UBC Math

Fri 27 Nov 2015, 3:00pm
Department Colloquium
MATX 1100

Pathwaycentric modeling of microbial ecosystems (Graduate Research Award Colloquium)

MATX 1100
Fri 27 Nov 2015, 3:00pm4:00pm
Abstract
New molecular techniques such as DNA sequencing provide conceptual insights into microbial community metabolism and biogeochemical cycling in natural and engineered ecosystems. However, attempts to mechanistically integrate molecular data with biogeochemistry are faced with the inhibitory complexity of individual cells and a large number of unknown physiological parameters. Recent work suggests that biochemical pathways are, at ecosystem scales, strongly shaped by thermodynamic and stoichiometric constraints. Pathwaycentric mathematical theories rooted in fluxes of matter and energy could thus provide holistic insight into microbial ecosystems and global biogeochemical fluxes.
Oxygen minimum zones (OMZ) are oxygendepleted regions in the ocean that are dominated by microbial metabolism, thus constituting ideal systems for developing theories of microbial ecology. I will present our current efforts to model the biogeochemistry of an intensely studied OMZ off the coast of Vancouver Island using reactionadvectiondiffusion models. In contrast to conventional approaches, we focus on individual enzymes catalyzing metabolic pathways and assume that energy fluxes translate directly to gene expression and biosynthesis. We use DNA, mRNA and protein sequence data, as well as geochemical depth profiles and process rate measurements to calibrate and validate our models.
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Mainz

Fri 4 Dec 2015, 3:00pm
Department Colloquium
MATX 1100

Counting curves  complex and tropical

MATX 1100
Fri 4 Dec 2015, 3:00pm4:00pm
Abstract
A curve is called rational if it can be parametrized by rational functions. Counting the number of rational curves in the plane that contain a given number of points has been an old and interesting problem. The degree of a curve is the degree of a polynomial equation defining it. We all know that there is only one curve of degree one through any given pair of points in the plane because this is just a straight line. The answer to similar questions for higher degrees quickly becomes more difficult and interesting. To simplify the problem, one may map a curve in the complex twospace to the real twospace by applying a componentwise absolute value and logarithm. The resulting object is for good reasons called an amoeba  I will show some pictures. The amoeba retracts to its spine which is a much simpler convexgeometric object that is also called a tropical curve. Such can be counted essentially by hand. A proof that the resulting counts coincide with the original problem goes via a recent theory of logarithmic GromovWitten invariants.
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University of Iowa

Fri 15 Jan 2016, 3:00pm
Department Colloquium
MATH 1100

TBA

MATH 1100
Fri 15 Jan 2016, 3:00pm4:00pm
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Princeton University

Fri 26 Feb 2016, 3:00pm
SPECIAL
Department Colloquium / PIMS Seminars and PDF Colloquiums
ESB 2012

TBAPIMS/UBC Distinguished Colloquium

ESB 2012
Fri 26 Feb 2016, 3:00pm4:00pm
Abstract
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UC Berkeley

Fri 4 Mar 2016, 3:00pm
SPECIAL
Department Colloquium
ESB 2012

PIMS Hugh Morris Lecture

ESB 2012
Fri 4 Mar 2016, 3:00pm4:00pm
Abstract
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Harvard University

Fri 18 Mar 2016, 3:00pm
SPECIAL
Department Colloquium / PIMS Seminars and PDF Colloquiums
ESB2012

PIMSUBC Distinguished ColloquiumTBA

ESB2012
Fri 18 Mar 2016, 3:00pm4:00pm
Abstract
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Courant Institute, NYU

Fri 1 Apr 2016, 3:00pm
SPECIAL
Department Colloquium
ESB2012

PIMSUBC Distinguished ColloquiumTBA

ESB2012
Fri 1 Apr 2016, 3:00pm4:00pm
Abstract
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