Vortex formation and instability in the left ventricle

We study the formation of the mitral vortex ring during early diastolic filling in a patient-specific left ventricle (LV) using direct numerical simulation. The geometry of the left ventricle is reconstructed from Magnetic Resonance Imaging (MRI) data of a healthy human subject. The left ventricular kinematics is modeled via a cell-based activation methodology, which is inspired by cardiac electro-physiology and yields physiologic LV wall motion. In the fluid dynamics videos, we describe in detail the three-dimensional structure of the mitral vortex ring, which is formed during early diastolic filling. The ring starts to deform as it propagates toward the apex of the heart and becomes inclined. The trailing secondary vortex tubes are formed as the result of interaction between the vortex ring and the LV wall. These vortex tubes wrap around the circumference and begin to interact with and destabilize the mitral vortex ring. At the end of diastole, the vortex ring impinges on the LV wall and the large-scale intraventricular flow rotates in clockwise direction. We show for the first time that the mitral vortex ring evolution is dominated by a number of vortex-vortex and vortex-wall interactions, including lateral straining and deformation of vortex ring, the interaction of two vortex tubes with unequal strengths, helicity polarization of vortex tubes and twisting instabilities of the vortex cores

Scalable natural user interfaces for data-intensive exploratory visualization: designing in the context of big data

University of Minnesota Ph.D. dissertation. July 2013. Major: Computer Science. Advisor: Daniel F. Keefe. 1 computer file (PDF) x, 195 pages.This dissertation investigates new exploratory visualization tools in data-intensive domains that are built upon natural user interface technology, including multi-touch surfaces and virtual reality. Scalable interactions are developed and evaluated in several software systems that are targeted toward supporting design workflows that make use of big data. A new immersive and highly-interactive multi-touch workbench is presented, along with a theoretical framework and evaluation of how visualizations may be developed on it. Building upon this foundation, two different exploratory visualization software systems are presented that address distinct challenges faced by designers working in data-intensive domains. The first of these systems is called Slice World-In-Miniature (WIM), which is designed to overcome the difficulty associated with exploring large-volume data, where the complexity of the data often leads to the designers becoming disoriented. Using Overview+Detail techniques to provide context, the designer navigates inside of complex volumes using multi-touch gestures. This Slice WIM system is applied to a number of medical device design applications and evaluated by domain experts in this field. The second system is called Design by Dragging, which addresses the information overload associated with comparing and navigating many sets of interelated simulations. Design by Dragging gives the designer the power to explore high-dimensional simulation design spaces by using natural direct manipulation interactions. This system is applied to several problems in medical device design and in visual effects simulation, and a domain expert evaluation is presented. The big data paradigm is integrally tied to the future of computing. The major contribution of this dissertation is its investigation into the effectiveness of natural user interfaces as a means of working in this paradigm. Although natural user interfaces have become ubiquitous in our daily lives, they are typically used only for simple interactions. This dissertation demonstrates that these technologies can also be effective in aiding design work in the context of big data, a result that could shape the future of computing and change the way designers work with computers

The East Asian Journal of British History, vol. 3

The East Asian Journal of British History is produced by the East Asian Society of British History, and supported by the Institute for Historical Research. The Institute of Historical Research is pleased and proud to be supporting this recent addition to British history scholarship. Developing out of the IHR’s long-standing collaborative partnership with Japanese universities, and now in its fourth year, the East Asian Journal of British History features some of the best emergent scholarship from Anglophone historians working in China, Japan, and South Korea. Divided between an articles section and one devoted to reviews, the journal’s remit wide-ranging covering all fields and periods of British history. It complements the triennial Anglo-Japanese Conference organised by the IHR and Japanese historians based at the universities of Tokyo, Kyoto and Osaka, and the conference of the East Asian Society of British history, in which we are joined by our colleagues from South Korea. In future, we hope that more contributions will be featured in the journal from the Chinese mainland and from Taiwan

Corporate philanthropy through the lens of ethical subjectivity

The dynamic organisational processes in businesses dilute the boundaries between the individual, organisational, and societal drivers of corporate philanthropy. This creates a complex framework in which charitable project selection occurs. Using the example of European tour operators, this study investigates the mechanisms through which companies invest in charitable projects in overseas destinations. Inextricably linked to this is the increasing contestation by local communities as to how they are able to engage effectively with tourism in order to realise the benefits tourism development can bring. This research furthers such debates by exploring the processes through which tour operators facilitate community development through charitable giving. Findings show, with no formal frameworks in existence, project selection depends upon emergent strategies that connect the professional with the personal, with trust being positioned as a central driver of these informal processes. Discretionary responsibilities are reworked through business leaders’ commitment to responsible business practises and the ethical subjectivity guiding these processes

BioWIM: A MultiSurface, MultiTouch Interface for Exploratory Visualization of Biomedical Data

This paper presents the BioWIM, a multi-surface, multi-touch interface for exploring visualizations of complex biomedical environments using a semi-immersive virtual reality (VR) display. The BioWIM reinterprets the traditional world-in-miniature (WIM) VR metaphor within the context of navigating visualizations based on medical imaging data and using the unique capabilities provided by coupling a multi-touch table with a stereoscopic display wall. A "Window to the World" metaphor is used to navigate a detailed 3D scene displayed on the vertical surface by manipulating widgets and making touch gestures on top of medical imaging data displayed on the table. The technique supports navigation through complex environments while maintaining context. The results of a controlled user study comparing the BioWIM to a more traditional touch interface demonstrate improvements in accuracy in a compound search and size judgment task when using the BioWIM. An interpretation of these results and discussion of design principles and lessons learned is presented