Variable Pulse Amplitude Research Articles

Experimental study on pulse characteristics of negative corona discharge in SF6/N2 gas mixtures under DC voltages

Corona discharge, an inevitable phenomenon, may lead to insulation degradation, threatening the safe and reliable operation of gas-insulated power equipment. The pulse stage is a complex but usual discharge process in corona discharge. In this paper, we investigate the pulse characteristics of negative corona discharge in a needle-to-plane electrode configuration in SF6/N2 gas mixtures under DC voltages. With an increase in mean current, a stage transition phenomenon from the Townsend stage through the pulse stage to the breakdown stage is observed. The variation in pulse amplitude and pulse time characteristics at the pulse stage is analyzed. In addition, the effects of gas pressure, gap spacing, and N2 content on onset voltage and pulse characteristic parameters, including pulse time parameters and the pulse repetition rate, at the pulse stage are presented. The results show that the current pulses mainly exhibit an irregular distribution of small amplitude. The pulse time parameters are not affected by gas pressure, gap spacing, or N2 content at pressures higher than 0.1 MPa. The pulse repetition rate decreases with an increase in gas pressure and N2 content but is only weakly affected by gap spacing, ranging from 1 kHz to dozens of kHz.

Development of Radial Artery Pulse Audiogram Sensing System for Fast Detection of Atrial Fibrillation and Pulse Amplitude Variation

Background: A new wearable pulse audiogram (PAG) of radial artery was developed with the main purpose to quickly screen atrial fibrillation (AF) and monitor pulse amplitude variation. Methods: Subjects with sinus rhythm (SR), AF, ectopic arrhythmia (EA), and a pacemaker rhythm (PM) were recruited to measure the PAG of radial artery. In total, 91 subjects were recruited: SR ( $n =45$ ), AF ( $n =21$ ), EA ( $n =11$ ), and PM ( $n =14$ ). For signal processing, the inter-pulse interval (IPI) and pulse height (PH) were extracted. Then, an automatic classification algorithm combining fuzzy c-means (FCM) or sample entropy (CEn) with an adaptive-network-based fuzzy inference system was constructed. The PAG data were divided into different segment lengths (10 to 30 beats) to investigate the robustness of the algorithm in short intervals. Furthermore, linear regression was performed to evaluate the relation between the normalized IPI and PH in the AF group. Results: The identification rate of AF increased with the number of beats and decreased with the number of classified types of arrhythmia. Results of combining CEn and FCM, or of FCM alone were better than those of CEn alone. When the combined method was used for the two types of arrhythmia and the number of beats was greater than 10, the rate of successful identification was greater than 90%, validating the technique. Furthermore, for the AF group, PH increased with IPI, while the amplitude of electrocardiogram (ECG) did not. Conclusions: Results indicated that our PAG can effectively identify AF, even in a time window as short as 10 beats. In addition, PAG can monitor the trend of pulse amplitude, possibility that cannot be offered by an ECG.

Finger and forehead PPG signal comparison for respiratory rate estimation

Objective: An evaluation of the location of the photoplethysmogram (PPG) sensor for respiratory rate estimation is performed. Approach: Finger PPG, forehead PPG, and respiratory signal were simultaneously recorded from 35 subjects while breathing spontaneously, and during controlled respiration experiments at a constant rate from 0.1 Hz to 0.6 Hz, in 0.1 Hz steps. Four PPG-derived respiratory (PDR) signals were extracted from each one of the recorded PPG signals: pulse rate variability (PRV), pulse width variability, pulse amplitude variability and the respiratory-induced intensity variability (RIIV). Respiratory rate was estimated from each one of the four PDR signals for both PPG sensor locations. In addition, different combinations of PDR signals, power distribution of the respiratory frequency range and differences of the morphological parameters extracted from both PPG signals have been analysed. Main results: Results show better performance in terms of successful estimation and relative error when: (i) PPG signal is recorded in the finger; (ii) the respiratory rate is less than 0.4 Hz; (iii) RIIV signal is not considered. Furthermore, lower spectral power around the respiratory rate in the PDR signals recorded from the forehead was observed. Significance: These results suggest that respiratory rate estimation is better at lower rates (0.4 Hz and below) and that the finger is better than the forehead to estimate respiratory rate.

Hybrid analytical-numerical approach for investigation of differential effects in normal and cancer cells under electroporation.

Electroporation has offered important biomedical applications in electrochemotherapy, tissue ablation and gene editing recently. Time and computation efficient analytical and numerical models should be developed to understand the differential effects of electroporation on normal and cancer cells. In this work, we present a hybrid analytical–numerical approach to investigate the behavior of normal and cancer cells under electroporation. We have compared the human breast cancer cell (MCF-7) and non-tumorigenic human breast cell (MCF-10A) under electroporation in terms of change in transmembrane voltage and pore formation on cell surface. The effects of electric pulse time, amplitude and membrane conductivity variation are analyzed in a systematic manner. To accelerate the calculation of transmembrane voltage, we have introduced a simple Multilayer Electric Potential Model (MEPM) which calculates the potential distribution across the cell analytically. The MEPM calculates electric potential distribution across a biological cell sandwiched between two semi-circular electrodes held at fixed potential, by solving the Laplace's equation over an equivalent planar, multilayer geometry. The MEPM model is then used in a Finite Element Method (FEM) based numerical model of electroporation. Transmembrane voltage and pore density for electroporated MCF-10A are estimated to be 1.31 V and 2.98 × 1013 m−2 respectively, and for MCF-7 the estimated values are 0.53 V and 1.93 × 1014 m−2, respectively. Our results suggest that under electroporation, the cancer cell's membrane get much more permeabilized than its counterpart normal cell even at small values of transmembrane voltage. This work provides a theoretical basis for further experimental exploration of electroporation process in cancer therapy, and serves as a design tool for performance optimization.

마취 중 통증판별을 위한 광용적맥파 박동간격 및 진폭 변화 관찰

마취 중 통증판별을 위한 광용적맥파 박동간격 및 진폭 변화 관찰

Pulsatile flow drivers in brain parenchyma and perivascular spaces: a resistance network model study

BackgroundIn animal models, dissolved compounds in the subarachnoid space and parenchyma have been found to preferentially transport through the cortex perivascular spaces (PVS) but the transport phenomena involved are unclear.MethodsIn this study two hydraulic network models were used to predict fluid motion produced by blood vessel pulsations and estimate the contribution made to solute transport in PVS and parenchyma. The effect of varying pulse amplitude and timing, PVS dimensions, and tissue hydraulic conductivity on fluid motion was investigated.ResultsPeriodic vessel pulses resulted in oscillatory fluid motion in PVS and parenchyma but no net flow over time. For baseline parameters, PVS and parenchyma peak fluid velocity was on the order of 10 μm/s and 1 nm/s, with corresponding Peclet numbers below 103 and 10−1 respectively. Peak fluid velocity in the PVS and parenchyma tended to increase with increasing pulse amplitude and vessel size, and exhibited asymptotic relationships with hydraulic conductivity.ConclusionsSolute transport in parenchyma was predicted to be diffusion dominated, with a negligible contribution from convection. In the PVS, dispersion due to oscillating flow likely plays a significant role in PVS rapid transport observed in previous in vivo experiments. This dispersive effect could be more significant than convective solute transport from net flow that may exist in PVS and should be studied further.

The interphase interval within a bipolar nanosecond electric pulse modulates bipolar cancellation.

Nanosecond electric pulse (nsEP) exposure generates an array of physiological effects. The extent of these effects is impacted by whether the nsEP is a unipolar (UP) or bipolar (BP) exposure. A 600 ns pulse can generate 71% more YO-PRO-1 uptake compared to a 600 ns + 600 ns pulse exposure. This observation is termed "bipolar cancellation" (BPC) because despite the BP nsEP consisting of an additional 600 ns pulse, it generates reduced membrane perturbation. BPC is achieved by varying pulse amplitudes, and symmetrical and asymmetric pulse widths. The effect appears to reverse by increasing the interphase interval between symmetric BP pulses, suggesting membrane recovery is a BPC factor. To date, the impact of the interphase interval between asymmetrical BP and other BPC-inducing symmetrical BP nsEPs has not been fully explored. Additionally, interpulse intervals beyond 50 μs have not been explored to understand the impact of time between the BP nsEP phases. Here, we surveyed different interphase intervals among symmetrical and asymmetrical BP nsEPs to monitor their impact on BPC of YO-PRO-1 uptake. We identified that a 10 microsecond (ms) interphase interval within a symmetrical 600 ns + 600 ns, and 900 ns + 900 ns pulse can resolve BPC. Furthermore, the interphase interval to resolve asymmetric BPC from a 300 ns + 900 ns pulse versus 600 ns pulse exposure is greater (<10 ms) compared to symmetrical BP nsEPs. From these findings, we extended on our conceptual model that BPC is balanced by localized charging and discharging events across the membrane. Bioelectromagnetics. 39:441-450, 2018. Published 2018. This article is a U.S. Government work and is in the public domain in the USA.

Finger and forehead photoplethysmography-derived pulse-pressure variation and the benefits of baseline correction

To non-invasively predict fluid responsiveness, respiration-induced pulse amplitude variation (PAV) in the photoplethysmographic (PPG) signal has been proposed as an alternative to pulse pressure variation (PPV) in the arterial blood pressure (ABP) signal. However, it is still unclear how the performance of the PPG-derived PAV is site-dependent during surgery. The aim of this study is to compare finger- and forehead-PPG derived PAV in their ability to approach the value and trend of ABP-derived PPV. Furthermore, this study investigates four potential confounding factors, (1) baseline variation, (2) PPV, (3) ratio of respiration and heart rate, and (4) perfusion index, which might affect the agreement between PPV and PAV. In this work, ABP, finger PPG, and forehead PPG were continuously recorded in 29 patients undergoing major surgery in the operating room. A total of 91.2 h data were used for analysis, from which PAV and PPV were calculated and compared. We analyzed the impact of the four factors using a multiple linear regression (MLR) analysis. The results show that compared with the ABP-derived PPV, finger-derived PAV had an agreement of 3.2 ± 5.1%, whereas forehead-PAV had an agreement of 12.0 ± 9.1%. From the MLR analysis, we found that baseline variation was a factor significantly affecting the agreement between PPV and PAV. After correcting for respiration-induced baseline variation, the agreements for finger- and forehead-derived PAV were improved to reach an agreement of − 1.2 ± 3.8% and 3.3 ± 4.8%, respectively. To conclude, finger-derived PAV showed better agreement with ABP-derived PPV compared to forehead-derived PAV. Baseline variation was a factor that significantly affected the agreement between PPV and PAV. By correcting for the baseline variation, improved agreements were obtained for both the finger and forehead, and the difference between these two agreements was diminished. The tracking abilities for both finger- and forehead-derived PAV still warrant improvement for wide use in clinical practice. Overall, our results show that baseline-corrected finger- and forehead-derived PAV may provide a non-invasive alternative for PPV.

Effects of electrical stimulus composition on cardiac electrophysiology in a rodent model of electroconvulsive therapy.

Background:No electroconvulsive therapy (ECT) study on humans or in animal models has so far examined whether differently composed electrical stimuli exert different cardiac electrophysiological effects at constant electrical dose. The subject is important because cardiac electrophysiological changes may provide indirect information about ECT seizure quality as modulated by stimulus composition.Materials and Methods:Adult female Wistar rats (n = 20/group) received fixed, moderately suprathreshold (18 mC) electrical stimuli. This stimulus in each of eight groups was formed by varying pulse amplitude, pulse width, pulse frequency, and stimulus duration. The electrocardiogram was recorded, and time and frequency domain variables were examined in 30 s epochs in preictal (30 s before electroconvulsive shock [ECS]), early postictal (starting 15 s after stimulation), and late postictal (5 h after ECS) periods. Alpha for statistical significance was set at P < 0.01 to adjust for multiple hypothesis testing.Results:Cardiac electrophysiological indices in the eight groups did not differ significantly at baseline. At both early and late postictal time points, almost no analysis yielded statistically significant differences between groups for four time domain variables, including heart rate and standard deviation of R-R intervals, and for six frequency domain variables, including low-frequency power, high-frequency power, and total power.Conclusions:Cardiac electrophysiological measures may not be helpful to identify differences in seizure quality that are driven by differences in the composition of electrical stimuli at constant, moderately suprathreshold electrical dose. The generalization of this conclusion to threshold electrical doses and to human contexts requires a study.

Characteristics of multilevel storage and switching dynamics in resistive switching cell of Al2O3/HfO2/Al2O3 sandwich structure

We reported an Al2O3/HfO2/Al2O3 sandwich structure resistive switching device with significant improvement of multilevel cell (MLC) operation capability, which exhibited that four stable and distinct resistance states (one low resistance state and three high resistance states) can be achieved by controlling the Reset stop voltages (VReset-stop) during the Reset operation. The improved MLC operation capability can be attributed to the RHRS/RLRS ratio enhancement resulting from increasing of the series resistance and decreasing of leakage current by inserting two Al2O3 layers. For the high-speed switching applications, we studied the initial switching dynamics by using the measurements of the pulse width and amplitude dependence of Set and Reset switching characteristics. The results showed that under the same pulse amplitude conditions, the initial Set progress is faster than the initial Reset progress, which can be explained by thermal-assisted electric field induced rupture model in the oxygen vacancies conductive filament. Thus, proper combination of varying pulse amplitude and width can help us to optimize the device operation parameters. Moreover, the device demonstrated ultrafast program/erase speed (10 ns) and good pulse switching endurance (105 cycles) characteristics, which are suitable for high-density and fast-speed nonvolatile memory applications.

A new method for compensation of the effect of charging transformer's leakage inductance on PFN voltage regulation in Klystron pulse modulators

The Line type modulators have been widely used to generate high voltage rectangular pulses to power the klystron for high power RF generation. In Line type modulator, the Pulse Forming Network (PFN) which is a cascade combination of lumped capacitors and inductors is used to store the electrical energy. The charged PFN is then discharged into a klystron by firing a high voltage Thyratron switch. This discharge generates a high voltage rectangular pulse across the klystron electrodes. The amplitude and phase of Klystron's RF output is governed by the high voltage pulse amplitude. The undesired RF amplitude and phase stability issues arises at the klystron's output due to inter-pulse and during the pulse amplitude variations. To reduce inter-pulse voltage variations, the PFN is required to be charged at the same voltage after every discharge cycle. At present, the combination of widely used resonant charging and deQing method is used to regulate the pulse to pulse PFN voltage variations but the charging transformer's leakage inductance puts an upper bound on the regulation achievable by this method. Here we have developed few insights of the deQing process and devised a new compensation method to compensate this undesired effect of charging transformer's leakage inductance on the pulse to pulse PFN voltage stability. This compensation is accomplished by the controlled partial discharging of the split PFN capacitor using a low voltage MOSFET switch. Theoretically, very high values of pulse to pulse voltage stability may be achieved using this method. This method may be used in deQing based existing modulators or in new modulators, to increase the pulse to pulse voltage stability, without having a very tight bound on charging transformer's leakage inductance. Given a stable charging power supply, this method may be used to further enhance the inter-pulse voltage stability of modulators which employ the direct charging, after replacing the direct charging with the resonant charging.

Optical measures of changes in cerebral vascular tone during voluntary breath holding and a Sternberg memory task

The human cerebral vasculature responds to changes in blood pressure and demands for oxygenation via cerebral autoregulation. Changes in cerebrovascular tone (vasoconstriction and vasodilation) also mediate the changes in blood flow measured by the BOLD fMRI signal. This cerebrovascular reactivity is known to vary with age. In two experiments, we demonstrate that cerebral pulse parameters measured using optical imaging can quantify changes in cerebral vascular tone, both globally and locally. In experiment 1, 51 older adults (age range=55–87) performed a voluntary breath-holding task while cerebral pulse amplitude measures were taken. We found significant pulse amplitude variations across breath-holding periods, indicating vasodilation during, and vasoconstriction after breath holding. The breath-holding index (BHI), a measure of cerebrovascular reactivity (CVR) was derived and found to correlate with age. BHI was also correlated with performance in the Modified Mini-Mental Status Examination, even after controlling for age and education. In experiment 2, the same participants performed a Sternberg task, and changes in regional pulse amplitude between high (set-size 6) and low (set-size 2) task loads were compared. Only task-related areas in the fronto-parietal network (FPN) showed significant reduction in pulse amplitude, indicating vasodilation. Non-task-related areas such as the somatosensory and auditory cortices did not show such reductions. Taken together, these experiments suggest that optical pulse parameters can index changes in brain vascular tone both globally and locally, using both physiological and cognitive load manipulations.

Respiratory rate derived from smartphone-camera-acquired pulse photoplethysmographic signals

A method for deriving respiratory rate from smartphone-camera-acquired pulse photoplethysmographic (SCPPG) signal is presented. Our method exploits respiratory information by examining the pulse wave velocity and dispersion from the SCPPG waveform and we term these indices as the pulse width variability (PWV). A method to combine information from several derived respiration signals is also presented and it is used to combine PWV information with other methods such as pulse amplitude variability (PAV), pulse rate variability (PRV), and respiration-induced amplitude and frequency modulations (AM and FM) in SCPPG signals.Evaluation is performed on a database containing SCPPG signals recorded from 30 subjects during controlled respiration experiments at rates from 0.2 to 0.6 Hz with an increment of 0.1 Hz, using three different devices: iPhone 4S, iPod 5, and HTC One M8. Results suggest that spontaneous respiratory rates (0.2–0.4 Hz) can be estimated from SCPPG signals by the PWV- and PRV-based methods with low relative error (median of order 0.5% and interquartile range of order 2.5%). The accuracy can be improved by combining PWV and PRV with other methods such as PAV, AM and/or FM methods. Combination of these methods yielded low relative error for normal respiratory rates, and maintained good performance at higher rates (0.5–0.6 Hz) when using the iPhone 4S or iPod 5 devices.

Comparison of Twitch Responses During Current‐ or Voltage‐Controlled Transcutaneous Neuromuscular Electrical Stimulation

Neuromuscular electrical stimulation (NMES) is an established method for functional restoration of muscle function, rehabilitation, and diagnostics. In this work, NMES was applied with surface electrodes placed on the anterior thigh to identify the main differences between current-controlled (CC) and voltage-controlled (VC) modes. Measurements of the evoked knee extension force and the myoelectric signal of quadriceps and hamstrings were taken during stimulation with different amplitudes, pulse widths, and stimulation techniques. The stimulation pulses were rectangular and symmetric biphasic for both stimulation modes. The electrode-tissue impedance influences the differences between CC and VC stimulation. The main difference is that for CC stimulation, variation of pulse width and amplitude influences the amount of nerve depolarization, whereas VC stimulation is only dependent on amplitude variations for pulse widths longer than 150 μs. An important remark is that these findings are strongly dependent on the characteristics of the electrode-skin interface. In our case, we used large stimulation electrodes placed on the anterior thigh, which cause higher capacitive effects. The controllability, voltage compliance, and charge characteristics of each stimulation technique should be considered during the stimulators design. For applications that require the activation of a large amount of nerve fibers, VC is a more suitable option. In contrast, if the application requires a high controllability, then CC should be chosen prior to VC.

Traditional Indian Medicine (TIM) based Humor Identification A recurrence based Approach

Objective analysis and interpretation of radial pulse signal has been attempted. Capacitance variation based sensing and instrumentation mechanism has been developed for pulse sensing and logging. Traditional Indian Medicine (TIM) perspective for humor identification has been attempted. Pulse signal of healthy individual analysed in dominant humor interval, display prominent changes in recurrence quantification measures for pulse amplitude variations. These marker results are observed to correlate strongly with those obtained for a group of healthy individuals in a dominant humor interval period. Recurrence quantification analysis can possibly help in arriving at inferences apparent to sense perception for a TIM physician. General Terms Biomedical Signal Processing, Traditional Indian Medicine(TIM) – Ayurveda.

Clinical Feasibility Trial for Transtracheal Stimulation of Vocal Fold Closure in Sensate Human Subjects

Objectives: (1) Apply transtracheal stimulation (TTS) of the recurrent laryngeal nerve (RLN) for vocal fold closure (VFC) in sensate humans. (2) Characterize tracheal sensory response to electrical stimuli. Methods: Patients with chronic tracheostomies were selected for a “first-in-man” clinical device trial to stimulate the RLN through tracheal tissue for VFC. Etiologies of trach dependence varied, but all subjects had normal laryngeal sensation, vocal cord mobility, and RLN function. Devices were introduced through subjects’ ostomies, and electrodes were subsequently deployed for tracheal contact. Videoendoscopy recorded responses to square wave pulse trains of varying pulse amplitude (PA) and pulse width (PW; 0.5 mA-5 mA and 60 us-500 us, respectively). Subjects were surveyed for sensory changes, discomfort, and pain. Results: TTS of the RLN successfully elicited VFC in all subjects. The PA threshold for closure (ThPA; at PW = 200 us) ranged from 1.5 mA to 3.5 mA unilaterally, and 1.0 mA to 2.5 mA bilaterally for all subjects except 1 outlier with thresholds of 0.9 mA and 1.2 mA unilaterally, and 0.7 mA bilaterally. PW thresholds (ThPW) ranged from 100 us to 300 us for all subjects (PA = 0.75 × ThPA). All subjects denied pain, but 3 described mild incremental “tingling” that initiated cough or swallow responses only at suprathreshold levels. Conclusions: TTS initiated arytenoid medialization for VFC in all subjects without pain or significant discomfort. This study presents a novel technique for noninvasive restoration of VFC in humans. Further trials will determine full clinical utility of this device component, individually and in conjunction with components targeting swallow detection and laryngeal elevation for coordinated airway protection.

Time-Domain Characterization of Short-Pulse Networks and Antennas Using Signal Space Method

Signal space method for time-domain characterization of short-pulse networks and antennas is presented and described. The short-duration pulses, which are usually recognized as energy signals, belong to the signal space L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (ℜ). By means of the signal space analysis, the Euclid distance on L <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> (ℜ) is related to fidelity and amplitude ratio, and thus can be used for comprehensively characterizing short-duration pulse waveform distortion and amplitude variation, resulting in an overall description of networks and antennas. Three numerical examples, microstrip transmission line, microstrip pulse power divider, and antipodal Vivaldi antenna, are given to demonstrate the usage and significance of this method for characterization of networks and antennas.

광용적맥파 신호를 이용한 수면 중 호흡 추정

Respiratory signal is one of the important physiological information indicating the status and function of the body. Recent studies have provided the possibility of being able to estimate the respiratory signal by using a change of PWV(pulse width variability), PRV(pulse rate variability) and PAV(pulse amplitude variability) in the PPG (photoplethysmography) signal during daily life. But, it is not clear whether the respiratory monitoring is possible even during sleep. Therefore, in this paper, we estimated the respiration from PWV, PRV and PAV of PPG signals during sleep. In addition, respiration rates of the estimated respiration signal were calculated through a time-frequency analysis, and errors between respiration rates calculated from each parameter and from reference signal were evaluated in terms of 1 sec, 10 sec and 1 min. As a result, it showed the errors in PWV(1s: <TEX>$36.38{\pm</TEX><TEX>}37.69$</TEX> mHz, 10s: <TEX>$36.53{\pm}38.16$</TEX> mHz, 60s: <TEX>$30.35{\pm}38.72$</TEX> mHz), in PRV(1s: <TEX>$1.45{\pm}1.38$</TEX> mHz, 10s: <TEX>$1.44{\pm}1.37$</TEX> mHz, 60s: <TEX>$0.45{\pm}0.56$</TEX> mHz), and in PAV(1s: <TEX>$1.05{\pm}0.81$</TEX> mHz, 10s: <TEX>$1.05{\pm}0.79$</TEX> mHz, 60s: <TEX>$0.56{\pm}0.93$</TEX> mHz). The errors in PRV and PAV are lower than that of PWV. Finally, we concluded that PRV and PAV are more effective than PWV in monitoring the respiration in daily life as well as during sleep.

Study of the 26 December 2011 Aswan earthquake, Aswan area, South of Egypt

The source process and parameters for a moderate earthquake of magnitude Ml 4.1 that occurred on the Kalabsha fault at the Aswan area are analyzed. The derived focal mechanisms of this event and other two aftershocks using polarities of P, SV, and SH waves show strike-slip fault with minor vertical movement of normal type. The solutions give two nodal planes trending ENE–WSW and NNW–SSE in close agreement with the surface traces of the faults crossing the area. The movement is right lateral along the first plane while left lateral along the second one. The rupture process characterization of this event has been investigated by using the empirical Green’s function deconvolution method. By inversion only for the P wave part of the records of these three events (main and other two aftershocks), the source time function for the master events and the azimuthally variations in the (RSTF) pulse amplitude are retrieved for estimating the rupture directivities. The estimated rupture direction is combined with the P-wave focal mechanisms for the three events to identify the fault plane solution for these earthquakes. Based on the width, amplitudes, and numbers of the isolated source time functions, a complex bi-lateral rupture of the studied earthquake is delineated. The source parameters of the master event is calculated and the derived corner frequencies fo for P-wave spectra show a value of 6.6 Hz; the seismic moment (Mo) is 4.2 × 1022 Nm; the average displacement (U) is 0.5 m; fault radius (r) 40 m; the average value of the stress drops (Δσ) is 0.6 Mpa, and the moment magnitude (Mw) is 4.4.

NsPEF-induced effects on cell membranes: use of electrophysical model to optimize experimental design

A numerical model, usually employed to analyze the electroporation phenomenon in eukaryotic cells exposed to high voltage electric pulses with duration in the ms to ?s time scale, is extended to investigate the electroporation onset and dynamics induced by nanosecond pulsed electric fields (nsPEFs). The model allows to track the primary events and dynamics of the electroporation process on a time scale where available experimental methods do not provide reliable information. In particular the model, solved in the time domain, provides the spatial and temporal distribution of the transmembrane voltage and pore density of fixed radii around the plasma membrane. Moreover, it allows to optimize the experimental design of biological investigations in the framework of the mechanistic understanding of nsPEF. The obtained simulation results are correlated to biological observations of plasma membrane permeabilization in human lymphoblastoid Jurkat T-cells exposed to nsPEFs with variable pulse amplitude, as assessed by YO-PRO1 dye uptake.