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Winter 2019 Colloquium Series

Date:  Thursday, March 14, 2019
Speaker: Matt Anderson, San Diego State University

Title: The Learning Glass Project

Abstract: The Learning Glass was developed out of necessity.  Many online courses were suffering from a lack of personality, and in an effort to put the professor’s face back in the picture, Dr. Anderson developed a transparent whiteboard lecture capture system called Learning Glass.  With this system, students are able to observe the nuances of problem solving as their professor teaches complex principles while facing them. And the instructor is not required to write backwards! The writing becomes forward with a simple horizontal “flip” of the image. Learning Glass has now been adopted by institutions across the world in a variety of pedagogical approaches: online courses, hybrid online, supplemental material for face to face, peer instruction, flipped classes, auditorium face to face, etc.  Dr. Anderson will speak about this new technology, pilot studies underway to study its effectiveness at engaging students, and his experience using Learning Glass in his physics courses. (Hint: teaching the Right Hand Rule is challenging!)
He will also bring a portable Learning Glass to this lecture and it will be available for people to try out after the talk.

Host:  Mike Raymer

 

Date:  Thursday, March 7, 2019
Speaker: Carol Paty, UO Earth Sciences

Title: Probing the Interior of Europa: Magnetic Fields and Plasma and Radio Waves, Oh My!

Abstract: Beginning with Galileo in 1610, the Jovian system of worlds has inspired us and provided a rich environment for paradigm change and discovery. The diversity of characteristics represented in the moons of Jupiter require an equally diverse approach for observing and understanding their evolution and inner workings.

In this lecture we examine the relatively recent suite of observations of Europa, from the in situ Voyager and Galileo missions to the more recent remote observations made by the Hubble Space Telescope. This assemblage of information leads us to contemplate the potential habitat residing beneath Europa’s icy shell, and over the last two decades this thinking has evolved into the Europa Clipper mission. We will discuss this exciting mission in terms of the instrumentation that will cooperatively and collaboratively explore what lies beneath the surface of Europa.

Host:  Ray Frey

 

Date:  Thursday, February 28, 2019
Speaker: John Toner, University of Oregon

Title:  The Physics of a(n asymmetric) piece of paper

Abstract:  I’ll describe the theory of inversion-asymmetric tethered membranes (e.g., Christmas wrapping paper). These exhibit a new “double-spiral“ phase not present in symmetric membranes, in which the membrane assumes a universal algebraic spiral shape. This state exhibits a type of infinite thermal expansion coefficient. Like flat tethered membranes, it can also crumple; indeed, the asymmetry can drive the crumpling. In-vitro experiments on lipid-red blood cell membrane extracts, and on graphene coated on one side, could test these predictions.

 

Date:  Thursday, February 21, 2019
Speaker: Vincenzo Vitelli, Department of Physics and James Franck Institute, University of Chicago

Title: Odd Elasticity

Abstract: Hooke’s law states that the deformations or strains experienced by an elastic object are proportional to the applied forces or stresses. The number of coefficients of proportionality between stress and strain, i.e. the elastic moduli, is constrained by energy conservation. In this talk, we generalize continuum elasticity to active media with non-conservative (or non-reciprocal) microscopic interactions.
This generalization, which we dub odd elasticity, reveals that two additional elastic moduli can exist in a two-dimensional isotropic solid with strain dependent activity.
Such an odd-elastic solid can be regarded as a distributed engine: work is locally extracted, or injected, during quasi-static cycles of deformation. By coarse graining illustrative microscopic models, we show how odd elasticity emerges in active metamaterials composed of springs that actuate internal torques in response to strain. Analytical predictions, corroborated by simulations, uncover phenomena ranging from activity-induced auxetic behavior and buckling to wave propagation powered by self-sustained active elastic cycles. Our work suggests a path towards designing emergent robots that simultaneously harvest energy, transmit it using odd mechanical waves and perform work at designated sites

Host: Jayson Paulose

 

Date:  Thursday, February 14, 2019
Speaker: Leif Karlstrom,  UO, Department of Earth Sciences

Title: The fluid and solid mechanics of volcanoes, as illuminated by recent activity at Kilauea, Hawaii

Abstract:  Volcanic eruptions represent the final stage of ascent for magma generated deep in the Earth’s mantle. Because this magma ascent occurs over a broad range of scales (>12 orders of magnitude in space and time), much of which is outside the realm of direct observation, fundamental unanswered questions remain about how volcanoes work. Kilauea volcano, Hawaii, is a laboratory for studying these questions: many decades of research and one of the best geophysical sensor networks on Earth provide an outstanding platform for discovery and hypothesis testing. I will describe ongoing work to integrate physics-based models for magma ascent and storage with geophysical observations of volcanic activity at Kilauea over the past decade, including developments related to the explosive summit eruptions that occurred in May 2018. By integrating fluid and solid mechanics models with rigorous data inversion techniques, my group is working to place new constraints on volcanic processes from the millimeter-scale of bubble dynamics to the kilometer-scale of magma reservoirs and conduits.

Host:  John Toner

 

Date:  Thursday, February 7, 2019
Speaker: Sowjanya Gollapinni, University of Tennessee

Title:  Neutrinos: Tiny Particles, Big Science!

Abstract: Neutrinos provide a promising window to probe a wide range of fundamental physics. Neutrino related discoveries in the last two decades indicate that the answer to the most sought after question of why we live in a matter-dominated universe maybe within reach. Although more than a trillion of neutrinos pass unnoticed through our bodies every second, they still remain largely mysterious. These ghostly little particles are notoriously difficult to detect given how rarely they interact with matter and require building immense and exquisitely sensitive detectors. The Deep Underground Neutrino Experiment (DUNE) is a long baseline neutrino oscillation experiment at Fermilab and South Dakota with primary goals of resolving the neutrino mass ordering and measuring the charge-parity violating phase, the indicator of a possible explanation for our matter dominated universe. DUNE will use the promising liquid argon time projection chamber (LArTPC) technology as it presents neutrino interactions with unprecedented detail. However, the path to DUNE is technologically very challenging as it will be the biggest, most intense neutrino experiment ever to be built. After briefly reviewing the current state of neutrino physics, open questions and recent results from accelerator-based neutrino oscillation experiments, this talk will describe the DUNE experiment along with the rich physics that it offers and highlight some of the challenges involved in realizing such an experiment.

Host: Stephanie Majewski

 

Date:  Thursday, January 31st, 2019
Speaker: Steve Kevan, Director, Advanced Light Source, Lawrence Berkeley National Laboratory, (and on leave from UO Physics)

Title: A Bright Future for Soft X-ray Science

Abstract: Plans are emerging around the world for new and upgraded storage-ring-based x-ray facilities that will increase source brightness by a factor of 100-1000 over existing facilities.  In the soft x-ray regime, these new sources will be essentially diffraction-limited and will therefore produce beams with full transverse coherence and high coherent flux. I will briefly discuss the technology behind these accelerator upgrades, and in more detail the new science opportunities that will be afforded by such an upgrade of the Advanced Light Source.

Host: Dietrich Belitz

 

Date:  Thursday, January 24th, 2019
Speaker: Nathan Keim,  Polytechnic State University

Title: Cyclic Memories in Disordered Matter

Abstract: Cyclic driving happens all around us. Buildings and bridges are repeatedly loaded and unloaded, and temperatures change between day and night. This kind of driving can change a material, but in some cases it also forms memories that can be recalled later. I present two examples of materials that, when deformed repeatedly, can “learn” and report the magnitudes of those deformations: a suspension of particles in liquid, and a jammed solid made of closely packed particles. Their memories follow different rules, with jammed solids approximating the return-point behavior best known in magnetic materials. These materials’ disordered structure, and sometimes even the presence of noise, are essential for the fidelity of their memories.

Host: Eric Corwin

 

Date:  Thursday, January 17th, 2019
Speaker: Rakshya Khatiwada, Fermilab

Title: Exploring the Mystery of Dark Matter

Abstract:  Very few mysteries in our current picture of the universe are bigger than the puzzle of dark matter. Recently the QCD axion — a weakly interacting, sub-eV particle — has been in the limelight as a cold dark matter candidate which also enjoys compelling theoretical motivation as a possible solution to the strong CP problem. This talk will give an overview of modern axion searches along with a detailed discussion of the most sensitive experiment to probe the QCD axion to date, ADMX. In particular, it will focus on ADMX’s recent success in reaching the so-called DFSZ sensitivity—a decade long goal sought by axion experimenters — and its newest limits covering axion mass ranges of 2.66 to 2.81 μeV. The limits ADMX has placed in this range have crucial implications for the future direction of on-going dark matter searches as I will outline.

Host: Stephanie Majewski

 

Date:  Thursday, January 10th, 2019
Speaker: Oleg D. Lavrentovich, Department of Physics, Advanced Materials and Liquid Crystal Institute, Kent State University

Title: Dynamics of Colloids in Liquid Crystals

Abstract: Dynamics of microparticles in fluids has fascinated scientists for centuries.  Phenomena such as electrokinetics of Janus spheres and swimming of microorganisms continue to inspire research and innovation.  The fluid in which the particles move is typically isotropic, such as water, and the dynamics is usually chaotic.  If one could learn how to control and streamline dynamics at microscale, it would open many technological opportunities.  This presentation describes how one can use an anisotropic fluid, namely, a nematic liquid crystal, to command the dynamics of living and inanimate microparticles. In nematics, molecules align along a preferred direction called the director.  A spatially-varying director field enables new mechanisms of transport and allows one to control many aspects of microscale dynamics. Three examples are considered: (i) liquid crystal-enabled electrokinetics; (ii) command of bacterial dynamics by a patterned director field; (iii) electrically powered 3D particle-like solitary waves. The main results are published in Nature 467, 947-950 (2010), Science 342, 1351-1354 (2013), Nature Comm. 5, 5033 (2014) and 9, 2912 (2018). Current work is supported by NSF grant DMREF DMS-1507637 and by the Office of Sciences, DOE, grant DE-SC0019105.

Host: John Toner