Norwegian version of this page

Events - Page 4

Time and place: , NHA B1120

I will discuss the “geometric method” for syzygies and discuss applications to the study of tautological bundles of linear spaces. From this, I will explain how to pass from realizable matroids to all matroids via initial degenerations. This is joint work in progress with Alex Fink and Chris Eur.

Time and place: , NHA B1020

A finite graph determines a Kirchhoff polynomial, which is a squarefree, homogeneous polynomial in a set of variables indexed by the edges. The Kirchhoff polynomial appears in an integrand in the study of particle interactions in high-energy physics, and this provides some incentive to study the motives and periods arising from the projective hypersurface cut out by such a polynomial.

From the geometric perspective, work of Bloch, Esnault and Kreimer (2006) suggested that the most natural object of study is a polynomial determined by a linear matroid realization, for which the Kirchhoff polynomial is a special case.

I will describe some ongoing joint work with Delphine Pol, Mathias Schulze, and Uli Walther on the interplay between geometry and matroid combinatorics for this family of objects.

Time and place: , NHA108

QOMBINE seminar by Roy Araiza (University of Illinois Urbana-Champaign)

Time and place: , Niels Henrik Abels hus, 9th floor

Innovations in fluid mechanics are leading to better food since ancient history, while creativity in cooking inspires applied and fundamental science. In this talk, I will discuss how recent advances in hydrodynamics are changing food science, and how the surprising phenomena that arise in the kitchen lead to discoveries and technologies across the disciplines, including rheology and soft matter. Central topics include cocktails and champagne (multiphase flows), whipped cream (complex fluids) and pancake making (viscous flows). For every topic, I will present the state-of-the-art knowledge, the open problems, and likely directions for future research.

Publications:
Mathijssen, A. J., Lisicki, M., Prakash, V. N., & Mossige, E. J. (2023). Culinary fluid mechanics and other currents in food science. Reviews of Modern Physics, 95(2), 025004.

Fuller, G. G., Lisicki, M., Mathijssen, A. J., Mossige, E. J., Pasquino, R., Prakash, V. N., & Ramos, L. (2022). Kitchen flows: Making science more accessible, affordable, and curiosity driven. Physics of Fluids, 34(11).

Time and place: , Abels Utsikt (NHA 1259)
Time and place: , NHA108

C*-algebra seminar talk by Valerio Proietti (University of Oslo)

Time and place: , NHA B1120
In this talk, I explain how we explicitly construct a motivic analog of the fundamental group of the circle. We construct a group structure on the set of pointed naive homotopy classes of maps from the Jouanolou device to the projective line. The group operation is defined via matrix multiplication on generating sections of line bundles and only requires basic algebraic geometry. In particular, it is completely independent of the construction of the motivic homotopy category. Based on joint work with William Hornslien, Gereon Quick, and Glen Matthew Wilson.
Time and place: , NHA108

QOMBINE seminar talk by Ruben Bassa (SINTEF)

Time and place: , Abels utsikt, 12. etasje, Niels Henrik Abels hus

Doctoral candidate Mari Dahl Eggen at the Department of Mathematics will be defending the thesis Stochastic differential equations with memory and relations - Modelling of stratospheric dynamics for the degree of Philosophiae Doctor.

Time and place: , NHA 108

Franz Fuchs (Sintef/UiO) will give a talk with title "Hamiltonians with time evolution restricted to subspaces"

Time and place: , room 1259 (Abels Utsikt) - Niels Henrik Abels hus

Doctoral candidate Juvenal Murwanashyaka at the Department of Mathematics will be defending the thesis Papers on Weak First-Order Theories and Decidability Problems for the degree of Philosophiae Doctor.

Time and place: , Niels Henrik Abels hus, 9th floor

We have developed a pump-less recirculation Organ-on-Chip (rOoC) platform that generates a directional gravity-driven flow. This platform can be adapted to various flow conditions and enables the study of endothelial lining, blood vessel sprouting, circulation of immune cells, pathogens or other particles, and incorporation of 3D cell models like organoids. Additionally, we have developed a computational model to predict shear stress and mass transport within the rOoC, allowing for customization of the platform for various use-cases.

The rOoC platform is very versatile and can be used to model for instance drug-induced liver-injury (DILI) that mimics the complex interaction between resident human stem cell-derived liver organoids (3D-HLO) and circulating immune cells. Moreover, we show the functional crosstalk between 3D-HLOs and human pancreatic islets to model the onset of type-2 diabetes.

Time and place: , NHA 723 and Online
Time and place: , Auditorium 4

Doctoral candidate Erik Habbestad at the Department of Mathematics will be defending the thesis C∗-algebras with quantum group symmetry -Noncommutative boundaries and equivariant subproduct systems for the degree of Philosophiae Doctor.

Time and place: , NHA B1120

Markus Spitzweck (Universität Osnabrück) will present the talk «Representation categories and motives».

Time and place: , Niels Henrik Abels hus, 9th floor

This seminar will consist of two separate presentations, each about 15-minute long.

1) Magnetic Quincke Rollers with tunable single particle dynamics and collective states
2) Electrically controllable ferrofluids

Time and place: , room 1259 (Abels Utsikt) - Niels Henrik Abels hus

Doctoral candidate Bastian Zapf at the Department of Mathematics will be defending the thesis Inverse mathematical modeling of solute transport in the human brain for the degree of Philosophiae Doctor.

Time and place: , Niels Henrik Abels hus, 9th floor
It is well known that if the singular values of a matrix are distinct, then its best rank-n approximation in the Frobenius norm is uniquely determined and given by the truncated singular value decomposition. On the other hand, this uniqueness is in general not true for best rank-n approximations in the spectral norm. In this talk we relate the problem of finding best rank-n approximations in the spectral norm to Kolmogorov n-widths and corresponding optimal spaces. By providing new criteria for optimality of subspaces with respect to the n-width, we describe a large family of best rank-n approximations to a given matrix. This results in a variety of solutions to the best low-rank approximation problem and provides alternatives to the truncated singular value decomposition. This variety can be exploited to obtain best low-rank approximations with problem-oriented properties.
We further discuss the generalization of these results to compact operators in L2, and explain how they can be used to both describe the out-performance of smooth spline approximations of solutions to differential equations when compared to classical finite element methods, and to solve the outlier-problem in isogeometric analysis.
This talk is based on work done in collaboration with Michael Floater, Carla Manni and Hendrik Speleers.
Time and place: , Niels Henrik Abels Hus and Zoom

This Stochastic Analysis and Applications Workshop aims to provide a professional platform for young researchers in stochastics from China and Norway to convene, exchange ideas, and potentially establish new collaborations.

Time and place: , Room 1119, Niels Henrik Abels hus

The Section 4 seminar for the Spring of 2023 will be held on Wednesdays at 10:15–12:00 (see the schedule)

Time and place: , NHA107

C*-algebra seminar talk by John Quigg (Arizona State University)

Time and place: , Niels Henrik Abels hus, 9th floor

I will discuss some of our recent results on active chiral and nematic membranes. The chiral stresses we consider give rise to a novel form of odd elasticity. To outline this phenomenology I will give explicit calculations outlining spontaneous flow transitions and shape instabilities. I will discuss the relevance of these results in developmental biology and their relation to active nematics, in particular how certain limits of active nematic membranes can reduce to a theory of an isotropic membrane with an active stress defined by the deviatoric part of the shape operator.

Time and place: , NHA107

C*-algebra seminar talk by Roberto Conti (Sapienza University of Rome)

Time and place: , NHA B1120

Many have tried to adapt Clemens and Griffiths's approach to irrationality of cubic threefolds to higher dimensions, using different invariants in place of H^3(X,Z): the transcendental part of H^4, derived categories, quantum cohomology... I will report on my attempt to use higher algebraic K-theory, which turns out to be strictly weaker than what Voisin and Colliot-Thélène have already gotten from Bloch-Ogus theory, but (I think) in an interesting way. For a positive result, I can show that the higher K-theory of Kuznetsov's K3 category for a cubic or Gushel-Mukai 4-fold looks the same as that of an honest K3 surface.