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Showing result 1 - 5 of 21 swedish dissertations matching the above criteria.

2. 1. Stochastic Models in Phylogenetic Comparative Methods: Analytical Properties and Parameter Estimation

   Author : Krzysztof Bartoszek; Göteborgs universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; Adaptation; Adaptation; Birth-death process; Branching diffusion; Brownian motions; Conditioned branching process; Evolution; General Linear Model; Hybridization; Macroevolution; Measurement error; Multivariate phylogenetic comparative method; Optimality; Ornstein-Uhlenbeck process; Phyletic gradualism; Phylogenetic inertia; Phylogenetic uncertainty; Punctuated equilibrium; Yule tree; Macroevolution;

   Abstract : Phylogenetic comparative methods are well established tools for using inter-species variation to analyse phenotypic evolution and adaptation. They are generally hampered, however, by predominantly univariate approaches and failure to include uncertainty and measurement error in the phylogeny as well as the measured traits. READ MORE

4. 2. Some Extensions of Fractional Ornstein-Uhlenbeck Model : Arbitrage and Other Applications

   Author : José Igor Morlanes; Andriy Andreev; Hans Nyquist; Henrik Hult; Stockholms universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; fractional Ornstein-Uhlenbeck process; insider information; simulation embedding method; jump times; least-squares estimator; likelihood process; Ito calculus; Malliavin calculus; stochastic calculus; Statistics; statistik;

   Abstract : This doctoral thesis endeavors to extend probability and statistical models using stochastic differential equations. The described models capture essential features from data that are not explained by classical diffusion models driven by Brownian motion.New results obtained by the author are presented in five articles. READ MORE

5. 3. Multivariate Aspects of Phylogenetic Comparative Methods

   Author : Krzysztof Bartoszek; Göteborgs universitet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; General Linear Model; Ornstein-Uhlenbeck process; Multivariate phylogenetic comparative method; Evolutionary model; Adaptation; Optimality; Measurement error; Regression; Adaptation; Major-axis regression; Reduced major-axis regression; Structural equation; Allometry; Phylogenetic inertia; Allometry;

   Abstract : his thesis concerns multivariate phylogenetic comparative methods. We investigate two aspects of them. The first is the bias caused by measurement error in regression studies of comparative data. We calculate the formula for the bias and show how to correct for it. READ MORE

6. 4. A Differentiable Approach to Stochastic Differential Equations : the Smoluchowski Limit Revisited

   Author : Haidar Al-Talibi; Astrid Hilbert; Yaozhong Hu; Linnéuniversitetet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; α-stable Lévy noise; Fractional Brownian motion; Girsanov theorem; Mean-field model; Nonlinear stochastic oscillator; Ornstein-Uhlenbeck process; Scaling limit; Second order Itô equation; Time change.; Matematik; Mathematics;

   Abstract : In this thesis we generalize results by Smoluchowski [43], Chandrasekhar[6], Kramers, and Nelson [30]. Their aim is to construct Brownian motion as a limit of stochastic processes with differentiable sample paths by exploiting a scaling limit which is a particular type of averaging studied by Papanicolao [35]. READ MORE

7. 5. Nelson-type Limits for α-Stable Lévy Processes

   Author : Haidar Al-Talibi; Astrid Hilbert; Francesco Russo; Linnéuniversitetet; []
   Keywords : NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; Ornstein-Uhlenbeck position process; α-stable Lévy noise; scaling limits; time change; stochastic Newton equations; Mathematical statistics; Matematisk statistik; Applied mathematics; Tillämpad matematik; Mathematics; Matematik;

   Abstract : Brownian motion has met growing interest in mathematics, physics and particularly in finance since it was introduced in the beginning of the twentieth century. Stochastic processes generalizing Brownian motion have influenced many research fields theoretically and practically. READ MORE