Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 39 for “"cosmological models"”.
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Cosmological Models and Observation
… conditions for numerical integration. With the cosmological software package Cmbeasy we compute model predictions and compare these with experimental data. For constraining cosmological models quickly and conveniently we employ Markov Chain Monte Carlo simulation. We describe both the theory and …
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On Inflationary cosmological models
… mechanisms leading to in ation are based on models of gravity minimally coupled to a scalar field rolling on a suitable potential V. We discuss such a model defined by the action I = ∫√-g p [R -2 (φ)2 )] d4x, in order to find exact general isotropic and homogeneous cosmological solutions …
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Representaciones mentales de docentes sobre el universo : los modelos cosmológicos que lo explican y aplicación de una estrategia metodológica para promover su evolución
… explain the universe included by them in their cosmological models; and the other one experimental, where we applied a methodological strategy inspired by common points of the theories of the mental models of Johnson-Laird and of the conceptual fields of Gérard Vergnaud whose objective was to …
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Aspects of String Compactification
… relevant to phenomenology, especially cosmological models derived from string theory Most attention is drawn to stabilizing the moduli and discussing the cosmology solutions given the effective potential obtained from string theory. We first discuss compactification of type IIB string …
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Cosmological hydrodynamic simulations of the Lyman-alpha forest
Several three dimensional, multi-species, cosmological hydrodynamic simulations of the formation and evolution of Ly$\alpha$ forest absorbers were performed in three CDM-like cosmological models: the standard CDM model (SCDM), the flat CDM model with a nonzero cosmological constant ($\Lambda$CDM) …
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Properties of expanding universes
… 4 deals with the occurrence of singularities in cosmological models. It is shown that a singularity is inevitable provided that certain very general conditions are satisfied.
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Cosmic expansion in homogeneous and inhomogeneous universes : supernovae type Ia as cosmic probes
… to be expanding accelerated, a large variety of cosmological models have been developed that allow for cosmic acceleration. Some of the models include a dark energy term that causes the acceleration, while others modify gravity or drop the assumption of homogeneity and isotropy. As an example of …
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Theory and phenomenology of quintessence
We investigate cosmological models containing quintessence. Quintessence is a hypothetical form of energy distributed almost homogeneously throughout the Universe. We calculate cosmological perturbations and cosmic microwave background anisotropies using gauge-invariant variables. For many models, …
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From the Harmony of the Spheres to Spherical Harmonics : The Potential of Wave-Based Morphogenetic Processes for Musical and Architectural Composition
… in the Western world. It also reflects the cosmological roots of this connection, which translates through a number of analogies in several fields (mythology, poetry, science, philosophy...), and which at times explicitly considered music and architecture as terrestrial echoes of the cosmos. …
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Constraining reionization: Evidence from 21 cm limits and predictions for fast radio bursts
… only been done for specific reionization models; I propose using a model-independent parameterization of reionization. I employ synthetic data of future FRB measurements at high redshifts z>5 to show that (i) the model-independent method removes a significant bias in the inferred optical …
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Topics in stringy cosmology
… topics. The first topic concerns Randall-Sundrum cosmological models, in particular their isotropization properties at early times. We first study the state space of inflationary braneworld models with exponential potential and identify the past and future attractors within the homogeneous state …
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The Effective Field Theory Approach to Fluid Dynamics, Modified Gravity Theories, and Cosmology
… mechanical properties and dissipative effects. Cosmological models can be built by naturally coupling the fluid EFT to gravity. From the EFT point of view, GR is the unique low energy theory for the spin-2 graviton field and any infrared modification corresponds to adding new degrees of freedom. …
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QSO Absorption Lines
… of this quantity is important for constraining cosmological models and can also help us to understand the chemical evolution of light elements in galaxies. A series of numerical simulations has been carried out to explore the potential for such measurements and an absorption system has been …
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Bayesian modeling of microwave foregrounds
… and Wilson, precise measurements of various cosmological parameters have provided a glimpse into the dynamics of the early Universe and the fate that awaits it in the very distant future. However, these measurements are hindered by the presence of strong foreground contamination (synchrotron, …
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THE COVARIANT APPROACH TO SPACE TIMES ANDSOME EXTENDED THEORIES OF GRAVITY
… in investigations of radiating stars and cosmological models. Here the Ricci tensor also contains a heat flow and anisotropic terms originating from the presence of a spatial acceleration vector. The geometric corrections in extended theories are investigated. In spherically symmetric …
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The search for dark matter annihilation in galaxy clusters at VERITAS
<p>Recent data and cosmological models point to a significant fraction of the Universe being comprised of Cold Dark Matter (DM), though little is known about it directly as it does not interact electromagnetically. The most likely explanation for DM is a Weakly Interacting Massive Particle (WIMP) …
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A New Mass Measurement for Galaxy Clusters Using Position and Radial Velocity
… mass profiles is a useful tool for constraining cosmological models. Mostmethods established for obtaining a mass profile of a cluster of galaxies assumes theclusters obey the virial theorem; however, the majority of clusters are observed to containnon-virialized substructures. Zaritsky outlined …
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Simulations of dark energy cosmologies
… of cosmic structure in different dark energy models, using ultra-large volume N-body simulations. We measure key observables such as the growth of large scale structure, the halo mass function and baryonic acoustic oscillations. We study the power spectrum in redshift space in $\Lambda$CDM and …
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Alternative theories of gravity and their application to cosmology
… us to investigate the global dynamics of some cosmological models resulting from scalar-tensor and higher-order theories of gravity. We use the dynamical systems approach with non–compact expansion normalised variables to study the isotropisation of Bianchi type I models in Rn–gravity. We find …
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