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Colloquium

Unless otherwise noted, the physics colloquia are held in Room 307 of the Science and Engineering Research Facility. Refreshments are served at 3:00 p.m. with the talk following at 3:30.

Fall 2019 Schedule
Date
Speaker
Title
Host

August 26

Karen Lloyd
University of Tennessee

A Thermodynamic Quirk in Marine Sediments May Explain Why We're Not All Suffocating in Methane Right Now

Kate Jones

September 9

Lucas Platter
University of Tennessee Department of Physics

Forthcoming

Mike Guidry

September 16

Royce Zia
Virginia Tech

Non-equilibrium Statistical Mechanics: a Growing Frontier of "Pure and Applied" Theoretical Physics

Max Lavrentovich

September 23

Kelly Holley-Bockelmann
Vanderbilt University

Forthcoming

Anthony Mezzacappa

September 30

Douglas Higinbotham
Jefferson Lab

Forthcoming

Nadia Fomin

October 7

Lance Cooper
University of Illinois Urbana-Champaign

Forthcoming

Haidong Zhou

October 14

Sung-Kwan Mo
Lawrence Berkeley National Laboratory

Forthcoming

Norman Mannella

October 21

Andrew Steiner
University of Tennessee Department of Physics

Determining the Properties of Dense Matter from Neutron Star Observations

Mike Guidry

October 28

Erik van Heumen
University of Amsterdam

Forthcoming

Steve Johnston

November 4

Ian Cloët
Argonne National Laboratory

Forthcoming

Lucas Platter

November 11

Manas Mukherjee
National University of Singapore

Forthcoming

Alfredo Galindo-Uribarri

November 18

TBA

 

 

November 25

K C Huang
Stanford University

Model Systems for Microbial Ecology

Jaan Mannik

December 2

Megan Connors
Georgia State University

Forthcoming

Christine Nattrass


Abstracts

August 26

Karen Lloyd, University of Tennessee
A Thermodynamic Quirk in Marine Sediments May Explain Why We're Not All Suffocating in Methane Right Now

Most of the microbes buried in marine sediments have never been cultured in a laboratory, so we must design experiments to test their physiology without removing them from their natural settings. A type of archaea, called ANME-1 have been shown to oxidize methane anaerobically in a consortium with sulfate reducing bacteria through a mechanism that has not been fully characterized. However, since ANME-1 survive on very low energies, theory predicts that they should reverse their metabolism to methanogenesis when the reaction becomes exergonic in that direction. We found evidence that this occurs in the White Oak River estuary, and a re-analysis of some published literature supports our conclusions. This nimble switching between methanogenesis and anaerobic methane oxidation in natural settings suggests that, despite being relatively slow growers, these organisms are well-poised to adapt their metabolism quickly to environmental changes. The fact that they get energy from both the forward and reverse directions of a single metabolism, depending on the exergonicity of the chemical reaction, may explain how they are able to consume 99% of the vast quantity of methane that is microbially produced in marine sediments.


September 16

Royce Zia, Virginia Tech
Non-equilibrium Statistical Mechanics: a Growing Frontier of "Pure and Applied" Theoretical Physics

Founded over a century ago, statistical mechanics for systems in thermal equilibrium has been so successful that, nowadays, it forms part of our physics core curriculum. On the other hand, most of "real life" phenomena occur under non-equilibrium conditions. Unfortunately, statistical mechanics for such systems is far from being well established. The goal of understanding complex collective behavior from simple microscopic rules (for how the system evolves, say) remains elusive. As an example of the difficulties we face, consider predicting the existence of a tree from an appropriate collection of H,C,O,N,... atoms! Over the last three decades, an increasing number of condensed matter theorists are devoting their efforts to this frontier. After a brief summary of the crucial differences between text-book equilibrium statistical mechanics and non-equilibrium statistical mechanics, I will give a bird's-eye view of some key issues, ranging from the "fundamental" to the "applied." The methods used also span a wide spectrum, from simple computer simulations to sophisticated field theoretic techniques. These will be illustrated in the context of an overview of our work, as well as one or two concrete examples.


September 25

K C Huang, Stanford University
Model Systems for Microbial Ecology

The past decade has seen an explosion in characterization of how microbial communities impact human health and the environment. Yet, our understanding of the molecular mechanisms driving community assembly, dynamics, and resilience has lagged far behind. I will discuss two of our efforts to develop "model communities" for microbiome research. First, we use the simple bacterial community in fly guts to uncover connections between growth, pH, and antibiotic sensitivity. Second, we use a top-down approach to derive stable, complex communities from human stool that exhibit colonization resistance to pathogens, robustness to antibiotic perturbation, and stability over months of passaging. I will end with a discussion of how these approaches can impact studies of other microbial ecosystems.


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