Beyond the Cosmological Principle

Simplifying the Einstein field equation by assuming the cosmological principle yields a set of differential equations which governs the dynamics of the universe as described in the cosmological standard model. The cosmological principle assumes the space appears the same everywhere and in every direction and moreover, the principle has earned its position as a fundamental assumption in cosmology by being compatible with the observations of the 20th century. It was not until the current century when observations in cosmological scales showed significant deviation from isotropy and homogeneity implying the violation of the principle. Among these observations are the inconsistency between local and non-local Hubble parameter evaluations, baryon acoustic features of the Lyman-α forest and the anomalies of the cosmic microwave background radiation. As a consequence, cosmological models beyond the cosmological principle have been studied vastly; after all, the principle is a hypothesis and as such should frequently be tested as any other assumption in physics. In this thesis, the effects of inhomogeneity and anisotropy, arising as a consequence of discarding the cosmological principle, is investigated. The geometry and matter content of the universe becomes more cumbersome and the resulting effects on the Einstein field equation is introduced. The cosmological standard model and its issues, both fundamental and observational are presented. Particular interest is given to the local Hubble parameter, supernova explosion, baryon acoustic oscillation, and cosmic microwave background observations and the cosmological constant problems. Explored and proposed resolutions emerging by violating the cosmological principle are reviewed. This thesis is concluded by a summary and outlook of the included research papers.Kosmologinen periaate, jonka otaksutaan pätevän kosmologisessa standardimallissa, olettaa avaruuden näyttävän samalta joka pisteessä ja joka suunnassa. Tämä periaate on ansainnut paikkansa hyvänä oletuksena sopimalla havaintoihin erittäin hyvin aina 2000-luvun vaihteeseen asti sekä yksinkertaistamalla Einsteinin yhtälön kauniiseen ja yksinkertaiseen muotoon.Vasta vuosituhannen vaihteen jälkeen tehdyissä havainnoissa on löytynyt uskottavia todisteita kosmologista periaatetta vastaan. Tällaisia havaintoja ovat muun muassa ristiriitaiset tulokset Hubblen parametrin määrityksessä, Lyman-α-metsän baryoniakustiset oskillaatiot sekä anomaliat kosmisessa taustasäteilyssä. Lisäksi, vaikka havaintoja kosmologista periaatetta vastaan ei olisikaan vielä löytynyt, periaatetta tulee testata kuin mitä tahansa oletusta fysiikassa. Tässä väitöskirjassa tutkitaan ilmiöitä, jotka seuraavat kosmologisen periaatteen hylkäämisestä. Yleisellä tasolla voidaan sanoa, että periaatteesta luovuttaessa universumin geometria monimutkaistuu ja materiasisältö monimuotoistuu. Tämän seurauksena systeemiä kuvaavien yhtälöiden ratkaiseminen hankaloituu, joka tässä kirjassa havainnollistetaan esittelemällä kosmologinen standardimalli sekä joitakin kosmologista periaatetta rikkovia malleja. Myös kosmologisen standardimallin ongelmia havainnollistetaan konkreettisesti. Erityistä huomiota saavat Hubblen parametri, supernovat, baryoniakustiset oskillaatiot, kosminen taustasäteily sekä pimeän energian ongelma. Kosmologista periaatetta rikkovia malleja on tutkittu laajasti yrittäen löytää niistä ratkaisu kosmologisen standardimallin ongelmiin; näitä ratkaisuyrityksiä kuvaillaan. Lopuksi väitöskirjassa esitellyistä artikkeleista tehdään yhteenveto.Siirretty Doriast

40Ar/39Ar ages of muscovites from modern Himalayan rivers: Himalayan evolution and the relative contribution of tectonicsand climate

International audience40Ar/39Ar ages from detrital muscovites have been analyzed from six modern rivers in central and western Nepal; the size of the drainage basins associated with these samples ranges from a few square kilometers to >40,000 km2. These data, when combined with previously published ages of detrital muscovites from other modern rivers in the region, suggest that a good correspondence between normalized age and normalized topography (the comparison of t* and z*) is rare, due to either nonuniform rates of passage through the ∼400 °C isotherm or subsequent faulting in the drainage area. The closure temperature of Ar in muscovite is perhaps too high to make meaningful comparisons to modern topography in tectonic analysis of active orogens.The distribution of 40Ar/39Ar ages from detrital muscovites from the Karnali basin in western Nepal is much older than that for the Narayani basin in central Nepal. The Karnali muscovites, when combined with previously published muscovites from the Siwalik Group in western Nepal and zircon fission track ages from modern and ancient samples from the region, suggest a thermal history for western Nepal consistent with vigorous tectonics (and attendant erosion) before the middle Miocene but a significant diminution in the rate of erosion since ca. 10 Ma.40Ar/39Ar ages of detrital muscovites from the Narayani basin in central Nepal suggest a markedly different history with an acceleration of the rate of erosion since ca. 10 Ma and reactivation of major faults; this is consistent with the abundant bedrock data from the Narayani basin.The strong difference in the erosional history of the adjacent Karnali and Narayani basins, as evidenced by the 40Ar/39Ar ages from detrital muscovites, is not likely to have been due to variations in climate, but rather due to strain partitioning within the Himalaya during and after the Miocene

Anisotropic cosmology and inflation from tilted Bianchi IX model

The dynamics of the tilted axisymmetric Bianchi IX cosmological models are explored allowing energy flux in the source fluid. The Einstein equations and the continuity equation are presented treating the equation of state w w and the tilt angle of the fluid lambda as time dependent functions, but when analysing the phase space ww and lambda are considered free parameters and the shear, the vorticity and the curvature of the spacetime span a three-dimensional phase space that contains seven fixed points. One of them is an attractor that inflates the universe anisotropically, thus providing a counter example to the cosmic no-hair conjecture. Also, examples of a realistic though fine-tuned cosmologies are presented wherein the rotation can grow significant towards the present epoch but the shear stays within the observational bounds. The examples suggest that the model used here can explain the parity-violating anomalies of the cosmic microwave background. The result significantly differs from an earlier study, where a non-axisymmetric Bianchi IX type with a tilted perfect dust source was found to induce too much shear for observationally significant vorticity.</p

Plasma atropine concentrations associated with decreased intestinal motility in horses

IntroductionAtropine is an essential part of the treatment protocol for equine uveitis. Topical atropine administration has been associated with decreased intestinal motility and abdominal pain in horses. Experimental studies have indicated that frequent dosing is associated with a higher risk than dosing every 6 h. Unfortunately, no quantitative pharmacodynamic data for inhibition of the equine gut are published. Materials and methodsEight standardbred horses were assigned to receive either atropine or saline (control) to be infused over 30 min in a two-treatment cross-over design. Atropine concentrations in plasma were measured using ultra-high-performance liquid chromatography-tandem mass spectrometry. Intestinal motility was measured using borborygmi frequency and electrointestinography (EIG). Experimental data were analyzed using a non-linear mixed effects model. The model was then used to simulate different dosing regimens. ResultsAtropine significantly decreased borborygmi response and EIG response. Six horses developed clinical signs of abdominal pain. The pharmacokinetic typical values were 0.31, 1.38, 0.69, and 1.95 L/kg center dot h for the volumes of the central, the highly perfused, the scarcely perfused compartments, and the total body clearance, respectively. The pharmacodynamic typical values were 0.31 mu g/L and 0.6 and 207 nV(2)7 cpm for the plasma concentration at 50% of the maximum response and the maximum response and the baseline of cecal EIG response, respectively. Six different dosing regimens of topical atropine sulfate to the eye (0.4 and 1 mg every hour, every 3 h, and every 6 h) were simulated. ConclusionThe IV PK/PD data coupled with simulations predict that administration of 1 mg of topical atropine sulfate administered to the eye every hour or every 3 h will lead to atropine accumulation in plasma and decreased intestinal myoelectric activity. Administration every 6 h predicted a safe dosing regimen in full-sized horses. Clinical studies would be valuable to confirm the conclusions. For smaller equids and horses put at risk for colic due to othercauses, droplet bottles that deliver 40 mu l of 1% atropine sulfate per drop or less may be used to lower the risk further

Gauge fields and infinite chains of dualities

We show that the particle states of Maxwell's theory, in $D$ dimensions, can be represented in an infinite number of ways by using different gauge fields. Using this result we formulate the dynamics in terms of an infinite set of duality relations which are first order in space-time derivatives. We derive a similar result for the three form in eleven dimensions where such a possibility was first observed in the context of E11. We also give an action formulation for some of the gauge fields. In this paper we give a pedagogical account of the Lorentz and gauge covariant formulation of the irreducible representations of the Poincar\'e group, used previously in higher spin theories, as this plays a key role in our constructions. It is clear that our results can be generalised to any particle.Comment: 37 page