Code verification examples of a fully geometrical nonlinear membrane element using the method of manufactured solutions

This paper presents an effective method to perform Code Verification of a software which is designed for structural analysis using membranes. The focus lies on initially curved structures with large deformations in steady and unsteady regimes. The material is assumed to be linear elastic isotropic. Code Verification is a part of efforts to guarantee the code’s correctness and to obtain finally predictive capability of the code. The Method of Manufactured Solutions turned out to be an effective tool to perform Code Verification, especially for initially curved structures. Here arbitrary invented geometries and analytical solutions are chosen. The computer code must approach this solution asymptotically. The observed error reduction with systematic mesh refinement (i.e. observed order of accuracy) must be in the range of the formal order of accuracy, e.g. derived by a Taylor series expansion. If these two orders match in the asymptotic range, the implemented numerical algorithms are working as intended. The given examples provide a complete hierarchical benchmark suite for the reader to assess other codes, too. In the present case several membrane states were tested successfully and the used code Carat++ assessed to converge - as intended - second order accurately in space and time for all kind of shapes and solution

Advancing Intraoperative Assessment of Urethral Stricture Anatomic Variation: a Prospective Proof-of-concept Study

INTRODUCTION Urethral strictures, particularly those refractory to endoscopic interventions, are commonly treated through open urethroplasty. However, predicting recurrence in homogeneous patient populations remains challenging. METHODS To address this, we developed an intraoperative urethral stricture assessment tool aiming to identify comprehensive risk predictors. The assessment includes detailed parameters on stricture location, length, urethral bed width, spongiosum thickness, obliteration grade, and spongiofibrosis extension. The tool was prospectively implemented in 106 men with anterior one-stage augmentation urethroplasty 04/2020 to 10/2021. RESULTS An intraoperative granular assessment of intricate stricture characteristics is feasible. Comparative analyses revealed significant differences between bulbar and penile strictures. Bulbar strictures exhibited wider urethral beds and thicker spongiosum compared to penile strictures (all P<0.001). The assessment showed marked variations in the degree of obliteration and spongiofibrosis extension. CONCLUSION Our tool aligns with efforts to standardize urethral surgery, providing insights into subtle disease intricacies and enabling comparisons between institutions. Notably, intraoperative assessment may surpass the limitations of preoperative imaging, emphasizing the necessity of intraoperative evaluation. While limitations include a single-institution study and limited sample size, future research aims to refine this tool and determine its impact on treatment strategies, potentially improving long-term outcomes for urethral strictures

Neurofilament Light Chain: Blood Biomarker of Neonatal Neuronal Injury

Background: Neurofilament light chain (NfL) is a highly promising biomarker of neuroaxonal injury that has mainly been studied in adult neurodegenerative disease. Its involvement in neonatal disease remains largely unknown. Our aim was to establish NfL plasma concentrations in preterm and term infants in the first week of life.Methods: Plasma NfL was measured by single molecule array immunoassay in two neonatal cohorts: cohort 1 contained 203 term and preterm infants, median gestational age (GA) 37.9 weeks (interquartile range [IQR] 31.9–39.4), in whom venous and arterial umbilical cord blood was sampled at birth and venous blood at day of life (DOL) 3; cohort 2 contained 98 preterm infants, median GA 29.3 weeks (IQR 26.9–30.6), in whom venous blood was sampled at DOL 7.Results: Median NfL concentrations in venous blood increased significantly from birth (18.2 pg/mL [IQR 12.8–30.8, cohort 1]) to DOL 3 (50.9 pg/mL [41.3–100, cohort 1]) and DOL 7 (126 pg/mL [78.8–225, cohort 2]) (p &lt; 0.001). In both cohorts NfL correlated inversely with birth weight (BW, Spearman's rho −0.403, p &lt; 0.001, cohort 1; R −0.525, p &lt; 0.001, cohort 2) and GA (R −0.271, p &lt; 0.001, cohort 1; R −0.487, p &lt; 0.001, cohort 2). Additional significant correlations were found for maternal age at delivery, preeclampsia, delivery mode, 5-min Apgar, duration of oxygen supplementation, sepsis, and brain damage (intraventricular hemorrhage or periventricular leukomalacia). Multivariable logistic regression analysis identified the independent predictors of NfL in cohort 1 as BW (beta = −0.297, p = 0.003), delivery mode (beta = 0.237, p = 0.001) and preeclampsia (beta = 0.183, p = 0.022) and in cohort 2 as BW (beta = −0.385, p = 0.001) and brain damage (beta = 0.222, p = 0.015).Conclusion: Neonatal NfL levels correlate inversely with maturity and BW, increase during the first days of life, and relate to brain injury factors such as intraventricular hemorrhage and periventricular leukomalacia, and also to vaginal delivery

Outcomes and Complication Rates of Cuff Downsizing in the Treatment of Worsening or Persistent Incontinence After Artificial Urinary Sphincter Implantation

Purpose This study investigated the functional outcomes and complication rates of cuff downsizing for the treatment of recurrent or persistent stress urinary incontinence (SUI) in men after the implantation of an artificial urinary sphincter (AUS). Methods Data from our institutional AUS database spanning the period from 2009 to 2020 were retrospectively analyzed. The number of pads per day was determined, a standardized quality of life (QoL) questionnaire and the International Consultation on Incontinence Questionnaire (ICIQ) were administered, and postoperative complications according to the Clavien-Dindo classification were analyzed. Results Out of 477 patients who received AUS implantation during the study period, 25 (5.2%) underwent cuff downsizing (median age, 77 years; interquartile range [IQR], 74–81 years; median follow-up, 4.4 years; IQR, 3–6.9 years). Before downsizing, SUI was very severe (ICIQ score 19–21) or severe (ICQ score 13–18) in 80% of patients, moderate (ICIQ score 6–12) in 12%, and slight (ICIQ score 1–5) in 8%. After downsizing, 52% showed an improvement of >5 out of 21 points. However, 28% still had very severe or severe SUI, 48% had moderate SUI, and 20% had slight SUI. One patient no longer had SUI. In 52% of patients, the use of pads per day was reduced by ≥50%. QoL improved by >2 out of 6 points in 56% of patients. Complications (infections/urethral erosions) requiring device explantation occurred in 36% of patients, with a median time to event of 14.5 months. Conclusions Although cuff downsizing carries a risk of AUS explantation, it can be a valuable treatment option for selected patients with persistent or recurrent SUI after AUS implantation. Over half of patients experienced improvements in symptoms, satisfaction, ICIQ scores, and pad use. It is important to inform patients about the potential risks and benefits of AUS to manage their expectations and assess individual risks

Experimental designs for small randomised clinical trials: An algorithm for choice

Background: Small clinical trials are necessary when there are difficulties in recruiting enough patients for conventional frequentist statistical analyses to provide an appropriate answer. These trials are often necessary for the study of rare diseases as well as specific study populations e.g. children. It has been estimated that there are between 6,000 and 8,000 rare diseases that cover a broad range of diseases and patients. In the European Union these diseases affect up to 30 million people, with about 50% of those affected being children. Therapies for treating these rare diseases need their efficacy and safety evaluated but due to the small number of potential trial participants, a standard randomised controlled trial is ofte

Etiology, 3-Month Functional Outcome and Recurrent Events in Non-Traumatic Intracerebral Hemorrhage.

BACKGROUND AND PURPOSE Knowledge about different etiologies of non-traumatic intracerebral hemorrhage (ICH) and their outcomes is scarce. METHODS We assessed prevalence of pre-specified ICH etiologies and their association with outcomes in consecutive ICH patients enrolled in the prospective Swiss Stroke Registry (2014 to 2019). RESULTS We included 2,650 patients (mean±standard deviation age 72±14 years, 46.5% female, median National Institutes of Health Stroke Scale 8 [interquartile range, 3 to 15]). Etiology was as follows: hypertension, 1,238 (46.7%); unknown, 566 (21.4%); antithrombotic therapy, 227 (8.6%); cerebral amyloid angiopathy (CAA), 217 (8.2%); macrovascular cause, 128 (4.8%); other determined etiology, 274 patients (10.3%). At 3 months, 880 patients (33.2%) were functionally independent and 664 had died (25.1%). ICH due to hypertension had a higher odds of functional independence (adjusted odds ratio [aOR], 1.33; 95% confidence interval [CI], 1.00 to 1.77; P=0.05) and lower mortality (aOR, 0.64; 95% CI, 0.47 to 0.86; P=0.003). ICH due to antithrombotic therapy had higher mortality (aOR, 1.62; 95% CI, 1.01 to 2.61; P=0.045). Within 3 months, 4.2% of patients had cerebrovascular events. The rate of ischemic stroke was higher than that of recurrent ICH in all etiologies but CAA and unknown etiology. CAA had high odds of recurrent ICH (aOR, 3.38; 95% CI, 1.48 to 7.69; P=0.004) while the odds was lower in ICH due to hypertension (aOR, 0.42; 95% CI, 0.19 to 0.93; P=0.031). CONCLUSIONS Although hypertension is the leading etiology of ICH, other etiologies are frequent. One-third of ICH patients are functionally independent at 3 months. Except for patients with presumed CAA, the risk of ischemic stroke within 3 months of ICH was higher than the risk of recurrent hemorrhage

Code verification examples of a fully geometrical nonlinear membrane element using the method of manufactured solutions

This paper presents an effective method to perform Code Verification of a software which is designed for structural analysis using membranes. The focus lies on initially curved structures with large deformations in steady and unsteady regimes. The material is assumed to be linear elastic isotropic. Code Verification is a part of efforts to guarantee the code’s correctness and to obtain finally predictive capability of the code. The Method of Manufactured Solutions turned out to be an effective tool to perform Code Verification, especially for initially curved structures. Here arbitrary invented geometries and analytical solutions are chosen. The computer code must approach this solution asymptotically. The observed error reduction with systematic mesh refinement (i.e. observed order of accuracy) must be in the range of the formal order of accuracy, e.g. derived by a Taylor series expansion. If these two orders match in the asymptotic range, the implemented numerical algorithms are working as intended. The given examples provide a complete hierarchical benchmark suite for the reader to assess other codes, too. In the present case several membrane states were tested successfully and the used code Carat++ assessed to converge - as intended - second order accurately in space and time for all kind of shapes and solution