Piotr Marszalek, Duke University

Nanomechanics of Biopolymers Beyond Their Entropic Elasticity Regime

Compared to other single-molecule techniques, AFM-based force spectroscopy uses stiff force transducers and it may apply large stretching forces to molecules, enabling their structural modifications and capturing high energy conformations that cannot be examined by (for example) X-ray crystallography or NMR. In my talk, I will present our AFM stretching and relaxation studies, supported by computer simulations of individual molecules of DNA and proteins.

Professor Naomi McClure-Griffiths, Professor at the Research School of Astronomy & Astrophysics in the College of Science – Australian National University

The Milky Way and Magellanic Clouds as Laboratories for Understanding the Evolution of Galaxies

Galaxies are not closed box systems. Their evolution is impacted by gas accreted via inflow, gas lost from the disk via large-scale outflows and gas circulations via the halo. Many simulations of galaxy formation and evolution have highlighted the importance of feedback in reproducing the observable Universe. In this talk, I will present an overview of observational evidence for outflows within the Milky Way and Magellanic Clouds.

Daniel J. Kennefick, University of Arkansas

No Shadow of Doubt: The 1919 Eclipse and General Relativity

This is the centenary year of the celebrated eclipse expeditions of 1919 which confirmed Einstein's theory of General Relativity. In recent decades, the story of these expeditions has focused on Arthur Stanley Eddington and the question of his alleged bias in favor of Einstein’s theory. It has been alleged that Eddington threw out data which did not favor Einstein’s theory.

There is no Physics colloquium currently scheduled for this date.

Goutam Sheet, Dept. of Physical Sciences, Indian Institute of Science Education & Research (IISER)

Tip-induced Superconductivity

It has been recently observed that certain novel phases of matter, like superconductivity, emerge at mesoscopic interfaces between elemental metals and topologically nontrivial systems such as topological insulators and topological Dirac and Weyl semimetals. In this talk, I will review some of our published results on such mesoscopic superconducting phases with special emphasis on tip-induced superconductivity (TISC). A TISC phase is known to emerge under the point of contact between a sharp tip of a (non-superconducting) normal metal and a material with topologically non-trivial band structure.

Andrew Baker, Rutgers University

Dusty Star-Forming Galaxies at High Redshift
Interstellar dust grains can collectively scatter, redden, and attenuate the light from a galaxy's stars-- in some cases, so effectively that a galaxy can become nearly undetectable at rest-frame ultraviolet and optical wavelengths. Starting in the late 1990s, astronomers have come to understand that luminous but optically obscured systems are much more prevalent at high redshifts (i.e., earlier times) than in the local universe, and that they make important contributions to the overall history of cosmic star formation.

Mark C. Williams, Northeastern University

How Proteins Use Thermodynamics to Fight Over DNA

Optical tweezers allow us to probe the interactions of proteins with single DNA molecules and apply very small forces. Measurement of force-dependent DNA conformations allows us to quantify interactions that govern cellular function. DNA forms a stable double-helix in order to store the genetic information for most organisms. However, in the process of replicating an organism’s genome, the two strands of the helix must be separated to form single-stranded DNA (ssDNA). This intermediate state is vulnerable to interference from many cellular processes and is therefore tightly regulated.

No colloquium this week - Dr. Narae Kang has been rescheduled for 4 October 2019.

Dr. Narae Kang, Intel Corp.

Design, Fabrication, and Characterization of Nanoelectronic Devices: From Carbon Nanotubes to Graphene, and Beyond

Fabrication of high-performance electronic devices using novel semiconductors is essential for developing future electronics applications such as large-area, flexible and transparent displays, sensors and solar cells. In the first part of my talk, I will discuss the fabrication of nanoelectronic devices and investigation of their transport properties using carbon nanotubes (CNTs) and graphene as electrode materials.

Dan Milisavljevic, Purdue University

Multi-messenger Autopsies of Stellar Death

The expanding zoo of astronomical transients has become one of the most important driving forces of scientific discovery in extreme astrophysics. Increasingly sophisticated all-sky surveys are uncovering unexpected phenomena that are forcing radical revisions to long accepted models of massive star evolution and their compact remnant objects. These discoveries, which will increase by orders of magnitude in the upcoming decade, are shaping the priorities of the next generation of science facilities such as the Large Synoptic Survey Telescope and Extremely Large Telescopes.