September 29-October 5, 2003 THE BOSTON AREA PHYSICS CALENDAR The Boston Area Physics Calendar is published weekly during the academic year by the Department of Physics at Boston University. You may send your announcement by e-mail (bapc-events@cosmos.phy.tufts.edu ) or FAX (617-353-9393). We cannot accept announcements by telephone. Entries should reach us no later than 11:00 a.m. the Monday of the week proceeding the week of the event. ENTRIES RECEIVED AFTER THE DEADLINE WILL NOT BE PUBLISHED. Monday, September 29, 2003 Monday, September 29, 2003, 11AM Massachusetts Institute of Technology Plasma Science and Fusion Center Seminar Series Building NW17, Room 218 "Wendelstein - achievements of W7-AS and goals of W7-X" Thomas Klinger Max Planck Institute Refreshments served at 10:45PM Monday, September 29, 2003 @4:15p.m. Harvard University Department of Physics Colloquium Jefferson 250 "On the Trail of the Quark Gluon Plasma at RHIC" Barbara Jacak SUNY tea will be served in Jefferson 450 at 3:30 pm Monday, September 29, 2003 Barus and Holley 168, 4:30 p.m.* Professor Sean Ling Brown University Physics Department Title: "Towards Nanopore DNA Sequencing: Developing Nanotechnology for Molecular Biophysics (My Sabbatical Report)" Host: Professor David Cutts *Refreshments served at 4:00 p.m. Tuesday, September 30, 2003 Tuesday, September 30, 2003, 2:30PM Massachusetts Institute of Technology Joint Tufts/CfA/MIT Cosmology Seminar Kolker Room 26-414 ``Back-Reaction of Cosmological Perturbations on a Local Measure of the Expansion Rate" Ghazal Geshnizjani Brown University Refreshments will be served at 2:00PM Tuesday, September 30, 2003, 4:00PM Note new time Massachusetts Institute of Technology Nuclear Theory Seminar Center for Theoretical Physics, Building 6, Third Floor seminar room ``A new window on Strange Quark Matter as the ground state of matter (and Strange Stars)" Vikram Soni New Delhi Physics Laboratory Refreshments will be served Tuesday, September 30, 2003, 4:00pm Brandeis University Martin Weiner Lecture Series, Physics Colloquium Physics Building, Abelson 131 "Stochastic decision-making in the brain: time integration and (not so fatal) attraction" Professor X-J. Wang Brandeis University Refreshments in Room 333 at 3:30pm Tuesday, September 30, 2003, 4:00PM Note new time Massachusetts Institute of Technology Nuclear Theory Seminar Center for Theoretical Physics, Building 6, Third Floor seminar room ``A new window on Strange Quark Matter as the ground state of matter (and Strange Stars)" Vikram Soni New Delhi Physics Laboratory Refreshments will be served Tuesday September 30, 4:00PM MIT Astrophysics Colloquia MIT Center for Space Research, 70 Vassar St, Cambridge, MA Prof. Scott Hughes Massachusetts Institute of Technology (title to be announced) Refreshments are served at 3:45 PM. Sponsored by the Astrophysics Division of the MIT Department of Physics and the MIT Center for Space Research Wednesday, October 1, 2003 Wednesday, 1 October 2003 Brown University Theoretical Seminar Physics Department, B&H 555 2:30PM ``Matrix Models from Unstable D-branes" Dr. John McGreevy (Princeton U) Tue, Sep 30, 12:30pm Michael Efroimsky (US Naval Observatory) "Implicit Gauge Invariance in the N-body Problem of Celestial Mechanics: Practical Applications" The seminar will be held in Pratt Conference Room (G04) at CfA, 60 Garden St. Following is the abstract of the talk. ------------------------------------------------------------ We revisit the Lagrange and Delaunay systems of equations of celestial mechanics, and point out a previously neglected aspect of these equations: in both cases the orbit resides on a certain 9(N-1)-dimensional submanifold of the 12(N-1)-dimensional space spanned by the orbital elements and their time derivatives. We demonstrate that there exists a vast freedom in choosing this submanifold. This freedom of choice (=freedom of gauge fixing) reveals a symmetry hiding behind Lagrange's and Delaunay's systems, which is, mathematically, analogous to the gauge invariance in electrodynamics. Historically, Lagrange removed this freedom by imposing, "by hand", a convenient constraint. This was the condition of the instantaneous ellipse (or hyperbola) being always tangential to the physical velocity. It turns out that the Lagrange constraint is also implicitly instilled into the Hamilton-Jacobi treatment of the N-body problem. Imposure of any supplementary condition different from the Lagrange constraint (but compatible with the equations of motion) is legitimate and will not alter the physical trajectory or velocity (though will much alter the mathematical form of the planetary equations). Existence of this internal freedom has consequences for the stability of numerical integrators. Another important aspect of this symmetry is that any gauge different from that of Lagrange makes the Delaunay system non-canonical. In a more general setting, when the disturbance depends not only upon positions but also upon velocities, there exists a "generalised Lagrange gauge" wherein the Delaunay system is symplectic. This special gauge renders orbital elements that are osculating in the phase space. It coincides with the regular Lagrange gauge when the perturbation is velocity-independent. We provide a practical example illustrating how the gauge formalism considerably simplifies the calculation of satellite motion about an oblate precessing planet. Wednesday, October 1, 2003, 2:00PM Massachusetts Institute of Technology String Theory Seminar Center for Theoretical Physics, Building 6, Third Floor seminar room ``A New Hat for the c=1 Matrix Model" Igor Klebanov Princeton Refreshments will be served Wednesday, October 1st, 2003, 4:00 p.m. CANCELLED Joint Theory Seminar Harvard University Jefferson 256 Cardassian Expansion: Dark Energy from Modified Friedmann Equations Prof. Katherine Freese, University of Michigan Thursday, October 2, 2003 12pm, Thursday, October 2, 2003 Harvard University The Condensed Matter Theory Seminar Department of Physics Lyman 425 "Momentum resolved tunnel spectroscopy: A tool to investigate interaction physics at quantum Hall edges" Dr. Matthew Grayson Walter Schottky Institut Technische Universitaet Muenchen, Germany Thursday, October 2, 2003, 4:15 p.m. Harvard University Duality Seminar Jefferson 453 "Matrix (string) theory of pp-waves " Jeremy Michelson University of Kentucky Refreshments will be offered in Jefferson 453, at 3:45 Thursday, October 2, 2003, 4:00 p.m. Harvard-Smithsonian Center for Astrophysics Phillips Auditorium 60 Garden Street, Cambridge " Extreme X-ray/Optical sources (EXOs): Probes of the High Redshift Universe" Anton Koekemoer Space Telescope Science Institue * tea and cookies at 3:30 p.m. * October 2, 2003 4:15pm Massachusetts Institute of Technology Building 10 - Room 250 Refreshments in Building 4 - 339 at 3:45 "Scientists and K-12 Education: Can We Make a Difference?" Diandra Leslie-Pelecky, University of Nebraska Friday, October 3, 2003 Friday, October 3, 2003, 4:00 PM Harvard University Condensed Matter and Applied Physics Colloquium Division of Engineering and Applied Sciences Pierce Hall, Room 209 “Nanosilicon a la carte” Dr. Ulrich M. Goesele Mikrostrukturphysik Halle, Germany Refreshments will be served in Brooks Room following the seminar Friday, October 3, 2pm Harvard University Eaton-Peabody Lab Seminars in Auditory Physiology MEEI, ENT conference room, 4th floor Spontaneous otoacoustic emissions: Evidence for cellular Hopf oscillators in the organ of Corti? Christopher A. Shera Harvard Medical School BU Condensed Matter Seminar Friday, Oct. 3, 11:00 am Room SCI 352 Metcalf Science Center 590 Commonwealth Ave., Boston Dr. Matthew Grayson Walter Schottky Institut Technische Universitaet Muenchen Germany "Corner quantum wells: Quantum Hall physics in a two-dimensional electron system bent by 90 degrees" Abstract: We demonstrate a new type of quantum confinement structure consisting of a high-mobility GaAs/AlGaAs heterostructure overgrown on top of a precleaved corner substrate. The resulting corner-junction quantum-well heterostructure (CQW) effectively bends a two-dimensional electron system (2DES) at an atomically sharp 90 degree angle. The 2DES exhibits the fractional quantum Hall effect on both facets, attesting to its high quality and enabling a set of new experiments on QHE edge systems to be realized. In tilted fields, we can measure equilibration between both co- and counterpropagating edge channels of arbitrary filling factor. With counterpropagating edge channels of the same filling factor, we observe anomalous Landauer-Buttiker reflection coefficients for both integer and fractional edges when they traverse the corner. To unsubscribe from the BAPC announcement list, send an email to bapc-request@cosmos.phy.tufts.edu and in the body put "unsubscribe". _______________________________________________ bapc mailing list http://cosmos.phy.tufts.edu/bapc.html