Full-wave EMC Simulations Using Maxwell Garnett Model For Composites With Cylindrical Inclusions

Four different models for effective dielectric properties of biphasic composite containing random or aligned cylindrical inclusions are considered in this paper. These models are based on the Maxwell Garnett (MG) mixing rule. The effects of distribution and orientation of cylindrical inclusions in a composite material is studied. An equivalent averaged material with Debye-like frequency characteristics, suitable for time-domain full-wave numerical electromagnetic simulations is retrieved. This Debye model is derived from the Maxwell Garnett formulation. The numerical model test structure consists of a composite slab inserted in a rectangular waveguide. Simulations are run for the frequency range above the cut-off frequency of the fundamental mode TE10. The differences between the proposed models are quantified using the Feature Selection Validation (FSV) tool. The comparison of the models provides an insight on the effect of inclusion orientation and distribution. © 2011 IEEE

Successful management of multiple permanent pacemaker complications – infection, 13 year old silent lead perforation and exteriorisation following failed percutaneous extraction, superior vena cava obstruction, tricuspid valve endocarditis, pulmonary embolism and prosthetic tricuspid valve thrombosis

A 59 year old man underwent mechanical tricuspid valve replacement and removal of pacemaker generator along with 4 pacemaker leads for pacemaker endocarditis and superior vena cava obstruction after an earlier percutaneous extraction had to be abandoned, 13 years ago, due to cardiac arrest, accompanied by silent, unsuspected right atrial perforation and exteriorisation of lead. Postoperative course was complicated by tricuspid valve thrombosis and secondary pulmonary embolism requiring TPA thrombolysis which was instantly successful. A review of literature of pacemaker endocarditis and tricuspid thrombosis along with the relevant management strategies is presented. We believe this case report is unusual on account of non operative management of right atrial lead perforation following an unsuccessful attempt at percutaneous removal of right sided infected pacemaker leads and the incidental discovery of the perforated lead 13 years later at sternotomy, presentation of pacemaker endocarditis with a massive load of vegetations along the entire pacemaker lead tract in superior vena cava, right atrial endocardium, tricuspid valve and right ventricular endocardium, leading to a functional and structural SVC obstruction, requirement of an unusually large dose of warfarin postoperatively occasioned, in all probability, by antibiotic drug interactions, presentation of tricuspid prosthetic valve thrombosis uniquely as vasovagal syncope and isolated hypoxia and near instantaneous resolution of tricuspid prosthetic valve thrombosis with Alteplase thrombolysis

Plasma Chemokine Levels Are Associated with the Presence and Extent of Angiographic Coronary Collaterals in Chronic Ischemic Heart Disease

In patients with chronic ischemic heart disease (IHD), the presence and extent of spontaneously visible coronary collaterals are powerful determinants of clinical outcome. There is marked heterogeneity in the recruitment of coronary collaterals amongst patients with similar degrees of coronary artery stenoses, but the biological basis of this heterogeneity is not known. Chemokines are potent mediators of vascular remodeling in diverse biological settings. Their role in coronary collateralization has not been investigated. We sought to determine whether plasma levels of angiogenic and angiostatic chemokines are associated with of the presence and extent of coronary collaterals in patients with chronic IHD.We measured plasma concentrations of angiogenic and angiostatic chemokine ligands in 156 consecutive subjects undergoing coronary angiography with at least one ≥90% coronary stenosis and determined the presence and extent of spontaneously visible coronary collaterals using the Rentrop scoring system. Eighty-eight subjects (56%) had evidence of coronary collaterals. In a multivariable regression model, the concentration of the angiogenic ligands CXCL5, CXCL8 and CXCL12, hyperlipidemia, and an occluded artery were associated with the presence of collaterals; conversely, the concentration of the angiostatic ligand CXCL11, interferon-γ, hypertension and diabetes were associated with the absence of collaterals (ROC area 0.91). When analyzed according to extent of collateralization, higher Rentrop scores were significantly associated with increased concentration of the angiogenic ligand CXCL1 (p<0.0001), and decreased concentrations of angiostatic ligands CXCL9 (p<0.0001), CXCL10 (p = 0.002), and CXCL11 (p = 0.0002), and interferon-γ (p = 0.0004).Plasma chemokine concentrations are associated with the presence and extent of spontaneously visible coronary artery collaterals and may be mechanistically involved in their recruitment

General regression neural network approach to prediction of electric field level in the reverberation chamber

This study presents an approach for the prediction of electric field level which depends on the positions of stirrer and frequency in the mode stirred reverberation chamber. A general regression neural network (GRNN) is used for prediction process. In order to show the system performance, feature selective validation (FSV) technique is given. The simulation results show that the predicted values of electrical field have been obtained with high accuracy. Thus, this technique will facilitate estimation of electric field level in the reverberation chamber which is component of especially mode stirrer reverberation chamber test method

Can thrombolytic therapy provide beneficial effects additional to epicardial coronary artery recanalization? A study based on coronary pressure measurement

Background Collaterals provide significant blood supply to the myocardium at risk and the presence of a preserved and adequate collateral network may limit microvascular damage during the occlusion of an epicardial coronary artery. The aim of this study was to evaluate whether thrombolytic therapy (TT) may produce beneficial effects at the level of microvascular circulation in addition to epicardial coronary artery recanalization by using quantitative intracoronary pressure measurement techniques in patients with recent acute myocardial infarction (AMI)