Jennifer M. Heemstra: University of Utah
Harnessing Nucleic Acid Molecular Recognition and Self-Assembly for Biosensing and Biomolecular Imaging
Two dynamical interfaces walk into an IRG…
a recap of tuesday's idea session
12:00 Eat real food 12:15 digest bloblets
Zoran Hadzibabic, University of Cambridge
Quantum gas in a box
Host: Cheng Chin
Anette Hosoi, MIT
Hydrodynamics of Hairy Surfaces
Flexible slender structures in flow are everywhere. While a great deal is known about individual flexible fibers interacting with fluids, considerably less work has been done on fiber ensembles, such as fur or hair, in flow. These hairy surfaces are abundant in nature and perform multiple functions from thermal regulation to water harvesting to sensing. Motivated by these biological systems, we consider two examples of hairy surfaces interacting with flow: (1) air entrainment in the fur of diving mammals and (2) symmetry breaking in hairy micro-channels. In the first example, we take inspiration from semi-aquatic mammals (such as fur seals, otters, and beavers) which have specially adapted fur that serves as an effective insulator both above and below water. Many of these animals have evolved pelts that naturally entrap air when they dive. This air: (1) provides additional insulation under water, (2) provides added buoyancy, and (3) facilitates water shedding when the animals resurface. In this study we investigate diving conditions and fur properties which amplify air entrainment in fur. In the second example, we consider a fundamental component in hydraulic systems, the flow rectifier. One of the simplest ways to generate asymmetry in these devices is with a ball valve in which flow is completely obstructed in one direction and free to flow in the other. In this work we seek a variation that: (1) allows the designer to modulate the relative resistances in the rectifier and (2) can be achieved with solid state components (i.e. no moving parts).
The Tuesday JFI Seminar - Monika Schleier-Smith, Department of Physics, Stanford University
"Echoes of Entanglement: from Quantum Metrology to Scrambling"
ABSTRACT: In the quest to approach the fundamental Heisenberg Limit in precision measurements, central challenges are the generation and detection of highly entangled states. I will describe how both of these challenges can be mitigated by “echo spectroscopy,” a technique inspired by the Loschmidt echo, a paradigmatic probe of chaos. A key ingredient is to effectively reverse the flow of time in an interacting many-body system by switching the sign of the Hamiltonian. I will describe progress towards engineering spin models with non-local, switchable-sign interactions using cold atoms strongly coupled to light an optical cavity. Intriguingly, similar non-local interactions feature in models for understanding fundamental bounds on chaos and information scrambling derived from the study of black holes, opening prospects for investigating these bounds in the laboratory.Host: Jonathan Simon, 2-9661 or via email at email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Viviana Gradinaru, PhD, CALTECH
Optogenetic, tissue clearing, and viral vector approaches to understand and influence whole-animal physiology and behavior
We develop & employ optogenetics, tissue clearing and viral vectors to gain new insights on circuits underlying locomotion, reward & sleep. I will discuss how bidirectional manipulation of mesopontine cholinergic cell bodies exerted opposing effects on locomotor behavior & reinforcement learning & how these effects were separable via limiting photostimulation to PPN cholinergic terminals in the ventral substantia nigra pars compacta or to the ventral tegmental area, respectively (Xiao et al, Neuron, '16). Genetically encoded tools that can be used to visualize, monitor, and modulate mammalian neurons are revolutionizing neuroscience. However, use of genetic tools in non-transgenic animals is often hindered by the lack of vectors capable of safe, efficient & specific delivery to the desired cellular targets. To begin to address these challenges, we have developed an in vivo Cre-based selection platform (CREATE) for identifying adeno-associated viruses (AAVs) that more efficiently transduce genetically defined cell populations (Deverman et al, Nature Biotechnology, '16). As a first test of the CREATE platform, we selected for viruses that transduced the brain after intravascular delivery and found a novel vector, AAV-PHP.B, that transduces most neuronal types and glia across the brain. We also demonstrate how whole-body tissue clearing can facilitate transduction maps of systemically delivered genes (Yang et al, Cell, '14; Treweek et al, Nature Protocols, '16) and how non-invasive delivery vectors can be used to achieve dense to sparse labeling to enable morphology tracing (unpublished). Since CNS disorders are notoriously challenging due to the restrictive nature of the blood brain barrier, the recombinant vectors engineered to overcome this barrier can enable potential future use of exciting advances in gene editing via the CRISPR-Cas, RNA interference and gene replacement strategies to restore diseased CNS circuits. In addition to control of neuronal activity we need feedback on how exactly the tissue is responding to modulation. We have worked on two related topics: optical voltage sensors and imaging of single molecule RNA in cleared tissue. We used directed evolution of opsins to make them better at reporting action potentials (Flytzanis et al, Nature Communications, '14). Changes in RNA transcripts can also report on activity history of brain circuits. Preserving spatial relationships while accessing the transcriptome of selected cells is a crucial feature for advancing many biological areas, from dev bio to neuroscience. We recently reported on methods for multi-color, multi-RNA, imaging in deep tissues. By using single-molecule hybridization chain reaction (smHCR), PACT tissue hydrogel embedding and clearing and light-sheet microscopy we detected single-molecule mRNAs in ~mm-thick brain tissue samples (Shah et al, Development, '16) and by rRNA labeling we mapped the identity & growth rate of pathogens in clinical samples (DePas et al,'16).
Closs Lecture-Professor Mostafa El-Sayed, Georgia Institute of Technology
Photothermal Therapy of Cancer in Cells and in Different Animals Using Gold Nano-Rods: A Progress Report
Roger Melko, Perimeter Institute
Machine Learning the Many-Body Problem
Condensed matter physics is the study of the collective behavior of infinitely complex assemblies of electrons, nuclei, magnetic moments, atoms or qubits. This complexity is reminiscent of the “curse of dimensionality” commonly encountered in machine learning. Despite this curse, the machine learning community has developed techniques with remarkable abilities to classify, characterize and interpret complex sets of data, such as images and natural language recordings. Here, we show that modern architectures for supervised learning, such as fully-connected and convolutional neural networks, can identify phases and phase transitions in a variety of condensed matter Hamiltonians. Readily programmable through open-source software libraries, neural networks can be trained to detect multiple types of order parameter, as well as highly non-trivial states with no conventional order, directly from raw state configurations sampled with standard Monte Carlo. Further, Monte Carlo configurations can be used to train a stochastic variant of a neural network, called a Restricted Boltzmann Machine (RBM), for use in unsupervised learning applications. We show how RBMs, once trained, can be sampled much like a physical Hamiltonian to produce configurations useful for estimating physical observables. Finally, we explore the representational power of quantum and classical RBMs, their role in deep learning, and its possible relationship to the renormalization group.
John Jewett: University of Arizona
Viral muses to inspire chemistry
Bloblets in your cells: what is their mission?
12:00 Eat real food 12:15 digest bloblets
Steve Kivelson, Stanford University
Intertwined Order in Highly Correlated Electron Fluids
Host: Paul Wiegmann
Minjung Ryu, PhD, Purdue
Language, Culture, and Learning: Implications for Interdisciplinary Research
Jonathan Simon, University of Chicago
Exploring Landau Levels in Curved Space
I will present recent work realizing topological phases of photons, both in curved space, and in lattices. The talk will focus on our recent exploration of Landau levels on a conical surface, generated using a non-planar (twisted) optical resonator to induce a synthetic magnetic field for optical photons, and employed to validate the famous Wen-Zee action. I will then discuss recent results demonstrating strong photon-photon interactions mediated by resonator Rydberg-electromagnetically induced transparency (EIT), and techniques we are developing to assemble topological few-body states both photon-by-photon, and through microscopic devices engineered for photon thermalization. I will conclude with our recent observation of time-resolved helical edge dynamics in Z_2 topological circuit lattices, and a T-broken extension in the microwave domain using arrays of 3D cavities and circuit quantum electrodynamics techniques. This work showcases the unique possibilities for Hamiltonian engineering and control in the photonic sector, a provides a taste of upcoming breakthroughs in engineering quantum materials from photons.
The Tuesday JFI Seminar - Elisabeth Guazzelli, Aix Marseille Univ, CNRS, IUSTI, Marseille, France
Rheology of Dense Suspensions of Non-Colloidal Particles
ABSTRACT: Dense suspensions are materials with broad applications both in industrial processes (e.g. waste disposal, concrete, drilling muds, metalworking chip transport, and food processing) and in natural phenomena (e.g. flows of slurries, debris, and lava). Despite its long research history and its practical relevance, the mechanics of dense suspensions remain poorly understood. The major difficulty is that the grains interact both by hydrodynamic interactions through the liquid and by mechanical contact. These systems thus belong to an intermediate regime between pure suspensions and granular flows. We show that we can unify suspension and granular rheology under a common framework by transferring the frictional approach of dry granular media to wet suspensions of spherical particles. We also discuss non-Newtonian behavior such as normal-stress differences and shear-induced migration. Beyond the classical problem of dense suspension of hard spheres which is far from being completely resolved, there are also entirely novel avenues of study concerning more complex mixtures of particles and fluids such as those involving other types of particles (e.g. fibers) or non-Newtonian fluids (e.g. yield-stress fluids) that we will also address. Host: Heinrich Jaeger, 2-6074 or via email at email@example.com. Persons with a disability who may need assistance contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Matthew Lapa, UIUC
Electromagnetic response and anomalies in bosonic symmetry-protected topological phases
Symmetry-protected topological (SPT) phases, gapped phases of matter protected by the symmetry of a group G and possessing interesting boundary states, have been the focus of intense investigation for the past several years. While much is known about the classification and properties of these phases, especially in low dimensions, it is still a challenge to understand the physical properties which characterize a given (interacting) SPT phase in a general dimension. In this talk I will explain how a field-theoretic description of bosonic SPT phases in terms of nonlinear sigma models (NLSMs) can be combined with the theory of gauged Wess-Zumino actions to study the electromagnetic response and anomalies of some bosonic SPT phases with U(1) symmetry in all dimensions. In particular, I will present a calculation of the topological part of the electromagnetic response of bosonic integer quantum Hall (BIQH) states in odd spacetime dimensions and bosonic topological insulator (BTI) states in even spacetime dimensions. In addition, I will argue that the boundary of the BTI state exhibits a global anomaly similar to the parity anomaly of Dirac fermions in odd spacetime dimensions. This argument can be made precise for the boundary theory of the BTI state in two spacetime dimensions. If time allows, I will explain how the connection between gauged Wess-Zumino actions and equivariant cohomology can be used to prove that these results are robust against smooth, symmetry-preserving deformations of the target space of the NLSM used to describe these states.
Gregory T. Tietjen, PhD, Yale
A biophysical approach to engineering vascular targeted nanomedicine
Ribhu Kaul, University of Kentucky
Quantum phase transitions in square lattice SU(N) and SO(N) magnets
I will discuss the phases and phase transitions in some simple SU(N) and SO(N) quantum spin models, studied both using ideas from quantum field theory and with large scale numerical simulations.
James Morken, Boston College
New Strategies in Organic Synthesis Enabled by Catalytic Reactions of Organoboron Reagents
The 1st Tuesday JFI Colloquium - Mark G. Raizen - Department of Physics, University of Texas at Austin
From Maxwell’s Demon to Einstein’s Speed Demon
ABSTRACT: In this talk, I will describe two historical thought experiments in statistical mechanics and their experimental realization. Maxwell’s Demon was proposed by James Clerk Maxwell in 1871 as a way to reduce the entropy of gas-phase particles by means of an “intelligent creature with deft hands.” We have realized this thought experiment with a self-acting one-way wall for atoms, as originally suggested by Maxwell. This construction has been used to cool atoms, and for efficient isotope separation which will have important medical applications. In 1907, Albert Einstein predicted that Brownian motion should be ballistic on very short time scales, rather than diffusive. Einstein concluded that this instantaneous velocity would be impossible to measure in practice, a prediction that held for over 100 years. We have realized such a ‘speed demon’ by measuring the motion of micrometer beads held in optical tweezers, and have resolved the instantaneous velocity of a Brownian particle in air and in liquid. This system can be used to study the onset of irreversibility, the “arrow of time.”Host(s):Cheng Chin, 2-7192 or via email to email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Wolfgang Ketterle, MIT
New forms of matter with ultracold atoms: synthetic gauge fields and supersolidity
Hosts: Cheng Chin
Yimon Aye, Cornell
Stay On Target: Deconvoluting Mixed Redox Messages through Precision Redox Targeting
The Tuesday JFI Seminar - James F. Cahoon, Department of Chemistry, University of North Carolina - Chapel Hill
From Nanowires to Nanoplatelets: Designing Semiconductor Morphology so Form Follows Function
Semiconductors are used in a vast array of modern technologies, including solar cells that convert sunlight into electricity and microprocessors that drive computers. They can be used to direct the flow of energy in devices or to convert energy from one form to another. These functions are enabled by the specific choice of material and composition. Shape, however, is another fundamental characteristic that can be used to encode functionality. Here, I will describe my group’s efforts to usenanometer-scale morphology as a strategy to encode novel photovoltaic, electronic, and optical properties in materials created by bottom-up methods. We chemically synthesize nanostructures, such as metal oxide particles and group IV nanowires, with precise morphology and composition, and we evaluate their physical properties using nanofabrication, spectroscopic, electrochemical, and computational methods. For instance, I will describe a strategy to create silicon nanowires with lithographic-like patterns, enabling applications ranging from photonic crystals to non-volatile memory. In addition, I will outline our efforts to design wide-bandgap photocathode materials for integration in solar fuels devices. The results yield insights into the synthesis, structure-function relationships, and technological applications of designed, bottom-up semiconductor nanomaterials. Host: Bozhi Tian; Contact him at 2-8749 or via email at email@example.com. Persons with a disability who may need assistance please contact Brenda Thomas at 2-7156 or by email at firstname.lastname@example.org.
Wheland Lecture - John P. Maier: University of Basel
Electronic Spectroscopy of C60+ and its Identification in Interstellar Space
The 2nd Tuesday JFI Colloquium - Hui Zhai, Tsinghua University, Institute for Advanced Study
Closs Lecture - Christopher Chang, University of California, Berkeley
Transition Metal Signaling in the Brain and Beyond
Moh El-Naggar, PhD, Depts of Physics and Astronomy, of Biological Sciences, and of Chemistry, University of Southern California
Far, Fast, & Surprising: Extracellular Electron Transport in Microbial Redox Chains
The stepwise movement of electrons within and between molecules dictates all biological energy conversion strategies, including respiration and photosynthesis. With such a universal role across all domains of life, the fundamentals of ET and its precise impact on bioenergetics have received considerable attention, and the broad mechanisms allowing ET over small length scales in biomolecules are now well appreciated. In what has become an established pattern, however, our planet’s oldest and most versatile organisms are now challenging our current state of knowledge. With the discovery of bacterial nanowires and multicellular bacterial cables, the length scales of microbial ET observations have jumped by 7 orders of magnitude, from nanometers to centimeters, during the last decade alone! This talk will take stock of where we are and where we are heading as we come to grips with the basic mechanisms and immense implications of microbial long-distance electron transport. We will focus on the biophysical and structural basis of long-distance, fast, extracellular electron transport by metal-reducing bacteria. These remarkable organisms have evolved direct charge transfer mechanisms to solid surfaces outside the cells, allowing them to use abundant minerals as electron acceptors for respiration, instead of oxygen or other soluble oxidants that would normally diffuse inside cells. From an environmental perspective, these microbes are major players in global elemental cycles. From a technological perspective, microbial extracellular electron transport is heavily pursued for interfacing redox reactions to electrodes in multiple renewable energy technologies. But how can an organism transfer electrons to a surface many cell lengths away? What molecules mediate this transport? And, from a physics standpoint, what are the relevant length, time, and energy scales? We will describe new experimental and computational approaches that revealed how bacteria organize heme networks on outer cell membranes, and along the quasi-one-dimensional filaments known as bacterial nanowires, to facilitate long-range charge transport. Using correlated electron cryo-tomography and in vivo fluorescent microscopy, we are gaining new insight into the localization patterns of multiheme cytochromes along nanowires as well as the morphology and the formation mechanism of these structures. In addition, we will examine the fundamental limits of extracellular electron transport, down to microbial energy acquisition by single cells. These findings are shedding light on one of the earliest forms of respiration on Earth while unraveling surprising biotic-abiotic interactions.
2017 Hillhouse Memorial Lecture - Professor Martin Karplus of Harvard University
Motion: Hallmark of Life. From Marsupials to Molecules
This lecture will present an intellectual path from the role of motion in animals to the molecules that make the motion possible. Motion is usually a way of distinguishing live animals from those that are not, but not always. Just as for the whole animal, motion is an essential part of the function of the cellular components. What about the molecules themsleves? Does motion distinguish molecules designed by people from those developed by evolution? For animals to move, they require energy, which is obtained primarily by using oxygen. So how are whales and dolphins able to use their muscles to dive to great depths, where oxygen is not available? The immediate energy source for muscle function is the molecule ATP. For the generation of this molecule, Nature has developed a marvelous rotary nanomotor. Experiments and simulations, particularly those with supercomputers, are now revealing the mechanism of this nanomotor and other cellular machines.
Closs Lecture-Eric Jacobsen, Harvard University
Frank Wise, Department of Physics, Cornell University
Optoelectronic Properties of Semiconductor Nanocrystal Solids
There is currently great interest in electron transport in nanocrystal solids, driven by potential applications to electronic and optoelectronic devices. A major goal of the field is to achieve bandtype transport of electrons, and despite much progress in this direction, claims of band transport remain controversial. Recently, the fabrication of quasi-two-dimensional superlattices of oriented and epitaxially connected nanocrystals was reported. The structures exhibit both short- and long-range order. Calculations of the electronic states of such “atomically-coherent” assemblies reveal bandwidths that imply promising transport properties. We will report on the synthesis of atomically-coherent superlattices of PbSe nanocrystals, along with structural characterization by x-ray diffraction and high-resolution electron microscopy. Studies of charge transport show that disorder plays a major role in the properties of existing nanocrystal solids. Prospects for achieving true band transport in these structures will be discussed. The talk will begin with a tutorial introduction to semiconductor nanocrystals and devices based on them such as solar cells and light emitters. Host: Philippe Guyot-Sionnest, contact via email at email@example.com or by phone at 2-7461.
Nandini Ananth: Cornell University
Uttam Tambar: UT Southwestern
Stereoselective Functionalization of Unactivated Hydrocarbons
Rainer Weiss, MIT
Meghan Thielges, Indiana University
Conformations and Dynamics of Protein Molecular Recognition
Pedro M Reis, Department of civil Engineering, MIT
Michael Filler, Department of Chemical and Biomolecular Engineering, Georgia Tech
Xiaogang Peng, Zhejiang University
Cheng Chin, University of Chicago
Arvind Murugan - Department of Physics, University of Chicago
Sean Garrett-Roe, University of Pittsburgh
Ultrafast vibrational spectroscopy of ionic liquids: Insight into carbon capture, chemical reactions, and energy storage
Jessie Shelton, University of Illinois (Urbana-Champaign)
Sungyon Lee, Texas A&M University
Particle-induced viscous fingering
Edward Sargent, University of Toronto
Materials and Devices for Flexible Optoelectronics and Renewable Fuels
Vast advances in materials and physical chemistry have led us to the point that, today, we can create a wide range of tunable, solution-processed materials whose spectral properties span the visible and infrared . These are enabling flexible solar cells , top-surface photodetectors, and ubiquitous light sources . I will discuss recent advances that leverage innovations from inorganic synthetic chemists and physical chemists and apply them in the engineering of high-performance optoelectronic devices. I will then discuss a further implication of rapid progress in the cost-effective conversion of solar energy into electrical power. These advances bring about a new challenge, namely, the need for massive (seasonal-scale) storage of energy . I will describe how the use of computational materials science, spectroscopies including ultrafast and synchrotron, and advances in materials chemistry, are accelerating the creation of new catalysts for CO2 reduction and oxygen evolution. I will discuss recent advances including a new high-activity OER catalyst  and a low-overpotential CO2 reduction catalyst based on field-induced reagent concentration . Host: Philippe Guyot-Sionnest; contact via email at firstname.lastname@example.org or by phone at 2-7461. Persons with a disability who may need assistance please contact Brenda Thomas by email at email@example.com or phone at 2-7156.
Bloch Lecture - Dr. Jay Bradner, Dana-Farber Cancer Institute
Inhibition and Degradation of Bromodomain Proteins
Closs Lecture - Sarah Tolbert, UCLA
Solution Processed Nanomaterials: From Basic Science to Solutions to Practical Energy Problems
Shinsei Ryu, University of Chicago
Topological insulators and superconductors--from band theory to interacting systems
Joshua A Frieman, Fermilab, University of Chicago
The Dark Energy Survey
I will overview the Dark Energy Survey (DES) project, highlight its early science results, and discuss its on-going activities and plans. The DES collaboration built the 570-megapixel Dark Energy Camera for the Blanco 4-meter telescope at Cerro Tololo Inter-American Observatory in Chile to carry out a 5-year, deep, multi-band, optical survey over one eighth of the sky and a time-domain survey that will discover several thousand supernovae. The survey started in Aug. 2013 and is now nearing completion of its fourth observing season. DES was designed to address the questions: why is the expansion of the Universe speeding up? Is cosmic acceleration due to dark energy or does it require a modification of General Relativity? If dark energy, is it the energy density of the vacuum (Einstein's cosmological constant) or something else? DES is addressing these questions by measuring the history of cosmic expansion and the growth of structure through four complementary techniques: galaxy clusters, the large-scale galaxy distribution, gravitational lensing, and supernovae, as well as through cross-correlation with other data sets. I will also discuss how the data are being used to make a variety of other astronomical discoveries, from our Solar System to the most distant quasars.
Steven Boxer, Stanford University
Electric Fields and Enzyme Catalysis
Dr. Daniel Greif, Harvard University
Quantum Antiferromagnets with Single-Site Resolution
Strongly correlated electron systems such as high-temperature superconductors and pseudo-gap states are a cornerstone of modern condensed matter research. A complementary approach to studying solid-state systems is to build an experimentally tunable quantum system governed by the Hubbard model, which is thought to qualitatively describe these systems but is difficult to understand theoretically. Ultracold fermionic quantum gases in optical lattices provide a clean and tunable implementation of the Hubbard model. At the same time, optical microscopy in these systems gives access to single-site observables and correlation functions, and provides dynamic control of the potential landscape at the single-site level. So far, ultracold atom experiments have not been able to reach the low-temperature regime of the Hubbard model, which becomes particularly interesting when doped. Here we report on the observation of antiferromagnetic long-range order in a repulsively interacting Fermi gas of Li-6 atoms on a 2D square lattice containing about 80 sites. The ordered state is directly detected from a peak in the spin structure factor and a diverging correlation length of the spin correlation function. When doping away from half-filling into a numerically intractable regime, we find that long-range order extends to doping concentrations of about 15%. Our results open the path for a controlled study of the low-temperature phase diagram of the Hubbard model. JFI TUESDAY SEMINAR January 27, 2017 GCIS W301 | Tuesday, 4:00 pm MORE INFORMATION
Dr. Scott W. Schmucker, Zyvex Labs, Richardson, Texas
Atomically-Precise Engineering of Low-Dimensional Systems
As ultra-precise manufacturing technology scales to its atomic limits, we transition into the realm of digital matter and novel composite materials while enabling a burgeoning array of quantum, electronic, and photonic devices. In this talk, we explore several fabrication technologies which enable atomic- precision while elucidating the fundamental science and the engineering applications motivated and enabled thereby. We first compare several related two-dimensional material systems: graphenic materials and hyperdoped delta layers in silicon, each of which can be chemically and lithographically engineered or combined to form van der Waals and covalent delta-doped heterostructures. We explore the influences of interlayer coupling, interfaces, and defects in layered systems. We will then expand our discussion beyond layered systems and extend atomic precision into three dimensions. Discussion will focus on scanned probe lithography for the fabrication of donor atom quantum devices in silicon and recent efforts to expand these devices to include acceptor dopants and to enable three-dimensional architectures. We discuss the physics and fabrication of donor atom qubits in silicon, and through a combination of scanning tunneling microscope-driven lithography and Zyvex engineering, we demonstrate the scaling of manufacturing precision to the atomic scale
Daniel Diermeier, University of Chicago
The talk will discuss models of elections from game-theory to statistical mechanics. I will discuss their relative strengths and weaknesses and their ability or inability to explain voting behavior in mass elections.