Pulsed Measurements Research Articles

A novel handheld ultrasound device equipped with spectral doppler- efficacy of left ventricle diastolic function parameters assessment

Abstract Background Echocardiographic assessment of left ventricular (LV) diastolic function is an essential part of the routine evaluation of patients presenting with dyspnea or impaired effort tolerance. Diagnostic algorithm of diastolic dysfunction involves pulsed and continuous wave Doppler measurements, which were not within the range of capabilities of previous generations of handheld ultrasound devices (HUD). However, implementing new modalities into HUD expanded the area in which they may thrive. Aim To verify and validate the reliability of diastolic function parameters acquired during the HUD echocardiographic examination Methods Study population consisted of the consecutive 100 pts admitted to Cardiology Emergency Room due to the dyspnea and/or impaired effort tolerance. All patients underwent brief bedside echocardiographic screening with HUD which involved the assessment of mitral inflow velocities- early (E) and late (A), septal and lateral mitral annular peak early diastolic velocity (e')- measured with the pulsed wave Doppler modality, E/E’ ratio, E/A ratio, and tricuspid regurgitation velocity (measured with the continuous wave Doppler modality). Within the next 24 hours all patients underwent full echocardiographic examination performed with the use of stationary ultrasonographic station, which results were treated as reference. Results Septal E’ did not exceed 7cm/s in 22 patients, lateral E’ was lower than 10cm/s in 24 patients. Correlation between the measurements from HUD and full echocardiography was 0,84 for septal E’ and 0,44 for lateral E’; for both parameters agreement for detection of incorrect, lowered values between methods was high (Kappa coefficient 0,751 i 0,8 respectively). E/E’ was significantly increased in 6 patients, which was detected with high agreement in HUD examination (Kappa coefficient 0,73). Correlation coefficient for E/A parameter was 0,77 and agreement categorized for each group (E/A≤0,8; E/A >0,8 & <2; E/A ≥2 ) was high (kappa coefficient 0,75; 0,74; 1,0 respectively); it is worth noting that all cases with E/A ≥2 were identified in HUD examination. TR velocity exceeded 2,8 m/s in 11pts, in this aspect the agreement between HUD and full examination was 0,65. However the positive predictive value of this parameter was 100%. Conclusion HUD equipped with a spectral doppler modality enables for reliable echocardiographic screening of LV diastolic function. Introducing the elements of imaging diagnostics to the initial assessment might markedly hasten the establishing of the final diagnosis. E/A ratio- HUD & full echocardiography HUD/fullECHO derived values correlation

Measurement of the 13S1→23S1 interval in positronium using field ionization of Rydberg states

We report a 40 parts per 109 measurement of the positronium 13S1→23S1 interval using pulsed two-photon optical spectroscopy. The transition is detected via field ionization of atoms excited from the 2S to the 20P Rydberg state. Precise Monte Carlo line-shape simulations allow for the accounting of effects such as Doppler and ac Stark shifts, while an optical heterodyne measurement of the excitation laser pulse is used to correct for laser frequency chirp. A value of 1233607210.5±49.6MHz is obtained. This scheme allows for the measurement of the velocity distribution of positronium atoms to correct for the second-order Doppler effect. This is a major source of systematic uncertainty expected for future measurements of this transition with a cw laser; thus, our technique paves the way toward a new generation of a high-precision determination of this interval in positronium. Published by the American Physical Society 2025

Measurement of femtosecond incoherent XUV pulses using shot-noise-driven fluctuations in plasma betatron sources

Measurement of femtosecond incoherent XUV pulses using shot-noise-driven fluctuations in plasma betatron sources

Measurement of Laser Pulse Energy and Duration Through Air Induced Breakdown Under Electric Field Action

Measurement of Laser Pulse Energy and Duration Through Air Induced Breakdown Under Electric Field Action

Development of a novel high-frequency reciprocal structure fiber optical pulsed current sensor.

A novel all-fiber optic current sensor (FOCS) is designed specifically for the measurement of large transient currents based on the Faraday effect. A reciprocal symmetric structure is incorporated into the optical sensing loop, and the current dependent phase demodulation is achieved by using a passive optical fiber coupler and the homodyne detection scheme. This design offers several advantages, including structural simplicity, high voltage insulation, low noise, high linearity, and excellent frequency response, and is highly suitable for use in any system of high-voltage, high-power, and high-frequency in nature. A current source based on fast capacitor discharge is used for the bench-test of the FOCS system, and several laser sources with different wavelengths and linewidths have been used to test the FOCS performance. Experimental results show that the phase noise of the laser is independent of both wavelength and linewidth. The sensitivity of the FOCS system has been calibrated against a commercial Rogowski current sensor. This FOCS offers precise and flexible high-current pulse measurements with a measured phase noise of 1.4 × 10-3rad, using a 1550nm laser with a 1kHz linewidth. The fully reciprocal sensing loop ensures that the phase noise remains unchanged as the loop length increases. These features make the FOCS a robust and adaptable tool for high-precision current sensing in challenging environments. Finally, the FOCS system has consistently demonstrated its superior and stable performance in terms of high-frequency response and low noise with minimal dependence on the laser parameters.

The effect of state preparation on the probe-bath parameters estimation

Abstract Projective measurement is a popular method of initial state preparation, which always prepares a pure state. However, in various physical situations of interest, this selective measurement becomes unrealistic. In this paper, we investigate the role of pulsed measurement (a unitary operation) on the estimation of system-environment parameters and compare the estimation results obtained via projective measurement with the results obtained via unitary operation. We argue that in typical situations, parameters can be estimated with higher accuracy if the initial state is prepared with the unitary operator (a pulse). We consider the spin-spin model in which a central two-level system (probe) interacts with a collection of two-level systems (bath). The probe interacts with the bath and attains thermal equilibrium. Then, via unitary operation, the initial state is prepared which evolves unitarily. The properties of the bath are imprinted on the reduced dynamics. Due to the initial probe-bath correlations present in the thermal equilibrium state, an additional factor arises in the dynamics, which has an important role in the parameter estimation. In this paper, we study the estimation of bath temperature and probe-bath coupling strength which is quantified by the quantum Fisher information. Our results are promising as one can improve the precision of the estimates by orders of magnitude (especially in the coupling strength case) via unitary operation and by incorporating the effect of initial correlations.

Dynamic performance enhancement in Ti/Au ohmic contacts on β-Ga2O3-on-SiC substrates: evidence from pulsed measurements

Dynamic performance enhancement in Ti/Au ohmic contacts on β-Ga2O3-on-SiC substrates: evidence from pulsed measurements

Ground‐Truth Validation of T2 ${T}_{2}$ Estimates From Steady‐State Surface NMR

AbstractSteady‐state sequences are a new protocol for surface nuclear magnetic resonance (NMR), that can yield high quality data in a short time. In addition to faster acquisition, steady‐state surface NMR purports to measure the transverse relaxation time , which is correlated with hydrogeological parameters like pore‐size. This is in contrast to the effective transverse relaxation time associated with standard single pulse measurements, which may or may not be correlated with pore‐size. While previous studies suggest that steady‐state measurements have enhanced sensitivity to , a ground‐truth validation has not yet been done. We compare steady‐state surface NMR results against borehole NMR logs at four locations. For relaxation regimes of > 10 ms, profiles from steady‐state data are in excellent agreement with borehole measurements, provided the assumption of homogeneous horizontal layers is valid. Even in more complex geological environments, steady‐state surface NMR delivers representative estimates of .

Work system improvement model with macro ergonomic analysis and design method approach

PT. X Company is a fishing boat manufacturing company that manufactures boats, speed boats, and sampan types using an order production process. The stages in making a ship include wood selection, determining the size of the vessel and cutting, wood smoothing, ship assembly, unification with glue between wood, and finishing, including smoothing the ship's body and painting. The vessels produced are, on average, 5 - 7.5 meters in size and weigh 500 kg - 2.5 tons with a completion time of 1 month and three months worked on by six workers still using traditional methods. Many workers currently complain of fatigue caused by the length of the shipbuilding process, and the temperature of the production work environment reaches 34o due to the weather. The study was conducted based on problem factors, including physical work environment factors, equipment/machine factors, workload factors, and organizational factors, with the aim of the study to provide suggestions for improving the work system by using the Macroergonomic Analysis and Design approach to increase worker productivity. Workers feel healthier and more comfortable in doing their jobs. The results obtained from the SPSS 23 calculation show that the work environment, equipment and machines, workload, and significant organization have a simultaneous effect because F count (0.00) < F table (0.05 on the work system. The measure of the worker's pulse to reduce fatigue obtained CVL = 37.32%, average rest energy consumption = 2.97 kcal/minute, and an additional 16 minutes of rest time was received at 12.00-13.19, so the total was 79 minutes. Work productivity in measuring and cutting wood produced 16 pieces of ship components per day, so there was an increase in work productivity of 2 pieces of ship components per day.

Non-Contact Stable Arterial Pulse Measurement Using mmWave Array Radar.

Pulse signals can serve as important indicators of one's cardiovascular condition. However, capturing signals with stable morphology using radar under varying measurement periods remains a significant challenge. This paper reports a non-contact arterial pulse measurement method based on mmWave radar, with stable signals achieved through a range-angle focusing algorithm. A total of six subjects participated in the experiment, and the results showed that, under different measurement times, the pulse morphology of the same body part for each subject had good consistency, reaching a correlation of over 0.84, and four selected pulse signs remained stable. This is a quantitative assessment revealing a high correlation in pulse morphology measured by radar over different periods. In addition, the influence of array size and measurement distance was analyzed, providing a reference of array selection for research work with different requirements. This work offers an effective reference framework for long-term pulse measurement using radar technology.

Comparison of Electrochemical Measurement Methods for Amperometric Sensor to Detect RNA with Isothermal Nucleic Acid Amplification

Amperometric sensors with nucleic acid amplification are expected to be useful for sensitive RNA detection. Nucleic acid amplification reaction involves current changes associated with accelerated redox reactions. Among the nucleic acid amplification methods, we have attempted to apply the signal amplification by ternary initiation complexes (SATIC) system to amperometric sensors1,2. Amperometric sensor with SATIC system detected target RNA by measuring the reduction of hydrogen peroxide by DNAzyme via ferrocene methyl alcohol (FMA). Although linear sweep voltammetry (LSV) was used in previous study, the current was included reactions other than reduction by DNAzyme, such as the charge of the electrical double layer and mass diffusion of redox species. Pulsed electrochemical measurement removes the other current by refreshing the diffusion layer of redox species with each pulse voltage. Therefore, in this study, we focused on pulsed electrochemical measurement methods to further increase the signal-to-noise ratio of amperometric sensors with SATIC system by removing the noise. Current values derived from nucleic acid amplification with the SATIC system were compared by LSV, differential pulse voltammetry (DPV), normal pulse voltammetry (NPV) and square wave voltammetry (SWV.)DNA primers and 6-merchapto-1-hexanol (MCH) were immobilized on gold electrode via gold-thiol bond. Then, the SATIC reaction proceeded (37 ºC, 2 h) on the electrode by target RNA, a circular DNA template, and φ29 DNA polymerase. After that, the electrode was placed in phosphate buffer containing hemin which iron-containing porphyrin. DNAzyme was formed by the G-quadruplex (G4) in the amplified nucleic acid by binding to hemin. The current value changes resulting from the catalytic reaction of DNAzyme before and after the SATIC reaction were measured by LSV, DPV, NPV, and SWV. The ranges of voltage scan were -0.15〜-0.4 V vs. Hg/Hg2SO4 and -0.05〜-0.4 V vs. Hg/Hg2SO4 in LSV and other pulsed electrochemical measurement, respectively. The step potential was 5 mV, pulse wide was 50 ms, and pulse periode was 100 ms. Additionally, the pulse amplitudes of DPV and SWV were 50 mV and 25 mV, respectively. The measuring points each were acquired after 40 s from applying the pulse signals.First, each electrochemical measurement methods in a simple redox reaction were compared. The current density corresponding to the reduction reaction of FMA was measured using a polished bare gold electrode. The results showed an increase in current density depending on FMA concentration in all electrochemical measurement methods. Furthermore, the slope of the current value change relative to the FMA concentration was found to be greater in the order LSV < SWV ≦ DPV ≦ NPV. As the pulse eliminated the contribution of the charging current due to the electrical double layer, the quantitative detectability of DPV, NPV and SWV was higher than LSV. Based on the above results, the signal-to-noise ratio of amperometric sensors with SATIC system was compared using each electrochemical measurement method. The amount of current density changes with the progression of the SATIC reaction to 1 µM Target RNA was measured. As a result, current density changes of LSV: 1.98 μA/cm2, DPV: 12.2 μA/cm2, NPV: 3.41 μA/cm2 and SWV: 9.04 μA/cm2 were observed (Figure 1). In NPV measurement, the variation in current density change was more varied than that using other electrochemical measurements. As the pulse signal were impressed from the open circuit potential in NPV, the current included not only electron transfer but also mass diffusion of FMA mediator, resulting in the variation of repeatability in each measurement. Moreover, in DPV and SWV measurements, the changing in current density were greater than that of LSV measurement. This result could be attributed to the fact that the contribution of the current due to the charging electrical double layer and mass diffusion of FMA mediator was removed by the impressed pulse signal. However, the signals obtained from measurements using DPV and SWV represent the slope of the current value change relative to the potential scan. Therefore, it is not advisable to compare each electrochemical measurement at a single RNA concentration point. In the presentation, we will further discuss the signal-to-noise ratio of measurement methods of amperometric sensors using the SATIC system by comparing the concentration dependence of the target RNA concentration obtained from each electrochemical measurement.Reference:[1] H.Fujita et al., Anal. Chem. 88, 7137−7144 (2016).[2] H.Saze et al., 2023 ECSJ Fall Metting, Abstr, S12_2_04, [in Japanese] Figure 1

Multiplex Pulsed Current Sensors for Anion Detection

Low-cost and stable sensors are needed for long-duration monitoring of nitrate and phosphate in waterways to help improve farming practices and understand the negative environmental and economic impacts caused by the release of these ions. One established platform that shows promise for detecting these ions is the use of solid-contact ion selective electrodes (SC−ISEs). Conventional SC-ISE measurements monitor electrode potential under open circuit conditions to quantify the amount of one target analyte. These conventional SC-ISEs rely on highly engineered membrane materials that are formulated to selectively bind to the target ion. These engineered membrane materials can achieve high selectivity for nitrate and phosphate, but are vulnerable to certain interferents, require frequent calibration, and have poor long-term stability. In recent work, we demonstrated the use of pulsed current technique for anion detection in SC-ISEs, which allows for anion detection based on differences in anion diffusion through the membrane rather than selective anion binding – opening up a wide range of materials as candidates for ion sensing membranes. In this report, we employ pulsed current measurement to examine anion detection using three common polymers as membrane layers: polyvinyl acetate (PVA), polyvinylchloride (PVC), and polyacrylonitrile (PAN). We measure the potential vs. time response for these three membrane materials in solutions containing various anions such as nitrate, phosphate, chloride, and carbonate at varying pulse currents. Afterwards, we employ tree-based and neural-based machine learning algorithms to examine the feasibility of detecting multiple ions simultaneously using the combined response data from multiple electrodes. Our experiments illustrate that our method for anion detection, used with machine learning analysis, is useful for investigating the interaction mechanisms of anions with the polymer matrix.

Comparison of dU/dQ, Voltage Decay, and Float Currents via Temperature Ramps and Steps in Li‐ion Batteries

In this study, the effect of temperature changes on the voltage decay and current behavior of lithium‐ion cells is investigated, focusing on a comparison between open‐circuit voltage (OCV) measurements and float current [[EQUATION]] measurements. Using our self‐developed advanced Floater system, the voltage decay rates [[EQUATION]] from OCV and float current measurements for three different cell types are assessed. Temperature ramps and steps, ranging from 5°C to 50°C, are applied to capture the impact of entropic effects and aging mechanisms. Both methods effectively capture aging dynamics, showing strong agreement between ramp and step measurements. Deviations arise only in cases of strong entropy effects due to differences in measurement strategies. The findings confirm that float currents do not introduce additional aging beyond that captured by OCV measurements. The relationship between OCV and float current is governed by differential capacity [[EQUATION]], which varies with cell voltage and temperature. Furthermore, strong deviations from classical differential voltage analysis but high agreement with local pulse measurements are observed, especially at low depths of discharge. This can be explained by the hysteresis effect of graphite. These findings highlight the benefits of high‐precision float current measurements in aging studies, particularly in contrast to simpler OCV methods.

Understanding of Regeneration Processes of Ruthenium-Poisoned ORR Catalysts

PEM fuel cells, that are operated with a reformate gas (H2, CO2, CO), are of great interest in maritime applications. Despite its outstanding activity in the hydrogen oxidation reaction (HOR), platinum can be quickly poisoned by only very small amounts of CO. Therefore, high CO tolerant anode catalyst materials such as platinum (Pt)-ruthenium (Ru) alloy nanoparticles (NPs) supported on carbon (Pt-Ru/C) are used for PEMFCs supplied with reformate gas. (1) However, these Pt-Ru/C catalysts strongly suffer from the Ru dissolution followed by the crossover through the membrane to the cathode. At the cathode, the soluble Ruz+ species quickly re-deposit at the Pt/C catalyst, resulting in a dramatic loss of performance for the oxygen reduction reaction (ORR). For instance, the kinetics of the ORR decreases by a factor of 8, when the Ru coverage on the surface of Pt nanoparticles is in the range of 20 at.%. (2, 3) Very recently, we have reported different electrochemical regeneration strategies of Ru-poisoned cathode catalyst using rotating disc electrode (RDE) technique. (4) Although the poisoned catalyst could be mostly re-activated, the atomic processes during the regeneration are poorly understood to date. Therefore, operando and in-situ spectroscopic and microscopic techniques are needed.In this work, we combined the electrochemical regeneration protocols with in-situ XAS technique to better understand the re-dissolution processes of the RuOx species from the Pt-based catalyst particle surface.Our regeneration strategies can be categorized into dynamic and steady-state conditions. Each protocol involved an initial pre-activation process by holding the potential at 1.40 VRHE for 5 minutes in 0.1 M HClO4. The dynamic regeneration protocol was performed by potential pulsing between 1.40 VRHE and 1.60 VRHE in 10-second intervals using chronoamperometric method. Additionally, single pulse measurements at 1.60 VRHE with a duration time of 100 s and 300 s were applied for the steady-state regeneration protocol. The regeneration procedure plays an important role in the recovery of the Ru-poisoned ORR activity. The best results of a recovery procedure for PtRu2 and PtRu catalysts are obtained under steady-state condition at 1.60 VRHE for 100 s.The next step was to correlate the electrochemical regeneration experiments with in-situ XAS investigations on commercially available PtRu2 and PtRu catalysts. The Ru K edge and Pt L2/3 edges XAS measurements were carried out in a home-made electrochemical flow cell. Based on the in-situ XAS data, we were able to monitor the changes in the electronic structure and atomic environment of both elements in the alloy nanoparticles as a function of the recovery parameters (potential, holding time). In addition, ex-situ scanning transmission electron microscopy with energy-dispersive X-ray spectroscopy (STEM-EDX) investigations were carried out on Ru-poisoned catalysts after the regeneration protocol to collaborate with the results from XAS.In summary, XAS is a powerful technique to elucidate the electronic structure and atomic arrangement of Ru and Pt atoms and link them with the electrochemical parameters of the regeneration protocol.

Silver-decorated laser-induced graphene for a linear, sensitive, and almost hysteresis-free piezoresistive strain sensor

A new approach has recently emerged in graphene synthesis by direct laser writing (LIG), which is highly economical and scalable, unlike previous methods. Here, the sputtering method has been used to coat silver onto the laser-induced graphene-based sensor. The results demonstrate that the chosen approach substantially impacts the expected outcomes. The initial resistance values were consistent across the different sensor samples. The average resistance was slightly lower in the silver-coated samples compared to the uncoated samples, demonstrating the effectiveness of the Ag coating in enhancing the electrical conductivity of the LIG material. However, the difference in resistance was not statistically significant. The electromechanical behavior of the Ag-coated LIG strain sensor was tested under cyclic tensile strain. The gauge factor increased from 12.9-14.7 for the uncoated LIG sensor to 17.2-26.7 for the Ag-coated sensor, with the difference growing at higher strains. At 5%, 30%, and 70% strain, the gauge factor increased by 30%, 80%, and 82%, respectively. Sensors measuring 1-70% strain were developed, enabling use in various applications. Blood pulse measurements showed the silver-coated sample produced more uniform and reliable results than the uncoated sample. The number of beats matched a commercial pulse oximeter. This sensitivity, linearity, and reliability demonstrate the potential for commercializing these sensors.

Concurrent determination of heat and capacity change of a sessile droplet using a single measurement

Microcalorimetry, designed for the independent measurement of enthalpy and heat capacity, has been commercially available for a considerable time. However, heat-related states in samples, especially liquids, can introduce complicated phenomena and challenging measurement and data evaluation processes. Such complexity becomes apparent when observing fluctuations in heat capacity (Cp) while measuring heat consumption (Q) during water evaporation. This paper presents a continuous heat pulse measurement (CHPM) method for concurrently analyzing Q and Cp in a single test using microcalorimetry. The sample droplet of 400 nL was directly dispensed on the microcalorimeter surface, followed by a light-emitting diode (LED) radiation generating heat to perform CHPM. We repetitively heated the microcalorimeter using heat pulses provided by LED irradiation, with their duration set to 100 ms and 10 s repetition, while measuring the temperature response of the microcalorimeter. A MATLAB-based simulation model was established to validate the accuracy of our Cp measurements, which show its value of 0.79 % of minimum variance. Water evaporation coupled with simultaneous salt crystallization served as our study model, where the Cp values were calculated from real-time responses to heat pulses provided by LED. The experimental outcomes confirm the suitability of CHPM in extracting key thermal properties and emphasize its versatility as a diagnostic tool, providing a significant method for research and applications in the fields of physics, engineering, and beyond.

Coherent dynamics in an optical quantum dot with phonons and photons

Genuine quantum-mechanical effects are readily observable in modern optomechanical systems comprising “classical” (bosonic) optical resonators. Unique features and advantages of optical two-level systems (qubits) for optomechanics, however, have not been so thoroughly explored. We experimentally demonstrate these advantages using charge-controlled InAs quantum dots (QDs) in surface-acoustic-wave resonators. We coherently control QD population dynamics using engineered optical pulses and mechanical motion, i.e., using both phonons and photons. As a first example, at moderate acoustic drive strengths, we demonstrate the potential of this technique to maximize fidelity in quantum microwave-to-optical transduction. Specifically, the scheme is tailored to enhance mechanically assisted photon scattering over the direct detuned photon scattering from the QD. Spectral analysis reveals distinct scattering channels related to Rayleigh scattering and luminescence in our pulsed excitation measurements, which lead to time-dependent scattering spectra. Quantum-mechanical calculations show good agreement with our experimental results, together providing a comprehensive description of excitation, scattering, and emission in a coupled QD-phonon system. These results highlight unique opportunities to expand the functionality of quantum optomechanical systems.

The Effects of Distraction on Cataract Surgery Performance in Consultants and Trainees Using a Simulator.

Mental workload is a recognised concept in medicine, and cognitive overload may lead to complications in surgery, including cataract surgery. A better understanding of what factors contribute to this can potentially improve patient safety and decrease surgeon stress. Simulated cataract surgery is now an essential part of training and a safe environment for exploring the effects of cognitive load upon performance. We used the EyeSi cataract surgery simulator to assess the effects of distraction on surgical performance and on ophthalmology trainees and consultants undertaking cataract surgery. Consultant and trainee cataract surgeons undertook a simulated list of six cases each, of which half were allowed to proceed without extraneous cognitive load with distraction and half were not. Blood pressure and pulse measurements were taken at three intervals in each of the six cases, as well as surgical scores on the simulator recorded for each case. Distraction did not statistically significantly affect the scores, blood pressure or pulse measurements of either the 10 trainees or 10 consultants. Consultants performed more poorly than trainees overall (P = 0.0229) and suffered more serious errors that returned a score of zero for an individual stage (P = 0.0074). Consultant cataract surgeons performed worse than trainees on the EyeSi simulator, raising questions over whether simulation is as true to reality as has been suggested. An important finding is that ophthalmic training curricula around the world have been adapted in order to include simulated cataract surgery as an essential component of training new ophthalmic surgeons.

Abstract 032: TOPSS: TOlerability of tDCS in Pediatric Stroke Survivors

Introduction Pediatric cerebrovascular disease is a leading cause of morbidity in children. Childhood‐onset stroke is defined as stroke occurring after the first month of life and accounts for about half of pediatric stroke. Most children with childhood‐onset stroke will survive to adulthood, but ~75% of those with childhood‐onset stroke experience long‐term neurologic impairments, including motor weakness and cognitive difficulties. Hemiparesis is a frequent complication of childhood‐onset stroke and is tremendously debilitating. Transcranial direct current stimulation (tDCS) is a promising and inexpensive non‐invasive neuromodulation technique that can be used to augment neuronal plasticity as an adjunctive rehabilitation therapy. Methods Participants with chronic hemiparesis from childhood‐onset ischemic or hemorrhagic stroke were prospectively enrolled in this study. All study participants received 5 sessions of tDCS lasting for 20 minutes each while engaging in 1‐on‐1 occupational therapy with a certified occupational therapist. tDCS sessions were followed by an additional 1 hour and 40 minutes of rehabilitation therapy focused on the impaired arm. The amplitude of stimulation was increased daily as follows: sham stimulation on day 1, 0.5mA on day 2, 1.0mA on day 3, 4, and 5. Participants aged 13‐19 years had stimulation further increased to 1.5mA on days 4 and 5. The primary objective measures were safety and tolerability which were assessed with percent study completion, participant tolerability questionnaires, and pre‐ and post‐ stimulation vital signs. Secondary outcome measures included arm function measured using the Fugl‐Meyer Assessment of the Upper Extremity (FMA‐UE) and box and blocks test. Satisfaction was measured using the Canadian Occupational Performance Measure (COPM). A data safety and monitoring board comprised of a pediatric neurologist and pediatric physiatrist reviewed all stimulation monitoring sheets. Results Five participants completed the study. Blood pressure and pulse measurements were within normal limits for all participants for all pre‐ and post‐therapy measurements. Participants reported itching sensations during 40% of tDCS sessions, with reports extinguishing within minutes after cessation of tDCS. The Fugl‐Meyer Assessment of the Upper Extremity is a functional scale with a score range of 0 (profound hemiplegia) to 66 (no impairment). An improvement of 5 points may be considered clinically significant. The median score was 35 at the pre‐therapy assessment, and improved to 42 at the 3 month follow up. 4 out of 5 participants had a clinically significant increase in the Fugl‐Meyer Assessment. Canadian Occupational Performance Measure performance score was 4 at baseline and improved to 6.4 at 3 month follow up. Conclusion tDCS was well‐tolerated in this pilot study of tDCS in participants with chronic hemiparesis from childhood‐onset stroke. There were no major adverse events, and the most common reported side effects were mild itching or tingling which did not limit participation. Fugl‐Meyer Assessment of the Upper Extremity scores improved an average of 7 points 3 months post therapy. Further research with larger, double‐blinded, sham controlled studies is needed. We will continue further research into the utility of tDCS for childhood‐onset stroke with a single center, double‐blinded, randomized controlled trial of tDCS vs sham with a goal enrollment of 20 participants.

Universal and waveform-resolving dual pulse reconstruction through interferometric strong-field ionization.

A dual pulse retrieval algorithm is introduced that builds upon time-domain interferometric strong-field ionization to simultaneously reconstruct both involved laser pulses in a waveform-resolved manner. The pulse characterization scheme removes many restrictions posed by former methods, leaving the avoidance of resonant ionization as a single boundary. It is widely and easily applicable at low cost and effort for common attosecond beamlines and allows for the robust and accurate in-situ retrieval of two unknown laser fields. For spectrally similar pulses, our method can also extract the carrier-envelope phase of both waveforms. Furthermore, it enables the accurate envelope measurement of ultraviolet laser pulses without any dispersive media, using much longer, commonly available pulses in the infrared. The new technique is therefore ideally suited for the characterization of resonant dispersive waves.