Previous events - Page 270

Friday seminar by Anna Gårdmark

CEES Extra seminar by Ana Gouveia

Welcome to the GeoHyd Lunch Seminar Friday 28 February. Meet up in Aud I in the Geology building.

We read a paper in Journal of Mathematical Biology by Lambert, Morlon and Etienne about a model for diversification when speciation is protracted, as a follow up to last week's reading. It's not yet up on the journal's website but is accessible at arvis.org

This Thursday we will discuss a paper on how speciation- and extinction rates contribute to the latitudinal gradient in mammal diversity. The paper entitled "Faster Speciation and Reduced Extinction in the Tropics Contribute to the Mammalian Latitudinal Diversity Gradient" by Rolland and colleagues was recently published in PloS Biology.  

Torstein Nilssen (Universitetet i Oslo) holder et seminar med tittelen: Malliavin differentiability for a class of SDE's in Hilbert spaces.

Christoph Weniger, University of Amsterdam

One of the major challenges of astroparticle research is to uncover the particle nature of dark matter. Weakly interacting massive particles (WIMPs) are the most popular candidates and currently scrutinized by a large number of experiments. In particular indirect searches for the self-annihilation products of WIMPs in the gamma- and cosmic-ray sky are a promising avenue to follow. I will discuss different techniques that aim at an identification of a dark matter contribution over the astrophysical background, recent claims for dark matter signals in the Fermi LAT data, and challenges for future experiments.

A continuation of the previous talk.   

Seminar by Dr. Fabrice Anizon, Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, France.

Magnus Landstad will give a talk with title: Quantum groups from almost matched pairs of groups - the groupoid approach

Abstract: If G is a locally compact group with two closed subgroups H,K s.t. G=HK, then (H,K) is called a matched pair of subgroups. The construction of a quantum group from such a pair goes back a long time. We shall look at the more general case where the subgroups are almost matched (the complement of HK in G has measure 0), then a groupoid approach to the construction is very useful and many formulas are obtained for free.

I shall start with explaining the concepts needed (quantum groups, groupoids, etc) and then how the groupoid is constructed. Finally we shall look at the special case where G has a compact open subgroup.

This is joint work with A. Van Daele.

Dongho Chae (Chung-Ang University, Korea) will give a seminar talk entitled

On the self-similar blow-up for the compressible Euler equations

Abstract: The problem of finite time blow-up/global regularity of the 3D incompressible Euler equations is an outstanding problem in mathematical fluid mechanics. On the other hand, the scenario of self-similar type blow-up is a natural candidate of blow-ups in various nonlinear partial differential equations such as the porous medium equation and the nonlinear Schrödinger equations. We also mention that for the closely related incompressible Navier-Stokes equations the question of self-similar blow-up was raised by J. Leray in 1930, and was negatively answered by J. Necas, M. Ruzicka and V. Sverak in 1996. In this talk we present the progress of study during the last several years on the self-similar blow-up for the Euler equations.

Friday seminar by Gilles Guillot

Johanna Ridder (University of Oslo) will give a talk about

Analysis of a finite difference method for two-dimensional incompressible magnetohydrodynamics

Abstract: We consider the magnetohydrodynamics equations for a viscous incompressible resistive fluid in two dimensions. For these equations we analyse a semi-discrete finite difference scheme that is based on a staggered grid and is energy preserving. We show an a priori H^1-bound and the convergence of the scheme.

Emily Freeland, postdoc at OCK/Stockholm University.

MaEcovo will discuss a review paper by Helene Morlon regarding models of diversification. Ecology Letters (early view)

Professor B. Rajeev (India Statistical Institute, Bangalore) holder et seminar med tittelen: The Monotonicity Inequality on Hermite-Sobolev spaces.

Do you supervise students? Do you find the responsibility daunting? Do you know how to avoid problems? Or solve them if they appear?

Francesca Calore, University of Amsterdam

Discovering Dark Matter (DM) interactions with ordinary matter, other than gravity, is the current challenge of DM detection experiments. Notably, the indirect detection looks for the final stable products of DM annihilation as rare components of cosmic rays.

For typical DM WIMP candidates the two-body annihilation rate today is suppressed because of helicity arguments. Luckily, the emission of an additional vector boson in the final state may play an important role in enhancing the discovery potential of this particularly well motivated DM candidate with current and future gamma-rays experiments.

I will show how the sharp spectral features at the high energy end of the gamma-ray spectrum induced by electromagnetic corrections can be promisingly looked for with gamma-ray telescopes.

I will then demonstrate that also electroweak bremsstrahlung, whose first fully general calculation in the framework of the Minimal Supersymmetric Standard Model (MSSM) I will present, might alter significantly the energy spectra of gamma rays and imply an annihilation into three-body final states at a rate several orders of magnitude above the tree-level result.

In 1980 R. W. Thomason published a proof that CAT, the category of small categories, is a proper closed model category that is Quillen equivalent to SSet, the category of simplicial sets, with the standard model structure defined by Quillen. D-C Cisinski has since corrected the proof of left properness by replacing the central term of Dwyer morphism - a class of morphisms that Thomason believed to be the cofibrations - with a rough analogue in CAT of the NDR-pairs. The cofibrations, then, which are all retracts of Dwyer morphisms, are really the NDR-pair analogues. I will go through the main parts of Thomason's argument, incorporating Cisinski's adjustment, point out Thomason's mistake and here and there use more recent terminology from M. Hovey's book Model Categories. Towards the end I'll compare Thomason's method with modern, standardized ways of confirming a cofibrantly generated (closed) model structure, like the necessary and sufficient conditions listed in Hovey's Model Categories (thm. 2.1.19) and transferring a model structure across an adjunction by using Kan's lemma on transfer and similar results 

Friday seminar by Bart Pollux

Welcome to the GeoHyd Lunch Seminar Friday 14 February. Meet up in Aud I in the Geology building.

Nils Chr. Stenseth, Professor of Ecology and Evolution at Department of Biosciences, University of Oslo  

On Friday the 14th of February, the MaEcovo journal club will be discussing the 2013 paper by Fussman and Gonzales: "Evolutionary rescue can maintain an oscillating community undergoing environmental change"