Effect of folds and pockets on the topology and propagation of premixed turbulent flames

Propagation of premixed turbulent flames is examined using a hybrid Navier-Stokes/front tracking methodology, within the context of a hydrodynamic model. The flame, treated as a surface of density discontinuity separating the burned and unburned gases, propagates relative to the fresh mixture at a speed that depends on the local mixture (through a Markstein length) and flow conditions (through the stretch rate), and the flow field is modified in turn by gas expansion; only positive Markstein length are considered, where thermo-diffusive instabilities are absent. Depending on the Markstein length, we have identified in a previous publication two modes of propagation - sub-critical and super-critical, based on whether the effects of the Darrieus-Landau instability are absent or dominant, respectively. The results were limited to low turbulence intensities where the mathematical representation of the flame front was based on an explicit single-valued function. In the present paper we utilize a generalized representation of the flame surface that allows for multivalued and disjointed interfaces, thus extending the results to higher turbulence intensities. We show that when increasing the turbulence intensity the influence of the Darrieus-Landau instability on the super-critical mode of propagation progressively decreases and in the newly identified highly-turbulent regime the flame is dominated completely by the turbulence for all values of Markstein numbers; i.e., with no distinction between sub- and super-critical conditions. Primary importance is given to the determination of the turbulent flame speed and its dependence on turbulence intensity which, when increasing the turbulence level, transitions from a quadratic to a sub-linear scaling. Moreover, the exponent of the sub-linear scaling for the turbulent flame speed is generally lower than the corresponding exponent for the scaling of the flame surface area ratio, which is often used for experimentally determining the turbulent flame speed. We show that the leveling in the rate of increase of the turbulent flame speed with turbulence intensity, is due to frequent flame folding and detachment of pockets of unburned gas that cause a reduction in the average main surface area of the flame, while the lower exponents in the scaling law for the turbulent flame speed compared to that of the flame surface area ratio is due to flame stretching. Disregarding the effect of flame stretch for mixtures of positive Markstein length results in overestimating the turbulent flame speed. Finally, we characterize the flame turbulence interaction via quantities such as the mean vorticity and mean strain, illustrating the effects of incoming turbulence on the flame and the modification of the flow by the flame on the unburned and burned sides

Numerical investigation of unsteady laminar methane/LOx flamelet at supercritical pressures

High-pressure combustion devices, such as liquid rocket engines, are usually characterized by transcritical and supercritical operating conditions. Propellants injected in the combustion chamber experience extremely high den- sity gradients and real fluid effects. In the present study, real fluid effects on flame structure are investigated in the framework of unsteady laminar flamelet equations, a well established representation and diagnostic tool for non pre- mixed combustion transient phenomena. Real fluid thermodynamic properties are taken into account by means of a computationally efficient cubic equation of state written in a general and comprehensive three-parameter fashion. High-pressure conditions for unsteady flame structure calculations and analysis are chosen as a representative range of a methane/liquid-oxygen rocket engine operating conditions. Particular focus is posed on the constant pressure specific heat behavior at low temperature, which influences the time evolution of the flame structure. Moreover time accurate integration of flamelet equations represent the very first building block of a conditional moment closure for supercritical turbulent combustion

Efficient and accurate calculation of dispersion relations for intrinsically unstable premixed flames

Premixed flames are susceptible to hydrodynamic and thermodiffusive instabilities that wrinkle the flame front and lead to complex multiscale patterns. They strongly impact the flame propagation and dynamics, increasing the speed of a laminar flame by several folds, easily as large as a factor of five for lean hydrogen flames at high pressure. The dispersion relation, which represents the growth rate of the different harmonic components of the perturbation of the flame front for different wavelengths, is useful to understand the dynamics during the linear phase of flame instabilities. In this work, an efficient and accurate approach based on a Fourier analysis of flame wrinkling is proposed to calculate the dispersion relation. Differently from the typical approach based on perturbing the flame with a single wavelength, the flame is perturbed with a spectrum of sine waves and their growth is followed with a spectral analysis. With the present method, the full dispersion relation is computed with a single simulation; this is significantly more efficient computationally than running a series of simulations with a single-wavelength perturbation for each point of the dispersion relation. It is shown that the presented approach is accurate and also solves an issue encountered when a single perturbation is imposed to compute the growth rate of large wavelengths. Several numerical and initialisation parameters, including resolution, domain size, and amplitude of the initial perturbation, are studied systematically and assessed

I.S.Mu.L.T - Rotator cuff tears guidelines

Despite the high level achieved in the field of shoulder surgery, a global consensus on rotator cuff tears management is lacking. This work is divided into two main sessions: in the first, we set questions about hot topics involved in the rotator cuff tears, from the etiopathogenesis to the surgical treatment. In the second, we answered these questions by mentioning Evidence Based Medicine. The aim of the present work is to provide easily accessible guidelines: they could be considered as recommendations for a good clinical practice developed through a process of systematic review of the literature and expert opinion, in order to improve the quality of care and rationalize the use of resources

MRI index lesion radiomics and machine learning for detection of extraprostatic extension of disease: a multicenter study

Objectives: To build a machine learning (ML) model to detect extraprostatic extension (EPE) of prostate cancer (PCa), based on radiomics features extracted from prostate MRI index lesions. Methods: Consecutive MRI exams of patients undergoing radical prostatectomy for PCa were retrospectively collected from three institutions. Axial T2-weighted and apparent diffusion coefficient map images were annotated to obtain index lesion volumes of interest for radiomics feature extraction. Data from one institution was used for training, feature selection (using reproducibility, variance and pairwise correlation analyses, and a correlation-based subset evaluator), and tuning of a support vector machine (SVM) algorithm, with stratified 10-fold cross-validation. The model was tested on the two remaining institutions' data and compared with a baseline reference and expert radiologist assessment of EPE. Results: In total, 193 patients were included. From an initial dataset of 2436 features, 2287 were excluded due to either poor stability, low variance, or high collinearity. Among the remaining, 14 features were used to train the ML model, which reached an overall accuracy of 83% in the training set. In the two external test sets, the SVM achieved an accuracy of 79% and 74% respectively, not statistically different from that of the radiologist (81-83%, p = 0.39-1) and outperforming the baseline reference (p = 0.001-0.02). Conclusions: A ML model solely based on radiomics features demonstrated high accuracy for EPE detection and good generalizability in a multicenter setting. Paired to qualitative EPE assessment, this approach could aid radiologists in this challenging task

Metastasis-Directed Radiation Therapy with Consolidative Intent for Oligometastatic Urothelial Carcinoma: A Systematic Review and Meta-Analysis

The management of patients with oligometastatic urothelial carcinoma (UC) represents an evolving field in uro-oncology, and the role of metastasis-directed therapies, including metastasectomy and metastasis-directed radiation therapy (MDRT), is gaining increasing attention. Herein, we summarize available evidence about the role of MDRT with consolidative intent in oligometastatic UC patients. A systematic review was performed in December 2021. Six studies involving 158 patients were identified. Most patients (n = 120, 90.2%) had a history of bladder cancer and the most frequent sites of metastases were lymph nodes (n = 61, 52.1%) followed by the lungs (n = 34, 29%). Overall, 144 metastases were treated with MDRT. Median follow-up ranged from 17.2 to 25 months. Local control rates ranged from 57% to 100%. Median Overall Survival (OS) ranged from 14.9 to 51.0 months and median progression-free survival ranged from 2.9 to 10.1 months. Rates of OS at one and two years ranged from 78.9% to 96% and from 26% to 63%, respectively. Treatment-related toxicity was recorded in few patients and in most cases a low-grade toxicity was evident. MDRT with consolidative intent represents a potential treatment option for selected patients with oligometastatic UC

Validation of the Italian version of wisconsin stone quality of life (WISQOL): a prospective Italian multicenter study

Urolithiasis is a worldwide spread condition that affects patients' Health-Related Quality of Life (HRQOL), which measurement is an important tool for routine clinical and research practice. Disease-specific HRQOL measures demonstrated to perform better in assessing the effects of specific conditions. A disease-specific questionnaire for kidney stones, the WISQOL, has been validated in different languages, but an Italian version is still missing. Our aim is to produce and validate the Italian version of WISQOL (IT-WISQOL). Patients undergoing any elective treatment for upper urinary tract stones were enrolled. A multi-step process with forward- and back-translation was used to translate WISQOL into Italian. Patients were evaluated within 15 days pre-operatively and then at 30-, 90 days post-operatively and administered both IT-WISQOL and SF-36v2. Post-operative data such as 30 days postoperative complications, late stone-related events, successful status, and stone complexity were collected. Cronbach's α was used to evaluate the internal consistency of IT-WISQOL, while Spearman's rho was used for item and inter-domain correlations and IT-WISQOL with SF-36v2 correlation. We found excellent internal consistency across all domains (α ≥ 0.88), particularly when the total score is considered (α = 0.960). Test-retest reliability showed excellent results for the total questionnaire (Pearson correlation value: 0.85). The Inter-domain association ranged from 0.497 to 0.786. Convergent validity was confirmed by a good correlation with subdomains of the SF-36v2 measures. IT-WISQOL is a reliable tool to measure HRQOL in stone patients. It shows analog characteristics if compared to English WISQOL

Mobile health applications in kidney stone disease management: A reliable support for patients?

Introduction: Mobile health applications (MHAs) represent an interesting issue to assist and improve the quality of life of patients affected by Kidney Stone Disease (KSD). Despite this, their scientific quality and adherence to guidelines are not yet addressed.Material and methods: On 2 November 2022, we conducted an observational cross-sectional descriptive study of all MHAs on KSD. A search in the Apple App Store and Google Play Store was performed. We reviewed all mobile apps from Apple App Store and Google Play Store for KSD and evaluated their usage in screening, prevention, management, and adherence to EAU guidelines.Results: In total 13 MHA were included in the final analysis. All MHAs, 4 (30.8%) from the Apple App Store and 9 (69.2%) from the Google Play Store are geared towards the patient. Engagement ranged from 1.73 to 4.06; Functionality ranged from 3.17 to 4.75; Aesthetics ranged from 1.9 to 4.12; Information ranged from 2.25 to 4.27, and Subjective quality ranged from 1.58 to 3.23. MHAs reported low and medium adherence to EAU guidelines.Conclusions: MHAs provide a very useful assistance in several medical fields, including KSD. Despite MHAs development is constantly increasing, the scientific validation, content, and quality are not yet solved. Future research is necessary to improve the quality of the apps and promote new user designed, and high-quality apps

Could YouTubeTM encourage men on prostate checks? A contemporary analysis

Objectives: To assess YouTube™ videos' quality on prostate checks, especially on the digital rectal exam (DRE), and to investigate if they can inform patients correctly and eradicate their beliefs and myths.Methods: A search using as keywords "digital rectal exam for prostate cancer" was performed on the YouTubeTM platform. We selected the first 100 videos. To assess video quality content, Patient Education Materials Assessment Tool for audio-visual content (PEMAT A/V) and Misinformation tool were used.Results: Seventy-three videos were suitable for the analyses. The median PEMAT A/V Understandability score and PEMAT A/V Actionability score were 46.2% (interquartile range [IQR]: 30.8-76.9) and 50.0% (IQR: 25.0-75.0), respectively. The medi-an PEMAT A/V Understandability and Actionability scores were 69.2% (IQR: 46.2-88.5) vs 46.2% (IQR: 30.8-61.5) (p = 0.01) and 100.0% (IQR: 87.5-100.0) vs 25.0% (IQR: 25.0-68.8)(p < 0.001), for healthcare workers vs patients, respectively. According to the Misinformation tool, the median misinforma-tion score of the overall videos was 2.2 (IQR:1.7-2.8). According to the target audience, the misinformation score was 2.8 (IQR: 2.4-3.5) vs 2.0 (IQR: 1.5-2.8) (p = 0.02), for healthcare workers vs patients, respectively. Conclusions: Currently, based on our analyses, YouTubeTM videos' quality on DRE resulted unsatisfactory according to the PEMAT A/V score and the Misinformation tool. Videos targeted to healthcare workers got higher quality scores if compared to videos targeted to patients. Therefore, YouTubeTM videos' may not be considered a reliable source of information on DRE for patients