Waveform Changes Research Articles

Changes in Oxygen Saturation and Pulse Waveform Measured with Photoplethysmogram Sensor and Magnetic Hall Sensor According to Hyperbaric Oxygen Therapy

Changes in Oxygen Saturation and Pulse Waveform Measured with Photoplethysmogram Sensor and Magnetic Hall Sensor According to Hyperbaric Oxygen Therapy

The Use of the Pulse Oximeter in Limb Ischemia: The Pulse Study

Purpose: Does a non-invasive pulse oximeter probe accurately indicate limb ischemia with inflation of a tourniquet? How are the pulse waveform, perfusion index and oxygen saturations affected? Does pulse oximetry return to normal with restoration of blood flow? Are the findings similar, regardless of which probe is used? Methods: Single Centre, pilot, proof of concept study. Each volunteer staff member had two probes applied to both lower limbs and then to both upper limbs. One limb had a tourniquet applied (experimental limb). The pulse oximeter trace, perfusion index and oxygen saturations were recorded before tourniquet inflation (time point 0), at inflation (time point 1), just prior to deflation (time point 2) and after deflation when the waveform returned to a biphasic appearance (time point 3). Results: Changes in both pulse oximeter waveforms occurred within 45 seconds of tourniquet inflation, with flattening of the biphasic trace followed by complete loss of amplitude, which normalized on release of the tourniquet. Perfusion index values for the experimental arms and legs were statistically significantly smaller than the control sides during tourniquet inflation and exceeded baseline on deflation, due to reperfusion. Oxygen saturations were unreliable and did not reflect tourniquet inflation. Conclusion: Pulse Oximeter waveform and perfusion index provide a noninvasive, sensitive, responsive, available, repeatable, objective measure of vascular supply in the limbs in healthy volunteers, although oxygen saturation is not a reliable indicator of perfusion. Objective assessment using the pulse oximeter could aid clinical judgement in initiating early vascular intervention in limb injury.

High-order harmonic generation of ZnO crystals in chirped and static electric fields

High harmonic generation in ZnO crystals under chirped single-color field and static electric field are investigated by solving the semiconductor Bloch equation (SBE). It is found that when the chirp pulse is introduced, the interference structure becomes obvious while the harmonic cutoff is not extended. Furthermore, the harmonic efficiency is improved when the static electric field is included. These phenomena are demonstrated by the classical recollision model in real space affected by the waveform of laser field and inversion symmetry. Specifically, the electron motion in k-space shows that the change of waveform and the destruction of the symmetry of the laser field lead to the incomplete X-structure of the crystal-momentum-resolved (k-resolved) inter-band harmonic spectrum. Furthermore, a pre-acceleration process in the solid four-step model is confirmed.

Cortical Neurons Adjust the Action Potential Onset Features as a Function of Stimulus Type

Pyramidal neurons and interneurons play critical roles in regulating the neuronal activities in the mammalian cortex, where they exhibit different firing patterns. Pyramidal neurons mainly exhibit regular-spiking firing patterns, while interneurons have fast-spiking firing patterns. Cortical neurons have distinct action potential onset dynamics, in which the evoked action potential is rapid and highly variable. However, it is still unclear how cortical regular-spiking and fast-spiking neurons discriminate between different types of stimuli by changing their action potential onset parameters. Thus, we used intracellular recordings of regular-spiking and fast-spiking neurons, taken from layer 2/3 in the somatosensory cortex of adult mice, to investigate changes in the action potential waveform in response to two distinct stimulation protocols: the conventional step-and-hold and frozen noise. The results show that the frozen noise stimulation paradigm evoked more rapid action potential with lower threshold potential in both neuron types. Nevertheless, the difference in the action potential rapidity in response to different stimuli was significant in regular-spiking pyramidal neurons while insignificant in fast-spiking interneurons. Furthermore, the threshold variation was significantly higher for regular-spiking neurons than for fast-spiking neurons. Our findings demonstrate that different types of cortical neurons exhibit various onset dynamics of the action potentials, implying that different mechanisms govern the initiation of action potentials across cortical neuron subtypes.

Analysis on the change characteristics of waveform during the transmission of continuous wave mud pulse signal

Continuous wave mud pulse transmission is the most widely used information transmission technology in measurement while drilling (MWD). The increase in transmission distance will cause the signal attenuation and deformation during transmission, the affecting exploration efficiency. The waveform change law of continuous mud pulse wave in the process of downhole transmission, this paper establishes a mathematical analysis model, focuses on the modulation form of continuous wave signal, physical mud characteristics, and drill pipe characteristics, and discusses the transmission rules of various characteristics on continuous pressure wave. A simulation system of drill pipe transmission pressure wave is constructed. The transmission characteristics of continuous wave signals under different modulation forms are discussed. The positive correlation between the amplitude attenuation and waveform distortion of pulse signals caused by increased gas holdup in the mud under bubbly flow patterns is analyzed. The numerical calculation and simulation analysis results show that the viscosity frequency characteristic of mud is the main factor affecting the attenuation of continuous wave signal. The surface roughness, size and other physical characteristics of drill pipe can affect the transmission speed and attenuation of signals in long-distance transmission. The signal is prone to distortion at the position of modulation phase change.

Evolution law of ultrasonic characteristics and its relationship with coal-measure sandstone mechanical properties during saturation and desaturation

Underground buildings are easily destabilised by water and there is a strong link between their mechanical properties and ultrasonic characteristics. To grasp the above features and the relationship among them, the mechanism of sandstone degradation under water erosion was briefly reviewed. Using the coal-measure sandstone as the object, experimental studies on the dynamic evolution of water content, ultrasonic wave velocity, waveform, uniaxial compressive strength (UCS), elastic modulus (E), and damage mode during saturation-desaturation were carried out. The findings demonstrate that coal-measure sandstones usually exhibit more mechanical parameter deterioration following saturation than non-coal-measure sandstones. During saturation, the water absorption velocity slows down; the P-wave velocity (VP) first fluctuates down, then fluctuates up and finally decreases slightly (VP increases after saturation), and the wave velocity anisotropy coefficient (δi) decreases; the waveform shows a trend of unequal time and unequal amplitude → equal time and equal amplitude → unequal time and equal amplitude, and the first wave reaches a progressively shorter time. During desaturation, the dehydration rate slows down, VP first drops rapidly and then fluctuates slightly and rises slightly near drying (VP decreases after desaturation), δi increases, and the waveform changes in the opposite trend to saturation. Saturation treatment significantly weakened the mechanical properties, while desaturation restored some of the strength lost due to immersion. The sandstone mechanical properties and ultrasonic features are more closely related during saturation than desaturation.

Computer and experimental analysis of a reconfigurable staircase module-based multi-level inverter with fault tolerant capability

In the conventional multilevel inverters, occurrence of a fault in one or more power switches can cause abnormal changes in the output waveforms. Besides, increasing the applied power switches results to an increase in the possibility of fault on the power switches. Accordingly, providing a comprehensive structure with high fault-tolerant capability is one of the vital requirements and critical challenges. To tackle these issues, this study first presents and explores a new basic unit and staircase module (SM) and then extends and optimizes it to yield a reconfigurable multi-level inverter (MLI) with more levels and different goals. The proposed MLI can continue to operate when open-circuit faults in switches. This advantage of the proposed structure is achieved without any redundant legs or switches. For further investigation, a comparison is made in terms of the number of power switches, drivers, dc sources, and reliability between the proposed and similar structures. To control the output voltage levels, the strategy of fundamental frequency switching triggers the configured topology. The carrier signals are reconfigured under fault conditions based on levels to be generated by bypassing the faulted switch. The validity of the established MLI with its fault-tolerant capability is certified through both computer simulations using the MATLAB/Simulink platform and laboratory prototype implementations.

Machine learning discriminates P2X7-mediated intracellular calcium sparks in human-induced pluripotent stem cell-derived neural stem cells

Adenosine triphosphate (ATP) is an extracellular signaling molecule that mainly affects the pathophysiological situation in the body and can be sensed by purinergic receptors, including ionotropic P2X7. Neuronal stem cells (NSCs) remain in adult neuronal tissues and can contribute to physiological processes via activation by evoked pathophysiological situations. In this study, we revealed that human-induced pluripotent stem cell-derived NSCs (iNSCs) have ATP-sensing ability primarily via the purinergic and ionotropic receptor P2X7. Next, to develop a machine learning (ML)-based screening system for food-derived neuronal effective substances and their effective doses, we collected ATP-triggered calcium responses of iNSCs pretreated with several substances and doses. Finally, we discovered that ML was performed using composite images, each containing nine waveform images, to achieve a better ML model (MLM) with higher precision. Our MLM can correctly sort subtle unidentified changes in waveforms produced by pretreated iNSCs with each substance and/or dose into the positive group, with common mRNA expression changes belonging to the gene ontology signatures.

Beat to Beat Continuous Blood Pressure Estimation using the Transmission Coefficient Waveforms out of On-body Continuous Wave Antennas

Blood pressure (BP) is a clear sign of hypertension, a condition that can be hazardous and even fatal. Regular blood pressure monitoring is therefore crucial, but many people dislike cuff-based devices, and they can only be used while at rest. To address this need, this paper investigates the use of micro strip patch antenna technology to obtain BP values through an innovative technique. The change of transmission coefficient EM waveforms emitted by the antennas will be analyzed and correlated with brachial artery thickness to radius ratios and hence, blood pressure assessment at different pressure points. The suggested morphology based on simulations and data algorithms performed at couple of instances of brachial artery diameters to mimic the condition of blood flow. A dedicated analysis software provided to calculate the systolic and diastolic pressure levels.

Research on the mechanism and restraining measures of ferroresonance in distribution network based on ATP-EMTP

In order to monitor the three-phase voltage of the busbar to ground, the substation bus is usually connected to the electromagnetic voltage transformer by YN connection in the distribution network. Under certain conditions, the excitation characteristics are easy to saturate, and the inductance parameters match the system capacitance, excite ferromagnetic resonance, cause damage to fuses or voltage transformers, and seriously affect the safe and stable operation of the power system.By analyzing typical single-phase ground faults, this paper introduces the generation mechanism of ferromagnetic resonance and the main suppression measures at this stage. The electromagnetic transient analysis software ATP-EMTP is used to analyze the operation of a typical transformer, and the change of ferromagnetic resonance waveform after the neutral point of the voltage transformer is replaced by resonant eliminator and arc suppression coil grounding. The results show that when eliminating the single-phase ground fault, it is easy to cause the frequency division resonance of the system, and the use of these two measures can effectively suppress the ferromagnetic resonance of the system.

Insights Into Vascular Physiology From Sleep Photoplethysmography.

Photoplethysmography (PPG) in consumer sleep trackers is now widely available and used to assess heart rate variability (HRV) for sleep staging. However, PPG waveform changes during sleep can also inform about vascular elasticity in healthy persons who constitute a majority of users. To assess its potential value, we traced the evolution of PPG-pulse waveform during sleep alongside measurements of HRV and blood pressure. Seventy eight healthy adults (50% male, median (range) age: 29.5 (23.0, 43.8)) underwent overnight polysomnography (PSG) with fingertip PPG, ambulatory blood pressure monitoring (ABPM) and electrocardiography (ECG). Selected PPG features that reflect arterial stiffness: systolic to diastolic distance (∆T_norm), normalized rising slope (Rslope) and normalized reflection index (RI) were derived using a custom-built algorithm. Pulse arrival time (PAT) was calculated using ECG and PPG signals. The effect of sleep stage on these measures of arterial elasticity and how this pattern of sleep stage evolution differed with participant age were investigated. Blood pressure, heart rate and PAT were reduced with deeper non-REM sleep but these changes were unaffected by the age range tested. After adjusting for lowered heart rate, ∆T_norm, Rslope and RI showed significant effects of sleep stage, whereby deeper sleep was associated with lower arterial stiffness. Age was significantly correlated with the amount of sleep-related change in ∆T_norm, Rslope and RI, and remained a significant predictor of RI after adjustment for sex, body mass index, office blood pressure and sleep efficiency. The current findings indicate that the magnitude of sleep-related change in PPG waveform can provide useful information about vascular elasticity and age effects on this in healthy adults.

Enhancement of turn-off gate voltage waveform change by digital gate control for bond wire lift-off detection in IGBT module

The bond wire lift-off is the one of main failures for insulated gate bipolar transistors (IGBT) power modules. The wire lift-off increases parasitic inductance LeE in the module and the gate voltage Vge waveform is modulated by LeE·dIe/dt. Therefore, the Vge waveform has the potential for an indicator of condition monitoring. The Digital gate control (DGC) can control switching behavior precisely for low-loss and low-noise switching. It is also effective for sensitivity enhancement of Vge waveform changed by the wire lift-off. This paper reports how the DGC 2-step vector control (2-sVC) can improve the wire lift-off failure detection sensitivity by Vge waveform. The experiment results showed that the Vge spike was generated by LeE·dIe/dt at the turn-off switching and the spike generation timing depended on the wire number. The DGC obtained the larger timing-shift Δtwire and the amplitude ΔVge-surge than those at the conventional gate control. In addition, the best vector condition improved the trade-off between turn-off loss and collector voltage overshoot compared with the conventional gate control. From these results, the DGC is effective to enhance the sensitivity of bond wire lift-off detection by Vge waveform maintaining the best switching performance.

Characterization of Chlamydomonas voltage-gated calcium channel and its interaction with photoreceptor support VGCC modulated photobehavioral response in the green alga

Calcium (Ca2+) signaling plays a major role in regulating multiple processes in living cells. The photoreceptor potential in Chlamydomonas triggers the generation of all or no flagellar Ca2+ currents that cause membrane depolarization across the eyespot and flagella. Modulation in membrane potential causes changes in the flagellar waveform, and hence, alters the beating patterns of Chlamydomonas flagella. The rhodopsin-mediated eyespot membrane potential is generated by the photoreceptor Ca2+ current or P-current however, the flagellar Ca2+ currents are mediated by unidentified voltage-gated calcium (VGCC or CaV) and potassium channels (VGKC). The voltage-gated ion channel that associates with ChRs to generate Ca2+ influx across the flagella and its cellular distribution has not yet been identified. Here, we identified putative VGCCs from algae and predicted their novel properties through insilico analysis. We further present experimental evidence on Chlamydomonas reinhardtii VGCCs to predict their novel physiological roles. Our experimental evidences showed that CrVGCC4 localizes to the eyespot and flagella of Chlamydomonas and associates with channelrhodopsins (ChRs). Further in silico interactome analysis of CrVGCCs suggested that they putatively interact with photoreceptor proteins, calcium signaling, and intraflagellar transport components. Expression analysis indicated that these VGCCs and their putative interactors can be perturbed by light stimuli. Collectively, our data suggest that VGCCs in general, and VGCC4 in particular, might be involved in the regulation of the photobehavioral response of Chlamydomonas.

A neonatal rat model of pulmonary vein stenosis

ObjectivesPulmonary vein stenosis (PVS), one of the most challenging clinical problems in congenital heart disease, leads to secondary pulmonary arterial hypertension (PAH) and right ventricular (RV) hypertrophy. Due to the lack of a rodent model, the mechanisms underlying PVS and its associated secondary effects are largely unknown, and treatments are minimally successful. This study developed a neonatal rat PVS model with the aim of increasing our understanding of the mechanisms and developing possible treatments for PVS.MethodsPVS was created at postnatal day 1 (P1) by banding pulmonary veins that receive blood from the right anterior and mid lobes. The condition was confirmed using echocardiography, computed tomography (CT), gross anatomic examination, hematoxylin and eosin (H&E) staining, fibrosis staining, and immunofluorescence. Lung and RV remodeling under the condition of PVS were evaluated using H&E staining, fibrosis staining, and immunofluorescence.ResultsAt P21, echocardiography revealed a change in wave form and a decrease in pulmonary artery acceleration time—indicators of PAH—at the transpulmonary valve site in the PVS group. CT at P21 showed a decrease in pulmonary vein diameter in the PVS group. At P30 in the PVS group, gross anatomic examination showed pulmonary congestion, H&E staining showed wall thickening and lumen narrowing in the upstream pulmonary veins, and immunofluorescence showed an increase in the smooth muscle layers in the upstream pulmonary veins. In addition, at P30 in the PVS group, lung remodeling was evidenced by hyperemia, thickening of pulmonary small vessel walls and smooth muscle layers, and reduction of the number of alveoli. RV remodeling was evidenced by an increase in RV free wall thickness.ConclusionsA neonatal rat model of PVS was successfully established, showing secondary lung and RV remodeling. This model may serve as a useful platform for understanding the mechanisms and treatments for PVS.

Development and Research of a Medium Vertical Dipole Electromagnetic Pulse Simulator

In this paper, the design of a self-developed EMP simulator with a 5 m height and an inverted conducting mono-cone antenna with a cone half-angle of 32° is introduced. The experimental region of the simulator is a circular area of 25 m in diameter around the cone vertex. Two feeding modes, feed-in over the ground and feed-in under the ground, are realized by two different high-voltage pulse sources. It can be concluded through radiation field testing that the radiation field waveform generated by the simulator has a rise time of 2–3 ns and a half-width of about 25 ns, meeting the specifications of the EMP experimental waveform in the IEC61000-2-9 standard. Meanwhile, the differences between the engineering implementation of the simulator and its ideal structure during the design process can lead to some distortion issues in the antenna radiation characteristics and the electromagnetic radiation field it generates. The radiation field waveform and the distribution of the EMP field generated by the simulator under different feeding methods, antenna wire quantities, antenna end processing methods, and different antenna resistive loading were studied, and the changes in the radiation field waveform and field distribution with different angles and distances of the monitoring point were analyzed. Based on the measurement results, the radiation characteristics of the antenna and the factors that affect the waveform of the field were studied and analyzed. Through the aforementioned work, a comprehensive understanding of the performance, radiation characteristics, and engineering factors affecting the electromagnetic environment generated by the simulator has been obtained. On this basis, the parameters of the antenna wire quantity, antenna end processing method, and test point position of the designed simulator were reconfirmed and optimized. In summary, this work has important reference significance for mastering the development technology of such simulators, understanding their antenna radiation characteristics, and conducting EMP-related assessments and effect experiments in the future.

Abstracts from The Aerosol Society Drug Delivery to the Lungs 33.

Abstracts from The Aerosol Society Drug Delivery to the Lungs 33.

Reproduction of human blood pressure waveform using physiology-based cardiovascular simulator

This study presents a cardiovascular simulator that mimics the human cardiovascular system's physiological structure and properties to reproduce the human blood pressure waveform. Systolic, diastolic blood pressures, and its waveform are key indicators of cardiovascular health. The blood pressure waveform is closely related to the pulse wave velocity and the overlap of the forward and reflected pressure waves. The presented cardiovascular simulator includes an artificial aorta made of biomimetic silicone. The artificial aorta has the same shape and stiffness as the human standard and is encased with a compliance chamber. The compliance chamber prevents distortion of the blood pressure waveform from strain-softening by applying extravascular pressure. The blood pressure waveform reproduced by the simulator has a pressure range of 80–120 mmHg, a pulse wave velocity of 6.58 m/s, and an augmentation index of 13.3%. These values are in the middle of the human standard range, and the reproduced blood pressure waveform is similar to that of humans. The errors from the human standard values are less than 1 mmHg for blood pressure, 0.05 m/s for pulse wave velocity, and 3% for augmentation index. The changes in blood pressure waveform according to cardiovascular parameters, including heart rate, stroke volume, and peripheral resistance, were evaluated. The same pressure ranges and trends as in humans were observed for systolic and diastolic blood pressures according to cardiovascular parameters.

Phenotypic screening using waveform analysis of synchronized calcium oscillations in primary cortical cultures.

At present, in vitro phenotypic screening methods are widely used for drug discovery. In the field of epilepsy research, measurements of neuronal activities have been utilized for predicting efficacy of anti-epileptic drugs. Fluorescence measurements of calcium oscillations in neurons are commonly used for measurement of neuronal activities, and some anti-epileptic drugs have been evaluated using this assay technique. However, changes in waveforms were not quantified in previous reports. Here, we have developed a high-throughput screening system containing a new analysis method for quantifying waveforms, and our method has successfully enabled simultaneous measurement of calcium oscillations in a 96-well plate. Features of waveforms were extracted automatically and allowed the characterization of some anti-epileptic drugs using principal component analysis. Moreover, we have shown that trajectories in accordance with the concentrations of compounds in principal component analysis plots were unique to the mechanism of anti-epileptic drugs. We believe that an approach that focuses on the features of calcium oscillations will lead to better understanding of the characteristics of existing anti-epileptic drugs and allow to predict the mechanism of action of novel drug candidates.

Theory and Application of Geostatistical Inversion: A Facies-Constrained MCMC Algorithm

To improve the prediction of thin reservoirs with special geophysical responses, a geostatistical inversion technique is proposed based on an in-depth analysis of the theory of geostatistical inversion. This technique is based on the Markov chain Monte Carlo algorithm, to which we added the contents of facies-constrained. The feasibility of the technique and the reliability of the prediction results are demonstrated by a prediction of the sand bodies in the braided river channel bars in the Xiazijie Oilfield in the Junggar Basin. Based on the MCMC algorithm, the results show that leveraging the lateral changes in the seismic waveforms as geologically relevant information to drive the construction of the variogram and the optimization of the statistical sampling can largely overcome the obstacle that prevents traditional geostatistical inversions from accurately delineating the sedimentary characteristics; thereby, the proposed algorithm truly achieves facies-constrained geostatistical inversion. The case study of the Xiazijie Oilfield showed the feasibility and reliability of this technology. The prediction accuracy of the FCMCMC algorithm-based geostatistical inversion is as high as 6 m for thin interbedded reservoirs, and the coincidence rate between the prediction results and the well log data is more than 85%, which confirms the reliability of the technique. The demonstrated performance of the proposed technique provides a preliminary reference for the prediction of the thin interbedded reservoirs formed in terrestrial sedimentary basins and characterized by small thicknesses and rapid lateral changes with special geophysical responses.

Use of portable devices to measure brain and heart activity during relaxation and comparative conditions: Electroencephalogram, heart rate variability, and correlations with self-report psychological measures

Recent technological advancements have enabled the development of portable devices that facilitate psychophysiological measurement in ecologically valid settings. The aim of the present study was to establish normative heart rate (HR), heart rate variability (HRV), and electroencephalogram (EEG) power during relaxation and comparative conditions. Fifty healthy adult participants completed baseline psychological questionnaires and subjective ratings of relaxation while portable devices measured continuous EEG, HR, and HRV data during eyes-open (EO) and eyes-closed (EC) resting, relaxation induction, and patting a toy dog (TD). Subjective relaxation levels were higher after the relaxation and TD compared to EO and EC resting conditions. Psychophysiological indications of relaxation included higher HRV during relaxation, and higher delta, theta, and alpha power during the TD condition. EEG recorded using a portable wireless single-channel device showed frontal EC versus EO differences comparable with those reported using traditional laboratory-based EEG equipment. Additionally, alpha power was positively correlated with resilience and negatively correlated with depression, anxiety, and stress. Delta power correlated positively with subjective relaxation levels during relaxation. Overall, the results suggest that portable devices can provide valid measurements of psychophysiological activity during relaxation outside of laboratory settings. Changes in HRV and EEG waveforms reveal more information about physiological relaxation and show promise for real-world monitoring in fields of study that investigate human arousal, stress, and health.