Browsing by Subject "EXTENSIONS"

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  • Jousimo, Jussi; Ovaskainen, Otso (2016)
    Random encounter models can be used to estimate population abundance from indirect data collected by non-invasive sampling methods, such as track counts or camera-trap data. The classical Formozov-Malyshev-Pereleshin (FMP) estimator converts track counts into an estimate of mean population density, assuming that data on the daily movement distances of the animals are available. We utilize generalized linear models with spatio-temporal error structures to extend the FMP estimator into a flexible Bayesian modelling approach that estimates not only total population size, but also spatio-temporal variation in population density. We also introduce a weighting scheme to estimate density on habitats that are not covered by survey transects, assuming that movement data on a subset of individuals is available. We test the performance of spatio-temporal and temporal approaches by a simulation study mimicking the Finnish winter track count survey. The results illustrate how the spatio-temporal modelling approach is able to borrow information from observations made on neighboring locations and times when estimating population density, and that spatio-temporal and temporal smoothing models can provide improved estimates of total population size compared to the FMP method.
  • Gao, Hui; Poyeton, Leo (2021)
    Let p be a prime, let K be a complete discrete valuation field of characteristic 0 with a perfect residue field of characteristic p, and let G(K) be the Galois group. Let pi be a fixed uniformizer of K, let K-infinity be the extension by adjoining to K a system of compatible p(n) th roots of pi for all n, and let L be the Galois closure of K-infinity. Using these field extensions, Caruso constructs the (phi, tau)-modules, which classify p-adic Galois representations of G(K). In this paper, we study locally analytic vectors in some period rings with respect to the p -adic Lie group Gal(L/K), in the spirit of the work by Berger and Colmez. Using these locally analytic vectors, and using the classical overconvergent (phi, Gamma)-modules, we can establish the overconvergence property of the (phi, tau)-modules.
  • Schwieger, Kay; Wagner, Stefan (2017)
    We study a simple class of free actions of non-Abelian groups on unital C* -algebras, namely cleft actions. These are characterized by the fact that the associated noncommutative vector bundles are trivial. In particular, we provide a complete classification theory for these actions and describe its relations to classical principal bundles.
  • Frank, Mariana; Fuks, Benjamin; Huitu, Katri; Rai, Santosh Kumar; Waltari, Harri (2017)
    Right-handed sneutrinos are natural components of left-right symmetric supersymmetric models where the gauge sector is extended to include right-handed weak interactions. Unlike in other models where right-handed sneutrinos are gauge singlets, here the right sneutrino is part of a doublet and could be a dark matter candidate whose annihilation proceeds via gauge interactions. We investigate this possibility, and find that relic density, low-energy observable and direct supersymmetry search constraints can be satisfied when the lightest supersymmetric particle is a right-handed sneutrino. We introduce benchmarks for left-right supersymmetric realizations where either a sneutrino or a neutralino is the lightest superpartner. We then study the LHC signals arising through resonant right-handed slepton production via a W-R gauge-boson exchange that lead to final states enriched in leptons, additionally containing a large amount of missing transverse momentum, and featuring a low jet multiplicity. We find that such a resonant production would boost the chances of discovering these weakly interacting supersymmetric particles for a mass range extending beyond 1TeV already with a luminosity of 100 fb(-1). Finally, we compare sneutrino versus neutralino scenarios, and comment on differences with other sneutrino dark matter models.