Adaptive Control in Swarm Robotic Systems

Inspired by the collective behavior observed in natural insects, swarm robotics is a new approach in designing control algorithms for a large group of robots performing a certain task. In such robotic systems, an individual robot with only limited capabilities in terms of sensing, computation, and communication can adapt its own behavior so that a desired collective behavior emerges from the local interactions among robots and between robots and the environment. Swarm robotics has been the focus of increased attention recently because of the beneficial features demonstrated in such systems, such as higher group efficiency, robustness against the failures of individual robots, flexibility to adapt to changes in the environment, and scalability over a wide range of group sizes. In this article we present an adaptive algorithm to regulate the behavior of an individual robot performing collective foraging tasks. Through the interactions between robots, a desired division of labor can be achieved at the group level. Robot groups also demonstrate the ability to improve energy efficiency and its potential robustness in different environments

Emergently Alteration of Procedural Strategy During Transcatheter Aortic Valve Replacement to Prevent Coronary Occlusion: A Case Report

BackgroundCoronary occlusion is an uncommon but fatal complication of transcatheter aortic valve replacement (TAVR) with a poor prognosis.Case PresentationA patient with symptomatic severe bicuspid aortic valve stenosis was admitted to a high-volume center specializing in transfemoral TAVR with self-expanding valves. No anatomical risk factors of coronary occlusion were identified on pre-procedural computed tomography analysis. The patient was scheduled for a transfemoral TAVR with a self-expanding valve. Balloon pre-dilatation prior to prosthesis implantation was routinely used for assessing the supra-annular structure and assessing the risk of coronary occlusion. Immediately after the tubular balloon inflation, fluoroscopy revealed that the right coronary artery was not visible, and the flow in the left coronary artery was reduced. The patient would be at high-risk of coronary occlusion if a long stent self-expanding valve was implanted. Therefore, our heart team decided to suspend the ongoing procedure. A transapical TAVR with a 23 mm J-valve was performed 3 days later. The prosthesis was deployed at a proper position without blocking the coronary ostia and the final fluoroscopy showed normal flow in bilateral coronary arteries with the same filling as preoperatively.DiscussionOur successful case highlights the importance of a comprehensive assessment of coronary risk and a thorough understanding of the TAVR procedure for the heart team. A short-stent prosthesis is feasible for patients at high risk of coronary occlusion. Most importantly TAVR should be called off even if the catheter has been introduced when an extremely high risk of coronary obstruction is identified during the procedure and no solution can be found

Novel hydrophobic associated polymer based nano-silica composite with core–shell structure for intelligent drilling fluid under ultra-high temperature and ultra-high pressure

Micro-nano-based drilling fluid has attracted a strong interest due to its attractive properties, and micro-nano composite materials have great potential for developing intelligent drilling fluid. In this study a novel hydrophobic associated polymer based nano-silica composite with core–shell structure was prepared and characterized by PSD, SEM, TEM and ESEM. The results showed that the composite, as a micro-nano drilling fluid additive, possessed excellent properties such as thermal stability, rheology, fluid loss and lubricity. Especially, it could plug the formation effectively and improve the pressure bearing capability of formation significantly

The influence of delayed treatment due to COVID-19 on patients with neovascular age-related macular degeneration and polypoidal choroidal vasculopathy

Purpose: To explore the impact of coronavirus disease 2019 (COVID-19) on the prognosis of patients with neovascular age-related macular degeneration (nAMD) and polypoidal choroidal vasculopathy (PCV), and share the experience in managing them during pandemics. Method: This is a retrospective study of nAMD and PCV patients treated at Peking Union Medical College Hospital from 31 December 2019 to 1 August 2020. Baseline demographic and clinical characteristics, best corrected visual acuity (BCVA), optical coherence tomography (OCT) features, duration of delayed treatment and number of anti-vascular endothelial growth factor (VEGF) injections were analyzed. Results: A total of 130 nAMD patients (155 eyes) and 76 PCV patients (89 eyes) were identified. Compared to the conditions before COVID-19, the BCVA of delayed cases decreased significantly, and the proportion of patients presenting with sub-macular scar was significantly greater in the delayed treatment group ( p  < 0.05). The BCVA of non-delayed cases remained stable, with the percentage of patients with disease activity sub-retinal fluid and hemorrhage at the fovea decreasing significantly ( p  < 0.05). The stable cases who did not require anti-VEGF treatment had significantly worse baseline and final BCVA, these patients were likely to be chronic and ‘burnt out’ cases with significantly worse anatomical structures ( p  < 0.05). Conclusions: The delayed cases due to the pandemic suffered compromised visual function and a higher rate of sub-macular scar formation, while the visual function of non-delayed cases remained stable with favorable anatomical outcomes, suggesting the importance of regular follow-up for nAMD and PCV patients. Besides, effective measures of hospitals during pandemics are crucial to provide timely treatment for chronic disease

Technical Success after Transcatheter Aortic Valve Replacement for Bicuspid versus Tricuspid Aortic Stenosis

Background: Comparative data of the Valve Academic Research Consortium (VARC-3)-defined technical success between bicuspid versus tricuspid aortic stenosis (AS) remain lacking. Aims: We sought to compare the technical success and other clinical outcomes between patients with bicuspid and tricuspid AS receiving transcatheter aortic valve replacement. Methods: A registration-based analysis was performed for 402 patients (211 and 191 cases of bicuspid and tricuspid AS, respectively). The primary outcome was VARC-3-defined technical success. Additional analysis was performed to assess outcomes for up to one year between the two groups. Results: Bicuspid AS patients tended to be younger (74 years vs. 77 years; p p = 0.003). Bicuspid AS patients showed a lower prevalence of hypertension and peripheral vascular diseases. Technical failure was encountered in 17.7% of these patients, driven primarily by the high incidence of second valve implantation. The technical success rates were comparable between the bicuspid and tricuspid AS groups (82.5% vs. 82.2%, p = 0.944). Chronic kidney disease (CKD) and larger sinotubular junctional diameter (STJ) were identified as predictors of technical failure, whereas CKD, impaired left ventricular ejection fraction (LVEF), along with larger STJ, were predictors of cardiac technical failure. Technical failure was associated with an increased risk of all-cause mortality at 30 days and 1 year, as evidenced by the Cox multivariable analysis. Conclusions: No significant differences were observed in the technical success rates and most clinical outcomes between the bicuspid and tricuspid AS groups. Technical failure conferred an increased risk for both 30-day and 1-year all-cause mortalities

Trimethylamine N-Oxide Levels Are Associated with Severe Aortic Stenosis and Predict Long-Term Adverse Outcome

Objective: Trimethylamine N-oxide (TMAO), a pathological microbial metabolite, is demonstrated to be related to cardiovascular diseases. This study was (1) to investigate the association between TMAO and aortic stenosis and (2) to determine the prognostic value of TMAO for predicting mortality after transcatheter aortic valve replacement (TAVR). Methods: 299 consecutive patients (77 (72–81) years, 58.2% male, Society of Thoracic Surgeons (STS) score 5.8 (4.9–9.3)) with severe aortic stenosis and 711 patients (59 (52–66) years, 51.9% male) without aortic stenosis were included in this retrospective study. A total of 126 pairs of patients were assembled by Propensity Score Matching. The primary outcome was all-cause mortality using survival analyses stratified by TMAO quartiles. Results: Patients with severe aortic stenosis had higher TMAO levels (3.18 (1.77–6.91) μmol/L vs. 1.78 (1.14–2.68) μmol/L, p p = 0.028) and higher late cumulative mortality (34.2% vs. 19.1%, log-rank p = 0.004). In Cox regression multivariate analysis, higher TMAO level remained an independent predictor (hazard ratio 1.788; 95% CI 1.064–3.005, p = 0.028) of all-cause mortality after adjusting for STS score, N-terminal pro b-type natriuretic peptide, and maximum velocity. Conclusions: The TMAO level was higher in aortic stenosis patients. Elevated TMAO was associated with poor adverse outcome after TAVR

Cerebral Ischemic Lesions after Transcatheter Aortic Valve Implantation in Patients with Non-Calcific Aortic Stenosis

Evidence for transcatheter aortic valve implantation (TAVI) is scarce among patients with non-calcific aortic stenosis, and it is not known whether aortic valve calcification is associated with new cerebral ischemic lesions (CILs) that are detected by diffusion-weighted magnetic resonance imaging. So, our study enrolled 328 patients who underwent transfemoral TAVI using a self-expanding valve between December 2016 and June 2021 from the TORCH registry (NCT02803294). A total of 34 patients were finally confirmed as non-calcific AS and the remaining 294 patients were included in the calcific AS group. Incidence of new CILs (70.6% vs. 85.7%, p = 0.022), number of lesions (2.0 vs. 3.0, p = 0.010), and lesions volume (105.0 mm3 vs. 200.0 mm3, p = 0.047) was significantly lower in the non-calcific AS group. However, the maximum and average lesion volumes were comparable between two groups. Non-calcific AS was associated with lower risk for developing new CILs by univariate logistic regression analysis [Odds ratio (OR): 0.040, 95% confident interval (CI): 0.18&ndash;0.90, p = 0.026] and multivariate analysis (OR: 0.031, 95% CI: 0.13&ndash;0.76, p = 0.010). In summary, non-calcific AS patients had a lower risk of developing new cerebral ischemic infarction after TAVI compared to calcific AS patients. However, new ischemic lesions were still found in over 70% of patients