The Large Synoptic Survey Telescope (LSST)

Abstract

Did a Comet Cause Noah's Flood?

Abstract

Dee Breger, Sr. Microscopist at Drexel University's Centralized Research Facilities and an award-winning analytical scanning electron microscopist, is a founding member of the Holocene Impact Working Group (HIWG), the core team of six international researchers and their colleagues who are bringing to light new evidence for numerous major comet impacts, particularly since - and including - the ending of the last ice age.

Cited in the New York Times as "a band of misfits", the group's data suggest that many more comets have struck the Earth during the Holocene period, particularly into its seas and oceans, than are currently accepted by traditionalists in geology and astronomy. An impact into the Indian Ocean estimated at 2800 BCE, is proposed as the source of worldwide deluge and flooding legends, including those of Gilgamesh and Noah. Multiple smaller impacts in 536 CE could well have caused a severe global cooling due to the recorded 18 months without sun, with subsequent famines, wars, massive population migrations, the first emergence of the plague, and attendant political upheavals.

Breger will present the geophysical methods used to support the team's paradigm by her colleague Columbia University geophysicist Dallas Abbott, including the results of an expedition to sample megatsunami deposits in Madagascar. This support will be complemented by microscopic evidence for these cataclysmic events, which will also link them to accepted impacts such as the Tunguska (Siberia) event in 1908 and the impact that created Chesapeake Bay 35 million years ago. Combined with the work of tsunami, tree-ring, and geomythology experts in the group, Abbott's and Breger's data suggest a potential paradigm shift in how we view our planet's recent geological past, as well as provide explanations for enduring mysteries in climate research, mass extinctions, and archaeology.

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Suggested reading:

Bryant, E., Walsh, G. and Abbott, D. Cosmogenic mega-tsunami in the Australia region: are they supported by Aboriginal and Maori legends? Myth and Geology, L. Piccardi and W.B. Masse, Eds., Geol.Soc. Special Publication 273, London, 2007

Firestone, R., West, A. and Warwick-Smith, S., The Cycle of Cosmic Catastrophes: Flood, Fire, and Famine in the History of Civilization, Bear & Company (2006)

Victor Clube and Bill Napier, The Cosmic Serpent, Universe Pub (1982)

Breger, D., Journeys in Microspace: The Art of the Scanning Electron Microscope, Columbia University Press, NY, NY (1995)

Is Quantum Mechanics Chaotic?

Abstract

Chaos is a ubiquitous phenomenon in the classical world. It appears in dripping faucets, human heartbeats, electrical circuits, lasers, etc. However, there is now great interest in the wave and quantum properties of systems that show chaos in the classical (short wavelength) limit. These wave chaotic systems appear in many contexts: nuclear physics, acoustics, two-dimensional quantum dots, and electromagnetic enclosures, for example. It has been hypothesized that Random Matrix Theory (RMT) predicts the universal fluctuating properties of quantum/wave systems that show chaos in the classical/ray limit. Microwave cavities, with classically chaotic ray dynamics, have proven to be a fruitful test-bed for the experimental tests of universal fluctuations in wave-chaotic systems. We have developed a microwave cavity experiment that mimics solutions to the Schrodinger equation for a two-dimensional infinite square well potential. I will present experimental tests of RMT predictions of both closed and open quantum systems, as simulated by our microwave cavity analog experiment. As a specific example we have examined quantum interference effects in the transport properties of nanoscopic systems, as simulated in the microwave cavity. The cavity is free of complications arising from finite temperatures (thermal smearing, inelastic scattering), and the excitation of two-level systems that can cause the electrons to decohere and drop out of the quantum-coherent transport process. The Landauer-Buttiker formalism is applied to obtain the conductance of a corresponding mesoscopic quantum-dot device, and we find good agreement for the probability density functions of the experimentally derived surrogate conductance, as well as its mean and variance, with the theoretical predictions based on RMT.

Ultrafast Optical Studies of Condensed Matter Systems

Abstract

'Ultrafast' optical studies means an optical pulse width as narrow as 10- 20 fs and a time 'window' of 20 fs- 10 ns. This time window complements the time windows of muon spin rotation (down to ~ 100 ps) and neutron scattering (down to sub-femtosecond with Neutron Compton Scattering methods), with the limitation that due to the negligible photon linear momentum the measurements involve only wavevector |k| ~ 0 excitations. In this talk, I illustrate some of the science found by using ultrafast optical probes, including semiconductors [1], cuprates [2-5], heavy fermions [6], colossal magnetoresistance materials [7-9] other unconventional superconductors, in particular Sr2RuO4 ,[10,11] collective excitations [12- 14] and ultrafast demagnetization [15,16].

Based on the data from my collaborations and independent scientists, there are five scientific topics I will briefly discuss:

* Electron- electron thermalization [2-4, 6, 10, 11]: The main point to recognize is the difference between the electron- electron interactions in the Fermi liquid regime of correlated electron systems [6, 10, 11] and the not- Fermi liquid regime of correlated electron systems [2-4, 10, 11];

* Relaxation (dissipation) [1-11]: Here the main point is to compare behaviors of semiconductors, which are independent electron systems having real electronic bandgaps, heavy fermion and cuprates, which exhibit bottlenecks in the relaxation behavior, and the Fermi liquid normal state of an unconventional superconductor, Sr2RuO4, which exhibit relaxation times that scale with the electrical conductivity;

* Coherent longitudinal acoustic phonons in cuprates,[5] in which a simple model [12] allows us to account quantitatively for the oscillation period, dispersion, phase and amplitude decay with time;

* Collective excitations observed in correlated electron systems, including phonon- polariton oscillations in colossal magnetoresistance materials,[7] charge density waves in chalcogenides,[13] and surface plasmons in silver nanoparticles;[14]

* Ultrafast demagnetization in both ferromagnetic [15] and antiferromagnetic [16] materials.

1. F. Rossi and T. Kuhn, Rev. Mod. Phys. 74 (2002) 895.

2. M.L. Schneider et al, Euro. Phys. J. B 36 (2003) 327.

3. N. Gedik et al, Science 300 (2003) 1410.

4. V.V. Kabanov et al, Phys. Rev. Lett. 95 (2005) 147002.

5. I. Bozovic et al, Phys. Rev. B 69 (2004) 132503.

6. J. Demsar et al, Phys. Rev. Lett. 91 (2003) 027401.

7. R.D. Averitt et al, Phys. Rev. Lett. 87 (2001) 017401.

8. Y. Ren et al, Phys. Rev. B 64 (2001) 144401.

9. E. Dagotto et al, Phys. Rep. 344 (2001) 1.

10. P. Guptasarma et al, J. Phys. Chem. Sol. 67 (2006) 525.

11. M. Onellion et al, in preparation.

12. C. Thomsen et al, Phys. Rev. B 34 (1986) 4129.

13. J. Demsar et al, Phys. Rev. Lett. 83 (1999) 800; J. Demsar et al, Phys. Rev. B 66 (2002) 041101.

14. J. Lehmann et al, Phys. Rev. Lett. 85 (2000) 2921.

15. E. Beaurepaire et al, Phys. Rev. Lett. 76 (1996) 4250; M. Vomir et al, J. Appl. Phys. 99 (2006) 08A501.

16. T. Ogasawara et al, Phys. Rev. Lett. 94 (2005) 087202 and references therein.

Mixed-mode oscillations: from dopamine neurons to solid fuel combustion

Abstract:

Mixed-mode oscillations form complex oscillatory patterns, which

combine large amplitude relaxation oscillations and small nearly

harmonic oscillations. Despite subtle dynamical structures underlying

these oscillations, they have been observed in numerous experiments

and numerical simulations in physical and life sciences. Often

differential equation models generating mixed-mode oscillations

feature rich bifurcation structures and exhibit a range of interesting

dynamical phenomena including chaos. In this talk, I will describe my

work aimed at understanding multimodal oscillations in two different

models from the natural sciences.

Convergence and Stability of the Inverse Scattering Series for Diffuse Waves

Abstract

The application of the inverse Born series for the inverse scattering problem for diffuse light has been very promising, (Markel et. al J. Opt. Soc. Am. A, 2003) . The technique gives nonlinear corrections to the inverse Born approximation which do not require any further operator inversion, and formally the entire series yields the absorption coefficient. Here we examine the radius convergence of this functional series and the stability of the limit with respect to perturbations in the measured data. We find in particular that its stability is determined by the stability of the linearized inverse problem. We also examine the error due to regularization. The approach extends to scalar waves in the near-field.

A Drexel Graduate’s Journey through Physics Professorship and Textbook Authoring

Abstract

I graduated from Drexel in 1969 with a B.S. in Physics. In graduate school, I had the goal of devoting my future efforts to improving physics education rather than performing traditional physics research. At that time, there were no Physics Education Research groups, as there are today, so my academic job opportunities were necessarily limited to universities where teaching was emphasized over research. As a physics professor, my efforts led to $2.5 million in educational research grants and co-authorship on two major physics textbooks. In this talk, I will review my education and professional career, focusing on details about my experiences in authoring textbooks and exploring new teaching techniques that have been developed from Physics Education Research. I will also discuss some of the unique teaching techniques that I have developed, including the use of antiques as demonstration apparatus in the classroom.

The Sun and Space Weather

Abstract

Space weather is the name given to a variety of terrestrial phenomena produced when highly energetic particles, launched from the Sun, impact on the Earth's atmosphere. Our society is becoming increasing reliant on technologies which are susceptible to the effects of space weather. For example, when energetic particles impact the Earth's ionosphere, they cause it to expand, which increases drag on space craft in unpredictable ways. Energetic particles can also damage electronics on space craft, and space weather induced magnetic storms can interfere with satellite communications and cause power grid blackouts. In addition, X-rays and other high energy particles can harm astronauts. These high energy particles primarily are produced by solar flares and coronal mass ejections (CME's) both of which are caused by the release of magnetic energy in coronal active regions in the Sun's atmosphere. One of the main goals of solar physics has become understanding the origin and evolution of flares and CME's, so that we will be able to forecast space weather storms. This will require a global model of the evolution of active regions. Recently, researchers here at Drexel University received a large grant to produce such a model. Our model will incorporate magnetic field data from nearly all available solar observatories. These data will be used as boundary conditions to our 3D MHD code with which we will model the evolution of actual solar active regions. In this talk I will provide an overview (meaning not too technical!) of the current research on solar flares and CME's and describe the details of our active region model.

Oak Ridge and Neutrinos - eHarmony forms another perfect couple

Abstract

To paraphrase D. Rumsfeld, there are things we know we know, there are known unknowns, and there are unknown unknowns. The rich field of particle physics comes from the drive to explore the second and third categories, by measuring properties of known particles and in the search for new physics. The recent decades have seen great advances in the characterization of particles. The elusive neutrino still holds many mysteries for physicists to uncover.

My research focuses on the study of neutrino oscillations and CP violation in the neutrino sector, using the MiniBooNE detector. MiniBooNE has released results using a neutrino data set, and will collect anti-neutrino data through September, 2009. MiniBooNE uses neutrinos coming from mesons decaying in flight. This provides a focused high-energy neutrino beam, but large systematic uncertainties due to flux and interaction cross sections.

Further exploration of neutrino properties may be best accomplished at a facility which provides neutrinos coming from mesons decaying at rest; this beam type greatly reduces the systematic uncertainties that plague MiniBooNE. The Spallation Neutron Source, the world's most intense pulsed neutron source, offers such a beam. An abundance of measurements may be performed at a neutrino detector located at the SNS : oscillation searches, CP violation studies, cross section measurements relevant for astrophysical calculations, and a search for sterile neutrinos.

I will present an introduction to neutrinos and MiniBooNE, and describe the measurements which may be performed at the SNS.

Your Textbook is wrong about the Milky Way

Abstract

Stellar photometry from the Sloan Digital Sky Survey has revealed previously unforseen substructure in the stellar spheroid of the Milky Way: enormous tidal streams from known and from unidentified progenitor, lumps of unknown origin, hints of triaxiality, along with new dwarf galaxies and star clusters. I will outline the new techniques that are being used to identify density substructure statistically, without precise information about the spacial position of each star. We are just beginning to tap the potential of velocity information for large numbers of Galactic stars, which will eventually allow us to piece together the merger history of our Galaxy, and may allow us to trace the dark matter potential. We currently get our velocity information from Sloan Extension for Galactic Understanding and Exploration (SEGUE) data, and we are exploring the possibility of future collaborations with the Chinese LAMOST project.

Has dark matter already been discovered?

Abstract

The WMAP experiment discovered an excess in microwave radiation, distributed radially around the center of our Galaxy. This radiation is unlikely to come from usual astrophysical mechanisms, but an explanation in terms of dark matter self-annihilation works surprisingly well. In this talk I will describe how we can further test this possibility by observing high energy gamma rays coming from the Galactic center with the satellite detector GLAST, about to be launched this spring.

Dynamic Disorder in Enzymatic Systems

Abstract

Single-molecule studies of enzymatic reactions reveal fluctuations in the reaction rate, which cannot be explained by classic Markovian dynamics. This dynamic disorder is attributed to slow transitions in enzyme conformations that take place over timescales longer than reaction cycle times.In this work we discuss a model for reaction kinetics in fluctuating, single enzyme systems and apply it to beta-galactosidase. Specifically, we focus on the implications of single-molecule fluctuations for reaction rates in systems such as cells or biosensors that contain a moderate number of molecular copies.

Dynamics of Intramolecular Contact Formation in Islet Amyloid Polypeptide

Abstract

Measuring the dynamical properties of unfolded chains in solution, and in particular of amyloid forming peptides, is of key importance to understand the first elementary steps in folding, misfolding and aggregation. Protein misfolding and aggregation is at the basis of a vast class of diseases (including Alzheimer's and type II Diabetes) called amyloid diseases, where aggregates of specific structure, called amyloid fibrils, are formed. In type II Diabetes a peptide called human islet amyloid polypeptide (hIAPP) forms amyloid fibrils inside the beta-cells of the pancreas (where insulin is produced) contributing to beta-cell death and ...

The Perfect Qantum State Transfer with Superconducting Phase Qubits

Abstract

In 1980, Tony Leggett argued that the validity of quantum mechanics at the macroscopic level can and should be put to experimental test. Verification would finally force us to accept the radical viewpoint that the superposition principle holds on all scales of size and complexity; a breakdown of quantum theory would be even more radical. He proposed that superconducting devices were one of the most promising places to look. Today this question has been merged with the ambitious goal of building a quantum computer using superconducting circuits as quantum bits (qubits). In this talk I will discuss these recent advances and a theoretical pr...

Star Formation in High Redshift Galaxies

Abstract

The Hubble Space Telescope for optical and near-infrared light and the Spitzer Space Telescope for the infrared have opened up a view of star formation in young galaxies that has never been possible before. Because the most distant galaxies are viewed as they were when light left them long ago, we can see the various steps of galaxy formation throughout time. Our work in the last three years has concentrated on the nature of star formation in these galaxies, many of which are quite peculiar by the standards of our own neighborhood. The dominant peculiarity is the presence of enormous young clusters and star complexes in the disk systems. These complexes are 1000 times more massive...

The Giant Magneto-Resistive (GMR) Effect

Abstract

The 2007 Nobel Prize for Physics was awarded to Albert Fert of France and Peter Grunberg of Germany who independently discovered the Giant Magneto-Resistive (GMR) effect. The GMR effect is the magnetically induced change in the electrical resistance of a sample. The GMR effect is solely responsible for the development of highly dense computer storage devices. I will present a brief description of the GMR effect and discuss how it is an outstanding example illustrating the beauty and utility of science coming together.