549 research outputs found
Fault tolerance for holonomic quantum computation
We review an approach to fault-tolerant holonomic quantum computation on
stabilizer codes. We explain its workings as based on adiabatic dragging of the
subsystem containing the logical information around suitable loops along which
the information remains protected.Comment: 16 pages, this is a chapter in the book "Quantum Error Correction",
edited by Daniel A. Lidar and Todd A. Brun, (Cambridge University Press,
2013), at
http://www.cambridge.org/us/academic/subjects/physics/quantum-physics-quantum-information-and-quantum-computation/quantum-error-correctio
Bi-temporal 3D active appearance models with applications to unsupervised ejection fraction estimation
Rapid and unsupervised quantitative analysis is of utmost importance to ensure clinical acceptance of many examinations using cardiac magnetic resonance imaging (MRI). We present a framework that aims at fulfilling these goals for the application of left ventricular ejection fraction estimation in four-dimensional MRI. The theoretical foundation of our work is the generative two-dimensional Active Appearance Models by Cootes et al., here extended to bi-temporal, three-dimensional models. Further issues treated include correction of respiratory induced slice displacements, systole detection, and a texture model pruning strategy. Cross-validation carried out on clinical-quality scans of twelve volunteers indicates that ejection fraction and cardiac blood pool volumes can be estimated automatically and rapidly with accuracy on par with typical inter-observer variability. \u
A system for advanced facial animation
Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1996.Includes bibliographical references (leaves 35-36).by Kenneth D. Miller, III.M.Eng
Object recognition in infrared imagery using appearance-based methods
Abstract unavailable please refer to PD
Handshape recognition using principal component analysis and convolutional neural networks applied to sign language
Handshape recognition is an important problem in computer vision with significant societal impact. However, it is not an easy task, since hands are naturally deformable objects. Handshape recognition contains open problems, such as low accuracy or low speed, and despite a large number of proposed approaches, no solution has been found to solve these open problems. In this thesis, a new image dataset for Irish Sign Language (ISL) recognition is introduced. A deeper study using only 2D images is presented on Principal Component Analysis (PCA) in two stages. A comparison between approaches that do not need features (known as end-to-end) and feature-based approaches is carried out.
The dataset was collected by filming six human subjects performing ISL handshapes and movements. Frames from the videos were extracted. Afterwards the redundant images were filtered with an iterative image selection process that selects the images which keep the dataset
diverse.
The accuracy of PCA can be improved using blurred images and interpolation. Interpolation is only feasible with a small number of points. For this reason two-stage PCA is proposed. In other words, PCA is applied to another PCA space. This makes the interpolation possible and improves the accuracy in recognising a shape at a translation and rotation unknown in the training stage.
Finally classification is done with two different approaches: (1) End-to-end approaches and (2) feature-based approaches. For (1) Convolutional Neural Networks (CNNs) and other classifiers are tested directly over raw pixels, whereas for (2) PCA is mostly used to extract features and again different algorithms are tested for classification. Finally, results are presented showing accuracy and speed for (1) and (2) and how blurring affects the accuracy
M-theory on Manifolds of G_2 Holonomy and Type IIA Orientifolds
We demonstrate that M-theory compactifications on 7-manifolds of G_2
holonomy, which yield 4d N=1 supersymmetric systems, often admit at special
loci in their moduli space a description as type IIA orientifolds. In this way,
we are able to find new dualities of special IIA orientifolds, including
dualities which relate orientifolds of IIA strings on manifolds of different
topology with different numbers of wrapped D-branes. We also discuss models
which incorporate, in a natural way, compact embeddings of gauge theory/gravity
dualities similar to those studied in the recent work of Atiyah, Maldacena and
Vafa.Comment: 14 pages, minor correction and references adde
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