Pulsed Measurements Research Articles

Method for the Statistical Analysis of the Signals Generated by an Acquisition Card for Pulse Measurement

This article shows a method for the statistical analysis of signals. Firstly, this method was applied to analyze the processing of signs generated by an acquisition card for pulse measurement using the synchronous demodulation method. The application of the method allowed the study of each signal consisting of a descriptive statistical analysis, followed by the analysis of the trend and dynamics of the movement using the augmented Dickey–Fuller test and Hurst exponent, respectively. Secondarily, the method presented here supported the comparison between the pulse signals obtained by synchronous demodulation and plethysmography methods. In addition, the residuals from the pulse comparison of both methods were analyzed. To quantify the differences between the signals, these were compared using the mean-squared error, the root-mean-square error, the mean absolute error, the mean error, the mean absolute percentage error, and the mean percentage error. After this research, it was possible to analyze the signals knowing characteristics such as the following: the presence of normal, exponential, lognormal, and uniform distributions, stationary trend, and dynamic movement anti-persistent. The novelty that this article proposes is the use of concepts traditionally used in the study of time series and models of demand administration, now focused on supporting improvements over the different stages of design and conceptualization of signal processing devices.

Estimation and Measurement of Alpha Decay Pulses in Fission Detectors and Their Practical Application for Verifying Detector Health

Estimation and Measurement of Alpha Decay Pulses in Fission Detectors and Their Practical Application for Verifying Detector Health

Energetic picosecond 10.2-μm pulses generated in a BGGSe crystal for nonlinear seeding of terawatt-class CO2 amplifiers

We demonstrate what we believe to be a new approach to energetic picosecond 10.2-µm pulse generation based on nonlinear mixing of subnanosecond single-frequency 1338-nm pulses and broadband 1540-nm chirped pulses in a BGGSe crystal followed by a grating compressor for the purpose of seeding high-power CO2 amplifiers. The energy of the 10.2-µm pulses exceeding 60 µJ with 3.4%-rms fluctuation can be routinely obtained. Single-shot pulse duration measurement, performed by Kerr polarization rotation time-resolved by a streak camera, together with the pulse spectrum, indicates the pulse width is between 2.7-3 ps. Numerical calculations show that power broadening and dynamic gain saturation with Rabi-flopping can be induced with such an intense seed in a multi-atmospheric CO2 amplifier. These nonlinear effects greatly suppresses pulse splitting due to the comb-like spectrum of the CO2 molecule. A peak power exceeding 1 TW is expected after multipass of amplification while maintaining an appropriate high intensity by controlling the beam size along the path.

Characterization of ultrashort vector pulses from a single amplitude swing measurement.

Ultrashort vector pulses exhibit time- and frequency-dependent polarization, sparking significant interest across various fields. Simple, robust, and versatile characterization techniques are crucial to meet this rising demand. Our study showcases how complete polarization dynamics are encoded within a single amplitude swing trace, demonstrated both theoretically and experimentally. We have developed a reconstruction strategy to effectively extract all this information. The amplitude swing technique's sensitivity to vector pulses offers a robust, compact in-line setup adaptable across diverse pulse bandwidths, durations, and spectral ranges. This self-referenced method offers effective measurement of ultrashort vector pulses, addressing the growing interest in these complex pulses.

Acoustic observations of individual bubble release events from melting glacier ice in an arctic fjord

Melting below the waterline of marine-terminating glaciers and ice sheets has the potential to remove ice that is holding back land-based ice upstream, and increase the rate of global mean sea level rise. It is difficult to observe this melting directly, and the physical processes involved remain an active area of study. As glacier ice melts, the air bubbles trapped in the ice are released into the water. The air bubbles are often at greater pressure than the surrounding hydrostatic pressure in the water, causing them to be released explosively and generate sound through resulting monopole oscillations. Studying this sound at the level of individual bubbles provides an opportunity to learn more about the role of the bubbles in affecting heat flux across the ice-water boundary layer. It is also essential for proposed efforts to use acoustic emissions as a tool to quantify glacier-scale submarine melting. We will present and discuss observations made at the ice-water interface of floating pieces of glacier ice in an Arctic fjord. These observations included measurements of the water thermal structure, velocity, and salinity, as well as ablation of the ice face, made concurrently with acoustic measurements of bubble release pulses from a 2-element hydrophone array.

Effectiveness of osteopathic manipulative applications on hypothalamic-pituitary-adrenal (HPA) axis in youth with major depressive disorder: a randomized double-blind, placebo-controlled trial.

Osteopathic treatments regulate the neurovegetative system through joint mobilizations and manipulations, and myofascial and craniosacral techniques. Despite the growing body of research, the precise impact of osteopathic medicine on the autonomic nervous system (ANS) is not yet fully elucidated. As to Kuchera's techniques, the stimulation of the sympathetic trunk and prevertebral ganglia contributed to harmonization of the sympathetic activity. However, potential relationships between the harmonization of the sympathetic nervous system (SNS) and the hypothalamic-pituitary-adrenal (HPA) axis largely remain uncertain and warrant further exploration. This study was designed to evaluate the effectiveness of the osteopathic sympathetic harmonization (OSH) on the SNS and the HPA axis in youth with major depressive disorder (MDD). The study included 39 youths aged 15-21 years and diagnosed with MDD. The participants were randomly assigned into either the OSH or the placebo group. Stimulation was performed on the sympathetic truncus and prevertebral ganglia in the OSH group. The stimulation of the placebo group was performed with a lighter touch and a shorter duration in similar areas. Each participant completed the Beck Depression Inventory (BDI) and the State and Trait Anxiety Inventory (SAI and TAI) before the application. Blood pressure (BP) and pulse measurements were made, and saliva samples were taken before, immediately after, and 20 min after application. The baseline BDI (p=0.617) and TAI (p=0.322) scores were similar in both groups. Although the SAI scores decreased in both groups postintervention, no statistically significant difference was found between the two groups. Subjects who received OSH had a decrease in α-amylase level (p=0.028) and an increase in cortisol level (p=0.009) 20 min after the procedure. Following OSH application in depressed youth, SNS activity may decrease, whereas HPA axis activity may increase. Future studies may examine the therapeutic efficacy of repeated OSH applications in depressed individuals.

Hydrogen Sensing Properties of FET-Type Sensors with Pt-In2O3 at Room Temperature

In this paper, a field effect transistor (FET)-type sensor with Pt-decorated In2O3 (Pt-In2O3) nanoparticles is fabricated for detecting H2 gas at room temperature. A pulsed measurement method is adopted to continuously alternate between pre-biasing the gate and reading the drain current of the FET-type sensor. This method effectively reduces the drift in the sensing signal. It is also found that negative pre-bias voltages can dramatically shorten the recovery time of the sensor after sensing H2, while positive pre-bias voltages have the opposite effect. The H2 sensing performance of the sensor is characterized under the enhancement of a pulsed negative pre-bias. By calculating and comparing the root mean square, signal-to-noise ratio, and detection limit of the sensor under different operating regions, it is found that the sensor has the best sensing performance in the subthreshold region, which is suggested to be the optimum operating region for FET-type sensors. In addition, the presence of oxygen significantly consumes the hydrogen molecules and reduces the room-temperature H2 sensitivity of the sensor. The proposed sensor presents promising H2 sensing properties, and this research could be a guide for the use of FET-type sensors in more gas detection applications.

Thermal Conductivity Switching in Pd-Catalyzed Gd and GdH2 Films Upon Gasochromic Hydrogenation and Dehydrogenation

Thermal conductivity switching in Pd-catalyzed Gd hydride films was investigated using in situ analyses of electrical, optical, structural, and thermophysical properties upon gasochromic hydrogenation/dehydrogenation at room temperature. These reactions allow the films to reversibly switch between the metallic (GdH2) phase in the hydrogenated state and the semiconductor (GdH3) phase in the dehydrogenated state. We fabricated three-layered films comprising Pd (5 nm)/Gd or GdH2 (300 nm)/Mo (100 nm) using DC magnetron sputtering using Pd, Gd, and Mo targets, respectively, on unheated synthetic quartz substrates. Ar or mixture of Ar + H2 (H2: 5 % to 50 %) gases were used for the deposition of the Gd or GdH2 films, respectively. The thermal conductivities of the Gd or GdH2 films were analyzed using in situ rear-heating/rear-detection type time-domain picosecond pulsed light heating thermoreflectance measurements by employing a gas mixture of N2/Ar and H2 (H2: 3 %) at 1 atm, which is below the explosive limit for hydrogen. The thermal conductivities of Gd and GdH2 films were measured for one and two hydro-/dehydrogenation cycles, respectively. The thermal switching ratios of the ON state thermal conductivity to the OFF state thermal conductivity were 6.4 and 2.9–5.4 for the Gd film and the GdH2 (H2: 5 %–50 %) films, respectively. The thermal conductivity of the Gd hydrides films changed along with those estimated from the Wiedemann–Franz Law and electrical conductivities.

High-sensitivity and high-speed measurements of ultrashort pulses as short as 74 fs at 1.9 µm using a GRENOUILLE device.

Ultrashort laser pulse sources in the wavelength range of 1.8 to 2 µm have many potential applications including medicine, materials processing, and sensing. In the use of such lasers, a crucial task is to measure their pulse's temporal intensity and phase. Such measurement devices are most useful when they are simple to build and operate and also have high speed and high sensitivity. The GRENOUILLE measurement device with few components, no moving parts, sensitivity of hundreds of picojoules, and measurement speed of hundreds of milliseconds, is commonly used to solve this problem at other wavelengths. In this paper, the measurement of ultrashort pulses by a GRENOUILLE device, developed using a silicon matrix sensor, for pulses in the wavelength range of 1.8 to 2 µm has been demonstrated. It is shown that ultrashort pulses with durations of 74 to 900 fs and a maximum spectral FWHM of 85 nm can be measured with this device. The recently developed ultra-reliable RANA approach was used for pulse retrieval from the measured traces. The device's performance was validated by comparing its measurements with those obtained by the robust FROG technique.

Nonlinear Dynamics in HfO2/SiO2-Based Interface Dipole Modulation Field-Effect Transistors for Synaptic Applications

In the pursuit of energy-efficient spiking neural network (SNN) hardware, synaptic devices leveraging emerging memory technologies hold significant promise. This study investigates the application of the recently proposed HfO2/SiO2-based interface dipole modulation (IDM) memory for synaptic spike timing-dependent plasticity (STDP) learning. Firstly, through pulse measurements of IDM metal–oxide–semiconductor (MOS) capacitors, we demonstrate that IDM exhibits an inherently nonlinear and near-symmetric response. Secondly, we discuss the drain current response of a field-effect transistor (FET) incorporating a multi-stack IDM structure, revealing its nonlinear and asymmetric pulse response, and suggest that the degree of the asymmetry depends on the modulation current ratio. Thirdly, to emulate synaptic STDP behavior, we implement double-pulse-controlled drain current modulation of IDMFET using a simple bipolar rectangular pulse. Additionally, we propose a double-pulse-controlled synaptic depression that is valuable for optimizing STDP-based unsupervised learning. Integrating the pulse response characteristics of IDMFETs into a two-layer SNN system for synaptic weight updates, we assess training and classification performance on handwritten digits. Our results demonstrate that IDMFET-based synaptic devices can achieve classification accuracy comparable to previously reported simulation-based results.

Analyzing Engine Exhaust Gas Temperature Pulsations and Gas-Dynamics Using Thin-Wire Thermocouples

Abstract The exhaust of internal combustion engines (ICEs) is characterized by rapid large amplitude exhaust gas temperature (EGT) pulsations that demand high-bandwidth measurements for accurate instantaneous and mean EGTs. While measurement technique challenges constrain on-engine EGT pulse measurements, reduced-order system simulations numerically estimate the EGT pulse and its mean to overcome the measurement limitation. Notwithstanding high-bandwidth pressure measurements, model calibration and validation for the EGT are confined to mean indications using sheathed thermal sensors like thermocouples and resistance thermometers. These EGT measurements are susceptible to errors caused by heat transfer, flow unsteadiness, and the thermal inertia of the sensor. Exposed thin-wire thermocouples provide an intermediate solution to the robustness-to-response tradeoff of thermal sensors. While the thermocouples' thermal inertia significantly affects the measured EGT pulse, the signal derivative (unscaled dynamic error) provides greater insight by indicating the EGT waveform. This study utilizes a 50.8-μm Type-K thermocouple to contrast the exhaust pressure and EGT pulses through the measured signal and its derivative. Experiments in a single-pipe exhaust of a heavy-duty diesel engine with isolated engine speed and load sweeps (LS) present significant differences between the pressure and indicative EGT waveforms. It also highlights a rapid prepulse fluctuation unique to the EGT pulse waveform caused by exhaust gas-dynamics and impacted by heat transfer. The study motivates the need for increased bandwidth EGT measurements to improve model validation of EGT pulse estimates while showcasing the utility of thin-wire thermocouples.

Gain Measurement of ZnGeP2 Optical Parametric Oscillator Pulses in a High-Pressure CO2 Amplifier

Laser pulse amplification by a high-pressure CO2 amplifier in the long-wave infrared (LWIR) spectral range is a feasible technology for strong-field physics research. Crystals such as ZnGeP2 (ZGP) have high nonlinear coefficients and transmittance in the LWIR region, with spectral widths of generated pulses closely matching the gain spectrum of high-pressure CO2 amplifiers. Therefore, ZGP optical parametric oscillation (OPO) may allow higher-efficiency energy extraction in amplifiers, improving the output characteristics of LWIR amplification systems. In this study, the gain measurement of ZGP OPO pulses amplified by a high-pressure CO2 amplifier was carried out for the first time. Single-detector acquisition was utilized to achieve a unified sensor responsivity, and a laser signal-triggered function generator was used to synchronize the seed pulse and amplifier. Six-pass amplification was performed successively, yielding an amplification factor of 4.5 for the peak power and a maximum coefficient of 0.42% cm−1 for the small-signal gain. The gain and loss effect during small-signal amplification were discussed. The potential capability of acquiring ultra-short pulses with ZGP OPO pulses was also explored with the FFT function of MATLAB software.

Natural Polymorphisms D60E and I62V Stabilize a Closed Conformation in HIV-1 Protease in the Absence of an Inhibitor or Substrate.

HIV infection remains a global health issue plagued by drug resistance and virological failure. Natural polymorphisms (NPs) contained within several African and Brazilian protease (PR) variants have been shown to induce a conformational landscape of more closed conformations compared to the sequence of subtype B prevalent in North America and Western Europe. Here we demonstrate through experimental pulsed EPR distance measurements and molecular dynamic (MD) simulations that the two common NPs D60E and I62V found within subtypes F and H can induce a closed conformation when introduced into HIV-1PR subtype B. Specifically, D60E alters the conformation in subtype B through the formation of a salt bridge with residue K43 contained within the nexus between the flap and hinge region of the HIV-1 PR fold. On the other hand, I62V modulates the packing of the hydrophobic cluster of the cantilever and fulcrum, also resulting in a more closed conformation.

Remote vision-based digital patient monitoring of pulse and respiratory rates in acute medical wards.

Remote Vision-Based digital Patient Monitoring (VBPM) of pulse (PR) and respiratory rate (RR) was set up in six single rooms in an acute medical and an orthopaedic ward. We compared 102 PR and 154 RR VBPM measurements (from 27 patients) with paired routine nurse measurements. VBPM measurements of RR were validated by reviewing video footage. Nurse measurements of RR were often 16-18 breaths/minute, and did not match VBPM RR (overestimating at low RR and underestimating at high RR). Nurse measurements of pulse were on average 3.9 beats per minute greater than matched VBPM measurements. VBPM was unobtrusive and well accepted.

Analysis of Trapping Effects on AlInN/GaN High Electron Mobility Transistors with Pulsed Electrical Measurements Under Visible and Infrared Illumination

The aim of this article is to show that it is possible to rapidly estimate the activation energies of electron traps in AlInN/GaN transistors operating at room temperature by combining pulsed electrical measurements with photoionization techniques using infrared illumination. This technique avoids the time‐consuming task of performing electrical measurements at different temperatures to determine the activation energies of the electron traps using Arrhenius laws. Thus, a deep level at 1.3 eV is detected and attributed to the presence of carbon in GaN buffer of the component. Moreover, we have highlighted that the trapping effect can be screened when the transistors are biased with a high drain‐source voltage during pulsed measurements.

Assessment of effectiveness of mobile phone application in detection of heart arrhythmias in comparison to 12 lead electrocardiogram and pulse measuring

Background: Nowadays more and more people suffer from arrhythmias. The arrhythmias can be both paroxysmal or persistent. Technological progress leads to miniaturization and personalization of electronic devices.Aims: The study aimed to declare if the effectiveness of mobile phone applications in arrhythmia detection can be compared with standard 12 leads electrocardiogram and manual pulse measurements.Methods: Each person had a manual pulse measurement on the radial artery for 30 seconds as an initial examination. The next 4 examinations were performed by various mobile applications, one for each application. The following applications were used: Kardia, Diagnostyka kardiologiczna, HeartBeats, Photo AFib Detector. Kardia examination was performed with a dedicated measure device. The last examination was a 12-lead electrocardiogram.Results: 121 people take part in the examination (67% were men, average age was 65,4 +/- 12,09). 61 of them had an arrhythmia during the examination. The control group consisted of 60 people without arrhythmia history. The following values of sensitivity [se] and specificity [sp] were obtained: Kardia (se: 98% sp: 100%), Diagnostyka Kardiologiczna (se: 77% sp: 58%), HeartBeats (se: 89% sp: 93%), PhotoAFib Detector (se: 18% sp: 90%), manual pulse measuring (se: 91% sp: 100%). Heartbeats and PhotoAFib Detector obtained a negative statistically significant correlation between age and effectiveness of measurements.Conclusion: Mobile phone applications can be in the future valuable alternative for 12 lead electrocardiogram and pulse measuring in arrhythmia detection, however, it should be noted that not all of them have enough quality. Only certified applications should be used as a diagnostic method.

A flexible multimodal pulse sensor for wearable continuous blood pressure monitoring.

Monitoring of arterial blood pressure via cuffless pulse waveform measurement at the wrist has an important clinical value for the early diagnosis and prevention of cardiovascular disease. However, accurate measurement of the radial pulse waveform is challenging owing to its subtle, wideband, and preload-dependent variation characteristics. Evidence shows that uncertainties or variations of wearing pressure and skin temperature can cause artifact signals in wrist pulse measurements, thus degrading blood pressure estimate accuracy and hindering precise clinical diagnosis. Herein, we report a flexible multisensory pulse sensor utilizing natural piezo-thermic transduction of human skin in conjunction with thin-film thermistors for the accurately measuring radial artery pulse waves with high fidelity and good anti-artifact performance. The flexible pulse sensor achieved a wide pressure measuring range (228.2 kPa), low detection limit (4 Pa), good linearity (R2 = 0.999), low hysteresis (2.45%), fast response (88 ms), and good durability and stability, thereby enabling accurate pulse measurement with high fidelity. The pulse sensor also monolithically integrated the simultaneous detections of skin temperature and wearing pressure for resisting artifact effects in pulse measurements. Through the fusion of multiple features extracted from the pulse waveform, wearing pressure, skin temperature and user's personal physical characteristics using an efficient multilayer perceptron, blood pressure is accurately estimated and good generalizability is achieved.

Ab. No. 20 “Pulse-Tech”- Ideation to Prototype to Measure Pulse Strength Device

Introduction: This study focused on the creation and evaluation of the ‘Pulse Tech’ device, a novel tool designed for the measurement of pulse strength. The pulse, a crucial indicator of cardiovascular health, reflects the heart’s efficacy in blood circulation. Traditional pulse assessment methods, while effective, often require significant expertise and could lack objectivity. The ‘Pulse Tech device addressed these limitations by offering a more standardized and accurate method for measuring pulse strength. Understanding pulse strength, including its rate, rhythm, and quality, is essential in diagnosing various cardiac conditions. The study delineated seven primary pulse points (temporal, carotid, brachial, femoral, radial, popliteal, dorsalis pedis) and their medical significance. It also detailed various cardiovascular pulse shapes, their physiological causes, and associated potential diseases. The ‘Pulse Tech device was innovatively designed to measure pulse strength objectively, utilizing advanced sensors and software for data capture and analysis. Its distinctive feature was the use of light absorption through blood vessels to indirectly measure pulse strength. The methodology comprised two phases: the first centered on designing and developing the device, including its components like the CPU section, pulse rate sensor, and software. The second phase involved testing the device on healthy individuals to validate its effectiveness against traditional methods. Methods: The study’s participant criteria included healthy individuals aged 18-30 years. The objective was to establish a new standard in pulse measurement, enhancing the accuracy and reliability of cardiovascular assessments. This was crucial in both clinical and research settings, potentially aiding in the early detection and management of heart-related diseases. The study emphasized the necessity of a ‘Pulse Tech’ in enabling physicians and physiotherapists to make more informed decisions about patient care. Conclusion: The ‘Pulse Tech’ device represented a significant advancement in biomedical devices, with the potential to revolutionize the measurement and interpretation of pulse strength in clinical practice.

Early Detection of Livestock Fever, Estrus, and Parturition Using Wearable Tail Sensor

The advancement of technology paved the way for the wearable tail sensor to be developed as livestock owners depend on analog measurements for detecting fever, estrus, and parturition. Hence, these advancements help farm and livestock management. This study aimed to design and develop a wearable tail sensor that integrates heat, motion, and pulse sensors for the early detection of livestock fever, estrus, and parturition. This study utilized a Research and Development (R&D) design employing the 4D Model of device development, which encompasses four distinct phases: define, design, develop, and disseminate. The study successfully designed and developed a device that integrates four sensors to detect fever, estrus, and parturition in livestock. The results revealed that the device has a high level of acceptability and adaptability. Statistical analysis also showed that there is no significant difference between the measurements of the analog instruments and the wearable tail sensor in terms of temperature and pulse rate for both cattle and pigs. The researchers successfully constructed a wearable device integrating four sensors to detect fever, estrus, and parturition in livestock that transmits real-time data over the web server and accurate measurements of temperature, pulse, and motion of livestock. This advancement benefits the livestock owners by making it less difficult to track the livestock’s fever, estrus, and parturition.

Measurement of ultrashort laser pulses with a time-dependent polarization state using the d-scan technique

The dispersion scan (d-scan) technique is extended to measurement of the time-dependent polarization state of ultrashort laser pulses. In the simplest implementation for linearly polarized ultrashort pulses, the d-scan technique records the second harmonic generation spectrum as a function of a known spectral phase manipulation. By applying this method to two orthogonally polarized projections of an arbitrary polarized electric field and by measuring the spectrum at an intermediate angle, we can reconstruct the evolution over time of the polarization state. We demonstrate the method by measuring a polarization gate generated from 6fs pulses with a combination of waveplates. The measurements are compared to simulations, showing an excellent agreement.