Response Waveform Research Articles

Improving Seaport Wharf Maintenance and Safety with Structural Health Monitoring System in High Salt and Humidity Environments

Due to the harsh working conditions, the durability of the seaport wharf structure is poor compared with similar hydraulic structures. According to the structural characteristics of coastal port wharf and the particularity of a high salt and high humidity environment, the stress features of the coastal wharf structure are analyzed, and the health inspection indicators of the wharf structure are proposed. A fiber grating sensor-based structural health monitoring system for coastal high-pile piers is established. A corresponding system for detecting structural health is designed according to the standard structural section of the wharf’s front platform. The corresponding monitoring implementation scheme, sensor selection, and performance parameters are proposed. Finally, the realization technology and related indicators of data acquisition and transmission subsystem are given. The experimental results indicate that the waveform of the structural response to the wave load has a consistent sine wave pattern with the actual wave load. The maximum strain of the berthing pier appears at 4.35 m and 6.14 m, and the elevations reach 4.66 με and 5.31 με, respectively. The strain at other positions also has an obvious change trend. The experimental results provide some help for the research of the wharf health monitoring system.

Model and data-driven homework problems for learning signal processing concepts

The Electrical and Computer Engineering Department at Portland State University offers a course in Sensor Array Processing. The content is designed to be introductory and approachable for undergraduate, first year graduate and students from other disciplines such as Mechanical Engineering or Physics. The signal processing techniques explored use two or more sensors and can be applied to acoustics or electromagnetic waves. I have two favorite homework problems: one is based on simulated data and the other based on measured data and both help solidify important concepts. For the simulations, a model is developed based on the method of images and can be applied to signals from a sonar in the ocean or to voices in a room. These multipath environments are used to illustrate how a signal (such as an audio clip the student creates) would change in different environments or source/receiver geometry. The channel impulse response is modeled and together with convolution allows different waveform responses to be easily computed. My favorite problem using measured data is based on recordings of a broadband source on two sensors. Cross-correlation is used to determine the source direction. This problem explores the concepts of pulse compression and pre-whitening for time-delay and direction estimation.

Shear wave elastography: From dispersion matching to full waveform inversion

Shear Wave Elastography (SWE) involves estimating mechanical properties through inversion, i.e., matching measured and simulated propagation characteristics of shear waves in the tissue. The accuracy of the estimated properties depends significantly on the specific characteristics/responses that are being matched. These could range from simple group velocity to dispersion curves and to full-wave response (particle velocity measurements). Using specific applications of arterial, liver, and tumor elstography, we illustrate that effective SWE is performed by resorting to an inversion approach, or combination of inversion approaches, guided by the underlying physics. To this end, we present inversion approaches ranging from matching dispersion characteristics to matching full waveform responses and provide rationale for choosing the appropriate technique(s) depending on the problem at hand.

Synthetic Data Resource and Benchmarks for Time Cell Analysis and Detection Algorithms.

Hippocampal CA1 cells take part in reliable, time-locked activity sequences in tasks that involve an association between temporally separated stimuli, in a manner that tiles the interval between the stimuli. Such cells have been termed time cells. Here, we adopt a first-principles approach to comparing diverse analysis and detection algorithms for identifying time cells. We generated synthetic activity datasets using calcium signals recorded in vivo from the mouse hippocampus using two-photon (2-P) imaging, as template response waveforms. We assigned known, ground truth values to perturbations applied to perfect activity signals, including noise, calcium event width, timing imprecision, hit trial ratio and background (untuned) activity. We tested a range of published and new algorithms and their variants on this dataset. We find that most algorithms correctly classify over 80% of cells, but have different balances between true and false positives, and different sensitivity to the five categories of perturbation. Reassuringly, most methods are reasonably robust to perturbations, including background activity, and show good concordance in classification of time cells. The same algorithms were also used to analyze and identify time cells in experimental physiology datasets recorded in vivo and most show good concordance.

Fast Detection Method on Water Tree Aging of MV Cable Based on Nonsinusoidal Response Measurement

A MV power cable will exhibit nonlinear impedance when dendritic defects appear. To solve the long time-consuming measurement of pure sinusoidal excitation and realize rapid and accurate evaluation of insulation conditions, a measurement and evaluation method based on nonsinusoidal excitation is proposed in this paper. Firstly, a nonsinusoidal excitation test system is established, which can obtain the high voltage dielectric response in the frequency range of 0.01 Hz–1 kHz. For parameterizing dielectric response characteristics of MV XLPE insulation under nonsinusoidal excitation, a Hammerstein-Wiener model is proposed to realize system parameter identification under non sinusoidal excitation with different aging degrees of water tree. The time-domain current response waveform based on the H-W model is more accurate than the traditional linear model, and the resulting fitting degree of the frequency-domain dielectric loss factor curve between the calculated H-W model and the measured curve was higher than 95%. The results show that the rotation and distortion of the u-i hysteresis ellipse under nonsinusoidal excitation can be used to diagnose the insulation defects of XLPE MV cables. The response model and its detection method proposed in this paper can improve the efficiency and accuracy of the field tests of cable insulation.

Features from the photoplethysmogram and the electrocardiogram for estimating changes in blood pressure

There is a growing emphasis being placed on the potential for cuffless blood pressure (BP) estimation through modelling of morphological features from the photoplethysmogram (PPG) and electrocardiogram (ECG). However, the appropriate features and models to use remain unclear. We investigated the best features available from the PPG and ECG for BP estimation using both linear and non-linear machine learning models. We conducted a clinical study in which changes in BP (DeltaBP) were induced by an infusion of phenylephrine in 30 healthy volunteers (53.8% female, 28.0 (9.0) years old). We extracted a large and diverse set of features from both the PPG and the ECG and assessed their individual importance for estimating DeltaBP through Shapley additive explanation values and a ranking coefficient. We trained, tuned, and evaluated linear (ordinary least squares, OLS) and non-linear (random forest, RF) machine learning models to estimate DeltaBP in a nested leave-one-subject-out cross-validation framework. We reported the results as correlation coefficient (rho _p), root mean squared error (RMSE), and mean absolute error (MAE). The non-linear RF model significantly (p<0.05) outperformed the linear OLS model using both the PPG and the ECG signals across all performance metrics. Estimating DeltaSBP using the PPG alone (rho _p = 0.86 (0.23), RMSE = 5.66 (4.76) mmHg, MAE = 4.86 (4.29) mmHg) performed significantly better than using the ECG alone (rho _p = 0.69 (0.45), RMSE = 6.79 (4.76) mmHg, MAE = 5.28 (4.57) mmHg), all p < 0.001. The highest ranking features from the PPG largely modelled increasing reflected wave interference driven by changes in arterial stiffness. This finding was supported by changes observed in the PPG waveform in response to the phenylephrine infusion. However, a large number of features were required for accurate BP estimation, highlighting the high complexity of the problem. We conclude that the PPG alone may be further explored as a potential single source, cuffless, blood pressure estimator. The use of the ECG alone is not justified. Non-linear models may perform better as they are able to incorporate interactions between feature values and demographics. However, demographics may not adequately account for the unique and individualised relationship between the extracted features and BP.

Enhancing power quality in solar-grid integrated systems with ANFIS-based control using split source inverters

Power generation and renewable energy consumption benefit greatly from integrated solar grid systems. However, the intermittent nature of solar electricity and potential voltage swings might raise power quality concerns when solar energy is integrated with the grid. The benefits of the split-source inverter architecture include higher efficiency, lower harmonic distortion, and the ability of power flow in both directions. The ANFIS controller improves the control parameters of the single-stage split-source inverter, eliminating power quality issues including voltage fluctuations, harmonics, and reactive power variations. These difficulties can negatively affect the overall quality of power. ANFIS-based control of the solar-grid integrated system guarantees optimal power conversion, precise voltage management, and higher power quality by intelligently altering the control settings. ANFIS solar electricity and potential voltage swings might raise power quality concerns when solar energy is integrated with the grid. Using an Adaptive Neuro-Fuzzy Inference System (ANFIS)- based control with split source inverters, this research provides a unique method to improve power quality in solar-grid integrated systems. The benefits of the split-source inverter architecture include higher efficiency, lower harmonic distortion, and the ability for power to flow in both directions. The ANFIS controller improves the control parameters of the single-stage split-source inverter, eliminating power quality issues including voltage fluctuations, harmonics, and reactive power variations. These difficulties can negatively impact the power's overall quality. ANFIS-based control of the solar-grid integrated system dynamically adjusts the voltage and current waveforms in response to variations in solar irradiation and grid circumstances. The simulation results show that the harmonic distortion is lowered, voltage stability is enhanced, and reactive power is managed more effectively.

A Novel Hybrid Brain-Computer Interface Combining the Illusion-Induced VEP and SSVEP.

Traditional single-modality brain-computer interface (BCI) systems are limited by their reliance on a single characteristic of brain signals. To address this issue, incorporating multiple features from EEG signals can provide robust information to enhance BCI performance. In this study, we designed and implemented a novel hybrid paradigm that combined illusion-induced visual evoked potential (IVEP) and steady-state visual evoked potential (SSVEP) with the aim of leveraging their features simultaneously to improve system efficiency. The proposed paradigm was validated through two experimental studies, which encompassed feature analysis of IVEP with a static paradigm, and performance evaluation of hybrid paradigm in comparison with the conventional SSVEP paradigm. The characteristic analysis yielded significant differences in response waveforms among different motion illusions. The performance evaluation of the hybrid BCI demonstrates the advantage of integrating illusory stimuli into the SSVEP paradigm. This integration effectively enhanced the spatio-temporal features of EEG signals, resulting in higher classification accuracy and information transfer rate (ITR) within a short time window when compared to traditional SSVEP-BCI in four-command task. Furthermore, the questionnaire results of subjective estimation revealed that proposed hybrid BCI offers less eye fatigue, and potentially higher levels of concentration, physical condition, and mental condition for users. This work first introduced the IVEP signals in hybrid BCI system that could enhance performance efficiently, which is promising to fulfill the requirements for efficiency in practical BCI control systems.

Development of a rating system assessing the quality of the service provided by drivers in a taxi aggregator company

This paper deals with the problem of quantitative description and improvement of the quality of the service provided by taxi aggregator companies working on the Russian market. This problem seems to be insufficiently addressed in open research publications due to its high specificity, though some research aiming at searching the quality metrics have been conducted for some companies worldwide. The goal of the current research is mathematical formalization of a rating system assessing the driver service quality that allows one to design a parametrically tunable model. The proposed mathematical model of the rating system is described by means of a state graph where the transition from a vertex to another happens when the explicitly written conditions are satisfied. We show that the rating evaluation for a driver remaining in the active can be carried out by means of linear filtration performed as digital signal processing of the time series consisting of the scores which are given to the driver by their passengers. The type and waveform of the filter impulse response is suggested. The A/B-test conducted for the group of drivers working with a taxi aggregator proved the fact that the integral metric of service quality is sensitive to changes in the parameters of the proposed rating system; this eventually led to a decrease in the rate of taxi rides accompanied with a negative client experience. The rating system model developed can be utilized to increase the quality of the service provided by the taxi aggregator by means of more effective differentiation of the drivers, while the subsequent optimization of the rating system parameters can serve as a tool for achieving indicators supporting the strategic goals of the company.

Semi-Automated Analysis of Peak Amplitude and Latency for Auditory Brainstem Response Waveforms Using R.

Many reports in the last 15 years have assessed changes in the auditory brainstem response (ABR) waveform after insults such as noise exposure. Common changes include reductions in the peak 1 amplitude and the relative latencies of the later peaks, as well as increased central gain, which is reflected by a relative increase in the amplitudes of the later peaks compared to the amplitude of peak 1. Many experimenters identify the peaks and troughs visually to assess their relative heights and latencies, which is a laborious process when the waveforms are collected in 5 dB increments throughout the hearing range for each frequency and condition. This paper describes free routines that may be executed in the open-source platform R with the RStudio interface to semi-automate the measurements of the peaks and troughs of auditory brainstem response (ABR) waveforms. The routines identify the amplitudes and latencies of peaks and troughs, display these on a generated waveform for inspection, collate and annotate the results into a spreadsheet for statistical analysis, and generate averaged waveforms for figures. In cases when the automated process misidentifies the ABR waveform, there is an additional tool to assist in correction. The goal is to reduce the time and effort needed to analyze the ABR waveform so that more researchers will include these analyses in the future.

Semi-Automated Analysis of Peak Amplitude and Latency for Auditory Brainstem Response Waveforms Using R

Semi Automated Analysis Peak Amplitude Latency For Auditory Brainstem - Video. JoVE publishes peer-reviewed scientific video protocols to accelerate biological, medical, chemical and physical research. Watch our scientific video articles. JoVE is the world-leading producer and provider of science videos with the mission to improve scientific research, scientific journals, and education. Millions of scientists, educators and students at thousands of universities, colleges, hospitals and biopharmaceutical companies worldwide use JoVE for their research, teaching and learning.

A case of spinal cord mapping using double train paradigm

Spinal cord tumor can have serious symptoms and postoperative sequelae. Accurate spinal cord mapping can be of great help because many structures are contained in a very narrow space. We tried to differentiate between the corticospinal tract (CT) and the dorsal column (DC) by introducing the double train stimulation paradigm as a first domestic case. The shapes of the first and second response waveforms with an intertrain interval of 60 ms were different for CT and DC, which can make identification of the two pathway. Additional cases are needed to determine the appropriate protocol because the test is not performed properly near the tumor and after myelotomy.

Modeling returned signal of a satellite laser altimeter over an urban area.

Modeling the returned signal of a satellite laser altimeter is a significant theoretical foundation for understanding the topography of the Earth. According to the lidar equation and working principle of laser altimeter, we establish the mathematical expression of the urban target response waveform (TRW) by using a definite integral formation. The characteristic parameters of the TRW, including signal energy, time delay, pulse width, and skewness are deduced in detail. Based on the specifications of the global ecosystem dynamics investigation laser altimeter and the assumption that the target is considered a rectangular plane, we simulate the influences of the geometrical parameters of the target, including the region area, the center geolocation, and the surface slope, on the TRW patterns and the characteristic parameters. The simulation results show that the TRW would present left-skewed and right-skewed patterns, with the exception that the center geolocation is nearly coincident with the laser footprint center. Such skewed distributions make the time delay derived from the TRW time centroid inaccurate for representing the range between the laser altimeter and the target center. In addition, the TRW energy is positively proportional to the region area and the proximity of the center geolocation to the laser footprint center and attenuated by the cosine of the surface slope. The root-mean-square pulse width is principally determined by the tangent of the surface slope. The simulation results contribute to a better understanding of the relationship between the TRW pattern and the geometrical parameters of the illuminated target. In particular, the characteristic parameters of the TRW can provide the detailed references for developing the waveform processing algorithm and the inversion of the surface elevation, the slope, and the reflectance. The returned signal in this paper may facilitate the application of the satellite laser altimeter over an urban area.

Identification of non-dimensional density distribution of concrete structures based on self-attention using hammering response data

The aging of concrete structures has become a serious problem in Japan, and periodic maintenance is essential for preventing accidents caused by structural aging. In this study, a method for estimating defects in concrete using data from hammering tests on a concrete plate using machine learning was developed. A neural network based on self-attention (SAN) to estimate the three-dimensional position and size of the defects was constructed. Moreover, a dataset was created from the topology of the internal defects and the acceleration response waveform when a concrete plate was struck. The entire plate was represented as a non-dimensional density matrix. The SAN used scalograms of the acceleration responses as the input. Furthermore, two types of data augmentation (‘Flip’ and ‘Rotate’) were proposed. The use of both data augmentation techniques achieved the highest accuracy. By setting an appropriate number of rotations, the model was able to estimate all defects in the dataset.

Fabrication and simulation of a piezoelectric PIN-PMN-PT thin film for ultrahigh-frequency ultrasonic transducers

Recently, ultrahigh-frequency (UHF) ultrasonic transducers (> 100 MHz) have been widely applied in research fields such as medical diagnostics, nondestructive testing, energy harvesting, and so on, due to their capability of creating high-resolution ultrasonic images and detecting micro-scale defects. To accomplish this, in this study, ternary Pb(In1/2Nb1/2)O 3 -Pb(Mg1/3Nb2/3)O 3 -PbTiO 3 (i.e., PIN-PMN-PT) polycrystalline single-phase thin film was fabricated for UHF ultrasonic transducers due to their extraordinary piezoelectric properties and electromechanical coupling coefficients. A tri-layered structure (of 1) aluminum substrate, 2) the PIN-PMN-PT thin film, and 3) a silver electrode) was used to create a PIN-PMN-PT thin film compatible with intense thermal treatment and having low cost. To analyze the performance of the newly developed PIN-PMN-PT thin film, data were collected on its crystallographic and piezoelectric characteristics, fabrication process, analysis of piezoelectric constants, and ultrasonic pulse-echo response waveforms according to different design conditions (various front matching layers, backing materials, and media). These data were provided by X-ray diffraction, X-ray fluorescence, X-ray reflectometry, field emission scanning electron microscopy, and polarization-electric field hysteresis curves. Moreover, pulse-echo simulation was conducted using PiezoCAD software based on the Krimholtz-Leedom-Matthaei model. The results showed that the proposed PIN-PMN-PT thin film exhibited ultrahigh-resonance frequencies of ∼ 500 MHz. Ultimately, it was concluded that the new high-frequency PIN-PMN-PT thin film could be applied in a variety of fields because its performance has been verified. • A ternary PIN-PMN-PT single crystal-based thin film for ultrahigh-frequency ultrasonic transducers was fabricated. • The performance of the newly developed PIN-PMN-PT thin film was analyzed in various ways to provide its characteristics. • In addition, pulse-echo simulations were conducted based on the Krimholtz-Leedom-Matthaei model for performance evaluation. • The results showed that the proposed PIN-PMN-PT thin film exhibited ultrahigh-resonance frequencies of ∼ 500 MHz.

Aortic waveform responses to insulin in late versus early chronotype with metabolic syndrome.

Late chronotype (LC) correlates with reduced metabolic insulin sensitivity and cardiovascular disease. It is unclear if insulin action on aortic waveforms and inflammation is altered in LC versus early chronotype (EC). Adults with metabolic syndrome (n = 39, MetS) were classified as either EC (Morning‐Eveningness Questionnaire [MEQ] = 63.5 ± 1.2) or LC (MEQ = 45.5 ± 1.3). A 120 min euglycemic clamp (40 mU/m2/min, 90 mg/dL) with indirect calorimetry was used to determine metabolic insulin sensitivity (glucose infusion rate [GIR]) and nonoxidative glucose disposal (NOGD). Aortic waveforms via applanation tonometry and inflammation by blood biochemistries were assessed at 0 and 120 min of the clamp. LC had higher fat‐free mass and lower VO2max, GIR, and NOGD (between groups, all p ≤ 0.05) than EC. Despite no difference in 0 min waveforms, both groups had insulin‐stimulated elevations in pulse pressure amplification with reduced AIx75 and augmentation pressure (AP; time effect, p ≤ 0.05). However, EC had decreased forward pressure (Pf; interaction effect, p = 0.007) with insulin versus rises in LC. Although LC had higher tumor necrosis factor‐α (TNF‐α; group effect, p ≤ 0.01) than EC, both LC and EC had insulin‐stimulated increases in TNF‐α and decreases in hs‐CRP (time effect, both p ≤ 0.01). Higher MEQ scores related to greater insulin‐stimulated reductions in AP (r = −0.42, p = 0.016) and Pf (r = −0.41, p = 0.02). VO2max correlated with insulin‐mediated reductions in AIx75 (r = −0.56, p < 0.01) and AP (r = −0.49, p < 0.01). NOGD related to decreased AP (r = −0.44, p = 0.03) and Pf (r = −0.43, p = 0.04) during insulin infusion. LC was depicted by blunted forward pressure waveform responses to insulin and higher TNF‐α in MetS. More work is needed to assess endothelial function across chronotypes.

Sole vein offenders confirmed by disappearance of the lateral spread response during microvascular decompression for hemifacial spasm

Sole vein offenders are rare and can be difficult to identify on preoperative magnetic resonance imaging (MRI) and intraoperative microscopy. The objective of this case review was to investigate factors resulting in successful decompression in venous offender cases. Among 234 cases of microvascular decompression surgery performed for hemifacial spasm from September 2020 to April 2022 at Konkuk University Medical Center, only two cases were identified as having a definite venous offender. We reviewed preoperative MRI and intraoperative microscopic findings and studied the correlation between decompression and lateral spread response (LSR) changes. Our two patients had possibility of a small venous offender on preoperative MRI, but it was ambiguous. A definite venous offender was identified on the operative microscopic findings and decompressed successfully, referring to the disappearance of the LSR waveform. Postoperatively, spasm disappeared or significantly improved. A venous offender is difficult to identify on preoperative MRI findings or even on intraoperative microscopic findings. In such cases, changes in the LSR waveform in response to decompressing the suspected vein can be a valuable reference for successful facial outcomes.

Characteristics of air-conducted and bone-conducted vibration cervical vestibular-evoked myogenic potential in preschool children

Objective: To investigate the characteristics of air-conducted sound cervical vestibular evoked myogenic potential （ACS-cVEMP） and bone-conducted vibration cervical vestibular evoked myogenic potential （BCV-cVEMP） in healthy preschool children, and to provide the normal reference range of VEMP for preschool children in China. Methods:Forty-four normal-hearing children （88 ears） aged 3-7 years were recruited to undergo ACS-cVEMP and BCV-cVEMP determination. These children were divided into two groups according to age: 3-4 years old group （ 17 cases, 34 ears） and 5-7 years old group （ 27 cases, 54 ears）. The response rates and waveform parameters were recorded and analyzed statistically using SPSS 18.0 software. Results:The response rates of ACS-cVEMP, BCV-cVEMP in 44 normal-hearing children （88 ears） were 96.59％（85/88） and 97.73％（86/88） respectively, and there was no significant difference between the two groups （P > 0.05）. The response rates of ACS-cVEMP in 3-4 year old group and 5-7 year old group were 94.12% （32/34） and 98.15% （53/54） respectively, and there was no significant difference between the two groups（P>0.05）; The response rates of BCV-cVEMP in 3-4 year old group and 5-7 year old group were 94.12% （32/34） and 100.00%（54/54） respectively, and there was no significant difference between the two groups （P>0.05）. Compared with the 5-7 year old group, the latency of p1 and n1 in the 3-4 year old group was shorter （P<0.05） and the amplitude was higher （P<0.05）, and there was no significant difference in other parameters （P>0.05）. There was no statistical difference in threshold, n1, p1 latency, n1-p1 wave interval, n1-p1 amplitude, and amplitude asymmetry ratio of BCV-cVEMP between the two groups （P>0.05）. Conclusion:ACS-cVEMP and BCV-cVEMP can be elicited in most preschool children, and cVEMP is a feasible method to detect vestibular function in children.

Altered Aortic Waveform Responses To Insulin In Late Chronotype With Metabolic Syndrome

PURPOSE: Late chronotype (LC) is linked to insulin resistance & cardiovascular disease. However, it is unclear if insulin reduces aortic waveforms & inflammation in LC versus early chronotype (EC). METHODS: Using the Morning-Eveningness Questionnaire (MEQ), adults with metabolic syndrome (MetS; 54.9 ± 1.1y; VO2MAX 22.2 ± 0.7 ml/kg/min, 3.5 ± 0.1 ATP-III score) were classified as either LC (n = 19 (16F); MEQ = 45.5 ± 1.3) or EC (n = 20 (16F); MEQ = 63.5 ± 1.2). A 120 min euglycemic clamp (40 mU/m2/min, 90 mg/dl) with indirect calorimetry was used to determine metabolic insulin sensitivity (glucose infusion rate (GIR)) & non-oxidized glucose disposal (NOGD; GIR-total carbohydrate oxidation). Aortic waveforms via applanation tonometry were taken at 0 & 120-min of the clamp & included augmentation index (AIx75), augmentation pressure (AP), pulse pressure amplification (PPA), mean arterial pressure (MAP), as well as forward (Pf) & backward (Pb) pulse wave. Inflammation (ICAM, VCAM, hs-CRP, TNF-α, & MMP-7) was also assessed before and after the clamp. RESULTS: While age, fat mass, & ATP III score were similar between groups, LC had higher FFM (P = 0.04) and lower VO2MAX (P = 0.05), GIR (P < 0.01) and NOGD (P < 0.01) than EC. No difference in 0 min waveforms were noted. Nonetheless, LC had increases in Pf versus EC (∆:1.9 ± 1.1 vs. -2.3 ± 1.0 mmHg; P = 0.007) during insulin infusion, though reflection magnitude decreased similarly (∆: -6.0 ± 2.2 vs. -5.9 ± 2.3%; P = 0.02). Further, both LC and EC had elevated PPA (∆: 0.04 ± 0.02 vs. 0.05 ± 0.02 mmHg; P = 0.02) & reduced AP (∆: -2.0 ± 1.0 vs. -2.8 ± 1.1 mmHg; P = 0.02) in response to insulin, while only EC had lower AIx75 (P = 0.02). LC had increased TNF-α (P = 0.04) and decreased MMP-7 (P = 0.04) in response to insulin, and EC decreased in hs-CRP (P = 0.009), ICAM (P = 0.009), and VCAM (P = 0.09). VO2MAX correlated with insulin-mediated reductions in AIx75 (r = -0.56, P < 0.01) and AP (r = -0.49, P < 0.01), while NOGD related to decreased AP during insulin (r = -0.44, P = 0.03) and Pf (r = -0.43, P = 0.04). Insulin-mediated reductions in VCAM also correlated with lower MAP during the clamp (r = 0.41, P = 0.03). CONCLUSIONS: LC was depicted by altered aortic waveform and inflammatory responses to insulin in MetS. More work is needed to assess peripheral endothelial function in chronotype. Funding: NIH RO1-HL130296

Nonlinear terahertz Kerr effect in quasi-2D MnPS3

The quadratic electro-optic effect (Kerr effect) is shown to be efficiently induced by a terahertz (THz) electric field in the quasi-two-dimensional (2D) material MnPS3. The waveform of the THz-induced response practically follows the intensity of the employed nearly single-cycle THz pulse. While neither THz-induced absorption nor the linear electro-optical effect are observed, we demonstrate that the THz electric field induces the refraction coefficient anisotropy experienced by light at the wavelength of 800 nm. In our experiment, the anisotropy results in polarization rotation of the light and corresponds to a nonlinear refractive index of the sample of approximately 13.1 × 10−14 W−1 cm2. This promotes the quasi-2D MnPS3 as a promising candidate for practical application in future ultrafast electro-optical devices.