Physics and Astronomy Calendar

Week of Monday, April 24th 2017

Monday, April 24th 2017
12:15 pm:
Speaker: Evan Skillman, UMN
Subject: Carbon

I will report on recent measurements of carbon abundances from optical recombination lines of star forming regions in the spiral galaxy M101 obtained with the Modular Double Spectrograph on the Large Binocular Telescope. These observations allow us to study the evolution of the relative abundance of carbon as a function of absolute abundance.

4:40 pm:
Speaker: Bryan Chem
Subject: Computational Studies of Defect Mediated Transport
Faculty Host: Paul Crowell

Tuesday, April 25th 2017
12:20 pm:
There will be no seminar this week.
4:30 pm:
There will be no seminar this week.

Wednesday, April 26th 2017
1:25 pm:
Speaker: Turan Birol, CEMS, University of Minnesota
Subject: Correlated Materials by Design

The process of materials design involves solving the inverse band structure problem to predict what stoichiometry and crystal structure give rise to desired properties. First principles methods, such as Density Functional Theory (DFT), are used extensively to predict/design novel materials, from ferroelectrics to high temperature superconductors. In this talk, I am going to discuss my materials design efforts using Dynamical Mean Field Theory (DFT+DMFT), which is the state of the art first principles method to approach on-site electronic correlations in transition metal systems. In particular, I am going to start with discussing a novel group of J=1/2 fluoro-iridates, and then move on to efforts of designing superior transparent conductors by taking advantage of the electronic correlations in the well known perovskite oxide strontium vanadate.

Faculty Host: Rafael Fernandes
Paper Reading

Title: Charged Lepton Violation (theory paper)
Author: Andrea de Gouvea, Northwestern Physics Dept
Topics: Model Independent CLFV, Exotic Models and production at LHC

4:30 pm:
CM Journal Club in PAN 120
Subject: There will be no CM Journal club

Thursday, April 27th 2017
10:10 am:
Biophysics Seminar in 120 PAN
Speaker: Prof. Julius Lucks, Northwestern University
Subject: Uncovering How RNA Molecules ‘Make Decisions’ On the Fly: Towards Understanding and Engineering Cotranscriptional RNA Folding

RNAs are emerging as a powerful substrate for engineering gene expression and cellular behavior since they are now known to control almost all aspects of gene expression. As with all biomolecules, RNA function is intimately related to its structure, since RNA can adopt structures that selectively modulate gene expression. Central questions in biology and bioengineering then are: How do RNAs fold inside cells?; and How can we engineer these folds to control gene expression? In this talk, I will present our work at the interface of these two questions and share results that are beginning to uncover design principles for understanding natural RNAs and engineering RNAs for an array of applications.

I will start by presenting our work on engineering RNA molecular switches that control transcription. The desire to uncover design principles for engineering these RNAs motivates our development of SHAPE-Seq, a technology that couples chemical probing with next-generation sequencing and that helps characterize RNA structures on an ‘omics’ scale. I will then describe our exciting recent developments in using SHAPE-Seq to help break open one of the frontiers of RNA structure-function relationships by uncovering at nucleotide resolution how RNAs fold cotranscriptionally. Specifically I will highlight new data on uncovering the ligand-dependent folding pathways of riboswitches, and how we are beginning to use these datasets to computationally reconstruct cotranscriptional folding pathways. This new ability is allowing us to ask deep questions about how RNA molecules make regulatory decisions ‘on the fly’ during the dynamic process of transcription. By probing the fundamental processes of RNA folding and function, these studies are expected to greatly aid RNA engineering.

Speaker: Jett Priewe and Claudia Scarlata
1:00 pm:
Speaker: Jingnan Cai
Subject: Crystal Growth and Seebeck Coefficient Measurement of Hg1201
Faculty Host: Paul Crowell
3:35 pm:
Speaker: Adriano Fontana, National Institute for Astrophysics (Italy)
Subject: The Large Binocular Telescope from first stars to exoplanets: challenges and results.
Refreshments to be served outside Smith 100 after the colloquium.

Modern-day astrophysics is facing many outstanding scientific questions.
They include the nature of the first stars and galaxies, the physics of the assembly and evolution of massive galaxies, the constraints to dark matter and cosmological model, the demographics of exoplanets and the physics of planet formation.

Progress in these fields is often driven by technological developments. Thanks to a wealth of new instrumentation that will become available in the very next years, we expect to be able to address or to make substantial advances toward the solution of most of these problems.

Crucially, key new technologies in the optical domain involve the use of adaptive optics for ground based telescopes, of which the Large Binocular Telescope is a world-leader.

In my talk I will briefly illustrate some of the “big” scientific questions that are on the table - at least in my personal and biased view - and then present the new technologies and instrumentation -mostly of which developed at LBT - that promise to revolutionize the field in a decade, including some early results from LBT.

Faculty Host: Roberta Humphreys

Friday, April 28th 2017
11:15 am:
There will be no seminar this week.
Speaker: Sajna Hameed, University of Minnesota
Subject: Magnetic Order and Excitations in Y1-xLaxTiO3
Faculty Host: Martin Greven
Speaker: Antonio Delgado, (Notre Dame U.)
Subject: TBA
Subject: No MIfA speaker this week. See the SPA colloquium April 27th
Adriano Fontana, Nat'l Institute for Astrophysics (Italy)
Speaker: Jessica Riskin, Stanford University
Subject: "How the Mouse Lost its Tail, Or, Lamarck's Dangerous Idea"
Refreshments served at 3:25 p.m.

The clockwork cosmos of early modern science was a passive and static thing, its shape imposed by an external designer, its movements originating outside itself. The classical mechanists of the seventeenth century evacuated force and agency from the cosmos, including, for the most part, from its living inhabitants, to the province of a supernatural Clockmaker. They thereby built a kind of supernaturalism into the very structure of modern science. But not everyone concurred in this banishment. From the late seventeenth century onward, a tradition of dissenters embraced the opposite principle, that agency -- a capacity to act, to be self-making and self-transforming -- was essential to nature, especially living nature. A crucial member of this dissenting, active-mechanist tradition was the French naturalist Jean-Baptiste Lamarck, professor of natural history at the Muséum national d’histoire naturelle in Paris. This paper examines his rigorously naturalist approach -- which naturalized rather than outsourced agency -- and its exile from the halls of mainstream science.

Lamarck was the leading author of two major, related ideas: first, the term “biology” and the idea of biology as a distinct science of life, and second, the idea of species-change, what we would now call “evolution,” but I will call it “transformism” to avoid reading aspects of later theories back into these early ideas about species-change. In 1802, Lamarck defined “biology” as one of three parts of “terrestrial physics,” the part comprehending everything to do with living bodies, especially their organization and its “tendency to create special organs.” In other words, the idea that living things composed and transformed themselves was central to this original definition of “biology.”

The paper will examine the political history of these conjoined ideas, transformism and a science devoted to its study, which carried with them an atmosphere of materialism, radicalism and anti-clericalism. This atmosphere became especially troubling toward the end of the nineteenth century to people such as the German Darwinist biologist August Weismann, who offered a definitive new interpretation of Darwinism that eliminated any whiff of Lamarckism. He and other neo-Darwinists were so successful that even today, Lamarck’s name is still in bad odor. His ideas themselves cannot tell us why; only their history can do that.

Co-sponsored with the Consortium for the Study of the Premodern World and the Anselm House.

3:35 pm:
Speaker: Vikram Nagarajan
Subject: Antiferromagnetic Excitations in Underdoped HgBa_2CuO_(4+delta)
Faculty Host: Paul Crowell
Group presentations #1
4:40 pm:
There will be no seminar this week.

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