Anisotropy Across Fields and Scales

This open access book focuses on processing, modeling, and visualization of anisotropy information, which are often addressed by employing sophisticated mathematical constructs such as tensors and other higher-order descriptors. It also discusses adaptations of such constructs to problems encountered in seemingly dissimilar areas of medical imaging, physical sciences, and engineering. Featuring original research contributions as well as insightful reviews for scientists interested in handling anisotropy information, it covers topics such as pertinent geometric and algebraic properties of tensors and tensor fields, challenges faced in processing and visualizing different types of data, statistical techniques for data processing, and specific applications like mapping white-matter fiber tracts in the brain. The book helps readers grasp the current challenges in the field and provides information on the techniques devised to address them. Further, it facilitates the transfer of knowledge between different disciplines in order to advance the research frontiers in these areas. This multidisciplinary book presents, in part, the outcomes of the seventh in a series of Dagstuhl seminars devoted to visualization and processing of tensor fields and higher-order descriptors, which was held in Dagstuhl, Germany, on October 28–November 2, 2018

Echocardiography

The book "Echocardiography - New Techniques" brings worldwide contributions from highly acclaimed clinical and imaging science investigators, and representatives from academic medical centers. Each chapter is designed and written to be accessible to those with a basic knowledge of echocardiography. Additionally, the chapters are meant to be stimulating and educational to the experts and investigators in the field of echocardiography. This book is aimed primarily at cardiology fellows on their basic echocardiography rotation, fellows in general internal medicine, radiology and emergency medicine, and experts in the arena of echocardiography. Over the last few decades, the rate of technological advancements has developed dramatically, resulting in new techniques and improved echocardiographic imaging. The authors of this book focused on presenting the most advanced techniques useful in today's research and in daily clinical practice. These advanced techniques are utilized in the detection of different cardiac pathologies in patients, in contributing to their clinical decision, as well as follow-up and outcome predictions. In addition to the advanced techniques covered, this book expounds upon several special pathologies with respect to the functions of echocardiography

The Formation and Dynamics of Clouds in the Environment of Active Galactic Nuclei

Active galactic nuclei (AGN) are among the most luminous objects in the universe and are known to be powered by accretion onto supermassive black holes in the centers of galaxies. AGN clouds are prominent components of successful models that attempt to unify the diversity of AGN. These clouds are often hypothesized to be the source of the broad and narrow line emission features seen in AGN spectra. Moreover, the high column densities of gas needed to account for broad absorption lines has been attributed to the same population of clouds, while the motion of AGN clouds has been invoked to explain the spectral variability observed in both broad absorption lines and warm absorbers. Despite the importance of AGN clouds for explaining phenomena associated with AGN, we still lack a comprehensive understanding of the origin, dynamics, lifetime, and properties of these clouds. This thesis is an attempt to lay the groundwork for such a comprehensive model. After summarizing the known physics of AGN clouds and our modeling framework (i.e. the equations of hydrodynamics), we review the linear theory of the thermal instability (TI), which provides a natural mechanism to form clouds. We then extend this theory of cloud formation to account for the role of cloud acceleration, which must accompany the nonlinear regime of TI. After presenting hydrodynamical simulations that demonstrate how cloud formation and acceleration are intertwined processes, we explore how the efficiency of cloud acceleration is affected by the inclusion of flux variability. We find that the acceleration can more than double when the period of flux oscillations is longer than the thermal timescale of the gas. Next we calculate synthetic absorption line profiles to determine how clouds evolving along the line of sight would appear to a distant observer. We identify a spectral signature for cloud acceleration in the case of absorption line doublets. Finally, we show how global hydrodynamical simulations can be used to make predictions for the observables obtainable from reverberation mapping campaigns. We conclude with a summary of our findings and the next steps needed to further develop a comprehensive model of AGN clouds