Redoubt Volcano is created by the superposition of increasingly frequent and regular, repeating stick–slip earthquakes through the Dirac comb effect.

  1. Movement-related dynamics of cortical oscillations in Parkinson's disease and essential tremor.

    Science.gov (United States)

    Kondylis, Efstathios D; Randazzo, Michael J; Alhourani, Ahmad; Lipski, Witold J; Wozny, Thomas A; Pandya, Yash; Ghuman, Avniel S; Turner, Robert S; Crammond, Donald J; Richardson, R M

    2016-08-01

    Recent electrocorticography data have demonstrated excessive coupling of beta-phase to gamma-amplitude in primary motor cortex and that deep brain stimulation facilitates motor improvement by decreasing baseline phase-amplitude coupling. However, both the dynamic modulation of phase-amplitude coupling during movement and the general cortical neurophysiology of other movement disorders, such as essential tremor, are relatively unexplored. To clarify the relationship of these interactions in cortical oscillatory activity to movement and disease state, we recorded local field potentials from hand sensorimotor cortex using subdural electrocorticography during a visually cued, incentivized handgrip task in subjects with Parkinson's disease (n = 11), with essential tremor (n = 9) and without a movement disorder (n = 6). We demonstrate that abnormal coupling of the phase of low frequency oscillations to the amplitude of gamma oscillations is not specific to Parkinson's disease, but also occurs in essential tremor, most prominently for the coupling of alpha to gamma oscillations. Movement kinematics were not significantly different between these groups, allowing us to show for the first time that robust alpha and beta desynchronization is a shared feature of sensorimotor cortical activity in Parkinson's disease and essential tremor, with the greatest high-beta desynchronization occurring in Parkinson's disease and the greatest alpha desynchronization occurring in essential tremor. We also show that the spatial extent of cortical phase-amplitude decoupling during movement is much greater in subjects with Parkinson's disease and essential tremor than in subjects without a movement disorder. These findings suggest that subjects with Parkinson's disease and essential tremor can produce movements that are kinematically similar to those of subjects without a movement disorder by reducing excess sensorimotor cortical phase-amplitude coupling that is characteristic of these

  2. Essential Tremor (ET): Surgical Options

    Science.gov (United States)

    ... t respond to propranolol, primidone, or other common ET medications and whose tremor has become debilitating, there ... treatments were first introduced. Current surgical options for ET include Deep Brain Stimulation (DBS) , Focused Ultrasound Thalamotomy , ...

  3. Essential tremor responsive to levetiracetam

    Directory of Open Access Journals (Sweden)

    Abdullah Yılgör

    2012-03-01

    Full Text Available Essential tremor is one of the most common movementdisorders with a prevalence of 0.4% to 3.9% in the generalpopulation and increases with age. The medical treatmentavailable for patients with essential tremor is ofteninadequate. Propranolol and primidone are the first-linetreatment options, improving in up to two thirds of cases.This article reports a satisfying response to levetiracetamwith disabling essential tremor in a 58-year-old man whompropranolol as well as primidone had to be discontinueddue to unresponsiveness and severe side effects. One ofthe antiepileptic drugs, levetiracetam, may be more usefulin the treatment of essential tremor. J Clin Exp Invest2012; 3(1: 108-110

  4. Tidal modulation of nonvolcanic tremor.

    Science.gov (United States)

    Rubinstein, Justin L; La Rocca, Mario; Vidale, John E; Creager, Kenneth C; Wech, Aaron G

    2008-01-11

    Episodes of nonvolcanic tremor and accompanying slow slip recently have been observed in the subduction zones of Japan and Cascadia. In Cascadia, such episodes typically last a few weeks and differ from "normal" earthquakes in their source location and moment-duration scaling. The three most recent episodes in the Puget Sound/southern Vancouver Island portion of the Cascadia subduction zone were exceptionally well recorded. In each episode, we saw clear pulsing of tremor activity with periods of 12.4 and 24 to 25 hours, the same as the principal lunar and lunisolar tides. This indicates that the small stresses associated with the solid-earth and ocean tides influence the genesis of tremor much more effectively than they do the genesis of normal earthquakes. Because the lithostatic stresses are 10(5) times larger than those associated with the tides, we argue that tremor occurs on very weak faults.

  5. Tidal sensitivity of tectonic tremors in Nankai and Cascadia subduction zones

    Science.gov (United States)

    Yabe, Suguru; Tanaka, Yoshiyuki; Houston, Heidi; Ide, Satoshi

    2015-11-01

    Tectonic tremors in subduction zones, which result from slip at the deep plate interface, are known to exhibit a 12.4 h periodicity in their activity, due to tidal influence. Because tidal stress can be calculated quantitatively, the response of the plate interface can yield quantitative information about its frictional property. The relation between tremor rate and tidal stress is investigated, and an exponential relation is widely confirmed, as observed by previous studies. This study particularly focuses on spatial variations of tidal sensitivity, which are compared with spatial variations of tremor duration and amplitude. The sensitivity is quantitatively defined by the exponent of the exponential relation, which can be related to the parameter aσ, or (a - b)σ in the rate-and-state friction law, where σ is effective normal stress. On the shallower tremor zone, short-duration and large-amplitude tremors occur followed by more sensitive tremors. Meanwhile, deeper tremors with longer duration and smaller amplitude show lower sensitivity, although along-strike variation also exists. Typical and maximum sensitivities estimated here imply values for aσ or (a - b)σ of about 3 and 1 kPa, respectively. These correlations are consistent with a model in which the plate interface consists of a velocity-strengthening background with embedded velocity-weakening regions. The frictional heterogeneity may be statistically characterized by cluster size and density of the velocity-weakening regions and controls the overall slip behavior. The observed depth dependency of tremor duration, amplitude, and sensitivity implies that frictional heterogeneity is controlled by physical quantities varying with depth, such as temperature or fluid amount.

  6. Detecting tectonic tremor through frequency scanning at a single station: Application to the Cascadia margin

    Science.gov (United States)

    Sit, Stefany; Brudzinski, Michael; Kao, Honn

    2012-11-01

    The discovery of episodic tremor and slip (ETS) spurred increased instrumentation and investigation of the Cascadia margin, which is now typified by the seismic phenomena. We utilize established detection and location techniques already present in the region to guide the development of a new single station detection method. While detailed network-wide investigations have led to exciting discoveries on the source location and migration patterns of tectonic tremor, single station detection has the ability to expand our search for tremor to more subduction zones and tectonic settings where instrumentation is not widely available. Our frequency scanning technique bandpass filters seismic data into three categories, 2-5 Hz, 10-15 Hz, and 0.02-0.1 Hz, where we expect prominent signals produced by tectonic tremor, local earthquakes, and surface waves, respectively. We combine amplitudes in each category into a ratio to determine tremor detection for a given hour. Results from our technique are evaluated in two ways: 1) combined in a network setting to compare with prominent location and detection methods and 2) assessed at an individual station and compared with other techniques that are capable of single station tremor detection. Network-wide processing over a two-year time period in both northern and southern Cascadia reveals common identification of larger ETS episodes when comparing our technique to both envelope waveform and combined single station detection methods. We find slight variations in the total duration of tremor and the onset timing between the different techniques, which may be due to the varying stations included in each technique. Frequency scanning identifies more inter-ETS episodes than envelope waveform and single station methods, particularly in the more sparsely instrumented region of southern Oregon. Our method also reduces erroneous signals more commonly found in other single station methods, discerned through comparison of nearby seismograms

  7. Slip rate and tremor genesis in Cascadia

    Science.gov (United States)

    Wech, Aaron G.; Bartlow, Noel M.

    2014-01-01

    At many plate boundaries, conditions in the transition zone between seismogenic and stable slip produce slow earthquakes. In the Cascadia subduction zone, these events are consistently observed as slow, aseismic slip on the plate interface accompanied by persistent tectonic tremor. However, not all slow slip at other plate boundaries coincides spatially and temporally with tremor, leaving the physics of tremor genesis poorly understood. Here we analyze seismic, geodetic, and strainmeter data in Cascadia to observe for the first time a large, tremor-generating slow earthquake change from tremor-genic to silent and back again. The tremor falls silent at reduced slip speeds when the migrating slip front pauses as it loads the stronger adjacent fault segment to failure. The finding suggests that rheology and slip-speed-regulated stressing rate control tremor genesis, and the same section of fault can slip both with and without detectable tremor, limiting tremor's use as a proxy for slip.

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

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    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.

  9. Seismic tremor signals from Bárðarbunga, Grímsvötn and other glacier covered volcanoes in Iceland's Vatnajökull ice cap

    Science.gov (United States)

    Vogfjörd, Kristin S.; Eibl, Eva; Bean, Chris; Roberts, Matthew; Ófeigsson, Benedikt; Jóhannesson, Tómas

    2016-04-01

    Many of Iceland's most active volcanoes, like Grímsvötn and Bárðarbunga are located under glaciers giving rise to a range of volcanic hazards having both local and cross-border effects on humans, infrastructures and aviation. Volcanic eruptions under ice can lead to explosive hydromagmatic volcanism and generate small to catastrophic subglacial floods that may take hours to days to emerge from the glacier edge. Unrest in subglacial hydrothermal systems and the draining of subglacial meltwater can also lead to flood hazards. These processes and magma-ice interactions in general, generate seismic tremor signals that are commonly observed on seismic systems during volcanic unrest and/or eruptions. The tremor signals exhibit certain characteristics in frequency content, amplitude and behavior with time, but their characteristics overlap. Ability to discriminate between the different processes in real-time or near-real time can support early eruption and flood warnings and help mitigate their detrimental effects. One of the goals set forth in the FUTUREVOLC volcano supersite project was in fact to understand and discriminate between the different types of seismic tremor recorded at subglacial volcanoes. In that pursuit, the seismic network was expanded into the Vatnajökull glacier with four permanent stations on rock and in the ice, in addition to three seismic arrays installed at the ice margin, to enable location and possible tracking of the tremor sources. To track subglacial floods with better resolution three GPS receivers were also installed on the ice, one in an ice cauldron above the Skaftárkatlar geothermal melting area and two down glacier, above the track of the expected subglacial flood. During FUTUREVOLC this infrastructure has recorded all the types of process expected: Magmatic dyke intrusion and propagation from Bárðarbunga, subaerial fissure eruption of that magma at Holuhraun, two subglacial floods, one small and one large, draining from the

  10. Quantification of high pressure nervous syndrome (HPNS) tremor in the guinea pig.

    Science.gov (United States)

    Gruenau, S P; Ackermann, M J

    1978-03-01

    Previous studies have demonstrated two tremorgenic systems that involve separate brain mechanisms and exhibit different peak frequencies. One system (the thalamo-cortical) generates low frequency (4--8 Hz) tremor; the other (the olivo-cerebellar) produces high frequency (10--18 Hz) tremor. Based on this evidence, the present study focused on determining whether one or both of these tremor systems is involved in the high pressure nervous syndrome (HPNS). Specifically, the concern was to identify and to quantify amplitude and frequency characteristics of HPNS tremor in 8 guinea pigs breathing helium-oxygen during compression (40 ft/min) in a chamber dive to 61.6 ATA (2000 fsw) with a bottom time of 1 h. Rectal temperature was recorded and maintained at 39 degrees C +/- 1 degree. Leg tremor was recorded by magnetic inductance and stored on magnetic tape for power spectral analysis. Frequency histograms of the tremor data revealed development of a biphasic response. From surface to about 31.3 ATA (1000 fsw), a low-power, single, 4- to 6-Hz component was evident, which resembled fine or moderate tremor. Between 34.3 ATA (1100 fsw) and 61.6 ATA, a 12- to 18-Hz component emerged abruptly with a dramatic increase in power, which reflected coarse, uncontrollable tremors. In the first 5 to 10 min after the animals arrived at maximum pressure, relative power of the high frequency component dropped to and remained near base-line levels. These results support the hypothesis that HPNS tremor consists of two components and possibly two separate tremor systems.

  11. Changes of Physiological Tremor Following Maximum Intensity Exercise in Male and Female Young Swimmers

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    Gajewski Jan

    2015-12-01

    Full Text Available Purpose. The aim of this study was to determine the changes in postural physiological tremor following maximum intensity effort performed on arm ergometer by young male and female swimmers. Methods. Ten female and nine male young swimmers served as subjects in the study. Forearm tremor was measured accelerometrically in the sitting position before the 30-second Wingate Anaerobic Test on arm ergometer and then 5, 15 and 30 minutes post-test. Results. Low-frequency tremor log-amplitude (L1−5 increased (repeated factor: p < 0.05 from −7.92 ± 0.45 to −7.44 ± 0.45 and from −6.81 ± 0.52 to −6.35 ± 0.58 in women and men, respectively (gender: p < 0.05 5 minute post-test. Tremor log-amplitude (L15−20 increased (repeated factor: p < 0.001 from −9.26 ± 0.70 to −8.59 ± 0.61 and from −8.79 ± 0.65 to −8.39 ± 0.79 in women and men, respectively 5 minute post-test. No effect of gender was found for high frequency range.The increased tremor amplitude was observed even 30 minute post-exercise. Mean frequency of tremor spectra gradually decreased post-exercises (p < 0.001. Conclusions. Exercise-induced changes in tremor were similar in males and females. A fatigue produced a decrement in the mean frequency of tremor what suggested decreased muscle stiffness post-exercise. Such changes intremorafter exercise may be used as the indicator of fatigue in the nervous system.

  12. Changes in physiological tremor associated with an epileptic seizure: a case report

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    Duval Christian

    2011-09-01

    Full Text Available Abstract Introduction Epileptic seizures are associated with motor, sensory, somatosensory or autonomic symptoms that have all been described in varying detail over the years. Of interest in the present report is a case of normal physiological tremor, which to date has never been evaluated prior to and during an epileptic seizure. In fact, there is only anecdotal mention of pre-ictal and ictal changes in clinically noticeable tremor in the literature. Case presentation Our patient was a left-handed, 27-year-old Caucasian woman diagnosed seven years previously with partial epileptic seizures, secondarily generalized. Physiological tremor was measured simultaneously on the index finger of both hands of our patient. Electromyography as well as heart rate and respiration were also monitored. A previously performed electroencephalography examination revealed abnormal oscillations focalized to the left primary somatosensory cortex. She was also diagnosed with left frontal neuronal heterotopias. We detected subclinical changes in tremor characteristics, such as amplitude, median power frequency and power dispersion, contralateral to the localization of epileptic activity. Tremor characteristics remained relatively steady ipsilateral to the localization of the epileptic activity. Conclusions Changes in physiological tremor characteristics should be considered as another possible pre-ictal or ictal manifestation. We propose that the network associated with physiological tremor might be more sensitive to abnormal oscillations generated within the central nervous system by epileptic activity from certain structures.

  13. Tremors along the Queen Charlotte Margin triggered by large teleseismic earthquakes

    Science.gov (United States)

    Aiken, Chastity; Peng, Zhigang; Chao, Kevin

    2013-03-01

    We conduct a systematic search of tectonic tremors along the Queen Charlotte Margin (QCM) in western Canada triggered by distant earthquakes. We identify triggered tremor as non-impulsive, high-frequency signals coherent among several stations and coincident with passing surface waves. So far, the 2002 Mw7.9 Denali Fault, the 2004 Mw9.2 Sumatra, and the 2011 Mw9.1 Tohoku-Oki earthquakes have triggered clear tremor in this region. The 2010 Mw8.8 Maule, Chile and the 2012 Mw8.6 Sumatra earthquakes may have triggered, but tremors in these two cases did not meet all of our criteria. The triggered tremors are mostly located east of the Queen Charlotte Fault in the southern portion of Haida Gwaii, near the epicenter of the 28 October 2012 Mw7.7 earthquake. Similar to the observations in other regions, the triggered tremors were initiated by the Love waves and continued during the subsequent Rayleigh waves. Tremor bursts correlate with both the particle velocity and displacement of the Love waves, indicating they are triggered at either low-angle thrust or vertical strike-slip faults. In addition, we find that the triggering potential for the QCM is controlled by a combination of amplitude, period, and incident angles.

  14. Holmes' tremor caused by midbrain cavernoma

    Institute of Scientific and Technical Information of China (English)

    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.

  15. Tremor UPDRS estimation in home environment.

    Science.gov (United States)

    Rigas, George; Gatsios, Dimitris; Fotiadis, Dimitrios I; Chondrogiorgi, Maria; Tsironis, Christos; Konitsiotis, Spyridon; Gentile, Giovanni; Marcante, Andrea; Antonini, Angelo

    2016-08-01

    In this paper, a method for the assessment of the Unified Parkinson Disease Rating scale (UPDRS) related to tremor is presented. The method described consists of hand resting and posture state detection, tremor detection and tremor quantification based on accelerometer and gyroscope readings from a wrist worn sensor. The initial results on PD patient recordings on home environment indicate the feasibility of the proposed method in monitoring UPDRS tremor in patient home environment.

  16. The Clinical Evaluation of Parkinson's Tremor

    NARCIS (Netherlands)

    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

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

    Science.gov (United States)

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

    2006-09-01

    Typical records of volcanic tremor and explosion quakes at Arenal volcano are analyzed with a high-resolution time-frequency method. The main characteristics of these seismic signals are: (1) numerous regularly spaced spectral peaks including both odd and even overtones; (2) frequency gliding in the range [0.9-2] Hz of the fundamental peak; (3) frequency jumps with either positive or negative increments; (4) tremor episodes with two simultaneous systems of spectral peaks affected by independent frequency gliding; (5) progressive transitions between spasmodic tremor and harmonic tremor; (6) lack of clear and systematic relationship between the occurrence of explosions and tremor. Some examples of alternation between two states of oscillation characterized by different fundamental frequencies are also observed. Some tremor and explosion codas are characterized by acoustic and seismic waves with identical spectral content and frequency gliding, which suggests a common excitation process. We propose a source model for the tremor at Arenal in which intermittent gas flow through fractures produces repetitive pressure pulses. The repeating period of the pulses is stabilized by a feedback mechanism associated with standing or traveling waves in the magmatic conduit. The pressure pulses generate acoustic waves in the atmosphere and act as excitation of the interface waves in the conduit. When the repeating period of the pulses is stable enough, they produce regularly spaced spectral peaks by the Dirac comb effect and hence harmonic tremor. When the period stability is lost, because of failures in the feedback mechanism, the tremor becomes spasmodic. The proposed source model of tremor is similar to the sound emission process of a clarinet. Fractures in the solid or viscous layer capping the lava pool in the crater act as the clarinet reed, and the conduit filled with low velocity bubbly magma is equivalent to the pipe of the musical instrument. The frequency gliding is

  18. Towards a Comprehensive Catalog of Volcanic Seismicity

    Science.gov (United States)

    Thompson, G.

    2014-12-01

    Catalogs of earthquakes located using differential travel-time techniques are a core product of volcano observatories, and while vital, they represent an incomplete perspective of volcanic seismicity. Many (often most) earthquakes are too small to locate accurately, and are omitted from available catalogs. Low frequency events, tremor and signals related to rockfalls, pyroclastic flows and lahars are not systematically catalogued, and yet from a hazard management perspective are exceedingly important. Because STA/LTA detection schemes break down in the presence of high amplitude tremor, swarms or dome collapses, catalogs may suggest low seismicity when seismicity peaks. We propose to develop a workflow and underlying software toolbox that can be applied to near-real-time and offline waveform data to produce comprehensive catalogs of volcanic seismicity. Existing tools to detect and locate phaseless signals will be adapted to fit within this framework. For this proof of concept the toolbox will be developed in MATLAB, extending the existing GISMO toolbox (an object-oriented MATLAB toolbox for seismic data analysis). Existing database schemas such as the CSS 3.0 will need to be extended to describe this wider range of volcano-seismic signals. WOVOdat may already incorporate many of the additional tables needed. Thus our framework may act as an interface between volcano observatories (or campaign-style research projects) and WOVOdat. We aim to take the further step of reducing volcano-seismic catalogs to sets of continuous metrics that are useful for recognizing data trends, and for feeding alarm systems and forecasting techniques. Previous experience has shown that frequency index, peak frequency, mean frequency, mean event rate, median event rate, and cumulative magnitude (or energy) are potentially useful metrics to generate for all catalogs at a 1-minute sample rate (directly comparable with RSAM and similar metrics derived from continuous data). Our framework

  19. Holmes’ Tremor with Shoulder Pain Treated by Deep Brain Stimulation of Unilateral Ventral Intermediate Thalamic Nucleus and Globus Pallidus Internus

    Directory of Open Access Journals (Sweden)

    Sabri Aydın

    2017-05-01

    Full Text Available A 21-year-old male was admitted with severe right arm and hand tremors after a thalamic hemorrhage caused by a traffic accident. He was also suffering from agonizing pain in his right shoulder that manifested after the tremor. Neurologic examination revealed a disabling, severe, and irregular kinetic and postural tremor in the right arm during target-directed movements. There was also an irregular ipsilateral rest tremor and dystonic movements in the distal part of the right arm. The amplitude was moderate at rest and extremely high during kinetic and intentional movements. The patient underwent left globus pallidum internus and ventral intermediate thalamic nucleus deep brain stimulation. The patient improved by more than 80% as rated by the Fahn-Tolosa-Marin Tremor Rating Scale and Visual Analog Scale six months after surgery.

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

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    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.

  1. Effects of alprazolam on cortical activity and tremors in patients with essential tremor.

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    Jaime Ibáñez

    Full Text Available BACKGROUND: Essential tremor (ET is characterised by postural and action tremors with a frequency of 4-12 Hz. Previous studies suggest that the tremor activity originates in the cerebello-thalamocortical pathways. Alprazolam is a short-acting benzodiazepine that attenuates tremors in ET. The mechanisms that mediate the therapeutic action of alprazolam are unknown; however, in healthy subjects, benzodiazepines increase cortical beta activity. In this study, we investigated the effect of alprazolam both on beta and tremor-related cortical activity and on alterations in tremor presentation in ET patients. Therefore, we characterised the dynamics of tremor and cortical activity in ET patients after alprazolam intake. METHODS: We recorded hand tremors and contralateral cortical activity in four recordings before and after a single dose of alprazolam. We then computed the changes in tremors, cortico-muscular coherence, and cortical activity at the tremor frequency and in the beta band. RESULTS: Alprazolam significantly attenuated tremors (EMG: 76.2 ± 22.68%, decreased cortical activity in the tremor frequency range and increased cortical beta activity in all patients (P<0.05. At the same time, the cortico-muscular coherence at the tremor frequency became non-significant (P<0.05. We also found a significant correlation (r = 0.757, P<0.001 between the reduction in tremor severity and the increased ratio of cortical activity in the beta band to the activity observed in the tremor frequency range. CONCLUSIONS: This study provides the first quantitative analysis of tremor reduction following alprazolam intake. We observed that the tremor severity decreased in association with an increased ratio of beta to tremor-related cortical activity. We hypothesise that the increase in cortical beta activity may act as a blocking mechanism and may dampen the pathological oscillatory activity, which in turn attenuates the observed tremor.

  2. Seismic Tremors and Three-Dimensional Magma Wagging

    Science.gov (United States)

    Liao, Y.; Bercovici, D.

    2015-12-01

    Seismic tremor is a feature shared by many silicic volcanoes and is a precursor of volcanic eruption. Many of the characteristics of tremors, including their frequency band from 0.5 Hz to 7 Hz, are common for volcanoes with very different geophysical and geochemical properties. The ubiquitous characteristics of tremor imply that it results from some generation mechanism that is common to all volcanoes, instead of being unique to each volcano. Here we present new analysis on the magma-wagging mechanism that has been proposed to generate tremor. The model is based on the suggestion given by previous work (Jellinek & Bercovici 2011; Bercovici et.al. 2013) that the magma column is surrounded by a compressible, bubble-rich foam annulus while rising inside the volcanic conduit, and that the lateral oscillation of the magma inside the annulus causes observable tremor. Unlike the previous two-dimensional wagging model where the displacement of the magma column is restricted to one vertical plane, the three-dimensional model we employ allows the magma column to bend in different directions and has angular motion as well. Our preliminary results show that, without damping from viscous deformation of the magma column, the system retains angular momentum and develops elliptical motion (i.e., the horizontal displacement traces an ellipse). In this ''inviscid'' limit, the magma column can also develop instabilities with higher frequencies than what is found in the original two-dimensional model. Lateral motion can also be out of phase for various depths in the magma column leading to a coiled wagging motion. For the viscous-magma model, we predict a similar damping rate for the uncoiled magma column as in the two-dimensional model, and faster damping for the coiled magma column. The higher damping thus requires the existence of a forcing mechanism to sustain the oscillation, for example the gas-driven Bernoulli effect proposed by Bercovici et al (2013). Finally, using our new 3

  3. Acoustic waves in the atmosphere and ground generated by volcanic activity

    Energy Technology Data Exchange (ETDEWEB)

    Ichihara, Mie; Lyons, John; Oikawa, Jun; Takeo, Minoru [Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan); Instituto Geofisico, Escuela Politecnica Nacional, Ladron de Guevara E11-253, Aptdo 2759, Quito (Ecuador); Earthquake Research Institute, University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-0032 (Japan)

    2012-09-04

    This paper reports an interesting sequence of harmonic tremor observed in the 2011 eruption of Shinmoe-dake volcano, southern Japan. The main eruptive activity started with ashcloud forming explosive eruptions, followed by lava effusion. Harmonic tremor was transmitted into the ground and observed as seismic waves at the last stage of the effusive eruption. The tremor observed at this stage had unclear and fluctuating harmonic modes. In the atmosphere, on the other hand, many impulsive acoustic waves indicating small surface explosions were observed. When the effusion stopped and the erupted lava began explosive degassing, harmonic tremor started to be transmitted also to the atmosphere and observed as acoustic waves. Then the harmonic modes became clearer and more stable. This sequence of harmonic tremor is interpreted as a process in which volcanic degassing generates an open connection between the volcanic conduit and the atmosphere. In order to test this hypothesis, a laboratory experiment was performed and the essential features were successfully reproduced.

  4. Six years of tectonic tremor observations prior to the Mw 7.4 March 20, 2012 Ometepec Earthquake

    Science.gov (United States)

    Sit, S. M.; Brudzinski, M. R.; Schlanser, K. M.; Cabral-Cano, E.; Arciniega-Ceballos, A.; DeMets, C.

    2012-12-01

    Observations of episodic tremor and slip (ETS) at several major tectonic boundaries have suggested a potential temporal relationship between the new seismic phenomena and megathrust earthquake events. The subduction zone in Oaxaca, Mexico provides an ideal locality to investigate this potential relationship, where we obtain a multi-year record of tectonic tremor detections and slow slip observations prior to the recent Mw 7.4 March 20, 2012 Ometepec earthquake. The preliminary epicenter, depth (20 km), and finite fault model all place the earthquake at the downdip edge of the band of background seismicity that is thought to outline the boundary between the seismogenic zone and transition zone of the plate interface. To detect tectonic tremor, we take advantage of its unique frequency content by scanning multiple frequency passbands where tremor (2-5 Hz), regional seismicity (10-15 Hz), and teleseismic surface waves (0.02-0.1 Hz) are present. We calculate a ratio of amplitudes favoring tremor behavior and downweighting activity from the other frequency passbands. Application of our technique allows us to quickly examine the prevalence of tremor beginning in mid-2006. Results from our frequency-based detection algorithm are in good agreement with previous tremor detections and locations in Oaxaca and additionally detects several previously unidentified low amplitude, short duration tremor episodes. Tremor occurs over a relatively short time period, 2-10 days, recurs as often as every 2-3 months, and does not regularly correlate with periods of large slow slip that tend to last several months and occur further updip. These observations are more consistent with those from Nankai than Cascadia. Preliminary analysis suggests that no obvious change in tremor prevalence occurred prior to the 2012 Ometepec earthquake; however, a variety of GPS inferred slow slip signals begin in the months leading up to the event. The puzzling relationship between tremor, slow slip, and

  5. Discrimination and characterization of Parkinsonian rest tremors by analyzing long-term correlations and multifractal signatures

    CERN Document Server

    Livi, Lorenzo

    2015-01-01

    In this paper, we analyze 48 signals of rest tremor velocity related to 12 distinct subjects affected by Parkinson's disease. The subjects belong to two different groups, formed by four and eight subjects with, respectively, high- and low-amplitude rest tremors. Each subject is tested in four settings, given by combining the use of deep brain stimulation and L-DOPA medication. We develop two main feature-based representations of such signals, which are obtained by considering (i) the long-term correlations and multifractal properties, and (ii) the power spectra. The feature-based representations are initially utilized for the purpose of characterizing the subjects under different settings. In agreement with previous studies, we show that deep brain stimulation does not significantly characterize neither of the two groups, regardless of the adopted representation. On the other hand, the medication effect yields statistically significant differences in both high- and low-amplitude tremor groups. We successively...

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

    Science.gov (United States)

    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.

  7. INFLUENCE OF VISUAL FEEDBACK ON HUMAN ISOMETRIC BITE-FORCE TREMOR

    NARCIS (Netherlands)

    BROEKHUIJSEN, ML; VANWILLIGEN, JD

    1994-01-01

    In contrast to recent reports, during an isometric short forceful bite, visual feedback had a significant influence on the force tremor spectrum. The value of a 'half-value frequency', being the frequency f1/2 at which, with increasing frequency, the amplitude of the spectrum for the first time drop

  8. INFLUENCE OF VISUAL FEEDBACK ON HUMAN ISOMETRIC BITE-FORCE TREMOR

    NARCIS (Netherlands)

    BROEKHUIJSEN, ML; VANWILLIGEN, JD

    1994-01-01

    In contrast to recent reports, during an isometric short forceful bite, visual feedback had a significant influence on the force tremor spectrum. The value of a 'half-value frequency', being the frequency f1/2 at which, with increasing frequency, the amplitude of the spectrum for the first time drop

  9. The Commercial TREMOR Strong-Motion Seismograph

    Science.gov (United States)

    Evans, J. R.; Hamstra, R. H.; Kuendig, C.; Camina, P.

    2001-12-01

    -connected cell-phone-based Internet technology (CDPD), but any RS-232 connected telemetry system is a viable candidate (spread spectrum, CDMA, GSM, POT). The instruments can be synchronized via CDPD to a few tenths of a second, or to full precision with an optional GPS receiver. Sensor RMS noise is 33 \\mathrm \\mu g over the band 0.1 to 35 Hz, 11 \\mathrm \\mu g$ over the band 0.1 to 1.0 Hz; the sensor is extremely linear (far better than 1% of full scale); temperature compensation is to better than 1% of full scale. TREMOR-class instruments are intended to fill the niche of high spatial resolution with an economical low-maintenance device, while conventional instruments continue to pursue maximum amplitude resolution. The TREMOR instrument also has applications in areas where budget or access limitations require lower purchase, installation, or maintenance cost (commercial ANSS partners, remote sites, on-call aftershock arrays, extremely dense arrays, and organizations with limited budgets). However, we primarily envision large, mixed arrays of conventional and TREMOR instruments in urban areas, the former providing better early information from small events and the TREMOR instruments guaranteeing better spatial resolution and more near-field recording of large events. Together, they would meet the ANSS goal of dense near-real-time urban monitoring and the collection of requisite data for risk mitigation.

  10. Migrating tremors illuminate complex deformation beneath the seismogenic San Andreas fault

    Science.gov (United States)

    Shelly, D.R.

    2010-01-01

    The San Andreas fault is one of the most extensively studied faults in the world, yet its physical character and deformation mode beneath the relatively shallow earthquake-generating portion remain largely unconstrained. Tectonic non-volcanic tremor, a recently discovered seismic signal probably generated by shear slip on the deep extension of some major faults, can provide new insight into the deep fate of such faults, including that of the San Andreas fault near Parkfield, California. Here I examine continuous seismic data from mid-2001 to 2008, identifying tremor and decomposing the signal into different families of activity based on the shape and timing of the waveforms at multiple stations. This approach allows differentiation between activities from nearby patches of the deep fault and begins to unveil rich and complex patterns of tremor occurrence. I find that tremor exhibits nearly continuous migration, with the most extensive episodes propagating more than 20 kilometres along fault strike at rates of 15-80 kilometres per hour. This suggests that the San Andreas fault remains a localized through-going structure, at least to the base of the crust, in this area. Tremor rates and recurrence behaviour changed markedly in the wake of the 2004 magnitude-6.0 Parkfield earthquake, but these changes were far from uniform within the tremor zone, probably reflecting heterogeneous fault properties and static and dynamic stresses decaying away from the rupture. The systematic recurrence of tremor demonstrated here suggests the potential to monitor detailed time-varying deformation on this portion of the deep San Andreas fault, deformation which unsteadily loads the shallower zone that last ruptured in the 1857 magnitude-7.9 Fort Tejon earthquake. ?? 2010 Macmillan Publishers Limited. All rights reserved.

  11. Electrophysiologic Assessments of Involuntary Movements: Tremor and Myoclonus

    Directory of Open Access Journals (Sweden)

    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.

  12. Nonvolcanic tremor observed in the Mexican subduction zone

    Science.gov (United States)

    Payero, Juan S.; Kostoglodov, Vladimir; Shapiro, Nikolai; Mikumo, Takeshi; Iglesias, Arturo; Pérez-Campos, Xyoli; Clayton, Robert W.

    2008-04-01

    Nonvolcanic tremor (NVT) activity is revealed as episodes of higher spectral amplitude at 1-8 Hz in daily spectrograms from the continuous seismological records in Guerrero, Mexico. The analyzed data cover a period of 2001-2007 when in 2001-2002 a large slow slip event (SSE) had occurred in the Guerrero-Oaxaca region, and then a new large SSE occurred in 2006. The tremor burst is dominated by S-waves. More than 100 strong NVT bursts were recorded in the narrow band of ~40 × 150 km2 to the south of Iguala City and parallel to the coastline. Depths of NVT hypocenters are mostly scattered in the continental crust between 5 and 40 km depth. Tremor activity is higher during the 2001-2002 and 2006 SSE compared with that for the ``quiet'' period of 2003-2005. While resistivity pattern in Guerrero does not correlate directly with the NVT distribution, gravity and magnetic anomaly modeling favors a hypothesis that the NVT is apparently related to the dehydration and serpentinization processes.

  13. Modulation of voice related to tremor and vibrato

    Science.gov (United States)

    Lester, Rosemary Anne

    Modulation of voice is a result of physiologic oscillation within one or more components of the vocal system including the breathing apparatus (i.e., pressure supply), the larynx (i.e. sound source), and the vocal tract (i.e., sound filter). These oscillations may be caused by pathological tremor associated with neurological disorders like essential tremor or by volitional production of vibrato in singers. Because the acoustical characteristics of voice modulation specific to each component of the vocal system and the effect of these characteristics on perception are not well-understood, it is difficult to assess individuals with vocal tremor and to determine the most effective interventions for reducing the perceptual severity of the disorder. The purpose of the present studies was to determine how the acoustical characteristics associated with laryngeal-based vocal tremor affect the perception of the magnitude of voice modulation, and to determine if adjustments could be made to the voice source and vocal tract filter to alter the acoustic output and reduce the perception of modulation. This research was carried out using both a computational model of speech production and trained singers producing vibrato to simulate laryngeal-based vocal tremor with different voice source characteristics (i.e., vocal fold length and degree of vocal fold adduction) and different vocal tract filter characteristics (i.e., vowel shapes). It was expected that, by making adjustments to the voice source and vocal tract filter that reduce the amplitude of the higher harmonics, the perception of magnitude of voice modulation would be reduced. The results of this study revealed that listeners' perception of the magnitude of modulation of voice was affected by the degree of vocal fold adduction and the vocal tract shape with the computational model, but only by the vocal quality (corresponding to the degree of vocal fold adduction) with the female singer. Based on regression analyses

  14. Volcanic Lake System at Aso Volcano, Japan: Fluctuations in the Supply of Volcanic Fluid from the Hydrothermal System beneath the Crater Lake (Invited)

    Science.gov (United States)

    Terada, A.; Hashimoto, T.; Kagiyama, T.

    2010-12-01

    /s) and enthalpy (1,800-3,000 kJ/kg) for the fluid supplied to the lake. We assumed that the fluid is mixture of high-temperature steam (800 °C) and liquid water (100 °C), and assessed their mass fluxes. The liquid water flux shows a seasonal variation, lagging the rainy season by 2 months, suggesting that a proportion of the liquid water is groundwater. The pattern of fluctuations in the flux of high-temperature steam shows a relation with the amplitude of continuous volcanic tremor. We consider that heating of the hydrothermal system drives the tremor.

  15. Catastrophic volcanism

    Science.gov (United States)

    Lipman, Peter W.

    1988-01-01

    Since primitive times, catastrophes due to volcanic activity have been vivid in the mind of man, who knew that his activities in many parts of the world were threatened by lava flows, mudflows, and ash falls. Within the present century, increasingly complex interactions between volcanism and the environment, on scales not previously experienced historically, have been detected or suspected from geologic observations. These include enormous hot pyroclastic flows associated with collapse at source calderas and fed by eruption columns that reached the stratosphere, relations between huge flood basalt eruptions at hotspots and the rifting of continents, devastating laterally-directed volcanic blasts and pyroclastic surges, great volcanic-generated tsunamis, climate modification from volcanic release of ash and sulfur aerosols into the upper atmosphere, modification of ocean circulation by volcanic constructs and attendent climatic implications, global pulsations in intensity of volcanic activity, and perhaps triggering of some intense terrestrial volcanism by planetary impacts. Complex feedback between volcanic activity and additional seemingly unrelated terrestrial processes likely remains unrecognized. Only recently has it become possible to begin to evaluate the degree to which such large-scale volcanic processes may have been important in triggering or modulating the tempo of faunal extinctions and other evolutionary events. In this overview, such processes are examined from the viewpoint of a field volcanologist, rather than as a previous participant in controversies concerning the interrelations between extinctions, impacts, and volcanism.

  16. Ambient tremors in a collisional orogenic belt

    Science.gov (United States)

    Chuang, Lindsay Yuling; Chen, Kate Huihsuan; Wech, Aaron G.; Byrne, Timothy; Peng, Wei

    2014-01-01

    Deep-seated tectonic tremors have been regarded as an observation tied to interconnected fluids at depth, which have been well documented in worldwide subduction zones and transform faults but not in a collisional mountain belt. In this study we explore the general features of collisional tremors in Taiwan and discuss the possible generation mechanism. In the 4 year data, we find 231 ambient tremor episodes with durations ranging from 5 to 30 min. In addition to a coseismic slip-induced stress change from nearby major earthquake, increased tremor rate is also highly correlated with the active, normal faulting earthquake swarms at the shallower depth. Both the tremor and earthquake swarm activities are confined in a small, area where the high attenuation, high thermal anomaly, the boundary between high and low resistivity, and localized veins on the surfaces distributed, suggesting the involvement of fluids from metamorphic dehydration within the orogen.

  17. 震颤的诊断和鉴别诊断策略%Differential diagnosis of tremor and its strategy

    Institute of Scientific and Technical Information of China (English)

    张文波; 王宇卉

    2012-01-01

    Tremors are the most prevalent movement disorder in clinic. Tremors can be classified on the basis of observable clinical characteristics: anatomical pattern, frequency amplitude and the related prominence of the tremor. Its diagnosis is still besed on clinical observation and descriptive analysis. This review describes the clinical features and investigational techniques for diagnosis of tremors.%震颤是最常见的运动障碍,临床上可根据震颤特征即发作方式、频率与幅度等进行分类.其诊断目前仍以临床观察与描述性分析为主.本文综述震颤的临床特征,常见及罕见原因,以及诊断分析过程.

  18. Corticomuscular coherence in asymptomatic first-degree relatives of patients with essential tremor.

    Science.gov (United States)

    Raethjen, Jan; Muthuraman, Muthuraman; Kostka, Achim; Nahrwold, Martin; Hellriegel, Helge; Lorenz, Delia; Deuschl, Günther

    2013-05-01

    Essential tremor (ET) follows an autosomal dominant type of inheritance in the majority of patients, yet its genetic basis has not been identified. Its exact origin is still elusive, but coherence measurements between electromyography tremor bursts and electroencephalography unequivocally demonstrate a correlation. We tested these measurements in 37 healthy first-degree relatives (children) of patients with essential tremor (ET) and a group of 37 age-matched and sex-matched controls. Pooled coherence spectra of the maximally coherent electroencephalogram electrodes were computed for ET relatives and controls. The maximal coherence and its frequency were significantly higher in ET relatives than in controls during the pinch grip task and during slow hand movements. Electromyography amplitude (root-mean-square) was slightly but significantly greater in ET relatives, whereas 2-Hz to 40-Hz power and spectral peak frequency were not different. The presymptomatic alteration in corticomuscular interaction may reflect a role of genetic factors. Copyright © 2013 Movement Disorder Society.

  19. Semiautomated tremor detection using a combined cross-correlation and neural network approach

    Science.gov (United States)

    Horstmann, Tobias; Harrington, Rebecca M.; Cochran, Elizabeth S.

    2013-01-01

    Despite observations of tectonic tremor in many locations around the globe, the emergent phase arrivals, low‒amplitude waveforms, and variable event durations make automatic detection a nontrivial task. In this study, we employ a new method to identify tremor in large data sets using a semiautomated technique. The method first reduces the data volume with an envelope cross‒correlation technique, followed by a Self‒Organizing Map (SOM) algorithm to identify and classify event types. The method detects tremor in an automated fashion after calibrating for a specific data set, hence we refer to it as being “semiautomated”. We apply the semiautomated detection algorithm to a newly acquired data set of waveforms from a temporary deployment of 13 seismometers near Cholame, California, from May 2010 to July 2011. We manually identify tremor events in a 3 week long test data set and compare to the SOM output and find a detection accuracy of 79.5%. Detection accuracy improves with increasing signal‒to‒noise ratios and number of available stations. We find detection completeness of 96% for tremor events with signal‒to‒noise ratios above 3 and optimal results when data from at least 10 stations are available. We compare the SOM algorithm to the envelope correlation method of Wech and Creager and find the SOM performs significantly better, at least for the data set examined here. Using the SOM algorithm, we detect 2606 tremor events with a cumulative signal duration of nearly 55 h during the 13 month deployment. Overall, the SOM algorithm is shown to be a flexible new method that utilizes characteristics of the waveforms to identify tremor from noise or other seismic signals.

  20. Episodic Tremor and Slip (ETS) as a chaotic multiphysics spring

    Science.gov (United States)

    Veveakis, E.; Alevizos, S.; Poulet, T.

    2017-03-01

    Episodic Tremor and Slip (ETS) events display a rich behaviour of slow and accelerated slip with simple oscillatory to complicated chaotic time series. It is commonly believed that the fast events appearing as non volcanic tremors are signatures of deep fluid injection. The fluid source is suggested to be related to the breakdown of hydrous phyllosilicates, mainly the serpentinite group minerals such as antigorite or lizardite that are widespread in the top of the slab in subduction environments. Similar ETS sequences are recorded in different lithologies in exhumed crustal carbonate-rich thrusts where the fluid source is suggested to be the more vigorous carbonate decomposition reaction. If indeed both types of events can be understood and modelled by the same generic fluid release reaction AB(solid) ⇌A(solid) +B(fluid) , the data from ETS sequences in subduction zones reveal a geophysically tractable temporal evolution with no access to the fault zone. This work reviews recent advances in modelling ETS events considering the multiphysics instabilities triggered by the fluid release reaction and develops a thermal-hydraulic-mechanical-chemical oscillator (THMC spring) model for such mineral reactions (like dehydration and decomposition) in Megathrusts. We describe advanced computational methods for THMC instabilities and discuss spectral element and finite element solutions. We apply the presented numerical methods to field examples of this important mechanism and reproduce the temporal signature of the Cascadia and Hikurangi trench with a serpentinite oscillator.

  1. Continuous theta-burst stimulation of the primary motor cortex in essential tremor.

    Science.gov (United States)

    Hellriegel, Helge; Schulz, Eva M; Siebner, Hartwig R; Deuschl, Günther; Raethjen, Jan H

    2012-05-01

    We investigated whether essential tremor (ET) can be altered by suppressing the corticospinal excitability in the primary motor cortex (M1) with transcranial magnetic stimulation. 10 Patients with ET and 10 healthy controls underwent transcranial continuous theta-burst stimulation (cTBS) of the left primary motor hand area at 80% (real cTBS) and 30% (control cTBS) of active motor threshold in two separate sessions at least one week apart. Postural tremor was rated clinically and measured accelerometrically before and after cTBS. Corticospinal excitability was assessed by recording the motor evoked potentials (MEP) from the first dorsal interosseous muscle. Real cTBS but not control cTBS reduced the tremor total power assessed with accelerometry. This beneficial effect was subclinical as there were no significant changes in clinical tremor rating after real cTBS. Relative to control cTBS, real cTBS reduced corticospinal excitability in the stimulated primary motor cortex only in healthy controls but not in ET patients. Real cTBS has a beneficial effect on ET. Since cTBS did not induce a parallel reduction in corticospinal excitability, this effect was not mediated by a suppression of the corticospinal motor output. "Inhibitory" cTBS of M1 leads to a consistent but subclinical reduction in tremor amplitude. Copyright © 2011 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  2. Very Low Frequency Earthquakes (VLFEs) in Cascadia and Their Interactions with Tremor

    Science.gov (United States)

    Ghosh, A.

    2014-12-01

    Very low frequency earthquakes (VLFEs) are discrete seismic events rich in low frequencies (20 - 50 sec) and depleted in high frequencies compared to similar size local events. They are associated with slow earthquakes and so far found in only a handful of subduction zones worldwide. I systematically search and find VLFEs in the Cascadia subduction zone. I use a grid-search moment tensor inversion method to scan for VLFEs in 3-D space and time, locate them and determine their source parameters. They are located downdip of the locked zone, where non-volcanic tremor occurs (Fig. 1). The best estimates of VLFE depths put them near the plate interface. Their focal mechanisms indicate double couple sources and are consistent with shallow dipping thrust movement. Their moment magnitude ranges between 3.3 and 3.5 suggesting that a significant part of seismic moment may be released by such VLFEs during slow earthquakes. Interestingly, most of the VLFEs are located where the slip is the largest in an ETS event. Generally, VLFEs correlates with tremor quite well in space and time. They slowly migrate alongstrike form south to north with tremor. In detail, VLFEs appear to be tracking tremor even during tremor migration of shorter time scales. I am currently expanding the VLFE catalog in space and time to better characterize their spatiotemporal distribution, moment release, and their role in slow earthquakes. VLFEs and their interaction with tremor is providing new insights to the physics of slow earthquakes, underlying processes governing them and fault properties in Cascadia.

  3. Beeinflussung des Essentiellen Tremors und des Tremors beim Morbus Parkinson durch transkranielle Gleichstromstimulation

    OpenAIRE

    Hellriegel, Helge

    2010-01-01

    Ziel dieser Arbeit war es die Rolle des primärmotorischen Kortex bei der Entstehung und Weiterleitung des Essentiellen Tremors und des Tremors beim Morbus Parkinson zu untersuchen. Hierzu wurde eine transkranielle Gleichstromstimulation über dem primärmotorischen Kortex bei Patienten mit oben genannten Tremorsyndromen durchgeführt und die klinischen sowie elektrophysiologisch messbaren Änderungen des Tremors beurteilt.

  4. Tectonic tremor on Vancouver Island, Cascadia, modulated by the body and surface waves of the Mw 8.6 and 8.2, 2012 East Indian Ocean earthquakes

    Science.gov (United States)

    Kundu, Bhaskar; Ghosh, Abhijit; Mendoza, Manuel; Bürgmann, Roland; Gahalaut, V. K.; Saikia, Dipankar

    2016-09-01

    The 2012 East Indian Ocean earthquake (Mw 8.6), so far the largest intraoceanic plate strike-slip event ever recorded, modulated tectonic tremors in the Cascadia subduction zone. The rate of tremor activity near Vancouver Island increased by about 1.5 times from its background level during the passage of seismic waves of this earthquake. In most cases of dynamic modulation, large-amplitude and long-period surface waves stimulate tremors. However, in this case even the small stress change caused by body waves generated by the 2012 earthquake modulated tremor activity. The tremor modulation continued during the passage of the surface waves, subsequent to which the tremor activity returned to background rates. Similar tremor modulation is observed during the passage of the teleseismic waves from the Mw 8.2 event, which occurs about 2 h later near the Mw 8.6 event. We show that dynamic stresses from back-to-back large teleseismic events can strongly influence tremor sources.

  5. Relationship between resting and action tremors in Parkinson's disease

    Directory of Open Access Journals (Sweden)

    Abdul Qayyum Rana

    2016-01-01

    Full Text Available Objective: To determine the relationship between resting tremor (RT and action tremor (AT in Parkinson's disease (PD patients. Methods: A retrospective study of RT and AT severity was conducted in 100 PD patients. The severity rating for each type of tremor in the upper extremities was assessed. The disparity in tremor severity between extremities for each tremor type was compared to that of the other two to identify commonalities in the laterality of the tremor manifestation. Results: Overall, RT is predictive of AT on the same side, but not the opposing side of the body. Patients with less intense resting right upper limb (RRU tremor and moderately intense RRU tremor were significantly more likely to have an action right upper limb (ARU tremor (−1.53, P = 0.020; −1.88, P = 0.005, respectively. Similarly, patients with less intense resting left upper limb (RLU tremor and moderately intense RLU tremors were significantly more likely to have an action left upper limb (ALU tremor (−3.49, P = 0.000; −1.86, P = 0.017, respectively. In addition, RRU and ALU tremors were associated with an increase in RLU and ARU tremors, respectively. Conclusion: Tremors are common findings in PD patients, and often impair quality of life. By identifying and classifying the relationship between resting and ATs in PD patients, our study sheds light onto the importance of better understanding and future management of this debilitating symptomology.

  6. Management of tremor in medieval Persia.

    Science.gov (United States)

    Zargaran, Arman; Zarshenas, Mohammad M; Mehdizadeh, Alireza; Mohagheghzadeh, Abdolali

    2013-01-01

    Tremor has been described in traditional systems of medicine throughout history. Persian medicine was one of those systems in medieval times and in it neurology and neurosurgery were also widely practiced and accepted. Based on the main Persian medical manuscripts, the current study focuses on the medieval concept of tremor as an important neurological disorder in order to clarify the development of neurology. Accordingly, three main approaches to the control and treatment of tremor in traditional Persian medicine are considered. First is lifestyle modification. The administration of simple medicines is the second, and the last is the application of compound medicines. Our study shows how much was known about tremor in traditional Persian medicine.

  7. Characteristics of Task-specific Tremor in String Instrument Players

    Science.gov (United States)

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

    2014-01-01

    Background In recent studies primary bowing tremor has been described; however, tremor frequency has never been quantitatively assessed. In addition to describing phenomenological aspects of tremor we thus aimed at assessing tremor frequency. Our hypothesis was that primary bowing tremor is similar to the phenomenological aspects and frequency of primary writing tremor. Methods We quantified primary bowing tremor in four violinists under two conditions: open strings and a G major scale. Data were analyzed using empirical mode decomposition because it takes into account non-stationarity and non-linearity of signals. For each patient we further described tremor phenomenology and assessed symptom onset, risk factors, medication, and family history with a structured anamnesis. We compare the findings to previous findings for primary bowing tremor and primary writing tremor. Results We mainly found a flexion–extension tremor of the wrist with a frequency range of 4.7–6.7 Hz. There was no significant difference between the conditions. Mean onset age was 43±2.4 years. Medication included trihexyphenidyl, propranolol, primidone, and botulinum toxin. We found a positive family history in two patients and an injury prior to symptom onset in another two patients. Comparison of onset age, frequency range, family history, and injuries prior to onset revealed that our findings are very similar to previous findings on primary bowing tremor and primary writing tremor. Discussion Our findings confirmed our hypothesis that primary bowing tremor is similar to primary writing tremor, with regard to phenomenology and epidemiology as well as tremor frequency. There was no difference in tremor frequency between conditions, suggesting that tremor is not influenced by bimanual coordination or bowing speed. Our findings thus provide new phenomenological aspects and may contribute to a better understanding of primary bowing tremor. PMID:24932423

  8. Source Processes Revealed at Two Guatemalan Volcanoes: Insights from Multidisciplinary Observations of Harmonic Tremor and Numerical Modeling

    Science.gov (United States)

    Brill, K. A.; Waite, G. P.

    2012-12-01

    Tremor signals at volcanoes are typically attributed to fluid movement within the system. Characteristics of harmonic tremor (i.e. duration, frequency content, polarization) can convey detailed information about source processes from which they emanate, but decoding these signals poses great challenges due to the complexity of volcanic environments. We recorded instances of harmonic tremor at both Santiaguito and Fuego volcanoes Guatemala, Central America. The instances of harmonic tremor occur both independent from and contemporaneous with explosions, and last anywhere from 30 seconds to tens of minutes. The signals have fundamental frequencies between 0.3 and 2.5 Hz, with as many as 20 overtones, and exhibit spectral gliding of up to 0.75 Hz over the course of an event, changing as quickly as 0.1 Hz/second. Field observations; video recordings; and time-lapse, ultraviolet, and thermal imagery; collected simultaneously with acoustic and seismic recordings allow us to constrain source locations and processes beyond what would otherwise be possible just acoustic and seismic recordings. We propose that the harmonic tremor signals are generated by nonlinear excitation of fracture walls as gas vents out of the systems. Additionally, we investigate the complex wavefield generated by harmonic tremor and the heterogeneous volcanic media. Particle motions at both volcanoes are typically elliptical, but vary dramatically over time as the fundamental frequency glides up and down (see figure). In addition, the particle motions of harmonics often have different polarities from each other and the fundamental frequency. Through finite difference modeling, we isolate the effects of near-field terms, topography, and source mechanism to explore each of these factors' contribution to the unexpected behavior.

  9. Development of an essential tremor embarrassment assessment.

    Science.gov (United States)

    Traub, Rebecca E; Gerbin, Marina; Mullaney, Mary M; Louis, Elan D

    2010-12-01

    Embarrassment is commonly reported in essential tremor (ET) patients yet there is no formal tool to assess embarrassment in ET. Our aim was to develop such a tool and to assess its clinimetric properties. A quantitative measure of embarrassment could be used to assess response to treatment in clinical practice and clinical trials. Based on surveys of international tremor experts and ET patients, we constructed the Essential Tremor Embarrassment Assessment (ETEA), a brief, easily administered, 14-item self-assessment scale. The ETEA was assessed for validity, reliability and other clinimetric properties in 75 ET patients. Forty-seven tremor experts from eight countries were surveyed. On average, they estimated that 75% of their patients experienced embarrassment, yet there was very little agreement (range = 10-95%). Among ET patients, three-quarters (77.3%) reported at least occasional embarrassment due to their tremor and one-third (36.4%) reported daily embarrassment. ETEA scores correlated with a tremor disability questionnaire score (p = 0.02 and p = 0.01) and Center for Epidemiologic Studies Depression Scale scores (pEmbarrassment is commonly experienced by ET patients. The ETEA is a reliable and valid tool to measure embarrassment in patients with this disease. Copyright © 2010 Elsevier Ltd. All rights reserved.

  10. Seismic monitoring at Cascade Volcanic Centers, 2004?status and recommendations

    Science.gov (United States)

    Moran, Seth C.

    2004-01-01

    The purpose of this report is to assess the current (May, 2004) status of seismic monitoring networks at the 13 major Cascade volcanic centers. Included in this assessment are descriptions of each network, analyses of the ability of each network to detect and to locate seismic activity, identification of specific weaknesses in each network, and a prioritized list of those networks that are most in need of additional seismic stations. At the outset it should be recognized that no Cascade volcanic center currently has an adequate seismic network relative to modern-day networks at Usu Volcano (Japan) or Etna and Stromboli volcanoes (Italy). For a system the size of Three Sisters, for example, a modern-day, cutting-edge seismic network would ideally consist of a minimum of 10 to 12 short-period three-component seismometers (for determining particle motions, reliable S-wave picks, moment tensor inversions, fault-plane solutions, and other important seismic parameters) and 7 to 10 broadband sensors (which, amongst other considerations, enable detection and location of very long period (VLP) and other low-frequency events, moment tensor inversions, and, because of their wide dynamic range, on-scale recording of large-amplitude events). Such a dense, multi component seismic network would give the ability to, for example, detect in near-real-time earthquake migrations over a distance of ~0.5km or less, locate tremor sources, determine the nature of a seismic source (that is, pure shear, implosive, explosive), provide on-scale recordings of very small and very large-amplitude seismic signals, and detect localized changes in seismic stress tensor orientations caused by movement of magma bodies. However, given that programmatic resources are currently limited, installation of such networks at this time is unrealistic. Instead, this report focuses on identifying what additional stations are needed to guarantee that anomalous seismicity associated with volcanic unrest will be

  11. Imaging Slow Slip Fronts in Cascadia With High-Precision Tremor Locations

    Science.gov (United States)

    Rubin, A. M.; Armbruster, J. G.

    2012-12-01

    of tremor sources. For those that occur behind the main front this explanation seems less likely, as the implied along-strike propagation would have to pass over closely-spaced tremor sources without triggering detected ones. The source of the stress drops driving the multiple secondary slip events (reloading by continued propagation of the main front; failure of tremor-producing asperities; tides; progressive weakening of the slip surface during rapid sliding) is not clear. In addition to a modest tidal modulation of the tremor amplitude, tremor amplitude tends to be smaller within 0.5-1 km of the main front than farther behind; it is possible that we are resolving the region at the front that is accelerating to the maximum slip speed. For the secondary fronts there is no obvious correlation between tremor amplitude and propagation speed.

  12. Tremor recording and analysis as a tool for target localisation in thalamotomy and DBS for tremor

    NARCIS (Netherlands)

    Journee, HL; Hamoen, DJ; Staal, MJ; Sclabassi, R; Haaxma, R; Elands, A; Hummel, JJJ; Boom, H; Robinson, C; Rutten, W; Neuman, M; Wijkstra, H

    1997-01-01

    The objective of this work was to design and use a tremor and analysis system for stereotactic thalamotomy and thalamus stimulation (DBS). A notebook PC based system was developed. The tremor was measured by accelero-transducers or EMG. The method was used to confirm the definitive localization of

  13. Tremor recording and analysis as a tool for target localisation in thalamotomy and DBS for tremor

    NARCIS (Netherlands)

    Journee, HL; Hamoen, DJ; Staal, MJ; Sclabassi, R; Haaxma, R; Elands, A; Hummel, JJJ; Boom, H; Robinson, C; Rutten, W; Neuman, M; Wijkstra, H

    1997-01-01

    The objective of this work was to design and use a tremor and analysis system for stereotactic thalamotomy and thalamus stimulation (DBS). A notebook PC based system was developed. The tremor was measured by accelero-transducers or EMG. The method was used to confirm the definitive localization of t

  14. Northern Cascadia episodic tremor and slip: A decade of tremor observations from 1997 to 2007

    Science.gov (United States)

    Kao, Honn; Shan, Shao-Ju; Dragert, Herb; Rogers, Garry

    2009-11-01

    We analyze continuous seismic and GPS records collected in the last decade (1997-2007) to establish the most comprehensive observational basis for northern Cascadia episodic tremor and slip (ETS) events. A simple "ETS scale" system, using a combination of a letter and a digit, is proposed to quantitatively characterize the spatial and temporal dimensions of ETS events. Clear correlation between GPS and tremor signals is observed for all A/B class episodes, but the GPS signature is less obvious for minor ones. Regular ETS recurrence can be established only for A/B class episodes in southern Vancouver Island. Halting and jumping are very common in ETS migration patterns, and along-strike migration can happen in both directions. A prominent tremor gap is observed in midisland around 49.5°N. This gap coincides with the epicenters of the only two large earthquakes beneath Vancouver Island. ETS tremors also tend to occur in places where the local seismicity is relatively sparse. The tremor depth distribution shows a peak in the 25-35 km range where strong seismic reflectors (i.e., the E layer) are documented. Detailed waveform analysis confirms the existence of shallow tremors above the currently interpreted plate interface. Our results suggest that a significant portion of the tremor activity and perhaps associated shearing are taking place along well-developed structures such as the E layer, while fewer tremor bursts are generated elsewhere in response to the induced stress variation throughout the source volume.

  15. Tectonic tremor and LFEs on a reverse fault in Taiwan: TREMOR AND LFES IN TAIWAN

    Energy Technology Data Exchange (ETDEWEB)

    Aguiar, Ana C. [Lawrence Livermore National Laboratory, Livermore California USA; Geophysics Department, Stanford University, Stanford California USA; Chao, Kevin [Center for Optimization and Statistical Learning, Northwestern Institute on Complex Systems, Northwestern University, Evanston Illinois USA; Beroza, Gregory C. [Geophysics Department, Stanford University, Stanford California USA

    2017-07-06

    We compare low-frequency earthquakes (LFEs) from triggered and ambient tremor under the southern Central Range, Taiwan. We apply the PageRank algorithm used by Aguiar and Beroza (2014) that exploits the repetitive nature of the LFEs to find repeating LFEs in both ambient and triggered tremor. We use these repeaters to create LFE templates and find that the templates created from both tremor types are very similar. To test their similarity, we use both interchangeably and find that most of both the ambient and triggered tremor match the LFE templates created from either data set, suggesting that LFEs for both events have a common origin. We locate the LFEs by using local earthquake P wave and S wave information and find that LFEs from triggered and ambient tremor locate to between 20 and 35 km on what we interpret as the deep extension of the Chaochou-Lishan Fault.

  16. Eighteen years of geochemical monitoring at the oceanic active volcanic island of El Hierro (Canary Islands, Spain)

    Science.gov (United States)

    Asensio-Ramos, María; Alonso, Mar; Sharp, Emerson; Woods, Hannah; Barrancos, José; Pérez, Nemesio M.

    2016-04-01

    We report herein the latest results of a diffuse CO2 efflux survey at El Hierro volcanic system carried out during the summer period of 2015 to constrain the total CO2 output from the studied area a during post-eruptive period. El Hierro Island (278 km2) is the youngest and the SW-most of the Canary Islands. On July 16, 2011, a seismic-volcanic crisis started with the occurrence of more than 11,900 seismic events and significant deformation along the island. On October 10, 2011, the dominant character of seismicity changed dramatically from discrete earthquakes to continuous tremor, a clear indication that magma was rapidly approaching the surface immediately before the onset of the eruption, October 12. Eruption was declared over on 5 March, 2012. In order to monitor the volcanic activity of El Hierro Island, from 1998 to 2015 diffuse CO2 emission studies have been performed at El Hierro volcanic system in a yearly basis (˜600 observation sites) according to the accumulation chamber method. Spatial distribution maps were constructed following the sequential Gaussian simulation (sGs) procedure. To quantify the total CO2 emission from the studied area, 100 simulations for each survey have been performed. During the eruption period, soil CO2 efflux values range from non-detectable (˜0.5 g m-2 d-1) up to 457 g m-2 d-1, reaching in November 27, 2011, the maximum CO2 output estimated value of all time series, 2,398 t d-1, just before the episodes of maximum degassing observed as vigorous bubbling at the sea surface and an increment in the amplitude of the tremor signal. During the 2015 survey, soil CO2 efflux values ranged from non-detectable up to 41 g m-2 d-1. The spatial distribution of diffuse CO2 emission values seemed to be controlled by the main volcano structural features of the island. The total diffuse CO2 output released to atmosphere was estimated at 575 ± 24 t d-1, value slightly higher that the background CO2 emission estimated at 422 t d-1 (Melián et

  17. A review of primary writing tremor.

    Science.gov (United States)

    Rana, Abdul Qayyum; Vaid, Haris M

    2012-03-01

    A task-specific tremor (TST) is a rare form of movement disorder that appears while performing or attempting to perform a particular task. Primary writing tremor (PWT) is the most common form of TST which only occurs during the act of writing and hinders it. (Bain PG, Findley LJ, Britton TC, Rothwell JC, Gresty MA, Thompson PD, Marsden CD. MRC Human Movement, and Balance Unit, Institute of Neurology, London, UK. Primary writing tremor. Brain. 1995;118(6):1461-72.) Primary writing tremor type B is present not only during the act of writing but also when the hand assumes a writing posture. (Bain PG, Findley LJ, Britton TC, Rothwell JC, Gresty MA, Thompson PD, Marsden CD. MRC Human Movement and Balance Unit, Institute of Neurology, London, UK. Primary writing tremor. Brain. 1995;118(6):1461-72.) We first of all describe a remarkable case study of a 50-year old, right-handed male who started experiencing a primary writing tremor in his right hand about a year ago. This case was found to be of particular interest because the patient had it relatively difficult when attempting to write numbers as opposed to writing letters. This review further discusses the clinical manifestations of PWT. In addition, three main hypotheses have been proposed for the causation of PWT, although the exact pathophysiology of PWT still remains unknown. It has been suggested that PWT is a separate entity, a variant of essential tremor and not a separate entity, or a type of dystonia. The various treatment options for PWT are discussed including botulinum toxin and oral pharmacotherapy.

  18. Shallow micro low-frequency tremor before the Tohoku-Oki earthquake

    Science.gov (United States)

    Katakami, Satoshi; Ito, Yoshihiro; Ohta, Kazuaki; Hino, Ryota; Suzuki, Syuichi; Shinohara, Masanao

    2017-04-01

    Slow earthquake activity is one of the important phenomena to understand slip behavior in the shallower part of the subduction zone, especially to understand the generation of tsunami earthquakes. Recently, SSEs and low-frequency tremor have been observed near the trench by using ocean bottom observations, and these have been located in the updip portion of a coseismic slip area [Wallace et al., 2016; Yamashita et al., 2015]. In addition, Ito et al. [2015] observed tremor sequences from the excitation of ambient noise amplitude, accompanied with SSE in the source area of the Tohoku-Oki earthquake's mainshock. However, the signals observed within these sequences showed very weak amplitude and were observed at only one station, nearest to the Japan Trench. Here, we report on our detection of micro low-frequency tectonic tremor (mLFT) activity prior to the 2011 Tohoku-Oki earthquake near the Japan Trench by using modified frequency scanning method (mFSM) as applied to ocean bottom seismometers (OBSs) . The original frequency scanning method [Sit et al., 2012] proposed a tremor detection method of calculating envelope waveform ratios through different bandpass filters of broadband data in the Cascadia margin. We modified this analysis for short period OBS seismic data recorded at 17 OBSs deployed in an area near the trench axis offshore Miyagi Prefecture, northeast Japan. Three bandpass filters of 2-4 Hz, 10-20 Hz, and 0.5-1.0 Hz, corresponding to the dominant frequency band of tremors, local earthquakes, and ocean noise, respectively, were applied to the OBS records for a period between November 19, 2010 and March 9, 2011. This duration is the same as the deployment period of TJT2 station which is located nearest to the Japan Trench, and is also before the largest foreshock of the Tohoku-Oki earthquake. The results of applying the mFSM show three major tremor sequences, suggesting tremor activity in the shallowest part of the subduction zone. The sequences agree with

  19. The central oscillatory network of orthostatic tremor.

    Science.gov (United States)

    Muthuraman, Muthuraman; Hellriegel, Helge; Paschen, Steffen; Hofschulte, Frank; Reese, Rene; Volkmann, Jens; Witt, K; Deuschl, G; Raethjen, Jan

    2013-09-01

    Orthostatic tremor (OT) is a movement disorder of the legs and trunk that is present in the standing position but typically absent when sitting. The pathological central network involved in orthostatic tremor is still unknown. In this study we analyzed 15 patients with simultaneous high-resolution electroencephalography and electromyography recording to assess corticomuscular coherence. In 1 patient we were able to simultaneously record the local field potential in the ventrolateral thalamus and electroencephalography. Dynamic imaging of coherent source analysis was used to find the sources in the brain that are coherent with the peripheral tremor signal. When standing, the network for the tremor frequency consisted of unilateral activation in the primary motor leg area, supplementary motor area, primary sensory cortex, two prefrontal/premotor sources, thalamus, and cerebellum for the whole 30-second segment recorded. The source coherence dynamics for the primary leg area and the thalamic source signals with the tibialis anterior muscle showed that they were highly coherent for the whole 30 seconds for the contralateral side but markedly decreased after 15 seconds for the ipsilateral side. The source signal and the recorded thalamus signal followed the same time frequency dynamics of coherence in 1 patient. The corticomuscular interaction in OT follows a consistent pattern with an initially bilateral pattern and then a segregated unilateral pattern after 15 seconds. This may add to the feeling of unsteadiness. It also makes the thalamus unlikely as the main source of orthostatic tremor. © 2013 International Parkinson and Movement Disorder Society.

  20. Tremor Reduction at the Palm of a Parkinson’s Patient Using Dynamic Vibration Absorber

    Directory of Open Access Journals (Sweden)

    Sarah Gebai

    2016-07-01

    Full Text Available Parkinson’s patients suffer from severe tremor due to an abnormality in their central oscillator. Medications used to decrease involuntary antagonistic muscles contraction can threaten their life. However, mechanical vibration absorbers can be used as an alternative treatment. The objective of this study is to provide a dynamic modeling of the human hand that describes the biodynamic response of Parkinson’s patients and to design an effective tuned vibration absorber able to suppress their pathological tremor. The hand is modeled as a three degrees-of-freedom (DOF system describing the flexion motion at the proximal joints on the horizontal plane. Resting tremor is modeled as dual harmonic excitation due to shoulder and elbow muscle activation operating at resonance frequencies. The performance of the single dynamic vibration absorber (DVA is studied when attached to the forearm and compared with the dual DVA tuned at both excitation frequencies. Equations of motion are derived and solved using the complex transfer function of the non-Lagrangian system. The absorber’s systems are designed as a stainless steel alloy cantilevered beam with an attached copper mass. The dual DVA was the most efficient absorber which reduces 98.3%–99.5%, 97.0%–97.3% and 97.4%–97.5% of the Parkinson’s tremor amplitude at the shoulder, elbow and wrist joint.

  1. Familial cortical tremor with epilepsy and cerebellar pathological findings

    NARCIS (Netherlands)

    van Rootselaar, AF; Aronica, E; Steur, ENHJ; Rozemuller-Kwakkel, JM; de Vos, RAI; Tijssen, MAJ

    The clinical and neuropathological findings in a patient with familial cortical tremor with epilepsy (FCTE) are described. Clinically, the patient showed cortical myoclonus, tremor, and generalized seizures. Pathological investigation showed cerebellar degeneration and somal sprouting and loss of

  2. Kinetic tremor: differences between smokers and non-smokers.

    Science.gov (United States)

    Louis, Elan D

    2007-05-01

    Tremor is among the acute effects of nicotine exposure. Published studies have focused on smoking-related postural (static) hand tremor rather than kinetic tremor (tremor during hand use), and gender differences in smoking-related tremor have not been examined. In a group of adults who were sampled from a population (mean+/-S.D.=65.7+/-11.5 years, range=18-92 years), the investigator assessed whether the severity of postural and kinetic tremors differed in smokers versus non-smokers, and whether this difference was influenced by gender. Twenty-seven (9.9%) of 273 subjects were current smokers. Greater tremor was observed in smokers than non-smokers during a variety of activities (drawing a spiral, using a spoon, finger-nose-finger maneuver, all phabits should be considered carefully in order to avoid over- or underestimating the effects of occupational and non-occupational exposures to other tremor-producing neurotoxins.

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

    Science.gov (United States)

    ... 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 ...

  4. Isolated tongue tremor after gamma knife radiosurgery for acoustic schwannoma.

    Science.gov (United States)

    Chung, Sun J; Im, Joo-Hyuk; Lee, Jae-Hong; Cho, A-Hyun; Kwon, Miseon; Lee, Myoung C

    2005-01-01

    We describe a patient who had an isolated tongue tremor with an audible click after gamma knife radiosurgery for acoustic schwannoma. The nature of the tongue tremor was clearly demonstrated by videofluoroscopy. The possible pathogenic mechanisms are discussed.

  5. Tremor da escrita: relato de caso

    Directory of Open Access Journals (Sweden)

    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.

  6. Spasmodic tremor and possible magma injection in Long Valley caldera, eastern California

    Energy Technology Data Exchange (ETDEWEB)

    Ryall, A.; Ryall, F.

    1983-03-25

    Intensive microearthquake swarms with the appearance of volcanic tremor have been observed in the southwest part of Long Valley caldera, southeastern California. This activity, possibly associated with magma injection, began 6 weeks after several strong (magnitude 6+) earthquakes in an area south of the caldera and has continued sporadically to the present time. The earthquake sequence and magmatic activity are part of a broad increase in tectonic activity in a 15,000-square-kilometer region surrounding the White Mountains seismic gap, an area with high potential for the next earthquake in the western Great Basin.

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

    Directory of Open Access Journals (Sweden)

    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.

  8. Diagnóstico diferencial dos tremores Differential diagnosis of tremors

    Directory of Open Access Journals (Sweden)

    JAMES PITÁGORAS DE MATTOS

    1998-06-01

    Full Text Available Baseado na revisão da literatura, o autor refere-se aos tremores normal (fisiológico e anormal (patológico. Analisa particularmente os patológicos, dividindo-os em de repouso e de ação. Com os elementos semiológicos estabelece o diagnóstico diferencial entre os tremores parkinsoniano, essencial severo, rubral, tardio, postural, cinético e os de posição e de ação específica, entre outros.After the review of the literature the author presents the semiologic basis for the differential diagnosis of rest and action tremors. The parkinsonian, severe essential, rubral, tardive, postural, kinetic and the task or position-specific tremors are mainly analysed.

  9. Dramatic response to levetiracetam in post-ischaemic Holmes’ tremor

    Science.gov (United States)

    Striano, P; Elefante, Andrea; Coppola, Antonietta; Tortora, Fabio; Zara, Federico; Minetti, Carlo

    2009-01-01

    Holmes’ tremor refers to an unusual combination of rest, postural and kinetic tremor of extremities. Common causes of Holmes’ tremor include stroke, trauma, vascular malformations and multiple sclerosis, with lesions involving the thalamus, brain stem or cerebellum. Although some drugs (eg, levodopa and dopaminergic drugs, clonazepam and propranolol) have been occasionally reported to give some benefit, medical treatment of Holmes’ tremor is unsatisfactory, and many patients require thalamic surgery to achieve satisfactory control. We report a patient in whom post-ischaemic Holmes’ tremor dramatically responded to levetiracetam treatment. PMID:21686707

  10. Remotely triggered microearthquakes and tremor in central California following the 2010 Mw 8.8 Chile earthquake

    Science.gov (United States)

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

    2010-01-01

    We examine remotely triggered microearthquakes and tectonic tremor in central California following the 2010 Mw 8.8 Chile earthquake. Several microearthquakes near the Coso Geothermal Field were apparently triggered, with the largest earthquake (Ml 3.5) occurring during the large-amplitude Love surface waves. The Chile mainshock also triggered numerous tremor bursts near the Parkfield-Cholame section of the San Andreas Fault (SAF). The locally triggered tremor bursts are partially masked at lower frequencies by the regionally triggered earthquake signals from Coso, but can be identified by applying high-pass or matched filters. Both triggered tremor along the SAF and the Ml 3.5 earthquake in Coso are consistent with frictional failure at different depths on critically-stressed faults under the Coulomb failure criteria. The triggered tremor, however, appears to be more phase-correlated with the surface waves than the triggered earthquakes, likely reflecting differences in constitutive properties between the brittle, seismogenic crust and the underlying lower crust.

  11. Facial emotion recognition is inversely correlated with tremor severity in essential tremor.

    Science.gov (United States)

    Auzou, Nicolas; Foubert-Samier, Alexandra; Dupouy, Sandrine; Meissner, Wassilios G

    2014-04-01

    We here assess limbic and orbitofrontal control in 20 patients with essential tremor (ET) and 18 age-matched healthy controls using the Ekman Facial Emotion Recognition Task and the IOWA Gambling Task. Our results show an inverse relation between facial emotion recognition and tremor severity. ET patients also showed worse performance in joy and fear recognition, as well as subtle abnormalities in risk detection, but these differences did not reach significance after correction for multiple testing.

  12. De fysiologische tremor van de hand

    NARCIS (Netherlands)

    Weerden, Tiemen Willem van

    1989-01-01

    Bij het innemen van een houding, zoals het willekeurig horizontaal gestrekt houden van de hand, vertoont het betrokken lichaamsdeel kleine fluctuaties in positie: de fysiologische tremor. Het doel van het proefschrift is, naast een beschrijving van het fenomeen, inzicht te geven in de oorzakelijke f

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

    Energy Technology Data Exchange (ETDEWEB)

    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.)

  14. Tactile and proprioceptive temporal discrimination are impaired in functional tremor.

    Directory of Open Access Journals (Sweden)

    Michele Tinazzi

    Full Text Available In order to obtain further information on the pathophysiology of functional tremor, we assessed tactile discrimination threshold and proprioceptive temporal discrimination motor threshold values in 11 patients with functional tremor, 11 age- and sex-matched patients with essential tremor and 13 healthy controls.Tactile discrimination threshold in both the right and left side was significantly higher in patients with functional tremor than in the other groups. Proprioceptive temporal discrimination threshold for both right and left side was significantly higher in patients with functional and essential tremor than in healthy controls. No significant correlation between discrimination thresholds and duration or severity of tremor was found.Temporal processing of tactile and proprioceptive stimuli is impaired in patients with functional tremor. The mechanisms underlying this impaired somatosensory processing and possible ways to apply these findings clinically merit further research.

  15. Strength stimuli on the quadriceps femoris influences the physiological tremor of the index finger

    CERN Document Server

    Lainez, Miguel J A; Gallach, Jose E; Moras, Gerard; Ranz, Daniel; Toca-Herrera, Jose L

    2008-01-01

    The influence of fatiguing stimuli applied to the quadriceps femoris on the tremor of the index finger on sixteen healthy subjects has been investigated, by measuring the acceleration and the electromyography activity of the extensor digitorum at two different speeds. No significant changes in the basal condition could be measured at 0.52 rad/s. However, at 1.05 rad/s the tremor amplitude (12.23%, p<0.05) and the electromyography activity (20.19%, p<0.05) increased in the time domain. In the frequential domain, the peak associated to the acceleration increased in 26.30% (p<0.05), while the electromiography activity experienced an increase of 81.34% (p<0.05). The largest change in frequency took place in the range 7-17 Hz. The discussion of the results leads to the conclusion that the supraespinal mechanism is responsible for the measured effect.

  16. Seismic tremor and gravity measurements at Inferno Crater Lake, Waimangu Geothermal Field, New Zealand

    Science.gov (United States)

    O'Brien, J. F.; Jolly, A. D.; Fournier, N.; Cole-Baker, J.; Hurst, T.; Roman, D. C.

    2011-12-01

    Volcanic crater lakes are often associated with active hydrothermal systems that induce cyclic behavior in the lake's level, temperature, and chemistry. Inferno Crater Lake, located in the Waimangu geothermal field within the Taupo Volcanic Zone (TVZ) on the North Island of New Zealand exhibits lake level fluctuations of >7m, and temperature fluctuations >40°C with a highly variable periodicity. Seismic and gravity monitoring of Inferno Lake was carried out from December, 2009 - March, 2010 and captured a full cycle of lake fluctuation. Results indicate that this cycle consisted of ~5 smaller fluctuations of ~3m in lake level followed by a larger fluctuation of ~7m. A broadband seismometer recorded strong seismic tremor in the hours leading up to each of the minor and major high stands in lake level. Spectral analysis of the tremor shows dominant frequencies in the range of ~10Hz and a fundamental harmonic frequency located in the 1Hz range. The 1Hz frequency band exhibits gliding spectral lines which increase in frequency at the end of each tremor period. Particle motion analysis of harmonic tremor waveforms indicate a ~100m upward migration of the source location from the onset of tremor until it ceases at the peak of each lake level high stand. Particle motions also indicate an azimuthal migration of the source by ~30° from the overflow outlet region of the lake toward the central vent location during the course of the tremor and lake level increase. Lake water temperature has a direct relationship with lake level and ranges between ~40°C - ~80°C. Gravity fluctuations were also continuously monitored using a Micro-g-LaCoste gPhone relative gravity meter with a 1Hz sampling rate and precision of 1 microgal. These data indicate a direct relationship between lake level and gravity showing a net increase of ~100 microgals between lake level low and high stands. A piezometer located beside the lake indicates an inflow of ground water into the subsoil during

  17. Analysis of nonvolcanic tremor on the San Andreas Fault near Parkfield, CA using U.S. Geological Survey Parkfield Seismic Array

    Science.gov (United States)

    Fletcher, Jon B.; Baker, Lawrence M.

    2010-01-01

    Reports by Nadeau and Dolenc (2005) that tremor had been detected near Cholame Valley spawned an effort to use UPSAR (U. S. Geological Survey Parkfield Seismic Array) to study characteristics of tremor. UPSAR was modified to record three channels of velocity at 40–50 sps continuously in January 2005 and ran for about 1 month, during which time we recorded numerous episodes of tremor. One tremor, on 21 January at 0728, was recorded with particularly high signal levels as well as another episode 3 days later. Both events were very emergent, had a frequency content between 2 and 8 Hz, and had numerous high-amplitude, short-duration arrivals within the tremor signal. Here using the first episode as an example, we discuss an analysis procedure, which yields azimuth and apparent velocity of the tremor at UPSAR. We then provide locations for both tremor episodes. The emphasis here is how the tremor episode evolves. Twelve stations were operating at the time of recording. Slowness of arrivals was determined using cross correlation of pairs of stations; the same method used in analyzing the main shock data from 28 September 2004. A feature of this analysis is that 20 s of the time series were used at a time to calculate correlation; the longer windows resulted in more consistent estimates of slowness, but lower peak correlations. These values of correlation (peaks of about 0.25), however, are similar to that obtained for the S wave of a microearthquake. Observed peaks in slowness were traced back to source locations assumed to lie on the San Andreas fault. Our inferred locations for the two tremor events cluster near the locations of previously observed tremor, south of the Cholame Valley. Tremor source depths are in the 14–24 km range, which is below the seismogenic brittle zone, but above the Moho. Estimates of error do not preclude locations below the Moho, however. The tremor signal is very emergent but contains packets that are several times larger than the

  18. Volcanic gas

    Science.gov (United States)

    McGee, Kenneth A.; Gerlach, Terrance M.

    1995-01-01

    In Roman mythology, Vulcan, the god of fire, was said to have made tools and weapons for the other gods in his workshop at Olympus. Throughout history, volcanoes have frequently been identified with Vulcan and other mythological figures. Scientists now know that the “smoke" from volcanoes, once attributed by poets to be from Vulcan’s forge, is actually volcanic gas naturally released from both active and many inactive volcanoes. The molten rock, or magma, that lies beneath volcanoes and fuels eruptions, contains abundant gases that are released to the surface before, during, and after eruptions. These gases range from relatively benign low-temperature steam to thick hot clouds of choking sulfurous fume jetting from the earth. Water vapor is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide. Other volcanic gases are hydrogen sulfide, hydrochloric acid, hydrogen, carbon monoxide, hydrofluoric acid, and other trace gases and volatile metals. The concentrations of these gas species can vary considerably from one volcano to the next.

  19. Full Wavefield Numerical Simulations of Sub-glacial Seismic Tremor at Vatnajökull Glacier, Iceland

    Science.gov (United States)

    Ying, Yingzi; Eibl, Eva P. S.; Bean, Christopher J.; Vogfjörd, Kristin; Pálsson, Finnur

    2015-04-01

    The volcanic systems, including the central volcanoes Bárðarbunga and Grimsvötn in South-East Iceland lie beneath the Vatnajökull glacier and are covered by up to 700 m of ice. This ice layer inhibits the recording of the seismic signal close to the source and acts as a wave guide, significantly modifying the seismic wavefield. Recordings of local earthquakes or tremor will therefore be modified by a potentially strong and unknown path effect. We tackle this problem with full wavefield numerical simulations, (2D and 3D) using the Spectral Element method. This allows for the introduction of viscoelasticity in the sub-surface geology and captures all wave conversions and scattering. We employ a 3D model of the glacier thickness and subglacial topography and insert a source wavelet at different depths and locations in order to simulate the wavefield recorded at the location of the field seismometers, in the region of Vatnajökull. Furthermore we calculate sensitivity kernels which show us which part of the model creates a specific part of the simulated seismogram, yielding a deeper understanding of tremor seismogram composition. Our findings show that path effects play a very significant role in determining the overall character of the tremor wavefield and must be removed or suppressed in order to gain a better understanding of the tremor source process itself.

  20. The measurement of tremor using a velocity transducer: comparison to simultaneous recordings using transducers of displacement, acceleration and muscle activity.

    Science.gov (United States)

    Norman, K E; Edwards, R; Beuter, A

    1999-10-15

    Precise kinematic measurements of tremor have historically been obtained using accelerometers. However, current technology permits precise measurements in velocity and displacement. The primary advantage of velocity recording is that only one step of integration or differentiation is required for either displacement or acceleration. A method is presented of measuring finger tremor using a laser system that transduces velocity precisely. Measurements of postural finger tremor thus obtained were compared to those simultaneously obtained from a laser system that transduces displacement, from an accelerometer and from surface electromyography (EMG) of the extensor digitorum communis. A range of amplitude and frequency content was obtained by testing control subjects and subjects with Parkinson's disease. The velocity transducer showed excellent correspondence of amplitude and frequency measurement with the displacement transducer. Measures of absolute and relative amplitude correlated well (r > or = 0.96 in amplitude measures in displacement, velocity and acceleration), and high coherence was found throughout the frequency range of interest. Measurements by the accelerometer generally showed poorer correspondence with those of the other instruments. EMG measurements showed good correspondence in some trials but poorer correspondence in others, attributed to the low level of muscle activity required in the task. Precise kinematic measurements appear to be highly sensitive to neuromotor impairment.

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

    NARCIS (Netherlands)

    Helmich, R.C.G.; Hallett, M.; Deuschl, G.; Toni, I.; Bloem, B.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

  2. Observations of two special kinds of tremor at Galeras volcano, Colombia (1989-1991)

    Energy Technology Data Exchange (ETDEWEB)

    Gil Cruz, F. [Observatorio Vulcanologico y Sismologico, Manizales (Colombia)

    1999-06-01

    The paper analyzes two kinds of tremor produced by Galeras volcano in 1988: flute tremor and spasmodic tremor. Spectrum and peak of flute tremor are described. The paper also distinguishes two types of spasmodic tremor on the basis of their spectral characteristics and field observations.

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

    NARCIS (Netherlands)

    Helmich, R.C.G.; Hallett, M.; Deuschl, G.; Toni, I.; Bloem, B.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 altere

  4. Volcanic Catastrophes

    Science.gov (United States)

    Eichelberger, J. C.

    2003-12-01

    The big news from 20th century geophysics may not be plate tectonics but rather the surprise return of catastrophism, following its apparent 19th century defeat to uniformitarianism. Divine miracles and plagues had yielded to the logic of integrating observations of everyday change over time. Yet the brilliant interpretation of the Cretaceous-Tertiary Boundary iridium anomaly introduced an empirically based catastrophism. Undoubtedly, decades of contemplating our own nuclear self-destruction played a role in this. Concepts of nuclear winter, volcanic winter, and meteor impact winter are closely allied. And once the veil of threat of all-out nuclear exchange began to lift, we could begin to imagine slower routes to destruction as "global change". As a way to end our world, fire is a good one. Three-dimensional magma chambers do not have as severe a magnitude limitation as essentially two-dimensional faults. Thus, while we have experienced earthquakes that are as big as they get, we have not experienced volcanic eruptions nearly as great as those preserved in the geologic record. The range extends to events almost three orders of magnitude greater than any eruptions of the 20th century. Such a calamity now would at the very least bring society to a temporary halt globally, and cause death and destruction on a continental scale. At maximum, there is the possibility of hindering photosynthesis and threatening life more generally. It has even been speculated that the relative genetic homogeneity of humankind derives from an evolutionary "bottleneck" from near-extinction in a volcanic cataclysm. This is somewhat more palatable to contemplate than a return to a form of Original Sin, in which we arrived at homogeneity by a sort of "ethnic cleansing". Lacking a written record of truly great eruptions, our sense of human impact must necessarily be aided by archeological and anthropological investigations. For example, there is much to be learned about the influence of

  5. Cosmic signatures in earth's seismic tremor?

    Science.gov (United States)

    Mulargia, Francesco

    2017-01-01

    Even in absence of earthquakes, each site on earth experiences continuous elastic vibrations which are mostly traced to the nonlinear interactions of ocean waves. However, the fine structure of the spectrum at mHz frequencies shows many persistent and highly significant narrow bandwidth peaks in surprising coincidence with solar acoustic eigenmodes. 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 ≳ 10-20, larger than those expected for any known gravitational stellar source. Hence, a gravitational source attribution to the tremor spectral peaks would call for a population of unknown non-luminous sources with well-defined mass-distance ratios.

  6. [Topiramate in the treatment of essential tremor].

    Science.gov (United States)

    Zalialova, Z A; Latypova, G R

    2008-01-01

    Therapeutic efficacy of topiramate in essential tremor (ET) was assessed in comparison with propranolol in two groups which included 24 and 20 patients, respectively, aged from 21 to 83 years (mean age 53 years). Along with clinical examination, a number of scales: Clinical rating scale for tremor, scale of functional disturbances and Visual-analogous scale have been administered. The efficacy of topiramate was comparable to that of propranolol in 83% and 75% cases, respectively. However topiramate has some therapeutic advantages compared to propranolol; it may be prescribed for all clinical forms regardless of sex (its efficacy is higher in women), age and illness duration, both in earlier and later onset, familial and sporadic variants of ET (propranolol is more effective in patients with family history of ET). Moreover, in contrast to propranolol, topiramate may be prescribed to patients with predisposition to arterial hypertension and bradicardia, bronchial spasms of diabetes mellitus and heart rhythm disturbances.

  7. Nonvolcanic tremors in the Mexican subduction zone

    Science.gov (United States)

    Payero, J. S.; Kostoglodov, V.; Mikumo, T.; Perez-Campos, X.; Iglesias, A.; Clayton, R.

    2007-05-01

    Nonvolcanic low frequency tremors (NVT) have been discovered and studied recently in Japan and Cascadia subduction zones and deep beneath the San Andreas Fault. The tremors activity is increasing during so-called silent earthquakes (SQ) in Japan and Cascadia. NVT clusters also migrate following the propagation of the SQ. The origin of the NVT is still unclear. The studies of NVT and SQ in different subduction zones are required to understand the cause for these phenomena. We discovered a number of NVT from daily spectrograms of continuous broad band records at seismic stations of Servicio Seismológico Nacional (SSN) an MASE project. The analyzed data cover a period of 2001-2004 (SSN) when in 2002 a large SQ has occurred in the Guerrero- Oaxaca region, and a steady-state interseismic epoch of 2005 and a new large SQ in 2006 (MASE). NVT occurred in the central part of the Mexican subduction zone (Guerrero) at approximately 200 km from the coast. We can not accurately localize the tremors because of sparse station coverage in 2001-2004. The MASE data of 2005-2006 show that NVT records in Mexico are very similar to those obtained in Cascadia subduction zone. The tremors duration is of 10-60 min, and they appear to travel at S-wave velocities. More than 100 strong NVT were recorded by most of the MASE stations with the epicenters clustered in the narrow band of ~40x150 km to the south of Iguala city and parallel to the coast line. NVT depths are poorly constrained but seem to be less than 40 km deep. We noticed a some increase of NVT activity during the 2001-2002 and 2006 SQs compared with an NVT activity for the "SQ quiet" period of 2003-2004 nevertheless. A lack of NVT for the period of 2-3 months after the SQ is apparent in 2002 and 2006.

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

    Science.gov (United States)

    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.

  9. Multistep prediction of physiological tremor for surgical robotics applications.

    Science.gov (United States)

    Veluvolu, Kalyana C; Tatinati, Sivanagaraja; Hong, Sun-Mog; Ang, Wei Tech

    2013-11-01

    Accurate canceling of physiological tremor is extremely important in robotics-assisted surgical instruments/procedures. The performance of robotics-based hand-held surgical devices degrades in real time due to the presence of phase delay in sensors (hardware) and filtering (software) processes. Effective tremor compensation requires zero-phase lag in filtering process so that the filtered tremor signal can be used to regenerate an opposing motion in real time. Delay as small as 20 ms degrades the performance of human-machine interference. To overcome this phase delay, we employ multistep prediction in this paper. Combined with the existing tremor estimation methods, the procedure improves the overall accuracy by 60% for tremor estimation compared to single-step prediction methods in the presence of phase delay. Experimental results with developed methods for 1-DOF tremor estimation highlight the improvement.

  10. Neurological tremor: sensors, signal processing and emerging applications.

    Science.gov (United States)

    Grimaldi, Giuliana; Manto, Mario

    2010-01-01

    Neurological tremor is the most common movement disorder, affecting more than 4% of elderly people. Tremor is a non linear and non stationary phenomenon, which is increasingly recognized. The issue of selection of sensors is central in the characterization of tremor. This paper reviews the state-of-the-art instrumentation and methods of signal processing for tremor occurring in humans. We describe the advantages and disadvantages of the most commonly used sensors, as well as the emerging wearable sensors being developed to assess tremor instantaneously. We discuss the current limitations and the future applications such as the integration of tremor sensors in BCIs (brain-computer interfaces) and the need for sensor fusion approaches for wearable solutions.

  11. Best-basis analysis of broadband tremor signals

    Directory of Open Access Journals (Sweden)

    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.

  12. Genetics of Parkinson disease and essential tremor.

    Science.gov (United States)

    Wider, Christian; Ross, Owen A; Wszolek, Zbigniew K

    2010-08-01

    Elucidating the genetic background of Parkinson disease and essential tremor is crucial to understand the pathogenesis and improve diagnostic and therapeutic strategies. A number of approaches have been applied including familial and association studies, and studies of gene expression profiles to identify genes involved in susceptibility to Parkinson disease. These studies have nominated a number of candidate Parkinson disease genes and novel loci including Omi/HtrA2, GIGYF2, FGF20, PDXK, EIF4G1 and PARK16. A recent notable finding has been the confirmation for the role of heterozygous mutations in glucocerebrosidase (GBA) as risk factors for Parkinson disease. Finally, association studies have nominated genetic variation in the leucine-rich repeat and Ig containing 1 gene (LINGO1) as a risk for both Parkinson disease and essential tremor, providing the first genetic evidence of a link between the two conditions. Although undoubtedly genes remain to be identified, considerable progress has been achieved in the understanding of the genetic basis of Parkinson disease. This same effort is now required for essential tremor. The use of next-generation high-throughput sequencing and genotyping technologies will help pave the way for future insight leading to advances in diagnosis, prevention and cure.

  13. Accuracy of forecast of mine tremors location

    Energy Technology Data Exchange (ETDEWEB)

    Jan Drzewieck [Central Mining Institute, Katowice (Poland)

    2009-09-15

    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 intensity (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 based on the results of tests and measurements carried out at the Central Mining Institute. 8 refs., 5 figs.

  14. Accuracy of forecast of mine tremors location

    Institute of Scientific and Technical Information of China (English)

    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.

  15. Embarrassment in essential tremor: prevalence, clinical correlates and therapeutic implications.

    Science.gov (United States)

    Louis, Elan D; Rios, Eileen

    2009-08-01

    Embarrassment is a commonly described feature of essential tremor (ET) but has not been the focus of clinical research. To estimate the prevalence, identify susceptible patient groups, and quantify the therapeutic correlates of reported embarrassment. A total of 106 ET cases from a population-based sample and 349 ET cases from a clinical sample were asked, "Does your tremor often embarrass you?" In the clinical sample, the prevalence of embarrassment was high (58.2%). Even in those ET cases with no head tremor and mild arm tremor, nearly one-half (29/61 [47.5%]) reported embarrassment. While the prevalence of embarrassment was lower in the population-based sample, it was not negligible (18.9%). Embarrassment was associated with younger age of onset (p=0.003) and women were nearly twice as likely as men to report embarrassment (OR=1.85, p=0.01). Independent of tremor severity, embarrassment nearly doubled the odds of using tremor medication (OR=1.86, p=0.01). Embarrassment may be a source of disability in ET. Even among clinic patients with mild tremor, nearly one-half reported embarrassment. We identified a number of patient characteristics linked to embarrassment. Embarrassment alone (i.e., independent of tremor severity) was responsible for a doubling of tremor medication usage. The majority of clinical trials do not assess the therapeutic effects of medication on embarrassment. These trials may benefit from scaled assessments of level of embarrassment.

  16. Tremor as observed by the Array of Arrays in Cascadia

    Science.gov (United States)

    Ghosh, A.; Vidale, J. E.; Creager, K. C.

    2010-12-01

    We are capturing the intimate details of tremor activity in Cascadia with 8 small-aperture seismic arrays in northwestern Washington. The Array of Arrays (AoA) focuses on the tremor-active megathrust, including the area we previously imaged with a solo seismic array in 2008 [Ghosh et al., GRL, 2009, 2010]. Each array consists of 10 to 20 three-component sensors recording in continuous mode. Since it became operational in June 2009, the AoA has recorded several minor tremor episodes, and the recent episodic tremor and slip (ETS) event in August 2010. During the ETS event, each array was augmented by 10 additional single-channel, vertical-component sensors. We have already started to analyze seismic data for tremor episodes in July 2009, and March 2010. At each array, we apply a beamforming technique to stack the seismic energy at every 0.2 Hz from 2 to 15 Hz. During active tremor, the arrays show stable slowness, and azimuth over time, and up to 15 Hz energy on vertical channels, and 6 Hz on horizontals, with slowness consistent with the P and S waves respectively (Figure 1). Vidale et al. in this meeting provide a detailed description of a weeklong tremor episode in March 2010. The ETS started early second week of August about 60 km south of our arrays, and in a week or so, migrated along-strike to the north passing directly underneath the arrays. Strong tremor is still active about 50 km north of the arrays as we write this abstract. We will imminently analyze this data, and by the time of AGU, have preliminary results to present. Currently, we are developing an algorithm to focus as many arrays as possible to locate the tremor sources. With fine tremor detection capability and good azimuthal coverage, our AoA will better resolve the various confounding features of tremor spatiotemporal distribution (e.g., tremor patches, bands, streaks, rapid tremor reversals, low frequency earthquakes) that have been recently discovered in Cascadia. The AoA is poised to provide

  17. Towards closed-loop deep brain stimulation: decision tree-based essential tremor patient's state classifier and tremor reappearance predictor.

    Science.gov (United States)

    Shukla, Pitamber; Basu, Ishita; Tuninetti, Daniela

    2014-01-01

    Deep Brain Stimulation (DBS) is a surgical procedure to treat some progressive neurological movement disorders, such as Essential Tremor (ET), in an advanced stage. Current FDA-approved DBS systems operate open-loop, i.e., their parameters are unchanged over time. This work develops a Decision Tree (DT) based algorithm that, by using non-invasively measured surface EMG and accelerometer signals as inputs during DBS-OFF periods, classifies the ET patient's state and then predicts when tremor is about to reappear, at which point DBS is turned ON again for a fixed amount of time. The proposed algorithm achieves an overall accuracy of 93.3% and sensitivity of 97.4%, along with 2.9% false alarm rate. Also, the ratio between predicted tremor delay and the actual detected tremor delay is about 0.93, indicating that tremor prediction is very close to the instant where tremor actually reappeared.

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

    Directory of Open Access Journals (Sweden)

    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.

  19. Characterizing the Relationship of Tremor and Slip during Recent ETS Events in Northern Cascadia using Strainmeters, GPS, and Tremor Observations

    Science.gov (United States)

    Krogstad, R. D.; Schmidt, D. A.

    2014-12-01

    We investigate the relationship between slip and tremor during multiple recent slow slip events in northern Cascadia. While the relationship of geodetically detectable slow slip and nonvolcanic tremor appears to be broadly coincident, the exact spatial and temporal characteristics remain unclear at a finer scale. Typical GPS derived slip distributions tend to be spatially and temporally smoothed and offset slightly updip of tremor distributions. These discrepancies may be real, or they may be a consequence of the resolution of GPS data or an artifact of the inversion methodology. Borehole strainmeters provide additional independent geodetic constraints for characterizing slip, provide greater temporal resolution, and greater precision than GPS. However, various non-tectonic artifacts and other sources of error have limited the number of usable stations and made deriving reliable information from strainmeters during slip events difficult. We utilize strainmeters with low levels of noise and minimal observable artifacts to constrain forward models and to provide additional independent observations in joint geodetic inversions with GPS data. A series of slip distributions are derived by inverting strainmeter and GPS data using the Kalman-filter-based Extended Network Inversion Filter. To compare the tremor distributions to the geodetically derived slip we also construct slip distributions using tremor occurrences as a proxy for localized slip on the plate interface. The magnitude of slip per tremor occurrence is then scaled to best match the observed surface displacements. Separate slip distributions informed by GPS and tremor are then used to predict strain time series. The comparisons between strain predictions and observations produce mixed results. This may indicate that that tremor and slip are not always coincident. This is particularly evident during the Aug. 2010 event, where the peak GPS-derived slip is located in a region with decreased tremor activity

  20. Minimising tremor in a joystick using fuzzy logic

    NARCIS (Netherlands)

    van der Zwaag, B.J.; Corbett, Dan; Jain, Lakhmi; Kappen, H.J.; Duin, R.P.W.; Krose, B.J.A.; Segeth, W.

    We have designed and built a fuzzy logic controller which minimises the effect of Multiple Sclerosis (MS) hand tremors. The aim of our project has been to give people with Multiple Sclerosis better control of an electronic wheelchair by removing tremors from the joystick signal. The system

  1. Capturing hand tremors with a fuzzy logic wheelchair joystick controller

    NARCIS (Netherlands)

    van der Zwaag, B.J.; Corbett, Dan

    1999-01-01

    We have designed and built a fuzzy logic wheelchair controller which minimizes the effect of Multiple Sclerosis and tremors. The aim of our project has been to give people with Multiple Sclerosis better control of an electric wheelchair by removing tremors from the joystick signal. The system interc

  2. Capturing hand tremors with a fuzzy logic wheelchair joystick controller

    NARCIS (Netherlands)

    Zwaag, van der Berend-Jan; Corbett, Dan

    1999-01-01

    We have designed and built a fuzzy logic wheelchair controller which minimizes the effect of Multiple Sclerosis and tremors. The aim of our project has been to give people with Multiple Sclerosis better control of an electric wheelchair by removing tremors from the joystick signal. The system interc

  3. Minimising tremor in a joystick using fuzzy logic

    NARCIS (Netherlands)

    Zwaag, van der Berend-Jan; Corbett, Dan; Jain, Lakhmi

    1999-01-01

    We have designed and built a fuzzy logic controller which minimises the effect of Multiple Sclerosis (MS) hand tremors. The aim of our project has been to give people with Multiple Sclerosis better control of an electronic wheelchair by removing tremors from the joystick signal. The system intercept

  4. Morphometric and functional MRI changes in essential tremor with and without resting tremor.

    Science.gov (United States)

    Nicoletti, Valentina; Cecchi, Paolo; Frosini, Daniela; Pesaresi, Ilaria; Fabbri, Serena; Diciotti, Stefano; Bonuccelli, Ubaldo; Cosottini, Mirco; Ceravolo, Roberto

    2015-03-01

    The etiopathogenesis of essential tremor (ET) is still debated, since the predominant role of circuit dysfunction or brain degenerative changes has not been clearly established. The relationship with Parkinson's Disease (PD) is also controversial and resting tremor occurs in up to 20 % of ET. We investigated the morphological and functional changes associated with ET and we assessed potential differences related to the presence (ET+R) or absence (ET-R) of resting tremor. 32 ET patients (18 ET+R; 14 ET-R) and 12 healthy controls (HC) underwent 3T-MRI protocol including Spoiled Gradient T1-weighted sequence for Voxel-Based Morphometry (VBM) analysis and functional MRI during continuous writing of "8" with right dominant hand. VBM analysis revealed no gray and white matter atrophy comparing ET patients to HC and ET+R to ET-R patients. HC showed a higher BOLD response with respect to ET patients in cerebellum and other brain areas pertaining to cerebello-thalamo-cortical circuit. Between-group activation maps showed higher activation in precentral gyrus bilaterally, right superior and inferior frontal gyri, left postcentral gyrus, superior and inferior parietal gyri, mid temporal and supramarginal gyri, cerebellum and internal globus pallidus in ET-R compared to ET+R patients. Our findings support that the dysfunction of cerebello-thalamo-cortical network is associated with ET in absence of any morphometric changes. The dysfunction of GPi in ET+R patients, consistently with data reported in PD resting tremor, might suggest a potential role of this structure in this type of tremor.

  5. Sensory electrical stimulation for suppression of postural tremor in patients with essential tremor.

    Science.gov (United States)

    Heo, Jae-Hoon; Kim, Ji-Won; Kwon, Yuri; Lee, Sang-Ki; Eom, Gwang-Moon; Kwon, Do-Young; Lee, Chan-Nyeong; Park, Kun-Woo; Manto, Mario

    2015-01-01

    Essential tremor is an involuntary trembling of body limbs in people without tremor-related disease. In previous study, suppression of tremor by sensory electrical stimulation was confirmed on the index finger. This study investigates the effect of sensory stimulation on multiple segments and joints of the upper limb. It denotes the observation regarding the effect's continuity after halting the stimulation. 18 patients with essential tremor (8 men and 10 women) participated in this study. The task, "arms stretched forward", was performed and sensory electrical stimulation was applied on four muscles of the upper limb (Flexor Carpi Radialis, Extensor Carpi Radialis, Biceps Brachii, and Triceps Brachii) for 15 seconds. Three 3-D gyro sensors were used to measure the angular velocities of segments (finger, hand, and forearm) and joints (metacarpophalangeal and wrist joints) for three phases of pre-stimulation (Pre), during-stimulation (On), and 5 minute post-stimulation (P5). Three characteristic variables of root-mean-squared angular velocity, peak power, and peak power frequency were derived from the vector sum of the sensor signals. At On phase, RMS velocity was reduced from Pre in all segments and joints while peak power was reduced from Pre in all segments and joints except for forearm segment. Sensory stimulation showed no effect on peak power frequency. All variables at P5 were similar to those at On at all segments and joints. The decrease of peak power of the index finger was noted by 90% during stimulation from that of On phase, which was maintained even after 5 min. The results indicate that sensory stimulation may be an effective clinical method to treat the essential tremor.

  6. Deterministic properties of mine tremor aftershocks

    CSIR Research Space (South Africa)

    Kgarume, TE

    2010-10-01

    Full Text Available on Deep and High Stress Mining, 6-8 October 2010, Santiago CHILE Deterministic properties of mine tremor aftershocks T.E. Kgarume CSIR Centre for Mining Innovation and University of the Witwatersrand, South Africa S.M. Spottiswoode Consultant, South... : Dyke 7 7 : Span Figure 1 Simplified mine plan showing the main elements of stopes in South African gold mines 5th International Seminar on Deep and High Stress Mining, 6-8 October 2010, Santiago CHILE Table 1 Datasets used in the analysis...

  7. Vocal Tremor: Novel Therapeutic Target for Deep Brain Stimulation

    Directory of Open Access Journals (Sweden)

    Vinod K. Ravikumar

    2016-10-01

    Full Text Available Tremulous voice is characteristically associated with essential tremor, and is referred to as essential vocal tremor (EVT. Current estimates suggest that up to 40% of individuals diagnosed with essential tremor also present with EVT, which is associated with an impaired quality of life. Traditional EVT treatments have demonstrated limited success in long-term management of symptoms. However, voice tremor has been noted to decrease in patients receiving deep brain stimulation (DBS with the targeting of thalamic nuclei. In this study, we describe our multidisciplinary procedure for awake, frameless DBS with optimal stimulation targets as well as acoustic analysis and laryngoscopic assessment to quantify tremor reduction. Finally, we investigate the most recent clinical evidence regarding the procedure.

  8. Tectonic tremor and LFEs on a reverse fault in Taiwan

    Science.gov (United States)

    Aguiar, Ana C.; Chao, Kevin; Beroza, Gregory C.

    2017-07-01

    We compare low-frequency earthquakes (LFEs) from triggered and ambient tremor under the southern Central Range, Taiwan. We apply the PageRank algorithm used by Aguiar and Beroza (2014) that exploits the repetitive nature of the LFEs to find repeating LFEs in both ambient and triggered tremor. We use these repeaters to create LFE templates and find that the templates created from both tremor types are very similar. To test their similarity, we use both interchangeably and find that most of both the ambient and triggered tremor match the LFE templates created from either data set, suggesting that LFEs for both events have a common origin. We locate the LFEs by using local earthquake P wave and S wave information and find that LFEs from triggered and ambient tremor locate to between 20 and 35 km on what we interpret as the deep extension of the Chaochou-Lishan Fault.

  9. Exploring dielectric elastomers as actuators for hand tremor suppression

    Science.gov (United States)

    Kelley, Christopher R.; Kauffman, Jeffrey L.

    2017-04-01

    Pathological tremor results in undesired motion of body parts, with the greatest effect typically occurring in the hands. Since common treatment methods are ineffective in some patients or have risks associated with surgery or side effects, researchers are investigating mechanical means of tremor suppression. This work explores the viability of dielectric elastomers as the actuators in a tremor suppression control system. Dielectric elastomers have many properties similar to human muscle, making them a natural fit for integration into the human biomechanical system. This investigation develops a model of the integrated wrist-actuator system to determine actuator parameters that produce the necessary control authority without significantly affecting voluntary motion. Furthermore, this paper develops a control law for the actuator voltage to increase the effective viscous damping of the system. Simulations show excellent theoretical tremor suppression, demonstrating the potential for dielectric elastomers to suppress tremor while maximizing compatibility between the actuator and the human body.

  10. High prevalence of reported tremor in Klinefelter syndrome.

    Science.gov (United States)

    Harlow, Tanya L; Gonzalez-Alegre, Pedro

    2009-06-01

    Several uncontrolled reports in the literature dating from decades ago suggest a link between Klinefelter syndrome (KS) and essential tremor (ET). Aiming to determine whether this association truly exists, we designed a controlled survey to ascertain the prevalence of reported tremor in KS. We identified subjects with KS through our hospital database and recruited controls among men who were accompanying patients to our Neurology Clinic. The presence of tremor and other variables were recorded employing a previously validated questionnaire. Whereas our control population was slightly older and more frequently reported a family history of tremor, the frequency of reported tremor was significantly higher in subjects with KS than controls with onset at a younger age. In addition, a high proportion of subjects with KS indicated gait imbalance. In summary, our study supports the previously reported association of an ET-like syndrome and KS.

  11. Source mechanisms of volcanic tsunamis.

    Science.gov (United States)

    Paris, Raphaël

    2015-10-28

    Volcanic tsunamis are generated by a variety of mechanisms, including volcano-tectonic earthquakes, slope instabilities, pyroclastic flows, underwater explosions, shock waves and caldera collapse. In this review, we focus on the lessons that can be learnt from past events and address the influence of parameters such as volume flux of mass flows, explosion energy or duration of caldera collapse on tsunami generation. The diversity of waves in terms of amplitude, period, form, dispersion, etc. poses difficulties for integration and harmonization of sources to be used for numerical models and probabilistic tsunami hazard maps. In many cases, monitoring and warning of volcanic tsunamis remain challenging (further technical and scientific developments being necessary) and must be coupled with policies of population preparedness. © 2015 The Author(s).

  12. Volcanic hazard management in dispersed volcanism areas

    Science.gov (United States)

    Marrero, Jose Manuel; Garcia, Alicia; Ortiz, Ramon

    2014-05-01

    Traditional volcanic hazard methodologies were developed mainly to deal with the big stratovolcanoes. In such type of volcanoes, the hazard map is an important tool for decision-makers not only during a volcanic crisis but also for territorial planning. According to the past and recent eruptions of a volcano, all possible volcanic hazards are modelled and included in the hazard map. Combining the hazard map with the Event Tree the impact area can be zoned and defining the likely eruptive scenarios that will be used during a real volcanic crisis. But in areas of disperse volcanism is very complex to apply the same volcanic hazard methodologies. The event tree do not take into account unknown vents, because the spatial concepts included in it are only related with the distance reached by volcanic hazards. The volcanic hazard simulation is also difficult because the vent scatter modifies the results. The volcanic susceptibility try to solve this problem, calculating the most likely areas to have an eruption, but the differences between low and large values obtained are often very small. In these conditions the traditional hazard map effectiveness could be questioned, making necessary a change in the concept of hazard map. Instead to delimit the potential impact areas, the hazard map should show the expected behaviour of the volcanic activity and how the differences in the landscape and internal geo-structures could condition such behaviour. This approach has been carried out in La Palma (Canary Islands), combining the concept of long-term hazard map with the short-term volcanic scenario to show the expected volcanic activity behaviour. The objective is the decision-makers understand how a volcanic crisis could be and what kind of mitigation measurement and strategy could be used.

  13. Neuroimaging essentials in essential tremor: a systematic review.

    Science.gov (United States)

    Sharifi, Sarvi; Nederveen, Aart J; Booij, Jan; van Rootselaar, Anne-Fleur

    2014-01-01

    Essential tremor is regarded to be a disease of the central nervous system. Neuroimaging is a rapidly growing field with potential benefits to both diagnostics and research. The exact role of imaging techniques with respect to essential tremor in research and clinical practice is not clear. A systematic review of the different imaging techniques in essential tremor is lacking in the literature. We performed a systematic literature search combining the terms essential tremor and familial tremor with the following keywords: imaging, mri, vbm, dwi, fmri, pet and spect, both in abbreviated form as well as in full form. We summarize and discuss the quality and the external validity of each study and place the results in the context of existing knowledge regarding the pathophysiology of essential tremor. A total of 48 neuroimaging studies met our search criteria, roughly divided into 19 structural and 29 functional and metabolic studies. The quality of the studies varied, especially concerning inclusion criteria. Functional imaging studies indicated cerebellar hyperactivity during rest and during tremor. The studies also pointed to the involvement of the thalamus, the inferior olive and the red nucleus. Structural studies showed less consistent results. Neuroimaging techniques in essential tremor give insight into the pathophysiology of essential tremor indicating the involvement of the cerebellum as the most consistent finding. GABAergic dysfunction might be a major premise in the pathophysiological hypotheses. Inconsistencies between studies can be partly explained by the inclusion of heterogeneous patient groups. Improvement of scientific research requires more stringent inclusion criteria and application of advanced analysis techniques. Also, the use of multimodal neuroimaging techniques is a promising development in movement disorders research. Currently, the role of imaging techniques in essential tremor in daily clinical practice is limited.

  14. Permanent tremor of Masaya Volcano, Nicaragua: Wave field analysis and source location

    Science.gov (United States)

    MéTaxian, Jean-Philippe; Lesage, Philippe; Dorel, Jacques

    1997-10-01

    The Masaya Volcano, Nicaragua, is a basaltic caldera in a subduction zone. The permanent source of the volcanic tremor was located inside Santiago crater, at the lava lake's position and 400 m below the NE rim, and therefore corresponds to superficial magma activity. We used two tripartite arrays (90 m side), one semicircular array (r=120 m) in 1992, and two semicircular arrays (r=60 m) and a 2500 m long linear array radiating out from the source and on the flank of the crater in 1993. We used both a cross-spectrum method and a correlation method to determine the wave delay time between the reference station and the other stations of an array and to quantify the wave field. Using the delays therefore by intersecting the back azimuth wave directions from the arrays, we could pinpoint the source. Additionally, the correlation coefficients obtained as functions of frequency for the three components of motion confirm the inferred position of the source of tremor. The tremor's wave field is composed of comparable quantities of dispersed Rayleigh and Love surface waves, whose phase velocities lie in the ranges 730-1240 m/s at 2 Hz and 330-550 m/s at 6 Hz. The dispersive phase velocities were inverted to obtain crustal structures with a minimal number of layers. The resulting velocity models are similar for the northern and southern parts of the volcano. After geometrical spreading corrections, Q2Hz=14 and Q3Hz=31 were determined along the northern linear array. The typical low velocities and low Q corresponding to the cone structure and are similar to those of other basaltic volcanoes like Puu Oo, Hawaii, and Klyuchevskoy, Kamchatka.

  15. Cosmic signatures in earth's seismic tremor?

    CERN Document Server

    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...

  16. Investigation of Motor Cortical Plasticity and Corticospinal Tract Diffusion Tensor Imaging in Patients with Parkinsons Disease and Essential Tremor

    Science.gov (United States)

    Chen, Chun-Ming; Duann, Jeng-Ren; Ziemann, Ulf; Chen, Jui-Cheng; Chiou, Shang-Ming; Tsai, Chon-Haw

    2016-01-01

    Parkinson’s disease (PD) and essential tremor (ET) are characterized with motor dysfunctions. Motor circuit dysfunctions can be complementarily investigated by paired associative stimulation (PAS)-induced long-term potentiation (LTP)-like plasticity and diffusion tensor imaging (DTI) of the corticospinal tract (CST). Three groups of twelve subjects with moderate severity PD, ET with intention tremor and healthy controls (HC) were studied. The primary motor cortex (M1) excitability, measured by motor evoked potential (MEP) amplitude and by short-interval and long-interval intracortical inhibition (SICI and LICI) was compared between the three groups before and after PAS. The DTI measures of fractional anisotropy (FA) and mean diffusivity (MD) were acquired. PAS effects and DTI data were simultaneously examined between groups. PAS increased MEP amplitude in HC but not in PD and ET. SICI and LICI were significantly reduced after PAS irrespective of groups. No significant differences of the mean FA and MD were found between groups. There was no significant correlation between the PAS effects and the DTI measures. Findings suggest that both PD and ET with intention tremor have impairment of the associative LTP-like corticospinal excitability change in M1. The microstructure of the CST is not relevant to the deficiency of M1 associative plasticity in PD and ET. PMID:27603204

  17. Volcanic hazard assessment in monogenetic volcanic fields

    OpenAIRE

    Bartolini, Stefania

    2014-01-01

    [eng] One of the most important tasks of modern volcanology, which represents a significant socio-economic implication, is to conduct hazard assessment in active volcanic systems. These volcanological studies are aimed at hazard that allows to constructing hazard maps and simulating different eruptive scenarios, and are mainly addressed to contribute to territorial planning, definition of emergency plans or managing volcanic crisis. The impact of a natural event, as a volcanic eruption, can s...

  18. CHANGES IN PHYSIOLOGICAL TREMOR RESULTING FROM SLEEP DEPRIVATION UNDER CONDITIONS OF INCREASING FATIGUE DURING PROLONGED MILITARY TRAINING

    Directory of Open Access Journals (Sweden)

    A. Tomczak

    2015-01-01

    Full Text Available The aim of the study was to define the changes of the characteristics of physiological postural tremor under conditions of increasing fatigue and lack of sleep during prolonged military training (survival.The subjects of the study were 15 students of the Polish Air Force Academy in Dęblin. The average age was 19.9±1.3 years. During the 36-hour-long continuous military training (survival the subjects were deprived of sleep. Four tremor measurements were carried out for each of the subjects: Day 1 – morning, after rest (measurement 0; Day 2 – morning, after overnight physical exercise (measurement 1; afternoon, after continuous sleep deprivation (measurement 2; Day 3 – morning, after a full night sleep (measurement 3. The accelerometric method using an acceleration measuring kit was applied to analyse tremor. A significant difference between mean values of the index evaluating tremor power in low frequencies L2-4 in measurement 0 and measurement 3 was observed (p<0.01. No significant differences were found in mean values of index L10-20. Mean frequencies F2-4 differed significantly from each other (F 2,42 =4.53; p<0.01. Their values were 2.94±0.11, 2.99±0.9, 2.93±0.07 and 2.91±0.07 for successive measurements. A gradual, significant decrease of F 8-14 was observed (F 2,42 =5.143; p<0.01. Prolonged sleep deprivation combined with performing tasks demanding constant physical effort causes long-lasting (over 24 hours changes of the amplitude of low-frequency tremor changes. This phenomenon may significantly influence psychomotor performance, deteriorating the ability to perform tasks requiring movement precision.

  19. Rest and action tremor in Parkinson's disease: effects of Deep Brain Stimulation

    NARCIS (Netherlands)

    Heida, Tjitske; Wentink, E.C.

    2010-01-01

    One of the cardinal symptoms of Parkinson’s disease is rest tremor. While rest tremor generally disappears during sleep and voluntary movement, action tremor may be triggered by voluntary movement, and may even be more disabling than rest tremor. Deep brain stimulation (DBS) in the subthalamic

  20. Rest and action tremor in Parkinson's disease: effects of Deep Brain Stimulation

    NARCIS (Netherlands)

    Heida, T.; Wentink, E.C.

    2010-01-01

    One of the cardinal symptoms of Parkinson’s disease is rest tremor. While rest tremor generally disappears during sleep and voluntary movement, action tremor may be triggered by voluntary movement, and may even be more disabling than rest tremor. Deep brain stimulation (DBS) in the subthalamic nucle

  1. The distributed somatotopy of tremor: a window into the motor system

    NARCIS (Netherlands)

    Helmich, R.C.G.

    2013-01-01

    The posterior ventrolateral thalamus (VLp) plays a crucial role in Parkinson's tremor and in essential tremor: deep brain stimulation (DBS) of the VLp effectively diminishes both tremor types. Previous research has shown tremor oscillations in the VLp, but the spatial extent and somatotopy of these

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

    Directory of Open Access Journals (Sweden)

    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

  3. Neural correlates of dystonic tremor: a multimodal study of voice tremor in spasmodic dysphonia.

    Science.gov (United States)

    Kirke, Diana N; Battistella, Giovanni; Kumar, Veena; Rubien-Thomas, Estee; Choy, Melissa; Rumbach, Anna; Simonyan, Kristina

    2016-02-03

    Tremor, affecting a dystonic body part, is a frequent feature of adult-onset dystonia. However, our understanding of dystonic tremor pathophysiology remains ambiguous as its interplay with the main co-occurring disorder, dystonia, is largely unknown. We used a combination of functional MRI, voxel-based morphometry and diffusion-weighted imaging to investigate similar and distinct patterns of brain functional and structural alterations in patients with dystonic tremor of voice (DTv) and isolated spasmodic dysphonia (SD). We found that, compared to controls, SD patients with and without DTv showed similarly increased activation in the sensorimotor cortex, inferior frontal (IFG) and superior temporal gyri, putamen and ventral thalamus, as well as deficient activation in the inferior parietal cortex and middle frontal gyrus (MFG). Common structural alterations were observed in the IFG and putamen, which were further coupled with functional abnormalities in both patient groups. Abnormal activation in left putamen was correlated with SD onset; SD/DTv onset was associated with right putaminal volumetric changes. DTv severity established a significant relationship with abnormal volume of the left IFG. Direct patient group comparisons showed that SD/DTv patients had additional abnormalities in MFG and cerebellar function and white matter integrity in the posterior limb of the internal capsule. Our findings suggest that dystonia and dystonic tremor, at least in the case of SD and SD/DTv, are heterogeneous disorders at different ends of the same pathophysiological spectrum, with each disorder carrying a characteristic neural signature, which may potentially help development of differential markers for these two conditions.

  4. Familial orthostatic tremor and essential tremor in two young brothers: A rare entity

    Directory of Open Access Journals (Sweden)

    Kalyan B Bhattacharyya

    2013-01-01

    Full Text Available Orthostatic tremor (OT, is usually a disease of old age and is characterized by quivering movements of the legs during quiet standing or in the state of isometric contraction in the lower limbs. This is relieved on walking or on lying down. It is diagnosed by surface electromyography, particularly over the quadriceps femoris muscles which shows a distinctive frequency of 13 to 18 Hz on standing. Some investigators consider it as a variant of essential tremor (ET and the two conditions often co-exist. The disease is usually non-familial. Two brothers presented with tremor in the lower limbs on standing and on the outstretched hands without any family history. Subsequently, they were proved to be suffering from OT and ET by clinical examination and surface EMG. Simultaneous occurrence of OT and ET in two young brothers without any family history in the previous generation has not been described before and they also appeared at a much earlier age than what is described in the literature.

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

    Science.gov (United States)

    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).

  6. Prominent Bilateral Hand Tremor in Hashimoto's Encephalopathy: A Video Demonstration.

    Science.gov (United States)

    Ramcharan, Kanterpersad; Hosein, Nadeem; Teelucksingh, Joel David; Rampersad, Fidel; Teelucksingh, Surujpal

    2016-01-01

    Hashimoto's encephalopathy often presents with neuropsychiatric manifestations including seizures and movement disorders. We describe a patient who presented with bilateral hand tremor and mild cognitive defects that fulfilled the criteria for a diagnosis of Hashimoto's encephalopathy. There was a rapid response to glucocorticoid therapy with relapse following treatment withdrawal. Recently published clinical criteria for the diagnosis of Hashimoto's encephalopathy include seizures, myoclonus, hallucinations, or stroke-like episodes but do not include tremor. Our case had mild cognitive dysfunction and a coarse tremor as the predominant clinical features, which probably represent mild disease.

  7. Evaluation of a screening instrument for essential tremor

    DEFF Research Database (Denmark)

    Lorenz, Delia; Papengut, Frank; Frederiksen, Henrik

    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....... Definite or probable ET was diagnosed in 104 patients, possible in 86 and other tremors in 98 patients. The sensitivity of the screening instrument was 70.5%, the positive predictive value was 64.9%, the specificity was 68.2%, and the negative predictive value was 73.5%. Tremor severity correlated...

  8. Slow slip events and seismic tremor at circum-Pacific subduction zones

    Science.gov (United States)

    Schwartz, Susan Y.; Rokosky, Juliana M.

    2007-09-01

    It has been known for a long time that slip accompanying earthquakes accounts for only a fraction of plate tectonic displacements. However, only recently has a fuller spectrum of strain release processes, including normal, slow, and silent earthquakes (or slow slip events) and continuous and episodic slip, been observed and generated by numerical simulations of the earthquake cycle. Despite a profusion of observations and modeling studies the physical mechanism of slow slip events remains elusive. The concurrence of seismic tremor with slow slip episodes in Cascadia and southwestern Japan provides insight into the process of slow slip. A perceived similarity between subduction zone and volcanic tremor has led to suggestions that slow slip involves fluid migration on or near the plate interface. Alternatively, evidence is accumulating to support the notion that tremor results from shear failure during slow slip. Global observations of the location, spatial extent, magnitude, duration, slip rate, and periodicity of these aseismic slip transients indicate significant variation that may be exploited to better understand their generation. Most slow slip events occur just downdip of the seismogenic zone, consistent with rate- and state-dependent frictional modeling that requires unstable to stable transitional properties for slow slip generation. At a few convergent margins the occurrence of slow slip events within the seismogenic zone makes it highly likely that transitions in frictional properties exist there and are the loci of slow slip nucleation. Slow slip events perturb the surrounding stress field and may either increase or relieve stress on a fault, bringing it closer to or farther from earthquake failure, respectively. This paper presents a review of slow slip events and related seismic tremor observed at plate boundaries worldwide, with a focus on circum-Pacific subduction zones. Trends in global observations of slow slip events suggest that (1) slow slip is a

  9. Amplitudes, acquisition and imaging

    Energy Technology Data Exchange (ETDEWEB)

    Bloor, Robert

    1998-12-31

    Accurate seismic amplitude information is important for the successful evaluation of many prospects and the importance of such amplitude information is increasing with the advent of time lapse seismic techniques. It is now widely accepted that the proper treatment of amplitudes requires seismic imaging in the form of either time or depth migration. A key factor in seismic imaging is the spatial sampling of the data and its relationship to the imaging algorithms. This presentation demonstrates that acquisition caused spatial sampling irregularity can affect the seismic imaging and perturb amplitudes. Equalization helps to balance the amplitudes, and the dealing strategy improves the imaging further when there are azimuth variations. Equalization and dealiasing can also help with the acquisition irregularities caused by shot and receiver dislocation or missing traces. 2 refs., 2 figs.

  10. Laboratory triggering of stick-slip events by oscillatory loading in the presence of pore fluid with implications for physics of tectonic tremor

    Science.gov (United States)

    Bartlow, Noel M.; Lockner, David A.; Beeler, Nicholas M.

    2012-01-01

    The physical mechanism by which the low-frequency earthquakes (LFEs) that make up portions of tectonic (also called non-volcanic) tremor are created is poorly understood. In many areas of the world, tectonic tremor and LFEs appear to be strongly tidally modulated, whereas ordinary earthquakes are not. Anomalous seismic wave speeds, interpreted as high pore fluid pressure, have been observed in regions that generate tremor. Here we build upon previous laboratory studies that investigated the response of stick-slip on artificial faults to oscillatory, tide-like loading. These previous experiments were carried out using room-dry samples of Westerly granite, at one effective stress. Here we augment these results with new experiments on Westerly granite, with the addition of varying effective stress using pore fluid at two pressures. We find that raising pore pressure, thereby lowering effective stress can significantly increase the degree of correlation of stick-slip to oscillatory loading. We also find other pore fluid effects that become important at higher frequencies, when the period of oscillation is comparable to the diffusion time of pore fluid into the fault. These results help constrain the conditions at depth that give rise to tidally modulated LFEs, providing confirmation of the effective pressure law for triggering and insights into why tremor is tidally modulated while earthquakes are at best only weakly modulated.

  11. Essential Tremor (ET): Coping Tips for Everyday Living

    Science.gov (United States)

    ... several marathons each year, raising funds and awareness. ET is a life-altering condition that makes everyday ... tremor. In order to assist people who have ET in continuing to live full, meaningful lives, the ...

  12. Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS)

    Science.gov (United States)

    ... a patient may be under the care of multiple or varying specialists. These include but are not limited to: Neurologists (for tremor, ataxia, memory loss) Psychiatrists (for personality change, depression, mood disorders) Psychologists (for cognitive impairment) Movement disorders specialists (for ...

  13. Tremor in workers with low exposure to metallic mercury

    Energy Technology Data Exchange (ETDEWEB)

    Verberk, M.M.; Salle, H.J.A.; Kemper, C.H.

    1986-09-01

    In a fluorescent lamp production factory, a newly developed lightweight balance-tremormeter was used to measure postural tremor of the finger in 21 workers (ages 28 to 61) exposed for 0.5-19 yr to metallic mercury. In addition, tremor was measured in an indirect way by means of a hole-tremormeter. The excretion of mercury in urine was 9-53 (average 20) ..mu..mol/mol creatinine. With increasing mercury excretion, the following parameters increased: the acceleration of the tremor, the contribution of the neuromuscular component (8-12 Hz) to the power spectrum of the acceleration, the width of the power-spectrum and the score on the hole-tremormeter. The study indicates that exposure to metallic mercury below the current TLV (50 ..mu..g/m/sup 3/) may increase the tremor of the finger.

  14. Palatal tremor after lithium and carbamazepine use: a case report

    Directory of Open Access Journals (Sweden)

    Kuruvilla Anju

    2010-06-01

    Full Text Available Abstract Introduction Palatal tremor, characterized by rhythmic contractions of the soft palate, can occur secondary to pathology in the dentato-rubro-olivary pathway, or in the absence of such structural lesions. Its pathogenesis is only partially understood. We describe a case of probable drug-induced palatal tremor. Case presentation A 27-year-old Indian man had taken carbamazepine and lithium for 7 years for the treatment of a manic episode. He presented with a one-year history of bilateral rhythmic oscillations of his soft palate and tremors of his tongue. There were no other abnormalities detected from his examination or after detailed investigation. Conclusion Palatal tremors may result from medication used in the treatment of psychiatric disorders.

  15. Chin tremor in full-term neonate after hypoxia

    Directory of Open Access Journals (Sweden)

    Mônica Ayres de Araújo Scattolin

    Full Text Available CONTEXT: Newborns may present a range of motor phenomena that are not epileptic in nature. Chin tremor is an unusual movement disorder that typically starts in early childhood and may be precipitated by stress and emotion. Its pathophysiology has not been fully elucidated. CASE REPORT: We describe a full-term newborn that, immediately after neonatal anoxia, presented body and chin tremors that were unresponsive to anti-epileptic drugs. Subsequent neurological evaluation revealed signs of pyramidal tract damage and chin tremor triggered by percussion and crying. We discuss the hypothesis that the anatomopathological abnormality may lie at the level of the higher cortical centers or midbrain. CONCLUSIONS: Further studies are needed in order to gain greater comprehension of neonatal tremors. Recognition of the various etiological possibilities and consequent management of treatable causes is essential for care optimization.

  16. Voluntary driven elbow orthosis with speed controlled tremor suppression

    Directory of Open Access Journals (Sweden)

    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

  17. Surface-wave potential for triggering tectonic (nonvolcanic) tremor

    Science.gov (United States)

    Hill, D.P.

    2010-01-01

    Source processes commonly posed to explain instances of remote dynamic triggering of tectonic (nonvolcanic) tremor by surface waves include frictional failure and various modes of fluid activation. The relative potential for Love- and Rayleigh-wave dynamic stresses to trigger tectonic tremor through failure on critically stressed thrust and vertical strike-slip faults under the Coulomb-Griffith failure criteria as a function of incidence angle is anticorrelated over the 15- to 30-km-depth range that hosts tectonic tremor. Love-wave potential is high for strike-parallel incidence on low-angle reverse faults and null for strike-normal incidence; the opposite holds for Rayleigh waves. Love-wave potential is high for both strike-parallel and strike-normal incidence on vertical, strike-slip faults and minimal for ~45?? incidence angles. The opposite holds for Rayleigh waves. This pattern is consistent with documented instances of tremor triggered by Love waves incident on the Cascadia mega-thrust and the San Andreas fault (SAF) in central California resulting from shear failure on weak faults (apparent friction, ????? 0.2). However, documented instances of tremor triggered by surface waves with strike-parallel incidence along the Nankai megathrust beneath Shikoku, Japan, is associated primarily with Rayleigh waves. This is consistent with the tremor bursts resulting from mixed-mode failure (crack opening and shear failure) facilitated by near-lithostatic ambient pore pressure, low differential stress, with a moderate friction coefficient (?? ~ 0.6) on the Nankai subduction interface. Rayleigh-wave dilatational stress is relatively weak at tectonic tremor source depths and seems unlikely to contribute significantly to the triggering process, except perhaps for an indirect role on the SAF in sustaining tremor into the Rayleigh-wave coda that was initially triggered by Love waves.

  18. Maximal force and tremor changes across the menstrual cycle.

    Science.gov (United States)

    Tenan, Matthew S; Hackney, Anthony C; Griffin, Lisa

    2016-01-01

    Sex hormones have profound effects on the nervous system in vitro and in vivo. The present study examines the effect of the menstrual cycle on maximal isometric force (MVC) and tremor during an endurance task. Nine eumenorrheic females participated in five study visits across their menstrual cycle. In each menstrual phase, an MVC and an endurance task to failure were performed. Tremor across the endurance task was quantified as the coefficient of variation in force and was assessed in absolute time and relative percent time to task failure. MVC decreases 23% from ovulation to the mid luteal phase of the menstrual cycle. In absolute time, the mid luteal phase has the highest initial tremor, though the early follicular phase has substantially higher tremor than other phases after 150 s of task performance. In relative time, the mid luteal phase has the highest level of tremor throughout the endurance task. Both MVC and tremor during an endurance task are modified by the menstrual cycle. Performance of tasks and sports which require high force and steadiness to exhaustion may be decreased in the mid luteal phase compared to other menstrual phases.

  19. Real topological string amplitudes

    Science.gov (United States)

    Narain, K. S.; Piazzalunga, N.; Tanzini, A.

    2017-03-01

    We discuss the physical superstring correlation functions in type I theory (or equivalently type II with orientifold) that compute real topological string amplitudes. We consider the correlator corresponding to holomorphic derivative of the real topological amplitude G_{χ } , at fixed worldsheet Euler characteristic χ. This corresponds in the low-energy effective action to N=2 Weyl multiplet, appropriately reduced to the orientifold invariant part, and raised to the power g' = -χ + 1. We show that the physical string correlator gives precisely the holomorphic derivative of topological amplitude. Finally, we apply this method to the standard closed oriented case as well, and prove a similar statement for the topological amplitude F_g.

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

    Science.gov (United States)

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

    2012-11-01

    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 also involved in many other tremors. The purpose of this review is to integrate these clinical and pathophysiological features of tremor in Parkinson's disease. We first describe clinical and pathological differences between tremor-dominant and non-tremor Parkinson's disease subtypes, and then summarize recent studies on the pathophysiology of tremor. We also discuss a newly proposed 'dimmer-switch model' that explains tremor as resulting from the combined actions of two circuits: the basal ganglia that trigger tremor episodes and the cerebello-thalamo-cortical circuit that produces the tremor. Finally, we address several important open questions: why resting tremor stops during voluntary movements, why it has a variable response to dopaminergic treatment, why it indicates a benign Parkinson's disease subtype and why its expression decreases with disease progression.

  1. Avaliação vestibular no tremor essencial Vestibular evaluation in the essential tremor

    Directory of Open Access Journals (Sweden)

    Bianca Simone Zeigelboim

    2008-01-01

    Full Text Available TEMA: o tremor essencial é familial em cerca de 50% dos casos, com uma herança autossômica, possui início insidioso e é lentamente progressivo. PROCEDIMENTOS: avaliou-se no Setor de Otoneurologia de um Hospital Particular em fevereiro de 2007, uma paciente do sexo feminino, branca, 59 anos, casada, artista plástica, com história de tremor na cabeça desde os dois anos de idade (sic. A paciente relata queixa de tontura há vários meses de origem súbita sem acompanhamento de náusea e/ou queda. Nega perda de força muscular e formigamento em membros superiores e inferiores, rebaixamento da acuidade auditiva e zumbido. A paciente relata que um de seus filhos possuiu tremor nas mãos há dois anos e avós maternos e paternos com Parkinson. Realizaram-se os seguintes procedimentos: anamnese, inspeção otológica e avaliação vestibular por meio da vectoeletronistagmografia. RESULTADOS: observaram-se os seguintes achados ao exame vestibular: nistagmo de posicionamento com características centrais, nistagmo espontâneo presente com os olhos abertos, nistagmo semi-espontâneo do tipo múltiplo e hiper-reflexia em valor absoluto à prova calórica 20ºC (OD e OE. CONCLUSÃO: o exame vestibular mostrou-se sensível e importante para captar alterações em provas que sugerissem envolvimento do sistema nervoso central.BACKGROUND: essential tremors are family-related in about 50% of the cases with an autosomal inheritance and they register an insidious beginning with a slow progression. PROCEDURE: a 59 year old, white female patient, married and whose occupation is a plastic artist with a history of head tremors since she was two years (sic old was evaluated in the Otoneurology sector of a private hospital, during the period from February 2007. The patient had been complaining of dizziness from unknown origin for several months without accompanying nausea and/or falls. She denied any loss of muscular strength or tingling in her upper and lower

  2. Designing a hand rest tremor dynamic vibration absorber using H{sub 2} optimization method

    Energy Technology Data Exchange (ETDEWEB)

    Rahnavard, Mostafa; Dizaji, Ahmad F. [Tehran University, Tehran (Iran, Islamic Republic of); Hashemi, Mojtaba [Amirkabir University, Tehran (Iran, Islamic Republic of); Faramand, Farzam [Sharif University, Tehran (Iran, Islamic Republic of)

    2014-05-15

    An optimal single DOF dynamic absorber is presented. A tremor has a random nature and then the system is subjected to a random excitation instead of a sinusoidal one; so the H{sub 2} optimization criterion is probably more desirable than the popular H{sub ∞} optimization method and was implemented in this research. The objective of H{sub 2} optimization criterion is to reduce the total vibration energy of the system for overall frequencies. An objective function, considering the elbow joint angle, θ {sub 2}, tremor suppression as the main goal, was selected. The optimization was done by minimization of this objective function. The optimal system, including the absorber, performance was analyzed in both time and frequency domains. Implementing the optimal absorber, the frequency response amplitude of θ{sub 2} was reduced by more than 98% and 80% at the first and second natural frequencies of the primary system, respectively. A reduction of more than 94% and 78%, was observed for the shoulder joint angle, θ{sub 1}. The objective function also decreased by more than 46%. Then, two types of random inputs were considered. For the first type, θ{sub 1} and θ {sub 2} revealed 60% and 39% reduction in their rms values, whereas for the second type, 33% and 50% decrease was observed.

  3. Depressive symptoms can amplify embarrassment in essential tremor.

    Science.gov (United States)

    Louis, Elan D; Cosentino, Stephanie; Huey, Edward D

    2016-01-01

    Embarrassment can be a considerable problem for patients with essential tremor (ET) and is a major motivator for treatment. Depression is also a common feature of ET; as many as 35 % of patients report moderate to severe depressive symptoms. Our goal was to assess the associations between these motor and psychosocial factors (tremor, depression, embarrassment) in ET, with a particular interest in more fully assessing the possible association between depression and embarrassment. Ninety one ET cases (age 70.4 ± 12.8 years) enrolled in a prospective, clinical-epidemiological study. Depressive symptoms were assessed with the Center for Epidemiological Studies Depression Scale (CESD-10, 0-30 [maximum]), embarrassment, with the Essential Tremor Embarrassment Assessment (ETEA, 0-70 [maximum]), and action tremor, with a detailed in-person neurological examination. Higher CESD-10 score was significantly associated with higher ETEA score (p = 0.005), but not with increasing tremor severity (p = 0.94). In stratified analyses, cases with no or minimal depressive symptoms had the lowest ETEA scores, cases with moderate depressive symptoms had intermediate ETEA scores, and cases with severe depressive symptoms had the highest ETEA scores (p = 0.01). Furthermore, at each level of tremor severity, cases with more depressive symptoms had more embarrassment. Depressive symptoms seem to be more than a secondary response to the tremor in ET; they seem to amplify the level of embarrassment and, in addition to their own importance, seem to be a driver of other important clinical outcomes. Earlier treatment of depressive symptoms in ET patients could lessen the burden of secondary embarrassment.

  4. Protostring scattering amplitudes

    Science.gov (United States)

    Thorn, Charles B.

    2016-11-01

    We calculate some tree-level scattering amplitudes for a generalization of the protostring, which is a novel string model implied by the simplest string bit models. These bit models produce a light-cone world sheet which supports s integer moded Grassmann fields. In the generalization we supplement this Grassmann world-sheet system with d =24 -s transverse coordinate world-sheet fields. The protostring corresponds to s =24 and the bosonic string to s =0 . The interaction vertex is a simple overlap with no operator insertions at the break/join point. Assuming that s is even we calculate the multistring scattering amplitudes by bosonizing the Grassmann fields, each pair equivalent to one compactified bosonic field, and applying Mandelstam's interacting string formalism to a system of s /2 compactified and d uncompactified bosonic world-sheet fields. We obtain all amplitudes for open strings with no oscillator excitations and for closed strings with no oscillator excitations and zero winding number. We then study in detail some simple special cases. Multistring processes with maximal helicity violation have much simpler amplitudes. We also specialize to general four-string amplitudes and discuss their high energy behavior. Most of these models are not covariant under the full Lorentz group O (d +1 ,1 ). The exceptions are the bosonic string whose Lorentz group is O (25 ,1 ) and the protostring whose Lorentz group is O (1 ,1 ). The models in between only enjoy an O (1 ,1 )×O (d ) spacetime symmetry.

  5. Protostring Scattering Amplitudes

    CERN Document Server

    Thorn, Charles B

    2016-01-01

    We calculate some tree level scattering amplitudes for a generalization of the protostring, which is a novel string model implied by the simplest string bit models. These bit models produce a lightcone worldsheet which supports $s$ integer moded Grassmann fields. In the generalization we supplement this Grassmann worldsheet system with $d=24-s$ transverse coordinate worldsheet fields. The protostring corresponds to $s=24$ and the bosonic string to $s=0$. The interaction vertex is a simple overlap with no operator insertions at the break/join point. Assuming that $s$ is even we calculate the multi-string scattering amplitudes by bosonizing the Grassmann fields, each pair equivalent to one compactified bosonic field, and applying Mandelstam's interacting string formalism to a system of $s/2$ compactified and $d$ uncompactified bosonic worldsheet fields. We obtain all amplitudes for open strings with no oscillator excitations and for closed strings with no oscillator excitations and zero winding number. We then ...

  6. The distributed somatotopy of tremor: a window into the motor system.

    Science.gov (United States)

    Helmich, Rick C

    2013-03-01

    The posterior ventrolateral thalamus (VLp) plays a crucial role in Parkinson's tremor and in essential tremor: deep brain stimulation (DBS) of the VLp effectively diminishes both tremor types. Previous research has shown tremor oscillations in the VLp, but the spatial extent and somatotopy of these oscillations remained unclear. In this issue of Experimental Neurology, Pedrosa and colleagues measured neuro-muscular coherence at multiple sites in the VLp of patients with essential tremor and Parkinson's disease using implanted DBS electrodes (Pedrosa et al., 2012). They found multiple tremor clusters within the VLp, with spatially distinct tremor clusters for antagonistic muscles, and in many patients also multiple distinct tremor clusters for a single muscle. Interestingly, this group previously showed similar effects for the STN in tremulous Parkinson's disease (Reck et al., 2009, 2010). Together, these studies suggest that the distribution of tremor clusters is a general organizational principle of tremor, being present in two different tremor pathologies, and in two different nodes of the motor system. The presence of multiple tremor clusters also fits with the distributed somatotopy of the healthy motor system. Therefore, a further conclusion of this study could be that tremor is caused by aberrant synchronization within an otherwise healthy network, brought about by different pathophysiological neural triggers.

  7. Heterogeneity of Monosymptomatic Resting Tremor in a Prospective Study: Clinical Features, Electrophysiological Test, and Dopamine Transporter Positron Emission Tomography

    Institute of Scientific and Technical Information of China (English)

    Hua-Guang Zheng; Rong Zhang; Xin Li; Fang-Fei Li; Ya-Chen Wang; Xue-Mei Wang; Ling-Long Lu

    2015-01-01

    Background:The relationship between monosymptomatic resting tremor (mRT) and Parkinson's disease (PD) remains controversial.In this study,we aimed to assess the function ofpresynaptic dopaminergic neurons in patients with mRT by dopamine transporter positron emission tomography (DAT-PET) and to evaluate the utility of clinical features or electrophysiological studies in differential diagnosis.Methods:Thirty-three consecutive patients with mRT were enrolled prospectively.The Unified Parkinson's Disease Rating Scale and electromyography were tested before DAT-PET.Striatal asymmetry index (SAI) was calculated,and a normal DAT-PET was defined as a SAI of <15%.Scans without evidence of dopaminergic deficits (SWEDDs) were diagnosed in patients with a subsequent normal DAT-PET and structural magnetic resonance imaging.Results:Twenty-eight mRT patients with a significant reduction in uptake of DAT binding in the striatum were diagnosed with PD,while the remained 5 with a normal DAT-PET scan were SWEDDs.As for UPRDS,the dressing and hygiene score,walking in motor experiences of daily living (Part Ⅱ) and motor examination (Part Ⅲ) were significant different between two groups (P < 0.05 andP< 0.01,respectively).Bilateral tremor was more frequent in the SWEDDs group (P < 0.05).The frequency of resting tremor and the amplitude of postural tremor tend to be higher in the SWEDDs group (P =0.08 and P =0.05,respectively).Conclusions:mRT is heterogeneous in presynaptic nigrostriatal dopaminergic degeneration,which can be determined by DAT-PET brain imaging.Clinical and electrophysiological features may provide clues to distinguish PD from SWEDDs.

  8. Automatic landslides detection on Stromboli volcanic Island

    Science.gov (United States)

    Silengo, Maria Cristina; Delle Donne, Dario; Ulivieri, Giacomo; Cigolini, Corrado; Ripepe, Maurizio

    2016-04-01

    Landslides occurring in active volcanic islands play a key role in triggering tsunami and other related risks. Therefore, it becomes vital for a correct and prompt risk assessment to monitor landslides activity and to have an automatic system for a robust early-warning. We then developed a system based on a multi-frequency analysis of seismic signals for automatic landslides detection occurring at Stromboli volcano. We used a network of 4 seismic 3 components stations located along the unstable flank of the Sciara del Fuoco. Our method is able to recognize and separate the different sources of seismic signals related to volcanic and tectonic activity (e.g. tremor, explosions, earthquake) from landslides. This is done using a multi-frequency analysis combined with a waveform patter recognition. We applied the method to one year of seismic activity of Stromboli volcano centered during the last 2007 effusive eruption. This eruption was characterized by a pre-eruptive landslide activity reflecting the slow deformation of the volcano edifice. The algorithm is at the moment running off-line but has proved to be robust and efficient in picking automatically landslide. The method provides also real-time statistics on the landslide occurrence, which could be used as a proxy for the volcano deformation during the pre-eruptive phases. This method is very promising since the number of false detections is quite small (landslide increases. The final aim will be to apply this method on-line and for a real-time automatic detection as an improving tool for early warnings of tsunami-genic landslide activity. We suggest that a similar approach could be also applied to other unstable non-volcanic also slopes.

  9. A course in amplitudes

    Science.gov (United States)

    Taylor, Tomasz R.

    2017-05-01

    This a pedagogical introduction to scattering amplitudes in gauge theories. It proceeds from Dirac equation and Weyl fermions to the two pivot points of current developments: the recursion relations of Britto, Cachazo, Feng and Witten, and the unitarity cut method pioneered by Bern, Dixon, Dunbar and Kosower. In ten lectures, it covers the basic elements of on-shell methods.

  10. Altered Functional Connectivity in Essential Tremor

    Science.gov (United States)

    Benito-León, Julián; Louis, Elan D.; Romero, Juan Pablo; Hernández-Tamames, Juan Antonio; Manzanedo, Eva; Álvarez-Linera, Juan; Bermejo-Pareja, Félix; Posada, Ignacio; Rocon, Eduardo

    2015-01-01

    Abstract Essential tremor (ET) has been associated with a spectrum of clinical features, with both motor and nonmotor elements, including cognitive deficits. We employed resting-state functional magnetic resonance imaging (fMRI) to assess whether brain networks that might be involved in the pathogenesis of nonmotor manifestations associated with ET are altered, and the relationship between abnormal connectivity and ET severity and neuropsychological function. Resting-state fMRI data in 23 ET patients (12 women and 11 men) and 22 healthy controls (HC) (12 women and 10 men) were analyzed using independent component analysis, in combination with a “dual-regression” technique, to identify the group differences of resting-state networks (RSNs) (default mode network [DMN] and executive, frontoparietal, sensorimotor, cerebellar, auditory/language, and visual networks). All participants underwent a neuropsychological and neuroimaging session, where resting-state data were collected. Relative to HC, ET patients showed increased connectivity in RSNs involved in cognitive processes (DMN and frontoparietal networks) and decreased connectivity in the cerebellum and visual networks. Changes in network integrity were associated not only with ET severity (DMN) and ET duration (DMN and left frontoparietal network), but also with cognitive ability. Moreover, in at least 3 networks (DMN and frontoparietal networks), increased connectivity was associated with worse performance on different cognitive domains (attention, executive function, visuospatial ability, verbal memory, visual memory, and language) and depressive symptoms. Further, in the visual network, decreased connectivity was associated with worse performance on visuospatial ability. ET was associated with abnormal brain connectivity in major RSNs that might be involved in both motor and nonmotor symptoms. Our findings underscore the importance of examining RSNs in this population as a biomarker of disease. PMID:26656325

  11. A new familial disease of saccadic oscillations and limb tremor provides clues to mechanisms of common tremor disorders.

    Science.gov (United States)

    Shaikh, Aasef G; Miura, Kenichiro; Optican, Lance M; Ramat, Stefano; Leigh, R John; Zee, David S

    2007-11-01

    Tremor disorders pose fundamental questions about disease mechanisms, and challenges to successful neurotherapeutics: What causes motor circuits to oscillate in disorders in which the central nervous system otherwise seems normal? How does inheritance 'determine' the clinical phenotype in familial tremor disorders? Here, we address these questions. Analogies between the neural circuits controlling rapid eye movements (saccades) and those controlling limb movements allow us to translate the interpretations from the saccadic systems to the limb movement system. Moreover, the relatively well understood neurophysiology of the ocular motor system offers a unique opportunity to test specific hypotheses about normal and abnormal motor control of both eye and limb movements. We describe a new familial disorder--'micro-saccadic oscillations and limb tremor (microSOLT)'--in a mother and daughter who had tiny saccadic oscillations of the eyes and tremor of the hands. This unique oscillatory movement disorder resembles other common tremor disorders (such as essential tremor) that occur in patients who have an otherwise normally functioning central nervous system. We hypothesize that microSOLT is caused by an inherited abnormality that results in abnormal membrane properties causing reduced external inhibition in the premotor neurons that generate the high-frequency discharge (burst) for saccades and for ballistic limb movements. To test this hypothesis, we recorded hand tremor and eye movements in two patients with microSOLT and particularly during natural circumstances when inhibition of the premotor saccadic burst neurons is removed (e.g. eye closure). We then simulated a conductance-based model for the premotor commands which included excitatory and reciprocally inhibitory burst neurons. The structure of this physiologically realistic model was based upon known cell types and anatomical connections in the brainstem (for saccades) and the thalamus (for limb movements). The

  12. Time-frequency scale decomposition of tectonic tremor signals for space-time reconstruction of tectonic tremor sources

    Science.gov (United States)

    Poiata, N.; Satriano, C.; Vilotte, J. P.; Bernard, P.; Obara, K.

    2015-12-01

    Seismic radiation associated with transient deformations along the faults and subduction interfaces encompasses a variety of events, i.e., tectonic tremors, low-frequency earthquakes (LFE), very low-frequency earthquakes (VLFs), and slow-slip events (SSE), with a wide range of seismic moment and characteristic durations. Characterizing in space and time the complex sources of these slow earthquakes, and their relationship with background seismicity and large earthquakes generation, is of great importance for understanding the physics and mechanics of the processes of active deformations along the plate interfaces. We present here first developments towards a methodology for: (1) extracting the different frequency and scale components of observed tectonic tremor signal, using advanced time-frequency and time-scale signal representation such as Gabor transform scheme based on, e.g. Wilson bases or Modified Discrete Cosine Transform (MDCT) bases; (2) reconstructing their corresponding potential sources in space and time, using the array method of Poiata et al. (2015). The methodology is assessed using a dataset of tectonic tremor episodes from Shikoku, Japan, recorded by the Hi-net seismic network operated by NIED. We illustrate its performance and potential in providing activity maps - associated to different scale-components of tectonic tremors - that can be analyzed statistically to improve our understanding of tremor sources and scaling, as well as their relation with the background seismicity.

  13. Dynamic Variability of Isometric Action Tremor in Precision Pinching

    Directory of Open Access Journals (Sweden)

    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.

  14. Continental crust anisotropy measurements from tectonic tremor in Cascadia

    Science.gov (United States)

    Huesca-Pérez, Eduardo; Ortega, Roberto; Valenzuela, Raúl W.

    2017-05-01

    We present new observations of crustal anisotropy in the southern Cascadia fore arc from tectonic tremor. The abundance of tremor activity in Oregon and northern California during slow-slip events offers an enormous amount of information with which to measure and analyze anisotropy in the upper brittle continental crust. To accomplish this, we performed analyses of wave polarization and shear wave splitting of tectonic tremor signals by using three component broadband seismic stations. The splitting times range between 0.11 and 0.32 s and are consistent with typical values observed in the continental crust. Fast polarization azimuths are, in general, margin parallel and trend N-S, which parallels the azimuths of the maximum compressive stresses observed in this region. This pattern is likely to be controlled by the stress field. Comparatively, the anisotropic structure of fast directions observed in the northern section of the Cascadia margin is oblique with respect to the southern section of Cascadia, which, in general, trends E-W and is mainly controlled by active faulting and geological structures. Source distribution analysis using a bivariate normal distribution that expresses the distribution of tremors in a preferred direction shows that in northern California and Oregon, the population of tremors tends to distribute parallel to fast polarization azimuths and maximum compressive stresses, suggesting that both tremor propagation and anisotropy are influenced by the stress field. Results show that the anisotropy reflects an active tectonic process that involves the northward movement of the Oregon Block, which is rotating as a rigid body. In northern Cascadia, previous results of anisotropy show that the crust is undergoing a shortening process due to velocity differences between the Oregon Block and the North America plate, which is moving more slowly with respect to the Oregon Block, making it clash against Vancouver Island.

  15. Evolution of Tremor's Tidal Sensitivity Through the Slow Slip Cycle

    Science.gov (United States)

    Houston, H.

    2014-12-01

    Solid Earth and ocean loading tides generate stresses that modulate slow slip and tremor on deep plate boundaries. Analysis of the influence of tidal stress on 35000 tremors located in a northern Cascadia region that ruptures repeatedly in M6.5 to 6.8 slow earthquakes has yielded several new findings (Houston, 2014, subm.). Tremor sensitivity to tidal stress is low for the first day or so of activity at a spot, but increases progressively over a few days of slip at that spot, constraining the pace of weakening during ETS. After the first day or so, sensitivity varies exponentially with stress. Consideration of an isotropic pore pressure model allows an in-situ estimate of intrinsic friction on the deep subduction interface, yielding values far below lab values (i.e., mu et al, 2010). Inter-ETS tremor groups of several months duration show some sensitivity to tidal stress, although not as much as tremor during the late portions of ETS. Interestingly, I see an evolution during the 12-15 month interval between major ETSs. In particular, tidal sensitivity increases moderately toward the end of the interval as the fault is reloaded and the next large ETS is imminent. First-order features are consistent with extension of the above-mentioned model of threshold failure strength versus stress. The concept is that during the inter-ETS period, strength rebuilds as the logarithm of time (e.g., Vidale et al, 1994) since the last major ETS, while average shear or Coulomb stress on the plate interface rebuilds roughly linearly due to plate convergence. Tidal stresses become more effective in triggering tremor later in the cycle as the linearly-growing stress approaches the logarithmically-growing strength. This approach illuminates the competition between healing on the plate interface and reloading with tectonic stress, and can help constrain healing rate and conditions on the deep subduction interface.

  16. Task force report: Scales for screening and evaluating tremor: Critique and recommendations

    NARCIS (Netherlands)

    Elble, R.; Bain, P.; Forjaz, M. Joao; Haubenberger, D.; Testa, C.; Goetz, C.G.; Leentjens, A.F.; Martinez-Martin, P.; Traon, A. Pavy-Le; Post, B.; Sampaio, C.; Stebbins, G.T.; Weintraub, D.; Schrag, A.

    2013-01-01

    The Movement Disorder Society established a task force to review rating scales for the assessment of tremor. Screening instruments used in identifying patients with tremor were also reviewed. Seven tremor severity scales, six activities of daily living (ADL)/disability scales, four quality-of-life

  17. Limited correlations between clinician-based and patient-based measures of essential tremor severity

    NARCIS (Netherlands)

    van der Stouwe, A. M. M.; Broersma, M.; Buijink, A. W. G.; van Rootselaar, A. F.; Maurits, N. M.

    2015-01-01

    Introduction: We investigated the relation between changes in clinician-based and patient-based measures of tremor severity, within the Fahn-Tolosa-Marin Tremor Rating Scale (IRS) and Visual Analogue Scale (VAS) in essential tremor patients. Methods: Thirty-seven patients were assessed twice: on- an

  18. Task force report: Scales for screening and evaluating tremor: Critique and recommendations

    NARCIS (Netherlands)

    Elble, R.; Bain, P.; Forjaz, M. Joao; Haubenberger, D.; Testa, C.; Goetz, C.G.; Leentjens, A.F.; Martinez-Martin, P.; Traon, A. Pavy-Le; Post, B.; Sampaio, C.; Stebbins, G.T.; Weintraub, D.; Schrag, A.

    2013-01-01

    The Movement Disorder Society established a task force to review rating scales for the assessment of tremor. Screening instruments used in identifying patients with tremor were also reviewed. Seven tremor severity scales, six activities of daily living (ADL)/disability scales, four quality-of-life s

  19. Tremor Detection Using Parametric and Non-Parametric Spectral Estimation Methods : A Comparison with Clinical Assessment

    NARCIS (Netherlands)

    Martinez Manzanera, Octavio; Elting, Jan Willem; van der Hoeven, Johannes H; Maurits, Natasha M

    2016-01-01

    In the clinic, tremor is diagnosed during a time-limited process in which patients are observed and the characteristics of tremor are visually assessed. For some tremor disorders, a more detailed analysis of these characteristics is needed. Accelerometry and electromyography can be used to obtain a

  20. Methodological issues in clinical drug development for essential tremor.

    Science.gov (United States)

    Carranza, Michael A; Snyder, Madeline R; Elble, Rodger J; Boutzoukas, Angelique E; Zesiewicz, Theresa A

    2012-01-01

    Essential tremor (ET) is one of the most common tremor disorders in the world. Despite this, only two medications have received Level A recommendations from the American Academy of Neurology to treat it (primidone and propranolol). Even though these medications provide relief to a large group of ET patients, up to 50% of patients are non-responders. Additional medications to treat ET are needed. This review discusses some of the methodological issues that should be addressed for quality clinical drug development in ET.

  1. Weak Boson Production Amplitude Zeros; Equalities of the Helicity Amplitudes

    CERN Document Server

    Mamedov, F

    2002-01-01

    We investigate the radiation amplitude zeros exhibited by many Standard Model amplitudes for triple weak gauge boson production processes. We show that $WZ\\gamma$ production amplitudes have especially rich structure in terms of zeros, these amplitudes have zeros originating from several different sources. It is also shown that TYPE I current null zone is the special case of the equality of the specific helicity amplitudes.

  2. Periods and Superstring Amplitudes

    CERN Document Server

    Stieberger, S

    2016-01-01

    Scattering amplitudes which describe the interaction of physical states play an important role in determining physical observables. In string theory the physical states are given by vibrations of open and closed strings and their interactions are described (at the leading order in perturbation theory) by a world-sheet given by the topology of a disk or sphere, respectively. Formally, for scattering of N strings this leads to N-3-dimensional iterated real integrals along the compactified real axis or N-3-dimensional complex sphere integrals, respectively. As a consequence the physical observables are described by periods on M_{0,N} - the moduli space of Riemann spheres of N ordered marked points. The mathematical structure of these string amplitudes share many recent advances in arithmetic algebraic geometry and number theory like multiple zeta values, single-valued multiple zeta values, Drinfeld, Deligne associators, Hopf algebra and Lie algebra structures related to Grothendiecks Galois theory. We review the...

  3. Light Meson Distribution Amplitudes

    CERN Document Server

    Arthur, R.; Brommel, D.; Donnellan, M.A.; Flynn, J.M.; Juttner, A.; de Lima, H.Pedroso; Rae, T.D.; Sachrajda, C.T.; Samways, B.

    2010-01-01

    We calculated the first two moments of the light-cone distribution amplitudes for the pseudoscalar mesons ($\\pi$ and $K$) and the longitudinally polarised vector mesons ($\\rho$, $K^*$ and $\\phi$) as part of the UKQCD and RBC collaborations' $N_f=2+1$ domain-wall fermion phenomenology programme. These quantities were obtained with a good precision and, in particular, the expected effects of $SU(3)$-flavour symmetry breaking were observed. Operators were renormalised non-perturbatively and extrapolations to the physical point were made, guided by leading order chiral perturbation theory. The main results presented are for two volumes, $16^3\\times 32$ and $24^3\\times 64$, with a common lattice spacing. Preliminary results for a lattice with a finer lattice spacing, $32^3\\times64$, are discussed and a first look is taken at the use of twisted boundary conditions to extract distribution amplitudes.

  4. Quantitative Seismic Amplitude Analysis

    OpenAIRE

    Dey, A. K.

    2011-01-01

    The Seismic Value Chain quantifies the cyclic interaction between seismic acquisition, imaging and reservoir characterization. Modern seismic innovation to address the global imbalance in hydrocarbon supply and demand requires such cyclic interaction of both feed-forward and feed-back processes. Currently, the seismic value chain paradigm is in a feed-forward mode. Modern seismic data now have the potential to yield the best images in terms of spatial resolution, amplitude accuracy, and incre...

  5. Axonal neuropathy in female carriers of the fragile X premutation with fragile x-associated tremor ataxia syndrome.

    Science.gov (United States)

    Ram, Suresh; Devapriya, Inoka A; Fenton, Grace; Mcvay, Lindsey; Nguyen, Danh V; Tassone, Flora; Maselli, Ricardo A; Hagerman, Randi J

    2015-08-01

    In this study we examined whether females with the fragile X-associated tremor ataxia syndrome (FXTAS) and non-FXTAS premutation carriers have electrophysiological signs of underlying peripheral neuropathy. Nerve conduction studies (NCS) were performed on 19 women with FXTAS, 20 non-FXTAS carriers, and 26 age-matched controls. The results were compared with existing data on corresponding male carriers. Women with FXTAS and non-FXTAS carriers had reduced sensory nerve action potential amplitudes. Also, there was a strong trend for reduced compound muscle action potential amplitudes in women with FXTAS, but not in non-FXTAS carriers. No significant slowing of nerve conduction velocities, prolongation of F-wave latencies, or associations with molecular measures was observed. This study suggests an underlying axonal neuropathy in women with FXTAS. However, in comparison to men with FXTAS, the NCS abnormalities in women were less severe, possibly due to the effect of a normal X chromosome. © 2014 Wiley Periodicals, Inc.

  6. Volcanic signals in oceans

    KAUST Repository

    Stenchikov, Georgiy L.

    2009-08-22

    Sulfate aerosols resulting from strong volcanic explosions last for 2–3 years in the lower stratosphere. Therefore it was traditionally believed that volcanic impacts produce mainly short-term, transient climate perturbations. However, the ocean integrates volcanic radiative cooling and responds over a wide range of time scales. The associated processes, especially ocean heat uptake, play a key role in ongoing climate change. However, they are not well constrained by observations, and attempts to simulate them in current climate models used for climate predictions yield a range of uncertainty. Volcanic impacts on the ocean provide an independent means of assessing these processes. This study focuses on quantification of the seasonal to multidecadal time scale response of the ocean to explosive volcanism. It employs the coupled climate model CM2.1, developed recently at the National Oceanic and Atmospheric Administration\\'s Geophysical Fluid Dynamics Laboratory, to simulate the response to the 1991 Pinatubo and the 1815 Tambora eruptions, which were the largest in the 20th and 19th centuries, respectively. The simulated climate perturbations compare well with available observations for the Pinatubo period. The stronger Tambora forcing produces responses with higher signal-to-noise ratio. Volcanic cooling tends to strengthen the Atlantic meridional overturning circulation. Sea ice extent appears to be sensitive to volcanic forcing, especially during the warm season. Because of the extremely long relaxation time of ocean subsurface temperature and sea level, the perturbations caused by the Tambora eruption could have lasted well into the 20th century.

  7. Knowledge gaps and research recommendations for essential tremor

    NARCIS (Netherlands)

    Hopfner, F.; Haubenberger, D.; Galpern, W.R.; Gwinn, K.; Veer, A. van der; White, S.; Bhatia, K.; Adler, C.H.; Eidelberg, D.; Ondo, W.; Stebbins, G.T.; Tanner, C.M.; Helmich, R.C.G.; Lenz, F.A.; Sillitoe, R.V.; Vaillancourt, D.; Vitek, J.L.; Louis, E.D.; Shill, H.A.; Frosch, M.P.; Foroud, T.; Kuhlenbaumer, G.; Singleton, A.; Testa, C.M.; Hallett, M.; Elble, R.; Deuschl, G.

    2016-01-01

    Essential tremor (ET) is a common cause of significant disability, but its etiologies and pathogenesis are poorly understood. Research has been hampered by the variable definition of ET and by non-standardized research approaches. The National Institute of Neurological Disorders and Stroke (USA)

  8. Fragile X-Associated Tremor/Ataxia Syndrome (FXTAS)

    Science.gov (United States)

    ... but almost always with less severity. Most affected women have some degree of tremor and/or ataxia. While the psychiatric and mood disorders are also less frequent in females, they are at higher risk for anxiety and depression in general. Additional symptoms affecting some ...

  9. Rhythmic finger tapping reveals cerebellar dysfunction in essential tremor

    NARCIS (Netherlands)

    Buijink, A. W. G.; Broersma, M.; van der Stouwe, A. M. M.; van Wingen, G. A.; Groot, P. F. C.; Speelman, J. D.; Maurits, N. M.; van Rootselaar, A. F.

    2015-01-01

    Introduction: Cerebellar circuits are hypothesized to play a central role in the pathogenesis of essential tremor. Rhythmic finger tapping is known to strongly engage the cerebellar motor circuitry. We characterize cerebellar and, more specifically, dentate nucleus function, and neural correlates of

  10. Semidominant heridity of absence-like seizures in tremor rat.

    Institute of Scientific and Technical Information of China (English)

    CaiJi-qun; KumatoshiIshihara; RyosukeHanaya; YoshihiroKiura; KaoruKurisu; TadaoSerikawa; MasashiSasa

    2004-01-01

    The tremor rat (tm/tm) exhibits absence-like seizures characterized by 5 -7 Hz spike-wave complexes in cortical and hippocampal EEG. Recently, the TM rat has been found to be devoid of the asp) artoacylase (asp gene responsible for metabolizing N-acetyl aspartate. Electrophysiological studies were performed to determine whether the tm gene was

  11. Dementia in Fragile X-associated Tremor/Ataxia Syndrome

    Directory of Open Access Journals (Sweden)

    Ricardo Nitrini

    Full Text Available Abstract Fragile X-associated tremor/ataxia syndrome (FXTAS is a cause of movement disorders and cognitive decline which has probably been underdiagnosed, especially if its prevalence proves similar to those of progressive supranuclear palsy and amyotrophic lateral sclerosis. We report a case of a 74-year-old man who presented with action tremor, gait ataxia and forgetfulness. There was a family history of tremor and dementia, and one of the patient's grandsons was mentally deficient. Neuropsychological evaluation disclosed a frontal network syndrome. MRI showed hyperintensity of both middle cerebellar peduncles, a major diagnostic hallmark of FXTAS. Genetic testing revealed premutation of the FMR1 gene with an expanded (CGG90 repeat. The diagnosis of FXTAS is important for genetic counseling because the daughters of the affected individuals are at high risk of having offspring with fragile X syndrome. Tremors and cognitive decline should raise the diagnostic hypothesis of FXTAS, which MRI may subsequently reinforce, while the detection of the FMR1 premutation can confirm the condition.

  12. Online tremor suppression using electromyography and low-level electrical stimulation.

    Science.gov (United States)

    Dosen, Strahinja; Muceli, Silvia; Dideriksen, Jakob Lund; Romero, Juan Pablo; Rocon, Eduardo; Pons, Jose; Farina, Dario

    2015-05-01

    Tremor is one of the most prevalent movement disorders. There is a large proportion of patients (around 25%) in whom current treatments do not attain a significant tremor reduction. This paper proposes a tremor suppression strategy that detects tremor from the electromyographic signals of the muscles from which tremor originates and counteracts it by delivering electrical stimulation to the antagonist muscles in an out of phase manner. The detection was based on the iterative Hilbert transform and stimulation was delivered above the motor threshold (motor stimulation) and below the motor threshold (sensory stimulation). The system was tested on six patients with predominant wrist flexion/extension tremor (four with Parkinson disease and two with Essential tremor) and led to an average tremor reduction in the range of 46%-81% and 35%-48% across five patients when using the motor and sensory stimulation, respectively. In one patient, the system did not attenuate tremor. These results demonstrate that tremor attenuation might be achieved by delivering electrical stimulation below the motor threshold, preventing muscle fatigue and discomfort for the patients, which sets the basis for the development of an alternative treatment for tremor.

  13. Using a smart phone as a standalone platform for detection and monitoring of pathological tremors.

    Science.gov (United States)

    Daneault, Jean-François; Carignan, Benoit; Codère, Carl Éric; Sadikot, Abbas F; Duval, Christian

    2012-01-01

    Smart phones are becoming ubiquitous and their computing capabilities are ever increasing. Consequently, more attention is geared toward their potential use in research and medical settings. For instance, their built-in hardware can provide quantitative data for different movements. Therefore, the goal of the current study was to evaluate the capabilities of a standalone smart phone platform to characterize tremor. Algorithms for tremor recording and online analysis can be implemented within a smart phone. The smart phone provides reliable time- and frequency-domain tremor characteristics. The smart phone can also provide medically relevant tremor assessments. Smart phones have the potential to provide researchers and clinicians with quantitative short- and long-term tremor assessments that are currently not easily available. A smart phone application for tremor quantification and online analysis was developed. Then, smart phone results were compared to those obtained simultaneously with a laboratory accelerometer. Finally, results from the smart phone were compared to clinical tremor assessments.

  14. Tremor in X-linked recessive spinal and bulbar muscular atrophy (Kennedy's disease

    Directory of Open Access Journals (Sweden)

    Francisco A. Dias

    2011-01-01

    Full Text Available OBJECTIVE: To study tremor in patients with X-linked recessive spinobulbar muscular atrophy or Kennedy's disease. METHODS: Ten patients (from 7 families with a genetic diagnosis of Kennedy's disease were screened for the presence of tremor using a standardized clinical protocol and followed up at a neurology outpatient clinic. All index patients were genotyped and showed an expanded allele in the androgen receptor gene. RESULTS: Mean patient age was 37.6 years and mean number of CAG repeats 47 (44-53. Tremor was present in 8 (80% patients and was predominantly postural hand tremor. Alcohol responsiveness was detected in 7 (88% patients with tremor, who all responded well to treatment with a β-blocker (propranolol. CONCLUSION: Tremor is a common feature in patients with Kennedy's disease and has characteristics similar to those of essential tremor.

  15. Automatic classification of seismo-volcanic signatures

    Science.gov (United States)

    Malfante, Marielle; Dalla Mura, Mauro; Mars, Jérôme; Macedo, Orlando; Inza, Adolfo; Métaxian, Jean-Philippe

    2017-04-01

    The prediction of volcanic eruptions and the evaluation of their associated risks is still a timely and open issue. For this purpose, several types of signals are recorded in the proximity of volcanoes and then analysed by experts. Typically, seismic signals that are considered as precursor or indicator of an active volcanic phase are detected and manually classified. In this work, we propose an architecture for automatic classification of seismo-volcanic waves. The system we propose is based on supervised machine learning. Specifically, a prediction model is built from a large dataset of labelled examples by the means of a learning algorithm (Support Vector Machine or Random Forest). Four main steps are involved: (i) preprocess the signals, (ii) from each signal, extract features that are useful for the classes discrimination, (iii) use an automatic learning algorithm to train a prediction model and (iv) classify (i.e., assign a semantic label) newly recorded and unlabelled examples. Our main contribution lies in the definition of the feature space used to represent the signals (i.e., in the choice of the features to extract from the data). Feature vectors describe the data in a space of lower dimension with respect to the original one. Ideally, signals are separable in the feature space depending on their classes. For this work, we consider a large set of features (79) gathered from an extensive state of the art in both acoustic and seismic fields. An analysis of this feature set shows that for the application of interest, 11 features are sufficient to discriminate the data. The architecture is tested on 4725 seismic events recorded between June 2006 and September 2011 at Ubinas, the most active volcano of Peru. Six main classes of signals are considered: volcanic tremors (TR), long period (LP), volcano-tectonic (VT), explosion (EXP), hybrids (HIB) and tornillo (TOR). Our model reaches above 90% of accuracy, thereby validating the proposed architecture and the

  16. Non-invasive Brain Stimulation for Essential Tremor

    Science.gov (United States)

    Shih, Ludy C.; Pascual-Leone, Alvaro

    2017-01-01

    Background There is increasing interest in the use of non-invasive brain stimulation to characterize and potentially treat essential tremor (ET). Studies have used a variety of stimulation coils, paradigms, and target locations to make these observations. We reviewed the literature to compare prior studies and to evaluate the rationale and the methods used in these studies. Methods We performed a systematic literature search of the PubMed database using the terms “transcranial,” “noninvasive,” “brain stimulation,” “transcranial magnetic stimulation (TMS),” “transcranial direct current stimulation (tDCS),” “transcranial alternating current stimulation (tACS),” and “essential tremor.” Results Single pulses of TMS to the primary motor cortex have long been known to reset tremor. Although there are relatively few studies showing alterations in motor cortical physiology, such as motor threshold, short and long intracortical inhibition, and cortical silent period, there may be some evidence of altered intracortical facilitation and cerebello-brain inhibition in ET. Repetitive TMS, theta burst stimulation, tDCS, and tACS have been applied to human subjects with tremor with some preliminary signs of tremor reduction, particularly in those studies that employed consecutive daily sessions. Discussion A variety of stimulation paradigms and targets have been explored, with the increasing rationale an interest in targeting the cerebellum. Rigorous assessment of coil geometry, stimulation paradigm, rationale for selection of the specific anatomic target, and careful phenotypic and physiologic characterization of the subjects with ET undergoing these interventions may be critical in extending these preliminary findings into effective stimulation therapies. PMID:28373927

  17. Task force report: scales for screening and evaluating tremor: critique and recommendations.

    Science.gov (United States)

    Elble, Rodger; Bain, Peter; Forjaz, Maria João; Haubenberger, Dietrich; Testa, Claudia; Goetz, Christopher G; Leentjens, Albert F G; Martinez-Martin, Pablo; Pavy-Le Traon, Anne; Post, Bart; Sampaio, Cristina; Stebbins, Glenn T; Weintraub, Daniel; Schrag, Anette

    2013-11-01

    The Movement Disorder Society established a task force to review rating scales for the assessment of tremor. Screening instruments used in identifying patients with tremor were also reviewed. Seven tremor severity scales, six activities of daily living (ADL)/disability scales, four quality-of-life scales, and five screening instruments were identified by searching PubMed.gov. The availability, use, acceptability, reliability, validity, and sensitivity to change were reviewed for each scale; and each scale was classified as recommended, suggested or listed based on whether 3, 2, or 1 of the following criteria were met: (1) used in the assessment of tremor (yes/no), (2) used in published studies by people other than the developers (yes/no), and (3) successful clinimetric testing (yes/no). Five tremor severity scales (the Fahn-Tolosa-Marin Tremor Rating Scale, the Bain and Findley Clinical Tremor Rating Scale, the Bain and Findley Spirography Scale, the Washington Heights-Inwood Genetic Study of Essential Tremor Rating Scale, and the Tremor Research Group Essential Tremor Rating Assessment Scale), one ADL/disability scale (the Bain and Findley Tremor ADL Scale), one quality-of-life scale (the Quality of Life in Essential Tremor Questionnaire), and one screening instrument (the Washington Heights-Inwood Genetic Study of Essential Tremor Rating Scale, version 1) are recommended using these criteria. However, all scales need a more comprehensive analysis of sensitivity to change in order to judge their utility in clinical trials and individual patient assessments. The task force recommends that further work with existing recommended scales be performed as opposed to the development of new tremor scales.

  18. Volcanic Rocks and Features

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Volcanoes have contributed significantly to the formation of the surface of our planet. Volcanism produced the crust we live on and most of the air we breathe. The...

  19. Research on the tremor suppression test system for the tremor suppression robot%抑制震颤机器人抑震试验系统研究

    Institute of Scientific and Technical Information of China (English)

    李军强; 王娟; 高永生

    2012-01-01

    By applying the magnetorheological damper developed,a tremor suppression robot with 2 degree of freedom was designed,which tremor occurred in the process of elbow flexion or extension and forearm revolving can be suppressed.Then a tremor suppression controller was developed, which can execute (he tremor suppression control algorithm,convert and process the tremor information as well as output the control current and communical.e with the PC and so on.Finally the tremor system for simulating arm was designed,which can output tremor information for the tremor suppression tesuBased on above results, the motion control test for the tremor suppression test system was done., which result shows that the tremor suppression test system can simulate the tremor effectually.%应用所研制的磁流变阻尼器,设计了两个自由度的抑震机器人结构,可对人体上肢肘部屈/伸、前臂旋转运动过程中产生的震颤进行抑制.研制了抑震控制器,能够完成抑震控制算法的运行、震颤信息的转换与处理、控制量的输出以及与上位机通信等工作.设计了模拟人体上肢震颤系统,为抑震试验提供震颤信息.在此基础上进行了抑震试验系统运动控制试验,试验结果显示,所研制的抑震试验系统能够较好的模拟人体的震颤过程.

  20. Noise-induced variability of volcanic extrusions

    Science.gov (United States)

    Alexandrov, D. V.; Bashkirtseva, I. A.; Ryashko, L. B.

    2016-11-01

    Motivated by important physical applications, we study a non-linear dynamics of volcanic extrusions on the basis of a simple pressure-mass flow model. We demonstrate that the deterministic phase portrait represents either the bulbous-type curves or closed paths stretched to their left depending on the initial conditions. The period of phase trajectories therewith increases when the pressure drop between the conduit top and bottom compensates the lava column pressure in it. Stochastic forcing changes the system dynamics drastically. We show that a repetitive scenario of volcanic behaviour with intermittency of stochastic oscillations of different extrusion amplitudes and frequencies appears in the presence of noises. As this takes place, the mean values of interspike intervals characterizing the system periodicity have a tendency to grow with increasing the noise intensity. The probability distribution functions confirming this dynamic behaviour are constructed.

  1. Volcanic Environments Monitoring by Drones Mud Volcano Case Study

    Science.gov (United States)

    Amici, S.; Turci, M.; Giulietti, F.; Giammanco, S.; Buongiorno, M. F.; La Spina, A.; Spampinato, L.

    2013-08-01

    Volcanic activity has often affected human life both at large and at small scale. For example, the 2010 Eyjafjallajokull eruption caused severe economic damage at continental scale due to its strong effect on air traffic. At a local scale, ash fall and lava flow emission can cause harm and disruption. Understanding precursory signals to volcanic eruptions is still an open and tricky challenge: seismic tremor and gas emissions, for example, are related to upcoming eruptive activity but the mechanisms are not yet completely understood. Furthermore, information related to gases emission mostly comes from the summit crater area of a volcano, which is usually hard to investigate with required accuracy. Although many regulation problems are still on the discussion table, an increasing interest in the application of cutting-edge technology like unmanned flying systems is growing up. In this sense, INGV (Istituto Nazionale di Geofisica e Vulcanologia) started to investigate the possibility to use unmanned air vehicles for volcanic environment application already in 2004. A flight both in visual- and radio-controlled mode was carried out on Stromboli volcano as feasibility test. In this work we present the preliminary results of a test performed by INGV in collaboration with the University of Bologna (aerospace division) by using a multi-rotor aircraft in a hexacopter configuration. Thermal camera observations and flying tests have been realised over a mud volcano located on its SW flank of Mt. Etna and whose activity proved to be related to early stages of magma accumulation within the volcano.

  2. Systematic search of triggered and ambient tectonic tremor in Southern California

    Science.gov (United States)

    Yang, H.; Peng, Z.

    2013-12-01

    Tectonic tremor has been extensively observed along the Parkfield-Cholame section of the San Andreas Fault in central California. In contrast, observations of either triggered or ambient tremor in southern California are quite sparse to date. In this study we conduct a systematic search of tectonic tremor around the Simi Valley (SV), the San Gabriel Mountain (SGM), and the San Jacinto Fault (SJF). We focus on these regions, mainly because of previous observations of triggered tremor at the SV and SJF, and evidence of near-lithostatic fluid under the SGM and deep creep along the SJF. We first search for tremor triggered by distant large earthquakes around the SV and the SGM in southern California. Out of 59 large earthquakes between 2000 and 2013, only the 2002 Mw 7.9 Denali Fault earthquake triggered clear tremor in the region. The observed travel times of the triggered tremors are consistent with theoretical predictions from tremor sources that are spatially clustered in the SV, close to the rupture zone of the 1994 Mw 6.7 Northridge earthquake. We also estimate the triggering stress threshold as ˜12 KPa from measuring the peak ground velocities near the tremor source. The lack of clear tremor beneath the SGM provides a 'negative' example for a region where tremor is expected to occur because of clear evidence of fluid-rich zones at the middle crust. The results imply that the necessary conditions for tremor to occur are more than fluid-induced low effective normal stress. In addition to tremor in the SV, we also investigate tremor along the SJF, where tremor was triggered by the 2002 Mw7.9 Denali Fault and the 2011 Mw9.1 Tohoku-Oki earthquakes. These triggered tremors provide natural templates of the low frequency earthquakes that can be used to perform matched-filter detection to search for additional tremors along the SJF. In addition, there are strain transients following the March 11, 2013, Mw 4.7 earthquake that are captured by PBO strainmeters near the SJF

  3. Slip Updip of Tremor during the 2012 Cascadia ETS Event

    Science.gov (United States)

    Hall, K.; Houston, H.

    2014-12-01

    The interplay between tremor and slow slip during ETS has implications for the slip budget of the Cascadia subduction zone. In particular, it can constrain the downdip edge of the locked zone, which informs the hazard assessments for major cities including Seattle, Tacoma, and Vancouver. As shown by Houston (AGU abstract, 2012), slip inferred from GPS extended updip of the seismically-detected tremor in the 2010 M6.8 ETS event. Following the methods used on the 2010 ETS event, we used the PANGA GPS to measure the displacement vectors for 71 stations to analyze a large ETS event in 2012 that extended from Vancouver Island to Southern Washington. We implemented Principal Component Analysis to automatically select the direction and magnitude of the maximum displacement vector. We then inverted these GPS displacements for slip, using the Okada formulation of buried rectangular faults in a halfspace with a grid of 8 by 8 km subfaults based on the McCrory slab model. We performed inversions with either 0th or 2nd order Tikhonov regularization and found that over the 6 weeks of propagation, the 2012 ETS event released moment corresponding to M6.7, in three high-slip regions. We compared two different inversions, one where slip was allowed on a broad regional grid and a tremor-restricted inversion (TRI) where slip was restricted to grid locations where tremor had been detected in the 2012 ETS. We found that the TRI forced the slip to the updip edge of the grid where it reached above 10 cm, which is physically implausible given that this exceeds the slip that can accumulate in an inter-ETS time period. Additionally, the regional grid inversion indicates that 1 to 2 cm of slip occurred 10's of km updip of the western edge of tremor. This further supports the inference from the 2010 event that in northern Washington, the slow slip during an ETS event extends many kilometers updip of the western edge of tremor.

  4. Cohort study of prevalence and phenomenology of tremor in dementia with Lewy bodies.

    Science.gov (United States)

    Onofrj, Marco; Varanese, Sara; Bonanni, Laura; Taylor, John-Paul; Antonini, Angelo; Valente, Enza Maria; Petrucci, Simona; Stocchi, Fabrizio; Thomas, Astrid; Perfetti, Bernardo

    2013-07-01

    To study prevalence, specific patterns and response to treatment of tremor in dementia with Lewy bodies (DLB), in comparison with other tremulous disorders prevalence, qualitative and quantitative features of tremor were studied in an incident cohort of 67 dopaminergic treatment naive DLB, 111 Parkinson's Disease (PD) and 34 Essential Tremor (ET) patients. Tremulous DLB patients (tDLB) were compared with tremulous PD (tPD) and ET patients and followed for 2 years. Double blind placebo-controlled acute drug challenge with L-Dopa and alcohol was performed in all ET, 24 tDLB and 27 tPD. Effects of dopaminergic chronic treatment in all tDLB and tPD patients and primidone in 8 tDLB were also assessed. Tremor occurred in 44.76 % of DLB patients. The tDLB patients presented a complex pattern of mixed tremors, characterized by rest and postural/action tremor, including walking tremor and standing overflow in 50 % tDLB. Standing tremor with overflow was characteristic of tDLB (p < 0.001). Head tremor was more frequent in tDLB than tPD and ET (p = 0.001). The tDLB tremors were reduced by acute and chronic dopaminergic treatments (p < 0.01) but not by alcohol or primidone. Tremor occurs commonly in DLB patients with a complex mixed tremor pattern which shows a significant response to acute and chronic dopaminergic treatments. Recognizing that there is a clinical category of tremulous DLB may help the differential diagnosis of tremors.

  5. Tremor and hand-arm vibration syndrome (HAVS) in road maintenance workers.

    Science.gov (United States)

    Bast-Pettersen, Rita; Ulvestad, Bente; Færden, Karl; Clemm, Thomas Aleksander C; Olsen, Raymond; Ellingsen, Dag Gunnar; Nordby, Karl-Christian

    2017-01-01

    The aim of this study was to evaluate postural and rest tremor among workers using vibrating hand tools, taking into account the possible effects of toxicants such as alcohol and tobacco. A further aim was to study workers diagnosed with hand-arm vibration syndrome (HAVS) at the time of examination. This study comprises 103 road maintenance workers, 55 exposed to vibrating hand tools (age 41.0 years; range 21-62) and 48 referents (age 38.5 years; range 19-64). They were examined with the CATSYS Tremor Pen(®). Exposure to vibrating tools and serum biomarkers of alcohol and tobacco consumption were measured. Cumulative exposure to vibrating tools was associated with increased postural (p < 0.01) and rest tremor (p < 0.05) and with a higher Center Frequency of postural tremor (p < 0.01) among smokers and users of smokeless tobacco. Rest tremor Center Frequency was higher than postural tremor frequency (p < 0.001). The main findings indicate an association between cumulative exposure to hand-held vibrating tools, tremor parameters and consumption of tobacco products. The hand position is important when testing for tremor. Rest tremor had a higher Center Frequency. Postural tremor was more strongly associated with exposure than rest tremor. The finding of increased tremor among the HAVS subjects indicated that tremor might be a part of the clinical picture of a HAVS diagnosis. As with all cross-sectional studies, inferences should be made with caution when drawing conclusions about associations between exposure and possible effects. Future research using longitudinal design is required to validate the findings of the present study.

  6. Different phase delays of peripheral input to primate motor cortex and spinal cord promote cancellation at physiological tremor frequencies.

    Science.gov (United States)

    Koželj, Saša; Baker, Stuart N

    2014-05-01

    Neurons in the spinal cord and motor cortex (M1) are partially phase-locked to cycles of physiological tremor, but with opposite phases. Convergence of spinal and cortical activity onto motoneurons may thus produce phase cancellation and a reduction in tremor amplitude. The mechanisms underlying this phase difference are unknown. We investigated coherence between spinal and M1 activity with sensory input. In two anesthetized monkeys, we electrically stimulated the medial, ulnar, deep radial, and superficial radial nerves; stimuli were timed as independent Poisson processes (rate 10 Hz). Single units were recorded from M1 (147 cells) or cervical spinal cord (61 cells). Ninety M1 cells were antidromically identified as pyramidal tract neurons (PTNs); M1 neurons were additionally classified according to M1 subdivision (rostral/caudal, M1r/c). Spike-stimulus coherence analysis revealed significant coupling over a broad range of frequencies, with the strongest coherence at <50 Hz. Delays implied by the slope of the coherence phase-frequency relationship were greater than the response onset latency, reflecting the importance of late response components for the transmission of oscillatory inputs. The spike-stimulus coherence phase over the 6-13 Hz physiological tremor band differed significantly between M1 and spinal cells (phase differences relative to the cord of 2.72 ± 0.29 and 1.72 ± 0.37 radians for PTNs from M1c and M1r, respectively). We conclude that different phases of the response to peripheral input could partially underlie antiphase M1 and spinal cord activity during motor behavior. The coordinated action of spinal and cortical feedback will act to reduce tremulous oscillations, possibly improving the overall stability and precision of motor control.

  7. Volcanic hazards to airports

    Science.gov (United States)

    Guffanti, M.; Mayberry, G.C.; Casadevall, T.J.; Wunderman, R.

    2009-01-01

    Volcanic activity has caused significant hazards to numerous airports worldwide, with local to far-ranging effects on travelers and commerce. Analysis of a new compilation of incidents of airports impacted by volcanic activity from 1944 through 2006 reveals that, at a minimum, 101 airports in 28 countries were affected on 171 occasions by eruptions at 46 volcanoes. Since 1980, five airports per year on average have been affected by volcanic activity, which indicates that volcanic hazards to airports are not rare on a worldwide basis. The main hazard to airports is ashfall, with accumulations of only a few millimeters sufficient to force temporary closures of some airports. A substantial portion of incidents has been caused by ash in airspace in the vicinity of airports, without accumulation of ash on the ground. On a few occasions, airports have been impacted by hazards other than ash (pyroclastic flow, lava flow, gas emission, and phreatic explosion). Several airports have been affected repeatedly by volcanic hazards. Four airports have been affected the most often and likely will continue to be among the most vulnerable owing to continued nearby volcanic activity: Fontanarossa International Airport in Catania, Italy; Ted Stevens Anchorage International Airport in Alaska, USA; Mariscal Sucre International Airport in Quito, Ecuador; and Tokua Airport in Kokopo, Papua New Guinea. The USA has the most airports affected by volcanic activity (17) on the most occasions (33) and hosts the second highest number of volcanoes that have caused the disruptions (5, after Indonesia with 7). One-fifth of the affected airports are within 30 km of the source volcanoes, approximately half are located within 150 km of the source volcanoes, and about three-quarters are within 300 km; nearly one-fifth are located more than 500 km away from the source volcanoes. The volcanoes that have caused the most impacts are Soufriere Hills on the island of Montserrat in the British West Indies

  8. PULSE AMPLITUDE DISTRIBUTION RECORDER

    Science.gov (United States)

    Cowper, G.

    1958-08-12

    A device is described for automatica1ly recording pulse annplitude distribution received from a counter. The novelty of the device consists of the over-all arrangement of conventional circuit elements to provide an easy to read permanent record of the pulse amplitude distribution during a certain time period. In the device a pulse analyzer separates the pulses according to annplitude into several channels. A scaler in each channel counts the pulses and operates a pen marker positioned over a drivable recorder sheet. Since the scalers in each channel have the sanne capacity, the control circuitry permits counting of the incoming pulses until one scaler reaches capacity, whereupon the input is removed and an internal oscillator supplies the necessary pulses to fill up the other scalers. Movement of the chart sheet is initiated wben the first scaler reaches capacity to thereby give a series of marks at spacings proportional to the time required to fill the remaining scalers, and accessory equipment marks calibration points on the recorder sheet to facilitate direct reading of the number of external pulses supplied to each scaler.

  9. A double-correlation tremor-location method

    CERN Document Server

    Li, Ka Lok; Sadeghisorkhani, Hamzeh; Roberts, Roland; Gudmundsson, Ólafur

    2016-01-01

    A double-correlation method is introduced to locate tremor sources based on stacks of complex, doubly-correlated tremor records of multiple triplets of seismographs back projected to hypothetical source locations in a geographic grid. Peaks in the resulting stack of moduli are inferred source locations. The stack of the moduli is a robust measure of energy radiated from a point source or point sources even when the velocity information is imprecise. Application to real data shows how double correlation focuses the source mapping compared to the common single correlation approach. Synthetic tests demonstrate the robustness of the method and its resolution limitations which are controlled by the station geometry, the finite frequency of the signal, the quality of the used velocity information and noise level. Both random noise and signal or noise correlated at time shifts that are inconsistent with the assumed velocity structure can be effectively suppressed. Assuming a surface-wave velocity, we can constrain t...

  10. Regular and stochastic behavior of Parkinsonian pathological tremor signals

    CERN Document Server

    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...

  11. Long-distance induced tremor observed off western Canada

    Science.gov (United States)

    Schultz, Colin

    2013-05-01

    Using seismic observations made near the Queen Charlotte Margin (QCM), a seismically active region off the western coast of Canada, Aiken et al. add to the growing body of research on how large earthquakes can cause tectonic plates to slip half way around the world. Reaching north from the intersection of the Juan de Fuca ridge, the Cascadia subduction zone, and the Queen Charlotte Fault, QCM underlies the islands of Haida Gwaii and was the site of a magnitude 7.7 earthquake in October 2012. Drawing on seismic readings collected from 1990 to 2012 and using a database of major worldwide earthquakes, the authors identified three earthquakes that induced tremors in QCM: the 2002 magnitude 7.9 Denali earthquake, the 2004 magnitude 9.2 Sumatra quake, and the 2011 magnitude 9.1 Tohoku earthquake. The authors observed the induction not of conventional earthquakes but of deep tectonic tremors, slips of tectonic plates with epicenters located far beneath the surface.

  12. Botulinum Toxin for the Treatment of Tremor and Tics.

    Science.gov (United States)

    Lotia, Mitesh; Jankovic, Joseph

    2016-02-01

    The therapeutic applications of botulinum toxin (BoNT) have grown manifold since its initial approval in 1989 by the U.S. Food and Drug Administration for the treatment of strabismus, blepharospasm, and other facial spasms. Although it is the most potent biologic toxin known to man, long-term studies have established its safety in the treatment of a variety of neurologic and nonneurologic disorders. Despite a paucity of randomized controlled trials, BoNT has been found to be beneficial in treating a variety of tremors and tics when used by clinicians skilled in the administration of the drug for these hyperkinetic movement disorders. Botulinum toxin injections can provide meaningful improvement in patients with localized tremors and tics; in some cases, they may be an alternative to other treatments with more undesirable adverse effects.

  13. Ambient Tremor Triggered by Long-term Slow Slip Event in Bungo Channel, Southwest Japan

    Science.gov (United States)

    Obara, K.; Hirose, H.; Matsuzawa, T.; Tanaka, S.; Maeda, T.

    2014-12-01

    Episodic tremor and slip (ETS) is a stick-slip in the transition zone between locked and stable sliding zones on the plate interface in Southwest Japan and Cascadia. ETS episode with duration of several days usually recurs at interval of several months at each segment. On the other hand, in the Bungo channel region where is the western edge of the ETS zone in SW Japan, tremor activity continued for several months during the long-term slow slip event (SSE) in 2003 and 2010. In this paper, the relationship between long-term SSE and surrounded triggered tremor is discussed. Tremor triggered by the long-term SSE is spatially localized in the narrow width of about 10 km at the shallowest part of the tremor zone, and at the neighboring area just downdip from the source fault of the SSE. The frequency distribution of tremor along the dip direction during the SSE period is consistent with the spatial distribution of total slip estimated for 2010 SSE. Therefore, the slip of the long-term SSE penetrated in the ETS zone may generate tremor. The daily number of the activated tremor is 12-14 during the SSE; however, it is 40-50 for regular ETS episode during the inter-SSE period. On the other hand, slip rates of the long-term SSE and ETS are typically 1 mm/d and 3 mm/d, respectively. Therefore, tremor rate may be controlled by slip rate. After SSEs in 2003 and 2010, tremor activity seems to slightly increase in the east region within 50 km from the triggered tremor area. Such 7-year period variation in tremor activity is observed in only the shallower side of the tremor zone. Moreover, pattern of the long-term variation seems to slightly migrate to east during a few years. We interpret that a tiny transient slip after the long-term SSE slowly propagates between transition and locked zones. Tremor activity at the shallowest part of the tremor zone in the Bungo channel continued longer than that of regular ETS in the late 2006 during the inter-SSE period. Associated tiny GPS

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

    Institute of Scientific and Technical Information of China (English)

    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.

  15. Prenatal exposure to the organophosphate pesticide chlorpyrifos and childhood tremor

    Science.gov (United States)

    Rauh, Virginia A.; Garcia, Wanda E.; Whyatt, Robin M.; Horton, Megan K.; Barr, Dana B.; Louis, Elan D.

    2016-01-01

    Background The organophosphate insecticide chlorpyrifos (CPF), widely used for agricultural purposes, has been linked to neurodevelopmental deficits. Possible motor effects at low to moderate levels of exposure have not been evaluated. Methods Prenatal exposure to CPF was measured in umbilical cord blood in a sample of 263 inner-city minority children, who were followed prospectively. At approximately 11 years of age (mean age 10.9 ± 0.85 years, range = 9.0–13.9), during a neuropsychological assessment, children were asked to draw Archimedes spirals. These were rated by a senior neurologist specializing in movement disorders who was blind to CPF exposure level. Results Compared to all other children, those with prenatal CPF exposure in the upper quartile range (n = 43) were more likely to exhibit mild or mild to moderate tremor (≥1) in either arm (p = 0.03), both arms (p = 0.02), the dominant arm (p = 0.01), and the non-dominant arm (p = 0.055). Logistic regression analyses showed significant CPF effects on tremor in both arms, either arm, the dominant arm (p-values < 0.05), and the non-dominant arm (p = 0.06), after adjustment for sex, age at testing, ethnicity, and medication. Conclusion Prenatal CPF exposure is associated with tremor in middle childhood, which may be a sign of the insecticide's effects on nervous system function. PMID:26385760

  16. Precambrian Lunar Volcanic Protolife

    Directory of Open Access Journals (Sweden)

    Jack Green

    2009-06-01

    Full Text Available Five representative terrestrial analogs of lunar craters are detailed relevant to Precambrian fumarolic activity. Fumarolic fluids contain the ingredients for protolife. Energy sources to derive formaldehyde, amino acids and related compounds could be by flow charging, charge separation and volcanic shock. With no photodecomposition in shadow, most fumarolic fluids at 40 K would persist over geologically long time periods. Relatively abundant tungsten would permit creation of critical enzymes, Fischer-Tropsch reactions could form polycyclic aromatic hydrocarbons and soluble volcanic polyphosphates would enable assembly of nucleic acids. Fumarolic stimuli factors are described. Orbital and lander sensors specific to protolife exploration including combined Raman/laser-induced breakdown spectrocsopy are evaluated.

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

    Directory of Open Access Journals (Sweden)

    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.

  18. Lung problems and volcanic smog

    Science.gov (United States)

    ... releases gases into the atmosphere. Volcanic smog can irritate the lungs and make existing lung problems worse. ... deep into the lungs. Breathing in volcanic smog irritates the lungs and mucus membranes. It can affect ...

  19. CHY formula and MHV amplitudes

    CERN Document Server

    Du, Yi-jian; Wu, Yong-shi

    2016-01-01

    In this paper, we study the relation between the Cachazo-He-Yuan (CHY) formula and the maximal-helicity-violating (MHV) amplitudes of Yang-Mills and gravity in four dimensions. We prove that only one special rational solution of the scattering equations found by Weinzierl support the MHV amplitudes. Namely, localized at this solution, the integrated CHY formula reproduces the Parke-Taylor formula for Yang-Mills amplitudes as well as the Hodges formula for gravitational amplitudes. This is achieved by developing techniques, in a manifestly M\\"obius covariant formalism, to explicitly compute relevant reduced Pfaffians/determinants. We observe and prove two interesting properties (or identities), which facilitate the computations. We also check that all the other $(n-3)!-1$ solutions to the scattering equations do not support the MHV amplitudes, and prove analytically that this is indeed true for the other special rational solution proposed by Weinzierl, that actually supports the anti-MHV amplitudes.

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

    CERN Document Server

    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.

  1. Primary task-specific bowing tremor: an entity of its own?

    Science.gov (United States)

    Lee, André; Altenmüller, Eckart

    2012-12-01

    A professional violinist in his early 60s, playing in a prestigious German orchestra for more than 20 years, presented to our institute because of a task-induced tremor in his right arm when playing the violin. We describe the phenomenology of this tremor and its treatment options and compare it to findings in primary writing tremor (PWT). We then discuss whether primary bowing tremor is an entity of its own (similar to PWT) and propose hypotheses that would derive from such a definition.

  2. Volcanism and Oil & Gas In Northeast China

    Institute of Scientific and Technical Information of China (English)

    Shan Xuanlong

    2000-01-01

    Based on study on the relation with volcanic rock and oil & gas in Songliao Basin and Liaohe Basin in northeast China, author proposes that material from deep by volcanism enrichs the resources in basins, that heat by volcanism promotes organic matter transforming to oil and gas, that volcanic reservoir is fracture, vesicular, solution pore, intercrystal pore.Lava facies and pyroclastic facies are favourable reservoir. Mesozoic volcanic reservoir is majority of intermediate, acid rock,but Cenozoic volcanic reservoir is majority of basalt. Types of oil and gas pool relating to volcanic rock include volcanic fracture pool, volcanic unconformity pool, volcanic rock - screened pool, volcanic darpe structural pool.

  3. Essential tremor then and now: How views of the most common tremor diathesis have changed over time.

    Science.gov (United States)

    Louis, Elan D

    2017-07-13

    Essential tremor (ET) is the most prevalent tremor diathesis. In this "then" and "now" piece, I detail how views of this disorder have changed over time. A PubMed search was conducted on June 15, 2017. The term "essential tremor" was crossed in sequential order with 14 s search terms (e.g., genetics, clinical). The traditional view of ET was that it was monosymptomatic. An emerging view of ET is as a more clinically-complex entity with a range of possible motor and non-motor features. Traditionally, ET was viewed as autosomal dominant with complete penetrance by age 65. Current thinking is that, in addition to monogenic forms of ET, the disease is likely to be complex, with incomplete penetrance into advanced age. While non-genetic factors were traditionally presumed to exist, epidemiological studies have explored several potential environmental toxicants. The traditional olivary model of ET posited the existence of a central oscillator; an alternative is the cerebellar degenerative model, which is now under consideration. For ET, there is clearly a "then" and "now" when one assesses changes in our understanding of the disease with time. Indeed, concepts relating to the clinical features, disease etiology and pathogenesis have all changed substantially. Copyright © 2017 Elsevier Ltd. All rights reserved.

  4. Fragile X-associated tremor/ataxia syndrome: An under-recognised cause of tremor and ataxia.

    Science.gov (United States)

    Kalus, Sarah; King, John; Lui, Elaine; Gaillard, Frank

    2016-01-01

    Fragile X-associated tremor/ataxia syndrome (FXTAS) is a progressive degenerative movement disorder resulting from a fragile X "premutation", defined as 55-200 CGG repeats in the 5'-untranslated region of the FMR1 gene. The FMR1 premutation occurs in 1/800 males and 1/250 females, with FXTAS affecting 40-45% of male and 8-16% of female premutation carriers over the age of 50. FXTAS typically presents with kinetic tremor and cerebellar ataxia. FXTAS has a classical imaging profile which, in concert with clinical manifestations and genetic testing, participates vitally in its diagnosis. The revised FXTAS diagnostic criteria include two major radiological features. The "MCP sign", referring to T2 hyperintensity in the middle cerebellar peduncle, has long been considered the radiological hallmark of FXTAS. Recently included as a major radiological criterion in the diagnosis of FXTAS is T2 hyperintensity in the splenium of the corpus callosum. Other imaging features of FXTAS include T2 hyperintensities in the pons, insula and periventricular white matter as well as generalised brain and cerebellar atrophy. FXTAS is an under-recognised and misdiagnosed entity. In patients with unexplained tremor, ataxia and cognitive decline, the presence of middle cerebellar peduncle and/or corpus callosum splenium hyperintensity should raise suspicion of FXTAS. Diagnosis of FXTAS has important implications not only for the patient but also, through genetic counselling and testing, for future generations.

  5. Retrieval and intercomparison of volcanic SO2 injection height and eruption time from satellite maps and ground-based observations

    Science.gov (United States)

    Pardini, Federica; Burton, Mike; de'Michieli Vitturi, Mattia; Corradini, Stefano; Salerno, Giuseppe; Merucci, Luca; Di Grazia, Giuseppe

    2017-02-01

    Syneruptive gas flux time series can, in principle, be retrieved from satellite maps of SO2 collected during and immediately after volcanic eruptions, and used to gain insights into the volcanic processes which drive the volcanic activity. Determination of the age and height of volcanic plumes are key prerequisites for such calculations. However, these parameters are challenging to constrain using satellite-based techniques. Here, we use imagery from OMI and GOME-2 satellite sensors and a novel numerical procedure based on back-trajectory analysis to calculate plume height as a function of position at the satellite measurement time together with plume injection height and time at a volcanic vent location. We applied this new procedure to three Etna eruptions (12 August 2011, 18 March 2012 and 12 April 2013) and compared our results with independent satellite and ground-based estimations. We also compare our injection height time-series with measurements of volcanic tremor, which reflects the eruption intensity, showing a good match between these two datasets. Our results are a milestone in progressing towards reliable determination of gas flux data from satellite-derived SO2 maps during volcanic eruptions, which would be of great value for operational management of explosive eruptions.

  6. Amplitude dependent closest tune approach

    CERN Document Server

    Tomas Garcia, Rogelio; Franchi, Andrea; Maclean, Ewen Hamish; CERN. Geneva. ATS Department

    2016-01-01

    Recent observations in the LHC point to the existence of an amplitude dependent closest tune approach. However this dynamical behavior and its underlying mechanism remain unknown. This effect is highly relevant for the LHC as an unexpectedly closest tune approach varying with amplitude modifies the frequency content of the beam and, hence, the Landau damping. Furthermore the single particle stability would also be affected by this effect as it would modify how particles with varying amplitudes approach and cross resonances. We present analytic derivations that lead to a mechanism generating an amplitude dependent closest tune approach.

  7. Graviton amplitudes from collinear limits of gauge amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Stieberger, Stephan, E-mail: stephan.stieberger@mpp.mpg.de [Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, 80805 München (Germany); Taylor, Tomasz R. [Department of Physics, Northeastern University, Boston, MA 02115 (United States)

    2015-05-11

    We express all tree-level graviton amplitudes in Einstein's gravity as the collinear limits of a linear combination of pure Yang–Mills amplitudes in which each graviton is represented by two gauge bosons, each of them carrying exactly one half of graviton's momentum and helicity.

  8. On the Period-Amplitude and Amplitude-Period Relationships

    Science.gov (United States)

    Wilson, Robert M.; Hathaway, David H.

    2008-01-01

    Examined are Period-Amplitude and Amplitude-Period relationships based on the cyclic behavior of the 12-month moving averages of monthly mean sunspot numbers for cycles 0.23, both in terms of Fisher's exact tests for 2x2 contingency tables and linear regression analyses. Concerning the Period-Amplitude relationship (same cycle), because cycle 23's maximum amplitude is known to be 120.8, the inferred regressions (90-percent prediction intervals) suggest that its period will be 131 +/- 24 months (using all cycles) or 131 +/- 18 months (ignoring cycles 2 and 4, which have the extremes of period, 108 and 164 months, respectively). Because cycle 23 has already persisted for 142 months (May 1996 through February 2008), based on the latter prediction, it should end before September 2008. Concerning the Amplitude-Period relationship (following cycle maximum amplitude versus preceding cycle period), because cycle 23's period is known to be at least 142 months, the inferred regressions (90-percent prediction intervals) suggest that cycle 24's maximum amplitude will be about less than or equal to 96.1 +/- 55.0 (using all cycle pairs) or less than or equal to 91.0 +/- 36.7 (ignoring statistical outlier cycle pairs). Hence, cycle 24's maximum amplitude is expected to be less than 151, perhaps even less than 128, unless cycle pair 23/24 proves to be a statistical outlier.

  9. Modeling volcanic ash dispersal

    CERN Document Server

    CERN. Geneva

    2010-01-01

    The assessment of volcanic fallout hazard is an important scientific, economic, and political issue, especially in densely populated areas. From a scientific point of view, considerable progress has been made during the last two decades through the use of increasingly powerful computational models and capabilities. Nowadays, models are used to quantify hazard...

  10. Self-potential anomalies in some Italian volcanic areas

    Directory of Open Access Journals (Sweden)

    C. Silenziario

    1996-06-01

    Full Text Available The study of Self-Potential (SP space and time variations in volcanic areas may provide useful information on both the geometrical structure of the volcanic apparatuses and the dynamical behaviour of the feeding and uprising systems. In this paper, the results obtained on the islands of Vulcano (Eolian arc and Ponza (Pontine archipelago and on the Mt. Somma-Vesuvius complex are shown. On the island of Vulcano and on the Mt. Somma-Vesuvius apparatus areal SP surveys were performed with the aim of evidencing anomalies closely associated to the zones of major volcanic activity. On the island of Vulcano a profile across the fumaroles along the crater rim of the Fossa Cone was also carried out in order to have a direct relationship between fumarolic fracture migration and flow rate and SP anomaly space and time variations. The areal survey on the island of Ponza, which is considered an inactive area, is assumed as a reference test with which to compare the amplitude and pattern of the anomalies in the active areas. A tentative interpretation of the SP anomalies in volcanic areas is suggested in terms of electrokinetic phenomena, related to the movement of fluids of both volcanic and non-volcanic origin.

  11. Assessing the Updip Spatial Offset of Tremor and Slip during ETS Events in Cascadia

    Science.gov (United States)

    Krogstad, R. D.; Schmidt, D. A.

    2015-12-01

    We investigate the updip spatial overlap of tremor and slip during recent episodic tremor and slip (ETS) events in Cascadia using a combination of forward and inverse models constrained by GPS, strainmeter, and tremor observations. Results from major ETS events in northern Cascadia suggest that, although there is significant spatial overlap, slow slip tends to extend further updip than tremor. ETS activity is thought to be dependent on a range of parameters, such as variable fluid pressures, temperature dependent physical properties, and facies changes. A spatial offset would indicant that tremor and slip are reflective of different physical conditions. While a clear offset of tremor and slip has been observed in multiple other subduction zones, a similar offset in Cascadia has remained difficult to constrain. Here we seek to establish whether the updip spatial offset is real in Cascadia and to quantify its extent. To complement GPS observations in Cascadia, we incorporate high fidelity strainmeter observations into inversions and sensitivity tests of iterative forward models. Tremor distributions are used as a proxy for slip and incorporated into slip models where parameters affecting the distribution and magnitude of slip are allowed to vary. These slip models are used to forward predict surface displacements and strains, which are then compared to the geodetic observations and inferred slip based on geodetic inversions. Results indicate that, while the tremor-derived slip distributions do a good job predicting the broad-scale surface deformation, the best-fit models have slip updip of the peak tremor activity. The fine-scale relationship of tremor and slip appears to vary on an event-by-event basis, where areas of high tremor density do not always correlate with increased surface displacements and vice-versa.

  12. Large amplitude oscillatory elongation flow

    DEFF Research Database (Denmark)

    Rasmussen, Henrik K.; Laillé, Philippe; Yu, Kaijia

    2008-01-01

    A filament stretching rheometer (FSR) was used for measuring the elongation flow with a large amplitude oscillative elongation imposed upon the flow. The large amplitude oscillation imposed upon the elongational flow as a function of the time t was defined as epsilon(t) =(epsilon) over dot(0)t + ...

  13. Closed string amplitudes as single-valued open string amplitudes

    Energy Technology Data Exchange (ETDEWEB)

    Stieberger, Stephan, E-mail: stephan.stieberger@mpp.mpg.de [Max-Planck-Institut für Physik, Werner-Heisenberg-Institut, 80805 München (Germany); Taylor, Tomasz R. [Department of Physics, Northeastern University, Boston, MA 02115 (United States)

    2014-04-15

    We show that the single trace heterotic N-point tree-level gauge amplitude A{sub N}{sup HET} can be obtained from the corresponding type I amplitude A{sub N}{sup I} by the single-valued (sv) projection: A{sub N}{sup HET}=sv(A{sub N}{sup I}). This projection maps multiple zeta values to single-valued multiple zeta values. The latter represent a subclass of multiple zeta values originating from single-valued multiple polylogarithms at unity. Similar relations between open and closed string amplitudes or amplitudes of different string vacua can be established. As a consequence the α{sup ′}-expansion of a closed string amplitude is dictated by that of the corresponding open string amplitude. The combination of single-valued projections, Kawai–Lewellen–Tye relations and Mellin correspondence reveal a unity of all tree-level open and closed superstring amplitudes together with the maximally supersymmetric Yang–Mills and supergravity theories.

  14. Episodic tremor and slip - a kinder and gentler variety of earthquake

    Science.gov (United States)

    Vidale, J. E.; Peng, Z.; Creager, K. C.

    2008-12-01

    Episodic Tremor and Slip (AKA ETS) is appearing numerous unsuspected places as seismic instruments and analysis gears up into the 21st century. From its initial and loudest lair in subduction zones, ETS observations have spread to strike-slip faults and fold-thrust belts. ETS differs from old-school earthquakes. ETS can last weeks while the grandest earthquakes run out of steam in minutes. ETS unleashes seismic moment roughly linearly with duration, as opposed to run-of-the- mill earthquakes, whose moment scales with the cube of duration. ETS has a redder spectrum and more emergent beginnings. ETS is more sensitive to stress perturbations, as revealed by susceptibility to triggering by teleseismic waves and amplitude modulation by weak tidal stressing. In the rare cases for which good location is possible, ETS most often unfolds near or well below the lower edge of the seismogenic portion of major faults, perhaps marking the transition between locked and freely slipping rheologies. Mechanically, it appears sensible that fluids play an integral role regulating the ETS process, although how fluids would be able to mediate ETS episodes spanning 100+ km of fault is a head- scratcher. Maybe ETS regions underlie most locked faults. Maybe ETS offers possibilities to delineate locked faults and detail their temporal loading with clues to when they will erupt. This story is still unfolding.

  15. Aseismic moment release associated with rapid tremor reversals in Cascadia

    Science.gov (United States)

    Hawthorne, J. C.; Bostock, M. G.; Royer, A. A.; Thomas, A.; Savard, G.

    2015-12-01

    We identify variations in slow slip moment rate associated with rapid tremor reversals (RTRs) beneath Vancouver Island, in Cascadia. The RTRs were identified by Royer et. al., 2015 with their high-quality tremor catalog based on low frequency earthquakes. In most of them, tremor propagates a few tens of kilometers over a few hours. We use PBO borehole strain data to search for aseismic moment rate variations associated with the reversals. We isolate components of strain that have high signal to noise ratios by avoiding components that have a strong response to atmospheric pressure. In the corrected strain data, the strain rate is systematically higher during the RTRs than during the 4 days surrounding them. On average, the strain rate increases by a factor of 2 during the reversals.This factor of 2 increase in strain rate can be roughly interpreted as a factor of 2 increase in moment rate. The location of slip moves by just a few tens of kilometers during the 4-day periods of interest, so the Green's functions do not change dramatically. If we scale this moment rate by the moment rate of the slow slip event, and account for the RTR durations, we estimate that each reversal releases a moment similar to that in a M 5 earthquake. If the along-dip width of the reversals is comparable to the width of the whole slow slip event, the estimated moment implies a stress drop of order 1 kPa. This is comparable to the tidal stresses and less than 10% of the slow slip stress drop. If the along-dip width of the RTRs is smaller---say 20 km---the aseismic moment implies a stress drop of order 5 kPa, only a factor of a few smaller than the slow slip stress drop.

  16. Quality of life and personality in essential tremor patients.

    Science.gov (United States)

    Lorenz, Delia; Schwieger, Daniel; Moises, Hans; Deuschl, Günther

    2006-08-01

    The aim of this study was to determine the impact of essential tremor (ET) on quality of life and its relation with tremor severity and the personality profile of ET patients. One hundred and five patients with definite or probable ET from an outpatient population were tested with the Short-Form 36-Item Health Survey (SF36) and the Eysenck Personality Questionnaire (EPQ-R). Compared to controls, the ET patients scored worse in all eight domains of the SF36. The physical component score (PCS) did not differ significantly from the normal population, whereas ET patients older than 40 years were significantly more affected with regard to the mental domains measured by the mental component score (MCS) with their median below the 20th percentile of the German controls. Tremor severity correlated with some of the physical domains and the PCS as well as with social function of the mental domains. ET patients showed significantly lower scores in the psychoticism (P) scale of the EPQ-R, with a median value on the 11th percentile of normal German population, indicating a more tender-minded personality type. The MCS correlated highly significant with the neuroticism (N) scale and extraversion (E) scale of EPQ-R. Multiple regression analysis identified age as the only predictive factor for the PCS and the N-scale as the only predictive factor for the MCS. Although ET is considered a pure movement disorder, the mental components of quality of life are more affected than the physical dimensions. A more controlled personality type may in part contribute to this.

  17. Exploring Hawaiian Volcanism

    Science.gov (United States)

    Poland, Michael P.; Okubo, Paul G.; Hon, Ken

    2013-02-01

    In 1912 the Hawaiian Volcano Observatory (HVO) was established by Massachusetts Institute of Technology professor Thomas A. Jaggar Jr. on the island of Hawaii. Driven by the devastation he observed while investigating the volcanic disasters of 1902 at Montagne Pelée in the Caribbean, Jaggar conducted a worldwide search and decided that Hawai`i provided an excellent natural laboratory for systematic study of earthquake and volcano processes toward better understanding of seismic and volcanic hazards. In the 100 years since HVO's founding, surveillance and investigation of Hawaiian volcanoes have spurred advances in volcano and seismic monitoring techniques, extended scientists' understanding of eruptive activity and processes, and contributed to development of global theories about hot spots and mantle plumes.

  18. Exploring Hawaiian volcanism

    Science.gov (United States)

    Poland, Michael P.; Okubo, Paul G.; Hon, Ken

    2013-01-01

    In 1912 the Hawaiian Volcano Observatory (HVO) was established by Massachusetts Institute of Technology professor Thomas A. Jaggar Jr. on the island of Hawaii. Driven by the devastation he observed while investigating the volcanic disasters of 1902 at Montagne Pelée in the Caribbean, Jaggar conducted a worldwide search and decided that Hawai‘i provided an excellent natural laboratory for systematic study of earthquake and volcano processes toward better understanding of seismic and volcanic hazards. In the 100 years since HVO’s founding, surveillance and investigation of Hawaiian volcanoes have spurred advances in volcano and seismic monitoring techniques, extended scientists’ understanding of eruptive activity and processes, and contributed to development of global theories about hot spots and mantle plumes.

  19. Mutation Analysis of HTRA2 Gene in Chinese Familial Essential Tremor and Familial Parkinson's Disease.

    Science.gov (United States)

    He, Ya-Chao; Huang, Pei; Li, Qiong-Qiong; Sun, Qian; Li, Dun-Hui; Wang, Tian; Shen, Jun-Yi; Du, Juan-Juan; Cui, Shi-Shuang; Gao, Chao; Fu, Rao; Chen, Sheng-Di

    2017-01-01

    Background. HTRA2 has already been nominated as PARK13 which may cause Parkinson's disease, though there are still discrepancies among these results. Recently, Gulsuner et al.'s study found that HTRA2 p.G399S is responsible for hereditary essential tremor and homozygotes of this allele develop Parkinson's disease by examining a six-generation family segregating essential tremor and essential tremor coexisting with Parkinson's disease. We performed this study to validate the condition of HTRA2 gene in Chinese familial essential tremor and familial Parkinson's disease patients, especially essential tremor. Methods. We directly sequenced all eight exons, exon-intron boundaries, and part of the introns in 101 familial essential tremor patients, 105 familial Parkinson's disease patients, and 100 healthy controls. Results. No exonic variant was identified, while one exon-intron boundary variant (rs2241028) and one intron variant (rs2241027) were detected, both with no clinical significance and uncertain function. There was no difference in allele, genotype, and haplotype between groups. Conclusions. HTRA2 exonic variant might be rare among Chinese Parkinson's disease and essential tremor patients with family history, and HTRA2 may not be the cause of familial Parkinson's disease and essential tremor in China.

  20. Motor network disruption in essential tremor : a functional and effective connectivity study

    NARCIS (Netherlands)

    Buijink, Arthur W. G.; van der Stouwe, A. M. Madelein; Broersma, Marja; Sharifi, Sarvi; Groot, Paul F. C.; Speelman, Johannes D.; Maurits, Natasha M.; van Rootselaar, Anne-Fleur

    2015-01-01

    Although involvement of the cerebello-thalamo-cortical network has often been suggested in essential tremor, the source of oscillatory activity remains largely unknown. To elucidate mechanisms of tremor generation, it is of crucial importance to study the dynamics within the

  1. Continuous theta-burst stimulation of the primary motor cortex in essential tremor

    DEFF Research Database (Denmark)

    Hellriegel, Helge; Schulz, Eva M; Siebner, Hartwig R

    2012-01-01

    We investigated whether essential tremor (ET) can be altered by suppressing the corticospinal excitability in the primary motor cortex (M1) with transcranial magnetic stimulation.......We investigated whether essential tremor (ET) can be altered by suppressing the corticospinal excitability in the primary motor cortex (M1) with transcranial magnetic stimulation....

  2. Motor imagery evokes increased somatosensory activity in parkinson's disease patients with tremor

    NARCIS (Netherlands)

    Helmich, R.C.G.; Bloem, B.R.; Toni, I.

    2012-01-01

    Parkinson's disease (PD) is surprisingly heterogeneous: some patients have a prominent resting tremor, while others never develop this symptom. Here we investigate whether the functional organization of the voluntary motor system differs between PD patients with and without resting tremor, and wheth

  3. Motor imagery evokes increased somatosensory activity in parkinson's disease patients with tremor.

    NARCIS (Netherlands)

    Helmich, R.C.G.; Bloem, B.R.; Toni, I.

    2012-01-01

    Parkinson's disease (PD) is surprisingly heterogeneous: some patients have a prominent resting tremor, while others never develop this symptom. Here we investigate whether the functional organization of the voluntary motor system differs between PD patients with and without resting tremor, and wheth

  4. Design and validation of a rehabilitation robotic exoskeleton for tremor assessment and suppression.

    Science.gov (United States)

    Rocon, E; Belda-Lois, J M; Ruiz, A F; Manto, M; Moreno, J C; Pons, J L

    2007-09-01

    Exoskeletons are mechatronic systems worn by a person in such a way that the physical interface permits a direct transfer of mechanical power and exchange of information. Upper limb robotic exoskeletons may be helpful for people with disabilities and/or limb weakness or injury. Tremor is the most common movement disorder in neurological practice. In addition to medication, rehabilitation programs, and deep brain stimulation, biomechanical loading has appeared as a potential tremor suppression alternative. This paper introduces the robotic exoskeleton called WOTAS (wearable orthosis for tremor assessment and suppression) that provides a means of testing and validating nongrounded control strategies for orthotic tremor suppression. This paper describes in detail the general concept for WOTAS, outlining the special features of the design and selection of system components. Two control strategies developed for tremor suppression with exoskeletons are described. These two strategies are based on biomechanical loading and notch filtering the tremor through the application of internal forces. Results from experiments using these two strategies on patients with tremor are summarized. Finally, results from clinical trials are presented, which indicate the feasibility of ambulatory mechanical suppression of tremor.

  5. Identifying unstable rock blocks by measuring micro-tremors and vibration on cliffs

    Science.gov (United States)

    Tanaka, H.; Fujisawa, K.; Asai, K.

    2008-01-01

    It is important to identify unstable rock blocks and take countermeasures to prevent sudden rock fall disasters. However, identifying such blocks visually is extremely difficult, so an identification method using peculiar features of unstable blocks must be developed. The method reported here uses a vibrometer, which is inexpensive and easy to operate. In order to assess the feasibility of the method, a field experiment was carried out on rock cliffs in three regions of Japan where unstable blocks are likely to exist. Vibrometers were set up on the cliffs to capture two types of vibration waves in three dimensions, i.e., micro-tremor and reactive vibration. The former type naturally exists all the time, while the latter is generated only by applying stimulation waves. At least one of the vibrometers was installed on stable baserock to compare the results with the wave patterns of unstable rock blocks. In addition to conventional items (amplitude, frequency spectrum, vibration particle trace), trace accumulation length, that is the accumulation of the trace length of a vibrating particle for ten seconds, was introduced to analyze the patterns for both types of wave. As a result, unstable rock blocks were found to generate higher amplitudes of vibration waves than stable rock blocks, and different patterns of frequency spectrum, direction of vibration particle trace, and trace accumulation length. Hence, vibrators were shown to be useful for identifying unstable rock blocks. In particular, by using trace accumulation length as an indicator, the stability of a block can be evaluated without generating stimulative waves, providing a direction for developing a cost-effective simple method for identifying unstable blocks in future.

  6. Hypertrophic Olivary Degeneration and Palatal or Oculopalatal Tremor

    Directory of Open Access Journals (Sweden)

    Caroline Tilikete

    2017-06-01

    Full Text Available Hypertrophic degeneration of the inferior olive is mainly observed in patients developing palatal tremor (PT or oculopalatal tremor (OPT. This syndrome manifests as a synchronous tremor of the palate (PT and/or eyes (OPT that may also involve other muscles from the branchial arches. It is associated with hypertrophic inferior olivary degeneration that is characterized by enlarged and vacuolated neurons, increased number and size of astrocytes, severe fibrillary gliosis, and demyelination. It appears on MRI as an increased T2/FLAIR signal intensity and enlargement of the inferior olive. There are two main conditions in which hypertrophic degeneration of the inferior olive occurs. The most frequent, studied, and reported condition is the development of PT/OPT and hypertrophic degeneration of the inferior olive in the weeks or months following a structural brainstem or cerebellar lesion. This “symptomatic” condition requires a destructive lesion in the Guillain–Mollaret pathway, which spans from the contralateral dentate nucleus via the brachium conjunctivum and the ipsilateral central tegmental tract innervating the inferior olive. The most frequent etiologies of destructive lesion are stroke (hemorrhagic more often than ischemic, brain trauma, brainstem tumors, and surgical or gamma knife treatment of brainstem cavernoma. The most accepted explanation for this symptomatic PT/OPT is that denervated olivary neurons released from inhibitory inputs enlarge and develop sustained synchronized oscillations. The cerebellum then modulates/accentuates this signal resulting in abnormal motor output in the branchial arches. In a second condition, PT/OPT and progressive cerebellar ataxia occurs in patients without structural brainstem or cerebellar lesion, other than cerebellar atrophy. This syndrome of progressive ataxia and palatal tremor may be sporadic or familial. In the familial form, where hypertrophic degeneration of the inferior olive may not

  7. Subdiffusion of volcanic earthquakes

    CERN Document Server

    Abe, Sumiyoshi

    2016-01-01

    A comparative study is performed on volcanic seismicities at Mt.Eyjafjallajokull in Iceland and Mt. Etna in Sicily, Italy, from the viewpoint of science of complex systems, and the discovery of remarkable similarities between them regarding their exotic spatio-temporal properties is reported. In both of the volcanic seismicities as point processes, the jump probability distributions of earthquakes are found to obey the exponential law, whereas the waiting-time distributions follow the power law. In particular, a careful analysis is made about the finite size effects on the waiting-time distributions, and accordingly, the previously reported results for Mt. Etna [S. Abe and N. Suzuki, EPL 110, 59001 (2015)] are reinterpreted. It is shown that spreads of the volcanic earthquakes are subdiffusive at both of the volcanoes. The aging phenomenon is observed in the "event-time-averaged" mean-squared displacements of the hypocenters. A comment is also made on presence/absence of long term memories in the context of t...

  8. Tectonic Tremor Triggered along Major Strike-Slip Faults around the World

    Science.gov (United States)

    Aiken, C.; Peng, Z.; Shelly, D. R.; Hill, D. P.; Gonzalez-Huizar, H.; Chao, K.; Zimmerman, J. P.; Douilly, R.; Deschamps, A.; Haase, J. S.; Calais, E.

    2013-12-01

    Over the last decade, deep tectonic tremor has been observed at several major plate-bounding faults around the Pacific Rim. Observations in these regions show that ambient tremor occurs spontaneously in association with geodetically detectable slow-slip events and that triggered tremor occurs in response to small stress perturbations arising from solid earth tides as well as passing seismic waves of a distant earthquake. Tremor generally occurs in the lower crust, beneath the seismogenic zone where earthquakes occur. In order to investigate the potential link between tremor and earthquake nucleation, further study of when, where, and how tremor occurs is needed. Here, we present a review of remotely triggered tectonic tremor in four strike-slip regions: (1) the Queen Charlotte Fault near Haida Gwaii, Canada, (2) the Eastern Denali Fault in Yukon, Canada, (3) the Enriquillo-Plantain Garden Fault in the southern Haiti peninsula, and (4) the Parkfield-Cholame segment of the San Andreas Fault near Parkfield, California. In Haida Gwaii, Yukon and Parkfield, we first compute the estimated dynamic stress for all magnitude ≥ 5.5 earthquakes based on the magnitude listed in the Advanced National Seismograph System (ANSS) earthquake catalog and epicentral distance to the region where tremor is observed. We then retrieve seismic data from local networks for earthquakes that are estimated to generate ≥ 1 kPa dynamic stress, without regard to epicentral distance. We characterize tremor triggered by these distant earthquakes as broadband signals with long duration that are coincident with surface waves from a distant event or occur in a large cluster immediately following the teleseismic wavetrain. In Haiti, a temporary seismic network was deployed shortly after the 2010/01/12 Mw7.0 Haiti earthquake. Thus, we are only able to report on triggering by the 2010/02/27 Mw8.8 Maule, Chile earthquake that occurred shortly thereafter. In Parkfield, we use a low-frequency earthquake

  9. Thalamic deep brain stimulation for the treatment of tremor due to multiple sclerosis: a prospective study of tremor and quality of life.

    Science.gov (United States)

    Berk, Caglar; Carr, Jason; Sinden, Marci; Martzke, Jeff; Honey, Christopher R

    2002-10-01

    In several studies a significant reduction in tremor after thalamic deep brain stimulation (DBS) has been reported among patients with multiple sclerosis (MS). It has not been determined if this results in an improved quality of life. In this study the authors prospectively evaluated the effects of thalamic DBS on tremor and quality of life. Videotapes of the patients' tremor were made preoperatively and 2 and 12 months postoperatively, and tremor was scored by a neurologist blinded to the treatment. Patients were tested pre- and postoperatively to measure any changes in their reported ability to perform selected activities of daily living and in their health-related quality of life. Patients were asked to complete a questionnaire about their satisfaction with the surgery. Postoperative changes were examined using paired t-tests. There were significant reductions in postural, action, and overall tremor at 2 and 12 months postoperatively. The patients' reported ability to feed themselves was significantly improved 2 months after surgery (p = 0.01). There were short-term trends toward improvement in reported dressing ability, personal hygiene, and writing. There were no significant changes in the SF-36 subscales or total score. In this cohort of patients with MS who suffered from tremor, thalamic DBS significantly improved their tremor and ability to feed themselves. Patient satisfaction with the procedure, however, was variable. Preoperative patient education about what functions might (and might not) be improved is crucial to avoid unrealistic expectations. Our results indicate that younger patients with MS tremor who had a shorter disease duration and no superimposed ataxia benefited most from this surgery.

  10. Tremor-genic slow slip regions may be deeper and warmer and may slip slower than non-tremor-genic regions

    Science.gov (United States)

    Montgomery-Brown, Emily; Syracuse, Ellen M.

    2015-01-01

    Slow slip events (SSEs) are observed worldwide and often coincide with tectonic tremor. Notable examples of SSEs lacking observed tectonic tremor, however, occur beneath Kīlauea Volcano, Hawaii, the Boso Peninsula, Japan, near San Juan Bautista on the San Andreas Fault, California, and recently in Central Ecuador. These SSEs are similar to other worldwide SSEs in many ways (e.g., size or duration), but lack the concurrent tectonic tremor observed elsewhere; instead, they trigger swarms of regular earthquakes. We investigate the physical conditions that may distinguish these non-tremor-genic SSEs from those associated with tectonic tremor, including slip velocity, pressure, temperature, fluids, and fault asperities, although we cannot eliminate the possibility that tectonic tremor may be obscured in highly attenuating regions. Slip velocities of SSEs at Kīlauea Volcano (∼10−6 m/s) and Boso Peninsula (∼10−7 m/s) are among the fastest SSEs worldwide. Kīlauea Volcano, the Boso Peninsula, and Central Ecuador are also among the shallowest SSEs worldwide, and thus have lower confining pressures and cooler temperatures in their respective slow slip zones. Fluids also likely contribute to tremor generation, and no corresponding zone of high vp/vs has been noted at Kīlauea or Boso. We suggest that the relatively faster slip velocities at Kīlauea Volcano and the Boso Peninsula result from specific physical conditions that may also be responsible for triggering swarms of regular earthquakes adjacent to the slow slip, while different conditions produce slower SSE velocities elsewhere and trigger tectonic tremor.

  11. Integration of Osteopathic Manual Treatments in Management of Cervical Dystonia with Tremor: A Case Series

    Science.gov (United States)

    Halimi, Miriam; Leder, Adena; Mancini, Jayme D.

    2017-01-01

    Background Cervical dystonia, also known as spasmodic torticollis, is a chronic disorder in which patients exhibit involuntary repetitive contractions of neck muscles resulting in abnormal postures or movements. Occasionally, there is also a dystonic head tremor. The underlying mechanisms for cervical dystonia and dystonic tremor are not clear, and treatments are limited. Case Report In the present cases, two females with head tremor starting in adolescence developed worsening symptoms of cervical dystonia with dystonic tremor in their 60s. On osteopathic physical examination, both had a vertical type strain to the sphenobasilar synchondrosis. Discussion Vertical strains are more frequently found in patients after head trauma, congenital or later in life, than in healthy patients, and head trauma may have been a precipitating factor in these patients. There were improvements in cervical dystonia symptoms, including tremor, in both patients after osteopathic manual treatment. PMID:28119789

  12. Disruption of nigrostriatal and cerebellothalamic pathways in dopamine responsive Holmes' tremor.

    Science.gov (United States)

    Seidel, S; Kasprian, G; Leutmezer, F; Prayer, D; Auff, E

    2009-08-01

    Holmes' tremor is an unusual combination of rest, postural and kinetic tremor of the extremities. Medical treatment of this condition still remains unsatisfactory. The case of a 20-year-old female patient is reported who developed right-sided Holmes' tremor 9 months after a left-sided, cavernoma induced midbrain/pontine haemorrhage at the age of 16 years. Beta-CIT single photon emission computed tomography revealed abolished dopamine transporter activity in the left basal ganglia and striatum, in accordance with missing ipsilateral tegmento-frontal connectivity (medial forebrain bundle), demonstrated by diffusion tensor MRI. Tractography showed reduced fibre connectivity of the superior and middle cerebellar peduncles on the lesioned side. Administration of pramipexole and L-DOPA led to a clinically significant reduction in tremor severity. In conclusion, our results support the notion that Holmes' tremor was a result of diminished striatal dopaminergic input in our patient.

  13. Quantification of a secondary task-specific tremor in a violinist after a temporal lobectomy.

    Science.gov (United States)

    Lee, André; Tominaga, Kenta; Furuya, Shinichi; Miyazaki, Fumio; Altenmüller, Eckart

    2014-01-01

    Task-specific tremors (TSTs) 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 TST of the right arm only while playing the violin 4 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.

  14. Parkinsonian Rest Tremor Is Associated With Modulations of Subthalamic High-Frequency Oscillations.

    Science.gov (United States)

    Hirschmann, Jan; Butz, Markus; Hartmann, Christian J; Hoogenboom, Nienke; Özkurt, Tolga E; Vesper, Jan; Wojtecki, Lars; Schnitzler, Alfons

    2016-10-01

    High frequency oscillations (>200 Hz) have been observed in the basal ganglia of PD patients and were shown to be modulated by the administration of levodopa and voluntary movement. The objective of this study was to test whether the power of high-frequency oscillations in the STN is associated with spontaneous manifestation of parkinsonian rest tremor. The electromyogram of both forearms and local field potentials from the STN were recorded in 11 PD patients (10 men, age 58 [9.4] years, disease duration 9.2 [6.3] years). Patients were recorded at rest and while performing repetitive hand movements before and after levodopa intake. High-frequency oscillation power was compared across epochs containing rest tremor, tremor-free rest, or voluntary movement and related to the tremor cycle. We observed prominent slow (200-300 Hz) and fast (300-400 Hz) high-frequency oscillations. The ratio between slow and fast high-frequency oscillation power increased when tremor became manifest. This increase was consistent across nuclei (94%) and occurred in medication ON and OFF. The ratio outperformed other potential markers of tremor, such as power at individual tremor frequency, beta power, or low gamma power. For voluntary movement, we did not observe a significant difference when compared with rest or rest tremor. Finally, rhythmic modulations of high-frequency oscillation power occurred within the tremor cycle. Subthalamic high-frequency oscillation power is closely linked to the occurrence of parkinsonian rest tremor. The balance between slow and fast high-frequency oscillation power combines information on motor and medication state. © 2016 International Parkinson and Movement Disorder Society. © 2016 International Parkinson and Movement Disorder Society.

  15. The complete frequency spectrum of physiological tremor can be recreated by broadband mechanical or electrical drive.

    Science.gov (United States)

    Vernooij, Carlijn Andrea; Lakie, Martin; Reynolds, Raymond Francis

    2015-01-15

    Two frequency peaks of variable preponderance have been reported for human physiological finger tremor. The high-frequency peak (20-25 Hz, seen only in postural tremor) is generally attributed to mechanical resonance, whereas the lower frequency peak (8-12 Hz, seen in both postural and kinetic tremor) is usually attributed to synchronous central or reflexive neural drive. In this study, we determine whether mechanical resonance could generate both peaks. In relaxed subjects, an artificial finger tremor was evoked by random mechanical perturbations of the middle finger or random electrical muscular stimulation of the finger extensor muscle. The high and the low frequencies observed in physiological tremor could both be created by either type of artificial input at appropriate input intensity. Resonance, inferred from cross-spectral gain and phase, occurred at both frequencies. To determine any neural contribution, we compared truly passive subjects with those who exhibited some electromyographic (EMG) activity in the finger extensor; artificially created tremor spectra were almost identical between groups. We also applied electrical stimuli to two clinically deafferented subjects lacking stretch reflexes. They exhibited the same artificial tremor spectrum as control subjects. These results suggest that both typical physiological finger tremor frequencies can be reproduced by random artificial input; neither requires synchronized neural input. We therefore suggest that mechanical resonance could generate both dominant frequency peaks characteristic of physiological finger tremor. The inverse relationship between the input intensity and the resulting tremor frequency can be explained by a movement-dependent reduction in muscle stiffness, a conjecture we support using a simple computational model.

  16. Using Seismic Arrays to Detect Triggered and Ambient Tremor in Taiwan

    Science.gov (United States)

    Sun, W.; Peng, Z.; Lin, C.; Chao, K.

    2013-12-01

    Deep tectonic tremor triggered by teleseismic surface waves have been recently observed in the southern Central Range in Taiwan, an arc-continental type collision environment. Aiming to capture more tremor events, we installed two dense 36-element, small-aperture seismic arrays in 2011 around the Liouguei and Lidao areas, which are located about 20 km in southwest and northeast to the tremor sources. In each array, short-period, vertical-channel GS-11D sensors with 4.5Hz natural frequency seismometers were laid out on the relatively flat parts of the mountain areas with a spacing of approximately 100 by 80 meters. We had successfully recorded continuously for a total of 4,034 hours in 2011. As expected, the two arrays recorded tremor bursts triggered by the great Tohoku earthquake (Mw=9.0) on March 11, 2011. We apply the broadband frequency wavenumber (BBFK) beamforming method to measure the back-azimuth and incident angles for each tremor burst and through the whole data set. Our initial results show that obtained array parameters closely match those predicted from locations using tremor envelope cross-correlations (WECC) and we detect more tremor duration by BBFK than WECC. We further use a moving-window grid-search (MWGS) method to detect regular earthquakes. Our result indicates the southwestern array provides more stable results than the northeastern array. Our next step is to apply the same MWGS procedure to detect ambient tremor recorded by the southwestern array. Our systematic analysis of deep tremor in Taiwan could help to better understand critical conditions related to tremor occurrence and fault mechanics at the bottom of the seismogenic layer.

  17. Scattering amplitudes in gauge theories

    CERN Document Server

    Henn, Johannes M

    2014-01-01

    At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge.   These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum ...

  18. Positive Amplitudes In The Amplituhedron

    CERN Document Server

    Arkani-Hamed, Nima; Trnka, Jaroslav

    2014-01-01

    The all-loop integrand for scattering amplitudes in planar N = 4 SYM is determined by an "amplitude form" with logarithmic singularities on the boundary of the amplituhedron. In this note we provide strong evidence for a new striking property of the superamplitude, which we conjecture to be true to all loop orders: the amplitude form is positive when evaluated inside the amplituhedron. The statement is sensibly formulated thanks to the natural "bosonization" of the superamplitude associated with the amplituhedron geometry. However this positivity is not manifest in any of the current approaches to scattering amplitudes, and in particular not in the cellulations of the amplituhedron related to on-shell diagrams and the positive grassmannian. The surprising positivity of the form suggests the existence of a "dual amplituhedron" formulation where this feature would be made obvious. We also suggest that the positivity is associated with an extended picture of amplituhedron geometry, with the amplituhedron sitting...

  19. Model selection for amplitude analysis

    CERN Document Server

    Guegan, Baptiste; Stevens, Justin; Williams, Mike

    2015-01-01

    Model complexity in amplitude analyses is often a priori under-constrained since the underlying theory permits a large number of amplitudes to contribute to most physical processes. The use of an overly complex model results in reduced predictive power and worse resolution on unknown parameters of interest. Therefore, it is common to reduce the complexity by removing from consideration some subset of the allowed amplitudes. This paper studies a data-driven method for limiting model complexity through regularization during regression in the context of a multivariate (Dalitz-plot) analysis. The regularization technique applied greatly improves the performance. A method is also proposed for obtaining the significance of a resonance in a multivariate amplitude analysis.

  20. Fragile X-associated tremor/ataxia syndrome.

    Science.gov (United States)

    Hagerman, Paul J; Hagerman, Randi J

    2015-03-01

    Fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder that affects some but not all carriers of small, noncoding CGG-repeat expansions (55-200 repeats; premutation) within the fragile X gene (FMR1). Principal features of FXTAS include intention tremor, cerebellar ataxia, Parkinsonism, memory and executive function deficits, autonomic dysfunction, brain atrophy with white matter disease, and cognitive decline. Although FXTAS was originally considered to be confined to the premutation range, rare individuals with a gray zone (45-54 repeats) or an unmethylated full mutation (>200 repeats) allele have now been described, the constant feature of the disorder remaining the requirement for FMR1 expression, in contradistinction to the gene silencing mechanism of fragile X syndrome. Although transcriptional activity is required for FXTAS pathogenesis, the specific trigger(s) for FXTAS pathogenesis remains elusive, highlighting the need for more research in this area. This need is underscored by recent neuroimaging findings of changes in the central nervous system that consistently appear well before the onset of clinical symptoms, thus creating an opportunity to delay or prevent the appearance of FXTAS. © 2015 New York Academy of Sciences.

  1. A double-correlation tremor-location method

    Science.gov (United States)

    Li, Ka Lok; Sgattoni, Giulia; Sadeghisorkhani, Hamzeh; Roberts, Roland; Gudmundsson, Olafur

    2017-02-01

    A double-correlation method is introduced to locate tremor sources based on stacks of complex, doubly-correlated tremor records of multiple triplets of seismographs back projected to hypothetical source locations in a geographic grid. Peaks in the resulting stack of moduli are inferred source locations. The stack of the moduli is a robust measure of energy radiated from a point source or point sources even when the velocity information is imprecise. Application to real data shows how double correlation focuses the source mapping compared to the common single correlation approach. Synthetic tests demonstrate the robustness of the method and its resolution limitations which are controlled by the station geometry, the finite frequency of the signal, the quality of the used velocity information and noise level. Both random noise and signal or noise correlated at time shifts that are inconsistent with the assumed velocity structure can be effectively suppressed. Assuming a surface wave velocity, we can constrain the source location even if the surface wave component does not dominate. The method can also in principle be used with body waves in 3-D, although this requires more data and seismographs placed near the source for depth resolution.

  2. Linking Essential Tremor to the Cerebellum: Physiological Evidence.

    Science.gov (United States)

    Filip, Pavel; Lungu, Ovidiu V; Manto, Mario-Ubaldo; Bareš, Martin

    2016-12-01

    Essential tremor (ET), clinically characterized by postural and kinetic tremors, predominantly in the upper extremities, originates from pathological activity in the dynamic oscillatory network comprising the majority of nodes in the central motor network. Evidence indicates dysfunction in the thalamus, the olivocerebellar loops, and intermittent cortical engagement. Pathology of the cerebellum, a structure with architecture intrinsically predisposed to oscillatory activity, has also been implicated in ET as shown by clinical, neuroimaging, and pathological studies. Despite electrophysiological studies assessing cerebellar impairment in ET being scarce, their impact is tangible, as summarized in this review. The electromyography-magnetoencephalography combination provided the first direct evidence of pathological alteration in cortico-subcortical communication, with a significant emphasis on the cerebellum. Furthermore, complex electromyography studies showed disruptions in the timing of agonist and antagonist muscle activation, a process generally attributed to the cerebellum. Evidence pointing to cerebellar engagement in ET has also been found in electrooculography measurements, cerebellar repetitive transcranial magnetic stimulation studies, and, indirectly, in complex analyses of the activity of the ventral intermediate thalamic nucleus (an area primarily receiving inputs from the cerebellum), which is also used in the advanced treatment of ET. In summary, further progress in therapy will require comprehensive electrophysiological and physiological analyses to elucidate the precise mechanisms leading to disease symptoms. The cerebellum, as a major node of this dynamic oscillatory network, requires further study to aid this endeavor.

  3. Knowledge gaps and research recommendations for essential tremor.

    Science.gov (United States)

    Hopfner, Franziska; Haubenberger, Dietrich; Galpern, Wendy R; Gwinn, Katrina; Van't Veer, Ashlee; White, Samantha; Bhatia, Kailash; Adler, Charles H; Eidelberg, David; Ondo, William; Stebbins, Glenn T; Tanner, Caroline M; Helmich, Rick C; Lenz, Fred A; Sillitoe, Roy V; Vaillancourt, David; Vitek, Jerrold L; Louis, Elan D; Shill, Holly A; Frosch, Matthew P; Foroud, Tatiana; Kuhlenbäumer, Gregor; Singleton, Andrew; Testa, Claudia M; Hallett, Mark; Elble, Rodger; Deuschl, Günther

    2016-12-01

    Essential tremor (ET) is a common cause of significant disability, but its etiologies and pathogenesis are poorly understood. Research has been hampered by the variable definition of ET and by non-standardized research approaches. The National Institute of Neurological Disorders and Stroke (USA) invited experts in ET and related fields to discuss current knowledge, controversies, and gaps in our understanding of ET and to develop recommendations for future research. Discussion focused on phenomenology and phenotypes, therapies and clinical trials, pathophysiology, pathology, and genetics. Across all areas, the need for collaborative and coordinated research on a multinational level was expressed. Standardized data collection using common data elements for genetic, clinical, neurophysiological, and pathological studies was recommended. Large cohorts of patients should be studied prospectively to collect bio-samples, characterize the natural history of the clinical syndrome including patient-oriented outcomes, investigate potential etiologies of various phenotypes, and identify pathophysiological mechanisms. In particular, cellular and system-level mechanisms of tremor oscillations should be elucidated because they may yield effective therapeutic targets and biomarkers. A neuropathology consortium was recommended to standardize postmortem analysis and further characterize neuropathological observations in the cerebellum and elsewhere. Furthermore, genome-wide association studies on large patient cohorts (>10,000 patients) may allow the identification of common genes contributing to risk, and whole exome or genome sequencing may enable the identification of genetic risk and causal mutations in cohorts and well-characterized families.

  4. The feasibility of using acoustic markers of speech for optimizing patient outcomes during randomized amplitude variation in deep brain stimulation: a proof of principle methods study

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    Adam P Vogel

    2015-07-01

    Full Text Available Background: Deep brain stimulation (DBS is an effective treatment for reducing symptoms of tremor. A common and typically subjectively determined adverse effect of DBS is dysarthria. Current assessment protocols are driven by the qualitative judgements of treating clinicians and lack the sensitivity and objectivity required to optimize patient outcomes where multiple stimulation parameters are trialled. Objective: To examine the effect of DBS on speech in patients receiving stimulation to the posterior sub-thalamic area (PSA via randomized manipulation of amplitude parameters.Methods: Six patients diagnosed with tremor receiving treatment via DBS of the PSA were assessed within a double-blinded, within-subjects experimental protocol. Amplitude (i.e., voltage or current was randomly adjusted across 10 settings while speech samples (e.g., sustained vowel, counting to 10 were recorded to identify the patient-specific settings required for optimal therapeutic benefit (reduced tremor with minimal adverse effects (altered speech. Speech production between stimulation parameters was quantified using acoustic analysis.Results: Speech changed as a response to DBS but those changes were not uniform across patients nor were they generally in line with changes in amplitude with the exception of reduced vocal control and increased mean silence length in two patients. Speech outcomes did not correlate with changes in tremor.Conclusion(s: Intra-individual changes in speech were detected as a response to modified amplitude however no clear pattern was observed across patients as a group. The use of objective acoustic measures allows for quantification of speech changes during DBS optimization protocols, even when those changes are subtle and potentially difficult to detect perceptually.

  5. Volcanism on Mars. Chapter 41

    Science.gov (United States)

    Zimbelman, J. R.; Garry, W. B.; Bleacher, J. E.; Crown, D. A.

    2015-01-01

    Spacecraft exploration has revealed abundant evidence that Mars possesses some of the most dramatic volcanic landforms found anywhere within the solar system. How did a planet half the size of Earth produce volcanoes like Olympus Mons, which is several times the size of the largest volcanoes on Earth? This question is an example of the kinds of issues currently being investigated as part of the space-age scientific endeavor called "comparative planetology." This chapter summarizes the basic information currently known about volcanism on Mars. The volcanoes on Mars appear to be broadly similar in overall morphology (although, often quite different in scale) to volcanic features on Earth, which suggests that Martian eruptive processes are not significantly different from the volcanic styles and processes on Earth. Martian volcanoes are found on terrains of different age, and Martian volcanic rocks are estimated to comprise more than 50% of the Martian surface. This is in contrast to volcanism on smaller bodies such as Earth's Moon, where volcanic activity was mainly confined to the first half of lunar history (see "Volcanism on the Moon"). Comparative planetology supports the concept that volcanism is the primary mechanism for a planetary body to get rid of its internal heat; smaller bodies tend to lose their internal heat more rapidly than larger bodies (although, Jupiter's moon Io appears to contradict this trend; Io's intense volcanic activity is powered by unique gravitational tidal forces within the Jovian system; see "Volcanism on Io"), so that volcanic activity on Mars would be expected to differ considerably from that found on Earth and the Moon.

  6. Spatial and Temporal Comparisons of Tremor and Slow Slip in Cascadia

    Science.gov (United States)

    Hall, K.; Houston, H.; Schmidt, D. A.

    2015-12-01

    Tremor is often thought to be a proxy for slip during ETS events and has been shown to have a relatively abrupt updip boundary, implying an abrupt updip limit of slip. However, as shown by Houston (AGU abstract, 2012) and Hall and Houston (AGU abstract, 2014), slip inferred from GPS extended updip of the seismically-detected tremor in the 2010 M6.8 and 2012 M6.7 ETS events. If slip extending updip of tremor is a persistent phenomena, tremor cannot be directly used as a proxy for slip. Following the methods used on the 2010 and 2012 ETS event, we found that the August 2009 ETS around Portland, OR also showed slip updip of tremor. Principal Component Analysis was implemented to automatically select the direction and magnitude of the maximum displacement vector. Our Green's functions use the Okada formulation of buried rectangular faults in a halfspace for a grid of 8x8 km subfaults based on the McCrory slab model. We then performed static inversions with 2nd order Tikhonov regularization to find slip on the fault surface. We also compared two different inversions for 2009, one where slip was allowed on a broad regional grid and a tremor-restricted inversion (TRI) where slip was restricted to subfaults in which tremor occurred. We found the 2009 ETS event released the equivalent of a M6.8 in slip. We also found that, as in the previous ETSs, the TRI forced up to 10 cm of slip to the updip edge of the grid, which is exceeds the amount of plate convergence expected in the inter-ETS periods and is therefore physically unsustainable over several ETS events. The excess slip along the updip edge in the TRI models also suggests that the geodetic data prefer slip with a larger footprint than the spatial pattern of tremor, and supports our conclusion that tremor does not represent all of the slip during an ETS event. We see consistent and clear spatial relationship between tremor and slip with some slip occurring updip of tremor. Our static inversions show where slip is

  7. Volcanic Ash Nephelometer Probe Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced dropsondes that could effectively be guided through atmospheric regions of interest such as volcanic plumes may enable unprecedented observations of...

  8. Volcanic Eruptions and Climate

    Science.gov (United States)

    Robock, A.

    2012-12-01

    Large volcanic eruptions inject sulfur gases into the stratosphere, which convert to sulfate aerosols with an e-folding residence time of about one year. The radiative and chemical effects of these aerosol clouds produce responses in the climate system. Observations and numerical models of the climate system show that volcanic eruptions produce global cooling and were the dominant natural cause of climate change for the past millennium, on timescales from annual to century. Major tropical eruptions produce winter warming of Northern Hemisphere continents for one or two years, while high latitude eruptions in the Northern Hemisphere weaken the Asian and African summer monsoon. The Toba supereruption 74,000 years ago caused very large climate changes, affecting human evolution. However, the effects did not last long enough to produce widespread glaciation. An episode of four large decadally-spaced eruptions at the end of the 13th century C.E. started the Little Ice Age. Since the Mt. Pinatubo eruption in the Philippines in 1991, there have been no large eruptions that affected climate, but the cumulative effects of small eruptions over the past decade had a small effect on global temperature trends. The June 13, 2011 Nabro eruption in Eritrea produced the largest stratospheric aerosol cloud since Pinatubo, and the most of the sulfur entered the stratosphere not by direct injection, but by slow lofting in the Asian summer monsoon circulation. Volcanic eruptions warn us that while stratospheric geoengineering could cool the surface, reducing ice melt and sea level rise, producing pretty sunsets, and increasing the CO2 sink, it could also reduce summer monsoon precipitation, destroy ozone, allowing more harmful UV at the surface, produce rapid warming when stopped, make the sky white, reduce solar power, perturb the ecology with more diffuse radiation, damage airplanes flying in the stratosphere, degrade astronomical observations, affect remote sensing, and affect

  9. System of Volcanic activity

    Directory of Open Access Journals (Sweden)

    P. HÉDERVARI

    1972-06-01

    Full Text Available A comparison is made among the systems of B. G.
    Escher (3, of R. W. van Bemmelen (1 and that of the author (4. In this
    connection, on the basis of Esclier's classification, the terms of "constructiv
    e " and "destructive" eruptions are introduced into the author's system and
    at the same time Escher's concept on the possible relation between the depth
    of magma-chamber and the measure of the gas-pressure is discussed briefly.
    Three complementary remarks to the first paper (4 011 the subject of system
    of volcanic activity are added.

  10. Computing Maximally Supersymmetric Scattering Amplitudes

    Science.gov (United States)

    Stankowicz, James Michael, Jr.

    This dissertation reviews work in computing N = 4 super-Yang--Mills (sYM) and N = 8 maximally supersymmetric gravity (mSUGRA) scattering amplitudes in D = 4 spacetime dimensions in novel ways. After a brief introduction and overview in Ch. 1, the various techniques used to construct amplitudes in the remainder of the dissertation are discussed in Ch. 2. This includes several new concepts such as d log and pure integrand bases, as well as how to construct the amplitude using exactly one kinematic point where it vanishes. Also included in this chapter is an outline of the Mathematica package on shell diagrams and numerics.m (osdn) that was developed for the computations herein. The rest of the dissertation is devoted to explicit examples. In Ch. 3, the starting point is tree-level sYM amplitudes that have integral representations with residues that obey amplitude relations. These residues are shown to have corresponding residue numerators that allow a double copy prescription that results in mSUGRA residues. In Ch. 4, the two-loop four-point sYM amplitude is constructed in several ways, showcasing many of the techniques of Ch. 2; this includes an example of how to use osdn. The two-loop five-point amplitude is also presented in a pure integrand representation with comments on how it was constructed from one homogeneous cut of the amplitude. On-going work on the two-loop n-point amplitude is presented at the end of Ch. 4. In Ch. 5, the three-loop four-point amplitude is presented in the d log representation and in the pure integrand representation. In Ch. 6, there are several examples of four- through seven-loop planar diagrams that illustrate how considerations of the singularity structure of the amplitude underpin dual-conformal invariance. Taken with the previous examples, this is additional evidence that the structure known to exist in the planar sector extends to the full theory. At the end of this chapter is a proof that all mSUGRA amplitudes have a pole at

  11. Head and Arm Tremor in X-linked Spinal and Bulbar Muscular Atrophy

    Science.gov (United States)

    Aicua, Irene; Verhagen, Okker; Arenaza, Naroa; Cubo, Esther

    2014-01-01

    Background X-linked spinal and bulbar muscular atrophy (SBMA) is a rare adult-onset neuronopathy. Although tremor is known to occur in this disease, the number of reported cases of SBMA with tremor is rare, and the number with videotaped documentation is exceedingly rare. Our aim was to describe/document the characteristic signs of tremor in spinal and bulbar muscular atrophy. Case Report We report a case of a 58-year-old male with a positive family history of tremor. On examination, the patient had jaw and hand tremors but he also exhibited gynecomastia, progressive bulbar paresis, and wasting and weakness primarily in the proximal limb muscles. The laboratory tests revealed an elevated creatine phosphokinase. Genetic testing was positive for X-SBMA, with 42 CAG repeats. Discussion Essential tremor is one of the most common movement disorders, yet it is important for clinicians to be aware of the presence of other distinguishing features that point to alternative diagnoses. The presence of action tremor associated with muscle atrophy and gynecomastia should lead to a suspicion of SBMA. PMID:25374767

  12. Role of altered cerebello-thalamo-cortical network in the neurobiology of essential tremor

    Energy Technology Data Exchange (ETDEWEB)

    Lenka, Abhishek; Bhalsing, Ketaki Swapnil; Jhunjhunwala, Ketan [National Institute of Mental Health and Neurosciences, Department of Neurology, Bangalore, Karnataka (India); National Institute of Mental Health and Neurosciences, Department of Clinical Neurosciences, Bangalore, Karnataka (India); Panda, Rajanikant; Saini, Jitender; Bharath, Rose Dawn [National Institute of Mental Health and Neurosciences, Department of Neuroimaging and Interventional Radiology, Bangalore, Karnataka (India); Naduthota, Rajini M.; Yadav, Ravi; Pal, Pramod Kumar [National Institute of Mental Health and Neurosciences, Department of Neurology, Bangalore, Karnataka (India)

    2017-02-15

    Essential tremor (ET) is the most common movement disorder among adults. Although ET has been recognized as a mono-symptomatic benign illness, reports of non-motor symptoms and non-tremor motor symptoms have increased its clinical heterogeneity. The neural correlates of ET are not clearly understood. The aim of this study was to understand the neurobiology of ET using resting state fMRI. Resting state functional MR images of 30 patients with ET and 30 age- and gender-matched healthy controls were obtained. The functional connectivity of the two groups was compared using whole-brain seed-to-voxel-based analysis. The ET group had decreased connectivity of several cortical regions especially of the primary motor cortex and the primary somatosensory cortex with several right cerebellar lobules compared to the controls. The thalamus on both hemispheres had increased connectivity with multiple posterior cerebellar lobules and vermis. Connectivity of several right cerebellar seeds with the cortical and thalamic seeds had significant correlation with an overall score of Fahn-Tolosa-Marin tremor rating scale (FTM-TRS) as well as the subscores for head tremor and limb tremor. Seed-to-voxel resting state connectivity analysis revealed significant alterations in the cerebello-thalamo-cortical network in patients with ET. These alterations correlated with the overall FTM scores as well as the subscores for limb tremor and head tremor in patients with ET. These results further support the previous evidence of cerebellar pathology in ET. (orig.)

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

    Science.gov (United States)

    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.

  14. Deep brain stimulation or thalamotomy in fragile X-associated tremor/ataxia syndrome? Case report.

    Science.gov (United States)

    Tamás, Gertrúd; Kovács, Norbert; Varga, Noémi Ágnes; Barsi, Péter; Erőss, Loránd; Molnár, Mária Judit; Balás, István

    2016-01-01

    We present the case of a 66-year-old man who has been treated for essential tremor since the age of 58. He developed mild cerebellar gait ataxia seven years after tremor onset. Moderate, global brain atrophy was identified on MRI scans. At the age of 68, only temporary tremor relief could be achieved by bilateral deep brain stimulation of the ventral intermedius nucleus of the thalamus. Bilateral stimulation of the subthalamic nucleus also resulted only in transient improvement. In the meantime, progressive gait ataxia and tetraataxia developed accompanied by other cerebellar symptoms, such as nystagmus and scanning speech. These correlated with progressive development of bilateral symmetric hyperintensity of the middle cerebellar peduncles on T2 weighted MRI scans. Genetic testing revealed premutation of the FMR1 gene, establishing the diagnosis of fragile X-associated tremor/ataxia syndrome. Although this is a rare disorder, it should be taken into consideration during preoperative evaluation of essential tremor. Postural tremor ceased two years later after thalamotomy on the left side, while kinetic tremor of the right hand also improved.

  15. Augmented visual feedback counteracts the effects of surface muscular functional electrical stimulation on physiological tremor.

    Science.gov (United States)

    Grimaldi, Giuliana; Fernandez, Alfredo; Manto, Mario

    2013-09-24

    Recent studies suggest that surface muscular functional electrical stimulation (FES) might suppress neurological upper limb tremor. We assessed its effects on upper limb physiological tremor, which is mainly driven by mechanical-reflex oscillations. We investigated the interaction between FES and augmented visual feedback, since (a) most daily activities are performed using visual cues, and (b) augmented visual feedback exacerbates upper limb tremor. 10 healthy subjects (23.4 ± 7.7 years) performed 2 postural tasks with combinations of FES (4 sites; frequency of stimulation: 30 Hz; pulse width: 300 microsec; range of current delivered 10-34 mAmp) and augmented visual feedback. Spectral analysis of tremor showed a decrease of power spectral density to 62.18% (p = 0.01), of the integral in the 8-12 Hz frequency band to 57.67% (p = 0.003), and of tremor root mean square (RMS) to 57.16% (p = 0.002) during FES, without any changes in tremor frequency. Augmented visual feedback blocked the beneficial effect of FES, as confirmed by power spectral analysis (p = 0.01). We found a statistically significant interaction between augmented visual feedback and electrical stimulation (p = 0.039). Augmented visual feedback antagonizes the effects of FES on physiological tremor. The absence of changes of peak frequency argues against an effect of FES on mechanical properties of the upper limb.

  16. The resonant component of human physiological hand tremor is altered by slow voluntary movements.

    Science.gov (United States)

    Lakie, Martin; Vernooij, Carlijn A; Osborne, Timothy M; Reynolds, Raymond F

    2012-05-15

    Limb resonance imparts a characteristic spectrum to hand tremor. Movement will alter the resonance. We have examined the consequences of this change. Rectified forearm extensor muscle EMG and physiological hand tremor were recorded. In postural conditions the EMG spectrum is relatively flat whereas the acceleration spectrum is sharply peaked. Consequently, the gain between EMG and acceleration is maximal at the frequency where the tremor is largest (∼8 Hz). The shape of the gain curve implies mechanical resonance. Substantial alterations in posture do not significantly change the characteristics of the tremor or the shape or size of the gain curve. By contrast, slow or moderately paced voluntary wrist flexion–extension movements dramatically increase the hand tremor size and lower its peak frequency. These changes in size and frequency of the tremor cannot be attributed to changes in the EMG. Instead they reflect a very large change in the size and shape of the gain curve relating EMG to acceleration. The gain becomes larger and the peak moves to a lower frequency (∼6 Hz). We suggest that a movement-related (thixotropic) alteration in resonant properties of the wrist provides a simple explanation for these changes. The mechanism is illustrated by a model. Our new findings confirm that resonance plays a major role in wrist tremor. We also demonstrate that muscles operate very differently under postural and dynamic conditions. The different coupling between EMG and movement in posture and when moving must pose a considerable challenge for neural predictive control of skeletal muscles.

  17. Estimation of pathological tremor from recorded signals based on adaptive sliding fast Fourier transform

    Directory of Open Access Journals (Sweden)

    Shengxin Wang

    2016-06-01

    Full Text Available Pathological tremor is an approximately rhythmic movement and considerably affects patients’ daily living activities. Biomechanical loading and functional electrical stimulation are proposed as potential alternatives for canceling the pathological tremor. However, the performance of suppression methods is associated with the separation of tremor from the recorded signals. In this literature, an algorithm incorporating a fast Fourier transform augmented with a sliding convolution window, an interpolation procedure, and a damping module of the frequency is presented to isolate tremulous components from the measured signals and estimate the instantaneous tremor frequency. Meanwhile, a mechanism platform is designed to provide the simulation tremor signals with different degrees of voluntary movements. The performance of the proposed algorithm and existing procedures is compared with simulated signals and experimental signals collected from patients. The results demonstrate that the proposed solution could detect the unknown dominant frequency and distinguish the tremor components with higher accuracy. Therefore, this algorithm is useful for actively compensating tremor by functional electrical stimulation without affecting the voluntary movement.

  18. Atypical Porcine Pestivirus: A Possible Cause of Congenital Tremor Type A‐II in Newborn Piglets

    Directory of Open Access Journals (Sweden)

    Ad de Groof

    2016-10-01

    Full Text Available Congenital tremor type A‐II in piglets has been regarded as a transmissible disease since the 1970s, possibly caused by a very recently‐described virus: atypical porcine pestivirus (APPV. Here, we describe several strains of APPV in piglets with clinical signs of congenital tremor (10 of 10 farms tested. Piglets on a farm with no history of congenital tremor were PCR‐negative for the virus. To demonstrate a causal relationship between APPV and disease, three gilts were inoculated via intramuscular injection at day 32 of pregnancy. In two of the three litters, vertical transmission of the virus occurred. Clinical signs of congenital tremor were observed in APPV‐infected newborns, yet also two asymptomatic carriers were among the offspring. Piglets of one litter were PCR‐negative for the virus, and these piglets were all without congenital tremors. Long‐term follow up of farm piglets born with congenital tremors showed that the initially high viremia in serum declines at five months of age, but shedding of the virus in feces continues, which explains why the virus remains present at affected farms and causes new outbreaks. We conclude that trans‐placental transmission of APPV and subsequent infection of the fetuses is a very likely cause of congenital tremor type A‐II in piglets.

  19. Atypical Porcine Pestivirus: A Possible Cause of Congenital Tremor Type A-II in Newborn Piglets

    Science.gov (United States)

    de Groof, Ad; Deijs, Martin; Guelen, Lars; van Grinsven, Lotte; van Os-Galdos, Laura; Vogels, Wannes; Derks, Carmen; Cruijsen, Toine; Geurts, Victor; Vrijenhoek, Mieke; Suijskens, Janneke; van Doorn, Peter; van Leengoed, Leo; Schrier, Carla; van der Hoek, Lia

    2016-01-01

    Congenital tremor type A-II in piglets has been regarded as a transmissible disease since the 1970s, possibly caused by a very recently-described virus: atypical porcine pestivirus (APPV). Here, we describe several strains of APPV in piglets with clinical signs of congenital tremor (10 of 10 farms tested). Piglets on a farm with no history of congenital tremor were PCR-negative for the virus. To demonstrate a causal relationship between APPV and disease, three gilts were inoculated via intramuscular injection at day 32 of pregnancy. In two of the three litters, vertical transmission of the virus occurred. Clinical signs of congenital tremor were observed in APPV-infected newborns, yet also two asymptomatic carriers were among the offspring. Piglets of one litter were PCR-negative for the virus, and these piglets were all without congenital tremors. Long-term follow up of farm piglets born with congenital tremors showed that the initially high viremia in serum declines at five months of age, but shedding of the virus in feces continues, which explains why the virus remains present at affected farms and causes new outbreaks. We conclude that trans-placental transmission of APPV and subsequent infection of the fetuses is a very likely cause of congenital tremor type A-II in piglets. PMID:27782037

  20. Long-term outcome of deep brain stimulation in fragile X-associated tremor/ataxia syndrome.

    Science.gov (United States)

    Weiss, Daniel; Mielke, Carina; Wächter, Tobias; Bender, Benjamin; Liscic, Rajka M; Scholten, Marlieke; Naros, Georgios; Plewnia, Christian; Gharabaghi, Alireza; Krüger, Rejko

    2015-03-01

    Fragile X-associated tremor/ataxia syndrome (FXTAS) presents as complex movement disorder including tremor and cerebellar ataxia. The efficacy and safety of deep brain stimulation of the nucleus ventralis intermedius of the thalamus in atypical tremor syndromes like FXTAS remains to be determined. Here, we report the long-term outcome of three male genetically confirmed FXTAS patients treated with bilateral neurostimulation of the nucleus ventralis intermedius for up to four years. All patients demonstrated sustained improvement of both tremor and ataxia - the latter included improvement of intention tremor and axial tremor. Kinematic gait analyses further demonstrated a regularization of the gait cycle. Initial improvements of hand functional disability were not sustained and reached the preoperative level of impairment within one to two years from surgery. Our data on patients with a genetic cause of tremor show favorable outcome and may contribute to improved patient stratification for neurostimulation therapy in the future. Copyright © 2014 Elsevier Ltd. All rights reserved.

  1. Scattering Amplitudes in Gauge Theories

    CERN Document Server

    Schubert, Ulrich

    2014-01-01

    This thesis is focused on the development of new mathematical methods for computing multi-loop scattering amplitudes in gauge theories. In this work we combine, for the first time, the unitarity-based construction for integrands, and the recently introduced integrand-reduction through multivariate polynomial division. After discussing the generic features of this novel reduction algorithm, we will apply it to the one- and two-loop five-point amplitudes in ${\\cal N}=4$ sYM. The integrands of the multiple-cuts are generated from products of tree-level amplitudes within the super-amplitudes formalism. The corresponding expressions will be used for the analytic reconstruction of the polynomial residues. Their parametric form is known a priori, as derived by means of successive polynomial divisions using the Gr\\"obner basis associated to the on-shell denominators. The integrand reduction method will be exploited to investigate the color-kinematic duality for multi-loop ${\\cal N}=4$ sYM scattering amplitudes. Our a...

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

    Directory of Open Access Journals (Sweden)

    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.

  3. Tectonic tremor and brittle seismic events triggered along the Eastern Denali Fault in northwest Canada

    Science.gov (United States)

    Zimmerman, J. P.; Aiken, C.; Peng, Z.

    2013-12-01

    Deep tectonic tremor has been observed in a number of plate-bounding tectonic environments around the world. It can occur both spontaneously (i.e. ambient) and as a result of small stress perturbations from passing seismic waves (i.e. triggered). Because tremor occurs beneath the seismogenic zone (> 15 km), it is important to understand where and how tremor occurs to discern its relationship with shallower earthquakes. In this study, we search for triggered tremor and brittle seismic events along the Eastern Denali Fault (EDF) in northwest Canada, an intraplate strike-slip region where previously tremor has not been observed. We retrieve seismic data for 19 distant earthquakes from 9 broadband stations monitored by the Canadian National Seismograph Network (CNSN). We apply high-pass or band-pass filters to the seismic data to suppress signals from distant events and search for local sources. Triggered tremor signals exhibit high-frequency contents, have long duration (> 15 s), are coincident with passing surface waves of the distant earthquakes, and are observable among nearby stations. Using this simple approach, we have identified 4 mainshocks that triggered tremor in our study region: the 2011/03/11 Mw9.1 Tohoku, 2012/04/11 Mw8.6 Sumatra, 2012/10/28 Mw7.7 Haida Gwaii, and 2013/01/05 Mw7.5 Craige earthquakes. Our initial locations indicate that the tremor source occurs on or near the southeastern portion of the EDF near the fault trace. In addition to the triggered tremor sources, we also identified many 'brittle' events with very short durations triggered by the Rayleigh waves of the 2012/10/28 Mw7.7 Haida Gwaii earthquake. While we were unable to locate these brittle events, they appear to be seismically similar to triggered icequakes observed in Antarctica (Peng et al., 2013) and occur during the dilatational strain changes caused by the Rayleigh waves.

  4. EFFECTS OF WRIST WEIGHING IN REDUCING UPPER LIMB TREMORS IN PATIENTS WITH CEREBELLAR LESIONS

    Directory of Open Access Journals (Sweden)

    Vishnu Priya

    2015-08-01

    Full Text Available Background: An intentional tremor is one of the most untreated causes in patients with cerebellar ataxia. Upper limb tremors decreases the performance of many activities of daily life Thus treatment of patients with tremor probably implies better functional ability. It is one of the major areas of concern to improve functional independence hence, this study proposed to know the effects of wrist weighing in reducing upper limb tremors in cerebellar injury patients. Materials and Methods: A total number of 21 patients with various abnormalities of cerebellum were selected depending on selection criteria. These patients were randomly divided into two groups. One group was treated with wrist weighing by using Velcro weight cuffs for 15 minutes along with conventional physiotherapy for 5 days a week for 2 months & other group is treated with conventional physiotherapy for 5 days in a week for 2 months. The objectives were tested by using tremor rating scale and nine hole peg test. The values are collected before and after the treatment Results: In the group treated with wrist weighing the improvement in the tremor rating scale is very significant (p: 0.0001 and in nine hole peg test is extremely significant (p: 0.0001. In conventional therapy group the improvement in the tremor rating scale is not significant (p: 0.0051 and in nine hole peg test is very significant (p: 0.0002. Conclusion: Incorporation of wrist weighing along with conventional therapy reduced the intensity of upper limb tremors in patients with cerebellar injuries but both the treatments are effective in improving upper limb functions. KEY WORDS: Intentional tremor, Rehabilitation, Wrist weighing

  5. Volcan Reventador's Unusual Umbrella

    Science.gov (United States)

    Chakraborty, P.; Gioia, G.; Kieffer, S. W.

    2005-12-01

    In the past two decades, field observations of the deposits of volcanoes have been supplemented by systemmatic, and sometimes, opportunistic photographic documentation. Two photographs of the umbrella of the December 3, 2002 eruption of Volcan Reventador, Ecuador, reveal a prominently scalloped umbrella that is unlike any umbrella previously documented on a volcanic column. The material in the umbrella was being swept off a descending pyroclastic flow, and was, therefore, a co-ignimbrite cloud. We propose that the scallops are the result of a turbulent Rayleigh-Taylor (RT) instability with no precedents in volcanology. We ascribe the rare loss of buoyancy that drives this instability to the fact that the Reventador column fed on a cool co-ignimbrite cloud. On the basis of the observed wavelength of the scallops, we estimate a value for the eddy viscosity of the umbrella of 4000 ~m2/s. This value is consistent with a previously obtained lower bound (200 ~m2/s, K. Wohletz, priv. comm., 2005). We do not know the fate of the material in the umbrella subsequent to the photos. The analysis suggests that the umbrella was negatively buoyant. Field work on the co-ignimbrite deposits might reveal whether or not the material reimpacted, and if so, where and whether or not this material was involved in the hazardous flows that affected the main oil pipeline across Ecuador.

  6. Uranium series, volcanic rocks

    Science.gov (United States)

    Vazquez, Jorge A.

    2014-01-01

    Application of U-series dating to volcanic rocks provides unique and valuable information about the absolute timing of crystallization and differentiation of magmas prior to eruption. The 238U–230Th and 230Th-226Ra methods are the most commonly employed for dating the crystallization of mafic to silicic magmas that erupt at volcanoes. Dates derived from the U–Th and Ra–Th methods reflect crystallization because diffusion of these elements at magmatic temperatures is sluggish (Cherniak 2010) and diffusive re-equilibration is insignificant over the timescales (less than or equal to 10^5 years) typically associated with pre-eruptive storage of nearly all magma compositions (Cooper and Reid 2008). Other dating methods based on elements that diffuse rapidly at magmatic temperatures, such as the 40Ar/39Ar and (U–Th)/He methods, yield dates for the cooling of magma at the time of eruption. Disequilibrium of some short-lived daughters of the uranium series such as 210Po may be fractionated by saturation of a volatile phase and can be employed to date magmatic gas loss that is synchronous with volcanic eruption (e.g., Rubin et al. 1994).

  7. Volcanic Eruptions and Climate

    Science.gov (United States)

    LeGrande, Allegra N.; Anchukaitis, Kevin J.

    2015-01-01

    Volcanic eruptions represent some of the most climatically important and societally disruptive short-term events in human history. Large eruptions inject ash, dust, sulfurous gases (e.g. SO2, H2S), halogens (e.g. Hcl and Hbr), and water vapor into the Earth's atmosphere. Sulfurous emissions principally interact with the climate by converting into sulfate aerosols that reduce incoming solar radiation, warming the stratosphere and altering ozone creation, reducing global mean surface temperature, and suppressing the hydrological cycle. In this issue, we focus on the history, processes, and consequences of these large eruptions that inject enough material into the stratosphere to significantly affect the climate system. In terms of the changes wrought on the energy balance of the Earth System, these transient events can temporarily have a radiative forcing magnitude larger than the range of solar, greenhouse gas, and land use variability over the last millennium. In simulations as well as modern and paleoclimate observations, volcanic eruptions cause large inter-annual to decadal-scale changes in climate. Active debates persist concerning their role in longer-term (multi-decadal to centennial) modification of the Earth System, however.

  8. Factorization of Chiral String Amplitudes

    CERN Document Server

    Huang, Yu-tin; Yuan, Ellis Ye

    2016-01-01

    We re-examine a closed-string model defined by altering the boundary conditions for one handedness of two-dimensional propagators in otherwise-standard string theory. We evaluate the amplitudes using Kawai-Lewellen-Tye factorization into open-string amplitudes. The only modification to standard string theory is effectively that the spacetime Minkowski metric changes overall sign in one open-string factor. This cancels all but a finite number of states: As found in earlier approaches, with enough supersymmetry (e.g., type II) the tree amplitudes reproduce those of the massless truncation of ordinary string theory. However, we now find for the other cases that additional fields, formerly thought to be auxiliary, describe new spin-2 states at the two adjacent mass levels (tachyonic and tardyonic). The tachyon is always a ghost, but can be avoided in the heterotic case.

  9. Factorization of chiral string amplitudes

    Science.gov (United States)

    Huang, Yu-tin; Siegel, Warren; Yuan, Ellis Ye

    2016-09-01

    We re-examine a closed-string model defined by altering the boundary conditions for one handedness of two-dimensional propagators in otherwise-standard string theory. We evaluate the amplitudes using Kawai-Lewellen-Tye factorization into open-string amplitudes. The only modification to standard string theory is effectively that the spacetime Minkowski metric changes overall sign in one open-string factor. This cancels all but a finite number of states: as found in earlier approaches, with enough supersymmetry (e.g., type II) the tree amplitudes reproduce those of the massless truncation of ordinary string theory. However, we now find for the other cases that additional fields, formerly thought to be auxiliary, describe new spin-2 states at the two adjacent mass levels (tachyonic and tardyonic). The tachyon is always a ghost, but can be avoided in the heterotic case.

  10. Shape of Pion Distribution Amplitude

    Energy Technology Data Exchange (ETDEWEB)

    Radyushkin, Anatoly

    2009-11-01

    A scenario is investigated in which the leading-twist pion distribution amplitude $\\varphi_\\pi (x)$ is approximated by the pion decay constant $f_\\pi$ for all essential values of the light-cone fraction $x$. A model for the light-front wave function $\\Psi (x, k_\\perp)$ is proposed that produces such a distribution amplitude and has a rapidly decreasing (exponential for definiteness) dependence on the light-front energy combination $ k_\\perp^2/x(1-x)$. It is shown that this model easily reproduces the fit of recent large-$Q^2$ BaBar data on the photon-pion transition form factor. Some aspects of scenario with flat pion distribution amplitude are discussed.

  11. Nonsinglet pentagons and NMHV amplitudes

    Directory of Open Access Journals (Sweden)

    A.V. Belitsky

    2015-07-01

    Full Text Available Scattering amplitudes in maximally supersymmetric gauge theory receive a dual description in terms of the expectation value of the super Wilson loop stretched on a null polygonal contour. This makes the analysis amenable to nonperturbative techniques. Presently, we elaborate on a refined form of the operator product expansion in terms of pentagon transitions to compute twist-two contributions to NMHV amplitudes. To start with, we provide a novel derivation of scattering matrices starting from Baxter equations for flux-tube excitations propagating on magnon background. We propose bootstrap equations obeyed by pentagon form factors with nonsinglet quantum numbers with respect to the R-symmetry group and provide solutions to them to all orders in 't Hooft coupling. These are then successfully confronted against available perturbative calculations for NMHV amplitudes to four-loop order.

  12. Spectrogram analysis of selected tremor signals using short-time Fourier transform and continuous wavelet transform

    Directory of Open Access Journals (Sweden)

    D. Seidl

    1999-06-01

    Full Text Available Among a variety of spectrogram methods Short-Time Fourier Transform (STFT and Continuous Wavelet Transform (CWT were selected to analyse transients in non-stationary tremor signals. Depending on the properties of the tremor signal a more suitable representation of the signal is gained by CWT. Three selected broadband tremor signals from the volcanos Mt. Stromboli, Mt. Semeru and Mt. Pinatubo were analyzed using both methods. The CWT can also be used to extend the definition of coherency into a time-varying coherency spectrogram. An example is given using array data from the volcano Mt. Stromboli.

  13. Sweet Spot Tremor Triggered by Intraslab Earthquakes in the Nankai Subduction Zone

    Science.gov (United States)

    Aiken, C.; Obara, K.; Peng, Z.; Chao, K.; Maeda, T.

    2014-12-01

    Deep tectonic tremor has been observed at several major plate-bounding faults around the Pacific Rim. Tremor­ in these regions can be triggered by small stresses arising from solid earth tides as well as passing seismic waves of large, distant earthquakes. While large, distant earthquakes are capable of repeatedly triggering tremor in the same region (i.e., a sweet spot), it is less understood how intraslab earthquakes interact with sweet spot tremor areas. We conduct a systematic survey of tremor triggered in the Nankai subduction zone by intraslab earthquakes to better understand what governs fault slip along the Eurasian-Philippine Sea Plate boundary. We examine 3 tremor sweet spots in the Nankai subduction zone: Shikoku West, Kii North, and Tokai. In each region, we select earthquakes from the Japan Meteorological Agency (JMA) catalog that occur from mid-2009 to mid-2014 with magnitude (M) greater than 2, that occur within the down-going Philippine Sea Plate, and within a 300 km epicentral distance of the sweet spot region. Using these selection criteria, we obtain ~1,200 earthquakes in each region. We examine a tremor catalog immediately before and after these local events as well as visually inspect filtered waveforms from short-period Hi-net seismic stations surrounding the sweet spot areas to identify additional tremor signals. From our initial analysis, we have identified 18 clear cases of increased tremor activity immediately following intraslab earthquakes in Shikoku West, most of which occur down-dip of the Shikoku West sweet spot. In comparison, we have identified only 5 triggering earthquakes in Kii North, and our investigation at Tokai is still ongoing. Our results so far are in agreement with triggering susceptibility being dependent upon background activity rates, as has been suggested for remote triggering of microearthquakes in geothermal regions by large, distant earthquakes as well as for remotely triggered tremor in the Nankai subduction zone

  14. Holmes tremor in association with bilateral hypertrophic olivary degeneration and palatal tremor: chronological considerations. Case report Tremor de Holmes em associação com degeneração olivar hipertrófica bilateral e tremor palatal: considerações cronológicas. Relato de caso

    Directory of Open Access Journals (Sweden)

    Carlos R.M. Rieder

    2003-06-01

    Full Text Available Hypertrophic olivary degeneration (HOD is a rare type of neuronal degeneration involving the dento-rubro-olivary pathway and presents clinically as palatal tremor. We present a 48 year old male patient who developed Holmes' tremor and bilateral HOD five months after brainstem hemorrhage. The severe rest tremor was refractory to pharmacotherapy and botulinum toxin injections, but was markedly reduced after thalamotomy. Magnetic resonance imaging permitted visualization of HOD, which appeared as a characteristic high signal intensity in the inferior olivary nuclei on T2- and proton-density-weighted images. Enlargement of the inferior olivary nuclei was also noted. Palatal tremor was absent in that moment and appears about two months later. The delayed-onset between insult and tremor following structural lesions of the brain suggest that compensatory or secondary changes in nervous system function must contribute to tremor genesis. The literature and imaging findings of this uncommon condition are reviewed.Degeneração olivar hipertrófica (DOH é um tipo raro de degeneração neuronal envolvendo o trato dento-rubro-olivar e se apresenta clinicamente como tremor palatal. Relatamos o caso de um homem de 48 anos que desenvolveu tremor de Holmes e DOH bilateral cinco meses após hemorragia em tronco encefálico. O intenso tremor de repouso foi refratário a farmacoterapia e injeções de toxina botulínica, mas foi enormemente reduzido após talamotomia. Ressonância magnética permitiu a visualização da DOH, que apareceu como um sinal intenso característico na oliva inferior em imagens ponderadas em T2 e densidade de prótons. Aumento do complexo olivar inferior também foi percebido. O tremor palatal era ausente naquele momento e apareceu cerca de dois meses depois. O início tardio do tremor após a lesão estrutural sugere que alterações compensatórias ou secundárias no sistema nervoso devem contribuir para a gênese do tremor. A

  15. Familial Essential Tremor Studied With Functional Magnetic Resonance Imaging

    Science.gov (United States)

    Hernandez, A.; Salgado, P.; Gil, A.; Barrios, F. A.

    2003-09-01

    Functional Magnetic Resonance Imaging has become an important analytical tool to study neurodegenerative diseases. We applied the EPI-BOLD functional Magnetic Resonance Imaging technique to acquire functional images of patients with familial essential tremor (FET) disorder and healthy control volunteers, during a motor task activity. Functional and anatomic images were used to produce the brain activation maps of the patients and volunteers. These functional maps of the primary somatosensorial and motor cortexes of patients and control subjects were compared for functional differences per subject. The averaged functional brain images of eight of each case were acquired were, it can be clearly observed the differences in active zones. The results presented in this work show that there are differences in the functional maps during motor task activation between control subjects and FET patients suggesting a cerebral functional reorganization that can be mapped with BOLD-fMRI.

  16. Infantile tremor syndrome: Role of Vitamin B12 revisited

    Directory of Open Access Journals (Sweden)

    Rajesh Gupta

    2016-01-01

    Full Text Available Objective: To study the role of Vitamin B12 as an etiological factor in patients of infantile tremor syndrome (ITS. Methods: Twelve consecutive admissions of children diagnosed clinically as ITS were assessed. Assessment was done using a predefined pro forma to document patient demographic factors, general examination, systemic examination as well as relevant hematological and biochemical investigations. Results: Out of the 12 cases of ITS, 6 were males and 6 were females. Two cases had serum B12 levels below reference values, five had levels in low normal range, and remaining five had normal values. Conclusions: Role of Vitamin B12 deficiency as an etiological factor in the patients of ITS is inconclusive.

  17. Memantine Improves Attentional Processes in Fragile X-Associated Tremor/Ataxia Syndrome: Electrophysiological Evidence from a Randomized Controlled Trial.

    Science.gov (United States)

    Yang, Jin-Chen; Rodriguez, Annette; Royston, Ashley; Niu, Yu-Qiong; Avar, Merve; Brill, Ryan; Simon, Christa; Grigsby, Jim; Hagerman, Randi J; Olichney, John M

    2016-02-22

    Progressive cognitive deficits are common in patients with fragile X-associated tremor/ataxia syndrome (FXTAS), with no targeted treatment yet established. In this substudy of the first randomized controlled trial for FXTAS, we examined the effects of NMDA antagonist memantine on attention and working memory. Data were analyzed for patients (24 in each arm) who completed both the primary memantine trial and two EEG recordings (at baseline and follow-up) using an auditory "oddball" task. Results demonstrated significantly improved attention/working memory performance after one year only for the memantine group. The event-related potential P2 amplitude elicited by non-targets was significantly enhanced in the treated group, indicating memantine-associated improvement in attentional processes at the stimulus identification/discrimination level. P2 amplitude increase was positively correlated with improvement on the behavioral measure of attention/working memory during target detection. Analysis also revealed that memantine treatment normalized the P2 habituation effect at the follow-up visit. These findings indicate that memantine may benefit attentional processes that represent fundamental components of executive function/dysfunction, thought to comprise the core cognitive deficit in FXTAS. The results provide evidence of target engagement of memantine, as well as therapeutically relevant information that could further the development of specific cognitive or disease-modifying therapies for FXTAS.

  18. Report on the Aseismic Slip, Tremor, and Earthquakes Workshop

    Science.gov (United States)

    Gomberg, Joan; Roeloffs, Evelyn; Trehu, Anne; Dragert, Herb; Meertens, Charles

    2008-01-01

    This report summarizes the discussions and information presented during the workshop on Aseismic Slip, Tremor, and Earthquakes. Workshop goals included improving coordination among those involved in conducting research related to these phenomena, assessing the implications for earthquake hazard assessment, and identifying ways to capitalize on the education and outreach opportunities presented by these phenomena. Research activities of focus included making, disseminating, and analyzing relevant measurements; the relationships among tremor, aseismic or 'slow-slip', and earthquakes; and discovering the underlying causative physical processes. More than 52 participants contributed to the workshop, held February 25-28, 2008 in Sidney, British Columbia. The workshop was sponsored by the U.S. Geological Survey, the National Science Foundation?s Earthscope Program and UNAVCO Consortium, and the Geological Survey of Canada. This report has five parts. In the first part, we integrate the information exchanged at the workshop as it relates to advancing our understanding of earthquake generation and hazard. In the second part, we summarize the ideas and concerns discussed in workshop working groups on Opportunities for Education and Outreach, Data and Instrumentation, User and Public Needs, and Research Coordination. The third part presents summaries of the oral presentations. The oral presentations are grouped as they were at the workshop in the categories of phenomenology, underlying physical processes, and implications for earthquake hazards. The fourth part contains the meeting program and the fifth part lists the workshop participants. References noted in parentheses refer to the authors of presentations made at the workshop, and published references are noted in square brackets and listed in the Reference section. Appendix A contains abstracts of all participant presentations and posters, which also have been posted online, along with presentations and author contact

  19. Treatment of essential tremor: Are there issues we are overlooking?

    Directory of Open Access Journals (Sweden)

    Elan D Louis

    2012-01-01

    Full Text Available Background: Essential tremor (ET is one of the most common neurological diseases. Although a large number of medications have been tested, there are only two first-line medications, primidone and propranolol, which is a situation that has not changed in approximately 30 years. Several recent reviews have summarized the current pharmacotherapeutic options for ET and the approach to the management of ET patients. Yet there remain a number of important issues, both scientific and clinical, that have not been broached in the literature and that have therapeutic implications. Objectives: To introduce several clinical and scientific issues that have not formally entered the published literature on the treatment of ET. Methods: In September 2011, materials for this article were gathered during a literature search of PubMed using the following terms: essential tremor, clinical, clinical trial, treatment, medications, therapeutics. English-language articles were selected for further review.Results: The paper focuses on several topics that have received scant or no discussion in the published literature on ET therapeutics. These topics are as follows: the nature of the underlying disease pathophysiology, the presence of pathological heterogeneity, the complexity of cellular and neurochemical changes which may be underlying this disorder, the presence of clinical heterogeneity, the selection of treatment endpoints, the effects of diagnostic uncertainty, the presence of cognitive and psychiatric features in ET, the identification of possible modifiable risk factors and the absence of any neuroprotective therapies. Conclusions: The author has identified several topics that have received scant or no discussion in the published literature on ET therapeutics. Further discussion of the issues raised here may lead to improvements in clinical trial methodologies as well as facilitate the development of fresh approaches to pharmacotherapy.

  20. Friction in volcanic environments

    Science.gov (United States)

    Kendrick, Jackie E.; Lavallée, Yan

    2016-04-01

    Volcanic landscapes are amongst the most dynamic on Earth and, as such, are particularly susceptible to failure and frictional processes. In rocks, damage accumulation is frequently accompanied by the release of seismic energy, which has been shown to accelerate in the approach to failure on both a field and laboratory scale. The point at which failure occurs is highly dependent upon strain-rate, which also dictates the slip-zone properties that pertain beyond failure, in scenarios such as sector collapse and pyroclastic flows as well as the ascent of viscous magma. High-velocity rotary shear (HVR) experiments have provided new opportunities to overcome the grand challenge of understanding faulting processes during volcanic phenomena. Work on granular ash material demonstrates that at ambient temperatures, ash gouge behaves according to Byerlee's rule at low slip velocities, but is slip-weakening, becoming increasingly lubricating as slip ensues. In absence of ash along a slip plane, rock-rock friction induces cataclasis and heating which, if sufficient, may induce melting (producing pseudotachylyte) and importantly, vesiculation. The viscosity of the melt, so generated, controls the subsequent lubrication or resistance to slip along the fault plane thanks to non-Newtonian suspension rheology. The shear-thinning behaviour and viscoelasticity of frictional melts yield a tendency for extremely unstable slip, and occurrence of frictional melt fragmentation. This velocity-dependence acts as an important feedback mechanism on the slip plane, in addition to the bulk composition, mineralogy and glass content of the magma, that all influence frictional behaviour. During sector collapse events and in pyroclastic density currents it is the frictional properties of the rocks and ash that, in-part, control the run-out distance and associated risk. In addition, friction plays an important role in the eruption of viscous magmas: In the conduit, the rheology of magma is integral

  1. Employing Helicity Amplitudes for Resummation

    CERN Document Server

    Moult, Ian; Tackmann, Frank J; Waalewijn, Wouter J

    2015-01-01

    Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are directly given in terms of color-ordered helicity amplitudes. Using this basis allows one to seamlessly combine fixed-order helicity amplitudes at any order they are known with a resummation of higher-order logarithmic corrections. In particular, the virtual loop amplitudes can be employed in factorization theorems to make predictions for exclusive jet cross sections without the use of numerical subtraction schemes to handle real-virtual infrared cancellations. We also discuss matching onto SCET in renormalization schemes with helicities in $4$- and $d$-dimensions. To demonstrate that our helicity operator basis is easy to use, we provide an explicit construction of the operator basis, as well as results for the hard m...

  2. Scattering amplitudes in gauge theories

    Energy Technology Data Exchange (ETDEWEB)

    Henn, Johannes M. [Institute for Advanced Study, Princeton, NJ (United States). School of Natural Sciences; Plefka, Jan C. [Humboldt-Universitaet, Berlin (Germany). Inst. fuer Physik

    2014-03-01

    First monographical text on this fundamental topic. Course-tested, pedagogical and self-contained exposition. Includes exercises and solutions. At the fundamental level, the interactions of elementary particles are described by quantum gauge field theory. The quantitative implications of these interactions are captured by scattering amplitudes, traditionally computed using Feynman diagrams. In the past decade tremendous progress has been made in our understanding of and computational abilities with regard to scattering amplitudes in gauge theories, going beyond the traditional textbook approach. These advances build upon on-shell methods that focus on the analytic structure of the amplitudes, as well as on their recently discovered hidden symmetries. In fact, when expressed in suitable variables the amplitudes are much simpler than anticipated and hidden patterns emerge. These modern methods are of increasing importance in phenomenological applications arising from the need for high-precision predictions for the experiments carried out at the Large Hadron Collider, as well as in foundational mathematical physics studies on the S-matrix in quantum field theory. Bridging the gap between introductory courses on quantum field theory and state-of-the-art research, these concise yet self-contained and course-tested lecture notes are well-suited for a one-semester graduate level course or as a self-study guide for anyone interested in fundamental aspects of quantum field theory and its applications. The numerous exercises and solutions included will help readers to embrace and apply the material presented in the main text.

  3. Employing Helicity Amplitudes for Resummation

    NARCIS (Netherlands)

    Moult, I.; Stewart, I.W.; Tackmann, F.J.; Waalewijn, W.J.

    2015-01-01

    Many state-of-the-art QCD calculations for multileg processes use helicity amplitudes as their fundamental ingredients. We construct a simple and easy-to-use helicity operator basis in soft-collinear effective theory (SCET), for which the hard Wilson coefficients from matching QCD onto SCET are dire

  4. Extracting amplitudes from photoproduction data

    Science.gov (United States)

    Workman, R. L.

    2011-09-01

    We consider the problems associated with amplitude extraction, from meson photoproduction data, over the first resonance regions. The notion of a complete experiment has motivated the FROST program at Jefferson Lab. Exercises applied to pion photoproduction data illustrate the problems to be confronted in any attempt to extract underlying resonance signals from these data (without introducing a model for the resonant process).

  5. A family of repeating low-frequency earthquakes at the downdip edge of tremor and slip

    Science.gov (United States)

    Sweet, Justin R.; Creager, Kenneth C.; Houston, Heidi

    2014-09-01

    analyze an isolated low-frequency earthquake (LFE) family located at the downdip edge of the main episodic tremor and slip (ETS) zone beneath western Washington State. The 9000 individual LFEs from this repeating family cluster into 198 swarms that recur roughly every week. Cumulative LFE seismic moment for each swarm correlates strongly with the time until the next swarm, suggesting that these LFE swarms are time predictable. Precise double-difference relative locations for 700 individual LFEs within this family show a distribution that is approximately 2 km long and 500 m wide, elongated parallel to the relative plate convergence direction. The distribution of locations (<300 m vertical spread) lies within a few hundred meters of two different plate interface models and has a similar dip. Peak-to-peak LFE S wave amplitudes range from 0.2 to 18 nm. Individual LFEs exhibit a trend of increasing magnitude during swarms, with smaller events at the beginning and the largest events toward the end. The largest LFEs cluster in a small area (300 m radius) coincident with maximum LFE density. We propose that the less-concentrated smaller LFEs act to unlock this patch core, allowing it to fully rupture in the largest LFEs, usually toward the end of a swarm. We interpret the patch responsible for producing these LFEs as a subducted seamount on the downgoing Juan de Fuca (JdF) plate. LFE locking efficiency (slip estimated during 5 years from summing LFE seismic moment divided by plate-rate-determined slip) is at most 20% and is highly concentrated in two ˜50 m radius locations in the larger patch core. Estimated individual LFE stress drops range from 1 to 20 kPa, but could also be significantly larger.

  6. Volcanic studies at Katmai

    Energy Technology Data Exchange (ETDEWEB)

    1989-12-31

    The Continental Scientific Drilling Program (CSDP) is a national effort supported by the Department of Energy, the US Geological Survey, and the National Science Foundation. One of the projects proposed for the CSDP consists of drilling a series of holes in Katmai National Park in Alaska to give a third dimension to the model of the 1912 eruption of Novarupta, and to investigate the processes of explosive volcanism and hydrothermal transport of metals (Eichelberger et al., 1988). The proposal for research drilling at Katmai states that ``the size, youth, elevated temperature, and simplicity of the Novarupta vent make it a truly unique scientific target.`` The National Park Service (NPS), which has jurisdiction, is sympathetic to aims of the study. However, NPS wishes to know whether Katmai is indeed uniquely suited to the research, and has asked the Interagency Coordinating Group to support an independent assessment of this claim. NPS suggested the National Academy of Sciences as an appropriate organization to conduct the assessment. In response, the National Research Council -- the working arm of the Academy -- established, under the aegis of its US Geodynamics Committee, a panel whose specific charge states: ``The proposed investigation at Katmai has been extensively reviewed for scientific merit by the three sponsoring and participating agencies. Thus, the scientific merit of the proposed drilling at Katmai is not at issue. The panel will review the proposal for scientific drilling at Katmai and prepare a short report addressing the specific question of the degree to which it is essential that the drilling be conducted at Katmai as opposed to volcanic areas elsewhere in the world.``

  7. Quaternary basaltic volcanism in the Payenia volcanic province, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina

    The extensive Quaternary volcanism in the Payenia volcanic province, Mendoza, Argentina, is investigated in this study by major and trace element analyses, Sr, Nd, Hf and Pb-isotopic analyses and Zr-Hf isotope dilution data on samples from almost the entire province. The samples are mainly...... in basalts from all the studied volcanic fields in Payenia is signs of lower crustal contamination indicating assimilation of, in some cases, large amounts of trace element depleted, mafic, plagioclase-bearing rocks. The northern Payenia is dominated by backarc basalts erupted between late Pliocene to late...

  8. Decreased cortical inhibition and yet cerebellar pathology in 'familial cortical myoclonic tremor with epilepsy'

    NARCIS (Netherlands)

    van Rootselaar, Anne-Fleur; van der Salm, Sandra M. A.; Bour, Lo J.; Edwards, Mark J.; Brown, Peter; Aronica, Eleonora; Rozemuller-Kwakkel, Johanna M.; Koehler, Peter J.; Koelman, Johannes H. T. M.; Rothwell, John C.; Tijssen, Marina A. J.

    2007-01-01

    Cortical hyperexcitability is a feature of "familial cortical myoclonic tremor with epilepsy" (FCMTE). However, neuropathological investigations in a single FCMTE patient showed isolated cerebellar pathology. Pathological investigations in a second FCMTE patient, reported here, confirmed cerebellar

  9. Tremor suppression using functional electrical stimulation: a comparison between digital and analog controllers.

    Science.gov (United States)

    Gillard, D M; Cameron, T; Prochazka, A; Gauthier, M J

    1999-09-01

    In this study, we compared digital and analog versions of a functional electrical stimulator designed to suppress tremor. The device was based on a closed-loop control system designed to attenuate movements in the tremor frequency range, without significantly affecting slower, voluntary movements. Testing of the digital filter was done on three patients with Parkinsonian tremor and the results compared to those of a functional electrical stimulation device based on an analog filter evaluated in a previous study. Additional testing of both the analog and digital filters was done on three subjects with no neurological impairment performing tremor-like movements and slow voluntary movements. We found that the digital controller provided a mean attenuation of 84%, compared to 65% for the analog controller.

  10. Cascadia tremor located near plate interface constrained by S minus P wave times.

    Science.gov (United States)

    La Rocca, Mario; Creager, Kenneth C; Galluzzo, Danilo; Malone, Steve; Vidale, John E; Sweet, Justin R; Wech, Aaron G

    2009-01-30

    Nonvolcanic tremor is difficult to locate because it does not produce impulsive phases identifiable across a seismic network. An alternative approach to identifying specific phases is to measure the lag between the S and P waves. We cross-correlate vertical and horizontal seismograms to reveal signals common to both, but with the horizontal delayed with respect to the vertical. This lagged correlation represents the time interval between vertical compressional waves and horizontal shear waves. Measurements of this interval, combined with location techniques, resolve the depth of tremor sources within +/-2 kilometers. For recent Cascadia tremor, the sources locate near or on the subducting slab interface. Strong correlations and steady S-P time differences imply that tremor consists of radiation from repeating sources.

  11. Cannabinoids and Tremor Induced by Motor-related Disorders: Friend or Foe?

    Science.gov (United States)

    Arjmand, Shokouh; Vaziri, Zohreh; Behzadi, Mina; Abbassian, Hassan; Stephens, Gary J; Shabani, Mohammad

    2015-10-01

    Tremor arises from an involuntary, rhythmic muscle contraction/relaxation cycle and is a common disabling symptom of many motor-related diseases such as Parkinson disease, multiple sclerosis, Huntington disease, and forms of ataxia. In the wake of anecdotal, largely uncontrolled, observations claiming the amelioration of some symptoms among cannabis smokers, and the high density of cannabinoid receptors in the areas responsible for motor function, including basal ganglia and cerebellum, many researchers have pursued the question of whether cannabinoid-based compounds could be used therapeutically to alleviate tremor associated with central nervous system diseases. In this review, we focus on possible effects of cannabinoid-based medicines, in particular on Parkinsonian and multiple sclerosis-related tremors and the common probable molecular mechanisms. While, at present, inconclusive results have been obtained, future investigations should extend preclinical studies with different cannabinoids to controlled clinical trials to determine potential benefits in tremor.

  12. Levetiracetam in primary orthostatic tremor: a double-blind placebo-controlled crossover study.

    Science.gov (United States)

    Hellriegel, Helge; Raethjen, Jan; Deuschl, G; Volkmann, Jens

    2011-11-01

    In a double-blind crossover study we evaluated the antitremor effect of a 4-week treatment with either escalating dosages of levetiracetam or placebo in orthostatic tremor. Twelve patients with orthostatic tremor participated in the study. Primary end point was improvement in stance duration. Secondary end points were total track length of the sway path and tremor total power. The patients' impression of impairment was assessed by a visual analog scale and quality of life by the SF-36. We found no significant effect of dosage or treatment on stance duration (P = .175), total track length (P = .690), total power (P = .280), or visual analog scale (P =.735). Neither was SF-36 differentially changed by levetiracetam or placebo (SF-36, Physical Component Summary: P = .079; SF-36, Mental Component Summary: P = .073). Side effects like dizziness, fatigue, or nausea were only mild to moderate. Levetiracetam is ineffective in the treatment of orthostatic tremor. Copyright © 2011 Movement Disorder Society.

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

    Science.gov (United States)

    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

    2015-05-08

    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.

  14. Implementation of an iPhone for characterizing Parkinson's disease tremor through a wireless accelerometer application.

    Science.gov (United States)

    Lemoyne, Robert; Mastroianni, Timothy; Cozza, Michael; Coroian, Cristian; Grundfest, Warren

    2010-01-01

    Parkinson's disease represents a chronic movement disorder, which is generally proportionally to age. The status of Parkinson's disease is traditionally classified through ordinal scale strategies, such as the Unified Parkinson's Disease Rating Scale. However, the application of the ordinal scale strategy inherently requires highly specialized and limited medical resources for interpretation. An alternative strategy involves the implementation of an iPhone application that enables the device to serve as a functional wireless accelerometer system. The Parkinson's disease tremor attributes may be recorded in either an effectively autonomous public or private setting, for which the resultant accelerometer signal of the tremor can be conveyed wireless and through email to a remote location for data post-processing. The initial testing and evaluation of the iPhone wireless accelerometer application for quantifying Parkinson's disease tremor successfully demonstrates the capacity to acquire tremor characteristics in an effectively autonomous environment, while potentially alleviating strain on limited and highly specialized medical resources.

  15. Detailed Tremor Migration Styles in Guerrero, Mexico Imaged with Cross-station Cross-correlations

    Science.gov (United States)

    Peng, Y.; Rubin, A. M.

    2015-12-01

    Tremor occurred downdip of the area that slipped the most during the 2006 slow slip event (SSE) in Guerrero, Mexico, as opposed to Cascadia, where tremor locations and rupture zones of SSEs largely overlap. Here we obtain high resolution tremor locations by applying cross-station cross-correlations [Armbruster et al., 2014] to seismic data from the Meso-America Subduction Experiment deployment. A few 3-station detectors are adopted to capture detailed deformation styles in the tremor "transient zone" and the downdip "sweet spot" as defined in Frank et al., 2014. Similar to Cascadia, tremor activities in our study region were comprised mostly of short tremor bursts lasting minutes to hours. Many of these bursts show clear migration patterns with propagation velocities of hundreds of km/day, comparable to those in Cascadia. However, the propagation of the main tremor front was often not in a simple unilateral fashion. Before the 2006 SSE, we observe 4 large tremor episodes during which both the transient zone and the sweet spot participated, consistent with previous findings [Frank et al., 2014]. The transient zone usually became active a few days after the sweet spot. We find many along-dip migrations with recurrence intervals of about a half day within a region about 10 km along strike and 35 km along dip in the sweet spot, suggesting possible tidal modulation, after the main front moved beyond this region. These migrations appear not to originate at the main front, in contrast to tremor migrations from a few km to tens of km across observed in Cascadia [Rubin and Armbruster, 2013; Peng et al., 2015; Peng and Rubin, submitted], but possibly similar to Shikoku, Japan [Shelly et al., 2007]. We do not observe obvious half-day periodicity for the migrations farther downdip within the sweet spot. During the SSE, the recurrence interval of tremor episodes decreased significantly in both the transient zone and the sweet spot, with that of the former being much shorter

  16. Recent Findings on the Nature of Episodic Tremor and Slip Along the Northern Cascadia Margin

    Science.gov (United States)

    Dragert, H.; Wang, K.; Kao, H.

    2008-12-01

    Episodic Tremor and Slip (ETS), as observed along the northern Cascadia margin, has been defined empirically as repeated, transient ground motions at a plate margin, roughly opposite to longer-term interseismic deformation, occurring synchronously with low-frequency, emergent seismic signals. Although the exact causal processes are still a matter of debate, recent improvements in the monitoring of these transient events provide clearer constraints for the location and the migration of both tremor and slip. In areal distribution, the tremors continue to occur in a band overlying the 25 to 55 km depth contours of the nominal subducting plate interface. The previously reported extended depth distribution of tremor is also observed for the most recent tremor episodes, as is the coincidence of peak tremor activity with a band of seismic reflectors that is commonly interpreted to be positioned above the plate interface. In these episodes, tremors migrate along strike of the subduction zone from the southeast to the northwest at speeds ranging from 5 to 13 km/day. Tremor data also show changes in migration speed during the course of a single episode. No systematic migration in depth has yet been resolved. Denser GPS monitoring and the introduction of borehole strainmeters have also led to a better definition of the ETS surface deformations patterns, including those derived from the vertical GPS component. Inversion of the GPS data, constrained by limiting slip to the currently accepted plate interface, results in an area of slip that parallels the strike of the subduction zone, overlapping with but narrower than the band of tremor distribution and displaced slightly seaward. Inversion constrained by a shallower occurrence of slip, on or near the reflector band, results in a broader distribution of slip with reduced magnitudes. This would be more commensurate with the wider distribution of tremor. The current GPS deformation data are unable to tell whether the slip could

  17. Self-sustained vibrations in volcanic areas extracted by Independent Component Analysis: a review and new results

    Science.gov (United States)

    de Lauro, E.; de Martino, S.; Falanga, M.; Palo, M.

    2011-12-01

    We investigate the physical processes associated with volcanic tremor and explosions. A volcano is a complex system where a fluid source interacts with the solid edifice so generating seismic waves in a regime of low turbulence. Although the complex behavior escapes a simple universal description, the phases of activity generate stable (self-sustained) oscillations that can be described as a non-linear dynamical system of low dimensionality. So, the system requires to be investigated with non-linear methods able to individuate, decompose, and extract the main characteristics of the phenomenon. Independent Component Analysis (ICA), an entropy-based technique is a good candidate for this purpose. Here, we review the results of ICA applied to seismic signals acquired in some volcanic areas. We emphasize analogies and differences among the self-oscillations individuated in three cases: Stromboli (Italy), Erebus (Antarctica) and Volcán de Colima (Mexico). The waveforms of the extracted independent components are specific for each volcano, whereas the similarity can be ascribed to a very general common source mechanism involving the interaction between gas/magma flow and solid structures (the volcanic edifice). Indeed, chocking phenomena or inhomogeneities in the volcanic cavity can play the same role in generating self-oscillations as the languid and the reed do in musical instruments. The understanding of these background oscillations is relevant not only for explaining the volcanic source process and to make a forecast into the future, but sheds light on the physics of complex systems developing low turbulence.

  18. Using a Smart Phone as a Standalone Platform for Detection and Monitoring of Pathological Tremors

    OpenAIRE

    Daneault, Jean-François; Carignan, Benoit; Codère, Carl Éric; Abbas F Sadikot; Duval, Christian

    2013-01-01

    Introduction: Smart phones are becoming ubiquitous and their computing capabilities are ever increasing. Consequently, more attention is geared toward their potential use in research and medical settings. For instance, their built-in hardware can provide quantitative data for different movements. Therefore, the goal of the current study was to evaluate the capabilities of a standalone smart phone platform to characterize tremor. Results: Algorithms for tremor recording and online analysis can...

  19. How to tackle tremor – systematic review of the literature and diagnostic work-up

    Directory of Open Access Journals (Sweden)

    Arthur W.G. Buijink

    2012-10-01

    Full Text Available BackgroundTremor is the most prevalent movement disorder in clinical practice. It is defined as involuntary, rhythmic, oscillatory movements. The diagnostic process of patients with tremor can be laborious and challenging, and a clear, systematic overview of available diagnostic techniques is lacking. Tremor can be a symptom of many diseases, but can also represent a distinct disease entity.ObjectiveThe objective of this review is to give a clear, systematic and step-wise overview of the diagnostic work-up of a patient with tremor. The clinical relevance and value of available laboratory tests in patients with tremor will be explored.MethodsWe systematically searched through EMBASE. The retrieved articles were supplemented by articles containing relevant data or provided important background information. Studies that were included investigated the value and/or usability of diagnostic tests for tremor.ResultsIn most patients, history and clinical examination by an experienced movement disorders neurologist are sufficient to establish a correct diagnosis, and further ancillary examinations will not be needed. Ancillary investigation should always be guided by tremor type(s present and other associated signs and symptoms. The main ancillary examination techniques currently are electromyography and SPECT imaging. Unfortunately, many techniques have not been studied in large prospective, diagnostic studies to be able to determine important variables like sensitivity and specificity.ConclusionWhen encountering a patient with tremor, history and careful clinical examination should guide the diagnostic process. Adherence to the diagnostic work-up provided in this review will help the diagnostic process of these patients.

  20. Iron accumulation and dysregulation in the putamen in fragile X-associated tremor/ataxia syndrome.

    Science.gov (United States)

    Ariza, Jeanelle; Rogers, Hailee; Hartvigsen, Anna; Snell, Melissa; Dill, Michael; Judd, Derek; Hagerman, Paul; Martínez-Cerdeño, Verónica

    2017-04-01

    Fragile X-associated tremor/ataxia syndrome is an adult-onset disorder associated with premutation alleles of the FMR1 gene. This disorder is characterized by progressive action tremor, gait ataxia, and cognitive decline. Fragile X-associated tremor/ataxia syndrome pathology includes dystrophic white matter and intranuclear inclusions in neurons and astrocytes. We previously demonstrated that the transport of iron into the brain is altered in fragile X-associated tremor/ataxia syndrome; therefore, we also expect an alteration of iron metabolism in brain areas related to motor control. Iron is essential for cell metabolism, but uncomplexed iron leads to oxidative stress and contributes to the development of neurodegenerative diseases. We investigated a potential iron modification in the putamen - a structure that participates in motor learning and performance - in fragile X-associated tremor/ataxia syndrome. We used samples of putamen obtained from 9 fragile X-associated tremor/ataxia syndrome and 9 control cases to study iron localization using Perl's method, and iron-binding proteins using immunostaining. We found increased iron deposition in neuronal and glial cells in the putamen in fragile X-associated tremor/ataxia syndrome. We also found a generalized decrease in the amount of the iron-binding proteins transferrin and ceruloplasmin, and decreased number of neurons and glial cells that contained ceruloplasmin. However, we found increased levels of iron, transferrin, and ceruloplasmin in microglial cells, indicating an attempt by the immune system to remove the excess iron. Overall, found a deficit in proteins that eliminate extra iron from the cells with a concomitant increase in the deposit of cellular iron in the putamen in Fragile X-associated tremor/ataxia syndrome. © 2017 International Parkinson and Movement Disorder Society. © 2017 International Parkinson and Movement Disorder Society.

  1. Balance in essential tremor during tandem gait: is the first mis-step an important finding?

    Science.gov (United States)

    Cinar, N; Sahin, S; Okluoglu Onay, T; Karsidag, S

    2013-10-01

    Essential tremor (ET) is the most commonly diagnosed movement disorder. ET may cause substantial loss of motor skills and balance with advanced age. We compared abnormalities in tandem gait with daily activity and Fahn-Tolosa-Marin Tremor Rating Scale (FTMTRS) scores in 90 ET patients. All patients performed a 15-step tandem three times. The mean of first mis-steps was accepted as the tandem index (TI). The mean age was 61.4 ± 17 years; the mean duration of tremor was 6.7 ± 4 years; and there were 36 men and 54 women. There was no significant difference for age or sex between patients and controls. Head (24.6%), jaw (5.5%), voice (11%), and tongue tremors (1.5%) were identified in ET patients. Rest (2.5%), postural (95%), and kinetic tremors (54%) were detected in the upper extremities. Postural tremor was found in the lower extremities of 5%. The mean TI was 8.3 ± 4 (median, 8) in ET patients, and 10.6 ± 3.9 (median, 10) in controls (p=0.04). Correlation analysis of TI and FTMTRS scores showed tandem gait was significantly correlated with age, total tremor score, postural and kinetic extremity tremor, writing, drawing, pouring, feeding, and working scores. Linear regression showed a significant effect of age and FTMTRS score on TI. The decrease in balance control is apparent with advancing age. Balance disorders were more pronounced in ET patients. Although first mis-step in tandem gait is not as detailed as dynamic balance tests, it can be a simple method for detecting balance disorders. Copyright © 2013 Elsevier Ltd. All rights reserved.

  2. Autosomal dominant cortical tremor, myoclonus, and epilepsy (ADCME: Probable first family from India

    Directory of Open Access Journals (Sweden)

    Chandra Mohan Sharma

    2014-01-01

    Full Text Available Autosomal dominant cortical tremor, myoclonus, and epilepsy (ADCME is an extremely rare syndrome characterized by familial occurrence of postural and action-induced tremors of the hands but showing electrophysiologic findings of cortical reflex myoclonus. Patients also have cognitive decline and tonic-clonic seizures, often precipitated by sleep deprivation or photic stimulation. We describe probably the first family from India of this ill-defined syndrome.

  3. Surface-wave potential for triggering tectonic (nonvolcanic) tremor-corrected

    Science.gov (United States)

    Hill, David P.

    2012-01-01

    Source processes commonly posed to explain instances of remote dynamic triggering of tectonic (nonvolcanic) tremor by surface waves include frictional failure and various modes of fluid activation. The relative potential for Love- and Rayleigh-wave dynamic stresses to trigger tectonic tremor through failure on critically stressed thrust and vertical strike-slip faults under the Coulomb-Griffith failure criteria as a function of incidence angle are anticorrelated over the 15- to 30-km-depth range that hosts tectonic tremor. Love-wave potential is high for strike-parallel incidence on low-angle reverse faults and null for strike-normal incidence; the opposite holds for Rayleigh waves. Love-wave potential is high for both strike-parallel and strike-normal incidence on vertical, strike-slip faults and minimal for ~45° incidence angles. The opposite holds for Rayleigh waves. This pattern is consistent with documented instances of tremor triggered by Love waves incident on the Cascadia megathrust and the San Andreas fault (SAF) in central California resulting from shear failure on weak faults (apparent friction is μ* ≤ 0:2). Documented instances of tremor triggered by surface waves with strike-parallel incidence along the Nankai megathrust beneath Shikoku, Japan, however, are associated primarily with Rayleigh waves. This is consistent with the tremor bursts resulting from mixed-mode failure (crack opening and shear failure) facilitated by near-lithostatic ambient pore pressure, low differential stress, with a moderate friction coefficient (μ ~ 0:6) on the Nankai subduction interface. Rayleigh-wave dilatational stress is relatively weak at tectonic tremor source depths and seems unlikely to contribute significantly to the triggering process, except perhaps for an indirect role on the SAF in sustaining tremor into the Rayleigh-wave coda that was initially triggered by Love waves.

  4. Northern Cascadia Episodic Tremor and Slip: A Decade of Observations from 1997 to 2007

    Science.gov (United States)

    Kao, H.; Shan, S.; Dragert, H.; Rogers, G.; Ito, Y.

    2008-12-01

    We analyze continuous seismic and GPS records collected in the last decade (1997-2007) to establish the most comprehensive observational basis for northern Cascadia episodic tremor and slip (ETS) events. A simple ¡§ETS scale¡¨ system, using a combination of a letter and a digit, is proposed to quantitatively characterize the spatial and temporal dimensions of ETS events. Clear correlation between GPS and tremor signals is observed for all major episodes with lateral dimension >150 km (i.e., A- or B-class), but the GPS signature is less obvious for minor ones. Regular ETS recurrence can be established only for A-/B-class episodes in southern Vancouver Island. Halting and jumping are very common in ETS migration patterns, and along-strike migration can happen in both directions. A prominent tremor gap is observed in mid island around 49.5N. This gap coincides with the epicenters of the only two large documented crustal earthquakes in the region. ETS tremors also tend to occur in places where the local seismicity is relatively sparse. The tremor depth distribution shows a peak in the 25-35 km range where strong seismic reflectors (i.e., the E- layer) are documented. Existence of tremors in the vicinity of E-layer is also confirmed by an independent waveform analysis. More significantly, we have found a few very-low-frequency earthquakes (VLFE) at the depth of E-layer showing low-angle thrust faulting mechanisms. Our results suggest that a significant portion of the tremor activity and perhaps associated shearing are taking place along well-developed structures such as the E-layer, while a reduced number of tremor bursts are generated elsewhere in response to induced stress variation throughout the source volume.

  5. Thalamic DBS with a constant-current device in essential tremor: A controlled clinical trial.

    Science.gov (United States)

    Wharen, Robert E; Okun, Michael S; Guthrie, Barton L; Uitti, Ryan J; Larson, Paul; Foote, Kelly; Walker, Harrison; Marshall, Frederick J; Schwalb, Jason; Ford, Blair; Jankovic, Joseph; Simpson, Richard; Dashtipour, Khashayar; Phibbs, Fenna; Neimat, Joseph S; Stewart, R Malcolm; Peichel, DeLea; Pahwa, Rajesh; Ostrem, Jill L

    2017-07-01

    This study of thalamic deep brain stimulation (DBS) investigated whether a novel constant-current device improves tremor and activities of daily living (ADL) in patients with essential tremor (ET). A prospective, controlled, multicenter study was conducted at 12 academic centers. We investigated the safety and efficacy of unilateral and bilateral constant-current DBS of the ventralis intermedius (VIM) nucleus of the thalamus in patients with essential tremor whose tremor was inadequately controlled by medications. The primary outcome measure was a rater-blinded assessment of the change in the target limb tremor score in the stimulation-on versus stimulation-off state six months following surgery. Multiple secondary outcomes were assessed at one-year follow-up, including motor, mood, and quality-of-life measures. 127 patients were implanted with VIM DBS. The blinded, primary outcome variable (n = 76) revealed a mean improvement of 1.25 ± 1.26 points in the target limb tremor rating scale (TRS) score in the arm contralateral to DBS (p < 0.001). Secondary outcome variables at one year revealed significant improvements (p ≤ 0.001) in quality of life, depression symptoms, and ADL scores. Forty-seven patients had a second contralateral VIM-DBS, and this group demonstrated reduction in second-sided tremor at 180 days (p < 0.001). Serious adverse events related to the surgery included infection (n = 3), intracranial hemorrhage (n = 3), and device explantation (n = 3). Unilateral and bilateral constant-current VIM DBS significantly improves upper extremity tremor, ADL, quality of life, and depression in patients with severe ET. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Methodology for estimating human perception to tremors in high-rise buildings

    Science.gov (United States)

    Du, Wenqi; Goh, Key Seng; Pan, Tso-Chien

    2016-12-01

    Human perception to tremors during earthquakes in high-rise buildings is usually associated with psychological discomfort such as fear and anxiety. This paper presents a methodology for estimating the level of perception to tremors for occupants living in high-rise buildings subjected to ground motion excitations. Unlike other approaches based on empirical or historical data, the proposed methodology performs a regression analysis using the analytical results of two generic models of 15 and 30 stories. The recorded ground motions in Singapore are collected and modified for structural response analyses. Simple predictive models are then developed to estimate the perception level to tremors based on a proposed ground motion intensity parameter—the average response spectrum intensity in the period range between 0.1 and 2.0 s. These models can be used to predict the percentage of occupants in high-rise buildings who may perceive the tremors at a given ground motion intensity. Furthermore, the models are validated with two recent tremor events reportedly felt in Singapore. It is found that the estimated results match reasonably well with the reports in the local newspapers and from the authorities. The proposed methodology is applicable to urban regions where people living in high-rise buildings might feel tremors during earthquakes.

  7. Dynamics of tremor-related oscillations in the human globus pallidus: A single case study

    Science.gov (United States)

    Hurtado, José M.; Gray, Charles M.; Tamas, Laszlo B.; Sigvardt, Karen A.

    1999-01-01

    Physiological evidence indicates that the resting tremor of Parkinson’s disease originates in oscillatory neural activity in the forebrain, but it is unknown whether that activity is globally synchronized or consists of parallel, independently oscillating circuits. In the present study, we used dual microelectrodes to record tremor-related neuronal activity from eight sites in the internal segment of the globus pallidus (GPi) from an awake Parkinson’s disease patient undergoing stereotaxic pallidotomy. We utilized spectral analysis to evaluate the temporal correlations between multiunit activity at spatially separated sites and between neural and limb electromyographic activity. We observed that some GPi neural pairs oscillated synchronously at the tremor frequency, whereas other neural pairs oscillated independently. Additionally, we found that GPi tremor-related activity at a given site could fluctuate between states of synchronization and independence with respect to upper limb tremor. Consistent with this finding, some paired recording sites within GPi showed periods of transient synchronization. These observations support the hypothesis of independent tremor-generating circuits whose coupling can fluctuate over time. PMID:9990083

  8. Analysis of fatigue and tremor during sustained maximal grip contractions using Hilbert-Huang Transformation.

    Science.gov (United States)

    Li, Ke; Hogrel, Jean-Yves; Duchêne, Jacques; Hewson, David J

    2012-09-01

    The objective of this study was to evaluate muscle fatigue and tremor during a Sustained Maximal Grip Contraction (SMGC) using the Hilbert-Huang Transformation (HHT). Thirty-nine healthy subjects volunteered for the study and performed a 25-s SMGC. Fatigue parameters such as the relative force output (RFO) were calculated from the residual of SMGC after applying Empirical Mode Decomposition (EMD). Using the energy spectrum of the Intrinsic Mode Functions (IMF) obtained using HHT, isometric force tremor was identified from the 4 to 12 Hz region in IMF3 and IMF4. Data were analysed for five consecutive 5-s epochs to identify changes in fatigue and tremor over time. The HHT method was able to identify a greater resistance to fatigue in women compared to men (p≤0.05) and in non-dominant hands compared to dominant hands (p≤0.05). Consistent with the results for fatigue, women had less tremor than men (p≤0.05), while non-dominant hands trembled less than did dominant hands (p≤0.05). Higher levels of tremor were observed for non-fatigue-resistant subjects for both 10-15 s and 15-20 s epochs (p≤0.05). The HHT is an appropriate method to identify both fatigue and tremor during SMGC. It would be of interest to apply this method to the study the elderly or patients with neuromuscular disorders.

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

    Directory of Open Access Journals (Sweden)

    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.

  10. The Parkfield tremors reveal slow and fast ruptures on the same asperity

    Science.gov (United States)

    Veedu, Deepa Mele; Barbot, Sylvain

    2016-04-01

    The deep extension of the San Andreas Fault is believed to be creeping, but the recent observations of tectonic tremors from these depths indicate a complex deformation style. In particular, an isolated tremor source near Parkfield has been producing a sequence of low-frequency earthquakes that indicates an uncommon mechanism of stress accumulation and release. The tremor pattern regularly oscillated between three and six days from mid-2003 until it was disrupted by the 2004 magnitude 6.0 Parkfield earthquake. After that event, the tremor source ruptured only about every three days, but over the next two years it gradually returned to its initial alternating recurrence pattern. The mechanism that drives this recurrence pattern is unknown. Here we use physics-based models to show that the same tremor asperity—the region from which the low-frequency earthquakes radiate—can regularly slip in slow and fast ruptures, naturally resulting in recurrence intervals alternating between three and six days. This unusual slip behaviour occurs when the tremor asperity size is close to the critical nucleation size of earthquakes. We also show that changes in pore pressure following the Parkfield earthquake can explain the sudden change and gradual recovery of the recurrence intervals. Our findings suggest a framework for fault deformation in which the same asperity can release tectonic stress through both slow and fast ruptures.

  11. Thyroid-Induced Worsening of Parkinsonian Tremor Resistant to Drugs and Subthalamic Nucleus Deep Brain Stimulation

    Directory of Open Access Journals (Sweden)

    Michal Minár

    2014-01-01

    Full Text Available Introduction. Symptoms of both hypothyroidism and thyrotoxicosis can be easily overlooked in patients with Parkinson’s disease (PD. We report on a patient whose parkinsonian tremor worsened and proved refractory not only to common treatment, but also to deep brain stimulation (DBS. Case Presentation. A 61-year-old woman with advanced PD underwent bilateral subthalamic DBS, with an excellent outcome. Twenty-one months after the surgery, however, patient’s resting/postural tremor markedly worsened. There was a slight improvement for 1 month after repeated adjustments of DBS parameters, but then the tremor worsened again. Since even a minimal increase of the dose of dopaminergic drugs caused extremely severe dyskinesias, an anticholinergic drug biperiden and benzodiazepine clonazepam were introduced, what helped for another month. With the onset of severe diarrhoea, a laboratory workup was performed. Thyrotoxicosis was detected. During treatment with the antithyroid agent carbimazole, the parkinsonian tremor clearly improved within two weeks. Conclusion. A hyperthyroid state can markedly exaggerate all forms of tremor, as well as other types of movement disorders. This condition can be overlooked or masked by other symptoms. Therefore, if the tremor in a patient with PD gradually worsens and proves resistant to the usual treatment, examine the thyroid gland.

  12. Methodology for estimating human perception to tremors in high-rise buildings

    Science.gov (United States)

    Du, Wenqi; Goh, Key Seng; Pan, Tso-Chien

    2017-07-01

    Human perception to tremors during earthquakes in high-rise buildings is usually associated with psychological discomfort such as fear and anxiety. This paper presents a methodology for estimating the level of perception to tremors for occupants living in high-rise buildings subjected to ground motion excitations. Unlike other approaches based on empirical or historical data, the proposed methodology performs a regression analysis using the analytical results of two generic models of 15 and 30 stories. The recorded ground motions in Singapore are collected and modified for structural response analyses. Simple predictive models are then developed to estimate the perception level to tremors based on a proposed ground motion intensity parameter—the average response spectrum intensity in the period range between 0.1 and 2.0 s. These models can be used to predict the percentage of occupants in high-rise buildings who may perceive the tremors at a given ground motion intensity. Furthermore, the models are validated with two recent tremor events reportedly felt in Singapore. It is found that the estimated results match reasonably well with the reports in the local newspapers and from the authorities. The proposed methodology is applicable to urban regions where people living in high-rise buildings might feel tremors during earthquakes.

  13. Io. [theories concerning volcanic activity

    Science.gov (United States)

    Johnson, T. V.; Soderblom, L. A.

    1983-01-01

    A report on the continuing investigation of Io is presented. Gravitational resonance is discussed as the cause of Io's volcanism, and the volcanic activity is explained in terms of sulfur chemistry. Theories concerning the reasons for the two main types of volcanic eruptions on Io are advanced and correlated with geographical features of the satellite. The sulfur and silicate models of the calderas are presented, citing the strengths and weaknesses of each. Problems of the gravitational resonance theory of Io's heat source are then described. Finally, observations of Io planned for the Galileo mission are summarized.

  14. Gauge and Gravity Amplitude Relations

    CERN Document Server

    Carrasco, John Joseph M

    2015-01-01

    In these lectures I talk about simplifications and universalities found in scattering amplitudes for gauge and gravity theories. In contrast to Ward identities, which are understood to arise from familiar symmetries of the classical action, these structures are currently only understood in terms of graphical organizational principles, such as the gauge-theoretic color-kinematics duality and the gravitational double-copy structure, for local representations of multi-loop S-matrix elements. These graphical principles make manifest new relationships in and between gauge and gravity scattering amplitudes. My lectures will focus on arriving at such graphical organizations for generic theories with examples presented from maximal supersymmetry, and their use in unitarity-based multi-loop integrand construction.

  15. High Amplitude Secondary Mass Drive

    Energy Technology Data Exchange (ETDEWEB)

    DYCK,CHRISTOPHER WILLIAM; ALLEN,JAMES J.; HUBER,ROBERT JOHN; SNIEGOWSKI,JEFFRY J.

    2000-07-06

    In this paper we describe a high amplitude electrostatic drive for surface micromachined mechanical oscillators that may be suitable for vibratory gyroscopes. It is an advanced design of a previously reported dual mass oscillator (Dyck, et. al., 1999). The structure is a 2 degree-of-freedom, parallel-plate driven motion amplifier, termed the secondary mass drive oscillator (SMD oscillator). During each cycle the device contacts the drive plates, generating large electrostatic forces. Peak-to-peak amplitudes of 54 {micro}m have been obtained by operating the structure in air with an applied voltage of 11 V. We describe the structure, present the analysis and design equations, and show recent results that have been obtained, including frequency response data, power dissipation, and out-of- plane motion.

  16. Infrared singularities in QCD amplitudes

    CERN Document Server

    Gardi, Einan

    2009-01-01

    We review recent progress in determining the infrared singularity structure of on-shell scattering amplitudes in massless gauge theories. We present a simple ansatz where soft singularities of any scattering amplitude of massless partons, to any loop order, are written as a sum over colour dipoles, governed by the cusp anomalous dimension. We explain how this formula was obtained, as the simplest solution to a newly-derived set of equations constraining the singularity structure to all orders. We emphasize the physical ideas underlying this derivation: the factorization of soft and collinear modes, the special properties of soft gluon interactions, and the notion of the cusp anomaly. Finally, we briefly discuss potential multi-loop contributions going beyond the sum-over-dipoles formula, which cannot be excluded at present.

  17. Pulse amplitude modulated chlorophyll fluorometer

    Energy Technology Data Exchange (ETDEWEB)

    Greenbaum, Elias; Wu, Jie

    2015-12-29

    Chlorophyll fluorometry may be used for detecting toxins in a sample because of changes in micro algae. A portable lab on a chip ("LOAC") based chlorophyll fluorometer may be used for toxin detection and environmental monitoring. In particular, the system may include a microfluidic pulse amplitude modulated ("PAM") chlorophyll fluorometer. The LOAC PAM chlorophyll fluorometer may analyze microalgae and cyanobacteria that grow naturally in source drinking water.

  18. All-Multiplicity Amplitudes with Massive Scalars

    CERN Document Server

    Forde, D; Forde, Darren; Kosower, David A.

    2005-01-01

    We compute two infinite series of tree-level amplitudes with a massive scalar pair and an arbitrary number of gluons. We provide results for amplitudes where all gluons have identical helicity, and amplitudes with one gluon of opposite helicity. These amplitudes are useful for unitarity-based one-loop calculations in nonsupersymmetric gauge theories generally, and QCD in particular.

  19. Crisis in Amplitude Control Hides in Multistability

    Science.gov (United States)

    Li, Chunbiao; Sprott, Julien Clinton; Xing, Hongyan

    2016-12-01

    A crisis of amplitude control can occur when a system is multistable. This paper proposes a new chaotic system with a line of equilibria to demonstrate the threat to amplitude control from multistability. The new symmetric system has two coefficients for amplitude control, one of which is a partial amplitude controller, while the other is a total amplitude controller that simultaneously controls the frequency. The amplitude parameter rescales the basins of attraction and triggers a state switch among different states resulting in a failure of amplitude control to the desired state.

  20. Head tremor in patients with cervical dystonia: different outcome? Tremor cefálico em pacientes com distonia cervical: evolução diferente?

    Directory of Open Access Journals (Sweden)

    Clecio Godeiro-Junior

    2008-12-01

    Full Text Available OBJECTIVE: The association of cervical dystonia (CD with other movement disorders have been already described, but data on clinical outcome regarding these patients are scant. The aim of this paper was to investigate whether patients with CD and head tremor (HT would have a different outcome regarding to botulinum toxin type-A (BTX-A treatment response and clinical and demographic parameters. METHOD: We retrospectively evaluated 118 medical charts of patients with CD and divided them into two groups: with (HT+ and without (HT- head tremor. We compared the following clinical and demographic parameters: age at onset, disease duration, progression of symptoms, etiology, familial history, presence of hand tremor. We also analyzed the response to BTX-A according to Tsui score in both groups. RESULTS: The occurrence of head tremor in our sample was of 38.2%. The occurrence of postural hand tremor in the patients from the HT+ group was higher than in the HT- one (p=0.015 and if we compare BTX-A response in each group, we observe that patients with HT present a better outcome in a setting of longer follow-up. In HT+ group, Tsui score pre treatment was 10 (6-12.5 and after follow-up was 8 (5.5-10.5; pOBJETIVO: A associação de distonia cervical (DC com outros transtornos do movimento já foi descrita, mas há poucos dados quanto à evolução clínica destes pacientes. Avaliamos se os pacientes com DC e tremor cefálico (TC apresentam características clínicas e demográficas, assim como a resposta ao tratamento com toxina botulínica tipo A, diferentes. MÉTODOS: Analisamos retrospectivamente 118 prontuários de pacientes com DC e os dividimos em dois grupos: com (TC+ e sem (TC- tremor cefálico. Comparamos os seguintes parâmetros clínicos e demográficos entre os grupos: idade de início, duração da doença, progressão de sintomas, etiologia, história familiar, presença de tremor em mãos. Também analisamos a resposta ao tratamento com toxina

  1. Applications of Terrestrial Remote Sensing to Volcanic Rock Masses

    Science.gov (United States)

    Dewit, M.; Williams-Jones, G.; Stead, D.; Kremsater, R.; So, M.; Francioni, M.

    2015-12-01

    Remote sensing methods are widely used in geological applications today. The physical properties of rock such as composition, texture and structure have previously been difficult to accurately quantify through remote sensing, however, new research in the fields of terrestrial LiDAR and infrared thermography has proven useful in the differentiation of lithology in sedimentary outcrops. This study focuses on the application of these methods, in conjunction with digital photogrammetry, to a number of volcanic rock masses in the Garibaldi Volcanic Belt (GVB) and Chilcotin Group (CG) of British Columbia. The GVB is a chain of volcanoes and related features extending through southwestern British Columbia and is the northern extension of the Cascade Volcanic Arc. The CG is an assemblage of Neogene-aged lavas covering nearly 36,500 km2 in central British Columbia. We integrate infrared chronothermography, which enables the characterization of temporal change in the thermal signature, laser waveform attributes such as amplitude and intensity, and digital photogrammetry, in order to distinguish between a range of rock types, lithologies and structures. This data is compared to laboratory experiments on field samples and ground-truth information collected by classical geological and geotechnical methods. Our research clearly shows that it is possible to remotely map, in 3D, otherwise inaccessible volcanic rock masses.

  2. Calculation of multi-loop superstring amplitudes

    Science.gov (United States)

    Danilov, G. S.

    2016-12-01

    The multi-loop interaction amplitudes in the closed, oriented superstring theory are obtained by the integration of local amplitudes. The local amplitude is represented by a sum over the spinning string local amplitudes. The spinning string local amplitudes are given explicitly through super-Schottky group parameters and through interaction vertex coordinates on the (1| 1) complex, non-split supermanifold. The obtained amplitudes are free from divergences. They are consistent with the world-sheet spinning string symmetries. The vacuum amplitude vanishes along with 1-, 2- and 3-point amplitudes of massless states. The vanishing of the above-mentioned amplitude occurs after the integration of the corresponding local amplitude has been performed over the super-Schottky group limiting points and over interaction vertex coordinate, except for those (3| 2) variables which are fixed due to SL(2)-symmetry.

  3. Volcanic eruptions observed with infrasound

    Science.gov (United States)

    Johnson, Jeffrey B.; Aster, Richard C.; Kyle, Philip R.

    2004-07-01

    Infrasonic airwaves produced by active volcanoes provide valuable insight into the eruption dynamics. Because the infrasonic pressure field may be directly associated with the flux rate of gas released at a volcanic vent, infrasound also enhances the efficacy of volcanic hazard monitoring and continuous studies of conduit processes. Here we present new results from Erebus, Fuego, and Villarrica volcanoes highlighting uses of infrasound for constraining quantitative eruption parameters, such as eruption duration, source mechanism, and explosive gas flux.

  4. Los volcanes y los hombres

    OpenAIRE

    García, Carmen

    2007-01-01

    Desde las entrañas de la tierra, los volcanes han creado la atmósfera, el agua de los océanos, y esculpido los relieves del planeta: son, pues, los zahoríes de la vida. Existen volcanes que los hombres explotan o cultivan, y otros sobre los cuales se han construido observatorios en los que se llevan a cabo avanzadas investigaciones científicas.

  5. Volcanic hazards and aviation safety

    Science.gov (United States)

    Casadevall, Thomas J.; Thompson, Theodore B.; Ewert, John W.; ,

    1996-01-01

    An aeronautical chart was developed to determine the relative proximity of volcanoes or ash clouds to the airports and flight corridors that may be affected by volcanic debris. The map aims to inform and increase awareness about the close spatial relationship between volcanoes and aviation operations. It shows the locations of the active volcanoes together with selected aeronautical navigation aids and great-circle routes. The map mitigates the threat that volcanic hazards pose to aircraft and improves aviation safety.

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

    Directory of Open Access Journals (Sweden)

    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.

  7. Volcanic Zone, New Zealand

    Directory of Open Access Journals (Sweden)

    Graham J. Weir

    2001-01-01

    Full Text Available A conceptual model of the Taupo Volcanic Zone (TVZ is developed, to a depth of 25 km, formed from three constant density layers. The upper layer is formed from eruption products. A constant rate of eruption is assumed, which eventually implies a constant rate of extension, and a constant rate of volumetric creation in the middle and bottom layers. Tectonic extension creates volume which can accomodate magmatic intrusions. Spreading models assume this volume is distributed throughout the whole region, perhaps in vertical dykes, whereas rifting models assume the upper crust is thinned and the volume created lies under this upper crust. Bounds on the heat flow from such magmatic intrusions are calculated. Heat flow calculations are performed and some examples are provided which match the present total heat output from the TVZ of about 4200 MW, but these either have extension rates greater than the low values of about 8 ± 4 mm/a being reported from GPS measurements, or else consider extension rates in the TVZ to have varied over time.

  8. Non-contact measurement of tremor for the characterisation of Parkinsonian individuals: comparison between Kinect and Laser Doppler vibrometer

    Science.gov (United States)

    Casacanditella, L.; Cosoli, G.; Ceravolo, MG; Tomasini, EP

    2017-08-01

    Parkinson’s disease is a progressive neurodegenerative disorder affecting the central nervous system. One of its main and most evident symptoms is the tremor, which usually manifests at rest with varying intensity during time. An important diagnostic challenge is the differential diagnosis between Parkinson’s disease and the other most widely represented tremor syndrome, i.e. Essential (or senile) tremor. At present there are no standard methods for the quantification of tremor and the diagnosis of both Parkinson’s disease and Essential tremor is mainly done on the base of clinical criteria and by using rating scales. The aim of this work is to objectively and non-invasively assess the tremor linked to the quoted diseases, using non-contact techniques: Laser Doppler Vibrometer (LDV) and Kinect for Windows device. Two subjects with Parkinson’s disease and one with Essential tremor were tested in different conditions: at rest, during a cognitive task, with forward stretched arms and in “Wing position”. The results from data processing in terms of tremor frequency seem to be comparable, with a mean deviation of 0.31 Hz. Furthermore, the values computed are consistent with what is stated in the literature (i.e. 4-12 Hz). So, both LDV and Kinect device can be considered suitable to be used as an objective means for the assessment and monitoring of Parkinson’s disease tremor, helping the clinician in the choice of the most suitable treatment for the patients.

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

    CERN Document Server

    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.

  10. LINGO-1 and Neurodegeneration: Pathophysiologic Clues for Essential Tremor.

    Science.gov (United States)

    Zhou, Zhi-Dong; Sathiyamoorthy, Sushmitha; Tan, Eng-King

    2012-01-01

    Essential tremor (ET), one of the most common adult-onset movement disorders, has been associated with cerebellar Purkinje cell degeneration and formation of brainstem Lewy bodies. Recent findings suggest that genetic variants of the leucine-rich repeat and Ig domain containing 1 (LINGO-1) gene could be risk factors for ET. The LINGO-1 protein contains both leucine-rich repeat (LRR) and immunoglobulin (Ig)-like domains in its extracellular region, as well as a transmembrane domain and a short cytoplasmic tail. LINGO-1 can form a ternary complex with Nogo-66 receptor (NgR1) and p75. Binding of LINGO-1 with NgR1 can activate the NgR1 signaling pathway, leading to inhibition of oligodendrocyte differentiation and myelination in the central nervous system. LINGO-1 has also been found to bind with epidermal growth factor receptor (EGFR) and induce downregulation of the activity of EGFR-PI3K-Akt signaling, which might decrease Purkinje cell survival. Therefore, it is possible that genetic variants of LINGO-1, either alone or in combination with other genetic or environmental factors, act to increase LINGO-1 expression levels in Purkinje cells and confer a risk to Purkinje cell survival in the cerebellum.Here, we provide a concise summary of the link between LINGO-1 and neurodegeneration and discuss various hypotheses as to how this could be potentially relevant to ET pathogenesis.

  11. Transcranial sonography on Parkinson′s disease and essential tremor

    Directory of Open Access Journals (Sweden)

    Ahmad Chitsaz

    2013-01-01

    Full Text Available Background: The study on transcranial sonocraphy (TCS as a diagnostic test for Parkinson′s disease (PD has been neglected in some hospitals. The current study was conducted as the first study to investigate the utility of TCS for diagnosis of PD and its ability to distinguish PD from essential tremor (ET in an Iranian population. Materials and Methods: TCS of substantia nigra (SN was performed on 50 PD, 48 ET, and 50 healthy controls by two blinded investigators. Results: Bilateral SN margin over 0.20 cm 2 was found in 39 (90% and 7 (15% in PD and ET patients, respectively. Furthermore, 4 (8% of healthy control displayed this particular echo feature as well (false positives. SN hyperechogenicity ≥0.20 cm 2 was considered as a cut-off point to detected PD. Accordingly, TCS proved 90% (95% confidence interval [CI]: 77.85-97.35 sensitive and 92% ( 95% CI: 80.75-97.73 specific for the detection of PD by visualizing the SN. Conclusion: SN hyperechogenicity ≥20 cm 2 is a specific feature of PD. Since, the symptoms of PD and ET might be overlapping; this method seems to be reliable to confirm PD diagnosis in doubtful clinical cases. Further studies in years to come are warranted to shed light on standardized data for Iranian to enhance the validity of TCS.

  12. Role of volcanic forcing on future global carbon cycle

    Directory of Open Access Journals (Sweden)

    J. F. Tjiputra

    2011-06-01

    Full Text Available Using a fully coupled global climate-carbon cycle model, we assess the potential role of volcanic eruptions on future projection of climate change and its associated carbon cycle feedback. The volcanic-like forcings are applied together with a business-as-usual IPCC-A2 carbon emissions scenario. We show that very large volcanic eruptions similar to Tambora lead to short-term substantial global cooling. However, over a long period, smaller eruptions similar to Pinatubo in amplitude, but set to occur frequently, would have a stronger impact on future climate change. In a scenario where the volcanic external forcings are prescribed with a five-year frequency, the induced cooling immediately lower the global temperature by more than one degree before it returns to the warming trend. Therefore, the climate change is approximately delayed by several decades, and by the end of the 21st century, the warming is still below two degrees when compared to the present day period. Our climate-carbon feedback analysis shows that future volcanic eruptions induce positive feedbacks (i.e., more carbon sink on both the terrestrial and oceanic carbon cycle. The feedback signal on the ocean is consistently smaller than the terrestrial counterpart and the feedback strength is proportionally related to the frequency of the volcanic eruption events. The cooler climate reduces the terrestrial heterotrophic respiration in the northern high latitude and increases net primary production in the tropics, which contributes to more than 45 % increase in accumulated carbon uptake over land. The increased solubility of CO2 gas in seawater associated with cooler SST is offset by a reduced CO2 partial pressure gradient between the ocean and the atmosphere, which results in small changes in net ocean carbon uptake. Similarly, there is nearly no change in the seawater buffer capacity simulated between the different volcanic scenarios. Our study shows that even

  13. Role of volcanic forcing on future global carbon cycle

    Science.gov (United States)

    Tjiputra, J. F.; Otterå, O. H.

    2011-06-01

    Using a fully coupled global climate-carbon cycle model, we assess the potential role of volcanic eruptions on future projection of climate change and its associated carbon cycle feedback. The volcanic-like forcings are applied together with a business-as-usual IPCC-A2 carbon emissions scenario. We show that very large volcanic eruptions similar to Tambora lead to short-term substantial global cooling. However, over a long period, smaller eruptions similar to Pinatubo in amplitude, but set to occur frequently, would have a stronger impact on future climate change. In a scenario where the volcanic external forcings are prescribed with a five-year frequency, the induced cooling immediately lower the global temperature by more than one degree before it returns to the warming trend. Therefore, the climate change is approximately delayed by several decades, and by the end of the 21st century, the warming is still below two degrees when compared to the present day period. Our climate-carbon feedback analysis shows that future volcanic eruptions induce positive feedbacks (i.e., more carbon sink) on both the terrestrial and oceanic carbon cycle. The feedback signal on the ocean is consistently smaller than the terrestrial counterpart and the feedback strength is proportionally related to the frequency of the volcanic eruption events. The cooler climate reduces the terrestrial heterotrophic respiration in the northern high latitude and increases net primary production in the tropics, which contributes to more than 45 % increase in accumulated carbon uptake over land. The increased solubility of CO2 gas in seawater associated with cooler SST is offset by a reduced CO2 partial pressure gradient between the ocean and the atmosphere, which results in small changes in net ocean carbon uptake. Similarly, there is nearly no change in the seawater buffer capacity simulated between the different volcanic scenarios. Our study shows that even in the relatively extreme scenario where

  14. Subthalamic and Cortical Local Field Potentials Associated with Pilocarpine-Induced Oral Tremor in the Rat.

    Science.gov (United States)

    Long, Lauren L; Podurgiel, Samantha J; Haque, Aileen F; Errante, Emily L; Chrobak, James J; Salamone, John D

    2016-01-01

    Tremulous jaw movements (TJMs) are rapid vertical deflections of the lower jaw that resemble chewing but are not directed at any particular stimulus. In rodents, TJMs are induced by neurochemical conditions that parallel those seen in human Parkinsonism, including neurotoxic or pharmacological depletion of striatal dopamine (DA), DA antagonism, and cholinomimetic administration. Moreover, TJMs in rodents can be attenuated by antiparkinsonian agents, including levodopa (L-DOPA), DA agonists, muscarinic antagonists, and adenosine A2A antagonists. In human Parkinsonian patients, exaggerated physiological synchrony is seen in the beta frequency band in various parts of the cortical/basal ganglia/thalamic circuitry, and activity in the tremor frequency range (3-7 Hz) also has been recorded. The present studies were undertaken to determine if tremor-related local field potential (LFP) activity could be recorded from motor cortex (M1) or subthalamic nucleus (STN) during the TJMs induced by the muscarinic agonist pilocarpine, which is a well-known tremorogenic agent. Pilocarpine induced a robust TJM response that was marked by rhythmic electromyographic (EMG) activity in the temporalis muscle. Compared to periods with no tremor activity, TJM epochs were characterized by increased LFP activity in the tremor frequency range in both neocortex and STN. Tremor activity was not associated with increased synchrony in the beta frequency band. These studies identified tremor-related LFP activity in parts of the cortical/basal ganglia circuitry that are involved in the pathophysiology of Parkinsonism. This research may ultimately lead to identification of the oscillatory neural mechanisms involved in the generation of tremulous activity, and promote development of novel treatments for tremor disorders.

  15. Differential analysis of muscle fatigue induced elbow and wrist tremor in controlled laparoscopic manoeuvring.

    Science.gov (United States)

    Chandra, Sourav; Hayashibe, Mitsuhiro; Thondiyath, Asokan; Ramalingam, Manickam

    2017-09-01

    Fatigue induced hand tremor (FIT) is a primary limiting concern for the prolonged surgical intervention in minimally invasive surgery (MIS) and robot-assisted-minimally invasive surgery (RAMIS). A thorough analysis is necessary to understand the FIT characteristics in laparoscopic tool movement. The primary aim of this study is to perform a differential analysis of the elbow and wrist tremor due to muscle fatigue in laparoscopic manoeuvring. We have introduced a joint angle based tremor analysis method, which enables us to perform a differential study of FIT characteristics at the individual joint. Experimental data was acquired from a group of subjects during static and dynamic laparoscopic movement in an imitative RAMIS master manipulation scenario. A repetitive task was performed with a total span of 1 h for observing the effect of muscle fatigue. Along with the joint angle variation, surface electromyography (sEMG) signal was also studied in the analysis. The wrist tremor is more predominant than tremor generated at the elbow, especially in highly fatigued condition. The high-frequency tremor (>4 Hz) is contributed by the wrist joint. Moreover, the variation of the wrist and elbow tremor ratio was found to be dependent upon the experience of the surgeons. In this work, we have investigated the attribution of elbow and wrist joints in FIT during laparoscopic tool manipulation. The outcomes may be useful for the design of robot-assisted surgical manipulator, and can be used for quality assessment of surgical training as well. Copyright © 2016 John Wiley & Sons, Ltd.

  16. Comparative study of tectonic tremor locations: Characterization of slow earthquakes in Guerrero, Mexico

    Science.gov (United States)

    Maury, J.; Ide, S.; Cruz-Atienza, V. M.; Kostoglodov, V.; González-Molina, G.; Pérez-Campos, X.

    2016-07-01

    Deep tectonic tremor in Guerrero, Mexico, has been observed using dense temporal seismic networks (i.e., the Meso-American Subduction Experiment and Guerrero Gap Experiment (G-GAP) arrays) during two different time periods. We apply a set of seismic waveform analysis methods to these data sets to constrain the locations of tremors and determine the associated moment tensors. First we detect and locate the tremors. Next, very low frequency (VLF) signals are identified by stacking waveform data during tremor bursts, and their moment tensors are determined. Finally, to better investigate the link between tremors and VLF earthquakes, we detect VLF events using a matched filtering algorithm to search continuous seismic records. None of the 11 VLF events detected by this method occurred in the absence of tremor bursts suggesting they are indeed part of the same phenomena. Unlike previous investigations, our results for the G-GAP period reveal that downdip tremor activity (i.e., in the so-called "sweet spot") is segmented into two patches separated by 40 km in the along-trench direction, indicating possible variations in the geometry of the plate interface and/or slab effective pressure. Moment tensors of VLF signals are consistent with shear slip on the near-horizontal plate interface, but source depths are about 5 km deeper than the established plate interface. The slip directions of the VLF events are slightly ( 10°) counterclockwise of the plate convergence direction, indicating that strain energy promoting left-lateral strike-slip motion may accumulate in the continental crust during the interseismic period.

  17. Differences in brain activation between tremor- and nontremor-dominant Parkinson disease.

    Science.gov (United States)

    Prodoehl, Janey; Planetta, Peggy J; Kurani, Ajay S; Comella, Cynthia L; Corcos, Daniel M; Vaillancourt, David E

    2013-01-01

    OBJECTIVE To compare differences in functional brain activity between tremor- and nontremor-dominant subtypes of Parkinson disease (PD) using functional magnetic resonance imaging. DESIGN In our study, patients with tremor-dominant PD and those with nontremor-dominant PD performed a grip task, and the results obtained were compared using voxelwise analysis. Areas of the brain that were significantly different were then examined using a region-of-interest analysis to compare these patients with healthy controls. Voxel-based morphometry was used to determine macroscopic differences in gray and white matter volume between patient groups. SETTING University-affiliated research institution. PARTICIPANTS A total of 20 drug-naive patients with PD (10 with tremor-dominant PD and 10 with nontremor-dominant PD) and a total of 20 healthy controls. MAIN OUTCOME MEASURES Blood oxygenation level-dependent activation and percent signal change. RESULTS Robust findings across both voxelwise and region-of-interest analyses showed that, compared with patients with tremor-dominant PD, patients with nontremor-dominant PD had reduced activation in the ipsilateral dorsolateral prefrontal cortex, the globus pallidus interna, and the globus pallidus externa. Region-of-interest analyses confirmed that patients with nontremor-dominant PD had reduced activity in the ipsilateral dorsolateral prefrontal cortex, the globus pallidus interna, and the globus pallidus externa compared with patients with tremor-dominant PD and healthy controls. Patients with tremor-dominant PD had increased activity in the contralateral dorsolateral prefrontal cortex compared with patients with nontremor-dominant PD and healthy controls. These results could not be explained by differences in gray or white matter volume. CONCLUSIONS Reduced brain activity occurs in the prefrontal cortex and globus pallidus of patients with nontremor-dominant PD compared with both patients with tremor-dominant PD and healthy controls

  18. Amplitude recruitment of cochlear potential

    Institute of Scientific and Technical Information of China (English)

    LI Xingqi; SUN Wei; SUN Jianhe; YU Ning; JIANG Sichang

    2001-01-01

    Intracellular recordings were made from outer hair cells (OHC) and the cochlear microphonics (CM) were recorded from scala media (SM) in three turn of guinea pig cochlea,the compound action potential (CAP) were recorded at the round window (RW) before and after the animal were exposed to white noise. The results suggest that the nonlinear properties with “saduration” of Input/output (I/O) function of OHC AC recepter potential and CM were founded; the nonlinear properties with “Low”, “Platean” and “high” of CAP also were investigated. After explosion, the threshold shift of CAP has about 10 dB. The I/O of OHC responses and CM were changed in a linearizing (i.e., nonlinearity loss), the “platean” of I/O CAP disappeared and the growth rate of CAP amplitude were larger than before explosion. The response amplitude recruitment of OHC appears to result from reduction in gain (i.e., hearing loss); It was due to the nonlinear growth function of OHC receptor potentials was changed in linearzing that the basilar membrance motion was changed in linearizing. Since intensity coding in the inner ear depends on an interactions of nonlinear basilar membrance and nerve fibers. So that it must lead to a linearizing of CAP as input responses.

  19. Quaternary basaltic volcanism in the Payenia volcanic province, Argentina

    DEFF Research Database (Denmark)

    Søager, Nina

    primitive basalts and trachybasalts but also more evolved samples from the retroarc region and the larger volcanoes Payún Matrú and Payún Liso are presented. The samples cover a broad range of compositions from intraplate lavas similar to ocean island basalts to arc andesites. A common feature found...... Pleistocene times. These basalts mark the end of a period of shallow subduction of the Nazca slab beneath the Payenia province and volcanism in the Nevado volcanic field apparently followed the downwarping slab in a north-northwest direction ending in the Northern Segment. The northern Payenia basalts...... the literature. The Nevado basalts have been modelled by 4-10 % melting of a primitive mantle added 1-5 % upper continental crust. In the southern Payenia province, intraplate basalts dominate. The samples from the Payún Matrú and Río Colorado volcanic fields are apparently unaffected by the subducting slab...

  20. Mirtazapine in essential tremor: a double-blind, placebo-controlled pilot study.

    Science.gov (United States)

    Pahwa, Rajesh; Lyons, Kelly E

    2003-05-01

    We sought to determine whether mirtazapine is safe and well-tolerated as a treatment for essential tremor (ET). We studied mirtazapine in a randomized, double-blind, placebo-controlled, crossover study of 17 ET patients. Patients were started with 15 mg per day of either mirtazapine or placebo for 1 week and the dose was escalated weekly until the targeted dose of 45 mg per day was achieved. This dose was maintained for 2 weeks. Tremor was assessed at baseline and after 14 days of 45 mg of mirtazapine or placebo. There was a minimum washout period of 14 days between the two arms of the study. Tremor assessments included global improvement, Fahn Tolosa Marin Tremor Rating Scale, Beck Depression Inventory and the Parkinson's Disease Questionnaire-39. Patient global improvement ratings indicated that in the placebo condition 12 patients were unchanged and 1 patient was mildly improved. In the mirtazapine condition, 10 patients were unchanged, 2 were moderately improved and 1 was markedly improved. There was no significant improvement with mirtazapine or placebo compared to baseline as measured by the Tremor Rating Scale. Adverse effects were more common in the mirtazapine group and included drowsiness, confusion, dry mouth, weight gain, polyuria, itching, nausea, gait and balance problems, blurred vision, and bad taste. We conclude that the majority of the ET patients do not benefit from mirtazapine. Mirtazapine has significant adverse effects and should be used cautiously in ET patients.

  1. Dystonia and tremor following exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin

    Energy Technology Data Exchange (ETDEWEB)

    Klawans, H.L.

    1987-01-01

    Forty-seven railroad workers who were exposed to polychlorinated phenols, including dioxin (TCDD), during 1979 while cleaning up the chemical spillage following damage to a tank car filled with these chemicals were followed medically for the subsequent 6 years. Two committed suicide. The initial neurological complaints included a sense of fatigue and muscle aching, both of which have been reported in other individuals following dioxin exposure. On detailed neurological examination in December, 1985, 24 of 45 had dystonic writer's cramp and/or other action dystonias of the hands. None of the involved individuals had a family history of dystonia, and all 24 dated the onset of the dystonia to the first 2 to 3 years subsequent to their toxic exposure. The dystonias varied in severity but were usually mild. No other types of dystonic involvement were recognized. Thirty-five of the 45 individuals also manifested postural and terminal intention tremor which resembled benign essential tremor. None of the involved individuals had a family history of tremor, and all 35 of those affected dated the onset of the tremor to some time subsequent to their toxic exposure. Forty-three of 45 patients had histories and findings suggestive of peripheral neuropathy. This is the first report relating any type of dystonia to prior dioxin exposure and the first report relating action dystonia, such as dystonic writer's cramp, and postural/terminal intention tremor, to toxic exposure of any type.

  2. Pramipexole, a nonergot dopamine agonist, is effective against rest tremor in intermediate to advanced Parkinson's disease.

    Science.gov (United States)

    Künig, G; Pogarell, O; Möller, J C; Delf, M; Oertel, W H

    1999-01-01

    We evaluated the efficacy of the nonergot dopamine receptor agonist pramipexole in 16 patients with advanced Parkinson's disease and marked rest tremor during an "on" period. The patients were drawn from a larger placebo-controlled, double-blind, randomized trial, which was not originally designed to investigate the effect of pramipexole on tremor. Eleven patients received pramipexole. The first effects were seen with a pramipexole dose of 0.75 mg/d with a reduction of the tremor item A of Unified Parkinson's Disease Rating Scale (UPDRS III, "on" state) by 25% and of rigidity and akinesia by 22%. Under the highest dose, 4.5 mg/d, the tremor score was improved by 61% over baseline (p < 0.0056, Wilcoxon signed rank) and the sum of rigidity and akinesia items by 66% (p < 0.0038, Wilcoxon signed rank). Five patients received placebo and did not improve. Based on this sample of patients, the nonergot dopamine receptor agonist pramipexole appears to have a potent anti-rest tremor action while being effective against akinesia and rigidity.

  3. Frequency and Factors of Tremor, Palpitation, and Cramp in Patients with COPD and Asthma

    Directory of Open Access Journals (Sweden)

    Sema Demir

    2015-04-01

    Full Text Available Objective: To evaluate the frequency and predictability of side effects, including tremor, cramp, and palpitation, due to treatment in patients with chronic obstructive pulmonary disease and asthma. Methods: We prepared a standard questionnaire for 299 patients concerning their diagnosis, treatment, and side effects of the treatment in February 2007 at Hacettepe University, Faculty of Medicine, Department of Pulmonary Diseases. We prospectively examined the clinical status of the patients and side effects of the treatment at the 15th, 30th, and 180th days of the treatment. Results: In our study, there were 38 (12.7% patients with drug-induced tremor. Of these, 27 (71.1% had asthma (p=0.004 and 18 (47.4% had anamnestic palpitation. Drug-induced tremor risk was 15.3 times higher in patients who used a beta-mimetic compared with those who used any drugs. Cramp risk increased with beta-mimetic use only. In our study, drug-induced tremor was still present at the 180th day of examination in 32 (84.2% patients. Conclusion: This study demonstrated that side effects, including tremor, palpitation, and cramp, were more common in our patients compared with those in other studies. These side effects were directly related to the primary disease and the use of beta-2-agonists. Another finding of our study is that tolerance did not develop as much as that reported in literature.

  4. A Pilot Study of Botulinum Toxin for Jerky, Position-Specific, Upper Limb Action Tremor

    Science.gov (United States)

    Saifee, Tabish A.; Teodoro, Tiago; Erro, Roberto; Edwards, Mark J.; Cordivari, Carla

    2016-01-01

    Background We aimed to investigate the efficacy and safety of botulinum toxin (BT) injections for jerky action tremor of the upper limb. Methods We performed an uncontrolled, prospective study of electromyography (EMG)-guided BT injections for jerky, position-specific, upper limb action tremor. The primary outcome was clinical global impression at 3–6 weeks after baseline. Results Eight patients with jerky, position-specific action tremor involving the upper limb were consecutively recruited. After a median follow-up of 4.4 weeks (interquartile range [IQR] 3.6–6 weeks), four of them rated themselves as “improved” and two as “much improved.” Five of these six subjects reported improvements in specific activities of daily living (bringing liquids to mouth, feeding, shaving, and dressing). Upper limb subscore of the Fahn–Tolosa–Marin Tremor Rating Scale (FTM) significantly decreased from 4.5 (4–6) to 3 (2–5) (p = 0.01). Discussion This pilot, prospective cohort study suggests that EMG-guided BT injections may improve jerky, position-specific, upper limb action tremor. Placebo-controlled studies evaluating larger samples of patients are warranted to confirm these findings. PMID:27818844

  5. Tectonic tremor and microseismicity associated with shallow slow slip along the northern Hikurangi Margin, New Zealand

    Science.gov (United States)

    Todd, E. K.; Schwartz, S. Y.

    2015-12-01

    The detection of circum-Pacific slow slip events (SSEs) along with associated tectonic tremor and microseismicity has led to numerous investigations into the modes and timescales of deformation in subduction zone boundaries. This discovery has shed light on a broader range of strain release processes that range from aseismic creep at plate convergence rates (cm/yr) to traditional earthquake slip rates (m/s). The largest SSEs along the northern Hikurangi subduction margin occur offshore Gisborne, New Zealand every 18-24 months at depths less than 15 km. We present a systematic investigation of tremor and microseismicity associated with these shallow SSEs from 2010 to the present using land data from the New Zealand National Seismograph Network operated by GeoNet (http://geonet.org.nz) and ocean-bottom data from the Hikurangi Ocean Bottom Investigation of Tremor and Slow Slip (HOBITSS) project. The HOBITSS project deployed an array of ocean-bottom seismometers and absolute pressure gauges between May 2014 and June 2015 above the Gisborne SSE patch. These instruments were in place during a large SSE in September/October 2014. Tremor and seismicity associated with Gisborne SSEs primarily occur along the downdip edge of the slip patch, but the addition of data from ocean-bottom stations located directly above the slip patch will reveal the updip extent of tremor and microseismicity related to these SSEs.

  6. Atmospheric chemistry in volcanic plumes.

    Science.gov (United States)

    von Glasow, Roland

    2010-04-13

    Recent field observations have shown that the atmospheric plumes of quiescently degassing volcanoes are chemically very active, pointing to the role of chemical cycles involving halogen species and heterogeneous reactions on aerosol particles that have previously been unexplored for this type of volcanic plumes. Key features of these measurements can be reproduced by numerical models such as the one employed in this study. The model shows sustained high levels of reactive bromine in the plume, leading to extensive ozone destruction, that, depending on plume dispersal, can be maintained for several days. The very high concentrations of sulfur dioxide in the volcanic plume reduces the lifetime of the OH radical drastically, so that it is virtually absent in the volcanic plume. This would imply an increased lifetime of methane in volcanic plumes, unless reactive chlorine chemistry in the plume is strong enough to offset the lack of OH chemistry. A further effect of bromine chemistry in addition to ozone destruction shown by the model studies presented here, is the oxidation of mercury. This relates to mercury that has been coemitted with bromine from the volcano but also to background atmospheric mercury. The rapid oxidation of mercury implies a drastically reduced atmospheric lifetime of mercury so that the contribution of volcanic mercury to the atmospheric background might be less than previously thought. However, the implications, especially health and environmental effects due to deposition, might be substantial and warrant further studies, especially field measurements to test this hypothesis.

  7. Climatic impact of volcanic eruptions

    Science.gov (United States)

    Rampino, Michael R.

    1991-01-01

    Studies have attempted to 'isolate' the volcanic signal in noisy temperature data. This assumes that it is possible to isolate a distinct volcanic signal in a record that may have a combination of forcings (ENSO, solar variability, random fluctuations, volcanism) that all interact. The key to discovering the greatest effects of volcanoes on short-term climate may be to concentrate on temperatures in regions where the effects of aerosol clouds may be amplified by perturbed atmospheric circulation patterns. This is especially true in subpolar and midlatitude areas affected by changes in the position of the polar front. Such climatic perturbation can be detected in proxy evidence such as decrease in tree-ring widths and frost rings, changes in the treeline, weather anomalies, severity of sea-ice in polar and subpolar regions, and poor grain yields and crop failures. In low latitudes, sudden temperature drops were correlated with the passage overhead of the volcanic dust cloud (Stothers, 1984). For some eruptions, such as Tambora, 1815, these kinds of proxy and anectdotal information were summarized in great detail in a number of papers and books (e.g., Post, 1978; Stothers, 1984; Stommel and Stommel, 1986; C. R. Harrington, in press). These studies lead to the general conclusion that regional effects on climate, sometimes quite severe, may be the major impact of large historical volcanic aerosol clouds.

  8. Relations Between Helicity Coupling Amplitude and L-S Coupling Amplitude

    Institute of Scientific and Technical Information of China (English)

    WU Ning; RUAN Tu-Nan

    2001-01-01

    Relations between helicity coupling amplitude and L-S coupling amplitude are discussed. The equivalence condition for these two kinematic analysis methods and the limitations of the L-S coupling amplitude are also studied in this paper.``

  9. Grassmannian geometry of scattering amplitudes

    CERN Document Server

    Arkani-Hamed, Nima; Cachazo, Freddy; Goncharov, Alexander; Postnikov, Alexander; Trnka, Jaroslav

    2016-01-01

    Outlining a revolutionary reformulation of the foundations of perturbative quantum field theory, this book is a self-contained and authoritative analysis of the application of this new formulation to the case of planar, maximally supersymmetric Yang–Mills theory. The book begins by deriving connections between scattering amplitudes and Grassmannian geometry from first principles before introducing novel physical and mathematical ideas in a systematic manner accessible to both physicists and mathematicians. The principle players in this process are on-shell functions which are closely related to certain sub-strata of Grassmannian manifolds called positroids - in terms of which the classification of on-shell functions and their relations becomes combinatorially manifest. This is an essential introduction to the geometry and combinatorics of the positroid stratification of the Grassmannian and an ideal text for advanced students and researchers working in the areas of field theory, high energy physics, and the...

  10. Holonomy-flux spinfoam amplitude

    CERN Document Server

    Perini, Claudio

    2012-01-01

    We introduce a holomorphic representation for the Lorentzian EPRL spinfoam on arbitrary 2-complexes. The representation is obtained via the Ashtekar-Lewandowski-Marolf-Mour\\~ao-Thiemann heat kernel coherent state transform. The new variables are classical holonomy-flux phase space variables $(h,X)\\simeq \\mathcal T^*SU(2)$ of Hamiltonian loop quantum gravity prescribing the holonomies of the Ashtekar connection $A=\\Gamma + \\gamma K$, and their conjugate gravitational fluxes. For small heat kernel `time' the spinfoam amplitude is peaked on classical space-time geometries, where at most countably many curvatures are allowed for non-zero Barbero-Immirzi parameter. We briefly comment on the possibility to use the alternative flipped classical limit.

  11. Constructing Amplitudes from Their Soft Limits

    Energy Technology Data Exchange (ETDEWEB)

    Boucher-Veronneau, Camille; Larkoski, Andrew J.; /SLAC

    2011-12-09

    The existence of universal soft limits for gauge-theory and gravity amplitudes has been known for a long time. The properties of the soft limits have been exploited in numerous ways; in particular for relating an n-point amplitude to an (n-1)-point amplitude by removing a soft particle. Recently, a procedure called inverse soft was developed by which 'soft' particles can be systematically added to an amplitude to construct a higher-point amplitude for generic kinematics. We review this procedure and relate it to Britto-Cachazo-Feng-Witten recursion. We show that all tree-level amplitudes in gauge theory and gravity up through seven points can be constructed in this way, as well as certain classes of NMHV gauge-theory amplitudes with any number of external legs. This provides us with a systematic procedure for constructing amplitudes solely from their soft limits.

  12. Constructing amplitudes from their soft limits

    Science.gov (United States)

    Boucher-Veronneau, Camille; Larkoski, Andrew J.

    2011-09-01

    The existence of universal soft limits for gauge-theory and gravity amplitudes has been known for a long time. The properties of the soft limits have been exploited in numerous ways; in particular for relating an n-point amplitude to an ( n - 1)-point amplitude by removing a soft particle. Recently, a procedure called inverse soft was developed by which "soft" particles can be systematically added to an amplitude to construct a higher-point amplitude for generic kinematics. We review this procedure and relate it to Britto-Cachazo-Feng-Witten recursion. We show that all tree-level amplitudes in gauge theory and gravity up through seven points can be constructed in this way, as well as certain classes of NMHV gauge-theory amplitudes with any number of external legs. This provides us with a systematic procedure for constructing amplitudes solely from their soft limits.

  13. O terramoto de Lisboa de 1755: tremores e temores

    Directory of Open Access Journals (Sweden)

    María José Ferro TAVARES

    2009-11-01

    Full Text Available RESUMEN: Con anterioridad al gran terremoto de 1755 ya se habían registrado en Portugal temblores de tierra de intensidad bastante significativa. En la actualidad, las cartas sismotectónicas enseñan que tanto la región de la Gran Lisboa, como la costa sur atlántica y costa algarvia son las que presentan mayor peligrosidad sísmica. Los temblores de tierra fueron desde siempre un asunto de preocupación para la población portuguesa que habitaba estas regiones, provocando temores y fobias que fueron transmitidos de generación en generación. En el presente trabajo se procura identificar las señales de cambios o de continuidad en la población portuguesa y las reacciones ante los efectos de los terremotos que desde tiempos remotos afectaran al país. Particular atención es atribuida a las interpretaciones de raíz escatológica, las primeras que surgieron y que gradualmente fueran sustituidas en el siglo XVII por explicaciones que invocaban la existencia de causas primeras (divinas y causas segundas (naturales en la discusión de este tipo de fenómenos. Va a ser con el terremoto de Lisboa, en 1755, cuando la experimentación surge como medio de explicación, inicialmente apenas en términos retóricos, para después, a partir del siglo XIX, en términos científicos, sustentar la aparición y desarrollo de la propia sismología. En Portugal, mientras exista un copioso acervo bibliográfico en lo que concierne a las referidas explicaciones, una actitud pragmática ante los terremotos ha prevalecido siempre, en el sentido de que es siempre más importante mitigar sus efectos, particularmente los efectos en la salud pública en lo que se refiere al terremoto de Lisboa, que determinar sus causas exactas.ABSTRACT: Before the great Lisbon earthquake of 1755 the continental part of Portugal had already experienced strong, catastrophic tremors; present day seismotectonic maps show that indeed the metropolitan area of the capital city, as well as

  14. O terramoto de Lisboa de 1755: tremores e temores

    Directory of Open Access Journals (Sweden)

    María José Ferro TAVARES

    2009-11-01

    Full Text Available RESUMEN: Con anterioridad al gran terremoto de 1755 ya se habían registrado en Portugal temblores de tierra de intensidad bastante significativa. En la actualidad, las cartas sismotectónicas enseñan que tanto la región de la Gran Lisboa, como la costa sur atlántica y costa algarvia son las que presentan mayor peligrosidad sísmica. Los temblores de tierra fueron desde siempre un asunto de preocupación para la población portuguesa que habitaba estas regiones, provocando temores y fobias que fueron transmitidos de generación en generación. En el presente trabajo se procura identificar las señales de cambios o de continuidad en la población portuguesa y las reacciones ante los efectos de los terremotos que desde tiempos remotos afectaran al país. Particular atención es atribuida a las interpretaciones de raíz escatológica, las primeras que surgieron y que gradualmente fueran sustituidas en el siglo XVII por explicaciones que invocaban la existencia de causas primeras (divinas y causas segundas (naturales en la discusión de este tipo de fenómenos. Va a ser con el terremoto de Lisboa, en 1755, cuando la experimentación surge como medio de explicación, inicialmente apenas en términos retóricos, para después, a partir del siglo XIX, en términos científicos, sustentar la aparición y desarrollo de la propia sismología. En Portugal, mientras exista un copioso acervo bibliográfico en lo que concierne a las referidas explicaciones, una actitud pragmática ante los terremotos ha prevalecido siempre, en el sentido de que es siempre más importante mitigar sus efectos, particularmente los efectos en la salud pública en lo que se refiere al terremoto de Lisboa, que determinar sus causas exactas.ABSTRACT: Before the great Lisbon earthquake of 1755 the continental part of Portugal had already experienced strong, catastrophic tremors; present day seismotectonic maps show that indeed the metropolitan area of the capital city, as well as

  15. Increased LINGO1 in the cerebellum of essential tremor patients.

    Science.gov (United States)

    Delay, Charlotte; Tremblay, Cyntia; Brochu, Elodie; Paris-Robidas, Sarah; Emond, Vincent; Rajput, Ali H; Rajput, Alex; Calon, Frédéric

    2014-11-01

    Essential tremor (ET) is the most prevalent adult-onset movement disorder. Despite its health burden, no clear pathognomonic sign has been identified to date because of the rarity of clinicopathological studies. Moreover, treatment options are still scarce and have not significantly changed in the last 30 years, underscoring the urgent need to develop new treatment avenues. In the recent years, leucine-rich repeat (LRR) and immunoglobulin (Ig) domain-containing Nogo receptor-interacting proteins 1 and 2 (LINGO1 and LINGO2, respectively) have been increasingly regarded as possible ET modulators due to emerging genetic association studies linking LINGO with ET. We have investigated LINGO protein and messenger RNA (mRNA) expression in the cerebellum of patients with ET, patients with Parkinson's disease (PD), and a control group using Western immunoblotting and in situ hybridization. Protein levels of LINGO1, but not LINGO2, were significantly increased in the cerebellar cortex of ET patients compared with controls, particularly in individuals with longer disease duration. Compared with controls, LINGO1 protein levels were increased in the cerebellar white matter of PD and ET patients but, for the latter, only when disease duration exceeded 20 years. However, no alteration in LINGO1 mRNA was observed between groups in either the cerebellar cortex or the white matter. We observed alterations in LINGO expression in diseased brain that seemed to progress along with the disease, being initiated in the cerebellar cortex before reaching the white matter. Because LINGO up-regulation has been identified as a potential pathological response to ongoing neurodegenerative processes, the present data suggest that LINGO1 is a potential drug target for ET.

  16. Visual function alterations in essential tremor: A case report

    Directory of Open Access Journals (Sweden)

    David P. Piñero

    2015-09-01

    Full Text Available Our purpose is to report alterations in contrast sensitivity function (CSF and in the magno, parvo and koniocellular visual pathways by means of a multichannel perimeter in case of an essential tremor (ET. A complete evaluation of the visual function was performed in a 69-year old patient, including the analysis of the chromatic discrimination by the Fansworth–Munsell 100 hue test, the measurement of the CSF by the CSV-1000E test, and the detection of potential alteration patterns in the magno, parvo and koniocellular visual pathways by means of a multichannel perimeter. Visual acuity and intraocular pressure (IOP were within the ranges of normality in both eyes. No abnormalities were detected in the fundoscopic examination and in the optical coherence tomography (OCT exam. The results of the color vision examination were also within the ranges of normality. A significant decrease in the achromatic CSFs for right eye (RE and left eye (LE was detected for all spatial frequencies. The statistical global values provided by the multichannel perimeter confirms that there were significant absolute sensitivity losses compared to the normal pattern in RE. In the LE, only a statistically significant decrease in sensitivity was detected for the blue-yellow (BY channel. The pattern standard deviation (PSD values obtained in our patient indicated that there were significant localized losses compared to the normality pattern in the achromatic channel of the RE and in the red-green (RG channel of the LE. Some color vision alterations may be present in ET that cannot be detected with conventional color vision tests, such as the FM 100 Hue.

  17. A Note on Loop Amplitudes in QED

    CERN Document Server

    Brandhuber, Andreas; Vincon, Massimiliano

    2009-01-01

    We consider the two-loop four-point amplitude in N=2 super QED, and show that there exists an approximate recursive structure similar to that captured by the ABDK/BDS ansatz for MHV amplitudes in N=4 super Yang-Mills. Furthermore, we present a simple relation between the box coefficients of one-loop photon MHV amplitudes in (super) QED, and sums of box coefficients of one-loop MHV amplitudes in (super) Yang-Mills.

  18. Aurorae and Volcanic Eruptions

    Science.gov (United States)

    2001-06-01

    Thermal-IR Observations of Jupiter and Io with ISAAC at the VLT Summary Impressive thermal-infrared images have been obtained of the giant planet Jupiter during tests of a new detector in the ISAAC instrument on the ESO Very Large Telescope (VLT) at the Paranal Observatory (Chile). . They show in particular the full extent of the northern auroral ring and part of the southern aurora. A volcanic eruption was also imaged on Io , the very active inner Jovian moon. Although these observations are of an experimental nature, they demonstrate a great potential for regular monitoring of the Jovian magnetosphere by ground-based telescopes together with space-based facilities. They also provide the added benefit of direct comparison with the terrestrial magnetosphere. PR Photo 21a/01 : ISAAC image of Jupiter (L-band: 3.5-4.0 µm) . PR Photo 21b/01 : ISAAC image of Jupiter (Narrow-band 4.07 µm) . PR Photo 21c/01 : ISAAC image of Jupiter (Narrow-band 3.28 µm) . PR Photo 21d/01 : ISAAC image of Jupiter (Narrow-band 3.21 µm) . PR Photo 21e/01 : ISAAC image of the Jovian aurorae (false-colour). PR Photo 21f/01 : ISAAC image of volcanic activity on Io . Addendum : The Jovian aurorae and polar haze. Aladdin Meets Jupiter Thermal-infrared images of Jupiter and its volcanic moon Io have been obtained during a series of system tests with the new Aladdin detector in the Infrared Spectrometer And Array Camera (ISAAC) , in combination with an upgrade of the ESO-developed detector control electronics IRACE. This state-of-the-art instrument is attached to the 8.2-m VLT ANTU telescope at the ESO Paranal Observatory. The observations were made on November 14, 2000, through various filters that isolate selected wavebands in the thermal-infrared spectral region [1]. They include a broad-band L-filter (wavelength interval 3.5 - 4.0 µm) as well as several narrow-band filters (3.21, 3.28 and 4.07 µm). The filters allow to record the light from different components of the Jovian atmosphere

  19. Speckle interferometric sensor to measure low-amplitude high frequency Ocular Microtremor (OMT)

    Science.gov (United States)

    Ryle, James P.; Al-Kalbani, Mohammed; Gopinathan, Unnikrishnan; Boyle, Gerard; Coakley, Davis; Sheridan, John T.

    2009-08-01

    Ocular microtremor (OMT) is a physiological high frequency (up to 150Hz) low amplitude (150-2500nm) involuntary tremor of the human eye. It is one of the three fixational ocular motions described by Adler and Fliegelman in 1934 as well as microsaccades and drift. Clinical OMT investigations to date have used eye-contacting piezoelectric probes or piezoelectric strain gauges. Before contact can be made, the eye must first be anaesthetised. In some cases, this induces eyelid spasms (blepharospasm) making it impossible to measure OMT. Using the contact probe method, the eye motion is mechanically damped. In addition to this, it is not possible to obtain exact information about the displacement. Results from clinical studies to date have given electrical signal amplitudes from the probe. Recent studies suggest a number of clinical applications for OMT, these include monitoring the depth of anaesthesia of a patient in surgery, prediction of outcome in coma, diagnosis of brainstem death. In addition to this, abnormal OMT frequency content is present in patients with neurological disorders such as Multiple sclerosis and Parkinson's disease. However for ongoing clinical investigations the contact probe method falls short of a non-contact accurate measurement solution. In this paper, we design a compact non contact phase modulating optical fiber speckle interferometer to measure eye motions. We present our calibration results using a calibrated piezoelectric vibration simulator. Digital signal processing is then performed to extract the low amplitude high frequency displacement information.

  20. Geopulsation, Volcanism and Astronomical Periods

    Institute of Scientific and Technical Information of China (English)

    Yang Xuexiang; Chen Dianyou; Yang Xiaoying; Yang Shuchen

    2000-01-01

    Volcanism is mainly controlled by the intermittent release of energy in the earth. As far as the differential rotation of the earth's inner core is concerned, the Galactic Year may change the gravitational constant G, the solar radiative quantity and the moving speed of the solar system and affect the exchange of angular momentum between core and mantle as well as the energy exchange between crust and mantle. As a result, this leads to eruptions of superplumes and magma, and controls the energy flow from core - mantle boundary (CMB) to crust. When the earth' s speed decreases, it will release a huge amount of energy. They are the reason of the correspondence of the volcanic cycles one by one with the astronomical periods one by one. According to the astronomical periods, volcanic eruptions may possibly be predicted in the future.

  1. Volcanic eruptions and solar activity

    Science.gov (United States)

    Stothers, Richard B.

    1989-01-01

    The historical record of large volcanic eruptions from 1500 to 1980 is subjected to detailed time series analysis. In two weak but probably statistically significant periodicities of about 11 and 80 yr, the frequency of volcanic eruptions increases (decreases) slightly around the times of solar minimum (maximum). Time series analysis of the volcanogenic acidities in a deep ice core from Greenland reveals several very long periods ranging from about 80 to about 350 yr which are similar to the very slow solar cycles previously detected in auroral and C-14 records. Solar flares may cause changes in atmospheric circulation patterns that abruptly alter the earth's spin. The resulting jolt probably triggers small earthquakes which affect volcanism.

  2. Geochemical study for volcanic surveillance

    Energy Technology Data Exchange (ETDEWEB)

    Panichi, C.; La Ruffa, G. [Consiglio Nazionale delle Ricerche, International Institute for Geothermal Research Ghezzano, PI (Italy)

    2000-07-01

    For years, geologists have been striving to reconstruct volcanic eruptions from the analysis of pyroclastic deposits and lava flows on the surface of the earth and in the oceans. This effort has produced valuable information on volcanic petrology and magma generation, separation, mixing, crystallisation, and interaction with water in phreatomagmatic and submarine eruptions. The volcanological process are tied to the dynamics of the earth's crust and lithosphere. The mantle, subducted oceanic crust, and continental crust contain different rock types and are sources of different magmas. Magmas consist primarily of completely or partially molten silicates containing volatile materials either dissolved in the melt or as bubbles of gas. The silicate and volatile portions affect the physical properties of magma and, therefore, the nature of a volcanic eruption.

  3. Models of volcanic eruption hazards

    Energy Technology Data Exchange (ETDEWEB)

    Wohletz, K.H.

    1992-01-01

    Volcanic eruptions pose an ever present but poorly constrained hazard to life and property for geothermal installations in volcanic areas. Because eruptions occur sporadically and may limit field access, quantitative and systematic field studies of eruptions are difficult to complete. Circumventing this difficulty, laboratory models and numerical simulations are pivotal in building our understanding of eruptions. For example, the results of fuel-coolant interaction experiments show that magma-water interaction controls many eruption styles. Applying these results, increasing numbers of field studies now document and interpret the role of external water eruptions. Similarly, numerical simulations solve the fundamental physics of high-speed fluid flow and give quantitative predictions that elucidate the complexities of pyroclastic flows and surges. A primary goal of these models is to guide geologists in searching for critical field relationships and making their interpretations. Coupled with field work, modeling is beginning to allow more quantitative and predictive volcanic hazard assessments.

  4. Using fuzzy logic to mitigate the effect of multiple-sclerosis tremors on a wheelchair joystick controller

    NARCIS (Netherlands)

    Corbett, Dan; Zwaag, van der Berend Jan; Antoniou, Grigoris; Slaney, John

    1998-01-01

    We have designed a fuzzy logic wheelchair controller to minimise the effect of Multiple Sclerosis hand tremors on a wheelchair joystick controller. The aim is to give people with Multiple Sclerosis better control of an electric wheelchair by removing tremors from the joystick signal. This has been a

  5. Familial cortical myoclonic tremor with epilepsy : A single syndromic classification for a group of pedigrees bearing common features

    NARCIS (Netherlands)

    van Rootselaar, AF; van Schaik, IN; van den Maagdenberg, AMJM; Koelman, JHTM; Callenbach, PMC; Tijssen, MAJ

    2005-01-01

    Fifty Japanese and European families with cortical myoclonic tremor and epilepsy have been reported under various names. Unfamiliarity with the syndrome often leads to an initial misdiagnosis of essential tremor or progressive myoclonus epilepsy. A detailed overview of the literature is lacking and

  6. Antagonism of quercetin against tremor induced by unilateral striatal lesion of 6-OHDA in rats.

    Science.gov (United States)

    Mu, Xin; Yuan, Xia; Du, Li-Da; He, Guo-Rong; Du, Guan-Hua

    2016-01-01

    Quercetin, a flavonoid present in many plants, is reported to be effective in models of neurodegenerative diseases. The aim of the present study was to evaluate the anti-tremor effects of quercetin in 6-hydroxydopamine (6-OHDA)-induced rat model of Parkinson's disease. In rats, quercetin had no effect on apomorphine-induced rotations, but it could significantly attenuate muscle tremor of 6-OHDA lesioned rats. Interestingly, quercetin could decrease the burst frequency in a dose- and time-dependent manner. These results suggest that quercetin may have a protective effect on models to mimic muscle tremors of Parkinson's disease. This effect of quercetin may be associated with serotonergic system, but further study is needed.

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

    Science.gov (United States)

    Rose, Martin H; Løkkegaard, Annemette; Sonne-Holm, Stig; Jensen, Bente R

    2013-04-01

    We investigated lower-extremity isometric tremor Approximate Entropy (irregularity), torque steadiness and rate of force development (RFD) and their associations to muscle activation strategy during isometric knee extensions in patients with Parkinson's disease (PD). Thirteen male patients with 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 coactivation. 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 both knee isometric tremor Approximate Entropy and torque steadiness clearly differentiate between patients with PD and healthy controls. Furthermore, severely compromised RFD was found in patients with PD and was associated with decreased agonist muscle activation.

  8. Joystick use for virtual power wheelchair driving in individuals with tremor: pilot study.

    Science.gov (United States)

    Dicianno, Brad E; Sibenaller, Sara; Kimmich, Claire; Cooper, Rory A; Pyo, Jay

    2009-01-01

    People with disabilities such as multiple sclerosis and Parkinson's disease have difficulty operating conventional movement-sensing joysticks (MSJs) because of varying levels of tremor. We developed an isometric joystick (IJ) that has performed as well as a conventional MSJ when used by persons with upper-limb impairments in real and virtual wheelchair driving tasks. The Weighted-Frequency Fourier Linear Combiner (WFLC) filter has been used to cancel tremor effectively in microsurgery. In this study, we compared an MSJ, IJ, and IJ with the WFLC filter in individuals performing a virtual driving task. Although the WFLC filter did not improve driving performance in this study, the IJ without a filter yielded better results than the conventional MSJ and thus may be a potential alternative to the MSJ in minimizing the effects of tremor.

  9. Recurrence models of volcanic events: Applications to volcanic risk assessment

    Energy Technology Data Exchange (ETDEWEB)

    Crowe, B.M. [Los Alamos National Lab., Las Vegas, NV (United States); Picard, R.; Valentine, G. [Los Alamos National Lab., NM (United States); Perry, F.V. [New Mexico Univ., Albuquerque, NM (United States)

    1992-03-01

    An assessment of the risk of future volcanism has been conducted for isolation of high-level radioactive waste at the potential Yucca Mountain site in southern Nevada. Risk used in this context refers to a combined assessment of the probability and consequences of future volcanic activity. Past studies established bounds on the probability of magmatic disruption of a repository. These bounds were revised as additional data were gathered from site characterization studies. The probability of direct intersection of a potential repository located in an eight km{sup 2} area of Yucca Mountain by ascending basalt magma was bounded by the range of 10{sup {minus}8} to 10{sup {minus}10} yr{sup {minus}1 2}. The consequences of magmatic disruption of a repository were estimated in previous studies to be limited. The exact releases from such an event are dependent on the strike of an intruding basalt dike relative to the repository geometry, the timing of the basaltic event relative to the age of the radioactive waste and the mechanisms of release and dispersal of the waste radionuclides in the accessible environment. The combined low probability of repository disruption and the limited releases associated with this event established the basis for the judgement that the risk of future volcanism was relatively low. It was reasoned that that risk of future volcanism was not likely to result in disqualification of the potential Yucca Mountain site.

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

    Science.gov (United States)

    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

  11. Infrasonic harmonic tremor and degassing bursts from Halema'uma'u Crater, Kilauea Volcano, Hawaii

    Science.gov (United States)

    Fee, David; Garcés, Milton; Patrick, Matt; Chouet, Bernard; Dawson, Phil; Swanson, Donald A.

    2010-01-01

    The formation, evolution, collapse, and subsequent resurrection of a vent within Halema'uma'u Crater, Kilauea Volcano, produced energetic and varied degassing signals recorded by a nearby infrasound array between 2008 and early 2009. After 25 years of quiescence, a vent-clearing explosive burst on 19 March 2008 produced a clear, complex acoustic signal. Near-continuous harmonic infrasonic tremor followed this burst until 4 December 2008, when a period of decreased degassing occurred. The tremor spectra suggest volume oscillation and reverberation of a shallow gas-filled cavity beneath the vent. The dominant tremor peak can be sustained through Helmholtz oscillations of the cavity, while the secondary tremor peak and overtones are interpreted assuming acoustic resonance. The dominant tremor frequency matches the oscillation frequency of the gas emanating from the vent observed by video. Tremor spectra and power are also correlated with cavity geometry and dynamics, with the cavity depth estimated at ~219 m and volume ~3 x 106 m3 in November 2008. Over 21 varied degassing bursts were observed with extended burst durations and frequency content consistent with a transient release of gas exciting the cavity into resonance. Correlation of infrasound with seismicity suggests an open system connecting the atmosphere to the seismic excitation process at depth. Numerous degassing bursts produced very long period (0.03-0.1 Hz) infrasound, the first recorded at Kilauea, indicative of long-duration atmospheric accelerat