Total Spectral Power Research Articles

The dark art of light curing in dentistry

ObjectiveThis study was designed to show that the commonly reported irradiance values that are quoted in most publications inadequately describe the light output from light curing units (LCUs). MethodsThe total spectral radiant power (mW) output from 12 contemporary LCUs was measured with a fiberoptic spectroradiometer and a calibrated integrating sphere. Five recordings were taken for each LCU and exposure mode. In addition, the irradiances (mW/cm²) delivered at 0-mm, 5-mm and 10-mm distances were recorded through a 6-mm diameter aperture and the radiant exposures (J/cm²) from the LCUs were calculated. Light beam profiles from the LCUs were recorded using a beam profiler, and the images were overlaid on a molar tooth to simulate a clinical setting. Data were analyzed using ANOVA followed by Tukey post-hoc test (α = 0.05). ResultsThe mean power outputs from the LCUs ranged from 380 to 2472 mW (p < 0.0001). The highest irradiance was recorded from the Cicada CV 215-G7 (3091 mW/cm² in its highest mode) and the lowest from the Radii Cal CX (731 mW/cm²). The emission spectra differed, even among the multi-peak and single-peak LCUs. Radiant exposures from the entire light tip ranged from 18.3 J/cm², Radii Cal CX, in its standard 25 s exposure mode to 3.9 J/cm² from the Monet Laser in a 3 s exposure setting. Half (50 %) of the measured irradiance values from the LCUs differed from the manufacturers' value by more than 10 %. There were significant differences in the impact of distance from the tip. The beam profiles visually highlighted the varying effects of distance from the LCU tip among different units. ConclusionThere were significant differences in the emission spectra, power outputs, tip diameters, irradiances, radiant exposures, and the effect distance from the light tips. These differences underline the importance of manufacturers and researchers correctly measuring and reporting the output from the LCU to ensure that research is reproducible and that patients receive acceptable dental restorations. Clinical SignificanceThis article alerts clinicians, researchers and journal editors that providing only the tip irradiance (radiant exitance) value from the LCU is no longer sufficient. Manufacturers and researchers should include information on the spectral radiant power, emission spectrum, tip diameters, and also the effect of distance on the irradiance and radiant exposure, beam profiles and tooth access information when describing an LCU.

Spectral Power Distribution of Heart Rate Variability in Contiguous Short-Term Intervals.

Heart rate variability (HRV) is determined by the variation of consecutive cardiac electrical excitations, usually from RR intervals of an EKG. The sequence of intervals is a time series that yields three HRV parameter categories: time domain, frequency domain, and nonlinear. Parameter estimates are based on widely different EKG sample times: short-term (~5-10 minutes), longer (24 hours), and ultra-short (<5 minutes). Five-minute intervals are useful to evaluate intervention effects that change HRV in a single session by comparing pre-to-post values. This approach relies on knowing the minimal detectible change (MDC) that indicates a real change in clinical and research studies. The specific aims of this pilot study were to (1) evaluate HRV power and its spectral distribution among contiguous five-minute intervals, (2) compare the power distribution in a five-minute interval with a full 45-minute assessment, and (3) provide data to aid estimation of the MDC between pre- and post-interventions during a single session. Methods: Twelve self-reported healthy young adults participated after signing an approved consent. Participation required subjects who had no history of cardiovascular disease or were taking vasoactive substances. Persons with diabetes were not eligible. While subjects were supine, EKG leads were placed, and EKG was recorded for 45 minutes at 1000 samples/sec. The 45 minutes were divided into nine five-minute contiguous intervals, and the spectral density in each was determined. Total power and spectral percentages within each interval were assessed in the very low (VLF, 0.003-0.04 Hz), low (LF, 0.04-0.15 Hz), and high (HF, 0.15-0.4 Hz) frequency bands. These were compared among intervals and to the full 45-minute sample. The MDC was determined by comparing powers in five-minute intervals separated by 10 minutes. The standard error of the measurement (SEME) for each pair was calculated from the square root of the mean square error (√MSE). MSE was based on a two-factor analysis of variance, and MDC was 2×√2×SEME. Differences in total power and spectral power distribution among intervals were not statistically significant. The total mean power±SD was 4561±1434 ms². The maximum difference in total power was 7.85%. The mean power for the VLF, LF, and HF bands wasrespectively1713±1736 ms², 1574±1072 ms², and 1257±1016 ms². The maximum percentage difference in spectral power across all intervals for VLF, LF, and HF wasrespectively3.75%, 8.5%, and 7.4%. The percentage of power in the VLF, LF, and HF bands wasrespectively37.9%, 36.1%, and 25.9%. The ratios of spectral to total power for VLF, LF, and HF bands were respectively 0.80±0.07, 1.20±0.11, and 1.22±0.10. MDC percentage values were 21.0±4.9% for the HF band, 25.7±1.4% for the LF band, and 30.4±5.5% for the VLF band. Results offer initial estimates of variations in HRV power in the VLF, LF, and HF bands in contiguous five-minute intervals and estimates of the minimum detectible "real" changes between intervals separated by 10 minutes. The pattern of variation and data are useful in experimental planning in which HRV spectral power changes are assessed subsequent to a short-duration intervention during a single session. MDC values (21.0% in the HF band to 30.4% in the VLF band) provide initial estimates useful for estimating the number of participants needed to evaluate the impact of an intervention on spectral components of HRV.

Decoding cardiac reinnervation from cardiac autonomic markers: A mathematical model approach

BackgroundAlthough cardiac autonomic markers are commonly used to assess cardiac reinnervation in heart transplant patients (HTx), their relationship to the degree of sympathetic and vagal cardiac reinnervation is not well understood yet. To study this relationship, we applied a mathematical model of the cardiovascular system and its autonomic control. MethodsBy simulating varying levels of sympathetic and vagal efferent sinoatrial reinnervation, we analyzed the induced changes in cardiac autonomic markers including resting heart rate (HR), bradycardic and tachycardic HR response to Valsalva Maneuver, root mean square of successive differences between normal heartbeats (RMSSD), low-frequency- (LF), high-frequency- (HF), and total spectral power. ResultsThe results suggest that for assessment of vagal cardiac reinnervation levels >20%, resting HR (ρ=0.99, p<0.05), RMSSD (ρ=0.97, p<0.05), and total spectral power (ρ=0.96, p<0.05) may be equally suitable as the commonly used measure of HF-power (ρ=0.97, p<0.05). To assess sympathetic reinnervation, our results suggest that the LF/HF-ratio (ρ=0.87, p<0.05) and tachycardic response to Valsalva maneuver (ρ=0.9, p<0.05) may be more suitable than the regularly used measure of LF-power (ρ=0.77, p<0.05). ConclusionsOur model reports, for the first time, mechanistic relationships between the cardiac autonomic markers and the level of efferent autonomic sinoatrial reinnervation. The results indicate differences in the suitability of these markers to assess vagal and sympathetic reinnervation. Although our analysis is purely conceptual yet, the developed mathematical model can help to gain important insights into the genesis of cardiac autonomic markers and their relationship to efferent sinoatrial reinnervation and, thus, provide indications for clinical study evaluation.

Postoperative pain relief quality after cesarean section using a stress monitor (Neon FSC system): prospective single-center randomized clinical comparative study

BACKGROUND: The objective assessment of pain levels during labor, postpartum period, and effectiveness of analgesic response remains difficult. We suppose that the dynamics of the activity of the sympathetic nervous system by measuring the galvanic skin response may become a promising method for solving this problem.&#x0D; OBJECTIVE: To evaluate the effectiveness of various multimodal analgesia regimens after cesarean section using the NeonFSC stress monitoring system.&#x0D; MATERIALS AND METHODS: A prospective single-center clinical comparative study was conducted to evaluate the effectiveness of various postoperative multimodal analgesia regimens in 48 postpartum women who underwent elective cesarean section under spinal anesthesia. For postoperative analgesia, group 1 (n=24) underwent a TAP block, and ketorolac and tramadol were prescribed, and group 2 (n=24) received only ketorolac and tramadol. Randomization was made using the envelope method. The visual analog scale (VAS) and NeonFSC system were used to assess the effectiveness of postoperative pain relief. The observation time was 19–22 h.&#x0D; RESULTS: The patients were comparable in age, gestational age, physical status, method of pain management and delivery. At baseline and during the 2-h postoperative period, the median and distribution of visual analogue scale pain scores did not show a statistically significant difference between groups. During the study period, the highest level of spectral power of skin conductance (SC) was recorded in group 2. Baseline skin conductance variability (SCV) values were comparable between groups (p 0.001). Lower SCV values were noted in patients of group 1, compared to group 2, at night (p=0.003 vs p 0.001). The median values of the level of total spectral power of skin conductivity (DASS) in patients of group 1 were 1.5–2 times lower, starting from the second hour until the end of observation.&#x0D; CONCLUSION: The NeonFSC system can be a component of an objective assessment of the effectiveness of analgesia after cesarean section.

Virtual neural network-guided optimization of non-invasive brain stimulation in Alzheimer's disease.

Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique with potential for counteracting disrupted brain network activity in Alzheimer's disease (AD) to improve cognition. However, the results of tDCS studies in AD have been variable due to different methodological choices such as electrode placement. To address this, a virtual brain network model of AD was used to explore tDCS optimization. We compared a large, representative set of virtual tDCS intervention setups, to identify the theoretically optimized tDCS electrode positions for restoring functional network features disrupted in AD. We simulated 20 tDCS setups using a computational dynamic network model of 78 neural masses coupled according to human structural topology. AD network damage was simulated using an activity-dependent degeneration algorithm. Current flow modeling was used to estimate tDCS-targeted cortical regions for different electrode positions, and excitability of the pyramidal neurons of the corresponding neural masses was modulated to simulate tDCS. Outcome measures were relative power spectral density (alpha bands, 8-10 Hz and 10-13 Hz), total spectral power, posterior alpha peak frequency, and connectivity measures phase lag index (PLI) and amplitude envelope correlation (AEC). Virtual tDCS performance varied, with optimized strategies improving all outcome measures, while others caused further deterioration. The best performing setup involved right parietal anodal stimulation, with a contralateral supraorbital cathode. A clear correlation between the network role of stimulated regions and tDCS success was not observed. This modeling-informed approach can guide and perhaps accelerate tDCS therapy development and enhance our understanding of tDCS effects. Follow-up studies will compare the general predictions to personalized virtual models and validate them with tDCS-magnetoencephalography (MEG) in a clinical AD patient cohort.

Влияние коморбидного метаболического синдрома на нарушения кардиореспираторной регуляции у больных нетяжелой внебольничной пневмонией

Community-acquired pneumonia (CAP) and metabolic syndrome (MS) are important independent medical and social problems. At the same time, the comorbid effect of MS on the course of CAP has not been sufficiently studied. The purpose — to evaluate the additional contribution of the metabolic syndrome (MS) to dysregulation of the cardiorespiratory system in patients with moderate severity community-acquired pneumonia (CAP). Material and methods. Four groups were examined: the first control group (CG) of 35 healthy individuals, the second control group CG + MS of 14 individuals with MS but without any acute disease; the group of 62 patients with CAP, and the group of 28 patients with CAP and comorbide MS (CAP+MS). To assess cardio-respiratory regulation, ECG and impedance pneumogram were synchronously recorded for 10 minutes. Time series of consecutive cardiointervals NN and respiratory intervals Ttot were formed from this recording. Heart rate variability (HRV) and respiratory rhythm variability (RRV) were evaluated by calculation of standard deviations (SDNN, TtotSD) and variation coefficients (CVNN, TtotCV). The spectral analysis of HRV was also performed with determination of the total spectral power Ptotal, spectral power in the intervals of 0.04–0.15 Hz (PLF) and 0.15–0.40 Hz (PHF). The data are presented as median and interquartile range Me (Q1; Q3). Results. In patients with CAP and comorbid MS, the most pronounced decrease in the variability of heart and respiratory rhythms was revealed, and it was more reliably characteristic of heart rate variability. The values of variability parameters in the CAP(1) and CAP + MS(1) groups were: SDNN — 31.7 (23.1; 43.3) and 15.6 (10.8; 20.0) ms, respectively, p &lt; 0.001, CVNN — 3.9 (2.7; 5.0) and 2.2 (1.7; 2.8) %, p &lt; 0.001, PLF 150.8 (73.6; 272.5) and 33.9 (15.3; 81.5) ms2, p &lt; 0.001, PHF — 167.0 (52.5; 468.7) and 22.7 (10.5; 64.4) ms2, p &lt; 0.001. The values of variability parameters in the CAP(2) and CAP + MS(2) groups were: SDNN — 40.7 (29.5; 62.6) and 22.4 (14.7; 33.9) ms, respectively, p &lt; 0.001, CVNN — 4.7 (3.3; 6.9) and 3.0 (2.1; 4.2)%, p &lt; 0.001, PLF 219.4 (119.6; 443.6) and 124.5 (30.4; 195.6) ms2, p = 0.001, PHF — 371.0 (93.4; 845.0) and 67.3 (27.8; 127.9) ms2, p &lt; 0.001. Conclusions. The presence of comorbid MS significantly aggravates functional dysregulation of the cardiovascular and respiratory systems in patients with moderate CAP.

Virtual brain model‐guided optimization of transcranial direct current stimulation in Alzheimer’s disease

AbstractBackgroundNon‐invasive brain stimulation techniques such as transcranial direct current stimulation (tDCS) can potentially counteract disrupted local and distributed brain network activity in Alzheimer’s disease (AD) with a beneficial effect on cognition. However, results of tDCS studies in AD up till now are inconsistent, probably partly due to different methodological choices such as electrode placement. We therefore explored tDCS optimization using a virtual brain network model of AD. Our aim was to compare a large, representative set of virtual tDCS intervention setups, to identify and potentially explain the optimal theoretical tDCS electrode positions for reducing or restoring functional network disruption.MethodWe simulated 20 tDCS setups in a computational macroscopic dynamic network model of 78 neural masses, coupled according to human structural topology. AD network damage was simulated using an activity‐dependent degeneration algorithm, which produces typical gradual oscillatory slowing and loss of connectivity. Current flow modeling was used to estimate tDCS‐targeted cortical regions for different electrode positions, and excitability of the pyramidal neurons of the corresponding neural masses was modulated to simulate tDCS. Outcome measures were relative power spectral density in the lower (8‐10 Hz) and upper (8‐13 Hz) alpha bands, total spectral power, posterior alpha peak frequency, and connectivity measures phase lag index (PLI) and amplitude envelope correlation (AEC).ResultThe performance of different tDCS strategies varied considerably, with best setups temporarily improving all spectral and connectivity outcome measures, while other setups had little to no effect, or even caused network deterioration. The best performing setup involved right parietal anodal stimulation, with a contralateral supraorbital cathode. A clear correlation between the network role of a region (e.g. hub) and its involvement in successful tDCS was not observed.ConclusionModeling tDCS produces specific, falsifiable predictions on how to counter disrupted brain dynamics in AD. In follow‐up studies, our general predictions will be compared to those of personalized virtual models, and then validated with tDCS‐magnetoencephalography (MEG) in a clinical AD patient cohort. This modeling‐informed approach can guide and perhaps accelerate tDCS therapy development, as well as enhance our understanding of tDCS effects.

189 Role of Total Spectral Power in Prediction of Neurological Outcome After Cardiac Arrest

189 Role of Total Spectral Power in Prediction of Neurological Outcome After Cardiac Arrest

Coping und vegetative Reaktivität bei Aderhautmelanomen

Summary Background We aimed to assess coping and vegetative reactivity in uveal melanoma (UM) patients compared to controls with benign nevi of the uvea. Material and methods In total, 20 patients with recently diagnosed uveal melanoma were recruited and matched for age and gender to 20 controls with benign nevi of the uvea. Heart rate variability (HRV) and blood pressure variability (BPV) were monitored throughout an initial period of rest (POR1), a mental stress test (DT), and another period of rest (POR2). Coping strategies were assessed for both groups using a stress-coping questionnaire. Results The LF/HF ratio (low-/high-frequency component of total spectral power) of HRV showed decreasing values in the UM group and increasing values in controls throughout the measurement sequence (p = 0.025). Diastolic BPV revealed declining values of the low-frequency component in normalized units (LFnu) between POR1 and DT in UM patients compared to rising values between POR1 and DT in controls (p = 0.006). There were no intergroup differences in coping strategies (p &gt; 0.05). Conclusions Coping mechanisms are unaltered in patients with uveal melanoma compared to controls, but vegetative reactivity may show a different pattern once patients are diagnosed.

Cardiac autonomic control in Rett syndrome: Insights from heart rate variability analysis.

Rett syndrome (RTT) is a rare and severe neurological disorder mainly affecting females, usually linked to methyl-CpG-binding protein 2 (MECP2) gene mutations. Manifestations of RTT typically include loss of purposeful hand skills, gait and motor abnormalities, loss of spoken language, stereotypic hand movements, epilepsy, and autonomic dysfunction. Patients with RTT have a higher incidence of sudden death than the general population. Literature data indicate an uncoupling between measures of breathing and heart rate control that could offer insight into the mechanisms that lead to greater vulnerability to sudden death. Understanding the neural mechanisms of autonomic dysfunction and its correlation with sudden death is essential for patient care. Experimental evidence for increased sympathetic or reduced vagal modulation to the heart has spurred efforts to develop quantitative markers of cardiac autonomic profile. Heart rate variability (HRV) has emerged as a valuable non-invasive test to estimate the modulation of sympathetic and parasympathetic branches of the autonomic nervous system (ANS) to the heart. This review aims to provide an overview of the current knowledge on autonomic dysfunction and, in particular, to assess whether HRV parameters can help unravel patterns of cardiac autonomic dysregulation in patients with RTT. Literature data show reduced global HRV (total spectral power and R-R mean) and a shifted sympatho-vagal balance toward sympathetic predominance and vagal withdrawal in patients with RTT compared to controls. In addition, correlations between HRV and genotype and phenotype features or neurochemical changes were investigated. The data reported in this review suggest an important impairment in sympatho-vagal balance, supporting possible future research scenarios, targeting ANS.

Effect of Objective Daytime Sleepiness on Heart Rate Variability in Patients With Obstructive Sleep Apnea

Excessive daytime sleepiness (EDS) is associated with cardiovascular events in patients with obstructive sleep apnea (OSA). Our study explored the correlation between objective daytime sleepiness assessed with daytime multiple sleep latency tests (MSLT) and heart rate variability (HRV) in OSA patients. The results may provide insight into possible mechanisms underlying increased risk of cardiovascular events in patients with OSA. A retrospective analysis was conducted with the data of 139 patients with OSA and 35 patients with primary snoring. All subjects underwent polysomnography (PSG) and MSLT at West China Hospital between January 2019 and May 2022. We used mean sleep latency (MSL) to measure the severity of EDS and to categorize OSA patients into three groups, severe EDS, light EDS, and non-EDS, with MSL of less than 5 minutes, 5 to 10 minutes, and greater than 10 minutes as the respective defining criteria for classification. A comparison of sleep structure, clinical characteristics, and HRV parameters was performed in order to evaluate the difference between OSA subgroups with varying levels of objective EDS and the primary snoring group. In addition, we also analyzed the correlation between MSL and HRV parameters. Severe EDS patients had higher values of standard deviation of all N-N intervals (SDNN), total spectral power (TOT), and low-frequency power (LF) as compared to non-EDS patients, which was indicative of sympathetic stimulation ( P<0.05). Additionally, high-frequency power (HF) was also higher in severe EDS patients, which indicated decreased parasympathetic drive. A significantly positive correlation was found between MSL and the values of SDNN, TOT, LF, and HF in OSA patients. OSA patients with objective EDS have elevated sympathetic drive and decreased parasympathetic drive. A positive correlation was found between this change in neural activity and the shortening of MSL.

Anti-Apoptotic Effects of AMPA Receptor Antagonist Perampanel in Early Brain Injury After Subarachnoid Hemorrhage in Mice.

This study was aimed to investigate if acute neuronal apoptosis is induced by activation of AMPA (α-amino-3-hydroxy-5-methyl-4-isoxazole propionate) receptors (AMPARs) and inhibited by a clinically available selective AMPAR antagonist and antiepileptic drug perampanel (PER) in subarachnoid hemorrhage (SAH), and if the mechanisms include upregulation of an inflammation-related matricellular protein periostin. Sham-operated and endovascular perforation SAH mice randomly received an administration of 3mg/kg PER or the vehicle intraperitoneally. Post-SAH neurological impairments and increased caspase-dependent neuronal apoptosis were associated with activation of AMPAR subunits GluA1 and GluA2, and upregulation of periostin and proinflammatory cytokines interleukins-1β and -6, all of which were suppressed by PER. PER also inhibited post-SAH convulsion-unrelated increases in the total spectral power on video electroencephalogram (EEG) monitoring. Intracerebroventricularly injected recombinant periostin blocked PER's anti-apoptotic effects on neurons. An intracerebroventricular injection of a selective agonist for GluA1 and GluA2 aggravated neurological impairment, neuronal apoptosis as well as periostin upregulation, but did not increase the EEG total spectral power after SAH. A higher dosage (10mg/kg) of PER had even more anti-apoptotic effects compared with 3mg/kg PER. Thus, this study first showed that AMPAR activation causes post-SAH neuronal apoptosis at least partly via periostin upregulation. A clinically available AMPAR antagonist PER appears to be neuroprotective against post-SAH early brain injury through the anti-inflammatory and anti-apoptotic effects, independent of the antiepileptic action, and deserves further study.

Wearable Spectroradiometer for Dosimetry.

Available wearable dosimeters suffer from spectral mismatch during the measurement of broadband UV and visible radiation in environments that receive radiation from multiple sources emitting differing spectra. We observed this type of multi-spectra environment in all five Washington State cannabis farms visited during a field study investigating worker exposure to ultraviolet radiation in 2018. Spectroradiometers do not suffer from spectral mismatch in these environments, however, an extensive literature review conducted at the time of writing did not identify any spectroradiometers that were directly deployable as wearable dosimetry devices. To close this research gap, we developed a microcontroller system and platform that allows for researchers to mount and deploy the Ocean Insight Flame-S Spectroradiometer as a wearable device for measurement of UV and visible wavelengths (300 to 700 nm). The platform validation consisted of comparing measurements taken under platform control with measurements taken with the spectrometer controlled by a personal computer running the software provided by the spectroradiometer manufacturer. Three Mann-Whitney U-Tests (two-tailed, 95% CI), one for each intensity condition, compared the central tendency between the total spectral power (TSP), the integral of a spectrum measurement, measured under both control schemas. An additional analysis of per pixel agreement and overall platform stability was performed. The three Mann-Whitney tests returned no significant difference between the set of TSPs for each filter condition. These results suggest that the spectroradiometer takes measurements of equivalent accuracy under both control schemas, and can be deployed as a wearable device for the measurement of wavelength resolved UV and visible radiation.

Features of Spectral Estimates of the Photoplethysmographic Waveform Variability in Patients with Aortic Stenosis

Introduction — A well-known method for assessing the autonomic status of patients in clinical practice is the use of spectral estimates of finger's photoplethysmographic waveform variability (PPGV). However, these estimates have not been studied in patients with aortic stenosis. Therefore, this study aimed to identify in the PPGV spectrum the markers of autonomic dysfunction specific for patients with aortic stenosis. Methods — The study included 34 patients with aortic stenosis at the age of 54 (43, 67) years and 30 healthy subjects at the age of 34 (31, 36) years (data presented as median with lower and upper quartiles). The following spectral estimates of PPGV were evaluated: LF% (low-frequency band, 0.04–0.15 Hz, in the percentage of total spectral power, 0–0.4 Hz), HF% (high-frequency band, 0.15–0.4 Hz, in the percentage of total spectral power, 0–0.4 Hz), and LF/HF ratio. Results — The study revealed the statistically significant (p&lt;0.05) differences in HF% and LF% values in patients with aortic valve disease compared with healthy people. LF% was increased by 2-4 times in group of patients with aortic stenosis, while HF% was increased by 1.2-7 times. The difference between the groups at LF/HF ratio was statistically insignificant. Conclusion — Patients with aortic stenosis are characterized by higher LF% and HF% values, relative to healthy people of comparable age.

Synchronization between music dynamics and heart rhythm is modulated by the musician's emotional involvement: A single case study.

In this study we evaluated heart rate variability (HRV) changes in a pianist, playing in a laboratory, to investigate whether HRV changes are guided by music temporal features or by technical difficulty and/or subjective factors (e.g., experienced effort). The pianist was equipped with a wearable telemetry device for ECG recording during the execution of 4 classical and 5 jazz pieces. From ECG we derived the RR intervals series (tachogram), and, for each piece, analyzed HRV in the time (RR, RMSSD, Stress Index) and frequency domains (Total spectral power) and performed non-linear analysis (Multiscale Entropy). We also studied the correlation (Pearson) between the time course of music volume envelope and tachogram. Results showed a general reduction of parasympathetic and an increase of sympathetic activity, with the greatest changes during the classical pieces execution, the pianist appraised as more demanding than the jazz ones. The most marked changes occurred during the most technically/emotionally demanding piece, and correlation analysis revealed a negative association between music volume envelope time course and tachogram only for this piece, suggesting a modulation of the limbic system on the synchronization between heart rhythm and music temporal features. Classical music was also associated with the increase of entropy (1st scale) with respect to rest, indicating its effectiveness in driving flexible, healthy, heart dynamics. In conclusion, HRV seems modulated not only by the music temporal features, but also by the pianist’s emotional involvement, which is greatly influenced, in a non-trivial manner, by the technical demands and musician expertise.

Alterations in Baroreflex Sensitivity and Blood Pressure Variability Following Sport-Related Concussion.

Current methods to diagnose concussions are subjective and difficult to confirm. A variety of physiological biomarkers have been reported, but with conflicting results. This study assessed heart rate variability (HRV), spontaneous baroreflex sensitivity (BRS), and systolic blood pressure variability (BPV) in concussed athletes. The assessment consisted of a 5-min seated rest followed by a 5-min (0.1 Hz) controlled breathing protocol. Thirty participants completed baseline assessments. The protocol was repeated during the post-injury acute phase (days one to five). Total (p = 0.02) and low-frequency (p = 0.009) BPV spectral power were significantly decreased during the acute phase of concussion. BRS down-sequence (p = 0.036) and up-sequence (p = 0.05) were significantly increased in the acute phase of concussion, with a trend towards an increased BRS pooled (p = 0.06). Significant decreases in HRV were also found. Acute concussion resulted in altered BRS and BPV dynamics compared to baseline. These findings highlight objective physiological parameters that could aid concussion diagnosis and return-to-play protocols.

Lightweight and Robust Chatter Detection Algorithms for Milling

Most machining processes suffer from self-excited chatter vibrations that destroy the work surface and affect machine tool’s health. Therefore, accurate and timely detection of chatter vibrations is critical for productivity and longevity of the manufacturing equipment. This paper presents two different chatter detection algorithms for milling process by monitoring power spectrum of the vibration signal measured on the machine. Firstly, a real-time suitable computationally efficient approach is presented, which computes total spectral power of the vibration signal using time-domain variance operator and forced vibration power using moving Fourier transform. Power spectrum of chatter vibration is then evaluated by deducting the forced vibration component from the total signal power. The second method is based on Principal Component Analysis (PCA), which extracts the dominant harmonics of the measured vibration signal. Forced and chatter vibration harmonics are then clustered and labeled to evaluate the forced and chatter vibration powers based on their eigenvectors and eigenvalue magnitudes. For both methods, the power ratio (PR) is used to detect chatter. Once PR exceeds 0.5, chatter starts to dominate whole process, and it is detected. Both algorithms are experimentally tested in machining flexible workpieces. Results show that although both methods perform well on detecting chatter timely, computationally efficient algorithm gives false alarms for flexible workpiece while PCA based algorithm provides more robust chatter detection.

Relationship Between Cardiac Autonomic Markers and Degree of Cardiac Reinnervation in Heart Transplant Patients: Insights from a Mathematical Model

<h3>Purpose</h3> Cardiac sympathovagal balance is often assessed using autonomic markers derived from cardiac rhythm, however, their relationship to the degree of reinnervation after heart transplantation is still not fully understood. This study aimed to investigate the influence of various levels of vagal and sympathetic cardiac reinnervation on the respective autonomic cardiac markers using a mathematical model of the human cardiovascular system. <h3>Methods</h3> The model integrates chronotropic and inotropic effects of arterial baroreflex and pulmonary stretch reflex, known as main contributors to heart rate variability. The markers of interest included resting heart rate, bradycardic and tachycardic heart rate response to Valsalva maneuver, root mean square error of normalized RR-intervals (RMSDD), high-frequency (HF) power, low-frequency (LF) power, and total power of the heart rate variability spectrum. To analyze how well different levels of sympathetic or vagal cardiac reinnervation can be discriminated through cardiac autonomic markers, five groups of increasing reinnervation levels were formed. The strength of the relationship between the level of cardiac reinnervation was quantified by Spearman's correlation coefficients. <h3>Results</h3> The results suggest that for assessment of vagal cardiac reinnervation levels <20%, resting heart rate (ρ=0.99, p<0.05), RMSDD (ρ=0.97, p<0.05), and total spectral power (ρ=0.89, p<0.05) may be equally suitable as the commonly used measure of HF-power (ρ=0.88, p<0.05). To assess sympathetic reinnervation, our results suggest that LF/HF-ratio (ρ=0.88, p<0.05) and tachycardic response to Valsalva maneuver (ρ=0.84, p<0.05) may be more suitable than LF-power (ρ=0.82, p<0.05). <h3>Conclusion</h3> Our model reports, for the first time, mechanistic relationships between cardiac autonomic markers and degrees of vagal/sympathetic reinnervation. The results suggest differences in the performance of cardiac autonomic markers to assess vagal and sympathetic reinnervation. Although our analysis is purely theoretical yet, the developed mathematical model can provide important insights into the genesis of autonomic cardiac markers and their relationship to cardiac reinnervation and provide indications for clinical study evaluation. This work is funded by the EU-Project NeuHeart (824071).

Возможности регионарной анестезии при радикальной цистэктомии у больных мышечно-инвазивным раком мочевого пузыря

На сегодняшний день регионарная анестезия при радикальной цистэктомии у пациентов с раком мочевого пузыря выполняется в качестве компонента общей анестезии в условиях искусственной вентиляции легких. Цель работы — оценить безопасность и преимущества выполнения радикальной цистэктомии на фоне комбинированной спинально-эпидуральной анестезии при сохраненном самостоятельном дыхании c последующей оценкой течения послеоперационного периода. Материалы и методы. С 2008 по 2012 г. 96 пациентам в возрасте 67,0 ± 6,5 года произведена радикальная цистэктомия с расширенной тазовой лимфаденэктомией и различными видами деривации мочи с использованием комбинированной спинально-эпидуральной анестезии. Послеоперационная анальгезия включала продленную инфузию наропина 0,2% — 6–8 мл/ч в комбинации с системным введением нестероидных противовоспалительных средств. Оценивали характеристики вариабельности сердечного ритма в частотной области. Результаты и выводы. Развитие спинального блока сопровождалось снижением общей спектральной мощности, преимущественно спектра активности симпатического отдела (LF) — вследствие симпатической блокады, менее выраженным угнетением парасимпатического отдела вегетативной нервной системы. Плотность спектра активности подкорковых нервных центров и процессов гуморальной регуляции (VLF) достоверно не изменялась до момента седации больного. Гемодинамика характеризовалась повышением сердечного индекса на 15,9 %, снижением индекса общего периферического сосудистого сопротивления на 23,2 %.Введение гипнотиков приводило к дальнейшему уменьшению спектральной мощности в диапазоне LF и достоверному подавлению в общей спектральной мощности спектра VLF. Эти изменения вегетативного гомеостаза сопровождались снижением артериального давления, сердечного индекса на фоне недостоверного повышения индекса общего периферического сосудистого сопротивления.Применение субгипнотических доз пропофола с целью достижения медикаментозного сна обеспечивало более стабильное состояние гемодинамики и вегетативного гомеостаза по сравнению с применением бензодиазепинов. Комбинированная спектрально-эпидуральная анестезия является методом выбора анестезиологического пособия при выполнении радикальной цистэктомии. Продленная послеоперационная эпидуральная анальгезия 0,2% наропином обеспечивает максимально раннюю активизацию пациентов, сопровождается ранним восстановлением моторики желудочно-кишечного тракта и пассажа, снижает риск развития респираторных и тромбоэмболических осложнений.

ЕЕГ-ознаки ризику розвитку симптомного інсульту в пацієнтів із множинними «німими» інфарктами мозку

У статті наведені дані дослідження ЕЕГ-корелятів порушення церебрального кровообігу та їх зв’язку з ризиком виникнення інсульту в пацієнтів із множинними «німими» інфарктами мозку (мНІМ). Аналіз біоелектричної активності мозку був проведений у 36 пацієнтів (середній вік 54,00 ± 3,22 року) із МРТ-ознаками поодинокого НІМ (пНІМ) та в 24 пацієнтів (середній вік 67,89 ± 1,84 року) із МРТ-ознаками мНІМ. Протягом року після ЕЕГ-дослідження в 4 пацієнтів із мНІМ стався симптомний інсульт. У пацієнтів із мНІМ числові показники ЕЕГ-корелятів порушення церебрального кровообігу значно відрізнялися від таких пацієнтів із пНІМ. Порівняно з пацієнтами з групи пНІМ для картини ЕЕГ пацієнтів із мНІМ було притаманне значне зниження спектральної потужності (за коефіцієнтом α/δ), щільності (14,87 ± 2,83 та 1,89 ± 0,49 мкВ2/Гц відповідно, р &lt; 0,001) та індексу (39,18 ± 2,96 та 11,65 ± 1,17 % відповідно, р &lt; 0,001) α-ритму на тлі зростання аналогічних показників δ-ритму. Загальна спектральна потужність ЕЕГ у пацієнтів групи мНІМ була в 2,3 раза нижчою, ніж у пацієнтів групи пНІМ (124,81 ± 18,24 та 285,03 ± 35,71 мкВ2 відповідно, р &lt; 0,001), коефіцієнт потужності α/δ — у 7 разів меншим (0,35 ± 0,05 та 2,49 ± 0,34 відповідно, р &lt; 0,001), а (δ + θ)/(α + β)-коефіцієнт — у 2,7 раза більшим (1,96 ± 0,26 та 0,71 ± 0,08 відповідно, р &lt; 0,001). Саме зниження загальної спектральної потужності ЕЕГ, α/δ-коефіцієнта та підвищення (δ + θ)/(α + β)-коефіцієнта є найбільш показовими та загрозливими ЕЕГ-ознаками з точки зору ризику симптомного інсульту в пацієнтів із мНІМ.