WIRE-MESH CAPACITANCE TOMOGRAPHY FOR TREATMENT PLANNING SYSTEM OF ELECTRO-CAPACITIVE CANCER THERAPY

The wire-mesh capacitance tomography (WMCT) has been applied to visualize 2D of the distribution of electric field intensity in the treatment planning system (TPS) of electro-capacitive cancer therapy (ECCT) using human head model. WMCT is proposed in this study to estimate accurately the distribution of electric field intensity which is the main optimum factors of ECCT in order to compensate the inaccuracy of TPS ECCT simulation. The experimental and simulation studies were conducted with wire-mesh sensor consisted of 8×8 wire matrix of copper in human head model using two type of helmet ECCT. The result of electric field value at the intersection wire-mesh have been compared between experimental studies and simulation studies. The electric field average value resulted from ECCT helmet-1 is higher than ECCT helmet-2. The average electric field generated by the ECCT helmet-1 is 1585.72 V/m in an air medium, 97.43 V/m in grey matter and 80.58 V/m in the cancer. While the average electric field generated by the ECCT helmet-2 is 1413.28 V/m in an air medium, 64.20 V/m in grey matter and 52.65 V/m in the cancer. ECCT helmet-1 and helmet-2 result the different of electric field distribution pattern. ECCT helmet-1 is more optimal for used to patient has cancer position in the right and bottom, while ECCT helmet-2 is more optimal for used to patient has cancer position in the top and bottom.

Экспериментальные исследования таунсендовского разряда с многоострийным катодом на динамической платформе из магнитоуправляемых частиц Fe и Fe-Al

Experimental results of the Townsend discharge in the air gap and atmospheric pressure from a multi-pin cathode based on a dynamic platform of magnetically controlled Fe and Fe-Al particles presented. Dynamic platform method formation from magnetically controlled particles for cathode surface presented. The current-voltage characteristics are obtained for various configurations of the cathode design (with a flat electrode without magnetically controlled particles, with a multi-pin cathode with magnetically controlled Fe or Fe-Al particles), as well as with the presence of a heated spiral in the electrode gap. The use of a multi-pin cathode based on the dynamic platform of magnetically controlled Fe and Fe-Al particles allows to maintain the average electric field strength in the discharge gap and to increase the spark discharge current.

Field of a moving locked charge in classical electrodynamics

The paradox of a field of a moving locked charge (confined in a closed space) is considered and solved with the use of the integral Maxwell equations. While known formulas obtained for instantaneous fields of charges moving along straight and curved lines are fully correct, measurable quantities are average electric and magnetic fields of locked charges. It is shown that the average electric field of locked charges does not depend on their motion. The average electric field of protons moving in nuclei coincides with that of protons being at rest and having the same spatial distribution of the charge density. The electric field of a twisted electron is equivalent to the field of a centroid with immobile charges whose spatial distribution is defined by the wave function of the twisted electron.

SCHEEPDOG: programming electric cues to dynamically herd large-scale cell migration

Directed cell migration is critical across biological processes spanning healing to cancer invasion, yet no existing tools allow real-time interactive guidance over such migration. We present a new bioreactor that harnesses electrotaxis—directed cell migration along electric field gradients—by integrating four independent electrodes under computer control to dynamically program electric field patterns, and hence steer cell migration. Using this platform, we programmed and characterized multiple precise, two-dimensional collective migration maneuvers in renal epithelia and primary skin keratinocyte ensembles. First, we demonstrated on-demand, 90-degree collective turning. Next, we developed a universal electrical stimulation scheme capable of programming arbitrary 2D migration maneuvers such as precise angular turns and migration in a complete circle. Our stimulation scheme proves that cells effectively time-average electric field cues, helping to elucidate the transduction time scales in electrotaxis. Together, this work represents an enabling platform for controlling cell migration with broad utility across many cell types.

Computational comparison of conventional and novel electroconvulsive therapy electrode placements for the treatment of depression

Background:Electroconvulsive therapy (ECT) is a highly effective treatment for severe psychiatric disorders. Despite its high efficacy, the use of ECT would be greater if the risk of cognitive side effects were reduced. Over the last 20 years, developments in ECT technique, including improvements in the dosing methodology and modification of the stimulus waveform, have allowed for improved treatment methods with reduced adverse cognitive effects. There is increasing evidence that the electrode placement is important for orienting the electrical stimulus and therefore modifying treatment outcomes, with potential for further improvement of the placements currently used in ECT.Objective:We used computational modelling to perform an in-depth examination into regional differences in brain excitation by the ECT stimulus for several lesser known and novel electrode placements, in order to investigate the potential for an electrode placement that may optimise clinical outcomes.Methods:High resolution finite element human head models were generated from MRI scans of three subjects. The models were used to compare regional differences in average electric field (EF) magnitude among a total of thirteen bipolar ECT electrode placements, i.e. three conventional placements as well as ten lesser known and novel placements.Results and conclusion:In this exploratory study on a systemic comparison of thirteen ECT electrode placements, the EF magnitude at regions of interest (ROIs) was highly dependent upon the position of both electrodes, especially the ROIs close to the cortical surface. Compared to conventional right-unilateral (RUL) ECT using a temporo-parietal placement, fronto-parietal and supraorbito-parietal RUL also robustly stimulated brain regions considered important for efficacy, while sparing regions related to cognitive functions, and may be a preferrable approach to the currently used placement for RUL ECT. The simulations also found that regional average EF magnitude varied between individual subjects, due to factors such as head size, and results also depended on the size of the defined ROI.

Experimental Study of the Influence of Ink Properties and Process Parameters on Ejection Volume in Electrohydrodynamic Jet Printing

Electrohydrodynamic jet (e-jet) printing has very promising applications due to its high printing resolution and material compatibility. It is necessary to know how to choose the printing parameters to get the right ejection volume. The previous scaling law of the ejection volume in e-jet printing borrows the scaling law of the ejection volume of an unstable isolated droplet charged to the Rayleigh limit. The influence of viscosity, applied voltage amplitude, and nozzle-to-substrate distance on the ejection volume in e-jet printing was not taken into account in the scaling law. This study investigated the influence of viscosity, conductivity, applied voltage, and nozzle-to-substrate distance on the ejection volume. The ejection volume increases with viscosity and decreases with applied voltage and nozzle-to-substrate distance. The average electric field was kept unchanged while changing the nozzle-to-substrate distance by changing the applied voltage according to the electric field model of a semi-infinite wire perpendicular to an infinite large planar counter electrode. The ejection volume decreases with conductivity as V ~ K − 0.6 , which is different from the previous scaling law, which concludes that V ~ K − 1 . Finally, a model about the relation between the ejection volume and four parameters was established by regression analysis using a third-order polynomial. Two more experiments were done, and the predicted results of the fitted model accorded well with the experiments. The model can be used to choose the ink properties and process parameters to get the right ejection volume.

Three-Terminal Amorphous Silicon Solar Cells

Many defects exist within amorphous silicon since it is not crystalline. This provides recombination centers, thus reducing the efficiency of a typical a-Si solar cell. A new structure is presented in this paper: a three-terminal a-Si solar cell. The new back-to-back p-i-n/n-i-p structure increased the average electric field in a solar cell. A typical a-Si p-i-n solar cell was also simulated for comparison using the same thickness and material parameters. The 0.28 μm-thick three-terminal a-Si solar cell achieved an efficiency of 11.4%, while the efficiency of a typical a-Si p-i-n solar cell was 9.0%. Furthermore, an efficiency of 11.7% was achieved by thickness optimization of the three-terminal solar cell.

Ross Ice Shelf (Antarctica) in situ radio-frequency attenuation

We have measured the in situ average electric field attenuation length, 〈Lα〉, for radio-frequency signals broadcast vertically through the Ross Ice Shelf, Antarctica. We chose a location, Moore Embayment, south of Minna Bluff, known for its high reflectivity at the ice–sea interface. We confirmed specular reflection and used the return pulses to measure the average attenuation length from 75–1250 MHz over the round-trip distance of 1155 m. We find 〈Lα〉 to vary from ∼500 m at 75 MHz to ∼300 m at 1250 MHz, with an experimental uncertainty of 55–15 m.

The large-scale magnetospheric electric field observed by Double Star TC-1

The relationship between the average structure of the inner magnetospheric large-scale electric field and geomagnetic activity levels has been investigated by Double Star TC-1 data for radial distances ρ between 4.5 RE and 12.5 RE and MLT between 18:00 h and 06:00 h from July to October in 2004 and 2005. The sunward component of the electric field decreases monotonically as ρ increases and approaches zero as the distance off the Earth is greater than 10 RE. The dawn-dusk component is always duskward. It decreases at about 6 RE where the ring current is typically observed to be the strongest and shows strong asymmetry with respect to the magnetic local time. Surprisingly, the average electric field obtained from TC-1 for low activity is almost comparable to that observed during moderate activity, which is always duskward at the magnetotail (8 RE~12 RE).

Comparative Analysis of Electric Field Measurement in Zaria

This paper presents the comparative analysis of the measurement of static electric field within and outside the test location in Zaria, Nigeria, based on the measurement carried out using a data acquisition system, interfaced with a digital electrostatic field strength meter (model 257D). The acquired electric field data are captured by a computer using the Microsoft Office Excel Program. The focus of the analysis is determining the effect of environmental factors such as temperature, pressure and relative humidity on the static electric field during the harmattan (March) and non-harmattan period (April – May). The plots of the average electric field against the variation of the environmental factors were used as the qualitative analytical tools and conclusion was drawn to the fact that the relative variation in the measurement of the electric field within and outside the test location is averagely 0.06KV/cm and dependent on the environmental factors.