Efficacy of the FDA nozzle benchmark and the lattice Boltzmann method for the analysis of biomedical flows in transitional regime

Flows through medical devices as well as in anatomical vessels despite being at moderate Reynolds number may exhibit transitional or even turbulent character. In order to validate numerical methods and codes used for biomedical flow computations, the U.S. food and drug administration (FDA) established an experimental benchmark, which was a pipe with gradual contraction and sudden expansion representing a nozzle. The experimental results for various Reynolds numbers ranging from 500 to 6500 were publicly released. Previous and recent computational investigations of flow in the FDA nozzle found limitations in various CFD approaches and some even questioned the adequacy of the benchmark itself. This communication reports the results of a lattice Boltzmann method (LBM) based direct numerical simulation (DNS) approach applied to the FDA nozzle benchmark for transitional cases of Reynolds numbers 2000 and 3500. The goal is to evaluate if a simple off the shelf LBM would predict the experimental results without the use of complex models or synthetic turbulence at the inflow. LBM computations with various spatial and temporal resolutions are performed - in the extremities of 44 million to 2.8 billion lattice cells - conducted respectively on 32 CPU cores of a desktop to more than 300'000 cores of a modern supercomputer to explore and characterize miniscule flow details and quantify Kolmogorov scales. The LBM simulations transition to turbulence at a Reynolds number 2000 like the FDA's experiments and acceptable agreement in jet breakdown locations, average velocity, shear stress and pressure is found for both the Reynolds numbers

Tibial tuberosity fracture in adult as an unusual pattern of injury

Tibial tuberosity avulsion is an uncommon fracture in adults, such lesions typically seen in adolescent male with well-developed quadriceps, ligaments when they are stronger than growth plate. We described a case of 51-year-old gentlemen had direct trauma to left knee, no risk factors were identified, not able to walk, difficulty in straight leg raise test, radiograph of left knee showed tibial tuberosity avulsion fracture. The fracture was treated with open reduction and internal fixation, f/u with successful rehabilitation which results in good range of motion and excellent function at knee joint. The aim of study is present unusual and rare case of tibial tuberosity Avulsion fracture in adult, early diagnosis, surgical mode of treatment, post-surgery rehabilitation and possible complications

Optimal Control of Logically Constrained Partially Observable and Multi-Agent Markov Decision Processes

Autonomous systems often have logical constraints arising, for example, from safety, operational, or regulatory requirements. Such constraints can be expressed using temporal logic specifications. The system state is often partially observable. Moreover, it could encompass a team of multiple agents with a common objective but disparate information structures and constraints. In this paper, we first introduce an optimal control theory for partially observable Markov decision processes (POMDPs) with finite linear temporal logic constraints. We provide a structured methodology for synthesizing policies that maximize a cumulative reward while ensuring that the probability of satisfying a temporal logic constraint is sufficiently high. Our approach comes with guarantees on approximate reward optimality and constraint satisfaction. We then build on this approach to design an optimal control framework for logically constrained multi-agent settings with information asymmetry. We illustrate the effectiveness of our approach by implementing it on several case studies.Comment: arXiv admin note: substantial text overlap with arXiv:2203.0903

Prevention of heart failure events with sodium-glucose co-transporter 2 inhibitors across a spectrum of cardio-renal-metabolic risk

Aims Trials have tested the safety and efficacy of sodium-glucose co-transporter 2 inhibitors (SGLT2i) across various disease states. We performed a meta-analysis of randomized controlled trials (RCTs) to estimate the relative and absolute effects of SGLT2i in the prevention of heart failure (HF) events across different risk groups. Methods and results We conducted a systematic review and meta-analysis of large, placebo-controlled RCTs with >1000 participants evaluating HF hospitalization and the composite of cardiovascular (CV) death or HF hospitalization. Due to varying durations of therapeutic exposure and follow-up, absolute risk reductions and number needed to treat were calculated based on incidence rates (per 100 patient-years). Across 71 553 patients enrolled in 10 late-phase RCTs, SGLT2i reduced the risk of HF hospitalization by 31% [hazard ratio (HR) 0.69, 95% confidence interval (CI) 0.64-0.74; I-2 = 0%] and the composite outcome of CV death or HF hospitalization by 24% (HR 0.76, 95% CI 0.72-0.80; I-2 = 1.4%) compared with placebo. The number of patient-years of treatment exposure needed to prevent one CV death or HF hospitalization ranged from 19-26 (established HF) to 72-125 (chronic kidney disease) to 96-400 (high-risk type 2 diabetes). In mixed-effects meta-regression analyses, the benefits of SGLT2i on HF hospitalizations or the composite outcome (CV death or HF hospitalization) were not influenced by age, sex, or change in intermediate markers (glycated haemoglobin, systolic blood pressure, and body weight) (all P >= 0.10). Conclusion Despite wide variation in baseline risks and disease states evaluated, SGLT2i demonstrated comparable relative risk reductions in preventing HF events. Patients at highest baseline risk derived the greatest absolute benefits in preventing HF events. These composite estimates may help guide targeted implementation of SGLT2i for the prevention of HF events in type 2 diabetes and chronic kidney disease and in the treatment of HF