scholarly journals Multi-Region Brain Stimulation Optimization Using Transcranial Direct Current Stimulation

2019 ◽  
Author(s):  
Ziliang Xu ◽  
Jinbo Sun ◽  
Yao Chen ◽  
Yang Yu ◽  
Xuejuan Yang ◽  
...  
Keyword(s):  
Field Strength ◽  
Direct Current ◽  
Brain Stimulation ◽  
Transcranial Direct Current Stimulation ◽  
Brain Region ◽  
Optimization Scheme ◽  
Electrical Field ◽  
Electrical Field Strength ◽  
Single Target ◽  
Optimization Schemes

AbstractTranscranial direct current stimulation (tDCS) is a type of noninvasive transcranial electrical brain stimulation. By optimizing the current distribution of each electrode on the scalp, the stimulation can be guided to a target brain region using a tDCS dense electrode array system. However, previous studies have yielded simple results using optimization schemes in single target stimulation cases. The detailed parameter settings for each optimization scheme and the associated simulation results have not been comprehensively assessed. In this study, we investigated parameter settings of optimization schemes in detail in both single target and multi-target cases. Two optimization schemes, minimum least squares (MLS) and maximum electrical field strength (ME), were examined in this study. MLS minimizes the squared errors between the expected electrical field and the estimated electrical field, whereas ME maximizes the electrical field strength in the target region. We constructed a five layer finite-element head model with 64 electrodes placed on the scalp according to the EEG 10/10 system for simulation. We evaluated the effects of stimulation using these two schemes under three conditions, 1) single target stimulation, 2) multi-target stimulation, and 3) multi-target stimulation under specific task activation, which shown that directly using MLS and ME scheme in multi-target stimulation case may lead to a wrong result. We also reported the improved results fixed by our proposed weighted MLS and weighted ME schemes which take detailed parameter settings into consideration. Our results indicate that the parameter settings in each optimization scheme greatly affected the final stimulation results, especially in the case of multi-target stimulation, and thus, indicate that the parameter settings of each optimization scheme should be carefully considered according to the expected stimulation mode. Our results also suggest that, by calculating the parameters through our proposed methods, the weighted ME and weighted MLS scheme can precisely distribute energy into each target brain region.

scholarly journals The Impact of Cross-Linking Effect on the Space Charge Characteristics of Cross-Linked Polyethylene with Different Degrees of Cross-Linking under Strong Direct Current Electric Field

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1149 ◽  
Author(s):  
Shuchao Wang ◽  
Quan Zhou ◽  
Ruijin Liao ◽  
Lai Xing ◽  
Nengcheng Wu ◽  
...  
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Space Charge ◽  
Direct Current ◽  
Cross Linking ◽  
Average Charge ◽  
Electrical Field ◽  
Electrical Field Strength ◽  
The Cross ◽  
The Impact

Cross-linked polyethylene (XLPE) obtained by the crossing-linking reaction of polyethylene (PE) can greatly enhance the mechanical properties and other properties of PE, which makes XLPE widely applied in the field of electric power engineering. However, the space charges can distort the distribution of the electrical field strength in the XLPE applied in the insulation materials, which can shorten the service life of the insulation materials. Therefore, the space charge characteristics of XLPE under the strong direct current (DC) electric field have been the focus of scholars and engineers all over the world. This article has studied the impact of the cross-linking effect on the space charge characteristics of XLPE with different degrees of cross-linking. For this issue, we used dicumyl peroxide (DCP) as the cross-linking agent and low-density polyethylene (LDPE) as the base material for the preparation of samples. Besides, the space charge distribution was measured by the pulsed electro-acoustic method (PEA). In addition, the average charge density as a characteristic parameter was introduced into the experiment, which was used to quantitatively analyze the impact of the cross-linking effect on the space charge characteristics of XLPE with different degrees of cross-linking. Meanwhile, we also explained the impact of the cross-linking effect on XLPE with different degrees of cross-linking from a microscopic point of view. Ultimately, some important conclusions can be obtained. For instance, the cross-linking effect significantly increases the threshold electrical field strength of XLPE, and as the content of cross-linking agent increases, the threshold electrical field strength increases at first and then decreases, and the threshold electrical field strength reaches the maximum value when the content of the cross-linking agent is 1.0% or 2.1%. Besides, the cross-linking effect introduces negative charge traps into the LDPE and increases the densities of the deeper charge traps, and so on. In addition, we have also analyzed the average charge density, and we have summarized the theoretical model of the average charge decay, namely, Q ( t ) = Q 0 + α e − t β , which is very effective for explaining the dissipation characteristics (more conclusive contents can be seen in the conclusion section of this article).

Prefrontal Cortex Transcranial Direct Current Stimulation Treatment in Alcohol Dependence Syndrome (PreCoTTA): Study Protocol for a Double-Blind Randomized Sham-Controlled Trial

2021 ◽  
Vol 16 ◽  
Author(s):  
Anagha S. Deshmukh ◽  
Samir Kumar Praharaj ◽  
Shweta Rai ◽  
Asha Kamath ◽  
Dinesh Upadhya
Keyword(s):  
Prefrontal Cortex ◽  
Alcohol Dependence ◽  
Direct Current ◽  
Brain Stimulation ◽  
Transcranial Direct Current Stimulation ◽  
Public Health Problem ◽  
Comprehensive Treatment ◽  
Direct Current Stimulation ◽  
Non Invasive ◽  
Alcohol Dependence Syndrome

Background: Alcohol dependence is a significant public health problem, contributing to the global health burden. Due to its immense socio-economic burden, various psychosocial, psychological, and pharmacological approaches have attempted to alter the behaviour of the patient misusing or abusing alcohol, but their efficacy is modest at best. Therefore, there is a search for newer treatment approaches, including noninvasive brain stimulation in the management of alcohol dependence. We plan to study the efficacy of Prefrontal Cortex Transcranial direct current stimulation Treatment in Alcohol dependence syndrome (PreCoTTA). Methods: Two hundred twenty-five male patients with alcohol dependence syndrome will be randomized into the three study arms (2 active, left dorsolateral prefrontal cortex and left orbitofrontal cortex, and 1 sham) to receive a total of 14 tDCS sessions (10 continuous and 4 booster sessions). Data will be collected from them at five different time points on clinical, neuropsychological and biochemical parameters. In addition, 225 healthy age and education matched controls will be administered the neuropsychological test battery at baseline for comparison with the patient group. Discussion: The proposed study aims to explore the use of non-invasive brain stimulation; tDCS as a treatment alternative. We also aim to overcome the methodological gaps of limited sample sizes, fewer tDCS intervention sessions, lack of long term follow ups to measure the sustainability of gains and lack comprehensive measures to track changes in functioning and abstinence after tDCS intervention. The main outcomes include clinical (reduction in cue-induced craving, time to first drink and QFI); neuropsychological (risk-taking, impulsivity, and other neuropsychological domains) and biochemical markers (BDNF, leptin and adiponectin). The findings of the study will have translational value as it may help to improve the clinician’s ability to effectively manage craving in patients with alcohol dependence syndrome. Furthermore, we will have a better understanding of the neuropsychological and biochemical effects of non-invasive brain stimulation techniques which are of interest in the comprehensive treatment of addiction disorders. Trial registration: The study has been registered with the Clinical Trials Registry-India (CTRI/2020/09/027582) on September 03rd 2020.

Electrohydrodynamic Printing via Spinneret with Conductive Probe

2013 ◽  
Vol 562-565 ◽  
pp. 1155-1160
Author(s):  
Yi Hong Lin ◽  
Guang Qi He ◽  
Hai Yan Liu ◽  
Jin Wei ◽  
Jian Yi Zheng ◽  
...  
Keyword(s):  
Field Strength ◽  
Applied Voltage ◽  
Industrial Application ◽  
Control Level ◽  
Direct Write ◽  
Electrical Field ◽  
Nano Structure ◽  
Electrical Field Strength ◽  
Electrohydrodynamic Printing ◽  
The Stability

Stability jet ejection and precision deposition are the two keys for industrial application of electrohydrodynamic printing. In this paper, inserted conductive probe is utilized to gain stability jet, which would increase the electrical field strength, reduce the back flow, onset and sustaining voltage. Lower applied voltage would enhance the stability of electrospun jet, in which fine jet can be used to direct-write orderly Micro/Nano-structure. With the guidance and constrain of inserted probe, the oscillating angle range of electrohydrodynamic jet is decreased to 3°from 15°, and the width of printed structures is 21μm in average that is much narrower than that printed from spinneret without probe (74μm in average). Spinneret with tip provides a good way to improve the control level of electrohydrodynamic printing, which would accelerate the industrial application of electrohydrodynamic printed Micro/Nano structure.

Fully Developed Flow of Power-Law Fluid Through a Cylindrical Microfluidic Pipe: Pressure Drop and Electroviscous Effects

2008 ◽  
Author(s):  
Ram P. Bharti ◽  
Dalton J. E. Harvie ◽  
Malcolm R. Davidson
Keyword(s):  
Pressure Drop ◽  
Field Strength ◽  
Charge Density ◽  
Power Law ◽  
Maximum Velocity ◽  
Shear Thickening ◽  
Shear Thinning ◽  
Electrical Field ◽  
Electrical Field Strength ◽  
Fluid Behaviour

Pressure drop and electroviscous effects in the axisymmetric, steady, fully developed, pressure-driven flow of incompressible power-law fluids through a cylindrical microchannel at low Reynolds number (Re = 0.01) have been investigated. The Poisson-Boltzmann equation (describing the electrical potential) and the momentum equations in conjunction with electrical force and power-law fluid rheology have been solved numerically using the finite difference method. The pipe wall is considered to have uniform surface charge density (S = 4) and the liquid is assumed to be a symmetric electrolyte solution. In particular, the influence of the dimensionless inverse Debye length (K = 2, 20) and power-law flow behaviour index (n = 0.2, 1, 1.8) on the EDL potential, ion concentrations and charge density profiles, induced electrical field strength, velocity and viscosity profiles and pressure drop have been studied. As expected, the local EDL potential, local charge density and electrical field strength increases with decreasing K and/or increasing S. The velocity profiles cross-over away from the charged pipe wall with increasing K and/or decreasing n. The maximum velocity at the center of the pipe increases with increasing n and/or increasing S and/or decreasing K. The shear-thinning fluid viscosity is strongly dependent on K and S, whereas the shear-thickening viscosity is very weakly dependent on K and S. For fixed K, as the fluid behaviour changes from Newtonian (n = 1) to shear-thinning (n < 1), the induced electrical field strength increases and maximum velocity reduces. On the other hand, the change in fluid behaviour from Newtonian (n = 1) to shear-thickening (n > 1) decreases the electrical field strength and increases the maximum velocity. The non-Newtonian effects on maximum velocity and pressure drop are stronger in shear-thinning fluids at small K and large S, the shear-thickening fluids show opposite influence. Electroviscous effects enhance with decreasing K and/or increasing S. The electroviscous effects show complex dependence on the non-Newtonian tendency of the fluids. The shear-thickening (n > 1) fluids and/or smaller K show stronger influence on the pressure drop and thus, enhance the electroviscous effects than that in shear-thinning (n < 1) fluids and/or large K where EDL is very thin.

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