Dark Energy: Observational Evidence and Theoretical Models

The book elucidates the current state of the dark energy problem and presents the results of the authors, who work in this area. It describes the observational evidence for the existence of dark energy, the methods and results of constraining of its parameters, modeling of dark energy by scalar fields, the space-times with extra spatial dimensions, especially Kaluza---Klein models, the braneworld models with a single extra dimension as well as the problems of positive definition of gravitational energy in General Relativity, energy conditions and consequences of their violation in the presence of dark energy. This monograph is intended for science professionals, educators and graduate students, specializing in general relativity, cosmology, field theory and particle physics.Comment: Book, 380 p., 88 figs., 7 tables; 1st volume of three-volume book "Dark energy and dark matter in the Universe", ed. V. Shulga, Kyiv, Academperiodyka, 2013; ISBN 978-966-360-239-4, ISBN 978-966-360-240-0 (vol. 1). arXiv admin note: text overlap with arXiv:0706.0033, arXiv:1104.3029 by other author

A Study of a Ventricular Motion in Cardiac MRI using Deformable Model

We experimented with a novel deformable model that track the right ventricle’s (RV) wall motion through complete cardiac cycle by using a snake-like approach. The model uses a complex Fourier shape descriptor parameterization for efficient calculation of forces that constrains contour deformation. Even though the complexity exists in RV boundary shape, the model tracks the contour correctly and shows the robustness in weak contrast and noisy edge map. We also present a quantitative evaluation of delineation accuracy by comparing manual segmented contours and semi-automatically segmented contour, to check the reliability of our deformable model. The extracted shapes shows that the error between two contours to be an average of two pixels from 256 pixels by 256 pixels of cardiac magnetic resonance images. We used the spatio-temporal characterization of ventricular wall motion, obtained by our model, to help classifying the Intra-ventricular dyssynchrony (IVD) in the LV - i.e. asynchronous activation of LV wall - by adding RV information of ventricular movement to existing data. The classifying method was to use a popular statistical pattern recognition method of the Principal Component Analysis and the Fisher’s Linear Discriminant Analysis. From a database contains 33 patients, our classifier produced correct classification performance of 87.9 % with the RV data, which shows the promising improved IVD classification as contrast to current criteria for selecting therapy, which provided the correct classification of just 84.8 % on the same database with only the LV data

Transverse Momentum Dependence of Hanbury-Brown/Twiss Correlation Radii

The transverse momentum dependence of Hanbury-Brown/Twiss (HBT) interferometry radii for 2-body correlation functions provides experimental access to the collective dynamics in heavy-ion collisions. We present an analytical approximation scheme for these HBT radii which combines the recently derived model-independent expressions with an approximate determination of the saddle point of the emission function. The method is illustrated for a longitudinally boost-invariant hydrodynamical model of a heavy ion collision with freeze-out on a sharp hypersurface. The analytical approximation converges rapidly to the width of the numerically computed correlation function and reproduces correctly its exact transverse momentum dependence. However, higher order corrections within our approximation scheme are essential, and the previously published lowest order results with simple $m_{\perp}$ scaling behaviour are quantitatively and qualitatively unreliable.Comment: 34 pages, 3 Postscript figures, RevTe

Measurement of the Top Quark Pair Production Cross Section in pbar-p Collisions Using Multijet Final States

We have studied tbar-t production using multijet final states in pbar-p collisions at a center-of-mass energy of 1.8 TeV, with an integrated luminosity of 110.3 pb(-1). Each of the top quarks with these final states decays exclusively to a bottom quark and a W boson, with the W bosons decaying into quark-antiquark pairs. The analysis has been optimized using neural networks to achieve the smallest expected fractional uncertainty on the tbar-t production cross section, and yields a cross section of 7.1 +/- 2.8(stat.) +/- 1.5(syst.) pb, assuming a top quark mass of 172.1 GeV/c^(2). Combining this result with previous D0 measurements, where one or both of the W bosons decay leptonically, gives a tbar t production cross section of 5.9 +/- 1.2(stat) +/- 1.1(syst) pb.Comment: 30 pages, 32 figures; no substative change in revisio

Automatic verification of road databases using multiple road models

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