631 research outputs found

    Beyond the Standard Model: LHC Phenomenology, Cosmology from Post-inflationary Sources, and Dark Matter Physics

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    It is the goal of this dissertation to demonstrate that beyond the standard model, certain theories exist which solve conflicts between observation and theory -- conflicts such as massive neutrinos, dark matter, unstable Higgs vacuum, and recent Planck observations of excess relativistic degrees of freedom in the early universe. Theories explored include a D-brane inspired construct of U(3) × Sp(1) × U(1) × U(1) extension of the standard model, in which we demonstrate several possible observables that may be detected at the LHC, and an ability to stabilize the Higgs mechanism. The extended model can also explain recent Planck data which, when added to HST data gives an excess of relativistic degrees of freedom of Δ N = 0.574 ± 0.25 above the standard result. Also explored is a possible non-thermal dark matter model for explanation of this result. Recent observations of Fermi bubble results indicate a signal of a 50 GeV dark matter particle annihilating into b b-bar, with a thermally averaged annihilation cross section corresponding to \u3cσ v\u3e = 8 × 10^(-27) cm^3/s, spurs interest in a Higgs portal model suggested by Steven Weinberg. Other implications of this model are also explored such as its ability to explain dark matter direct detection results along with LHC Higgs data, and Planck data. Particle physics is complimented by possible stochastic gravitational wave searches for which a model of second order global phase transitions is explored. These transitions generate gravitational wave spectra with amplitudes of order Ω(gw) h^2 = 10^(-24) - 10^(-15). Furthermore, techniques into such calculations are investigated in hopes to improve the stability required in such lattice simulations

    VHDL Models with Usage of the LFSR_PCKG Package

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    LFSRs (Linear Feedback Shift Registers) are very often used in the BIST (Built-In Self-Test) methodology. Implementation of the LFSRs to the design or application of digital system, which supports BIST techniques or which only uses these LFSRs, can be done by VHDL language. This paper presents VHDL models of the devices and subroutines (e.g. test pattern generators, signature analysers). Models are based on LFSR structures with usage of the LFSR_PCKG package described in the (Kovalsky and Vlcek, 2001), which can be used in the applications supporting BIST techniques. Devices are described as behavioural and structural models. These models and descriptions can be used e.g. in the (Kovalsky, 2001). The LFSR_PCKG was modified and new approach is presented. Naturally, there are presented some synthesis conclusions of the VHDL models and applications in this paper

    Utilization of Birefringent Fiber as Sensor of Temperature Field Disturbance

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    The paper deals with utilization of induced birefringence sensitivity to temperature field in birefringent optical fibers. The propagating optical wave and optical fibers are described by means of coherency and Jones matrices, which are decomposed into unitary matrix and spin matrices. The development of polarization caused by temperature field is interpreted on the Poincare sphere by means of MATLAB® environment. The temperature sensitivity of Panda and bow-tie fiber has been measured for circular polarization excitation. Curves of intensity fluctuation caused by the temperature dependence are presented

    Evaluation of seals for high-performance cryogenic turbomachines

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    An approach to computing flow and dynamic characteristics for seals or bearings is discussed. The local average velocity was strongly influenced by inlet and exit effects and fluid injection, which in turn drove zones of secondary flow. For the restricted three-dimensional model considered, the integral averaged results were in reasonable agreement with selected data. Unidirectional pressure measurements alone were insufficient to define such flow variations. However, for seal and bearing leakage correlations the principles of corresponding states were found to be useful. Also discussed are three phenomena encountered during testing of three eccentric nonrotating seal configurations for the Space Shuttle Main Engine (SSME) Program. Fluid injection, choking within a seal, and pressure profile crossover are related to postulated zones of secondary flow or separation and to direct stiffness

    Large Scale Anisotropy of Cosmic Rays and Directional Neutrino Signals from Galactic Sources

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    We investigate the neutrino - cosmic ray connection for sources in the Galaxy in terms of two observables: the shape of the energy spectrum and the distribution of arrival directions. We also study the associated gamma ray emission from these sources.Comment: Proceedings of the 2nd Cosmic Ray Anisotropy Workshop, 26-28 September 2013, Madison, Wisconsin. To appear in IOP Conference Serie

    Comparison of linear and non-linear 2D+T registration methods for DE-MRI cardiac perfusion studies

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    A series of motion compensation algorithms is run on the challenge data including methods that optimize only a linear transformation, or a non-linear transformation, or both – first a linear and then a non-linear transformation. Methods that optimize a linear transformation run an initial segmentation of the area of interest around the left myocardium by means of an independent component analysis (ICA) (ICA-*). Methods that optimize non-linear transformations may run directly on the full images, or after linear registration. Non-linear motion compensation approaches applied include one method that only registers pairs of images in temporal succession (SERIAL), one method that registers all image to one common reference (AllToOne), one method that was designed to exploit quasi-periodicity in free breathing acquired image data and was adapted to also be usable to image data acquired with initial breath-hold (QUASI-P), a method that uses ICA to identify the motion and eliminate it (ICA-SP), and a method that relies on the estimation of a pseudo ground truth (PG) to guide the motion compensation
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