## Visiting address

Ullevål StadionSognsveien 77B

0855 OSLO

Norway

Time and place:
Sep. 23, 2016 11:15 AM - 12:00 PM,
NHA bygget 9 etg B91

**Experimental investigation of linear stability mechanisms in stratified gas-liquid pipe flow**

The evolution of interfacial waves on a stratified air water pipe flow is investigated experimentally. An oscillating plate introduced controlled perturbations at the inlet of the pipe. High speed cameras captured the evolution of these perturbations along the pipe by means of a phase-locked shadowgraphy technique. Thereby, it was possible to measure the temporal and the spatial evolution of the disturbances introduced in the flow. Particle image velocimetry was performed further downstream in order to evaluate changes in the base flow.

A relatively large data bank has been gathered with varying air and water flow rates as well as varying amplitudes and frequencies of the inlet perturbations. Some preliminary results contain a qualitative assessment of linear vs. non-linear regimes and momentum transfer into the water layer.

Time and place:
Sep. 23, 2016 10:15 AM,
Aud. 4 Vilhelm Bjerknes' hus

M.Sc. Bas P. A. Jordans ved Matematisk institutt avholder prøveforelesning over oppgitt emne: "Connections between quantum groups and operator algebras".

Time and place:
Sep. 22, 2016 2:15 PM - 4:00 PM,
B638, NH Abels hus

Yuan Wang (Utah), gives the Seminar in Algebra and Algebraic Geometry:

*"On the characterization of abelian varieties for log pairs in zero and positive characteristic"*

Time:
Sep. 20, 2016 2:15 PM

Håvard Kvamme (UiO, Dept. of mathematics) will give a seminar in the lunch area, 8th floor Niels Henrik Abels hus at 14:15.

Time and place:
Sep. 20, 2016 10:15 AM - 12:00 PM,
B 738

We will discuss the motivic May spectral sequence and demonstrate how to use it to identify Massey products in the motivic Adams spectral sequence. We will then investigate what is known about the motivic homotopy groups of the eta-local sphere over the complex numbers and discuss how these calculations may work over other base fields.

Time and place:
Sep. 15, 2016 2:15 PM - 4:00 PM,
B638, NH Abels hus

Francesco Galuppi (UiO/Ferrara) gives the algebraic geometry seminar:

"Identifiability of polynomials and Cremona transformations."

Time and place:
Sep. 14, 2016 2:15 PM - 3:15 PM,
B 637

Certain 3-dimensional lens spaces are known to smoothly bound 4-manifolds with the rational homology of a ball. These can sometimes be useful in cut-and-paste constructions of interesting (exotic) smooth 4-manifolds. To this end it is interesting to identify 4-manifolds which contain these rational balls. Khodorovskiy used Kirby calculus to exhibit embeddings of rational balls in certain linear plumbed 4-manifolds, and recently Park-Park-Shin used methods from the minimal model program in 3-dimensional complex algebraic geometry to generalise Khodorovskiy's result. The goal of this talk is to give an accessible introduction to the objects mentioned above and also to describe a much easier topological proof of Park-Park-Shin's theorem.

Time and place:
Sep. 14, 2016 10:15 AM - 12:00 PM,
B81

Bartosz Kwasniewski (Odense) will give a talk with title: Paradoxicality and pure infiniteness of C*-algebras associated to Fell bundles

Abstract: Abstract: In this talk we present conditions implying pure infiniteness of the reduced cross-sectional $C^*$-algebra $C^*_r(\mathcal{B})$ of a Fell bundle $\mathcal{B}$ over a discrete group $G$. We introduce notions of aperiodicity, $\mathcal{B}$-paradoxicality and residual $\mathcal{B}$-infiniteness. We discuss their relationship with similar conditions studied, in the context of crossed products, by the following duos: Laca, Spielberg; Jolissaint, Robertson; Sierakowski, R{\o}rdam; Giordano, Sierakowski and Kirchberg, Sierakowski. (based on joint work with Wojciech Szyma{\'n}ski)

Time and place:
Sep. 13, 2016 9:15 AM -
Sep. 16, 2016 11:00 AM,
Seminar room 1133

Francesca Biagini, professor in mathematical finance from Ludwig-Maximillian University of Munich, will give an intensive course from Tuesday Sept 13 to Friday Sept 16.

Time and place:
Sep. 9, 2016 -
Sep. 10, 2016,
Klækken Hotell

The statistics groups at the University of Oslo and the Norwegian University of Life Sciences invite all PhD-students and postdocs within statistics in the Oslo-region as well as their teachers and supervisors to a 2-days workshop.

Time and place:
Sep. 8, 2016 2:15 PM - 4:00 PM,
B738, NH Abels hus

Seckin Adali (UiO), gives the Seminar in Algebra and Algebraic Geometry:

Singularities of Restriction Varieties in OG(k,n)

Time and place:
Sep. 8, 2016 2:15 PM - 3:15 PM,
B637 NHA

In the nineties, Deninger gave a detailed description of a conjectural cohomological interpretation of the (completed) Hasse-Weil zeta function of a regular scheme proper over the ring of rational integers. He envisioned the cohomology theory to take values in countably infinite dimensional complex vector spaces and the zeta function to emerge as the regularized determinant of the infinitesimal generator of a Frobenius flow. In this talk, I will explain that for a scheme smooth and proper over a finite field, the desired cohomology theory naturally appears from the Tate cohomology of the action by the circle group on the topological Hochschild homology of the scheme in question.

Time and place:
Sep. 7, 2016 10:15 AM - 12:00 PM,
B801

Abstract: Exploring connections between subfactors and conformal field theories, Vaughan Jones recently observed that planar algebras give rise to unitary representations of the Thompson group F, and more generally, to unitary representations of the group of fractions of certain categories. Remarkably, this procedure applies to oriented link invariants. In particular, a suitably normalized HOMFLYPT polynomial is a positive definite function on the oriented Thompson group. (Based on joint work with V. Aiello and V. Jones.)

Time and place:
Sep. 6, 2016 10:15 AM - 12:00 PM,
B 738

The motivic Adams spectral sequence is a general tool for calculating homotopy groups of a motivic spectrum X. We will investigate the construction of the motivic Adams spectral sequence, determine the second page of the spectral sequence, and identify what it converges to in good cases. If time permits, we will show how to use the motivic Adams spectral sequence to obtain explicit calculations of the motivic homotopy groups of spheres and other spectra.

Time and place:
Sep. 5, 2016 1:00 PM -
Sep. 7, 2016 4:00 PM,
Meeting room 12th Floor NHA hus

On 5-7 September the first STORE PHD Gathering will take place, with two intensive courses. The first is on the new class of stochastic processes called Trawl processes and instructed by Almut Veraart from Imperial College London, UK. The second is led by Rudiger Kiesel from University of Duisburg-Essen, Germany, and focuses on intra-day trading of electricity.

Time and place:
Sep. 2, 2016 10:15 AM - 11:00 AM,
Undervisningsrom 801, Niels Henrik Abels hus

A class of nonlinear evolution equations of second order

Time and place:
Sep. 1, 2016 2:15 PM - 4:00 PM,
B638, NH Abels hus

Kristian Ranestad (UiO), gives the Seminar in Algebra and Algebraic Geometry:

*"Kummer surfaces and hyperkähler fourfolds, as degeneracy loci"*

Time and place:
Aug. 31, 2016 9:15 AM - 10:00 AM,
Niels Henrik Abels hus, room U26

Arturo Kohatsu-Higa (Ritsumeikan University, Kusatsu, Japan) gives a lecture with the title: Probabilistic interpretation of the parametrix method

Time and place:
Aug. 25, 2016 2:30 PM - 3:30 PM,
Rest area 7.floor NHA

Coffee/Tea/Biscuit from 14.00

Time:
Aug. 25, 2016 2:15 PM

Prof. Yasunori Fujikoshi (Hiroshima University) will give a seminar in Sverdrups plass (lunch area), 8th floor, Niels Henrik Abels hus at 14:15.

Time and place:
Aug. 25, 2016 10:15 AM - 12:00 PM,
9th floor-Ole Johan Dahls hus

The Logic Seminar will take place at the same time and location as in previous terms.

Andrea Cremaschi: Bayesian inference and prediction for high-frequency data using Particle Filtering

Time:
Aug. 16, 2016 2:15 PM

Andrea Cremaschi (earlier University of Kent, now UiO) will give a seminar in the lunch area, 8th floor Niels Henrik Abels hus at 14:15.

Time and place:
Aug. 16, 2016 10:15 AM,
B 738 NHA

Bloch constructed higher cycle class maps from higher Chow groups to Deligne cohomology and étale cohomology. I will define a map from the motivic Eilenberg-Mac Lane spectrum to the spectrum representing Deligne cohomology in the motivic stable homotopy category over C such that it gives Bloch's higher cycle class map on cohomology. The map is induced by the map from Voevodsky's algebraic cobordism spectrum MGL to the Hodge-filtered complex cobordism spectrum defined by Hopkins-Quick. This extends a result of Totaro showing that the usual cycle class map to singular cohomology factors through complex cobordism modulo the coefficients of the Lazard ring MU^{2*} tensor_L Z. This is joint work with Amit Hogadi.

Time and place:
Aug. 11, 2016 2:15 PM - 3:00 PM,
Niels Henrik Abels hus, room 935

Yaozhong Hu (University of Kansas, USA) gives a lecture with the title: Rate of convergence and asymptotic error distribution of Euler approximation schemes for fractional diffusions

Time and place:
Aug. 11, 2016 1:15 PM - 2:00 PM,
Niels Henrik Abels hus, room 935

Olfa Draouil (University of Tunis El Manar, Tunisia) gives a lecture with the title: Optimal insider control of stochastic partial differential equations