### Monday, March 14

**MSCS Colloquium**: *Estimating temporal associations in electrocorticographic (ECoG) time series
*Haley Hedlin, ’06, Ph.D Senior Biostatistician, Stanford Medicine

Granger causality (GC) is a statistical technique used to estimate temporal associations in multivariate time series. Many applications and extensions have been proposed since its formulation by Granger in 1969. Here we apply Granger causality in the context of electrocorticography (ECoG), also known as intracranial electroencephalography. A pruning approach to remove spurious connections and simultaneously reduce the required number of estimations to fit the functional connectivity graph is proposed. This approach overcomes limitations encountered when estimating many parameters in multivariate time series data, an increasingly common predicament in today’s brain mapping studies.

3:30pm, RNS 310 –

*Individual mini-pies will be served*in celebration of Pi Day with conversation at 3:15pm.

**Biology Seminar: ***Scavenger – how a starving bacterium takes up scarce nutrients.*

Professor Lisa Bowers

Caulobacter crescentus is a species of bacteria that lives in water everywhere. It’s well known as a scavenger due to its ability to take up scarce nutrients. It has many

interesting adaptations that allow it to thrive in low nutrient environments, including an unusually large group of surface proteins called TonB-dependent receptors (TBDRs) that

actively bind and transport nutrients into the cell. For a long time, TBDRs were thought to transport only iron complexes and Vitamin B12 but now we know iron and B12

represent just the tip of the iceberg. Recent studies have identified many novel substrates yet most of Caulobacter’s 65 TBDRs are still uncharacterized. What are the

other TBDRs doing? We are investigating a subset of TBDRs and are hot on the trail as we test our hypotheses with RT-qPCR, gene knockouts, and growth assays.

4:00 PM, RNS 410

### Tuesday, March 15

**No Seminars**

### Wednesday, March 16

**Physics Colloquium**: *Subsurface Waves in the Oceans and Lake Superior**
*Sam Kelly, Assistant Professor, Large Lakes Observatory and Dept. of Physics, University of Minnesota Duluth

2:00 pm, RNS 210

**MSCS – The Pi Mu Epsilon Spring lecture: ***Matrix Factorizations and Singularities of Hypersurfaces
*Kosmos Diveris, Assistant Professor of Mathematics, St. Olaf College.

Algebraic geometers study geometric objects defined by polynomial equations, like the unit sphere in R3 which is defined by x 2+y 2+z 2 = 1. A lot of interesting geometry is encoded in algebraic properties of these polynomials. In this talk we will discuss what factoring of polynomials can tell us about geometric objects, and explain how one can “factor” irreducible polynomials using matrices. These matrix factorizations, introduced by David Eisenbud in 1980, play a central role in the study of singularities of hypersurfaces and are an active area of research today.

4pm, RNS 208 –

*Shamrock Shakes*will be served at 3:45pm.

### Thursday, March 17

**No Seminars**

### Friday, March 18

**No Seminars**