Time-domain Measurements Research Articles

Immediate Effects of OM Chanting on Heart Rate Variability Measures Compared Between Experienced and Inexperienced Yoga Practitioners.

Background:Chanting “OM” is a form of meditation that has numerous health benefits. However, the neurophysiological mechanisms underpinning its effect are surprisingly scarce. The present study aimed to investigate the effect of OM chanting on autonomic modulation, using heart rate variability (HRV), on experienced yoga practitioners and yoga naïve persons.Methods:This prospective study included 19 yoga practitioners (9 females and 10 males; group mean age ± standard deviation [SD]; 25.9 ± 3.2 years) and 17 yoga naïve persons (8 females and 9 males; group mean age ± SD; 24.8 ± 3.6 years) of both sexes and similar age range. Both the groups were assessed for HRV indices (time and frequency domain measures) before and after loud OM chanting for 5 min.Results:Baseline comparison using Mann–Whitney U test between groups showed yoga practitioners had significantly increased high frequency (HF) power (P < 0.029) than nonyoga practitioners, signifying a state of tranquility before the chanting of OM. After 5 min of loud chanting of OM, a comparison between groups assessed using Wilcoxon Signed Ranks test revealed: HF Power, a component of the parasympathetic nervous system, was further amplified with a significantly increase (P < 0.001) in the yoga practitioners group compared to nonyoga practitioners. Furthermore, this increase in HF power was positively correlated with the years of experience in yoga.Conclusion:The present study showed that a brief chanting of OM (5 min) might enhance parasympathetic nervous system activity, promote relaxation, and provide calmness. Further, this experience may be achieved effectively in individuals experienced in yoga than nonyoga practitioners.

Left ventricular hypertrophy and sinus variability in arterial hypertension

Previous studies on heart rate variability (HRV) in systemic hypertension have yielded conflicting results. We sought to assess changes in HRV in hypertensive patients with or without left ventricular hypertrophy (LVH). In total, 112 patients with sinus rhythm hypertension, mean age 56 ± 10 years, without diabetes mellitus, symptomatic coronary artery disease or systolic dysfunction, were recruited prospectively. Echocardiographic examination allowed them to be subdivided into 3 groups: normal geometry (71), concentric remodeling (23) and LVH (18). HRV time and frequency domain measurements were obtained from 24-hour Holter ECG recordings in all patients and in 40 control subjects. In comparison with control subjects, the 3 hypertensive groups exhibited a significant decrease in SDNN and total frequency power, the two indices of overall HRV; a significant decrease in pNN50 and power at high frequency, indices of HRV reflecting parasympathetic tone, and a significant decrease in SDANN and power at low frequency, indices reflecting sympathetic modulation of HRV. Comparisons between the three hypertensive groups showed that patients with LVH had significantly ( P < 0.05) lower low frequency power (5.5 ± 1.0 Ln m2) than patients with normal left ventricular geometry. (5.9 ± 0.8 Ln m2) or a concentric remodeling (5.9 ± 0.9 Ln m2). Evaluation of HRV in hypertensive patients shows a constant decrease in parasympathetic indices and a more marked reduction in sympathetic parameters in the presence of LVH.

A broadband optical fiber transmission-based time domain measurement system for nanosecond-level transient electric field.

A novel nanosecond transient electric field (E-field) measurement system is developed in this paper to measure the E-field pulse caused by the operation of the high-voltage switch (switching E-field pulse) in the substation. An electrically small rod antenna is used as the receiving antenna and is matched by the operational amplifier with high input impedance to achieve broadband frequency response and stable working performance. A broadband analogoptical fiber transmission system is further designed based on the high-frequency circuit model of the electronic components. Unlike the traditional frequency domain E-field measurement methods, the developed measurement system can directly output the time domain waveform of the switching E-field pulse. It also has the advantages of adjustable sensitivity, portability, and anti-electromagnetic interference. The calibrated measurement bandwidth ranges from 200Hz to 680MHz. Furthermore, the switching E-field pulse in an ultra-high voltage substation is measured and analyzed to verify the effectiveness of the fabricated measurement system.

Technology for the Detection of Ablation Defects in Buffer Layers of High-Voltage Cables

This article discusses the main structure of HV cables as well as the characteristics of buffer layers and detection of ablation defects. To effectively detect ablation defects in the buffer layer, two approaches, terahertz time-domain measurements and commercial computed tomography (CT), were used in the laboratory to evaluate samples of cable with these defects and compare different preset conditions for detecting defects. The test results showed that the terahertz time domain measurement method was more sensitive than CT to moisture intrusion into the cable, but terahertz wave energy was reflected on the surface of the aluminum sheath of the cable and could not penetrate the sheath, thus, it was difficult to use this method to detect internal defects. The commercial CT method used X-rays to penetrate the aluminum sheath, and it could effectively obtain data for the three-dimensional reconstruction of each layer of material, other than the copper core. The structure of the cable was mapped through three-dimensional reconstruction using VGstudio Max software, and the three-dimensional map and gray value analysis were combined. The results confirmed that defects with different densities in the buffer layer could be detected by commercial CT. Thus, commercial CT detection methods provide an effective solution for identifying hidden defects in cables and have profound practical significance for the development of methods to detect defects when cables are in use.

Complex Permittivity and Thickness Evaluation of Low-Loss Dielectrics From Uncalibrated Free-Space Time-Domain Measurements

A free-space time-domain method is proposed to retrieve dielectric constant (<inline-formula> <tex-math notation="LaTeX">$\varepsilon _{r}$ </tex-math></inline-formula>), conductivity (<inline-formula> <tex-math notation="LaTeX">$\sigma _{e}$ </tex-math></inline-formula>), and thickness (<inline-formula> <tex-math notation="LaTeX">$d$ </tex-math></inline-formula>) of metal-backed low-loss dielectric samples using calibration-independent reflected power peak measurements. Its algorithm is validated by numerical calculations and simulations (CST Microwave Studio) using a sine-modulated Gaussian window. A sensitivity analysis is followed to examine its performance considering the dependencies of reflected power peaks with respect to <inline-formula> <tex-math notation="LaTeX">$\varepsilon _{r}$ </tex-math></inline-formula> and <inline-formula> <tex-math notation="LaTeX">$\sigma _{e}$ </tex-math></inline-formula>. Free-space time-domain measurements have been implemented after transforming frequency-domain measurements into time-domain ones to extract <inline-formula> <tex-math notation="LaTeX">$\varepsilon _{r}$ </tex-math></inline-formula>, <inline-formula> <tex-math notation="LaTeX">$\sigma _{e}$ </tex-math></inline-formula>, and <inline-formula> <tex-math notation="LaTeX">$d$ </tex-math></inline-formula> of polypropylene, polyethylene, and polyoxymethylene samples.

Time Reversal Communications With Channel State Information Estimated From Impedance Modulation at the Receiver

We determine the channel state information (CSI) of a multiple-input single-output (MISO) Rayleigh channel without prior communications between the transmitting antennas and the receiver. Our approach solely relies on an impedance modulation at the receiver and therefore circumvents the vexing need of a direct feedback between receiver and transmitters. We extract the wavefront to be transmitted in order to achieve optimal focusing on the receiver from a generalized Wigner-Smith operator (WSO). The latter is evaluated based on the scattering matrix of the transmit array measured in the two possible states of the receiver. Based on the CSI extracted via the WSO, any desired precoding technique can be implemented. Here, we show through in-situ time-domain measurements in a reverberation chamber that our approach closely reaches time-reversal performances in terms of focusing efficiency. We expect our approach to open up new perspectives for future wireless communications and wireless power transfer, including applications in the biomedical domain and electronic warfare.

Spectral and time domain fluorescence spectroscopy of gentisic acid molecule in protic and aprotic polymer matrix

In the present work, the effect of polymer microenvironment on the photophysics of gentisic acid molecule [2,5-dihydroxybenzoic acid] (GA), steady-state and time-domain fluorescence measurements at different pH conditions were carried out in protic [polyvinyl alcohol PVA] and aprotic [polymethyl methacrylate (PMMA)] polymer matrices. Change in the proticity of the microenvironment of the polymer traps different ionic species along with the neutral form of rotamer P and R conformers of GA molecule, are found to be responsible for the change in the spectral, multi-exponential decay behaviour. In protic polymer, the appearance of a single emission band indicates, dissociation of the GA molecule is very high, and it present as a monoanion along with hydrogen-bonded P and R rotamers. However, in the basic polymer film, most of the conformers of R converted to the anion. In contrast, protonation slows down the dissociation of both P and R forms in the acidic film. Unlike PVA matrix, in PMMA, dual emission band appears due to slow dissociation of GA molecule and hydrogen-bonded rotamer P, and R form exists with monoanion species. The magnitude of large stokes shifted red emission due to excited-state intramolecular proton transfers (ESIPT) found grater in rotamer P compared to its anionic species (green emission) and a blue emission corresponds to rotamer R.

Using Bluetooth Low Energy Technology to Perform ToF-Based Positioning

Many distributed systems that perform indoor positioning are often based on ultrasound signals and time domain measurements exchanged between low-cost ultrasound transceivers. Synchronization between transmitters and receivers is usually needed. In this paper, the use of BLE technology to achieve time synchronization by wirelessly triggered ultrasound transceivers is analyzed. Building on a previous work, the proposed solution uses BLE technology as communication infrastructure and achieves a level of synchronization compatible with Time of Flight (ToF)-based distance estimations and positioning. The proposed solution was validated experimentally. First, a measurement campaign of the time-synchronization delay for the adopted embedded platforms was carried out. Then, ToF-based distance estimations and positioning were performed. The results show that an accurate and low-cost ToF-based positioning system is achievable, using ultrasound transmissions and triggered by BLE RF transmissions.

Long-memory and volatility spillovers across petroleum futures

Return volatility usually presents a degree of persistence, which, although still consistent with an essential stationary process, cannot be adequately captured by standard autoregressive specifications. In this study, we examine the transmission mechanism across petroleum volatilities accounting for this stylized fact. To do so, we compute both time and frequency domain measures of connectedness based on variance decompositions from a fractionally integrated VAR (FIVAR). Our main findings summarize: (1) there is strong evidence of long-memory in petroleum volatilities, but no evidence of infinite variances; (2) an adequate quantification of spillovers must consider long-memory persistence explicitly; (3) spillovers are relatively high, but considerably lower than predicted in the traditional short-memory framework, especially at low frequencies. Thus, accounting for long-memory has asymmetric implications for different market participants.

Spectral pedestal during the kilowatt-level amplification of a random fiber laser operating near the lasing threshold.

The amplification of random fiber lasers (RFLs) attracts much attention due to their unique characteristics such as wavelength flexibility and low coherence. We present that, in the kilowatt-level amplification of RFL operating near its lasing threshold, a broad and flat spectral pedestal can co-exist with the narrow spectral peak of RFL. This phenomenon is different from the case in the amplification of fixed-cavity laser seeds. Time-domain measurements show that the broad and flat spectral pedestal, which extends to long wavelengths, is composed of temporal pulses, while few temporal pulses exist in the narrow spectral peak. We attribute the spectral pedestal to intensity fluctuations from the random seed laser and modulation instability in the amplification stage. Control experiments reveal that the working status of the random seed laser and the effective length of the amplifier can influence the spectral bandwidth. By taking advantage of this phenomenon, we propose a novel approach to achieve a high-power broadband light source through the amplification of RFLs operating near the lasing threshold.

Relationship Between Heart Rate Variability and Pulse Rate Variability Measures in Patients After Coronary Artery Bypass Graft Surgery.

Background: Heart rate variability (HRV) and pulse rate variability (PRV) measures are two kinds of physiological indices that can be used to evaluate the autonomic nervous function of healthy subjects and patients with various kinds of illness.Purpose: In this study, we compared the agreement and linear relationship between electrocardiographic signals (ECG)-derived HRV and photoplethysmographic signals (PPG)-derived right hand PRV (R-PRV) and left hand PRV (L-PRV) measures in 14 patients over 1 year after coronary artery bypass graft (CABG) surgery.Method: The ECG and PPG signals of the patient were recorded simultaneously for 10 min in a supine position. The last 512 stationary RR intervals (RRI) and peak-to peak intervals (PPI) of pulse wave were derived for data analysis. Bland-Altman plot was used to assess the agreement among HRV and both hand PRV measures, while linear regression analysis was used to examine the relationship among corresponding measures of HRV, R-PRV, and L-PRV.Result: The results revealed significant differences in total power (TP), very low-frequency power (VLF), low-frequency power (LF), high-frequency power (HF), and normalized VLF (VLFnorm) among HRV, R-PRV, and L-PRV. Bland-Altman plot analysis showed good agreements in almost all measures between R-PRV and L-PRV, except insufficient agreement was found in LF/HF. Insufficient agreements were found in root mean square successive difference (RMSSD), normalized HF (HFnorm), and LF/HF indices between HRV and L-PRV, and in VLFnorm, HFnorm, and LF/HF indices between HRV and R-PRV. Linear regression analysis showed that the HRV, R-PRV, and L-PRV measures were all highly correlated with one another (r = 0.94 ~ 1; p < 0.001).Conclusion: Though PRV measures of either hand are not surrogates of HRV measures, they might still be used to evaluate the autonomic nervous functions of CABG patients due to the moderate to good agreements in most time-domain and frequency-domain HRV measures and the strong and positive correlations among HRV and both hands PRV measures in CABG patients.

Superposition of 2ω and Electrostatic Field Induced Terahertz Waveforms in DC-Biased Two-Color Filament

Increase in conversion efficiency from a femtosecond optical pump into broadband terahertz (THz) radiation is currently an essential issue since it boosts THz source performance for medicine and security applications. An air-plasma based THz radiation from a two-color femtosecond filament is the most efficient gas-based THz emitter, with a dipole local source having a maximum on the beam propagation axis. In this work, we show the novel advancement to THz yield increase with preservation of the forwardly directed dipole radiation. The two-color THz source can be enhanced if the filament plasma channel is placed into an external electrostatic field (DC bias), which is parallel to the second harmonic polarization direction. In the experiment, we produce a plasma channel from 800-nm, ∼50-fs, 2-mJ pulse with 200 μJ of 400-nm, ∼50-fs mixed with the pump, and allocate it between the electrodes carrying 7-kV/cm static field. Time-domain measurements and 3D+time simulations of THz waveforms from the two-color DC-biased filament show that the THz emission is the superposition of the THz waveforms generated in the 800+400-nm filament without a DC-bias and in the 800-nm (without 400-nm) plasma channel biased by 7-kV/cm static field. The additivity of the two local dipole THz sources is possible if the majority of free electrons are produced by the pump pulse.

Objective frequency analysis of transient visual evoked potentials in autistic children.

Visual evoked potentials (VEPs) provide a means to examine neural mechanisms in autism with high temporal resolution. Conventional VEP analysis relies on subjective inspection of a few points (peaks and troughs) in the time-domain waveform. The current study applied power spectral analysis and magnitude-squared coherence (MSC) statistics (frequency-domain measures) to VEPs recorded during 1-minute runs and with a recently developed short-duration technique that allow for objective examination of the responses (Zemon & Gordon, European Journal of Neuroscience, 2018, 48, 1765-1788) from nonautistic and autistic children. Results indicate that, for both groups, early time-domain measures (P60 , N75 , P100 ) are highly correlated with middle- and high-frequency (14-28 and 30-48 Hz, respectively) mechanisms, and late measures are highly correlated with a low-frequency (6-12 Hz) mechanism. One frequency-domain measure (power in the middle-frequency band) is capable of predicting the key amplitude measure (N75 -P100 ) with high accuracy. MSC and power measures were combined to yield separate measures of signal and noise strength to evaluate alternate hypotheses in autism. Linear mixed-effects modeling demonstrated selective differences in early time-domain and middle-to-high frequency-domain measures in autistic children as compared to nonautistic children given both recording techniques, implicating weaker excitatory input to the cortex. Receiver-operating-characteristic curve analysis showed predictive diagnostic accuracy for middle- and high-frequency bands based on MSC. These findings support the value of frequency analysis measures (power spectral analysis and MSC) in the objective examination of neural differences in autism. LAY SUMMARY: Visual evoked potentials (VEPs) are used to assess neural mechanisms. Typically, VEPs are analyzed by subjective examination of time-series waveforms; but here objective techniques were applied to quantify VEP frequency components to investigate neural differences between autistic and nonautistic children. The objective measures demonstrate group differences in brain function that point to weaker excitatory input to the cortex in autism.

The electromechanical damping of piezo actuator resonances: Theory and practice

Piezo actuators have very desirable properties, such as a high stiffness and extreme position resolution, but suffer from electromechanical resonances that complicate their use in high-speed applications. These resonances can be minimized by using resistive or resistive-inductive damping.In this paper a comprehensive theory is presented which describes these piezo resonances, and the mechanism by which these resonances are minimized by adding electrical damping components. The theory is based on a purely electronic model, and uses an electrical-mechanical transformation to describe actual piezo displacements. Using this theory, an ‘optimal’ value of damping resistance is readily identified. This optimal resistance causes maximal damping of the primary resonance of the piezo. It is shown that damping with a combination of a resistor and an inductor can theoretically be even better.An optical displacement setup was developed, and frequency- and time-domain measurements were performed that validate the theory. The mechanical damping of the piezo actuator needs to be included in the theory to obtain a good fit with the electrical and mechanical behavior of an actual piezo actuator.

Seismic topology optimization based on spectral approaches

In this study, the structural design problem under earthquake excitations is handled using the proposed topology optimization scheme that successfully copes with the complexity of seismic loading. To achieve this success, the optimization scheme is formulated based on response spectrum method, adequately balancing the accuracy and computational cost in calculating seismic responses of structures. Also, an interpolation strategy, providing smooth curves to supersede the non-differentiable response spectra, is suggested to ensure that the derivatives of spectral values can be obtained for the sensitivity analysis. In addition, the terms including the derivatives of eigenvectors in the sensitivity expressions are annihilated through the derived adjoint approach, which is more accurate and convenient compared with directly solving the derivatives of eigenvectors. In the present numerical examples, the specified seismic responses of the optimized structures are significantly reduced, and these reductions are also observed in the time-domain measurement. Therefore, the efficacy of the proposed optimization scheme is validated.

Time-domain measurement of coherent transition radiation using a photoconductive antenna with micro-structured electrodes

The longitudinal electric field profile of coherent transition radiation (CTR), which is a radially polarized terahertz (THz) pulse from an electron bunch, was measured using a large-aperture photoconductive antenna (PCA) with a diameter of 8.8 mm and micro-structured concentric electrodes to detect THz light pulses. Photo-induced charge carriers were generated on the PCA by the irradiation of femtosecond laser pulses on the electrode plane. Pulsed light irradiation enabled time-resolved measurement of the THz light pulses, and time-domain measurement of CTR was conducted by measuring the electric-field-induced current output from the PCA by sweeping the timing of the laser irradiation. The frequency spectra obtained from the detected longitudinal electric field profiles of the CTR showed a reasonable response signal from the low-frequency region as low as 0.1 THz. In the present demonstration, the large-aperture PCA-detected THz wave from the CTR was from 0.1 to at least 1 THz. THz generation using the PCA was also performed and measured using a Michelson interferometer with a helium-cooled bolometer. Comparison of the THz pulse of the CTR detected using the PCA and that generated using the PCA revealed that time-domain measurement of the THz pulse using the PCA was limited by the response time of the charge carriers in the semiconductor. Enlargement of the aperture of the PCA enhanced the detectable frequency region toward a lower frequency.

Investigation of Light Parameters on Image Quality and Optical Coherence Tomography

In this work, image quality and optical coherence tomography were studied. The results of the study show that there is a very significant difference between ultrasound and optical coherence tomography to produce an image with a different wave. To understand this, we studied the basic principle of optical coherence tomography in the Michelson interferometer using monochromatic and broadband sources. Time-domain and spectral-domain measurements, which exist at the detector level, are briefly described using a glass sample. The time-domain signal strength of the Michelson interferometer using a broadband source is a Gaussian envelope.

Abstract 14228: Mechanism of Atrial Fibrillation in an Animal Model of Inflammatory Bowel Disease

Introduction: Ulcerative colitis (UC) is an i nflammatory bowel disease with a relapsing and remitting course. UC has extraintestinal manifestations and UC patients exhibit twice the risk for atrial fibrillation (AF) during acute disease activity. The mechanism of AF due to UC remains to be determined. Hypothesis: During acute UC a dysregulation of vagal signaling increases a patients propensity for AF. Methods: Mice (male, C57BL/6) were treated with Dextran Sulfate Sodium (DSS: 3%) supplemented drinking water for 7days that disrupts intestinal barrier function and mimics the disease phenotype of acute UC. Changes in atrial electrophysiology were quantified in vivo (EKG), on the whole heart (Langendorff configuration) and the cellular level (Fluo-4AM) during peak inflammation (DSS A ) and remission (DSS R ). Results: DSS A mice exhibited an attenuated heart rate (HR) in vivo (CTL: 491 ± 11 bpm, n=10; DSS A : 448 ± 11 bpm, n=16; p&lt;0.05) and in excised perfused hearts (Langendorff configuration: CTL: 321 ± 15 bpm, n = 3; DSS A : 256 ± 17 bpm, n = 4; p &lt; 0.05). The P-wave duration was prolonged (in vivo, CTL: 25.5 ± 0.6 ms, n=10; DSS A : 30.2 ± 0.5 ms, n=16; p &lt; 0.0001) and HR variability time-domain measure RR-corrected SDNN was attenuated (CTL: 11.3 ± 1.1 ms, n=10; DSS A : 8.2 ± 0.7 ms, n=16; p &lt; 0.05). The latter is an indicator for an attenuated vagal tone in DSS A mice and coincided with an increased sensitivity to the vagal agonist Carbachol in-vivo (CCh 150 ng/g, change in HR: CTL: -3.8 ± 4.4 %, n=6; DSS A : -42.2 ± 4.8 %, n=10; p &lt; 0.0001). After burst pacing DSS A hearts exhibited a prolonged RR-corrected sinus node recovery time (CTL: 11.2 ± 1.4 ms, n=3; DSS A : 25.5 ± 2.1 ms, n=4; p &lt; 0.0001), an increased AF propensity, and prolonged duration of AF episodes (CTL: 0.8 ± 0.17 s, n=3; DSS A : 2.4 ± 0.31 s, n=4; p &lt; 0.05) even in the absence of CCh. No changes in atrial myocyte Ca handling properties were determined. After remission HR, P-wave duration, and HRV in DSS R returned to control values. Conclusions: The data suggests that acute UC increases the risk for AF likely as a consequence of an attenuated sinus rhythm and atrial conduction velocity where vagal stimuli could exacerbate the risk for reentry of excitation. If these changes are the direct consequence of the attenuated vagal tone remains to be determined.

Short-term effects of natural view and daylight from windows on thermal perception, health, and energy-saving potential

The connection of nature has been demonstrated to have a positive effect on humans' health, behaviors, and well-being. In buildings, the visual window can provide natural views and daylight to the indoors, which may have a similar effect on occupants. This study explored the influence of the natural views and daylight from visual windows on thermal perception, health, and energy-saving potential, conducting a laboratory experiment with twenty participants in spaces with and without windows, and set three temperatures at 17 °C, 20 °C, and 23 °C, as cool, slightly cool, and neutral thermal conditions. The measurement included environmental parameters, physiological parameters, e.g., arterial oxygen saturation (SpO2) and heart rate variability (HRV), and subjective questionnaires, e.g., thermal perceptions, emotions. The results showed that participants with a visual window felt more comfortable (0.44 thermal comfort vote) in a cool condition. Additionally, SpO2 increased, indicating reduced sick building syndrome (SBS) symptoms, while the time-domain measurements of HRV increased, indicating stress and fatigue were reduced. Daylight had no positive effect on lighting perception but had energy-saving potentials (82% in this experiment). The visual window improved the occupants’ tolerance to the thermal environment, which will have energy-saving potentials of about 1.21 °C setpoint adjustments of HVAC. This research provides evidence that biophilic design elements impact thermal comfort, stress level, and fatigue. It also demonstrated the energy-saving potentials of visual windows.

Interictal autonomic changes in persons with epilepsy (PWE) on carbamazepine (CBZ) versus other anti-seizure drug monotherapy: A cross-sectional study

ObjectiveEpilepsy is one of the most prevalent neurological conditions and carbamazepine is a commonly used anti-seizure drug (ASD), especially in developing nations. There are reports of carbamazepine causing atrioventricular conduction defects and autonomic dysfunctions and its implication in Sudden Unexpected Death in Epilepsy (SUDEP) is controversial. We planned this study to assess the effect of carbamazepine (CBZ) on autonomic function compared to other ASDs in persons with epilepsy. MethodsIn this cross-sectional study, we assessed the sympathetic and parasympathetic autonomic functions in persons with epilepsy (PWE) on CBZ versus other anti-seizure monotherapy using tests of heart rate variability including its time-, frequency- and non-linear domains, heart rate response to deep breathing, valsalva maneuver, and blood pressure response to isometric handgrip. ResultsPersons with epilepsy on CBZ monotherapy did not show a significant reduction in the time domain parameter SDRR compared to other ASDs used as monotherapy (mean ± SD, 38.04 ± 18.75 ms vs 44.37 ± 20.35 ms; p = 0.125). However, PWE on CBZ had significantly lower time-domain measurements including RMSSD (mean ± SD 31.95 ± 17.29 ms vs 42.02 ± 22.29 ms; p = 0.018), SDSD (mean ± SD 31.91 ± 17.26 ms vs 41.96 ± 22.27 ms; p 0.018), and pNN50 [median (IQR) 05.45(0.69–25.37) vs 16.38(2.32–36.83); p = 0.030]. Frequency domain measures of HRV, heart rate responses to deep breathing, valsalva maneuver and tilt-testing and BP responses to valsalva and tilt-testing were not significantly different between the groups. ConclusionThe findings of our study indicate reduced parasympathetic activity in persons on CBZ monotherapy compared to other ASDs, which may pose risk of SUDEP. Carbamazepine may thus be avoided in those at risk of autonomic dysfunction and SUDEP.