A Bayes-competing risk model for the use of expert judgement in reliability estimation

In an analysis of the reliability of heat exchangers, a number of causes of failure and a number of potential failure patterns were identified. To allow a simplification of the analysis, five independent groups of failure causes were defined and formed the basis of a competing risks model. Further, lack of data and poor quality data required the experience of ‘experts’ to be used in a quantitative way through Bayesian methods. Lastly, to simplify the elicitation of the prior densities, a shape, scale and location parameter model for the failure time distributions was adopted

Anomalies of ac driven solitary waves with internal modes: Nonparametric resonances induced by parametric forces

We study the dynamics of kinks in the $\phi^4$ model subjected to a parametric ac force, both with and without damping, as a paradigm of solitary waves with internal modes. By using a collective coordinate approach, we find that the parametric force has a non-parametric effect on the kink motion. Specifically, we find that the internal mode leads to a resonance for frequencies of the parametric driving close to its own frequency, in which case the energy of the system grows as well as the width of the kink. These predictions of the collective coordinate theory are verified by numerical simulations of the full partial differential equation. We finally compare this kind of resonance with that obtained for non-parametric ac forces and conclude that the effect of ac drivings on solitary waves with internal modes is exactly the opposite of their character in the partial differential equation.Comment: To appear in Phys Rev

Digestion, rumen fermentation and circulating concentrations of insulin, growth hormone and IGF-1 in steers fed diets based on different proportions of maize silage and grass silage

Replacing grass silage with maize silage results in a fundamental change in the ratio of structural to non-structural carbohydrates with commensurate changes in rumen fermentation patterns and nutrient utilisation. This study investigated the effects of feeding four forage mixtures, namely grass silage (G); 67 g/100 g grass silage133 g/100 g maize silage (GGM); 67 g/100 g maize silage133/100 g grass silage (MMG); maize silage (M) to four ruminally and duodenally canulated Holstein Friesian steers. All diets were formulated to be isonitrogenous (22.4 g N/kg DM) using a concentrate mixture. Dietary dry matter (DM) and organic matter (OM) digestibility increased with ascending maize silage inclusion (P,0.1) whereas starch and neutral detergent fibre digestibility declined (P,0.05). Ratio of non-glucogenic to glucogenic precursors in the rumen fluid increased with maize silage inclusion (P,0.01) with a commensurate reduction in rumen pH (P,0.05). Mean circulating concentrations of insulin were greatest and similar in diets MMG and GGM, lower in diet M and lowest in diet G (P,0.01). There were no effects of diet on the mean circulating concentration of growth hormone (GH), or the frequency, amplitude and duration of GH pulses, or the mean circulating concentrations of IGF-1. Increasing levels of DM, OM and starch intakes with the substitution of grass silage with maize silage affected overall digestion, nutrient partitioning and subsequent circulating concentrations of insulin

Original research: long-term prognosis after ST-elevation myocardial infarction in patients with a prior cancer diagnosis

Introduction It is unknown how long-term prognosis after ST-elevation myocardial infarction (STEMI) in patients with a prior cancer diagnosis is impacted by cancer-related factors as diagnosis, stage, and treatment. We aimed to assess long-term survival trends after STEMI in this population to evaluate both cardiovascular and cancer-related drivers of prognosis over a follow-up period of 5 years. Methods In this retrospective single-center cohort study, patients with a prior cancer diagnosis admitted with STEMI between 2004 and 2014 and treated with primary percutaneous coronary intervention (PCI) were recruited from the STEMI clinical registry of our institution. Results In the 211 included patients, the cumulative incidence of all-cause death after 5 years of follow-up was 38.1% (N = 60). The cause of death was predominantly malignancy-related (N = 29, 48.3% of deaths) and nine patients (15.0%) died of a cardiovascular cause. After correcting for age and sex, a recent cancer diagnosis ( 10 years, HRadj 2.98 [95% CI: 1.39-6.41], p = 0.005) and distant metastasis at presentation (HRadj 4.02 [1.70-9.53], p = 0.002) were significant predictors of long-term mortality. While maximum levels of cardiac troponin-T and creatinine kinase showed significant association with mortality (resp. HRadj 1.34 [1.08-1.66], p = 0.008; HRadj 1.36 [1.05-1.76], p = 0.019), other known determinants of prognosis after STEMI, e.g., hypertension and renal insufficiency, were not significantly associated with survival. Conclusions Patients with a prior cancer diagnosis admitted with STEMI have a poor survival rate. However, when the STEMI is optimally treated with primary PCI and medication, cardiac mortality is low, and prognosis is mainly determined by factors related to cancer stage.Cardiolog

Coronary anomalies in tetralogy of Fallot - a meta-analysis

Background: An anomalous coronary artery is reported in 2% to 23% of patients with tetralogy of Fallot (TOF). Knowledge of coronary anatomy prior to corrective surgery is vital to avoid damage to vessels crossing the right ventricular outflow tract (RVOT). A meta-analysis on the prevalence of anomalous coronary arteries in TOF is lacking to date. Here, an overview of coronary anomalies in TOF is provided and implications for patient management are discussed.Methods: PubMed, Embase and Web of Science were searched. Analysis was done using Revman 5.3 (Cochrane Community, London). The primary analysis focused on the origin and proximal course of the right and left coronary arteries. In addition, the prevalence of large conus arteries and coronary arteriovenous fistulas (CAVF) was calculated.Results: Twenty-eight studies, encompassing 6956 patients, were included; 6% of TOF patients have an anomalous coronary artery. Hereof, 72% cross the RVOT; the majority of the remaining 28% courses behind the aorta. Six percent of patients have a large conus artery and 4% a CAVF. Other coronary anomalies include a left or right coronary artery from the pulmonary trunk or left or right pulmonary artery, coronary tree hypoplasia and anastomoses between coronary and bronchial arteries.Conclusions: The prevalence of coronary anomalies in TOF is 4-6%. In patients with an anomalous coronary artery, 72% cross the RVOT. The combined risk of encountering an anomalous coronary artery or a large conus artery crossing the RVOT is 10.3%. Coronary anatomy should be defined before surgery and the surgical approach adapted accordingly. (c) 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).Cardiolog

Usefulness of the CRT-SCORE for Shared Decision Making in Cardiac Resynchronization Therapy in Patients With a Left Ventricular Ejection Fraction of <= 35%

Cardiolog

Validation and feasibility of echocardiographic assessment of systemic right ventricular function: serial correlation with MRI

Background: Inherent to its geometry, echocardiographic imaging of the systemic right ventricle (RV) is challenging. Therefore, echocardiographic assessment of systemic RV function may not always be feasible and/or reproducible in daily practice. Here, we aim to validate the usefulness of a comprehensive range of 32 echocardiographic measurements of systemic RV function in a longitudinal cohort by serial assessment of their correlations with cardiac magnetic resonance (CMR)-derived systemic RV ejection fraction (RVEF).Methods: A single-center, retrospective cohort study was performed. Adult patients with a systemic RV who underwent a combination of both CMR and echocardiography at two different points in time were included. Off-line analysis of echocardiographic images was blinded to off-line CMR analysis and vice versa. In half of the echocardiograms, measurements were repeated by a second observer blinded to the results of the first. Correlations between echocardiographic and CMR measures were assessed with Pearson's correlation coefficient and interobserver agreement was quantified with intraclass correlation coefficients (ICC).Results: Fourteen patients were included, of which 4 had congenitally corrected transposition of the great arteries (ccTGA) and 10 patients had TGA late after an atrial switch operation. Eight patients (57%) were female. There was a mean of 8 years between the first and second imaging assessment. Only global systemic RV function, fractional area change (FAC), and global longitudinal strain (GLS) were consistently, i.e., at both time points, correlated with CMR-RVEF (global RV function: r = -0.77/r = -0.63; FAC: r = 0.79/r = 0.67; GLS: r = -0.73/r = -0.70, all p-values < 0.05). The ICC of GLS (0.82 at t = 1, p = 0.006, 0.77 at t = 2, p = 0.024) was higher than the ICC of FAC (0.35 at t = 1, p = 0.196, 0.70 at t = 2, p = 0.051) at both time points.Conclusion: GLS appears to be the most robust echocardiographic measurement of systemic RV function with good correlation with CMR-RVEF and reproducibility.Cardiolog

Resonances in the dynamics of ϕ4\phi^4 kinks perturbed by ac forces

We study the dynamics of $\phi^4$ kinks perturbed by an ac force, both with and without damping. We address this issue by using a collective coordinate theory, which allows us to reduce the problem to the dynamics of the kink center and width. We carry out a careful analysis of the corresponding ordinary differential equations, of Mathieu type in the undamped case, finding and characterizing the resonant frequencies and the regions of existence of resonant solutions. We verify the accuracy of our predictions by numerical simulation of the full partial differential equation, showing that the collective coordinate prediction is very accurate. Numerical simulations for the damped case establish that the strongest resonance is the one at half the frequency of the internal mode of the kink. In the conclusion we discuss on the possible relevance of our results for other systems, especially the sine-Gordon equation. We also obtain additional results regarding the equivalence between different collective coordinate methods applied to this problem.Comment: 23 pages, 7 figures, REVTeX, accepted for publication in Phys. Rev.