Control of flow geometry using electromagnetic body forcing

Accepted versio

Variational methods

International audienceThis contribution presents derivative-based methods for local sensitivity analysis, called Variational Sensitivity Analysis (VSA). If one defines an output called the response function, its sensitivity to inputs variations around a nominal value can be studied using derivative (gradient) information. The main issue of VSA is then to provide an efficient way of computing gradients. This contribution first presents the theoretical grounds of VSA: framework and problem statement, tangent and adjoint methods. Then it covers pratical means to compute derivatives, from naive to more sophisticated approaches, discussing their various 2 merits. Finally, applications of VSA are reviewed and some examples are presented, covering various applications fields: oceanography, glaciology, meteorology

Perioperative Risk in Adults with Congenital Heart Disease Undergoing Non-Cardiac Surgery: Challenges and Tailored Strategies.

Advances in surgical and medical management of congenital heart disease have improved survival rates, leading to a growing population of adult congenital heart disease (ACHD) patients requiring specialized perioperative care. Studies indicate that ACHD patients undergoing non-cardiac surgery (NC surgery) have increased mortality and morbidity risks compared to the general population, with complication rates particularly high in those with complex defects, such as Fontan circulation, Eisenmenger syndrome, or cyanotic congenital heart disease. Key perioperative concerns include hemodynamic instability, arrhythmias, thromboembolic events, and bleeding risks. Additionally, comorbidities, such as frailty, chronic inflammation, or respiratory disease, further complicate perioperative management. Multidisciplinary collaboration is critical, involving cardiologists, anesthesiologists, and surgeons to optimize preoperative preparation and perioperative monitoring. Preoperative risk stratification is essential, integrating congenital heart lesion complexity, functional status, and procedural risk. This review underscores the importance of structured preoperative assessment, appropriate risk evaluation, and individualized perioperative strategies to improve surgical outcomes in ACHD patients undergoing NC surgery. Further research is needed to refine risk prediction models and optimize perioperative protocols tailored to this unique patient population

Seeding and adjoining zero-halo partitioned parallel scientific codes

Algorithmic differentiation tools can automate the adjoint transformation of parallel message passing codes [18] using the AMPI library. Nevertheless, a non-trivial and manual step post-differentiation is seed initialisation and retrieval of the output values from the differentiated code. In this work, we present the problems and ambiguities associated with seed initialisation and output retrieval for adjoint transformation of zero-halo partitioned MPI programs. Shared-node reduction is an important parallel primitive in the zero-halo context. We introduce a general framework to eliminate ambiguities in seeding and retrieval for a general class of shared-node reduction using a conceptual master-worker model. Corollaries from the model show the need for new MPI calls for retrieval and eliminate MPI calls for seed initialisation. Different possible implementations for seeding manually assembled adjoints were inferred from the model, namely, (i) partial and (ii) unique. We successfully demonstrate the seeding of the manually assembled adjoint FPI in a 3d zero-halo partitioned unstructured compressible flow solver. The different implementations, their merits and demerits are highlighted. Tapenade AD tool was used throughout this work. Keywords

Reverse Automatic Differentiation for Optimum Design: from Adjoint State Assembly to Gradient Computation

The utilization of reverse mode Automatic Differentiation to the adjoint method for solving an Optimal Design problem is described. Using the reverse mode, we obtain the adjoint system residual in a rather efficient way. But memory requirements may be very large. The family of programs to differentiate involves many independant calculations, typically in parallel loops. Then we propose to apply a reverse differentiation «by iteration». This demands much less memory storage. This methods is used for the computing of the adjoint state and gradient related to the Optimal Design problem

Surgical site infection after gastrointestinal surgery in high-income, middle-income, and low-income countries: a prospective, international, multicentre cohort study

Background: Surgical site infection (SSI) is one of the most common infections associated with health care, but its importance as a global health priority is not fully understood. We quantified the burden of SSI after gastrointestinal surgery in countries in all parts of the world. Methods: This international, prospective, multicentre cohort study included consecutive patients undergoing elective or emergency gastrointestinal resection within 2-week time periods at any health-care facility in any country. Countries with participating centres were stratified into high-income, middle-income, and low-income groups according to the UN's Human Development Index (HDI). Data variables from the GlobalSurg 1 study and other studies that have been found to affect the likelihood of SSI were entered into risk adjustment models. The primary outcome measure was the 30-day SSI incidence (defined by US Centers for Disease Control and Prevention criteria for superficial and deep incisional SSI). Relationships with explanatory variables were examined using Bayesian multilevel logistic regression models. This trial is registered with ClinicalTrials.gov, number NCT02662231. Findings: Between Jan 4, 2016, and July 31, 2016, 13 265 records were submitted for analysis. 12 539 patients from 343 hospitals in 66 countries were included. 7339 (58·5%) patient were from high-HDI countries (193 hospitals in 30 countries), 3918 (31·2%) patients were from middle-HDI countries (82 hospitals in 18 countries), and 1282 (10·2%) patients were from low-HDI countries (68 hospitals in 18 countries). In total, 1538 (12·3%) patients had SSI within 30 days of surgery. The incidence of SSI varied between countries with high (691 [9·4%] of 7339 patients), middle (549 [14·0%] of 3918 patients), and low (298 [23·2%] of 1282) HDI (p < 0·001). The highest SSI incidence in each HDI group was after dirty surgery (102 [17·8%] of 574 patients in high-HDI countries; 74 [31·4%] of 236 patients in middle-HDI countries; 72 [39·8%] of 181 patients in low-HDI countries). Following risk factor adjustment, patients in low-HDI countries were at greatest risk of SSI (adjusted odds ratio 1·60, 95% credible interval 1·05–2·37; p=0·030). 132 (21·6%) of 610 patients with an SSI and a microbiology culture result had an infection that was resistant to the prophylactic antibiotic used. Resistant infections were detected in 49 (16·6%) of 295 patients in high-HDI countries, in 37 (19·8%) of 187 patients in middle-HDI countries, and in 46 (35·9%) of 128 patients in low-HDI countries (p < 0·001). Interpretation: Countries with a low HDI carry a disproportionately greater burden of SSI than countries with a middle or high HDI and might have higher rates of antibiotic resistance. In view of WHO recommendations on SSI prevention that highlight the absence of high-quality interventional research, urgent, pragmatic, randomised trials based in LMICs are needed to assess measures aiming to reduce this preventable complication

COVID-19-Related Thrombotic and Bleeding Events in Adults With Congenital Heart Disease.

BACKGROUND Altered coagulation is a striking feature of COVID-19. Adult patients with congenital heart disease (ACHD) are prone to thromboembolic (TE) and bleeding complications. OBJECTIVES The purpose of this study was to investigate the prevalence and risk factors for COVID-19 TE/bleeding complications in ACHD patients. METHODS COVID-19-positive ACHD patients were included between May 2020 and November 2021. TE events included ischemic cerebrovascular accident, systemic and pulmonary embolism, deep venous thrombosis, myocardial infarction, and intracardiac thrombosis. Major bleeding included cases with hemoglobin drop >2 g/dl, involvement of critical sites, or fatal bleeding. Severe infection was defined as need for intensive care unit, endotracheal intubation, renal replacement therapy, extracorporeal membrane oxygenation, or death. Patients with TE/bleeding were compared to those without events. Factors associated with TE/bleeding were determined using logistic regression. RESULTS Of 1,988 patients (age 32 [IQR: 25-42] years, 47% male, 59 ACHD centers), 30 (1.5%) had significant TE/bleeding: 12 TE events, 12 major bleeds, and 6 with both TE and bleeding. Patients with TE/bleeding had higher in-hospital mortality compared to the remainder cohort (33% vs 1.7%; P < 0.0001) and were in more advanced physiological stage (P = 0.032) and NYHA functional class (P = 0.01), had lower baseline oxygen saturation (P = 0.0001), and more frequently had a history of atrial arrhythmia (P < 0.0001), previous hospitalization for heart failure (P < 0.0007), and were more likely hospitalized for COVID-19 (P < 0.0001). By multivariable logistic regression, prior anticoagulation (OR: 4.92; 95% CI: 2-11.76; P = 0.0003), cardiac injury (OR: 5.34; 95% CI: 1.98-14.76; P = 0.0009), and severe COVID-19 (OR: 17.39; 95% CI: 6.67-45.32; P < 0.0001) were independently associated with increased risk of TE/bleeding complications. CONCLUSIONS ACHD patients with TE/bleeding during COVID-19 infection have a higher in-hospital mortality from the illness. Risk of coagulation disorders is related to severe COVID-19, cardiac injury during infection, and use of anticoagulants