Physics and Astronomy Calendar

Week of Monday, March 26th 2018

Monday, March 26th 2018
12:15 pm:
Speaker: Liliya L.R. Williams, UMN

Tuesday, March 27th 2018
Speaker: Michael Fogler, University of California, San Diego
Faculty Host: Boris Shklovskii

Wednesday, March 28th 2018
1:25 pm:
Speaker: Paul Canfield (Iowa State)
Subject: TBD
Faculty Host: Martin Greven
3:30 pm:
Space Physics Seminar in Physics 201-20
Speaker: Barry Mauk, APL
Subject: TBD
Faculty Host: Robert Lysak

Thursday, March 29th 2018
10:10 am:
Biophysics Seminar in 120 PAN
Speaker: Casim Sarkar, Professor of Biomedical Engineering, University of Minnesota
Subject: Integrating experimental and computational approaches to elucidate mechanisms of binding in multivalent proteins

Multivalent proteins are ubiquitous in nature and can provide unique, exploitable properties in therapeutic applications such as increased affinity or multi-target specificity. Despite the importance of these proteins in fundamental and applied biomedical research, mechanistic quantitative descriptions of their binding kinetics are limited. We have considered such multivalent protein-protein interactions to be driven by three key variables: the binding affinity of individual monomer units, the linker length/structure between the monomers, and the overall valency of each multivalent protein. Using model synthetic proteins in which all three of these variables can be independently tuned, we have performed surface plasmon resonance experiments to quantify the kinetics of association and dissociation as a function of affinity, linker, and valency. In parallel, we developed a mechanistic model based on mass-action kinetics that explictly enumerates all possible microstates that participate in the binding reaction. Integration of these quantitative experimental and computational approaches has elucidated a number of interesting findings, including the role of valency in generating non-canonical reaction kinetics, that will be discussed. Our approach should enable better understanding of dynamic behaviors in natural multivalent proteins and lead to more rational optimization of multivalent therapeutics.

Speaker: Brian O'Neill
3:35 pm:
Speaker: Barry Mauk, APL
Subject: New perspectives on Jupiter’s novel space environment and aurora from NASA’s Juno mission

B. H. Mauk, The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland, USA (

Jupiter’s uniquely powerful auroras are thought to be symptoms of Jupiter’s attempt to spin up its space environment and shed angular moment (albeit minuscule amounts). The processes involved connect together such disparate phenomena as the volcanoes of Jupiter’s moon Io and the Jupiter-unique synchrotron emissions imaged from ground radio telescopes at Earth. While the power sources for auroral processes at Earth and Jupiter are known to be very different, it has been expected that the processes that convert that power to auroral emissions would be very similar. NASA’s Juno mission, now in a polar orbit at Jupiter, is dramatically altering this view about how Jupiter’s space environment operates. Auroral processes are much more energetic than expected, generating beams of electrons with multiple MeV energies and with directional intensities that can be more intense than the electrons within Jupiter’s radiation belts. The most intense auroral emissions appear to be generated by processes that have no precedent within Earth auroral processes. And, the auroral generation processes are poorly correlated, unexpectedly, with any large-scale electric currents thought necessary to regulate the interactions between Jupiter’s spinning atmosphere and space environment. These and other findings are discussed, along with presentation of Juno’s broader mission and discoveries.

Faculty Host: Robert Lysak

Friday, March 30th 2018
Speaker: Hooman Davoudiasl (Brookhaven)
Subject: TBA
Speaker: Lou Stolger, Space Telescope
Subject: The Rates of Supernovae, Far and Near

For nearly two decades, the Hubble Space Telescope has been heavily used to locate supernovae in high redshift environments, with the primary goal of improving constraints on the nature of dark energy. Along the way we have made surprising observations on the nature of supernovae themselves, and clues to their elusive progenitor mechanisms, some of which are difficult to reconcile with observations at much lower redshift. From complete volumetric supernova rate histories that now extend to z > 2 we find type Ia supernova delay-time distributions are consistent with a power law index of -1, but with the fraction of prompt (t_d < 500 Myr) is less than expected from various ground-based surveys. Core collapse supernova rates trace the cosmic star formation rate history, but require stellar progenitors more massive than has been seen in deep studies of nearby events (M > 20 M_sol). I’ll detail some interesting discoveries from our recent campaigns on clusters of galaxies, and also discuss what we expect to find with the James Webb Space Telescope, launching in 2018, and with WFIRST in the 2020s.

Speaker: Susan Rensing, Department of Women's & Gender Studies, University of Wisconsin - Oshkosh
Subject: HSTM Alumni Lecture - "‘A Coldly Scientific Venture’: Unwed Mothers and the Eugenic Baby Panic"
Refreshments served at 3:15 p.m.

In January of 1928, the New York World set off a firestorm of controversy with a front page story about a wealthy widow, Grace Burnham, who had “mated lovelessly” as a eugenic experiment. Newspapers rushed to seek out stories of other women who were conceiving eugenic babies by selecting a man purely for reproduction, not for marriage. Unlike the wholesome eugenic babies that won ribbons in Better Baby Contests at state fairs, these eugenic babies were portrayed as potential Frankensteins--creations of science run amok. Moral condemnation raged in editorials across the nation as experts weighed in with their opinions about this alarming trend. This talk will use the eugenic baby panic as a cultural lens to examine fears about science bereft of morality in the late 1920s and early 1930s.

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