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Dr. Malcolm Chisholm
Chief Innovation Officer
First San Francisco Partners
Oakland, CA
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, Oct. 16, 2019, at 3:00 PM

There will be a reception in the Olin Lounge at approximately 4 PM following the colloquium. All interested persons are cordially invited to attend.

ABSTRACT

“Big Data” is a term that emerged in the early 2000’s to describe both datasets at a very large scale and a set of technologies that could manage these datasets. Since the emergence of Big Data its significance has grown and seems set to expand with anticipated future technological advances. This presentation explores the significance of Big Data in the general academic context, principally why it should matter to both students and researchers. With respect to students, the economic shifts that have occurred due to Big Data in the past 10 years need to be understood if students are to quickly take their place in the workforce without the need for extensive additional training. For researchers, the promise of Big Data must be balanced with the need for sound methodological approaches that may mean extensions of the scientific method that have not be relevant in the past. The presentation will focus on:

· What Big Data is and how it differs to traditional types of data and related technologies

· How the private sector and government have responded to the emergence of Big Data, and how this may affect students’ employment prospects

· The opportunities for research provided by Big Data, along with the increased requirements for data governance, metadata management

· Challenges that have resulted from the widespread adoption of Big Data

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Professor Dmitri Kilin
Department of Chemistry and Biochemistry
North Dakota State University
Fargo, ND
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, Oct. 2, 2019, at 3:00 PM

There will be a reception in the Olin Lounge at approximately 4 PM following the colloquium. All interested persons are cordially invited to attend.

ABSTRACT

Colloidal semiconductor nanostructures demonstrate favorable tuning of the optoelectronic properties facilitated by quantum confinements. The interpretation, understanding, and optimization of fabrication and characterization of nanostructures are assisted by computational modeling of excited state dynamics at the atomistic level. Dynamics of heat and light activated processes is contributed by simultaneous evolution of (I) nuclear and (II) electronic degrees of freedom. (I) The dynamics in nuclear degrees of freedom is dictated by heights of activation barriers and mechanisms to overcome such barriers, including tunneling. A recently developed time dependent excited state molecular dynamics (TDESMD), has been applied to investigate overcoming of barriers in polymerization reactions for cyclohexasilane (Si6H12) precursors for fabrication of solid silicon nanoparticles. (II) Photoinduced dynamics of electronic degrees of freedom is useful in computational characterization of semiconductor nanostructures. Two important factors provide contribution to efficiency, quantum yield (QY), and line-shape of photoluminescence (PL) signal in photoexcited colloidal nanostructures: (a) cascading process of hot carriers cooling via non-adiabatic dissipation of electronic excitation energy to lattice vibrations and (b) distribution of transition energy and oscillator strength in an ensemble, also related to exciton-to-phonon coupling, providing quantitative way to assess thermal broadening of the PL lineshape. The first principles modeling demonstrated correlation between temperature and PL lineshape of Si-quantum dots. The radiative and nonradiative relaxation and multi-exciton processes in methylammonium lead-halide MAPbI3 quantum dots are all found to be affected by quantum confinement, that positively affects PLQY. For nanostructures composed of heavy elements, such as CsPbBr3 colloidal quantum dots, the spin-orbit interaction is found to enable spin-forbidden transitions and to provide additional splitting between transitions energies of states involved in PL and affect rates and efficiencies of the PL. Nanostructures with periodicity such as nanowires and nanotubes provides specific spectral signatures, especially for materials that carry indirect gap feature in bulk form. Electronic transitions with change of electron’s momentum introduce additional pathways of nonradiative relaxation, which facilitate cooling of hot charge carriers.

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Professor Adam Wax
Department of Biomedical Engineering
Duke University
Durham, NC
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, Sept. 25, 2019, at 3:00 PM

There will be a reception in the Olin Lounge at approximately 4 PM following the colloquium. All interested persons are cordially invited to attend.

ABSTRACT

The mechanisms by which cells respond to mechanical stimuli are essential for cell function yet not well understood. Many rheological tools have been developed to characterize cellular viscoelastic properties but these typically have limited throughput or require complex schemes. We have developed quantitative phase imaging methods which can image structural changes in cells due to mechanical stimuli at the nanoscale. These methods are label free and can image cells in culture or flowing through microfluidic
chips, providing high throughput measurements. We will present our single-shot phase imaging method that measures refractive index variance and relates it to disorder strength, which correlates to measured cellular mechanical properties such as shear modulus. Studies will be presented which relate mechanical properties to early carcinogenic events, investigate the role of specific cellular structural proteins in mechanotransduction and track water regulation due to mechanical stress.

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Professor Erin Henslee
Department of Engineering
Wake Forest University
Winston-Salem, NC
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, Sept. 11, 2019, at 3:00 PM

There will be a reception in the Olin Lounge at approximately 4 PM following the colloquium. All interested persons are cordially invited to attend.

ABSTRACT

Dielectrophoresis (DEP), which is the induced motion of particles in non-uniform AC electric fields, is a label-free assay capable of characterizing cells based on their electrophysiological response. By varying the frequency of the electric field, it is possible to produce a profile of cell polarisability; the resultant electrophysiological spectra allow the determination of electrophysiological parameters including effective membrane conductance (Geff, -indicative of ionic transport across the membrane and on its surface), capacitance (Ceff, -indicative of membrane morphology and/or composition) and cytoplasmic conductivity (σcyt, indicative of free ionic concentration within the cytoplasm). In my work, I have applied DEP characterization as a rapid analysis tool in cancer diagnostics, circadian biomarkers, as well as characterizing stages of programed cell death (apoptosis) and drug efficacy. For this talk I will introduce 3DEP, the platform I was part of creating for this analysis, as well as some of the applications and future directions of the work.

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WFU Physics Honor Society (ΣΠΣ) and Department Awards Ceremony
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, May 1, 2019, at 4:00 PM

There will be a reception with refreshments at 3:30 PM in the foyer. All interested persons are cordially invited to attend.

PROGRAM

  • Physics Honor Society (ΣΠΣ) Ceremony
  • Recognition of New Physics Department Majors
  • Physics Awards Ceremony

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Paul W. Ayers, PhD
Department of Chemistry and Chemical Biology
McMaster University, Canada
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, April 17, 2019, at 4:00 PM

There will be a reception with refreshments at 3:30 PM in the lounge. All interested persons are cordially invited to attend.

ABSTRACT

What happens when two substances are mixed together? Does a chemical reaction occur? If so, which chemical bonds are broken? What new chemical bonds are formed? Can we increase the efficiency of the reaction by changing the conditions under which it occurs? Questions like these lie at the core of chemistry. Addressing them requires understanding, at a fundamental level, how the electrons that bind atoms into molecules rearrange during the course of a chemical reaction and, more subtly, how different molecular environments influence these rearrangements. Therefore, in order to understand the nature of the chemical bond, and to master the chemical reactions by which chemical bonds are fractured and formed, we must uncover the inner lives of electrons.
The physical laws regulating how electrons behave in a molecular environment are encapsulated by the electronic Schrödinger equation. Unfortunately, highly-accurate solutions to the Schrödinger equation are rarely available for molecules containing more than four electrons, while most molecules of interest to chemists contain hundreds, or even thousands, of electrons. This impels the development of approximate models for electronic behavior. Such models are only effective in certain special cases. For example, it is relatively easy to describe cases where the electrons in a molecule move nearly independently, so that the motion of one electron does not affect the other electrons very much. It is also relatively easy to describe cases where the electrons in a molecule are rigidly correlated, so that moving one electron causes the other electrons to move in a nearly deterministic way. The electrons in most chemical substances lie between these two extremes, and developing practical computational methods for these in-between cases is the primary challenge of modern quantum chemistry. In this talk, I will reveal how quantum chemists develop new models for the behavior of electrons in molecules and materials. Some of the new methods are practical even for large molecules containing hundreds of electrons.

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Jennie Traschen, PhD
Department of Physics
University of Massachusetts Amherst
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, April 10, 2019, at 4:00 PM

There will be a reception with refreshments at 3:30 PM in the lounge. All interested persons are cordially invited to attend.

ABSTRACT

The Laws of Thermodynamcis, and the properties of Black Holes, are two topics that have long engaged both our imagination and calculational stamina. The formal identification of the area and surface gravity of a black hole horizon as an entropy and a temperature respectively, was made into a physics connection by Hawking’s 1975 calculation that classical black holes radiate quantum mechanical particles. Subsequently the field of black hole thermodynamics has expanded to study black holes in different environments, including black holes with a cosmological constant Λ. Here we will focus on that case of a positive Λ, which plays important roles in cosmology– whether as a GUT (Grand Unified Theory) scale Λ that drives the rapid expansion of the universe during an inflationary epoch, or the milli-eV scale Λ that models the observed dark energy in our universe today. Black holes with Λ > 0 have fascinating properties that are distinct from the asymptotically flat Λ = 0 case, starting with the fact that there are two horizons in the spacetime, one black hole and one cosmological. Hence there are two (generally unequal) temperatures, and two horizon areas that contribute to the total gravitational entropy. Both the mass M and entropy S are bounded between minimum and maximum values. There is a peak in the heat capacity ∂M/∂T as well as in the curve ∂S/∂T, which resemble the Schottky anomaly of a two level system in statistical mechanics. This talk will start with an introduction to black hole thermodynamics and particle production, and then discuss classical and quantum mechanical features of the cosmological black hole system that resemble the physics of a paramagnet.

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Randall D. Ledford, PhD
Wake Forest Alumni
Retired CTO of Emerson Electric Company
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, April 3, 2019, at 4:00 PM

There will be a reception with refreshments at 3:30 PM in the lounge. All interested persons are cordially invited to attend.

ABSTRACT

Dr. Ledford is this year’s winner of the Distinguished Alumni award. He recently retired as Chief Technology Officer of Emerson Electric Company, one of the world’s leading electronics companies. After graduating from Duke, Dr. Ledford joined Bell Telephone Labs in New Jersey where he worked on microwave communication leading to today’s cell phone communication. Before joining Emerson Electric Dr. Ledford was president and general manager of several divisions of Texas Instruments Inc. including software, digital imaging, enterprise solutions and process automation. Dr. Ledford also generously sponsors scholarships for physics undergraduate majors here at Wake Forest University. He will be speaking about …Emerson Corporation, a global manufacturer of industrial and residential products focusing on the technical and engineering challenges on business in today’s economic climate. Dr. Ledford graduated from WFU with honors in physics (with the assistance of a very young Bill Kerr) and received his Ph.D. in nuclear physics from Duke University.

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WFU Physics Career Advising Event

SPEAKER:  Dr. Heather Bedle, Assistant Professor, Conoco Philips School of Geology and Geophysics, University of Oklahoma

TIME: Wednesday, March 27, 2019, from 12:00 – 1:00 PM

PLACE: Olin Physical Laboratory, Lounge

Lunch will be provided. All interested persons are cordially invited to attend.

Dr. Bedle received her BS in Physics from WFU in 1999.  She initially worked in the defense industry, focusing on signal analysis physics for the development of various antenna and radar systems.  After a few years working as an engineer, Dr. Bedle then decided to go to graduate school for a degree in geophysics, studying earthquakes and velocity structure of the Earth.  After being granted her PhD in 2008 from Northwestern University, she went to work in the petroleum industry, where she further developed her seismic analysis and rock physics skills – all based on physics which she initially learned at WFU.  In 2016, Dr. Bedle left her industry job to instruct graduate-level applied geophysics courses at the University of Houston, and recently started a tenure-track position at the University of Oklahoma.

Dr. Bedle’s research interests focus primarily on combining a range of techniques across the disciplines of geophysics, petrophysics, and geology to further improve our understanding of the subsurface through seismic interpretation.  Her research works to refine and employ a wide range of interpretation tools and workflows from multiattribute seismic analysis, geostatistics, and seismic geomorphology to rock physics modeling.

Dr. Bedle is currently working on a variety of projects including improving the seismic identification of gas hydrate zones in the subsurface, as well as techniques to improve reservoir characterization and prediction on the sub-seismic scale, and seismic tomography.

For this Career Advising Event, Dr. Bedle will discuss her non-linear career path and will close the event with an interactive Q&A session.

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Heather Bedle, PhD
School of Geology and Geophyics
University of Oklahoma
George P. Williams, Jr. Lecture Hall, (Olin 101)
Wednesday, March 27, 2019, at 4:00 PM

There will be a reception with refreshments at 3:30 PM in the lounge. All interested persons are cordially invited to attend.

ABSTRACT

Methane gas hydrates buried in the shallow crust of the Earth are often difficult to image with current geophysical techniques.  Understanding their extent in the crustal subsurface is important as they play a role as a future energy source.  In addition, if the clathrates are destabilized from their solid form to a gas, they can enter the atmosphere and affect the climate as methane is a greenhouse gas.  To improve subsurface mapping techniques of gas hydrates, Dr. Bedle and her research group have been approaching the imaging and detection problem by combining rock physics and geophysical seismic techniques.  These methods are additionally enhanced by incorporating new approaches including the use of seismic attributes and machine learning algorithms.  Initial results focused on gas hydrate accumulations in New Zealand will be presented.

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