33 research outputs found

    Can induced gravity isotropize Bianchi I, V, or IX Universes?

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    We analyze if Bianchi I, V, and IX models in the Induced Gravity (IG) theory can evolve to a Friedmann--Roberson--Walker (FRW) expansion due to the non--minimal coupling of gravity and the scalar field. The analytical results that we found for the Brans-Dicke (BD) theory are now applied to the IG theory which has ωâ‰Ș1\omega \ll 1 (ω\omega being the square ratio of the Higgs to Planck mass) in a cosmological era in which the IG--potential is not significant. We find that the isotropization mechanism crucially depends on the value of ω\omega. Its smallness also permits inflationary solutions. For the Bianch V model inflation due to the Higgs potential takes place afterwads, and subsequently the spontaneous symmetry breaking (SSB) ends with an effective FRW evolution. The ordinary tests of successful cosmology are well satisfied.Comment: 24 pages, 5 figures, to be published in Phys. Rev. D1

    Global patterns and drivers of ecosystem functioning in rivers and riparian zones

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    River ecosystems receive and process vast quantities of terrestrial organic carbon, the fate of which depends strongly on microbial activity. Variation in and controls of processing rates, however, are poorly characterized at the global scale. In response, we used a peer-sourced research network and a highly standardized carbon processing assay to conduct a global-scale field experiment in greater than 1000 river and riparian sites. We found that Earth's biomes have distinct carbon processing signatures. Slow processing is evident across latitudes, whereas rapid rates are restricted to lower latitudes. Both the mean rate and variability decline with latitude, suggesting temperature constraints toward the poles and greater roles for other environmental drivers (e.g., nutrient loading) toward the equator. These results and data set the stage for unprecedented "next-generation biomonitoring" by establishing baselines to help quantify environmental impacts to the functioning of ecosystems at a global scale.peerReviewe

    ICAR: endoscopic skull‐base surgery

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    The 3D interplay between folding and faulting in a syn-orogenic extensional system: the Simplon Fault Zone in the Central Alps (Switzerland and Italy)

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    International audienceExtensional low-angle detachments developed in convergent or post-collisional settings are often associated with upright folding of the exhumed footwall. TheSimplon Fault Zone (SFZ) is a Miocene low-angle detachment that developed during convergence in the Central Alps (Switzerland and Italy), accommodating a large component of orogen-parallel extension. Its footwall shows complex structural relationships between large-scale backfolds, mylonites and a discrete brittle detachment and forms a 3D gneiss dome reflecting upright folding with fold axes oriented both parallel and perpendicular to the extension direction. We present a regional study that investigates the interplay between folding and faulting and its implications for the resulting exhumation pattern of the gneiss dome using 3D geometric modelling (computer software GeoModeller), together with a consideration of the chronological relationships from field relationships and 40Ar/39Ar dating. The early Simplon mylonitic fabric is clearly folded by both extension-parallel and extensionperpendicular folds, forming a doubly plunging antiform, whereas the later ductile-to-brittle fabric and the cataclastic detachment are only affected by wavy extension-parallel folds. This observation, together with the interpreted cooling pattern across the SFZ, suggests that updoming of the footwall initiated at the onset of faulting during ductile shearing around 18.5 Ma, due to coeval extension and perpendicular convergence. New 40Ar/39Ar dating on micas (biotite and muscovite) from a sample affected by a strong crenulation cleavage parallel to the axial plane of the Glishorn and Berisal parasitic folds establishes that these folds formed at ca. 10 Ma, broadly coeval with late movement along the more discrete detachment of the SFZ. These extension-parallel folds in the footwall of the SFZ developed due to continued convergence across the Alps, accelerating ongoing exhumation of the western Lepontine dome and promoting coeval uplift of the crystalline Aar and Gotthard massifs in the late Miocene
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