Colloquia Archive

2012 - 2013 Academic Year Colloquium Series

April 26, 2013

"Mega-Optics"

Dr. Nader Engheta, H. Nedwill Ramsey Professor, University of Pennsylvania

Metamaterials and plasmonic optics have become exciting platforms for controlling and harnessing light and electrons in unprecedented ways. As these fields reach a certain level of development, new directions and novel vistas are appearing in the horizon.  Balancing the simplicity with the complexity in metamaterials becomes one of the key issues, and consequently modularization, functionalization, and parameterization of metamaterials may be exploited for new functionalities and possibilities in such interesting platforms that may include nonlinearity, anisotropy, chirality, non-reciprocity, and non-locality.   The new paradigm of “meta-optics” offers new and transformative grounds for innovation in the field of nanooptics, nanoelectronics, and electrodynamics.  I will give an overview of some of our most recent results in this area and will forecast some future possibilities.

April 19, 2013

"Overview of the Theory of Materials: Adventures in Alphabet Soup"

 Dr. Joseph Schick, Department of Physics, Villanova University

Materials have been long a focus of intense research in physics, chemistry, and engineering for practical applications. In a general sense, the description of the behavior of matter can be completely obtained through application of quantum theory. In practice, however, the problem becomes quickly intractable. In this presentation I provide an overview of basic concepts of the physics of solid materials and some theoretical tools currently used to model these materials, such as density functional theory (DFT). I will illustrate the effectiveness of theoretical approximations used through comparison of some theoretically calculated and experimentally measured properties for selected materials.

February 1, 2013

"Adventures in Frustrated Magnetism"

Dr. Jeremy Carlo, Department of Physics, Villanova University

In recent years the topic of frustrated magnetism has attracted significant interest.   Magnetic frustration occurs when the geometric arrangement of ions prevents magnetic order, such as ferromagnetism or antiferromagnetism, from arising.   Frustrated materials are known for a wide variety of ground states and the accessibility of subtle physics normally masked in ordinary magnetic materials.   I will give an introduction to the topic of magnetic frustration, and an overview of some of the work my group has done and will be doing in the field.    I will focus on materials exhibiting face-centered structural symmetry, including the double perovskites, which allow for systematic studies of the effects of lattice distortion, moment size, doping and spin-orbit coupling.

 

November 30, 2012

Time-resolved imaging of spin dynamics in magnetic nanostructures”

 Dr. Xuemei Cheng, Department of Physics, Bryn Mawr College

 

November 9, 2012

“On Hot Electron Transfer in Mesoscopic Semiconductor Wires and Its Remarkable Tuning”

Dr. Jonathan Spanier, Drexel University, Department of Materials Science & Engineering

 Nanowires provide fascinating opportunities to study the effects of finite size, of shape anisotropy, and of surface chemical environment on the phase stability in ferroic materials and on optical properties and electronic transport within semiconductors. Moreover the integrating of different functional materials within individual nanostructures permits investigation of physical and functional properties where interfaces and surfaces play pivotal roles.

 I shall first present on our recent work in the proximal probe-based analyses and model calculation results involving ferroelectric polarizations within individual oxide nanowires, and within perovskite nanoshells surrounding selected other materials, including magnetoelastic coupling.  In the second part of my talk I shall discuss our recent work involving the electronic and optoelectronic transport within core-shell radial semiconductor heterojunction nanowires, including ultrafast response and several modes of tuning hot electron transfer across co-axial interfaces.  I will discuss implications of these results for optoelectronic devices: dynamic manipulation of this transfer rate permits the introduction and control of a continuously adjustable phase delay over a wide range within a single nanometer-scale device element.

 October 26, 2012

“Abraham, Lorentz, Fermi & Gauss: Energy and Momentum in Classical Electrodynamics”

Dr. Robert Jantzen, Villanova University, Mathematics

 September 28, 2012

The Age of Precision Cosmology"

 Dr. David T. Chuss, Villanova Alumnus, NASA Goddard Space Flight Center

2011 - 2012 Academic Year Colloquium Series

March 26, 2012

“Innovative Routes to Designing Functional Oxides: Using Centric Octahedral Rotations to Induce Ferroelectric Polarizations "

Dr. James Rondinelli, Department of Materials Science & Engineering, Drexel University

  Research in ABO3 perovskite oxides ranges from fundamental scientific studies in superconductivity and magnetism to technologies for advanced low-power electronics, energy storage, and conversion. The breadth in functionalities observed in this versatile materials class originates, in part, from the ability to control the local and extended atomic structure of the corner-connected octahedral units. In this talk, I will describe emerging routes in multilayer superlattices enabled by epitaxial synthesis aimed at engineering the octahedral connectivity—rotational magnitudes and patterns—to realize functional materials by design. I will introduce the crystal–chemistry–functionality relationships in perovskite oxides within the context of ferroelectricity: the most familiar design strategy to achieve a spontaneous polarization involves the incorporation of second-order Jahn-Teller (SOJT) active cations. This mechanism, however, is limited to specific chemistries and the polar distortions that arise are largely decoupled from the octahedral rotations which control the electronic, magnetic and orbital properties. I will then describe the crystal-chemistry criteria which enable the rational design of new perovskite oxides displaying octahedral rotation-induced ferroelectricity – electric polarizations without SOJT cations – from centric BO6 building blocks. Using state-of-the-art electronic-structure computations combined with group theoretical methods, I detail the design of ferroelectric gallate and aluminate perovskites with sizeable polarizations. Finally, I argue this novel form of ferroelectricity is a promising avenue to couple ferroelectric polarizations with octahedral rotation-derived properties. By uniting switchable electric polarizations to the connectivity of the transition-metal oxygen octahedra, electric-field control over materials properties is possible.

March 12, 2012

"A Path to the Definitive Detection of Dark Matter"

 Dr. James Battat, Department of Physics, Bryn Mawr College

  The mysterious nature of dark matter has eluded explanation for decades, and remains a major puzzle in physics today.  Detectors that search for the direct interaction of dark matter with target nuclei must distinguish rare dark matter interactions from abundant backgrounds that can masquerade as signal.  Searches for dark matter have not yet fully exploited a unique astrophysical signature of dark matter:  the angular distribution on the sky.  The Earth's motion through the Galactic halo should produce a head-wind of dark matter, and a forward-backward asymmetry in the direction of dark matter-induced nuclear recoils.  No known background can mimic this signature.  I will discuss directional dark matter detection, and I will describe recent results from the Dark Matter Time Projection Chamber, a direction-sensitive dark matter detector.  We operate one detector underground, are commissioning an improved second-generation detector at MIT, and are funded to construct a large-scale detector to provide leading sensitivity to a class of dark matter particles.

February 20, 2012

"Terahertz Wireless Communications"

 Dr. John Federici, Department of Physics, New Jersey Institute of Technology

 The rapidly increasing demand for higher bandwidth and data rates in wireless communication systems over the past several decades is well-known. According to Edholm's law, the demand for point-to-point bandwidth in wireless short-range communications has doubled every 18 months over the last 25 years. It can be predicted that data rates of around 5-10 Gb/s will be required in 10 years. Some of the reported advantages of THz communications links compared to millimeter wave links are inherently higher utilizable bandwidth relative to the higher carrier frequency, less susceptibility to scintillation effects than infrared wireless links, and the ability to use THz links for secure communications. Over the past 12 years, several groups have considered the prospects of using THz waves as a means to transmit data and numerous papers covering various aspects of the topic - THz sources and detectors, modulation schemes, wireless communication measurements - have been reported. In this talk, a comprehensive review of wireless THz communications is presented.

February 13, 2012

“Mössbauer Studies of Monovalent Iron in Hydrogenase Models”

Dr. Codrina Popescu, Department of Chemistry & The Biochemistry/Molecular Biology Program, Ursinus College

The active site of the Fe-Fe hydrogenase (so-called, H-cluster) contains a dinuclear subcluster, which is known to catalyze hydrogen production.  Several studies of the enzyme have shown that the relevant catalytic states for this dinuclear cluster are Fe(I)Fe(I), Fe(II)Fe(I) and Fe(H)Fe.  The uncovering of spectroscopic evidence for Fe(I) organometallic complexes in an enzyme prompted several groups to pursue the synthesis of model complexes for two reasons.  First, low-spin Fe(I) complexes were very rare in the literature, thus the H-cluster presented a new frontier for inorganic chemistry and spectroscopy.  Second, hydrogenases produce hydrogen very efficiently, using an environmentally benign metal.  Thus the dinuclear subcluster is an inspiration in the creation of new small-molecule catalysts for cheaper H2-production.  We are studying a series of Fe(I)Fe(I) and Fe(II)Fe(I) complexes with Mössbauer spectroscopy in an effort to understand the so far unexplored electronic structure of low-spin Fe(I), and in particular the structure of mixed-valence states that could help elucidate the structure of the oxidized H-cluster.

January 30, 2012

Energy Transportation in Nanoengineered Systems

Calvin Hong Li, Ph.D., Department of Mechanical Engineering, Villanova University

Research and development of nanoengineered materials has been one of the most important and exciting forefront research topics in recent years, on a broad range of scientific and industrial applications of new materials and the bottom-up synthesis of novel nano-systems. This talk will emphasize recent progress made in Nanoengineered Materials that improve energy efficiency, biofuel combustion quality, and thermomagnetic energy conversion.  The talk will also cover advances in thermophysical properties and efficiency in thermal management systems, such as nano-millimeter hierarchical porous structures for two-phase change heat transfer enhancement, nanoenergetic additives for biofuel combustion quality improvement, and ferromagnetic nanoparticle thermomagnetic energy conversion. Some novel properties related to nanoscale phenomena will be presented and discussed, as well as fabrication methods.

Monday, November 14, 2011

Against the Wind: How Extremely Massive Stars Lose Weight

 Dr. Michael F. Corcoran, USRA CRESST Director, Universities Space Research Association, Goddard Space Flight Center

Extremely massive stars (50 solar masses and above) are exceedingly rare in the local Universe but are believed to compose the entire first generation of stars, which lived fast, died young and left behind the first generation of black holes and set the stage for the formation of lower mass stars suitable to support life.  For most of their lives, extremely massive stars give mass back to the ISM out of which they formed via strong radiatively-driven winds, though sporadic eruptions may play an important role too.  This mass loss plays an important role in the chemical and dynamical evolution of the local interstellar medium prior to the supernova explosion. I'll discuss how high energy thermal (and, in some cases, non-thermal) emission, along with modern simulations in 2 and 3 dimensions, can be used to help determine a physically realistic picture of mass loss in some well-studied systems.

 Monday, November 7, 2011

Lightweight Medium-Aperture Mirrors for Astronomy & Power Generation

 Dr. Bruce D. Holenstein, President & CEO, Gravic, Inc.

 We will present some current efforts at fabricating lightweight medium-aperture mirrors from non-traditional substrates which include pneumatically-formed Mylar, slumped meniscus glass, spun epoxy, and CNC machined foamed glass. We will discuss various optical quality metrics and efforts at residual wavefront aberration remediation. Also, we will discuss some fixed and portable mount designs and associated uses for 0.7-m to 1.5-m lightweight mirrors.

Monday, October 17, 2011

Dr. Andrew M. Rappe, Department of Chemistry, Department of Materials Science and Engineering, Pennergy:  the Penn Center for Energy Innovation, University of Pennsylvania

Ab initio design of materials and surfaces for Green Energy Applications

The present search for new ways to harness, store, convert, and use energy inspires modern research in many fields. First-principles electronic structure calculations offer a window into materials, revealing how favorable properties arise and offering opportunities to propose new materials with improved properties. In this talk, three examples of theoretical modeling guiding the development of surfaces and near-surface materials for energy applications will be described.

1. The simple creation of epitaxial nonstoichiometric surfaces through annealing will be presented, and their potential as novel catalysts discussed.

2. The use of ferroelectricity to control surface composition and structure will be highlighted, focusing on bare surface catalysis, oxide control of deposited metal morphology, and
oxide control of metal reactivity.

3. The use of aliovalent dopants to make ferroelectric oxides efficient single-phase photovoltaic materials will be presented. Through these examples, the interplay
between theoretical and experimental design of novel materials for energy applications with be emphasized.


Monday, September 26, 2011

Dr. Steven May, Department of Materials Science & Engineering, Drexel University

Oxide Interfaces: Emerging Routes to Enhanced Material Functionality

Scientific interest in ABO3 perovskite oxides remains intense due to the wide range of physical behavior present in these materials, such as high-TC superconductivity, electronic correlations, metal-insulator transitions, ferroelectricity and magnetism. Recent advances in thin film deposition techniques, such as molecular beam epitaxy, have made it possible to synthesize perovskite heterostructures and superlattices with unit cell precision. This talk will focus on how the formation of oxide heterostructures and interfaces can be used to realize novel electronic and magnetic properties. I will first describe how the electronic properties of oxide interfaces can give rise to novel magnetic properties. Next, I will discuss how interfacial structural coupling can be used to stabilize non-equilibrium bond angles and lengths, thereby altering a wide of functional properties.


2010 - 2011 Academic Year Colloquium Series

Thursday, April 14, 2011

Dr. Frans Pretorius, Department of Physics, Princeton University

When: 4:00 PM
Where: Mendel 101
Refreshments will be served at 3:30 PM

Black Holes: Probes of the Cosmos & Fundamental Physics
The class of spacetimes with event horizons contain some of the most fascinating solutions to the equations of general relativity. Over the past few years, numerical simulations of the field equations have begun to reveal some of the more dynamical, strong-field solutions not amenable to exact analytical or perturbative treatments.

In this talk, I will describe 3 such scenarios. First, the inspiral and merger of two black holes, which is thought to occur frequently in the universe. Such events are powerful emitters of gravitational waves, and a concerted world-wide effort is currently underway to observe the universe through gravitational waves.

Second, I will discuss the ultra-relativistic collision of two solitons. Arguments suggest that at sufficiently high velocities gravity dominates the interaction, causing a black hole to form regardless of the internal structure or nature of any non-gravitational interaction. These arguments underly claims that the Large Hadron Collider will produce black holes in speculative large extra dimension scenarios. Finally, I will show results elucidating the fate of a black string in 5 dimensions, subject to the Gregory-Laflamme instability. Rather remarkably, the event horizon exhibits dynamics akin to a low viscosity fluid stream suffering the Raleigh-Plateau instability, where the horizon starts to form spherical "beads" connected by ever thinner string segments that are themselves unstable, and the instability unfolds in a self-similar cascade. This process reveals arbitrarily large spacetime curvatures to an external observer, culminating in naked singularities. This is therefore a generic example of cosmic censorship violation in higher dimensional Einstein gravity.

Thursday, April 7, 2011

Dr. David Goldberg, Department of Physics, Drexel University

When: 4:00 PM
Where: Mendel 101
Refreshments will be served at 3:30 PM

"Where's the Matter with Clusters?"
Clusters of galaxies are the largest collapsed structures in the universe. Their mass maps reveal properties of the primordial density field, and their mass distribution as a function of time is a sensitive probe of Lambda-CDM cosmology.  However, it has been known for nearly a century that the luminous matter in clusters is not necessarily a good indicator of the mass.  In this talk, I will describe how to map rich clusters using gravitational lensing, what numerical simulations have led us to expect, and what the differences between observation and theory can tell us about the nature of the universe.
 

Thursday, February 24, 2011

Dr. V. Parameswaran Nair, Department of Physics, City College of the CUNY

When: 4:00 PM
Where: Mendel 101
Refreshments will be served at 3:30 PM

Feyman's Last Problem 30 years later: Liquid Helium and QCD
In 1954, Feynman gave a beautiful analysis of superfluid Helium using general properties of wave functions and of the space of particle configurations. In the 1970s, starting with the discovery of asymptotic freedom and the emergence of QCD, the question of quark confinement and the generation of a mass gap was recognized as an important question about the nonperturbative behavior of nonabelian gauge theories. Needless to say, this has proved to be a very difficult problem to analyze. Two spatial dimensions would provide the simplest case of  a nontrivial gauge theory which could exhibit confinement and mass gap. In 1981, Feynman tried to use a set of arguments similar to what he had developed for superfluidity to argue for the existence of a mass gap for these theories. Did he succeed? Did he fail? If so, to what extent? I shall give a brief recapitulation of Feynman's arguments for Helium and then present his arguments for YM(2+1), in a slightly modernized and more precise language, so that we may gain some perspective on how much progress has been made. The emphasis will be on concepts more than on detailed formulae.

Thursday, October 21, 2010

Dr. Marija Drndic, University of Pennsylvania

When: 3:30 PM
Where: Mendel 115
Refreshments will be served at 3:00 PM

Nanosculpting Solid-State Devices with Electrons and their Biophysics Applications
Manipulation of matter on the scale of atoms and molecules is an essential part of realizing the potential that nanotechnology has to offer. I will describe a method to nanosculpt matter by controllably exposing it to an intense and highly focused beam of electrons. Electron irradiation can be used to controllably displace or ablate regions of the material, such as thin metal films and graphene sheets, with nearly atomic resolution. I will discuss the impact of this work in biophysics, including DNA translocation studies through graphene nanopores and detection of small nucleic acids down to 10 base pairs with nanopores in ultrathin membranes.

Thursday, October 7, 2010

Gravitational Lensing in the Accelerating Universe

Dr. Bhuvnesh Jain

When: 3:30 PM
Where: Mendel 115
Refreshments will be served at 3:00 PM


Thursday, September 30, 2010

Dr. Joseph Schick, Department of Physics, Villanova University

When: 3:30 PM
Where: Mendel 115
Refreshments will be served at 3:00 PM

Theory of Gallium Diffusion In Gallium Arsenide and Its Effects
Gallium arsenide has been a material of continuing technological interest for many years. Despite the length of time it has been under investigation, both experimentally and theoretically, gaps in a full understanding of this material remain. One such area has to do with the movement of atoms in the material, which can be both useful, in controlling the properties of the material, and harmful, in disrupting the usefulness of devices once they are in operation. In this presentation I will provide a brief overview of the theoretical methods that can address this situation. I will present results of my application of density functional theory to a comprehensive study of all the native point defects in this material. Additionally I will discuss how these results shed light on one particular set of experiments that are aimed at determining how gallium atoms diffuse ....

2009 - 2010 Academic Year Colloquium Series

Thursday, March 19, 2009 - WMAP and Beyond
Dr. David Spergel, Princeton University
When: 4:00 PM
Where: Mendel 102
Refreshments will be served at 3:30 PM

The Wilkinson Microwave Anisotropy Probe (WMAP) has made an accurate full-sky measurement of the microwave background temperature and polarization fluctuations. These measurements probe both the physics of the very early universe and the basic proprties of the universe today. The WMAP measurements rigorously test our standard cosmological model and provide an accurate determination of basic cosmological parameters (the curvature of the universe, its matter density and composition). When combined with other astronomical measurements, the measurements constrain the properties of the dark energy and the mass of the neutrino. The observations also directly probe the physics of inflation: the current data imply that the primordial fluctuatiuons were primarily adiabatic and nearly scale invariant.

Many key cosmological questions remain unanswered: What happened during the first moments of the big bang? What is the dark energy? What were the properties of the first stars? I will discuss the role of on-going and future CMB observations in these key cosmological questions and describe how the combination of large-scale structure, supernova and CMB data can be used to address these questions.

Thursday, March 26,2009 - How quickly do planets form? Studying protoplanetary disk dispersal to constrain planet formation models
Dr. Eric Jensen, Swarthmore College
When: 4:00 PM
Where: Mendel 102
Refreshments will be served at 3:30 PM

More than 80% of Sun-like stars are surrounded at birth by orbiting disks of gas and dust like the one that formed the planets in our solar system. Most of these stars have lost any observable trace of this protoplanetary material by an age of three million years, much shorter than the commonly-cited theoretical timescale of tens of millions of years for the formation of giant planets. Have these stars already formed planets on a much shorter timescale? Or does rapid disk dispersal mean that planet formation is a rare event? I will discuss my studies of disk evolution around young stars, and how these data may give us insight into planet formation mechanisms. In particular, I will focus on DoAr 21, a low- mass star that has already lost its disk at an age of less than 1 Myr, but which is still illuminating circumstellar gas with intense UV radiation; and on lithium depletion in low-mass stars which may help us identify young stars of planet-forming age that are far from known star-forming regions.

2008 - 2009 Academic Year Colloquium Series

December 4, 2008 - Borexino
When: 3:30 PM
Where: Mendel 154
Refreshments at 3:00 PM

Cristiano Galbiati, Department of Physics, Princeton University

The Borexino Solar Neutrino Detector at Gran Sasso Labs (Italy) is a low energy solar neutrino detector operating since 2007 at Gran Sasso, with 300 tons of liquid scintillator serving as an active target. The extremely low background achieved in the target allowed the first real time observation of low energy solar neutrinos, below the natural radioactivity barrier. I will report on recent results from Borexino and their implications on neutrino physics and oscillations.

November 13, 2008 - Particle Physics Puzzles for the LHC
When: 3:30 PM
Where: Mendel 154
Refreshments at 3:00 PM

Evelyn Thomson, Department of Physics and Astronomy, University of Pennsylvania

I will explain the motivation for the Large Hadron Collider and discuss the status of the commissioning of both the LHC and the giant ATLAS particle detector. ATLAS will take digital pictures of the particles from LHC collisions. I'll explain the interpretation of this information and how it could lead to discovery of the missing piece of the standard model of particle physics, the Higgs boson, or to discovery of particles and dimensions beyond the standard model.

October 30, 2008 - The Rising of a Giant Collider
When: 3:30 PM
Where: Mendel 154
Refreshments served at 3:00 PM

Chris Tulley, Department of Physics, Princeton University

On Sept 10th of this year the Large Hadron Collider (LHC) succeeded to circulate proton beams in both directions around its 27 kilometer circumference. The ring operated with all magnets superconducting at 1.9K and in the following week, the radio-frequency acceleration system was commissioned. Shortly after, an incident occurred in the magnet/cryostat systems that disabled sector 34 of the ring, prompting an early shutdown of the LHC until late Spring of 2009. The successes and failure of 2008 startup will be described for both the accelerator and the Compact Muon Solenoid (CMS) experiment. There are many predictions for what new physics lies ahead at the 14 TeV energy scale. I will present the goals for the 2009 run and the approach being taken to search for unknown new physics.

October 23, 2008 - Revealing the mysteries of water by first-principles approach
When: 3:30 PM
Where: Mendel 154
Refreshments served at 3:00 PM.

Krzysztof Szalewicz, Department of Physics and Astronomy, University of Delaware

April 11, 2008 - A New Look at the Proton and Neutron
When: 4:30 PM (Follows Sigma Pi Sigma induction ceremony at 4:00 PM)
Where: Mendel 102
Refreshments will be served.

Gerald A. Miller, Department of Physics, University of Washington

Recent electron scattering measurements have revealed unexpected features of the proton and neutron wave functions. I discuss recent work revealing that the proton is unlikely to have a spherical shape. Furthermore, the charge density of the neutron is negative at its center.

2007 - 2008 Academic Year Colloquium Series

September 7, 2007 - Extrinsic and Intrinsic Magnetism of Carbon Nanotubes
Jay Kikkawa Department of Physics & Astronomy University of Pennsylvania
When:
2:30 PM
Where: Mendel 213
Refreshments at 2:15 (Mendel 354)

Carbon nanotubes are a unique class of macromolecules exhibiting aromaticity, one dimensionality, a high degree of symmetry, and a diversity of bandgaps.
Physical properties of carbon nanotubes depend on their detailed atomic structure, and two nanotubes with nearly identical diameters can display markedly different responses to external stimuli. Magnetic anisotropy is particularly interesting for aromatic molecules because diamagnetic anisotropy probes charge delocalization in ring-like conduction paths. In this talk I will explain how relatively straighforward magnetic alignment experiments on carbon nanotubes in suspension yield information about both extrinsic and intrinsic magnetic anisotropies. 

2006-2007 Academic Year

April 20, 2007 - Building Motion: Constructing Movements from Simple Spinal Circuits
Corey Hart, Department of Neurobiology and Anatomy
Drexel University, College of Medicine
When: 3:00 PM
Where: Mendel 213
Refreshments at 2:30

March 23, 2007 - The Protein Ferritin As An Environmentally Relevant Nanosystem
Daniel R. Strongin, Department of Chemistry
Temple University
When: 3:00 PM
Where: Mendel 213
Refreshments at 2:30

The mineralization of ferritin proteins is a simple, yet effective method for assembling nanosized catalytic precursors having precise, pre-determined structures and sizes ranging from 10 to 80 Å. Horse spleen ferritin and Listeria Innocua ferritin-like protein were used to assemble Fe(O)OH particles ranging from 40 to 80 Å and 10 to 40 Å in diameter, respectively. In some cases, the protein was deposited on a Si support, dried and exposed to ozone to remove the protein shell. Probe molecules were used to investigate the surface reactivity of the nanoparticles in ferritin and without the protein cage as a function of size. First, the photoexcitation of ferritin results in the rapid reduction of toxic Cr6+ to immobile Cr3+ species. Second, results will be presented that investigate the reactions of sulfur dioxide (with molecular oxygen) on different sizes of iron oxyhrydoxide (ferrihydrite) nanoparticles. The surface reactions that led to the production of adsorbed sulfur oxyanions were found to be sensitive to the size and structure of the nanoparticle substrate.

March 16, 2007 - A Brief Survey of Computer-Aided Auscultation of the Heart: From Anatomy to Applications
Ray Watrous, Chief Technology Officer & Founder
Zargis Medical Corp.
When: 3:00 PM
Where: Mendel 213
Refreshments at 2:30

Understanding of the origin and physiological significance of heart sounds has progressed tremendously since the invention of the stethoscope by Rene Laennec in 1816. This brief survey reviews the development of computer-aided auscultation of the heart, and traces the relationship between cardiac anatomy and physiology and the acoustic signals that are foundational to cardiac auscultation. The survey includes a review of human perception of heart sounds and its limitations, and notes the contributions of phonocardiogaphy to clinical medicine and the development of heart sound analysis systems. Examples and results of advanced signal processing methods (wavelet decomposition, neural network classifiers, Hidden Markov models) that have been applied to the analysis of heart sounds and murmurs are summarized. The talk concludes with an overview of clinical applications of computer-assisted diagnostic decision support and screening systems, illustrated by two clinical studies: one discriminating innocent versus pathological murmurs and the other identifying cases of obstructive hypertrophic cardiomyopathy, a significant cause of sudden cardiac death in young athletes.

December 1, 2006 - Weighing Neutron Stars
David Nice, Department of Physics
Bryn Mawr College
When: 3:00 PM
Where: Mendel 213
Refreshments at 2:30

Millisecond radio pulsars are among the most extreme objects in the Galaxy — these neutron stars pack more than a solar mass of matter within radii of only a few kilometers, while rotating hundreds of times a second. I will describe observations of binary pulsar systems made with the Arecibo radio telescope. The main focus of the talk will be the measurement of relativistic phenomena in the orbital motion of pulsars — including detection of the effects of emission of gravitational radiation by tight binary systems — and the use of these relativistic observations to measure their masses.

2005 - 2006 Academic Year

March 31, 2006 - Physical Cosmology from Einstein to Dark Energy
David T. Chuss, 1995, Goddard Space Flight Center, NASA
When: 4:00 PM
Where: Mendel 102 (Gallen Lecture Hall)
Refreshments at 3:00
Sigma Pi Sigma Induction Ceremony at 3:30

March 17, 2006 - Strings, Black Holes, and Gauge Theories
Steven S. Gubser Department of Physics
Princeton University
When: 3:00 PM
Where: Mendel 213
Refreshments at 2:30

February 10, 2006 - The Role of Medical Physics in the Treatment of Cancer
Peter J. Debus, Staff Medical Physicist
The Cancer Institute
When: 3:00 PM
Where: Mendel 213
Refreshments at 2:30

2003 - 2004 Academic Year

April 30, 2004 - Hybrid II-VI Semiconductors: A Unique Class of Nanostructures with Tunable Properties
Jing Li, Chemistry & Materials Science
Rutgers University
When: 12:30 PM
Where: Mendel 115

April 16, 2004 - Dark Matter and the DRIFT Experiment

C. J. Martoff, Professor of Physics
Temple University
When: 12:30 PM
Where: Mendel 341
Refreshments in 362

March 12, 2004 - GE Global Research: Overview and Photonics Technology

James Loman, GE Corporation
When: 12:30 PM
Where: Mendel 341
Refreshments in 362

November 21, 2003 - The Role of Physics in Modern Medicine: Development of Minimally-Invasive Diagnostics & Therapies
Apostolos Doukas, Wellman Laboratories of Photomedicine
Harvard Medical School
When: 12:30 PM
Where: Mendel 115

November 7, 2003 - Metal Clusters: (1) The Onset of Metallicity (2) The Search for Cluster-Assembled Materials
Kit Bowen, Chemistry & Applied Physics Laboratory
Johns Hopkins University
When: 12:30 PM
Where: Mendel 115

October 31, 2003 - Supercritical CO2-Based “Dry” Chemical Mechanical Planarization Processes for Microelectronic Device Fabrication
Carol Bessel, Department of Chemistry
Villanova University
When: 12:30 PM
Where: Mendel 115

October 3, 2003 - Controlling Resonant Interactions in a Frozen Gas of Highly-Excited Atoms
Michael Noel, Department of Physics
Bryn Mawr College
When: 12:30 PM
Where: Mendel 115

2002 - 2003 Academic Year

March 28, 2003 - Quasicrystal Surfaces: From Fibonacci to Frying Pans
Renee D. Diehl, Dept. of Physics
Pennsylvania State Univ.
When: 12:45 PM
Where: Gallen Lecture Hall (Mendel 102)

March 14, 2003 - Where the Fundamental Scales of Physics Come From
Stephen Barr, Dept. of Physics & Astronomy
Univ. of Delaware
When: 12:45 PM
Where: Gallen Lecture Hall (Mendel 102)

February 28, 2003 - Title to be announced
A. Doukas
When: 12:45 PM
Where: Gallen Lecture Hall (Mendel 102)

February 21, 2003 - Title to be announced
William P. Knopf, Applied Physics Laboratory
Johns Hopkins Univ.
When: 12:45 PM
Where: Gallen Lecture Hall (Mendel 102)

February 7, 2003 - High Performance Rigid-Rod Polymers as used in Composite Materials: A Quantum Chemistry Point of View
Carl Krauthauser, Univ. of Delaware
When: 12:45 PM
Where: Gallen Lecture Hall (Mendel 102)

January 17, 2003  - Effective Interactions are Effective Interactions
Barry R. Holstein, Deptartment of Physics
University of Massachusetts at Amherst
When: 12:45 PM
Where: Gallen Lecture Hall (Mendel 102)

November 1, 2002 - Of Frogs and Force Fields: Motor Primitives and the Basis of Movement
Corey B. Hart, Department of Neurobiology
Drexel University, College of Medicine
When: 12:45 PM
Where: Gallen Lecture Hall (Mendel 102)

September 20, 2002 - Magnetic Fields in the Cold Dust at the Galactic Center
David T. Chuss, Northwestern Univ.
When: 12:45 PM
Where: Gallen Lecture Hall (Mendel 102)

2001-2002 Academic Year

April 12, 2002 - Polymer Models of Proteins and Predictions of Stability and Function
Huan-Xiang Zhou, Department of Physics and Astronomy
Drexel University
When: 12:45PM
Where: Room 362, Mendel

February 15, 2002 - The Role of Neutrinos in Astrophysics and Cosmology
David Seckel, Department of Physics and Astronomy
University of Delaware
When: 12:45 PM
Where: Room 362, Mendel

January 25, 2002 - Analysis of the origins of the 1,4-Dioxane Anomaly, using steady state and time-resolved fluorescence spectroscopy
Mazdak Heidary-Khajehpour, Department of Biochemistry and Biophysics
University of Pennsylvania
When: 12:45 PM
Where: Room 362, Mendel

September 21, 2001 - Adventures in Biophysics: Applications of Image Analysis, Computer Simulations and Laser Tweezers in Immunology
Suzanne Amadore Kane, Department of Physics and Astronomy
Haverford College
When: 12:30 PM
Where: Room 362, Mendel

2000-2001 Academic Year

The Fractal EEG: Fractal Dimension and the Detection of and Prediction of Epileptic Seisures
Corey B. Hart (1995), Department of Neuroscience and Anatomy
The Pennsylvania State College of Medicine

Research at the Jefferson Lab: Free Electron Laser User Facility
Michelle Shinn, Thomas Jefferson National Accelerator Facility
(Sigma Pb Sigma Induction Lecture)

HREELS and SPM Applied to Polymer Surfaces and Interfaces
N. John Dinardo, Department of Physics
Drexel University

High Precision tests and the Next Energy Frontier in Experimental Particle Physics
Joseph I. Kroll, Department of Physics & Astronomy
University of Pennsylvania

Submillimeter Polarimetry of the Galactic Center from Antarctica
David T. Chuss (1995)
Northwestern University
(Physics Club presentation)