The role of Cardiac Magnetic Resonance (CMR) in the diagnosis of cardiomyopathy: A systematic review

BackgroundMyocardial pathologies are significant causes of morbidity and mortality in patients worldwide. Ischemic and non-ischemic cardiomyopathies have become a worldwide epidemic of the 21st century with an increasing impact on health care systems. The 2012 European Society of Cardiology and 2013 American College of Cardiology Foundation/American Heart Association guidelines provide current therapy guidance to reduce mortality and morbidity.MethodsThis was a systematic review involving cardiac magnetic resonance (CMR) studies for the diagnosis of cardiomyopathy from January 2013 to April 2017. Out of 62 reviewed studies, only 12 were included in our study.ResultsThe average sensitivity and specificity of CMR in the diagnosis of cardiomyopathy was 86.75% (95% confidence interval [CI], 70.30% to 92.58%) and 81.75% (95% CI, 73.0% to 87.6%), respectively, and the positive predictive and negative predictive values were 80.17% and 86.75%, respectively.ConclusionDespite some limitations, our study shows that CMR has high sensitivity, specificity, and positive predictive value in diagnosing different types of cardiomyopathy. CMR may be used to differentiate types of cardiomyopathy, accurately quantify the chamber dimensions, volumes, and cardiac function, which make it useful for prognosis as well

Accurate gradient computations at interfaces using finite element methods

New finite element methods are proposed for elliptic interface problems in one and two dimensions. The main motivation is not only to get an accurate solution but also an accurate first order derivative at the interface (from each side). The key in 1D is to use the idea from \cite{wheeler1974galerkin}. For 2D interface problems, the idea is to introduce a small tube near the interface and introduce the gradient as part of unknowns, which is similar to a mixed finite element method, except only at the interface. Thus the computational cost is just slightly higher than the standard finite element method. We present rigorous one dimensional analysis, which show second order convergence order for both of the solution and the gradient in 1D. For two dimensional problems, we present numerical results and observe second order convergence for the solution, and super-convergence for the gradient at the interface

Performance Prediction of Underwater Acoustic Communications Based on Channel Impulse Responses

Featured Application: Convolutional neural networks are used on the channel impulse response data to predict the performance of underwater acoustic communications. Abstract: Predicting the channel quality for an underwater acoustic communication link is not a straightforward task. Previous approaches have focused on either physical observations of weather or engineered signal features, some of which require substantial processing to obtain. This work applies a convolutional neural network to the channel impulse responses, allowing the network to learn the features that are useful in predicting the channel quality. Results obtained are comparable or better than conventional supervised learning models, depending on the dataset. The universality of the learned features is also demonstrated by strong prediction performance when transferring from a more complex underwater acoustic channel to a simpler one

Simulation of wave propagation in plate structures by using new spectral element with piezoelectric coupling

This paper presents an efficient approach to simulate Lamb wave propagations in thin plate structures by using new time domain spectral plate elements. A novel approach is proposed to incorporate the coupling of piezoelectric transducers within the two-dimensional plate element. The diagonal mass matrix is obtained by using a simple method with less computational effort. Detailed formulations are given. The benchmark problem of a thin aluminum plate with two surface-mounted piezoelectric transducers was investigated in detail. Comparisons are made with results obtained by using ABAQUS to verify the developed spectral plate element. It is shown that the proposed element can efficiently simulate the propagation of Lamb wave generated by a piezoelectric actuator and picked up by a piezoelectric sensor

Multicell Edge Coverage Enhancement Using Mobile UAV-Relay

Unmanned aerial vehicle (UAV)-assisted communication is a promising technology in future wireless communication networks. UAVs can not only help offload data traffic from ground base stations (GBSs) but also improve the Quality of Service (QoS) of cell-edge users (CEUs). In this article, we consider the enhancement of cell-edge communications through a mobile relay, i.e., UAV, in multicell networks. During each transmission period, GBSs first send data to the UAV, and then the UAV forwards its received data to CEUs according to a certain association strategy. In order to maximize the sum rate of all CEUs, we jointly optimize the UAV mobility management, including trajectory, velocity, and acceleration, and association strategy of CEUs to the UAV, subject to minimum rate requirements of CEUs, mobility constraints of the UAV, and causal buffer constraints in practice. To address the mixed-integer nonconvex problem, we transform it into two convex subproblems by applying tight bounds and relaxations. An iterative algorithm is proposed to solve the two subproblems in an alternating manner. Numerical results show that the proposed algorithm achieves higher rates of CEUs as compared with the existing benchmark schemes