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This paper presents an optimal framework for demand response aggregators in wholesale electricity markets. Demand response aggregators provide customers with flexible contracts in the proposed model. These contracts allow for hourly load reductions through load curtailment, load shifting, onsite generation utilization, and energy storage systems. The study suggests the price-based self-scheduling model for demand response aggregators, which seeks to maximize the aggregator's payoff for participation in day-ahead energy markets. The proposed model is implemented on a sample demand response aggregator with uncertainty and without uncertainty. Three methods, box, polyhedral, and ellipsoidal, based on robust optimization, are proposed for uncertainty modeling in this work, and their effectiveness is compared with each other. The results show that if the uncertainty is modeled using the polyhedral method, the value of the objective function will deviate by only 22.72 % compared to the case without uncertainty. However, this deviation in box and ellipsoidal methods is 118.48 % and 49.20 %, respectively, which shows the superiority of the polyhedral method compared to the oval and box methods., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. None., (© 2024 The Authors.)

Objectives: Uncorrected severe mitral regurgitation (MR) due to posterior prolapse leads to left ventricular dilatation. At this stage, mitral valve repair becomes mandatory to avoid permanent myocardial injury. However, which technique among neochoardae implantation and leaflet resection provides the best results in this scenario remains unknown., Methods: We selected 332 patients with left ventricular dilatation and severe degenerative MR due to posterior leaflet (PL) prolapse who underwent neochoardae implantation (85 patients) or PL resection (247 patients) at our institution between 2008 and 2020. A propensity score matching analysis was carried on to decrease the differences at baseline., Results: Matching yielded 85 neochordae implantations and 85 PL resections. At 10 years, freedom from cardiac death and freedom from mitral valve reoperation were 92.6 ± 6.1% vs 97.8 ± 2.1% and 97.7 ± 2.2% vs 95 ± 3% in the neochordae group and in the PL resection group, respectively. The MR ≥2+ recurrence rate was 23.9 ± 10% in the neochordae group and 20.8 ± 5.8% in the PL resection group (P = 0.834) at 10 years. At the last follow-up, the neochordae group showed a higher reduction of left ventricular end-diastolic diameter (44 vs 48 mm; P = 0.001) and a better ejection fraction (60% vs 55%; P < 0.001) compared to PL resection group., Conclusions: In this subgroup of patients, both neochordae implantation and leaflet resection provide excellent durability of the repair in the long term. Neochordae implantation might have a better effect on dilated left ventricle., (© The Author(s) 2023. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.)

The aim of this retrospective study is to show medium-long-term results in terms of cardiac death and aortic events in patients undergoing reduction ascending aortoplasty between 1997 and 2009 in our hospital. The Fine and Grey model for competing risk analysis was performed for time to cardiac death, with non-cardiac death as the competing risk, and time to recurrence of both re-dilation (aortic diameter > 45 mm) and re-operation with overall death as the competing risk. Paired t-test was used to evaluate the change in aortic diameter from the post-operative values to follow-up. The population included 142 patients. The mean pre-operative aortic diameter and the diameter at follow-up were respectively 46.5 ± 5.11 mm vs. 41.4 ± 5.55 mm (p-value < 0.001). At a mean follow-up of 11.6 ± 4.15 years, 11 patients (7.7%) required re-operation on the ascending aorta. At 16 years, the CIF of aortic-related events was 29.4 ± 7.2%; the freedom from cardiac death was 89.2 ± 3.7%. Ten patients (7%) died from cardiac causes but no one was aortic-related. The Fine and Grey analysis did not identify any significant predictors. This procedure is safe but might be justified only in high-risk patients or in those with advanced age/short life expectancy.