Low High Frequency Research Articles

Design and experimental study of a planar piezoelectric actuator with resonant actuation

Planar piezoelectric actuators, which can achieve high-precision motions over a wide range, have been widely applied in high-end equipment fields. However, the existing planar piezoelectric actuators can no longer meet the high actuation characteristics required for the rapidly development of these fields, which include large travel, high resolution, fast speed, planar three degrees of freedom (3-DOF) and a compact structure. A planar piezoelectric actuator with resonant actuation is proposed and tested in this work. The actuator consists of four symmetrically configured uniform bending-bending hybrid piezoelectric units, which coordinate to achieve large travel and planar 3-DOF characteristics. A vibration isolation mechanism adopting thin beam structure with low stiffness in coupling directions is designed to achieve vibration isolation among the units. The actuator can operate in high frequency resonance mode and low frequency stepping mode, allowing for the achievement of high-speed and high-resolution characteristics. A prototype is fabricated and tested. A compact structure measuring 53 mm × 53 mm × 13 mm and weighing only 30.2 g has been achieved. The maximum linear and rotary speeds have been tested to be over 400 mm/s and 13 rad/s, respectively. The linear and rotary resolutions are 0.42 μm and 12.9 μrad, respectively. The proposed actuator achieves characteristics of large travel, high resolution, fast speed, 3-DOF and a compact structure.

Unilateral periocular spasm.

Hemifacial spasm is an uncontrollable, recurrent facial muscular contraction that typically occurs on one side of the face, cannot be suppressed, and can last the entire day and during sleep. The most common underlying cause of facial nerve compression is an enlarged or abnormal tracking blood vessel at the brainstem level. Clinical diagnoses are frequently based on a patient's medical history and physical examination. Before deciding on a course of action, however, an electromyogram and MRI are performed to determine the underlying cause. Due to its high effectiveness (success rates of 85% to 95%) and low frequency of adverse reactions, botulinum toxin is the preferred therapy for hemifacial spasm and can provide transient symptomatic alleviation. Surgical microvascular decompression is a therapeutic approach that targets the underlying cause of this condition and has an average success rate of 85%.

Detection of defects during laser-powder interaction by acoustic emission sensors and signal characteristics

Acoustic Emission (AE) sensing is an in-situ real-time nondestructive monitoring method proposed for Additive Manufacturing (AM) to detect defects such as cracks. Previous AE research in AM mainly focused on developing algorithms to automatically detect the defects from AE signals without understanding the physical mechanisms or the signal characteristics that could be used as identifiers. We study AE signals during a laser spot welding on a powder bed to clearly distinguish between different physical mechanisms using their signal characteristics. We identified specific signals associated with 1) tensile cracks from cooling, 2) a powder effect on the substrate, and 3) sudden thermal expansion of the substrate. We used the spectral ratio between high frequency (70–150 kHz) and low frequency (10–40 kHz) spectral amplitudes in the frequency domain to classify and differentiate the source types. We found that porosity due to insufficient energy density did not produce detectable AE signals. Using a ball drop calibration technique, we used AE signals to estimate the absolute sizes of the tensile cracks. Crack sizes ranged from 40 μm to 1 mm and were in general agreement with scanning electron microscope images of the fractures. We performed a line scanning test and successfully validated its potential for the application. Our findings provide a basic understanding of AE signal characteristics in AM, as well as the practical parameters used to separate the signal types.

Looming Angry Faces: Preliminary Evidence of Differential Electrophysiological Dynamics for Filtered Stimuli via Low and High Spatial Frequencies.

Looming motion interacts with threatening emotional cues in the initial stages of visual processing. However, the underlying neural networks are unclear. The current study investigated if the interactive effect of threat elicited by angry and looming faces is favoured by rapid, magnocellular neural pathways and if exogenous or endogenous attention influences such processing. Here, EEG/ERP techniques were used to explore the early ERP responses to moving emotional faces filtered for high spatial frequencies (HSF) and low spatial frequencies (LSF). Experiment 1 applied a passive-viewing paradigm, presenting filtered angry and neutral faces in static, approaching, or receding motions on a depth-cued background. In the second experiment, broadband faces (BSF) were included, and endogenous attention was directed to the expression of faces. Our main results showed that regardless of attentional control, P1 was enhanced by BSF angry faces, but neither HSF nor LSF faces drove the effect of facial expressions. Such findings indicate that looming motion and threatening expressions are integrated rapidly at the P1 level but that this processing relies neither on LSF nor on HSF information in isolation. The N170 was enhanced for BSF angry faces regardless of attention but was enhanced for LSF angry faces during passive viewing. These results suggest the involvement of a neural pathway reliant on LSF information at the N170 level. Taken together with previous reports from the literature, this may indicate the involvement of multiple parallel neural pathways during early visual processing of approaching emotional faces.

Healthy lifestyle and essential metals attenuated association of polycyclic aromatic hydrocarbons with heart rate variability in coke oven workers

Whether adopting healthy lifestyles and maintaining moderate levels of essential metals could attenuate the reduction of heart rate variability (HRV) related to polycyclic aromatic hydrocarbons (PAHs) exposure are largely unknown. In this study, we measured urinary metals and PAHs as well as HRV, and constructed a healthy lifestyle score in 1267 coke oven workers. Linear regression models were used to explore the association of healthy lifestyle score and essential metals with HRV, and interaction analysis was performed to investigate the potential interaction between healthy lifestyle score, essential metals, and PAHs on HRV. Mean age of the participants was 41.9 years (84.5% male). Per one point higher healthy lifestyle score was associated with a 2.5% (95% CI, 1.0%–3.9%) higher standard deviation of all normal to normal intervals (SDNN), 2.1% (95% CI, 0.5%–3.6%) higher root mean square of successive differences in adjacent NN intervals (r-MSSD), 4.3% (95% CI, 0.4%–8.2%) higher low frequency, 4.4% (95% CI, 0.2%–8.5%) higher high frequency, and 4.4% (95% CI, 1.2%–7.6%) higher total power, respectively. Urinary level of chromium was positively associated with HRV indices, with the corresponding β (95% CI) (%) was 5.17 (2.84, 7.50) for SDNN, 4.29 (1.74, 6.84) for r-MSSD, 12.26 (6.08, 18.45) for low frequency, 12.61 (5.87, 19.36) for high frequency, and 11.31 (6.19, 16.43) for total power. Additionally, a significant interaction was found between healthy lifestyle score and urinary total hydroxynaphthalene on SDNN (Pinteraction = 0.04), and higher level of urinary chromium could attenuate the adverse effect of total hydroxynaphthalene level on HRV (all Pinteraction <0.05). Findings of our study suggest adopting healthy lifestyle and maintaining a relatively high level of chromium might attenuate the reduction of HRV related to total hydroxynaphthalene exposure.

The optimal Holmium laser settings for disintegration of cystine and calcium oxalate monohydrate stones: In vitro study

ABSTRACT Objective Disintegrating cystine and calcium oxalate monohydrate stones present a formidable challenge owing to their hardness and distinct composition. This study aimed to establish optimal laser settings for these hard stones lithotripsy. Patients and Methods Cystine and calcium oxalate monohydrate stones were extracted from two patients. Two experiments were conducted in vitro by utilizing a 272 μm laser fiber with variable settings to disintegrate the cystine and calcium oxalate monohydrate stones. In the first experiment, energy was adjustable while frequency was constant, whereas the second experiment involved constant energy with adjustable frequency on each type of stone and each experiment was repeated three times to ensure robustness and reliability. Results Our findings indicated that for cystine stones, use of higher total power with high energy and low frequency proved to be effective. Conversely, for calcium oxalate monohydrate stones, settings involving higher total power with low energy and high frequency demonstrated superior efficacy and safety. Conclusion Holmium (Ho: YAG) laser settings with higher total power, high energy, and low frequency effectively disintegrate cystine stones despite increased heat, which was measured by a thermometer with a thermocouple. For calcium oxalate monohydrate stones, higher total power, high frequency, and low energy settings are recommended and safe.

Low-Intensity Focused Ultrasound to the Human Dorsal Anterior Cingulate Attenuates Acute Pain Perception and Autonomic Responses.

The dorsal anterior cingulate cortex (dACC) is a critical brain area for pain and autonomic processing, making it a promising noninvasive therapeutic target. We leverage the high spatial resolution and deep focal lengths of low-intensity focused ultrasound (LIFU) to noninvasively modulate the dACC for effects on behavioral and cardiac autonomic responses using transient heat pain stimuli. A N = 16 healthy human volunteers (6 M/10 F) received transient contact heat pain during either LIFU to the dACC or Sham stimulation. Continuous electroencephalogram (EEG), electrocardiogram (ECG), and electrodermal response (EDR) were recorded. Outcome measures included pain ratings, heart rate variability, EDR response, blood pressure, and the amplitude of the contact heat-evoked potential (CHEP).LIFU reduced pain ratings by 1.09 ± 0.20 points relative to Sham. LIFU increased heart rate variability indexed by the standard deviation of normal sinus beats (SDNN), low-frequency (LF) power, and the low-frequency/high-frequency (LF/HF) ratio. There were no effects on the blood pressure or EDR. LIFU resulted in a 38.1% reduction in the P2 CHEP amplitude. Results demonstrate LIFU to the dACC reduces pain and alters autonomic responses to acute heat pain stimuli. This has implications for the causal understanding of human pain and autonomic processing in the dACC and potential future therapeutic options for pain relief and modulation of homeostatic signals.

Synchronization and firing mode transition of two neurons in a bilateral auditory system driven by a high–low frequency signal

The FitzHugh–Nagumo neuron circuit integrates a piezoelectric ceramic to form a piezoelectric sensing neuron, which can capture external sound signals and simulate the auditory neuron system. Two piezoelectric sensing neurons are coupled by a parallel circuit consisting of a Josephson junction and a linear resistor, and a binaural auditory system is established. Considering the non-singleness of external sound sources, the high–low frequency signal is used as the input signal to study the firing mode transition and synchronization of this system. It is found that the angular frequency of the high–low frequency signal is a key factor in determining whether the dynamic behaviors of two coupled neurons are synchronous. When they are in synchronization at a specific angular frequency, the changes in physical parameters of the input signal and the coupling strength between them will not destroy their synchronization. In addition, the firing mode of two coupled auditory neurons in synchronization is affected by the characteristic parameters of the high–low frequency signal rather than the coupling strength. The asynchronous dynamic behavior and variations in firing modes will harm the auditory system. These findings could help determine the causes of hearing loss and devise functional assistive devices for patients.

Data Analysis of Heart Rate Variability and Arrhythmia in Patients with Paroxysmal Atrial Fibrillation.

Atrial fibrillation (AF) is the most common type of arrhythmia. Heart rate variability (HRV) may be associated with AF risk. The aim of this study was to test HRV indices and arrhythmias as predictors of paroxysmal AF based on 24-hour dynamic electrocardiogram recordings of patients. A total of 199 patients with paroxysmal AF (AF group) and 204 elderly volunteers over 60 years old (Control group) who underwent a 24-hour dynamic electrocardiogram from August 2022 to March 2023 were included. Time-domain indices, frequency-domain indices, and arrhythmia data of the two groups were classified and measured. Binary logistic regression analysis was performed on variables with significant differences to identify independent risk factors. A nomogram prediction model was established, and the sum of individual scores of each variable was calculated. Gender, age, body mass index and low-density lipoprotein (LDL) did not differ significantly between AF and Control groups (p > 0.05), whereas significant group differences were found for smoking, hypertension, diabetes, and high-density lipoprotein (HDL) (p < 0.05). The standard deviation of all normal to normal (NN) R-R intervals (SDNN), standard deviation of 5-minute average NN intervals (SDANN), root mean square of successive NN interval differences (rMSSD), 50 ms from the preceding interval (pNN50), low-frequency/high-frequency (LF/HF), LF, premature atrial contractions (PACs), atrial tachycardia (AT), T-wave index, and ST-segment index differed significantly between the two groups. Logistic regression analysis identified rMSSD, PACs, and AT as independent predictors of AF. For each unit increase in rMSSD and PACs, the odds of developing AF increased by 1.0357 and 1.0005 times, respectively. For each unit increase in AT, the odds of developing AF decreased by 0.9976 times. The total score of the nomogram prediction model ranged from 0 to 110. The autonomic nervous system (ANS) plays a pivotal role in the occurrence and development of AF. The individualized nomogram prediction model of AF occurrence contributes to the early identification of high-risk patients with AF.

Unsharp Masking of Medical Images using Rolling Guidance Filter

Medical Images consists of both high frequency and low frequency information needed by Physician for diagnostics and treatment purpose. Since, human eye is sensitive to high frequency information, the enhancement of high frequency information of medical image is very important. Most image enhancement techniques use the traditional unsharp mask filter to enhance the detail and edge information of medical image. While enhancing the detail and edge information, Gaussian Filter in traditional Unsharp Masking Filter introduces halo effects around edges. To remove this halo effects in enhanced images, this paper proposes a novel image enhancement filter in which Gaussian Filter is replaced by rolling guidance filter. This method provides satisfying results over Traditional Unsharp Mask Filter, Amended Unsharp Mask Filter, Anisotropic Diffusion based Unsharp Mask Filter and Guided Filtering based Unsharp Mask Filter in terms of high frequency information measures like mean gradient, spatial frequency and sharpness.

Cerebral Hemodynamics and Vagally Mediated HRV Associated with High- and Low-frequency Yoga Breathing: An Exploratory, Randomized, Crossover Study.

Volitionally modifying respiration leads to changes in middle cerebral arterial (MCA) blood flow. The effect of changes in breath rate on MCA blood flow has not been reported. To determine the effect of slow (bumblebee yoga breathing) and fast (high frequency yoga breathing) yoga breathing techniques on MCA blood flow and vagally mediated heart rate variability. Thirty participants (mean age ± standard deviation, 27.3 ± 4.2 years) were assessed on 2 separate days practicing either high frequency yoga breathing (HFYB, breath frequency 54.2/min) or slow frequency bumblebee yoga breathing (BBYB, breath frequency 3.8/min) in random order to determine the effects of changes in breath frequency on MCA hemodynamics. Assessments included transcranial Doppler sonography, vagally mediated heart rate variability (VmHRV), and respiration. Both HFYB and BBYB (i) reduced MCA flow velocities, i.e., peak systolic, end diastolic, and mean flow velocities, and (ii) increased MCA pulsatility indices. There was an increase in VmHRV during BBYB based on increased power in high frequency (HF) and low frequency (LF). LF reflects VmHRV for slow breath frequencies. In BBYB the average breath rate was 3.8 breaths/min. In contrast, VmHRV decreased during HFYB (based on reduced HF power; repeated measures analysis of variance, P < 0.05, all cases). Hence, irrespective of the differences in breath frequency, both HFYB and BBYB appear to reduce MCA flow velocities and increase the resistance to blood flow bilaterally, although the VmHRV changed in opposite directions. MCA velocity and pulsatility changes are speculated to be associated with low global neural activity during yoga breathing.

Low-frequency repetitive transcranial magnetic stimulation for the treatment of post-traumatic stress disorder and its comparison with high-frequency stimulation: a systematic review and meta-analysis.

Repetitive transcranial magnetic stimulation (rTMS) showed potentially beneficial effects for the treatment of post-traumatic stress disorder (PTSD). Low-frequency (LF) rTMS decreases neuronal excitability and may have better safety compared to high-frequency (HF) rTMS. However, there lacks meta-analysis specifically focusing on LF rTMS. To specifically explore the efficacy and safety of LF rTMS for treating PTSD. Databases including PubMed, EMBASE, MEDLINE, and Web of Science were systematically searched from inception to October 17, 2023. Both randomized controlled trials (RCTs) and open trials of LF rTMS on PTSD were included, and we additionally included RCTs comparing HF rTMS and sham treatment on PTSD. First, we qualitatively summarized parameters of LF rTMS treatment; then, we extracted data from the LF rTMS treatment subgroups of these studies to examine its effect size and potential influencing factors; third, we compared the effect sizes among LF rTMS, HF rTMS and sham treatment through network meta-analysis of RCTs. In all, 15 studies with a sample size of 542 participants were included. The overall effect size for LF rTMS as a treatment for PTSD was found as Hedges' g = 1.02 (95% CI (0.56, 1.47)). Meta-regression analysis did not reveal any influencing factors. Network meta-analysis showed that compared to sham treatment, only HF rTMS on the right dorsolateral prefrontal cortex (DLPFC) demonstrated a significant advantage in ameliorating PTSD symptoms, while LF rTMS on the right DLPFC showed a trend toward advantage, but the difference was not significant. The current literature shows LF rTMS has effect in treating PTSD caused by various traumatic events. However, present limited number of RCT studies only showed LF rTMS to have a trend of advantage compared to sham treatment in treating PTSD caused by external traumatic events. In the future, more RCTs are needed to be made to confirm the efficacy of LF rTMS. Additionally, studies are required to elucidate the underlying mechanism in order to further improve its efficacy in different traumatic populations. CRD42023470169.

A Cascaded Network With Coupled High-Low Frequency Features for Building Extraction

A Cascaded Network With Coupled High-Low Frequency Features for Building Extraction

Global existence for perturbations of the 2D stochastic Navier–Stokes equations with space-time white noise

We prove global in time well-posedness for perturbations of the 2D stochastic Navier–Stokes equations ∂tu+u·∇u=Δu-∇p+ζ+ξ,u(0,·)=u0,div(u)=0,\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\begin{aligned} \\partial _t u + u \\cdot \ abla u= & {} \\Delta u - \ abla p + \\zeta + \\xi \\;, \\qquad u (0, \\cdot ) = u_{0} \\;,\\\\ {\ ext {div}}(u)= & {} 0 \\;, \\end{aligned}$$\\end{document}driven by additive space-time white noise ξ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\xi $$\\end{document}, with perturbation ζ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\zeta $$\\end{document} in the Hölder–Besov space C-2+3κ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathcal {C}^{-2 + 3\\kappa } $$\\end{document}, periodic boundary conditions and initial condition u0∈C-1+κ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ u_{0} \\in \\mathcal {C}^{-1 + \\kappa } $$\\end{document} for any κ>0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\kappa >0 $$\\end{document}. The proof relies on an energy estimate which in turn builds on a dynamic high-low frequency decomposition and tools from paracontrolled calculus. Our argument uses that the solution to the linear equation is a log\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\log $$\\end{document}–correlated field, yielding a double exponential growth bound on the solution. Notably, our method does not rely on any explicit knowledge of the invariant measure to the SPDE, hence the perturbation ζ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ \\zeta $$\\end{document} is not restricted to the Cameron–Martin space of the noise, and the initial condition may be anticipative. Finally, we introduce a notion of weak solution that leads to well-posedness for all initial data u0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ u_{0}$$\\end{document} in L2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$ L^{2} $$\\end{document}, the critical space of initial conditions.

Effects of posture on heart rate variability in non-frail and prefrail individuals: a cross-sectional study

BackgroundFrailty is an aging-related syndrome leading to high mortality in older adults. Without effective assessment and prevention of frailty, the incidence of frailty and relevant adverse outcomes will increase by 2050 as worldwide populations age. Although evidence suggested heart rate variability (HRV) is a potential measure of frailty, the role of HRV in frailty assessment remains unclear because of controversial findings. This study examined the effects of posture on HRV parameters in non-frail and prefrail individuals to understand the role of HRV in assessing frailty.MethodsForty-six participants aged ≥ 50 years were recruited between April and August 2022. Frailty was defined using Fried’s criteria. HRV was measured in standing, sitting, and lying postures, respectively, using a Polar Watch, and analyzed using Kubios HRV Standard 3.5.0 (Kubios). The five most commonly used parameters were examined, including standard deviations of all normal-to-normal intervals (SDNN), root mean square of the successive differences (RMSSD), low frequency (LF), high frequency (HF), and LF/HF. Independent t-tests and Mann–Whitney tests were used for inter-group comparisons. Friedman tests were used for intra-group comparisons across postures.ResultsThe non-frail group showed significant differences in HRV parameters across postures (all p < 0.05), whereas the prefrail group did not demonstrate any difference (all p > 0.05). The differences in the non-frail group included higher RMSSD and HF in the lying posture compared to those in the standing posture (29.54 vs 21.99 p = 0.003, 210.34 vs 96.34 p = 0.001, respectively), and higher LF and LF/HF in the sitting posture compared to those in the lying posture (248.40 vs 136.29 P = 0.024, 1.26 vs 0.77 p = 0.011, respectively).ConclusionsThe effects of posture on HRV were blunted in the prefrail group, which suggests an impaired cardiac autonomic functioning. Measuring the effects of posture on HRV parameters may contribute to frailty assessment. However, further evidence from larger cohorts and including additional HRV parameters is needed.

Optimal decay rate and convergence of the incompressible viscous resistive MHD system

In this work, we investigate the optimal Lp(p≥2) time decay rate of global solutions to the incompressible viscous resistive MHD system with degeneration, and study its convergence to the incompressible viscous ideal MHD system as the resistivity ε goes to zero. The analysis is based on the high-low frequency decomposition and the uniform energy estimate of the system with respect to ε.

Changes in autonomic function and cerebral and somatic oxygenation with arterial flow pulsatility for children requiring veno-arterial extracorporeal membrane oxygenation

BackgroundVeno-arterial extracorporeal membrane oxygenation (VA-ECMO) carries variability in arterial flow pulsatility (AFP). Research questionWhat changes in cerebral and somatic oxygenation, hemodynamics, and autonomic function are associated with AFP during VA-ECMO? MethodsThis is a prospective study of children on VA-ECMO undergoing neuromonitoring. AFP was quantified by arterial blood pressure pulse amplitude and subcategorized: no pulsatility (<1 mmHg), minimal pulsatility (1 to <5 mmHg), moderate pulsatility (5 to <15 mmHg) and high pulsatility (≥15 mmHg). CVPR was assessed using the cerebral oximetry index (COx). Cerebral and somatic oxygenation was assessed using cerebral regional oximetry (rSO2) or peripheral oxygen saturation (SpO2). Autonomic function was assessed using baroreflex sensitivity (BRs), low-frequency high-frequency (LF/HF) ratio and standard deviation of heart rate R–R intervals (HRsd). Differences were assessed across AFP categories using linear mixed effects models with Tukey pairwise comparisons. Univariate logistic regression was used to explore risk of AFP with brain injuries. ResultsAmong fifty-three children, comparisons of moderate to high pulsatility were associated with reductions in rSO2 (p < 0.001), SpO 2 (p = 0.005), LF/HF ratio (p = 0.028) and an increase in HRsd (p < 0.001). Reductions in BRs were observed across comparisons of none to minimal (P < 0.001) and minimal to moderate pulsatility (p = 0.004). Comparisons of no to low pulsatility were associated with reductions in BRs (p < 0.001) and ABP (p < 0.001) with increases in SpO2 (p < 0.001) and HR (p < 0.001). Arterial ischemic stroke was associated with higher pulsatility (p = 0.0384). ConclusionDuring VA-ECMO support, changes toward high AFP are associated with autonomic dysregulation and compromised cerebral and somatic tissue oxygenation.

Effects of different extreme cold exposure on heart rate variability

Frequent extreme cold events in recent years have brought serious threats to outdoor workers and rescuers. Changes in ambient temperature are associated with altered cardiac autonomic function. The study aims to investigate heart rate variability (HRV) and its relationship to other physiological parameters under extreme cold exposures. Twelve males underwent a 30-min preconditioning phase in a neutral environment followed by a 30-min cold exposure (−5, −10, −15, and −20 °C). Time-domain indexes(meanRR, SDNN, RMSSD, and pNN50), frequency domain indexes [Log(HF), Log(LF), and low frequency/high frequency (LF/HF)], parasympathetic nervous system (PNS), and sympathetic nervous system (SNS) were analysed. Results showed all HRV indexes of four cold exposures were significant. The decrease in temperature was accompanied by progressive PNS activation with SNS retraction. SDNN was the most sensitive HRV index and had good linear relationships with blood pressure, pulse, and hand temperature. The results are significant for formulating safety protection strategies for workers in extremely cold environments. Practitioner Summary: This study investigated heart rate variability (HRV) in 12 males during a 30-min cold exposure (−5, −10, −15, and −20 °C). Results showed all HRV indexes of four cold exposures were significant. The decrease in temperature was accompanied by progressive PNS activation with SNS retraction. SDNN was the most sensitive HRV index and had good linear relationships with blood pressure, pulse, and hand temperature.

Coexisting Firing Patterns in an Improved Memristive Hindmarsh-Rose Neuron Model with Multi-Frequency Alternating Current Injection.

With the development of memristor theory, the application of memristor in the field of the nervous system has achieved remarkable results and has bright development prospects. Flux-controlled memristor can be used to describe the magnetic induction effect of the neuron. Based on the Hindmarsh-Rose (HR) neuron model, a new HR neuron model is proposed by introducing a flux-controlled memristor and a multi-frequency excitation with high-low frequency current superimposed. Various firing patterns under single and multiple stimuli are investigated. The model can exhibit different coexisting firing patterns. In addition, when the memristor coupling strength changes, the multiple stability of the model is eliminated, which is a rare phenomenon. Moreover, an analog circuit is built to verify the numerical simulation results.

Improvement of inverse dispersion technique for ground roll attenuation in sedimentary environment

Ground roll, often characterized as high energy, low velocity, low frequency and dispersion, which always dominates a large part of shot records and damages the desired reflections. The attenuation of ground roll is important for high data resolution and signal to noise ratio (S/N) in seismic processing. Conventional frequency-wave number (F-K) filter is effective in eliminating linear noise, but they do not deal well with appearance linear noise, like dispersive fan-shape ground roll. In the F-K domain, the components of ground roll and the desired reflection always overlap, which leads to destruction of the low-frequency components during the F-K filtering process. A novel inverse dispersion method is introduced to overcome this disadvantage. The proposed method transforms dispersive ground roll towards non-dispersive, high velocity linear noise. The time delay caused by dispersion is calculated and compensated by using an inverse dispersion operator. Then the ground roll is separated from the desired reflections and can be easily subtracted by the F-K filter. The conventional f-k filter can efficiently attenuate the ground roll without affecting the desired data, thus improve the resolution and S/N of seismic data. Model test and real data application demonstrate the feasibility and efficiency of the proposed method in ground roll attenuation.