Electrocardiographic predictors of left ventricular hypertrophy in pediatric hypertension

Objective: To determine the efficacy of electrocardiography (ECG) in detecting left ventricular hypertrophy (LVH) in pediatric hypertension (HT). Study design: Concomitant echocardiograms and electrocardiograms in 108 children with HT were reviewed. Left ventricular mass (LVM), assessed by echocardiography, was used as a basis for a diagnosis of LVH (echo LVH) using accepted pediatric criteria. Using Wilcoxon’s rank-sum test, 14 ECG variables were compared between subjects with and without echo LVH. Spearman correlations were used to examine the linear association between echo LVH and these ECG variables. The sensitivity and specificity of ECG in diagnosing LVH were computed. Results: Of the 108 subjects studied, 35 (32%) met the pediatric criteria for LVH; of these, 8 (7.4%) also met the adult criteria (>51 g/m 2.7) for LVH. Mean values for only 5 ECG criteria differed significantly among the groups: RI, SaVR, RaVL, RI SIII, and SVI RV6 (P<.05). Significant correlations were found for several ECG criteria and at least 1 measure of LVM, but the magnitudes were modest. Standard ECG criteria predicted LVH with high specificity (>90%) but low sensitivity (<35%). RI>10 mm was identified as demonstrating a modestly improved positive likelihood ratio of 3. Conclusions: ECG is not an adequate predictor of LVH for clinical use in HT

Experiments and modelling of two-phase transient flow during pipeline depressurization of CO2 with various N2 compositions

Pressure-release experiments of CO2 with impurity contents of 10, 20 and 30 mol% nitrogen have been executed. The experimental investigations were performed in a 140 m long horizontal tube with an inner diameter of 10 mm. The initial conditions of the CO2-N2 mixtures were in the supercritical region at approximately 120 bar and 20 °C. The results, which showed a good repeatability, were then compared with numerical data from a homogeneous equilibrium model. The investigations have concentrated on the pressure wave at the start as well as the pressure and temperature development during the pressure release. The model, which has a certain complexity, but still contains several simplifications, gave relatively good results for all three gas mixtures. Although the absolute values for the temperature development showed to be consistently higher in the experimental results compared to the numerical results, the liquid dry-out points were predicted with good accuracy at all measurement points. The numerical results of the pressure development match the experimental results very well, both regarding the absolute and relative values. Regarding the speed of the pressure wave, the numerical results were consistently too high, which is believed to be caused by the EOS overpredicting the speed of sound for our cases. The good results, especially for the pressure, are promising, and further work is suggested to improve the model

CO2pipehaz : quantitative hazard assessment for next generation CO2 pipelines

International audienceThis paper presents an overview of the recently commenced CO(2)PipeHaz project focused on the hazard assessment of CO2 pipelines to be employed as an integral part of the Carbon Capture and Storage (CCS) chain. Funded by the European Commission FP7 Energy programme, the project's objective is to address the fundamentally important and urgent issue regarding the accurate predictions of fluid phase, discharge rate and subsequent atmospheric dispersion during accidental releases from pressurised CO2 pipelines. This information is pivotal to quantifying all the hazard consequences associated with failure of CO2 transportation pipelines forming the basis for emergency response planning and determining minimum safe distances to populated areas. The developments of the state of the art multi-phase heterogeneous discharge and dispersion models for predicting the correct fluid phase during the discharge process will be given special consideration given the very different hazard profiles of CO2 in the gas and solid states. Model validations are based on both small scale controlled laboratory conditions as well as large scale field trials using a unique CCS facility in China, the world's largest CO2 emitter. A cost/benefit analysis will be performed to determine the optimum level of impurities in the captured CO2 stream based on safety and economic considerations. The project will embody the understanding gained within safety and risk assessment tools that can be used for evaluating the adequacy of controls in CO2 pipelines, with best practice guidelines also being developed

CO(2)QUEST : Techno-economic assessment of CO2 quality effect on its storage and transport

Presented is an overview of the CO(2)QUEST project that addresses fundamentally important issues regarding the impact of typical impurities in the gas or dense phase CO2 stream captured from fossil fuel power plants on its safe and economic transportation and storage. Previous studies have mainly investigated the impact of CO2 stream impurities on each part of the carbon capture and storage (CCS) chain in isolation. This is a significant drawback given the different sensitivities of pipeline, wellbore materials and storage sites to the various impurities. The project brings together leading researchers and stakeholders, to address the impact of the typical impurities upon safe and economic CO2 transportation and storage. State-of-the-art mathematical models, backed by laboratory and industrial-scale experimentation, are implemented to perform a comprehensive techno-economic assessment of the impact of impurities upon the thermo-physical phenomena governing pipeline and storage-site integrities