Cardiac autonomic control in the obstructive sleep apnea

Introduction: The sympathetic activation is considered to be the main mechanism involved in the development of cardiovascular diseases in obstructive sleep apnea (OSA). The heart rate variability (HRV) analysis represents a non-invasive tool allowing the study of the autonomic nervous system. The impairment of HRV parameters in OSA has been documented. However, only a few studies tackled the dynamics of the autonomic nervous system during sleep in patients having OSA.Aims: To analyze the HRVover sleep stages and across sleep periods in order to clarify the impact of OSA on cardiac autonomic modulation. The second objective is to examine the nocturnal HRV of OSA patients to find out which HRV parameter is the best to reflect the symptoms severity.Methods: The study was retrospective. We have included 30 patients undergoing overnight polysomnography. Subjects were categorized into two groups according to apneahypopnea index (AHI): mild-to-moderate OSAS group (AHI: 5-30) and severe OSAS group (AHI>30). The HRV measures for participants with low apneahypopnea indices were compared to those of patients with high rates of apneahypopnea across the sleep period and sleep stages.Results: HRV measures during sleep stages for the group with low rates of apneahypopnea have indicated a parasympathetic activation during non-rapid eye movement (NREM) sleep. However, no significant difference has been observed in the high AHI group except for the mean of RR intervals (mean RR). The parasympathetic activity tended to increase across the night but without a statistical difference. After control of age and body mass index, the most significant correlation found was for the mean RR (p =0.0001, r = -0.248).Conclusion: OSA affects sympathovagal modulation during sleep, and this impact has been correlated to the severity of the disease. The mean RR seemed to be a better index allowing the sympathovagal balance appreciation during the night in OSA.Keywords: autonomic nervous system; sleep apnea; heart rate; sleep; circadia

The influence of nano-additives in strengthening mechanical performance of 3D printed multi-binder geopolymer composites

The weak mechanical properties the 3D printed parts can limit the competence of this technology when compared to conventionally cast-in-mold cementitious composites structures. However, experimental results in this study showed that the incorporation of nano additives could improve the mechanical property of printed structures. Six geopolymeric mixtures were designed and tested for their flow-ability, shape stability, buildability and mechanical performance. Different dosage of nano graphite platelets (NGPs) ranging from 0.1% to 1%, by the weight of geopolymer, were incorporated to the best performing geopolymer. The 3D printed geopolymer with 1% of NGPs increased the flexural strength by 89% and 46% compared to the same 3D printed and casted geopolymer without any NGPs, respectively. The same increase for compressive strength was 28% and 12%. Moreover, the geopolymer mix containing 1% of NGPs demonstrated the best shape retention and buildability

In middle-aged and old obese patients, training intervention reduces leptin level: A meta-analysis

BACKGROUND: Leptin is one of the major adipokines in obesity that indicates the severity of fat accumulation. It is also an important etiological factor of consequent cardiometabolic and autoimmune disorders. Aging has been demonstrated to aggravate obesity and to induce leptin resistance and hyperleptinemia. Hyperleptinemia, on the other hand, may promote the development of age-related abnormalities. While major weight loss has been demonstrated to ameliorate hyperleptinemia, obese people show a poor tendency to achieve lasting success in this field. The question arises whether training intervention per se is able to reduce the level of this adipokine. OBJECTIVES: We aimed to review the literature on the effects of training intervention on peripheral leptin level in obesity during aging, in order to evaluate the independent efficacy of this method. In the studies that were included in our analysis, changes of adiponectin levels (when present) were also evaluated. DATA SOURCES: 3481 records were identified through searching of PubMed, Embase and Cochrane Library Database. Altogether 19 articles were suitable for analyses. STUDY ELIGIBILITY CRITERIA: Empirical research papers were eligible provided that they reported data of middle-aged or older (above 45 years of age) overweight or obese (body mass index above 25) individuals and included physical training intervention or at least fitness status of groups together with corresponding blood leptin values. STATISTICAL METHODS: We used random effect models in each of the meta-analyses calculating with the DerSimonian and Laird weighting methods. I-squared indicator and Q test were performed to assess heterogeneity. To assess publication bias Egger's test was applied. In case of significant publication bias, the Duval and Tweedie's trim and fill algorithm was used. RESULTS: Training intervention leads to a decrease in leptin level of middle-aged or older, overweight or obese male and female groups, even without major weight loss, indicated by unchanged serum adiponectin levels. Resistance training appears to be more efficient in reducing blood leptin level than aerobic training alone. CONCLUSIONS: Physical training, especially resistance training successfully reduces hyperleptinemia even without diet or major weight loss

Prototype Design and Experimental Evaluation of Autonomous Collaborative Communication System for Emerging Maritime Use Cases

Automated systems have been seamlessly integrated into several industries as part of their industrial automation processes. Employing automated systems, such as autonomous vehicles, allows industries to increase productivity, benefit from a wide range of technologies and capabilities, and improve workplace safety. So far, most of the existing systems consider utilizing one type of autonomous vehicle. In this work, we propose a collaboration of different types of unmanned vehicles in maritime offshore scenarios. Providing high capacity, extended coverage, and better quality of services, autonomous collaborative systems can enable emerging maritime use cases, such as remote monitoring and navigation assistance. Motivated by these potential benefits, we propose the deployment of an Unmanned Surface Vehicle (USV) and an Unmanned Aerial Vehicle (UAV) in an autonomous collaborative communication system. Specifically, we design high-speed, directional communication links between a terrestrial control station and the two unmanned vehicles. Using measurement and simulation results, we evaluate the performance of the designed links in different communication scenarios and we show the benefits of employing multiple autonomous vehicles in the proposed communication system

3D printed lightweight concrete containing surface pretreated coal gangue

Eco-friendly concrete becomes research hotspots since concrete production emits 8–10% of the total anthropogenic CO2 emissions worldwide. Industry solid waste modification exhibits great potentials on mitigating aggregates depletion and carbon emissions. Coal gangue aggregate (CGA) coated by silica fume manually (CGACM) and in a desiccator (CGACD) are utilised to optimize the 3D printing concrete. Specimens were printed by a 3D printing robotic arm with a 25 mm-diameter nozzle. The compressive strength of CGACM and CGACD increases by 49% and 44% than non-activated series. For splitting tensile strength, the figures are 43% and 36%. The density of activation series decreases over 16% compared with standard sand. However, both surface pretreated methods make negative effects on structure compactness. From the SEM, SiO2 particles filles defects of aggregates, resulting in a denser internal structure and promoting secondary hydration reaction. However, excessive SiO2 particles agglomerated on CGA leads to the lubricant film among particles. These results expand recycle methods for CG and promotes 3D printing technology application on mine

3D printed lightweight concrete containing surface pretreated coal gangue

Eco-friendly concrete becomes research hotspots since concrete production emits 8–10% of the total anthropogenic CO2 emissions worldwide. Industry solid waste modification exhibits great potentials on mitigating aggregates depletion and carbon emissions. Coal gangue aggregate (CGA) coated by silica fume manually (CGACM) and in a desiccator (CGACD) are utilised to optimize the 3D printing concrete. Specimens were printed by a 3D printing robotic arm with a 25 mm-diameter nozzle. The compressive strength of CGACM and CGACD increases by 49% and 44% than non-activated series. For splitting tensile strength, the figures are 43% and 36%. The density of activation series decreases over 16% compared with standard sand. However, both surface pretreated methods make negative effects on structure compactness. From the SEM, SiO2 particles filles defects of aggregates, resulting in a denser internal structure and promoting secondary hydration reaction. However, excessive SiO2 particles agglomerated on CGA leads to the lubricant film among particles. These results expand recycle methods for CG and promotes 3D printing technology application on mine