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To enhance frequency and active power control performance, this research proposes a decentralized robust optimal tuning approach for power grid frequency regulation support using energy storage systems (ESSs) as the primary source of grid-forming (GFM) converters. The proposed approach employs the robust Kharitonov theory to find a family of stabilizing sets of a proportional-integral (PI)-based supplementary controller, which is used in the outer control layer of the GFM control system. A family of stabilizing parameter sets is found in the presence of system uncertainties and disturbances that are common in power grid operation. Then, using a developed Bayesian optimization algorithm, an optimal set of parameters is determined among the mentioned family member sets. The proposed sophisticated combination of a robust control theorem and an optimization algorithm provides a promising solution for the robust and optimal tuning of control system parameters in ESS-based GFM converters. The efficacy of the proposed method is demonstrated via simulation and laboratory real-time experiment results for a given detailed case study.

This paper presents a study on the robust tuning of damping coefficient, inertia, and conventional controller gains for a grid-forming converter connected to the main grid. The proposed method is evaluated using the Typhoon Hill system, which allows for comprehensive simulation and analysis. The Kharitonov theorem is utilized to achieve robustness in the face of deviations in line parameters. Unlike previous works, our approach systematically and graphically searches for a non-conservative Kharitonov region in the solution area of the controller coefficients. This region characterizes all stabilizing gain controllers that effectively stabilize an uncertain control structure. By selecting coefficients from the obtained non-conservative Kharitonov region, the synthesized controller effectively stabilizes the grid-forming converter. The results of this study highlight the efficacy of the Kharitonov theorem in achieving robust tuning of essential parameters for grid-forming converters, enhancing stability and performance in the presence of line parameter variations.

This paper deals with the frequency response modeling of interconnected microgrids. The frequency response model is used for frequency and tie-line power control analysis and synthesis. The proposed frequency response model is obtained using two different perspectives: (1) based on frequency sensitivity analysis, (2) based on the inertia concept. Besides, the dynamic of back-to-back converters and controllable active power sources are also included to obtain a generalized frequency response model with desirable performance. Indeed, it can be observed that in the first method, some circuit parameters can be neglected in the frequency response model. This finding is effective in providing a more simplified model. In the second method, the frequency response model has been presented as an innovative approach. In a way, we have selected the nature of distributed generations as an indicator of source classification in the model. This model is also enhanced by considering the inertia dynamics and controllable power source and has a better performance to show the network status. Since the microgrid frequency response model only covers the low-frequency dynamics, the fast dynamics of inner control loops as well as the modulation units and sensors are not considered. The proposed frequency response model can be used for frequency stability analysis studies as well as frequency and tie-line power control analysis and synthesis. Comprehensive simulation studies are carried out using the MATLAB simulation environment to compare and evaluate the developed models. Further, the proposed models are verified via PSCAD/EMTDC, considering two microgrids interconnected through back-to-back converters. The results showed that the proposed models are suitable and efficient for frequency response studies.

Introduction: The incidence of acute kidney injury (AKI) in pediatric patients following cardiac surgery varies between 15 and 64%, with a mortality rate of 10-89% among those requiring dialysis. This variation in the incidence and mortality of AKI across studies is probably due to the inconsistent definitions used for AKI. The purpose of this study is to present our experience with AKI post-cardiac surgery with emphasis on predisposing or aggravating factors. Patients and Methods: We evaluated the incidence of AKI using the KDIGO criteria in 150 infants and children undergoing cardiac surgeries between 2015 and 2017. Post-operatively, all patients were admitted to the pediatric intensive care unit (PICU) at a tertiary care center in a developing country. This is a retrospective chart review in which data collected included age, gender, type of heart disease, prior cardiac surgeries, RACHS-1 category, and pre- and post-operative creatinine levels. Neonates were not included in this study. Results: Six percent of the studied patients were below 1 year of age, 84% 1-10 years, and 10% 10-18 years. Fourteen patients (9.3%) developed AKI. Patients with cyanotic heart disease were more prone to develop AKI (78%) compared to those with non-cyanotic heart disease (44%). Children with AKI had a higher length of stay in PICU, 2.56 ± 1.44 vs. 4 ± 2.66 ( p - 0.02). Serum lactic acid was higher in patients who developed AKI with a mean value of 6.8 ± 6.9 vs. 2.85 ± 1.55 mmol/l in the non-AKI group ( p - 0.03). Lower hemoglobin levels and hyperlactic acidemia were significantly more prevalent in the AKI group. There were five deaths in this series (3.3%), and four of those (80%) were in the AKI group. Conclusion: Using the KDIGO criteria, the incidence of AKI in infants and children following cardiac surgery was 9.3%. This is slightly lower than in previously published studies where the range was between 15 and 64%. Children with cyanotic cardiac disease, hyperlactic acidemia, and anemia were more prone to developing AKI. Identifying patients at risk might help decrease the risk of post-operative AKI., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Aoun, Daher, Daou, Sanjad, Tamim, El Rassi, Arabi, Sharara, Bitar, Assy, Bulbul, Degheili and Majdalani.)

Background: Developing countries are profoundly affected by the burden of congenital heart disease (CHD) because of limited resources, poverty, cost, and inefficient governance. The outcome of pediatric cardiac surgery in developing countries is suboptimal, and the availability of sustainable programs is minimal. Aim: This study describes the establishment of a high quality in-situ pediatric cardiac surgery program in Lebanon, a limited resource country. Methods: We enrolled all patients operated for CHD at the Children's Heart Center at the American University of Beirut between January 2014 and December 2018. Financial information was obtained. We established a partnership between the state, private University hospital, and philanthropic organizations to support the program. Results: In 5 years, 856 consecutive patients underwent 993 surgical procedures. Neonates and infants constituted 22.5 and 22.6% of our cohort, respectively. Most patients (82.6%) underwent one cardiac procedure. Our results were similar to those of the Society of Thoracic Surgeons (STS) harvest and to the expected mortalities in RACHS-1 scores with an overall mortality of 2.8%. The government (Public) covered 43% of the hospital bill, the Philanthropic organizations covered 30%, and the Private hospital provided a 25% discount. The parents' out-of-pocket contribution included another 2%. The average cost per patient, including neonates, was $19,800. Conclusion: High standard pediatric cardiac surgery programs can be achieved in limited-resource countries, with outcome measures comparable to developed countries. We established a viable financial model through a tripartite partnership between Public, Private, and Philanthropy (3P system) to provide high caliber care to children with CHD., (Copyright © 2020 El Rassi, Assy, Arabi, Majdalani, Yunis, Sharara, Maroun-Aouad, Khaddoum, Siddik-Sayyid, Foz, Bulbul and Bitar.)

To investigate the influence of pre-induced fatigue in one leg on neuromuscular performance and corticospinal responses of the contralateral homologous muscles, three experiments were conducted with different exercise protocols; A (n = 12): a 60 s rest vs. time-matched sustained left leg knee extension maximum voluntary contraction (MVC), B ( n = 12): a 60 s rest vs. time-matched left leg MVC immediately followed by 60 s right leg MVC, and C ( n = 9): a similar protocol to experiment B, but with blood flow occluded in the left leg while the right leg was performing the 60 s MVC. The neuromuscular assessment included 5 s knee extensions at 100%, 75%, and 50% of MVC. At each force level, transcranial magnetic and peripheral nerve stimuli were elicited to investigate the influence of different protocols on the right (tested) knee extensors' maximal force output, voluntary activation, corticospinal excitability, and inhibition. The pre-induced fatigue in the left leg did not alter the performance nor the neuromuscular responses recorded from the right leg in the three experiments (all p > 0.3). However, enhanced corticospinal pathway excitability was evident in the tested knee extensors ( p = 0.002). These results suggest that the pre-induced fatigue and muscle ischemia in one leg did not compromise the central and peripheral components of the neuromuscular function in the tested contralateral leg.

Background: An Asthma Adherence Pathway (AAP) application, which is an Internet application that combines patient and clinician education strategies to promote adherence to asthma therapy, has been developed., Objective: The primary objective of this pilot study was to evaluate the effectiveness of the AAP application with electronic adherence monitors on asthma control. Secondary objectives evaluated the effect of AAP and monitors on medication adherence, asthma symptoms, quality of life, psychosocial factors, and barriers to treatment., Methods: Adult patients with asthma were randomly assigned either to intervention (n = 19) or control (n = 20) groups in this 3-month prospective study, and they completed the Asthma Control Questionnaire (ACQ). Intervention patients completed the AAP software and were given barrier-specific motivational interviewing adherence strategies and a SmartTrack device to monitor mometasone furoate/formoterol (MF/F) use. Clinicians in the interventional group received adherence management training. Interventional patients were given feedback regarding adherence findings at each visit. Treatment adherence was determined by the mean of 4 measures of doses taken over 3 months. Control patients were not monitored for MF/F adherence., Results: The mean MF/F adherence in the intervention group was 81%. The intervention and control groups did not differ on the mean baseline ACQ. Thirteen intervention patients achieved the minimal important difference (defined as an improvement ≥0.5 units on the ACQ) compared with 6 control patients (P = .016). The intervention group showed greater improvement in the ACQ (0.75) than the control group (0.19) representing a moderate-to-large effect size of d = 0.638., Conclusions: The AAP was effective in promoting adherence and helped to improve asthma control. These findings provide preliminary validation of the AAP model., (Copyright © 2019 American Academy of Allergy, Asthma & Immunology. Published by Elsevier Inc. All rights reserved.)

Venous thromboembolisms are major risk factors for many of our hospitalized patients. These events, however, can be prevented with prophylactic measurements when administered appropriately and on a timely basis. As patients are admitted, discharged, transferred, and scheduled for procedures on an hourly basis, anticoagulation and deep vein thrombosis prophylaxis are held or discontinued in anticipation for possible procedures. This results in delay of care and intervals where patients may not be covered with any prophylactic measurements. Similarly, alterations in clinical status can quickly change such as an increase in creatinine levels or the development of a new bleed, thus requiring a revision in their deep vein thrombosis prophylaxis. Nurses, therefore, play an integral role in not only administering the medicine but also routinely assessing the patients' clinical status and, therefore, their deep vein thrombosis prophylactic regimens as well. This article will review the indications, scoring systems, common prophylactic methods, and special populations at increased risks for venous thromboembolisms.

Advanced therapies are available for both deep venous thrombosis and pulmonary embolism when anticoagulation alone is not sufficient to improve clinical outcomes. In some cases, clinical deterioration ensues despite anticoagulation, and this requires unique techniques that can ameliorate the clinical course. Such advancements are described in this upcoming article.