Scientific

Nutations in Growing Plant Shoots: Endogenous and Exogenous Factors in the Presence of Elastic Deformations

Speaker: 
Daniele Agostinelli
Date: 
Wed, Aug 4, 2021
Location: 
Zoom
Online
Conference: 
Mathematical Biology Seminar
Abstract: 

Growing plant shoots exhibit circumnutations, namely, oscillations that draw three-dimensional trajectories, whose projections on the horizontal plane generate pendular, elliptical, or circular orbits. A large body of literature has followed the seminal work by Charles Darwin in 1880, but the nature of this phenomena is still uncertain and a long-lasting debate produced three main theories: the endogenous oscillator, the exogenous feedback oscillator, and the two-oscillator model. After briefly reviewing the three existing hypotheses, I will discuss a possible interpretation of these spontaneous oscillations as a Hopf-like bifurcation in a growing morphoelastic rod.

Class: 

Theory of rational curves and its arithmetic applications: Lecture 3

Speaker: 
Brian Lehmann
Date: 
Wed, Aug 4, 2021
Location: 
Online
Conference: 
PRIMA 2021 Summer School: Rational curves and moduli spaces in arithmetic geometry
Abstract: 

We discuss deformation theory of rational curves and Mori’s famous Bend and Break techniques as well as their applications to Geometric Manin’s Conjecture. The lecture series contain introductory components as well as problem sessions and they aim for graduate students and postdocs.

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Subject: 

Brauer classes in moduli problems and arithmetic: Lecture 3

Speaker: 
Nicolas Addington
Date: 
Wed, Aug 4, 2021
Location: 
Online
Conference: 
PRIMA 2021 Summer School: Rational curves and moduli spaces in arithmetic geometry
Abstract: 

We cover Brauer classes, how they arise as obstructions on moduli spaces of sheaves, and how they can be used to obstruct rational points, highlighting recent links between the two.

Class: 
Subject: 

Theory of rational curves and its arithmetic applications: Lecture 2

Speaker: 
Brian Lehmann
Date: 
Tue, Aug 3, 2021
Location: 
Online
Conference: 
PRIMA 2021 Summer School: Rational curves and moduli spaces in arithmetic geometry
Abstract: 

We discuss deformation theory of rational curves and Mori’s famous Bend and Break techniques as well as their applications to Geometric Manin’s Conjecture. The lecture series contain introductory components as well as problem sessions and they aim for graduate students and postdocs.

Class: 
Subject: 

Brauer classes in moduli problems and arithmetic: Lecture 2

Speaker: 
Sara Frei
Date: 
Tue, Aug 3, 2021
Location: 
Online
Conference: 
PRIMA 2021 Summer School: Rational curves and moduli spaces in arithmetic geometry
Abstract: 

The Pacific Rim Mathematical Association Congress meets in December 2022. A number of summer schools will take place prior to the main event at the end of the year. This summer school is part of the PRIMA Special Session on Arithmetic geometry: theory and computation. In this summer school, we cover two topics:(1) Brauer classes in moduli problems and arithmetic and (2) theory of rational curves and its arithmetic applications.

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Subject: 

Theory of rational curves and its arithmetic applications: Lecture 1

Speaker: 
Brian Lehmann
Date: 
Mon, Aug 2, 2021
Location: 
Online
Conference: 
PRIMA 2021 Summer School: Rational curves and moduli spaces in arithmetic geometry
Abstract: 

We discuss deformation theory of rational curves and Mori’s famous Bend and Break techniques as well as their applications to Geometric Manin’s Conjecture. The lecture series contain introductory components as well as problem sessions and they aim for graduate students and postdocs.

Class: 
Subject: 

Brauer classes in moduli problems and arithmetic: Lecture 1

Speaker: 
Nicholas Addington
Sara Frei
Date: 
Mon, Aug 2, 2021
Location: 
Online
Conference: 
PRIMA 2021 Summer School: Rational curves and moduli spaces in arithmetic geometry
Abstract: 

We cover Brauer classes, how they arise as obstructions on moduli spaces of sheaves, and how they can be used to obstruct rational points, highlighting recent links between the two.

Class: 
Subject: 

Environmental Escape from the Prisoner's Dilemma

Speaker: 
Jaye Sudweeks
Date: 
Wed, Jul 28, 2021
Location: 
Zoom
Online
Conference: 
Mathematical Biology Seminar
Abstract: 

During reproduction, viruses manufacture products that diffuse within the host cell. Because a virus does not have exclusive access to its own gene products, coinfection of multiple viruses allows for strategies of cooperation and defection— cooperators produce large amounts of gene product while defectors produce less product but specialize in appropriating a larger share of the common pool. Experimental data shows that, under conditions where coinfection is common, bacteriophage Φ6 becomes trapped in a Prisoner’s dilemma, with defectors spreading to fixation, causing lowered population fitness. However, these experiments did not allow for fluctuation in the density of the external viral population. Here, I’ll discuss a model formulated to see if environmental feedback can free Φ6 from the Prisoner’s dilemma. I’ll also discuss the concept of the Effective Game, which incorporates the frequency and density of different viral types in the environment.

Class: 

Random walks on Gromov hyperbolic spaes and Teichmüller spaces. Pacific Dynamics Seminar

Speaker: 
Inhyeok Choi
Date: 
Thu, Jul 22, 2021
Location: 
Online
Zoom
Conference: 
Pacific Dynamics Seminar
Abstract: 

n this talk, I will discuss random walks on Gromov hyperbolic spaces. Due
to the hyperbolicity of the spaces, random walks exhibit behaviors that
differ from the classic (Euclidean) ones. These behaviors include the
escape to infinity, central limit theorems when centered at the escape
rate, and geodesic tracking. I will explain how one can sharpen these
behaviors based on the recent observations by Gouëzel and Baik-Choi-Kim. If
time allows, I will also explain how one can implement this theory on
(non-hyperbolic) Teichmüller spaces.

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Subject: 

Dynamic Self Organization and Microscale Fluid Properties of Nucleoplasm

Speaker: 
Jay Newby
Date: 
Wed, Jul 21, 2021
Location: 
Zoom
Online
Conference: 
Mathematical Biology Seminar
Abstract: 

The principal function of the nucleus is to facilitate storage, retrieval, and maintenance of the genetic information encoded into DNA and RNA sequences. A unique feature of nucleoplasm—the fluid of the nucleus—is that it contains chromatin (DNA) and RNA.

In contrast to other important biological polymer hydrogels, such as mucus and extracellular matrix, the nucleic acid polymers have a sequence. Recent experiments have shown that during the growth phase of the cell cycle, chromatin condenses in a sequence specific manner into regions within the nucleoplasm, possibly so that functionally related genes are grouped together spatially even though they might be far apart in terms of sequence distance.

At the same time, we are becoming increasingly aware of the role of liquid-liquid phase separation (LLPS) in cellular processes in the nucleus and the cytoplasm. Complex molecular interactions over a wide range of timescales can cause large biopolymers (RNA, protein, etc) to phase separate from the surrounding nucleoplasm into distinct biocondensates (spherical droplets in the simplest cases).

I will discuss recent work modelling the role of nuclear biocondensates in neurodegenerative disease and several ongoing projects related to
modelling and microscopy image analysis.

Class: 

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