Noncommutative Topological Theories of Gravity

The possibility of noncommutative topological gravity arising in the same manner as Yang-Mills theory is explored. We use the Seiberg-Witten map to construct such a theory based on a SL(2,C) complex connection, from which the Euler characteristic and the signature invariant are obtained. This gives us a way towards the description of noncommutative gravitational instantons as well as noncommutative local gravitational anomalies.Comment: 17+1 pages, LaTeX, no figures, some clarifications, comments and references added, style improve

Combining Asian and European genome-wide association studies of colorectal cancer improves risk prediction across racial and ethnic populations

Polygenic risk scores (PRS) have great potential to guide precision colorectal cancer (CRC) prevention by identifying those at higher risk to undertake targeted screening. However, current PRS using European ancestry data have sub-optimal performance in non-European ancestry populations, limiting their utility among these populations. Towards addressing this deficiency, we expand PRS development for CRC by incorporating Asian ancestry data (21,731 cases; 47,444 controls) into European ancestry training datasets (78,473 cases; 107,143 controls). The AUC estimates (95% CI) of PRS are 0.63(0.62-0.64), 0.59(0.57-0.61), 0.62(0.60-0.63), and 0.65(0.63-0.66) in independent datasets including 1681-3651 cases and 8696-115,105 controls of Asian, Black/African American, Latinx/Hispanic, and non-Hispanic White, respectively. They are significantly better than the European-centric PRS in all four major US racial and ethnic groups (p-values < 0.05). Further inclusion of non-European ancestry populations, especially Black/African American and Latinx/Hispanic, is needed to improve the risk prediction and enhance equity in applying PRS in clinical practice

Evaluating ITER remote handling middleware concepts

Remote maintenance activities in ITER will be performed by a unique set of hardware systems, supported by an extensive software kit. A layer of middleware will manage and control a complex set of interconnections between teams of operators, hardware devices in various operating theatres, and databases managing tool and task logistics. The middleware is driven by constraints on amounts and timing of data like real-time control loops, camera images, and database access. The Remote Handling Study Centre (RHSC), located at FOM institute DIFFER, has a 4-operator work cell in an ITER relevant RH Control Room setup which connects to a virtual hot cell back-end. The centre is developing and testing flexible integration of the Control Room components, resulting in proof-of-concept tests of this middleware layer. SW components studied include generic human-machine interface software, a prototype of a RH operations management system, and a distributed virtual reality system supporting multi-screen, multi-actor, and multiple independent views. Real-time rigid body dynamics and contact interaction simulation software supports simulation of structural deformation, “augmented reality” operations and operator training. The paper presents generic requirements and conceptual design of middleware components and Operations Management System in the context of a RH Control Room work cell. The simulation software is analyzed for real-time performance and it is argued that it is critical for middleware to have complete control over the physical network to be able to guarantee bandwidth and latency to the components

An approach to tiltrotor wing aeroservoelastic optimization through increased productivity

Presented at the 4th AIAA/NASA/USAF/ISSMO Symposium on Multidisciplinary Analysis and Optimization, Cleveland, OH, September 21-23, 1992.The paper describes one way to approach the multidisciplinary task of optimizing a tiltrotor wing structure which is equipped with an active flutter suppression system. Objective function is a productivity index, as a measure for aircraft cost-effectiveness. Short digress is held on the characteristics of the tiltrotor's dynamic system and its aeroelastic behavior. Contributing analyses (CA's) for calculating aircraft performance, modeling the dynamic system, and designing an active flutter suppression control system are selected. Multilevel and non-hierarchic decomposition techniques are discussed. A file structure for handling data transfer between the CA's and the optimizer is presented. Preliminary results are shown which highlight some peculiarities of this optimization problem

Heart valve function: a biomechanical perspective

Heart valves (HVs) are cardiac structures whose physiological function is to ensure directed blood flow through the heart over the cardiac cycle. While primarily passive structures that are driven by forces exerted by the surrounding blood and heart, this description does not adequately describe their elegant and complex biomechanical function. Moreover, they must replicate their cyclic function over an entire lifetime, with an estimated total functional demand of least 3×109 cycles. As in many physiological systems, one can approach HV biomechanics from a multi-length-scale approach, since mechanical stimuli occur and have biological impact at the organ, tissue and cellular scales. The present review focuses on the functional biomechanics of HVs. Specifically, we refer to the unique aspects of valvular function, and how the mechanical and mechanobiological behaviours of the constituent biological materials (e.g. extracellular matrix proteins and cells) achieve this remarkable feat. While we focus on the work from the authors' respective laboratories, the works of most investigators known to the authors have been included whenever appropriate. We conclude with a summary and underscore important future trends