Decrease In Total Power Research Articles

Flow mechanism and back gap windage loss of a sCO2 radial inflow turbine with impeller scallops

The Internal flow mechanisms and windage loss in impeller back gap of a supercritical carbon dioxide (sCO2) radial inflow turbine with scallops are comprehensively investigated in this paper. The study emphasizes the effects of scallop depth and leakage outlet pressure. The results indicate that scallop structures lead to a degradation in overall turbine performance. Under design conditions, a turbine with a scallop depth ratio of 0.5 exhibits a 3.7% reduction in efficiency and a 3.4% decrease in total power compared to no scallop configuration. Furthermore, as scallop depth increases, the skin friction coefficient decreases in the disk gap while it increases for the seal in the impeller back gap. Increasing leakage outlet pressure reduces the leakage flow rate and skin friction coefficient. Fitted models for skin friction coefficient are proposed respectively. The conclusions providing valuable insights for designing and optimizing sCO2 radial inflow turbines with scallops.

Telemetric long-term assessment of autonomic function in experimental heart failure

Despite medical advances in the treatment of heart failure (HF), mortality remains high. It has been shown that alterations of the autonomic-nervous-system (ANS) are associated with HF progression and increased mortality. Preclinical models are required to evaluate the effectiveness of novel treatments modulating the autonomic imbalance. However, there are neither standard models nor diagnostic methods established to measure sympathetic and parasympathetic outflow continuously. Digital technologies might be a reliable tool for continuous assessment of autonomic function within experimental HF models.Telemetry devices and pacemakers were implanted in beagle dogs (n = 6). HF was induced by ventricular pacing. Cardiac hemodynamics, plasma catecholamines and parameter describing the ANS ((heart rate variability (HRV), deceleration capacity (DC), and baroreflex sensitivity (BRS)) were continuously measured at baseline, during HF conditions and during recovery phase.The pacing regime led to the expected depression in cardiac hemodynamics. Telemetric assessment of the ANS function showed a significant decrease in Total power, DC, and Heart rate recovery, whereas BRS was not significantly affected. In contrast, plasma catecholamines, revealing sympathetic activity, showed only a significant increase in the recovery phase.A precise diagnostic of the ANS in the context of HF is becoming increasingly important in experimental models. Up to now, these models have shown many limitations. Here we present the continuous assessment of the autonomic function in the progression of HF. We could demonstrate the advantage of highly resolved ANS measurement by HR and BP derived parameters due to early detection of an autonomic imbalance in the progression of HF.

Optimization Model and Application for Agricultural Machinery Systems Based on Timeliness Losses of Multiple Operations

Present agricultural practices confront issues such as mismatches between tractors and implements, imprecise machinery allocation, and excessive machinery investment. Optimization of agricultural machinery systems was a potent remedy for these concerns. To address inaccuracies in calculating objective functions and the incompleteness of constraints in existing models for agricultural machinery system optimization, a comprehensive mixed integer nonlinear programming (MINP) model for agricultural machinery system optimization was established. The model introduced timeliness loss costs for multiple key operations across various crops into the objective function, and constraints were enhanced by including operation sequence constraints and boundary constraints on initiation and completion dates of those key operations. Taking corn and soybeans as examples, timeliness loss functions of sowing and harvesting operations were derived through experiments. Solving the MINP model by Lingo (V.14.0) software, improvements in total power, workload per unit power, and total operational costs were shown when comparing the optimized machinery system through the MINP model against current systems. When the model omitted considerations for timeliness loss functions and operation sequence constraints, issues arose including an increase in total operational costs and an inversion of operation sequence. The model’s application in devising machinery allocation plans for production units of various operational scales revealed a gradual decrease in total power and costs per unit area with expanding scale, approaching stability when scale exceeded 1600 hm2. This study enriches theory and methodology for optimizing agricultural machinery systems, provides theoretical and technological underpinnings for rational machinery acquisition, and promotes the high-quality progression of comprehensive agricultural mechanization.

Inflammation and decreased cardiovagal modulation are linked to stress and depression at 36th week of pregnancy in gestational diabetes mellitus

Stress and depression have been reported in gestational diabetes mellitus (GDM). Though inflammation and oxidative stress are associated with depression, there are no reports of link of cardiometabolic risks (CMR) to stress and depression in GDM. Normal pregnant women (control group, n = 164) and women with GDM (study group, n = 176) at 36th week of gestation were recruited for the study. Blood pressure (BP), body composition, heart rate variability (HRV), glycated hemoglobin (HbA1C), markers of insulin resistance, oxidative stress, inflammation and endothelial dysfunction, were assessed. Perceived stress score (PSS), quality of life (QoL) scale, Indian diabetic risk score (IDRS) and Edinburg postnatal depression score (EPDS) were assessed. Association of potential contributors to PSS and EDPS were assessed by correlation and regression analyses. There was significant increase in PSS, EPDS, IDRS scores, HbA1C, malondialdehyde (MDA) (oxidative stress marker) and high-sensitive C-reactive protein and interleukin-6 (inflammatory markers), and significant decrease in total power (TP) of HRV (marker of cardiovagal modulation), QoL and nitric oxide (endothelial dysfunction marker) in study group compared to control group. Though many cardiometabolic risk parameters were correlated with PSS and EPDS, the significant independent association was observed for TP, HbA1C, MDA and interleukin-6. However, interleukin-6 had maximum contribution to PSS (β = 0.550, p < 0.001) and EPDS (β = 0.393, p < 0.001) as demonstrated by multiple regression analysis. Inflammation, oxidative stress, glycation status and decreased cardiovagal modulation are associated with stress and depression at 36th week of gestation in GDM.

Impact of Cancer and 12 Weeks of Chemotherapy on the Balance of the Autonomic Nervous System in Cancer Patients

Cancer and its treatment itself (especially chemotherapy) is associated with number of negative effects on the human body. These include mainly cardiac toxicity, peripheral neuropathy, bone loss, depression, anxiety, nausea, pain, cognitive changes, fatigue, fitness reduction and more. Fatigue is one of the most common negative effects, often persists long after treatment and is described as insurmountable and is associated with lower parasympathetic activity. The autonomic nervous system (ANS) is the main homeostatic regulatory system of the body, it regulates involuntary physiological processes. We believe that this part of the peripheral nervous system can be negatively affected by cancer and chemotherapy, which can have a negative impact on all the processes that control this system. Most drugs used in oncology lead to chemotherapy-induced peripheral neuropathy and are expected to have an influence on the autonomic nervous system. Activity and balance of the autonomic nervous system depend on a range of dynamically changing and quantitatively different conditions such as age, stress, physical activity, sleep, illness, fatigue and more. Methods: To evaluate ANS activity, spectral analysis of heart rate variability (HRV) was assessed. During treatment, 19 oncological patients with prescribed adjuvant chemotherapy measured HRV 3 times a week using a chest strap with a HRV monitor mySASY and mySASY software. Parasympathetic activity (PA), sympathetic activity (S), total score (TS) and total power (TP) were selected as indicators of ANS activity. The patients were women aged 50.38 ± 10,29 with BMI 25,72 ± 4,16. The mean values for the first 14 days of treatment and then for 14 days after 12 weeks of treatment were compared. Data normality was verified by Kolmogorov-Smirnov test (K-S) and static significance was calculated by t-test. All statistical tests were performed at a significance level of 5%. Results: There was a significant decrease in values for three parameters. The PA decreased from 3,80 ± 1,56 to 3,14 ± 1,67 (p = .03), TP decreased from 3,65 ± 1,87 to 2,82 ± 2,08 (p = .04), TS decreased from 3,40 ± 1,67 to 2,67 ± 1,73 (p = .01). Sympathetic activity was somewhat but not significantly higher, increased from 6,74 ± 1,22 to 6,80 ± 1,44 (p = .83). Conclusion: During the 12 weeks of treatment with adjuvant chemotherapy, there was a significant reduction in parasympathetic activity, total score, and total power. A decrease in PA is usually associated with lower regenerative abilities of the organism, a decrease in TP is associated with a decrease in the activity of the entire ANS. TS evaluates the total power and balance of both ANS branches. The higher the values, the more the body is regenerated and ready for further stress and response to stress.

THE TOTAL POWER OF THE HEART AS A PROMISING PARAMETER FOR ASSESSING THE FUNCTIONAL STATE OF THE PATIENT DURING AN OBJECTIVE STRUCTURED CLINICAL EXAMINATION: GNOSEOLOGY, CLINICAL SIGNIFICANCE

This study reveals the clinical value of the parameter of the total power of the heart in assessing the functional state of the patient. The article is devoted to the expediency of using the method of short recording of heart rhythm variability in Objective Structured Clinical Examination.&#x0D; The purpose of the study was to investigate the total power in patients with noncommunicable diseases based on the results of recording a short record of heart rhythm variability as a promising parameter for assessing the functional state during an Objective Structured Clinical Examination.&#x0D; Materials and methods. An analysis of the total power was carried out based on the data of the short record of heart rhythm variability in 229 people. 43 persons were comorbid patients with coronary heart disease, 111 persons were young functionally healthy non-athletes, 75 persons were professional young athletes.&#x0D; Results. The diagnostic value of the parameter of the total power of the heart was proved. 23% and 21% of patients with non-stationary heart rhythm in the background and orthostatic modes were found. A decrease in total power of various degrees was established in patients, in contrast to control groups.&#x0D; Conclusions. 1) The total power of cardiac activity is a promising, diagnostically valuable parameter for assessing the patient's functional state during an Objective Structured Clinical Examination. 2) Now all the conditions have been formed for the widespread introduction of the method of short recording of heart rhythm variability in the practice of internal medicine doctors.3) The method of short recording of heart rhythm variability can be recommended for use in the clinical examination of patients as a device for improving the individual work of a doctor in order to determine the individual characteristics of the functioning of the heart, determine the risk of cardiac death, and early preclinical diagnosis of emerging pathology.

Effect of Lesion of Central Amygdala on Heart Rate Variability in Albino Wistar Rats

Background and Aim: Heart rate variability (HRV) reflects the pre-frontal cortex (PFC) and amygdalar connections. HRV is also influenced by emotions, which is controlled by limbic system. Thus, amygdala-limbic connection is suggested to be the major integrator of HRV and the alterations in the regulation lead to cardiometabolic risks. The present study was conducted to assess the central amygdala in the heart rate variability in albino Wistar rats. Methods: A total of 8 albino Wistar rats were taken for the study. Stereotaxic procedure was performed and lesion was made into the central amygdalar nuclei bilaterally. HRV was assessed before and after lesion of central amygdala. Results: Following lesion of central amygdala, there was decrease in total power (TP), high frequency (HF), and other time domain indices of HRV, while there was increase in low frequency (LF) and LF-HF ratio. Conclusion: Lesion of central amygdala decreased TP indicating the crucial role of central amygdala in the control of HRV. The control of central amygdala on sympathovagal balance is profound.

Heart Rate Variability in Hyperthyroidism: A Systematic Review and Meta-Analysis.

Objective: Cardiovascular effects of thyroid hormones may be measured through heart rate variability (HRV). We sought to determine the impact of hyperthyroidism on HRV. Design: A systematic review and meta-analysis on the impact of hyperthyroidism on HRV. Methods: PubMed, Cochrane, Embase and Google Scholar were searched until 20 August 2021 for articles reporting HRV parameters in untreated hyperthyroidism and healthy controls. Random-effects meta-analysis was stratified by degree of hyperthyroidism for each HRV parameter: RR intervals (or Normal-to-Normal intervals—NN), SDNN (standard deviation of RR intervals), RMSSD (square root of the mean difference of successive RR intervals), pNN50 (percentage of RR intervals with >50 ms of variation), total power (TP), LFnu (low-frequency normalized unit) and HFnu (high-frequency), VLF (very low-frequency), and LF/HF ratio. Results: We included 22 studies with 10,811 patients: 1002 with hyperthyroidism and 9809 healthy controls. There was a decrease in RR (effect size = −4.63, 95% CI −5.7 to −3.56), SDNN (−6.07, −7.42 to −4.71), RMSSD (−1.52, −2.18 to −0.87), pNN50 (−1.36, −1.83 to −0.88), TP (−2.05, −2.87 to −1.24), HFnu (−3.51, −4.76 to −2.26), and VLF power (−2.65, −3.74 to −1.55), and an increase in LFnu (2.66, 1.55 to 3.78) and LF/HF ratio (1.75, 1.02 to 2.48) (p < 0.01). Most parameters had ES that was twice as high in overt compared to subclinical hyperthyroidism. Increased peripheral thyroid hormones and decreased TSH levels were associated with lower RR intervals. Conclusions: Hyperthyroidism is associated with a decreased HRV, which may be explained by the deleterious effect of thyroid hormones and TSH. The increased sympathetic and decreased parasympathetic activity may have clinical implications.

Функциональное состояние центральной и вегетативной регуляции у врачей экстренной помощи молодого возраста в северном регионе

The purpose of this research was to analyse the functional state of the central and autonomic nervous systems in young emergency physicians working in the northern region. Materials and methods. We examined 33 emergency physicians of a multidisciplinary hospital in Khanty-Mansi Autonomous Okrug – Yugra aged 25 to 43 years (19 men and 14 women). The functional state of the central nervous system (CNS) was assessed using the method of simple visual-motor reaction (SVMR) and criteria developed by T.D. Loskutova – system’s functional level (SFL), reaction stability (RS) and level of functional abilities (LFA) – as well as attention stability, working memory and Whipple’s accuracy index. The state of autonomic regulation was evaluated according to the dynamics of heart rate variability (HRV) at rest and during active orthostatic test (AOT). Results. We found that male emergency physicians have higher rates of psychomotor reactions, SFL, RS, and LFA than their female colleagues. SVMR showed pathological reactions of the CNS in subjects of both sexes. The body’s adaptive capabilities due to autonomic regulation were preserved in most emergency physicians. However, a pathological response to AOT was found in both men and women. The pathological basis for impaired autonomic regulation and the development of maladaptive reactions in the subjects was a deterioration of the current functional state of the body, excessive activation of the sympathoadrenal system and a decrease in parasympathetic regulation. Responses to AOT in male emergency physicians were accompanied by a decrease in the total power (TP) of the HRV spectrum by 24.7 %, and an increase in low frequency (LF) to high frequency (HF) ratio by a factor of 2.6; while in female doctors, by a decrease in TP by 11.5 % and an increase in LF/HF ratio by a factor of 1.7. The median of 30/15 coefficient was 1.48 for men and 1.45 for women. Thus, in the course of professional selection of doctors to provide emergency care under unfavourable climatic conditions of the North, it is advisable to conduct a comprehensive examination of the functional state of the central nervous system and autonomic regulation to identify a risk group with impaired adaptation mechanisms. For citation: Popova M.A., Scherbakova A.E., Karimov R.R. Functional State of the Central and Autonomic Regulation in Young Emergency Physicians in the Northern Region. Journal of Medical and Biological Research, 2021, vol. 9, no. 4, pp. 374–384. DOI: 10.37482/2687-1491-Z075

Disturbances of Autonomic Regulation of Cardiovascular System at Different Working Regimes with Night Shifts

Aim To study temporal and spectral characteristics of heart rhythm variability (HRV) in night shift workers.Materials and methods Along with traditional risk factors, conditions of labor contribute to development of cardiovascular morbidity, including night shift work, which can be associated with disorders of the autonomic regulation detected by analysis of HRV. This study included 100 healthy men. 74 of them were engaged in shift work, including 53 men with rotating shift work, 21 men with fixed night shifts, and 26 men with day-time work. HRV was analyzed by data of 5-min electrocardiogram recording (background recording and orthostatic test).Results Night-shift workers had decreases in total power of regulation (ТР, SDNN) and in the parasympathetic branch (HF, pNN50). Rotating night-shift workers displayed significant decreases in SDNN and pNN50 and pronounced changes in the VLF / LF / HF ratio in the orthostatic test.Conclusion In work with night shifts, the type of autonomic regulation differs from the "standard" functioning of the autonomic nervous system (ANS). This study showed different effects of night work regimens on HRV indexes. With the rotating shift work, the ANS dysregulation was more profound and was evident by a significant decrease in the ANS total tone and parasympathetic activity (SDNN, pNN50) compared to night shifts with fixed working hours. The excessive weakening of the parasympathetic component in the passive orthostatic test can be considered as an early marker for ANS maladaptation.

Optimal Power and Efficiency of Multi-Stage Endoreversible Quantum Carnot Heat Engine with Harmonic Oscillators at the Classical Limit.

At the classical limit, a multi-stage, endoreversible Carnot cycle model of quantum heat engine (QHE) working with non-interacting harmonic oscillators systems is established in this paper. A simplified combined cycle, where all sub-cycles work at maximum power output (MPO), is analyzed under two types of combined form: constraint of cycle period or constraint of interstage heat current. The expressions of power and the corresponding efficiency under two types of combined constrains are derived. A general combined cycle, in which all sub-cycles run at arbitrary state, is further investigated under two types of combined constrains. By introducing the Lagrangian function, the MPO of two-stage combined QHE with different intermediate temperatures is obtained, utilizing numerical calculation. The results show that, for the simplified combined cycle, the total power decreases and heat exchange from hot reservoir increases under two types of constrains with the increasing number (N) of stages. The efficiency of the combined cycle decreases under the constraints of the cycle period, but keeps constant under the constraint of interstage heat current. For the general combined cycle, three operating modes, including single heat engine mode at low “temperature” (SM1), double heat engine mode (DM) and single heat engine mode at high “temperature” (SM2), appear as intermediate temperature varies. For the constraint of cycle period, the MPO is obtained at the junction of DM mode and SM2 mode. For the constraint of interstage heat current, the MPO keeps constant during DM mode, in which the two sub-cycles compensate each other.

Impact of neuromuscular function on pain during walking in individuals with knee osteoarthritis

Purpose: The neuromuscular mechanisms for pain-related mobility deficits in patients with symptomatic knee osteoarthritis (OA) are not well understood. Alterations in muscle activity including prolonged activation and greater co-activation of muscles surrounding the knee have been reported and vary with radiographic severity; however, their relevance for symptom onset, severity and mobility impairment is not clear. The first study aim was to quantify differences in muscle activation patterns for individuals who do or do not experience increased pain with walking. We hypothesized that those who experience pain with walking would have greater activation intensity and total activation power as compared to those who do not. The second aim was to quantify the impact of increased pain on muscle activity during a bout of walking. We hypothesized with an increase in pain there would be a decreased mean activation intensity of medial muscles and total activation power. Methods: Twenty-two individuals with knee OA performed a 20-minute treadmill walk at a preferred pace: 11 reported an increase in self-reported pain (IP) in the affected limb, and 11 who reported no change in pain (NC)(Table1). Electromyography (EMG) was collected at 2000Hz on 8 lower extremity muscles of the most affected limb (Rectus Femoris(RF), Tibialis Anterior(TA), and the medial and lateral Vastii(VM, VL), gastronemii(MG,LG), and hamstrings(MH,LH). Nine walking strides from minute 2 and minute 20 of the treadmill walk were resolved in time and frequency space simultaneously using 20 non-linearly scaled wavelets ranging from 0-250Hz. EMG for each muscle was normalized to mean activation intensity in minute 2 and time normalized to 100% of the gait cycle. To test for group and time effects in EMG intensity a curve analysis with statistical parametric mapping (SPM) was used to apply 2-way repeated measures ANOVA over the gait cycle. EMG power (sum of intensity over time) for high (cfs: 108.7-246.1) and low (cfs: 12.2-93.0) frequency bands, and total power were also calculated. Group and time effect were assessed with a 2-way repeated measures ANOVA. Post-hoc tests were applied where appropriate.Tabled 1Table 1 DemographicsAge (yrs)BMI(kg/m2)Gait Speed (m/s)ΔvNRSKOOS painNC62.8 (6.3)25.8 (3.1)1.16 (0.6)-0.09 (0.3)69.9 (12.6)IP67.9 (3.3)25.4 (4.2)1.39 (0.4)2.27 (1.4)71.45 (11.6) Open table in a new tab Results: No significant group effects for EMG intensity were found. Main effects of time were found with a decrease of EMG intensity in the LG from 79-84% (p<0.001), and MG from 69-73% of the gait cycle (p<0.001)(Fig.1). A group*time interaction effect was found for the TA in late-stance (p<0.001; 35-43% gait cycle). Post-hoc testing found greater TA EMG intensity from 32-47% (p=0.006) of the gait cycle for NC compared to IP at minute 2 only as NC had a decrease pre to post for 10-56% gait cycle (p<0.001). Significant main effect of time was found with ∼12% decrease in total power in LG (p=0.04) and a group*time interaction in the TA (p=0.009). Post-hoc testing found at the end of the walk IP had greater TA EMG power compared to NC (p=0.04) as the NC decreased total EMG power in the walk by ∼20%, while IP had no change. No other significant differences were found for total or lower frequency power. For high frequency EMG power, main effects of time were found with decreases in LG, MH, LH, RF, TA, and VL (p<0.05). Group*time interactions were found for the TA (p=0.028), VL (p=0.029), VM (p=0.046). IP had lower EMG power compared to NC in the VL (p=0.02) and VM (p=0.002) at minute 2, and VM (p=0.04) at minute 20 (Fig.2). NC decreased EMG power in the VL (p=0.003) and VM(p=0.021) with walking. No significant post hoc differences were found for the TA. Conclusions: The study findings suggest there are differences at baseline in the EMG power within higher frequency bands of the Vastii muscles for knee OA patients who do vs do not experience pain with a bout of walking. Those who reported an increase in pain during the walk had 40% lower EMG power in the Vastii muscles at the walk start compared to those who reported no change in pain. Greater TA activation intensity at baseline was also found for those with no pain change compared to pain increase suggesting there may be differences in stride length. In response to the treadmill walk, those who had no change in pain had a reduction in high frequency EMG power in the Vastii muscles. Yet, at the end of the walk, high frequency power in the VM remained lower in those with a pain increase as compared to those without. Several possible physiologic changes may alter the higher frequency EMG including a modulation of motor unit recruitment, firing rate, and/or slowing of conduction velocity and should be further explored to understand the neuromuscular mechanisms for pain-related mobility deficits.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Behavioral and physiological assessment of liquid nitrogen cryoablation to prevent horn development in dairy calves

The aim of this series of studies was to evaluate the behavioral and physiological responses (experiment 1), the electroencephalographic response (experiment 2), and the efficacy (experiment 3) of cryoablation to determine if it could provide an alternative to cautery disbudding (DB) for calves. In experiment 1, at approximately 3 d of age, 58 female Friesian dairy calves were allocated to one of five treatments: (1) control handling (CON, n = 11), (2) cautery DB (n = 11), DB plus local anesthetic (n = 12), DB using cryoablation (CR, n = 12), and CR plus local anesthetic (n = 12). Behavioral and physiological (complete blood cell counts and plasma cortisol concentrations) measures were recorded for up to 4 and 72 h post-treatment, respectively. In experiment 2, at approximately 4 d of age, the electroencephalographic response was recorded in 20 male and female Friesian-cross dairy calves disbudded using cautery (DB, n = 10) or cryoablation (CR, n = 10). In experiment 3, at approximately 4 d of age, 274 female Friesian-cross dairy calves were enrolled from two dairy farms and each calf had one of two treatments randomly assigned to each horn bud: cryoablation applied for 10 s (CR-10, n = 274 buds) or 15 s (CR-15, n = 274 buds). At approximately 6 months of age, calves were checked for scur or horn growth. In experiment 1, DB calves spent less (P < 0.05) time lying than DB plus local anesthetic, CR, and CR plus local anesthetic calves. At 3 h post-treatment, the total white blood cell counts and neutrophil:lymphocyte ratio were higher (P < 0.05) in CR than DB and CON calves. Plasma cortisol concentrations were greater (P < 0.05) 30 min after DB and CR compared with CON; however, concentrations did not differ between DB and CR calves. Cortisol concentrations were greater (P < 0.05) in CR calves 90 min post-treatment compared with all other treatments. In experiment 2, cryoablation elicited increases in median frequency and 95% spectral edge frequency and a decrease in total power, whereas cautery elicited an increase in 95% spectral edge frequency only. In experiment 3, cryoablation successfully prevented horn growth in only 19% and 33% of CR-10 and CR-15 calves, respectively. Spraying liquid nitrogen directly onto the horn bud region appeared to cause more acute pain than cautery DB and did not effectively prevent horn growth.

Abstract P331: Transition From Pre-Diabetes To Diabetes Is Associated With Worsening Of Cardiac Autonomic Neuropathy: Reversal By Anti-Diabetic Drugs

Cardiac autonomic neuropathy (CAN) occurs early in the course of diabetes leading to significant cardiovascular mortality and morbidity. Manifested as impaired heart rate variability (HRV) and baroreflex sensitivity (BRS), CAN represents an independent risk predictor of cardiac mortality. CAN development is linked to hyperglycemia; however, current understanding extends cardiovascular risk to pre-diabetic patients with slight glycemic changes. Here, we assessed the incidence and manifestation of CAN in a rat model of metabolic challenge prior to and after the development of diabetes. Rats were fed a hypercaloric (HC) diet (4.035 KCal/g vs. 3 KCal/g for control rats) composed of: weight (calories) 18.06 % fat (38.68%), 15.8% protein (15.66%), and 46.13% carbohydrates (45.73%). Stable fasting hyperglycemia developed by 16 weeks of feeding. The pre-diabetic stage was associated with signs of perivascular and epicardiac adipose inflammation (4- and 40- fold increase in IL-1β and TGF-β and 2-fold increase in NK-κB expression; and macrophage infiltration) and increased brainstem oxidative stress accompanied with impairment of HRV (total power decrease from 3098 ± 233 to 89 ± 88μs 2 ) and the parasympathetic arm of the baroreflex (slope decrease from -1.02 ± 0.12 to -0.34 ± 0.04). These abnormalities were reversed upon treatment with non-hypoglycemic doses of either metformin or pioglitazone or upon lowering the rat caloric intake. On the other hand, after progression to diabetes, the autonomic deficit progressed to the sympathetic arm of the baroreflex (Slope reduction from -0.35 ± 0.02 to -0.09 ± 0.03). The same hypoglycemic doses of metformin and pioglitazone failed to reverse the impaired HRV and BRS. Whereas, reduction of hyperglycemia to control levels by insulin was only capable of reversing the sympathetic impairment (BRS slope of -0.28 ± 0.04). Our present results outline a framework for sequential involvement of different detrimental mechanisms in the course of metabolic disease leading to differential impact on cardiac autonomic control. Furthermore, our findings emphasize the value of early intervention with antidiabetic drugs with potential protective pleiotropic effects.

Characteristic of a multistage reheating radial inflow in supercritical compressed air energy storage with variable operating parameters

In the present study, aerodynamic performance of a four-stage reheating radial inflow turbine, which is adopted in the 1.5 MW supercritical compressed air energy storage system, is analyzed by using the method of integral numerical calculation. Results illustrate that when the inlet total pressure of the first stage is decreased, the expansion ratio of the fourth stage decreases the most. System isentropic efficiency decreases about 1% when the inlet total pressure of the first stage is changed from 7 MPa to 3 MPa, and the fourth stage’s isentropic efficiency decreases about 7%. When the rotational speed is decreased, isentropic efficiency and total power decrease gradually and isentropic efficiency changes from 90.5% at 110% speed ratio to 71.1% at 60% speed ratio. Increasing reheating temperature results to the decrease of mass flow rate and isentropic efficiency and the increase of total power. Total power increases by about 105% when the reheating temperature is changed from 60 ℃ to 520 ℃. When the guide vane opening of the first stage is increased, the expansion ratio of the first stage shows different trends compared to other stages and mass flow rates, and total power are proportional to the guide vane opening. System isentropic efficiency decreases by about 4% when the guide vane opening is adjusted from 80% to 30%.

INFLUENCE OF THE TOTAL POWER OF THE HEART RATE VARIABILITY SPECTRUM ON THE SPECTRAL PARAMETERS DISTRIBUTION IN PATIENTS WITH ARTERIAL HYPERTENSION IN A PACED BREATHING TEST

To determine the effect of the total power (TP) of the heart rate variability (HRV) spectrum on the distribution of high, low and very low frequency waves, 40 patients with arterial hypertension (AH) at the age of 58 ± 9 years were divided into 5 groups according to the degree of TP decrease in the initial stage of the test: 1st – more than 3000 ms2; 2nd – 3000–2000 ms2; 3rd – 2000-1000 ms2; 4th – 1000–500 ms2; 5th – less than 500 ms2. To assess HRV parameters in each group, 3 stages of the paced breathing test with a double (light and sound) metronome were evaluated; the hardware and software complex «Cardiolab» («HAI-Medica») was used. The distribution of the parameters was estimated taking into account the median, 25 and 75 quartiles. To estimate the differences between the statistical samples, the nonparametric Mann-Whitney U-test was used, as well as the Craskell–Wallis criterion. Statistically significant differences were considered between the data at a value of p &lt; 0.05. It was found that the greater is the degree of TP reduction, the more significant is the autonomic imbalance, as well as the decrease in the influence of paced breathing on the regulation of the heart rhythm; at TP values below 1000 ms2 not only the parasympathetic component decrease is observed, but also the transition from sympathicotonia to the neurohumoral factors prevalence. In patients with arterial hypertension, there is a tendency of decrease in the total power of the HRV spectrum, thus reflecting the decreased functional capacity of heart rhythm regulation.The lower the degree of TP, the more significant is the disturbance of HRV regulation with a decrease in the parasympathetic component of the heart rate variability spectrum and the dominant influence of sympathetic and neurohumoral factors.The influence of the paced breathing on the heart rhythm regulation falls depending on the decrease in the total power of the HRV spectrum: at TP values below 1000 ms2 not only the parasympathetic component decrease is observed, but also the transition from sympathotonia to the neurohumoral factors prevalence.Decrease in TP can be considered as an indicator of aggravation of autonomic and neurohumoral regulation.Thepaced breathing test allows determine the basic level of cardiac activity regulation and dynamic disruptions in the distribution of HRV components in the metronomized breathing, as well as the possibilities for restoring the regulatory balance of heart rate variability, which is especially important in the examination of patients with arterial hypertension.

Power spectral analysis of cardiovascular autonomic functional modulation in response to acute psychological stress after induction of acupressure at GV20: An observational study

Background: Acupressure is a simple, non-invasive, painless method which can be complementary and alternative medicine treatment to reduce stress. Acupressure at GV-20 provides the relief of anxiety and acute stress. Aims and Objectives: Evaluate the effect of GV20 Acupressure on cardiac autonomic functional modulation using heart rate variability (HRV). Materials and Methods: This is a cross-sectional study to investigate the use of an acupressure in acute stress reduction in adults (n = 30). Mental arithmetic stress was administered before and after acupressure. Acupressure was given at GV20 for 5 min, and HRV was measured. The collected data were analyzed for frequency domain using nonparametric method of Fast Fourier Transform, using Ku-bios HRV analysis software. Results: All interventions were associated with the following changes, during stress after acupressure compared to stress before acupressure: Significant increase of total power (P ≤ 0.05), decrease in low frequency (LF), and increase in high frequency (HF) and decrease in LF/HF value. Changes during rest after acupressure and before acupressure are as follows: Decrease in total power, increase in LF, decrease in HF, and decrease in LF/HF but not significant (P ≥ 0.05). Conclusion: Thus, this study indicates that acupressure at GV20 was able to reduce stress in the subjects significantly. This positive finding suggests that acupressure may have a role in reducing acute psychological stress in young adults and help in improving performance.

Behavioural, brain and cardiac responses to hypobaric hypoxia in broiler chickens

A novel approach to pre-slaughter stunning of chickens has been developed in which birds are rendered unconscious by progressive hypobaric hypoxia. Termed Low Atmospheric Pressure Stunning (LAPS), this approach involves application of gradual decompression lasting 280s according to a prescribed curve. We examined responses to LAPS by recording behaviour, electroencephalogram (EEG) and electrocardiogram (ECG) in individual male chickens, and interpreted these with regard to the welfare impact of the process. We also examined the effect of two temperature adjusted pressure curves on these responses. Broiler chickens were exposed to LAPS in 30 triplets (16 and 14 triplets assigned to each pressure curve). In each triplet, one bird was instrumented for recording of EEG and ECG while the behaviour of all three birds was observed. Birds showed a consistent sequence of behaviours during LAPS (ataxia, loss of posture, clonic convulsions and motionless) which were observed in all birds. Leg paddling, tonic convulsions, slow wing flapping, mandibulation, head shaking, open bill breathing, deep inhalation, jumping and vocalisation were observed in a proportion of birds. Spectral analysis of EEG responses at 2s intervals throughout LAPS revealed progressive decreases in median frequency at the same time as corresponding progressive increases in total power, followed later by decreases in total power as all birds exhibited isoelectric EEG and died. There was a very pronounced increase in total power at 50–60s into the LAPS cycle, which corresponded to dominance of the signal by high amplitude slow waves, indicating loss of consciousness. Slow wave EEG was seen early in the LAPS process, before behavioural evidence of loss of consciousness such as ataxia and loss of posture, almost certainly due to the fact that it was completely dark in the LAPS chamber. ECG recordings showed a pronounced bradycardia (starting on average 49.6s into LAPS), often associated with arrhythmia, until around 60s into LAPS when heart rate levelled off. There was a good correlation between behavioural, EEG and cardiac measures in relation to loss of consciousness which collectively provide a loss of consciousness estimate of around 60s. There were some effects of temperature adjusted pressure curves on behavioural latencies and ECG responses, but in general responses were consistent and very similar to those reported in previous research on controlled atmosphere stunning with inert gases. The results suggest that the process is humane (slaughter without avoidable fear, anxiety, pain, suffering and distress). In particular, the maintenance of slow wave EEG patterns in the early part of LAPS (while birds are still conscious) is strongly suggestive that LAPS is non-aversive, since we would expect this to be interrupted by pain or discomfort.

Framingham risk score modifies the effect of PM10 on heart rate variability

Health conditions may greatly modify the association between particulate matter (PM) and heart rate variability (HRV), but whether the modification of PM effect by coronary artery disease (CAD) risk status depends on the PM levels remains unknown. We investigated the associations between personal exposures to PM with aerodynamic diameter of ≤10μm (PM10) and ≤2.5μm (PM2.5) and concurrent HRV, and whether the effect of PM on HRV was modified by Framingham risk score (FRS) in healthy subjects with different PM exposure levels. Personal exposures to PM10 and PM2.5 were measured for 24h in 152 volunteers of community residents who were free of cardiovascular disease in two cities (Zhuhai and Wuhan) that differ in air quality. Simultaneously, 24h HRV indices were obtained from 3-channel Holter monitor. FRS was calculated based on age, sex, lipid profiles, blood pressure, diabetes, and smoking status. Linear regression models were constructed after adjusting for potential confounders. We found significant decrease in total power (TP) and low power (LF) with increased PM10 concentrations (P for trend<0.05) in the high PM levels city (Wuhan) and total population, but not in the low PM levels city (Zhuhai). We also observed significant modification of FRS on PM10 effect in Wuhan. Interestingly, elevated PM10 was associated in a greater decreased HRV in the low FRS subgroup, but not in the high FRS subgroup. However, we did not find any significant main effects of PM2.5 or PM2.5–FRS interactions on HRV in city-specified or city-combined analyses. Overall, the findings indicate that individual coronary risk profiles may modulate the association between particulate air pollution and HRV in high PM exposure levels.

Utilizing heart rate variability: Midazolam prevents the sympathovagal imbalance caused by fentanyl/propofol induction

Context Heart rate variability (HRV) can monitor cardiac autonomic control. Sympathovagal imbalance is expected after fentanyl/propofol induction. Aim The aim of the study was to investigate the effects of intravenous midazolam on HRV and whether it prevents the sympathovagal imbalance caused by fentanyl/propofol induction. Settings and design This is a controlled, randomized, double-blinded study. Patients and methods The study included 50 patients undergoing knee arthroscopies under general anesthesia. Powers of low-frequency (LF: 0.04-0.15 Hz) and high-frequency (HF: 0.15-0.4 Hz) components of HRV, total power (TP), and LF/HF ratio were recorded using MemCalc software. Patients received midazolam 0.05 mg/kg (midazolam group) or an equivalent volume of normal saline (control group), followed by fentanyl 1 mcg/kg and then propofol 2 mg/kg intravenously. Statistical analysis The Mann-Whitney U-test and two-way repeated analysis of variance, followed by Bonferroni correction as a post-hoc test, were used to analyze the data. Results Midazolam induced significant decrease in TP and HF powers, with unchanged LF power and LF/HF ratio. Fentanyl induced significant decrease in TP and LF powers with unchanged HF power and LF/HF ratio in both groups. Propofol induced a significant decrease in TP, HF, and LF powers in both groups. Propofol decreased the LF/HF ratio significantly in the control group but not in the midazolam group. Conclusion Midazolam premedication induced significant decrease in TP and HF powers without changes in LF power or LF/HF ratio. When fentanyl and propofol were given, midazolam was capable of modulating the net effects of both drugs on the HRV by minimizing the decrease in LF power to keep the LF/HF ratio unchanged. This modulatory effect of midazolam works in favor of maintaining the sympathovagal balance.