Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 32 for “"High-frequency oscillations"”.
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Investigation of High Frequency Oscillations in Epilepsy Using Computational Intelligence
… delineation of the seizure onset zone (SOZ). High frequency oscillations (HFOs, 80 - 500 Hz) are proposed as putative biomarkers in epilepsy with their potentials of identifying the SOZ, either by augmenting or replacing the current preoperative evaluation modality which requires detained …
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Physiological High-Frequency Oscillations in Scalp EEGs Change During Brain Maturation
High-frequency oscillations (HFOs), occurring between 80-1000 Hz, were first identified only three decades ago. Since then, physiological HFOs have been implicated in learning, memory and motor function, while epileptic HFOs have been associated with epileptogenic tissue. Many studies have shown …
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UNSUPERVISED CLASSIFICATION OF HIGH-FREQUENCY OSCILLATIONS IN NEOCORTICAL EPILEPSY AND CONTROL PATIENTS
… for generating their seizures can be localized. High-frequency (100-500 Hz) field-potential oscillations (HFOs) are emerging as a candidate biomarker for epileptogenic networks, but quantitative HFO studies are hampered by selection bias arising out of the need to reduce large volumes of data in …
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Optogenetic investigation of normal and pathological rhythms in the hippocampal formation
… and properties of two oscillatory patterns, the high frequency sharp-wave ripple oscillation thought to be involved in the long term storage of memories, and the high amplitude pathological oscillations associated with epileptic seizure. Hippocampal sharp-wave ripples are observed in CA1 during …
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An Adaptive Approach to Gibbs’ Phenomenon
… on them. The resulting reconstructions have high frequency oscillations near the jumps making the reconstructions far from being accurate. To get rid of the unwanted oscillations, we used the Lanczos sigma factor to adjust the Fourier series and we came across three cases. Out of the three, …
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Inverse modelling and inverse simulation for system engineering and control applications
… algorithm suffer from numerical problems such as high-frequency oscillations and can have limitations in their applicability due to problems of input-output redundancy. The existing approaches may also show a phenomenon which has been termed “constraint oscillations” which leads to low-frequency …
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The Influence of Aging and Parkinson’s Disease on Neural Oscillations Associated with Memory Consolidation
… activity occurs crossregional synchronization of oscillations of various frequencies and this coupling is fundamental to the process of memory consolidation. Specifically, high-frequency oscillations, or ripples, in the hippocampal formation are required for the conversion of short-term to …
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X-ray power density spectra of black hole binaries : a new deadtime model for the RXTE PCA
… is an essential tool for determining the frequency content of X-ray radiation from astronomical sources. For neutron star systems, power density spectra reveal coherent oscillations for those sources that are pulsars, while quasi-periodic oscillations over a wide range of frequencies (0.01 …
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Meshless Direct Numerical Simulation of Turbulent Incompressible Flows
… Inflow conditions were white noise and high frequency oscillations. Results suggest that, if no numerical instability is present, inflow conditions alone are not enough to sustain permanently the turbulent regime. Finally, the 2D-DNS on a backward-facing step is studied. Expansion ratios …
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Well-posedness and convergence of cfd two-fluid model for bubbly flows
… physical instabilities along with the undesired high frequency oscillations resulting from the ill-posedness. Thus, the TFM loses the capability to predict the inherent local dynamics of the two-phase flow. The alternative approach followed in the current study is to introduce appropriate …
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High frequency field potentials of the cerebellar cortex
… The origin and function of the field potential oscillations in the cerebellum, especially in the high frequencies, have not been explored sufficiently. The primary objective of this study was to investigate the spatio-temporal characteristics of high frequency field potentials (150-350Hz) in the …
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Prediction of the Outcome in Cardiac Arrest Patients Undergoing Hypothermia Using EEG Wavelet Entropy
… demonstrate more complexity and consequently higher values of wavelet sub-band entropies.</p> <p>A dataset of 16-channel EEG signals collected from CA patients undergoing hypothermia at Long Beach Memorial Medical Center was used to test the hypothesis. Following preprocessing of the signals …
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Feedforward and Feedback Signals in the Olfactory System
… in neural systems often results in prominent oscillations. The primary goal of the research presented in this thesis was to study effects of sensory stimulus on the olfactory system of rats, focusing on the olfactory bulb (OB) and the anterior piriform cortex (aPC). Extracellular …
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Dispersive neural networks for adaptive signal processing
… networks were unstable, generating high-frequency oscillations. Dispersive networks also showed an improvement over conventional techniques in an adaptive channel equalization task, where the channel transfer function was nonlinear. The adaptable delays in the dispersive network …
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Development and Testing of a Gallium Electromagnetic (GEM) Thruster
… 6 - 7 milliohms at peak current. The absence of high-frequency oscillations in the arc voltage trace indicates lack of the ``onset"" condition often seen in MPD arcs, suggesting that a sufficient number of charge carriers are present for current conduction. It is found that the mass bit varies …
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Spiking and oscillatory correlates of visual short-term memory for multiple items
… cortex (PFC). At stimulus encoding, lower frequency oscillations decreased in power in proportion to the total number of stimuli presented, while higher frequency oscillations increased in power in proportion to the number of stimuli contralateral to the recording site. During the delay, …
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Adaptive Process Control for Achieving Consistent Mean Particles' States in Atmospheric Plasma Spray Process
… laws and including a low-pass filter that remove high-frequency oscillations in the output. The utility of the MRAC controller to achieve desired locations of NiCrAlY and zirconia powder particles for generating a 5-layered coating is demonstrated. In this case a pure NiCrAlY layer bonds to the …
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Stability Limits of Uncertain Systems in the Presence of Unmatched Coupled Dynamics and Actuator Dynamics with Adaptive Architectures
… of incorporating a low-pass filter to mitigate high-frequency oscillations that can arise from the large MRAC update rates that are required for faster convergence. Furthermore within the modified hedged- and modified expanded reference model-based MRAC schemes, we analyze three approaches to …
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Antioxidants in Normal and Epileptic Brain: Effect on Synaptic Plasticity, Neural Network Physiology, and Memory
… for its cellular protection in environments of high oxidative stress. Even though physiological concentrations of AA in the brain are significant (0.2–10 mM), surprisingly little is known concerning the role of AA in synaptic neurotransmission under normal, non-disease state conditions. AA …
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