The impact of brain lesions on tDCS-induced electric field magnitude

Background: Transcranial direct current stimulation (tDCS) has been used to enhance motor and language rehabilitation following a stroke. However, improving the effectiveness of clinical tDCS protocols depends on understanding how a lesion may influence tDCS-induced current flow through the brain. Objective: We systematically investigated the effect of brain lesions on the magnitude of electric fields (e-mag) induced by tDCS. Methods: We simulated the effect of 630 different lesions - by varying lesion location, distance from the region of interest (ROI), size and conductivity - on tDCS-induced e-mag. We used current flow models in the brains of two participants, for two commonly used tDCS montages, targeting either primary motor cortex (M1) or Brocas area (BA44) as ROIs. Results: The effect on absolute e-mag change was highly dependent on lesion size, conductance and distance from ROI. Larger lesions, with high conductivity, close to the ROI caused e-mag changes of more than 30%. The sign of this change was determined by the location of the lesion. Specifically, lesions located in-line with the predominant direction of current flow increased e-mag in the ROI, whereas lesions located in the opposite direction caused a decrease. Conclusions: These results demonstrate that tDCS-induced electric fields are profoundly influenced by lesion characteristics. This highlights the need for individualised targeting and dose control in stroke. Additionally, the variation in electrical fields caused by assigned conductance of the lesion underlines the need for improved estimates of lesion conductivity for current flow models.

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Impact of pin Type Insulators on Power Distribution Networks Caused by Lightning Impulse Overvoltage

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.781.300 ◽

2015 ◽

Vol 781 ◽

pp. 300-303

Author(s):

Khamhyo Phothilath ◽

Kittipong Tonmitra ◽

Pramin Artrit

Keyword(s):

Power Distribution ◽

Current Flow ◽

Distribution Networks ◽

Lightning Strike ◽

Power Distribution Networks ◽

Lightning Impulse ◽

Flow Through ◽

The Impact

The impact of pin type insulators may cause from the lightning impulse overvoltage that hits directly to them. To investigate this problem, this work applies the ATP Draw version 5.6 software to simulate the effect of pin type insulators. Therefore, the obtained results are showed that pin type insulators at pole P4 is closely the lightning strike point, has affected more than the poles P3-P1 and P5-P7. In addition, the conductor has been taken by the heat of over current flow through on it. The flashover and breakdown severity is on insulator upon the distance of them.

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Measurements and models of electric fields in the in vivo human brain during transcranial electric stimulation

eLife ◽

10.7554/elife.18834 ◽

2017 ◽

Vol 6 ◽

Cited By ~ 187

Author(s):

Yu Huang ◽

Anli A Liu ◽

Belen Lafon ◽

Daniel Friedman ◽

Michael Dayan ◽

...

Keyword(s):

Human Brain ◽

Electric Fields ◽

Electric Stimulation ◽

Animal Studies ◽

Current Flow ◽

Electrical Currents ◽

Tissue Conductivity ◽

Flow Models ◽

Transcranial Electric Stimulation

Transcranial electric stimulation aims to stimulate the brain by applying weak electrical currents at the scalp. However, the magnitude and spatial distribution of electric fields in the human brain are unknown. We measured electric potentials intracranially in ten epilepsy patients and estimated electric fields across the entire brain by leveraging calibrated current-flow models. When stimulating at 2 mA, cortical electric fields reach 0.8 V/m, the lower limit of effectiveness in animal studies. When individual whole-head anatomy is considered, the predicted electric field magnitudes correlate with the recorded values in cortical (r = 0.86) and depth (r = 0.88) electrodes. Accurate models require adjustment of tissue conductivity values reported in the literature, but accuracy is not improved when incorporating white matter anisotropy or different skull compartments. This is the first study to validate and calibrate current-flow models with in vivo intracranial recordings in humans, providing a solid foundation to target stimulation and interpret clinical trials.

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A Deep Insight into the Electronic Properties of CIGS Modules with Monolithic Interconnects Based on 2D Simulations with TCAD

Coatings ◽

10.3390/coatings9020128 ◽

2019 ◽

Vol 9 (2) ◽

pp. 128 ◽

Cited By ~ 1

Author(s):

Ricardo Vidal Lorbada ◽

Thomas Walter ◽

David Fuertes Marrón ◽

Tetiana Lavrenko ◽

Dennis Muecke

Keyword(s):

Field Effect Transistor ◽

Current Flow ◽

Light Conditions ◽

Flow Through ◽

Weak Light ◽

Effect Transistor ◽

P Type ◽

The Impact ◽

Fabrication Parameters ◽

Insight Into

The aim of this work is to provide an insight into the impact of the P1 shunt on the performance of ZnO/CdS/Cu(In,Ga)Se2/Mo modules with monolithic interconnects. The P1 scribe is a pattern that separates the back contact of two adjacent cells and is filled with Cu(In,Ga)Se2 (CIGS). This scribe introduces a shunt that can affect significantly the behavior of the device, especially under weak light conditions. Based on 2D numerical simulations performed with TCAD, we postulate a mechanism that affects the current flow through the P1 shunt. This mechanism is similar to that of a junction field effect transistor device with a p-type channel, in which the current flow can be modulated by varying the thickness of the channel and the doping concentration. The results of these simulations suggest that expanding the space charge region (SCR) into P1 reduces the shunt conductance in this path significantly, thus decreasing the current flow through it. The presented simulations demonstrate that two fabrication parameters have a direct influence on the extension of the SCR, which are the thickness of the absorber layer and its acceptor concentration.

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THE EFFECT OF OXYGEN ADSORPTION ON THE CONDUCTIVITY OF PBTE FILMS.

EurasianUnionScientists ◽

10.31618/esu.2413-9335.2020.6.77.1001 ◽

2020 ◽

Vol 6 (8(77)) ◽

pp. 21-23

Author(s):

S.N. Sarmasov ◽

R.Sh. Rahimov ◽

T.Sh. Abdullayev

Keyword(s):

Spectral Region ◽

Current Flow ◽

Oxygen Adsorption ◽

Tunneling Mechanism ◽

Pn Junction ◽

Flow Through ◽

Pn Junctions ◽

Effect Of Oxygen

The effect of oxygen adsorption on the conductivity of PbTe films is studied. Pn junctions based on PbTe films are photosensitive in the IR spectral region with a maximum photosensitivity of 𝜆𝑚𝑎𝑥 microns. The tunneling mechanism of current flow through the pn junction is shown.

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Water Temperature Control Using PID Control System Based on LabVIEW

Telekontran : Jurnal Ilmiah Telekomunikasi, Kendali dan Elektronika Terapan ◽

10.34010/telekontran.v4i2.1888 ◽

2016 ◽

Vol 4 (2) ◽

pp. 35-46

Author(s):

Ari Ramadhani

Keyword(s):

Water Temperature ◽

Pid Control ◽

Temperature Sensor ◽

Pid Controller ◽

Current Flow ◽

Electrical Energy ◽

Heating Process ◽

Water Heater ◽

Digital Thermometer ◽

Flow Through

Abstract - Automatic system have grown widespread across all sector so do water heater. Traditionally, heating water is done by utilizing fire as heat source. As the growing of technology, the heating process could be done by manipulating electrical energy by convert it to heat. Electrical energy is flown to a metal rod that contact directly with the water which increase the water temperature. On some case, appropiate water temperature is needed. Altough, a thermometer is needed to read the actual temperature as a feedback value for the system and a system that can control the electricity current flow through the heater that the heat produced is linear to the current flow. With implementing microcontroller as a process node for generating PWM signal, this problem can be solved. Also, Labview is needed as an interface for monitoring and bursting an output which have been processed by Proportional, Integral, and Devivative (PID) controller to producing accurate and stable heat. Based on the results of testing, the system is able to provide a rapid response to any changes that occur, both changes in set-point and changes in water temperature (actual value). Another test is done by comparing the temperature value detected by the temperature sensor in this device with an external digital thermometer placed in the same place, and from some of the tests the temperature value detected by the temperature sensor in this device has a difference of ± 0.19 ℃ with a digital thermometer. Keyword : Water Heater, Thermometer, Microcontroller, LabView, PID.

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Mathematical modelling of salt purification by recrystallization. A cross-current flow model and its comparison with the countercurrent arrangement

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19862489 ◽

1986 ◽

Vol 51 (11) ◽

pp. 2489-2501

Author(s):

Benitto Mayrhofer ◽

Jana Mayrhoferová ◽

Lubomír Neužil ◽

Jaroslav Nývlt

Keyword(s):

Flow Model ◽

Current Flow ◽

Countercurrent Flow ◽

Flow Models ◽

Multi Stage ◽

Stage Crystallization ◽

The Cross ◽

Current Flows ◽

Set Up ◽

Cross Current

A model is derived for a multi-stage crystallization with cross-current flows of the solution and the crystals being purified. The purity of the product is compared with that achieved in the countercurrent arrangement. A suitable function has been set up which allows the cross-current and countercurrent flow models to be compared and reduces substantially the labour of computation for the countercurrent arrangement. Using the recrystallization of KAl(SO4)2.12 H2O as an example, it is shown that, when the cross-current and countercurrent processes are operated at the same output, the countercurrent arrangement is more advantageous because its solvent consumption is lower.

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Peculiarities of Neurostimulation by Intense Nanosecond Pulsed Electric Fields: How to Avoid Firing in Peripheral Nerve Fibers

International Journal of Molecular Sciences ◽

10.3390/ijms22137051 ◽

2021 ◽

Vol 22 (13) ◽

pp. 7051

Author(s):

Vitalii Kim ◽

Emily Gudvangen ◽

Oleg Kondratiev ◽

Luis Redondo ◽

Shu Xiao ◽

...

Keyword(s):

Side Effects ◽

Electric Fields ◽

Pulsed Electric Fields ◽

Opposite Polarity ◽

Nerve Fibers ◽

High Rate ◽

Excitation Threshold ◽

Compound Action Potentials ◽

Supramaximal Stimulation ◽

The Impact

Intense pulsed electric fields (PEF) are a novel modality for the efficient and targeted ablation of tumors by electroporation. The major adverse side effects of PEF therapies are strong involuntary muscle contractions and pain. Nanosecond-range PEF (nsPEF) are less efficient at neurostimulation and can be employed to minimize such side effects. We quantified the impact of the electrode configuration, PEF strength (up to 20 kV/cm), repetition rate (up to 3 MHz), bi- and triphasic pulse shapes, and pulse duration (down to 10 ns) on eliciting compound action potentials (CAPs) in nerve fibers. The excitation thresholds for single unipolar but not bipolar stimuli followed the classic strength–duration dependence. The addition of the opposite polarity phase for nsPEF increased the excitation threshold, with symmetrical bipolar nsPEF being the least efficient. Stimulation by nsPEF bursts decreased the excitation threshold as a power function above a critical duty cycle of 0.1%. The threshold reduction was much weaker for symmetrical bipolar nsPEF. Supramaximal stimulation by high-rate nsPEF bursts elicited only a single CAP as long as the burst duration did not exceed the nerve refractory period. Such brief bursts of bipolar nsPEF could be the best choice to minimize neuromuscular stimulation in ablation therapies.

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Film-Forming Systems for the Delivery of DNDI-0690 to Treat Cutaneous Leishmaniasis

Pharmaceutics ◽

10.3390/pharmaceutics13040516 ◽

2021 ◽

Vol 13 (4) ◽

pp. 516

Author(s):

Katrien Van Bocxlaer ◽

Kerri-Nicola McArthur ◽

Andy Harris ◽

Mo Alavijeh ◽

Stéphanie Braillard ◽

...

Keyword(s):

Drug Delivery ◽

Cutaneous Leishmaniasis ◽

Mouse Skin ◽

Parasite Load ◽

Leishmania Species ◽

Lesion Size ◽

Drying Time ◽

Sustained Drug Delivery ◽

Film Forming ◽

The Impact

In cutaneous leishmaniasis (CL), parasites reside in the dermis, creating an opportunity for local drug administration potentially reducing adverse effects and improving treatment adherence compared to current therapies. Polymeric film-forming systems (FFSs) are directly applied to the skin and form a thin film as the solvent evaporates. In contrast to conventional topical dosage forms, FFSs strongly adhere to the skin, favouring sustained drug delivery to the affected site, reducing the need for frequent applications, and enhancing patient compliance. This study reports the first investigation of the use of film-forming systems for the delivery of DNDI-0690, a nitroimidazole compound with potent activity against CL-causing Leishmania species. A total of seven polymers with or without plasticiser were evaluated for drying time, stickiness, film-flexibility, and cosmetic attributes; three FFSs yielded a positive evaluation for all test parameters. The impact of each of these FFSs on the permeation of the model skin permeant hydrocortisone (hydrocortisone, 1% (w/v) across the Strat-M membrane was evaluated, and the formulations resulting in the highest and lowest permeation flux (Klucel LF with triethyl citrate and Eudragit RS with dibutyl sebacate, respectively) were selected as the FFS vehicle for DNDI-0690. The release and skin distribution of the drug upon application to Leishmania-infected and uninfected BALB/c mouse skin were examined using Franz diffusion cells followed by an evaluation of the efficacy of both DNDI-0690 FFSs (1% (w/v)) in an experimental CL model. Whereas the Eudragit film resulted in a higher permeation of DNDI-0690, the Klucel film was able to deposit four times more drug into the skin, where the parasite resides. Of the FFSs formulations, only the Eudragit system resulted in a reduced parasite load, but not reduced lesion size, when compared to the vehicle only control. Whereas drug delivery into the skin was successfully modulated using different FFS systems, the FFS systems selected were not effective for the topical application of DNDI-0690. The convenience and aesthetic of FFS systems alongside their ability to modulate drug delivery to and into the skin merit further investigation using other promising antileishmanial drugs.

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Elastic Modulus and Elasticity Ratio of Malignant Breast Lesions with Shear Wave Ultrasound Elastography: Variations with Different Region of Interest and Lesion Size

Diagnostics ◽

10.3390/diagnostics11061015 ◽

2021 ◽

Vol 11 (6) ◽

pp. 1015

Author(s):

Antonio Bulum ◽

Gordana Ivanac ◽

Eugen Divjak ◽

Iva Biondić Špoljar ◽

Martina Džoić Dominković ◽

...

Keyword(s):

Elastic Modulus ◽

Shear Wave ◽

Large Diameter ◽

Small Diameter ◽

Shear Wave Elastography ◽

Lesion Size ◽

Ultrasound Elastography ◽

Breast Lesions ◽

Malignant Breast ◽

The Impact

Shear wave elastography (SWE) is a type of ultrasound elastography with which the elastic properties of breast tissues can be quantitatively assessed. The purpose of this study was to determine the impact of different regions of interest (ROI) and lesion size on the performance of SWE in differentiating malignant breast lesions. The study included 150 female patients with histopathologically confirmed malignant breast lesions. Minimal (Emin), mean (Emean), maximal (Emax) elastic modulus and elasticity ratio (e-ratio) values were measured using a circular ROI size of 2, 4 and 6 mm diameters and the lesions were divided into large (diameter ≥ 15 mm) and small (diameter < 15 mm). Highest Emin, Emean and e-ratio values and lowest variability were observed when using the 2 mm ROI. Emax values did not differ between different ROI sizes. Larger lesions had significantly higher Emean and Emax values, but there was no difference in e-ratio values between lesions of different sizes. In conclusion, when measuring the Emin, Emean and e-ratio of malignant breast lesions using SWE the smallest possible ROI size should be used regardless of lesion size. ROI size has no impact on Emax values while lesion size has no impact on e-ratio values.

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Restraining Surface Charge Accumulation and Enhancing Surface Flashover Voltage through Dielectric Coating

Coatings ◽

10.3390/coatings11070750 ◽

2021 ◽

Vol 11 (7) ◽

pp. 750

Author(s):

Jixing Sun ◽

Sibo Song ◽

Xiyu Li ◽

Yunlong Lv ◽

Jiayi Ren ◽

...

Keyword(s):

Charge Transfer ◽

Electric Field ◽

Electric Fields ◽

Transition Process ◽

Metallic Particle ◽

Particle Charging ◽

Insulating Surfaces ◽

Surface Flashover ◽

Charging Time ◽

The Impact

A conductive metallic particle in a gas-insulated metal-enclosed system can charge through conduction or induction and move between electrodes or on insulating surfaces, which may lead to breakdown and flashover. The charge on the metallic particle and the charging time vary depending on the spatial electric field intensity, the particle shape, and the electrode surface coating. The charged metallic particle can move between the electrodes under the influence of the spatial electric field, and it can discharge and become electrically conductive when colliding with the electrodes, thus changing its charge. This process and its factors are mainly affected by the coating condition of the colliding electrode. In addition, the interface characteristics affect the particle when it is near the insulator. The charge transition process also changes due to the electric field strength and the particle charging state. This paper explores the impact of the coating material on particle charging characteristics, movement, and discharge. Particle charging, movement, and charge transfer in DC, AC, and superimposed electric fields are summarized. Furthermore, the effects of conductive particles on discharge characteristics are compared between coated and bare electrodes. The reviewed studies demonstrate that the coating can effectively reduce particle charge and thus the probability of discharge. The presented research results can provide theoretical support and data for studying charge transfer theory and design optimization in a gas-insulated system.

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