Colloquia 2018 Spring

  • 1/11/2018
    • Speaker  No colloquium this week
    • Affiliation
    • Title
    • Abstract
  • 1/18/2018
    • Speaker Allison Grow
    • Affiliation North Florida Cancer Center and CyberKnife
    • Title The Emperor of All Maladies Meets the Queen of Sciences: A Whirlwind Tour Through Radiation Oncology
    • Abstract 60% of all patients diagnosed with malignant disease, as well as a number with benign disease, will be treated with radiotherapy at some point during their course. I will provide a review of indications, useful concepts, techniques​, and new directions, from the perspective of a practicing clinician in a busy community oncology program.
  • 1/25/2018
    • Speaker Stephan Rosswog
    • Affiliation Stockholm University
    • Title Multi-messenger signals from gravitational wave sources
    • Abstract Neutron star mergers had long been suspected to produce gravitational
      wave "chirps", gamma ray bursts and produce r-process elements.
      While overall convincing, all these conjectures were based on indirect
      arguments and none was proven directly.
      This changed on August 17, 2017: a gravitational wave signal from a
      merging neutron star binary was detected, closely followed by a
      short gamma-ray burst and  transients accross the electromagnetic
      spectrum coming from the radioactive decay of freshly synthesised r-process
      elements. In this talk I will give an overview over these recent, very
      exciting developments.
  • 2/1/2018
    • Speaker Michael Bachmann
    • Affiliation UGA
    • Title The Broken Geometry of Life as a Reason of Us Being
    • Abstract For decades, theoretical physics has often been guided by the idea that
      "symmetry is beautiful" - problems could simply be solved easier once
      symmetries were identified. However, it became quickly apparent that Nature
      does not entirely comply. Symmetry-breaking was found to be an important
      process that enabled complexity, diversity, flexibility - and life. One of
      the most obvious geometric symmetry-breaking processes is the melting of a
      crystal. Long-range bulk order turns into short-range domain order and
      long-range disorder. Resulting liquid phases are dominated by the competition
      of these ordering and disordering principles: energy vs entropy. A liquid is
      capable of changing its properties quickly in perfect adaptation to the
      environmental conditions. Therefore, it is not surprising that lifeforms are
      composed of liquid objects of finite size, cells, containing the
      macromolecular machinery that makes life possible. For the understanding of
      this "soft matter," statistical mechanics had to be brought to new life,
      after it had mainly been used in the past to study very large systems (to
      avoid dealing with cumbersome surface effects). Adopting statistical physics
      for understanding the behavior of biological matter is a modern challenge,
      only made possible by powerful computational facilities nowadays available
      and the realization that some physical problems can only be solved
      algorithmically. In this talk, some of the challenges in modeling and
      simulation, and statistical analysis of biomacromolecular systems and
      structural phase transitions accompanying protein folding, polymer
      aggregation, and adsorption processes are discussed. Clues are presented, but
      certainly more questions will be raised than answers given. E
  • 2/8/2018
    • Speaker Casey Miller
    • Affiliation Rochester Institute of Technology
    • Title Admissions Criteria and Diversity in STEM Graduate Programs
    • Abstract The National Academies have suggested that increasing diversity in Science, Technology, Engineering, and Math will be critical to the future competitiveness of the US in these areas [1], and the National Science Foundation [2], the American Physical Society [3], and the American Astronomical Society [4] are taking this seriously.  In this talk, I will discuss several opportunities that may help move toward meeting this goal, and, importantly, the potential benefits to programs and individual investigators willing to take on these challenges. The most universally applicable and implementable actions regard perturbing graduate admissions policies and practices [5-7], and employing key features of successful Bridge Programs into graduate programs [8].  Despite the prevalent use of minimum acceptable scores by admissions committees, there is no correlation between GRE scores and PhD completion in physics. I will remind the community that the use of minimum acceptable GRE scores for admissions is in opposition to ETS’s Guide to the Use of GRE Scores, and I will present data showing that this practice will have (has had?) a negative impact on diversity in graduate programs.  I will conclude by discussing non-cognitive competencies and their potential utility in selection processes in the physical sciences [9].  
      [1] National Academy of Sciences, National Academy of Engineering, and Institute of Medicine, “Expanding Underrepresented Minority Participation: America's Science and Technology Talent at the Crossroads,” The National Acadamies Press (2011);
      [2] Joan Ferrini-Mundy, “Driven by Diversity,” Science 340, 278 (2013).
      [5] Casey W. Miller, “Admissions Criteria and Diversity in Graduate School,”APS News, The Back Page, February 2013.
      [6] Casey W. Miller and K. G. Stassun, Nature 510, 303-304 (11 June 2014) | doi:10.1038/nj7504-303a
      [7] Julie R. Posselt Inside graduate admissions: Merit, diversity, and faculty gatekeeping. Harvard University Press (2016).
      [8] Stassun, K.G., Sturm, S., Holley-Bockelmann, K., Burger, A., Ernst, D., & Webb, D., “The Fisk-Vanderbilt Masters-to-PhD Bridge Program: Broadening Participating of Underrepresented Minorities in the Physical Sciences. Recognizing, enlisting, and cultivating ‘unrealized or unrecognized potential’ in students”, American Journal of Physics 79, 374 (2011).
      [9] Casey W. Miller, “Using Non-Cognitive Assessments in Graduate Admissions to Select Better Students and Increase Diversity”, STATUS, p1, January (2015)
  • 2/15/2018
    • Speaker David Mitzi
    • Affiliation Duke University
    • Title Halide Perovskites: Structural Diversity and Opportunities for Semiconductor Design and Fabrication
    • Abstract Although known for more than a century, organic-inorganic hybrid and related inorganic halide-based perovskites have received extraordinary attention recently, because of the unique physical properties of the lead(II)-based systems, which make them outstanding candidates for application in photovoltaic (PV) and related electronic devices. Despite the high levels of device performance, incorporation of the heavy metal lead, coupled with issues of device stability and electrical hysteresis pose challenges for commercializing these exciting technologies. This talk will explore beyond the current focus on three-dimensional (3-D) lead(II) halide perovskites (e.g., CH3NH3PbI3), to highlight the great chemical flexibility and outstanding potential (and challenges) of the broader 3-D and lower-dimensional perovskite family. As part of the discussion, the prospects for replacing lead with other metals, the importance of structural dimensionality for determining semiconducting character, along with the promise for both inorganic and organic structural components to play an active role in determining the overall hybrid semiconducting character, will be emphasized. Beyond structural flexibility, the talk will further discuss how chemical flexibility leads to an unusually large range of processing options for preparing high-performance perovskite films. Outstanding functionality combined with versatile/facile processing provide two pillars for future application and study of this materials family.
  • 2/22/2018
    • Speaker Daniel Stolarski
    • Affiliation Carleton University
    • Title The Nature of the Higgs Boson
    • Abstract With the discovery of the Higgs boson at the Large Hadron Collider, we
      have begun to uncover the nature of electroweak symmetry breaking: how
      elementary particles acquire mass. I will describe the underlying
      theory of particle physics, the Standard Model, and how it is now
      completed by the Higgs. I will also explain the theoretical framework
      used to go from seeing a bump in certain experimental distributions to
      being sure this discovery is in fact a Higgs boson. Finally, I will
      describe the shortcomings of the Standard Model, focusing on the
      hierarchy problem, and show how future measurements of the Higgs can
      shed light on some of the mysteries of our universe.
  • 3/1/2018
    • Speaker Kate Scholberg (PDF of talk)
    • Affiliation Duke University
    • Title CEvNS and NINs: observation of coherent elastic neutrino-nucleus scattering by COHERENT
    • Abstract Coherent elastic neutrino-nucleus scattering (CEvNS) is a process in
      which a neutrino scatters off an entire nucleus and for which the
      observable signature is a tiny nuclear recoil. The process was first
      predicted in 1973.  It was measured for the first time by the COHERENT
      collaboration using the unique, high-quality source of neutrinos from
      the Spallation Neutron Source (SNS) at Oak Ridge National Laboratory
      and a cesium iodide crystal scintillator detector.  This talk will
      describe COHERENT's recent measurement of CEvNS, the status and plans
      of COHERENT's suite of detectors at the SNS, and future physics reach.
  • 3/8/2018
    • Speaker Rodi Herzberg
    • Affiliation University of Liverpool
    • Title Alchemy in the 21st century - the quest to understand superheavy elements
    • Abstract

      A chemical element is characterised by the total number of positively charged protons in the atomic nucleus. The interplay between the attractive short range strong force and the repulsive long range Coulomb force leads to a limit in the number of protons and neutrons that can be bound in a nucleus. Today single atoms of elements up to Z=118 have been created in the laboratory.

      Super heavy nuclei are so finely balanced on the edge of stability that they provide extremely sensitive testing grounds for nuclear models. With the advent of modern detection systems structural investigations are possible in systems ever further from stability, including the determination of shape and single particle structure, chemical properties, and the unique identification of the precise atomic number of the produced nuclei via X-ray fingerprinting.

  • 3/15/2018
    • Speaker No colloquium - Spring Break
    • Affiliation
    • Title
    • Abstract
  • 3/22/2018
    • Speaker Pawan Kumar
    • Affiliation University of Texas, Austin
    • Title The mystery of Fast Radio Bursts, and its possible resolution
    • Abstract Fast radio bursts (FRBs) are millisecond duration transient events of
      unknown physical origin that were discovered in pulsar surveys at GHz
      radio frequency in 2007. About a year ago it was established that
      these bursts are located at a distance of several billion light years
      away. And therefore the energy release in the radio band in these events
      is quite large. Using very general arguments I will show that the radio
      emission is coherent, the magnetic field strength associated with the
      source of these events should be 10^{14}Gauss or more, and the electric
      field is of order 10^{11} esu. I will describe the recent work of my group
      that magnetic reconnection is likely to be responsible for the strong
      electric field and the coherent radiation produced in these enigmatic
  • 3/29/2018
    • Speaker Kenneth Taylor
    • Affiliation FSU Biology
    • Title The origins of cryoelectron microscopy, its development into the hottest technique in Biophysics, and its future directions
    • Abstract Cryoelectron microscopy (cryoEM) has become the technique of choice for determining the structure of biological specimens Its development from a fringe technique to its prominence today took a long incubation period with important contributions from many scientists, three of the most prominent of which received the 2017 Nobel Prize in Chemistry. This lecture will cover the very early development of cryoEM and its evolution into the powerful technique that it has become in recent years and where opportunities for dramatic further advances are likely to come in the future.
  • 4/5/2018
    • Speaker Thomas Glasmacher
    • Affiliation Michigan State University
    • Title Building the Facility for Rare Isotope Beams
    • Abstract Once every decade or two, the Office of Nuclear Physics in the U.S. Department of Energy Office of Science embarks on building a new accelerator-based user facility to enable nuclear scientists to make discoveries. Following construction starts for CEBAF in the 1980’s and for RHIC in the 1990’s, the Facility for Rare Isotope Beams (FRIB) project started in 2009. Nine years later, FRIB construction is 83% complete and being managed to early completion in 2021. I will give an overview of FRIB science, science driving design decisions, and construction progress accomplished by a committed team from around the world to deliver FRIB for a community of 1,400 scientists.
  • 4/12/2018
    • Speaker Neil Johnson
    • Affiliation U. Miami
    • Title Physics of Extremes — and Extremism
    • Abstract Our view of the world and universe — from Physics to Biology, Medicine and the Social Sciences — tends to focus on there being an average behavior with fluctuations. However the world is more complex than this, and it is the fluctuations and extremes that often dictate the long-term behavior that we care about, both intellectually and in terms of practical consequences. In this talk, I will try to convince you that such extremes offer a wealth of interesting Physics — and hence opportunities for physicists -- related to many-body out-of-equilibrium systems, complex dynamical networks, critical phenomena, kinetic theory, and even Green's Functions and Feynman diagrams [e.g. NFJ et al., Science 2016; 2017]. Moreover there now exist ‘big’ spatiotemporal datasets to test out these claims. I will also argue that this is not just about providing something new for Physics, but rather that Physics is uniquely positioned to offer key insights into important ‘many-body problems’ in other fields.
  • 4/19/2018
    • Speaker Toyoko Orimoto
    • Affiliation Northeastern University
    • Title Exploring the High Energy Frontier with Precision Electromagnetic Calorimetry: CMS ECAL & the Search for di-Higgs Production
    • Abstract The Compact Muon Solenoid (CMS) detector, located at the CERN Large Hadron Collider (LHC), was designed with the goals of elucidating the origin of electroweak symmetry breaking and discovering new physics at the high energy frontier. A crucial component of the discovery of the Higgs boson was the excellent energy resolution of the CMS electromagnetic calorimeter (ECAL), which is made of 75k scintillating lead tungstate crystals. Despite the discovery of the Higgs, a number of tensions persist in the standard model of particle physics, urging further exploration of the high energy frontier. As such, a high-luminosity upgrade is planned for the LHC (HL-LHC), and the CMS detector will undergo an extensive Phase II upgrade program to prepare for the challenging environment of the HL-LHC. In particular, the ECAL barrel read-out electronics will be upgraded to accommodate the higher event rates and latency required at the HL-LHC. A major benchmark for the CMS physics program at the HL-LHC will be the measurement of di-Higgs production, which allows us to probe the Higgs self-coupling and can illuminate the vacuum stability of the universe.  The most sensitive channel for standard model di-Higgs production at the HL-LC is the final state with two photons and two b-quarks will be the most sensitive. In this presentation, I will describe the CMS ECAL detector and the status of the Phase II upgrade for the ECAL barrel. I will also report on the search for di-Higgs production in the two photon and two b-quark final state with Run 2 data, and the prospects for the search at the HL-LHC.
  • 4/20/2018 at 2:30 pm in Keen room 701  - Hagopian Family Lecture (note special day and time)
    • Speaker Ani Aprahamian
    • Affiliation  University of Notre Dame
    • Title Origin of the heavy elements: are gravitational waves from neutron star mergers the answer?
    • Abstract

      The US science academies report on ``Connecting Quarks to the Cosmos'' identified eleven of the most challenging open questions for all of physics in the 21st century. One of these eleven questions included the identification of the site(s) for the production of the heaviest elements found in nature. How were elements Fe to U made?

      Most of the elements above Fe  in the periodic table are thought to have been produced by either the slow (s-process) or rapid (r-process) capture of neutrons in astrophysical environments. The s-process proceeds close to stability and astrophysical sites have been identified, while the r-process allows the production of nuclei much further from stability and potential sites remain mostly unresolved.

      The recent observation of gravitational waves from two neutron star mergers simultaneously with the spectroscopy showed lines from rare earth elements. The questions remain;
      are there enough such mergers?
      are mergers the only source of r-process elements ?

  • 4/26/2018
    • Speaker Jeremiah Murphy
    • Affiliation FSU
    • Title How Do Massive Stars Die?
    • Abstract The title of this talk remains one of the most important and challenging questions in theoretical astrophysics.  The explosive deaths of massive stars, core-collapse supernovae, are some of the most energetic events in the Universe; they herald the birth of neutron stars and black holes, are a major site for nucleosynthesis, influence galactic hydrodynamics, trigger further star formation, and are prodigious emitters of neutrinos and gravitational waves.  Though these explosions play an important and multifaceted role in many cosmic phenomena, the details of the explosion mechanism have remained elusive for many decades.  The fundamental challenge of core-collapse theory is to understand what makes the difference between a fizzled result and successful explosions.  Ultimately, answering this question will require both theory and observational constraints.  In this talk, I will present a unifying theory for core-collapse supernova explosions, and I will present our observational constraints on which stars actually explode.
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