On-lattice kinetic Monte Carlo simulations of point defect aggregation in entropically influenced crystalline systems

An on-lattice kinetic Monte Carlo model of vacancy aggregation in crystalline silicon is parametrized using direct regression to evolution data from nonequilibrium molecular dynamics simulations. The approach bypasses the need to manually compute an energy barrier for each possible transition and leads to an excellent, robust representation of the molecular dynamics data. We show that the resulting lattice kinetic Monte Carlo model correctly captures the behavior of the real, continuous space system by properly accounting for continuous space entropic effects, which are often neglected in lattice-based models of atomistic processes. These contributions are particularly important at the high temperatures relevant to many steps in semiconductor materials processing

Risk Factors for Major Early Adverse Events Related to Cardiac Catheterization in Children and Young Adults With Pulmonary Hypertension: An Analysis of Data From the IMPACT (Improving Adult and Congenital Treatment) Registry.

BACKGROUND: Cardiac catheterization is the gold standard for assessment and follow-up of patients with pulmonary hypertension (PH). To date, there are limited data about the factors that influence the risk of catastrophic adverse events after catheterization in this population. METHODS AND RESULTS: A retrospective multicenter cohort study was performed to measure risk of catastrophic adverse outcomes after catheterization in children and young adults with PH and identify risk factors for these outcomes. All catheterizations in children and young adults, aged 0 to 21 years, with PH at hospitals submitting data to the IMPACT (Improving Adult and Congenital Treatment) registry between January 1, 2011, and December 31, 2015, were studied. Using mixed-effects multivariable regression, we assessed the association between prespecified subject-, procedure-, and center-level covariates and the risk of death, cardiac arrest, or mechanical circulatory support during or after cardiac catheterization. A total of 8111 procedures performed in 7729 subjects at 77 centers were studied. The observed risk of the composite outcome was 1.4%, and the risk of death before discharge was 5.2%. Catheterization in prematurely born neonates and nonpremature infants was associated with increased risk of catastrophic adverse event, as was precatheterization treatment with inotropes and lower systemic arterial saturation. Secondary analyses demonstrated the following: (1) increasing volumes of catheterization in patients with PH were associated with reduced risk of composite outcome (odds ratio, 0.8 per 10 procedures; CONCLUSIONS: Young patients with PH are a high-risk population for diagnostic and interventional cardiac catheterization. Hospital experience with PH is associated with reduced risk, independent of total catheterization case volume

Quantitative cardiac magnetic resonance T2 imaging offers ability to non-invasively predict acute allograft rejection in children

BACKGROUND: Monitoring for acute allograft rejection improves outcomes after cardiac transplantation. Endomyocardial biopsy is the gold standard test defining rejection, but carries risk and has limitations. Cardiac magnetic resonance T2 mapping may be able to predict rejection in adults, but has not been studied in children. Our aim was to evaluate T2 mapping in identifying paediatric cardiac transplant patients with acute rejection. METHODS: Eleven paediatric transplant patients presenting 18 times were prospectively enrolled for non-contrast cardiac magnetic resonance at 1.5 T followed by endomyocardial biopsy. Imaging included volumetry, flow, and T2 mapping. Regions of interest were manually selected on the T2 maps using the middle-third technique in the left ventricular septal and lateral wall in a short-axis and four-chamber slice. Mean and maximum T2 values were compared with Student\u27s t-tests analysis. RESULTS: Five cases of acute rejection were identified in three patients, including two cases of grade 2R on biopsy and three cases of negative biopsy treated for clinical symptoms attributed to rejection (new arrhythmia, decreased exercise capacity). A monotonic trend between increasing T2 values and higher biopsy grades was observed: grade 0R T2 53.4 ± 3 ms, grade 1R T2 54.5 ms ± 3 ms, grade 2R T2 61.3 ± 1 ms. The five rejection cases had significantly higher mean T2 values compared to cases without rejection (58.3 ± 4 ms versus 53 ± 2 ms, p = 0.001). CONCLUSIONS: Cardiac magnetic resonance with quantitative T2 mapping may offer a non-invasive method for screening paediatric cardiac transplant patients for acute allograft rejection. More data are needed to understand the relationship between T2 and rejection in children

Radiation-free CMR diagnostic heart catheterization in children.

BACKGROUND: Children with heart disease may require repeated X-Ray cardiac catheterization procedures, are more radiosensitive, and more likely to survive to experience oncologic risks of medical radiation. Cardiovascular magnetic resonance (CMR) is radiation-free and offers information about structure, function, and perfusion but not hemodynamics. We intend to perform complete radiation-free diagnostic right heart catheterization entirely using CMR fluoroscopy guidance in an unselected cohort of pediatric patients; we report the feasibility and safety. METHODS: We performed 50 CMR fluoroscopy guided comprehensive transfemoral right heart catheterizations in 39 pediatric (12.7 ± 4.7 years) subjects referred for clinically indicated cardiac catheterization. CMR guided catheterizations were assessed by completion (success/failure), procedure time, and safety events (catheterization, anesthesia). Pre and post CMR body temperature was recorded. Concurrent invasive hemodynamic and diagnostic CMR data were collected. RESULTS: During a twenty-two month period (3/2015 - 12/2016), enrolled subjects had the following clinical indications: post-heart transplant 33%, shunt 28%, pulmonary hypertension 18%, cardiomyopathy 15%, valvular heart disease 3%, and other 3%. Radiation-free CMR guided right heart catheterization attempts were all successful using passive catheters. In two subjects with septal defects, right and left heart catheterization were performed. There were no complications. One subject had six such procedures. Most subjects (51%) had undergone multiple (5.5 ± 5) previous X-Ray cardiac catheterizations. Retained thoracic surgical or transcatheter implants (36%) did not preclude successful CMR fluoroscopy heart catheterization. During the procedure, two subjects were receiving vasopressor infusions at baseline because of poor cardiac function, and in ten procedures, multiple hemodynamic conditions were tested. CONCLUSIONS: Comprehensive CMR fluoroscopy guided right heart catheterization was feasible and safe in this small cohort of pediatric subjects. This includes subjects with previous metallic implants, those requiring continuous vasopressor medication infusions, and those requiring pharmacologic provocation. Children requiring multiple, serial X-Ray cardiac catheterizations may benefit most from radiation sparing. This is a step toward wholly CMR guided diagnostic (right and left heart) cardiac catheterization and future CMR guided cardiac intervention. TRIAL REGISTRATION: ClinicalTrials.gov NCT02739087 registered February 17, 2016

Language of Lullabies: The Russification and De-Russification of the Baltic States

This article argues that the laws for promotion of the national languages are a legitimate means for the Baltic states to establish their cultural independence from Russia and the former Soviet Union

Model -based control of nonlinear processes

Model-based control of continuous-time, multivariable, nonlinear processes with input constraints and time delays is studied. Differential geometric control laws are derived for stable processes, whether their delay-free part is minimum- or non-minimum-phase. They are obtained by requesting an approximately linear, input-output response and exploiting the connections between model-predictive control and input-output linearization. Conditions under which the closed-loop system is asymptotically stable are given. The control laws ensure asymptotic tracking of the measured output in the presence of constant model errors and disturbances as long as nominal, closed-loop, asymptotic stability is preserved. There are no limitations on the order, relative order, or number of unstable modes of the zero dynamics of the processes to which the control laws are applicable. To derive control laws that can perform optimally in the presence of input constraints, the connections between model-predictive control and input-output linearization are exploited. The continuous-time control laws are solutions of constrained optimization problems that are solved on-line. They minimize the error between controlled outputs and their reference trajectories, subject to the input constraints. In the absence of input constraints the control laws do not induce a linear, closed-loop, output response when process zero dynamics are unstable. The nonlinearity of the resulting process output response is the price of ensuring closed-loop stability for non-minimum-phase processes. The application and performance of the control laws are illustrated using numerical simulation of several chemical reactors that exhibit non-minimum-phase behavior. The control laws are also implemented in real-time on a pilot-scale, liquid-level process with non-minimum-phase behavior. Real-time implementation issues, and advantages and disadvantages of the control laws are discussed

Model -based control of nonlinear processes

Model-based control of continuous-time, multivariable, nonlinear processes with input constraints and time delays is studied. Differential geometric control laws are derived for stable processes, whether their delay-free part is minimum- or non-minimum-phase. They are obtained by requesting an approximately linear, input-output response and exploiting the connections between model-predictive control and input-output linearization. Conditions under which the closed-loop system is asymptotically stable are given. The control laws ensure asymptotic tracking of the measured output in the presence of constant model errors and disturbances as long as nominal, closed-loop, asymptotic stability is preserved. There are no limitations on the order, relative order, or number of unstable modes of the zero dynamics of the processes to which the control laws are applicable. To derive control laws that can perform optimally in the presence of input constraints, the connections between model-predictive control and input-output linearization are exploited. The continuous-time control laws are solutions of constrained optimization problems that are solved on-line. They minimize the error between controlled outputs and their reference trajectories, subject to the input constraints. In the absence of input constraints the control laws do not induce a linear, closed-loop, output response when process zero dynamics are unstable. The nonlinearity of the resulting process output response is the price of ensuring closed-loop stability for non-minimum-phase processes. The application and performance of the control laws are illustrated using numerical simulation of several chemical reactors that exhibit non-minimum-phase behavior. The control laws are also implemented in real-time on a pilot-scale, liquid-level process with non-minimum-phase behavior. Real-time implementation issues, and advantages and disadvantages of the control laws are discussed

Surgical Retrieval of an Embolized Patent Ductus Arteriosus Closure Device in an Infant Weighing 1050 G

UNLABELLED: The dislodgement of device during transcatheter procedure is a rare complication and the device can be retrieved by transcatheter techniques in most cases. In case of failed attempts, the surgery may be required and in haemodynamically unstable patients cardiopulmonary bypass may be unavoidable. A case of surgical retrieving of patent ductus arteriosus occlusion device from the right pulmonary artery in a 1050 g baby on CPB was presented. In literature CPB use in babies weighing under 1 kg has been rarely reported. CPB support was performed securely in our case who is one of the tiniest patients operated on. CPB can be safe enough in surgical approach of a complication of very low birth weight patient. CLINICAL REGISTRATION NUMBER/DATE/REGISTRY: Pro00015566-07/01/2021-Children\u27s National Medical Center