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May 4, 2018

Re-Examining Astrophysical Constraints on the Dark Matter Model

Speaker:  Alyson Brooks, Rutgers University

Abstract:

The cosmological model based on cold dark matter (CDM) and dark energy has been hugely successful in describing the observed evolution and large scale structure of our Universe. However, at small scales (in the smallest galaxies and at the centers of larger galaxies), a number of observations seem to conflict with the predictions of CDM cosmology, leading to recent interest in alternative dark matter models. I will summarize a number of ways that including baryonic physics (the physics of gas and stars) can resolve the conflict between theory and observations, by significantly altering the structure and evolution of galaxies. Despite all of the successes of baryonic physics in reconciling CDM with observations, I will explain why alternative dark matter models are still viable and interesting.

Host: Graham Kribs

Date:  Thursday, May 10th, 2018
Time: 4:00-5:00pm
Location: 100 Willamette Hall

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

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April 26, 2018

Fluids that Stiffen and Swim

Speaker:  Daniel Blair, Georgetown University

Abstract:

In this talk I will discuss our recent results on the microscopic physical origins of shear thickening in sheared colloidal suspensions and the viscoelasticity of active fluids. In the first part of my talk, I will introduce a method we have developed that allows us to resolve the spatial distribution of stresses in sheared soft-materials, known as Boundary Stress Microscopy. We have applied this technique suspensions undergoing continuous and discontinuous shear thickening. I will present our results on the existence of clearly defined dynamically localized regions of substantially increased stress that appear intermittently at stresses well above the applied stress. Surprisingly, we find that these spatially distinct and dynamic phases account quantitatively for the observed shear thickening seen in sheared colloidal dispersions (e.g. Oobleck). In the second part of my talk I will discuss our results on the rheology of active matter. Our system is composed of microtubules and motor kinesin proteins that self-assemble to form complexes that propel themselves through the fluid, resulting in spontaneous “swimming” of the suspended material. What results is an interplay between the internal active stresses and any imposed external stress. I will discuss the impact of the internal flows have on the local and bulk rheological response.

Host: Eric Corwin

Date:  Thursday, May 3rd, 2018
Time: 4:00-5:00pm
Location: 100 Willamette Hall

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

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April 20, 2018

Quantum Mechanical Bounds on Transport from First Principles

Speaker:  Sean Hartnoll, Stanford University

Abstract:

Some of hardest theoretical challenges in strongly-interacting many-body systems are concerned with transport. This involves understanding quantities such as the electric resistivity, the thermal conductivity, the viscosity, spin diffusivity etc. of media as diverse as the quark-gluon plasma, unconventional metals and cold atomic gases. I will argue that a handle on these problems can be gained from understanding fundamental limits on the dynamics of many-body systems imposed by quantum mechanics and statistical mechanics themselves. The advantage of this approach is that it does not depend on the presence of weakly interacting quasiparticles.

Host: Tim Cohen

Date:  Thursday, April 26th, 2018
Time: 4:00-5:00pm
Location: 100 Willamette Hall

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

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April 13, 2018

Why Systems Biology Shouldn’t Work but Does and What Heat Capacity Can Explain About Inference

Speaker:  Paul Wiggins, University of Washington

Abstract:

Why do systems biology models work in spite of a blizzard of poorly-defined parameters and yet the detection of the Higgs boson required five sigma precision? Scientific and technological innovations are rapidly increasing the size and scope of datasets. Accompanying this growth come new challenges in analysis, interpretation and modeling. Fundamental questions remain about the mechanism of learning. To study the universal principles governing these processes, we expand upon a long-discussed correspondence between thermodynamics and statistics. This correspondence to thermal physics provides some surprising insights into the mechanism of learning. An analogy to heat capacity demonstrates both a universal scaling of learning algorithms as well as how and why these scaling relations fail in many of the most interesting models, including systems biology models. An analogy to the Gibbs entropy provides a new algorithm for efficient inference, well-suited to single-molecule-fluorescence measurements where the number of photons collected is small.

Host: Tristan Ursell

Date:  Thursday, April 19th, 2018
Time: 4:00-5:00pm
Location: 100 Willamette Hall

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

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April 9, 2018

Laser Immunotherapy for Metastatic Cancers: Interplay of Photons, Molecules, Cells, and Humans

Speaker:  Wei R. Chen, University of Central Oklahoma

Abstract:

The cure for cancer remains elusive because of the ability of cancer cells to disguise themselves as normal “self” cells, thus evading detection and destruction by the host immune system. Metastasis is the major cause of cancer-related death.  We have developed Laser Immunotherapy (LIT) to treat metastatic cancers by using a combination of local laser irradiation and immunological stimulation. In LIT the laser-treated tumor cells become the source of tumor antigens that act as the signals for the immune system to recognize as “foreign” objects. The immune system then proceeds to eradicate both the residual tumor cells at the treatment site and distant metastasized tumors.  Essentially, LIT turns the host immune system around from defending against “foreign” cells to eradicating “domestic” tumor cells.  In this talk the procedures and mechanism of LIT will be introduced.  Our successful clinical results using LIT in patients with late-stage melanoma and breast cancer will be presented.

Host: Rudy Hwa

Date:  Thursday, April 12th, 2018
Time: 4:00-5:00pm
Location: 100 Willamette Hall

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

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March 16, 2018

Quantum Quantum-Thermodynamics

Speaker: Terry Rudolph, Imperial College London

Abstract: The thermodynamic implications of quantization of energy were realized before the full quantum theory was even developed. By contrast, the thermodynamic implications of quantum coherence, in the myriad guises it can arise, are still today encountered in a somewhat piecemeal fashion. I will discuss some simple quantum thermodynamic phenomena that rely on the presence of quantum entanglement or quantum coherence, and then discuss progress to a coherent (!) general framework for such phenomena using tools of quantum information theory.

Host: Mike Raymer

Date:  Thursday, April 5th, 2018
Time: 4:00-5:00pm
Location: 100 Willamette Hall

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

 

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March 9, 2018

Atomic-Resolution In-Situ Characterization of Multi-Functional Materials

Speaker: Robert F Klie, University of Illinois, Chicago

Abstract:

The last few years have seen a paradigm change in the way we characterize materials, with unprecedented improvements in both spatial and spectroscopic resolution being realized in current transmission electron microscopes (TEM). When multi-modal X-ray and electron imaging is combined with density-functional theory (DFT) calculations, the effects of defects, dopants or strain at grain boundaries or interfaces can now be directly determined and correlated to electronic/thermal transport properties. While spatial and energy resolutions better than 60 pm and 10 meV have been reported, aberration-corrected TEM has also enables a large variety of in-situ experiments at close to atomic resolution. Using this approach, the intercalation of multi-valent ions into cathode materials, the dynamics of vacancies, and the interactions between gases and nano-particles can now be directly observed, to only mention a few examples.

Here, I will demonstrate how in-situ multi-modal characterization and DFT modeling can be used to unravel the fundamental structure-property relationship of grain boundaries in photovoltaic CdTe devices or the intercalation of Mg-ions in transition metal oxide cathodes. I will further introduce a novel approach to measuring temperature and thermal expansion in nano-scale materials using electron microscope. I will also show how our recent development of graphene-based liquid cells now enables the direct characterization of  biological materials and solid-liquid interfaces at close to atomic-resolution. I will conclude by discussing my vision for the future of high-resolution transmission electron microscopy, including monochromated electron-sources, new data processing approaches for low-dose microscopy as well as operando multi-modal methods combing x-ray and electron scattering.

Host: Ben McMorran

Date:  Thursday, March 15th, 2018
Time: 4:00-5:00pm
Location: 100 Willamette Hall

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

March 2, 2018

Frequency Conversion and Time Reversal of Single-Photon States for a Quantum Internet

Speaker:  Mike Raymer, UO

Abstract: Given a single photon, information can be encoded on it using its color (frequency) or temporal shape (temporal mode). Nonlinear wave mixing in a strongly driven medium can exchange (or swap) the quantum states between two narrow spectral bands of the optical spectrum. When one spectral band is occupied by a single-photon wave-packet state, and the other band is occupied by vacuum, this process can achieve quantum frequency conversion (QFC), changing the carrier frequency of the photon. QFC can also act to time reverse the photon’s wave packet. Both of these operations play essential roles in creating a future quantum Internet.

Date:  Thursday, March 8th, 2018
Time: 4:00-5:00pm
Location: 100 Willamette Hall

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

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February 21, 2018

Electrical Measurement and Simulation of the Human Brain

Date:  Thursday, March 1st, 2018

Speaker:  Don M. Tucker, Ph.D, Professor of Psychology, Director of the Neuroinformatics Center, University of Oregon
Head of Clinical Science, Philips Neuro egi.com
CEO, NADA (Neural Analog-to-Digital Approximation) nadaweb.net

Date:  Thursday, March 1st, 2018
Time: 4:00-5:00pm
Location: 100 Willamette Hall

Abstract:

The electroencephalogram or EEG has been an important research and clinical tool for the last 75 years.  Recent advances in localizing the EEG to the electrical fields of the cortex have been achieved through dense electrode arrays, specifying the geometry of head tissues with MRI and CT, and measuring the conductivity of head tissues with electrical impedance tomogrphy (EIT).  With bounded EIT (bEIT), we assume the geometry (from MRI) is known and need only to estimate the conductivity of each compartment.  Small currents are injected into the head, recovered in the EEG signal, and the difference in amplitude is related to tissue conductivity of the model with Ohm’s law.  My associates and I are exploring the possibility of understanding the pattern of cortical electrical fields through simulation, in which a whole brain artificial neural network model (thevirtualbrain.org) is created for to match the individual person’s fiber tractography (cerebral wiring diagram).  Each node modeling the cortex is used to generate a simulated EEG field in proportion to its dynamic activity in the network model.  Using machine learning to improve the emulation of the model of the individual’s cortical electrical fields over many weeks and months of recording, and extending the virtual brain with high performance computing, we will attempt to recreate the essential dynamics of the person’s brain in the artificial neural network model.  Applications to be evaluated will include neurological diagnosis, educational analysis and remediation, and sharing memory between neural and machine intelligence.

Host:  Mike Raymer

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

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February 16, 2018

Quantum Control and Manipulation of Trapped Ions: From Atomic to Complex Molecular Species

Date:  MONDAY,  February 19, 2018

Speaker:  Michael Drewsen, Department of Physics and Astronomy, Aarhus University, Denmark

Location:  PACIFIC Hall 123

Abstract:

In the recent past, the ability to control and manipulate trapped ions at the quantum level have gone through an amazing evolution. Based on laser cooling of trapped atomic ions, investigations of a wide range of fundamental quantum physics phenomena have been made possible, and today, laser-cooled and trapped ions constitute one of the most successful platforms for the quantum technology as well as optical atomic clock developments. The importance of these achievements is probably best exemplified by the Nobel Prize in Physics in 2012 to Prof. David Wineland, University of Oregon. Recently, the methods used to control and manipulate atomic ions has furthermore attracted attention from researchers interested in cold molecular science due to the potential of investigating the structure and internal dynamics of molecules at an unprecedented level of accuracy, as well as the prospects of studying Chemistry in unexplored cold and ultracold regimes. This field of research is still in its infancy, but holds great promises for the future.

In the talk, I will discuss some of my research group’s contributions to both quantum physics and chemistry based on cold and trapped ions.

Host:  Mike Raymer

Catered Reception: 3:40pm-3:55pm, Willamette Hall, Paul Olum Atrium

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