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Sample records for assimilating seizure dynamics

  1. Assimilating seizure dynamics.

    Directory of Open Access Journals (Sweden)

    Ghanim Ullah

    2010-05-01

    Full Text Available Observability of a dynamical system requires an understanding of its state-the collective values of its variables. However, existing techniques are too limited to measure all but a small fraction of the physical variables and parameters of neuronal networks. We constructed models of the biophysical properties of neuronal membrane, synaptic, and microenvironment dynamics, and incorporated them into a model-based predictor-controller framework from modern control theory. We demonstrate that it is now possible to meaningfully estimate the dynamics of small neuronal networks using as few as a single measured variable. Specifically, we assimilate noisy membrane potential measurements from individual hippocampal neurons to reconstruct the dynamics of networks of these cells, their extracellular microenvironment, and the activities of different neuronal types during seizures. We use reconstruction to account for unmeasured parts of the neuronal system, relating micro-domain metabolic processes to cellular excitability, and validate the reconstruction of cellular dynamical interactions against actual measurements. Data assimilation, the fusing of measurement with computational models, has significant potential to improve the way we observe and understand brain dynamics.

  2. Assimilation Dynamic Network (ADN) Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Assimilation Dynamic Network (ADN) is a dynamic inter-processor communication network that spans heterogeneous processor architectures, unifying components,...

  3. Plasticity-modulated seizure dynamics for seizure termination in realistic neuronal models

    NARCIS (Netherlands)

    Koppert, M.M.J.; Kalitzin, S.; Lopes da Silva, F.H.; Viergever, M.A.

    2011-01-01

    In previous studies we showed that autonomous absence seizure generation and termination can be explained by realistic neuronal models eliciting bi-stable dynamics. In these models epileptic seizures are triggered either by external stimuli (reflex epilepsies) or by internal fluctuations. This scena

  4. Plasticity-modulated seizure dynamics for seizure termination in realistic neuronal models

    Science.gov (United States)

    Koppert, M. M. J.; Kalitzin, S.; Lopes da Silva, F. H.; Viergever, M. A.

    2011-08-01

    In previous studies we showed that autonomous absence seizure generation and termination can be explained by realistic neuronal models eliciting bi-stable dynamics. In these models epileptic seizures are triggered either by external stimuli (reflex epilepsies) or by internal fluctuations. This scenario predicts exponential distributions of the duration of the seizures and of the inter-ictal intervals. These predictions were validated in rat models of absence epilepsy, as well as in a few human cases. Nonetheless, deviations from the predictions with respect to seizure duration distributions remained unexplained. The objective of the present work is to implement a simple but realistic computational model of a neuronal network including synaptic plasticity and ionic current dynamics and to explore the dynamics of the model with special emphasis on the distributions of seizure and inter-ictal period durations. We use as a basis our lumped model of cortical neuronal circuits. Here we introduce 'activity dependent' parameters, namely post-synaptic voltage-dependent plasticity, as well as a voltage-dependent hyperpolarization-activated current driven by slow and fast activation conductances. We examine the distributions of the durations of the seizure-like model activity and the normal activity, described respectively by the limit cycle and the steady state in the dynamics. We use a parametric γ-distribution fit as a quantifier. Our results show that autonomous, activity-dependent membrane processes can account for experimentally obtained statistical distributions of seizure durations, which were not explainable using the previous model. The activity-dependent membrane processes that display the strongest effect in accounting for these distributions are the hyperpolarization-dependent cationic (Ih) current and the GABAa plastic dynamics. Plastic synapses (NMDA-type) in the interneuron population show only a minor effect. The inter-ictal statistics retain their

  5. Microscale spatiotemporal dynamics during neocortical propagation of human focal seizures.

    Science.gov (United States)

    Wagner, Fabien B; Eskandar, Emad N; Cosgrove, G Rees; Madsen, Joseph R; Blum, Andrew S; Potter, N Stevenson; Hochberg, Leigh R; Cash, Sydney S; Truccolo, Wilson

    2015-11-15

    Some of the most clinically consequential aspects of focal epilepsy, e.g. loss of consciousness, arise from the generalization or propagation of seizures through local and large-scale neocortical networks. Yet, the dynamics of such neocortical propagation remain poorly understood. Here, we studied the microdynamics of focal seizure propagation in neocortical patches (4×4 mm) recorded via high-density microelectrode arrays (MEAs) implanted in people with pharmacologically resistant epilepsy. Our main findings are threefold: (1) a newly developed stage segmentation method, applied to local field potentials (LFPs) and multiunit activity (MUA), revealed a succession of discrete seizure stages, each lasting several seconds. These different stages showed characteristic evolutions in overall activity and spatial patterns, which were relatively consistent across seizures within each of the 5 patients studied. Interestingly, segmented seizure stages based on LFPs or MUA showed a dissociation of their spatiotemporal dynamics, likely reflecting different contributions of non-local synaptic inputs and local network activity. (2) As previously reported, some of the seizures showed a peak in MUA that happened several seconds after local seizure onset and slowly propagated across the MEA. However, other seizures had a more complex structure characterized by, for example, several MUA peaks, more consistent with the succession of discrete stages than the slow propagation of a simple wavefront of increased MUA. In both cases, nevertheless, seizures characterized by spike-wave discharges (SWDs, ~2-3 Hz) eventually evolved into patterns of phase-locked MUA and LFPs. (3) Individual SWDs or gamma oscillation cycles (25-60 Hz), characteristic of two different types of recorded seizures, tended to propagate with varying degrees of directionality, directions of propagation and speeds, depending on the identified seizure stage. However, no clear relationship was observed between the MUA

  6. Dynamics of muscle activation during tonic-clonic seizures

    DEFF Research Database (Denmark)

    Conradsen, Isa; Moldovan, Mihai; Jennum, Poul

    2012-01-01

    The purpose of our study was to elucidate the dynamics of muscle activation during generalised tonic-clonic seizures (GTCS). We recorded surface electromyography (EMG) from the deltoid muscle during 26 GTCS from 13 patients and compared it with GTCS-like events acted by 10 control subjects. GTCS ...... is a valuable tool for monitoring the balance between pro-convulsive and anti-convulsive factors....

  7. A study of the dynamics of seizure propagation across micro domains in the vicinity of the seizure onset zone

    Science.gov (United States)

    Basu, Ishita; Kudela, Pawel; Korzeniewska, Anna; Franaszczuk, Piotr J.; Anderson, William S.

    2015-08-01

    Objective. The use of micro-electrode arrays to measure electrical activity from the surface of the brain is increasingly being investigated as a means to improve seizure onset zone (SOZ) localization. In this work, we used a multivariate autoregressive model to determine the evolution of seizure dynamics in the 70-110 Hz high frequency band across micro-domains sampled by such micro-electrode arrays. We showed that a directed transfer function (DTF) can be used to estimate the flow of seizure activity in a set of simulated micro-electrode data with known propagation pattern. Approach. We used seven complex partial seizures recorded from four patients undergoing intracranial monitoring for surgical evaluation to reconstruct the seizure propagation pattern over sliding windows using a DTF measure. Main results. We showed that a DTF can be used to estimate the flow of seizure activity in a set of simulated micro-electrode data with a known propagation pattern. In general, depending on the location of the micro-electrode grid with respect to the clinical SOZ and the time from seizure onset, ictal propagation changed in directional characteristics over a 2-10 s time scale, with gross directionality limited to spatial dimensions of approximately 9 m{{m}2}. It was also seen that the strongest seizure patterns in the high frequency band and their sources over such micro-domains are more stable over time and across seizures bordering the clinically determined SOZ than inside. Significance. This type of propagation analysis might in future provide an additional tool to epileptologists for characterizing epileptogenic tissue. This will potentially help narrowing down resection zones without compromising essential brain functions as well as provide important information about targeting anti-epileptic stimulation devices.

  8. Deterministic dynamics of neural activity during absence seizures in rats

    Science.gov (United States)

    Ouyang, Gaoxiang; Li, Xiaoli; Dang, Chuangyin; Richards, Douglas A.

    2009-04-01

    The study of brain electrical activities in terms of deterministic nonlinear dynamics has recently received much attention. Forbidden ordinal patterns (FOP) is a recently proposed method to investigate the determinism of a dynamical system through the analysis of intrinsic ordinal properties of a nonstationary time series. The advantages of this method in comparison to others include simplicity and low complexity in computation without further model assumptions. In this paper, the FOP of the EEG series of genetic absence epilepsy rats from Strasbourg was examined to demonstrate evidence of deterministic dynamics during epileptic states. Experiments showed that the number of FOP of the EEG series grew significantly from an interictal to an ictal state via a preictal state. These findings indicated that the deterministic dynamics of neural networks increased significantly in the transition from the interictal to the ictal states and also suggested that the FOP measures of the EEG series could be considered as a predictor of absence seizures.

  9. Assimilation of dynamic topography in a global model

    OpenAIRE

    2013-01-01

    Absolute dynamic topography, i.e. the difference between time dependent multi-mission altimetric sea surface height and one of the most recent GOCE and GRACE based geoids, is assimilated in a global ocean general circulation model. To this end we apply an ensemble based Kalman technique, the "Error Subspace Transform Kalman Filter" (ESTKF). Here we present an update of our work. First of all the geoid is improved over previous versions. The ocean model now includes better dynam...

  10. An Operational Technology for Assimilating Lagrangian Data Based on Dynamical Systems Techniques

    Science.gov (United States)

    2016-06-07

    An Operational Technology for Assimilating Lagrangian Data Based on Dynamical Systems Techniques Christopher K. R. T. Jones Department of... technology for assimilating Lagrangian data. This new Lagrangian data assimilation platform is expected to be particularly effective in ocean regions where...COVERED 00-00-2006 to 00-00-2006 4. TITLE AND SUBTITLE An Operational Technology for Assimilating Lagrangian Data Based on Dynamical Systems

  11. Variational Data Assimilation Technique in Mathematical Modeling of Ocean Dynamics

    Science.gov (United States)

    Agoshkov, V. I.; Zalesny, V. B.

    2012-03-01

    Problems of the variational data assimilation for the primitive equation ocean model constructed at the Institute of Numerical Mathematics, Russian Academy of Sciences are considered. The model has a flexible computational structure and consists of two parts: a forward prognostic model, and its adjoint analog. The numerical algorithm for the forward and adjoint models is constructed based on the method of multicomponent splitting. The method includes splitting with respect to physical processes and space coordinates. Numerical experiments are performed with the use of the Indian Ocean and the World Ocean as examples. These numerical examples support the theoretical conclusions and demonstrate the rationality of the approach using an ocean dynamics model with an observed data assimilation procedure.

  12. Dynamical characteristics of pre-epileptic seizures in rats with recurrence quantification analysis

    Science.gov (United States)

    Li, Xiaoli; Ouyang, Gaoxiang; Yao, Xin; Guan, Xinping

    2004-11-01

    Understanding the transition of brain activity towards an epileptic seizure, called pre-epileptic seizure, is a challenge in epilepsy. In this Letter, a recurrence quantification analysis (RQA) is proposed to describe dynamical characteristics of EEG (electroencephalograph) recordings on rat experiments, which is helpful to predict seizures. One of the advantages of this method does not require any assumptions to EEG data, such as linear, stationary, noiseless and so on. A series of experimental tests in this study show that the dynamical characteristics of EEG data with RQA can identify the differences among inter-ictal, pre-ictal and ictal phases; and support the hypothesis that complexity of brain electrical activity has a significant decrease prior to an epileptic seizure. This change could be useful in predicting epileptic seizures.

  13. Dynamical analogy between epileptic seizures and seismogenic electromagnetic emissions by means of nonextensive statistical mechanics

    CERN Document Server

    Eftaxias, Konstantinos; Potirakis, Stelios M; Balasis, George

    2012-01-01

    The field of study of complex systems considers that the dynamics of complex systems are founded on universal principles that may be used to describe a great variety of scientific and technological approaches of different types of natural, artificial, and social systems. Several authors have suggested that earthquake dynamics and neurodynamics can be analyzed within similar mathematical frameworks. Recently, authors have shown that a dynamical analogy supported by scale-free statistics exists between seizures and earthquakes, analysing populations of different seizures and earthquakes, respectively. The purpose of this paper is to suggest a shift in emphasis from the large to the small scale: our analyses focus on a single epileptic seizure generation and the activation of a single fault (earthquake) and not on the statistics of sequences of different seizures and earthquakes. We apply the concepts of the nonextensive statistical physics to support the suggestion that a dynamical analogy exists between the tw...

  14. Dynamical analogy between epileptic seizures and seismogenic electromagnetic emissions by means of nonextensive statistical mechanics

    Science.gov (United States)

    Eftaxias, Konstantinos; Minadakis, George; Potirakis, Stelios. M.; Balasis, Georgios

    2013-02-01

    The field of study of complex systems considers that the dynamics of complex systems are founded on universal principles that may be used to describe a great variety of scientific and technological approaches of different types of natural, artificial, and social systems. Several authors have suggested that earthquake dynamics and neurodynamics can be analyzed within similar mathematical frameworks. Recently, authors have shown that a dynamical analogy supported by scale-free statistics exists between seizures and earthquakes, analyzing populations of different seizures and earthquakes, respectively. The purpose of this paper is to suggest a shift in emphasis from the large to the small scale: our analyses focus on a single epileptic seizure generation and the activation of a single fault (earthquake) and not on the statistics of sequences of different seizures and earthquakes. We apply the concepts of the nonextensive statistical physics to support the suggestion that a dynamical analogy exists between the two different extreme events, seizures and earthquakes. We also investigate the existence of such an analogy by means of scale-free statistics (the Gutenberg-Richter distribution of event sizes and the distribution of the waiting time until the next event). The performed analysis confirms the existence of a dynamic analogy between earthquakes and seizures, which moreover follow the dynamics of magnetic storms and solar flares.

  15. Dynamic causal modelling of electrographic seizure activity using Bayesian belief updating.

    Science.gov (United States)

    Cooray, Gerald K; Sengupta, Biswa; Douglas, Pamela K; Friston, Karl

    2016-01-15

    Seizure activity in EEG recordings can persist for hours with seizure dynamics changing rapidly over time and space. To characterise the spatiotemporal evolution of seizure activity, large data sets often need to be analysed. Dynamic causal modelling (DCM) can be used to estimate the synaptic drivers of cortical dynamics during a seizure; however, the requisite (Bayesian) inversion procedure is computationally expensive. In this note, we describe a straightforward procedure, within the DCM framework, that provides efficient inversion of seizure activity measured with non-invasive and invasive physiological recordings; namely, EEG/ECoG. We describe the theoretical background behind a Bayesian belief updating scheme for DCM. The scheme is tested on simulated and empirical seizure activity (recorded both invasively and non-invasively) and compared with standard Bayesian inversion. We show that the Bayesian belief updating scheme provides similar estimates of time-varying synaptic parameters, compared to standard schemes, indicating no significant qualitative change in accuracy. The difference in variance explained was small (less than 5%). The updating method was substantially more efficient, taking approximately 5-10min compared to approximately 1-2h. Moreover, the setup of the model under the updating scheme allows for a clear specification of how neuronal variables fluctuate over separable timescales. This method now allows us to investigate the effect of fast (neuronal) activity on slow fluctuations in (synaptic) parameters, paving a way forward to understand how seizure activity is generated.

  16. Dynamic calibration of agent-based models using data assimilation.

    Science.gov (United States)

    Ward, Jonathan A; Evans, Andrew J; Malleson, Nicolas S

    2016-04-01

    A widespread approach to investigating the dynamical behaviour of complex social systems is via agent-based models (ABMs). In this paper, we describe how such models can be dynamically calibrated using the ensemble Kalman filter (EnKF), a standard method of data assimilation. Our goal is twofold. First, we want to present the EnKF in a simple setting for the benefit of ABM practitioners who are unfamiliar with it. Second, we want to illustrate to data assimilation experts the value of using such methods in the context of ABMs of complex social systems and the new challenges these types of model present. We work towards these goals within the context of a simple question of practical value: how many people are there in Leeds (or any other major city) right now? We build a hierarchy of exemplar models that we use to demonstrate how to apply the EnKF and calibrate these using open data of footfall counts in Leeds.

  17. Characterising seizures in anti-NMDA-receptor encephalitis with dynamic causal modelling.

    Science.gov (United States)

    Cooray, Gerald K; Sengupta, Biswa; Douglas, Pamela; Englund, Marita; Wickstrom, Ronny; Friston, Karl

    2015-09-01

    We characterised the pathophysiology of seizure onset in terms of slow fluctuations in synaptic efficacy using EEG in patients with anti-N-methyl-d-aspartate receptor (NMDA-R) encephalitis. EEG recordings were obtained from two female patients with anti-NMDA-R encephalitis with recurrent partial seizures (ages 19 and 31). Focal electrographic seizure activity was localised using an empirical Bayes beamformer. The spectral density of reconstructed source activity was then characterised with dynamic causal modelling (DCM). Eight models were compared for each patient, to evaluate the relative contribution of changes in intrinsic (excitatory and inhibitory) connectivity and endogenous afferent input. Bayesian model comparison established a role for changes in both excitatory and inhibitory connectivity during seizure activity (in addition to changes in the exogenous input). Seizures in both patients were associated with a sequence of changes in inhibitory and excitatory connectivity; a transient increase in inhibitory connectivity followed by a transient increase in excitatory connectivity and a final peak of excitatory-inhibitory balance at seizure offset. These systematic fluctuations in excitatory and inhibitory gain may be characteristic of (anti NMDA-R encephalitis) seizures. We present these results as a case study and replication to motivate analyses of larger patient cohorts, to see whether our findings generalise and further characterise the mechanisms of seizure activity in anti-NMDA-R encephalitis.

  18. Data assimilation as a nonlinear dynamical systems problem: stability and convergence of the prediction-assimilation system.

    Science.gov (United States)

    Carrassi, Alberto; Ghil, Michael; Trevisan, Anna; Uboldi, Francesco

    2008-06-01

    We study prediction-assimilation systems, which have become routine in meteorology and oceanography and are rapidly spreading to other areas of the geosciences and of continuum physics. The long-term, nonlinear stability of such a system leads to the uniqueness of its sequentially estimated solutions and is required for the convergence of these solutions to the system's true, chaotic evolution. The key ideas of our approach are illustrated for a linearized Lorenz system. Stability of two nonlinear prediction-assimilation systems from dynamic meteorology is studied next via the complete spectrum of their Lyapunov exponents; these two systems are governed by a large set of ordinary and of partial differential equations, respectively. The degree of data-induced stabilization is crucial for the performance of such a system. This degree, in turn, depends on two key ingredients: (i) the observational network, either fixed or data-adaptive, and (ii) the assimilation method.

  19. Assimilation of Multi-Sensor Synoptic and Mesoscale Datasets: An Approach Based on Statistic, Dynamic, Physical and Synoptic Considerations

    Science.gov (United States)

    2016-06-13

    Assimilation of Multi- Sensor Synoptic and Mesoscale Datasets: An Approach Based on Statistic, Dynamic, Physical and Synoptic Considerations Xiaolei...Assimilation of Multi- Sensor Synoptic and Mesoscale Datasets: An Approach Based on Statistic, Dynamic, Physical and Synoptic Considerations 5a

  20. Application of approximate entropy on dynamic characteristics of epileptic absence seizure

    Institute of Scientific and Technical Information of China (English)

    Yi Zhou; Ruimei Huang; Ziyi Chen; Xin Chang; Jialong Chen; Lingli Xie

    2012-01-01

    Electroencephalogram signals are time-varying complex electrophysiological signals. Existing studies show that approximate entropy, which is a nonlinear dynamics index, is not an ideal method for electroencephalogram analysis. Clinical electroencephalogram measurements usually contain electrical interference signals, creating additional challenges in terms of maintaining robustness of the analytic methods. There is an urgent need for a novel method of nonlinear dynamical analysis of the electroencephalogram that can characterize seizure-related changes in cerebral dynamics. The aim of this paper was to study the fluctuations of approximate entropy in preictal, ictal, and postictal electroencephalogram signals from a patient with absence seizures, and to improve the algorithm used to calculate the approximate entropy. The approximate entropy algorithm, especially our modified version, could accurately describe the dynamical changes of the brain during absence seizures. We could also demonstrate that the complexity of the brain was greater in the normal state than in the ictal state. The fluctuations of the approximate entropy before epileptic seizures observed in this study can form a goodbasis for further study on the prediction of seizures with nonlinear dynamics.

  1. Sequential assimilation of multi-mission dynamical topography into a global finite-element ocean model

    Directory of Open Access Journals (Sweden)

    S. Skachko

    2008-12-01

    Full Text Available This study focuses on an accurate estimation of ocean circulation via assimilation of satellite measurements of ocean dynamical topography into the global finite-element ocean model (FEOM. The dynamical topography data are derived from a complex analysis of multi-mission altimetry data combined with a referenced earth geoid. The assimilation is split into two parts. First, the mean dynamic topography is adjusted. To this end an adiabatic pressure correction method is used which reduces model divergence from the real evolution. Second, a sequential assimilation technique is applied to improve the representation of thermodynamical processes by assimilating the time varying dynamic topography. A method is used according to which the temperature and salinity are updated following the vertical structure of the first baroclinic mode. It is shown that the method leads to a partially successful assimilation approach reducing the rms difference between the model and data from 16 cm to 2 cm. This improvement of the mean state is accompanied by significant improvement of temporal variability in our analysis. However, it remains suboptimal, showing a tendency in the forecast phase of returning toward a free run without data assimilation. Both the mean difference and standard deviation of the difference between the forecast and observation data are reduced as the result of assimilation.

  2. Real-time Detection of Precursors to Epileptic Seizures: Non-Linear Analysis of System Dynamics.

    Science.gov (United States)

    Nesaei, Sahar; Sharafat, Ahmad R

    2014-04-01

    We propose a novel approach for detecting precursors to epileptic seizures in intracranial electroencephalograms (iEEG), which is based on the analysis of system dynamics. In the proposed scheme, the largest Lyapunov exponent of the discrete wavelet packet transform (DWPT) of the segmented EEG signals is considered as the discriminating features. Such features are processed by a support vector machine (SVM) classifier to identify whether the corresponding segment of the EEG signal contains a precursor to an epileptic seizure. When consecutive EEG segments contain such precursors, a decision is made that a precursor is in fact detected. The proposed scheme is applied to the Freiburg dataset, and the results show that seizure precursors are detected in a time frame that unlike other existing schemes is very much convenient to patients, with sensitivity of 100% and negligible false positive detection rates.

  3. An evaluation of spindle-shaft seizure accident sequences for the Schenck Dynamic Balancer

    Energy Technology Data Exchange (ETDEWEB)

    Bott, T.F.; Fischer, S.R.

    1998-11-01

    This study was conducted at the request of the USDOE/AL Dynamic Balancer Project Team to develop a set of representative accident sequences initiated by rapid seizure of the spindle shaft of the Schenck dynamic balancing machine used in the mass properties testing activities in Bay 12-60 at the Pantex Plant. This Balancer is used for balancing reentry vehicles. In addition, the study identified potential causes of possible spindle-shaft seizure leading to a rapid deceleration of the rotating assembly. These accident sequences extend to the point that the reentry vehicle either remains in stable condition on the balancing machine or leaves the machine with some translational and rotational motion. Fault-tree analysis was used to identify possible causes of spindle-shaft seizure, and failure modes and effects analysis identified the results of shearing of different machine components. Cause-consequence diagrams were used to help develop accident sequences resulting from the possible effects of spindle-shaft seizure. To make these accident sequences physically reasonable, the analysts used idealized models of the dynamics of rotating masses. Idealized physical modeling also was used to provide approximate values of accident parameters that lead to branching down different accident progression paths. The exacerbating conditions of balancing machine over-speed and improper assembly of the fixture to the face plate are also addressed.

  4. Dynamics of vowel-to-vowel assimilation in French.

    OpenAIRE

    2013-01-01

    International audience; Vowel-to-vowel assimilation in French is described as an anticipatory process affecting non-final mid vowels (V1) : [e], [E], [ø], [œ], [o], [O] that assimilate in height to the final tonic vowel (V2). The non-final mid vowel tend to be mid-high before a high or mid-high vowel (e. g. aimer [eme] 'to love'), and mid-low before a low or mid-low vowel (aimable [Emabl] 'kind')[1, 4, 6]. The present study investigates the nature of vowel harmony (VH) in French. Does vowel a...

  5. Internetwork and intranetwork communications during bursting dynamics: Applications to seizure prediction

    Science.gov (United States)

    Feldt, S.; Osterhage, H.; Mormann, F.; Lehnertz, K.; Żochowski, M.

    2007-08-01

    We use a simple dynamical model of two interacting networks of integrate-and-fire neurons to explain a seemingly paradoxical result observed in epileptic patients indicating that the level of phase synchrony declines below normal levels during the state preceding seizures (preictal state). We model the transition from the seizure free interval (interictal state) to the seizure (ictal state) as a slow increase in the mean depolarization of neurons in a network corresponding to the epileptic focus. We show that the transition from the interictal to preictal and then to the ictal state may be divided into separate dynamical regimes: the formation of slow oscillatory activity due to resonance between the two interacting networks observed during the interictal period, structureless activity during the preictal period when the two networks have different properties, and bursting dynamics driven by the network corresponding to the epileptic focus. Based on this result, we hypothesize that the beginning of the preictal period marks the beginning of the transition of the epileptic network from normal activity toward seizing.

  6. Improved epileptic seizure detection combining dynamic feature normalization with EEG novelty detection.

    Science.gov (United States)

    Bogaarts, J G; Hilkman, D M W; Gommer, E D; van Kranen-Mastenbroek, V H J M; Reulen, J P H

    2016-12-01

    Continuous electroencephalographic monitoring of critically ill patients is an established procedure in intensive care units. Seizure detection algorithms, such as support vector machines (SVM), play a prominent role in this procedure. To correct for inter-human differences in EEG characteristics, as well as for intra-human EEG variability over time, dynamic EEG feature normalization is essential. Recently, the median decaying memory (MDM) approach was determined to be the best method of normalization. MDM uses a sliding baseline buffer of EEG epochs to calculate feature normalization constants. However, while this method does include non-seizure EEG epochs, it also includes EEG activity that can have a detrimental effect on the normalization and subsequent seizure detection performance. In this study, EEG data that is to be incorporated into the baseline buffer are automatically selected based on a novelty detection algorithm (Novelty-MDM). Performance of an SVM-based seizure detection framework is evaluated in 17 long-term ICU registrations using the area under the sensitivity-specificity ROC curve. This evaluation compares three different EEG normalization methods, namely a fixed baseline buffer (FB), the median decaying memory (MDM) approach, and our novelty median decaying memory (Novelty-MDM) method. It is demonstrated that MDM did not improve overall performance compared to FB (p < 0.27), partly because seizure like episodes were included in the baseline. More importantly, Novelty-MDM significantly outperforms both FB (p = 0.015) and MDM (p = 0.0065).

  7. Scientific Studies of the High-Latitude Ionosphere with the Ionosphere Dynamics and ElectroDynamics - Data Assimilation (IDED-DA) Model

    Science.gov (United States)

    2014-09-23

    titlelScientific Studies of the High-Latitude Ionosphere with the Ionosphere Dynamics and Electrodynamics-Data Assimilation (IDED-DA) Model...awardnumberl]N00014-13-l-0267 [awardnumber2] [awardnumbermore] [keywords]Ionosphere, Assimilation , Simulations [specialcat] [pillRobert W...totalminoritypostdocs] [bestaccomplishment] With only ground magnetometer measurements, our high-latitude data assimilation model can track the

  8. Dynamic imaging of coherent sources reveals different network connectivity underlying the generation and perpetuation of epileptic seizures.

    Directory of Open Access Journals (Sweden)

    Lydia Elshoff

    Full Text Available The concept of focal epilepsies includes a seizure origin in brain regions with hyper synchronous activity (epileptogenic zone and seizure onset zone and a complex epileptic network of different brain areas involved in the generation, propagation, and modulation of seizures. The purpose of this work was to study functional and effective connectivity between regions involved in networks of epileptic seizures. The beginning and middle part of focal seizures from ictal surface EEG data were analyzed using dynamic imaging of coherent sources (DICS, an inverse solution in the frequency domain which describes neuronal networks and coherences of oscillatory brain activities. The information flow (effective connectivity between coherent sources was investigated using the renormalized partial directed coherence (RPDC method. In 8/11 patients, the first and second source of epileptic activity as found by DICS were concordant with the operative resection site; these patients became seizure free after epilepsy surgery. In the remaining 3 patients, the results of DICS / RPDC calculations and the resection site were discordant; these patients had a poorer post-operative outcome. The first sources as found by DICS were located predominantly in cortical structures; subsequent sources included some subcortical structures: thalamus, Nucl. Subthalamicus and cerebellum. DICS seems to be a powerful tool to define the seizure onset zone and the epileptic networks involved. Seizure generation seems to be related to the propagation of epileptic activity from the primary source in the seizure onset zone, and maintenance of seizures is attributed to the perpetuation of epileptic activity between nodes in the epileptic network. Despite of these promising results, this proof of principle study needs further confirmation prior to the use of the described methods in the clinical praxis.

  9. Dynamic Responses of the Earth's Outer Core to Assimilation of Observed Geomagnetic Secular Variation

    Science.gov (United States)

    Kuang, Weijia; Tangborn, Andrew

    2014-01-01

    Assimilation of surface geomagnetic observations and geodynamo models has advanced very quickly in recent years. However, compared to advanced data assimilation systems in meteorology, geomagnetic data assimilation (GDAS) is still in an early stage. Among many challenges ranging from data to models is the disparity between the short observation records and the long time scales of the core dynamics. To better utilize available observational information, we have made an effort in this study to directly assimilate the Gauss coefficients of both the core field and its secular variation (SV) obtained via global geomagnetic field modeling, aiming at understanding the dynamical responses of the core fluid to these additional observational constraints. Our studies show that the SV assimilation helps significantly to shorten the dynamo model spin-up process. The flow beneath the core-mantle boundary (CMB) responds significantly to the observed field and its SV. The strongest responses occur in the relatively small scale flow (of the degrees L is approx. 30 in spherical harmonic expansions). This part of the flow includes the axisymmetric toroidal flow (of order m = 0) and non-axisymmetric poloidal flow with m (is) greater than 5. These responses can be used to better understand the core flow and, in particular, to improve accuracies of predicting geomagnetic variability in future.

  10. A data assimilation tool for the Pagasitikos Gulf ecosystem dynamics: Methods and benefits

    KAUST Repository

    Korres, Gerasimos

    2012-06-01

    Within the framework of the European INSEA project, an advanced assimilation system has been implemented for the Pagasitikos Gulf ecosystem. The system is based on a multivariate sequential data assimilation scheme that combines satellite ocean sea color (chlorophyll-a) data with the predictions of a three-dimensional coupled physical-biochemical model of the Pagasitikos Gulf ecosystem presented in a companion paper. The hydrodynamics are solved with a very high resolution (1/100°) implementation of the Princeton Ocean Model (POM). This model is nested within a coarser resolution model of the Aegean Sea which is part of the Greek POSEIDON forecasting system. The forecast of the Aegean Sea model, itself nested and initialized from a Mediterranean implementation of POM, is also used to periodically re-initalize the Pagatisikos hydrodynamics model using variational initialization techniques. The ecosystem dynamics of Pagasitikos are tackled with a stand-alone implementation of the European Seas Ecosystem Model (ERSEM). The assimilation scheme is based on the Singular Evolutive Extended Kalman (SEEK) filter, in which the error statistics are parameterized by means of a suitable set of Empirical Orthogonal Functions (EOFs).The assimilation experiments were performed for year 2003 and additionally for a 9-month period over 2006 during which the physical model was forced with the POSEIDON-ETA 6-hour atmospheric fields. The assimilation system is validated by assessing the relevance of the system in fitting the data, the impact of the assimilation on non-observed biochemical processes and the overall quality of the forecasts. Assimilation of either GlobColour in 2003 or SeaWiFS in 2006 chlorophyll-a data enhances the identification of the ecological state of the Pagasitikos Gulf. Results, however, suggest that subsurface ecological observations are needed to improve the controllability of the ecosystem in the deep layers. © 2011 Elsevier B.V.

  11. Neural networks for emulation variational method for data assimilation in nonlinear dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Morais Furtado, Helaine Cristina; Fraga de Campos Velho, Haroldo; Macau, Elbert E N, E-mail: helaine.furtado@lac.inpe.br, E-mail: haroldo@lac.inpe.br, E-mail: elbert@lac.inpe.br [Laboratorio Associado de Computacao e Matematica Aplicada, Sao Jose dos Campos (Brazil)

    2011-03-01

    Description of a physical phenomenon through differential equations has errors involved, since the mathematical model is always an approximation of reality. For an operational prediction system, one strategy to improve the prediction is to add some information from the real dynamics into mathematical model. This additional information consists of observations on the phenomenon. However, the observational data insertion should be done carefully, for avoiding a worse performance of the prediction. Technical data assimilation are tools to combine data from physical-mathematics model with observational data to obtain a better forecast. The goal of this work is to present the performance of the Neural Network Multilayer Perceptrons trained to emulate a Variational method in context of data assimilation. Techniques for data assimilation are applied for the Lorenz systems; which presents a strong nonlinearity and chaotic nature.

  12. Variational Assimilation for Xenon Dynamical Forecasts in Neutronic using Advanced Background Error Covariance Matrix

    CERN Document Server

    Ponçot, Angélique; Bouriquet, Bertrand; Erhard, Patrick; Gratton, Serge; Thual, Olivier

    2013-01-01

    Data assimilation method consists in combining all available pieces of information about a system to obtain optimal estimates of initial states. The different sources of information are weighted according to their accuracy by the means of error covariance matrices. Our purpose here is to evaluate the efficiency of variational data assimilation for the xenon induced oscillations forecasts in nuclear cores. In this paper we focus on the comparison between 3DVAR schemes with optimised background error covariance matrix B and a 4DVAR scheme. Tests were made in twin experiments using a simulation code which implements a mono-dimensional coupled model of xenon dynamics, thermal, and thermal-hydraulic processes. We enlighten the very good efficiency of the 4DVAR scheme as well as good results with the 3DVAR one using a careful multivariate modelling of B.

  13. An effective method based on dynamic sampling for data assimilation in a global wave model

    Science.gov (United States)

    Sun, Meng; Yin, Xunqiang; Yang, Yongzeng; Wu, Kejian

    2017-01-01

    The ensemble Kalman filter (EnKF) performs well because that the covariance of background error is varying along time. It provides a dynamic estimate of background error and represents the reasonable statistic characters of background error. However, high computational cost due to model ensemble in EnKF is employed. In this study, two methods referred as static and dynamic sampling methods are proposed to obtain a good performance and reduce the computation cost. Ensemble adjustment Kalman filter (EAKF) method is used in a global surface wave model to examine the performance of EnKF. The 24-h interval difference of simulated significant wave height (SWH) within 1 year is used to compose the static samples for ensemble errors, and these errors are used to construct the ensemble states at each time the observations are available. And then, the same method of updating the model states in the EAKF is applied for the ensemble states constructed by a static sampling method. The dynamic sampling method employs a similar method to construct the ensemble states, but the period of the simulated SWH is changing with time. Here, 7 days before and after the observation time is used as this period. To examine the performance of three schemes, EAKF, static, or dynamic sampling method, observations from satellite Jason-2 in 2014 are assimilated into a global wave model, and observations from satellite Saral are used for validation. The results indicate that the EAKF performs best, while the static sampling method is relatively worse. The dynamic sampling method improves an assimilation effect dramatically compared to the static sampling method, and its overall performance is closed to the EAKF. In low latitudes, the dynamic sampling method has a slight advantage over the EAKF. In the dynamic or static sampling methods, only one wave model is required to run and their computational cost is reduced sharply. According to the performance of these three methods, the dynamic sampling

  14. Predicting Flow Reversals in a Computational Fluid Dynamics Simulated Thermosyphon Using Data Assimilation.

    Science.gov (United States)

    Reagan, Andrew J; Dubief, Yves; Dodds, Peter Sheridan; Danforth, Christopher M

    2016-01-01

    A thermal convection loop is a annular chamber filled with water, heated on the bottom half and cooled on the top half. With sufficiently large forcing of heat, the direction of fluid flow in the loop oscillates chaotically, dynamics analogous to the Earth's weather. As is the case for state-of-the-art weather models, we only observe the statistics over a small region of state space, making prediction difficult. To overcome this challenge, data assimilation (DA) methods, and specifically ensemble methods, use the computational model itself to estimate the uncertainty of the model to optimally combine these observations into an initial condition for predicting the future state. Here, we build and verify four distinct DA methods, and then, we perform a twin model experiment with the computational fluid dynamics simulation of the loop using the Ensemble Transform Kalman Filter (ETKF) to assimilate observations and predict flow reversals. We show that using adaptively shaped localized covariance outperforms static localized covariance with the ETKF, and allows for the use of less observations in predicting flow reversals. We also show that a Dynamic Mode Decomposition (DMD) of the temperature and velocity fields recovers the low dimensional system underlying reversals, finding specific modes which together are predictive of reversal direction.

  15. Predicting Flow Reversals in a Computational Fluid Dynamics Simulated Thermosyphon Using Data Assimilation.

    Directory of Open Access Journals (Sweden)

    Andrew J Reagan

    Full Text Available A thermal convection loop is a annular chamber filled with water, heated on the bottom half and cooled on the top half. With sufficiently large forcing of heat, the direction of fluid flow in the loop oscillates chaotically, dynamics analogous to the Earth's weather. As is the case for state-of-the-art weather models, we only observe the statistics over a small region of state space, making prediction difficult. To overcome this challenge, data assimilation (DA methods, and specifically ensemble methods, use the computational model itself to estimate the uncertainty of the model to optimally combine these observations into an initial condition for predicting the future state. Here, we build and verify four distinct DA methods, and then, we perform a twin model experiment with the computational fluid dynamics simulation of the loop using the Ensemble Transform Kalman Filter (ETKF to assimilate observations and predict flow reversals. We show that using adaptively shaped localized covariance outperforms static localized covariance with the ETKF, and allows for the use of less observations in predicting flow reversals. We also show that a Dynamic Mode Decomposition (DMD of the temperature and velocity fields recovers the low dimensional system underlying reversals, finding specific modes which together are predictive of reversal direction.

  16. Assimilative model for ionospheric dynamics employing delay, Doppler, and direction of arrival measurements from multiple HF channels

    Science.gov (United States)

    Fridman, Sergey V.; Nickisch, L. J.; Hausman, Mark; Zunich, George

    2016-03-01

    We describe the development of new HF data assimilation capabilities for our ionospheric inversion algorithm called GPSII (GPS Ionospheric Inversion). Previously existing capabilities of this algorithm included assimilation of GPS total electron content data as well as assimilation of backscatter ionograms. In the present effort we concentrated on developing assimilation tools for data related to HF propagation channels. Measurements of propagation delay, angle of arrival, and the ionosphere-induced Doppler from any number of known propagation links can now be utilized by GPSII. The resulting ionospheric model is consistent with all assimilated measurements. This means that ray tracing simulations of the assimilated propagation links are guaranteed to be in agreement with measured data within the errors of measurement. The key theoretical element for assimilating HF data is the raypath response operator (RPRO) which describes response of raypath parameters to infinitesimal variations of electron density in the ionosphere. We construct the RPRO out of the fundamental solution of linearized ray tracing equations for a dynamic magnetoactive plasma. We demonstrate performance and internal consistency of the algorithm using propagation delay data from multiple oblique ionograms (courtesy of Defence Science and Technology Organisation, Australia) as well as with time series of near-vertical incidence sky wave data (courtesy of the Intelligence Advanced Research Projects Activity HFGeo Program Government team). In all cases GPSII produces electron density distributions which are smooth in space and in time. We simulate the assimilated propagation links by performing ray tracing through GPSII-produced ionosphere and observe that simulated data are indeed in agreement with assimilated measurements.

  17. Altered fMRI connectivity dynamics in temporal lobe epilepsy might explain seizure semiology

    Directory of Open Access Journals (Sweden)

    Helmut eLaufs

    2014-09-01

    Full Text Available Abstract: Temporal lobe epilepsy (TLE can be conceptualized as a network disease. The network can be characterized by inter-regional functional connectivity, i.e. blood oxygen level-dependent (BOLD signal correlations between any two region pairs. However, functional connectivity is not constant over time, thus computing correlation at a given time and then at some later time could give different results (non-stationarity. We hypothesized (1 that non-stationarities can be induced by epilepsy (e.g. interictal epileptic activity increasing local signal variance and that (2 these transient events contribute to fluctuations in connectivity leading to pathological functioning, i.e. TLE semiology. We analyzed fMRI data from 27 patients with TLE and 22 healthy controls focusing on EEG-confirmed wake epochs only to protect against sleep-induced connectivity changes. Testing hypothesis (1, we identified brain regions where the BOLD signal variance was significantly greater in TLE than in controls: the temporal pole - including the hippocampus. Taking the latter as the seed region and testing hypothesis (2 we calculated the time-varying interregional correlation values (dynamic functional connectivity to other brain regions and found greater connectivity variance in the TLE than the control group mainly in the precuneus, the supplementary and sensori-motor and the frontal cortices.We conclude that the highest BOLD signal variance in the hippocampi is highly suggestive of a specific epilepsy-related effect. The altered connectivity dynamics in TLE patients might help to explain the hallmark semiological features of dyscognitive seizures including impaired consciousness (precuneus, frontal cortex, sensory disturbance and motor automatisms (sensorimotor cortices, supplementary motor cortex. Accounting for the non-stationarity and state-dependence of functional connectivity are a prerequisite in the search for potential connectivity-derived biomarkers in TLE.

  18. Modeling absence seizure dynamics: implications for basic mechanisms and measurement of thalamocortical and corticothalamic latencies.

    Science.gov (United States)

    Roberts, James A; Robinson, Peter A

    2008-07-01

    A successful physiologically based continuum model of the corticothalamic system is applied to determine the relative contributions of axonal and intrinsic cellular delays to the waveforms of absence seizures. The predicted period of the absence seizure depends linearly on model parameters describing thalamocortical, corticothalamic, intracortical, and synaptodendritic delays, and these dependences are linked to the seizure mechanism by showing how time intervals between peaks in the waveforms depend on the parameters. Counterintuitively, it is found that a peak in the local field potential recorded in the thalamic relay nuclei can precede the peak in the cortical field that drove it, without violating causality, but rendering naive interpretation of time intervals between peaks invalid. We argue that a thalamocortical loop mechanism for absence seizures is consistent with intrathalamic cellular properties being the leading determinant of the frequency of spike-wave discharges in rat genetic models, with the combination of network and cellular properties providing a natural explanation for the lower frequency of human absence seizures. Finally, our results imply that the seizure frequency is not determined by the fastest thalamocortical and corticothalamic fibers, but rather depends on an effective weighted conduction velocity of all pathways present.

  19. [Ecstatic seizures].

    Science.gov (United States)

    Likhachev, S A; Astapenko, A V; Osos, E L; Zmachynskaya, O L; Gvishch, T G

    2015-01-01

    Ecstatic seizures is a rare manifestation of epilepsy. They were described for the first time by F.M. Dostoevsky. Currently, the description of ecstatic seizures is possible to find in the scientific literature. The description of the own observation of a patient with emotional-affective seizures is presented. A role of the anterior insular cortex in the ecstatic seizures origin is discussed. The similarities between the feelings reported during ecstatic seizures and the feelings experienced under the effect of stimulant addictive drugs are described. The possible reasons of the low frequency of emotional-affective seizures are considered.

  20. Dynamical and Microphysical Retrieval from Simulated Doppler Radar Observations Using the 4DVAR Assimilation Technique

    Institute of Scientific and Technical Information of China (English)

    XU Xiaoyong; LIU Liping; ZHENG Guoguang

    2005-01-01

    Based on a cloud model and the four-dimensional variational (4DVAR) data assimilation method developed by Sun and Crook (1997), simulated experiments of dynamical and microphysical retrieval from Doppler radar data were performed. The 4DVAR data assimilation technique was applied to a cloud scale model with a warm rain parameterization scheme. The 3D wind, thermodynamical, and microphysical fields were determined by minimizing a cost function, defined by the difference between both radar observed radial velocities and reflectivities and their model predictions. The adjoint of the numerical model was used to provide the gradient of the cost function with respect to the control variables. Experiments have demonstrated that the 4DVAR assimilation method is able to retrieve the detailed structure of wind, thermodynamics, and microphysics by using either dual-Doppler or single-Doppler information. The quality of retrieval depends strongly on the magnitude of constraint with respect to the variables. Retrieving the temperature field,cloud water and water vapor is more difficult than the recovery of the wind field and rainwater. Accurate thermodynamic retrieval requires a longer assimilation period. The inclusion of a background term, even mean fields from a single sounding, helped reduce the retrieval errors. Less accurate velocity fields were obtained when single-Doppler data were used. It was found that the retrieved velocity is sensitive to the location of the retrieval domain relative to the radars while the other fields have very little changes. Two radar volumetric scans are generally adequate for providing the evolution, although the use of additional volumes improves the retrieval. As the amount of the observations decreases, the performance of the retrieval is degraded. However, the missing observations can be compensated by adding a background term to the cost function. The technique is robust to random errors in radial velocity and calibration errors in

  1. Transfer of Real-time Dynamic Radiation Environment Assimilation Model; Research to Operation

    Science.gov (United States)

    Cho, K. S. F.; Hwang, J.; Shin, D. K.; Kim, G. J.; Morley, S.; Henderson, M. G.; Friedel, R. H.; Reeves, G. D.

    2015-12-01

    Real-time Dynamic Radiation Environment Assimilation Model (rtDREAM) was developed by LANL for nowcast of energetic electrons' flux at the radiation belt to quantify potential risks from radiation damage at the satellites. Assimilated data are from multiple sources including LANL assets (GEO, GPS). For transfer from research to operation of the rtDREAM code, LANL/KSWC/NOAA makes a Memorandum Of Understanding (MOU) on the collaboration between three parts. By this MOU, KWSC/RRA provides all the support for transitioning the research version of DREAM to operations. KASI is primarily responsible for providing all the interfaces between the current scientific output formats of the code and useful space weather products that can be used and accessed through the web. In the second phase, KASI will be responsible in performing the work needed to transform the Van Allen Probes beacon data into "DREAM ready" inputs. KASI will also provide the "operational" code framework and additional data preparation, model output, display and web page codes back to LANL and SWPC. KASI is already a NASA partnering ground station for the Van Allen Probes' space weather beacon data and can here show use and utility of these data for comparison between rtDREAM and observations by web. NOAA has offered to take on some of the data processing tasks specific to the GOES data.

  2. Local changes in neocortical circuit dynamics coincide with the spread of seizures to thalamus in a model of epilepsy.

    Science.gov (United States)

    Neubauer, Florian B; Sederberg, Audrey; MacLean, Jason N

    2014-01-01

    During the generalization of epileptic seizures, pathological activity in one brain area recruits distant brain structures into joint synchronous discharges. However, it remains unknown whether specific changes in local circuit activity are related to the aberrant recruitment of anatomically distant structures into epileptiform discharges. Further, it is not known whether aberrant areas recruit or entrain healthy ones into pathological activity. Here we study the dynamics of local circuit activity during the spread of epileptiform discharges in the zero-magnesium in vitro model of epilepsy. We employ high-speed multi-photon imaging in combination with dual whole-cell recordings in acute thalamocortical (TC) slices of the juvenile mouse to characterize the generalization of epileptic activity between neocortex and thalamus. We find that, although both structures are exposed to zero-magnesium, the initial onset of focal epileptiform discharge occurs in cortex. This suggests that local recurrent connectivity that is particularly prevalent in cortex is important for the initiation of seizure activity. Subsequent recruitment of thalamus into joint, generalized discharges is coincident with an increase in the coherence of local cortical circuit activity that itself does not depend on thalamus. Finally, the intensity of population discharges is positively correlated between both brain areas. This suggests that during and after seizure generalization not only the timing but also the amplitude of epileptiform discharges in thalamus is entrained by cortex. Together these results suggest a central role of neocortical activity for the onset and the structure of pathological recruitment of thalamus into joint synchronous epileptiform discharges.

  3. Obtaining a Pragmatic Representation of Fire Disturbance in Dynamic Vegetation Models by Assimilating Earth Observation Data

    Science.gov (United States)

    Kantzas, Euripides; Quegan, Shaun

    2015-04-01

    Fire constitutes a violent and unpredictable pathway of carbon from the terrestrial biosphere into the atmosphere. Despite fire emissions being in many biomes of similar magnitude to that of Net Ecosystem Exchange, even the most complex Dynamic Vegetation Models (DVMs) embedded in IPCC General Circulation Models poorly represent fire behavior and dynamics, a fact which still remains understated. As DVMs operate on a deterministic, grid cell-by-grid cell basis they are unable to describe a host of important fire characteristics such as its propagation, magnitude of area burned and stochastic nature. Here we address these issues by describing a model-independent methodology which assimilates Earth Observation (EO) data by employing image analysis techniques and algorithms to offer a realistic fire disturbance regime in a DVM. This novel approach, with minimum model restructuring, manages to retain the Fire Return Interval produced by the model whilst assigning pragmatic characteristics to its fire outputs thus allowing realistic simulations of fire-related processes such as carbon injection into the atmosphere and permafrost degradation. We focus our simulations in the Arctic and specifically Canada and Russia and we offer a snippet of how this approach permits models to engage in post-fire dynamics hitherto absent from any other model regardless of complexity.

  4. A Dynamic Approach to Addressing Observation-Minus-Forecast Mean Differences in a Land Surface Skin Temperature Data Assimilation System

    Science.gov (United States)

    Draper, Clara; Reichle, Rolf; De Lannoy, Gabrielle; Scarino, Benjamin

    2015-01-01

    In land data assimilation, bias in the observation-minus-forecast (O-F) residuals is typically removed from the observations prior to assimilation by rescaling the observations to have the same long-term mean (and higher-order moments) as the corresponding model forecasts. Such observation rescaling approaches require a long record of observed and forecast estimates, and an assumption that the O-F mean differences are stationary. A two-stage observation bias and state estimation filter is presented, as an alternative to observation rescaling that does not require a long data record or assume stationary O-F mean differences. The two-stage filter removes dynamic (nonstationary) estimates of the seasonal scale O-F mean difference from the assimilated observations, allowing the assimilation to correct the model for synoptic-scale errors without adverse effects from observation biases. The two-stage filter is demonstrated by assimilating geostationary skin temperature (Tsk) observations into the Catchment land surface model. Global maps of the O-F mean differences are presented, and the two-stage filter is evaluated for one year over the Americas. The two-stage filter effectively removed the Tsk O-F mean differences, for example the GOES-West O-F mean difference at 21:00 UTC was reduced from 5.1 K for a bias-blind assimilation to 0.3 K. Compared to independent in situ and remotely sensed Tsk observations, the two-stage assimilation reduced the unbiased Root Mean Square Difference (ubRMSD) of the modeled Tsk by 10 of the open-loop values.

  5. Dynamic control of modeled tonic-clonic seizure states with closed-loop stimulation

    Directory of Open Access Journals (Sweden)

    Bryce eBeverlin II

    2013-02-01

    Full Text Available Seizure control using deep brain stimulation (DBS provides an alternative therapy to patients with intractable and drug resistant epilepsy. This paper presents novel DBS stimulus protocols to disrupt seizures. Two protocols are presented: open-loop stimulation and a closed-loop feedback system utilizing measured firing rates to adjust stimulus frequency. Stimulation suppression is demonstrated in a computational model using 3000 excitatory Morris-Lecar model neurons connected with depressing synapses. Cells are connected using second order network topology to simulate network topologies measured in cortical networks. The network spontaneously switches from tonic to clonic as synaptic strengths and tonic input to the neurons decreases. To this model we add periodic stimulation pulses to simulate DBS. Periodic forcing can synchronize or desynchronize an oscillating population of neurons, depending on the stimulus frequency and amplitude. Therefore, it is possible to either extend or truncate the tonic or clonic phases of the seizure. Stimuli applied at the firing rate of the neuron generally synchronize the population while stimuli slightly slower than the firing rate prevent synchronization. We present an adaptive stimulation algorithm that measures the firing rate of a neuron and adjusts the stimulus to maintain a relative stimulus frequency to firing frequency and demonstrate it in a computational model of a tonic-clonic seizure. This adaptive algorithm can affect the duration of the tonic phase using much smaller stimulus amplitudes than the open-loop control.

  6. Improving the representation of fire disturbance in dynamic vegetation models by assimilating satellite data

    Directory of Open Access Journals (Sweden)

    E. P. Kantzas

    2015-03-01

    Full Text Available Fire provides an impulsive and stochastic pathway for carbon from the terrestrial biosphere to enter the atmosphere. Despite fire emissions being of similar magnitude to Net Ecosystem Exchange in many biomes, even the most complex Dynamic Vegetation Models (DVMs embedded in General Circulation Models contain poor representations of fire behaviour and dynamics such as propagation and distribution of fire sizes. A model-independent methodology is developed which addresses this issue. Its focus is on the Arctic where fire is linked to permafrost dynamics and on occasion can release great amounts of carbon from carbon-rich organic soils. Connected Component Labeling is used to identify individual fire events across Canada and Russia from daily, low-resolution burned area satellite products, and the results are validated against historical data. This allows the creation of a fire database holding information on area burned and temporal evolution of fires in space and time. A method of assimilating the statistical distribution of fire area into a DVM whilst maintaining its Fire Return Interval is then described. The algorithm imposes a regional scale spatially dependent fire regime on a sub-scale spatially independent model (point model; the fire regime is described by large scale statistical distributions of fire intensity and spatial extent, and the temporal dynamics (fire return intervals are determined locally. This permits DVMs to estimate many aspects of post-fire dynamics that cannot occur under their current representations of fire, as is illustrated by considering the evolution of land cover, biomass and Net Ecosystem Exchange after a fire.

  7. Improving the representation of fire disturbance in dynamic vegetation models by assimilating satellite data

    Science.gov (United States)

    Kantzas, E. P.; Quegan, S.; Lomas, M.

    2015-03-01

    Fire provides an impulsive and stochastic pathway for carbon from the terrestrial biosphere to enter the atmosphere. Despite fire emissions being of similar magnitude to Net Ecosystem Exchange in many biomes, even the most complex Dynamic Vegetation Models (DVMs) embedded in General Circulation Models contain poor representations of fire behaviour and dynamics such as propagation and distribution of fire sizes. A model-independent methodology is developed which addresses this issue. Its focus is on the Arctic where fire is linked to permafrost dynamics and on occasion can release great amounts of carbon from carbon-rich organic soils. Connected Component Labeling is used to identify individual fire events across Canada and Russia from daily, low-resolution burned area satellite products, and the results are validated against historical data. This allows the creation of a fire database holding information on area burned and temporal evolution of fires in space and time. A method of assimilating the statistical distribution of fire area into a DVM whilst maintaining its Fire Return Interval is then described. The algorithm imposes a regional scale spatially dependent fire regime on a sub-scale spatially independent model (point model); the fire regime is described by large scale statistical distributions of fire intensity and spatial extent, and the temporal dynamics (fire return intervals) are determined locally. This permits DVMs to estimate many aspects of post-fire dynamics that cannot occur under their current representations of fire, as is illustrated by considering the evolution of land cover, biomass and Net Ecosystem Exchange after a fire.

  8. Capturing Dynamics in the Power Grid: Formulation of Dynamic State Estimation through Data Assimilation

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Ning; Huang, Zhenyu; Meng, Da; Elbert, Stephen T.; Wang, Shaobu; Diao, Ruisheng

    2014-03-31

    With the increasing complexity resulting from uncertainties and stochastic variations introduced by intermittent renewable energy sources, responsive loads, mobile consumption of plug-in vehicles, and new market designs, more and more dynamic behaviors are observed in everyday power system operation. To operate a power system efficiently and reliably, it is critical to adopt a dynamic paradigm so that effective control actions can be taken in time. The dynamic paradigm needs to include three fundamental components: dynamic state estimation; look-ahead dynamic simulation; and dynamic contingency analysis (Figure 1). These three components answer three basic questions: where the system is; where the system is going; and how secure the system is against accidents. The dynamic state estimation provides a solid cornerstone to support the other 2 components and is the focus of this study.

  9. Local changes in neocortical circuit dynamics coincide with the spread of seizures to thalamus in a model of epilepsy

    Directory of Open Access Journals (Sweden)

    Florian B Neubauer

    2014-09-01

    Full Text Available During the generalization of epileptic seizures, pathological activity in one brain area recruits distant brain structures into joint synchronous discharges. However, it remains unknown whether specific changes in local circuit activity are related to the aberrant recruitment of anatomically distant structures into epileptiform discharges. Further, it is not known whether aberrant areas recruit or entrain healthy ones into pathological activity. Here we study the dynamics of local circuit activity during the spread of epileptiform discharges in the zero-magnesium in vitro model of epilepsy. We employ high-speed multi-photon imaging in combination with dual whole-cell recordings in acute thalamocortical slices of the juvenile mouse to characterize the generalization of epileptic activity between neocortex and thalamus. We find that, although both structures are exposed to zero-magnesium, the initial onset of focal epileptiform discharge occurs in cortex. This suggests that local recurrent connectivity that is particularly prevalent in cortex is important for the initiation of seizure activity. Subsequent recruitment of thalamus into joint, generalized discharges is coincident with an increase in the coherence of local cortical circuit activity that itself does not depend on thalamus. Finally, the intensity of population discharges is positively correlated between both brain areas. This suggests that during and after seizure generalization not only the timing but also the amplitude of epileptiform discharges in thalamus is entrained by cortex. Together these results suggest a central role of neocortical activity for the onset and the structure of pathological recruitment of thalamus into joint synchronous epileptiform discharges.

  10. Febrile Seizures

    Science.gov (United States)

    ... it occasionally can cause drowsiness, a lack of coordination, or hyperactivity. Children vary widely in their susceptibility to such side ... determine the impact of these seizures on the development of epilepsy and memory. Children who have experienced prolonged febrile seizures are more ...

  11. Dopey's seizure.

    Science.gov (United States)

    Dan, B; Christiaens, F

    1999-06-01

    Angelman syndrome is a neurogenetic condition namely characterized by developmental delay, virtual absence of expressive verbal language, peculiar organization of movement, seizures and happy demeanor. This syndrome has been recognized since 1965, but it seems that Walt Disney presented an original depiction of it in his first full-length animated film, including myoclonic jerks and an apparently generalized tonic-clonic seizure.

  12. A reduced-dynamics variational approach for the assimilation of altimeter data into eddy-resolving ocean models

    Science.gov (United States)

    Yu, Peng; Morey, Steven L.; O'Brien, James J.

    A new method of assimilating sea surface height (SSH) data into ocean models is introduced and tested. Many features observable by satellite altimetry are approximated by the first baroclinic mode over much of the ocean, especially in the lower (but non-equatorial) and mid latitude regions. Based on this dynamical trait, a reduced-dynamics adjoint technique is developed and implemented with a three-dimensional model using vertical normal mode decomposition. To reduce the complexity of the variational data assimilation problem, the adjoint equations are based on a one-active-layer reduced-gravity model, which approximates the first baroclinic mode, as opposed to the full three-dimensional model equations. The reduced dimensionality of the adjoint model leads to lower computational cost than a traditional variational data assimilation algorithm. The technique is applicable to regions of the ocean where the SSH variability is dominated by the first baroclinic mode. The adjustment of the first baroclinic mode model fields dynamically transfers the SSH information to the deep ocean layers. The technique is developed in a modular fashion that can be readily implemented with many three-dimensional ocean models. For this study, the method is tested with the Navy Coastal Ocean Model (NCOM) configured to simulate the Gulf of Mexico.

  13. Wavelet-based Gaussian-mixture hidden Markov model for the detection of multistage seizure dynamics: A proof-of-concept study

    Directory of Open Access Journals (Sweden)

    Carlen Peter L

    2011-04-01

    validated with experimental intracellular electrical recordings of seizures. Conclusions The HMM implementation of a seizure dynamics detector is an improvement over existing approaches using visual detection and complexity measures. The subjectivity involved in partitioning the observed data prior to training can be eliminated. It can also decipher the probabilities of seizure state transitions using the magnitude and rate of change wavelet information of the LFPs.

  14. Temperature-dependent changes in neuronal dynamics in a patient with an SCN1A mutation and hyperthermia induced seizures

    Science.gov (United States)

    Peters, C.; Rosch, R. E.; Hughes, E.; Ruben, P. C.

    2016-09-01

    Dravet syndrome is the prototype of SCN1A-mutation associated epilepsies. It is characterised by prolonged seizures, typically provoked by fever. We describe the evaluation of an SCN1A mutation in a child with early-onset temperature-sensitive seizures. The patient carries a heterozygous missense variant (c3818C > T pAla1273Val) in the NaV1.1 brain sodium channel. We compared the functional effects of the variant vs. wild type NaV1.1 using patch clamp recordings from channels expressed in Chinese Hamster Ovary Cells at different temperatures (32, 37, and 40 °C). The variant channels produced a temperature-dependent destabilization of activation and fast inactivation. Implementing these empirical abnormalities in a computational model predicts a higher threshold for depolarization block in the variant, particularly at 40 °C, suggesting a failure to autoregulate at high-input states. These results reveal direct effects of abnormalities in NaV1.1 biophysical properties on neuronal dynamics. They illustrate the value of combining cellular measurements with computational models to integrate different observational scales (gene/channel to patient).

  15. Assimilation of Altimeter Data into a Quasigeostrophic Model of the Gulf Stream System. Part 1; Dynamical Considerations

    Science.gov (United States)

    Capotondi, Antonietta; Malanotte-Rizzoli, Paola; Holland, William R.

    1995-01-01

    The dynamical consequences of constraining a numerical model with sea surface height data have been investigated. The model used for this study is a quasigeostrophic model of the Gulf Stream region. The data that have been assimilated are maps of sea surface height obtained as the superposition of sea surface height variability deduced from the Geosat altimeter measurements and a mean field constructed from historical hydrographic data. The method used for assimilating the data is the nudging technique. Nudging has been implemented in such a way as to achieve a high degree of convergence of the surface model fields toward the observations. The assimilation of the surface data is thus equivalent to the prescription of a surface pressure boundary condition. The authors analyzed the mechanisms of the model adjustment and the characteristics of the resultant equilibrium state when the surface data are assimilated. Since the surface data are the superposition of a mean component and an eddy component, in order to understand the relative role of these two components in determining the characteristics of the final equilibrium state, two different experiments have been considered: in the first experiment only the climatological mean field is assimilated, while in the second experiment the total surface streamfunction field (mean plus eddies) has been used. It is shown that the model behavior in the presence of the surface data constraint can be conveniently described in terms of baroclinic Fofonoff modes. The prescribed mean component of the surface data acts as a 'surface topography' in this problem. Its presence determines a distortion of the geostrophic contours in the subsurface layers, thus constraining the mean circulation in those layers. The intensity of the mean flow is determined by the inflow/outflow conditions at the open boundaries, as well as by eddy forcing and dissipation.

  16. Dynamics of regional brain activity in epilepsy: a cross-disciplinary study on both intracranial and scalp-recorded epileptic seizures

    Science.gov (United States)

    Minadakis, George; Ventouras, Errikos; Gatzonis, Stylianos D.; Siatouni, Anna; Tsekou, Hara; Kalatzis, Ioannis; Sakas, Damianos E.; Stonham, John

    2014-04-01

    Objective. Recent cross-disciplinary literature suggests a dynamical analogy between earthquakes and epileptic seizures. This study extends the focus of inquiry for the applicability of models for earthquake dynamics to examine both scalp-recorded and intracranial electroencephalogram recordings related to epileptic seizures. Approach. First, we provide an updated definition of the electric event in terms of magnitude and we focus on the applicability of (i) a model for earthquake dynamics, rooted in a nonextensive Tsallis framework, (ii) the traditional Gutenberg and Richter law and (iii) an alternative method for the magnitude-frequency relation for earthquakes. Second, we apply spatiotemporal analysis in terms of nonextensive statistical physics and we further examine the behavior of the parameters included in the nonextensive formula for both types of electroencephalogram recordings under study. Main results. We confirm the previously observed power-law distribution, showing that the nonextensive formula can adequately describe the sequences of electric events included in both types of electroencephalogram recordings. We also show the intermittent behavior of the epileptic seizure cycle which is analogous to the earthquake cycles and we provide evidence of self-affinity of the regional electroencephalogram epileptic seizure activity. Significance. This study may provide a framework for the analysis and interpretation of epileptic brain activity and other biological phenomena with similar underlying dynamical mechanisms.

  17. The assimilation of spectral sensing and the WOFOST model for the dynamic simulation of cadmium accumulation in rice tissues

    Science.gov (United States)

    Wu, Ling; Liu, Xiangnan; Wang, Ping; Zhou, Botian; Liu, Meiling; Li, Xuqing

    2013-12-01

    The accurate detection of heavy metal-induced stress on crop growth is important for food security and agricultural, ecological and environmental protection. Spectral sensing offers an efficient and undamaged observation tool to monitor soil and vegetation contamination. This study proposed a methodology for dynamically estimating the total cadmium (Cd) accumulation in rice tissues by assimilating spectral information into WOFOST (World Food Study) model. Based on the differences among ground hyperspectral data of rice in three experiments fields under different Cd concentration levels, the spectral indices MCARI1, NREP and RH were selected to reflect the rice stress condition and dry matter production of rice. With assimilating these sensitive spectral indices into the WOFOST + PROSPECT + SAIL model to optimize the Cd pollution stress factor fwi, the dynamic dry matter production processes of rice were adjusted. Based on the relation between dry matter production and Cd accumulation, we dynamically simulating the Cd accumulation in rice tissues. The results showed that the method performed well in dynamically estimating the total amount of Cd accumulation in rice tissues with R2 over 85%. This study suggests that the proposed method of integrating the spectral information and the crop growth model could successfully dynamically simulate the Cd accumulation in rice tissues.

  18. Computational analysis of the oscillatory dynamics in the processes of CO₂ assimilation and photorespiration.

    Science.gov (United States)

    Dubinsky, Andrey Yu; Ivlev, Alexander A

    2011-02-01

    The computational analysis of the model system consisting of the processes of CO₂ assimilation and photorespiration shows the appearance of sustained oscillations in the system which might reflect their presence in photosynthesizing cells. Concentrations of CO₂ and O₂ oscillate in opposite phases causing Rubisco switching continuously between the carboxylase (CO₂ assimilation) and the oxygenase (photorespiration) reactions. The results of modeling are consistent with carbon isotopic and other observed data. They show that the oscillation period varies from about 1s to 3s depending on the values of parameters taken. Too high concentrations of O₂ suppress the oscillations.

  19. Wavelet Jensen Shannon divergence as a tool for studying the dynamics of frequency band components in EEG epileptic seizures

    Science.gov (United States)

    Pereyra, M. E.; Lamberti, P. W.; Rosso, O. A.

    2007-06-01

    We develop a quantitative method of analysis of EEG records. The method is based on the wavelet analysis of the record and on the capability of the Jensen-Shannon divergence (JSD) to identify dynamical changes in a time series. The JSD is a measure of distance between probability distributions. Therefore for its evaluation it is necessary to define a (time dependent) probability distribution along the record. We define this probability distribution from the wavelet decomposition of the associated time series. The wavelet JSD provides information about dynamical changes in the scales and can be considered a complementary methodology reported earlier [O.A. Rosso, S. Blanco, A. Rabinowicz, Signal Processing 86 (2003) 1275; O.A. Rosso, S. Blanco, J. Yordanova, V. Kolev, A. Figliola, M. Schürmann, E. Başar, J. Neurosci. Methods 105 (2001) 65; O.A. Rosso, M.T. Martin, A. Figliola, K. Keller, A. Plastino, J. Neurosci. Methods 153 (2006) 163]. In the present study we have demonstrated it by analyzing EEG signal of tonic-clonic epileptic seizures applying the JSD method. The display of the JSD curves enables easy comparison of frequency band component dynamics. This would, in turn, promise easy and successful comparison of the EEG records from various scalp locations of the brain.

  20. Multiscale Dynamics and Information in Data Collection and Assimilation for Environmental Applications

    Science.gov (United States)

    2015-07-30

    proof is as follows: vε is asymptotically expanded into an order 1 term, a correction term of order ε, and a remainder order higher than ε. These...observations collected at intervals equal to error doubling time 2. Education and Academic Outreach Results from the development of the reduced-order...Non- linear filtering and data assimilation, The International Centre for Theoretical Sciences ( ICTS ) -Tata Institute of Fundamental Research (TIFR

  1. Controlling Seizures

    Science.gov (United States)

    Henderson, Nancy

    2008-01-01

    This article describes how an implantable device could greatly improve the quality of life for people with epilepsy. Gabe Anderson was diagnosed with bilateral heterotopia, a congenital condition that can lead to the onset of complex partial seizures stemming from both hemispheres of the brain. In early 2004, Gabe became one of the first 35…

  2. Age-Dependent Increase of Absence Seizures and Intrinsic Frequency Dynamics of Sleep Spindles in Rats

    Directory of Open Access Journals (Sweden)

    Evgenia Sitnikova

    2014-01-01

    Full Text Available The risk of neurological diseases increases with age. In WAG/Rij rat model of absence epilepsy, the incidence of epileptic spike-wave discharges is known to be elevated with age. Considering close relationship between epileptic spike-wave discharges and physiologic sleep spindles, it was assumed that age-dependent increase of epileptic activity may affect time-frequency characteristics of sleep spindles. In order to examine this hypothesis, electroencephalograms (EEG were recorded in WAG/Rij rats successively at the ages 5, 7, and 9 months. Spike-wave discharges and sleep spindles were detected in frontal EEG channel. Sleep spindles were identified automatically using wavelet-based algorithm. Instantaneous (localized in time frequency of sleep spindles was determined using continuous wavelet transform of EEG signal, and intraspindle frequency dynamics were further examined. It was found that in 5-months-old rats epileptic activity has not fully developed (preclinical stage and sleep spindles demonstrated an increase of instantaneous frequency from beginning to the end. At the age of 7 and 9 months, when animals developed matured and longer epileptic discharges (symptomatic stage, their sleep spindles did not display changes of intrinsic frequency. The present data suggest that age-dependent increase of epileptic activity in WAG/Rij rats affects intrinsic dynamics of sleep spindle frequency.

  3. Cellular and network mechanisms of electrographic seizures

    Science.gov (United States)

    Bazhenov, Maxim; Timofeev, Igor; Fröhlich, Flavio; Sejnowski, Terrence J.

    2008-01-01

    Epileptic seizures constitute a complex multiscale phenomenon that is characterized by synchronized hyperexcitation of neurons in neuronal networks. Recent progress in understanding pathological seizure dynamics provides crucial insights into underlying mechanisms and possible new avenues for the development of novel treatment modalities. Here we review some recent work that combines in vivo experiments and computational modeling to unravel the pathophysiology of seizures of cortical origin. We particularly focus on how activity-dependent changes in extracellular potassium concentration affects the intrinsic dynamics of neurons involved in cortical seizures characterized by spike/wave complexes and fast runs. PMID:19190736

  4. Assimilation and Individual Differences in Emotion: The Dynamics of Anger and Approach Motivation.

    Science.gov (United States)

    Lechuga, Julia; Fernandez, Norma P

    2011-03-01

    Individuals who cross cultural boundaries face many challenges when trying to adapt to a receiving culture. Adaptation challenges such as learning to maneuver across societal domains may become increasingly complex if structural level factors such as discrimination are present. Researchers have conceptualized acculturation as a relatively autonomous decision indicating that four acculturation strategies exist: assimilation, separation, integration, and marginalization. Moreover, researchers have also long debated the link between acculturation strategy, adaptation hassles and negative health outcomes. However, models seeking to explain how individual difference and structural level variables may influence each other and subsequently influence acculturation and adaptation are needed. The purpose of this study is to lay the foundation for the conceptualization of such a model. We propose that temperamental predispositions to negative emotionality, anger, and impulsivity may highlight discrimination which in turn may lead to increases in acculturative stress and negative markers of psychosocial well-being. We used SEM to test our hypothesized model. Results supported a modified model. Implications for the measurement of adaptation and interventions are discussed.

  5. Assimilation and Individual Differences in Emotion: The Dynamics of Anger and Approach Motivation

    Science.gov (United States)

    Lechuga, Julia; Fernandez, Norma P.

    2011-01-01

    Individuals who cross cultural boundaries face many challenges when trying to adapt to a receiving culture. Adaptation challenges such as learning to maneuver across societal domains may become increasingly complex if structural level factors such as discrimination are present. Researchers have conceptualized acculturation as a relatively autonomous decision indicating that four acculturation strategies exist: assimilation, separation, integration, and marginalization. Moreover, researchers have also long debated the link between acculturation strategy, adaptation hassles and negative health outcomes. However, models seeking to explain how individual difference and structural level variables may influence each other and subsequently influence acculturation and adaptation are needed. The purpose of this study is to lay the foundation for the conceptualization of such a model. We propose that temperamental predispositions to negative emotionality, anger, and impulsivity may highlight discrimination which in turn may lead to increases in acculturative stress and negative markers of psychosocial well-being. We used SEM to test our hypothesized model. Results supported a modified model. Implications for the measurement of adaptation and interventions are discussed. PMID:21625350

  6. An eddy-permitting, dynamically consistent adjoint-based assimilation system for the tropical Pacific: Hindcast experiments in 2000

    KAUST Repository

    Hoteit, Ibrahim

    2010-03-02

    An eddy-permitting adjoint-based assimilation system has been implemented to estimate the state of the tropical Pacific Ocean. The system uses the Massachusetts Institute of Technology\\'s general circulation model and its adjoint. The adjoint method is used to adjust the model to observations by controlling the initial temperature and salinity; temperature, salinity, and horizontal velocities at the open boundaries; and surface fluxes of momentum, heat, and freshwater. The model is constrained with most of the available data sets in the tropical Pacific, including Tropical Atmosphere and Ocean, ARGO, expendable bathythermograph, and satellite SST and sea surface height data, and climatologies. Results of hindcast experiments in 2000 suggest that the iterated adjoint-based descent is able to significantly improve the model consistency with the multivariate data sets, providing a dynamically consistent realization of the tropical Pacific circulation that generally matches the observations to within specified errors. The estimated model state is evaluated both by comparisons with observations and by checking the controls, the momentum balances, and the representation of small-scale features that were not well sampled by the observations used in the assimilation. As part of these checks, the estimated controls are smoothed and applied in independent model runs to check that small changes in the controls do not greatly change the model hindcast. This is a simple ensemble-based uncertainty analysis. In addition, the original and smoothed controls are applied to a version of the model with doubled horizontal resolution resulting in a broadly similar “downscaled” hindcast, showing that the adjustments are not tuned to a single configuration (meaning resolution, topography, and parameter settings). The time-evolving model state and the adjusted controls should be useful for analysis or to supply the forcing, initial, and boundary conditions for runs of other models.

  7. Can Seizure-Alert Dogs predict seizures?

    Science.gov (United States)

    Brown, Stephen W; Goldstein, Laura H

    2011-12-01

    An index observation where a dog was trained to alert to, as well as respond to, human tonic-clonic seizures led to further research and refinement of training techniques. This was followed by anecdotal reports of pet dogs spontaneously anticipating human epileptic seizures. An industry has since developed training Seizure-Alert Dogs (SADs) to give humans warnings of their seizures. In some cases this has been accompanied by a reduction in seizure frequency. SADs may be trained along with the person with epilepsy, responding specifically to that person's seizures, or may be trained separately. Recent sceptical reports of non-epileptic seizures in some people with SADs have cast doubt on dogs' ability to anticipate true epileptic seizures. This may reflect selection criteria for training programmes as well as training methods used, but does not necessarily indicate that SADs might not be able to predict epileptic seizures. Whether the seizures are epileptic or non-epileptic, it is speculated that SADs probably alert to subtle pre-ictal human behaviour changes, but may also be sensitive to heart rate or olfactory cues. As yet, however, no rigorous data exist as to whether seizure prediction by SADS is better than chance, and what false positive and negative prediction rates might be.

  8. Visualization of spatiotemporal energy dynamics of hippocampal neurons by mass spectrometry during a kainate-induced seizure.

    Directory of Open Access Journals (Sweden)

    Yuki Sugiura

    Full Text Available We report the use of matrix-assisted laser desorption/ionization (MALDI imaging mass spectrometry combined with capillary electrophoresis (CE mass spectrometry to visualize energy metabolism in the mouse hippocampus by imaging energy-related metabolites. We show the distribution patterns of ATP, ADP, and AMP in the hippocampus as well as changes in their amounts and distribution patterns in a murine model of limbic, kainate-induced seizure. As an acute response to kainate administration, we found massive and moderate reductions in ATP and ADP levels, respectively, but no significant changes in AMP levels--especially in cells of the CA3 layer. The results suggest the existence of CA3 neuron-selective energy metabolism at the anhydride bonds of ATP and ADP in the hippocampal neurons during seizure. In addition, metabolome analysis of energy synthesis pathways indicates accelerated glycolysis and possibly TCA cycle activity during seizure, presumably due to the depletion of ATP. Consistent with this result, the observed energy depletion significantly recovered up to 180 min after kainate administration. However, the recovery rate was remarkably low in part of the data-pixel population in the CA3 cell layer region, which likely reflects acute and CA3-selective neural death. Taken together, the present approach successfully revealed the spatiotemporal energy metabolism of the mouse hippocampus at a cellular resolution--both quantitatively and qualitatively. We aim to further elucidate various metabolic processes in the neural system.

  9. Technical report series on global modeling and data assimilation. Volume 5: Documentation of the AIRES/GEOS dynamical core, version 2

    Science.gov (United States)

    Suarez, Max J. (Editor); Takacs, Lawrence L.

    1995-01-01

    A detailed description of the numerical formulation of Version 2 of the ARIES/GEOS 'dynamical core' is presented. This code is a nearly 'plug-compatible' dynamics for use in atmospheric general circulation models (GCMs). It is a finite difference model on a staggered latitude-longitude C-grid. It uses second-order differences for all terms except the advection of vorticity by the rotation part of the flow, which is done at fourth-order accuracy. This dynamical core is currently being used in the climate (ARIES) and data assimilation (GEOS) GCMs at Goddard.

  10. Cumulative ozone effect on canopy stomatal resistance and the impact on boundary layer dynamics and CO2 assimilation at the diurnal scale: A case study for grassland in the Netherlands

    NARCIS (Netherlands)

    Super, I.; Vilà-Guerau De Arellano, J.; Krol, M.C.

    2015-01-01

    Biological, chemical, and dynamical processes occurring at the surface strongly interact at diurnal scales. Therefore, this study examines the seasonal ozone impact on stomatal resistance, surface energy balance, boundary layer dynamics, and CO2 assimilation at this (sub)diurnal scale under changing

  11. Dynamics of Control and Resistance: Reactions to the Modern Policy of Assimilation of the Travellers in Norway

    Directory of Open Access Journals (Sweden)

    Rune Halvorsen

    2004-07-01

    Full Text Available For much of the 20th century, the Norwegian authorities pursued a strict assimilation policy towards Travellers (tatere/ romanifolket and their culture. As was the case in many other countries, Travellers were constructed as "the other" (Riggins 1997, MacLaughlin 1999. When compared to other Western European countries, it is, however, surprising that Norwegian Travellers were seen as such a serious problem and threat during the 20th century. The 1845 census counted 1145 Travellers out of a total population of 1.3 million in Norway (Sundt 1852, SSB 1968: Table 13. A private charity organisation acting on behalf of the state registered 5129 "itinerants" in their archives from 1900 to 1959 (Haave 2000. These were the figures that worried the elites. This paper examines the modern assimilation policy and Travellers' reactions to this policy. In particular the paper analyses the internal relation between the modern assimilation policy and the emergence of collective demands for recognition as an ethnic minority and moral redress among Travellers in the 1990s.

  12. Fever, febrile seizures and epilepsy

    OpenAIRE

    2007-01-01

    Seizures induced by fever (febrile seizures) are the most common type of pathological brain activity in infants and children. These febrile seizures and their potential contribution to the mechanisms of limbic (temporal lobe) epilepsy have been a topic of major clinical and scientific interest. Key questions include the mechanisms by which fever generates seizures, the effects of long febrile seizures on neuronal function and the potential contribution of these seizures to epilepsy. This revi...

  13. Management of provoked seizure

    Directory of Open Access Journals (Sweden)

    Misra Usha

    2011-01-01

    Full Text Available A provoked seizure may be due to structural damage (resulting from traumatic brain injury, brain tumor, stroke, tuberculosis, or neurocysticercosis or due to metabolic abnormalities (such as alcohol withdrawal and renal or hepatic failure. This article is a part of the Guidelines for Epilepsy in India. This article reviews the problem of provoked seizure and its management and also provides recommendations based on currently available information. Seizure provoked by metabolic disturbances requires correction of the triggering factors. Benzodiazepines are recommended for treatment of seizure due to alcohol withdrawal; gabapentin for seizure seen in porphyria; and antiepileptic drugs (AED, that are not inducer of hepatic enzymes, in the seizures seen in hepatic dysfunction. In severe traumatic brain injury, with or without seizure, phenytoin (PHT may be given for 7 days. In ischemic or hemorrhagic stroke one may individualize the AED therapy. In cerebral venous sinus thrombosis (CVST, AED may be prescribed if there is seizure or computed tomographic (CT abnormalities or focal weakness; the treatment, in these cases, has to be continued for 1 year. Prophylactic AED is not recommended in cases of brain tumor and neurosurgical procedures and if patient is on an AED it can be stopped after 1 week.

  14. Dynamics of Arctic and Sub-Arctic Climate and Atmospheric Circulation: Diagnosis of Mechanisms and Biases Using Data Assimilation

    Energy Technology Data Exchange (ETDEWEB)

    Eric T. DeWeaver

    2010-01-19

    This is the final report for DOE grant DE-FG02-07ER64434 to Eric DeWeaver at the University of Wisconsin-Madison. The overall goal of work performed under this grant is to enhance understanding of simulations of present-day climate and greenhouse gas-induced climate change. Enhanced understanding is desirable 1) as a prerequisite for improving simulations; 2) for assessing the credibility of model simulations and their usefulness as tools for decision support; and 3) as a means to identify robust behaviors which commonly occur over a wide range of models, and may yield insights regarding the dominant physical mechanisms which determine mean climate and produce climate change. A furthe objective is to investigate the use of data assimilation as a means for examining and correcting model biases. Our primary focus is on the Arctic, but the scope of the work was expanded to include the global climate system to the extent that research targets of opportunity present themselves. Research performed under the grant falls into five main research areas: 1) a study of data assimilation using an ensemble filter with the atmospheric circulation model of the National Center for Atmospheric Research, in which both conventional observations and observations of the refraction of radio waves from GPS satellites were used to constrain the atmospheric state of the model; 2) research on the likely future status of polar bears, in which climate model simluations were used to assess the effectiveness of climate change mitigation efforts in preserving the habitat of polar bears, now considered a threatened species under global warming; 3) as assessment of the credibility of Arctic sea ice thickness simulations from climate models; 4) An examination of the persistence and reemergence of Northern Hemisphere sea ice area anomalies in climate model simulations and in observations; 5) An examination of the roles played by changes in net radiation and surface relative humidity in determine the

  15. An application of Data Assimilation to a dynamic global vegetation model: fusing CLM(ED) model results with streams of observed data

    Science.gov (United States)

    Massoud, Elias; Xu, Chonggang; Fisher, Rosie; Vrugt, Jasper

    2016-04-01

    We implement a data assimilation approach for a Dynamic Global Vegetation Model (DGVM), named the CLM(ED) for its combined strengths of a Community Land Model (CLM) and an implementation of the Ecosystem Demography (ED) concept. This unique model combination allows for scaling the behavior of forest ecosystems by aggregating individual trees into representative "cohorts", and thus allows for the prediction of plant distribution (including stem distribution, mortality, and growth) directly from their given physiological traits. The model is constantly improving as it evolves, as less simple empirical models are used and more physically based ones are included to represent the physiological and biogeochemical processes taking place on the land-air surface. For example, very recently a mechanistic model simulating the photosynthetic capacity was implemented for a better representation of a leaf's nitrogen allocation. Some possible outputs of CLM(ED) include GPP, NPP, LAI, and interestingly, predictions of biome boundaries. In this study, we first conduct a global sensitivity analysis by estimating the range of model parameters from literature. Then, an application of Data Assimilation (DA) is introduced, where we attempt to fuse the model simulations with observed data, such as GPP. The updated system properties achieved through DA allow for better parameterization and more accurate overall predictions of vegetation dynamics. More importantly, this study addresses structural uncertainties within the model, and by combining model estimates with observed measurements, we aim to improve the overall representation of the underlying processes by explicitly pinpointing deficiencies in the model structure. We advocate the use of DA in Earth System Models for many reasons, including the direct benefit linked to the recent availability of ecological data sets, the efficient implementation within models thanks to improvements in computational power, and the proven ability of DA

  16. Epileptic Seizures: Quakes of the brain?

    CERN Document Server

    Osorio, Ivan; Sornette, Didier; Milton, John; Lai, Ying-Cheng

    2007-01-01

    The concept of universality proposes that dynamical systems with the same power law behaviors are equivalent at large scales. We test this hypothesis on the Earth's crust and the epileptic brain, and discover that power laws also govern the distributions of seizure energies and recurrence times. This robust correspondence is extended over seven statistics, including the direct and inverse Omori laws. We also verify in an animal seizure model the earthquake-driven hypothesis that power law statistics co-exist with characteristic scales, as coupling between constitutive elements increases towards the synchronization regime. These observations point to the universality of the dynamics of coupled threshold oscillators for systems even as diverse as Earth and brain and suggest a general strategy for forecasting seizures, one of neurosciences' grails.

  17. Diazepam for Febrile Seizures

    OpenAIRE

    1990-01-01

    The efficacy and side effects of intermittent oral diazepam for the prevention of febrile seizure recurrence were investigated in the Departments of Clinical Pharmacology, Neurosurgery, and Biostatistics, University of Tours, France.

  18. Fibromyalgia and seizures.

    Science.gov (United States)

    Tatum, William O; Langston, Michael E; Acton, Emily K

    2016-06-01

    The purpose of this case-matched study was to determine how frequently fibromyalgia is associated with different paroxysmal neurological disorders and explore the utility of fibromyalgia as a predictor for the diagnosis of psychogenic non-epileptic seizures. The billing diagnosis codes of 1,730 new, non-selected patient encounters were reviewed over a three-year period for an epileptologist in a neurology clinic to identify all patients with historical diagnoses of fibromyalgia. The frequency with which epileptic seizures, psychogenic non-epileptic seizures, and physiological non-epileptic events were comorbid with fibromyalgia was assessed. Age and gender case-matched controls were used for a between-group comparison. Wilcoxon tests were used to analyse interval data, and Chi-square was used to analyse categorical data (pFibromyalgia was retrospectively identified in 95/1,730 (5.5%) patients in this cohort. Females represented 95% of the fibromyalgia sample (age: 53 years; 95% CI: 57, 51). Forty-three percent of those with fibromyalgia had a non-paroxysmal, neurological primary clinical diagnosis, most commonly chronic pain. Paroxysmal events were present in 57% of fibromyalgia patients and 54% of case-matched controls. Among patients with fibromyalgia and paroxysmal disorders, 11% had epileptic seizures, 74% had psychogenic non-epileptic seizures, and 15% had physiological non-epileptic events, compared to case-matched controls with 37% epileptic seizures, 51% psychogenic non-epileptic events, and 12% physiological non-epileptic events (p = 0.009). Fibromyalgia was shown to be a predictor for the diagnosis of psychogenic non-epileptic seizures in patients with undifferentiated paroxysmal spells. However, our results suggest that the specificity and sensitivity of fibromyalgia as a marker for psychogenic non-epileptic seizures in a mixed general neurological population of patients is less than previously described.

  19. Seizures Induced by Music

    Directory of Open Access Journals (Sweden)

    A. O. Ogunyemi

    1993-01-01

    Full Text Available Musicogenic epilepsy is a rare disorder. Much remains to be learned about the electroclinical features. This report describes a patient who has been followed at our institution for 17 years, and was investigated with long-term telemetered simultaneous video-EEG recordings. She began to have seizures at the age of 10 years. She experienced complex partial seizures, often preceded by elementary auditory hallucination and complex auditory illusion. The seizures occurred in relation to singing, listening to music or thinking about music. She also had occasional generalized tonic clonic seizures during sleep. There was no significant antecedent history. The family history was negative for epilepsy. The physical examination was unremarkable. CT and MRI scans of the brain were normal. During long-term simultaneous video-EEG recordings, clinical and electrographic seizure activities were recorded in association with singing and listening to music. Mathematical calculation, copying or viewing geometric patterns and playing the game of chess failed to evoke seizures.

  20. Assortative mixing in functional brain networks during epileptic seizures

    CERN Document Server

    Bialonski, Stephan

    2013-01-01

    We investigate assortativity of functional brain networks before, during, and after one-hundred epileptic seizures with different anatomical onset locations. We construct binary functional networks from multi-channel electroencephalographic data recorded from 60 epilepsy patients, and from time-resolved estimates of the assortativity coefficient we conclude that positive degree-degree correlations are inherent to seizure dynamics. While seizures evolve, an increasing assortativity indicates a segregation of the underlying functional network into groups of brain regions that are only sparsely interconnected, if at all. Interestingly, assortativity decreases already prior to seizure end. Together with previous observations of characteristic temporal evolutions of global statistical properties and synchronizability of epileptic brain networks, our findings may help to gain deeper insights into the complicated dynamics underlying generation, propagation, and termination of seizures.

  1. Febrile and other occasional seizures.

    Science.gov (United States)

    Bast, T; Carmant, L

    2013-01-01

    Seizures with fever that result from encephalitis or meningitis usually occur late in the course of febrile illness, and are focal and prolonged. Febrile seizures are by far the most common affecting 5% of the population, followed by posttraumatic seizures and those observed in the setting of a toxic, infectious, or metabolic encephalopathy. This chapter reviews the clinical presentation of the three most common forms, due to fever, trauma, and intoxication. Febrile seizures carry no cognitive or mortality risk. Recurrence risk is increased by young age, namely before 1 year of age. Febrile seizures that persist after the age of 6 years are usually part of the syndrome of Generalized epilepsy febrile seizures plus. These febrile seizures have a strong link with epilepsy since non-febrile seizures may occur later in the same patient and in other members of the same family with an autosomal dominant transmission. Complex febrile seizures, i.e., with focal or prolonged manifestations or followed by focal defect, are related to later mesial temporal epilepsy with hippocampal sclerosis; risk factors are seizure duration and brain malformation. Prophylactic treatment is usually not required in febrile seizures. Early onset of complex seizures is the main indication for AED prophylaxis. Early posttraumatic seizures, i.e., within the first week, are often focal and indicate brain trauma: contusion, hematoma, 24 hours amnesia, and depressed skull fracture are major factors of posttraumatic epilepsy. Prophylaxis with antiepileptic drugs is not effective. Various psychotropic drugs, including antiepileptics, may cause seizures.

  2. [Pyridoxine dependent seizures].

    Science.gov (United States)

    Hansen, K N; Ostergaard, J R; Møller, S M

    1994-10-17

    Pyridoxine dependent seizures is a rare autosomal recessive disorder. Its manifestations are intractable epilepsy leading to death in status epilepticus. Treatment with pyridoxine prevents the seizures and normalizes the EEG. Early diagnosis is important for the intellectual outcome. In Denmark, the disease has occurred in a child of healthy Tamil immigrants, who are first cousins. The child's case story is described and points to awareness of increased occurrence of rare autosomal recessive disorders in immigrants from cultures with traditional consanguinity. We suggest giving a pyridoxine test dosis to all cases of severe epilepsy and status epilepticus in infants younger than 18 months.

  3. Classification of seizures and epilepsy.

    Science.gov (United States)

    Riviello, James J

    2003-07-01

    The management of seizures and epilepsy begins with forming a differential diagnosis, making the diagnosis, and then classifying seizure type and epileptic syndrome. Classification guides treatment, including ancillary testing, management, prognosis, and if needed, selection of the appropriate antiepileptic drug (AED). Many AEDs are available, and certain seizure types or epilepsy syndromes respond to specific AEDs. The identification of the genetics, molecular basis, and pathophysiologic mechanisms of epilepsy has resulted from classification of specific epileptic syndromes. The classification system used by the International League Against Epilepsy is periodically revised. The proposed revision changes the classification emphasis from the anatomic origin of seizures (focal vs generalized) to seizure semiology (ie, the signs or clinical manifestations). Modified systems have been developed for specific circumstances (eg, neonatal seizures, infantile seizures, status epilepticus, and epilepsy surgery). This article reviews seizure and epilepsy classification, emphasizing new data.

  4. GELASTIC SEIZURES IN TUBEROUS SCLEROSIS

    Directory of Open Access Journals (Sweden)

    M. B. Mironov

    2014-01-01

    Full Text Available The authors consider the historical description, nosological entity, clinical and electroencephalographic manifestations of gelastic seizures, a rare type of epileptic seizures manifesting as sudden attacks of spasmodic laughter. They describe their case of gelastic seizures in a child with tuberous sclerosis.

  5. Terminology of psychogenic nonepileptic seizures.

    Science.gov (United States)

    Brigo, Francesco; Igwe, Stanley C; Ausserer, Harald; Nardone, Raffaele; Tezzon, Frediano; Bongiovanni, Luigi Giuseppe; Tinazzi, Michele; Trinka, Eugen

    2015-03-01

    Several different terms have been used to describe "psychogenic nonepileptic seizures" (PNES) in the literature. In this study, we evaluated the most common English terms used to describe PNES on Google and in PubMed using multiple search terms (https://www.google.com and http://www.ncbi.nlm.nih.gov/pubmed). The information prevalence of the five terms most frequently used to refer to PNES in PubMed were: psychogenic non(-)epileptic seizure(s), followed by pseudo(-)seizure(s), non(-)epileptic seizure(s), psychogenic seizure(s), and non(-)epileptic event(s). The five most frequently adopted terms to describe PNES in Google were: psychogenic non(-)epileptic seizure(s), followed by non(-)epileptic event(s), psychogenic attack(s), non(-)epileptic attack(s), and psychogenic non(-)epileptic attack(s). The broad spectrum of synonyms used to refer to PNES in the medical literature reflects a lack of internationally accepted, uniform terminology for PNES. In addition to "seizure(s)," lay people use the word "attack(s)" to describe PNES. Although considered obsolete, some terms, e.g., pseudoseizure(s), are still used in the recent medical literature. Adopting a uniform terminology to describe PNES could facilitate communication between epileptologists, physicians without specific expertise in epilepsy, and patients.

  6. Seizures Complicating Bacterial Meningitis

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2004-09-01

    Full Text Available The clinical data of 116 patients, 1 month to <5 years of age, admitted for bacterial meningitis, and grouped according to those with and without seizures during hospitalization, were compared in a study at Buddhist Dalin Tzu Chi General Hospital, Chang Gung Memorial Hospital and other centers in Taiwan.

  7. Assimilating atmosphere reanalysis in coupled data assimilation

    Science.gov (United States)

    Liu, Huaran; Lu, Feiyu; Liu, Zhengyu; Liu, Yun; Zhang, Shaoqing

    2016-06-01

    This paper tests the idea of substituting the atmospheric observations with atmospheric reanalysis when setting up a coupled data assimilation system. The paper focuses on the quantification of the effects on the oceanic analysis resulted from this substitution and designs four different assimilation schemes for such a substitution. A coupled Lorenz96 system is constructed and an ensemble Kalman filter is adopted. The atmospheric reanalysis and oceanic observations are assimilated into the system and the analysis quality is compared to a benchmark experiment where both atmospheric and oceanic observations are assimilated. Four schemes are designed for assimilating the reanalysis and they differ in the generation of the perturbed observation ensemble and the representation of the error covariance matrix. The results show that when the reanalysis is assimilated directly as independent observations, the root-mean-square error increase of oceanic analysis relative to the benchmark is less than 16% in the perfect model framework; in the biased model case, the increase is less than 22%. This result is robust with sufficient ensemble size and reasonable atmospheric observation quality (e.g., frequency, noisiness, and density). If the observation is overly noisy, infrequent, sparse, or the ensemble size is insufficiently small, the analysis deterioration caused by the substitution is less severe since the analysis quality of the benchmark also deteriorates significantly due to worse observations and undersampling. The results from different assimilation schemes highlight the importance of two factors: accurate representation of the error covariance of the reanalysis and the temporal coherence along each ensemble member, which are crucial for the analysis quality of the substitution experiment.

  8. Multiscale Data Assimilation

    Science.gov (United States)

    2014-09-30

    1 Multiscale Data Assimilation Dr. Pierre F.J. Lermusiaux Department of Mechanical Engineering, Center for Ocean Science and Engineering...concerned with next-generation multiscale data assimilation , with a focus on shelfbreak regions, including non-hydrostatic effects. Our long-term...goals are to: - Develop and utilize GMM-DO data assimilation schemes for rigorous multiscale inferences, where observations provide information on

  9. Thermospheric Data Assimilation

    Science.gov (United States)

    2016-05-05

    Thermospheric Data Assimilation 5a. CONTRACT NUMBER 5b. GRANT NUMBER FA9550-13-1-0058 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) Dr. Tomoko...unlimited 13. SUPPLEMENTARY NOTES Program Manager: Dr. Julie J Moses, AFOSR, 703-696-9586, Julie.moses@us.af.mil 14. ABSTRACT This project...thermosphere-ionosphere first- principles model. An ensemble data assimilation procedure, constructed with the NCAR Data Assimilation Research Testbed

  10. Variational data assimilation with superparameterization

    Directory of Open Access Journals (Sweden)

    I. Grooms

    2015-03-01

    Full Text Available Superparameterization (SP is a multiscale computational approach wherein a large scale atmosphere or ocean model is coupled to an array of simulations of small scale dynamics on periodic domains embedded into the computational grid of the large scale model. SP has been successfully developed in global atmosphere and climate models, and is a promising approach for new applications. The authors develop a 3D-Var variational data assimilation framework for use with SP; the relatively low cost and simplicity of 3D-Var in comparison with ensemble approaches makes it a natural fit for relatively expensive multiscale SP models. To demonstrate the assimilation framework in a simple model, the authors develop a new system of ordinary differential equations similar to the two-scale Lorenz-'96 model. The system has one set of variables denoted {Yi}, with large and small scale parts, and the SP approximation to the system is straightforward. With the new assimilation framework the SP model approximates the large scale dynamics of the true system accurately.

  11. Emergence of semiology in epileptic seizures.

    Science.gov (United States)

    Chauvel, Patrick; McGonigal, Aileen

    2014-09-01

    clinical expression, as evidenced, for example, by studies of ictal fear-related behavior (decorrelation of activity between structures inducing "release" phenomena) and of déjà vu (increased synchronization). Studies of functional coupling within networks underlying complex ictal behavior indicate that the clinical semiology of a given seizure depends upon neither the anatomical origin of ictal discharge nor the target areas of its propagation alone but on the dynamic interaction between these. Careful mapping of the ictal network in its full spread offers essential information as to the localization of seizure onset, by deducing that a given network configuration could only be generated by a given area or group of areas.

  12. Data Assimilation in Marine Models

    DEFF Research Database (Denmark)

    Frydendall, Jan

    a computational point of view, e.g. low storage cost, no linearizations of the numerical models, etc. However, this also gives rise to many unforeseen difficulties, e.g. the curse of dimensionality, huge computational costs, etc. The challenge faced in this thesis was finding filters that could handle...... assimilation concept into an atmospheric chemical transport model. This paper deals with the results and conclusions obtained through some of the first experiments with the Optimal Interpolation filter in a geophysical model. The second paper F, deals with the construction of a finite element solver......This thesis consists of six research papers published or submitted for publication in the period 2006-2009 together with a summary report. The main topics of this thesis are nonlinear data assimilation techniques and estimation in dynamical models. The focus has been on the nonlinear filtering...

  13. Voltage synchronizations between multichannel electroencephalograms during epileptic seizures

    CERN Document Server

    Tuncay, Caglar

    2010-01-01

    The underlying dynamics for the electroencephalographic (EEG) recordings from humans but especially epilepsy patients are usually not completely known. However, the ictal activity is claimed to be characterized by synchronous oscillations in the brain voltages in the literature. These time dependent interdependencies (synchronization, coupling) between the EEG voltages from epileptogenic and non epileptogenic brain sites of nineteen focal epileptic patients are investigated in this work. It is found that strong synchronizationdesynchronization events occur in alternation during most of the investigated seizures. Thus, these seizures are detected with considerable sensitivity (71 of the 79 seizures).

  14. Increased Cortical Extracellular Adenosine Correlates with Seizure Termination

    Science.gov (United States)

    Van Gompel, Jamie J.; Bower, Mark R.; Worrell, Gregory A.; Stead, Matt; Chang, Su-Youne; Goerss, Stephan J.; Kim, Inyong; Bennet, Kevin E.; Meyer, Fredric B.; Marsh, W. Richard; Blaha, Charles D.; Lee, Kendall H.

    2014-01-01

    Objective Seizures are currently defined by their electrographic features. However, neuronal networks are intrinsically dependent upon neurotransmitters of which little is known regarding their peri-ictal dynamics. Evidence supports adenosine as having a prominent role in seizure termination, as its administration can terminate and reduce seizures in animal models. Further, microdialysis studies in humans suggest adenosine is elevated peri-ictally, but the relationship to the seizure is obscured by its temporal measurement limitations. Because electrochemical techniques can provide vastly superior temporal resolution, we test the hypothesis that extracellular adenosine concentrations rise during seizure termination in an animal model and humans using electrochemistry. Methods White farm swine (n=45) were used in an acute cortical model of epilepsy and 10 human epilepsy patients were studied during intraoperative electrocorticography (Ecog). Wireless Instantaneous Neurotransmitter Concentration Sensor (WINCS) based fast scan cyclic voltametry (FSCV) and fixed potential amperometry were obtained utilizing an adenosine specific triangular waveform or biosensors respectively. Results Simultaneous Ecog and electrochemistry demonstrated an average adenosine rise of 260% compared to baseline at 7.5 ± 16.9 seconds with amperometry (n=75 events) and 2.6 ± 11.2 seconds with FSCV (n=15 events) prior to electrographic seizure termination. In agreement with these animal data, adenosine elevation prior to seizure termination in a human patient utilizing FSCV was also seen. Significance Simultaneous Ecog and electrochemical recording supports the hypothesis that adenosine rises prior to seizure termination, suggesting that adenosine itself may be responsible for seizure termination. Future work using intraoperative WINCS based FSCV recording may help to elucidate the precise relationship between adenosine and seizure termination. PMID:24483230

  15. MMR Vaccination and Febrile Seizures

    DEFF Research Database (Denmark)

    Vestergaard, Mogens; Hviid, Anders; Madsen, Kreesten Meldgaard

    2004-01-01

    CONTEXT: The rate of febrile seizures increases following measles, mumps, and rubella (MMR) vaccination but it is unknown whether the rate varies according to personal or family history of seizures, perinatal factors, or socioeconomic status. Furthermore, little is known about the long-term outcome...... of febrile seizures increased during the 2 weeks following MMR vaccination (2.75; 95% confidence interval [CI], 2.55-2.97), and thereafter was close to the observed RR for nonvaccinated children. The RR did not vary significantly in the subgroups of children that had been defined by their family history...... of seizures, perinatal factors, or socioeconomic status. At 15 to 17 months, the risk difference of febrile seizures within 2 weeks following MMR vaccination was 1.56 per 1000 children overall (95% CI, 1.44-1.68), 3.97 per 1000 (95% CI, 2.90-5.40) for siblings of children with a history of febrile seizures...

  16. Psychogenic seizures--why women?

    Science.gov (United States)

    Rosenbaum, M

    2000-01-01

    The only consistent finding in studies of psychogenic seizures is the approximately threefold higher incidence in women. Therefore, why women? Charcot and Freud emphasized the sexual aspects of the seizure as has the current interest in childhood sexual abuse. From case studies and review of the literature the author believes that psychogenic seizures in women express rage, fear, and helplessness against the dominant and abusive male rather than sexual conflicts. Emphasizing the aggressive component of seizures does not minimize the traumatic effects of sexual abuse but rather includes it as leading to rage and helplessness.

  17. Seizure activity post organophosphate exposure.

    Science.gov (United States)

    Tattersall, John

    2009-01-01

    Electrographic seizures are a feature of organophosphate anticholinesterase intoxication. Clinical studies of pesticide poisonings suggest that seizures are more common in children than in adults. Since flaccid paralysis, a characteristic sign of organophosphate poisoning, can mask convulsions, the most reliable indicator of seizures is the electroencephalogram, but this has not been widely used in clinical studies. Seizures can rapidly progress to status epilepticus, contributing to mortality and, in survivors, to neuronal damage and neurological impairment. Anticonvulsant drugs can significantly reduce the lethal and toxic effects of these compounds. A benzodiazepine, usually diazepam, is the treatment currently indicated for control of seizures. Animal studies have indicated that the early phase of seizure activity (0-5 min after seizure onset) is purely cholinergic, predominantly involving muscarinic mechanisms. Seizure activity subsequently progresses through mixed cholinergic and noncholinergic modulation (5-40 min) into a final noncholinergic phase. Neuropathology caused by seizures is most likely associated with glutamatergic excitotoxicity. Future prospects for improved treatments include new benzodiazepines, glutamate receptor antagonists, antimuscarinics with additional antiglutamatergic activity and adenosine receptor antagonists.

  18. An Ensemble Algorithm Based Component for Geomagnetic Data Assimilation

    Directory of Open Access Journals (Sweden)

    Zhibin Sun and Weijia Kuang

    2015-01-01

    Full Text Available Geomagnetic data assimilation is one of the most recent developments in geomagnetic studies. It combines geodynamo model outputs and surface geomagnetic observations to provide more accurate estimates of the core dynamic state and provide accurate geomagnetic secular variation forecasting. To facilitate geomagnetic data assimilation studies, we develop a stand-alone data assimilation component for the geomagnetic community. This component is used to calculate the forecast error covariance matrices and the gain matrix from a given geodynamo solution, which can then be used for sequential geomagnetic data assimilation. This component is very flexible and can be executed independently. It can also be easily integrated with arbitrary dynamo models.

  19. Oxygen desaturations triggered by partial seizures: implications for cardiopulmonary instability in epilepsy

    Science.gov (United States)

    Blum, A. S.; Ives, J. R.; Goldberger, A. L.; Al-Aweel, I. C.; Krishnamurthy, K. B.; Drislane, F. W.; Schomer, D. L.

    2000-01-01

    PURPOSE: The occurrence of hypoxemia in adults with partial seizures has not been systematically explored. Our aim was to study in detail the temporal dynamics of this specific type of ictal-associated hypoxemia. METHODS: During long-term video/EEG monitoring (LTM), patients underwent monitoring of oxygen saturation using a digital Spo2 (pulse oximeter) transducer. Six patients (nine seizures) were identified with oxygen desaturations after the onset of partial seizure activity. RESULTS: Complex partial seizures originated from both left and right temporal lobes. Mean seizure duration (+/-SD) was 73 +/- 18 s. Mean Spo2 desaturation duration was 76 +/- 19 s. The onset of oxygen desaturation followed seizure onset with a mean delay of 43 +/- 16 s. Mean (+/-SD) Spo2 nadir was 83 +/- 5% (range, 77-91%), occurring an average of 35 +/- 12 s after the onset of the desaturation. One seizure was associated with prolonged and recurrent Spo2 desaturations. CONCLUSIONS: Partial seizures may be associated with prominent oxygen desaturations. The comparable duration of each seizure and its subsequent desaturation suggests a close mechanistic (possibly causal) relation. Spo2 monitoring provides an added means for seizure detection that may increase LTM yield. These observations also raise the possibility that ictal ventilatory dysfunction could play a role in certain cases of sudden unexpected death in epilepsy in adults with partial seizures.

  20. Displacement Data Assimilation

    CERN Document Server

    Rosenthal, W Steven; Mariano, Arthur J; Restrepo, Juan M

    2016-01-01

    We show that modifying a Bayesian data assimilation scheme by incorporating kinematically-consistent displacement corrections produces a scheme that is demonstrably better at estimating partially observed state vectors in a setting where feature information important. While the displacement transformation is not tied to any particular assimilation scheme, here we implement it within an ensemble Kalman Filter and demonstrate its effectiveness in tracking stochastically perturbed vortices.

  1. Fluoxetine Overdose-Induced Seizure

    OpenAIRE

    Suchard, Jeffrey R

    2008-01-01

    A 37-year-old woman experienced a witnessed generalized seizure in the Emergency Department three hours after ingesting approximately 1400 mg of fluoxetine in a suicide attempt. Although the majority of fluoxetine ingestions are benign, seizures may occur after large intentional overdoses. [WestJEM. 2008;9:154-156

  2. Recurrent seizures after lidocaine ingestion

    Directory of Open Access Journals (Sweden)

    Hamed Aminiahidashti

    2015-01-01

    Full Text Available Lidocaine has a concentration-dependent effect on seizures. Concentrations above 15 μg/mL frequently result in seizures in laboratory animals and human. We report a case of central nervous system (CNS lidocaine toxicity and recurrent seizure after erroneous ingestion of lidocaine solution. A 4-year-old boy presented to the Emergency Department of Imam Hospital of Sari in December 2013 due to tonic-clonic generalized seizures approximately 30 min ago. 3 h before seizure, his mother gave him 2 spoons (amount 20-25 cc lidocaine hydrochloride 2% solution instead of pediatric gripe by mistake. Seizure with generalized tonic-clonic occurred 3 times in home. Neurological examination was essentially unremarkable except for the depressed level of consciousness. Personal and medical history was unremarkable. There was no evidence of intracranial ischemic or hemorrhagic lesions in computed tomography scan. There were no further seizures, the condition of the patient remained stable, and he was discharged 2 days after admission. The use of viscous lidocaine may result in cardiovascular and CNS toxicity, particularly in children. Conservative management is the best option for treatment of lidocaine induced seizure.

  3. [Reflex seizures, cinema and television].

    Science.gov (United States)

    Olivares-Romero, Jesús

    2015-12-16

    In movies and television series are few references to seizures or reflex epilepsy even though in real life are an important subgroup of total epileptic syndromes. It has performed a search on the topic, identified 25 films in which they appear reflex seizures. Most seizures observed are tonic-clonic and visual stimuli are the most numerous, corresponding all with flashing lights. The emotions are the main stimuli in higher level processes. In most cases it is not possible to know if a character suffers a reflex epilepsy or suffer reflex seizures in the context of another epileptic syndrome. The main conclusion is that, in the movies, the reflex seizures are merely a visual reinforcing and anecdotal element without significant influence on the plot.

  4. Predicting epileptic seizures in advance.

    Directory of Open Access Journals (Sweden)

    Negin Moghim

    Full Text Available Epilepsy is the second most common neurological disorder, affecting 0.6-0.8% of the world's population. In this neurological disorder, abnormal activity of the brain causes seizures, the nature of which tend to be sudden. Antiepileptic Drugs (AEDs are used as long-term therapeutic solutions that control the condition. Of those treated with AEDs, 35% become resistant to medication. The unpredictable nature of seizures poses risks for the individual with epilepsy. It is clearly desirable to find more effective ways of preventing seizures for such patients. The automatic detection of oncoming seizures, before their actual onset, can facilitate timely intervention and hence minimize these risks. In addition, advance prediction of seizures can enrich our understanding of the epileptic brain. In this study, drawing on the body of work behind automatic seizure detection and prediction from digitised Invasive Electroencephalography (EEG data, a prediction algorithm, ASPPR (Advance Seizure Prediction via Pre-ictal Relabeling, is described. ASPPR facilitates the learning of predictive models targeted at recognizing patterns in EEG activity that are in a specific time window in advance of a seizure. It then exploits advanced machine learning coupled with the design and selection of appropriate features from EEG signals. Results, from evaluating ASPPR independently on 21 different patients, suggest that seizures for many patients can be predicted up to 20 minutes in advance of their onset. Compared to benchmark performance represented by a mean S1-Score (harmonic mean of Sensitivity and Specificity of 90.6% for predicting seizure onset between 0 and 5 minutes in advance, ASPPR achieves mean S1-Scores of: 96.30% for prediction between 1 and 6 minutes in advance, 96.13% for prediction between 8 and 13 minutes in advance, 94.5% for prediction between 14 and 19 minutes in advance, and 94.2% for prediction between 20 and 25 minutes in advance.

  5. Frequency evolution during tonic-clonic seizures.

    Science.gov (United States)

    Quiroga, R Quian; Garcia, H; Rabinowicz, A

    2002-09-01

    By using the Short Time Fourier Transform, we analyzed the EEG frequency evolution during tonic-clonic seizures on 18 scalp recordings corresponding to 7 patients admitted for Video-EEG monitoring. This information was correlated with clinical findings observed in the video recordings. From the time-frequency plots, we recognized patterns related with brain activity even when embedded in a background of muscle artifacts. In 13/18 seizures we found a clear frequency dynamics characterized by an activity originally localized at about 8 Hz, later slowing down to about 1.5 Hz. In the remaining cases muscle artifacts hinder the disclosure of a clear frequency evolution. The clonic phases started when the main frequency slowed down to about 3 Hz. We conclude that the Short Time Fourier Transform is very useful for a quantitative analysis of epileptic seizures, especially when muscle artifacts contaminate the recordings. We further conclude that the clonic phase starts as a response to brain activity that can be only established when brain oscillations are slow enough to be followed by the muscles.

  6. Cannabidiol Rescues Acute Hepatic Toxicity and Seizure Induced by Cocaine

    Directory of Open Access Journals (Sweden)

    Luciano Rezende Vilela

    2015-01-01

    Full Text Available Cocaine is a commonly abused illicit drug that causes significant morbidity and mortality. The most severe and common complications are seizures, ischemic strokes, myocardial infarction, and acute liver injury. Here, we demonstrated that acute cocaine intoxication promoted seizure along with acute liver damage in mice, with intense inflammatory infiltrate. Considering the protective role of the endocannabinoid system against cell toxicity, we hypothesized that treatment with an anandamide hydrolysis inhibitor, URB597, or with a phytocannabinoid, cannabidiol (CBD, protects against cocaine toxicity. URB597 (1.0 mg/kg abolished cocaine-induced seizure, yet it did not protect against acute liver injury. Using confocal liver intravital microscopy, we observed that CBD (30 mg/kg reduced acute liver inflammation and damage induced by cocaine and prevented associated seizure. Additionally, we showed that previous liver damage induced by another hepatotoxic drug (acetaminophen increased seizure and lethality induced by cocaine intoxication, linking hepatotoxicity to seizure dynamics. These findings suggest that activation of cannabinoid system may have protective actions on both liver and brain induced by cocaine, minimizing inflammatory injury promoted by cocaine, supporting its further clinical application in the treatment of cocaine abuse.

  7. A low computation cost method for seizure prediction.

    Science.gov (United States)

    Zhang, Yanli; Zhou, Weidong; Yuan, Qi; Wu, Qi

    2014-10-01

    The dynamic changes of electroencephalograph (EEG) signals in the period prior to epileptic seizures play a major role in the seizure prediction. This paper proposes a low computation seizure prediction algorithm that combines a fractal dimension with a machine learning algorithm. The presented seizure prediction algorithm extracts the Higuchi fractal dimension (HFD) of EEG signals as features to classify the patient's preictal or interictal state with Bayesian linear discriminant analysis (BLDA) as a classifier. The outputs of BLDA are smoothed by a Kalman filter for reducing possible sporadic and isolated false alarms and then the final prediction results are produced using a thresholding procedure. The algorithm was evaluated on the intracranial EEG recordings of 21 patients in the Freiburg EEG database. For seizure occurrence period of 30 min and 50 min, our algorithm obtained an average sensitivity of 86.95% and 89.33%, an average false prediction rate of 0.20/h, and an average prediction time of 24.47 min and 39.39 min, respectively. The results confirm that the changes of HFD can serve as a precursor of ictal activities and be used for distinguishing between interictal and preictal epochs. Both HFD and BLDA classifier have a low computational complexity. All of these make the proposed algorithm suitable for real-time seizure prediction.

  8. Data assimilation a mathematical introduction

    CERN Document Server

    Law, Kody; Zygalakis, Konstantinos

    2015-01-01

    This book provides a systematic treatment of the mathematical underpinnings of work in data assimilation, covering both theoretical and computational approaches. Specifically the authors develop a unified mathematical framework in which a Bayesian formulation of the problem provides the bedrock for the derivation, development and analysis of algorithms; the many examples used in the text, together with the algorithms which are introduced and discussed, are all illustrated by the MATLAB software detailed in the book and made freely available online. The book is organized into nine chapters: the first contains a brief introduction to the mathematical tools around which the material is organized; the next four are concerned with discrete time dynamical systems and discrete time data; the last four are concerned with continuous time dynamical systems and continuous time data and are organized analogously to the corresponding discrete time chapters. This book is aimed at mathematical researchers interested in a sy...

  9. FOCAL MOTOR SEIZURES WITH TYPICAL AUTOMATISMS (FOCAL AUTOMOTOR SEIZURES

    Directory of Open Access Journals (Sweden)

    M. B. Mironov

    2014-01-01

    Full Text Available The paper deals with the study of a group of patients with focal automotor seizures, by taking into consideration their nosological, anamnestic, clinical, electroencephalographic, and neuroimaging features.

  10. Evaluating Data Assimilation Algorithms

    CERN Document Server

    Law, K J H

    2011-01-01

    Data assimilation refers to methodologies for the incorporation of noisy observations of a physical system into an underlying model in order to infer the properties of the state of the system (and/or parameters). The model itself is typically subject to uncertainties, in the input data and in the physical laws themselves. This leads naturally to a Bayesian formulation in which the posterior probability distribution of the system state, given the observations, plays a central conceptual role. The aim of this paper is to use this Bayesian posterior probability distribution as a gold standard against which to evaluate various commonly used data assimilation algorithms. A key aspect of geophysical data assimilation is the high dimensionality of the computational model. With this in mind, yet with the goal of allowing an explicit and accurate computation of the posterior distribution in order to facilitate our evaluation, we study the 2D Navier-Stokes equations in a periodic geometry. We compute the posterior prob...

  11. Impact of Assimilation on Heavy Rainfall Simulations Using WRF Model: Sensitivity of Assimilation Results to Background Error Statistics

    Science.gov (United States)

    Rakesh, V.; Kantharao, B.

    2017-03-01

    Data assimilation is considered as one of the effective tools for improving forecast skill of mesoscale models. However, for optimum utilization and effective assimilation of observations, many factors need to be taken into account while designing data assimilation methodology. One of the critical components that determines the amount and propagation observation information into the analysis, is model background error statistics (BES). The objective of this study is to quantify how BES in data assimilation impacts on simulation of heavy rainfall events over a southern state in India, Karnataka. Simulations of 40 heavy rainfall events were carried out using Weather Research and Forecasting Model with and without data assimilation. The assimilation experiments were conducted using global and regional BES while the experiment with no assimilation was used as the baseline for assessing the impact of data assimilation. The simulated rainfall is verified against high-resolution rain-gage observations over Karnataka. Statistical evaluation using several accuracy and skill measures shows that data assimilation has improved the heavy rainfall simulation. Our results showed that the experiment using regional BES outperformed the one which used global BES. Critical thermo-dynamic variables conducive for heavy rainfall like convective available potential energy simulated using regional BES is more realistic compared to global BES. It is pointed out that these results have important practical implications in design of forecast platforms while decision-making during extreme weather events

  12. Optimality in Data Assimilation

    Science.gov (United States)

    Nearing, Grey; Yatheendradas, Soni

    2016-04-01

    It costs a lot more to develop and launch an earth-observing satellite than it does to build a data assimilation system. As such, we propose that it is important to understand the efficiency of our assimilation algorithms at extracting information from remote sensing retrievals. To address this, we propose that it is necessary to adopt completely general definition of "optimality" that explicitly acknowledges all differences between the parametric constraints of our assimilation algorithm (e.g., Gaussianity, partial linearity, Markovian updates) and the true nature of the environmetnal system and observing system. In fact, it is not only possible, but incredibly straightforward, to measure the optimality (in this more general sense) of any data assimilation algorithm as applied to any intended model or natural system. We measure the information content of remote sensing data conditional on the fact that we are already running a model and then measure the actual information extracted by data assimilation. The ratio of the two is an efficiency metric, and optimality is defined as occurring when the data assimilation algorithm is perfectly efficient at extracting information from the retrievals. We measure the information content of the remote sensing data in a way that, unlike triple collocation, does not rely on any a priori presumed relationship (e.g., linear) between the retrieval and the ground truth, however, like triple-collocation, is insensitive to the spatial mismatch between point-based measurements and grid-scale retrievals. This theory and method is therefore suitable for use with both dense and sparse validation networks. Additionally, the method we propose is *constructive* in the sense that it provides guidance on how to improve data assimilation systems. All data assimilation strategies can be reduced to approximations of Bayes' law, and we measure the fractions of total information loss that are due to individual assumptions or approximations in the

  13. Reading-Induced Absence Seizures

    OpenAIRE

    J Gordon Millichap

    1995-01-01

    A 12-year-old girl with a 2-year history of absence seizures induced by reading and diagnosed by video EEG is reported from The University of Texas Southwestern Medical Center, Dallas, and Riyadh Armed Forces Hospital, Saudi Arabia.

  14. Galactosemia and phantom absence seizures

    Directory of Open Access Journals (Sweden)

    Zeynep Aydin-Özemir

    2014-01-01

    Full Text Available Generalized and focal seizures can rarely be seen in galactosemia patients, but absence seizures were not reported previously. An 18-year-old male was diagnosed as galactosemia at the age of 8 months. No family history of epilepsy was present. His absence seizures realized at the age of 9 years. Generalized 3-4 Hz spike-wave discharges were identified in his electroencephalography. Homozygous mutation at exon 6 c. 563A > G was identified. The electroencephalogram of his sibling was unremarkable. Our aim was to present the long-term follow-up of a patient diagnosed with galactosemia, who had phantom absence seizures and typical 3-4 Hz spike-wave discharges in his electroencephalogram to draw attention to this rare association.

  15. On Assimilation of English Sounds

    Institute of Scientific and Technical Information of China (English)

    刘恩华

    2015-01-01

    This paper makes a careful study of assimilation in English speaking, meanwhile a systematic knowledge of assimilation wil be helpful for the pronunciations of English learners, facilitate English fluency and improve listening comprehension.

  16. Treatment of febrile seizures with intermittent clobazam

    OpenAIRE

    1997-01-01

    Fifty children, 24 female and 26 male, with ages varying from 6 to 72 months (mean=23.7 m.) that experienced at least one febrile seizure (FS) entered a prospective study of intermittent therapy with clobazam. Cases with severe neurological abnormalities, progressive neurological disease, afebrile seizures, symptomatic seizures of other nature, or seizures during a central nervous system infection were excluded. Seizures were of the simple type in 25 patients, complex in 20 and unclassified i...

  17. Management Of Post Stroke Seizures

    Directory of Open Access Journals (Sweden)

    Kavian Ghandehari

    2017-02-01

    Full Text Available The incidence of seizures in relation to stroke is 8.9%, with a frequency of 10.6 and 8.6% in haemorrhagic and ischaemic stroke, respectively. In subarachnoid haemorrhage the incidence is 8.5%. Due to the fact that infarcts are significantly more frequent than haemorrhages, seizures are mainly related to occlusive vascular disease of the brain. The general view is to consider stroke-related seizures as harmless complications in the course of a prolonged vascular disease involving the heart and brain. Seizures can be classified as those of early and those of late onset in a paradigm comparable to post-traumatic epilepsy, with an arbitrary dividing point of two weeks after the event. Most early-onset seizures occur during the first day after the stroke. Late-onset seizures occur three times more often than early-onset ones. A first late-onset epileptic event is most likely to take place between six months and two years after the stroke. However, up to 28% of patients develop their first seizure several years later. Simple partial seizures, with or without secondary generalisation, account for about 50% of total seizures, while complex partial spells, with or without secondary generalisation, and primary generalised tonic–clonic insults account for approximately 25% each. Status epilepticus occurs in 12% of stroke patients, but the recurrence rate after an initial status epilepticus is not higher than after a single seizure. Inhibitory seizures, mimicking transient ischaemic attacks, are observed in 7.1% of cases. The only clinical predictor of late-onset seizures is the initial presentation of partial anterior circulation syndrome due to a territorial infarct. Patients with total anterior circulation syndrome have less chance of developing epileptic spells, not only due to their shorter life expectancy but also due to the fact that the large infarcts are sharply demarcated in these patients. The optimal timing and type of antiepileptic drug

  18. Displacement data assimilation

    Science.gov (United States)

    Rosenthal, W. Steven; Venkataramani, Shankar; Mariano, Arthur J.; Restrepo, Juan M.

    2017-02-01

    We show that modifying a Bayesian data assimilation scheme by incorporating kinematically-consistent displacement corrections produces a scheme that is demonstrably better at estimating partially observed state vectors in a setting where feature information is important. While the displacement transformation is generic, here we implement it within an ensemble Kalman Filter framework and demonstrate its effectiveness in tracking stochastically perturbed vortices.

  19. SST data assimilation experiments using an adaptive variational method

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    An adaptive variational data assimilation method is proposed by Zhu and Kamachi[1]. This method can adaptively adjust the model state without knowing explicitly the model error covariance matrix. The method enables very flexible ways to form some reduced order problems. A proper reduced order problem not only reduces computational burden but also leads to corrections that are more consistent with the model dynamics that trends to produce better forecast. These features make the adaptive variational method a good candidate for SST data assimilation because the model error of an ocean model is usually difficult to estimate. We applied this method to an SST data assimilation problem using the LOTUS data sets and an ocean mixed layer model (Mellor-Yamada level 2.5). Results of assimilation experiments showed good skill of improvement subsurface temperatures by assimilating surface observation alone.

  20. A variational formulation for translation and assimilation of coherent structures

    Directory of Open Access Journals (Sweden)

    M. Plu

    2013-10-01

    Full Text Available The assimilation of observations from teledetected images in geophysical models requires one to develop algorithms that would account for the existence of coherent structures. In the context of variational data assimilation, a method is proposed to allow the background to be translated so as to fit structure positions deduced from images. Translation occurs as a first step before assimilating all the observations using a classical assimilation procedure with specific covariances for the translated background. A simple validation is proposed using a dynamical system based on the one-dimensional complex Ginzburg–Landau equation in a regime prone to phase and amplitude errors. Assimilation of observations after background translation leads to better scores and a better representation of extremas than the method without translation.

  1. A primer for data assimilation with ecological models using Markov Chain Monte Carlo (MCMC).

    Science.gov (United States)

    Zobitz, J M; Desai, A R; Moore, D J P; Chadwick, M A

    2011-11-01

    Data assimilation, or the fusion of a mathematical model with ecological data, is rapidly expanding knowledge of ecological systems across multiple spatial and temporal scales. As the amount of ecological data available to a broader audience increases, quantitative proficiency with data assimilation tools and techniques will be an essential skill for ecological analysis in this data-rich era. We provide a data assimilation primer for the novice user by (1) reviewing data assimilation terminology and methodology, (2) showcasing a variety of data assimilation studies across the ecological, environmental, and atmospheric sciences with the aim of gaining an understanding of potential applications of data assimilation, and (3) applying data assimilation in specific ecological examples to determine the components of net ecosystem carbon uptake in a forest and also the population dynamics of the mayfly (Hexagenia limbata, Serville). The review and examples are then used to provide guiding principles to newly proficient data assimilation practitioners.

  2. [Martin Luther's seizure disorder].

    Science.gov (United States)

    Feldmann, H

    1989-01-01

    Martin Luther's diseases are well documented, because he used to discuss them freely in his letters. There is also a wealth of evidence through reports by his friends. Most of his diseases were common and well known to the contemporary physicians, who accordingly interpreted them correctly: bladder stones, chronic constipation, hemorrhoids. Luther's death obviously was due to a coronary thrombosis. During the last 19 years of his life, in addition to these "natural diseases", Luther also suffered from recurring attacks of a peculiar symptomatology. Luther himself and his friends considered these seizures to be no "natural disease", but Satan punching his flesh, and he compared them to St. Paul's disease (2. Cor. 12). The first of these attacks occurred on July 6, 1527, when Luther was 43 years of age. It began with a roaring tinnitus in his left ear, which increased dramatically and seemed to occupy the left half of his head. Then a state of sickness and collapse followed, however, consciousness was retained throughout the whole period. After a night's rest all the symptoms had subsided, except the tinnitus, which, from that day on, continued for all the following years in varying intensity. Similar attacks with increase of the tinnitus and vertigo as the leading symptoms, seized Luther at irregular intervals and distressed him extremely. Former investigators of Luther's diseases interpreted these attacks as manifestations of a psychiatric disorder and a chronic inflammatory disease of the middle ear. The present detailed study reveals that it was a typical case of Menière's disease of the left ear manifesting itself more than 330 years before Menière's classical observation.

  3. Evaluation of first nonfebrile seizures.

    Science.gov (United States)

    Wilden, Jessica A; Cohen-Gadol, Aaron A

    2012-08-15

    Nonfebrile seizures may indicate underlying disease or epilepsy. The patient history can often distinguish epileptic seizures from nonepileptic disorders by identifying the events directly preceding the convulsion, associated conditions, and details of the seizure, including triggers, length, and type of movements. Laboratory testing, lumbar puncture, and neuroimaging may be indicated depending on the presentation, suspected etiology, and patient's age. Electroencephalography should be performed 24 to 48 hours after a first seizure because of its substantial yield and ability to predict recurrence. Neuroimaging is recommended for adults, infants, and children who have cognitive or motor developmental delay or a focal seizure. Neuroimaging may be scheduled on an outpatient basis for patients with stable vital signs who are awake and have returned to neurologic baseline. Emergent neuroimaging should be performed in patients with persistent decreased mental status or a new focal neurologic abnormality. Although magnetic resonance imaging is generally preferred to head computed tomography because of its greater sensitivity for intracranial pathology, computed tomography should be performed if intracranial bleeding is suspected because of recent head trauma, coagulopathy, or severe headache. Treatment with an antiepileptic drug after a first seizure does not prevent epilepsy in the long term, but it decreases the short-term likelihood of a second seizure. Adults with an unremarkable neurologic examination, no comorbidities, and no known structural brain disease who have returned to neurologic baseline do not need to be started on antiepileptic therapy. Treatment decisions should weigh the benefit of decreased short-term risk of recurrence against the potential adverse effects of antiepileptic drugs.

  4. Seizures and Meperidine: Overstated and Underutilized.

    Science.gov (United States)

    Schlick, Konrad H; Hemmen, Thomas M; Lyden, Patrick D

    2015-12-01

    Meperidine is used for pain control and treatment of shivering. Concerns about neurotoxicity, particularly seizures, have led to efforts limiting meperidine use. We reviewed the body of evidence linking meperidine to seizures. We searched PubMed for the terms meperidine, normeperidine, pethidine, and norpethidine; each was combined with the terms: seizure, epilepsy, epileptogenic, toxicity, overdose, seizure threshold, and convulsion. Articles were assessed for relevance. Semiologies were reviewed to ascertain seizure likelihood. Our search yielded 351 articles, of which 66 were relevant. Of these, 33 had primary clinical data on meperidine-associated seizures, comprising 50 patients. Twenty events were deemed likely to be seizures, 26 indeterminate, and 4 unlikely. Most studies were case reports. Confounding comorbidities were frequent. The evidence base for meperidine-associated seizures in man is scant. Seizure risk associated with meperidine appears to be overstated. The utility of meperidine should continue to be explored, especially for therapeutic hypothermia.

  5. Multiscale Aspects of Generation of High-Gamma Activity during Seizures in Human Neocortex123

    Science.gov (United States)

    Marcuccilli, Charles J.; Ben-Mabrouk, Faiza; Lew, Sean M.; Goodman, Robert R.; McKhann, Guy M.; Frim, David M.; Kohrman, Michael H.; Schevon, Catherine A.; van Drongelen, Wim

    2016-01-01

    High-gamma (HG; 80-150 Hz) activity in macroscopic clinical records is considered a marker for critical brain regions involved in seizure initiation; it is correlated with pathological multiunit firing during neocortical seizures in the seizure core, an area identified by correlated multiunit spiking and low frequency seizure activity. However, the effects of the spatiotemporal dynamics of seizure on HG power generation are not well understood. Here, we studied HG generation and propagation, using a three-step, multiscale signal analysis and modeling approach. First, we analyzed concurrent neuronal and microscopic network HG activity in neocortical slices from seven intractable epilepsy patients. We found HG activity in these networks, especially when neurons displayed paroxysmal depolarization shifts and network activity was highly synchronized. Second, we examined HG activity acquired with microelectrode arrays recorded during human seizures (n = 8). We confirmed the presence of synchronized HG power across microelectrode records and the macroscale, both specifically associated with the core region of the seizure. Third, we used volume conduction-based modeling to relate HG activity and network synchrony at different network scales. We showed that local HG oscillations require high levels of synchrony to cross scales, and that this requirement is met at the microscopic scale, but not within macroscopic networks. Instead, we present evidence that HG power at the macroscale may result from harmonics of ongoing seizure activity. Ictal HG power marks the seizure core, but the generating mechanism can differ across spatial scales. PMID:27257623

  6. Synchronization analysis of voltage-sensitive dye imaging during focal seizures in the rat neocortex

    Science.gov (United States)

    Takeshita, Daisuke; Bahar, Sonya

    2011-12-01

    Seizures are often assumed to result from an excess of synchronized neural activity. However, various recent studies have suggested that this is not necessarily the case. We investigate synchronization during focal neocortical seizures induced by injection of 4-aminopyridine (4AP) in the rat neocortex in vivo. Neocortical activity is monitored by field potential recording and by the fluorescence of the voltage-sensitive dye RH-1691. After removal of artifacts, the voltage-sensitive dye (VSD) signal is analyzed using the nonlinear dynamics-based technique of stochastic phase synchronization in order to determine the degree of synchronization within the neocortex during the development and spread of each seizure event. Results show a large, statistically significant increase in synchronization during seizure activity. Synchrony is typically greater between closer pixel pairs during a seizure event; the entire seizure region is synchronized almost exactly in phase. This study represents, to our knowledge, the first application of synchronization analysis methods to mammalian VSD imaging in vivo. Our observations indicate a clear increase in synchronization in this model of focal neocortical seizures across a large area of the neocortex; a sharp increase in synchronization during seizure events was observed in all 37 seizures imaged. The results are consistent with a recent computational study which simulates the effect of 4AP in a neocortical neuron model.

  7. A novel genetic programming approach for epileptic seizure detection.

    Science.gov (United States)

    Bhardwaj, Arpit; Tiwari, Aruna; Krishna, Ramesh; Varma, Vishaal

    2016-02-01

    The human brain is a delicate mix of neurons (brain cells), electrical impulses and chemicals, known as neurotransmitters. Any damage has the potential to disrupt the workings of the brain and cause seizures. These epileptic seizures are the manifestations of epilepsy. The electroencephalograph (EEG) signals register average neuronal activity from the cerebral cortex and label changes in activity over large areas. A detailed analysis of these electroencephalograph (EEG) signals provides valuable insights into the mechanisms instigating epileptic disorders. Moreover, the detection of interictal spikes and epileptic seizures in an EEG signal plays an important role in the diagnosis of epilepsy. Automatic seizure detection methods are required, as these epileptic seizures are volatile and unpredictable. This paper deals with an automated detection of epileptic seizures in EEG signals using empirical mode decomposition (EMD) for feature extraction and proposes a novel genetic programming (GP) approach for classifying the EEG signals. Improvements in the standard GP approach are made using a Constructive Genetic Programming (CGP) in which constructive crossover and constructive subtree mutation operators are introduced. A hill climbing search is integrated in crossover and mutation operators to remove the destructive nature of these operators. A new concept of selecting the Globally Prime offspring is also presented to select the best fitness offspring generated during crossover. To decrease the time complexity of GP, a new dynamic fitness value computation (DFVC) is employed to increase the computational speed. We conducted five different sets of experiments to evaluate the performance of the proposed model in the classification of different mixtures of normal, interictal and ictal signals, and the accuracies achieved are outstandingly high. The experimental results are compared with the existing methods on same datasets, and these results affirm the potential use of

  8. Seizures in the critically ill.

    Science.gov (United States)

    Ch'ang, J; Claassen, J

    2017-01-01

    Critically ill patients with seizures are either admitted to the intensive care unit because of uncontrolled seizures requiring aggressive treatment or are admitted for other reasons and develop seizures secondarily. These patients may have multiorgan failure and severe metabolic and electrolyte disarrangements, and may require complex medication regimens and interventions. Seizures can be seen as a result of an acute systemic illness, a primary neurologic pathology, or a medication side-effect and can present in a wide array of symptoms from convulsive activity, subtle twitching, to lethargy. In this population, untreated isolated seizures can quickly escalate to generalized convulsive status epilepticus or, more frequently, nonconvulsive status epileptics, which is associated with a high morbidity and mortality. Status epilepticus (SE) arises from a failure of inhibitory mechanisms and an enhancement of excitatory pathways causing permanent neuronal injury and other systemic sequelae. Carrying a high 30-day mortality rate, SE can be very difficult to treat in this complex setting, and a portion of these patients will become refractory, requiring narcotics and anesthetic medications. The most significant factor in successfully treating status epilepticus is initiating antiepileptic drugs as soon as possible, thus attentiveness and recognition of this disease are critical.

  9. Seizures after liver transplantation: a clinicopathologic study.

    Science.gov (United States)

    Estol, C J; Lopez, O; Brenner, R P; Martinez, A J

    1989-10-01

    We reviewed the clinical and neuropathologic findings in 21 patients who had seizures after orthotopic liver transplants. Tonic-clonic seizures were the most common seizure type. Six patients developed status epilepticus. In 9 patients, seizures occurred within 1 week following transplantation. We found CNS lesions that were probably responsible for the occurrence of seizures in most patients; some had more than 1 finding. Neuropathologic examination revealed ischemic or hemorrhagic strokes in 18 patients, central pontine myelinolysis in 5, and CNS infections in 5. Multiple metabolic abnormalities were a contributing factor to the onset of seizures in some patients.

  10. Explosive Blast Neuropathology and Seizures

    Directory of Open Access Journals (Sweden)

    S. Krisztian eKovacs

    2014-04-01

    Full Text Available Traumatic brain injury (TBI due to explosive blast exposure is a leading combat casualty. It is also implicated as a key contributor to war related mental health diseases. A clinically important consequence of all types of TBI is a high risk for development of seizures and epilepsy. Seizures have been reported in patients who have suffered blast injuries in the Global War on Terror but the exact prevalence is unknown. The occurrence of seizures supports the contention that explosive blast leads to both cellular and structural brain pathology. Unfortunately, the exact mechanism by which explosions cause brain injury is unclear, which complicates development of meaningful therapies and mitigation strategies. To help improve understanding, detailed neuropathological analysis is needed. For this, histopathological techniques are extremely valuable and indispensable. In the following we will review the pathological results, including those from immunohistochemical and special staining approaches, from recent preclinical explosive blast studies.

  11. Global Assimilation of Ionospheric Measurements (GAIM)

    Science.gov (United States)

    Schunk, R. W.; Scherliess, L.; Sojka, J. J.; Thompson, D. C.; Anderson, D. N.; Codrescu, M.; Minter, C.; Fuller-Rowell, T. J.; Heelis, R. A.; Hairston, M.; Howe, B. M.

    2001-12-01

    The ionosphere is a highly dynamic medium that can vary significantly from day to day and from hour to hour at a given location, and these variations can have detrimental effects on military and civilian systems. In an effort to minimize or circumvent the detrimental effects, a physics-based data assimilation model of the ionosphere and neutral atmosphere is under development with funding from the DoD MURI program. Two university consortia are involved, with USU and USC as the lead institutions. When completed, the GAIM (Global Assimilation of Ionospheric Measurements) model will provide specifications and forecasts on a spatial grid that can be global, regional, or local (50 km x 50 km). GAIM will use a physics-based ionosphere-plasmasphere model and a Kalman filter as a basis for assimilating a diverse set of real-time (or near real-time) measurements. Some of the data to be assimilated include in situ density measurements from satellites, ionosonde electron density profiles, occultation data, ground-based GPS TECs, TECs between ground stations and LEO satellites with radio beacons, and line-of-sight UV emissions from selected satellites. The resulting specifications and forecasts will be in the form of 3-dimensional electron density distributions from 90 km to geosynchronous altitude (35,000 km). An initial form of GAIM already exists and recent results from the USU consortium will be presented.

  12. Ensemble data assimilation in the Whole Atmosphere Community Climate Model

    Science.gov (United States)

    Pedatella, N. M.; Raeder, K.; Anderson, J. L.; Liu, H.-L.

    2014-08-01

    We present results pertaining to the assimilation of real lower, middle, and upper atmosphere observations in the Whole Atmosphere Community Climate Model (WACCM) using the Data Assimilation Research Testbed (DART) ensemble adjustment Kalman filter. The ability to assimilate lower atmosphere observations of aircraft and radiosonde temperature and winds, satellite drift winds, and Constellation Observing System for Meteorology, Ionosphere, and Climate refractivity along with middle/upper atmosphere temperature observations from SABER and Aura MLS is demonstrated. The WACCM+DART data assimilation system is shown to be able to reproduce the salient features, and variability, of the troposphere present in the National Centers for Environmental Prediction/National Center for Atmospheric Research Re-Analysis. In the mesosphere, the fit of WACCM+DART to observations is found to be slightly worse when only lower atmosphere observations are assimilated compared to a control experiment that is reflective of the model climatological variability. This differs from previous results which found that assimilation of lower atmosphere observations improves the fit to mesospheric observations. This discrepancy is attributed to the fact that due to the gravity wave drag parameterizations, the model climatology differs significantly from the observations in the mesosphere, and this is not corrected by the assimilation of lower atmosphere observations. The fit of WACCM+DART to mesospheric observations is, however, significantly improved compared to the control experiment when middle/upper atmosphere observations are assimilated. We find that assimilating SABER observations reduces the root-mean-square error and bias of WACCM+DART relative to the independent Aura MLS observations by ˜50%, demonstrating that assimilation of middle/upper atmosphere observations is essential for accurate specification of the mesosphere and lower thermosphere region in WACCM+DART. Last, we demonstrate that

  13. Snow Radiance Assimilation Studies

    Science.gov (United States)

    Kim, E. J.; Durand, M. T.; Toure, A.; Margulis, S. A.; Goita, K.; Royer, A.; Lu, H.

    2009-12-01

    Passive microwave-based retrievals of terrestrial snow parameters from satellite observations form a 30-year global record which will continue for the forseeable future. So far, these snow retrievals have been generated primarily by regression-based empirical “inversion” methods based on snapshots in time, and are limited to footprints around 25 km in diameter. Assimilation of microwave radiances into physical land surface models may be used to create a retrieval framework that is inherently self-consistent with respect to model physics as well as a more physically-based approach vs. legacy retrieval/inversion methods. This radiance assimilation approach has been used for years for atmospheric parameters by the operational weather forecasting community with great success, and represents one motivation for our work. A radiance assimilation scheme for snow requires a snowpack land surface model (LSM) coupled to a radiative transfer model (RTM). In previous local-scale studies, Durand, Kim, & Margulis (2008) explored the requirements on LSM model fidelity (i.e., snowpack state information) required in order for the RTM to produce brightness temperatures suitable for radiance assimilation purposes at a local scale, using the well-known Microwave Emission Model for Layered Snowpacks (MEMLS) as the RTM and a combination of Simple SIB (SSiB) and Snow Atmosphere (SAST) as the LSM. They also demonstrated improvement of simulated snow depth through the use of an ensemble Kalman filter scheme at this local scale (2009). This modeling framework reflects another motivation—namely, possibilities for downscaling. Our focus at this stage has been at the local scale where high-quality ground truth data is available in order to evaluate radiance assimilation under a “best case scenario.” The quantitative results then form a benchmark for future assessment of effects such as sparse forcing data, upscaling/downscaling, forest attenuation, and model details. Field data from

  14. Febrile Seizures: Controversy and Consensus

    Science.gov (United States)

    Doiron, Omer A.

    1983-01-01

    Although febrile convulsions are a relatively common complaint, the approach to their management is far from uniform and highly controversial. This article reviews the consensus statement on febrile convulsions arrived at by the Consensus Development Conference held in 1980 by the National Institutes of Health, together with other literature of interest to family physicians. Guidelines are given for the assessment, diagnosis and emergency treatment of febrile seizures. Epilepsy and atypical febrile convulsions are distinguished from simple febrile seizures. Prognosis, prevention, and the importance of counselling parents are discussed, as well as the controversial issue of prophylactic treatment. PMID:21286583

  15. Utility of different seizure induction protocols in psychogenic nonepileptic seizures.

    Science.gov (United States)

    Goyal, Gourav; Kalita, Jayantee; Misra, Usha K

    2014-08-01

    Psychogenic non epileptic seizure (PNES) can be induced by several induction tests but their relative usefulness has not been evaluated. In this study, we report the sensitivity and specificity of various induction tests in the diagnosis of PNES and assess their discomfort level. The induction tests were: (a) compression of temple region (CTR), (b) verbal suggestion (VS), (c) tuning fork application (TFA), (d) moist swab application (MSA), (e) torch light stimulation (TLS) and (f) saline injection (SI). Up to 3 trials were done for each test except for normal saline injection which was given once. For comparison of these tests, patients with epileptic seizures were included as controls. The time to precipitate PNES was recorded and patients' discomfort levels were noted on a 0-10 scale. Video EEG was recorded in the PNES patients. 140 patients with PNES and 50 controls with epileptic seizures were included. The diagnostic yield of CTR was 65.7%, TFA 61.4%, MSA 60.7%, SI 55.6%, VS 54.3% and TLS 40.7%. These tests did not induce seizures in the controls. All these tests had 100% specificity and 100% positive predictive value in the diagnosis of PNES. The maximum discomfort was reported with SI and minimum with MSA. The similarity of efficacy and discomfort with CTR and TFA appear to be the most optimal induction techniques when compared with VS, AMS, TLS, and SI.

  16. Epileptic Seizures from Abnormal Networks: Why Some Seizures Defy Predictability

    Science.gov (United States)

    2011-12-12

    are provoked (e.g. medications and alcohol) and less than half of these patients have recurrent seizures. The life- time cumulative risk of developing... microwire and clinical macroelectrode recordings. Brain 131 (Pt 4), 928—937. Worrell, G.A., Parish, L., Cranstoun, S.D., Jonas, R., Bal- tuch, G., Litt

  17. Pyridoxine-dependent seizures and microcephaly.

    Science.gov (United States)

    Tan, Hüseyin; Kardaş, Fatih; Büyükavci, Mustafa; Karakelleoğlu, Cahit

    2004-09-01

    Pyridoxine dependency is a rare autosomal-recessive disorder causing intractable seizures in neonates and infants. This case report describes an infant with pyridoxine-dependent seizures with microcephaly and discusses a probable pathogenetic mechanism of microcephaly in this condition.

  18. Temperature, age, and recurrence of febrile seizure

    NARCIS (Netherlands)

    M. van Stuijvenberg (Margriet); E.W. Steyerberg (Ewout); G. Derksen-Lubsen (Gerarda); H.A. Moll (Henriëtte)

    1998-01-01

    textabstractOBJECTIVE: Prediction of a recurrent febrile seizure during subsequent episodes of fever. DESIGN: Study of the data of the temperatures, seizure recurrences, and baseline patient characteristics that were collected at a randomized placebo controlled trial of ibuprofen s

  19. The Epilepsies and Seizures: Hope Through Research

    Science.gov (United States)

    ... were sometimes referred to as grand mal seizures. vagus nerve stimulator – a surgically implanted device that sends short ... of electrical energy to the brain via the vagus nerve and helps some individuals reduce their seizure activity. ...

  20. Sensitivity of simulated terrestrial carbon assimilation and canopy transpiration to different stomatal conductance and carbon assimilation schemes

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Haishan [Nanjing University of Information Science and Technology, Key Laboratory of Meteorological Disaster of Ministry of Education, Nanjing (China); Georgia Institute of Technology, School of Earth and Atmospheric Sciences, Atlanta, GA (United States); Dickinson, Robert E. [Georgia Institute of Technology, School of Earth and Atmospheric Sciences, Atlanta, GA (United States); The University of Texas at Austin, Department of Geological Sciences, Austin, TX (United States); Dai, Yongjiu [Beijing Normal University, State Key Laboratory of Earth Surface Processes and Resource Ecology, School of Global Change and Earth System Science, Beijing (China); Zhou, Liming [Georgia Institute of Technology, School of Earth and Atmospheric Sciences, Atlanta, GA (United States)

    2011-03-15

    Accurate simulations of terrestrial carbon assimilation and canopy transpiration are needed for both climate modeling and vegetation dynamics. Coupled stomatal conductance and carbon assimilation (A - g{sub s}) models have been widely used as part of land surface parameterizations in climate models to describe the biogeophysical and biogeochemical roles of terrestrial vegetation. Differences in various A - g{sub s} schemes produce substantial differences in the estimation of carbon assimilation and canopy transpiration, as well as in other land-atmosphere fluxes. The terrestrial carbon assimilation and canopy transpiration simulated by two different representative A - g{sub s} schemes, a simple A-g{sub s} scheme adopted from the treatments of the NCAR model (Scheme I) and a two-big-leaf A - g{sub s} scheme newly developed by Dai et al. (J Clim 17:2281-2299, 2004) (Scheme II), are compared via some sensitivity experiments to investigate impacts of different A - g{sub s} schemes on the simulations. Major differences are found in the estimate of canopy carbon assimilation rate, canopy conductance and canopy transpiration between the two schemes, primarily due to differences in (a) functional forms used to estimate parameters for carbon assimilation sub-models, (b) co-limitation methods used to estimate carbon assimilation rate from the three limiting rates, and (c) leaf-to-canopy scaling schemes. On the whole, the differences in the scaling approach are the largest contributor to the simulation discrepancies, but the different methods of co-limitation of assimilation rate also impact the results. Except for a few biomes, the residual effects caused by the different parameter estimations in assimilation sub-models are relatively small. It is also noted that the two-leaf temperature scheme produces distinctly different sunlit and shaded leaf temperatures but has negligible impacts on the simulation of the carbon assimilation. (orig.)

  1. The Life Time Prevalence of Childhood Seizure

    OpenAIRE

    P AlizadehTaheri; Naseri, M; M Lahooti; Sadeghi, M

    2009-01-01

    "nBackground: Seizure is the most common pediatric neurologic disorder. Epidemiological studies of childhood epilepsy are of importance to compare incidence and prevalence rates, age distribution, inheritance, seizure types, epilepsy syn­dromes and treatment strategies. Since there is little information about prevalence of childhood seizure in Iran, this study was aimed to determine the life time prevalence of childhood seizure and some of its determining factors in Tehran, Iran....

  2. Neonatal Seizures. Advances in Mechanisms and Management.

    OpenAIRE

    2014-01-01

    Seizures occur in approximately 1–5 per 1,000 live births, and are among the most common neurologic conditions managed by a neonatal neurocritical care service. There are several, age-specific factors that are particular to the developing brain, which influence excitability and seizure generation, response to medications, and impact of seizures on brain structure and function. Neonatal seizures are often associated with serious underlying brain injury such as hypoxia-ischemia, stroke or hemor...

  3. Channel selection for automatic seizure detection

    DEFF Research Database (Denmark)

    Duun-Henriksen, Jonas; Kjaer, Troels Wesenberg; Madsen, Rasmus Elsborg

    2012-01-01

    of an automatic channel selection method. The characteristics of the seizures are extracted by the use of a wavelet analysis and classified by a support vector machine. The best channel selection method is based upon maximum variance during the seizure. Results: Using only three channels, a seizure detection...

  4. Treatment of seizures in multiple sclerosis

    NARCIS (Netherlands)

    Koch, Marcus W.; Polman, Susanne K. L.; Uyttenboogaart, Maarten; De Keyser, Jacques

    2009-01-01

    Background Epileptic seizures occur in only a minority of patients with multiple sclerosis (MS), but can have serious consequences. The available literature suggests an association of seizures in MS with cortical and subcortical demyelinating lesions, which suggest that seizures in MS are probably m

  5. Dynamical Downscaling of Climate Change Impacts on Wind Energy Resources in the Contiguous United States by Using a Limited-Area Model with Scale-Selective Data Assimilation

    Directory of Open Access Journals (Sweden)

    Bin Liu

    2014-01-01

    Full Text Available By using a limited-area model (LAM in combination with the scale-selective data assimilation (SSDA approach, wind energy resources in the contiguous United States (CONUS were downscaled from IPCC CCSM3 global model projections for both current and future climate conditions. An assessment of climate change impacts on wind energy resources in the CONUS region was then conducted. Based on the downscaling results, when projecting into future climate under IPCC’s A1B scenario, the average annual wind speed experiences an overall shift across the CONUS region. From the current climate to the 2040s, the average annual wind speed is expected to increase from 0.1 to 0.2 m s−1 over the Great Plains, Northern Great Lakes Region, and Southwestern United States located southwest of the Rocky Mountains. When projecting into the 2090s from current climate, there is an overall increase in the Great Plains Region and Southwestern United States located southwest of the Rockies with a mean wind speed increase between 0 and 0.1 m s−1, while, the Northern Great Lakes Region experiences an even greater increase from current climate to 2090s than over the first few decades with an increase of mean wind speed from 0.1 to 0.4 m s−1.

  6. Hippocampal Abnormalities and Seizure Recurrence

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2006-08-01

    Full Text Available Hippocampal volumetry and T2 relaxometry were performed on 84 consecutive patients (adolescents and adults with partial epilepsy submitted to antiepileptic drug (AED withdrawal after at least 2 years of seizure control, in a study at State University of Campinas-UNICAMP, Brazil.

  7. Integrated Data Assimilation Architecture Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Integrated Data Assimilation Architecture (IDAA) is a middleware architecture that facilitates the incorporation of heterogeneous sensing and control devices...

  8. Integrated Data Assimilation Architecture Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The Integrated Data Assimilation Architecture (IDAA) addresses the fundamental problem of command, control, and communications systems interoperability....

  9. Regional Ocean Data Assimilation

    KAUST Repository

    Edwards, Christopher A.

    2015-01-03

    This article reviews the past 15 years of developments in regional ocean data assimilation. A variety of scientific, management, and safety-related objectives motivate marine scientists to characterize many ocean environments, including coastal regions. As in weather prediction, the accurate representation of physical, chemical, and/or biological properties in the ocean is challenging. Models and observations alone provide imperfect representations of the ocean state, but together they can offer improved estimates. Variational and sequential methods are among the most widely used in regional ocean systems, and there have been exciting recent advances in ensemble and four-dimensional variational approaches. These techniques are increasingly being tested and adapted for biogeochemical applications.

  10. Regional ocean data assimilation.

    Science.gov (United States)

    Edwards, Christopher A; Moore, Andrew M; Hoteit, Ibrahim; Cornuelle, Bruce D

    2015-01-01

    This article reviews the past 15 years of developments in regional ocean data assimilation. A variety of scientific, management, and safety-related objectives motivate marine scientists to characterize many ocean environments, including coastal regions. As in weather prediction, the accurate representation of physical, chemical, and/or biological properties in the ocean is challenging. Models and observations alone provide imperfect representations of the ocean state, but together they can offer improved estimates. Variational and sequential methods are among the most widely used in regional ocean systems, and there have been exciting recent advances in ensemble and four-dimensional variational approaches. These techniques are increasingly being tested and adapted for biogeochemical applications.

  11. Immigration, assimilation and growth.

    Science.gov (United States)

    Durkin, J T

    1998-01-01

    "This paper analyzes the welfare effects of immigration and its subsequent effect on ethnic diversity in a model featuring human capital spillovers which depend on the degree of ethnic heterogeneity, variation rates of time preference across individuals and endogenous levels of immigration and assimilation. In the model, an increase in ethnic diversity reduces the spillovers effect for the majority. Nonetheless, immigration can be welfare improving for the majority ethnic group even if it increases the degree of diversity as long as it raises the average human capital level and/or growth rate by increasing the proportion of people with low rates of time preference."

  12. Are Epileptic Seizures Quakes of the Brain? An Approach by Means of Nonextensive Tsallis Statistics

    CERN Document Server

    Eftaxias, K; Athanasopoulou, L; Kalimeri, M; Potirakis, S M; Balasis, G

    2011-01-01

    The field of study of complex systems holds that the dynamics of complex systems are founded on universal principles that may used to describe a great variety of scientific and technological approaches of different types of natural, artificial, and social systems. Authors have suggested that earthquake dynamics and neurodynamics can be analyzed within similar mathematical frameworks, a claim further supported by recent evidence. The purpose of this paper is to suggest a shift in emphasis from the large to the small in the search for a dynamical analogy between seizure and earthquake. Our analyses focus on a single epileptic seizure generation and the activation of a single fault (earthquake) and not on the statistics of sequences of different seizures and earthquakes. A central property of the epileptic seizure / earthquake generation is the occurrence of coherent large-scale collective behaviour with very rich structure, resulting from repeated nonlinear interactions among the constituents of the system, res...

  13. Probabilistic forecasting and Bayesian data assimilation

    CERN Document Server

    Reich, Sebastian

    2015-01-01

    In this book the authors describe the principles and methods behind probabilistic forecasting and Bayesian data assimilation. Instead of focusing on particular application areas, the authors adopt a general dynamical systems approach, with a profusion of low-dimensional, discrete-time numerical examples designed to build intuition about the subject. Part I explains the mathematical framework of ensemble-based probabilistic forecasting and uncertainty quantification. Part II is devoted to Bayesian filtering algorithms, from classical data assimilation algorithms such as the Kalman filter, variational techniques, and sequential Monte Carlo methods, through to more recent developments such as the ensemble Kalman filter and ensemble transform filters. The McKean approach to sequential filtering in combination with coupling of measures serves as a unifying mathematical framework throughout Part II. Assuming only some basic familiarity with probability, this book is an ideal introduction for graduate students in ap...

  14. Nonlinear analysis of EEG for epileptic seizures

    Energy Technology Data Exchange (ETDEWEB)

    Hively, L.M.; Clapp, N.E.; Daw, C.S.; Lawkins, W.F. [Oak Ridge National Lab., TN (United States); Eisenstadt, M.L. [Knoxville Neurology Clinic, St. Mary`s Medical Center, Knoxville, TN (United States)

    1995-04-01

    We apply chaotic time series analysis (CTSA) to human electroencephalogram (EEG) data. Three epoches were examined: epileptic seizure, non-seizure, and transition from non-seizure to seizure. The CTSA tools were applied to four forms of these data: raw EEG data (e-data), artifact data (f-data) via application of a quadratic zero-phase filter of the raw data, artifact-filtered data (g- data) and that was the residual after subtracting f-data from e-data, and a low-pass-filtered version (h-data) of g-data. Two different seizures were analyzed for the same patient. Several nonlinear measures uniquely indicate an epileptic seizure in both cases, including an abrupt decrease in the time per wave cycle in f-data, an abrupt increase in the Kolmogorov entropy and in the correlation dimension for e-h data, and an abrupt increase in the correlation dimension for e-h data. The transition from normal to seizure state also is characterized by distinctly different trends in the nonlinear measures for each seizure and may be potential seizure predictors for this patient. Surrogate analysis of e-data shows that statistically significant nonlinear structure is present during the non-seizure, transition , and seizure epoches.

  15. Glycolysis in energy metabolism during seizures

    Institute of Scientific and Technical Information of China (English)

    Heng Yang; Jiongxing Wu; Ren Guo; Yufen Peng; Wen Zheng; Ding Liu; Zhi Song

    2013-01-01

    Studies have shown that glycolysis increases during seizures, and that the glycolytic metabolite lactic acid can be used as an energy source. However, how lactic acid provides energy for seizures and how it can participate in the termination of seizures remains unclear. We reviewed possible mechanisms of glycolysis involved in seizure onset. Results showed that lactic acid was involved in seizure onset and provided energy at early stages. As seizures progress, lactic acid reduces the pH of tissue and induces metabolic acidosis, which terminates the seizure. The specific mechanism of lactic acid-induced acidosis involves several aspects, which include lactic acid-induced inhibition of the glycolytic enzyme 6-diphosphate kinase-1, inhibition of the N-methyl-D-aspartate receptor, activation of the acid-sensitive 1A ion channel, strengthening of the receptive mechanism of the inhibitory neurotransmitter γ-aminobutyric acid, and changes in the intra- and extracellular environment.

  16. Localizing epileptic seizure onsets with Granger causality

    Science.gov (United States)

    Adhikari, Bhim M.; Epstein, Charles M.; Dhamala, Mukesh

    2013-09-01

    Accurate localization of the epileptic seizure onset zones (SOZs) is crucial for successful surgery, which usually depends on the information obtained from intracranial electroencephalography (IEEG) recordings. The visual criteria and univariate methods of analyzing IEEG recordings have not always produced clarity on the SOZs for resection and ultimate seizure freedom for patients. Here, to contribute to improving the localization of the SOZs and to understanding the mechanism of seizure propagation over the brain, we applied spectral interdependency methods to IEEG time series recorded from patients during seizures. We found that the high-frequency (>80 Hz) Granger causality (GC) occurs before the onset of any visible ictal activity and causal relationships involve the recording electrodes where clinically identifiable seizures later develop. These results suggest that high-frequency oscillatory network activities precede and underlie epileptic seizures, and that GC spectral measures derived from IEEG can assist in precise delineation of seizure onset times and SOZs.

  17. Stalking the Perfect Culture Assimilator.

    Science.gov (United States)

    Williams, John H.

    1982-01-01

    Discusses and gives examples of culture assimilators composed of a narrative of an intercultural encounter, four alternative interpretations, and four feedback explanations. Culture assimilators can be used to teach Americans about how to conduct themselves appropriately in France. (Author/BK)

  18. Assimilate Partitioning and Plant Development

    Institute of Scientific and Technical Information of China (English)

    Yong-Ling Ruan; John W.Patrick; Hans Weber

    2010-01-01

    @@ It has been a pleasure to organize this special issue of Molecular Plant on 'Assimilate Partitioning and Plant Development'. Assimilate, a collective term describing organic carbon (C) and nitrogen (N), is of paramount importance for plant development and realization of crop productivity.

  19. Seizure-induced disinhibition of the HPA axis increases seizure susceptibility.

    Science.gov (United States)

    O'Toole, Kate K; Hooper, Andrew; Wakefield, Seth; Maguire, Jamie

    2014-01-01

    Stress is the most commonly reported precipitating factor for seizures. The proconvulsant actions of stress hormones are thought to mediate the effects of stress on seizure susceptibility. Interestingly, epileptic patients have increased basal levels of stress hormones, including corticotropin-releasing hormone (CRH) and corticosterone, which are further increased following seizures. Given the proconvulsant actions of stress hormones, we proposed that seizure-induced activation of the hypothalamic-pituitary-adrenal (HPA) axis may contribute to future seizure susceptibility. Consistent with this hypothesis, our data demonstrate that pharmacological induction of seizures in mice with kainic acid or pilocarpine increases circulating levels of the stress hormone, corticosterone, and exogenous corticosterone administration is sufficient to increase seizure susceptibility. However, the mechanism(s) whereby seizures activate the HPA axis remain unknown. Here we demonstrate that seizure-induced activation of the HPA axis involves compromised GABAergic control of CRH neurons, which govern HPA axis function. Following seizure activity, there is a collapse of the chloride gradient due to changes in NKCC1 and KCC2 expression, resulting in reduced amplitude of sIPSPs and even depolarizing effects of GABA on CRH neurons. Seizure-induced activation of the HPA axis results in future seizure susceptibility which can be blocked by treatment with an NKCC1 inhibitor, bumetanide, or blocking the CRH signaling with Antalarmin. These data suggest that compromised GABAergic control of CRH neurons following an initial seizure event may cause hyperexcitability of the HPA axis and increase future seizure susceptibility.

  20. Nonlinear data assimilation

    CERN Document Server

    Van Leeuwen, Peter Jan; Reich, Sebastian

    2015-01-01

    This book contains two review articles on nonlinear data assimilation that deal with closely related topics but were written and can be read independently. Both contributions focus on so-called particle filters. The first contribution by Jan van Leeuwen focuses on the potential of proposal densities. It discusses the issues with present-day particle filters and explorers new ideas for proposal densities to solve them, converging to particle filters that work well in systems of any dimension, closing the contribution with a high-dimensional example. The second contribution by Cheng and Reich discusses a unified framework for ensemble-transform particle filters. This allows one to bridge successful ensemble Kalman filters with fully nonlinear particle filters, and allows a proper introduction of localization in particle filters, which has been lacking up to now.

  1. Smartphone applications for seizure management.

    Science.gov (United States)

    Pandher, Puneet Singh; Bhullar, Karamdeep Kaur

    2016-06-01

    Technological advancements continue to provide innovative ways of enhancing patient care in medicine. In particular, the growing popularity of smartphone technology has seen the recent emergence of a myriad of healthcare applications (or apps) that promise to help shape the way in which health information is delivered to people worldwide. While limited research already exists on a range of such apps, our study is the first to examine the salient features of smartphone applications as they apply to the area of seizure management. For the purposes of this review, we conducted a search of the official online application stores of the five major smartphone platforms: iPhone, Android, Blackberry, Windows Mobile and Nokia-Symbian. Apps were included if they reported to contain some information or tools relating to seizure management and excluded if they were aimed exclusively at health professionals. A total of 28 applications met these criteria. Overall, we found an increasing number of epilepsy apps available on the smartphone market, but with only a minority offering comprehensive educational information alongside tools such as seizure diaries, medication tracking and/or video recording.

  2. A novel seizure detection algorithm informed by hidden Markov model event states

    Science.gov (United States)

    Baldassano, Steven; Wulsin, Drausin; Ung, Hoameng; Blevins, Tyler; Brown, Mesha-Gay; Fox, Emily; Litt, Brian

    2016-06-01

    Objective. Recently the FDA approved the first responsive, closed-loop intracranial device to treat epilepsy. Because these devices must respond within seconds of seizure onset and not miss events, they are tuned to have high sensitivity, leading to frequent false positive stimulations and decreased battery life. In this work, we propose a more robust seizure detection model. Approach. We use a Bayesian nonparametric Markov switching process to parse intracranial EEG (iEEG) data into distinct dynamic event states. Each event state is then modeled as a multidimensional Gaussian distribution to allow for predictive state assignment. By detecting event states highly specific for seizure onset zones, the method can identify precise regions of iEEG data associated with the transition to seizure activity, reducing false positive detections associated with interictal bursts. The seizure detection algorithm was translated to a real-time application and validated in a small pilot study using 391 days of continuous iEEG data from two dogs with naturally occurring, multifocal epilepsy. A feature-based seizure detector modeled after the NeuroPace RNS System was developed as a control. Main results. Our novel seizure detection method demonstrated an improvement in false negative rate (0/55 seizures missed versus 2/55 seizures missed) as well as a significantly reduced false positive rate (0.0012 h versus 0.058 h-1). All seizures were detected an average of 12.1 ± 6.9 s before the onset of unequivocal epileptic activity (unequivocal epileptic onset (UEO)). Significance. This algorithm represents a computationally inexpensive, individualized, real-time detection method suitable for implantable antiepileptic devices that may considerably reduce false positive rate relative to current industry standards.

  3. Assessing and predicting biodiversity in a floodplain ecosystem: Assimilation of net primary prodution derived from imaging spectrometer data into a dynamic vegetation model

    NARCIS (Netherlands)

    Kooistra, L.; Wamelink, G.W.W.; Schaepman-Strub, G.; Schaepman, M.E.; Dobben, van H.F.; Aduaka, U.; Batelaan, O.

    2008-01-01

    New concepts for river management in northwestern Europe are being developed which aim at both flood protection and nature conservation. As a result, methods are required that assess the effect of management activities on the biodiversity of floodplain ecosystems. In this paper, we show that dynamic

  4. Data Assimilation and Model Evaluation Experiment Datasets.

    Science.gov (United States)

    Lai, Chung-Chieng A.; Qian, Wen; Glenn, Scott M.

    1994-05-01

    The Institute for Naval Oceanography, in cooperation with Naval Research Laboratories and universities, executed the Data Assimilation and Model Evaluation Experiment (DAMÉE) for the Gulf Stream region during fiscal years 1991-1993. Enormous effort has gone into the preparation of several high-quality and consistent datasets for model initialization and verification. This paper describes the preparation process, the temporal and spatial scopes, the contents, the structure, etc., of these datasets.The goal of DAMEE and the need of data for the four phases of experiment are briefly stated. The preparation of DAMEE datasets consisted of a series of processes: 1)collection of observational data; 2) analysis and interpretation; 3) interpolation using the Optimum Thermal Interpolation System package; 4) quality control and re-analysis; and 5) data archiving and software documentation.The data products from these processes included a time series of 3D fields of temperature and salinity, 2D fields of surface dynamic height and mixed-layer depth, analysis of the Gulf Stream and rings system, and bathythermograph profiles. To date, these are the most detailed and high-quality data for mesoscale ocean modeling, data assimilation, and forecasting research. Feedback from ocean modeling groups who tested this data was incorporated into its refinement.Suggestions for DAMEE data usages include 1) ocean modeling and data assimilation studies, 2) diagnosis and theorectical studies, and 3) comparisons with locally detailed observations.

  5. Marked Seizure Reduction after MCT Supplementation

    Directory of Open Access Journals (Sweden)

    Raed Azzam

    2013-01-01

    Full Text Available We report the case of a 43-year-old man with history of nonsurgical partial epilepsy who previously failed multiple trials of antiepileptic drugs. Medium-chain triglycerides (MCT were added to his regular diet in the form of pure oil. Subsequently, his seizure frequency was markedly reduced from multiple daily seizures to one seizure every four days. His seizures recurred after transient discontinuation of MCT over a period of ten days. His seizure improvement was achieved at a dose of four tablespoons of MCT twice daily with no reported side effects. He developed significant diarrhea and flatulence at higher doses. We conclude that MCT oil supplementation to regular diet may provide better seizure control in some patients. MCT oil supplementation may be a more tolerable alternative to the standard ketogenic diet.

  6. Seizure detection algorithms based on EMG signals

    DEFF Research Database (Denmark)

    Conradsen, Isa

    Background: the currently used non-invasive seizure detection methods are not reliable. Muscle fibers are directly connected to the nerves, whereby electric signals are generated during activity. Therefore, an alarm system on electromyography (EMG) signals is a theoretical possibility. Objective...... on the amplitude of the signal. The other algorithm was based on information of the signal in the frequency domain, and it focused on synchronisation of the electrical activity in a single muscle during the seizure. Results: The amplitude-based algorithm reliably detected seizures in 2 of the patients, while......: to show whether medical signal processing of EMG data is feasible for detection of epileptic seizures. Methods: EMG signals during generalised seizures were recorded from 3 patients (with 20 seizures in total). Two possible medical signal processing algorithms were tested. The first algorithm was based...

  7. Ketamine Induced Seizures in an Autistic Child

    Directory of Open Access Journals (Sweden)

    Geetanjali S Verma

    2014-02-01

    Full Text Available An autistic child of eight years age, with attention deficit hyperactivity syndrome presented for tooth extraction under general anaesthesia. Ketamine was used for induction and the child developed seizures following its administration. Seizures were controlled, extraction done and post-operative period was uneventful. Ketamine was suspected to have caused seizures though safe use of Ketamine has been reported in autistic patient.

  8. Seizures and X-linked intellectual disability

    OpenAIRE

    Stevenson, Roger E; Holden, Kenton R.; Rogers, R. Curtis; Schwartz, Charles E.

    2012-01-01

    Intellectual disability occurs as an isolated X-linked trait and as a component of recognizable X-linked syndromes in the company of somatic, metabolic, neuromuscular, or behavioral abnormalities. Seizures accompany intellectual disability in almost half of these X-linked disorders. The spectrum of seizures found in the X-linked intellectual disability syndromes is broad, varying in time of onset, type of seizure, and response to anticonvulsant therapy. The majority of the genes associated wi...

  9. Family history and recurrence of febrile seizures.

    OpenAIRE

    1994-01-01

    To determine the value of a detailed family history for the assessment of the risk of recurrence of febrile seizures, 115 children who visited the emergency room of an academic children's hospital were studied prospectively. The recurrence risk of febrile seizures was analysed in relation to the child's family history and the proportion of relatives affected by febrile seizures using Kaplan-Meier estimates and Cox proportional hazard models. A first degree family history positive for febrile ...

  10. Seizure characteristics in Pallister-Killian syndrome.

    Science.gov (United States)

    Candee, Meghan S; Carey, John C; Krantz, Ian D; Filloux, Francis M

    2012-12-01

    Pallister-Killian syndrome (PKS) is a congenital disorder attributed to supernumerary isochromosome 12p mosaicism. Craniofacial dysmorphism, learning impairment and seizures are considered cardinal features. However, little is known regarding the seizure and epilepsy patterns in PKS. To better define the prevalence and spectrum of seizures in PKS, we studied 51 patients (39 male, 12 female; median age 4 years and 9 months; age range 7 months to 31 years) with confirmed 12p tetrasomy. Using a parent-based structured questionnaire, we collected data regarding seizure onset, frequency, timing, semiology, and medication therapy. Patients were recruited through our practice, at PKS Kids family events, and via the PKS Kids website. Epilepsy occurred in 27 (53%) with 23 (85%) of those with seizures having seizure onset prior to 3.5 years of age. Mean age at seizure onset was 2 years and 4 months. The most common seizure types were myoclonic (15/27, 56%), generalized convulsions (13/27, 48%), and clustered tonic spasms (similar to infantile spasms; 8/27, 30%). Thirteen of 27 patients with seizures (48%) had more than one seizure type with 26 out of 27 (96%) ever having taken antiepileptic medications. Nineteen of 27 (70%) continued to have seizures and 17/27 (63%) remained on antiepileptic medication. The most commonly used medications were: levetiracetam (10/27, 37%), valproic acid (10/27, 37%), and topiramate (9/27, 33%) with levetiracetam felt to be "most helpful" by parents (6/27, 22%). Further exploration of seizure timing, in-depth analysis of EEG recordings, and collection of MRI data to rule out confounding factors is warranted.

  11. Deterministic treatment of model error in geophysical data assimilation

    CERN Document Server

    Carrassi, Alberto

    2015-01-01

    This chapter describes a novel approach for the treatment of model error in geophysical data assimilation. In this method, model error is treated as a deterministic process fully correlated in time. This allows for the derivation of the evolution equations for the relevant moments of the model error statistics required in data assimilation procedures, along with an approximation suitable for application to large numerical models typical of environmental science. In this contribution we first derive the equations for the model error dynamics in the general case, and then for the particular situation of parametric error. We show how this deterministic description of the model error can be incorporated in sequential and variational data assimilation procedures. A numerical comparison with standard methods is given using low-order dynamical systems, prototypes of atmospheric circulation, and a realistic soil model. The deterministic approach proves to be very competitive with only minor additional computational c...

  12. A seizure response dog: video recording of reacting behaviour during repetitive prolonged seizures.

    Science.gov (United States)

    Di Vito, Lidia; Naldi, Ilaria; Mostacci, Barbara; Licchetta, Laura; Bisulli, Francesca; Tinuper, Paolo

    2010-06-01

    Seizure response and alerting behaviour may spontaneously develop in dogs living with children or adults with epilepsy. Some dogs can also be reliably trained to respond and anticipate seizures. We describe the case of a dog, not previously trained for assistance work, showing complex seizure response behaviour. This is the first release of a home video recording of a dog reacting to its owner's seizure.

  13. Seizure-Induced Neuronal Injury: Vulnerability to Febrile Seizures in an Immature Rat Model

    OpenAIRE

    Toth, Zsolt; Yan, Xiao-Xin; Haftoglou, Suzie; Ribak, Charles E.; Tallie Z. Baram

    1998-01-01

    Febrile seizures are the most common seizure type in young children. Whether they induce death of hippocampal and amygdala neurons and consequent limbic (temporal lobe) epilepsy has remained controversial, with conflicting data from prospective and retrospective studies. Using an appropriate-age rat model of febrile seizures, we investigated the acute and chronic effects of hyperthermic seizures on neuronal integrity and survival in the hippocampus and amygdala via molecular and neuroanatomic...

  14. Data assimilation for air quality models

    DEFF Research Database (Denmark)

    Silver, Jeremy David

    2014-01-01

    chemical and physical dynamics. Concentrations of atmospheric trace gases such as ozone, carbon monoxide and nitrogen dioxide vary substantially in space and time, and this variation can be investigated by various methods including direct measurements, remote-sensing measurements and atmospheric chemistry......-dimensional optimal interpolation procedure (OI), an Ensemble Kalman Filter (EnKF), and a three-dimensional variational scheme (3D-var). The three assimilation procedures are described and tested. A multi-faceted approach is taken for the verification, using independent measurements from surface air...

  15. Treating seizures in Creutzfeldt–Jakob disease

    Directory of Open Access Journals (Sweden)

    Marcus C. Ng

    2014-01-01

    Full Text Available Seizures are known to occur in Creutzfeldt–Jakob disease (CJD. In the setting of a rapidly progressive condition with no effective therapy, determining appropriate treatment for seizures can be difficult if clinical morbidity is not obvious yet the electroencephalogram (EEG demonstrates a worrisome pattern such as status epilepticus. Herein, we present the case of a 39-year-old man with CJD and electrographic seizures, discuss how this case challenges conventional definitions of seizures, and discuss a rational approach toward treatment. Coincidentally, our case is the first report of CJD in a patient with Stickler syndrome.

  16. Global Data Assimilation System (GDAS)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Global Data Assimilation System (GDAS) is the system used by the Global Forecast System (GFS) model to place observations into a gridded model space for the...

  17. Data assimilation in hydrological modelling

    DEFF Research Database (Denmark)

    Drecourt, Jean-Philippe

    Data assimilation is an invaluable tool in hydrological modelling as it allows to efficiently combine scarce data with a numerical model to obtain improved model predictions. In addition, data assimilation also provides an uncertainty analysis of the predictions made by the hydrological model...... with model non-linearities and biased errors. A literature review analyzes the most popular techniques and their application in hydrological modelling. Since bias is an important problem in groundwater modelling, two bias aware Kalman filters have been implemented and compared using an artificial test case....... In this thesis, the Kalman filter is used for data assimilation with a focus on groundwater modelling. However the developed techniques are general and can be applied also in other modelling domains. Modelling involves conceptualization of the processes of Nature. Data assimilation provides a way to deal...

  18. WAVE ASSIMILATION AND NUMERICAL PREDICTION

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    An adjoint variational method for wave data assimilation in the LAGFD-WAM wave model is proposed. The adjoint equation of the wavenumber energy spectrum balance equation is derived. And fortunately, its characteristic equations are the same as those in the LAGFD-WAM wave model. Simple experiments on the functional optimization and assimilation effectiveness during the prediction period indicated that the adjoint variational method is effective for wave assimilation and that the initial optimization of the wave model is important for the short-range wave prediction. All of this is under the assumption that the wind field is accurate, the method is the important first step for combined wind and wave data assimilation systems.

  19. Global Land Data Assimilation System

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — The goal of the Global Land Data Assimilation System (GLDAS) is to ingest satellite- and ground-based observational data products, using advanced land surface...

  20. Data Assimilation in Ocean Prediction

    Science.gov (United States)

    2016-06-07

    contour plots of the estimates of the sea surface height ( SSH ) for the top layer after 5 Topex/ Poseidon simulated repeat cycles. The top plot in Figure... SSH ): Top: SSH for the actual truth; middle: SSH with no data assimilation; and bottom: SSH with data assimilation from satellite altimetry. Darker...regions are deeper, lighter regions are higher. 2: RMSE of the SSH for the top two layers. The lower curve is the RMSE for the surface layer while the

  1. CONSIDERATIONS UPON ASSIMILATED ADMINISTRATIVE ACTS

    OpenAIRE

    2011-01-01

    Although the classic administrative courts know as object the acts against classic administrative acts, it should not be lost sight of the assimilated administrative acts, which also may be subject to acts in this litigation. Taking in consideration this category of acts, this study will examine the documents falling into this category and the impact that such acts have on public authorities. Given the significant increase of administrative cases that have as object assimilated administrative...

  2. Assimilation of Geosat Altimetric Data in a Nonlinear Shallow-Water Model of the Indian Ocean by Adjoint Approach. Part II: Some Validation and Interpretation of the Assimilated Results. Part 2; Some Validation and Interpretation of the Assimilated Results

    Science.gov (United States)

    Greiner, Eric; Perigaud, Claire

    1996-01-01

    This paper examines the results of assimilating Geosat sea level variations relative to the November 1986-November 1988 mean reference, in a nonlinear reduced-gravity model of the Indian Ocean, Data have been assimilated during one year starting in November 1986 with the objective of optimizing the initial conditions and the yearly averaged reference surface. The thermocline slope simulated by the model with or without assimilation is validated by comparison with the signal, which can be derived from expandable bathythermograph measurements performed in the Indian Ocean at that time. The topography simulated with assimilation on November 1986 is in very good agreement with the hydrographic data. The slopes corresponding to the South Equatorial Current and to the South Equatorial Countercurrent are better reproduced with assimilation than without during the first nine months. The whole circulation of the cyclonic gyre south of the equator is then strongly intensified by assimilation. Another assimilation experiment is run over the following year starting in November 1987. The difference between the two yearly mean surfaces simulated with assimilation is in excellent agreement with Geosat. In the southeastern Indian Ocean, the correction to the yearly mean dynamic topography due to assimilation over the second year is negatively correlated to the one the year before. This correction is also in agreement with hydrographic data. It is likely that the signal corrected by assimilation is not only due to wind error, because simulations driven by various wind forcings present the same features over the two years. Model simulations run with a prescribed throughflow transport anomaly indicate that assimilation is rather correcting in the interior of the model domain for inadequate boundary conditions with the Pacific.

  3. Seizures

    Science.gov (United States)

    ... Geme JW, Schor NF, eds. Nelson Textbook of Pediatrics . 20th ed. Philadelphia, PA: Elsevier; 2016:chap 593. Read ... Brain aneurysm repair - discharge Epilepsy in children - discharge Epilepsy or ...

  4. Complex partial seizures: cerebellar metabolism

    Energy Technology Data Exchange (ETDEWEB)

    Theodore, W.H.; Fishbein, D.; Deitz, M.; Baldwin, P.

    1987-07-01

    We used positron emission tomography (PET) with (/sup 18/F)2-deoxyglucose to study cerebellar glucose metabolism (LCMRglu) and the effect of phenytoin (PHT) in 42 patients with complex partial seizures (CPS), and 12 normal controls. Mean +/- SD patient LCMRglu was 6.9 +/- 1.8 mg glucose/100 g/min (left = right), significantly lower than control values of 8.5 +/- 1.8 (left, p less than 0.006), and 8.3 +/- 1.6 (right, p less than 0.02). Only four patients had cerebellar atrophy on CT/MRI; cerebellar LCMRglu in these was 5.5 +/- 1.5 (p = 0.054 vs. total patient sample). Patients with unilateral temporal hypometabolism or EEG foci did not have lateralized cerebellar hypometabolism. Patients receiving phenytoin (PHT) at the time of scan and patients with less than 5 years total PHT exposure had lower LCMRglu, but the differences were not significant. There were weak inverse correlations between PHT level and cerebellar LCMRglu in patients receiving PHT (r = -0.36; 0.05 less than p less than 0.1), as well as between length of illness and LCMRglu (r = -0.22; 0.05 less than p less than 0.1). Patients with complex partial seizures have cerebellar hypometabolism that is bilateral and due only in part to the effect of PHT.

  5. Update on the Neurobiology of Alcohol Withdrawal Seizures

    OpenAIRE

    2005-01-01

    Abrupt cessation of alcohol intake after prolonged heavy drinking may trigger alcohol withdrawal seizures. Generalized tonic–clonic seizures are the most characteristic and severe type of seizure that occur in this setting. Generalized seizures also occur in rodent models of alcohol withdrawal. In these models, the withdrawal seizures are triggered by neuronal networks in the brainstem, including the inferior colliculus; similar brainstem mechanisms may contribute to alcohol withdrawal seizur...

  6. De novo psychogenic seizures after epilepsy surgery: case report

    Directory of Open Access Journals (Sweden)

    MONTENEGRO MARIA AUGUSTA

    2000-01-01

    Full Text Available The occurrence of de novo psychogenic seizures after epilepsy surgery is rare, and is estimated in 1.8% to 3.6%. Seizures after epilepsy surgery should be carefully evaluated, and de novo psychogenic seizures should be considered especially when there is a change in the ictal semiology. We report a patient with de novo psychogenic seizures after anterior temporal lobe removal for refractory temporal lobe epilepsy. Once psychogenic seizures were diagnosed and psychiatric treatment was started, seizures stopped.

  7. Data assimilation for magnetohydrodynamics systems

    Science.gov (United States)

    Mendoza, O. Barrero; de Moor, B.; Bernstein, D. S.

    2006-05-01

    Prediction of solar storms has become a very important issue due to the fact that they can affect dramatically the telecommunication and electrical power systems at the earth. As a result, a lot of research is being done in this direction, space weather forecast. Magnetohydrodynamics systems are being studied in order to analyse the space plasma dynamics, and techniques which have been broadly used in the prediction of earth environmental variables like the Kalman filter (KF), the ensemble Kalman filter (EnKF), the extended Kalman filter (EKF), etc., are being studied and adapted to this new framework. The assimilation of a wide range of space environment data into first-principles-based global numerical models will improve our understanding of the physics of the geospace environment and the forecasting of its behaviour. Therefore, the aim of this paper is to study the performance of nonlinear observers in magnetohydrodynamics systems, namely, the EnKF.The EnKF is based on a Monte Carlo simulation approach for propagation of process and measurement errors. In this paper, the EnKF for a nonlinear two-dimensional magnetohydrodynamic (2D-MHD) system is considered. For its implementation, two software packages are merged, namely, the Versatile Advection Code (VAC) written in Fortran and Matlab of Mathworks. The 2D-MHD is simulated with the VAC code while the EnKF is computed in Matlab. In order to study the performance of the EnKF in MHD systems, different number of measurement points as well as ensemble members are set.

  8. Transient inhibitory seizures mimicking crescendo TIAs.

    Science.gov (United States)

    Lee, H; Lerner, A

    1990-01-01

    Somatic inhibitory seizures are thought to occur rarely. We describe a patient with somatic inhibitory seizures who initially presented with a clinical picture of crescendo transient ischemic attacks. He did not improve with anticoagulation, but the episodes ceased promptly after the administration of an anticonvulsant.

  9. ROLE OF MRI IN EVALUATION OF SEIZURES

    Directory of Open Access Journals (Sweden)

    Avadhesh Pratap Singh

    2015-12-01

    Full Text Available BACKGROUND Seizure is a paroxysmal alteration in neurologic function resulting from abnormal excessive neuronal electrical activity. Epilepsy is a chronic condition characterized by recurrent seizures unprovoked by an acute systemic or neurologic insult.1 An epileptic seizure is a clinical manifestation of abnormal, excessive neuronal activity arising in the grey matter of the cerebral cortex. MATERIALS AND METHODS Prospective studies of 100 patients with clinical impression of seizures were examined by 1.5 Tesla magnetic resonance imaging. RESULT A total of 100 patients satisfying the inclusion criteria were included in the study. The age range of patients was from neonate to elderly with male predominance, male 64 (64% and female 36 (36%. GTCS was the most common clinical diagnosis constituting (80% cases. The common abnormalities were cerebral infarction with gliosis (16%, infections – NCC (7% and tuberculoma (10%, cerebral atrophy (1%, developmental cortical malformations (2%, venous thrombosis (4%, low-grade glioma (9%, meningioma (3%. CONCLUSION MRI is the investigation of choice in patients with seizure disorder. The sensitivity of MRI in detecting abnormalities in patients with seizure disorder is in part associated to the underlying pathologies and by the MRI techniques and experience of the interpreting physician. Accurate diagnosis of the cause of seizure is crucial for finding an effective treatment. With its high spatial resolution, excellent inherent soft tissue contrast, multiplanar imaging capability and lack of ionizing radiation, MR imaging has emerged as a versatile tool in the evaluation of patients with seizure disorder.

  10. Treatment of drug-induced seizures.

    Science.gov (United States)

    Chen, Hsien-Yi; Albertson, Timothy E; Olson, Kent R

    2016-03-01

    Seizures are a common complication of drug intoxication, and up to 9% of status epilepticus cases are caused by a drug or poison. While the specific drugs associated with drug-induced seizures may vary by geography and change over time, common reported causes include antidepressants, stimulants and antihistamines. Seizures occur generally as a result of inadequate inhibitory influences (e.g., gamma aminobutyric acid, GABA) or excessive excitatory stimulation (e.g. glutamate) although many other neurotransmitters play a role. Most drug-induced seizures are self-limited. However, status epilepticus occurs in up to 10% of cases. Prolonged or recurrent seizures can lead to serious complications and require vigorous supportive care and anticonvulsant drugs. Benzodiazepines are generally accepted as the first line anticonvulsant therapy for drug-induced seizures. If benzodiazepines fail to halt seizures promptly, second line drugs include barbiturates and propofol. If isoniazid poisoning is a possibility, pyridoxine is given. Continuous infusion of one or more anticonvulsants may be required in refractory status epilepticus. There is no role for phenytoin in the treatment of drug-induced seizures. The potential role of ketamine and levetiracetam is promising but not established.

  11. Effect of Seizure Clustering on Epilepsy Outcome

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2008-05-01

    Full Text Available A prospective, long-term population-based study was performed to determine whether seizure clustering (3 or more afebrile seizures during a 24 hour period is associated with drug resistance and increased mortality in childhood-onset epilepsy, in a study at University of Turku, Finland, and the Epilepsy Research Group, Berlin, Germany.

  12. Febrile Seizures: clinical and genetic studies

    NARCIS (Netherlands)

    M. van Stuijvenberg (Margriet)

    1998-01-01

    textabstractFebrile seizures are described as a temporary seizure disorder of childhood; the attacks occur by definition in association with fever and are usually accompanied by sudden tonic-clonic muscle contractions and reduced consciousness, usually lasting not longer than 5 to 10 minutes. Accord

  13. The Role of Seizure-Related SEZ6 as a Susceptibility Gene in Febrile Seizures

    Directory of Open Access Journals (Sweden)

    John C. Mulley

    2011-01-01

    Full Text Available Sixty cases of febrile seizures from a Chinese cohort had previously been reported with a strong association between variants in the seizure-related (SEZ 6 gene and febrile seizures. They found a striking lack of genetic variation in their controls. We found genetic variation in SEZ6 at similar levels at the same DNA sequence positions in our 94 febrile seizure cases as in our 96 unaffected controls. Two of our febrile seizure cases carried rare variants predicted to have damaging consequences. Combined with some of the variants from the Chinese cohort, these data are compatible with a role for SEZ6 as a susceptibility gene for febrile seizures. However, the polygenic determinants underlying most cases of febrile seizures with complex inheritance remain to be determined.

  14. Predictors of seizures during pregnancy in women with epilepsy.

    Science.gov (United States)

    Thomas, Sanjeev V; Syam, Unnikrishnan; Devi, J Sucharitha

    2012-05-01

    We aimed to characterize the seizure pattern during pregnancy in a large cohort of women with epilepsy (WWE) and identify possible predictors of seizure relapse during pregnancy. We recorded the antiepileptic drug (AED) use and seizure frequency for WWE during the prepregnancy month and pregnancy. The seizure profile was correlated with the clinical details and seizure type as abstracted from the clinical records maintained in the registry. Of the 1,297 pregnancies in WWE with complete seizure data, 47.8% were seizure-free during pregnancy. Seizure relapse was highest during the three peripartum days. Women with partial seizures-had higher risk of relapse (odds ratio [OR] 1.6, 95% confidence interval [CI] 1.2-2.0) than those with generalized seizures. They had two peaks of seizure relapse (second to third month and sixth month). Those with generalized seizures had one peak at first trimester. Those who were on polytherapy had increased risk of seizures (OR 2.98, 95% CI 2.3-3.9) when compared to those on monotherapy. Those who had seizures in the prepregnancy month had higher risk (OR 15, 95% CI 9-25.1) of seizures during pregnancy when compared to those who were seizure-free during that period. On multiple logistic regression, prepregnancy seizure was the most important predictor of seizures during pregnancy.

  15. Detection and Prediction of Epileptic Seizures

    DEFF Research Database (Denmark)

    Duun-Henriksen, Jonas

    monitoring of their brain waves. More specifically, three issues were investigated: The feasibility of automatic seizure prediction, optimization of automatic seizure detection algorithms, and the link between intra- and extracranial EEG. Regarding feasibility of automatic seizure prediction, neither...... seizure prediction algorithms. More promising results were obtained in the investigating of possible use of an outpatient EEG monitoring device for idiopathic generalized epilepsy patients. Combined with an automatic seizure detection algorithm such a device can give an objective account of the paroxysm...... frequency, duration, and time of occurrence. Based on standard EEG data from 20 patients recorded in the clinic, the log-sum of wavelet transform coefficients were used as feature input to a classifier consisting of a support vector machine. 97% of paroxysms lasting more than two seconds were correctly...

  16. Febrile seizures and risk of schizophrenia

    DEFF Research Database (Denmark)

    Vestergaard, Mogens; Pedersen, Carsten Bøcker; Christensen, Jakob;

    2005-01-01

    BACKGROUND: Febrile seizure is a benign condition for most children, but experiments in animals and neuroimaging studies in humans suggest that some febrile seizures may damage the hippocampus, a brain area of possible importance in schizophrenia. METHODS: A population-based cohort of all children...... with schizophrenia. A history of febrile seizures was associated with a 44% increased risk of schizophrenia [relative risk (RR)=1.44; 95% confidence interval (CI), 1.07-1.95] after adjusting for confounding factors. The association between febrile seizures and schizophrenia remained virtually unchanged when...... restricting the analyses to people with no history of epilepsy. A history of both febrile seizures and epilepsy was associated with a 204% increased risk of schizophrenia (RR=3.04; 95% CI, 1.36-6.79) as compared with people with no such history. CONCLUSIONS: We found a slightly increased risk of schizophrenia...

  17. Moxifloxacin Induced Seizures -A Case Report.

    Directory of Open Access Journals (Sweden)

    Jiana Shi

    2014-09-01

    Full Text Available A 73-year-old female patient developed a generalized tonic-clonic seizure on the 6th day after treatment with moxifloxacin 400 mg daily intravenously for appendicitis. This patient had atrial fibrillation and history of a surgery for intracerebral hemorrhage, with impaired renal function and liver function, but without history of seizures. Moxifloxacin was discontinued and switched to cefuroxime. The patient remained seizure-free at discharge four days later. The naranjo adverse drug reaction probability scale score was 4, indicating a possible adverse reaction to moxifloxacin. The potential risk factors related to moxifloxacin-induced seizures are discussed. It highlights that preexisting central nervous system disease, elderly female with lower bodyweight and severe renal impairment may be the risk factors involved in moxifloxacin-induced seizures.

  18. Dynamic Monitoring of Heavy Metal Stresses in Rice by a Remote Sensing Data-Assimilated WOFOST Model%遥感同化WOFOST模型动态监测水稻重金属污染胁迫

    Institute of Scientific and Technical Information of China (English)

    赵利婷; 刘湘南; 丁超; 刘烽; 裴松伟; 夏小鹏

    2015-01-01

    . Additionally, assimilating remote sensing data into the WOFOST model can also monitor heavy metal stresses in rice on spatial scale dynamically and continuously.%为研究土壤重金属污染对作物生长尤其是根系生长的影响,探讨了利用遥感与作物生长模型同化方法获取水稻根重WRT (Weight of Root)的变化,进而动态监测水稻重金属污染胁迫的可行性。以吉林省长春市两块不同污染水平的水稻种植区为研究对象,以叶面积指数LAI(Leaf Area Index)为结合点,使用灰色关联度分析选择与根重关联度最高的作物参数CVR(干物质转化为根重的效率,Efficiency of Conversion into Roots),通过粒子群优化算法PSO(Particle Swarm Optimization)优化CVR,实现作物生长模型WOFOST(World Food Studies)与CCD遥感数据的同化,并用同化后的WOFOST模型模拟WRT进行水稻重金属污染胁迫状况分析,最后对研究区水稻重金属污染胁迫进行了分级评价。结果表明,整个生长期污染严重区域水稻根重比污染较轻区的水稻根重低,二者比值范围为0.894~0.972,均值为0.922,在水稻分蘖期比值最低达到0.894。可见根重的变化是监测水稻重金属污染胁迫的有效指标,该方法能够在水稻生长的早期(分蘖期)就监测到重金属污染胁迫。

  19. Folinic acid-responsive neonatal seizures.

    Science.gov (United States)

    Torres, O A; Miller, V S; Buist, N M; Hyland, K

    1999-08-01

    We report three cases of folinic acid-responsive intractable neonatal seizures. All patients were born at term following normal gestation and delivery. In the first infant, seizures began on the 5th day of life and were unresponsive to phenobarbital, pyridoxine, and valproate, but stopped within 24 hours of initiation of folinic acid treatment at the age of 6 months. Her sibling had died at age 6 months with intractable seizures. In the second infant, seizures began in the 2nd hour of life. These were initially controlled with phenobarbital; however, at 3 months of age she developed status epilepticus refractory to anticonvulsants, steroids, and pyridoxine and she required repeated induction of pentobarbital coma. Seizures stopped within 24 hours of starting folinic acid. Seizures and encephalopathy were noted in the third infant on the 2nd day of life. These were controlled with phenobarbital, but at 8 weeks of age seizures recurred and were difficult to control despite the addition of phenytoin. Immediately after folinic acid was initiated the seizures stopped. Breakthrough seizures in all patients have responded to increases in folinic acid; two of the three remain on standard anticonvulsants. All patients have global developmental delay. Cranial magnetic resonance imaging in the second patient shows diffuse atrophy, and in the third patient shows increased signal on T2 images in the white matter of the frontal and parietal lobes. Analysis of cerebrospinal fluid from these patients using high-performance liquid chromatography with electrochemical detection has consistently revealed an as-yet unidentified compound, which can be used as a marker for this condition. We suggest that cerebrospinal fluid be analyzed for the presence of this compound and a trial of folinic acid be considered in neonates with unexplained early onset intractable seizures.

  20. Effective Assimilation of Global Precipitation

    Science.gov (United States)

    Lien, G.; Kalnay, E.; Miyoshi, T.; Huffman, G. J.

    2012-12-01

    Assimilating precipitation observations by modifying the moisture and sometimes temperature profiles has been shown successful in forcing the model precipitation to be close to the observed precipitation, but only while the assimilation is taking place. After the forecast start, the model tends to "forget" the assimilation changes and lose their extra skill after few forecast hours. This suggests that this approach is not an efficient way to modify the potential vorticity field, since this is the variable that the model would remember. In this study, the ensemble Kalman filter (EnKF) method is used to effectively change the potential vorticity field by allowing ensemble members with better precipitation to receive higher weights. In addition to using an EnKF, two other changes in the precipitation assimilation process are proposed to solve the problems related to the highly non-Gaussian nature of the precipitation variable: a) transform precipitation into a Gaussian distribution based on its climatological distribution, and b) only assimilate precipitation at the location where some ensemble members have positive precipitation. The idea is first tested by the observing system simulation experiments (OSSEs) using SPEEDY, a simplified but realistic general circulation model. When the global precipitation is assimilated in addition to conventional rawinsonde observations, both the analyses and the medium range forecasts are significantly improved as compared to only having rawinsonde observations. The improvement is much reduced when only modifying the moisture field with the same approach, which shows the importance of the error covariance between precipitation and all other model variables. The effect of precipitation assimilation is larger in the Southern Hemisphere than that in the Northern Hemisphere because the Northern Hemisphere analyses are already accurate as a result of denser rawinsonde stations. Assimilation of precipitation using a more comprehensive

  1. Lexical frequency and voice assimilation.

    Science.gov (United States)

    Ernestus, Mirjam; Lahey, Mybeth; Verhees, Femke; Baayen, R Harald

    2006-08-01

    Acoustic duration and degree of vowel reduction are known to correlate with a word's frequency of occurrence. The present study broadens the research on the role of frequency in speech production to voice assimilation. The test case was regressive voice assimilation in Dutch. Clusters from a corpus of read speech were more often perceived as unassimilated in lower-frequency words and as either completely voiced (regressive assimilation) or, unexpectedly, as completely voiceless (progressive assimilation) in higher-frequency words. Frequency did not predict the voice classifications over and above important acoustic cues to voicing, suggesting that the frequency effects on the classifications were carried exclusively by the acoustic signal. The duration of the cluster and the period of glottal vibration during the cluster decreased while the duration of the release noises increased with frequency. This indicates that speakers reduce articulatory effort for higher-frequency words, with some acoustic cues signaling more voicing and others less voicing. A higher frequency leads not only to acoustic reduction but also to more assimilation.

  2. Chemical Data Assimilation &Optimized Earth Observation

    Science.gov (United States)

    Lary, D.

    2003-04-01

    Issues such as ozone depletion, acid rain, and photochemical smog are all of considerable environmental importance. These issues are studied using the dual approach of observations and numerical modelling. In making balanced assessments of these issues it is vital to make the best use of all the information available to us, both theoretical and observational. This is a non-trivial task. The technique of "data assimilation" is a powerful tool which allows us to address this issue. It is revolutionising the way we can study atmospheric chemistry. Data assimilation allows us to simultaneously make good use of however many observations are available to us, our theoretical understanding, and any apriori information we have, within a mathematical framework. It even allows us to infer information about chemical constituents which are not observed. It is a technique which is set to grow in importance. It is also applicable to any system for which we have both observations, a deterministic model, and estimates of uncertainty. Such applications could be from laboratory kinetics to metabolic pathways. Looking ahead we can envision Data assimilation as part of a Optimized Earth Observation System by developing a dynamic data retrieval control system. The dynamic data retrieval control system will dynamically adapt the what, where, and when for the observations made in an online fashion to maximize information content, minimize uncertainty in characterizing the system’s state vector, and minimize both the required storage and data processing time for a given observation capability (with the possibility of even directing unmanned sub-orbital platforms, drones, to make additional observations). This is particularly desirable to facilitate the dynamic tracking of evolving sharp gradients, for example, those in chemical tracer fields often located at the polar vortex edge, the tropopause and the day-night division. The basic idea is the desire for symbiotic communication to

  3. Improving the Horizontal Transport in the Lower Troposphere with Four Dimensional Data Assimilation

    Science.gov (United States)

    The physical processes involved in air quality modeling are governed by dynamically-generated meteorological model fields. This research focuses on reducing the uncertainty in the horizontal transport in the lower troposphere by improving the four dimensional data assimilation (F...

  4. Continuous Data Assimilation Using General Interpolant Observables

    CERN Document Server

    Azouani, Abderrahim; Titi, Edriss S

    2013-01-01

    We present a new continuous data assimilation algorithm based on ideas that have been developed for designing finite-dimensional feedback controls for dissipative dynamical systems, in particular, in the context of the incompressible two-dimensional Navier--Stokes equations. These ideas are motivated by the fact that dissipative dynamical systems possess finite numbers of determining parameters (degrees of freedom) such as modes, nodes and local spatial averages which govern their long-term behavior. Therefore, our algorithm allows the use of any type of measurement data for which a general type of approximation interpolation operator exists. Our main result provides conditions, on the finite-dimensional spatial resolution of the collected data, sufficient to guarantee that the approximating solution, obtained by our algorithm from the measurement data, converges to the unknown reference solution over time. Our algorithm is also applicable in the context of signal synchronization in which one can recover, asy...

  5. Assimilation of Unusual Carbon Compounds

    Science.gov (United States)

    Middelhoven, Wouter J.

    Yeast taxa traditionally are distinguished by growth tests on several sugars and organic acids. During the last decades it became apparent that many yeast species assimilate a much greater variety of naturally occurring carbon compounds as sole source of carbon and energy. These abilities are indicative of a greater role of yeasts in the carbon cycle than previously assumed. Especially in acidic soils and other habitats, yeasts may play a role in the degradation of carbon compounds. Such compounds include purines like uric acid and adenine, aliphatic amines, diamines and hydroxyamines, phenolics and other benzene compounds and polysaccharides. Assimilation of purines and amines is a feature of many ascomycetes and basidiomycetes. However, benzene compounds are degraded by only a few ascomycetous yeasts (e.g. the Stephanoascus/ Blastobotrys clade and black yeastlike fungi) but by many basidiomycetes, e.g. Filobasidiales, Trichosporonales, red yeasts producing ballistoconidia and related species, but not by Tremellales. Assimilation of polysaccharides is wide-spread among basidiomycetes

  6. Data Assimilation Cycling for Weather Analysis

    Science.gov (United States)

    Tran, Nam; Li, Yongzuo; Fitzpatrick, Patrick

    2008-01-01

    This software package runs the atmospheric model MM5 in data assimilation cycling mode to produce an optimized weather analysis, including the ability to insert or adjust a hurricane vortex. The program runs MM5 through a cycle of short forecasts every three hours where the vortex is adjusted to match the observed hurricane location and storm intensity. This technique adjusts the surrounding environment so that the proper steering current and environmental shear are achieved. MM5cycle uses a Cressman analysis to blend observation into model fields to get a more accurate weather analysis. Quality control of observations is also done in every cycle to remove bad data that may contaminate the analysis. This technique can assimilate and propagate data in time from intermittent and infrequent observations while maintaining the atmospheric field in a dynamically balanced state. The software consists of a C-shell script (MM5cycle.driver) and three FORTRAN programs (splitMM5files.F, comRegrid.F, and insert_vortex.F), and are contained in the pre-processor component of MM5 called "Regridder." The model is first initialized with data from a global model such as the Global Forecast System (GFS), which also provides lateral boundary conditions. These data are separated into single-time files using splitMM5.F. The hurricane vortex is then bogussed in the correct location and with the correct wind field using insert_vortex.F. The modified initial and boundary conditions are then recombined into the model fields using comRegrid.F. The model then makes a three-hour forecast. The three-hour forecast data from MM5 now become the analysis for the next short forecast run, where the vortex will again be adjusted. The process repeats itself until the desired time of analysis is achieved. This code can also assimilate observations if desired.

  7. Data assimilation in hydrological modelling

    DEFF Research Database (Denmark)

    Drecourt, Jean-Philippe

    Data assimilation is an invaluable tool in hydrological modelling as it allows to efficiently combine scarce data with a numerical model to obtain improved model predictions. In addition, data assimilation also provides an uncertainty analysis of the predictions made by the hydrological model...... with model non-linearities and biased errors. A literature review analyzes the most popular techniques and their application in hydrological modelling. Since bias is an important problem in groundwater modelling, two bias aware Kalman filters have been implemented and compared using an artificial test case...

  8. Storm surge variational assimilation model

    Directory of Open Access Journals (Sweden)

    Shi-li HUANG

    2010-06-01

    Full Text Available To eliminate errors caused by uncertainty of parameters and further improve capability of storm surge forecasting, the variational data assimilation method is applied to the storm surge model based on unstructured grid with high spatial resolution. The method can effectively improve the forecasting accuracy of storm surge induced by typhoon through controlling wind drag force coefficient parameter. The model is first theoretically validated with synthetic data. Then, the real storm surge process induced by the TC 0515 typhoon is forecasted by the variational data assimilation model, and results show the feasibility of practical application.

  9. Oxaliplatin-Induced Tonic-Clonic Seizures

    Directory of Open Access Journals (Sweden)

    Ahmad K. Rahal

    2015-01-01

    Full Text Available Oxaliplatin is a common chemotherapy drug used for colon and gastric cancers. Common side effects are peripheral neuropathy, hematological toxicity, and allergic reactions. A rare side effect is seizures which are usually associated with posterior reversible leukoencephalopathy syndrome (PRES. A 50-year-old male patient presented with severe abdominal pain. CT scan of the abdomen showed acute appendicitis. Appendectomy was done and pathology showed mixed adenoneuroendocrine carcinoma. Adjuvant chemotherapy was started with Folinic acid, Fluorouracil, and Oxaliplatin (FOLFOX. During the third cycle of FOLFOX, the patient developed tonic-clonic seizures. Laboratory workup was within normal limits. EEG and MRI of the brain showed no acute abnormality. The patient was rechallenged with FOLFOX but he had tonic-clonic seizures for the second time. His chemotherapy regimen was switched to Folinic acid, Fluorouracil, and Irinotecan (FOLFIRI. After 5 cycles of FOLFIRI, the patient did not develop any seizures, making Oxaliplatin the most likely culprit for his seizures. Oxaliplatin-induced seizures rarely occur in the absence of PRES. One case report has been described in the literature. We present a rare case of tonic-clonic seizures in a patient receiving Oxaliplatin in the absence of PRES.

  10. Detecting Neonatal Seizures With Computer Algorithms.

    Science.gov (United States)

    Temko, Andriy; Lightbody, Gordon

    2016-10-01

    It is now generally accepted that EEG is the only reliable way to accurately detect newborn seizures and, as such, prolonged EEG monitoring is increasingly being adopted in neonatal intensive care units. Long EEG recordings may last from several hours to a few days. With neurophysiologists not always available to review the EEG during unsociable hours, there is a pressing need to develop a reliable and robust automatic seizure detection method-a computer algorithm that can take the EEG signal, process it, and output information that supports clinical decision making. In this study, we review existing algorithms based on how the relevant seizure information is exploited. We start with commonly used methods to extract signatures from seizure signals that range from those that mimic the clinical neurophysiologist to those that exploit mathematical models of neonatal EEG generation. Commonly used classification methods are reviewed that are based on a set of rules and thresholds that are either heuristically tuned or automatically derived from the data. These are followed by techniques to use information about spatiotemporal seizure context. The usual errors in system design and validation are discussed. Current clinical decision support tools that have met regulatory requirements and are available to detect neonatal seizures are reviewed with progress and the outstanding challenges are outlined. This review discusses the current state of the art regarding automatic detection of neonatal seizures.

  11. Scale invariance properties of intracerebral EEG improve seizure prediction in mesial temporal lobe epilepsy.

    Directory of Open Access Journals (Sweden)

    Kais Gadhoumi

    Full Text Available Although treatment for epilepsy is available and effective for nearly 70 percent of patients, many remain in need of new therapeutic approaches. Predicting the impending seizures in these patients could significantly enhance their quality of life if the prediction performance is clinically practical. In this study, we investigate the improvement of the performance of a seizure prediction algorithm in 17 patients with mesial temporal lobe epilepsy by means of a novel measure. Scale-free dynamics of the intracerebral EEG are quantified through robust estimates of the scaling exponents--the first cumulants--derived from a wavelet leader and bootstrap based multifractal analysis. The cumulants are investigated for the discriminability between preictal and interictal epochs. The performance of our recently published patient-specific seizure prediction algorithm is then out-of-sample tested on long-lasting data using combinations of cumulants and state similarity measures previously introduced. By using the first cumulant in combination with state similarity measures, up to 13 of 17 patients had seizures predicted above chance with clinically practical levels of sensitivity (80.5% and specificity (25.1% of total time under warning for prediction horizons above 25 min. These results indicate that the scale-free dynamics of the preictal state are different from those of the interictal state. Quantifiers of these dynamics may carry a predictive power that can be used to improve seizure prediction performance.

  12. Ionic changes during experimentally induced seizure activity.

    Science.gov (United States)

    Lux, H D; Heinemann, U

    1978-01-01

    Changes in intra- and extracellular ionic activity and their relation to generation and termination of seizure phenomena can be studied with the help of ion-selective microelectrodes. Transient changes in extracellular potassium activity (aK) of the cortex regularly accompany paroxysmal activity induced by electrical stimulation and pentylenetetrazol injections or occur within active penicillin and aluminum foci. A rise of aK from baseline levels of about 3 mmoles/l up to ceiling levels of 8--12 mmoles/l, followed by subnormal K activity, is typically found during seizure discharge. Extracellular K accumulation during seizures facilitates the spread into extrafocal regions. Ceiling levels of extracellular aK are characterized by pronounced K reabsorption which is probably a limiting mechanism for the rise in extracellular aK. It may be a consequence of a simultaneous rise in intracellular Na activity that an electrogenic Na--K exchange process is involved in the termination of ictal activity. Seizures are also accompanied by significant reductions in extracellular Ca2+ activity (aCa) to as low as 0.7 mmoles/l (resting aCa 1.25 mmoles/l). There is no critical level of lowered aCa at which a seizure ultimately results. However, unlike changes in aK reductions in aCa can precede ictal activity. Thus, a fall of aCa occurs before the onset of paroxysmal periods during cyclical spike driving in a penicillin focus and before seizures induced by pentylenetetrazol. Ca2+-dependent mechanisms may contribute to seizure generation. In addition to changes in aK and aCa, intracellular chloride activity (aCl) can increase during seizure activity, as a result of an impaired chloride extrusion mechanism, which would lead to a reduced efficacy of inhibitory synaptic transmission and, therefore, to facilitation of seizure generation.

  13. ATPergic signalling during seizures and epilepsy.

    Science.gov (United States)

    Engel, Tobias; Alves, Mariana; Sheedy, Caroline; Henshall, David C

    2016-05-01

    Much progress has been made over the last few decades in the identification of new anti-epileptic drugs (AEDs). However, 30% of epilepsy patients suffer poor seizure control. This underscores the need to identify alternative druggable neurotransmitter systems and drugs with novel mechanisms of action. An emerging concept is that seizure generation involves a complex interplay between neurons and glial cells at the tripartite synapse and neuroinflammation has been proposed as one of the main drivers of epileptogenesis. The ATP-gated purinergic receptor family is expressed throughout the brain and is functional on neurons and glial cells. ATP is released in high amounts into the extracellular space after increased neuronal activity and during chronic inflammation and cell death to act as a neuro- and gliotransmitter. Emerging work shows pharmacological targeting of ATP-gated purinergic P2 receptors can potently modulate seizure generation, inflammatory processes and seizure-induced brain damage. To date, work showing the functional contribution of P2 receptors has been mainly performed in animal models of acute seizures, in particular, by targeting the ionotropic P2X7 receptor subtype. Other ionotropic P2X and metabotropic P2Y receptor family members have also been implicated in pathological processes following seizures such as the P2X4 receptor and the P2Y12 receptor. However, during epilepsy, the characterization of P2 receptors was mostly restricted to the study of expressional changes of the different receptor subtypes. This review summarizes the work to date on ATP-mediated signalling during seizures and the functional impact of targeting the ATP-gated purinergic receptors on seizures and seizure-induced pathology. This article is part of the Special Issue entitled 'Purines in Neurodegeneration and Neuroregeneration'.

  14. Efficacy of lacosamide by focal seizure subtype.

    Science.gov (United States)

    Sperling, Michael R; Rosenow, Felix; Faught, Edward; Hebert, David; Doty, Pamela; Isojärvi, Jouko

    2014-10-01

    The purpose of this post hoc exploratory analysis was to determine the effects of the antiepileptic drug, lacosamide, on focal (partial-onset) seizure subtypes. Patient data from the three lacosamide pivotal trials were grouped and pooled by focal seizure subtype at Baseline: simple partial seizures (SPS), complex partial seizures (CPS), and secondarily generalized partial seizures (SGPS). Both efficacy outcomes (median percent change from Baseline to Maintenance Phase in seizure frequency per 28 days and the proportion of patients experiencing at least a 50% reduction in seizures) were evaluated by lacosamide dose (200, 400, or 600 mg/day) compared to placebo for each seizure subtype. An additional analysis was performed to determine whether a shift from more severe focal seizure subtypes to less severe occurred upon treatment with lacosamide. In patients with CPS or SGPS at Baseline, lacosamide 400 mg/day (maximum recommended daily dose) and 600 mg/day reduced the frequency of CPS and SGPS compared to placebo. Likewise, a proportion of patients with CPS and SGPS at Baseline experienced at least a 50% reduction in the frequency of CPS and SGPS (≥50% responder rate) in the lacosamide 400 and 600 mg/day groups compared with placebo. For both outcomes, numerically greatest responses were observed in the lacosamide 600 mg/day group among patients with SGPS at Baseline. In patients with SPS at Baseline, no difference between placebo and lacosamide was observed for either efficacy outcome. An additional exploratory analysis suggests that in patients with SPS at Baseline, CPS and SGPS may have been shifted to less severe SPS upon treatment with lacosamide. The results of these exploratory analyses revealed reductions in CPS and SGPS frequency with adjunctive lacosamide. Reduction in CPS and SGPS may confound assessment of SPS since the CPS or SGPS may possibly change to SPS by effective treatment.

  15. Biotelemetry system for Epilepsy Seizure Control

    Energy Technology Data Exchange (ETDEWEB)

    Smith, LaCurtise; Bohnert, George W.

    2009-07-02

    The Biotelemetry System for Epilepsy Seizure Control Project developed and tested an automated telemetry system for use in an epileptic seizure prevention device that precisely controls localized brain temperature. This project was a result of a Department of Energy (DOE) Global Initiatives for Proliferation Prevention (GIPP) grant to the Kansas City Plant (KCP), Argonne National Laboratory (ANL), and Pacific Northwest National Laboratory (PNNL) to partner with Flint Hills Scientific, LLC, Lawrence, KS and Biophysical Laboratory Ltd (BIOFIL), Sarov, Russia to develop a method to help control epileptic seizures.

  16. Folinic acid-responsive seizures initially responsive to pyridoxine.

    NARCIS (Netherlands)

    Nicolai, J.; Kranen-Mastenbroek, V.H. van; Wevers, R.A.; Hurkx, W.A.; Vles, J.S.

    2006-01-01

    This report presents a male who developed clonic seizures on the day he was born. The next day, the diagnosis of pyridoxine-dependent seizures was made. However, contradictory to this diagnosis, seizures reappeared despite treatment with pyridoxine. Seizures ceased after folinic acid was initiated.

  17. Febrile Seizure: Demographic Features and Causative Factors

    Directory of Open Access Journals (Sweden)

    Hamed ESMAILI GOURABI

    2013-01-01

    Full Text Available How to cite this article: Esmaili Gourabi H, Bidabadi E, Cheraghalipour  F, Aarabi  Y, Salamat F. Febrile Seizure: Demographic Features and Causative Factors. Iran J Child Neurol Autumn 2012; 6(4:33-37.Abstract Objective Because of geographical and periodical variation, we prompted to determine the demographic features and causative factors for febrile seizure in Rasht. Materials & Methods In this cross-sectional study, all 6–month- to 6-year-old children with the diagnosis of febrile seizure admitted to 17 Shahrivar hospital in Rasht, from August, 2009 to August, 2010 were studied. Age, sex, family history of the disease, seizure types, body temperature upon admission and infectious causes of the fever were recorded. All statistical analysis was performed with SPSS software, version 16. Results Of the 214 children (mean age, 25.24±15.40 months, 124 were boys and 109 had a positive family history. Complex seizures were seen in 39 cases. In patients with a complex febrile seizure, 59% had the repetitive type, 20.5% had the focal type and 20.5% had more than 15 minutes duration of seizures. Most of the repetitive seizures (78.3% occurred in patients under 2 years old; the difference between under and over 2-year-old patients was statistically significant (P=0.02. Study results did not show significant differences between the two genders for simple or complex seizures. The mean body temperature upon admission was 38.2±1.32◦C (38.31±0.82 degrees in boys and 38.04±1.78 in girls. Upper respiratory infections were seen in most patients (74.29%. All cases of lower respiratory infections were boys. There was a statistically significant difference between boys and girls in causes of fever. Conclusion Most of the children had a positive family history and the most common causative factor was upper respiratory infection.  References: Huang MC, Huang CC, Thomas K. Febrile convulsions: development and validation of a questionnaire to measure

  18. Assimilative modeling of low latitude ionosphere

    Science.gov (United States)

    Pi, Xiaoqing; Wang, Chunining; Hajj, George A.; Rosen, I. Gary; Wilson, Brian D.; Mannucci, Anthony J.

    2004-01-01

    In this paper we present an observation system simulation experiment for modeling low-latitude ionosphere using a 3-dimensional (3-D) global assimilative ionospheric model (GAIM). The experiment is conducted to test the effectiveness of GAIM with a 4-D variational approach (4DVAR) in estimation of the ExB drift and thermospheric wind in the magnetic meridional planes simultaneously for all longitude or local time sectors. The operational Global Positioning System (GPS) satellites and the ground-based global GPS receiver network of the International GPS Service are used in the experiment as the data assimilation source. 'The optimization of the ionospheric state (electron density) modeling is performed through a nonlinear least-squares minimization process that adjusts the dynamical forces to reduce the difference between the modeled and observed slant total electron content in the entire modeled region. The present experiment for multiple force estimations reinforces our previous assessment made through single driver estimations conducted for the ExB drift only.

  19. Data assimilation applied to a chaotic toy climate

    CERN Document Server

    Harris, Kameron Decker; Hitt, Darren L; Danforth, Christopher M

    2011-01-01

    A simplified model of natural convection, similar to the 1963 Lorenz system, is derived and compared to computational fluid dynamics simulations as a test bed for data assimilation methods. The thermosyphon is represented by a long time flow simulation, which serves as a reference "truth". Forecasts are then made using the Lorenz-like model and synchronized to noisy and limited observations of the truth, a realistic \\textit{in silico} forecasting scenario, using three dimensional variational filtering, the extended Kalman filter, the ensemble square root filter, and the ensemble transform Kalman filter. We find that these data assimilation algorithms successfully couple the simplified model to observations of the computational fluid dynamics simulation and, in fact, can infer dynamics absent from the model.

  20. Two types of parasitic assimilation

    Directory of Open Access Journals (Sweden)

    Peter Jurgec

    2013-02-01

    Full Text Available This paper shows that consonant harmony and parasitic vowel harmony are more similar than previously assumed. I provide a unified and restrictive analysis of parasitic assimilation using feature spreading constraints. In particular, I attribute the differences between the attested and unattested patterns to two types of markedness constraints—alignment and agreement.

  1. Assimilation of Unusual Carbon Compounds

    NARCIS (Netherlands)

    Middelhoven, W.J.

    2009-01-01

    Yeast taxa traditionally are distinguished by growth tests on several sugars and organic acids. During the last decades it became apparent that many yeast species assimilate a much greater variety of naturally occurring carbon compounds as sole source of carbon and energy. These abilities are indica

  2. The Phonological Assimilation of Borrowing.

    Science.gov (United States)

    Suleiman, Saleh M.

    Linguistic borrowing from English to Jordanian Arabic at the lexical level is described, focusing on phonology and the extent to which Jordanian Arabic has affected the phonetic structure of English loans assimilated partially or completely into it. Conspicuous distinctive sound features in the two languages that may affect non-native speakers'…

  3. Detection of Epileptic Seizures with Multi-modal Signal Processing

    DEFF Research Database (Denmark)

    Conradsen, Isa

    and alarm whenever a seizure starts is of great importance to these patients and their relatives, in the sense, that the alert of the seizure will make them feel more safe. Thus the objective of the project is to investigate the movements of convulsive epileptic seizures and design seizure detection...... convulsive seizures tested. Another study was performed, involving quantitative parameters in the time and frequency domain. The study showed, that there are several differences between tonic seizures and the tonic phase of GTC seizures and furthermore revealed differences of the epileptic (tonic and tonic...

  4. Direct variational data assimilation algorithm for atmospheric chemistry data with transport and transformation model

    Science.gov (United States)

    Penenko, Alexey; Penenko, Vladimir; Nuterman, Roman; Baklanov, Alexander; Mahura, Alexander

    2015-11-01

    Atmospheric chemistry dynamics is studied with convection-diffusion-reaction model. The numerical Data Assimilation algorithm presented is based on the additive-averaged splitting schemes. It carries out ''fine-grained'' variational data assimilation on the separate splitting stages with respect to spatial dimensions and processes i.e. the same measurement data is assimilated to different parts of the split model. This design has efficient implementation due to the direct data assimilation algorithms of the transport process along coordinate lines. Results of numerical experiments with chemical data assimilation algorithm of in situ concentration measurements on real data scenario have been presented. In order to construct the scenario, meteorological data has been taken from EnviroHIRLAM model output, initial conditions from MOZART model output and measurements from Airbase database.

  5. Ocean Data Assimilation in Support of Climate Applications: Status and Perspectives.

    Science.gov (United States)

    Stammer, D; Balmaseda, M; Heimbach, P; Köhl, A; Weaver, A

    2016-01-01

    Ocean data assimilation brings together observations with known dynamics encapsulated in a circulation model to describe the time-varying ocean circulation. Its applications are manifold, ranging from marine and ecosystem forecasting to climate prediction and studies of the carbon cycle. Here, we address only climate applications, which range from improving our understanding of ocean circulation to estimating initial or boundary conditions and model parameters for ocean and climate forecasts. Because of differences in underlying methodologies, data assimilation products must be used judiciously and selected according to the specific purpose, as not all related inferences would be equally reliable. Further advances are expected from improved models and methods for estimating and representing error information in data assimilation systems. Ultimately, data assimilation into coupled climate system components is needed to support ocean and climate services. However, maintaining the infrastructure and expertise for sustained data assimilation remains challenging.

  6. Cyclosporin A acute encephalopathy and seizure syndrome in childhood: clinical features and risk of seizure recurrence.

    Science.gov (United States)

    Gleeson, J G; duPlessis, A J; Barnes, P D; Riviello, J J

    1998-07-01

    Cyclosporin A is associated with an acute encephalopathy including seizures and alterations in mental status, herein referred to as cyclosporin A acute encephalopathy and seizure syndrome. The clinical history, electroencephalogram (EEG), and neuroimaging findings in 19 children with cyclosporin A acute encephalopathy and seizure syndrome over a 10-year period were reviewed in order to delineate clinical characteristics, imaging features, and to determine the risk of seizure recurrence in this population. All 19 had motor seizures associated with other features of cortical and subcortical dysfunction. The acute mean cyclosporin A level was 342 microg/L, but was within the "therapeutic" range in five cases. Brain imaging by computed tomography (CT) or magnetic resonance imaging (MRI) in the acute or subacute phase revealed lesions characteristic of cyclosporin A toxicity in 14 cases. Acute EEG abnormalities were present in all and included epileptiform discharges or focal slowing. Patients were followed for a median of 49 months (1-9 years). Follow-up imaging (n = 10) showed lesion resolution or improvement in the majority while EEG (n = 10) had normalized in only three. Seizures recurred in six patients and only in those with persistent EEG or imaging abnormalities. No patient had a second episode of cyclosporin A associated neurotoxicity or seizure. It appears that a significant risk of seizure recurrence exists following cyclosporin A acute encephalopathy and seizure syndrome and primarily in those children with persistent EEG or imaging abnormalities.

  7. Serum Prolactin in Diagnosis of Epileptic Seizures

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2005-09-01

    Full Text Available The results of studies in databases and references concerning serum prolactin levels (PRL in patients with suspected seizures were rated for quality and analyzed by members of the Therapeutics Subcommittee of the American Academy of Neurology.

  8. Recurrence Within 24 Hours of Unprovoked Seizures

    Directory of Open Access Journals (Sweden)

    J Gordon Millichap

    2006-09-01

    Full Text Available The incidence and risk factors of acute recurrence of unprovoked seizures within 24 hours of admission to an Emergency Department (ED were analyzed by a retrospective chart review at Schneider Children’s Hospital, New York.

  9. Genetics Home Reference: benign familial neonatal seizures

    Science.gov (United States)

    ... Facebook Share on Twitter Your Guide to Understanding Genetic Conditions Search MENU Toggle navigation Home Page Search ... Conditions Genes Chromosomes & mtDNA Resources Help Me Understand Genetics Home Health Conditions BFNS benign familial neonatal seizures ...

  10. Sheehan's syndrome presenting as postpartum seizures.

    Science.gov (United States)

    Jain, G; Singh, D; Kumar, S

    2010-05-01

    We report a case where a patient presented with generalised tonic-clonic seizures secondary to nausea, vomiting and dehydration. She had suffered a postpartum haemorrhage six months previously. On laboratory assessment hyponatraemia and low hormone concentrations suggested pituitary failure. The diagnosis was confirmed by magnetic resonance imaging of the head, which showed a partially empty sella turcica. Given the severity of the morbidity in this case we emphasise that Sheehan's syndrome should be suspected in women presenting with postpartum seizures.

  11. Febrile seizures: A review for family physicians

    OpenAIRE

    2007-01-01

    Febrile seizures are the most common cause of convulsions in children. Most are simple in nature, although those with focal onset, prolonged duration (³15 min) or those that recur within 24 h or within the same febrile illness are considered complex. Diagnosis of this condition is essentially clinical and based on its description provided by parents. Its pathophysiology remains unclear, but genetics plays a major role in conferring susceptibility. Although most febrile seizures are ben...

  12. The lunar cycle and seizures in children

    Directory of Open Access Journals (Sweden)

    Devleta Hadžić

    2010-08-01

    Full Text Available Aim To analyze the annual trend of hospitalization and potential influence of the lunar cycle of children treated for seizures.Methods The data of the patients treated for seizures (convulsions, epileptic seizures, disturbance of consciousness and epileptic seizures in children with neurodevelopmental disability in the Pediatrics Clinic of the University Clinical Center of Tuzla were retrospectively analyzed during 2008 in relation to seasonaldistribution, admission time (month, week, admission moment, day in a week, time of the day and the lunar cycle. Results Out f the totalof 234 treated children, 55 (23,5% were infants, 101 (43,1% were under six years of age and 78 (33,3% were of school age. The most common type of seizures were convulsions, 123 (42,6%. The seizures were numerous in the midst of the week, as opposed to weekends. Thein the midst of the week, as opposed to weekends. The highest number of children was treated in January, February, July and August, that it, in the fourth, seventh, twenty-seventh and thirty-first week of the year. Seizures occured during the day in 149 patients (63,7% and during the night in 84 (35,9% patients (p < 0,0034. The number of treated patients was significantly larger in the third and fourthlunar phases (p < 0,018. Conclusion The results suggested seasonal and weekly trends of hospitalization of patients with seizures and their relation with circadian and lunar cycles. There is a need for further prospective studies in order to get better understanding of the influence of the lunar cycle on health.

  13. Febrile Seizure: Demographic Features and Causative Factors

    Directory of Open Access Journals (Sweden)

    Hamed ESMAILI GOURABI

    2012-10-01

    Full Text Available ObjectiveBecause of geographical and periodical variation, we prompted to determine the demographic features and causative factors for febrile seizure in Rasht.Materials & MethodsIn this cross-sectional study, all 6–month- to 6-year-old children with the diagnosis of febrile seizure admitted to 17 Shahrivar hospital in Rasht, from August, 2009 to August, 2010 were studied. Age, sex, family history of the disease, seizure types, body temperature upon admission and infectious causes of the fever were recorded. All statistical analysis was performed with SPSS software, version 16.ResultsOf the 214 children (mean age, 25.24±15.40 months, 124 were boys and 109 had a positive family history. Complex seizures were seen in 39 cases. In patients with a complex febrile seizure, 59% had the repetitive type, 20.5% had the focal type and 20.5% had more than 15 minutes duration of seizures. Most of the repetitive seizures (78.3% occurred in patients under 2 years old; the difference between under and over 2-year-old patients was statistically significant (P=0.02. Study results did not show significant differences between the two genders for simple or complex seizures. The mean body temperature upon admission was 38.2±1.32◦C (38.31±0.82 degrees in boys and 38.04±1.78 in girls. Upper respiratory infections were seen in most patients (74.29%. All cases of lower respiratory infections were boys. There was a statistically significant difference between boys and girls in causes of fever.ConclusionMost of the children had a positive family history and the most common causative factor was upper respiratory infection.

  14. Seizure characteristics in multiple sclerosis patients

    Directory of Open Access Journals (Sweden)

    Vahid Shaygannejad

    2013-01-01

    Full Text Available Background: To evaluate seizure characteristic among multiple sclerosis patients with coexistent seizure activity compared to control group. Materials and Methods : This study is a cross-sectional study which was conducted by reviewing the clinical records of patients with definite diagnosis of MS according to McDonald′s criteria from March 2007 to June 2011, who referred to the MS clinic of the university. Results : A total of 920 patients with a diagnosis of MS were identified, among whom 29 patients (3.15% with seizure activity (case due to MS with the mean age of 32.6 ± 6.23 years were analyzed. Also, fifty MS patients without any seizure occurrence with the mean age of 33.7 ± 7.4 years were used as our control group. In case group, seizure was general tonic clonic in 23 patients (79.3%, complex partial in four (13.8%, and simple partial in two (5.9%. The 26 available interictal EEGs in MS patients showed abnormal EEG pattern in 22 (84.6% of them, including focal epileptic form discharge or focal slowing in 10 (38.5%, generalized discharge (spike-wave, polyspike, or general paroxysmal fast activity in 10 (38.5%, and general slowing activity in 10 record (38.5%. MRI reviews of the 26 available brain MRIs showed subcortical white mater lesions in 22 (84.6% of patients with seizure. All MRIs were performed within one month after the first seizure episode. Amongst 48 available MRIs in our control group, 91.7% (44 cases showed periventricular lesions and in 8.3% (4 cases subcortical white matter lesions were reported. Conclusion : The result of this study demonstrated the higher rate of subcortical whit matter lesion in MS patients with seizure occurrence compared to control group.

  15. Occipital seizures presenting with bilateral visual loss

    Directory of Open Access Journals (Sweden)

    Hadjikoutis S

    2003-01-01

    Full Text Available Transient visual loss may occur with occipital seizures as an ictal or post-ictal phenomenon. Its duration varies from less than one minute to days, or can be permanent. We describe a 61-year-old man presenting with headache, vomiting and bilateral visual loss. EEG revealed persistent spike discharge in the occipital lobes suggesting occipital seizures. His vision improved with carbamazepine.

  16. Seizures in horses: diagnosis and classification

    Directory of Open Access Journals (Sweden)

    Lacombe VA

    2015-10-01

    Full Text Available Véronique A Lacombe Department of Physiological Sciences, Oklahoma State University Center for Veterinary Health Sciences, Stillwater, OK, USA Abstract: Seizures are a diverse and very common set of chronic neurologic disorders in humans and dogs but are less common in horses. Seizures refer to a specific clinical event (described as sudden and severe regardless of the etiology, which includes both intracranial and extracranial causes. Therefore, after briefly reviewing some definitions, this article aims to describe the use of a standardized classification, which could facilitate a logical approach for the clinician to establish a diagnosis, as well as to use a consistent mode of communication. For instance, seizures can be classified by type (ie, focal vs generalized or etiology (ie, reactive, symptomatic, cryptogenic, idiopathic. In particular, epilepsy, a brain disorder characterized by recurrent seizures can be classified as primary (ie, genetic origin or secondary (ie, acquired. This review further discusses the limitations associated with the clinical workup of horses with seizures. This is germane to the fact that the identification of the underlying cause remains challenging due to the technical limitations of imaging the equine adult brain. Indeed, as in man and dogs, epilepsies of unknown cause (ie, cryptogenic account for the majority of all epilepsies. Therefore, although electroencephalography and advanced brain imaging techniques (eg, computed tomography and magnetic resonance imaging are becoming increasingly available, information obtained from the history, physical, and neurologic examinations and progression of clinical signs and response to treatment remain essential in the workup of horses with seizures. Keywords: focal seizure, generalized seizure, symptomatic, cryptogenic, electroencephalography, computed tomography

  17. Assimilation of drifter observations for the reconstruction of eulerian circulation field.

    Science.gov (United States)

    Molcard, A.; Ozgokmen, T.; Piterbarg, L.; Griffa, A.

    2003-04-01

    In light of the increasing number of drifting buoys in the ocean, and recent advances in the realism of ocean general circulation models toward oceanic forecasting, the problem of assimilation of Lagrangian observations data in Eulerian models is investigated. A new and general rigorous approach is developed based on optimal interpolation methods, which takes into account directly the Lagrangian nature of the observations. An idealized version of this general formulation is tested in the framework of identical twin-experiments using a reduced-gravity, quasi-geostrophic model. An extensive study is conducted to quantify the effectiveness of Lagrangian data assimilation as a function of the number of drifters, the frequency of assimilation and uncertainties associated with the forcing functions driving the ocean model. The performance of the Lagrangian assimilation technique is also compared to that of conventional methods of assimilating drifters as moving current meters, and assimilation of Eulerian data, such as fixed-point velocities. Overall the results are very favorable for the assimilation of Lagrangian observations to improve the Eulerian velocity field in ocean models. The results of our assimilation twin experiments imply an optimal sampling frequency for oceanic Lagrangian instruments in the range of 20-50% of the Lagrangian integral time scale of the flow field. The method is extended to primitive equation ocean models by using a dynamical relationship between velocity components and layer thickness based on geostrophy. The method is implemented in an idealized MICOM of midlatitude circulation, and performances of three different techniques, Pseudo-Lagrangian OI, Lagrangian OI and Pseudo-Lagrangian Kalman Filter (based on Chin et al., 1999) are compared using a comprehensive set of experiments. The main finding of this study is that two different strategies of data assimilation are simultaneously supported: (i) the strategy of adopting well

  18. Genetic effects on sleep/wake variation of seizures

    Science.gov (United States)

    Winawer, Melodie R.; Shih, Jerry; Beck, Erin S.; Hunter, Jessica E.; Epstein, Michael P.

    2016-01-01

    Summary Objective There is a complex bidirectional relationship between sleep and epilepsy. Sleep/wake timing of seizures has been investigated for several individual seizure types and syndromes, but few large-scale studies of the timing of seizures exist in people with varied epilepsy types. In addition, the genetic contributions to seizure timing have not been well studied. Methods Sleep/wake timing of seizures was determined for 1,395 subjects in 546 families enrolled in the Epilepsy Phenome/Genome Project (EPGP). We examined seizure timing among subjects with different epilepsy types, seizure types, epilepsy syndromes, and localization. We also examined the familial aggregation of sleep/wake occurrence of seizures. Results Seizures in nonacquired focal epilepsy (NAFE) were more likely to occur during sleep than seizures in generalized epilepsy (GE), for both convulsive (odds ratio [OR] 5.2, 95% confidence interval [CI] 3.59–7.52) and nonconvulsive seizures (OR 4.2, 95% CI 2.48–7.21). Seizures occurring within 1 h of awakening were more likely to occur in patients with GE than with NAFE for both convulsive (OR 2.3, 95% CI 1.54– 3.39) and nonconvulsive (OR 1.7, 95% CI 1.04–2.66) seizures. Frontal onset seizures were more likely than temporal onset seizures to occur during sleep. Sleep/wake timing of seizures in first-degree relatives predicted timing of seizures in the proband. Significance We found that sleep/wake timing of seizures is associated with both epilepsy syndrome and seizure type. In addition, we provide the first evidence for a genetic contribution to sleep/wake timing of seizures in a large group of individuals with common epilepsy syndromes. PMID:26948972

  19. Childhood epileptic seizures imitating migraine and encephalitis

    Directory of Open Access Journals (Sweden)

    Kravljanac Ružica

    2012-01-01

    Full Text Available Introduction. Paroxismal events can resemble epileptic seizures, however, some epileptic seizures, especially benign occipital childhood epilepsies can imitate migraine, cycling vomiting or encephalitis. Objective. The aim of this study was evaluation of clinical and electroencephalographic (EEG features and outcome in children with benign occipital childhood epilepsies. Methods. Investigation included 18 patients with benign occipital childhood epilepsies hospitalized in the period from 2007 to 2010. The diagnosis was based on clinical and EEG characteristics of seizures, while treatment included acute therapy for seizures and chronic antiepileptic drugs. Prognosis was analyzed in terms of neurological outcome and seizure recurrence rate. Results. Benign occipital childhood epilepsy with early onset was diagnosed in 15 children. Vegetative symptoms, mostly ictal vomiting (13, eye deviation and loss of consciousness (13 dominated in the clinical presentation. The most frequent EEG findings showed occipital epileptic discharges. Benign occipital childhood epilepsy with late onset was diagnosed in three cases. Seizures were manifested by visual hallucinations, headache and secondary generalized convulsions. All three patients were administered chronic antiepileptic drugs and had good outcome. Conclusion. In our patients, clinical manifestations of benign occipital epilepsies had some similarities with clinical features of migraine and encephalitis. It could explain misdiagnosis in some of them. Knowledge about main features and differences between each of these disorders is crucial for making appropriate diagnosis.

  20. Febrile Seizures: Four Steps Algorithmic Clinical Approach

    Directory of Open Access Journals (Sweden)

    Mahmoud Mohammadi

    2010-03-01

    Full Text Available Febrile seizures (FS are the most common form of convulsive phenomena in human being and affect 2% to 14% of children. It is the most common type of seizures that every pediatrician is dealing with. It is the most benign type of all seizures occurring in childhood. There are many debates on how to approach to febrile seizures in pediatric neurology and there are many possible malpractices in this field. Some of the most common frequent queries are -How could we differentiate FS from seizures and fever associated with serious infections involving the central nervous system? - When should we refer the affected child for further investigations such as lumbar puncture, EEG, neuroimaging, and routine biochemical studies? - How should we treat FS in its acute phase? - How could we assess the risk for further recurrences as well as other risks threatening the childs health in future? - How could we select the patients for treatment or prophylaxis? - Which medication(s should be selected for treatment or prophylaxis? Trying to answer the above-mentioned questions, this review article will present a four steps algorithmic clinical approach model to a child with febrile seizures based on the current medical literature.

  1. Millimeter-scale epileptiform spike propagation patterns and their relationship to seizures

    Science.gov (United States)

    Vanleer, Ann C.; Blanco, Justin A.; Wagenaar, Joost B.; Viventi, Jonathan; Contreras, Diego; Litt, Brian

    2016-04-01

    Objective. Current mapping of epileptic networks in patients prior to epilepsy surgery utilizes electrode arrays with sparse spatial sampling (∼1.0 cm inter-electrode spacing). Recent research demonstrates that sub-millimeter, cortical-column-scale domains have a role in seizure generation that may be clinically significant. We use high-resolution, active, flexible surface electrode arrays with 500 μm inter-electrode spacing to explore epileptiform local field potential (LFP) spike propagation patterns in two dimensions recorded from subdural micro-electrocorticographic signals in vivo in cat. In this study, we aimed to develop methods to quantitatively characterize the spatiotemporal dynamics of epileptiform activity at high-resolution. Approach. We topically administered a GABA-antagonist, picrotoxin, to induce acute neocortical epileptiform activity leading up to discrete electrographic seizures. We extracted features from LFP spikes to characterize spatiotemporal patterns in these events. We then tested the hypothesis that two-dimensional spike patterns during seizures were different from those between seizures. Main results. We showed that spatially correlated events can be used to distinguish ictal versus interictal spikes. Significance. We conclude that sub-millimeter-scale spatiotemporal spike patterns reveal network dynamics that are invisible to standard clinical recordings and contain information related to seizure-state.

  2. Ensemble Optimal Interpolation Data Assimilation of Surface Currents by Utilizing Monte Carlo Simulation

    Science.gov (United States)

    Hartnett, Michael; Ren, Lei

    2013-04-01

    This paper describes the application of Ensemble Optimal Interpolation (EnOI) with Monte Carlo (MC) simulation for surface currents forecasting. Environment Fluid Dynamics Codes (EFDC) is run for 7 days with initial conditions and boundary conditions. For the assimilation process, Direct Insertion (DI), Optimal Interpolation (OI) and Ensemble Optimal Interpolation (EnOI) approaches are applied from t=5.0d, and wind forcing is switched off during updating process. For Optimal Interpolation, background error covariance is estimated from the first run combining empirical correlation function, while for Ensemble Optimal Interpolation, background error covariance is calculated from the ensemble of first run, optimal number of ensemble is acquired by comparing different assimilation. Different strategies have been proposed to obtain the measurement error covariance, optimal measurement error covariance gives the least forecast error. Different kinds of pseudo measurements are produced from Monte Carlo simulation by adding different type of perturbations, which obey certain distribution. A series of experiments with distinct perturbations are carried out to show the improvement of simulating the stochastic process. Three types of reference points: inside of the assimilation area, outside of the assimilation area, and the boundary points are analyzed to show the improvement of the assimilation process and the influence after assimilation. This study also investigates the impacts of the updating interval for the assimilation process, the felicitous updating interval is chosen by comparison. To compare the improvement of operating Ensemble Optimal Interpolation with Direct Insertion and Optimal Interpolation, RMS error and data assimilation skill are calculated.

  3. Development of a Chinese land data assimilation system: its progress and prospects

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The objective of land data assimilation is to merge multi-source observations into the dynamics of land surface model for improving the estimation of land surface states. We have developed a land data assimilation system for China's land territory. In this system, the Common Land Model and Simple Biosphere Model 2 are used to simulate land surface processes. The radiative transfer models of thawed and frozen soil, snow, lake, and vegetation are used as observation operators to transfer model predictions into estimated brightness temperatures. A Monte-Carlo based sequential filter, the ensemble Kalman filter, is implemented as data assimilation method to integrate modeling and observation. The system is capable of assimilating passive microwave remotely sensed data such as special sensor microwave/imager (SSM/I), TRMM microwave imager (TMI), and advanced microwave scanning radiometer enhanced for EOS (AMSRE) and the conventional in situ measurements of soil and snow. A spatiotemporally consistent assimilated dataset for soil moisture, soil temperature, snow and frozen soil, with a spatial resolution of 0.25 degree and temporal resolution of one hour, has been produced. This paper introduces the development of Chinese land data assimilation system and the progress made on data assimilation algorithms, land surface modeling, microwave remote sensing of land surface hydrological variables, and the preparation of atmospheric forcing data. The distinct characteristics and challenges of developing land data assimilation system and the perspectives for future development are also discussed .

  4. At first glance, transparency enhances assimilation.

    Science.gov (United States)

    Koning, Arno; de Weert, Charles M M; van Lier, Rob

    2008-01-01

    We investigated the role of transparency, perceptual grouping, and presentation time on perceived lightness. Both transparency and perceptual grouping have been found to result in assimilation effects, but only for ambiguous stimulus displays and with specific attentional instructions. By varying the presentation times of displays with two partly overlapping transparent E-shaped objects, we measured assimilation in unambiguous stimulus displays and without specific attentional instructions. The task was to judge which of two simultaneously presented E-shaped objects was darker. With unrestrained presentation times, if a transparency interpretation was possible, assimilation was not found. Inhibiting a transparency interpretation by occluding the local junctions between the two E-shaped objects, did lead to assimilation. With short presentation times, if a transparency interpretation was possible, assimilation was now also found. Thus, we conclude that, although transparency appears to enhance assimilation, with unambiguous stimulus displays and without specific attentional instructions, perceptual grouping is more important for assimilation to occur.

  5. Snow multivariable data assimilation for hydrological predictions in mountain areas

    Science.gov (United States)

    Piazzi, Gaia; Campo, Lorenzo; Gabellani, Simone; Rudari, Roberto; Castelli, Fabio; Cremonese, Edoardo; Morra di Cella, Umberto; Stevenin, Hervé; Ratto, Sara Maria

    2016-04-01

    The seasonal presence of snow on alpine catchments strongly impacts both surface energy balance and water resource. Thus, the knowledge of the snowpack dynamics is of critical importance for several applications, such as water resource management, floods prediction and hydroelectric power production. Several independent data sources provide information about snowpack state: ground-based measurements, satellite data and physical models. Although all these data types are reliable, each of them is affected by specific flaws and errors (respectively dependency on local conditions, sensor biases and limitations, initialization and poor quality forcing data). Moreover, there are physical factors that make an exhaustive reconstruction of snow dynamics complicated: snow intermittence in space and time, stratification and slow phenomena like metamorphism processes, uncertainty in snowfall evaluation, wind transportation, etc. Data Assimilation (DA) techniques provide an objective methodology to combine observational and modeled information to obtain the most likely estimate of snowpack state. Indeed, by combining all the available sources of information, the implementation of DA schemes can quantify and reduce the uncertainties of the estimations. This study presents SMASH (Snow Multidata Assimilation System for Hydrology), a multi-layer snow dynamic model, strengthened by a robust multivariable data assimilation algorithm. The model is physically based on mass and energy balances and can be used to reproduce the main physical processes occurring within the snowpack: accumulation, density dynamics, melting, sublimation, radiative balance, heat and mass exchanges. The model is driven by observed forcing meteorological data (air temperature, wind velocity, relative air humidity, precipitation and incident solar radiation) to provide a complete estimate of snowpack state. The implementation of an Ensemble Kalman Filter (EnKF) scheme enables to assimilate simultaneously ground

  6. Assimilation of remote sensing observations into a sediment transport model of China's largest freshwater lake: spatial and temporal effects.

    Science.gov (United States)

    Zhang, Peng; Chen, Xiaoling; Lu, Jianzhong; Zhang, Wei

    2015-12-01

    Numerical models are important tools that are used in studies of sediment dynamics in inland and coastal waters, and these models can now benefit from the use of integrated remote sensing observations. This study explores a scheme for assimilating remotely sensed suspended sediment (from charge-coupled device (CCD) images obtained from the Huanjing (HJ) satellite) into a two-dimensional sediment transport model of Poyang Lake, the largest freshwater lake in China. Optimal interpolation is used as the assimilation method, and model predictions are obtained by combining four remote sensing images. The parameters for optimal interpolation are determined through a series of assimilation experiments evaluating the sediment predictions based on field measurements. The model with assimilation of remotely sensed sediment reduces the root-mean-square error of the predicted sediment concentrations by 39.4% relative to the model without assimilation, demonstrating the effectiveness of the assimilation scheme. The spatial effect of assimilation is explored by comparing model predictions with remotely sensed sediment, revealing that the model with assimilation generates reasonable spatial distribution patterns of suspended sediment. The temporal effect of assimilation on the model's predictive capabilities varies spatially, with an average temporal effect of approximately 10.8 days. The current velocities which dominate the rate and direction of sediment transport most likely result in spatial differences in the temporal effect of assimilation on model predictions.

  7. Treatment of partial seizures and seizure-like activity with felbamate in six dogs.

    Science.gov (United States)

    Ruehlmann, D; Podell, M; March, P

    2001-08-01

    Six dogs with partial seizures or partial seizure-like activity were treated with the antiepileptic drug felbamate between 1993 and 1998. All dogs had a history and results of diagnostic testing suggestive of either primary (idiopathic) or occult secondary epilepsy. Dogs ranged between four months and eight years of age at the onset of seizure activity. The median time period between onset of the first seizure and the start of felbamate therapy was 3.8 months (range 0.75 to 36 months). Median duration of therapy was nine months (range two to 22 months). All dogs experienced a reduction in seizure frequency after felbamate administration. Median total number of seizures post-treatment was two (range 0 to 9). Two dogs had an immediate and prolonged cessation of seizure activity. Steady-state trough serum felbamate concentrations measured at two weeks, and one, 12 and 22 months after the commencement of therapy in four dogs ranged between 13 and 55 mg/litre (median 35 mg/litre). Reversible haematological adverse effects were detected in two dogs, with one dog developing concurrent keratoconjunctivitis sicca. These results suggest that felbamate can be an effective antiepileptic drug without life-threatening complications when used as monotherapy for partial seizures in the dog.

  8. Assimilation of nitrate by yeasts.

    Science.gov (United States)

    Siverio, José M

    2002-08-01

    Nitrate assimilation has received much attention in filamentous fungi and plants but not so much in yeasts. Recently the availability of classical genetic and molecular biology tools for the yeast Hansenula polymorpha has allowed the advance of the study of this metabolic pathway in yeasts. The genes YNT1, YNR1 and YNI1, encoding respectively nitrate transport, nitrate reductase and nitrite reductase, have been cloned, as well as two other genes encoding transcriptional regulatory factors. All these genes lie closely together in a cluster. Transcriptional regulation is the main regulatory mechanism that controls the levels of the enzymes involved in nitrate metabolism although other mechanisms may also be operative. The process involved in the sensing and signalling of the presence of nitrate in the medium is not well understood. In this article the current state of the studies of nitrate assimilation in yeasts as well as possible venues for future research are reviewed.

  9. Febrile seizures: A review for family physicians

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    Karande Sunil

    2007-03-01

    Full Text Available Febrile seizures are the most common cause of convulsions in children. Most are simple in nature, although those with focal onset, prolonged duration (³15 min or those that recur within 24 h or within the same febrile illness are considered complex. Diagnosis of this condition is essentially clinical and based on its description provided by parents. Its pathophysiology remains unclear, but genetics plays a major role in conferring susceptibility. Although most febrile seizures are benign and associated with minor viral illnesses, it is critical that the child be evaluated immediately to reduce parental anxiety and to identify the cause of the fever. It is essential to exclude underlying pyogenic meningitis, either clinically or, if any doubt remains, by lumbar puncture. The risk of pyogenic meningitis is as low (< 1.3% as the risk in a febrile child without seizures. After an initial febrile seizure (simple or complex, 3-12% of children develop epilepsy by adolescence. However, the risk of developing epilepsy after an initial simple febrile seizure is low (1.5-2.4%. Since the vast majority of children have a normal long-term outcome, antiepileptic medication is not recommended to prevent recurrence of febrile seizures. Oral diazepam or clobazam, given only when fever is present, is an effective means of reducing the risk of recurrence. The family physician can play an important role in counseling the parents that most febrile seizures are brief, do not require any specific treatment or extensive work-up, the probability of frequent or possibly threatening recurrences is low and the long-term prognosis is excellent.

  10. Febrile seizures in Kaduna, north western Nigeria

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    E E Eseigbe

    2012-01-01

    Full Text Available Background: Febrile seizure is the most common seizure of childhood and has a good prognosis. However its presentation is fraught with poor management, with grave consequences, in our environment. Thus a review of its current status is important. Objective: To review the status of febrile seizures in Kaduna metropolis. Materials and Methods: A review of cases seen in the Department of Paediatrics, 44 Nigeria Army Reference Hospital, Kaduna between June 2008 and June 2010. Results: Out of the 635 cases admitted in the department 17 (2.7% fulfilled the criteria for febrile seizures. There were 11 Males and 6 Females (M: F, 1.8:1. Age range was from 9 months to 5 years with a mean of 2.2 years ± 1.1 and peak age of 3 years. Twelve (70.6% were in the upper social classes (I-III. Fever, convulsion, catarrh and cough were major presenting symptoms. Incidence of convulsion was least on the 1st day of complaint. Fourteen (82.4% of the cases were simple febrile seizures while 3 were complex. There was a positive family history in 5 (29.4% of the cases. Eleven (64.7% had orthodox medication at home, before presentation, 5 (29.4% consulted patient medicine sellers and 7 (41.7% received traditional medication as part of home management. Malaria and acute respiratory infections were the identifiable causes. Standard anti-malaria and anti-biotic therapy were instituted, where indicated. All recovered and were discharged. Conclusion: There was a low prevalence of febrile seizures among the hospitalized children and a poor pre-hospitalization management of cases. It highlighted the need for improved community awareness on the prevention and management of febrile seizures.

  11. Frontal lobe epilepsy with atypical seizure semiology resembling shuddering attacks or wet dog shake seizures.

    Science.gov (United States)

    Jahodova, Alena; Krsek, Pavel; Komarek, Vladimir; Kudr, Martin; Kyncl, Martin; Zamecnik, Josef; Tichy, Michal

    2012-03-01

    We report a girl with a drug-resistant frontal lobe epilepsy caused by focal cortical dysplasia, who exhibited uncommon seizures. The seizures consisted of shoulder or whole body shuddering after a short psychic aura and face grimacing. Consciousness was fully preserved. The seizures resembled "wet dog shake" seizures described in rat models of epilepsy or shuddering attacks in infants. EEG findings were inconclusive, however, MRI showed a clear dysplastic lesion in the right frontal mesial and polar structures. The patient underwent an extended lesionectomy guided by neuronavigation and intraoperative electrocorticography. Focal cortical dysplasia type Ib was histologically confirmed and the patient has been seizure-free for the three years following resection. [Published with video sequences].

  12. The effects of glycemic control on seizures and seizure-induced excitotoxic cell death

    Directory of Open Access Journals (Sweden)

    Schauwecker Paula

    2012-08-01

    Full Text Available Abstract Background Epilepsy is the most common neurological disorder after stroke, affecting more than 50 million persons worldwide. Metabolic disturbances are often associated with epileptic seizures, but the pathogenesis of this relationship is poorly understood. It is known that seizures result in altered glucose metabolism, the reduction of intracellular energy metabolites such as ATP, ADP and phosphocreatine and the accumulation of metabolic intermediates, such as lactate and adenosine. In particular, it has been suggested that the duration and extent of glucose dysregulation may be a predictor of the pathological outcome of status. However, little is known about neither the effects of glycemic control on brain metabolism nor the effects of managing systemic glucose concentrations in epilepsy. Results In this study, we examined glycemic modulation of kainate-induced seizure sensitivity and its neuropathological consequences. To investigate the relationship between glycemic modulation, seizure susceptibility and its neuropathological consequences, C57BL/6 mice (excitotoxin cell death resistant were subjected to hypoglycemia or hyperglycemia, followed by systemic administration of kainic acid to induce seizures. Glycemic modulation resulted in minimal consequences with regard to seizure severity but increased hippocampal pathology, irrespective of whether mice were hypoglycemic or hyperglycemic prior to kainate administration. Moreover, we found that exogenous administration of glucose following kainic acid seizures significantly reduced the extent of hippocampal pathology in FVB/N mice (excitotoxin cell death susceptible following systemic administration of kainic acid. Conclusion These findings demonstrate that modulation of the glycemic index can modify the outcome of brain injury in the kainate model of seizure induction. Moreover, modulation of the glycemic index through glucose rescue greatly diminishes the extent of seizure

  13. Constipation enhances the propensity to seizure in pentylenetetrazole-induced seizure models of mice.

    Science.gov (United States)

    Moezi, Leila; Pirsalami, Fatema; Inaloo, Soroor

    2015-03-01

    Epilepsy is characterized by spontaneous recurrent seizures and represents one of the most frequent neurological diseases, affecting about 60 million people worldwide. The cellular and neurocircuit bases of epilepsy are poorly understood. Constipation is a common gastrointestinal disorder characterized by symptoms such as straining, hard stool, and infrequent defecation. Population-based studies have shown that the prevalence of constipation is up to 30% of the population in developed countries. The causal link between seizure and constipation is a common belief among patients and physicians, but there are no scientific data to support this association. The current investigation evaluated the effects of constipation induced by loperamide (a peripheral μ-opioid receptor agonist without effect on central nervous system receptors) and clidinium (a quaternary amine antimuscarinic agent with reduced central nervous system effects) on two different seizure models of mice: (1) myoclonic, clonic, and generalized tonic seizures and death induced by intraperitoneal administration of pentylenetetrazole and (2) clonic seizure threshold induced by intravenous infusion of pentylenetetrazole. We demonstrated that the measured intestinal transit (%intestinal transit) decreased after loperamide or clidinium treatment for 3days. Constipation in mice which was induced by loperamide or clonidine caused a decrease in threshold to clonic seizure in the intravenous pentylenetetrazole seizure model. Moreover loperamide- or clidinium-induced constipation decreased latencies to, clonic, and tonic seizures and death in the intraperitoneal pentylenetetrazole model of mice. Serum ammonia levels were slightly elevated in both loperamide- and clidinium-treated mice. In conclusion, loperamide- or clidinium-induced constipated mice are more prone to seizure which might confirm the belief of patients and physicians about constipation as a trigger of seizure.

  14. Febrile Seizures: Etiology, Prevalence, and Geographical Variation

    Directory of Open Access Journals (Sweden)

    Ali DELPISHEH

    2014-07-01

    Full Text Available How to Cite This Article: Delpisheh A, Veisani Y, Sayehmiri K, Fayyazi A. Febrile Seizures: Etiology, Prevalence, and Geographical Variation. Iran J Child Neurol. 2014 Summer; 8(3:30-37. AbstractObjectiveFebrile seizures (FSs are the most common neurological disorder observed in the pediatric age group. The present study provides information about epidemiological and clinical characteristics as well as risk factors associated with FS among Iranian children.Materials & MethodsOn the computerized literature valid databases, the FS prevalence and 95% confidence intervals were calculated using a random effects model. A metaregression analysis was introduced to explore heterogeneity between studies. Data manipulation and statistical analyses were performed using Stata10.ResultsThe important viral or bacterial infection causes of FSs were; recent upper respiratory infection 42.3% (95% CI: 37.2%–47.4%, gastroenteritis21.5% (95% CI: 13.6%–29.4%, and otitis media infections15.2% (95% CI: 9.8%- 20.7% respectively. The pooled prevalence rate of FS among other childhood convulsions was 47.9% (95% CI: 38.8–59.9%. The meta–regression analysis showed that the sample size does not significantly affect heterogeneity for the factor ‘prevalence FS’.ConclusionsAlmost half of all childhood convulsions among Iranian children are associated with Febrile seizure. ReferencesFelipe L, Siqueira M. febrile seizures: update on diagnosis and management. Siqueira LFM. 2010;56 (4:489–92.Oka E, Ishida S, Ohtsuka Y, Ohtahara S. Neuroepidemiological Study of Childhood Epilepsy by Application of International Classification of Epilepsies and Epileptic Syndromes (ILAE, 1989. Epilepsia. 1995;36 (7:658–61.Shi X, Lin Z, Ye X, Hu Y, Zheng F, Hu H. An epidemiological survey of febrile convulsions among pupils in the Wenzhou region. Zhongguo Dang Dai Er Ke Za Zhi. 2012 Feb;14 (2:128–30.Waruiru C, Appleton R. Febrile seizures: an update. Arch Dis Child

  15. Unusual Cause of Seizure: Pott Puffy Tumor.

    Science.gov (United States)

    Sade, Recep; Polat, Gokhan; Kantarci, Mecit

    2016-09-01

    Seizures is a comparatively common neurologic unwellness in children that has significant implications for development, parents, and society. The etiologic categories of seizures involve idiopathic, symptomatic, and cryptogenic. Pott puff tumor is a rare cause of seizures. The authors present a rare cause of the seizures.A 12-year-old boy presented with seizures. On physical examination there was swelling on his glabella. Laboratory testing indicated leukocytosis and increased C-reactive protein, and microbiological testing showed the presence of pathogenic streptococcus sp. Brain magnetic resonance imaging was performed. T1-weighted image with gadolinium enhancement revealed frontal bone defects and subcutaneous abscess and left frontal swelling. On the diffusion-weighted imaging, the abscess has relatively homogeneous increased signal intensity b1000. The apparent diffusion coefficient map reveals low intensity. Intracranial spread also showed contrast-enhanced image (). Magnetic resonance imaging typically reveals an intracranial abscess.Pott puffy tumor is an unusual clinical existence characterized by osteomyelitis of the frontal bone. The very common symptoms are headache, swelling fever, and nasal discharge. Frontal sinus infection may induce osteomyelitis, subperiosteal, and epidural abscess.

  16. Pyridoxine-dependent seizures: a review.

    Science.gov (United States)

    Rajesh, R; Girija, A S

    2003-07-01

    Pyridoxine-dependent seizure is a rare autosomal recessive disorder that usually presents with neonatal intractable seizures. This syndrome results from an inborn abnormality of the enzyme glutamic acid decarboxylase, which results in reduced pyridazine-dependent synthesis of the inhibitory neurotransmitter gamma amino butyric acid. The full range of symptomatology is unknown; but can be associated with autism, breath holding and severe mental retardation, bilious vomiting, transient visual agnosia, severe articulatory apraxia motor dyspraxia, microcephaly and intrauterine seizures. Parenteral pyridine injection test is a highly effective and reproducible test in confirming the diagnosis. Pyridoxine should be administered as a diagnostic test in all cases of convulsive disorders of infancy in which no other diagnosis is evident. Epileptic seizure discharges subside within 2-6 minutes after the intravenous injection of 50-100 mg of pyridaoxine. Once the diagnosis is confirmed, maintenance therapy should be continued indefinitely and doses increased with age or intercurrent illnesses. The maintenance dose of Bg needed is still not clear. There is a relatively wide range for the daily B6 dose necessary to control the seizure i.e., 10-200 mg/day.

  17. Liposteroid therapy for refractory seizures in children.

    Science.gov (United States)

    Yoshikawa, H; Yamazaki, S; Abe, T; Oda, Y

    2000-10-01

    Liposteroid is dexamethasone palmitate incorporated into liposomes and was developed as an anti-inflammatory drug for targeting therapy mainly for rheumatoid arthritis. Recently, it was reported that liposteroid might be effective for the treatment of West syndrome, with fewer side effects than those of corticotropin therapy. We describe three patients, a 2-month-old boy with early infantile epileptic encephalopathy, a 4-month-old girl with symptomatic West syndrome, and a 2-year-old girl with symptomatic localization-related epilepsy, whose refractory seizures were treated with liposteroid according to the original method reported by Yamamoto and colleagues in 1998. Uncontrollable seizures ceased completely in two patients and the seizure frequency decreased markedly in the other patient. Electroencephalograms revealed marked improvement in all patients. They showed no relapse of the seizures, and all showed no adverse effects except for mild brain shrinkage in one patient. Our experience with these three patients suggests that liposteroid therapy might be a new option for the treatment of refractory seizures in children, as well as for West syndrome.

  18. Folinic acid-responsive seizures initially responsive to pyridoxine.

    Science.gov (United States)

    Nicolai, Joost; van Kranen-Mastenbroek, Vivianne H J M; Wevers, Ron A; Hurkx, Wilfred A P T; Vles, Johan S H

    2006-02-01

    This report presents a male who developed clonic seizures on the day he was born. The next day, the diagnosis of pyridoxine-dependent seizures was made. However, contradictory to this diagnosis, seizures reappeared despite treatment with pyridoxine. Seizures ceased after folinic acid was initiated. The clinical and biochemical characteristics of folinic acid-responsive seizures are reviewed. Treatment with folinic acid should be considered in neonatal seizures of unknown origin that do not respond to pyridoxine, or manifest a transient response to pyridoxine.

  19. Modeling and analyzing non-seizure EEG data for patients with epilepsy

    Energy Technology Data Exchange (ETDEWEB)

    Lawkins, W.F.; Clapp, N.E. Jr.; Daw, C.S.; Hively, L.M.; Protopopescu, V. [Oak Ridge National Lab., TN (United States); Eisenstadt, M.L. [Knoxville Neurology Clinic, Knoxville, TN (United States)

    1996-05-01

    We present nonlinear analysis of non-seizure electroencephalogram (EEG) time series data from four epileptic patients. A non-seizure state is a period that is free of any part of an epileptic seizure, including the transition to a fully developed episode. EEG measurements are typically contaminated with a large amount of non- neurophysiological source information, generally called artifact, which arises, for example, from eye movement, muscle tension, and physical motion. The first objective of this study is to gain some insight into how much variability in analysis results to be expected from patients having similar clinical characteristics. The second objective is to investigate the impact of eye movement on the analysis results. A special feature presented here is the introduction and testing of a filter for eye movement artifact. The third objective is to determine if neurophysiological activity as viewed from two adjacent channels appears dynamically to be the same.

  20. Non-invasive imaging of epileptic seizures in vivo using photoacoustic tomography

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Qizhi; Carney, Paul R; Yuan Zhen; Jiang Huabei [J. Crayton Pruitt Family Department of Biomedical Engineering, University of Florida, Gainesville, FL 32611 (United States); Liu Zhao [Department of Pediatrics, Division of Pediatric Neurology, University of Florida, Gainesville, FL 32610 (United States); Chen Huanxin; Roper, Steven N [Department of Neurosurgery, University of Florida, Gainesville, FL 32610-0265 (United States)], E-mail: hjiang@bme.ufl.edu

    2008-04-07

    Non-invasive laser-induced photoacoustic tomography (PAT) is an emerging imaging modality that has the potential to image the dynamic function of the brain due to its unique ability of imaging biological tissues with high optical contrast and ultrasound resolution. Here we report the first application of our finite-element-based PAT for imaging of epileptic seizures in an animal model. In vivo photoacoustic images were obtained in rats with focal seizures induced by microinjection of bicuculline, a GABA{sub A} antagonist, into the neocortex. The seizure focus was accurately localized by PAT as confirmed with gold-standard electroencephalogram (EEG). Compared to the existing neuroimaging modalities, PAT not only has the unprecedented advantage of high spatial and temporal resolution in a single imaging modality, but also is portable and low in cost, making it possible to bring brain imaging to the bedside.

  1. Epileptic Seizure Prediction by a System of Particle Filter Associated with a Neural Network

    Science.gov (United States)

    Liu, Derong; Pang, Zhongyu; Wang, Zhuo

    2009-12-01

    None of the current epileptic seizure prediction methods can widely be accepted, due to their poor consistency in performance. In this work, we have developed a novel approach to analyze intracranial EEG data. The energy of the frequency band of 4-12 Hz is obtained by wavelet transform. A dynamic model is introduced to describe the process and a hidden variable is included. The hidden variable can be considered as indicator of seizure activities. The method of particle filter associated with a neural network is used to calculate the hidden variable. Six patients' intracranial EEG data are used to test our algorithm including 39 hours of ictal EEG with 22 seizures and 70 hours of normal EEG recordings. The minimum least square error algorithm is applied to determine optimal parameters in the model adaptively. The results show that our algorithm can successfully predict 15 out of 16 seizures and the average prediction time is 38.5 minutes before seizure onset. The sensitivity is about 93.75% and the specificity (false prediction rate) is approximately 0.09 FP/h. A random predictor is used to calculate the sensitivity under significance level of 5%. Compared to the random predictor, our method achieved much better performance.

  2. Management of dental patients with seizure disorders.

    Science.gov (United States)

    Bryan, Robert B; Sullivan, Steven M

    2006-10-01

    Dental practitioners from time to time must treat patients with epilepsy or similar seizure disorders. This article describes the various classification for epilepsy, explains how such disorders are evaluated and diagnosed, discusses management methods, and addresses related issues for special populations, such as pregnant women and elderly. In addition, the article offers information about what special steps dentists should take in treating such epileptic patients and others vulnerable to seizures and in preparing offices and staff for the possibility that a patient will have a seizure in the office. In general, a patient with severe, poorly controlled epilepsy should be treated in a hospital. Otherwise, a well-controlled patient should easily be treated in the office.

  3. Are seizures in the setting of sleep deprivation provoked?

    Science.gov (United States)

    Lawn, Nicholas; Lieblich, Sam; Lee, Judy; Dunne, John

    2014-04-01

    It is generally accepted that sleep deprivation contributes to seizures. However, it is unclear whether a seizure occurring in the setting of sleep deprivation should be considered as provoked or not and whether this is influenced by seizure type and etiology. This information may have an important impact on epilepsy diagnosis and management. We prospectively analyzed the influence of sleep deprivation on the risk of seizure recurrence in patients with first-ever unprovoked seizures and compared the findings with patients with first-ever provoked seizures. Of 1026 patients with first-ever unprovoked seizures, 204 (20%) were associated with sleep deprivation. While the overall likelihood of seizure recurrence was slightly lower in sleep-deprived patients with first-ever seizures (log-rank p=0.03), sleep deprivation was not an independent predictor of seizure recurrence on multivariate analysis. Seizure recurrence following a first-ever unprovoked seizure associated with sleep deprivation was far more likely than for 174 patients with a provoked first-ever seizure (log-rank psleep deprivation should not be regarded as provoked.

  4. Prenatal exposure to ionizing radiation and subsequent development of seizures

    Energy Technology Data Exchange (ETDEWEB)

    Dunn, K.; Yoshimaru, H.; Otake, M.; Annegers, J.F.; Schull, W.J. (Radiation Effects Research Foundation, Hiroshima (Japan))

    1990-01-01

    Seizures are a frequent sequela of impaired brain development and can be expected to affect more children with radiation-related brain damage than children without such damage. This report deals with the incidence and type of seizures among survivors prenatally exposed to the atomic bombing of Hiroshima and Nagasaki, and their association with specific stages of prenatal development at the time of irradiation. Fetal radiation dose was assumed to be equal to the dose to the maternal uterus. Seizures here include all references in the clinical record to seizure, epilepsy, or convulsion. Histories of seizures were obtained at biennial routine clinical examinations starting at about the age of 2 years. These clinical records were used to classify seizures as febrile or unprovoked (without precipitating cause). No seizures were ascertained among subjects exposed 0-7 weeks after fertilization at doses higher than 0.10 Gy. The incidence of seizures was highest with irradiation at the eighth through the 15th week after fertilization among subjects with doses exceeding 0.10 Gy and was linearly related to the level of fetal exposure. This obtains for all seizures without regard to the presence of fever or precipitating causes, and for unprovoked seizures. When the 22 cases of severe mental retardation were excluded, the increase in seizures was only suggestively significant and only for unprovoked seizures. After exposure at later stages of development, there was no increase in recorded seizures.

  5. Treatment of febrile seizures with intermittent clobazam.

    Science.gov (United States)

    Manreza, M L; Gherpelli, J L; Machado-Haertel, L R; Pedreira, C C; Heise, C O; Diament, A

    1997-12-01

    Fifty children, 24 female and 26 male, with ages varying from 6 to 72 months (mean = 23.7 m.) that experienced at least one febrile seizure (FS) entered a prospective study of intermittent therapy with clobazam. Cases with severe neurological abnormalities, progressive neurological disease, afebrile seizures, symptomatic seizures of other nature, or seizures during a central nervous system infection were excluded. Seizures were of the simple type in 25 patients, complex in 20 and unclassified in 5. The mean follow-up period was 7.9 months (range = 1 to 23 m.), and the age at the first seizure varied from 5 to 42 months (mean = 16.8 m.). Clobazam was administered orally during the febrile episode according to the child's weight: up to 5 kg, 5 mg/day; from 5 to 10 kg, 10 mg/day; from 11 to 15 kg, 15 mg/day, and over 15 kg, 20 mg/day. There were 219 febrile episodes, with temperature above 37.8 degrees C, in 40 children during the study period. Twelve children never received clobazam and 28 received the drug at least once. Drug efficacy was measured by comparing FS recurrence in the febrile episodes that were treated with clobazam with those in which only antipyretic measures were taken. Ten children (20%) experienced a FS during the study period. Of the 171 febrile episodes treated with clobazam there were only 3 recurrences (1.7%), while of the 48 episodes treated only with antipyretic measures there were 11 recurrences (22.9%), a difference highly significant (p diazepam in the intermittent treatment of FS recurrence.

  6. Adjunctive pregabalin vs gabapentin for focal seizures

    Science.gov (United States)

    Glue, Paul; Friedman, Daniel; Almas, Mary; Yardi, Nandan; Knapp, Lloyd; Pitman, Verne; Posner, Holly B.

    2016-01-01

    Objective: To evaluate the comparative safety and adjunctive efficacy of pregabalin and gabapentin in reducing seizure frequency in patients with partial-onset seizures based on prestudy modeling showing superior efficacy for pregabalin. Methods: The design of this comparative efficacy and safety study of pregabalin and gabapentin as adjunctive treatment in adults with refractory partial-onset seizures was randomized, flexible dose, double blind, and parallel group. The study included a 6-week baseline and a 21-week treatment phase. The primary endpoint was the percentage change from baseline in 28-day seizure rate to the treatment phase. Results: A total of 484 patients were randomized to pregabalin (n = 242) or gabapentin (n = 242). Of these, 359 patients (187 pregabalin, 172 gabapentin) completed the treatment phase. The observed median and mean in percentage change from baseline was −58.65 and −47.7 (SD 48.3) for pregabalin and −57.43 and −45.28 (SD 60.6) for gabapentin. For the primary endpoint, there was no significant difference between treatments. The Hodges-Lehman estimated median difference was 0.0 (95% confidence interval −6.0 to 7.0). Safety profiles were comparable and consistent with prior trials. Conclusions: The absence of the anticipated efficacy difference based on modeling of prior, nearly identical trials and the larger-than-expected response rates of the 2 antiepileptic drugs were unexpected. These findings raise questions that are potentially important to consider in future comparative efficacy trials. ClinicalTrials.gov identifier: NCT00537940. Classification of evidence: This study provides Class II evidence that for patients with partial seizures enrolled in this study, pregabalin is not superior to gabapentin in reducing seizure frequency. Because of the atypical response rates, the results of this study are poorly generalizable to other epilepsy populations. PMID:27521437

  7. Non-invasive cerebral blood volume measurement during seizures using multi-channel near infrared spectroscopic topography

    Science.gov (United States)

    Watanabe, Eiju; Maki, Atsushi; Kawaguchi, Fumio; Yamashita, Yuichi; Koizumi, Hideaki; Mayanagi, Yoshiaki

    2000-07-01

    Near infrared spectroscopic topography (NIRS) is widely recognized as a noninvasive method to measure the regional cerebral blood volume (rCBV) dynamics coupled with neuronal activities. We analyzed the rCBV change in the early phase of epileptic seizures in 12 consecutive patients with medically intractable epilepsy. Seizure was induced by bemegride injection. We used eight-channel NIRS in nine cases and 24 channel in three cases. In all of the cases, rCBV increased rapidly after the seizure onset on the focus side. The increased rCBV was observed for about 30 - 60 s. The NIRS method can be applied to monitor the rCBV change continuously during seizures. Therefore, this method may be combined with ictal SPECT as one of the most reliable noninvasive methods of focus diagnosis.

  8. "Nocturnal seizures" in idiopathic pulmonary arterial hypertension.

    Science.gov (United States)

    Izzo, Anthony; McSweeney, Julia; Kulik, Thomas; Khatwa, Umakanth; Kothare, Sanjeev V

    2013-10-15

    The usual differential diagnoses of nocturnal events in children include parasomnias, nocturnal seizures, nocturnal reflux (Sandifer syndrome), hypnic jerks, periodic limb movements of sleep, and sleep disordered breathing. We report a previously healthy young girl who presented to the sleep clinic for evaluation of nocturnal events which were diagnosed as medically refractory nocturnal seizures. It was not until a syncopal event occurred in the daytime, which prompted referral for cardiac evaluation, the diagnosis of idiopathic pulmonary arterial hyper-tension (IPAH) was made. Sleep physicians should consider IPAH in the differential diagnosis of nocturnal events in children.

  9. Seizures and Praziquantel. A case report

    Directory of Open Access Journals (Sweden)

    Jaime R. Torres R.

    1988-12-01

    Full Text Available A 27 year Old male developed seizures after receiving a single 20 mg/kg dose of praziquantel for the treatment of an intestinal Hymenolepis nana infection. On further clinical and laboratorial evaluations, he was found to suffer from an until then asymptomatic parenchymal brain cysticercosis. Praziquantel must be used with caution in those areas where cysticercosis represents a mayor public health problem. The occurrence of unexpected seizures in an individual being treated with the compound, must prompt clinicians to rule out cysticercosis of the CNS.

  10. Seizures due to high dose camphor ingestion.

    Science.gov (United States)

    Tekin, Hande Gazeteci; Gökben, Sarenur; Serdaroğlu, Gül

    2015-12-01

    Camphor is a cyclic ketone of the hydro aromatic terpene group. Today it is frequently used as a prescription or non-prescription topical antitussive, analgesic, anesthetic and antipruritic agent. Camphor which is considered an innocent drug by parents and physicians is a common household item which can lead to severe poisoning in children even when taken in small amounts. Neurotoxicity in the form of seizures can ocur soon after ingestion. A two-year old female patient who presented with a complaint of generalized tonic-clonic seizures after oral ingestion of camphor is presented.

  11. Seizures after intravenous tramadol given as premedication

    Directory of Open Access Journals (Sweden)

    Lalit Kumar Raiger

    2012-01-01

    Full Text Available A 35-year-old, 50-kg female with a history of epilepsy was scheduled for elective breast surgery (fibroadenoma under general anaesthesia. She was given glycopyrrolate 0.2 mg, ondansetron 4 mg and tramadol 100 mg i.v. as premedication. Within 5 min, she had an acute episode of generalised tonic-clonic seizure that was successfully treated with 75 mg thiopentone i.v. and after 30 min, she was given general anaesthesia with endotracheal intubation. Surgery, intra-operative period, extubation and post-operative period were uneventful. We conclude that tramadol may provoke seizures in patients with epilepsy even within the recommended dose range.

  12. Febrile Seizure: Demographic Features and Causative Factors

    OpenAIRE

    2012-01-01

    How to cite this article: Esmaili Gourabi H, Bidabadi E, Cheraghalipour  F, Aarabi  Y, Salamat F. Febrile Seizure: Demographic Features and Causative Factors. Iran J Child Neurol Autumn 2012; 6(4):33-37.Abstract Objective Because of geographical and periodical variation, we prompted to determine the demographic features and causative factors for febrile seizure in Rasht. Materials & Methods In this cross-sectional study, all 6–month- to 6-year-old children with the diagnosis of febrile s...

  13. Neural - glial circuits : Can Interneurons stop seizures

    Science.gov (United States)

    Nadkarni, Suhita; Jung, Peter

    2004-03-01

    Recent progress in neurobiology suggests that astrocytes - through calcium excitability - are active partners to the neurons by integrating their activity and, in turn, regulating synaptic transmission. In a similar fashion neurons and interneurons are the 'Yin and Yang' of the hippocampus. The dichotomy of excitation and inhibition between pyramidal neurons and interneurons plays a crucial role in the function of the neuronal circuit.We consider a model of a pyramidal cell in contact with one synaptic astrocytes. It has been shown that such a circuit - triggered by transient stimulation - can exhibit sustained oscillations ("seizures") for strong coupling. The question we are considering is, under what conditions synaptic inhibition can stop these seizures?

  14. Perfusion network shift during seizures in medial temporal lobe epilepsy.

    Directory of Open Access Journals (Sweden)

    Karen M Sequeira

    Full Text Available BACKGROUND: Medial temporal lobe epilepsy (MTLE is associated with limbic atrophy involving the hippocampus, peri-hippocampal and extra-temporal structures. While MTLE is related to static structural limbic compromise, it is unknown whether the limbic system undergoes dynamic regional perfusion network alterations during seizures. In this study, we aimed to investigate state specific (i.e. ictal versus interictal perfusional limbic networks in patients with MTLE. METHODS: We studied clinical information and single photon emission computed tomography (SPECT images obtained with intravenous infusion of the radioactive tracer Technetium- Tc 99 m Hexamethylpropyleneamine Oxime (Tc-99 m HMPAO during ictal and interictal state confirmed by video-electroencephalography (VEEG in 20 patients with unilateral MTLE (12 left and 8 right MTLE. Pair-wise voxel-based analyses were used to define global changes in tracer between states. Regional tracer uptake was calculated and state specific adjacency matrices were constructed based on regional correlation of uptake across subjects. Graph theoretical measures were applied to investigate global and regional state specific network reconfigurations. RESULTS: A significant increase in tracer uptake was observed during the ictal state in the medial temporal region, cerebellum, thalamus, insula and putamen. From network analyses, we observed a relative decreased correlation between the epileptogenic temporal region and remaining cortex during the interictal state, followed by a surge of cross-correlated perfusion in epileptogenic temporal-limbic structures during a seizure, corresponding to local network integration. CONCLUSIONS: These results suggest that MTLE is associated with a state specific perfusion and possibly functional organization consisting of a surge of limbic cross-correlated tracer uptake during a seizure, with a relative disconnection of the epileptogenic temporal lobe in the interictal period. This

  15. Ionospheric Data Assimilation from a Data Provider's Perspective

    Science.gov (United States)

    Schaefer, R. K.; Paxton, L. J.; Bust, G.; Zhang, Y.; Romeo, G.; Comberiate, J.; Gelinas, L. J.

    2014-12-01

    The Ionosphere/Thermosphere system is a very dynamic and complex medium to model. Given sufficient data and proper data handling, assimilative models can give a good representation of this system. One good dataset for this purpose comes from UV imagers on spacecraft. In particular, the Oxygen recombination emission (135.6 nm) and the Nitrogen Lyman-Birge Hopfield band (both 140-150 nm and 165-180 nm) are being collected by instruments on the NASA TIMED/GUVI and DMSP/SSUSI instruments. Similar UV data will also be available in the future from the ICON and GOLD missions. Currently, the Air Force is using the oxygen emission to infer ionospheric electron densities in the USU GAIM model for ionospheric forecasts. We have also been integrating data for the IDA4D model assimilation (Bust et al, 2007). As the data product designer for these UV products, we have an unique perspective on issues related to assimilating this data. These issues concern model resolution scales (Schunk, et al, 2011), filtering of noisy data, and handling of second order effects. We will discuss our experience with these issues and point out some future directions for assimilation of UV data. Bust, G., Crowley, G., Curtis, N., Reynolds, A., Paxton, L., Coker, C., Bernhardt, P. "IDA4D - a new ionospheric imaging algorithm using non-linear ground-based and spaced- based data sources", American Geophysical Union, Fall Meeting 2007, abstract #SA11B-06. Schunk, R.W., Scherliess, L., and Thompson, D.C., 2011 "Ionospheric Data Assimilation: Problems Associated with Missing Physics", Aeronomy of the Earth's Atmosphere and Ionosphere. IAGA Special Sopron Book Series Volume 2, pp 437-442.

  16. Canine and feline epileptic seizures and the lunar cycle: 2,507 seizures (2000-2008).

    Science.gov (United States)

    Browand-Stainback, Laura; Levesque, Donald; McBee, Matthew

    2011-01-01

    Epileptic seizures in 211 canine and feline patients diagnosed with idiopathic epilepsy were evaluated for temporal significance in relation to the lunar cycle. Seizure counts were compared among each of the eight individual lunar phases, among each of eight exact lunar phase dates, and by percent of lunar illumination using generalized estimating equations. No statistical significance was found in any of these comparisons excluding a relationship between the onset of epileptic seizures and the phases of the moon. Alteration in anticonvulsant treatment or monitoring of canine and feline patients with idiopathic epilepsy at large was not warranted based on the lunar cycle.

  17. Data assimilation in a coupled physical-biogeochemical model of the California Current System using an incremental lognormal 4-dimensional variational approach: Part 2-Joint physical and biological data assimilation twin experiments

    Science.gov (United States)

    Song, Hajoon; Edwards, Christopher A.; Moore, Andrew M.; Fiechter, Jerome

    2016-10-01

    Coupled physical and biological data assimilation is performed within the California Current System using model twin experiments. The initial condition of physical and biological variables is estimated using the four-dimensional variational (4DVar) method under the Gaussian and lognormal error distributions assumption, respectively. Errors are assumed to be independent, yet variables are coupled by assimilation through model dynamics. Using a nutrient-phytoplankton-zooplankton-detritus (NPZD) model coupled to an ocean circulation model (the Regional Ocean Modeling System, ROMS), the coupled data assimilation procedure is evaluated by comparing results to experiments with no assimilation and with assimilation of physical data and biological data separately. Independent assimilation of physical (biological) data reduces the root-mean-squared error (RMSE) of physical (biological) state variables by more than 56% (43%). However, the improvement in biological (physical) state variables is less than 7% (13%). In contrast, coupled data assimilation improves both physical and biological components by 57% and 49%, respectively. Coupled data assimilation shows robust performance with varied observational errors, resulting in significantly smaller RMSEs compared to the free run. It still produces the estimation of observed variables better than that from the free run even with the physical and biological model error, but leads to higher RMSEs for unobserved variables. A series of twin experiments illustrates that coupled physical and biological 4DVar assimilation is computationally efficient and practical, capable of providing the reliable estimation of the coupled system with the same and ready to be examined in a realistic configuration.

  18. Conditions for successful data assimilation

    Science.gov (United States)

    Morzfeld, M.; Chorin, A. J.

    2013-12-01

    Many applications in science and engineering require that the predictions of uncertain models be updated by information from a stream of noisy data. The model and the data jointly define a conditional probability density function (pdf), which contains all the information one has about the process of interest and various numerical methods can be used to study and approximate this pdf, e.g. the Kalman filter, variational methods or particle filters. Given a model and data, each of these algorithms will produce a result. We are interested in the conditions under which this result is reasonable, i.e. consistent with the real-life situation one is modeling. In particular, we show, using idealized models, that numerical data assimilation is feasible in principle only if a suitably defined effective dimension of the problem is not excessive. This effective dimension depends on the noise in the model and the data, and in physically reasonable problems it can be moderate even when the number of variables is huge. In particular, we find that the effective dimension being moderate induces a balance condition between the noises in the model and the data; this balance condition is often satisfied in realistic applications or else the noise levels are excessive and drown the underlying signal. We also study the effects of the effective dimension on particle filters in two instances, one in which the importance function is based on the model alone, and one in which it is based on both the model and the data. We have three main conclusions: (1) the stability (i.e., non-collapse of weights) in particle filtering depends on the effective dimension of the problem. Particle filters can work well if the effective dimension is moderate even if the true dimension is large (which we expect to happen often in practice). (2) A suitable choice of importance function is essential, or else particle filtering fails even when data assimilation is feasible in principle with a sequential algorithm

  19. Altimeter data assimilation in the tropical Indian Ocean using water property conserving scheme

    Indian Academy of Sciences (India)

    Bhasha M Mankad; Rashmi Sharma; Sujit Basu; P K Pal

    2012-02-01

    Altimeter data have been assimilated in an ocean general circulation model using the water property conserving scheme. Two runs of the model have been conducted for the year 2004. In one of the runs, altimeter data have been assimilated sequentially, while in another run, assimilation has been suppressed. Assimilation has been restricted to the tropical Indian Ocean. An assessment of the strength of the scheme has been carried out by comparing the sea surface temperature (SST), simulated in the two runs, with in situ derived as well as remotely sensed observations of the same quantity. It has been found that the assimilation exhibits a significant positive impact on the simulation of SST. The subsurface effect of the assimilation could be judged by comparing the model simulated depth of the 20°C isotherm (hereafter referred to as D20), as a proxy of the thermocline depth, with the same quantity estimated from ARGO observations. In this case also, the impact is noteworthy. Effect on the dynamics has been judged by comparison of simulated surface current with observed current at a moored buoy location, and finally the impact on model sea level forecast in a free run after assimilation has been quantified in a representative example.

  20. Soil Moisture Data Assimilation in Soil Water Flow Modeling

    Science.gov (United States)

    Pachepsky, Y. A.; Guber, A.; Jacques, D.; Pan, F.; van Genuchten, M.; Cady, R. E.; Nicholson, T. J.

    2010-12-01

    selecting one best depth or two best depths will be presented. Best depths appear to be different depending on whether simulations are carried out to estimate soil water dynamics in root zone or to estimate infiltration losses beyond this zone. Soil moisture sensor data assimilation in soil flow modeling allows one to avoid multiparametric calibration and correct simulation on the go which can be beneficial in many applications, Using pedotransfer functions in ensemble Kalman filter results in the effective data assimilation in soil water flow modeling.

  1. Compensation for Complete Assimilation in Speech Perception: The Case of Korean Labial-to-Velar Assimilation

    Science.gov (United States)

    Mitterer, Holger; Kim, Sahyang; Cho, Taehong

    2013-01-01

    In connected speech, phonological assimilation to neighboring words can lead to pronunciation variants (e.g., "garden bench" [arrow right] "garde'm' bench"). A large body of literature suggests that listeners use the phonetic context to reconstruct the intended word for assimilation types that often lead to incomplete assimilations (e.g., a…

  2. Neonatal seizures and therapeutic hypothermia for hypoxic-ischemic encephalopathy

    OpenAIRE

    2014-01-01

    Neonatal seizures are associated with morbidity and mortality. Hypoxic-ischemic encephalopathy (HIE) is the most common cause of seizures in newborns. Neonatal animal models suggest that therapeutic hypothermia can reduce seizures and epileptiform activity in the setting of hypoxia-ischemia, however data from human studies have conflicting results. In this research highlight, we will discuss the findings of our recent study that demonstrated a decreased seizure burden in term newborns with mo...

  3. Spectral characteristics of background error covariance and multiscale data assimilation

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhijin [Jet Propulsion Laboratory, California Institute of Technology, Pasadena California USA; Cheng, Xiaoping [The Joint Institute for Regional Earth System Science and Engineering, University of California, Los Angeles California USA; Gustafson Jr., William I. [Pacific Northwest National Laboratory, Richland Washington USA; Vogelmann, Andrew M. [Brookhaven National Laboratory, Upton New York USA

    2016-05-17

    The spatial resolutions of numerical atmospheric and oceanic circulation models have steadily increased over the past decades. Horizontal grid spacing down to the order of 1 km is now often used to resolve cloud systems in the atmosphere and sub-mesoscale circulation systems in the ocean. These fine resolution models encompass a wide range of temporal and spatial scales, across which dynamical and statistical properties vary. In particular, dynamic flow systems for small scales can become spatially localized and temporarily intermittent. An analysis shows that the background correlation length scale is larger than 75 km for streamfunctions, even for a 2-km resolution model, and larger than 25 km for water vapor mixing ratios. The theoretical analyses suggest that such correlation length scales prevent the currently used data assimilation schemes from constraining spatial scales smaller than 150 km for streamfunctions and 50 km for water vapor mixing ratios. These results highlight the necessity of fundamentally modifying the currently used data assimilation algorithm for assimilating high-resolution observations into the aforementioned fine resolution models. A multiscale methodology based on scale decomposition is suggested, and challenges are discussed.

  4. 28 CFR 0.86 - Seizure of gambling devices.

    Science.gov (United States)

    2010-07-01

    ... 28 Judicial Administration 1 2010-07-01 2010-07-01 false Seizure of gambling devices. 0.86 Section... Bureau of Investigation § 0.86 Seizure of gambling devices. The Director, Associate Director, Assistants... General to make seizures of gambling devices (18 U.S.C. 1955(d), 15 U.S.C. 1171 et seq.) and wire or...

  5. Seizure-like activity during fentanyl anesthesia. A case report.

    OpenAIRE

    Webb, M. D.

    1990-01-01

    Fentanyl induced seizures have been described previously in the literature. Clinical observations has labeled the movements seen in fentanyl anesthesia as seizure activity but electroencephalographic studies have not supported this. A case of seizure-like activity after the administration of fentanyl in a 20-year-old female is reported.

  6. Seizure increases electroencephalographic abnormalities in children with tuberculous meningitis

    Directory of Open Access Journals (Sweden)

    Prastiya Indra Gunawan

    2016-04-01

    The EEG pattern in children with TBM varies, and EEG abnormalities were more frequently localized in the frontotemporal region. Seizures were associated with EEG abnormalities in children with TBM. EEG abnormalities occurring simultaneously with seizures may predict the occurrence of seizures.

  7. Out-of-body experiences associated with seizures

    Directory of Open Access Journals (Sweden)

    Bruce eGreyson

    2014-02-01

    Full Text Available Alterations of consciousness are critical factors in the diagnosis of epileptic seizures. With these alterations in consciousness, some persons report sensations of separating from the physical body, experiences that may in rare cases resemble spontaneous out-of-body experiences. This study was designed to identify and characterize these out-of-body-like subjective experiences associated with seizure activity. 55% of the patients in this study recalled some subjective experience in association with their seizures. Among our sample of 100 patients, 7 reported out-of-body experiences associated with their seizures. We found no differentiating traits that were associated with patients’ reports of out-of-body experiences, in terms of either demographics; medical history, including age of onset and duration of seizure disorder, and seizure frequency; seizure characteristics, including localization, lateralization, etiology, and type of seizure, and epilepsy syndrome; or ability to recall any subjective experiences associated with their seizures. Reporting out-of-body experiences in association with seizures did not affect epilepsy-related quality of life. It should be noted that even in those patients who report out-of-body experiences, such sensations are extremely rare events that do not occur routinely with their seizures. Most patients who reported out-of-body experiences described one or two experiences that occurred an indeterminate number of years ago, which precludes the possibility of associating the experience with the particular characteristics of that one seizure or with medications taken or other conditions at the time.

  8. Rapidly Learned Identification of Epileptic Seizures from Sonified EEG

    Directory of Open Access Journals (Sweden)

    Psyche eLoui

    2014-10-01

    Full Text Available Sonification refers to a process by which data are converted into sound, providing an auditory alternative to visual display. Currently, the prevalent method for diagnosing seizures in epilepsy is by visually reading a patient’s electroencephalogram (EEG. However, sonification of the EEG data provides certain advantages due to the nature of human auditory perception. We hypothesized that human listeners will be able to identify seizures from EEGs using the auditory modality alone, and that accuracy of seizure identification will increase after a short training session. Here we describe an algorithm we have used to sonify EEGs of both seizure and non-seizure activity, followed by a training study in which subjects listened to short clips of sonified EEGs and determine whether each clip was of seizure or normal activity, both before and after a short training session. Results show that before training subjects performed at chance level in differentiating seizures vs. non-seizures, but there was a significant improvement of accuracy after the training session. After training, subjects successfully distinguished seizures from non-seizures using the auditory modality alone. Further analyses using signal detection theory demonstrated improvement in sensitivity and reduction in response bias as a result of training. This study demonstrates the potential of sonified EEGs to be used for the detection of seizures. Future studies will attempt to increase accuracy using novel training and sonification modifications, with the goals of managing, predicting, and ultimately controlling seizures using sonification as a possible biofeedback-based intervention for epilepsy.

  9. Effectiveness of diazepam rectal gel in adults with acute repetitive seizures and prolonged seizures: a single-center experience.

    Science.gov (United States)

    Fakhoury, Toufic; Chumley, Amber; Bensalem-Owen, Meriem

    2007-11-01

    Many adults with epilepsy have breakthrough seizures despite treatment with antiepileptic drugs (AEDs), requiring them to have a rescue medication as part of a comprehensive treatment plan. We evaluated the effectiveness and tolerability of rectal diazepam in the treatment of breakthrough seizures in adult patients with epilepsy. We identified 50 such patients who had used diazepam rectal gel for clusters of seizures defined as acute repetitive seizures, prolonged seizures, or both, in the previous 18 months. Information on diagnoses, dose, frequency of use, reasons for use, safety, and efficacy was collected. Diazepam rectal gel was effective in stopping seizures in 45 patients (90%). Somnolence was reported in most patients, but no other adverse events were reported. Diazepam rectal gel demonstrates efficacy and tolerability as a seizure rescue medication for adult patients with a variety of seizure types, and may help improve quality of life.

  10. Assimilation of MLS and OMI Ozone Data

    Science.gov (United States)

    Stajner, I.; Wargan, K.; Chang, L.-P.; Hayashi, H.; Pawson, S.; Froidevaux, L.; Livesey, N.

    2005-01-01

    Ozone data from Aura Microwave Limb Sounder (MLS) and Ozone Monitoring Instrument (OMI) were assimilated into the ozone model at NASA's Global Modeling and Assimilation Office (GMAO). This assimilation produces ozone fields that are superior to those from the operational GMAO assimilation of Solar Backscatter Ultraviolet (SBUV/2) instrument data. Assimilation of Aura data improves the representation of the "ozone hole" and the agreement with independent Stratospheric Aerosol and Gas Experiment (SAGE) III and ozone sonde data. Ozone in the lower stratosphere is captured better: mean state, vertical gradients, spatial and temporal variability are all improved. Inclusion of OMI and MLS data together, or separately, in the assimilation system provides a way of checking how consistent OMI and MLS data are with each other, and with the ozone model. We found that differences between OMI total ozone column data and model forecasts decrease after MLS data are assimilated. This indicates that MLS stratospheric ozone profiles are consistent with OMI total ozone columns. The evaluation of error characteristics of OMI and MLS ozone will continue as data from newer versions of retrievals becomes available. We report on the initial step in obtaining global assimilated ozone fields that combine measurements from different Aura instruments, the ozone model at the GMAO, and their respective error characteristics. We plan to use assimilated ozone fields in estimation of tropospheric ozone. We also plan to investigate impacts of assimilated ozone fields on numerical weather prediction through their use in radiative models and in the assimilation of infrared nadir radiance data from NASA's Advanced Infrared Sounder (AIRS).

  11. Data Assimilation - Advances and Applications

    Energy Technology Data Exchange (ETDEWEB)

    Williams, Brian J. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2014-07-30

    This presentation provides an overview of data assimilation (model calibration) for complex computer experiments. Calibration refers to the process of probabilistically constraining uncertain physics/engineering model inputs to be consistent with observed experimental data. An initial probability distribution for these parameters is updated using the experimental information. Utilization of surrogate models and empirical adjustment for model form error in code calibration form the basis for the statistical methodology considered. The role of probabilistic code calibration in supporting code validation is discussed. Incorporation of model form uncertainty in rigorous uncertainty quantification (UQ) analyses is also addressed. Design criteria used within a batch sequential design algorithm are introduced for efficiently achieving predictive maturity and improved code calibration. Predictive maturity refers to obtaining stable predictive inference with calibrated computer codes. These approaches allow for augmentation of initial experiment designs for collecting new physical data. A standard framework for data assimilation is presented and techniques for updating the posterior distribution of the state variables based on particle filtering and the ensemble Kalman filter are introduced.

  12. Seizures beget seizures in temporal lobe epilepsies: the boomerang effects of newly formed aberrant kainatergic synapses.

    Science.gov (United States)

    Ben-Ari, Yehezkel; Crepel, Valérie; Represa, Alfonso

    2008-01-01

    Do temporal lobe epilepsy (TLE) seizures in adults promote further seizures? Clinical and experimental data suggest that new synapses are formed after an initial episode of status epilepticus, however their contribution to the transformation of a naive network to an epileptogenic one has been debated. Recent experimental data show that newly formed aberrant excitatory synapses on the granule cells of the fascia dentate operate by means of kainate receptor-operated signals that are not present on naive granule cells. Therefore, genuine epileptic networks rely on signaling cascades that differentiate them from naive networks. Recurrent limbic seizures generated by the activation of kainate receptors and synapses in naive animals lead to the formation of novel synapses that facilitate the emergence of further seizures. This negative, vicious cycle illustrates the central role of reactive plasticity in neurological disorders.

  13. Treatment Of Seizures In The Elderly

    Directory of Open Access Journals (Sweden)

    Aleem MA

    2005-01-01

    Full Text Available The increasing life expectancy over the preceding decades and trend towards further increase means that the elderly is now a growing section of the population. Seizures are a particularly common disorder in the age group. Considering that above the age of 50 years, one is prone to suffer from atleast one chromic illness, the interplay between associated medical and neurologic diseases and seizures need to be understood. These comorbidities like hypertension, cerebrovascular accidents, diabetes, renal failure and others not only contribute to seizures, they may also interfere with their appropriate treatment. Seizures, on the other hand, may be the cause of added morbidity like fractures, head injury and poor self esteem which may lead to poor quality of life. In addition, the unique pharmacokinetics, pharmacodynamics and side effect profile of the various antieplileptic drugs in the elderly and the multiple drug interactions, require judicious use along with regular monitoring. However, an ideal antiepileptic drug for the elderly is yet to be found.

  14. Photosensitivity and visually induced seizures: review

    NARCIS (Netherlands)

    J. Parra; S. Kalitzin; F.H. Lopes da Silva

    2005-01-01

    PURPOSE OF REVIEW: Interest in visually induced seizures has increased in recent years as a result of the increasing number of precipitants in our modern environment. This review addresses new developments in this field with special attention given to the emergence of new diagnostic, therapeutic and

  15. Seizures - Multiple Languages: MedlinePlus

    Science.gov (United States)

    ... Somali) Bilingual PDF Health Information Translations Spanish (español) Convulsiones Ukrainian (Українська) Seizures Припадки - Українська (Ukrainian) Bilingual PDF ...

  16. [Classification of epileptic seizures and syndromes].

    Science.gov (United States)

    Noachtar, S; Rémi, J

    2012-02-01

    Advances in diagnostic and therapeutic options require a revision of the current classification of seizures and epilepsies. Recently, a classification proposal was introduced which reflects the ambivalence of the Internationalen Liga gegen Epilepsie (ILAE). We suggest that epileptology should utilize the same established systematic approach used in clinical neurology.

  17. Cardiac arrhythmias during or after epileptic seizures

    Science.gov (United States)

    van der Lende, Marije; Surges, Rainer; Sander, Josemir W; Thijs, Roland D

    2016-01-01

    Seizure-related cardiac arrhythmias are frequently reported and have been implicated as potential pathomechanisms of Sudden Unexpected Death in Epilepsy (SUDEP). We attempted to identify clinical profiles associated with various (post)ictal cardiac arrhythmias. We conducted a systematic search from the first date available to July 2013 on the combination of two terms: ‘cardiac arrhythmias’ and ‘epilepsy’. The databases searched were PubMed, Embase (OVID version), Web of Science and COCHRANE Library. We attempted to identify all case reports and case series. We identified seven distinct patterns of (post)ictal cardiac arrhythmias: ictal asystole (103 cases), postictal asystole (13 cases), ictal bradycardia (25 cases), ictal atrioventricular (AV)-conduction block (11 cases), postictal AV-conduction block (2 cases), (post)ictal atrial flutter/atrial fibrillation (14 cases) and postictal ventricular fibrillation (3 cases). Ictal asystole had a mean prevalence of 0.318% (95% CI 0.316% to 0.320%) in people with refractory epilepsy who underwent video-EEG monitoring. Ictal asystole, bradycardia and AV-conduction block were self-limiting in all but one of the cases and seen during focal dyscognitive seizures. Seizure onset was mostly temporal (91%) without consistent lateralisation. Postictal arrhythmias were mostly found following convulsive seizures and often associated with (near) SUDEP. The contrasting clinical profiles of ictal and postictal arrhythmias suggest different pathomechanisms. Postictal rather than ictal arrhythmias seem of greater importance to the pathophysiology of SUDEP. PMID:26038597

  18. Types of Seizures Affecting Individuals with TSC

    Science.gov (United States)

    ... infantile spasms. Older children and adults may develop multiple types of seizures including generalized, complex partial and ... caused by air forced through contracted vocal cord). Limbs may be extended, ... bluish skin, possible loss of bladder or bowel control, usually lasts a ...

  19. Cardiac arrhythmias during or after epileptic seizures.

    Science.gov (United States)

    van der Lende, Marije; Surges, Rainer; Sander, Josemir W; Thijs, Roland D

    2016-01-01

    Seizure-related cardiac arrhythmias are frequently reported and have been implicated as potential pathomechanisms of Sudden Unexpected Death in Epilepsy (SUDEP). We attempted to identify clinical profiles associated with various (post)ictal cardiac arrhythmias. We conducted a systematic search from the first date available to July 2013 on the combination of two terms: 'cardiac arrhythmias' and 'epilepsy'. The databases searched were PubMed, Embase (OVID version), Web of Science and COCHRANE Library. We attempted to identify all case reports and case series. We identified seven distinct patterns of (post)ictal cardiac arrhythmias: ictal asystole (103 cases), postictal asystole (13 cases), ictal bradycardia (25 cases), ictal atrioventricular (AV)-conduction block (11 cases), postictal AV-conduction block (2 cases), (post)ictal atrial flutter/atrial fibrillation (14 cases) and postictal ventricular fibrillation (3 cases). Ictal asystole had a mean prevalence of 0.318% (95% CI 0.316% to 0.320%) in people with refractory epilepsy who underwent video-EEG monitoring. Ictal asystole, bradycardia and AV-conduction block were self-limiting in all but one of the cases and seen during focal dyscognitive seizures. Seizure onset was mostly temporal (91%) without consistent lateralisation. Postictal arrhythmias were mostly found following convulsive seizures and often associated with (near) SUDEP. The contrasting clinical profiles of ictal and postictal arrhythmias suggest different pathomechanisms. Postictal rather than ictal arrhythmias seem of greater importance to the pathophysiology of SUDEP.

  20. Hippocampal kindling: corticosterone modulation of induced seizures

    NARCIS (Netherlands)

    Kloet, E.R. de; Cottrell, G.A.; Nyakas, C.; Bohus, B.

    1984-01-01

    The effect of adrenalectomy (ADX) and corticosterone replacement was studied on seizures induced by hippocampal kindling. A complex series of changes occurred in after-discharge (AD) and behavioural depression (BD) during the immediate hours after ADX, culminating at day 1 in markedly decreased AD a

  1. Pyridoxine-Dependent Seizures and MRI Abnormality

    OpenAIRE

    J Gordon Millichap

    1996-01-01

    An infant with pyridoxine-dependent seizures and MRI, PET, and EEG evidence of diffuse structural or functional brain disease is reported from the University of New Mexico Health Sciences Center, Albuquerque, NM, and the UCLA School of Medicine, Los Angeles, CA.

  2. Data Assimilation by Conditioning of Driving Noise on Future Observations

    KAUST Repository

    Lee, Wonjung

    2014-08-01

    Conventional recursive filtering approaches, designed for quantifying the state of an evolving stochastic dynamical system with intermittent observations, use a sequence of i) an uncertainty propagation step followed by ii) a step where the associated data is assimilated using Bayes\\' rule. Alternatively, the order of the steps can be switched to i) one step ahead data assimilation followed by ii) uncertainty propagation. In this paper, we apply this smoothing-based sequential filter to systems driven by random noise, however with the conditioning on future observation not only to the system variable but to the driving noise. Our research reveals that, for the nonlinear filtering problem, the conditioned driving noise is biased by a nonzero mean and in turn pushes forward the filtering solution in time closer to the true state when it drives the system. As a result our proposed method can yield a more accurate approximate solution for the state estimation problem. © 1991-2012 IEEE.

  3. Interictal EEG discoordination in a rat seizure model.

    Science.gov (United States)

    Neymotin, Samuel A; Lee, Heekyung; Fenton, André A; Lytton, William W

    2010-12-01

    Cognitive and psychiatric comorbidities are common and clinically important in medial temporal lobe epilepsy and are likely caused by ongoing abnormalities in brain activity. In addition, it is unclear how the dynamics of interictal brain activity in medial temporal lobe epilepsy contributes to the generation of seizures. To investigate these issues, the authors evaluated multisite interictal EEG from a perinatal excitotoxic, hippocampal lesion rat model of medial temporal lobe epilepsy. Sample entropy, an information theoretical measure, demonstrated decreased complexity at different time scales and across all channels in epileptic animals. However, higher-order multiarea measures showed evidence of increased variability in population correlation measures. This apparent paradox was resolved by noting that although the EEG from epileptic animals was overall more stereotyped, there were frequent periods where two or more brain areas "broke off" from ongoing brain activity in epileptic animals, producing decorrelations between areas. These decorrelations were particularly apparent across the midline, suggesting impairments of interhemispheric coordination, a form of interhemispheric diaschisis. Both the observed alterations could contribute to a reduction in brain functionality: an overall reduction in complexity and a failure of interhemispheric brain coordination, suggesting a breakdown in communication between hemispheres. The authors speculate that any tendency of areas to lose communication or break away from coordinated brain activity might predispose to seizures in these areas.

  4. Low dose zinc supplementation beneficially affects seizure development in experimental seizure models in rats.

    Science.gov (United States)

    Kumar, Hemant; Katyal, Jatinder; Gupta, Yogendra K

    2015-02-01

    The role of zinc in seizure models and with antiepileptic drugs sodium valproate (SV) and phenytoin (PHT) was studied using experimental models of seizures in rats. Male Wistar rats, 150-250 g were administered zinc 2, 20, and 200 mg/kg, orally for 14 days. Sixty minutes after the last dose of zinc, rats were challenged with pentylenetetrazole (PTZ, 60 mg/kg, ip) or maximal electroshock (MES, 70 mA, 0.2 s duration). In another group, SV (150/300 mg/kg, ip) or PHT (40 mg/kg, ip) was administered after 30 min of zinc administration followed by seizure challenge. Zinc pretreatment at all doses had no effect on MES seizures. In PTZ seizures, with the lowest dose used, i.e., 2 mg/kg, a protective effect was observed. Neither the protection offered by the 100 % anticonvulsant dose of SV (300 mg/kg) in PTZ seizures was affected by pre-treatment with zinc nor a combination of subanticonvulsant dose of SV (150 mg/kg) and zinc offer any statistically significant advantage over either drug alone. The combination of phenytoin with zinc had no effect on any of the parameters tested. Apart from this, chronic zinc administration hampered development of chemically (PTZ)-kindled seizures in rats. Zinc supplementation is unlikely to have any undesirable effect when used in epileptics rather it may offer advantage in epileptic and seizure prone patients.

  5. Assessing the performance of data assimilation algorithms which employ linear error feedback.

    Science.gov (United States)

    Mallia-Parfitt, Noeleene; Bröcker, Jochen

    2016-10-01

    Data assimilation means to find an (approximate) trajectory of a dynamical model that (approximately) matches a given set of observations. A direct evaluation of the trajectory against the available observations is likely to yield a too optimistic view of performance, since the observations were already used to find the solution. A possible remedy is presented which simply consists of estimating that optimism, thereby giving a more realistic picture of the "out of sample" performance. Our approach is inspired by methods from statistical learning employed for model selection and assessment purposes in statistics. Applying similar ideas to data assimilation algorithms yields an operationally viable means of assessment. The approach can be used to improve the performance of models or the data assimilation itself. This is illustrated by optimising the feedback gain for data assimilation employing linear feedback.

  6. Advanced Data Assimilation for Geosciences : Lecture Notes of the Les Houches School of Physics

    CERN Document Server

    Bocquet, Marc; Cosme, Emmanuel; Cugliandolo, Leticia F

    2014-01-01

    This book gathers notes from lectures and seminars given during a three-week school on theoretical and applied data assimilation held in Les Houches in 2012. Data assimilation aims at determining as accurately as possible the state of a dynamical system by combining heterogeneous sources of information in an optimal way. Generally speaking, the mathematical methods of data assimilation describe algorithms for forming optimal combinations of observations of a system, a numerical model that describes its evolution, and appropriate prior information. Data assimilation has a long history of application to high-dimensional geophysical systems dating back to the 1960s, with application to the estimation of initial conditions for weather forecasts. It has become a major component of numerical forecasting systems in geophysics, and an intensive field of research, with numerous additional applications in oceanography and atmospheric chemistry, with extensions to other geophysical sciences. The physical complexity and ...

  7. Implementation of Localized Ensemble Assimilation for a Three-Dimensional Radiation Belt Model (Invited)

    Science.gov (United States)

    Godinez, H. C.; Chen, Y.; Kellerman, A. C.; Subbotin, D.; Shprits, Y.

    2013-12-01

    Earth's outer radiation belt is very dynamic and energetic electrons therein undergo constant changes due to acceleration, loss, and trans- port processes. In this work we improve the accuracy of simulated electron phase space density (PSD) of the Versatile Electron Radiation Belt (VERB) code, a three-dimensional radiation belt model, by implementing the localized ensemble transform Kalman filter (LETKF) assimilation method. Assimilation methods based on Kalman filtering have been successfully applied to one-dimensional radial diffusion radiation belt models, where it has been shown to greatly improve the model estimation of electron phase space density (PSD). This work expands upon previous research by implementing the LETKF method to assimilate observed electron density into VERB, a three-dimensional radiation belt model. In particular, the LETKF will perform the assimilation locally, where the size of the local region is defined by the diffusion of electrons in the model. This will enable the optimal assimilation of data throughout the model consistently with the flow of electrons. Two sets of assimilation experiments are presented. The first is an identical-twin experiment, where artificial data is generated from the same model, with the purpose of verifying the assimilation method. In the second set of experiments, real PSD observational data from missions such as CRRES and/or the Van Allen Probes are assimilated into VERB. The results show that data assimilation significantly improves the accuracy of the VERB model by efficiently including the available observations at the appropriate pitch angles, energy levels, and L-shell regions throughout the model.

  8. FEBRILE SEIZURE: RECURRENCE AND RISK FACTORS

    Directory of Open Access Journals (Sweden)

    A. TALEBIAN

    2006-06-01

    Full Text Available Background:Febrile Convulsion is the most common convulsive disorder in children,occurring in 2 to 4% of the pediatric population and recurring in 30-50% of cases. Considering the varying recurrence rates reported, thisstudy was conducted at the pediatric ward of the Shaheed BeheshtiGeneral Hospital, between 2000-2001 to determine the frequencyof recurrence and related risk factors in children presenting with theirfirst episode of febrile convulsionMaterials & Methods:A two–year cohort study was performed on 50 children presentingwith the first attack of febrile convulsion. Patient demographic dataincluding age, sex, type and duration of seizure, family history offebrile seizure or epilepsy and the interval between fever onset andoccurrence of seizure were recorded in questionnaires. Those patients,for whom prophylactic medication was not administered, werefollowed at three–month intervals for up to one year. Findings werestatistically analyzed using Fisher’s exact testResults:Recurrence was observed in twelve children (24% out of the fifty,being most common in patients aged less than one year (54.4%.Recurrence rates among children with a positive family history offebrile convulsion, presence of complex febrile seizure and positivefamily history of epilepsy were 42.1%, 42.8% and 25% respectively.From among those children with a “less than one hour” intervalbetween fever onset and occurrence of seizure, recurrence occurredin 43-7% of cases, while in those with a “more than one hourinterval”, 14.7% experienced recurrence.Conclusion:Recurrence rates are increased by certain factors including age-belowone year-, positive family history of febrile convulsion, and a “lessthan one hour” interval between time of fever onset and seizureoccurrence.

  9. NONCONVULSIVE SEIZURES AFTER SUBARACHNOID HEMORRHAGE: MULTIMODAL DETECTION AND OUTCOMES

    Science.gov (United States)

    Claassen, Jan; Perotte, Adler; Albers, David; Kleinberg, Samantha; Schmidt, J. Michael; Tu, Bin; Badjatia, Neeraj; Lantigua, Hector; Hirsch, Lawrence J.; Mayer, Stephan A.; Connolly, E. Sander; Hripcsak, George

    2013-01-01

    Objective Seizures have been implicated as a cause of secondary brain injury, but the systemic and cerebral physiologic effects of seizures after acute brain injury are poorly understood. Methods We analyzed intracortical EEG and multimodality physiological recordings in 48 comatose subarachnoid hemorrhage patients to better characterize the physiological response to seizures after acute brain injury. Results Intracortical seizures were seen in 38% of patients and 8% had surface seizures. Intracortical seizures were accompanied by elevated heart rate (P=0.001), blood pressure (P<0.001), and respiratory rate (P<0.001). There were trends for rising cerebral perfusion pressure (P=0.03) and intracranial pressure (P =0.06) seen after seizure onset. Intracortical seizure associated increases in global brain metabolism, partial brain tissue oxygenation, and regional cerebral blood flow (rCBF) did not reach significance, but a trend for a pronounced delayed rCBF rise was seen for surface seizures (P=0.08). Functional outcome was very poor for patients with severe background attenuation without seizures and best for those without severe attenuation or seizures (77% vs. 0% dead or severely disabled, respectively). Outcome was intermediate for those with seizures independent of the background EEG and worse for those with intracortical only seizures when compared to those with intracortical and scalp seizures (50% and 25% death or severe disability, respectively). Interpretation We replicated in humans complex physiologic processes associated with seizures after acute brain injury previously described in laboratory experiments and illustrated differences such as the delayed increase in regional cerebral blood flow. These real-world physiologic observations may permit more successful translation of laboratory research to the bedside. PMID:23813945

  10. The Race Race: Assimilation in America

    Science.gov (United States)

    Balis, Andrea; Aman, Michael

    2013-01-01

    Can race and assimilation be taught? Interdisciplinary pedagogy provides a methodology, context, and use of nontraditional texts culled from American cultural history such as from, theater and historical texts. This approach and these texts prove useful for an examination of race and assimilation in America. The paper describes a course that while…

  11. MoSST DAS: The First Working Geomagnetic Data Assimilation System

    Science.gov (United States)

    Kuang, Weijia; Wei, Zigang; Tangborn, Andrew

    2011-01-01

    The Earth possesses an internal magnetic field (geomagnetic field) generated by convection in the outer core (geodynamo). Previous efforts have been focused along two distinct paths: (1) numerical geodynamo modeling to understand the origin of the geomagnetic field, and the mechanisms of geomagnetic secular variations (SV); and (2) geomagnetic field modeling to map the spatial/temporal variations of the field from geomagnetic data, and to derive core properties, e.g. inversion of core flow near the core-mantle boundary (CMB). Geomagnetic data assimilation is a new approach emerged over the past 5 years: surface observations are assimilated with geodynamo models for better understanding of the core dynamical state, and accurately prediction of SV. In collaboration with several geomagnetic research groups, we have developed the first working geomagnetic data assimilation system, Modular, Scalable, Self-consistent, and Three-dimensional (MoSST) DAS, that includes the MoSST numerical dynamo model; 7000 years of geomagnetic field maps from several field models utilizing satellite and ground observatory data, historical magnetic records and archeo/paleo magnetic data; and an ensemble based optimal interpolation (01) assimilation algorithm. With this system, we have demonstrated clearly that the assimilated core dynamical state is substantially different from those of pure geodynamo simulations. Ensemble assimilation runs also show the convergence of the assimilated solutions inside the core, suggesting that the simulation state is pulled closer to the truth via data assimilation. The forecasts from this system are also very accurate: the 5-year forecast of the geomagnetic field agrees very well with the observations; and the 5-year secular variation forecast is more accurate than the IGRF SV forecast models in the past. Using geomagnetic records up to 2009, we have made an SV forecast for the period from 2010-2015, and is a candidate SV model for IGRF-11.

  12. Nerve agent-induced seizures and their pharmacological modulation

    Energy Technology Data Exchange (ETDEWEB)

    McDonough, J.H.; Shih, T.M.; Adams, N.L.; Koviak, T.A.; Cook, L.A.

    1993-05-13

    Intoxication with nerve agents produces prolonged central nervous system seizures (status epilepticus) that can produce irreversible brain pathology (15). This report summarizes our recent findings regarding the neurotransmitter changes that occur in discrete brain regions as a function of seizure duration and the differential effectiveness of anticholinergic, benzodiazepine and excitatory amino acid (EAA) antagonist drugs in terminating soman-induced seizures when given at different times after seizure onset. These results are discussed in relation to a model we have proposed to explain the sequence of electrophysiological, biochemical and neurochemical events and mechanisms controlling nerve agent-induced seizures.

  13. Assimilation de données: les propriétés asymptotiques du filtre de Kalman d'ensemble

    OpenAIRE

    Tran, Vu Duc

    2009-01-01

    This thesis is concerned with the data assimilation methods which combine the dynamical model with the observations. We present the well-known methods: statistical interpolation, variational data assimilation methods and sequential data assimilation methods. We are particularly interested in the Ensemble Kalman Filter (EnKF) which is more and more used in the oceanographic applications. The Ensemble Kalman Filter has been initially proposed as approximation of the Kalman filter in the case of...

  14. SERUM ZINC LEVEL IN PATIENTS WITH SIMPLE FEBRILE SEIZURE

    Directory of Open Access Journals (Sweden)

    Farhad HEYDARIAN

    2010-10-01

    Full Text Available ObjectiveTo evaluate the serum zinc level of the patients with simple febrile seizure and compare them with febrile children without seizure.Materials & MethodsThis prospective case - control study was performed on 60 patients aged 6 months to 6 years from Apr. 2009 to Jan.2010 in Ghaem, Imam Reza and Dr. Sheikh Hospitals in Mashhad. The serum zinc level was assessed and compared between the cases (30 individuals who suffered from simple febrile seizure and the controls (30 individuals who had fever without seizure.ResultsMean serum zinc level was 663.7 µg /l and 758.33  µg /l in the case group and the control group, respectively (PConclusionIt was revealed that the serum level of zinc was significantly lower in children with simple febrile seizure in comparison with febrile children without seizure.Keywords: Simple febrile seizure, children, zinc, CSF (cerebrospinal fluid

  15. [Electroclinical characteristics of seizures in the Aicardi syndrome].

    Science.gov (United States)

    Bour, F; Chiron, C; Dulac, O; Plouin, P

    1986-12-01

    Electro-clinical patterns of seizures were studied in 7 infants with Aicardi Syndrome. In all 7 cases, partial seizure preceded the appearance of asymetrical spasms. Partial seizures and spasms were recorded by polygraphing tracings of long duration. There was a constant correlation between the EEG localization of partial seizures and the side of asymetrical spasms. In 6 cases, a cluster of spasms followed the partial discharge whereas in the 7th case, the partial discharge appeared in the middle of the cluster. Therefore, both partial seizure and cluster of spasms seem to be part of the same critical manifestation. The authors have recorded the same king of seizures in other malformative syndromes (lissencephaly, Bourneville disease) and compare them to those recorded in Aicardi Syndrome. In Aicardi Syndrome, this type of seizures might be in relation with the association of a corpus callosum agenesy and paraventricular heterotopies.

  16. Suspected exercise-induced seizures in a young dog.

    Science.gov (United States)

    Motta, L; Dutton, E

    2013-04-01

    A 12-month-old female neutered crossbreed was referred for investigation of seizure-like episodes occurring only at intense exercise. Thorough medical, neurological and cardiac investigations were performed and excluded the most commonly known causes of seizure-like activity. The dog was fitted with an ambulatory electrocardiography device and underwent another exercise-induced seizure. The electrocardiogram during the episode revealed a sinus tachycardia at approximately 300 beats/minute. A video recording of the episode revealed generalised tonic clonic limb activity with jaw chomping and frothing at the mouth typical of seizure activity. Antiepileptic medications were not prescribed and the owner was advised not to exercise the dog intensely. The dog responded well and did not seizure after 12 months of mild-moderate off-lead exercise. As all the seizures in this case were triggered by intense physical activity, it is suggested that this may be a new form of reflex seizure activity.

  17. Analysis of Seizure EEG in Kindled Epileptic Rats

    Directory of Open Access Journals (Sweden)

    A. K. Sen

    2007-01-01

    Full Text Available Using wavelet analysis we have detected the presence of chirps in seizure EEG signals recorded from kindled epileptic rats. Seizures were induced by electrical stimulation of the amygdala and the EEG signals recorded from the amygdala were analyzed using a continuous wavelet transform. A time–frequency representation of the wavelet power spectrum revealed that during seizure the EEG signal is characterized by a chirp-like waveform whose frequency changes with time from the onset of seizure to its completion. Similar chirp-like time–frequency profiles have been observed in newborn and adult patients undergoing epileptic seizures. The global wavelet spectrum depicting the variation of power with frequency showed two dominant frequencies with the largest amounts of power during seizure. Our results indicate that a kindling paradigm in rats can be used as an animal model of human temporal lobe epilepsy to detect seizures by identifying chirp-like time–frequency variations in the EEG signal.

  18. α-Spinasterol, a TRPV1 receptor antagonist, elevates the seizure threshold in three acute seizure tests in mice

    OpenAIRE

    2015-01-01

    α-Spinasterol is a plant-derived compound which was reported to act as a selective antagonist for the transient receptor potential vanilloid 1 (TRPV1) receptor. Several studies revealed that the TRPV1 receptors might modulate seizure activity in animal models of seizures and epilepsy. The aim of the present study was to investigate the effect of α-spinasterol on the seizure threshold in three acute models of seizures, i.e., in the intravenous (i.v.) pentylenetetrazole (PTZ) seizure test, in t...

  19. SEIZURE SEVERITY AS AN ALTERNATIVE MEASURE OF OUTCOME IN EPILEPSY

    Directory of Open Access Journals (Sweden)

    Koraliya S. Todorova

    2013-07-01

    Full Text Available Seizure severity emerges as an important aspect of epilepsy. This is most relevant in refractory patients in whom complete remission of seizures is unlikely and reduced seizure severity may be a significant determinant of psychosocial well-being with a consequent improvement in quality of life (QOL. Thus a valid measure of seizure severity can serve both as an indicator of clinical outcome and as an evaluation tool of the interaction between seizures and the psychosocial complications of epilepsy.After a brief review of the most frequently used scales measuring seizure severity in adults with epilepsy we have explored the relationship between seizure severity and QOL in a set of 103 patients. Two self-evaluation questionnaires were applied: the Seizure Severity Questionnaire (SSQ and the Quality of Life in Epilepsy Inventory (QOLIE-31. The severity of the coexisting depression, an important confounder in the relationship between seizure severity and QOL, was assessed by the Hamilton Depression Rating Scale (HAMD-17.All domains of the Quality-of-Life in Epilepsy Inventory (QOLIE-31 correlated highly significantly with seizure severity (p≤0.01. The correlation was strong for the Overall score (r=-0.70; p≤0.001 and the Seizure worry domain (r=-0.71; p≤0.001. When the potentially confounding effect of depression was controlled for, the regression of seizure severity with the QOLIE-31 Overall score (P=0.001; R²=0.56 and the Seizure worry domain (P=0.001; R²=0.50 remained significant. These findings indicate that seizure severity is strongly associated with QOL in epilepsy and could be used as an alternative indicator of outcome in clinical research.

  20. Mutations in KPTN Cause Macrocephaly, Neurodevelopmental Delay, and Seizures

    Science.gov (United States)

    Baple, Emma L.; Maroofian, Reza; Chioza, Barry A.; Izadi, Maryam; Cross, Harold E.; Al-Turki, Saeed; Barwick, Katy; Skrzypiec, Anna; Pawlak, Robert; Wagner, Karin; Coblentz, Roselyn; Zainy, Tala; Patton, Michael A.; Mansour, Sahar; Rich, Phillip; Qualmann, Britta; Hurles, Matt E.; Kessels, Michael M.; Crosby, Andrew H.

    2014-01-01

    The proper development of neuronal circuits during neuromorphogenesis and neuronal-network formation is critically dependent on a coordinated and intricate series of molecular and cellular cues and responses. Although the cortical actin cytoskeleton is known to play a key role in neuromorphogenesis, relatively little is known about the specific molecules important for this process. Using linkage analysis and whole-exome sequencing on samples from families from the Amish community of Ohio, we have demonstrated that mutations in KPTN, encoding kaptin, cause a syndrome typified by macrocephaly, neurodevelopmental delay, and seizures. Our immunofluorescence analyses in primary neuronal cell cultures showed that endogenous and GFP-tagged kaptin associates with dynamic actin cytoskeletal structures and that this association is lost upon introduction of the identified mutations. Taken together, our studies have identified kaptin alterations responsible for macrocephaly and neurodevelopmental delay and define kaptin as a molecule crucial for normal human neuromorphogenesis. PMID:24239382

  1. A New Approach to Data Assimilation

    Institute of Scientific and Technical Information of China (English)

    Wang Bin; ZHAO Ying

    2006-01-01

    A significant attempt to design a timesaving and efficient four-dimensional variational data assimilation dimensional variational data assimilation of mapped observation (3DVM)' is proposed, based on the new concept of mapped observation and the new idea of backward 4DVar. Like the available 4DVar, 3DVM produces an optimal initial condition (IC) that is consistent with the prediction model due to the inclusion of model constraints and best fits the observations in the assimilation window through the model solution trajectory. Different from the 4DVar, the IC derived from 3DVM is located at the end of the assimilation window rather than at the beginning conventionally. This change greatly reduces the computing cost for the new approach, which is almost the same as that of the three-dimensional variational data assimilation (3DVar). Especially, such a change is able to improve assimilation accuracy because it does not need the tangential linear and adjoint approximations to calculate the gradient of cost function. Therefore,in numerical test, the new approach produces better IC than 4DVar does for 72-h simulation of TY9914(Dan), by assimilating the three-dimensional fields of temperature and wind retrieved from the Advanced Microwave Sounding Unit-A (AMSU-A) observations. Meanwhile, it takes only 1/7 of the computing cost that the 4DVar requires for the same initialization with the same retrieved data.

  2. Local cerebral metabolism during partial seizures

    Energy Technology Data Exchange (ETDEWEB)

    Engel, J. Jr.; Kuhl, D.E.; Phelps, M.E.; Rausch, R.; Nuwer, M.

    1983-04-01

    Interictal and ictal fluorodeoxyglucose scans were obtained with positron CT from four patients with spontaneous recurrent partial seizures, one with epilepsia partialis continua, and one with a single partial seizure induced by electrical stimulation of the hippocampus. Ictal metabolic patterns were different for each patient studied. Focal and generalized increased and decreased metabolism were observed. Ictal hypermetabolism may exceed six times the interictal rate and could represent activation of excitatory or inhibitory synapses in the epileptogenic region and its projection fields. Hypometabolism seen on ictal scans most likely reflects postictal depression and may indicate projection fields of inhibited neurons. No quantitative relationship between alterations in metabolism and EEG or behavioral measurements of ictal events could be demonstrated.

  3. Physics of the Brain: Interaction of the Optical-Fiber-Guided Multi-Ultraviolet-Photon Beams with the Epilepsy Topion, (the Seizure Onset Area)

    Science.gov (United States)

    Stefan, V. Alexander

    A novel method for the possible prevention of epileptic seizures is proposed, based on the multi-ultraviolet-photon beam interaction with the epilepsy topion, (nonlinear coupling of an ultra high frequency mode to the brain beta phonons). It is hypothesized that epilepsy is a chaotic-dynamics phenomenon: small electrical changes in the epilepsy-topion lead, (within the 10s of milliseconds), to the onset of chaos, (seizure--excessive electrical discharge), and subsequent cascading into adjacent areas. The ultraviolet photons may control the imbalance of sodium and potassium ions and, consequently, may prove to be efficient in the prevention of epileptic seizures. Supported by Nikola Tesla Labs, Stefan University.

  4. Seizures beget seizures: the quest for GABA as a key player.

    Science.gov (United States)

    Ben-Ari, Yehezkel

    2006-01-01

    Synapses mediated by gamma-aminobutyric acid (GABA) A receptors are notoriously altered during periods of enhanced activity. Since a loss of inhibitory tone is a basic cause of seizures and epilepsies, it is important to determine the underlying mechanisms and the way this could be alleviated or at least reduced. Alterations of the intracellular content of chloride are thought to be a major player in the sequence of events that follow episodes of hyperactivity. In this review, I discuss these mechanisms both in the adult and developing brain, relying on studies in which chloride and GABAergic currents were measured by electrophysiological and imaging techniques. The main conclusion is that in adult systems, status epilepticus induces a complete re-organization of the networks, with cell death, axonal growth, and glutamatergic neosynapse formation leading to an increased glutamatergic drive. This, in turn, will decrease the threshold of seizure generation and thus contribute to seizure generation. In contrast, GABAergic synapses are not readily "plastic" as the lost interneurones and synapses are not replaced. Somatostatin-positive 0-LM Interneurons that innervate the dendrites of the principal cells in the hippocampus degenerate selectively, leading to a loss of the inhibitory drive in the dendrites, whereas somatic projecting basket cells and somatic inhibitory drives are relatively spared. This imbalance leads to a reduction of the inhibitory strength that is necessary but not sufficient to generate ongoing seizures. An additional important factor is the persistent increase of the intracellular chloride concentration that leads to a long-lasting shift in the depolarizing direction of the actions of GABA that will also contribute to seizure generation. In the developing brain, a major source of seizure generation is the depolarizing and often excitatory actions of GABA due to a higher intracellular chloride concentration ([Cl-]I) in immature neurons, a property

  5. The importance of peers: assimilation patterns among second-generation Turkish immigrants in Western Europe

    NARCIS (Netherlands)

    Ali, S.; Fokkema, C.M.

    2011-01-01

    The two dominant approaches to immigrant assimilation, segmented assimilation and "new" assimilation theories, have been successful at reporting and analyzing between-group differences in assimilation patterns. However, studies of assimilation generally do not address differences at the individual l

  6. Seizure Following Topical Gammabenzene Hexachloride Therapy

    Directory of Open Access Journals (Sweden)

    Biswas Animesh

    2002-01-01

    Full Text Available Development of short-lived, self-limiting major epileptic seizures following an improper application of gammabenzene hexachloride (GBHC lotion in a 15 month old boy suffering from scabies with secondary bacterial infection is reported here due to its rarity in clinical practice and, more particularly, to stress the need of correct instructions on the use of GBHC application for the prevention of iatrogenic neurotoxicity.

  7. Data assimilation in integrated hydrological modelling

    DEFF Research Database (Denmark)

    Rasmussen, Jørn

    are assimilated significant improvements are obtained in both stream flow and groundwater modeling. However, the successfulness of both the state updating and the parameter estimation is conditioned on a sufficiently large ensemble size, as spurious correlations often had a negative impact on the performance...... of the data assimilation algorithm. To reduce the impact of spurious correlation, an adaptive localization method is applied, which significantly improved the performance of the assimilation while reducing the computational requirements. Finally, as observation bias is common in groundwater head observations...

  8. The Acceleration of Immigrant Unhealthy Assimilation.

    Science.gov (United States)

    Giuntella, Osea; Stella, Luca

    2017-04-01

    It is well known that immigrants tend to be healthier than US natives and that this advantage erodes with time spent in the USA. However, we know less about the heterogeneity of these trajectories among arrival cohorts. Recent studies have shown that later arrival cohorts of immigrants have lower entry wages and experience less economic assimilation. In this paper, we investigate whether similar cohort effects can be observed in the weight assimilation of immigrants in the USA. Focusing on obesity, we show that more recent immigrant cohorts arrive with higher obesity rates and experience a faster 'unhealthy assimilation' in terms of weight gain. Copyright © 2016 John Wiley & Sons, Ltd.

  9. Data assimilation experiments with MPIESM climate model

    Directory of Open Access Journals (Sweden)

    Belyaev Konstantin

    2016-01-01

    Full Text Available Further development of data assimilation technique and its application in numerical experiments with state-of-the art Max Plank Institute Earth System model have been carried out. In particularly, the stability problem of assimilation is posed and discussed In the experiments the sea surface height data from archive Archiving, Validating and Interpolating Satellite Ocean have been used. All computations have been realized on cluster system of German Climate Computing Center. The results of numerical experiments with and without assimilation were recorded and analyzed. A special attention has been focused on the Arctic zone. It is shown that there is a good coincidence of model tendencies and independent data.

  10. Ictal alterations of consciousness during ecstatic seizures.

    Science.gov (United States)

    Picard, Fabienne; Kurth, Florian

    2014-01-01

    Patients with ecstatic epileptic seizures report an altered consciousness, which they describe as a sense of heightened perception of themselves – they “feel very present” – and an increased vividness of sensory perceptions. Recently, the anterior insula has been proposed as the region where these seizures originate, based on the results of ictal nuclear imaging in three patients, the first induction of ecstatic auras by electrical stimulation, and the functional characteristics of the anterior insula in neuroimaging literature. Specifically, the anterior insula is thought to play a key role in integrating information from within the body, the external world, as well as the emotional states. In addition, the anterior insula is thought to convert this integrated information into successive global emotional moments, thus enabling both the construct of a sentient self as well as a mechanism for predictive coding. As part of the salience network, this region is also involved in switching from mind wandering toward attentional and executive processing. In this review, we will summarize previous patient reports and recap how insular functioning may be involved in the phenomenon of ecstatic seizures. Furthermore, we will relate these hypotheses to the results from research on meditation and effects of drug abuse.

  11. Magnetic resonance imaging in complex partial seizures

    Energy Technology Data Exchange (ETDEWEB)

    Furune, Sunao; Negoro, Tamiko; Maehara, Mitsuo; Nomura, Kazushi; Miura, Kiyokuni; Takahashi, Izumi; Watanabe, Kazuyoshi (Nagoya Univ. (Japan). Faculty of Medicine)

    1989-09-01

    Magnetic resonance imaging (MRI) and computed tomography (CT) were performed on 45 patients with intractable complex partial seizures. MRI was performed with a superconducting whole-body scanner operating at 0.5 tesla (T) and 1.5 T. In patients with temporal lobe epilepsy, 8 of 24 patients had abnormal CT, but 16 or 24 patients showed abnormal MRI. 1.5 T MRI detected more abnormality than 0.5 T MRI when CT was normal. In patients with frontal lobe epilepsy, 5 of 7 patients had normal CT and MRI. In 2 other patients, MRI demonstrated an arachnoid cyst and increased signal intensity area on the T2-weighted images which were not detected by CT. In patients with occipital lobe epilepsy, 5 of 6 patients show abnormal CT and MRI. In patients with tuberous sclerosis, MRI revealed some increased signal intensity areas on the T2-weighted images in the occipital and temporal lobe, which were not detected by CT. Most surface EEG foci corresponded with the side of MRI abnormality. These data indicate that MRI is more informative than CT in complex partial seizures. MRI is the imaging technique of choice in the diagnosis of complex partial seizures. (author).

  12. Hybrid variational-ensemble assimilation of lightning observations in a mesoscale model

    Directory of Open Access Journals (Sweden)

    K. Apodaca

    2014-05-01

    Full Text Available Lightning measurements from the Geostationary Lightning Mapper (GLM that will be aboard the Goestationary Operational Environmental Satellite – R Series will bring new information that can have the potential for improving the initialization of numerical weather prediction models by assisting in the detection of clouds and convection through data assimilation. In this study we focus on investigating the utility of lightning observations in mesoscale and regional applications suitable for current operational environments, in which convection cannot be explicitly resolved. Therefore, we examine the impact of lightning observations on storm environment. Preliminary steps in developing a lightning data assimilation capability suitable for mesoscale modeling are presented in this paper. World Wide Lightning Location Network (WWLLN data was utilized as a proxy for GLM measurements and was assimilated with the Maximum Likelihood Ensemble Filter, interfaced with the Nonhydrostatic Mesoscale Model core of the Weather Research and Forecasting system (WRF-NMM. In order to test this methodology, regional data assimilation experiments were conducted. Results indicate that lightning data assimilation had a positive impact on the following: information content, influencing several dynamical variables in the model (e.g., moisture, temperature, and winds, improving initial conditions, and partially improving WRF-NMM forecasts during several data assimilation cycles.

  13. Unsupervised EEG analysis for automated epileptic seizure detection

    Science.gov (United States)

    Birjandtalab, Javad; Pouyan, Maziyar Baran; Nourani, Mehrdad

    2016-07-01

    Epilepsy is a neurological disorder which can, if not controlled, potentially cause unexpected death. It is extremely crucial to have accurate automatic pattern recognition and data mining techniques to detect the onset of seizures and inform care-givers to help the patients. EEG signals are the preferred biosignals for diagnosis of epileptic patients. Most of the existing pattern recognition techniques used in EEG analysis leverage the notion of supervised machine learning algorithms. Since seizure data are heavily under-represented, such techniques are not always practical particularly when the labeled data is not sufficiently available or when disease progression is rapid and the corresponding EEG footprint pattern will not be robust. Furthermore, EEG pattern change is highly individual dependent and requires experienced specialists to annotate the seizure and non-seizure events. In this work, we present an unsupervised technique to discriminate seizures and non-seizures events. We employ power spectral density of EEG signals in different frequency bands that are informative features to accurately cluster seizure and non-seizure events. The experimental results tried so far indicate achieving more than 90% accuracy in clustering seizure and non-seizure events without having any prior knowledge on patient's history.

  14. Perspectives on seizure clusters: Gaps in lexicon, awareness, and treatment.

    Science.gov (United States)

    Buelow, Janice M; Shafer, Patricia; Shinnar, Ruth; Austin, Joan; Dewar, Sandra; Long, Lucretia; O'Hara, Kathryn; Santilli, Nancy

    2016-04-01

    Seizure clusters in epilepsy can result in serious outcomes such as missed work or school, postictal psychosis, emergency room visits, or hospitalizations, and yet they are often not included in discussions between health-care professionals (HCPs) and their patients. The purpose of this paper was to describe and compare consumer (patient and caregivers) and professional understanding of seizure clusters and to describe how consumers and HCPs communicate regarding seizure clusters. We reviewed social media discussion sites to explore consumers' understanding of seizure clusters. We analyzed professional (medical) literature to explore the HCPs' understanding of seizure clusters. Major themes were revealed in one or both groups, including: communication about diagnosis; frequency, duration, and time frame; seizure type and pattern; severity; and self-management. When comparing discussions of professionals and consumers, both consumers and clinicians discussed the definition of seizure clusters. Discussions of HCPs were understandably clinically focused, and consumer discussions reflected the experience of seizure clusters; however, both groups struggled with a common lexicon. Seizure cluster events remain a problem associated with serious outcomes. Herein, we outline the lack of a common understanding and recommend the development of a common lexicon to improve communication regarding seizure clusters.

  15. Post-stroke seizures in consecutive elderly stroke patients

    Institute of Scientific and Technical Information of China (English)

    Yue Chen; Lufang Chen; Yiqing Tao; Maomao Han; Chunlan Cui; Shichao Liu

    2011-01-01

    This prospective study sought to investigate the clinical, radiological and electroencephalographic (EEG) characteristics of seizures in elderly stroke patients, and their outcomes. Over a 2-year study period, 158 consecutive eldedy patients with stroke were examined and followed up. Of these patients, 32 (20%) developed seizures, primarily related to stroke, within a follow up period between 5 months and 2 years. Of these 32 cases, 20 experienced infarctions, and 12 experienced hemorrhages. Involvement of cortical regions was detected in most of the patients exhibiting seizures. In these patients, 44% of the lesions involved cortical areas exclusively or in addition to subcortical areas observed on computed tomography (CT) images. Twenty-five patients (78%)developed early seizures (within 2 weeks after stroke), and half exhibited immediate post-stroke seizures. None of the patients exhibiting early onset seizures developed recurrent seizures or epilepsy, while 57% of late onset seizures (four cases) developed epilepsy. No specific EEG patterns were apparent in those who later developed epilepsy. Overall, early onset seizures after stroke were found to be relatively common, and did not affect outcome. Late onset seizures were less common, but were associated with chronic epilepsy.

  16. Epileptic Seizure Prediction Using a New Similarity Index for Chaotic Signals

    Science.gov (United States)

    Niknazar, Hamid; Nasrabadi, Ali Motie

    Epileptic seizures are generated by abnormal activity of neurons. The prediction of epileptic seizures is an important issue in the field of neurology, since it may improve the quality of life of patients suffering from drug resistant epilepsy. In this study a new similarity index based on symbolic dynamic techniques which can be used for extracting behavior of chaotic time series is presented. Using Freiburg EEG dataset, it is found that the method is able to detect the behavioral changes of the neural activity prior to epileptic seizures, so it can be used for prediction of epileptic seizure. A sensitivity of 63.75% with 0.33 false positive rate (FPR) in all 21 patients and sensitivity of 96.66% with 0.33 FPR in eight patients were achieved using the proposed method. Moreover, the method was evaluated by applying on Logistic and Tent map with different parameters to demonstrate its robustness and ability in determining similarity between two time series with the same chaotic characterization.

  17. Epileptic seizures in patients with a posterior circulation infarct

    Directory of Open Access Journals (Sweden)

    Yüksel Kaplan

    2014-08-01

    Full Text Available OBJECTIVE: The aim of this study was to investigate the frequency of seizures and the clinical features of patients with seizures related to a posterior circulation infarct (POCI. METHODS: We reviewed all ischemic stroke patients admitted to our clinic between January 2011 and January 2012. The patients’ database information was retrospectively analyzed. Fifty-five patients with a POCI were included in the study. We reviewed all patients with epileptic seizures related to a POCI. Age, gender, recurrent stroke, risk factors, etiology, radiographic localization, the seizure type and onset time, and the electroencephalographic findings of patients were evaluated. We excluded all patients who had precipitating conditions during seizures such as taking drugs, acid-base disturbances, electrolyte imbalance, and history of epilepsy. RESULTS: Seizures were observed in four patients (3 male, 1 female with a POCI related epileptic seizures (7.2%. The etiology of strokes was cardiac-embolic in 3 patients and vertebral artery dissection in 1 patient. Seizures occurred in 2 patients as presenting finding, in 1 patient within 7 days, and 1 patient within 28 days. Primary generalized tonic-clonic seizures occurred in 3 patients and simple partial seizures with secondary generalization in 1 patient. Three patients had cerebellum infarction at the left hemisphere. One patient had lateral medullary infarction at the right side. The electroencephalographic findings of patients were normal. CONCLUSION: Studies involving patients with seizures related to a POCI are novel and few in number. Three patients with seizure had cerebellum infarction. The cerebellum in these patients may contribute via different mechanisms over seizure activity.

  18. Technical report series on global modeling and data assimilation. Volume 4: Documentation of the Goddard Earth Observing System (GEOS) data assimilation system, version 1

    Science.gov (United States)

    Suarez, Max J. (Editor); Pfaendtner, James; Bloom, Stephen; Lamich, David; Seablom, Michael; Sienkiewicz, Meta; Stobie, James; Dasilva, Arlindo

    1995-01-01

    This report describes the analysis component of the Goddard Earth Observing System, Data Assimilation System, Version 1 (GEOS-1 DAS). The general features of the data assimilation system are outlined, followed by a thorough description of the statistical interpolation algorithm, including specification of error covariances and quality control of observations. We conclude with a discussion of the current status of development of the GEOS data assimilation system. The main components of GEOS-1 DAS are an atmospheric general circulation model and an Optimal Interpolation algorithm. The system is cycled using the Incremental Analysis Update (IAU) technique in which analysis increments are introduced as time independent forcing terms in a forecast model integration. The system is capable of producing dynamically balanced states without the explicit use of initialization, as well as a time-continuous representation of non- observables such as precipitation and radiational fluxes. This version of the data assimilation system was used in the five-year reanalysis project completed in April 1994 by Goddard's Data Assimilation Office (DAO) Data from this reanalysis are available from the Goddard Distributed Active Center (DAAC), which is part of NASA's Earth Observing System Data and Information System (EOSDIS). For information on how to obtain these data sets, contact the Goddard DAAC at (301) 286-3209, EMAIL daac@gsfc.nasa.gov.

  19. Detection of Epilepsy from EEG Signal during Seizure Using Entropy-Based Fuzzy c-Means

    Directory of Open Access Journals (Sweden)

    Tahir Ahmad

    2012-09-01

    Full Text Available One of the major roles of Electrocephalography (EEG is an aid to diagnose epilepsy. Abnormal patterns such as spikes, sharp wave complexes can be seen. Our main interest is to extract information about the dynamics from a few observations of this record signal. In this study, the entropy-based fuzzy c-Means is used to cluster EEG signal of patients during an epileptic seizure.We obtained signatures of general epilepsy by superimposing results of the method.

  20. Assimilative and non-assimilative color spreading in the watercolor configuration

    Directory of Open Access Journals (Sweden)

    Eiji eKimura

    2014-09-01

    Full Text Available A colored line flanking a darker contour will appear to spread its color onto an area enclosed by the line (watercolor effect. The watercolor effect has been characterized as an assimilative effect, but non-assimilative color spreading has also been demonstrated in the same spatial configuration; e.g., when a black inner contour (IC is paired with a blue outer contour (OC, yellow color spreading can be observed. To elucidate visual mechanisms underlying these different color spreading effects, this study investigated the effects of luminance ratio between the double contours on the induced color by systematically manipulating the IC and OC luminances (Experiment 1 as well as the background luminance (Experiment 2. The results showed that the luminance conditions suitable for assimilative and non-assimilative color spreading were nearly opposite. When the Weber contrast of the IC to the background luminances (IC contrast was smaller than that of the OC (OC contrast, the induced color became similar to the IC color (assimilative spreading. In contrast, when the OC contrast was smaller than or equal to the IC contrast, the induced color became yellow (non-assimilative spreading. Extending these findings, Experiment 3 showed that bilateral color spreading, e.g., assimilative spreading on one side and non-assimilative spreading on the other side, can also be observed in the watercolor configuration. These results suggest that the assimilative and non-assimilative spreading were mediated by different visual mechanisms. The properties of the assimilative spreading are consistent with the model proposed to account for neon color spreading [Grossberg, S. & Mingolla, E. (1985 Percept. Psychophys., 38, 141-171] and extended for the watercolor effect [Pinna, B., & Grossberg, S. (2005 J. Opt. Soc. Am. A, 22, 2207-2221]. However, the present results suggest that additional mechanisms are needed to account for the non-assimilative color spreading.

  1. IS ASSIMILATION THEORY DEAD? THE EFFECT OF ASSIMILATION ON ADOLESCENT WELL-BEING

    OpenAIRE

    Greenman, Emily; Xie, Yu

    2008-01-01

    The relationship between assimilation and the well-being of immigrant children has been the focus of debate in the recent sociological literature. Much of this work has questioned whether classical theories of immigrant adaptation, which assumed assimilation to be an integral part of the process of upward mobility for immigrants, are still applicable to today’s immigrant children. This study reevaluates the applicability of classical assimilation theory with a comprehensive empirical assessme...

  2. Development of a data assimilation algorithm

    DEFF Research Database (Denmark)

    Thomsen, Per Grove; Zlatev, Zahari

    2008-01-01

    efficiently observations in a large-scale model (for example, in order to obtain more reliable initial values). Variational data assimilation techniques are based on a combination of three very important components • numerical methods for solving differential equations, • splitting procedures......It is important to incorporate all available observations when large-scale mathematical models arising in different fields of science and engineering are used to study various physical and chemical processes. Variational data assimilation techniques can be used in the attempts to utilize...... assimilation technique is applied. Therefore, it is important to study the interplay between the three components of the variational data assimilation techniques as well as to apply powerful parallel computers in the computations. Some results obtained in the search for a good combination of numerical methods...

  3. ITERATIVE ALGORITHMS FOR DATA ASSIMILATION PROBLEMS

    Institute of Scientific and Technical Information of China (English)

    2002-01-01

    Iterative algorithms for solving the data assimilation problems are considered, based on the main and adjoint equations. Spectral properties of the control operators of the problem are studied, the iterative algorithms are justified.

  4. ERP ASSIMILATION: AN END-USER APPROACH

    Directory of Open Access Journals (Sweden)

    Hurbean Luminita

    2013-07-01

    The paper discusses the ERP adoption based on the IT assimilation theory. The ERP lifecycle is associated with the IT assimilation steps. We propose a distribution of these steps along the lifecycle. Derived from the findings in the reviewed literature we will focus the cultural factors, in particular those related to the end-users (determined as a major impact factor in our previous study: Negovan et al., 2011. Our empirical study is centred on the end-users perspective and it tries to determine if and how their behaviour affects the achievement of the ERP assimilation steps. The paper reasons that organizations that understand the IT assimilation steps correlated to the ERP implementation critical factors are more likely to implement and use ERP successfully.

  5. Synchronicity in predictive modelling: a new view of data assimilation

    Science.gov (United States)

    Duane, G. S.; Tribbia, J. J.; Weiss, J. B.

    2006-11-01

    The problem of data assimilation can be viewed as one of synchronizing two dynamical systems, one representing "truth" and the other representing "model", with a unidirectional flow of information between the two. Synchronization of truth and model defines a general view of data assimilation, as machine perception, that is reminiscent of the Jung-Pauli notion of synchronicity between matter and mind. The dynamical systems paradigm of the synchronization of a pair of loosely coupled chaotic systems is expected to be useful because quasi-2D geophysical fluid models have been shown to synchronize when only medium-scale modes are coupled. The synchronization approach is equivalent to standard approaches based on least-squares optimization, including Kalman filtering, except in highly non-linear regions of state space where observational noise links regimes with qualitatively different dynamics. The synchronization approach is used to calculate covariance inflation factors from parameters describing the bimodality of a one-dimensional system. The factors agree in overall magnitude with those used in operational practice on an ad hoc basis. The calculation is robust against the introduction of stochastic model error arising from unresolved scales.

  6. Synchronicity in predictive modelling: a new view of data assimilation

    Directory of Open Access Journals (Sweden)

    G. S. Duane

    2006-01-01

    Full Text Available The problem of data assimilation can be viewed as one of synchronizing two dynamical systems, one representing "truth" and the other representing "model", with a unidirectional flow of information between the two. Synchronization of truth and model defines a general view of data assimilation, as machine perception, that is reminiscent of the Jung-Pauli notion of synchronicity between matter and mind. The dynamical systems paradigm of the synchronization of a pair of loosely coupled chaotic systems is expected to be useful because quasi-2D geophysical fluid models have been shown to synchronize when only medium-scale modes are coupled. The synchronization approach is equivalent to standard approaches based on least-squares optimization, including Kalman filtering, except in highly non-linear regions of state space where observational noise links regimes with qualitatively different dynamics. The synchronization approach is used to calculate covariance inflation factors from parameters describing the bimodality of a one-dimensional system. The factors agree in overall magnitude with those used in operational practice on an ad hoc basis. The calculation is robust against the introduction of stochastic model error arising from unresolved scales.

  7. At first glance, transparency enhances assimilation

    OpenAIRE

    2008-01-01

    We investigated the role of transparency, perceptual grouping, and presentation time on perceived lightness. Both transparency and perceptual grouping have been found to result in assimilation effects, but only for ambiguous stimulus displays and with specific attentional instructions. By varying the presentation times of displays with two partly overlapping transparent E-shaped objects, we measured assimilation in unambiguous stimulus displays and without specific attentional instructions. T...

  8. Wage and Occupational Assimilation by Skill Level

    OpenAIRE

    Alcobendas, Miguel Angel; Rodríguez-Planas, Núria; Vegas, Raquel

    2012-01-01

    While much of the literature on immigrants' assimilation has focused on countries with a large tradition of receiving immigrants and with flexible labor markets, very little is known on how immigrants adjust to other types of host economies. With its severe dual labor market, and an unprecedented immigration boom, Spain presents a quite unique experience to analyze immigrations' assimilation process. Using alternative datasets and methodologies, this paper provides evidence of a differential ...

  9. Data Assimilation: Making Sense of Earth Observation

    Directory of Open Access Journals (Sweden)

    William Albert Lahoz

    2014-05-01

    Full Text Available Climate change, air quality and environmental degradation are important societal challenges for the 21st Century. These challenges require an intelligent response from society, which in turn requires access to information about the Earth System. This information comes from observations and prior knowledge, the latter typically embodied in a model describing relationships between variables of the Earth System. Data assimilation provides an objective methodology to combine observational and model information to provide an estimate of the most likely state and its uncertainty for the whole Earth System. This approach adds value to the observations – by filling in the spatio-temporal gaps in observations; and to the model – by constraining it with the observations. In this review paper we motivate data assimilation as a methodology to fill in the gaps in observational information; illustrate the data assimilation approach with examples that span a broad range of features of the Earth System (atmosphere, including chemistry; ocean; land surface; and discuss the outlook for data assimilation, including the novel application of data assimilation ideas to observational information obtained using Citizen Science. Ultimately, a strong motivation of data assimilation is the many benefits it provides to users. These include: providing the initial state for weather and air quality forecasts; providing analyses and reanalyses for studying the Earth System; evaluating observations, instruments and models; assessing the relative value of elements of the Global Observing System (GOS; and assessing the added value of future additions to the GOS.

  10. Response to diazepam in children with malaria-induced seizures.

    Science.gov (United States)

    Ikumi, M L; Muchohi, S N; Ohuma, E O; Kokwaro, G O; Newton, C R J C

    2008-12-01

    Malaria infection reduces the binding capacity of benzodiazepine receptors in mice. We studied the efficacy of diazepam terminating seizures in children with falciparum malaria. Diazepam stopped seizures in fewer patients with malaria parasitaemia (chi(2)=3.93, P=0.047) and those with clinical diagnosis of malaria (chi(2)=9.84, P=0.002) compared to those without. However malaria was not identified as an independent risk factor for diazepam's failure to stop seizures in children.

  11. Noradrenergic mechanism in the regulation of seizures in GEPR.

    Institute of Scientific and Technical Information of China (English)

    Kwang-HoKo; Dong-OokSeo; Jae-RyunRyu; Chan-YoungShin

    2004-01-01

    Genetically epilepsy prone rat (GEPR) is a model of generalized tonic/clonic epilepsy and a useful tool in the understanding of basic mechanisms of human epilepsy. GEPR is susceptible to audiogenic seizure, hyperthermia induced seizure,and has lower threshold for electrical and chemical stimuli. Several strains of GEPR, from GEPR-3 to GEPR-9, are available depending on the degree of the intensity of audiogenic seizure.

  12. Interleukin-1ß, seizures and neuronal cell death

    OpenAIRE

    Medel-Matus, Jesús S.; Postgrado en Neuroetología, Universidad Veracruzana. Xalapa, México. Centro de Investigaciones Cerebrales, Universidad Veracruzana. Xalapa, México. Químico clínico maestro en Neuroetología.; Cortijo-Palacios, Libia X.; Postgrado en Neuroetología, Universidad Veracruzana. Xalapa, México. química clínica.; Álvarez-Croda, Dulce M.; Postgrado en Neuroetología, Universidad Veracruzana. Xalapa, México. Centro de Investigaciones Cerebrales, Universidad Veracruzana. Xalapa, México. química farmacéutica bióloga.; Martínez-Quiroz, Joel; Facultad de Química Farmacéutica Biológica, Universidad Veracruzana. Xalapa, México. químico farmacéutico biólogo maestro en Ciencias Químico-Biológicas.; López-Meraz, María L.; Centro de Investigaciones Cerebrales, Universidad Veracruzana. Xalapa, México. Facultad de Medicina, Universidad Veracruzana. Xalapa, México. química farmacéutica bióloga doctora en Neurofarmacología y Terapéutica Experimental.

    2014-01-01

    Epilepsy is a neurological disorder affecting almost 1% of the world population. Experimental human and animal studies suggest that inflammation mediators, like cytokines, participate in the physiopathology of epilepsy. Interleukin-1beta (IL-1β) could influence susceptibility for seizures, as well as neuronal death caused by seizures, although some findings are contradictory. This document reviews the current knowledge establishing a connection between IL-1β, seizures and neuronal death. L...

  13. Forecasting seizures in dogs with naturally occurring epilepsy.

    Science.gov (United States)

    Howbert, J Jeffry; Patterson, Edward E; Stead, S Matt; Brinkmann, Ben; Vasoli, Vincent; Crepeau, Daniel; Vite, Charles H; Sturges, Beverly; Ruedebusch, Vanessa; Mavoori, Jaideep; Leyde, Kent; Sheffield, W Douglas; Litt, Brian; Worrell, Gregory A

    2014-01-01

    Seizure forecasting has the potential to create new therapeutic strategies for epilepsy, such as providing patient warnings and delivering preemptive therapy. Progress on seizure forecasting, however, has been hindered by lack of sufficient data to rigorously evaluate the hypothesis that seizures are preceded by physiological changes, and are not simply random events. We investigated seizure forecasting in three dogs with naturally occurring focal epilepsy implanted with a device recording continuous intracranial EEG (iEEG). The iEEG spectral power in six frequency bands: delta (0.1-4 Hz), theta (4-8 Hz), alpha (8-12 Hz), beta (12-30 Hz), low-gamma (30-70 Hz), and high-gamma (70-180 Hz), were used as features. Logistic regression classifiers were trained to discriminate labeled pre-ictal and inter-ictal data segments using combinations of the band spectral power features. Performance was assessed on separate test data sets via 10-fold cross-validation. A total of 125 spontaneous seizures were detected in continuous iEEG recordings spanning 6.5 to 15 months from 3 dogs. When considering all seizures, the seizure forecasting algorithm performed significantly better than a Poisson-model chance predictor constrained to have the same time in warning for all 3 dogs over a range of total warning times. Seizure clusters were observed in all 3 dogs, and when the effect of seizure clusters was decreased by considering the subset of seizures separated by at least 4 hours, the forecasting performance remained better than chance for a subset of algorithm parameters. These results demonstrate that seizures in canine epilepsy are not randomly occurring events, and highlight the feasibility of long-term seizure forecasting using iEEG monitoring.

  14. Surface acoustic wave probe implant for predicting epileptic seizures

    Science.gov (United States)

    Gopalsami, Nachappa [Naperville, IL; Kulikov, Stanislav [Sarov, RU; Osorio, Ivan [Leawood, KS; Raptis, Apostolos C [Downers Grove, IL

    2012-04-24

    A system and method for predicting and avoiding a seizure in a patient. The system and method includes use of an implanted surface acoustic wave probe and coupled RF antenna to monitor temperature of the patient's brain, critical changes in the temperature characteristic of a precursor to the seizure. The system can activate an implanted cooling unit which can avoid or minimize a seizure in the patient.

  15. 78 FR 17917 - Medical Waivers for Merchant Mariner Credential Applicants With a History of Seizure Disorders

    Science.gov (United States)

    2013-03-25

    ... type of seizure disorder) may be granted conditional certification to drive, provided that the... a lower likelihood of seizure recurrence than individuals who have been apparently seizure-free and... seizure among individuals on AEDs who are apparently seizure-free? (4) What is the likelihood of...

  16. The Global Structure of UTLS Ozone in GEOS-5: A Multi-Year Assimilation of EOS Aura Data

    Science.gov (United States)

    Wargan, Krzysztof; Pawson, Steven; Olsen, Mark A.; Witte, Jacquelyn C.; Douglass, Anne R.; Ziemke, Jerald R.; Strahan, Susan E.; Nielsen, J. Eric

    2015-01-01

    Eight years of ozone measurements retrieved from the Ozone Monitoring Instrument (OMI) and the Microwave Limb Sounder, both on the EOS Aura satellite, have been assimilated into the Goddard Earth Observing System version 5 (GEOS-5) data assimilation system. This study thoroughly evaluates this assimilated product, highlighting its potential for science. The impact of observations on the GEOS-5 system is explored by examining the spatial distribution of the observation-minus-forecast statistics. Independent data are used for product validation. The correlation coefficient of the lower-stratospheric ozone column with ozonesondes is 0.99 and the bias is 0.5%, indicating the success of the assimilation in reproducing the ozone variability in that layer. The upper-tropospheric assimilated ozone column is about 10% lower than the ozonesonde column but the correlation is still high (0.87). The assimilation is shown to realistically capture the sharp cross-tropopause gradient in ozone mixing ratio. Occurrence of transport-driven low ozone laminae in the assimilation system is similar to that obtained from the High Resolution Dynamics Limb Sounder (HIRDLS) above the 400 K potential temperature surface but the assimilation produces fewer laminae than seen by HIRDLS below that surface. Although the assimilation produces 5 - 8 fewer occurrences per day (up to approximately 20%) during the three years of HIRDLS data, the interannual variability is captured correctly. This data-driven assimilated product is complementary to ozone fields generated from chemistry and transport models. Applications include study of the radiative forcing by ozone and tracer transport near the tropopause.

  17. Neuro-inflammation, blood-brain barrier, seizures and autism

    Directory of Open Access Journals (Sweden)

    Theoharides Theoharis C

    2011-11-01

    Full Text Available Abstract Many children with Autism Spectrum Diseases (ASD present with seizure activity, but the pathogenesis is not understood. Recent evidence indicates that neuro-inflammation could contribute to seizures. We hypothesize that brain mast cell activation due to allergic, environmental and/or stress triggers could lead to focal disruption of the blood-brain barrier and neuro-inflammation, thus contributing to the development of seizures. Treating neuro-inflammation may be useful when anti-seizure medications are ineffective.

  18. [Role of central histamine in amygdaloid kindled seizures].

    Science.gov (United States)

    Kamei, C; Okuma, C

    2001-05-01

    The role of central histamine in amygdaloid kindled seizures in rats was studied. Histamine content in the amygdala was significantly decreased after development of amygdaloid kindling. Intracerebroventricular (i.c.v.) injection of histamine resulted in inhibition of amygdaloid kindled seizures. The H1-agonists 2-methylhistamine and 2-thiazolylethylamine also inhibited amygdaloid kindled seizures. In addition, intraperitoneal (i.p.) injection of histidine and metoprine inhibited amygdaloid kindled seizures at doses that caused increases in histamine contents of the brain. H1-antagonists (diphenhydramine and chlorpheniramine) attenuated histamine- or histidine-induced inhibition of amygdaloid kindled seizures. Both i.c.v. and i.p. injections of H3-antagonists (thioperamide, AQ0145 and clobenpropit) resulted in a dose-related inhibition of amygdaloid kindled seizures. The effects of thioperamide and AQ0145 were inhibited by an H3-agonist (R)-alpha-methylhistamine and H1-antagonists. On the other hand, H2-antagonists showed no antagonistic effect. GABAmimetic drugs, diazepam, sodium valproate and muscimol potentiated the effect of clobenpropit. Bicuculline caused significant antagonism of the inhibition of amygdaloid kindled seizures induced by clobenpropit. These findings suggested that a histaminergic mechanism plays an important role in suppressing amygdaloid kindled seizures through histamine H1-receptors. In addition, an inhibition of amygdaloid kindled seizures induced by histamine is closely related with the action of GABA.

  19. The neural correlates of altered consciousness during epileptic seizures.

    Science.gov (United States)

    Cavanna, Andrea E; Bagshaw, Andrew P; McCorry, Dougall

    2009-06-01

    Epileptic seizures are characterized by a multifaceted spectrum of alterations in the general level of awareness and/or the subjective contents of consciousness. Complete loss of consciousness occurs when epileptic activity involves both cortical and subcortical structures, as in generalized seizures. On the other hand, simple partial seizures can spare both the level and contents of consciousness. Finally, complex partial seizures associated with medial temporal lobe discharges can selectively impair the patient's subjective experiences with variable degrees of responsiveness. The differences in ictal semiology between patients with epilepsy offer unique avenues for understanding the relationship between pathological brain function and altered conscious states.

  20. Brain mechanisms of altered conscious states during epileptic seizures.

    Science.gov (United States)

    Cavanna, Andrea Eugenio; Monaco, Francesco

    2009-05-01

    Impaired consciousness has long been considered the hallmark of epileptic seizures. Both generalized seizures and complex partial seizures are characterized by a multifaceted spectrum of altered conscious states, in terms of the general level of awareness and the subjective contents of consciousness. Complete loss of consciousness occurs when epileptic activity involves both cortical and subcortical structures, as in tonic-clonic seizures and absence seizures. Medial temporal lobe discharges can selectively impair experience in complex partial seizures (with affected responsiveness) and certain simple partial seizures (with unaffected responsiveness). Electrical stimulation of temporal lobe structures has been shown to evoke similar subjective experiences. Findings from neurophysiological and brain-imaging studies in epilepsy have now demonstrated that involvement of the bilateral thalamus and upper brainstem leads to selective impairment of frontoparietal association cortices and midline 'default mode' networks, which results in ictal loss of consciousness. The spread of epileptic discharges from the medial temporal lobe to the same subcortical structures can ultimately cause impairment in the level of consciousness in the late ictal and immediate postictal phase of complex partial seizures. This paper reviews novel insights into the brain mechanisms that underlie alterations of consciousness during epileptic seizures and the implications for clinical practice in terms of diagnosis and management.

  1. Modulation of pilocarpine-induced seizures by cannabinoid receptor 1.

    Directory of Open Access Journals (Sweden)

    Rebecca L Kow

    Full Text Available Administration of the muscarinic agonist pilocarpine is commonly used to induce seizures in rodents for the study of epilepsy. Activation of muscarinic receptors has been previously shown to increase the production of endocannabinoids in the brain. Endocannabinoids act at the cannabinoid CB1 receptors to reduce neurotransmitter release and the severity of seizures in several models of epilepsy. In this study, we determined the effect of CB1 receptor activity on the induction in mice of seizures by pilocarpine. We found that decreased activation of the CB1 receptor, either through genetic deletion of the receptor or treatment with a CB1 antagonist, increased pilocarpine seizure severity without modifying seizure-induced cell proliferation and cell death. These results indicate that endocannabinoids act at the CB1 receptor to modulate the severity of pilocarpine-induced seizures. Administration of a CB1 agonist produced characteristic CB1-dependent behavioral responses, but did not affect pilocarpine seizure severity. A possible explanation for the lack of effect of CB1 agonist administration on pilocarpine seizures, despite the effects of CB1 antagonist administration and CB1 gene deletion, is that muscarinic receptor-stimulated endocannabinoid production is acting maximally at CB1 receptors to modulate sensitivity to pilocarpine seizures.

  2. Treatment Outcome Of Seizures Associated With Intracranial Cavernous Angiomas

    Directory of Open Access Journals (Sweden)

    Nievera Conrad C

    1999-01-01

    Full Text Available Seizures are among the typical presentations of intracranial cavernous angiomas (ICA. Twenty-one patients (age range: 2 to 53 years treated for seizures associated with ICA between 1983 and 1997 were restrospectively studied to evaluate their outcome following medical or surgical intervention. The mean interval between seizure onset and initial presentation at our institution was 7.6 years. Seizures were simple partial in 3 patients, complex partial in 15 and secondarily generalized tonic-clonic in 13. The commonest site of the lesion was the temporal lobe (52%. Multiple angiomas were observed in 5 (24% patients. Seven (32% patients were medically-managed with antiepileptic therapy and 14 (68% underwent either lesionectomy with resection of the epileptogenic zone (9 patients or temporal lobectomy (5 patients. Mean follow-up time was 4 years (range: 3 months to 14 years. Of the medically-managed patients, 3 (43% remained seizure-free whereas 4 (57% continued to have seizures with an average frequency of one per day. Of the surgically-managed patients, 12 (86% became seizure-free and 2 (14% had no more than two seizures per year. Surgery appears to be extremely effective in the management of seizures associated with ICA and should receive a strong and early consideration in patients who fail medical therapy.

  3. Automatic multi-modal intelligent seizure acquisition (MISA) system for detection of motor seizures from electromyographic data and motion data

    DEFF Research Database (Denmark)

    Conradsen, Isa; Beniczky, Sándor; Wolf, Peter

    2012-01-01

    The objective is to develop a non-invasive automatic method for detection of epileptic seizures with motor manifestations. Ten healthy subjects who simulated seizures and one patient participated in the study. Surface electromyography (sEMG) and motion sensor features were extracted as energy...... of the seizure from the patient showed that the simulated seizures were visually similar to the epileptic one. The multi-modal intelligent seizure acquisition (MISA) system showed high sensitivity, short detection latency and low false detection rate. The results showed superiority of the multi- modal detection...... system compared to the uni-modal one. The presented system has a promising potential for seizure detection based on multi-modal data....

  4. Benign focal epilepsy of childhood with centrotemporal spikes (BECTS: clinical characteristics of seizures according to age at first seizure

    Directory of Open Access Journals (Sweden)

    Miziara Carmen Silvia M.G.

    2002-01-01

    Full Text Available BECTS is characterized by the presence of simple partial motor seizures in the face and/or oropharynx, with or without sensory symptoms and often with secondary generalization. These seizures tend to occur more often during sleep or drowsiness. According to some authors, generalized seizures prevail over other types particularly among children aged five or less. The purpose of this study is to determine the characteristics of the first epileptic episode among children with BECTS, grouped by age as of their first epileptic seizure, as well as to analyze how such seizures change over the course of clinical evolution. A total of 61 children were examined, 16 of whom below the age of 5 and 45 above. With regard to the first and recurrent epileptic episodes, our final assessment showed that partial seizures occurred more frequently than generalized tonic-clonic seizures in both groups. Although no conclusive relation could be established between the type of partial seizure (i.e. simple versus complex and the children's age as of their first epileptic episode, it was possible to correlate the type of epileptic seizure with their clinical evolution, in which case simple partial seizures proved to be more frequent than complex partial seizures. It should be noted that the number of children under the age of five was relatively small, which evinces the need for further studies. It should also be borne in mind that the reported frequency of generalized seizures in these children's first epileptic episode may be due to their parents' lack of attention and familiarity with this pathology and their attendant difficulty in characterizing its clinical symptoms.

  5. Brugada syndrome masquerading as febrile seizures.

    Science.gov (United States)

    Skinner, Jonathan Robert; Chung, Seo-Kyung; Nel, Carey-Anne; Shelling, Andrew Neil; Crawford, Jackie Robyn; McKenzie, Neil; Pinnock, Ralph; French, John Kerswell; Rees, Mark Ian

    2007-05-01

    Fever can precipitate ventricular tachycardia in adults with Brugada syndrome, but such a link has not been reported in children. A 21-month-old white girl presented repeatedly with decreased conscious level and seizures during fever. During a typical episode, rapid ventricular tachycardia was documented. The resting 12-lead electrocardiogram revealed a Brugada electrocardiogram signature. Resting electrocardiograms of the asymptomatic brother and mother were normal, but fever in the mother and pharmacologic stress with ajmaline in the brother revealed Brugada electrocardiogram features. Genetic testing revealed an SCN5A mutation in the affected family members.

  6. Pediatric seizure disorders in dogs and cats.

    Science.gov (United States)

    Lavely, James A

    2014-03-01

    Seizure disorders in young animals pose different considerations as to cause and therapeutic decisions compared with adult animals. Infectious diseases of the nervous system are more likely in puppies and kittens compared with adults. The diagnosis of canine distemper is often based on clinical signs. Idiopathic epilepsy typically occurs in dogs between 1 and 5 years of age; however, inflammatory brain diseases such as necrotizing encephalitis and granulomatous meningoencephalomyelitis also commonly occur in young to middle-aged small-breed dogs. The choice of which anticonvulsant to administer for maintenance therapy is tailored to each individual patient.

  7. Intractable Seizures and Rehabilitation in Ciguatera Poisoning.

    Science.gov (United States)

    Derian, Armen; Khurana, Seema; Rothenberg, Joshua; Plumlee, Charles

    2016-08-31

    Ciguatera fish poisoning is the most frequently reported seafood toxin illness associated with the ingestion of contaminated tropical fish. Diagnosis relies on a history of recent tropical fish ingestion and subsequent development of gastrointestinal, cardiovascular, and neurological symptoms. Ciguatera poisoning usually has a self-limited time course, and its management involves symptomatic control and supportive care. This case report presents an uncommon case of ciguatera poisoning with prolonged intractable seizures refractory to standard antiseizure medications. The patient also had significant functional decline that responded to rigorous inpatient rehabilitation not previously described in literature.

  8. Children with New Onset Seizures: A Prospective Study of Parent Variables, Child Behavior Problems, and Seizure Occurrence

    Science.gov (United States)

    Austin, Joan K.; Haber, Linda C.; Dunn, David W.; Shore, Cheryl P.; Johnson, Cynthia S.; Perkins, Susan M.

    2015-01-01

    Objective Parent variables (stigma, mood, unmet needs for information and support, and worry) are associated with behavioral difficulties in children with seizures, however, it is not known how this relationship is influenced by additional seizures. This study followed children (ages 4 – 14 years) and their parents over a 24-month period (with data collected at baseline, 6, 12, and 24 months) and investigated the effect of an additional seizure on the relationship between parenting variables and child behavior difficulties. Methods The sample was parents of 196 children (104 girls and 92 boys) with a first seizure within the past 6 weeks. Child mean age at baseline was 8 years, 3 months (SD 3 years). Data were analyzed using t-tests, chi-square tests, and repeated measures analyses of covariance. Results Relationships between parent variables, additional seizures, and child behavior problems were consistent across time. Several associations between parent variables and child behavior problems were stronger in the additional seizure group than in the no additional seizures group. Conclusions Findings suggest that interventions that assist families to respond constructively to the reactions of others regarding their child's seizure condition and to address their needs for information and support could help families of children with continuing seizures to have an improved quality of life. PMID:26520879

  9. Seizure susceptibility of neuropeptide-Y null mutant mice in amygdala kindling and chemical-induced seizure models.

    Science.gov (United States)

    Shannon, Harlan E; Yang, Lijuan

    2004-01-01

    Neuropeptide Y (NPY) administered exogenously is anticonvulsant, and, NPY null mutant mice are more susceptible to kainate-induced seizures. In order to better understand the potential role of NPY in epileptogenesis, the present studies investigated the development of amygdala kindling, post-kindling seizure thresholds, and anticonvulsant effects of carbamazepine and levetiracetam in 129S6/SvEv NPY(+/+) and NPY(-/-) mice. In addition, susceptibility to pilocarpine- and kainate-induced seizures was compared in NPY(+/+) and (-/-) mice. The rate of amygdala kindling development did not differ in the NPY(-/-) and NPY(+/+) mice either when kindling stimuli were presented once daily for at least 20 days, or, 12 times daily for 2 days. However, during kindling development, the NPY(-/-) mice had higher seizure severity scores and longer afterdischarge durations than the NPY(+/+) mice. Post-kindling, the NPY(-/-) mice had markedly lower afterdischarge thresholds and longer afterdischarge durations than NPY (+/+) mice. Carbamazepine and levetiracetam increased the seizure thresholds of both NPY (-/-) and (+/+) mice. In addition, NPY (-/-) mice had lower thresholds for both kainate- and pilocarpine-induced seizures. The present results in amygdala kindling and chemical seizure models suggest that NPY may play a more prominent role in determining seizure thresholds and severity of seizures than in events leading to epileptogenesis. In addition, a lack of NPY does not appear to confer drug-resistance in that carbamazepine and levetiracetam were anticonvulsant in both wild type (WT) and NPY null mutant mice.

  10. The social context of assimilation: testing implications of segmented assimilation theory.

    Science.gov (United States)

    Xie, Yu; Greenman, Emily

    2011-05-01

    Segmented assimilation theory has been a popular explanation for the diverse experiences of assimilation among new waves of immigrants and their children. While the theory has been interpreted in many different ways, we emphasize its implications for the important role of social context: both processes and consequences of assimilation should depend on the local social context in which immigrants are embedded. We derive empirically falsifiable hypotheses about the interaction effects between social context and assimilation on immigrant children's well-being. We then test the hypotheses using data from the National Longitudinal Study of Adolescent Health. Our empirical analyses yield two main findings. First, for immigrant adolescents living in non-poverty neighborhoods, we find assimilation to be positively associated with educational achievement and psychological well-being but also positively associated with at-risk behavior. Second, there is little empirical evidence supporting our hypotheses derived from segmented assimilation theory. We interpret these results to mean that future research would be more fruitful focusing on differential processes of assimilation rather than differential consequences of assimilation.

  11. Assimilation of gridded GRACE terrestrial water storage estimates in the North American Land Data Assimilation System

    Science.gov (United States)

    The objective of the North American Land Data Assimilation System (NLDAS) is to provide best-available estimates of near surface meteorological conditions and soil hydrological status for the Continental United States. The first two phases of NLDAS, however, have not included the assimilation of rem...

  12. IS ASSIMILATION THEORY DEAD? THE EFFECT OF ASSIMILATION ON ADOLESCENT WELL-BEING.

    Science.gov (United States)

    Greenman, Emily; Xie, Yu

    2008-03-01

    The relationship between assimilation and the well-being of immigrant children has been the focus of debate in the recent sociological literature. Much of this work has questioned whether classical theories of immigrant adaptation, which assumed assimilation to be an integral part of the process of upward mobility for immigrants, are still applicable to today's immigrant children. This study reevaluates the applicability of classical assimilation theory with a comprehensive empirical assessment of the relationship between assimilation and the well-being of Hispanic and Asian immigrant adolescents. Using Add Health data, we examine the effect of different aspects of assimilation on educational achievement, psychological well-being, and at-risk behaviors. We find that the effect of assimilation varies greatly depending on the ethnic group and outcome under consideration, but that it is generally related to both greater academic achievement and more at-risk behavior. We conclude that assimilation theory is still relevant, but suggest an interpretation that emphasizes a process of decreasing differences between groups rather than either detrimental or beneficial effects of assimilation.

  13. Efficient Methods to Assimilate Satellite Retrievals Based on Information Content. Part 2; Suboptimal Retrieval Assimilation

    Science.gov (United States)

    Joiner, J.; Dee, D. P.

    1998-01-01

    One of the outstanding problems in data assimilation has been and continues to be how best to utilize satellite data while balancing the tradeoff between accuracy and computational cost. A number of weather prediction centers have recently achieved remarkable success in improving their forecast skill by changing the method by which satellite data are assimilated into the forecast model from the traditional approach of assimilating retrievals to the direct assimilation of radiances in a variational framework. The operational implementation of such a substantial change in methodology involves a great number of technical details, e.g., pertaining to quality control procedures, systematic error correction techniques, and tuning of the statistical parameters in the analysis algorithm. Although there are clear theoretical advantages to the direct radiance assimilation approach, it is not obvious at all to what extent the improvements that have been obtained so far can be attributed to the change in methodology, or to various technical aspects of the implementation. The issue is of interest because retrieval assimilation retains many practical and logistical advantages which may become even more significant in the near future when increasingly high-volume data sources become available. The central question we address here is: how much improvement can we expect from assimilating radiances rather than retrievals, all other things being equal? We compare the two approaches in a simplified one-dimensional theoretical framework, in which problems related to quality control and systematic error correction are conveniently absent. By assuming a perfect radiative transfer model and perfect knowledge of radiance and background error covariances, we are able to formulate a nonlinear local error analysis for each assimilation method. Direct radiance assimilation is optimal in this idealized context, while the traditional method of assimilating retrievals is suboptimal because it

  14. Pulmonary edema following generalized tonic clonic seizures is directly associated with seizure duration

    Science.gov (United States)

    Kennedy, Jeffrey D.; Hardin, Kimberly A.; Parikh, Palak; Li, Chin-Shang; Seyal, Masud

    2015-01-01

    Purpose Postictal pulmonary edema (PPE) is almost invariably present in human and animal cases of sudden unexpected death in epilepsy (SUDEP) coming to autopsy. PPE may be a contributing factor in SUDEP. The incidence of postictal PPE is unknown. We retrospectively investigated PPE following generalized tonic clonic seizures (GTCS) in the epilepsy monitoring unit. Methods Chest X-Rays (CXR) following each GTCS were obtained in 24 consecutive patients. Relationship of CXR abnormality to seizure duration, ictal/postictal oxygen desaturation (SpO2), apnea and presence of postictal generalized EEG suppression (PGES) was investigated using logistic regression. Results Eleven of 24 patients had CXR abnormalities following a GTCS. In these 11 patients, 22 CXR were obtained and abnormalities were present in 15 CXR. Abnormalities included PPE in 7 patients, of which 2 also had focal infiltrates. In 4 patients focal infiltrates were present without PPE. There was no significant difference in mean time to CXR (225 min) following GTCS in the abnormal CXR group versus the normal group of patients (196 min). Mean preceding seizure duration was longer (p=0.002) in GTCS with abnormal CXR (259.7 sec) versus GTCS with normal CXR (101.2 sec). Odds-ratio for CXR abnormality was 20.46 (p=0.006) with seizure duration greater than 100 sec versus less than 100 sec. On multivariable analysis, only the seizure duration was a significant predictor of CXR abnormality (p=0.015). Conclusions Radiographic abnormalities are not uncommon following GTCS. The presence of CXR abnormality is significantly associated with the duration of the preceding GTCS. Severe, untreated PPE may be relevant to the pathophysiology of SUDEP. PMID:25844030

  15. Sleep seizures versus wake seizures: A comparative hospital study on clinical, electroencephalographic and radiological profile

    Directory of Open Access Journals (Sweden)

    Goel Deepak

    2008-01-01

    Full Text Available Background: Epileptic seizures, predominantly or exclusively during sleep had been the focus of attention for many electroencephalographers. Though few epileptic syndromes are associated with sleep seizures (SS its frequencies in Indian patients is still unknown. Aim: To find out the patterns of epilepsies in patients having SS and compare them with patients having wake seizures (WS. Setting and Design : Open label hospital based study. Materials and Methods: One hundred and forty-four (13% patients having predominantly SS were compared with 976 (87% patients of WS by various clinical, electrophysiological and radiological factors. Statistical Analysis: Chi square test and student T test, using software SPSS (version 10, 1999 was applied to compare various parameters. Relative risk was calculated by 2 x 2 contingency table. Results: The seizure semiology was better defined in patients with WS and GTCS was more common in SS ( P = 0.001. Wake-electroencephalogram (EEG was abnormal in significantly ( P = 0.001 higher number of patients with WS. Symptomatic etiologies were found in more than half patients. Left lobe involvement was more common in patients having SS ( P = 0.000. After symptomatic, idiopathic generalized and frontal lobe epilepsy were most frequent with SS. Undetermined epilepsy was found in 37 (25.7% patients with SS. Conclusion: Epilepsies associated with SS were less frequent and had symptomatic cause in most cases. Left hemispherical and frontal lobe lesion were more commonly associated with SS. Frontal lobe and idiopathic generalized epilepsy was most frequent in patients of SS. Sleep EEG should always be done in patients with sleep seizures.

  16. SERUM CHEMISTRY ABNORMALITIES IN CHILDREN WITH UNPROVOKED SEIZURES

    Directory of Open Access Journals (Sweden)

    J. Akhondian MD

    2009-01-01

    Full Text Available ObjectiveMost children brought to the emergency department (ED for evaluation of seizures undergo an extensive laboratory workup. Since results are usually negative, the value of such routine laboratory workups has been questioned. A group of children with unprovoked seizures was prospectively studied to determine the diagnostic values of routine serum chemistries and to identify risk factors predictive of abnormal findings.Materials & MethodsAll patients evaluated at the ED of the Ghaem hospital during a consecutive 12 months period between Jan 2004 through Jan 2005 were studied. We collected data for patient's demographics, details of the history of present illness (including vomiting, diarrhea, apnea, medication use, past history of seizures, family history of seizures, metabolic disorders or other chronic medical illnesses, neonatal history and neurological examination as well as nutritional status, type and time of seizure. The role of abnormal serum chemistries as a seizure trigger factor was assessed in patients with a history of seizure.ResultsA total of 210 patients (mean age 19.2 months with unprovoked seizures were evaluated. Twenty- three serum abnormalities were noted in the patients (12 cases of hyponatremia, 7 of hypoglycemia, 4 of hypokalemia, 4 of uremia. The incidence of abnormal serum biochemical values was higher in patients with a first seizure, younger patients, and those with gastrointestinal symptoms.ConclusionAccording to the present study, one can conclude that in children younger than 2 years and having no structural CNS abnormality, electrolyte and glucose screening is recommended only for a first unprovoked seizure, when gastrointestinal symptoms or symptoms suggesting electrolyte disturbances are present.Keywords:Unprovoked, Seizure, Biochemistry, Children

  17. GENERALIZED VARIATIONAL DATA ASSIMILATION METHOD AND NUMERICAL EXPERIMENT FOR NON-DIFFERENTIAL SYSTEM

    Institute of Scientific and Technical Information of China (English)

    黄思训; 杜华栋; 韩威

    2004-01-01

    The generalized variational data assimilation for non-differential dynamical systems is studied.There is no tangent linear model for non-differential systems and thus the general adjoint model can not be derived in the traditional way.The weak form of the original system was introduced, and then the generalized adjoint model was derived. The generalized variational data assimilation methods were developed for non-differential low dimensional system and non-differential high dimensional system with global and local observations. Furthermore, ideas in inverse problems are introduced to 4DVAR (Four-dimensional variational) of non-differential partial differential system with local observations.

  18. Seizure prediction using polynomial SVM classification.

    Science.gov (United States)

    Zisheng Zhang; Parhi, Keshab K

    2015-08-01

    This paper presents a novel patient-specific algorithm for prediction of seizures in epileptic patients with low hardware complexity and low power consumption. In the proposed approach, we first compute the spectrogram of the input fragmented EEG signals from a few electrodes. Each fragmented data clip is ten minutes in duration. Band powers, relative spectral powers and ratios of spectral powers are extracted as features. The features are then subjected to electrode selection and feature selection using classification and regression tree. The baseline experiment uses all features from selected electrodes and these features are then subjected to a radial basis function kernel support vector machine (RBF-SVM) classifier. The proposed method further selects a small number features from the selected electrodes and train a polynomial support vector machine (SVM) classifier with degree of 2 on these features. Prediction performances are compared between the baseline experiment and the proposed method. The algorithm is tested using intra-cranial EEG (iEEG) from the American Epilepsy Society Seizure Prediction Challenge database. The baseline experiment using a large number of features and RBF-SVM achieves a 100% sensitivity and an average AUC of 0.9985, while the proposed algorithm using only a small number of features and polynomial SVM with degree of 2 can achieve a sensitivity of 100.0%, an average area under curve (AUC) of 0.9795. For both experiments, only 10% of the available training data are used for training.

  19. CHOLESTEROL ASSIMILATION BY COMMERCIAL YOGHURT STARTER CULTURES

    Directory of Open Access Journals (Sweden)

    Małgorzata Ziarno

    2007-03-01

    Full Text Available The ability to in vitro cholesterol level reduction in laboratory media has been shown for numerous strains of lactic acid bacteria, but not for all strains of lactic bacteria used in the dairy industry. The aim of this work was the determination of the ability of selected thermophilic lactic acid bacteria to cholesterol assimilation during 24 h culture in MRS broth. Commercial starter cultures showed various ability to cholesterol assimilation from laboratory medium. In case of starter cultures used for production of traditional yoghurt, consisting of Streptococcus salivarius subsp. thermophilus and Lactobacillus delbrueckii subsp. bulgaricus, the quantity of assimilated cholesterol did not exceed 27% of its initial contents (0.7 g in 1 dm3. Starter cultures used for bioyoghurt production, containing also probiotic strains (came from Lactobacillus acidophilus species or Bifidobacterium genus assimilated from almost 18% to over 38% of cholesterol. For one monoculture of Lb. acidophilus, cholesterol assimilation ability of 49-55% was observed, despite that the number of bacterial cells in this culture was not different from number of bacteria in other cultures.

  20. Chronic omega-3 supplementation in seizure-prone versus seizure-resistant rat strains: a cautionary tale.

    Science.gov (United States)

    Gilby, K L; Jans, J; McIntyre, D C

    2009-10-20

    Several studies have shown fatty acid supplementation to be efficacious in the treatment of attention deficit hyperactivity disorder/autism spectrum disorder (ADHD/ASD) and epilepsy. Interestingly, rats bred to be seizure-prone (Fast), unlike those bred for seizure-resistance (Slow), naturally exhibit behaviors and physiology reminiscent of ADHD/ASD in humans, suggesting a fundamental link between seizure disposition and these developmental disorders. To determine whether chronic omega-3 supplementation might ameliorate ADHD-like behaviors in the seizure-prone rat strain and/or alter natural predispositions for or against seizure in either strain, Fast and Slow weanlings were maintained on a control or omega-3-supplemented diet. As adults, rats were tested in paradigms known to elicit ADHD-like behaviors from Fast rats and then kindled from the amygdala to assess relative seizure disposition. While omega-3 supplementation did not significantly alter the relative hyperactivity, learning deficits or heightened seizure sensitivity naturally exhibited by Fast rats, it dramatically reduced their impulsivity to Slow-like levels. In contrast, typical behavioral patterns in Slow rats were largely unaffected by omega-3 supplementation yet their proclivity for seizure was greatly increased. This heightened vulnerability to seizure in Slow rats was paralleled by a drop in circulating plasma non-esterified fatty acids (NEFA) to match levels normally observed in Fast rats. These findings suggest a delicate balance between seizure predisposition and ADHD-like behaviors that can be influenced by omega-3 treatment. Further, a relationship between circulating NEFA levels and seizure susceptibility has surfaced that advocates caution when treating different genetic backgrounds with omega-3 fatty acids.

  1. Seizures and Epilepsy and Their Relationship to Autism Spectrum Disorders

    Science.gov (United States)

    Matson, Johnny L.; Neal, Daniene

    2009-01-01

    Autism spectrum disorders (ASD) are serious neurodevelopmental disorders which often co-occur with intellectual disabilities. A disorder which is strongly correlated with both of these disabilities are seizures and epilepsy. The purpose of this review was to provide an overview of available research on seizures and epilepsy in the ASD population…

  2. Identification of Srp9 as a febrile seizure susceptibility gene

    NARCIS (Netherlands)

    Hessel, Ellen V S; de Wit, Marina; Wolterink-Donselaar, Inge G; Karst, Henk; de Graaff, Esther; van Lith, Hein A; de Bruijn, Ewart; de Sonnaville, Sophietje; Verbeek, Nienke E; Lindhout, Dick; de Kovel, Carolien G F; Koeleman, Bobby P C; van Kempen, Marjan; Brilstra, Eva; Cuppen, Edwin; Loos, Maarten; Spijker, Sabine S; Kan, Anne A; Baars, Susanne E; van Rijen, Peter C; Gosselaar, Peter H; Groot Koerkamp, Marian J A; Holstege, Frank C P; van Duijn, Cornelia; Vergeer, Jeanette; Moll, Henriette A; Taubøll, Erik; Heuser, Kjell; Ramakers, Geert M J; Pasterkamp, R Jeroen; van Nieuwenhuizen, Onno; Hoogenraad, Casper C; Kas, Martien J H; de Graan, Pierre N E

    2014-01-01

    OBJECTIVE: Febrile seizures (FS) are the most common seizure type in young children. Complex FS are a risk factor for mesial temporal lobe epilepsy (mTLE). To identify new FS susceptibility genes we used a forward genetic strategy in mice and subsequently analyzed candidate genes in humans. METHODS:

  3. Histamine H1 antagonists and clinical characteristics of febrile seizures

    Directory of Open Access Journals (Sweden)

    Zolaly MA

    2012-03-01

    Full Text Available Mohammed A ZolalyDepartment of Pediatrics, College of Medicine, Taibah University, Al-Madinah Al-Munawarah, Kingdom of Saudi ArabiaBackground: The purpose of this study was to determine whether seizure susceptibility due to antihistamines is provoked in patients with febrile seizures.Methods: The current descriptive study was carried out from April 2009 to February 2011 in 250 infants and children who visited the Madinah Maternity and Children's Hospital as a result of febrile convulsions. They were divided into two groups according to administration of antihistamines at the onset of fever.Results: Detailed clinical manifestations were compared between patients with and without administration of antihistamines. The time from fever detection to seizure onset was significantly shorter in the antihistamine group than that in the nonantihistamine group, and the duration of seizures was significantly longer in the antihistamine group than in the nonantihistamine group. No significant difference was found in time from fever detection to seizure onset or seizure duration between patients who received a first-generation antihistamine and those who received a second-generation antihistamine.Conclusion: Due to their central nervous system effects, H1 antagonists should not be administered to patients with febrile seizures and epilepsy. Caution should be exercised regarding the use of histamine H1 antagonists in young infants, because these drugs could potentially disturb the anticonvulsive central histaminergic system.Keywords: antihistamine, nonantihistamine, histamine H1 antagonist, febrile seizures

  4. Responding to Seizures (A Cup of Health with CDC)

    Centers for Disease Control (CDC) Podcasts

    2015-11-26

    As traumatic as epilepsy can be for the person experiencing seizures, it can be just as troubling for witnesses who want to try and help. In this podcast, Rosemarie Kobau discusses the appropriate way to help someone who is experiencing a seizure.  Created: 11/26/2015 by MMWR.   Date Released: 11/26/2015.

  5. Temporal epileptic seizures and occupational exposure to solvents

    DEFF Research Database (Denmark)

    Jacobsen, M; Bælum, Jesper; Bonde, J P

    1994-01-01

    exposure to a mixture of organic solvents (mainly cyclohexanone, white spirit, and isopropanol). Epileptic seizures of temporal type were occurring in relation to solvent exposure. The seizures disappeared shortly after stopping exposure but returned just after a short term re-exposure to cyclohexanone...

  6. Nicotine Elicits Convulsive Seizures by Activating Amygdalar Neurons

    Science.gov (United States)

    Iha, Higor A.; Kunisawa, Naofumi; Shimizu, Saki; Tokudome, Kentaro; Mukai, Takahiro; Kinboshi, Masato; Ikeda, Akio; Ito, Hidefumi; Serikawa, Tadao; Ohno, Yukihiro

    2017-01-01

    Nicotinic acetylcholine (nACh) receptors are implicated in the pathogenesis of epileptic disorders; however, the mechanisms of nACh receptors in seizure generation remain unknown. Here, we performed behavioral and immunohistochemical studies in mice and rats to clarify the mechanisms underlying nicotine-induced seizures. Treatment of animals with nicotine (1–4 mg/kg, i.p.) produced motor excitement in a dose-dependent manner and elicited convulsive seizures at 3 and 4 mg/kg. The nicotine-induced seizures were abolished by a subtype non-selective nACh antagonist, mecamylamine (MEC). An α7 nACh antagonist, methyllycaconitine, also significantly inhibited nicotine-induced seizures whereas an α4β2 nACh antagonist, dihydro-β-erythroidine, affected only weakly. Topographical analysis of Fos protein expression, a biological marker of neural excitation, revealed that a convulsive dose (4 mg/kg) of nicotine region-specifically activated neurons in the piriform cortex, amygdala, medial habenula, paratenial thalamus, anterior hypothalamus and solitary nucleus among 48 brain regions examined, and this was also suppressed by MEC. In addition, electric lesioning of the amygdala, but not the piriform cortex, medial habenula and thalamus, specifically inhibited nicotine-induced seizures. Furthermore, microinjection of nicotine (100 and 300 μg/side) into the amygdala elicited convulsive seizures in a dose-related manner. The present results suggest that nicotine elicits convulsive seizures by activating amygdalar neurons mainly via α7 nACh receptors.

  7. 19 CFR 162.63 - Arrests and seizures.

    Science.gov (United States)

    2010-04-01

    ... 19 Customs Duties 2 2010-04-01 2010-04-01 false Arrests and seizures. 162.63 Section 162.63 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY (CONTINUED) INSPECTION, SEARCH, AND SEIZURE Controlled Substances, Narcotics, and Marihuana §...

  8. Neuropeptide FF receptors as novel targets for limbic seizure attenuation.

    Science.gov (United States)

    Portelli, Jeanelle; Meurs, Alfred; Bihel, Frederic; Hammoud, Hassan; Schmitt, Martine; De Kock, Joery; Utard, Valerie; Humbert, Jean-Paul; Bertin, Isabelle; Buffel, Ine; Coppens, Jessica; Tourwe, Dirk; Maes, Veronique; De Prins, An; Vanhaecke, Tamara; Massie, Ann; Balasubramaniam, Ambikaipakan; Boon, Paul; Bourguignon, Jean-Jacques; Simonin, Frederic; Smolders, Ilse

    2015-08-01

    Neuropeptide Y (NPY) is a well established anticonvulsant and first-in-class antiepileptic neuropeptide. In this study, the controversial role of NPY1 receptors in epilepsy was reassessed by testing two highly selective NPY1 receptor ligands and a mixed NPY1/NPFF receptor antagonist BIBP3226 in a rat model for limbic seizures. While BIBP3226 significantly attenuated the pilocarpine-induced seizures, neither of the highly selective NPY1 receptor ligands altered the seizure severity. Administration of the NPFF1/NPFF2 receptor antagonist RF9 also significantly attenuated limbic seizure activity. To further prove the involvement of NPFF receptors in these seizure-modulating effects, low and high affinity antagonists for the NPFF receptors were tested. We observed that the low affinity ligand failed to exhibit anticonvulsant properties while the two high affinity ligands significantly attenuated the seizures. Continuous NPFF1 receptor agonist administration also inhibited limbic seizures whereas bolus administration of the NPFF1 receptor agonist was without effect. This suggests that continuous agonist perfusion could result in NPFF1 receptor desensitization and mimic NPFF1 receptor antagonist administration. Our data unveil for the first time the involvement of the NPFF system in the management of limbic seizures.

  9. Increasing Epilepsy Awareness in Schools: A Seizure Smart Schools Project

    Science.gov (United States)

    Brook, Heather A.; Hiltz, Cynthia M.; Kopplin, Vicki L.; Lindeke, Linda L.

    2015-01-01

    A high prevalence of epilepsy diagnoses and seizure events among students was identified at a large Midwestern school district. In partnership with the Epilepsy Foundation of Minnesota (EFMN), a quality improvement project was conducted to provide education and resources to staff caring for school children with seizures. School nurses (N = 26)…

  10. Neonatal Seizures: new developments in monitoring and therapy

    NARCIS (Netherlands)

    van Rooij, L.G.M.

    2009-01-01

    Seizures are common in the neonatal period and represent a most distinctive signal of neurological disease. Seizures in newborns are associated with an increased risk of neurodevelopmental impairment, including cerebral palsy, mental retardation and epilepsy and mortality. Controversy still exists c

  11. Refractory seizures associated with an organic aciduria in a dog.

    Science.gov (United States)

    Platt, Simon; McGrotty, Yvonne L; Abramson, Carley J; Jakobs, Cornelis

    2007-01-01

    A 6-month-old, female Cavalier King Charles spaniel exhibited seizures that were difficult to control with standard anticonvulsants over a 12-month period. The diagnosis of an organic aciduria with excessive excretion of hexanoylglycine was determined when the dog was 20 months old. Recurrent and cluster seizures were eventually controlled with the addition of levetiracetam to potassium bromide and phenobarbital.

  12. Another Tool in the Fight against Epilepsy: Seizure Response Dogs

    Science.gov (United States)

    Hollingsworth, Jan Carter

    2007-01-01

    Epilepsy, a chronic neurological seizure disorder, affects 2.7 million Americans, half of them children, and worldwide, it is the most common brain disorder. While there is not a cure for epilepsy, the goal of treatment is to achieve the greatest freedom from seizures that can be attained with the minimal amount of side effects. These days…

  13. Responding to Seizures (A Minute of Health with CDC)

    Centers for Disease Control (CDC) Podcasts

    2015-11-26

    When helping someone with a seizure, it’s important to remain calm. This podcast discusses what to do if you witness someone having a seizure.  Created: 11/26/2015 by MMWR.   Date Released: 11/26/2015.

  14. Improving Sediment Transport Prediction by Assimilating Satellite Images in a Tidal Bay Model of Hong Kong

    Directory of Open Access Journals (Sweden)

    Peng Zhang

    2014-03-01

    Full Text Available Numerical models being one of the major tools for sediment dynamic studies in complex coastal waters are now benefitting from remote sensing images that are easily available for model inputs. The present study explored various methods of integrating remote sensing ocean color data into a numerical model to improve sediment transport prediction in a tide-dominated bay in Hong Kong, Deep Bay. Two sea surface sediment datasets delineated from satellite images from the Moderate Resolution Imaging Spectra-radiometer (MODIS were assimilated into a coastal ocean model of the bay for one tidal cycle. It was found that remote sensing sediment information enhanced the sediment transport model ability by validating the model results with in situ measurements. Model results showed that root mean square errors of forecast sediment both at the surface layer and the vertical layers from the model with satellite sediment assimilation are reduced by at least 36% over the model without assimilation.

  15. Clinically silent seizures in a neonate with tuberous sclerosis.

    Science.gov (United States)

    Ikeno, Mitsuru; Okumura, Akihisa; Abe, Shinpei; Igarashi, Ayuko; Hisata, Ken; Shoji, Hiromichi; Shimizu, Toshiaki

    2016-01-01

    Although seizures during infancy in patients with tuberous sclerosis complex are common, seizures in neonates are infrequent. Here, we report the clinical course and electroencephalography (EEG) findings of a neonate with tuberous sclerosis complex associated with clinically silent seizures. The patient was a girl in whom cardiac tumors were detected on fetal ultrasonography. Brain magnetic resonance imaging during the neonatal period showed subependymal and cortical tubers. Routine EEG indicated unexpected ictal changes with no noticeable clinical symptoms. Ictal EEG was associated with a subtle increase in heart rate and a brief increase in chin electromyogram. These changes were difficult to identify clinically. The patient later developed focal seizures and epileptic spasms and had severe psychomotor delay. The present case suggests the occurrence of clinically silent seizures before the appearance of epileptic spasms in infants with tuberous sclerosis, and that EEG is an option for neonates with a prenatal diagnosis.

  16. The piriform, perirhinal, and entorhinal cortex in seizure generation

    Directory of Open Access Journals (Sweden)

    Marta S Vismer

    2015-05-01

    Full Text Available Understanding neural network behavior is essential to shed light on epileptogenesis and seizure propagation. The interconnectivity and plasticity of the limbic and cortical regions of the mammalian brain provide the substrate for the hypersynchrony and hyperexcitability associated with epilepsy and seizure activity. Recurrent unprovoked seizures are the hallmark of epilepsy, and limbic epilepsy is the most common type of medically-intractable focal epilepsy in adolescents and adults that necessitates surgical evaluation. In this review, we describe the role and relationships among the piriform (PIRC, perirhinal (PRC, and entorhinal cortex (ERC in seizure-generation and epilepsy. The inherent function, anatomy, and histological composition of these cortical regions are discussed. In addition, the neurotransmitters, intrinsic and extrinsic connections, and the interaction of these regions are described. Furthermore, we provide evidence based on clinical research and animal models that suggest that these cortical regions may act as key seizure-trigger zones and, even, epileptogenesis.

  17. The piriform, perirhinal, and entorhinal cortex in seizure generation.

    Science.gov (United States)

    Vismer, Marta S; Forcelli, Patrick A; Skopin, Mark D; Gale, Karen; Koubeissi, Mohamad Z

    2015-01-01

    Understanding neural network behavior is essential to shed light on epileptogenesis and seizure propagation. The interconnectivity and plasticity of mammalian limbic and neocortical brain regions provide the substrate for the hypersynchrony and hyperexcitability associated with seizure activity. Recurrent unprovoked seizures are the hallmark of epilepsy, and limbic epilepsy is the most common type of medically-intractable focal epilepsy in adolescents and adults that necessitates surgical evaluation. In this review, we describe the role and relationships among the piriform (PIRC), perirhinal (PRC), and entorhinal cortex (ERC) in seizure-generation and epilepsy. The inherent function, anatomy, and histological composition of these cortical regions are discussed. In addition, the neurotransmitters, intrinsic and extrinsic connections, and the interaction of these regions are described. Furthermore, we provide evidence based on clinical research and animal models that suggest that these cortical regions may act as key seizure-trigger zones and, even, epileptogenesis.

  18. Seizure disorders: update of medical and dental considerations.

    Science.gov (United States)

    Stoopler, Eric T; Sollecito, Thomas P; Greenberg, Martin S

    2003-01-01

    Seizure disorders and epilepsy represent neurologic conditions that commonly are seen among patients requiring dental treatment. When dentists possess a working knowledge of seizures, in addition to an understanding of updated therapies for seizure management and oral complications associated with pharmacological therapy, they are able to treat patients with these disorders more effectively. Neurologic consultations and selecting an appropriate venue for treatment may need to be addressed prior to treatment, depending on the level of seizure control. Laboratory tests designed to evaluate medication levels, leukocyte counts, and clotting ability also may be required. Frequent recall visits may be necessary for seizure disorder patients who display adverse oral complications from medication, such as gingival hypertrophy, xerostomia, and oral yeast infections.

  19. Heavy rainfall prediction applying satellite-based cloud data assimilation over land

    Science.gov (United States)

    Seto, Rie; Koike, Toshio; Rasmy, Mohamed

    2016-08-01

    To optimize flood management, it is crucial to determine whether rain will fall within a river basin. This requires very fine precision in prediction of rainfall areas. Cloud data assimilation has great potential to improve the prediction of precipitation area because it can directly obtain information on locations of rain systems. Clouds can be observed globally by satellite-based microwave remote sensing. Microwave observation also includes information of latent heat and water vapor associated with cloud amount, which enables the assimilation of not only cloud itself but also the cloud-affected atmosphere. However, it is difficult to observe clouds over land using satellite microwave remote sensing, because their emissivity is much lower than that of the land surface. To overcome this challenge, we need appropriate representation of heterogeneous land emissivity. We developed a coupled atmosphere and land data assimilation system with the Weather Research and Forecasting Model (CALDAS-WRF), which can assimilate soil moisture, vertically integrated cloud water content over land, and heat and moisture within clouds simultaneously. We applied this system to heavy rain events in Japan. Results show that the system effectively assimilated cloud signals and produced very accurate cloud and precipitation distributions. The system also accurately formed a consistent atmospheric field around the cloud. Precipitation intensity was also substantially improved by appropriately representing the local atmospheric field. Furthermore, combination of the method and operationally analyzed dynamical and moisture fields improved prediction of precipitation duration. The results demonstrate the method's promise in dramatically improving predictions of heavy rain and consequent flooding.

  20. Data assimilation with the ensemble Kalman filter in a numerical model of the North Sea

    Science.gov (United States)

    Ponsar, Stéphanie; Luyten, Patrick; Dulière, Valérie

    2016-08-01

    Coastal management and maritime safety strongly rely on accurate representations of the sea state. Both dynamical models and observations provide abundant pieces of information. However, none of them provides the complete picture. The assimilation of observations into models is one way to improve our knowledge of the ocean state. Its application in coastal models remains challenging because of the wide range of temporal and spatial variabilities of the processes involved. This study investigates the assimilation of temperature profiles with the ensemble Kalman filter in 3-D North Sea simulations. The model error is represented by the standard deviation of an ensemble of model states. Parameters' values for the ensemble generation are first computed from the misfit between the data and the model results without assimilation. Then, two square root algorithms are applied to assimilate the data. The impact of data assimilation on the simulated temperature is assessed. Results show that the ensemble Kalman filter is adequate for improving temperature forecasts in coastal areas, under adequate model error specification.

  1. Assimilation of Aura Ozone Data and Comparisons with In Situ Observations

    Science.gov (United States)

    Stajner, Ivanka; Wargan, Krzysztof; Pawson, Steven

    2008-01-01

    Ozone data from the Ozone Monitoring Instrument (OMI) and the Microwave Limb Sounder (MLS) onboard EOS Aura satellite were assimilated into the Goddard Earth Observing System Version 4 (GEOS-4) ozone assimilation system. Comparison of assimilated ozone with ozone sonde and MOZAIC data indicate an agreement within 10% in the lower stratosphere, where dynamical processes dominate. Assimilation of OMI and MLS data improves tropospheric column estimates in the Atlantic region, but leads to an overestimation in the tropical Pacific in comparison with SHADOZ sondes. Transport and data biases are considered in order to understand these discrepancies. Comparisons of assimilated tropospheric ozone columns with ozone sonde data reveal root-mean-square (RMS) differences of 2.9 to 7.2 DU, which are typically smaller than the model-sonde RMS differences. Four different definitions of the tropopause using temperature lapse rate, potential vorticity (PV) and isentropic surfaces or ozone isosurfaces are compared with respect to their global impact on the estimated tropospheric ozone column. The largest sensitivity in the tropospheric ozone column is found near the subtropical jet, where the ozone or PV determined tropopause typically lies below the lapse rate tropopause.

  2. Implicit assimilation for marine ecological models

    Science.gov (United States)

    Weir, B.; Miller, R.; Spitz, Y. H.

    2012-12-01

    We use a new data assimilation method to estimate the parameters of a marine ecological model. At a given point in the ocean, the estimated values of the parameters determine the behaviors of the modeled planktonic groups, and thus indicate which species are dominant. To begin, we assimilate in situ observations, e.g., the Bermuda Atlantic Time-series Study, the Hawaii Ocean Time-series, and Ocean Weather Station Papa. From there, we estimate the parameters at surrounding points in space based on satellite observations of ocean color. Given the variation of the estimated parameters, we divide the ocean into regions meant to represent distinct ecosystems. An important feature of the data assimilation approach is that it refines the confidence limits of the optimal Gaussian approximation to the distribution of the parameters. This enables us to determine the ecological divisions with greater accuracy.

  3. SERUM CHEMISTRY ABNORMALITIES IN CHILDREN WITH UNPROVOKED SEIZURES

    Directory of Open Access Journals (Sweden)

    J. Akhondian MD,

    2007-02-01

    Full Text Available ObjectiveMost children brought to the emergency department (ED for evaluation of seizures undergo an extensive laboratory workup. Since results are usually negative, the value of such routine laboratory workups has been questioned. A group of children with unprovoked seizures was prospectively studied to determine the diagnostic values of routine serum chemistries and to identify risk factors predictive of abnormal findings.Materials & MethodsAll patients evaluated at the ED of the Ghaem hospital during a consecutive 12 months period between Jan 2004 through Jan 2005 were studied. We collected data for patient's demographics, details of the history of present illness (including vomiting, diarrhea, apnea, medication use, past history of seizures, family history of seizures, metabolic disorders or other chronic medical illnesses, neonatal history and neurological examination as well as nutritional status, type and time of seizure. The role of abnormal serum chemistries as a seizure trigger factor was assessed in patients with a history of seizure.ResultsA total of 210 patients (mean age 19.2 months with unprovoked seizures were evaluated. Twenty- three serum abnormalities were noted in the patients (12 cases of hyponatremia, 7 of hypoglycemia, 4 of hypokalemia, 4 of uremia. The incidence of abnormal serum biochemical values was higher in patients with a first seizure, younger patients, and those with gastrointestinal symptoms.ConclusionAccording to the present study, one can conclude that in children younger than 2 years and having no structural CNS abnormality, electrolyte and glucose screening is recommended only for a first unprovoked seizure, when gastrointestinal symptoms or symptoms suggesting electrolyte disturbances are present.

  4. Modeling Seizure Self-Prediction: An E-Diary Study

    Science.gov (United States)

    Haut, Sheryl R.; Hall, Charles B.; Borkowski, Thomas; Tennen, Howard; Lipton, Richard B.

    2013-01-01

    Purpose A subset of patients with epilepsy successfully self-predicted seizures in a paper diary study. We conducted an e-diary study to ensure that prediction precedes seizures, and to characterize the prodromal features and time windows that underlie self-prediction. Methods Subjects 18 or older with LRE and ≥3 seizures/month maintained an e-diary, reporting AM/PM data daily, including mood, premonitory symptoms, and all seizures. Self-prediction was rated by, “How likely are you to experience a seizure [time frame]”? Five choices ranged from almost certain (>95% chance) to very unlikely. Relative odds of seizure (OR) within time frames was examined using Poisson models with log normal random effects to adjust for multiple observations. Key Findings Nineteen subjects reported 244 eligible seizures. OR for prediction choices within 6hrs was as high as 9.31 (1.92,45.23) for “almost certain”. Prediction was most robust within 6hrs of diary entry, and remained significant up to 12hrs. For 9 best predictors, average sensitivity was 50%. Older age contributed to successful self-prediction, and self-prediction appeared to be driven by mood and premonitory symptoms. In multivariate modeling of seizure occurrence, self-prediction (2.84; 1.68,4.81), favorable change in mood (0.82; 0.67,0.99) and number of premonitory symptoms (1,11; 1.00,1.24) were significant. Significance Some persons with epilepsy can self-predict seizures. In these individuals, the odds of a seizure following a positive prediction are high. Predictions were robust, not attributable to recall bias, and were related to self awareness of mood and premonitory features. The 6-hour prediction window is suitable for the development of pre-emptive therapy. PMID:24111898

  5. Serum prolactin for differentiating epileptic seizures in children

    Directory of Open Access Journals (Sweden)

    Harry Mangunsong

    2015-09-01

    Full Text Available Background Serum prolactin level has been used as a marker to differentiate epileptic from non-epileptic seizures in adults. Electroencephalogram (EEG examination is the primary diagnostic tool used to assess seizures. However, EEGs are quite difficult to perform in children and have sensitivity of only 50%-55%, with 96% specificity. Objective To assess the diagnostic potential of serum prolactin level as an alternative tool for children for differentiating between epileptic and non-epileptic seizures. Methods This diagnostic study was performed between January 2013 and December 2013. Thirty patients aged 3 months to 15 years with seizures and without fever who visited the Emergency Department of Arifin Ahmad Hospital, Pekanbaru, Riau, were included. Blood specimens were collected within 2 hours after seizure. Subjects underwent serum prolactin measurements and EEG examinations. Results Fifteen subjects had normal EEGs and 15 subjects had abnormal EEGs. Post-ictal serum prolactin levels were significantly higher in the epileptiform EEG group. The mean serum prolactin levels were 23.78 (SD 21.86 ng/mL and 10.57 (SD 5.62ng/mL in patients with epileptic and non-epileptic patients, respectively. Using a prolactin cut-off point of 17.2 ng/mL, serum prolactin had a 73.3% sensitivity and 93.3% specificity for differentiating between epileptic and non-epileptic seizures. Conclusion Our findings suggest that serum prolactin level increases after an epileptic seizure, but not after a non-epileptic seizure. Post-ictal prolactin elevation within 2 hours may be useful in differentiating epileptic seizures from non-epileptic seizures.

  6. Serum prolactin for differentiating epileptic seizures in children

    Directory of Open Access Journals (Sweden)

    Harry Mangunsong

    2015-10-01

    Full Text Available Background Serum prolactin level has been used as a marker to differentiate epileptic from non-epileptic seizures in adults. Electroencephalogram (EEG examination is the primary diagnostic tool used to assess seizures. However, EEGs are quite difficult to perform in children and have sensitivity of only 50%- 55%, with 96% specificity. Objective To assess the diagnostic potential of serum prolactin level as an alternative tool for children for differentiating between epileptic and non-epileptic seizures. Methods This diagnostic study was performed between January 2013 and December 2013. Thirty patients aged 3 months to 15 years with seizures and without fever who visited the Emergency Department of Arifin Ahmad Hospital, Pekanbaru, Riau, were included. Blood specimens were collected within 2 hours after seizure. Subjects underwent serum prolactin measurements and EEG examinations. Results Fifteen subjects had normal EEGs and 15 subjects had abnormal EEGs. Post-ictal serum prolactin levels were significantly higher in the epileptiform EEG group. The mean serum prolactin levels were 23.78 (SD 21.86 ng/mL and 10.57 (SD 5.62ng/mL in patients with epileptic and non-epileptic patients, respectively. Using a prolactin cut-off point of 17.2 ng/mL, serum prolactin had a 73.3% sensitivity and 93.3% specificity for differentiating between epileptic and non-epileptic seizures. Conclusion Our findings suggest that serum prolactin level increases after an epileptic seizure, but not after a non-epileptic seizure. Post-ictal prolactin elevation within 2 hours may be useful in differentiating epileptic seizures from non-epileptic seizures.

  7. Neurodiagnostic Evaluation of a Child with First Complex Febrile Seizure

    Directory of Open Access Journals (Sweden)

    Arpita S Thakker

    2016-04-01

    Full Text Available Background: Febrile seizure is the most common type of childhood seizure and complex febrile seizure has been associated with the risk of epilepsy. The neurodiagnostic evaluation of a child with first CFS is still unclear. Aim & Objective: To assess the clinical characteristics and diagnostic evaluation of children aged 1 month to 5 years presenting with first Complex Febrile Seizure (CFS and to determine the utility of various investigations in a case of first CFS. Material and Methods: A prospective study was conducted in the pediatric department of a tertiary hospital. Fortynine children aged 1 month-5 years with first CFS fulfilling the inclusion criteria were enrolled in the study over duration of 8-months. All the cases were evaluated with complete blood count, serum calcium, serum electrolytes, Electroencephalography (EEG, CT/MRI and lumbar puncture. Results: The investigation results were analyzed with respect to different CFS parameter like type of seizure (focal or generalized and duration of seizure(less than or more than 15 minutes. Upper respiratory tract infection is the main cause of febrile seizure. The duration of CFS did not vary according to the underlying cause. Serum calcium levels are found to be lower in children with complex febrile seizure. All children with CFS, whether focal or multiple generalized, whether of long or short duration, had a normal EEG. Children who had prolonged focal and multiple generalized seizures had abnormal neuroimaging but it was not statistically significant. Conclusion: We conclude from our study that a child with first CFS may not need EEG and neuroimaging as a diagnostic evaluation test. Hypocalcemia can be identified in these children and can be corrected to stop the seizure. Further studies are needed on a large series of children with first CFS to form guidelines for their neurodiagnostic evaluation.

  8. Zinc chelation reduces hippocampal neurogenesis after pilocarpine-induced seizure.

    Directory of Open Access Journals (Sweden)

    Jin Hee Kim

    Full Text Available Several studies have shown that epileptic seizures increase hippocampal neurogenesis in the adult. However, the mechanism underlying increased neurogenesis after seizures remains largely unknown. Neurogenesis occurs in the subgranular zone (SGZ of the hippocampus in the adult brain, although an understanding of why it actively occurs in this region has remained elusive. A high level of vesicular zinc is localized in the presynaptic terminals of the SGZ. Previously, we demonstrated that a possible correlation may exist between synaptic zinc localization and high rates of neurogenesis in this area after hypoglycemia. Using a lithium-pilocarpine model, we tested our hypothesis that zinc plays a key role in modulating hippocampal neurogenesis after seizure. Then, we injected the zinc chelator, clioquinol (CQ, 30 mg/kg, into the intraperitoneal space to reduce brain zinc availability. Neuronal death was detected with Fluoro Jade-B and NeuN staining to determine whether CQ has neuroprotective effects after seizure. The total number of degenerating and live neurons was similar in vehicle and in CQ treated rats at 1 week after seizure. Neurogenesis was evaluated using BrdU, Ki67 and doublecortin (DCX immunostaining 1 week after seizure. The number of BrdU, Ki67 and DCX positive cell was increased after seizure. However, the number of BrdU, Ki67 and DCX positive cells was significantly decreased by CQ treatment. Intracellular zinc chelator, N,N,N0,N-Tetrakis (2-pyridylmethyl ethylenediamine (TPEN, also reduced seizure-induced neurogenesis in the hippocampus. The present study shows that zinc chelation does not prevent neurodegeneration but does reduce seizure-induced progenitor cell proliferation and neurogenesis. Therefore, this study suggests that zinc has an essential role for modulating hippocampal neurogenesis after seizure.

  9. The Computational Complexity, Parallel Scalability, and Performance of Atmospheric Data Assimilation Algorithms

    Science.gov (United States)

    Lyster, Peter M.; Guo, J.; Clune, T.; Larson, J. W.; Atlas, Robert (Technical Monitor)

    2001-01-01

    The computational complexity of algorithms for Four Dimensional Data Assimilation (4DDA) at NASA's Data Assimilation Office (DAO) is discussed. In 4DDA, observations are assimilated with the output of a dynamical model to generate best-estimates of the states of the system. It is thus a mapping problem, whereby scattered observations are converted into regular accurate maps of wind, temperature, moisture and other variables. The DAO is developing and using 4DDA algorithms that provide these datasets, or analyses, in support of Earth System Science research. Two large-scale algorithms are discussed. The first approach, the Goddard Earth Observing System Data Assimilation System (GEOS DAS), uses an atmospheric general circulation model (GCM) and an observation-space based analysis system, the Physical-space Statistical Analysis System (PSAS). GEOS DAS is very similar to global meteorological weather forecasting data assimilation systems, but is used at NASA for climate research. Systems of this size typically run at between 1 and 20 gigaflop/s. The second approach, the Kalman filter, uses a more consistent algorithm to determine the forecast error covariance matrix than does GEOS DAS. For atmospheric assimilation, the gridded dynamical fields typically have More than 10(exp 6) variables, therefore the full error covariance matrix may be in excess of a teraword. For the Kalman filter this problem can easily scale to petaflop/s proportions. We discuss the computational complexity of GEOS DAS and our implementation of the Kalman filter. We also discuss and quantify some of the technical issues and limitations in developing efficient, in terms of wall clock time, and scalable parallel implementations of the algorithms.

  10. On the Assimilation of Tree-Ring-Width Chronologies

    Science.gov (United States)

    Acevedo, Walter; Reich, Sebastian; Cubasch, Ulrich

    2015-04-01

    Data assimilation (DA) of climate proxy records is currently acknowledged as a promising approach to the paleoclimate reconstruction problem, with the potential to bring physical consistency to reconstructed fields. Previous paleo-DA studies have typically assumed a linear relationship between climate forcing and the resulting proxy data, whereas there exist growing evidence of complex, potentially non-linear, proxy formation processes. Accordingly, it appears natural to simulate the proxy response to climate in a more realistic fashion, by way of proxy-specific forward models. Following this train of thought, we investigate the assimilation of the most traditional climate proxy type, Tree-Ring-Width (TRW) chronologies, using the process-based tree-ring growth forward model Vaganov-Shashkin-Lite (VSL) and ensemble Kalman filter (EnKF) techniques. Used as observation operator, VSL's formulation implies three compounding, challenging features: (i) time averaging, (ii) "switching recording" of 2 variables and (iii) bounded response windows leading to "thresholded response". DA experiments involving VSL-based pseudo-TRW observations are performed first for a chaotic 2-scale dynamical system, used as a cartoon of the atmosphere-land system, and then for an atmospheric general circulation model of intermediate complexity. Our results reveal that VSL's nonlinearities may considerable deteriorate the performance of EnKF for Time-Averaged (TA) estimation, as compared to the utilization of a TA linear observation operator. Moreover, we show that this assimilation skill loss can be considerably reduced by embedding VSL's formulation into fuzzy logic theory, which fosters new interpretations of tree-ring growth limitation processes.

  11. Why Are Seizures Rare in Rapid Eye Movement Sleep? Review of the Frequency of Seizures in Different Sleep Stages

    Directory of Open Access Journals (Sweden)

    Marcus Ng

    2013-01-01

    Full Text Available Since the formal characterization of sleep stages, there have been reports that seizures may preferentially occur in certain phases of sleep. Through ascending cholinergic connections from the brainstem, rapid eye movement (REM sleep is physiologically characterized by low voltage fast activity on the electroencephalogram, REMs, and muscle atonia. Multiple independent studies confirm that, in REM sleep, there is a strikingly low proportion of seizures (~1% or less. We review a total of 42 distinct conventional and intracranial studies in the literature which comprised a net of 1458 patients. Indexed to duration, we found that REM sleep was the most protective stage of sleep against focal seizures, generalized seizures, focal interictal discharges, and two particular epilepsy syndromes. REM sleep had an additional protective effect compared to wakefulness with an average 7.83 times fewer focal seizures, 3.25 times fewer generalized seizures, and 1.11 times fewer focal interictal discharges. In further studies REM sleep has also demonstrated utility in localizing epileptogenic foci with potential translation into postsurgical seizure freedom. Based on emerging connectivity data in sleep, we hypothesize that the influence of REM sleep on seizures is due to a desynchronized EEG pattern which reflects important connectivity differences unique to this sleep stage.

  12. Multi-modal Intelligent Seizure Acquisition (MISA) system - A new approach towards seizure detection based on full body motion measures

    DEFF Research Database (Denmark)

    Conradsen, Isa; Beniczky, Sándor; Wolf, Peter

    2009-01-01

    Many epilepsy patients cannot call for help during a seizure, because they are unconscious or because of the affection of their motor system or speech function. This can lead to injuries, medical complications and at worst death. An alarm system setting off at seizure onset could help to avoid...

  13. Masturbation mimicking seizure in an infant.

    Science.gov (United States)

    Deda, G; Caksen, H; Suskan, E; Gümüs, D

    2001-08-01

    A 3.5-month-old boy was referred to our hospital with the diagnosis of infantile spasm. His developmental milestones and physical examination were normal. During the follow-up we recorded about six to nine attacks a day and the duration of attacks was changed between 15 seconds-1.5 minutes. During the episodic attacks he was flushed and had tonic posturing associated with crossing of thighs, without loss of consciousness and his eye movements were normal. Routine and long-term electroencephalogram (EEG) were normal during attack. The patient was diagnosed as masturbation according to the clinical and EEG findings. In conclusion, we would like to stress that masturbation should also be considered in infants who were admitted with complaint of seizure, and aside from EEG monitoring a detailed history and careful observation are very important factors in differential diagnosis of these two different conditions.

  14. Acute isoniazid intoxication: seizures, acidosis and coma.

    Science.gov (United States)

    Temmerman, W; Dhondt, A; Vandewoude, K

    1999-08-01

    Isoniazid (INH) is the most widely used of the antituberculosis drugs. An acute overdose is potentially fatal and is characterized by the clinical triad of repetitive seizures unresponsive to the usual anticonvulsants, metabolic acidosis with a high anion gap and coma. The diagnosis of INH overdose should be considered in any patient who presents with an unexplained metabolic acidosis and convulsions. The cornerstone of therapy consists in pyridoxine (vitamin B6) and the dose should be equal to the amount of INH ingested. When conservative therapy fails or in case of renal insufficiency, dialysis must be considered. Severe central nervous toxicity can also be caused by chronic ingestion of higher than therapeutic doses of INH. In those cases pyridoxine-therapy can be useful as well. In the present paper a case of acute overdose of INH is reported, followed by a review of the literature.

  15. Epileptic Seizure, Postictal Hemiparesis, and Hyperleukocytosis

    Directory of Open Access Journals (Sweden)

    Martin Olivieri MD

    2016-12-01

    Full Text Available Introduction: Acute ischemic stroke (AIS is a rare event in infancy. Besides vasculopathy, thrombophilia, or cardiac disorders, cancer and chemotherapy are known predisposing factors for AIS. Leukemia can be associated with different abnormal coagulation parameters, but severe bleeding or thrombosis occurs rarely. Clinical Course: We report the case of a 2-year-old boy who was presented to our emergency ward after a prolonged seizure with right sided postictal hemiparesis. Cranial computed tomography scan revealed a large infarction and edema due to thrombosis of the left carotid artery, the middle cerebral artery, and the anterior cerebral artery. Laboratory workup showed 196 g/L leukocytes with 75% myeloid blast cells. Immediate exchange transfusion, hydration, and chemotherapy with cytarabine were started. During the hospital course intracranial pressure increased and the patient developed a unilateral dilated pupil unresponsive to light. Cranial computed tomography scan revealed a new infarction in the right middle cerebral artery territory. Refractory increased intracranial pressure and brain stem herniation developed, and the child died 3 days after admission to hospital. Conclusion: Seizures with postictal hemiparesis due to cerebral infarction can be a rare manifestation of acute myeloid leukemia. Leukocytosis and cancer-induced coagulopathy are main reasons for thrombosis and/or hemorrhage. High leukocyte counts need immediate interventions with hydration, careful chemotherapy, and perhaps exchange transfusion or leukapharesis. In the presence of thrombosis, anticoagulation must be discussed despite the risk of bleeding due to hyperfibrinolysis and low platelet counts. Mortality may be reduced by awareness of this rare presentation of leukemia and prompt institution of leucoreductive treatment.

  16. The Madden-Julian Oscillation in the NCAR Community Earth System Model Coupled Data Assimilation System

    Science.gov (United States)

    Chatterjee, A.; Anderson, J. L.; Moncrieff, M.; Collins, N.; Danabasoglu, G.; Hoar, T.; Karspeck, A. R.; Neale, R. B.; Raeder, K.; Tribbia, J. J.

    2014-12-01

    We present a quantitative evaluation of the simulated MJO in analyses produced with a coupled data assimilation (CDA) framework developed at the National Center for Atmosphere Research. This system is based on the Community Earth System Model (CESM; previously known as the Community Climate System Model -CCSM) interfaced to a community facility for ensemble data assimilation (Data Assimilation Research Testbed - DART). The system (multi-component CDA) assimilates data into each of the respective ocean/atmosphere/land model components during the assimilation step followed by an exchange of information between the model components during the forecast step. Note that this is an advancement over many existing prototypes of coupled data assimilation systems, which typically assimilate observations only in one of the model components (i.e., single-component CDA). The more realistic treatment of air-sea interactions and improvements to the model mean state in the multi-component CDA recover many aspects of MJO representation, from its space-time structure and propagation (see Figure 1) to the governing relationships between precipitation and sea surface temperature on intra-seasonal scales. Standard qualitative and process-based diagnostics identified by the MJO Task Force (currently under the auspices of the Working Group on Numerical Experimentation) have been used to detect the MJO signals across a suite of coupled model experiments involving both multi-component and single-component DA experiments as well as a free run of the coupled CESM model (i.e., CMIP5 style without data assimilation). Short predictability experiments during the boreal winter are used to demonstrate that the decay rates of the MJO convective anomalies are slower in the multi-component CDA system, which allows it to retain the MJO dynamics for a longer period. We anticipate that the knowledge gained through this study will enhance our understanding of the MJO feedback mechanisms across the air

  17. Variational data assimilation system with nesting model for high resolution ocean circulation

    Energy Technology Data Exchange (ETDEWEB)

    Ishikawa, Yoichi; Igarashi, Hiromichi; Hiyoshi, Yoshimasa; Sasaki, Yuji; Wakamatsu, Tsuyoshi; Awaji, Toshiyuki [Center for Earth Information Science and Technology, Japan Agency for Marine-Earth Science and Technology, 3173-25 Showa-machi, Kanazawa-Ku, Yokohama 236-0001 (Japan); In, Teiji [Japan Marine Science Foundation, 4-24, Minato-cho, Mutsu, Aomori, 035-0064 (Japan); Nakada, Satoshi [Graduate School of Maritime Science, Kobe University, 5-1-1, Fukae-minamimachi, Higashinada-Ku, Kobe, 658-0022 (Japan); Nishina, Kei, E-mail: ishikaway@jamstec.go.jp [Graduate School of Science, Kyoto University, Kitashirakawaoiwake-cho, Sakyo-Ku, Kyoto, 606-8502 (Japan)

    2015-10-15

    To obtain the high-resolution analysis fields for ocean circulation, a new incremental approach is developed using a four-dimensional variational data assimilation system with nesting models. The results show that there are substantial biases when using a classical method combined with data assimilation and downscaling, caused by different dynamics resulting from the different resolutions of the models used within the nesting models. However, a remarkable reduction in biases of the low-resolution model relative to the high-resolution model was observed using our new approach in narrow strait regions, such as the Tsushima and Tsugaru straits, where the difference in the dynamics represented by the high- and low-resolution models is substantial. In addition, error reductions are demonstrated in the downstream region of these narrow channels associated with the propagation of information through the model dynamics. (paper)

  18. Involvement of central histamine in amygdaloid kindled seizures in rats.

    Science.gov (United States)

    Kamei, C

    2001-10-15

    The involvement of central histamine in amygdaloid kindled seizures in rats was investigated using histamine-related compounds. Histamine contents in the amygdala of electrical stimulation site was significantly decreased after development of amygdaloid kindling. Intracerebroventricular (i.c.v.) injection of histamine resulted in inhibition of amygdaloid kindled seizures. The H(1)-agonists 2-methylhistamine and 2-thiazolylethylamine also inhibited amygdaloid kindled seizures. In addition, intraperitoneal (i.p.) injection of histidine and metoprine inhibited amygdaloid kindled seizures at doses that caused increases in histamine contents of the brain. H(1)-antagonists (diphenhydramine and chlorpheniramine) attenuated histamine (i.c.v.)-induced inhibition of amygdaloid kindled seizures, however, no significant antagonism was observed with H(2)-antagonists (cimetidine, ranitidine or zolantidine). Intracerebroventricular injection of H(3)-antagonists (thioperamide and AQ 0145) resulted in a dose-related inhibition of amygdaloid kindled seizures. The same findings were observed when thioperamide and clobenpropit were injected i.p. The effects of thioperamide (i.p.) and AQ 0145 (i.p.) were inhibited by an H(3)-agonist [(R)-alpha-methylhistamine] and H(1)-antagonists (diphenhydramine and chlorpheniramine). On the other hand, H(2)-antagonists (cimetidine and ranitidine) showed no antagonistic effects. These findings suggested that a histaminergic mechanism plays an important role in suppressing amygdaloid kindled seizures through histamine H(1)-receptors.

  19. Cocaine-Associated Seizures and Incidence of Status Epilepticus

    Directory of Open Access Journals (Sweden)

    Majlesi, Nima DO

    2010-05-01

    Full Text Available Objectives: Acute complications from cocaine abuse are commonly treated in the emergency department (ED; one of the most consequential is status epilepticus. The incidence of this complication is not clearly defined in the prior literature on cocaine-associated sequelae. We evaluated the incidence of status epilepticus in patients with seizures secondary to suspected cocaine use.Methods: We performed a retrospective multi-center study of patients with seizures resulting from cocaine use. We identified study subjects at 15 hospitals by record review and conducted a computer-assisted records search to identify patients with seizures for each institution over a four-year period. We selected subjects from this group on the basis of cocaine use and determined the occurrence of status epilepticus among them. Data were collected on each subject using a standardized data collection form.Results: We evaluated 43 patients in the ED for cocaine-associated seizures. Their age range was 17 to 54, with a mean age was 31 years; 53% were male. Of 43 patients, 42 experienced a single tonic-clonic seizure and one developed status epilepticus. All patients had either a history of cocaine use or positive urine drug screen for cocaine.Conclusion: Despite reported cases of status epilepticus with cocaine-induced seizures, the incidence of this complication was unclear based on prior literature. This study shows that most cocaine-associated seizures are self-limited. [West J Emerg Med. 2010; 11(2:157-160.

  20. A case of seizures induced by abstract reasoning.

    Science.gov (United States)

    Tatsuzawa, Yasutaka; Yoshino, Aihide; Nomura, Soichiro

    2010-04-01

    We describe a case of reflex seizures induced by abstract reasoning but not other cognitive processes. The patient, a 46-year-old man, experienced myoclonic seizures whenever he played shogi (Japanese chess). To identify the critical thought processes responsible for inducing his seizures, we monitored his clinical seizures and epileptiform discharges while he performed comprehensive neuropsychological tests, including the Wechsler Adult Intelligence Scale-Revised (WAIS-R), spatial working memory, mental rotation, and Wisconsin Card Sorting Test (WCST) tasks. A myoclonic seizure occurred only during the WCST. Generalized 3- to 5-Hz spike-and-slow-wave bursts occurred repeatedly during the Block Design subtest of the WAIS-R and the WCST, whereas no discharges occurred during other subtests of the WAIS-R including the calculation, spatial working memory, and mental rotation tasks. These results indicate that abstract reasoning, independent of other cognitive processes, could induce the patient's epileptiform discharges, suggesting that his reflex seizures might be a distinct subtype of nonverbal thinking-induced seizures.

  1. INTERMITTENT CLONAZEPAM IN THE PREVENTION OF RECURRENT FEBRILE SEIZURES

    Directory of Open Access Journals (Sweden)

    Touran MAHMOUDIAN

    2010-10-01

    Full Text Available ObjectiveTo evaluate the efficacy and common side effects of intermittent clonazepam in febrile  seizures.Materials & MethodsThis study was an experimental trial designed to determine the efficacy of intermittent clonazepam in febrile seizures .Thirty patients with an age range of 6 months to 5 years (60% male, 40% female were studied. Children with a history of psychomotor delay, abnormal  neurological examination, a history of antiepileptic drug consumption, and afebrile seizures were excluded from the study. Patients received a single dose of prophylactic Clonazepam (0.05 mg/kg/ day on the first day of febrile illness and twice daily during the course of fever.An antipyretic medication (Acetaminophen was advised if fever exceeded 38oC. Patients were followed up for one year after the study inclusion date.ResultsThree patients were excluded from study since they didnot follow the tritment and three patients experienced afebrile seizures. Twenty four patients had 162 febrile episodes during the course of the study and all patients were seizure-free after 1 year.ConclusionClonazepam was 100% effective but lethargy and ataxia were common side effects in patients. Fortunately, their parents continued treatment because they had prior awareness of the  possible side effects of clonazepam. Clonazepam is efficacious as an intermittent therapy for febrile seizures if parents are informed of its side effects.Keywords: recurrent febrile seizures, clonazepam, intermittent prophylaxis

  2. Phonological Assimilation and Visual Word Recognition

    Science.gov (United States)

    Lee, Yang; Moreno, Miguel A.; Park, Hyeongsaeng; Carello, Claudia; Turvey, Michael T.

    2006-01-01

    Are the visual word-processing tasks of naming and lexical decision sensitive to systematic phonological properties that may or may not be specified in the spelling? Two experiments with Hangul, the alphabetic orthography of Korea, were directed at the effects of the phonological process of assimilation whereby one articulation changes to conform…

  3. At first glance, transparency enhances assimilation

    NARCIS (Netherlands)

    Koning, A.R.; Weert, C.M.M. de; Lier, R.J. van

    2008-01-01

    We investigated the role of transparency, perceptual grouping, and presentation time on perceived lightness. Both transparency and perceptual grouping have been found to result in assimilation effects, but only for ambiguous stimulus displays and with specific attentional instructions. By varying th

  4. Context effect in assimilation and contrast

    NARCIS (Netherlands)

    Weert, C.M.M. de; Koning, A.R.; Lier, R.J. van

    2005-01-01

    We have systematically studied the change of lightness appearance in an ambiguous visual pattern. Fuchs (1923 Zeitschrift für Psychologie 92 249 - 325) found that differently coloured parts assimilate, whereas Agostini et al (1993 Perception 22 263 - 272) described the opposite effect: contrast betw

  5. Data Assimilation With Regional Lagrangian Models

    Science.gov (United States)

    1999-09-30

    Journal of Marine Systems . RESULTS We are able to fit the inviscid Lagrangian model with synthetic Lagrangian data for short periods of time (1-2 days...Mead and A.F. Bennett, 1999. Towards regional assimilation of data: The Lagrangian form of the reduced gravity model and its inverse, (submitted), Journal of Marine Systems .

  6. A new sequential data assimilation method

    Institute of Scientific and Technical Information of China (English)

    HAN YueQi; ZHANG YaoCun; WANG YunFeng; YE Song; FANG HanXian

    2009-01-01

    A new sequential data assimilation method named "Monte Carlo H∞ filter" is Introduced based on H∞ filter technique and Monte Carlo method in this paper. This method applies to nonlinear systems in condition of lacking the statistical properties of observational errors. In order to compare the assimilation capability of Monte Carlo H= filter with that of the ensemble Kalman filter (EnKF) in solving practical problems caused by temporal correlation or spatial correlation of observational errors, two numerical experiments are performed by using Lorenz (1963) system and shallow-water equations respectively. The result is that the assimilation capability of the new method is better than that of EnKF method. It is also shown that Monte Carlo H∞ filter assimilation method is effective and suitable to nonlinear systems in that it does not depend on the statistical properties of observational errors and has better robustnesa than EnKF method when the statistical properties of observational errors are varying. In addition, for the new method, the smallest level factor founded by search method is flow-dependent.

  7. Ensemble Assimilation of Nonconventional Observations for Nowcasting

    Science.gov (United States)

    2013-09-30

    microphysical fields (qc - cloud liquid water mixing ratio, qi – cloud ice mixing ratio, qr – rain water mixing ratio, qs – snow ice mixing ratio, and qg...L. Wei, W. Gu, J. Gong , and Q. Zhao, 2010: A 3.5-dimensional Variational Method for Doppler Radar Data Assimilation and Its Application to

  8. Rates, Mechanisms, and Implications of Crustal Assimilation in Continental Arcs

    Science.gov (United States)

    Dungan, M.; Davidson, J.

    2002-12-01

    Contrary to the limiting constraints postulated by Bowen for the coupled thermal and mass balance implicated in assimilation, many studies [1-6] suggest that multi-stage and multi-component assimilation, abetted by magma mixing, may be volumetrically important and have profound consequences for the chemistry of basaltic and evolved magmas in long-lived continental magmatic systems. The probability of a primitive or evolved basalt arriving at the Earth's surface having undergone perfectly closed-system evolution during passage through 25-60 km of continental crust is vanishingly low. A case-by-case demonstration that the intra-crustal chemical overprint is trivial, or that it can be quantified and subtracted, is an essential step in any evaluation of mantle source-region chemistry and processes based on inversion of continental basalt compositions. In magmatic systems characterized by mafic magma recharge the thermal energy and physical dynamism needed for assimilation are not constrained to come uniquely from one magma batch [7, 8]. Equally important is that assimilation is rarely equivalent to bulk melting of ingested blocks followed by reservoir-wide homogenization. The mechanics of crustal assimilation are governed by grain boundary melting, disaggregation, and dispersal of refractory solids (including xenocryst settling) wherein liberated low-density, incompatible element-enriched partial melts have the capacity to render primitive arc magma batches variably modified, as well as heterogeneous on short length-scales. Evidence that basalts thermally erode surface channels and conduit walls, and new observations constraining the maximum time that some extensively melted xenoliths have resided in their host magmas, indicate that the time required to impose an open-system overprint on a hot basaltic magma (days to yrs) is far shorter than typical repose periods at most arc volcanoes (50-500 yrs). Assimilative recycling of broadly gabbroic arc cumulates has had large

  9. A flexible Open Data Assimilation framework

    Science.gov (United States)

    van Velzen, Nils; Ridler, Marc E.; Altaf, Umer; Madsen, Henrik; Heemink, Arnold; Dijkzeul, Johan

    2015-04-01

    Accurate and reliable real-time hydrological forecasts are essential for protection against water-related hazards, operation of infrastructure, and water resources management. Recent advances in radar rainfall estimation and forecasting, numerical weather predictions, satellite and in-situ monitoring, and faster computing facilities are opening up new opportunities in real-time hydrological forecasting. More effective use of the different information sources via data assimilation will provide the basis for producing more accurate and more reliable forecasts. In this regard, development and implementation of robust and computationally efficient data assimilation algorithms that are feasible for real-time applications remains one of the key challenges. The implementation of data assimilation techniques is traditionally in a model specific form. The disadvantage of this approach is the need to have in-depth knowledge of the numerical core computations and it does not allow to freely experiment with data assimilation algorithms and measurement sources without the need of additional programming. We present a more flexible approach to setup a forecasting system. The OpenDA data assimilation framework contains many state of the art data assimilation algorithms to easily set up a forecasting system. The setup of the framework allows users to select and experiment with various algorithms. OpenDA defines an interface between model and data assimilation algorithms. This interface only needs to be implemented once for a particular model. The OpenDA model interface is already implemented for various models. Besides these models it is very easy to couple models that are already implementing the Open Model Interface (OpenMI) to OpenDA using the generic OpenMI-OpenDA coupler. Using a synthetic test case we demonstrate the capabilities of the proposed approach using OpenMI and OpenDA. We use the MIKE SHE distributed and integrated hydrological modeling system to demonstrate how

  10. A hardware-algorithm co-design approach to optimize seizure detection algorithms for implantable applications.

    Science.gov (United States)

    Raghunathan, Shriram; Gupta, Sumeet K; Markandeya, Himanshu S; Roy, Kaushik; Irazoqui, Pedro P

    2010-10-30

    Implantable neural prostheses that deliver focal electrical stimulation upon demand are rapidly emerging as an alternate therapy for roughly a third of the epileptic patient population that is medically refractory. Seizure detection algorithms enable feedback mechanisms to provide focally and temporally specific intervention. Real-time feasibility and computational complexity often limit most reported detection algorithms to implementations using computers for bedside monitoring or external devices communicating with the implanted electrodes. A comparison of algorithms based on detection efficacy does not present a complete picture of the feasibility of the algorithm with limited computational power, as is the case with most battery-powered applications. We present a two-dimensional design optimization approach that takes into account both detection efficacy and hardware cost in evaluating algorithms for their feasibility in an implantable application. Detection features are first compared for their ability to detect electrographic seizures from micro-electrode data recorded from kainate-treated rats. Circuit models are then used to estimate the dynamic and leakage power consumption of the compared features. A score is assigned based on detection efficacy and the hardware cost for each of the features, then plotted on a two-dimensional design space. An optimal combination of compared features is used to construct an algorithm that provides maximal detection efficacy per unit hardware cost. The methods presented in this paper would facilitate the development of a common platform to benchmark seizure detection algorithms for comparison and feasibility analysis in the next generation of implantable neuroprosthetic devices to treat epilepsy.

  11. OpenDA-NEMO framework for ocean data assimilation

    NARCIS (Netherlands)

    Van Velzen, C.; Altaf, M.U.; Verlaan, M.

    2016-01-01

    Data assimilation methods provide a means to handle the modeling errors and uncertainties in sophisticated ocean models. In this study, we have created an OpenDA-NEMO framework unlocking the data assimilation tools available in OpenDA for use with NEMO models. This includes data assimilation methods

  12. Estimation of friction parameters in gravity currents by data assimilation in a model hierarchy

    Directory of Open Access Journals (Sweden)

    A. Wirth

    2011-01-01

    Full Text Available This paper is the last in a series of three investigating the friction laws and their parametrisation in idealised gravity currents in a rotating frame. Results on the dynamics of a gravity current (Wirth, 2009 and on the estimation of friction laws by data assimilation (Wirth and Verron, 2008 are combined to estimate the friction parameters and discriminate between friction laws in non-hydrostatic numerical simulations of gravity current dynamics, using data assimilation and a reduced gravity shallow water model.

    I demonstrate, that friction parameters and laws in gravity currents can be estimated using data assimilation. The results clearly show that friction follows a linear Rayleigh law for small Reynolds numbers and the estimated value agrees well with the analytical value obtained for non-accelerating Ekman layers. A significant and sudden departure towards a quadratic drag law at an Ekman layer based Reynolds number of around 800 is shown, in agreement with classical laboratory experiments. The drag coefficient obtained compare well to friction values over smooth surfaces. I show that data assimilation can be used to determine friction parameters and discriminate between friction laws and that it is a powerful tool in systematically connection models within a model hierarchy.

  13. Estimation of friction parameters in gravity currents by data assimilation in a model hierarchy

    Directory of Open Access Journals (Sweden)

    A. Wirth

    2011-04-01

    Full Text Available This paper is the last in a series of three investigating the friction laws and their parametrisation in idealised gravity currents in a rotating frame. Results on the dynamics of a gravity current (Wirth, 2009 and on the estimation of friction laws by data assimilation (Wirth and Verron, 2008 are combined to estimate the friction parameters and discriminate between friction laws in non-hydrostatic numerical simulations of gravity current dynamics, using data assimilation and a reduced gravity shallow water model.

    I demonstrate, that friction parameters and laws in gravity currents can be estimated using data assimilation. The results clearly show that friction follows a linear Rayleigh law for small Reynolds numbers and the estimated value agrees well with the analytical value obtained for non-accelerating Ekman layers. A significant and sudden departure towards a quadratic drag law at an Ekman layer based Reynolds number of around 800 is shown, in agreement with classical laboratory experiments. The drag coefficient obtained compares well to friction values over smooth surfaces. I show that data assimilation can be used to determine friction parameters and discriminate between friction laws and that it is a powerful tool in systematically connecting models within a model hierarchy.

  14. Continuous data assimilation for downscaling large-footprint soil moisture retrievals

    KAUST Repository

    Altaf, M. U.

    2016-01-01

    Soil moisture is a key component of the hydrologic cycle, influencing processes leading to runoff generation, infiltration and groundwater recharge, evaporation and transpiration. Generally, the measurement scale for soil moisture is found to be different from the modeling scales for these processes. Reducing this mismatch between observation and model scales in necessary for improved hydrological modeling. An innovative approach to downscaling coarse resolution soil moisture data by combining continuous data assimilation and physically based modeling is presented. In this approach, we exploit the features of Continuous Data Assimilation (CDA) which was initially designed for general dissipative dynamical systems and later tested numerically on the incompressible Navier-Stokes equation, and the Benard equation. A nudging term, estimated as the misfit between interpolants of the assimilated coarse grid measurements and the fine grid model solution, is added to the model equations to constrain the model’s large scale variability by available measurements. Soil moisture fields generated at a fine resolution by a physically-based vadose zone model (HYDRUS) are subjected to data assimilation conditioned upon coarse resolution observations. This enables nudging of the model outputs towards values that honor the coarse resolution dynamics while still being generated at the fine scale. Results show that the approach is feasible to generate fine scale soil moisture fields across large extents, based on coarse scale observations. Application of this approach is likely in generating fine and intermediate resolution soil moisture fields conditioned on the radiometer-based, coarse resolution products from remote sensing satellites.

  15. Regulation of nitrate assimilation in cyanobacteria.

    Science.gov (United States)

    Ohashi, Yoshitake; Shi, Wei; Takatani, Nobuyuki; Aichi, Makiko; Maeda, Shin-ichi; Watanabe, Satoru; Yoshikawa, Hirofumi; Omata, Tatsuo

    2011-02-01

    Nitrate assimilation by cyanobacteria is inhibited by the presence of ammonium in the growth medium. Both nitrate uptake and transcription of the nitrate assimilatory genes are regulated. The major intracellular signal for the regulation is, however, not ammonium or glutamine, but 2-oxoglutarate (2-OG), whose concentration changes according to the change in cellular C/N balance. When nitrogen is limiting growth, accumulation of 2-OG activates the transcription factor NtcA to induce transcription of the nitrate assimilation genes. Ammonium inhibits transcription by quickly depleting the 2-OG pool through its metabolism via the glutamine synthetase/glutamate synthase cycle. The P(II) protein inhibits the ABC-type nitrate transporter, and also nitrate reductase in some strains, by an unknown mechanism(s) when the cellular 2-OG level is low. Upon nitrogen limitation, 2-OG binds to P(II) to prevent the protein from inhibiting nitrate assimilation. A pathway-specific transcriptional regulator NtcB activates the nitrate assimilation genes in response to nitrite, either added to the medium or generated intracellularly by nitrate reduction. It plays an important role in selective activation of the nitrate assimilation pathway during growth under a limited supply of nitrate. P(II) was recently shown to regulate the activity of NtcA negatively by binding to PipX, a small coactivator protein of NtcA. On the basis of accumulating genome information from a variety of cyanobacteria and the molecular genetic data obtained from the representative strains, common features and group- or species-specific characteristics of the response of cyanobacteria to nitrogen is summarized and discussed in terms of ecophysiological significance.

  16. Response to diazepam in children with malaria induced seizures

    OpenAIRE

    2008-01-01

    Summary Malaria infection reduces the binding capacity of benzodiazepine receptors in mice. We studied the efficacy of diazepam terminating seizures in children with falciparum malaria. Diazepam stopped seizures in fewer patients with malaria parasitaemia (χ 2 = 3.93, P = 0.047) and those with clinical diagnosis of malaria (χ 2 = 9.84, P = 0.002) compared to those without. However malaria was not identified as an independent risk factor for diazepam's failure to stop seizures in children....

  17. Musical hallucinations associated with seizures originating from an intracranial aneurysm.

    Science.gov (United States)

    Roberts, D L; Tatini, U; Zimmerman, R S; Bortz, J J; Sirven, J I

    2001-04-01

    Hallucinations are defined as sensory phenomena in the absence of external sensory stimuli. Auditory hallucinations have been shown to arise from many different intracranial lesions, but seizures manifesting as musical hallucinations triggered by unruptured intracranial aneurysms are rare. We present a case of persistent, episodic musical hallucinations associated with seizures that led to the discovery of 2 small intracranial aneurysms. Typical electroencephalographic findings for seizure activity were observed but resolved after surgical clipping of the aneurysms. Concomitantly, the patient's hallucinations resolved. The literature on musical hallucinations is reviewed.

  18. Automated differentiation between epileptic and non-epileptic convulsive seizures

    DEFF Research Database (Denmark)

    Beniczky, Sándor; Conradsen, Isa; Moldovan, Mihai

    2015-01-01

    Our objective was the clinical validation of an automated algorithm based on surface electromyography (EMG) for differentiation between convulsive epileptic and psychogenic nonepileptic seizures (PNESs). Forty-four consecutive episodes with convulsive events were automatically analyzed...... with the algorithm: 25 generalized tonic-clonic seizures (GTCSs) from 11 patients, and 19 episodes of convulsive PNES from 13 patients. The gold standard was the interpretation of the video-electroencephalographic recordings by experts blinded to the EMG results. The algorithm correctly classified 24 GTCSs (96......%) and 18 PNESs (95%). The overall diagnostic accuracy was 95%. This algorithm is useful for distinguishing between epileptic and psychogenic convulsive seizures....

  19. Approach To The First Unprovoked Seizure- PART II

    Directory of Open Access Journals (Sweden)

    Mohammad GHOFRANI

    2013-11-01

    Full Text Available How to Cite This Article: Ghofrani M. Approach To The First Unprovoked Seizure- PART II. Iran J Child Neurol. 2013 Autumn; 7(4:1-5.Abstract The approach to a child who has experienced a first unprovoked generalized tonic-clonic seizure is challenging and at the same time controversial.How to establish the diagnosis, ways and means of investigation and whether treatment is appropriate, are different aspects of this subject. In this writing the above mentioned matters are discussed. References31.Berg AT, Testa FM., Levy SR, Shinnar S. Neuroimaging in children with newly diagnosed epilepsy. A community based study. Pediatrics 2000;106:527-532.32.Shinnar S, Odell C. Treating childhood seizure; when and for how long. In: Shinnar S, Amir N, Branski D (Eds. Childhood seizure. S Karger Basel. 1995. P.100-110.33.Shinnar S, Berg AT, Moshe Sl, et al. Risk of Seizure recurrence following a first unprovoked seizure in childhood; A prospective study. Pediatrics 1990;85:1076-2085.34.Shinnar S, Berg At, Moshe SL, et al. The risk of seizure recurrence after a first unprovoked febrile seizure in childhood: An extended follow up. Pediatrics 1996:98:216-225.35.Hauser WA, Rich SS, Annegers JF, Anderson VE. Seizure recurrence after a first unprovoked seizure: An extended follow up. Neurology 1990;40:1163-1170.36.Stroink H, Brouwer O F, Arts WF, Greets AT, Peter AC, Van Donselaar CA. The First unprovoked, untreated seizure in childhood: A hospital based study of the accuracy of diagnosis, rate of recurrence, and long term outcome after recurrence. Dutch study of epilepsy in childhood. J Neurol Neurosurg Psychiatry 1998;64:595-600. 37.Shinnar S, Berg AT, O’Dell C. Newstein D, et al. Predictors of multiple seizure in a cohort of children prospectively followed from the time of their first unprovoked seizure, Ann Neurol 2000; 48:140-147.38.Martinovie Z, Jovic N. Seizure recurrence after a first generalized tonic-clonic seizure in children

  20. Direct assimilation of satellite radiance data in GRAPES variational assimilation system

    Institute of Scientific and Technical Information of China (English)

    ZHU GuoFu; XUE JiShan; ZHANG Hua; LIU ZhiQuan; ZHUANG ShiYu; HUANG LiPing; DONG PeiMing

    2008-01-01

    Variational method is capable of dealing with observations that have a complicated nonlinear relation with model variables representative of the atmospheric state, and so make it possible to directly as-similate such measured variables as satellite radiance, which have a nonlinear relation with the model variables. Assimilation of any type of observations requires a corresponding observation operator, which establishes a specific mapping from the space of the model state to the space of observation. This paper presents in detail how the direct assimilation of real satellite radiance data is implemented in the GRAPES-3DVar analysis system. It focuses on all the components of the observation operator for direct assimilation of real satellite radiance data, including a spatial interpolation operator that trans-forms variables from model grid points to observation locations, a physical transformation from model variables to observed elements with different choices of model variables, and a data quality control. Assimilation experiments, using satellite radiances such as NOAA17 AMSU-A and AMSU-B (Advanced Microwave Sounding Unit), are carried out with two different schemes. The results from these experi-ments can be physically understood and clearly reflect a rational effect of direct assimilation of satellite radiance data in GRAPES-3DVar analysis system.

  1. Increased Seizure Latency and Decreased Severity of Pentylenetetrazol-Induced Seizures in Mice after Essential Oil Administration

    Directory of Open Access Journals (Sweden)

    Eleni Koutroumanidou

    2013-01-01

    Full Text Available The effect of pretreatment with essential oils (EOs from eight aromatic plants on the seizure latency and severity of pentylenetetrazol- (PTZ- induced seizures in mice was evaluated. Weight-dependent doses of Rosmarinus officinalis, Ocimum basilicum, Mentha spicata, Mentha pulegium, Lavandula angustifolia, Mentha piperita, Origanum dictamnus, and Origanum vulgare, isolated from the respective aromatic plants from NE Greece, were administered 60 minutes prior to intraperitoneal (i.p. injection of a lethal dose of PTZ to eight respective groups of Balb-c mice. Control group received only one i.p. PTZ injection. Motor and behavioral activity of the animals after EOs administration, development of tonic-clonic seizures, seizure latency and severity, and percentage of survival after PTZ administration were determined for each group. All groups of mice treated with the EOs showed reduced activity and stability after the administration of the oil, except for those treated with O. vulgare (100% mortality after the administration of the oil. After PTZ administration, mice from the different groups showed increased latency and reduced severity of seizures (ranging from simple twitches to complete seizures. Mice who had received M. piperita demonstrated no seizures and 100% survival. The different drastic component and its concentration could account for the diversity of anticonvulsant effects.

  2. Diagnostic decision-making after a first and recurrent seizure in adults

    NARCIS (Netherlands)

    Askamp, J.; Putten, van M.J.A.M.

    2013-01-01

    Purpose The role of EEG after a first seizure has been debated. Epileptiform EEG activity is a good predictor of seizure recurrence, but is reported in only 8-50% of first-seizure adult patients. Even if the EEG is abnormal, the opinions about treatment after a first seizure differ. The role of EEG

  3. Effect of Immunotherapy on Seizure Outcome in Patients with Autoimmune Encephalitis: A Prospective Observational Registry Study.

    Directory of Open Access Journals (Sweden)

    Jung-Ick Byun

    Full Text Available To evaluate the seizure characteristics and outcome after immunotherapy in adult patients with autoimmune encephalitis (AE and new-onset seizure.Adult (age ≥18 years patients with AE and new-onset seizure who underwent immunotherapy and were followed-up for at least 6 months were included. Seizure frequency was evaluated at 2-4 weeks and 6 months after the onset of the initial immunotherapy and was categorized as "seizure remission", "> 50% seizure reduction", or "no change" based on the degree of its decrease.Forty-one AE patients who presented with new-onset seizure were analysed. At 2-4 weeks after the initial immunotherapy, 51.2% of the patients were seizure free, and 24.4% had significant seizure reduction. At 6 months, seizure remission was observed in 73.2% of the patients, although four patients died during hospitalization. Rituximab was used as a second-line immunotherapy in 12 patients who continued to have seizures despite the initial immunotherapy, and additional seizure remission was achieved in 66.6% of them. In particular, those who exhibited partial response to the initial immunotherapy had a better seizure outcome after rituximab, with low adverse events.AE frequently presented as seizure, but only 18.9% of the living patients suffered from seizure at 6 months after immunotherapy. Aggressive immunotherapy can improve seizure outcome in patients with AE.

  4. Impacts of XBT, TAO, Altimetry and ARGO Observations on the Tropical Pacific Ocean Data Assimilation

    Institute of Scientific and Technical Information of China (English)

    YAN Changxiang; ZHU Jiang; ZHOU Guangqing

    2007-01-01

    This study aims at assessing the relative impacts of four major components of the tropical Pacific Ocean observing system on assimilation of temperature and salinity fields. Observations were collected over a period between January 2001 through June 2003 including temperature data from the expendable bathythermographs (XBT), thermistor data from the Tropical Ocean Global Atmosphere Tropical Atmosphere-Ocean (TOGA-TAO) mooring array, sea level anomalies from the Topex/Poseidon and Jason-1 altimetry (T/P-J),and temperature and salinity profiles from the Array for Real-time Geostrophic Oceanography (ARGO) floats.An efficient three-dimensional variational analysis-based method was introduced to assimilate the above data into the tropical-Pacific circulation model. To evaluate the impact of the individual component of the observing system, four observation system experiments were carried out. The experiment that assimilated all four components of the observing system was taken as the reference. The other three experiments were implemented by withholding one of the four components. Results show that the spatial distribution of the data influences its relative contribution. XBT observations produce the most distinguished effects on temperature analyses in the off-equatorial region due to the large amount of measurements and high quality.Similarly, the impact of TAO is dominant in the equatorial region due to the focus of the spatial distribution.The Topex/Poseidon-Jason-1 can be highly complementary where the XBT and TAO observations are sparse.The contribution of XBT or TAO on the assimilated salinity is made by the model dynamics because no salinity observations from them are assimilated. Therefore, T/P-J, as a main source for providing salinity data, has been shown to have greater impacts than either XBT or TAO on the salinity analysis. Although ARGO includes the subsurface observations, the relatively smaller number of observation makes it have the smallest

  5. UNIFICATION AND APPLICATIONS OF MODERN OCEANIC/ATMOSPHERIC DATA ASSIMILATION ALGORITHMS

    Institute of Scientific and Technical Information of China (English)

    QIAO Fang-li; ZHANG Shao-qing; YUAN Ye-li

    2004-01-01

    The key mathematics and applications of various modern atmospheric/oceanic data assimilation methods including Optimal Interpolation(OI),4-dimensional variational approach(4D-Var)and filters were systematically reviewed and classified.Based on the data assimilation philosophy,I.e.,using model dynamics to extract the observational information,the common character of the problem,such as the probabilistic nature of the evolution of the atmospheric/oceanic system,noisy and irregularly spaced observations,and the advantages and disadvantages of these data assimilation algorithms,were discussed.In the filtering framework,all modern data assimilation algorithms were unified: OI/3D-Var is a stationary filter,4D-Var is a linear(Kalman)filter and an ensemble of Kalman filters is able to construct a nonlinear filter.The nonlinear filter such as the Ensemble Kalman Filter(ENKF),Ensemble Adjustment Kalman Filter(EAKF)and Ensemble Transformation Kalman Filter(ETKF)can,to some extent,account for the non-Gaussian information of the prior distribution from the model.The flow-dependent covariance estimated by an ensemble filter may be introduced to OI and 4D-Var to improve these traditional algorithms.In practice,the performance of algorithms may depend on the specific numerical model and the choice of algorithm may depend on the specific problem.However,the unification of algorithms allows us to establish a unified test system to evaluate these algorithms,which provides more insights into data assimilation philosophies and helps improve data assimilation techniques.

  6. Characteristic strategy of assimilation of various saccharides by Clostridium cellulovorans.

    Science.gov (United States)

    Inamori, Takako; Aburaya, Shunsuke; Morisaka, Hironobu; Kuroda, Kouichi; Ueda, Mitsuyoshi

    2016-12-01

    Clostridium cellulovorans can effectively assimilate not only cellulose but also hemicellulose by producing cellulosomal and non-cellulosomal enzymes. However, little is known about how C. cellulovorans assimilates various saccharides in media containing polysaccharides and oligosaccharides. In this research, we investigated the property of saccharide incorporation and assimilation by C. cellulovorans. Faster growth in media containing xylan and cellulose was achieved by switching polysaccharides, in which xylan was first assimilated, followed by cellulose. Furthermore, the presence of polysaccharides that can be easily degraded might increase the assimilation rate of lignocellulose by promoting growth. These properties of C. cellulovorans could be suitable for the effective utilization of lignocellulosic biomass.

  7. A 3-D variational assimilation scheme in coupled transport-biogeochemical models: Forecast of Mediterranean biogeochemical properties.

    Science.gov (United States)

    Teruzzi, Anna; Dobricic, Srdjan; Solidoro, Cosimo; Cossarini, Gianpiero

    2014-01-01

    [1] Increasing attention is dedicated to the implementation of suitable marine forecast systems for the estimate of the state of the ocean. Within the framework of the European MyOcean infrastructure, the pre-existing short-term Mediterranean Sea biogeochemistry operational forecast system has been upgraded by assimilating remotely sensed ocean color data in the coupled transport-biogeochemical model OPATM-BFM using a 3-D variational data assimilation (3D-VAR) procedure. In the present work, the 3D-VAR scheme is used to correct the four phytoplankton functional groups included in the OPATM-BFM in the period July 2007 to September 2008. The 3D-VAR scheme decomposes the error covariance matrix using a sequence of different operators that account separately for vertical covariance, horizontal covariance, and covariance among biogeochemical variables. The assimilation solution is found in a reduced dimensional space, and the innovation for the biogeochemical variables is obtained by the sequential application of the covariance operators. Results show a general improvement in the forecast skill, providing a correction of the basin-scale bias of surface chlorophyll concentration and of the local-scale spatial and temporal dynamics of typical bloom events. Further, analysis of the assimilation skill provides insights into the functioning of the model. The computational costs of the assimilation scheme adopted are low compared to other assimilation techniques, and its modular structure facilitates further developments. The 3D-VAR scheme results especially suitable for implementation within a biogeochemistry operational forecast system.

  8. Data-assimilation by delay-coordinate nudging

    CERN Document Server

    Pazó, D; López, J M

    2015-01-01

    A new nudging method for data assimilation, delay-coordinate nudging, is presented. Delay-coordinate nudging makes explicit use of present and past observations in the formulation of the forcing driving the model evolution at each time-step. Numerical experiments with a low order chaotic system show that the new method systematically outperforms standard nudging in different model and observational scenarios, also when using an un-optimized formulation of the delay-nudging coefficients. A connection between the optimal delay and the dominant Lyapunov exponent of the dynamics is found based on heuristic arguments and is confirmed by the numerical results, providing a guideline for the practical implementation of the algorithm. Delay-coordinate nudging preserves the easiness of implementation, the intuitive functioning and the reduced computational cost of the standard nudging, making it a potential alternative especially in the field of seasonal-to-decadal predictions with large Earth system models that limit ...

  9. Sample size reduction in groundwater surveys via sparse data assimilation

    KAUST Repository

    Hussain, Z.

    2013-04-01

    In this paper, we focus on sparse signal recovery methods for data assimilation in groundwater models. The objective of this work is to exploit the commonly understood spatial sparsity in hydrodynamic models and thereby reduce the number of measurements to image a dynamic groundwater profile. To achieve this we employ a Bayesian compressive sensing framework that lets us adaptively select the next measurement to reduce the estimation error. An extension to the Bayesian compressive sensing framework is also proposed which incorporates the additional model information to estimate system states from even lesser measurements. Instead of using cumulative imaging-like measurements, such as those used in standard compressive sensing, we use sparse binary matrices. This choice of measurements can be interpreted as randomly sampling only a small subset of dug wells at each time step, instead of sampling the entire grid. Therefore, this framework offers groundwater surveyors a significant reduction in surveying effort without compromising the quality of the survey. © 2013 IEEE.

  10. Nonlinear balance constraints in 3DVAR data assimilation

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    In many applications of 3DVAR, the balance constraints can be considered via two main approaches: weak constraint method which adds penalty terms to the cost function; and proper definition of the background error covariance matrix with non-zero cross-correlation sub-matrices. The weak constraint approach requires determining the weighting matrices of the penalty terms. The background error covariance approach does not require determining those additional weighting matrices. However, it is only applicable to those linear or linearized balance constraints. A novel approach is proposed based on the background error covariance approach by generalizing the so-called Derber-Bouttier formulation. An assimilation experiment of estimating temperature and salinity from the sea surface dynamic height observation is given to illustrate the proposed treatments of nonlinear balance constraints.

  11. Hippocampal closed-loop modeling and implications for seizure stimulation design

    Science.gov (United States)

    Sandler, Roman A.; Song, Dong; Hampson, Robert E.; Deadwyler, Sam A.; Berger, Theodore W.; Marmarelis, Vasilis Z.

    2015-10-01

    Objective. Traditional hippocampal modeling has focused on the series of feedforward synapses known as the trisynaptic pathway. However, feedback connections from CA1 back to the hippocampus through the entorhinal cortex (EC) actually make the hippocampus a closed-loop system. By constructing a functional closed-loop model of the hippocampus, one may learn how both physiological and epileptic oscillations emerge and design efficient neurostimulation patterns to abate such oscillations. Approach. Point process input-output models where estimated from recorded rodent hippocampal data to describe the nonlinear dynamical transformation from CA3 → CA1, via the schaffer-collateral synapse, and CA1 → CA3 via the EC. Each Volterra-like subsystem was composed of linear dynamics (principal dynamic modes) followed by static nonlinearities. The two subsystems were then wired together to produce the full closed-loop model of the hippocampus. Main results. Closed-loop connectivity was found to be necessary for the emergence of theta resonances as seen in recorded data, thus validating the model. The model was then used to identify frequency parameters for the design of neurostimulation patterns to abate seizures. Significance. Deep-brain stimulation (DBS) is a new and promising therapy for intractable seizures. Currently, there is no efficient way to determine optimal frequency parameters for DBS, or even whether periodic or broadband stimuli are optimal. Data-based computational models have the potential to be used as a testbed for designing optimal DBS patterns for individual patients. However, in order for these models to be successful they must incorporate the complex closed-loop structure of the seizure focus. This study serves as a proof-of-concept of using such models to design efficient personalized DBS patterns for epilepsy.

  12. Backpropagation Artificial Neural Network To Detect Hyperthermic Seizures In Rats

    Directory of Open Access Journals (Sweden)

    Rakesh Kumar Sinha

    2003-02-01

    Full Text Available A three-layered feed-forward back-propagation Artificial Neural Network was used to classify the seizure episodes in rats. Seizure patterns were induced by subjecting anesthetized rats to a Biological Oxygen Demand incubator at 45-47ºC for 30 to 60 minutes. Selected fast Fourier transform data of one second epochs of electroencephalogram were used to train and test the network for the classification of seizure and normal patterns. The results indicate that the present network with the architecture of 40-12-1 (input-hidden-output nodes agrees with manual scoring of seizure and normal patterns with a high recognition rate of 98.6%.

  13. Oxcarbazepine versus carbamazepine monotherapy for partial onset seizures

    NARCIS (Netherlands)

    Koch, Marcus W.; Polman, Susanne K. L.

    2009-01-01

    Background Partial onset seizures are often treated with the standard antiepileptic drug carbamazepine. Oxcarbazepine is a newer antiepileptic drug related to carbamazepine that is claimed to be better tolerated. Objectives To compare efficacy and tolerability of carbamazepine and oxcarbazepine mono

  14. Seizure following the Use of the COX-2 Inhibitor Etoricoxib

    Science.gov (United States)

    Arnao, Valentina; Riolo, Marianna; Fierro, Brigida

    2017-01-01

    We describe a case of epileptic seizures occurring after the use of a COX-2 inhibitor. A 61-year-old man was admitted to our department because of a generalized tonic-clonic seizure. EEG showed generalized slowdown of the activity. Neuroimaging and blood samples studies did not evidence alterations, but a careful pharmacological history revealed that the patient had taken the COX-2 inhibitor etoricoxib to treat lumbago few days before the onset of clinical symptoms. No seizures were reported after etoricoxib discontinuation and an EEG resulted to be normal two months after this. Conclusion. Knowing the pharmacological history of a patient is important for understanding the clinical presentation and selecting appropriate treatment. This is, to the best of our knowledge, the first reported case of generalized seizures associated with the use of COX-2 inhibitors. PMID:28210513

  15. Recurrent seizures: An unusual manifestation of vitamin B12 deficiency

    Directory of Open Access Journals (Sweden)

    Kumar S

    2004-01-01

    Full Text Available The present report highlights an unusual presentation of vitamin B12 deficiency— recurrent seizures in a 26-year-old man. His symptoms responded to parenteral vitamin B12 therapy. The relevant literature is reviewed.

  16. Pyridoxine-dependent seizures in an older child.

    Science.gov (United States)

    Yoshikawa, H; Abe, T; Oda, Y

    1999-10-01

    The case of a 12-year-old girl with pyridoxine-dependent seizures is reported. She developed status epilepticus just after birth and ordinary antiepileptic drugs were administered without effect. Her seizures ceased only on the administration of pyridoxine. Status epilepticus associated with the withdrawal of pyridoxine occurred three times, and ceased only after the renewed administration of pyridoxine. She now has mental retardation and mild spastic diplegia. The reported cases of pyridoxine-dependent seizures usually have been neonates and infants. Older patients were not fully investigated, and so we have reviewed these cases of pyridoxine-dependent seizures. As known previously, pediatricians should not forget that pyridoxine should be continued for life.

  17. Nitric Oxide Regulates Neurogenesis in the Hippocampus following Seizures

    Directory of Open Access Journals (Sweden)

    Bruno P. Carreira

    2015-01-01

    Full Text Available Hippocampal neurogenesis is changed by brain injury. When neuroinflammation accompanies injury, activation of resident microglial cells promotes the release of inflammatory cytokines and reactive oxygen/nitrogen species like nitric oxide (NO. In these conditions, NO promotes proliferation of neural stem cells (NSC in the hippocampus. However, little is known about the role of NO in the survival and differentiation of newborn cells in the injured dentate gyrus. Here we investigated the role of NO following seizures in the regulation of proliferation, migration, differentiation, and survival of NSC in the hippocampus using the kainic acid (KA induced seizure mouse model. We show that NO increased the proliferation of NSC and the number of neuroblasts following seizures but was detrimental to the survival of newborn neurons. NO was also required for the maintenance of long-term neuroinflammation. Taken together, our data show that NO positively contributes to the initial stages of neurogenesis following seizures but compromises survival of newborn neurons.

  18. Moonstruck? The effect of the lunar cycle on seizures.

    Science.gov (United States)

    Baxendale, Sallie; Fisher, Jennifer

    2008-10-01

    Recent reports on the effects of the lunar cycle on seizure occurrence have yielded mixed results. If the moon phase is influential, we hypothesized that this would be due to the moon's contribution to nocturnal illumination, rather than its waxing or waning state, and that significant correlations would not be apparent if local cloud cover were controlled for. We found a significant negative correlation between the mean number of seizures and the fraction of the moon illuminated by the sun (rho=-0.09, P<0.05) in 1571 seizures recorded in a dedicated epilepsy inpatient unit over 341 days. This correlation disappeared when we controlled for the local clarity of the night sky, suggesting that it is the brightness of the night and the contribution the moon phase makes to nocturnal luminance, rather than the moon phase per se, that may influence the occurrence of epileptic seizures.

  19. Maternal thyroid dysfunction and risk of seizure in the child

    DEFF Research Database (Denmark)

    Andersen, Stine Linding; Laurberg, Peter; Wu, Chunsen;

    2013-01-01

    Thyroid hormones are essential for brain development, and maternal thyroid disease may affect child neurocognitive development. Some types of seizures may also depend upon early exposure of the developing central nervous system, and we hypothesized that maternal thyroid dysfunction could increase...... the risk of seizure in the child. In a Danish population-based study we included 1,699,693 liveborn singletons, and from the Danish National Hospital Register we obtained information on maternal diagnosis of hyper- or hypothyroidism and neonatal seizure, febrile seizure, and epilepsy in the child. Maternal...... diagnosis of thyroid dysfunction before or after birth of the child was registered in two percent of the singleton births. In adjusted analyses, maternal hyperthyroidism and hypothyroidism first time diagnosed after birth of the child were associated with a significant increased risk of epilepsy...

  20. Ontology and Knowledge Management System on Epilepsy and Epileptic Seizures

    CERN Document Server

    Almeida, Pedro; Sales, Francisco; Nogueira, Ana; Dourado, António

    2010-01-01

    A Knowledge Management System developed for supporting creation, capture, storage and dissemination of information about Epilepsy and Epileptic Seizures is presented. We present an Ontology on Epilepsy and a Web-based prototype that together create the KMS.

  1. Genetics Home Reference: malignant migrating partial seizures of infancy

    Science.gov (United States)

    ... Facebook Share on Twitter Your Guide to Understanding Genetic Conditions Search MENU Toggle navigation Home Page Search ... Conditions Genes Chromosomes & mtDNA Resources Help Me Understand Genetics Home Health Conditions malignant migrating partial seizures of ...

  2. Mapping preictal networks preceding childhood absence seizures using magnetoencephalography.

    Science.gov (United States)

    Jacobs-Brichford, Eliza; Horn, Paul S; Tenney, Jeffrey R

    2014-10-01

    The electrographic hallmark of childhood absence seizures is 3 Hz generalized spike and wave discharges; however, there is likely a focal thalamic or cortical onset that cannot be detected using scalp electroencephalography (EEG). The purpose of this study was to study the earliest preictal changes in children with absence epilepsy. In this report, magnetoencephalography recordings of 44 absence seizures recorded from 12 children with drug-naïve childhood absence seizures were used to perform time frequency analysis and source localization prior to the onset of the seizures. Evidence of preictal magnetoencephalography frequency changes were detected a mean of 694 ms before the initial spike on the EEG. A consistent pattern of focal sources was present in the frontal cortex and thalamus during this preictal period, but source localization occurred synchronously so that independent activity between the 2 structures could not be distinguished.

  3. Acetylcholinesterase activity in the cerebrospinal fluid of dogs with seizures.

    Science.gov (United States)

    Chai, Orit; Sommer, Adi; Zimmerman, Gabriel; Soreq, Hermona; Friedman, Alon; Bdolah-Abram, Tali; Aroch, Itamar; Shamir, Merav H

    2013-10-01

    Recent studies in animal models have focused on the role of cholinergic elements, mainly acetylcholinesterase (AChE) and the 'readthrough' acetylcholinesterase isoform (AChE-R), in seizures. A prospective double-masked study was conducted to assess the activity of AChE and AChE-R in cerebrospinal fluid (CSF) of 26 dogs post-seizure, 28 dogs with intervertebral disc disease (IVDD) and 16 healthy dogs. AChE was also measured in the serum in the post-seizure and IVDD groups. The results showed no significant differences in CSF AChE among the three groups. AChE-R was not detected in any dog and AChE in the serum was similar between groups. This preliminary study provides new information on AChE and AChE-R in the CSF and sera of dogs following naturally-occurring seizures.

  4. Convulsive seizures with a therapeutic dose of isoniazid.

    Science.gov (United States)

    Tsubouchi, Kazuya; Ikematsu, Yuuki; Hashisako, Mikiko; Harada, Eiji; Miyagi, Hiroto; Fujisawa, Nobumitsu

    2014-01-01

    An 86-year-old woman who had been treated for tuberculous peritonitis and pulmonary tuberculosis, exhibited a disturbance of consciousness and tonic-clonic convulsions seven days after the administration of the antituberculous drug isoniazid. As her serum vitamin B6 level was remarkably low, she was diagnosed with convulsive seizures due to vitamin B6 deficiency associated with isoniazid treatment. Seizures refractory to standard anticonvulsant therapy were controlled with the administration of pyridoxine. Most reported cases of isoniazid-induced convulsive seizures occurred as a result of an overdose due to attempted suicide. This report presents a case of convulsive seizures that occurred in association with the short-term administration of a therapeutic dose of isoniazid.

  5. Gelastic seizures and fever originating from a parietal cortical dysplasia

    Directory of Open Access Journals (Sweden)

    Sana Chaouki

    2013-01-01

    Full Text Available Gelastic seizures (GS is an uncommon seizure type characterized by sudden inappropriate attacks of uncontrolled and unmotivated laugh and its diagnostic criteria were elaborated by Gascon. These criteria included stereotypical recurrence of laugh, which is unjustified by the context, associated signs compatible with seizure, and ictal or interictal abnormalities. GS can be cryptogenic or symptomatic of a variety of cerebral lesions, the most common being hypothalamic hamartoma. However, GS associated with other types of cerebral lesions are exceedingly rare. The physiopathologic mechanisms of this type of seizure are still undefined. Two reports have described a non-lesional GS arising from a parietal focus. In this paper, we report the first case of lesional GS associated to the parietal area of the brain in a child and this case has associated fever that is likely an ictal symptom.

  6. Clinical and psychosocial characteristics of children with nonepileptic seizures

    Directory of Open Access Journals (Sweden)

    Chinta Sri

    2008-01-01

    Full Text Available Objective: The aim of this study is to present a comprehensive profile of clinical and psychosocial characteristics of children with psychogenic nonepileptic seizures and to assess the short-term outcome of these patients. Materials and Methods: The subjects were consecutive cases of children with a diagnosis of nonepileptic seizures (N=17, mean age = 10.7 years, S.D. = 1.26 and two groups of control groups matched on age and sex: true seizure group and healthy controls. All the children were recruited from the out-patient services of the Department of Pediatrics of a tertiary care teaching hospital in North India. Detailed history taking and clinical examination was done in the case of every child. A standard 18 channel EEG was done in all the children and a video EEG was done in 12 cases of children with nonepileptic seizures. The Childhood Psychopathology Measurement Schedule (CPMS and Life Events Scale for Indian Children (LESIC were used to measure the children′s emotional and behavioral functioning at home, and the number of life events and the stress associated with these events in the preceding year and the year before that. Short-term outcome was examined three to six months after the diagnosis of nonepileptic seizures was made. Results: Unresponsiveness without marked motor manifestations was the most common "ictal" characteristic of the nonepileptic seizures. Pelvic thrusting, upper and lower limb movements, head movements, and vocalization were observed in less than one-third of the patients. Increased psychosocial stress and significantly higher number of life events in the preceding year were found to characterize children with nonepileptic seizures, as compared to the two control groups. The nonepileptic seizures and true seizures groups had a higher proportion of children with psychopathology scores in the clinically significant maladjustment range, as compared to those in the healthy control group. A majority of the patients

  7. A Spectral Based Forecasting Tool of Epileptic Seizures

    Directory of Open Access Journals (Sweden)

    Hedi Khammari

    2012-05-01

    Full Text Available A new approach to recognize and predict succedent epileptic seizure by using single channel electroencephalogram (EEG analysis is proposed. Spectral analysis of a brain time series of the left frontal FP1-F7 (LF scalp location signal is devoted for seizure prediction and analysis. Important findings showing the presence of preictal spectral changes in studied brain signal are described. Spectral features occurring during the preictal epoch are extracted from the application of sliding spectral windows of raw EEG at different moments in time preceding the seizure onset. The same method is then applied to a couple of Intrinsic Mode Functions (IMF1 and IMF2 of the raw EEG (FP1-F7 decomposed by the algorithm of empirical mode decomposition. The main prediction features are derived from the changes of amplitudes, frequency and the number of spikes which are of diagnostic values. The sliding spectral windows were computed to trace the amplitude changes of higher harmonics during time interval preceding the seizure onset. Choosing different moments in time aims to identify the best prediction time of seizure onset. Obviously an early prediction time is always desirable but the seizure may result from an abrupt change and so the spectral 'signs of an imminent seizure occur during a very short prediction time. From another viewpoint, it may be advantageous to consider a successive prediction times showing the increase of spike numbers and the predominance of certain waves rather than others when approaching seizure onset. The common prediction features extracted from the analysis of FP1-F7 signal for both patients were mainly the increasing number of spikes of low frequency waves namely delta and theta waves.

  8. PREVALENCE OF SEIZURE IN PKU:AN ANALYTIC HISTORICAL STUDY

    Directory of Open Access Journals (Sweden)

    Parvaneh KARIMZADEH

    2010-10-01

    Full Text Available ObjectivePhenylketonuria (PKU is an autosomal recessive metabolic genetic disorder characterized by a deficiency in the hepatic enzyme phenylalanine hydroxylase (PAH which can cause problems with brain development, leading to progressive mental retardation, brain damage, and seizures. In this study we evaluated the frequency of seizure, EEG abnormality and behavioral disorders.Materials & Methods In this case study, 94 PKU children aged between 1 month and 23 years who were referred to Mofid children Hospital between 2009 and 2010 were enrolled.Patients were age and sex matched. Statistical tests were used for comparing patients' data.Results The mean age of patients was 8.4 years. Parents were relatives in 80.9% of the cases (76 patients. Of all, 43% (45 patients had seizure but EEG was abnormal only in 81% of them (35 patients out of 43 patients. Totally, EEG was abnormal in 67% of the cases (63 patients of whom 44.4% (28 patients of 63 patients did not have seizure. Therefore, there was a significant relationship between seizure and EEG abnormality. The phenylalanine level ranged from 8mg/dL to 50mg/dL (mean: 18.88 mg/dL at the time of diagnosis and from 0.4mg/dL to 18mg/dL (mean: 7.37mg/dL at the time of evaluation. On the other hand,we observed abnormal behaviors in all EEG abnormalities and there was a significant relationship between EEG abnormality and behavioral disorders.ConclusionIn our study, the prevalence of seizure was less than EEG abnormality and there was a significant relationship between EEG abnormalities and behavioral disorders in patients with Phenylketonuria regardless of seizure.The authors believe that treatment of EEG abnormalities may lead to the correction of behavioral disorders in these patients.Keywords:Phenylketonuria, Seizure, EEG abnormality, behavioral disorder

  9. Influences on seizure activity in pregnant women with epilepsy

    DEFF Research Database (Denmark)

    Sabers, Anne

    2009-01-01

    This study evaluated whether referral to a specialized epilepsy clinic prior to pregnancy influences seizure activity during pregnancy. In addition, folic acid supplementation prior to pregnancy as a marker of intent to conceive was used to evaluate whether the use of folic acid at the time......). Seizure deterioration was significantly lower in group 1 than in group 2: 9% versus 32% (Pfolic acid supplements was significantly higher in group 1 (P

  10. Brain Mechanisms of Altered Consciousness in Generalised Seizures

    Directory of Open Access Journals (Sweden)

    Stefano Seri

    2011-01-01

    Full Text Available In spite of the inherent difficulties in achieving a biologically meaningful definition of consciousness, recent neurophysiological studies are starting to provide some insight in fundamental mechanisms associated with impaired consciousness in neurological disorders. Generalised seizures are associated with disruption of the default state network, a functional network of discrete brain areas, which include the fronto-parietal cortices. Subcortical contribution through activation of thalamocortical structures, as well as striate nuclei are also crucial to produce impaired consciousness in generalised seizures.

  11. Seizures Related to Vitamin B6 Deficiency in Adults

    OpenAIRE

    2015-01-01

    Vitamin B6 is closely associated with functions of the nervous, immune, and endocrine systems. Its deficiency may result in neurological disorders including convulsions and epileptic encephalopathy. Until today, this has only been reported in infants, children, and critically ill adult patients. We report a case of a 36year-old man with chronic alcoholism who presented with seizures after gastrointestinal disturbance. His seizures persisted even after treatment with antiepileptic drugs, but e...

  12. Somatic overgrowth predisposes to seizures in autism spectrum disorders.

    Directory of Open Access Journals (Sweden)

    Giulia Valvo

    Full Text Available BACKGROUND: Comorbidity of Autism Spectrum Disorders with seizures or abnormal EEG (Autism-Epilepsy Phenotype suggests shared pathomechanisms, and might be a starting point to identify distinct populations within the clinical complexity of the autistic spectrum. In this study, we tried to assess whether distinct subgroups, having distinctive clinical hallmarks, emerge from this comorbid condition. METHODS: Two-hundred and six individuals with idiopathic Autism Spectrum Disorders were subgrouped into three experimental classes depending on the presence of seizures and EEG abnormalities. Neurobehavioral, electroclinical and auxological parameters were investigated to identify differences among groups and features which increase the risk of seizures. Our statistical analyses used ANOVA, post-hoc multiple comparisons, and the Chi-squared test to analyze continuous and categorical variables. A correspondence analysis was also used to decompose significant Chi-squared and reduce variables dimensions. RESULTS: The high percentage of children with seizures (28.2% of our whole cohort and EEG abnormalities (64.1% confirmed that the prevalence of epilepsy in Autism Spectrum Disorders exceeds that of the general population. Seizures were associated with severe intellectual disability, and not with autism severity. Interestingly, tall stature (without macrocephaly was significantly associated with EEG abnormalities or later onset seizures. However, isolated macrocephaly was equally distributed among groups or associated with early onset seizures when accompanied by tall stature. CONCLUSIONS: Tall stature seems to be a phenotypic "biomarker" of susceptibility to EEG abnormalities or late epilepsy in Autism Spectrum Disorders and, when concurring with macrocephaly, predisposes to early onset seizures. Growth pattern might act as an endophenotypic marker in Autism-Epilepsy comorbidity, delineating distinct pathophysiological subtypes and addressing personalized

  13. Acute encephalopathy with biphasic seizures and late reduced diffusion

    Directory of Open Access Journals (Sweden)

    Saroj S Yadav

    2013-01-01

    Full Text Available Acute encephalopathy with biphasic seizures and reduced diffusion (AESD is a syndrome of encephalopathy characterized by biphasic seizures and altered consciousness in the acute stage followed in the subacute stage by restricted diffusion in the subcortical white matter on magnetic resonance imaging. The etiology of AESD has been attributed to viral infection like influenza A and human herpes virus 6. The exact pathogenesis of AESD is uncertain. Here we report a case of AESD, diagnosed based on clinicoradiological correlation.

  14. Global Assimilation of EOS-Aura Data as a Means of Mapping Ozone Distribution in the Lower Stratosphere and Troposphere

    Science.gov (United States)

    Wargan, Krzysztof; Olsen, M.; Douglass, A.; Witte, J.; Strahan, S.; Livesey, N.

    2012-01-01

    Ozone in the lower stratosphere and the troposphere plays an important role in forcing the climate. However, the global ozone distribution in this region is not well known because of the sparse distribution of in-situ data and the poor sensitivity of satellite based observations to the lowermost of the atmosphere. The Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) instruments on EOS-Aura provide information on the total ozone column and the stratospheric ozone profile. This data has been assimilated into NASA s Global Earth Observing System, Version 5 (GEOS-5) data assimilation system (DAS). We will discuss the results of assimilating three years of OMI and MLS data into GEOS-5. This data was assimilated alongside meteorological observations from both conventional sources and satellite instruments. Previous studies have shown that combining observations from these instruments through the Trajectory Tropospheric Ozone Residual methodology (TTOR) or using data assimilation can yield useful, yet low biased, estimates of the tropospheric ozone budget. We show that the assimilated ozone fields in this updated version of GEOS-5 exhibit an excellent agreement with ozone sonde and High Resolution Dynamics Limb Sounder (HIRDLS) data in the lower stratosphere in terms of spatial and temporal variability as well as integrated ozone abundances. Good representation of small-scale vertical features follows from combining the MLS data with the assimilated meteorological fields. We then demonstrate how this information can be used to calculate the Stratosphere - Troposphere Exchange of ozone and its contribution to the tropospheric ozone column in GEOS-5. Evaluations of tropospheric ozone distributions from the assimilation will be made by comparisons with sonde and other in-situ observations.

  15. Treatment of febrile seizures with intermittent clobazam Tratamento de convuslsões febris com clobazam intermitente

    OpenAIRE

    1997-01-01

    Fifty children, 24 female and 26 male, with ages varying from 6 to 72 months (mean=23.7 m.) that experienced at least one febrile seizure (FS) entered a prospective study of intermittent therapy with clobazam. Cases with severe neurological abnormalities, progressive neurological disease, afebrile seizures, symptomatic seizures of other nature, or seizures during a central nervous system infection were excluded. Seizures were of the simple type in 25 patients, complex in 20 and unclassified i...

  16. Neonatal seizures-part 1: Not everything that jerks, stiffens and shakes is a fit.

    Science.gov (United States)

    Hart, Anthony R; Pilling, Elizabeth L; Alix, James J P

    2015-08-01

    The neonatal period is the most frequent time of life to have epileptic seizures. However, neonates can also exhibit unusual movements that are not epileptic seizures. Differentiating between epileptic and non-epileptic movements can be difficult. Many neonatal seizures exhibit few or no clinical features at all. This article is for the benefit of paediatric trainees and reviews the published evidence on which neonatal movements are likely to be epileptic seizures and which are not. We also discuss epileptic seizure classification.

  17. Effect of Antiepileptic Drugs for Acute and Chronic Seizures in Children with Encephalitis

    OpenAIRE

    Kuang-Lin Lin; Jainn-Jim Lin; Shao-Hsuan Hsia; Min-Liang Chou; Po-Cheng Hung; Huei-Shyong Wang

    2015-01-01

    Background Encephalitis presents with seizures in the acute phase and increases the risk of late unprovoked seizures and epilepsy. This study aimed to evaluate the effect of antiepileptic drugs in pediatric patients with acute seizures due to encephalitis and epilepsy. Patients and Methods Cases of acute pediatric encephalitis between January 2000 and December 2010 were reviewed. Clinical data, including onset at age, seizure type, seizure frequency, effects of antiepileptic drugs, and progno...

  18. The quantitative measurement of consciousness during epileptic seizures.

    Science.gov (United States)

    Nani, Andrea; Cavanna, Andrea E

    2014-01-01

    The assessment of consciousness is a fundamental element in the classification of epileptic seizures. It is, therefore, of great importance for clinical practice to develop instruments that enable an accurate and reliable measurement of the alteration of consciousness during seizures. Over the last few years, three psychometric scales have been specifically proposed to measure ictal consciousness: the Ictal Consciousness Inventory (ICI), the Consciousness Seizure Scale (CSS), and the Responsiveness in Epilepsy Scale--versions I and II (RES-I and RES-II). The ICI is a self-report psychometric instrument which retrospectively assesses ictal consciousness along the dimensions of the level/arousal and contents/awareness. The CSS has been used by clinicians to quantify the impairment of consciousness in order to establish correlations with the brain mechanisms underlying alterations of consciousness during temporal lobe seizures. The most recently developed observer-rated instrument is the RES-I, which has been used to assess responsiveness during epileptic seizures in patients undergoing video-EEG. The implementation of standardized psychometric tools for the assessment of ictal consciousness can complement clinical observations and contribute to improve accuracy in seizure classification.

  19. Hyperspherical Manifold for EEG Signals of Epileptic Seizures

    Directory of Open Access Journals (Sweden)

    Tahir Ahmad

    2012-01-01

    Full Text Available The mathematical modelling of EEG signals of epileptic seizures presents a challenge as seizure data is erratic, often with no visible trend. Limitations in existing models indicate a need for a generalized model that can be used to analyze seizures without the need for apriori information, whilst minimizing the loss of signal data due to smoothing. This paper utilizes measure theory to design a discrete probability measure that reformats EEG data without altering its geometric structure. An analysis of EEG data from three patients experiencing epileptic seizures is made using the developed measure, resulting in successful identification of increased potential difference in portions of the brain that correspond to physical symptoms demonstrated by the patients. A mapping then is devised to transport the measure data onto the surface of a high-dimensional manifold, enabling the analysis of seizures using directional statistics and manifold theory. The subset of seizure signals on the manifold is shown to be a topological space, verifying Ahmad's approach to use topological modelling.

  20. INTERMITTENT CLONAZEPAM IN THE PREVENTION OF RECURRENT FEBRILE SEIZURES

    Directory of Open Access Journals (Sweden)

    BAJOGHLI Shirin MD

    2010-09-01

    Full Text Available ObjectiveTo evaluate the efficacy and common side effects of intermittent clonazepamin febrile seizures.Materials & MethodsThis study was an experimental trial designed to determine the efficacy ofintermittent clonazepam in febrile seizures .Thirty patients with an age rangeof 6 months to 5 years (60% male, 40% female were studied. Children with ahistory of psychomotor delay, abnormal neurological examination, a history ofantiepileptic drug consumption, and afebrile seizures were excluded from thestudy. Patients received a single dose of prophylactic Clonazepam (0.05 mg/kg/day on the first day of febrile illness and twice daily during the course of fever.An antipyretic medication (Acetaminophen was advised if fever exceeded38oC. Patients were followed up for one year after the study inclusion date.ResultsThree patients were excluded from study since they didnot follow the tritmentand three patients experienced afebrile seizures. Twenty four patients had 162febrile episodes during the course of the study and all patients were seizure-freeafter 1 year.ConclusionClonazepam was 100% effective but lethargy and ataxia were common sideeffects in patients. Fortunately, their parents continued treatment because theyhad prior awareness of the possible side effects of clonazepam. Clonazepam isefficacious as an intermittent therapy for febrile seizures if parents are informedof its side effects.

  1. Risk factors for developing seizures after a stroke.

    Science.gov (United States)

    Lancman, M E; Golimstok, A; Norscini, J; Granillo, R

    1993-01-01

    We evaluated development of seizures in 219 consecutive patients who had ischemic or hemorrhagic stroke. Subjects with transitory ischemic attacks, subarachnoid, subdural, and epidural hemorrhages or those with previous history of epilepsy were excluded. Mean follow-up time was 11.5 months (range 1-72 months). Twenty-two of 219 stroke patients (10.04%) had seizures. Twelve (54.55%) were of early onset (< 1 month after the stroke), and 10 (45.45%) were of late onset. No statistically significant differences were evident between the early- and late-onset seizure group in comparisons of type of stroke, localization, and size of the lesion. Six of 22 patients (27%) had seizure recurrence. Seizures developed in (a) 13 of 183 patients with ischemic stroke (7.1%) and 9 of 36 patients with hemorrhagic stroke (25%) (p = 0.01); (b) 16 of 93 patients with cortical lesions (17%) and 6 of 126 patients with subcortical lesions (4.7%) (p = 0.01); and (c) 14 of 66 patients with a lesion comprising more than one lobe (21.2%) and 8 of 153 patients with a lesion comprising less than one lobe (5.2%) (p < 0.01). We conclude that patients with hemorrhagic stroke, cortical lesions, and lesions involving more than one lobe are at higher risk of developing seizures.

  2. Seizure Prediction: Science Fiction or Soon to Become Reality?

    Science.gov (United States)

    Freestone, Dean R; Karoly, Philippa J; Peterson, Andre D H; Kuhlmann, Levin; Lai, Alan; Goodarzy, Farhad; Cook, Mark J

    2015-11-01

    This review highlights recent developments in the field of epileptic seizure prediction. We argue that seizure prediction is possible; however, most previous attempts have used data with an insufficient amount of information to solve the problem. The review discusses four methods for gaining more information above standard clinical electrophysiological recordings. We first discuss developments in obtaining long-term data that enables better characterisation of signal features and trends. Then, we discuss the usage of electrical stimulation to probe neural circuits to obtain robust information regarding excitability. Following this, we present a review of developments in high-resolution micro-electrode technologies that enable neuroimaging across spatial scales. Finally, we present recent results from data-driven model-based analyses, which enable imaging of seizure generating mechanisms from clinical electrophysiological measurements. It is foreseeable that the field of seizure prediction will shift focus to a more probabilistic forecasting approach leading to improvements in the quality of life for the millions of people who suffer uncontrolled seizures. However, a missing piece of the puzzle is devices to acquire long-term high-quality data. When this void is filled, seizure prediction will become a reality.

  3. MR Imaging Findings in Children with First Recognized Seizure

    Science.gov (United States)

    Kalnin, Andrew J.; Fastenau, Philip S.; deGrauw, Ton J.; Musick, Beverly S.; Perkins, Susan M.; Johnson, Cynthia S.; Mathews, Vincent P.; Egelhoff, John C.; Dunn, David W.; Austin, Joan K.

    2008-01-01

    This study characterized structural abnormalities associated with onset of seizures in children using MRI and a standardized classification system in a large prospective cohort. A total of 281 children aged 6 to 14 years completed an MRI within six months of their first recognized seizure. Most MRI examinations were performed with a standardized, dedicated seizure protocol, and all were scored using a standard scoring system. At least one MRI abnormality was identified in 87 of the 281 (31%) of children with first recognized seizure. Two or more abnormalities were identified in 34 (12%). The most common abnormalities were ventricular enlargement (51%), leukomalacia/gliosis (23%), gray matter lesions such as heterotopias and cortical dysplasia (12%), volume loss (12%), various other white matter lesions (9%), and encephalomalacia (6%). Abnormalities defined as significant, or potentially related to seizures, occurred in 40 (14%). Temporal lobe and hippocampal abnormalities were detected at a higher frequency than in previous studies (13/87). Use of MRI and a standardized reliable and valid scoring system demonstrated a higher rate of abnormal findings than previous investigations, including findings that might have been considered incidental in the past. Practice parameters may need to be revised to expand the definition of significant abnormalities and to support wider use of MRI in children with newly diagnosed seizures. PMID:19027586

  4. Approach To The First Unprovoked Seizure- PART I

    Directory of Open Access Journals (Sweden)

    Mohammad GHOFRANI

    2013-08-01

    Full Text Available How to Cite This Article: Ghofrani M. Approach To The First Unprovoked Seizure- PART I. Iran J Child Neurol. 2013 Summer; 7(3: 1- 5. The approach to a child who has experienced a first unprovoked generalized tonic-clonic seizure is challenging and at the same time controversial.How to establish the diagnosis, ways and means of investigation and whether treatment is appropriate, are different aspects of this subject.In this writing the above mentioned matters are discussed.References1. Bluvstein JS, Moshe SL. First unprovoked seizure CurrentManagement in child Neurology, third ed. 2005.P.89-92.2. Hirtz D, Berg A, Bettis D, et al. Practice Parameter: treatment of the child with a first unprovoked seizure. American Academy of Neurology 2003;60:166-175.3. Verity GM, Ross EN, Golding J. Epilepsy in the first ten years of life: finding of the child health and education study. Br Med J 1992;305:857-861.4. Camfiled CS, Camfield PB, Gordon K, et al. Incidence of epilepsy in childhood and adolescence: A populationbasedstudy in Nova Scotia from 1977 to 1985. Epilepsia 1996;37:19-23.5. Hauser W, Annegers J, Kurland L. Incidence of epilepsy and unprovoked seizure in Rochester, Minnisota, 1935- 1984. Epilepsia 1993;34:453-468.6. Jallon P, Goumaz M, Haenggeli G, Morabia A. Incidenceof first epileptic seizure in the canton of Geneve Switzerland. Epilepsia 1997;38:547-552.7. Camfiled PR, Camfiled CS. Pediatric Epilepsy: An overview. Swaiman’s pediatric Neurology, 5th ed, 2012. P.703-710.8. Gowers WB. Epilepsy and other chronic convulsive diseases; their causes, symptoms and treatment. London: J&A Churchill,1881. P.242.9. Goddard GV, Mc Intyre DC, Leech CK. A permanent change in brain function resulting from daily electrical stimulation- Exp Neural 1969;25:295-330.10. Berg AT, Shinnar S. Do seizures beget seizure? An assessment of the clinical evidence in human. J ClinicalNeurophysiol 1993: 14: 102-110.11. Wasterlain CG. Recurrent seizures in developing brain

  5. Combination anticonvulsant treatment of soman-induced seizures.

    Science.gov (United States)

    Koplovitz, I; Schulz, S; Shutz, M; Railer, R; Macalalag, R; Schons, M; McDonough, J

    2001-12-01

    These studies investigated the effectiveness of combination treatment with a benzodiazepine and an anticholinergic drug against soman-induced seizures. The anticholinergic drugs considered were biperiden, scopolamine, trihexaphenidyl, and procyclidine; the benzodiazepines were diazepam and midazolam. Male guinea pigs were implanted surgically with cortical screw electrodes. Electrocorticograms were displayed continually and recorded on a computerized electroencephalographic system. Pyridostigmine (0.026 mg x kg(-1), i.m.) was injected as a pretreatment to inhibit red blood cell acetylcholinesterase by 30-40%. Thirty minutes after pyridostigmine, 2 x LD50 (56 microg x kg(-1)) of soman was injected s.c., followed 1 min later by i.m. treatment with atropine (2 mg x kg(-1)) + 2-PAM (25 mg x kg(-1)). Electrographic seizures occurred in all animals. Anticonvulsant treatment combinations were administered i.m. at 5 or 40 min after seizure onset. Treatment consisted of diazepam or midazolam plus one of the above-mentioned anticholinergic drugs. All doses of the treatment compounds exhibited little or no antiseizure efficacy when given individually. The combination of a benzodiazepine and an anticholinergic drug was effective in terminating soman-induced seizure, whether given 5 or 40 min after seizure onset. The results suggest a strong synergistic effect of combining benzodiazepines with centrally active anticholinergic drugs and support the concept of using an adjunct to supplement diazepam for the treatment of nerve-agent-induced seizures.

  6. ROLE OF MAGNETIC RESONANCE IMAGING BRAIN IN EVALUATION OF SEIZURES

    Directory of Open Access Journals (Sweden)

    Athira

    2015-09-01

    Full Text Available BACKGROUND AND OBJECTIVES: In patients with seizures a dedicated MRI protocol is a useful tool in the detection of an epileptogenic focus, including congenital, neoplastic and degenerative. Resection of these lesions can lead to seizure freedom in most patients. In this context, a prospective study was conducted to evaluate the etiology of seizures using MRI brain. METHODOLOGY: 120 patients presenting with seizures, above the age of 2years, referred to the Department of Radio - diagnosis were included in this study. RESULTS: In this study, the MR examination revealed pathological findi ngs i n 32.50% (39 out of 120 patients which includes: mesial temporal sclerosis - 14.2% (17, cerebral infarct with gliosis - 6.6% (8, meningioma - 2.5% (3, hypoxic ischemic encephalopathy - 1.6% (2, cortical dysplasia - 1.6% (2, tuberous sclerosis - 11.6% (2, nodula r heterotopias - 0.83% (1, neurocysticercosis - 0.83% (1%, metastasis - 0.83% (1, Dyke Davidoff Maison syndrome - 0.83% (1 and Arnold Chiari Malformation 0.83% (1. CONCLUSION: This study concludes that MR imaging plays a pivotal role in the evaluation of pati ents with seizures using a dedicated MRI seizure protocol to confirm or rule out any organic or developmental lesions. The most common abnormality seen in this study was mesial temporal sclerosis.

  7. Recognition and management of seizures in children in emergency departments.

    Science.gov (United States)

    Caplan, Edward; Dey, Indranil; Scammell, Andrea; Burnage, Katy; Paul, Siba Prosad

    2016-09-01

    Seizure is defined as 'a sudden surge of electrical activity in the brain, which usually affects how a person appears or acts for a short time'. Children who have experienced seizures commonly present to emergency departments (EDs), and detailed history taking will usually help differentiate between epileptic and non-epileptic events. ED nurses are often the first health professionals to manage children with seizures, and this is best done by following the ABCDE approach. Treatment involves termination of seizures with anticonvulsants, and children may need other symptomatic management. Seizures in children can be an extremely distressing experience for parents, who should be supported and kept informed by experienced ED nurses. Nurses also play a vital role in educating parents on correct administration of anticonvulsants and safety advice. This article discusses the aetiology, clinical presentation, diagnosis and management of children with seizures, with particular emphasis on epilepsy. It includes two reflective case studies to highlight the challenges faced by healthcare professionals managing children who present with convulsions.

  8. S100B proteins in febrile seizures

    DEFF Research Database (Denmark)

    Mikkonen, Kirsi; Pekkala, Niina; Pokka, Tytti

    2011-01-01

    S100B protein concentrations correlate with the severity and outcome of brain damage after brain injuries, and have been shown to be markers of blood-brain barrier damage. In children elevated S100B values are seen as a marker of damage to astrocytes even after mild head injuries. S100B proteins...... may also give an indication of an ongoing pathological process in the brain with respect to febrile seizures (FS) and the likelihood of their recurrence. To evaluate this, we measured S100B protein concentrations in serum and cerebrospinal fluid from 103 children after their first FS. 33 children...... with acute infection without FS served as controls for the serum concentrations. In the FS patients the mean S100B concentration in the cerebrospinal fluid samples was 0.21μg/L and that in the serum samples 0.12μg/L. The mean serum concentration in the controls was 0.11μg/L (difference 0.01μg/L, 95...

  9. S100B proteins in febrile seizures

    DEFF Research Database (Denmark)

    Mikkonen, Kirsi; Pekkala, Niina; Pokka, Tytti

    2011-01-01

    S100B protein concentrations correlate with the severity and outcome of brain damage after brain injuries, and have been shown to be markers of blood-brain barrier damage. In children elevated S100B values are seen as a marker of damage to astrocytes even after mild head injuries. S100B proteins...... may also give an indication of an ongoing pathological process in the brain with respect to febrile seizures (FS) and the likelihood of their recurrence. To evaluate this, we measured S100B protein concentrations in serum and cerebrospinal fluid from 103 children after their first FS. 33 children...... with acute infection without FS served as controls for the serum concentrations. In the FS patients the mean S100B concentration in the cerebrospinal fluid samples was 0.21µg/L and that in the serum samples 0.12µg/L. The mean serum concentration in the controls was 0.11µg/L (difference 0.01µg/L, 95...

  10. Impact of SLA assimilation in the Sicily Channel Regional Model: model skills and mesoscale features

    Directory of Open Access Journals (Sweden)

    A. Olita

    2012-07-01

    Full Text Available The impact of the assimilation of MyOcean sea level anomalies along-track data on the analyses of the Sicily Channel Regional Model was studied. The numerical model has a resolution of 1/32° degrees and is capable to reproduce mesoscale and sub-mesoscale features. The impact of the SLA assimilation is studied by comparing a simulation (SIM, which does not assimilate data with an analysis (AN assimilating SLA along-track multi-mission data produced in the framework of MyOcean project. The quality of the analysis was evaluated by computing RMSE of the misfits between analysis background and observations (sea level before assimilation. A qualitative evaluation of the ability of the analyses to reproduce mesoscale structures is accomplished by comparing model results with ocean colour and SST satellite data, able to detect such features on the ocean surface. CTD profiles allowed to evaluate the impact of the SLA assimilation along the water column. We found a significant improvement for AN solution in terms of SLA RMSE with respect to SIM (the averaged RMSE of AN SLA misfits over 2 years is about 0.5 cm smaller than SIM. Comparison with CTD data shows a questionable improvement produced by the assimilation process in terms of vertical features: AN is better in temperature while for salinity it gets worse than SIM at the surface. This suggests that a better a-priori description of the vertical error covariances would be desirable. The qualitative comparison of simulation and analyses with synoptic satellite independent data proves that SLA assimilation allows to correctly reproduce some dynamical features (above all the circulation in the Ionian portion of the domain and mesoscale structures otherwise misplaced or neglected by SIM. Such mesoscale changes also infer that the eddy momentum fluxes (i.e. Reynolds stresses show major changes in the Ionian area. Changes in Reynolds stresses reflect a different pumping of eastward momentum from the eddy to

  11. Helioseismic Data Assimilation in Solar Dynamo Models

    CERN Document Server

    Muñoz-Jaramillo, Andrés; Martens, Petrus C H

    2008-01-01

    An essential ingredient in kinematic dynamo models is the velocity field within the solar convection zone. In particular, the differential rotation is now well constrained by helioseismic observations. Helioseismology also gives us information about the depth-dependence of the meridional circulation in the near-surface layers. The typical velocity inputs used in solar dynamo models, however, continue to be an analytic fit to the observed differential rotation and a theoretically constructed meridional flow profile that matches only the peak flow speed at the surface. Here we take the first steps towards realistic helioseismic data assimilation, by presenting methodologies for constructing differential rotation and meridional circulation profiles that more closely conform to the observational constraints currently available. We also present simulations driven by the assimilated rotation and four plausible profiles for the internal meridional circulation -- all of which match the helioseismically inferred near-...

  12. Monitoring groundwater drought with GRACE data assimilation

    Science.gov (United States)

    Li, B.; Rodell, M.; Beaudoing, H. K.; Getirana, A.; Zaitchik, B. F.

    2015-12-01

    Groundwater drought is a distinct class of drought, not a sub-class of meteorological, agricultural and hydrological drought and has profound impacts on natural environments and societies. Due to a deficiency of in situ measurements, we developed a groundwater drought indicator using groundwater change estimates derived by assimilating GRACE derived terrestrial water storage (TWS) anomalies into the NASA Catchment land surface model. Data assimilation enables spatial and temporal downscaling of coarse GRACE TWS observations (monthly and ~150,000 km2 effective spatial resolution) and extrapolation to near-real time. In this talk, we will present our latest progress on using GRACE satellite data for groundwater drought monitoring in the U.S. and globally. Characteristics of this groundwater drought indicator will be discussed, including its relationship with other types of drought and how they are influenced by model physics and climate conditions. Results are evaluated using in situ groundwater observations.

  13. In-depth performance analysis of an EEG based neonatal seizure detection algorithm

    Science.gov (United States)

    Mathieson, S.; Rennie, J.; Livingstone, V.; Temko, A.; Low, E.; Pressler, R.M.; Boylan, G.B.

    2016-01-01

    Objective To describe a novel neurophysiology based performance analysis of automated seizure detection algorithms for neonatal EEG to characterize features of detected and non-detected seizures and causes of false detections to identify areas for algorithmic improvement. Methods EEGs of 20 term neonates were recorded (10 seizure, 10 non-seizure). Seizures were annotated by an expert and characterized using a novel set of 10 criteria. ANSeR seizure detection algorithm (SDA) seizure annotations were compared to the expert to derive detected and non-detected seizures at three SDA sensitivity thresholds. Differences in seizure characteristics between groups were compared using univariate and multivariate analysis. False detections were characterized. Results The expert detected 421 seizures. The SDA at thresholds 0.4, 0.5, 0.6 detected 60%, 54% and 45% of seizures. At all thresholds, multivariate analyses demonstrated that the odds of detecting seizure increased with 4 criteria: seizure amplitude, duration, rhythmicity and number of EEG channels involved at seizure peak. Major causes of false detections included respiration and sweat artefacts or a highly rhythmic background, often during intermediate sleep. Conclusion This rigorous analysis allows estimation of how key seizure features are exploited by SDAs. Significance This study resulted in a beta version of ANSeR with significantly improved performance. PMID:27072097

  14. CSF glutamate/GABA concentrations in pyridoxine-dependent seizures: etiology of pyridoxine-dependent seizures and the mechanisms of pyridoxine action in seizure control.

    Science.gov (United States)

    Goto, T; Matsuo, N; Takahashi, T

    2001-03-01

    Several lines of evidence suggest that the binding affinity of glutamate decarboxylase (GAD) to the active form of pyridoxine is low in cases of pyridoxine-dependent seizures (PDS) and that a quantitative imbalance between excitatory (i.e. glutamate) and inhibitory (i.e. gamma-aminobutyric acid, GABA) neurotransmitters could cause refractory seizures. However, inconsistent findings with GAD insufficiency have been reported in PDS. We report a case of PDS that is not accompanied by an elevated cerebrospinal fluid (CSF) glutamate concentration. Intravenous pyridoxine phosphate terminated generalized seizures which were otherwise refractory to conventional anti-epileptic medicines. No seizure occurred once oral pyridoxine (13.5 mg/kg per day) was started in combination with phenobarbital sodium (PB, 3.7 mg/kg per day). The electroencephalogram (EEG) normalized approximately 8 months after pyridoxine was started. The patient is gradually acquiring developmental milestones during the 15 months follow-up period. The CSF glutamate and GABA concentrations were determined on three separate occasions: (1) during status epilepticus; (2) during a seizure-free period with administration of pyridoxine and PB; and (3) 6 days after suspension of pyridoxine and PB and immediately before a convulsion. The CSF glutamate level was below the sensitivity of detection (pyridoxine supplementation, were within the normal range. We suggest that (1) PDS is not a discrete disease of single etiology in that insufficient activation of GAD may not account for seizure susceptibility in all cases and (2) mechanism(s) of anti-convulsive effect of pyridoxine, at least in some cases, may be independent of GAD activation.

  15. Augmenting an operational forecasting system for the North and Baltic Seas by in situ T and S data assimilation

    Science.gov (United States)

    Losa, Svetlana; Danilov, Sergey; Schröter, Jens; Nerger, Lars; Maßmann, Silvia; Janssen, Frank

    2014-05-01

    In order to improve the hydrography forecast of the North and Baltic Seas, the operational circulation model of the German Federal Maritime and Hydrographic Agency (BSH) has been augmented by a data assimilation (DA) system. The DA system has been developed based on the Singular Evolution Interpolated Kalman (SEIK) filter algorithm (Pham, 1998) coded within the Parallel Data Assimilation Framework (Nerger et al., 2004, Nerger and Hiller, 2012). Previously the only data assimilated were sea surface temperature (SST) measurements obtained with the Advanced Very High Resolution Radiometer (AVHRR) aboard NOAA's polar orbiting satellites. While the quality of the forecast has been significantly improved by assimilating the satellite data (Losa et al., 2012, Losa et al., 2014), assimilation of in situ observational temperature (T) and salinity (S) profiles has allowed for further improvement. Assimilating MARNET time series and CTD and Scanfish measurements, however, required a careful calibration of the DA system with respect to local analysis. The study addresses the problem of the local SEIK analysis accounting for the data within a certain radius. The localisation radius is considered spatially variable and dependent on the system local dynamics. As such, we define the radius of the data influence based on the energy ratio of the baroclinic and barotropic flows. D. T. Pham, J. Verron, L. Gourdeau, 1998. Singular evolutive Kalman filters for data assimilation in oceanography, C. R. Acad. Sci. Paris, Earth and Planetary Sciences, 326, 255-260. L. Nerger, W. Hiller, J. Schröter, 2004. PDAF - The Parallel Data Assimilation Framework: Experiences with Kalman Filtering, In: Zwieflhofer, W., Mozdzynski, G. (Eds.), Use of high performance computing in meteorology: proceedings of the Eleventh ECMWF Workshop on the Use of High Performance Computing in Meteorology. Singapore: World Scientific, Reading, UK, 63-83. L. Nerger, W. Hiller, 2012. Software for Ensemble-based Data

  16. Ocean Data Assimilation for Coupled Models

    Science.gov (United States)

    2016-06-07

    MODAS) developed at NRL Stennis, CODA now assimilates altimeter sea surface height ( SSH ) data, in the form of MODAS synthetic temperature and...The residual errors are time and space dependent and residual errors are at a minimum where the relationship between SSH , SST and temperature at depth...is well-defined (e.g. western boundary currents). In a CODA analysis, residual errors are combined with errors in the SST and SSH predictor fields to

  17. Variational Data Assimilation for the Global Ocean

    Science.gov (United States)

    2013-01-01

    a mixture of fore- cast and analysis error. Forecast errors result from initial condition, model, and atmospheric forcing deficiencies, while...are not lost . Second, when ensemble variances are imperfect the optimal error variance estimate is a linear combination of a climatological...Res 105:16803-16821 Martin MJ, Hines A, Bell MJ (2007) Data assimilation in the FOAM operational short-range ocean forecasting system: a

  18. Opinion formation and bi-polarization with biased assimilation and homophily

    Science.gov (United States)

    Fu, Guiyuan; Zhang, Weidong

    2016-02-01

    An agent-based model incorporating biased assimilation is proposed in this paper to investigate opinion dynamics over a connected social network. The opinion of each agent is represented by a sequence of arguments, and it evolves through the interactions between agents. The probability that one agent chooses another to communicate depends on the similarity of their opinions. During every interaction, interacting agents exchange the argument randomly selected from the corresponding arguments sequence. Theoretical analysis reveals that this model results in consensus on either extreme positive opinion or extreme negative opinion, or generates bi-polarization. Numerical simulations are carried out to investigate the dynamics of the model over different networks. Results are obtained in terms of the effect of homophily, biased assimilation and network topology on opinion formation.

  19. Data Assimilation in a Solar Dynamo Model Using Ensemble Kalman Filters: Sensitivity and Robustness in Reconstruction of Meridional Flow Speed

    Science.gov (United States)

    Dikpati, Mausumi; Anderson, Jeffrey L.; Mitra, Dhrubaditya

    2016-09-01

    We implement an Ensemble Kalman Filter procedure using the Data Assimilation Research Testbed for assimilating “synthetic” meridional flow-speed data in a Babcock-Leighton-type flux-transport solar dynamo model. By performing several “observing system simulation experiments,” we reconstruct time variation in meridional flow speed and analyze sensitivity and robustness of reconstruction. Using 192 ensemble members including 10 observations, each with 4% error, we find that flow speed is reconstructed best if observations of near-surface poloidal fields from low latitudes and tachocline toroidal fields from midlatitudes are assimilated. If observations include a mixture of poloidal and toroidal fields from different latitude locations, reconstruction is reasonably good for ≤slant 40 % error in low-latitude data, even if observational error in polar region data becomes 200%, but deteriorates when observational error increases in low- and midlatitude data. Solar polar region observations are known to contain larger errors than those in low latitudes; our forward operator (a flux-transport dynamo model here) can sustain larger errors in polar region data, but is more sensitive to errors in low-latitude data. An optimal reconstruction is obtained if an assimilation interval of 15 days is used; 10- and 20-day assimilation intervals also give reasonably good results. Assimilation intervals \\lt 5 days do not produce faithful reconstructions of flow speed, because the system requires a minimum time to develop dynamics to respond to flow variations. Reconstruction also deteriorates if an assimilation interval \\gt 45 days is used, because the system’s inherent memory interferes with its short-term dynamics during a substantially long run without updating.

  20. Targeting iron assimilation to develop new antibacterials

    Science.gov (United States)

    Foley, Timothy L.; Simeonov, Anton

    2012-01-01

    Introduction Since the first application of antibiotics to treat bacterial infections, the development and spread of resistance has been a persistent threat. An ever-evolving pipeline of next-generation therapeutics is required for modern medicine to remain one step ahead of pathogens. Areas covered in this review This review describes recent efforts to develop drugs that interrupt the assimilation of iron by bacteria, a process that is vital to cellular homeostasis and is not currently targeted by antibiotics used in the clinic. We cover the mechanisms through which bacteria acquire iron for their environment and detail efforts to intervene in these processes with small molecule inhibitors that target key steps in these pathways, with a special emphasis on recent advances published during the 2010–2012 period. Expert Opinion For decades, the routes used by bacteria to assimilate iron from host and environmental settings have been the subject of intense study. While numerous investigations have identified inhibitors of these pathways, many have stopped short of translating the in vitro results to in vivo proof of concept experiments. Extension of preliminary findings in this manner to validate the clinical potential of iron assimilation pathways for therapeutic development will significantly increase the impact of the field. PMID:22812521