The Experts below are selected from a list of 17547 Experts worldwide ranked by ideXlab platform
C Montella - One of the best experts on this subject based on the ideXlab platform.
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re examination of the potential step chronoamperometry method through numerical inversion of laplace transforms i general formulation and numerical solution
Journal of Electroanalytical Chemistry, 2009Co-Authors: C MontellaAbstract:Abstract Re-examination of the potential-step chronoamperometry (PSCA) method through numerical inversion of Laplace transforms is proposed in this work. First, a general expression is derived in the Laplace domain for the current transient following the application of a potential step of arbitrary amplitude. The formulation applies to first-order electrochemical–chemical reactions (E, EC and CE reactions) with one-dimensional mass-transport processes of implicated species in the electrolytic solution or the Electrode. Next, numerical inversion of the relevant Laplace transform is performed by the Gaver–Stehfest (GS), Fourier–Euler (FE) and ‘fixed’ Talbot (FT) methods. The so-called GS-, FE- and FT-PSCA algorithms in this work make it possible to investigate a wide range of Electrode Geometry and chemical, electrochemical and one-dimensional mass-transport processes by the PSCA method. Each algorithm provides a full explicit formulation of Faradaic current with respect to time, applied potential and electrochemical parameters (initial concentrations, geometrical parameter(s), standard potential, electrochemical and chemical rate constants and diffusion coefficients), which greatly simplifies the computation of potentiostatic current transients. Some application examples relative to diffusion equations with spherical Electrode Geometry will be presented in the second part of this work.
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re examination of the potential step chronoamperometry method through numerical inversion of laplace transforms ii application examples
Journal of Electroanalytical Chemistry, 2009Co-Authors: C MontellaAbstract:In the first part of this work, we proposed the so-called GS-, FE- and FT-PSCA algorithms to investigate a wide range of Electrode Geometry and chemical, electrochemical and one-dimensional mass-transport processes by the potential-step chronoamperometry (PSCA) method. Each algorithm provides a full explicit formulation of Faradaic current with respect to time, applied potential and electrochemical parameters (initial concentrations, geometrical parameter(s), standard potential, electrochemical and chemical rate constants and diffusion coefficients). Application examples relative to diffusion equations with spherical Electrode Geometry are presented in this second article by way of illustration of the potentialities of GS- and FT-PSCA algorithms. First, the case of one-step electrochemical reactions at spherical and hemispherical Electrodes of any radius is investigated when both implicated species are soluble in the electrolytic solution. The numerical solution obtained from GS-PSCA algorithm is favourably compared to previous results in the electrochemical literature. Next, we use the FT-PSCA algorithm for investigating spherical diffusion with amalgamation reaction. Finally, the characteristic features of chronoamperograms and sampled-current voltammograms pertaining to the above reaction are examined and discussed.
Kevin L. Kilgore - One of the best experts on this subject based on the ideXlab platform.
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Effect of Nerve Cuff Electrode Geometry on Onset Response Firing in High-Frequency Nerve Conduction Block
2015Co-Authors: Michael D Ackermann, Emily L. Foldes, Niloy Bhadra [member, Xiao-feng Wang, Kevin L. KilgoreAbstract:The delivery of high-frequency alternating currents has been shown to produce a focal and reversible conduction block in whole nerve and is a potential therapeutic option for various diseases and disorders involving pathological or undesired neurological activity. However, delivery of high-frequency alternating current to a nerve produces a finite burst of neuronal firing, called the onset response, before the nerve is blocked. Reduction or elimination of the onset response is very important to moving this type of nerve block into clinical applications since the onset response is likely to result in undesired muscle contraction and pain. This paper describes a study of the effect of nerve cuff Electrode Geometry (specifically, bipolar contact separation distance), and waveform amplitude on the magnitude and duration of the onset response. Electrode Geometry and waveform amplitude were both found to affect these measures. The magnitude and duration of the onset response showed a monotonic relationship with bipolar separation distance and amplitude. The duration of the onset response varied by as much as 820 % on average for combinations of different Electrode geometries and waveform amplitudes. Bipolar Electrodes with a contact separation distance of 0.5 mm resulted in the briefest onset response on average
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effect of nerve cuff Electrode Geometry on onset response firing in high frequency nerve conduction block
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2010Co-Authors: Michael D Ackermann, Narendra Bhadra, Emily L. Foldes, X Wang, Kevin L. KilgoreAbstract:The delivery of high-frequency alternating currents has been shown to produce a focal and reversible conduction block in whole nerve and is a potential therapeutic option for various diseases and disorders involving pathological or undesired neurological activity. However, delivery of high-frequency alternating current to a nerve produces a finite burst of neuronal firing, called the onset response, before the nerve is blocked. Reduction or elimination of the onset response is very important to moving this type of nerve block into clinical applications since the onset response is likely to result in undesired muscle contraction and pain. This paper describes a study of the effect of nerve cuff Electrode Geometry (specifically, bipolar contact separation distance), and waveform amplitude on the magnitude and duration of the onset response. Electrode Geometry and waveform amplitude were both found to affect these measures. The magnitude and duration of the onset response showed a monotonic relationship with bipolar separation distance and amplitude. The duration of the onset response varied by as much as 820% on average for combinations of different Electrode geometries and waveform amplitudes. Bipolar Electrodes with a contact separation distance of 0.5 mm resulted in the briefest onset response on average. Furthermore, the data presented in this study provide some insight into a biophysical explanation for the onset response. These data suggest that the onset response consists of two different phases: one phase which is responsive to experimental variables such as Electrode Geometry and waveform amplitude, and one which is not and appears to be inherent to the transition to the blocked state. This study has implications for nerve block Electrode and stimulation parameter selection for clinical therapy systems and basic neurophysiology studies.
David J. Wineland - One of the best experts on this subject based on the ideXlab platform.
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toward scalable ion traps for quantum information processing
New Journal of Physics, 2010Co-Authors: J M Amini, D Leibfried, J Britton, Hermann Uys, J H Wesenberg, S Seidelin, John J Bollinger, C Ospelkaus, Aaron P Vandevender, David J. WinelandAbstract:In this paper, we report the design, fabrication and preliminary testing of a 150 zone ion trap array built in a 'surface-Electrode' Geometry micro- fabricated on a single substrate. We demonstrate the transport of atomic ions between the legs of a 'Y'-type junction and measure the in-situ heating rates for the ions. The trap design demonstrates the use of a basic component design librarythat canbequickly assembledto formstructuresoptimized foraparticular experiment.
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scalable ion traps for quantum information processing
arXiv: Quantum Physics, 2009Co-Authors: J M Amini, D Leibfried, J Britton, Hermann Uys, J H Wesenberg, S Seidelin, John J Bollinger, C Ospelkaus, Aaron P Vandevender, David J. WinelandAbstract:We report on the design, fabrication, and preliminary testing of a 150 zone array built in a `surface-Electrode' Geometry microfabricated on a single substrate. We demonstrate transport of atomic ions between legs of a `Y'-type junction and measure the in-situ heating rates for the ions. The trap design demonstrates use of a basic component design library that can be quickly assembled to form structures optimized for a particular experiment.
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surface Electrode architecture for ion trap quantum information processing
Quantum Information & Computation, 2005Co-Authors: Jessica Chiaverini, D Leibfried, R B Blakestad, J Britton, J D Jost, C Langer, Roee Ozeri, David J. WinelandAbstract:We investigate a surface-mounted Electrode Geometry for miniature linear radio frequencyPaul ion traps. The Electrodes reside in a single plane on a substrate, and the pseudopotentialminimum of the trap is located above the substrate at a distance on the orderof the Electrodes' lateral extent or separation. This architecture provides the possibilityto apply standard microfabrication principles to the construction of multiplexed iontraps, which may be of particular importance in light of recent proposals for large-scalequantum computation based on individual trapped ions.
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surface Electrode architecture for ion trap quantum information processing
arXiv: Quantum Physics, 2005Co-Authors: Jessica Chiaverini, D Leibfried, R B Blakestad, J Britton, J D Jost, C Langer, Roee Ozeri, David J. WinelandAbstract:We investigate a surface-mounted Electrode Geometry for miniature linear radio frequency Paul ion traps. The Electrodes reside in a single plane on a substrate, and the pseudopotential minimum of the trap is located above the substrate at a distance on order of the Electrodes' lateral extent or separation. This architecture provides the possibility to apply standard microfabrication principles to the construction of multiplexed ion traps, which may be of particular importance in light of recent proposals for large-scale quantum computation based on individual trapped ions.
Warren M. Grill - One of the best experts on this subject based on the ideXlab platform.
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evaluation of high perimeter Electrode designs for deep brain stimulation
Journal of Neural Engineering, 2014Co-Authors: Bryan Howell, Warren M. GrillAbstract:Objective. Deep brain stimulation (DBS) is an effective treatment for movement disorders and a promising therapy for treating epilepsy and psychiatric disorders. Despite its clinical success, complications including infections and mis-programing following surgical replacement of the battery-powered implantable pulse generator adversely impact the safety profile of this therapy. We sought to decrease power consumption and extend battery life by modifying the Electrode Geometry to increase stimulation efficiency. The specific goal of this study was to determine whether Electrode contact perimeter or area had a greater effect on increasing stimulation efficiency. Approach. Finite-element method (FEM) models of eight prototype Electrode designs were used to calculate the Electrode access resistance, and the FEM models were coupled with cable models of passing axons to quantify stimulation efficiency. We also measured in vitro the electrical properties of the prototype Electrode designs and measured in vivo the stimulation efficiency following acute implantation in anesthetized cats. Main results. Area had a greater effect than perimeter on altering the Electrode access resistance; Electrode (access or dynamic) resistance alone did not predict stimulation efficiency because efficiency was dependent on the shape of the potential distribution in the tissue; and, quantitative assessment of stimulation efficiency required consideration of the effects of the Electrode–tissue interface impedance. Significance. These results advance understanding of the features of Electrode Geometry that are important for designing the next generation of efficient DBS Electrodes.
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Influences of interpolation error, Electrode Geometry, and the Electrode-tissue interface on models of electric fields produced by deep brain stimulation
IEEE Transactions on Biomedical Engineering, 2014Co-Authors: Bryan Howell, Sagar Naik, Warren M. GrillAbstract:Deep brain stimulation (DBS) is an established therapy for movement disorders, but the fundamental mechanisms by which DBS has its effects remain unknown. Computational models can provide insights into the mechanisms of DBS, but to be useful, the models must have sufficient detail to predict accurately the electric fields produced by DBS. We used a finite-element method model of the Medtronic 3387 Electrode array, coupled to cable models of myelinated axons, to quantify how interpolation errors, Electrode Geometry, and the Electrode-tissue interface affect calculation of electrical potentials and stimulation thresholds for populations of model nerve fibers. Convergence of the potentials was not a sufficient criterion for ensuring the same degree of accuracy in subsequent determination of stimulation thresholds, because the accuracy of the stimulation thresholds depended on the order of the elements. Simplifying the 3387 Electrode array by ignoring the inactive contacts and extending the terminated end of the shaft had position-dependent effects on the potentials and excitation thresholds, and these simplifications may impact correlations between DBS parameters and clinical outcomes. When the current density in the bulk tissue is uniform, the effect of the Electrode-tissue interface impedance could be approximated by filtering the potentials calculated with a static lumped electrical equivalent circuit. Further, for typical DBS parameters during voltage-regulated stimulation, it was valid to approximate the Electrode as an ideal polarized Electrode with a nonlinear capacitance. Validation of these computational considerations enables accurate modeling of the electric field produced by DBS.
Michael D Ackermann - One of the best experts on this subject based on the ideXlab platform.
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Effect of Nerve Cuff Electrode Geometry on Onset Response Firing in High-Frequency Nerve Conduction Block
2015Co-Authors: Michael D Ackermann, Emily L. Foldes, Niloy Bhadra [member, Xiao-feng Wang, Kevin L. KilgoreAbstract:The delivery of high-frequency alternating currents has been shown to produce a focal and reversible conduction block in whole nerve and is a potential therapeutic option for various diseases and disorders involving pathological or undesired neurological activity. However, delivery of high-frequency alternating current to a nerve produces a finite burst of neuronal firing, called the onset response, before the nerve is blocked. Reduction or elimination of the onset response is very important to moving this type of nerve block into clinical applications since the onset response is likely to result in undesired muscle contraction and pain. This paper describes a study of the effect of nerve cuff Electrode Geometry (specifically, bipolar contact separation distance), and waveform amplitude on the magnitude and duration of the onset response. Electrode Geometry and waveform amplitude were both found to affect these measures. The magnitude and duration of the onset response showed a monotonic relationship with bipolar separation distance and amplitude. The duration of the onset response varied by as much as 820 % on average for combinations of different Electrode geometries and waveform amplitudes. Bipolar Electrodes with a contact separation distance of 0.5 mm resulted in the briefest onset response on average
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effect of nerve cuff Electrode Geometry on onset response firing in high frequency nerve conduction block
IEEE Transactions on Neural Systems and Rehabilitation Engineering, 2010Co-Authors: Michael D Ackermann, Narendra Bhadra, Emily L. Foldes, X Wang, Kevin L. KilgoreAbstract:The delivery of high-frequency alternating currents has been shown to produce a focal and reversible conduction block in whole nerve and is a potential therapeutic option for various diseases and disorders involving pathological or undesired neurological activity. However, delivery of high-frequency alternating current to a nerve produces a finite burst of neuronal firing, called the onset response, before the nerve is blocked. Reduction or elimination of the onset response is very important to moving this type of nerve block into clinical applications since the onset response is likely to result in undesired muscle contraction and pain. This paper describes a study of the effect of nerve cuff Electrode Geometry (specifically, bipolar contact separation distance), and waveform amplitude on the magnitude and duration of the onset response. Electrode Geometry and waveform amplitude were both found to affect these measures. The magnitude and duration of the onset response showed a monotonic relationship with bipolar separation distance and amplitude. The duration of the onset response varied by as much as 820% on average for combinations of different Electrode geometries and waveform amplitudes. Bipolar Electrodes with a contact separation distance of 0.5 mm resulted in the briefest onset response on average. Furthermore, the data presented in this study provide some insight into a biophysical explanation for the onset response. These data suggest that the onset response consists of two different phases: one phase which is responsive to experimental variables such as Electrode Geometry and waveform amplitude, and one which is not and appears to be inherent to the transition to the blocked state. This study has implications for nerve block Electrode and stimulation parameter selection for clinical therapy systems and basic neurophysiology studies.