Effective Fall 2021, unless stated otherwise, we are back to holding our colloquia in person. All physics and astronomy colloquia will take place on Thursday afternoon from 4 to 5 pm in room 4327 Stevenson Center, but we will also have a hybrid Zoom option available for those who would prefer to attend remotely
For details please contact Ashley E. Brammer by email (email@example.com) or phone (615-343-7389).
Thursday September 1st 2022 12:00 AM
Wilson Ho, University of California, Irvine
The Scanning Tunneling Microscope: an enabling tool for nanoscience
The scanning tunneling microscope (STM) was invented in 1981 as a tool for demonstrating the phenomenon of vacuum tunneling. However, its power for analyzing surfaces of matter was soon realized. While the STM is known for its inherent capability of sub-Ångström spatial resolution, the extension to other limits of measurement continues to be an interesting challenge. The spectral resolution can be increased by lowering the temperature of the sample and the microscope to below 1 K. Combined with ultrahigh vacuum and high magnetic field, the high spectral resolution has enabled the observation of states that would otherwise remain hidden. These hidden states reveal new interactions that are observed by probing single molecules. Results from the STM provide stringent testing grounds for condensed matter theory and challenge our basic understanding of quantum mechanical phenomena.
Host: R. Scherrer
Thursday September 8th 2022 12:00 AM
Alfredo Gurrola, Vanderbilt University
The Higgs Particle Found?
The Large Hadronc Collider was built to probe what particle physicists believe to be one of the great pillars of our understanding of the universe, the Higgs boson. The role and significance of the Higgs boson goes far beyond just particle physics, which studies the smallest scales of the world, and has a direct impact on our understanding of the Universe, the largest scale known to us. The importance of the Higgs boson to our understanding of the universe will be described in a way that can be appreciated by both experts and non-experts. I will describe the reasons particle physicists believe the Higgs boson, through the Higgs mechanism, is responsible for the origin of mass in the Universe and why our best mathematical framework for describing particle physics, the Standard Model, is believed to be incomplete. The current status of the searches for the Higgs boson at the Large Hadron Collider will be described. In doing so, the ideas and strategies behind the searches, channels considered, and the experimental techniques used by scientists at the Large Hadron Collider will be outlined. A small portion of the allocated time will be used to outline the relevant statistical methods, explain the terminology, and illustrate their meaning using easy to follow examples. These statistical methods will be used to answer the question of whether the Higgs boson has already been discovered. The discovery of a Higgs boson is only the first step in a long journey toward understanding the evolution of our universe. Therefore, some time will be spent addressing some important follow up questions and possible ways to find answers. Finally, the possible discovery of the Higgs boson has many implications for theories/models which extend the Standard Model of particle physics. Focus will be placed on the role Vanderbilt has played in the search for a Higgs boson and the role it will play in the years to follow trying to unravel the implications of a possible discovery.
Host: P. Sheldon
Thursday September 15th 2022 12:00 AM
Giancarlo Guerrero, Music Director of the Nashville Symphony
Music and the Nashville Symphony Orchestra, with Physics Overtones
Maestro Guerrero will hold an open discussion concerning the past, present and future of the award winning Nashville Symphony Orchestra. He will start the conversation by talking about this coming season and what audiences can expect for the future, he will also touch upon the recent Carnegie Hall performance, the Grammys, the enthusiastic audiences, and will talk about some of the programs that have touched upon the Physics theme. Attendees are encouraged to bring comments and questions (and even requests) for the Symphony. Of course, there will be significant time for questions and answers.
Host: N. Tolk
Thursday September 22nd 2022 12:00 AM
Kate Jones, U. Tennessee
Structure, Reactions, Astrophysics - Overlaps in Low-Energy Nuclear Physics
An important focus in low-energy nuclear physics has been the link to astrophysics, and in particular, the synthesis of heavy elements in the cosmos. Nucleosynthesis occurs in different astrophysical environments, including stars, novae, supernovae, not to mention during the big bang itself. Each nucleosynthetic pathway consists of many nuclear reactions, many on nuclei that have not been produced in the laboratory. Some nuclei are intrinsically interesting because of their unusual structure or their location in the chart of the nuclei. Many interesting unstable nuclei available in modern accelerator facilities are produced through a reaction. Reactions can also be used to study the structure of nuclei. In this colloquium I will show results of nuclear reaction measurements that have shone a light on nuclear astrophysics and/or nuclearstructure.
Host: J. Hamilton
Thursday September 29th 2022 12:00 AM
Peter Nordlander, Rice University
Plasmonics: From Quantum Effects to Fano Interference and Light Harvesting
The "plasmon hybridization"concept shows that the plasmon resonances in complex metallic nanostructures interact and hybridize in analogous to the way atomic orbitals hybridize to form molecular orbitals in molecules. The insight gained from this concept provides an important conceptual foundation for the development of new plasmonic structures that can serve as substrates for surface enhanced spectroscopies, chemical and biosensing, and subwavelength plasmonic waveguiding and other applications. The talk comprises an introductory overview interspersed with a few more specialized "hot topics" such as plasmonic Fano resonances, quantum plasmonics, quantum plexcitonics, and active plasmonic nanoantennas for enhanced light harvesting and plasmon induced chemical reactions.
Host: R. Haglund
Thursday October 6th 2022 12:00 AM
Casey Miller, University of South Florida
Search for Spin Seebeck Effect in in situ grown magnetic thin film structures
The Spin Seebeck Effect (SSE) is a phenomenon in which the application of a temperature gradient cross a ferromagnet causes a measurable electric potential difference transverse to the gradient, as transduced via the Inverse Spin Hall Effect (ISHE) in a normal metal in contact with the ferromagnet. Measuring the SSE accurately is challenging due to presence of other effects, most notably, the Anomalous Nernst Effect. In this talk, we report our efforts to measure the SSE in thin film structures grown completely in situ, including magnetic thin films of NiFe and Co, using Au and Ta as the ISHE electrodes. The SSE-like signals we measure appear to be dominated by the Anomalous Nernst Effect, which is inferred from a symmetrical voltage signal at the hot and cold ends of the sample, as well as the signal's dependence on the angle between the magnetization and the temperature gradient. This implies the presence of a temperature gradient along the surface normal, which is also indicated by COMSOL simulations. Efforts to eliminate parasitic temperature gradients lead to the Planar Nernst Effect. Our results appear to underscore the extrinsic nature of the Spin Seebeck Effect.
Host: E. Rericha
Thursday October 13th 2022 12:00 AM
Thursday October 20th 2022 12:00 AM
Wayne Hess, Pacific Northwest National Laboratory
Modifying surface atomic structure with light: Laser control of desorption
Understanding the dynamics of electronically excited species in solids is essential to forming mechanistic models of photocatalysis, radiation damage, and energy transfer. Photo-stimulated desorption, of atoms or molecules, provides a direct window into many important processes and is often indicative of electronic excited solid-state dynamics. We use femtosecond and nanosecond lasers to excite specific surface sites (e.g. terraces, step edges, corners) of nano-structured wide-gap ionic crystals and measure velocities and state distributions of desorbed atoms or molecules under highly controlled conditions. Photon energies are chosen to excite specific surface structural features that lead to particular desorption reactions. The photon energy selective approach takes advantage of energetic differences between surface and bulk exciton states and probes the surface exciton directly. We have demonstrated that desorbed atom product states can be selected by careful choice of laser wavelength, pulse duration, and delay between laser pulses. Excited state dynamics in solids is inherently complex and greater understanding is gained using a combined experiment/theory approach. Our experiments are designed specifically to test theoretical models based on the results of ab initio calculations. Our current efforts focus materials such as metal oxides that have broad technological applications and metal-insulator hybrid materials with applications to photocathode research.
Host: R. Haglund
Thursday October 27th 2022 12:00 AM
John Rogers, University of Illinois.
Materials and Mechanics for Bio-Integrated Electronics
Biology is curved, soft and elastic; silicon wafers are not. Semiconductor technologies that can bridge this gap in form and mechanics will create new opportunities in devices that adopt biologically inspired designs or require intimate integration with the human body. This talk describes the development of ideas for electronics that offer the performance of state-of-the-art, wafer-based systems but with the mechanical properties of a rubber band. We explain the underlying materials science and mechanics of these approaches, and illustrate their use in bio-integrated, ‘tissue-like’ electronics with unique capabilities for mapping cardiac electrophysiology, in both endocardial and epicardial modes, and for performing electrocorticography. Demonstrations in live animal models illustrate the functionality offered by these technologies, and suggest several clinically relevant applications.
Host: R. Scherrer
Thursday November 3rd 2022 12:00 AM
Richard Superfine, University of North Carolina
Mucus Clearance: The physics that keeps your lungs clean
The lung maintains an air/blood interface with a surface area the size of half a tennis court. This huge surface area presents a challenge to physiology to maintain a sterile environment in the presence of continual assaults from inhaled environmental pathogens. The body is successful by secreting a layer of mucus, a viscoelastic polymeric fluid, onto the epithelial surface to trap dust and unwanted visitors. This mucus filter is then changed through the continual upward flow due to beating cilia and cough. We are attempting to understand each aspect of this process through biophysical measurements and through the development of engineered biomimetic systems. Using a magnetic microbead assay, we have measured the force developed by individual lung cilia. To understand the response of the mucus, we measure the fluid rheology using driven microbead rheology that reveals the strain thickening behavior due to high shear rates at the surface of micro and nano sized structures. To understand the flows generated by carpets of cilia, we have engineered artificial cilia at the size scale of their biological counterparts and have observed directed flow and enhanced mixing in actuated arrays. Finally, we are challenging our understanding of cilia-generated flows by performing microscopy on the flow of mucus on cell cultures that are tilted so that they need to push mucus upwards - against gravity.
Host: R. Haglund
Thursday November 17th 2022 12:00 AM
Charles Horowitz, Indiana University
Multimessenger Observations of Neutron Rich Matter
Compress almost anything to great densities and electrons react with protons to make neutron rich matter. This material is at the heart of many fundamental questions in Nuclear Physics and Astrophysics. What are the high-density phases of Quantum Chromodynamics? Where did the chemical elements come from? What is the structure of many compact and energetic objects in the heavens, and what determines their electromagnetic, neutrino, and gravitational-wave radiations? Moreover, neutron rich matter is being studied with an extraordinary variety of new tools such as Facility for Rare Isotope Beams (FRIB), an accelerator that is being built at Michigan State University, and the Laser Interferometer Gravitational Wave Observatory (LIGO). We describe the Lead Radius Experiment (PREX) that is using parity violating electron scattering to measure the neutron radius in 208Pb. This has important implications for neutron rich matter, neutron stars, and their crusts. We discuss fusion reactions of neutron rich nuclei as material accretes onto a neutron star. We model neutron rich matter using large-scale molecular dynamics simulations. We find neutron star crust to be the strongest material known, some 10 billion times stronger than steel. It can support large mountains. These concentrated masses, on rapidly rotating stars, can generate detectable oscillations of space and time known as gravitational waves.
Host: Sait Umar
Thursday December 1st 2022 12:00 AM
Dmitri Basov, University of California, San Diego
Many body effects in graphene revealed by infrared nano-imaging
Charge carriers in graphene behave as massless fermions obeying the Dirac equation with an effective speed of light given by the Fermi velocity. Early experiments seemed to suggest that many-body effects play only an insignificant role in the properties of graphene. In conflict with this common view infrared spectroscopy has uncovered rather exotic electrodynamics in graphene inconsistent with the picture of non-interacting Dirac quasiparticles [Nature-Physics 4, 532 (2008), PRL 102, 037403 (2009)]. Recent infrared nano-imaging studies have allowed us to take a much closer look at many-body effects at length scales commensurate with the omnipresent inhomogeneities of realistic samples. The experimental novelty of this work is that we have utilized propagating surface plasmons in graphene to probe losses in the electronic system [Nature 487, 82 (2012), Nano Letters 11, 4701 (2011)]. New nanoscopy data support the notion of strongly interacting electron liquid in graphene. This work – the first direct imaging of Dirac plasmons – also uncovers opportunities for nano-scale control of electromagnetic energy along the surface of graphene, far beyond what is attainable with metal-based plasmonics.
Host: K. Bolotin
Thursday December 8th 2022 12:00 AM
Nicholas P. Bigelow, Department of Physics and Astronomy, University of Rochester
Spinning a Spinor Bose-Einstein Condensate
The spinor Bose-Einstein condensate (BEC) is a degenerate, dilute quantum gas in which the spin state of the atoms provide added degrees of freedom that can be manipulated and studied. The BEC is also a superfluid in which angular momentum is quantized, giving rise, for example, to quantized vortex states similar to the flux vortices in a superconductor. In this talk I will review the physics of the spinor BEC and describe how light beams carrying orbital angular momentum can be used to create novel topological vortex excitations that connect BEC physics to several other fields of physics.
Host: R. Haglund
Thursday December 15th 2022 12:00 AM
Thursday January 13th 2022 12:00 AM
Daniel J Gervais, Law School, Vanderbilt University
Patenting Science: What Can Patent Law Learn From The Traditional Distinction Between Science And Technology
Traditionally, a distinction had been made between non-commercial science (scientific research), on the one hand, and commercial-industrial technology, sometimes bundled under the appellation research and development or applied science, on the other hand. While the distinction is not one that can be easily wrestled to the ground in legal terms, it has often informed patent policy and guided both the USPTO and courts. It also undergirds a number of legislative and judge-made exceptions to patentable subject matter. This traditional distinction may be summarized as follows: Basic science is mostly done in universities and public laboratories, often with government funding. Science produced under this system is then used by the private sector and sometimes universities or university-based researchers to develop (applied) technologies. The distinction is used to delineate the domain of patents : Patents should be granted on technology but not on "basic" science because (a) normatively science is a public good that should not be appropriated; and (b) science does not meet the usual patentability criteria, in particular that a patentable invention be useful (or industrially applicable). The distinction is also used to explain the peer-review process and citations to previous literature that seem inseparable from any definition of the scientific process but are not typical in technological development. This emphasis of communication patterns is probably an essential feature of the distinction: the progress of science is encoded verbally (hence can be seen as a communicative process) while the progress of technology is encoded in physical structures and other commercially viable vectors. In a seminal paper on the topic published in 1987, Professor Rebecca Eisenberg had argued that patent protection should be granted only to technologies that are ripe enough for exploitation and relate to an applied discipline. The erratic evolution of the patentable subject-matter caselaw (trending towards the patenting of research tool and basic science) and the elimination of the experimental use exception points to the need to revisit her conclusions and reoperationalize her insights.
Host: R. Scherrer
John A. Johnson, Assistant Professor of Astronomy. California Institute of Technology
Searching for Earths Next Door
Thanks to the dedicated efforts of planet hunters over the past decade and a half, we now know that the Galaxy is positively teeming with low-mass planets. In particular, the highly successful NASA Kepler mission has ushered us from the era of hunting to a time of plentiful gathering. To meet this paradigm shift, we are designing and building a new observing facility dedicated to the detection of the Earth-like planets around nearby stars. The facility, named Project Minerva, is based on the concept of constructing a larger effective telescope aperture by combining many small, roboticized telescopes. I will present the motivation for our survey by highlighting the exciting planet discoveries from the Kepler mission. I will then present our novel approach of using Project Minerva to extend our knowledge of low-mass planets from the distant Kepler field to the stars right next door to the Sun.
Hosts: K. Stassun and D. Weintraub
Thursday January 27th 2022 12:00 AM
Despina Louca, Physics Department, University of Virginia
Emergent Properties in Perovskite Cobaltites
Spatially inhomogeneous states are ubiquitous in complex transition metal oxides. Such states are the result of competing mechanisms resulting from strong interactions among the viable degrees of freedom, be it spin, charge, orbital and lattice. Associated with this complexity is a tendency for new forms of order such as the formation of stripes or phase separation, and an enhanced response to external influences. In this talk, I will describe the nature, origin and organization of various such states as observed in the cobalt perovskite oxides. The results will be predominantly from neutron scattering experiments used to probe both the static and dynamic structures.
Host: S. Pantelides
Thursday February 3rd 2022 12:00 AM
Thomas Orlando, School of Chemistry and Biochemistry and School of Physics , Georgia Institute of Technology
Very low-energy electron-induced damage of DNA
We have examined theoretically and experimentally the low energy (1-25 eV) electron-induced damage of DNA oligomers. Specifically, we have calculated the elastic scattering of 5-30 eV electrons within the B-DNA 5'-CCGGCGCCGG-3' and A-DNA 5'-CGCGAATTCGCG-3' sequences using the separable representation of a free-space electron propagator and a curved wave multiple scattering formalism. The disorder brought about by the surrounding water and helical base stacking leads to featureless amplitude build-up of elastically scattered electrons on the sugars and phosphate groups for all energies between 5-30 eV. However, some constructive interference features arising from diffraction were revealed when examining the structural waters within the major groove. These appear at 5-10, 12-18 and 22-28 eV for the B-DNA target and at 7-11, 12-18 and 18-25 eV for the A-DNA target. Though the diffraction depends upon the base-pair sequence, the energy dependent elastic scattering features are primarily associated with the structural water molecules localized within 8-10 Å spheres surrounding the bases and/or the sugar-phosphate backbone. The electron density build-up occurs in regions of electron attachment resonances, direct electronic excitation and dissociative ionization. We correlated these scattering features with our measured DNA single and double strand breaks and suggested that states involving major groove waters may be important in low-energy electron induced damage of DNA. Compound resonance states involving interfacial water and excitation energies > 5 eV seem to be required for lethal double strand breaks. We have also recently extended this work to excitation energies below 5 eV by examining the damage using Raman-microscopy and scanning electrostatic force microscopy. Very efficient damage via single strand breaks is observed below 5 eV excitation energies. This involves π* negative ion resonances that are initially localized on the bases but transferred to the σ* states of the sugar-phosphate bond. The efficacies of these channels depend upon the base-pair sequences as well as the presence of water.
Hosts: E. Rericha and N. Tolk
Thursday February 10th 2022 12:00 AM
Thursday February 17th 2022 12:00 AM
Thursday February 24th 2022 12:00 AM
Thomas Yankeelov, Institute of Imaging Science, Vanderbilt University
Building Tumor Forecasts from Noninvasive Images and Biophysical Models
At the turn of the 20th century, meteorology was in its infancy and weather forecasts were based on historical trends, intuition, and guesswork. It was not until the development of realistic physical models of atmospheric phenomena as well as advances in data acquisition and computation that accurate weather prediction became a reality. At the onset of the 21st century, our approach to cancer treatment resembles the early days of weather forecasting. We argue that the development of clinically relevant spatiotemporal mathematical modeling of tumor growth and treatment response should meet a fundamental pre-requisite: the ability to incorporate quantitative data from the individual patient. We will present preliminary evidence that emerging imaging methods can provide such data to initialize and constrain realistic biophysical models to predict treatment response on an individual basis. We will conclude with a discussion of how such an approach has the potential to usher in a new era in which the forecasting power of biophysical modeling in oncology is realized.Presentation
Host: E. Rericha
S. James Gates Jr., Department of Physics, University of Maryland
Symmetry and the Quincunx Nexus
From the time of the ancient Greeks until today, the concept of symmetry has often been an important, but little understood concept, driving advances in physics. This presentation will strive to take an audience from understanding this link to its direct impact on ideas in Superstring/M-Theory and at one of its boundary where there appears to be a 5-fold overlap with other human ways of interpreting the universe.
Host: R. Scherrer
Szabolcs Marka, Walter O. LeCroy Jr. Associate Professor of Physics, Columbia University
Multimessenger Astronomy from Instruments to Open Questions
Gravitational-waves, frequently conceptualized as "ripples in the fabric of spacetime," carry information about crucial aspects of extremely energetic cosmic processes that are usually hidden from us, such as the birth and the death of black holes and neutron stars. While Einstein predicted the existence of gravitational waves, they have never been detected directly. Scientists expect that to change soon, and they hope that Nature will help us answer myriads of questions: Was Einstein right once again or will alternative theories of gravity prevail? Is there a hidden population of black holes in the core of galaxies? What happens deep down in the heart of a supernova at the moment of its explosion? New instruments being constructed might offer insight on some of these exciting puzzles as well as the possibility that the most exciting phenomenon discovered by gravitational-wave astrophysics may be completely unforeseen!
Host: N. Tolk
Thursday March 17th 2022 12:00 AM
Ilias Perakis, Physics Department, University of Crete and the Foundation of Research and Technology-Hellas, Heraklion, Crete, Greece
Quantum tricks in the shadows of relativity and the Coulomb force: teaching devices how to think ultra-fast
The technological demand to bump the gigahertz switching speed limit of today's magnetic memory and logic devices into the terahertz regime underlies the entire field of spin-electronics and integrated multi-functional nano-devices. In this talk, I use theory and experiment to show how this challenge could be met by all-optical switching based on the quantum-mechanical manipulation of spins with a train of phase-coherent femtosecond laser pulses. By analogy to femto-chemistry and photosynthetic dynamics—in which photoproducts of bio-chemical reactions can be influenced by creating suitable superpositions of molecular states—we have demonstrated that femtosecond-laser-excited quantum coherence between electronic states can control the four-state memory of magnetic semiconductors and switch, within a mere 100 femtoseconds, the magnetic order of colossal magneto-resistive manganite quantum materials. The creation of magnetic correlations within femtoseconds, even faster than one period of lattice oscillations, reveals a new quantum-coherent temporal regime of magnetism that is clearly distinguished from the previously-observed picosecond lattice-heating regime. References: T. Li, A. Patz, L. Mouchliadis, J. Yan, T. Lograsso, I. E. Perakis, and J. Wang, Nature (in press, 2013), M. Kapetanakis, P. Lingos, C. Piermarocchi, J. Wang, and I. E. Perakis, Appl. Phys. Lett. 99, 091111 (2011), M. Kapetanakis, I. E. Perakis, K. Wickey, C. Piermarocchi, and J. Wang, Phys. Rev. Lett. 103, 047404 (2009); J. Chovan, E. Kavousanaki, and I. E. Perakis, Phys. Rev. Lett. 96, 057402 (2006).
Host: S. Pantelides
Thursday March 24th 2022 12:00 AM
Walt Harris, Department of Applied Science, University of California, Davis
Exploring the Heliopause through polarimetric remote sensing of boundary crossing interstellar hydrogen.
The heliosphere can be defined as the region of space where the Sun's influence dominates over that of the local interstellar medium (LISM). Its outer boundary, the heliopause, is established through a plasma pressure balance between the outward-streaming magnetized solar wind and the ionized component of the LISM. The exact physical extent of the heliosphere is unknown, but it is believed to be vast, extending up to several hundred AU in the direction of relative motion between the LISM and solar system and perhaps thousands of AU in the downstream wake. These scales are well beyond the reach of most existing spacecraft, leaving remote sensing as the best technique available to us for probing the interface. For over 40 years a reliable, if infrequently used, method of studying the heliopause has been to monitor the bulk velocity and velocity distribution of interplanetary hydrogen (IPH) that has crossed the barrier from the LISM after undergoing charge exchange reactions with decelerating plasma. The IPH is detectable from resonance scattering of solar H Ly-a emission, but there is a solar cycle component to the velocity that comes from variable radiation pressure that must be accounted for. In this presentation, I will discuss the current state of our understanding of the IPH and describe a new experiment we are constructing to better confine the parameters of the observed emission.
Host: W. Johns
Thursday March 31st 2022 12:00 AM
Nitin Samarth, Department of Physics, Penn State University
Spin control in semiconductors and topological insulators
The manipulation of electron spins in solid state devices via electric, magnetic and exchange fields is a core concept in spintronics [1,2]. This talk will provide a general overview of key advances in the development of this field, highlighting the role of the spin-orbit interaction in controlling electron spin polarization in conventional semiconductors  and in the more contemporary context of "topological insulators [4-6]. REFERENCES: 1. D. D. Awschalom, M. E. Flatte and N. Samarth, Scientific American 286, 67 (2002). 2. N. Samarth, Solid State Physics 58, 1 (2004). 3. D. D. Awschalom and N. Samarth, Physics 2, 50 (2009). 4. S.Y. Xu et al., Nature Physics 8, 616 (2012). 5. D.M. Zhang et al., Phys. Rev. B 86, 205127 (2012). 6. A. Kandala et al., arxiv 1212.1225.
Host: R. Scherrer
Thursday April 7th 2022 12:00 AM
Brian D. Storey, Olin College of Engineering
The nonlinear dynamics of blood flow patterns through capillaries
Non-linear dynamics in simple fluid networks A classic and useful problem in the field of hydraulics is determining the distribution of flow rates inside a piping network for fixed inlet conditions. In 1936, a structural engineer named Hardy Cross revolutionized the analysis of hydraulic networks by developing a method by which one could reliably solve these problems by hand calculation. While the Hardy Cross method has been made obsolete by computer techniques, the problem can again become intractable if one considers networks filled with a fluid comprised of multiple phases. The phase distribution within fluid networks may exhibit non-linear behavior such as multiple stable equilibrium states and the emergence of spontaneous oscillations. Such behavior has been observed or predicted in a number of different networks, both man-made and natural, at a variety of scales. Examples include the flow of blood through the microcirculation, the flow of picoliter droplets through microfluidic devices, the flow of magma through lava tubes, two-phase flow in refrigeration systems and water flow in solar steam generators. The existence of non-linear phenomena in a network with many inter-connections containing fluids with complex rheology (such as blood in the microvasculature) may seem unsurprising. However, even the simplest networks with ordinary fluids can demonstrate rich behavior. In this talk, I will discuss recent and ongoing work to understand the phase distribution in simple networks. Experiments demonstrate that multiple equilibrium states are common in many ordinary systems. Theoretical results with microvascular models indicate that chaotic dynamics which are reminiscent of the Lorenz attractor can emerge under the right conditions.
Host: E. Rericha
Thursday April 14th 2022 12:00 AM
Sheila Kannappan, University of North Carolina, Chapel Hill
Global Gas Content Trends Across the Galaxy Population
Patterns in global atomic and molecular gas content as a function of mass, environment, and evolutionary state provide key insights into the physics of gas fueling and star formation in galaxies. I will present results from several z=0 surveys pointing to clear transitions between gas accretion/processing regimes that couple to transitions in galaxy morphology and to a lesser extent mass and environment. Contrary to popular wisdom, bulgeless dwarf galaxies appear to be experiencing rapid gas accretion and stellar mass growth in their typical low-density environments. In contrast, "normal" spiral galaxies like our Milky Way seem to represent transient though efficient gas-processing states, mostly on the way to becoming "dead" spheroids in dense environments. Intriguingly, some low-mass spheroids seem to represent gas-rich merger remnants capable of accreting fresh gas and (re)building spiral disks.
Host: K. Holley-Bockelmann
Thursday April 21st 2022 12:00 AM
Lyman Page, Physics Department, Princeton University
Neutrinos and the cosmic microwave background
Nine years of WMAP data on the cosmic microwave background (CMB) radiation, combined with additional measurements such as baryon acoustic oscillations in the distribution of galaxies, have ushered in an unprecedented era of precision cosmology. The standard λCDM cosmological model has passed many stringent tests, and its basic parameters have been tightly constrained. The standard model is now so well established that we may use it as a foundation to address such questions as "What is the sum of the neutrino masses?" and "How many neutrino-like species are there?" Forthcoming results from ESA's Planck mission, ever more precise ground-based CMB observations, and new neutrino detectors promise to take precision cosmology and astroparticle physics to new heights. We review the status of observations and recent results.
Host: R. Scherrer
Marina Artuso, Department of Physics, Syracuse University
New physics through beauty: snapshots from LHCb
The LHCb experiment at LHC is the first experiment operating at a hadron collider dedicated to the study of heavy flavor decays. One of its key purposes is the search for signatures of new physics manifestations in beauty and charm meson decays. I will present an overview of the properties of the LHCb detector that are crucial to its performance, and give some highlights of the most exciting measurements performed in the course of its first three years of operation.
Host: W. Johns
Phil Nelson, University of Pennsylvania
Physics of human and superhuman vision
Scientists often seem to be asking obscure theoretical questions. But sometimes, asking such questions and doggedly following the answers leads to unexpected practical payoffs, as well as deep insights into how the world works. I'll explore how the question, "What is light?" leads us to an understanding of how we see, and also to some powerful new ways to see things. These advances have recently given us breathtaking results in biomedical imaging, and new ways to break through a resolution barrier that had been thought sacred for over a hundred years.
Host: E. Rericha
Thursday May 5th 2022 12:00 AM
Travis Taylor, Redstone Arsenal, Huntsville, Alabama
The Universal Quantum Connection: Stay With it and You CAN Control Your Universe!
13.5 Billion years ago or so the universe was a single tiny infinitesimal point with infinite energy density we call the "Big Bang Singularity". The universe was a single connected mass of energy. For whatever reason the universe then expanded to what we see today. All that exists today is still a part of that single connected mass of energy but from our perspective within it we see objects as discrete entities. In reality, everything in the universe is actually a piece of that universe and, if we were smart enough, could represent all with a Universal Quantum Wave function showing coupling to and between all things through Einstein's "spooky action at a distance". Dr. Taylor will discuss this aspect of reality and how it applies to all aspects of physics from the nano to the macroscopic going into detail about light, Young's double slit experiment, and the Thompson-Wolf experiment. The information once understood can be implemented in everyday life to achieve goals like building rockets, Iron Man suits, finishing college, and having your own t.v. show!
Host: E. Rericha
Tuesday May 24th 2022 7:30 PM
Joe Incandela Leader (Spokesperson) of the CMS Experiment University of California Santa Barbara/CERN
Probing deep into the fabric of space and time: The discovery and latest results on the Higgs boson
The Large Hadron Collider (LHC) at the European laboratory for nuclear research (CERN) near Geneva Switzerland performed spectacularly well in its first running period from December 2009 through February 2013. Data of unprecedented quality and quantity have been recorded for proton-proton collisions at energies of 7 and 8 Trillion electron Volts – the highest energies ever. In this lecture, Joe Incandela will give an overview of the decades-long, worldwide effort to construct and operate the LHC accelerator and the ATLAS and CMS experiments that together represent the largest, most complex system ever built for physics research. The science program will be reviewed with emphasis on the Higgs boson whose role in our universe is profound, and whose properties may have extraordinary implications. Highlights from the discovery announced July 4th will be shown, followed by recent results obtained with much more data. References:  http://cms.web.cern.ch/  http://atlas.web.cern.ch/  https://twiki.cern.ch/twiki/bin/view/CMSPublic/PhysicsResults  https://twiki.cern.ch/twiki/bin/view/AtlasPublic
Host: P. Sheldon