Physics and Astronomy Calendar

semester, 2007


Tuesday, January 16th 2007
12:20 pm:
No seminar this week.
Subject: Organizational Meeting
2:30 pm:
No seminar this week.

Wednesday, January 17th 2007
4:00 pm:
Subject: No seminar this week.

Thursday, January 18th 2007
12:10 pm:
No seminar this week.
12:15 pm:
Speaker: Mikhail Shifman, FTPI
Subject: "Flying saucer" solitons in supersymmetric Yang-Mills
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Matthew B. Stone, Oak Ridge National Laboratory
Subject: Where the Spectrum Ends: Spectrum Termination and Reentrance in a Two-Dimensional Organometallic Magnet
Dr. Stone is a candidate for the condensed matter experimental position.

Although magnetism is fundamentally a quantum mechanical effect, it has clear macroscopic consequences. For example, the interactions occurring on the length scale of several Angstroms lead to materials with properties that allow one to attach messages to a refrigerator door, or produce 100 GB hard drives. The technological implications and diverse behavior have made magnetic materials a consistent venue of study for condensed matter physics. I will be presenting research on an organometallic antiferromagnet, piperazinium hexachlorodicuprate (PHCC). The frustrated interactions in this material lead to a magnetic ground state which only has very short range correlations such that PHCC is best described as a quantum spin liquid. The excitations associated with the quantum spin liquid ground state can easily be modified by the application of external magnetic fields. I will discuss the magnetic field versus temperature phase diagram of this system as determined by pulsed field magnetic susceptibility measurements, specific heat measurements and both elastic and inelastic neutron scattering experiments. In addition to two magnetic field-driven quantum critical points which can be described as a Bose-Einstein condensation of excitations, there also exists a reentrant phase transition between the disordered ground state and a long range ordered phase. Along with the ability to dramatically alter the excitations in PHCC using an applied magnetic field, I will also discuss a peculiar point in the zero-field excitation spectrum where higher energy excitations cause the lower energy excitations to abruptly decay.

Speaker: Dr. Chao-Lin Kuo, California Institute of Technology. Dr.Kuo is a candidate for the Astrophysics faculty position.
Subject: CMB Beyond the Acoustic Peaks
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

Together with other cosmological probes, observations of the cosmic microwave background (CMB) radiation have been used to determine standard cosmological parameters with high precision. Much more information is needed, however, to understand the link between the outlandish Lambda dominated-CDM Universe and fundamental physics. In the first part of the talk, I will describe several ongoing CMB experiments targeting the high-l power spectrum and the B-mode polarization anisotropies. These ground- and balloon-based experiments highly compliment the WMAP satellite in survey parameters and science goals. In the second part of the talk, I will describe the CMB detector development efforts at JPL/Caltech, with emphasis on the antenna-coupled transition edge sensors (TES), a technology now reaching maturity. The next generation CMB experiments enabled by this new technology will look even deeper in the B-mode polarization to pursue the imprints of the primordial gravitational background radiation left by Inflation.

2:30 pm:
Nuclear Physics Seminar in 435 Physics
No seminar this week.

Friday, January 19th 2007
2:30 pm:
No seminar this week.
No seminar this week.

Monday, January 22nd 2007
Speaker: Liliya Williams
Subject: Detecting Dark Matter Caustics

Tuesday, January 23rd 2007
12:20 pm:
Speaker: Jianjie Zhang
Subject: Electron-nuclear spin coupling in Fe/GaAs spin transport devices
1:00 pm:
Space Physics Seminar in 236A Physics
Speaker: Professor Mark Engebretson, Augsburg College
Subject: "Pc 1-2 Waves and Energetic Particle Precipitation During and After Magnetic Storms: Superposed Epoch Analysis and Case Studies.

Wednesday, January 24th 2007
4:00 pm:
Speaker: Steve Pierson, Head of Government Relations, American Physical Society
Subject: China and India: A new Sputnik? Federal funding for physical sciences research
Refreshments served in Room 216 Physics at 3:30 p.m.

Federal funding for the physical sciences has been stagnant for nearly 30 years, hindering scientific progress in many regards. Meanwhile, in the last decade, countries like China and India have made impressive strides in improving their science and technology infrastructure, to the extent that U.S. leadership in many scientific fields is, or will soon be, challenged. The United States is also losing high-tech market share and jobs. Just as Sputnik jolted the U.S. into action almost 50 years ago, many believe that the current challenges require a Sputnik-like response. Indeed, in January 2006, President Bush proposed to double the funding for physical sciences basic research. A year later, the proposed increases are yet to be enacted. In this talk, I will discuss the Washington environment for basic research funding, challenges to U.S. science leadership, and the APS efforts to increase science research budgets.


Thursday, January 25th 2007
12:10 pm:
Speaker: Terry Jones, University of Minnesota
12:15 pm:
Speaker: Alexander A. Voronov, School of Mathematics
Subject: Quantum master equation in open-closed string theory
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Dr. Emilia Morosan, Princeton University
Subject: New properties in old materials: the layered dichalcogenides
Dr. Morosan is a candidate for the Condensed Matter Experimentalist

Transition metal dichalcogenides have long been known and explored. Due to their reduced dimensionality, such compounds sometimes display charge density wave (CDW) transitions or, upon doping with magnetic ions, often reveal dramatic changes of their physical properties. I will discuss the effects of transition metal intercalation on the properties of two layered
chalcogenide materials, TiSe2 and TaS2. Although TiSe2 is one of the first known CDW-bearing materials, the nature of its CDW transition remains controversial. Recently the interest in TiSe2 has been renewed by our discovery of the new superconducting state (SC) that emerges upon Cu doping. Thus CuxTiSe2 provides the first example of a system in which controlled chemical doping can be used to study the competition between the CDW and SC. I will also discuss experiments on FexTaS2 aimed at studying the sharp switching of the magnetization that we recently observed in this compound for x = 1/4. For this particular Fe content, FexTaS2 orders ferromagnetically below 160 K and displays very sharp hysteresis loops in the ordered state for H||c. The corresponding magnetoresistance is negative, and qualitatively reproduces the features observed in the M(H) data, by showing a sharp drop around the critical field for moment reversal.

Speaker: Dr. Vuk Mandic, California Inst. of Technology. Dr.Mandic is a candidate for the Astrophysics faculty position.
Subject: Searching for Stochastic Gravitational-wave Background with LIGO: Results and Implications
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

The Laser Interferometer Gravitational-wave Observatory (LIGO) has built three multi-km scale interferometers, designed to search for gravitational waves (GW). One of the targets for these searches is the stochastic GW background, whose existence is expected both due to cosmological and due to astrophysical sources. We discuss the status of LIGO, the most recent results of the search for stochastic GW radiation with LIGO interferometers, and the implications of these results for some of the theoretical models of stochastic GW background.

3:00 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Scott Bowman, University of Minnesota
Subject: T.B.A.

Friday, January 26th 2007
Speaker: Lisa Gannett, Department of Philosophy, Saint Mary's University
Subject: Theodosius Dobzhansky, the Typological-Population Distinction, and the Question of Race
Refreshments served in Room 216 Physics at 3:15 p.m. Cosponsored by Studies of Science and Tech., the MN Cntr for Philosophy of Sci., the Consortium on Law & Values in Health, Env. & Life Sciences

The typological-population distinction has its genesis in the distinction between "races as types" and "races as populations" made by Theodosius Dobzhansky in a paper delivered at a 1950 Cold Spring Harbor symposium that sought to embrace physical anthropology and human genetics within the modern evolutionary synthesis. While developments in Dobzhansky's field of population genetics rendered the concept of "races as types" obsolete, his redefinition of "races as populations" remains to be fully understood, both historically and philosophically. This paper explores the question of race - especially the question of the reality of race - in Dobzhansky's work. Dobzhansky's views are compared with those of his and our contemporaries and critically assessed. Particular attention is paid to tensions arising in his joint appeal to an object ontology and a process ontology. On the one hand, a race is considered to be a genetically distinct Mendelian population, "which exists regardless of whether a classifier describes it or not." On the other hand, "what is [considered] essential about races is not their state of being but that of becoming."


Monday, January 29th 2007
Speaker: Jean-Philippe Uzan, Institut d'Astrophysique de Paris
Subject: Gravity and the nature of dark energy

The understanding of the physical origin of the acceleration of our universe is a big puzzle for both cosmology and theoretical physics. I will first briefly review the evidence for the acceleration of the expansion of the universe, focusing on the assumptions that lead to this conclusion. I will then describe a general classification of the models that could explain this acceleration and explain why it calls for better tests of general relativity on astrophysical and cosmological scales. I will review some of the possible tests and then discuss what constraints can be set from cosmology on a general class of theories including general relativity, namely scalar-tensor
theories.

1:30 pm:
Speaker: Amy Connolly, UCLA, Candidate for the Astrophysics & Cosmology Faculty Position
Subject: Closing in on Ultra-High Energy Neutrinos with the Radio Detection Technique

No diffuse, extraterrestrial neutrino flux has yet been observed, but there is expected to be a near-guaranteed flux of neutrinos from interactions between the highest energy cosmic rays and cosmic microwave background photons. These neutrinos would carry information that would complement data from other cosmic messengers. The radio Cerenkov technique allows us to build experiments with effective detection volumes that exceed hundreds of km^3, the volume that is needed to be sensitive to the expected flux of neutrinos above 10^18 eV. The Antarctic Impulsive Transient Antenna (ANITA) is a balloon experiment that aims to detect neutrinos deep in the Antarctic ice using this technique. ANITA just completed its first full physics flight this month. I will give an overview of the ANITA project, and discuss techniques that we are developing to improve our simulations of the detection system. I will then describe two next-generation radio detection experiments under development, one in a salt formation and another on the Antarctic Ross Ice Shelf, that are designed to move beyond the discovery stage and measure a sample of ultra-high energy neutrinos that is large enough to study their rich properties.


Tuesday, January 30th 2007
12:20 pm:
Speaker: Jun Kyung Chung
Subject: Coarse grained molecular dynamics using frequency filtering
1:00 pm:
Space Physics Seminar in 236A Physics
No seminar this week.

Wednesday, January 31st 2007
4:00 pm:
Speaker: Bolek Wyslouch - MIT
Subject: Heavy-Ion Physics with the CMS Experiment at the Large Hadron Collider
Refreshments served in Room 216 Physics at 3:30 p.m.

The Large Hadron Collider at CERN will collide protons at \sqrt{s} = 14 TeV and lead ions at \sqrt{s_NN} = 5.5 TeV. The new energy regime will allow us to significantly extend and enhance our knowledge of the behavior of the strongly interacting hot nuclear matter recently observed in the heavy-ion collisions at RHIC. The physics program of the Compact Muon Solenoid (CMS) includes the study of heavy-ion collisions. The high energies
available at the LHC will allow high statistics studies of the dense partonic system with hard probes: heavy quarks and quarkonia with an emphasis on the b and Upsilon, high p_T jets, photons, as well as Z bosons. I will present the physics goals of the heavy-ion program at the LHC including examples of the planned physics measurements using the CMS apparatus.


Thursday, February 1st 2007
12:10 pm:
Speaker: Larry Rudnick, University of Minnesota
Subject: The Feasibility of Shading the Greenhouse with Dust Clouds at the Stable Lunar Lagrange Points
12:15 pm:
Speaker: Enrico Lunghi, Fermilab
Subject: Rare decays and dark matter in the MSSM from the GUT scale
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Michel Kenzelmann, ETH Zurich. Dr. Kinzelmann is a candidate for the Condensed Matter Experimentalist
Subject: Competing interactions in quantum magnetic insulators

I will talk about magnetic insulators in which the symmetry of the spin interactions leads to strong fluctuations and qualitatively new ground states. Of particular interest are low-dimensional magnets in which the magnetic moments interact mainly in one or two directions, or frustrated magnets in which long-range magnetic order is impeded because of competing interactions. The proximity of such systems to quantum critical points can lead to emergent quantum coherence over macroscopic length scales and strong cross-coupling between magnetic order and the nuclear lattice. Case in point is a new class of multiferroic materials in which the magnetic and ferroelectric order parameters are directly coupled, and the application of a magnetic field can suppress or switch the electric polarization. Our neutron measurements reveal that ferroelectricity is induced by magnetic order and emerges only if the magnetic structure creates a polar axis. The spin dynamics and the field-temperature phase diagram of the ordered phases provide evidence that competing ground states are essential but not sufficient for ferroelectricity. The origin of the magneto-electric coupling is not understood at present, but it may arise from anisotropic exchange couplings such as Dzyahloshinskii-Moriya interactions.

Speaker: Ignacio Taboada, Berkeley. Candidate for the Astrophysics & Cosmology Faculty Position
Subject: High Energy Neutrino Astrophysics: IceCube

Forty years ago it was recognized that the detection of high energy (E > 10^11 eV) neutrinos from astronomical sources would require the construction of a device with 1 gigaton (or 1 cubic kilometer of water) of target material. This idea is finally becoming a reality with the construction, at the South Pole, of IceCube. Detection of extraterrestrial high energy neutrinos will open new avenues in astrophysics and neutrino physics. What is the origin of the highest energy cosmic rays? How do gamma-ray bursts, the most powerful objects in the universe, work? What is the origin of dark matter? These are just some of the questions that IceCube will help answer. In this talk I will present a summary of the construction status of IceCube, summarize the results of AMANDA, the predecessor (and now part) of IceCube, and present first results from IceCube.

Speaker: Jim Kneller, University of Minnesota
Subject: Temporal Evolution of the Supernova Neutrino Signal

Friday, February 2nd 2007
Speaker: Mark Dykman, Michigan State University
Subject: Metastable decay via quantum activation

Standard mechanisms of metastable decay are tunneling and thermal activation. We show that periodically modulated systems may display a different decay mechanism, quantum activation. Here, decay occurs via diffusion over a quasi-energy barrier. The diffusion is induced by quantum fluctuations. We study quantum activation for nonlinear oscillators and show that the decay rate displays unexpected features. It exhibits scaling behavior near critical parameter values where metastable vibrational states disappear. The results bear on quantum measurements with nonlinear oscillators.

Speaker: Roger Penrose, Oxford University
Subject: Before the Big Bang: A Radical Solution to a Profound Cosmological Mystery
Dr. Penrose will also discuss his new book at 7:00 pm at the University Bookstore.
Speaker: Helen Rozwadowski, Department of History, University of Connecticut
Subject: Science, Technology, and the 1960s Ocean: New Worlds of Exploration and Exploitation
Refreshments served in Room 216 Physics at 3:15 p.m.

The decade of the 1960s in oceanography was characterized by excitement and optimism regarding the possibilities for studying the ocean and for the uses to which the resulting technology and knowledge might be put. The second world war touched off explosive growth of ocean sciences, such that marine sciences and oceanography are among the most generously funded sciences in the United States (and often at the top of this list). Certainly through the Cold War, physical oceanography, funded for its relevance to undersea warfare, dominated scientific study of the ocean. A look through 1960s eyes, however, reveals a different vista. Study of the ocean was expected to encompass human physiology, engineering and underwater archaeology in addition to geology, chemistry, marine biology, and physics. The number of anticipated uses of the ocean environment and its resources proliferated. These new uses, many eagerly anticipated but never realized, included wilderness to explore, farmland to cultivate, battleground, playground, dump site, mine, oil well, construction site, movie set, and human habitat. To live, work, and play on and within the ocean would require new knowledge and technology – which the ocean scientists and engineers of the 1960s eagerly set about creating. Their vision of ocean science was much broader than the version of oceanography that remained by the mid-to-late 1970s. Their version was intended to support a new human relationship with the sea, one akin to plans for that other frontier of the time, outer space


Saturday, February 3rd 2007
4:00 pm:
Speaker: Michael Marder, University of Texas, Austin
Subject: Rising above the gathering storm with U Teach
Refreshments served in Room 216 Physics at 3:30 p.m.

Monday, February 5th 2007
12:15 pm:
Speaker: Michael Dragowsky, Case Western Reserve University. Candidate for the Astrophysics & Cosmology Faculty Position
Subject: Dark Matter and Particle Astrophysics

I will present an overview of the broad program to determine the nature of dark matter that involves investigations in astronomy, astrophysics, cosmology and particle physics. My research concentrates on testing the hypothesis that weakly-interacting massive particles (WIMPS) constitute the dark matter. This hypothesis is testable through direct detection of nuclear recoils at low energy resulting from elastic scattering of WIMPs with nuclei. It is also testable by observing WIMP annihilation products, such as GeV-scale gamma-rays and/or neutrinos, as well as antiparticles in the near-Earth environment. Accelerator facilities, principally the Large Hadron Collider in Switzerland, will probe the TeV energy scale that should be associated with a WIMP solution to the dark matter question. The interplay between these three areas is the subject of my talk, with emphasis given to the direct detection of dark matter via athermal phonon mediated detectors of the CDMS (Cryogenic Dark Matter Search) collaboration and the use of scintillation in liquid Argon and liquid Neon with the DEAP&CLEAN collaboration.


Tuesday, February 6th 2007
12:20 pm:
Speaker: Yu Chen
Subject: Transport in metallic nanowires
1:00 pm:
Space Physics Seminar in 236A Physics
Speaker: Professor Terry Jones, University of Minnesota
Subject: Magnetic Fields in Galaxies

Wednesday, February 7th 2007
4:00 pm:
Speaker: Open Date
Refreshments served in Room 216 Physics at 3:30 p.m.

Thursday, February 8th 2007
12:15 pm:
Speaker: Akin Wingerter, Ohio State University
Subject: A Heterotic Landscape [hep-th/0611095]
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Nuh Gedik, California Institute of Technology. Dr. Gedik is a candidate for the Condensed Matter Experimentalist
Subject: Ultrafast structural dynamics observed with atomic scale resolution

Ultrafast optical spectroscopy has long been used with great success to generate and probe non-equilibrium electronic excitations with femtosecond time resolution. The spatial resolution in these techniques, however, is limited to micron scales and structural dynamics can only be inferred indirectly. I will report direct measurements of structural dynamics with atomic scale spatial resolution by using ultrafast electron diffraction (UED). In UED, a femtosecond laser pulse is split into two, the first part is used to induce structural change and the second part
is used to generate ultrafast high energy electron packets via photoelectric effect. Recording the diffraction pattern of these electron packets at different times after the photo-excitation of the sample provides a movie of the laser induced structural change with sub-picosecond temporal and sub-Angstrom spatial resolution. I will discuss recent experiments where we used UED to observe lattice dynamics in cuprate superconductors in response to photo-excitation of the charge carriers. Above certain threshold laser intensity, we observe direct conversion between two structures with different c axis lattice constants indicating a non-equilibrium structural phase transition.

2:00 pm:
Speaker: James Aguirre, a candidate for the Astrophysics & Cosmology faculty position
Subject: Studying the Evolution of the Universe with Submillimeter Astronomy

Approximately half the light ever produced from stars and the formation of supermassive black holes has been absorbed and re-emitted by dust. This light traces the formation of structure in a cold dark matter dominated universe, but has until recently been hidden due to technological limitations. I will discuss how I have been studying the galaxies producing this light by using new instrumentation to detect them and find their redshifts, and will discuss future plans for the study of mass assembly at high redshift.

2:30 pm:
Nuclear Physics Seminar in 435 Physics
No seminar this week.

Friday, February 9th 2007
3:35 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. James Leger, University of Minnesota
Subject: Managing Diffraction and Polarization: New Tools for Optical Scientists
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics
Speaker: Nina Lerman, Department of History, Whitman College
Subject: Jim Crow and the White Way: Thoughts on Race, Progress, and Early Electrification in the US.
Refreshments served in Room 216 Physics at 3:15 p.m.

Electricity has been linked, by cultural historians of the US and by historians of technology, with American ideologies of progress, civilization, and, in turn, whiteness. Perhaps most obviously demonstrated at the Columbian Exposition of 1893, but evident in any number of late 19th- and early 20th-century sources, electricity seems to have been entwined with a kind of moral obligation to modernity – at least for the white nation. In a period of increasingly entrenched racism, when civilized progress was routinely contrasted with the dark primitive and material privileges were increasingly denied (on trains, in bathrooms, on sidewalks) in demonstration of legal and social segregation, electrification would seem an unlikely feature of any spaces of designated blackness. Yet Tuskegee Institute was electrified by 1898, and several of its spin-off schools in the rural south had generators at a time when, overall, electrification was still rare, and northern African Americans had trouble putting technological knowledge to economic use. This paper seeks to link the material dimensions of technological choice with ideological context, exploring the entwined and regionalized understandings of race, technology, and social order in a period of rapid industrialization.


Monday, February 12th 2007
Speaker: Marco Peloso
Subject: The fate of SUSY flat directions, and their role at reheating

Tuesday, February 13th 2007
12:20 pm:
Speaker: Mun Chan, University of Minnesota
Subject: Spin Injection into Normal Metals
1:00 pm:
Space Physics Seminar in 236A Physics
No seminar this week.
1:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Kenji Fukushima, Brookhaven National Laboratory, a candidate for the Nuclear Theory faculty position.
Subject: Exploring paradigms of QCD - Hot, Dense, and Energetic Matter

Quantum Chromodynamics (QCD) has rich contents under various
extreme environments. I will discuss recent developments of
hot and dense QCD I have been involved in; a complicated
phase structure of color superconductivity at high baryon
density, an effective description by the idea of the Color
Glass Condensate at high gluon density, and its application
to the very initial stage of heavy-ion collisions. I will
present some ongoing works and address a way to go from my
point of view.


Wednesday, February 14th 2007
1:30 pm:
Ph.D. Thesis Defense in 435 Physics
Speaker: K. H. Sarwa B. Tan
Subject: Electrical Transport in Indium Oxide Thin Films near the Magnetic Field-Induced Superconductor-Insulator Transition
4:00 pm:
Speaker: Alexander Grosberg
Subject: To knot or not to knot: making neckties of polymers
Refreshments served in Room 216 Physics at 3:30 p.m.

The mathematics and physics of knots has a long and fascinating
history, starting from a model of an atom suggested by W.Thompson
(Lord Kelvin). Knots in DNA are abundant and important. Recently, we surveyed the protein data bank and found that evolution for some as yet unknown reason preferred unknotted proteins, although a few beautiful counterexamples were found, including Gordian knot in human ubiquitin hydrolase. In theoretical aspect, the field was long dominated by either highly abstract mathematics or computer simulations. Recently, some progress was made in the direction of physical understanding of knots. In the talk, all these various aspects will be reviewed in some mixture.


Thursday, February 15th 2007
12:10 pm:
Speaker: Paul Edmon and Tom Jones, University of Minnesota
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Jason Hancock, Stanford University. Dr. Hancock is a candidate for the Condensed Matter Experimentalist
Subject: Resonant inelastic X-ray scattering: a new tool for the study of correlated-electron materials

Recent angle-resolved photoemission spectroscopy (ARPES) results suggest a ubiquity and prominence of both quasiparticle and higher-energy correlated bands in cuprate systems. While ARPES is of great benefit to the understanding the electronic structure of correlated electron systems, the technique is limited in the sense that it probes only the occupied portion of the spectral function. In analogy to Raman spectroscopy, resonant inelastic X-ray scattering (RIXS) is a two-particle spectroscopic technique involving both particle removal and particle addition states, and is thereby capable of probing the unoccupied states of an interacting many-electron system. In contrast to Raman spectroscopy, RIXS provides the additional capability of exploring momentum dependence. I will give an introduction to the burgeoning technique of RIXS, using cuprates as an example, and present new results on the energy structure of certain model systems. I will also present results that suggest how scattering geometry may act as a sensitive probe of excitation symmetry, and suggest directions for the technique in future experiments.

2:00 pm:
Astrophysics Colloquium in 133 Physics
Speaker: Dr. Richard Schnee, Dr. Schnee is a candidate for the Astrophysics faculty position.
Subject: What’s the Matter in the Universe? Looking for Wimps with the Cryogenic Dark Matter Search
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

Astrophysical observations indicate that at least 90% of the mass of any galaxy -- and as much as 98% of the mass of the universe -- is in the form of matter that cannot be seen. Furthermore, most of this matter isn't even made from protons and neutrons -- or any other known particles. What could this matter be and how can we find out? Perhaps the best motivated possibility is weakly interacting massive particles (WIMPs) left over from the Big Bang; these particles naturally arise, for example, under supersymmetry. Detection of these particles requires exquisite
rejection of interactions from natural radioactivity, as achieved using the CDMS experiment's cryogenically cooled crystals of silicon or germanium with thin-film sensors to detect both ionization and athermal phonons. Operation of these novel detectors and the prospects for discovering what's the matter in the universe will be discussed.


Friday, February 16th 2007
2:30 pm:
Speaker: Sergei Dubovsky, Harvard University
Subject: Quantum Horizons of the Standard Model Landscape
Please note CHANGE IN TIME
No H.S.T. Colloquium this week.

Monday, February 19th 2007
Speaker: Chris Savage, University of Minnesota
Subject: The annual modulation of dark matter in the presence of streams

Tuesday, February 20th 2007
12:20 pm:
Condensed Matter Seminar in 435 Physics
Speaker: Dr. Xuan Gao, Harvard University, Dept. of Chemistry and Chemical Biology. Dr. Gao is a candidate for the Condensed Matter Experimentalist Position.
Subject: The Sensitivity Limits of Nanowire Bio-Sensors

Nanowire field effect transistors (NWFETs) are emerging as powerful tools for biological applications such as bio-molecule detection, yet their sensitivity limits are not understood at a fundamental level. I will discuss the interplay of device parameters such as gate bias and NW diameter on the operating modality and sensitivity of NWFET sensors. pH and cancer marker detections are studied as silicon-NWFETs are tuned from linear to subthreshold regimes by electrochemical gating. First, pH sensing data show that NWFET has the strongest response and the best signal to noise ratio in the subthreshold regime. Operating in the subthreshold regime also reduces the detection limit for prostate specific antigen down to ~fM for a device with ~pM detection limit in the linear regime. This sensitivity improvement is due to the reduced screening ability of carriers in NW. A quantitative model describing these results and the intrinsic charge detection limit of NWFET sensors will be discussed.

1:00 pm:
Space Physics Seminar in 236A Physics
Speaker: Lynn Wilson, University of Minnesota
Subject: Possible Dissipation Mechanisms of Interplanetary Shocks: Pilot Results from a Wind/WAVES Study

Wednesday, February 21st 2007
4:00 pm:
Speaker: Marco Peloso
Subject: Before and After Inflation
Refreshments served in Room 216 Physics at 3:30 p.m.

I will review some aspects of inflationary physics. Inflation
is responsible for producing the ``clean'' homogeneous and isotropic
universe we live in, starting from rather generic initial conditions.
While inflation is very efficient in erasing any information on the
initial state, some trace may have remained on the largest observable
scales, if inflation had a limited duration. Inflation produced the
cosmological perturbations which are imprinted in the Cosmic Microwave
Background (CMB) radiation, and which are the ``seeds'' of the present
galaxies. The recent CMB data measured by WMAP are overall in excellent
agreement with the simplest inflationary prediction. However, they also
present a few unclear features, as for instance a hint for broken
isotropy at the largest scales. In the first part of the talk I will
present an attempt to explain this feature in terms of a primordial
anisotropy which survived a limited amount of inflation. In the second
part, I will instead discuss the reheating stage after inflation,
focusing on the role that nonperturbative effects may have played in
this period.


Thursday, February 22nd 2007
12:10 pm:
Speaker: Steve Warren, University of Minnesota
12:15 pm:
Speaker: Kazuhiro Tobe, Michigan State
Subject: Light MSSM Higgs boson scenario and its test at hadron colliders
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Jian Huang, Princeton University
Subject: Novel transport behaviors in strongly correlated two-dimensional holes
2:30 pm:
Nuclear Physics Seminar in 435 Physics
No seminar this week.

Friday, February 23rd 2007
3:35 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Anil Seth, Harvard SAO
Subject: From the Inside Out: the Evolution of Late-Type Galaxy Nuclei & Disks
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

I will present observational constraints on the formation and evolution of two separate components of late-type spiral galaxies, their nuclear star clusters and their disks. Both projects stem from HST observations of nearby, edge-on galaxies. First, I will show nuclear clusters that have both compact (<10 pc) disk and spheroidal components. These compact disk components are aligned with the major axis of the galaxy disk and have younger stellar populations than the spheroidal components. Combined with spectroscopic evidence of multiple stellar populations, these observations strongly suggest that nuclear star clusters form in situ, with episodic star formation occurring in compact disks. Second, I will examine the vertical structure of six low mass, late-type spiral galaxies. By using resolved stars to track populations of different ages, I will demonstrate that older populations have larger disk scale heights. The metallicity of the oldest population is [Z] ~ -1, similar to the Milky Way thick disk, and does not vary with height above the disk. These observations require both disk heating and merging to play a role in the formation of these disks. Finally, I will present the preliminary detection of a low-metallicity stellar halo in one of these galaxies, NGC 4244.

Speaker: Eileen Reeves, Department of Comparative Literature, Princeton University
Subject: Mere Projections: Galileo and Scheiner on the Sunspots
Refreshments served in Room 216 Physics at 3:15 p.m.

Despite the novelty of sunspot study in the Latin West, Galileo placed no particular emphasis on pitfalls in either the observational process or the visual presentation of his data: in the second of his Letters on the Sunspots, the camera obscura and the ephemeral phenomena it was designed to show figure as curiously available to all. While Galileo emphasized the naturalness and inevitability of the engravings that accompanied his work—or, better, the irrelevance of their prehistory as traced projections of the sunspots—his rival Christoph Scheiner masked his own reliance on the camera obscura with frequent and misleading references to his direct observations of the sun and to the inaccuracy of his hand-drawn sketches. In this lecture I will examine the strategies adopted by both observers in the earliest phase of the debate, and I will use the sunspot images produced through direct observation by the English scientist Thomas Harriot in this same period to evaluate the logic of their arguments, and the strengths and limits of these visual data.


Monday, February 26th 2007
Speaker: Larry Rudnick
Subject: The Role of Cosmic Rays in Galaxy Formation

Tuesday, February 27th 2007
12:20 pm:
Subject: APS March Meeting practice talks
1:00 pm:
Space Physics Seminar in 236A Physics
The Space Physics Seminar will not be held this week. Please attend the Physics and Astronomy Colloquium on Wednesday instead.

Wednesday, February 28th 2007
4:00 pm:
Speaker: Ellen Zweibel, University of Wisconsin
Subject: The Generation and Evolution of Astrophysical Magnetic Fields
Refreshments served in Room 216 Physics at 3:30 p.m.

Despite recent advances in cosmology, we still do not understand how or when magnetic fields originated. After reviewing the evidence, I will discuss one particular scenario in which magnetic fields originate in accretion disks, are amplified by a dynamo, are ejected into the ambient medium in a jet, and eventually become pervasive. Certain aspects of the problem are relevant to the formation of the first stars.


Thursday, March 1st 2007
12:10 pm:
Speaker: Sean O'Neill and Elisha Polomski, both University of Minnesota
12:15 pm:
Speaker: Alexei Yung, PNPI/FTPI
Subject: Confined non-Abelian monopoles in N=1 supersymmetric QCD
1:25 pm:
Condensed Matter Seminar in 210 Physics
Subject: APS March Meeting practice talks
2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Misha Stephanov, University of Illinois, Chicago
Subject: AdS/QCD
Professor Stephanov is a candidate for the Nuclear Theory position at the associate professor level.

I shall describe a bottom-up approach to constructing a
higher-dimensional theory holographically dual to QCD: AdS/QCD.
Hadronic models built in this way simultaneously satisfy
chiral symmetry constraints together with QCD sum rules
and can be constrained by matching asymptotic behavior of QCD
correlation functions. The simplest model of this type gives a
remarkably good fit to low energy hadronic observables.


Friday, March 2nd 2007
3:35 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Eric Hallman, CASA, Colorado
Subject: Simulating Large Area Galaxy Cluster Surveys
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

Clusters of galaxies form from the highest peaks in the primordial spectrum of density perturbations generated by inflation in the early universe. They are the most massive virialized structures in the universe, and as such are rare objects. The number density of galaxy clusters as a function of mass and redshift is strongly dependent on a number of cosmological parameters.

I will present results from a study of sophisticated synthetic Sunyaev-Zel'dovich effect (SZE) galaxy cluster surveys with both large sky coverage and high angular resolution. These surveys are generated from simulations using the cosmological adaptive mesh refinement (AMR) hydro/N-body code Enzo. I will show comparisons of expected yields for various upcoming SZE cluster surveys using the Atacama Cosmology Telescope, the South Pole Telescope, Planck, and others as calculated from our synthetic surveys.

These synthetic surveys provide extremely useful guidance for the interpretation of galaxy cluster surveys. The precise
quantification of survey systematics will allow observers to both create effective survey strategies and ultimately to accurately determine cosmological parameters.

Speaker: Mark Borrello, History of Science and Technology, University of Minnesota
Subject: There's no success like failure: 'Relative Significance' in Evolutionary Biology and the History of Evolutionary Biology
Refreshments served in Room 216 Physics at 3:15 p.m.

Responding to Steve Shapin’s recent essay in Isis bemoaning the lack of scholarship that appeals to an audience beyond a very limited group of historians, I’ll use John Beatty’s idea of ‘relative significance’ disputes in evolutionary theory, and the history of biology more broadly, to argue that the debate over group selection can illuminate the history of evolutionary biology and the process of science more generally. The debate over group selection, though often characterized as a categorical rejection of naïve evolutionary theorizing, was actually a much more complex affair. Analyzing the initial debate that occurred in the 1960s and then examining the current status of the theory demonstrates the value of the relative significance framework for historians of biology and invites application of this approach in other sciences.


Monday, March 5th 2007
Speaker: Johannes Hubmayr
Subject: The Non-Gaussian Cold Spot in the 3-year WMAP Data

Tuesday, March 6th 2007
12:20 pm:
Due to the APS March meeting, there will be no sack lunch seminar.
1:00 pm:
Space Physics Seminar in 236A Physics
Speaker: Tom Jones, University of Minnesota
Subject: Modeling Particle Acceleration at Shocks.

Wednesday, March 7th 2007
4:00 pm:
Speaker: Wick Haxton - University of Washington
Subject: What Nuclear Physicists Don't Know About Neutrinos
Refreshments served in Room 216 Physics at 3:30 p.m.

Some intriguing discoveries in neutrino physics have been made in the past decade, clarifying their behavior in vacuum and in matter, and defining their role as a component of dark matter. But a lot remains to be learned. I will describe some of the questions that impact nuclear physics, including neutrinos in quiescent and explosive massive stars, their properties under particle-antiparticle conjugation, and their importance in
a variety of mechanisms for nucleosynthesis.


Thursday, March 8th 2007
12:15 pm:
No seminar this week.
1:25 pm:
Condensed Matter Seminar in 210 Physics
No Seminar this week.
2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Feng Yuan, Brookhaven National Lab. Feng Yuan is a candidate for the Nuclear Theory Faculty position.
Subject: A New Spin on the Proton: the Perspective from RHIC

In the naive model of the proton, its 1/2 spin is carried by its
quark constituents. However, experiments over the last several decades have shown that the quark spin only contribute a small portion of the proton spin. In this talk, I will discuss the current status of world efforts for solving this "spin crisis", focusing on the theoretical challenges and the perspective from the RHIC spin program.


Friday, March 9th 2007
3:35 pm:
Astrophysics Colloquium in 210 Physics
Subject: No Colloquium this week.
No colloquium: Spring Break

Monday, March 12th 2007
Spring Break - No ACLS Seminar this week

Tuesday, March 13th 2007
12:20 pm:
Spring Break: No Seminar this week.
1:00 pm:
Space Physics Seminar in 236A Physics
Spring Break: No Seminar this week.

Wednesday, March 14th 2007
4:00 pm:
Spring Break: No Colloquium this week.

Thursday, March 15th 2007
12:10 pm:
Spring Break: No Seminar this week.
12:15 pm:
Spring Break: No Seminar this week
1:25 pm:
Condensed Matter Seminar in 210 Physics
Spring Break: No Seminar this week.
2:30 pm:
Nuclear Physics Seminar in 435 Physics
Spring Break: No Seminar this week.

Friday, March 16th 2007
3:35 pm:
Astrophysics Colloquium in 210 Physics
Spring Break: No Colloquium this week.
Spring Break: No Colloquium this week.

Monday, March 19th 2007
Speaker: Emir Gumrukcuoglu
Subject: Relic Anisotropy as a Source for CMB Anomalies

Tuesday, March 20th 2007
12:20 pm:
Speaker: Shun Wang
Subject: Investigating Incommensurate Nanoscale Helical Pitch in SmC_alpha* Phase by Differential Optical Reflectivity
1:00 pm:
Space Physics Seminar in 236A Physics
Speaker: Slava Pilipenko, Space Research Institute, Moscow
Subject: Interaction of propagating magnetosonic and Alfven waves in longitudinally inhomogeneous gyrotropic plasma.

Wednesday, March 21st 2007
4:00 pm:
Speaker: Professor Barry Barish - California Institute of Technology
Subject: "Probing Einstein’s Universe"
Refreshments served in Room 216 Physics following lecture

As a consequence of his theory of general relativity, Einstein predicted the existence of a new physical phenomenon called gravitational radiation. In this theory, concentrations of mass (or energy) warp space-time, and changes in the shape of such objects cause distortions called gravitational waves that propagate through the Universe at the speed of light. Almost 100 years later, these waves so fundamental to Einstein’s theory are yet to be directly observed. A new generation of interferometric detectors represents an ambitious attempt to detect such waves from some of the most spectacular phenomena in the universe: colliding black holes, supernovae and even relic waves from the big bang. The science of gravitational waves, the status of the searches and the prospects for detection will be discussed.


Thursday, March 22nd 2007
12:10 pm:
Speaker: Martha Boyer and Bob Gehrz, both from the University of Minnesota
12:15 pm:
Speaker: Andre de Gouvea, Northwestern University
Subject: Neutrino Masses and New Physics at or Below the Electroweak Scale
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Greg McKusky
Subject: Double Magnetic Tunnel Junctions and Spin Diffusion Length Measurements
2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Abhijit Majumder, Duke
Subject: Probing the structure of the strongly coupled Quark Gluon Plasma
Abhijit Majumder is a candidate for the nuclear theory faculty position at the assistant professor level.

The Relativistic Heavy-Ion Collider (RHIC) has produced a wide variety of measurements which have led to major strides in our understanding of the structure of strongly interacting matter heated beyond the deconfinement temperature. We focus on a class of observables centered around the perturbative modification of hard jets and jet-like correlations which have been instrumental in resolving the basic picture underlying some of the startling discoveries at RHIC. Jet modification and jet medium interactions will be shown to yield a consistent space-time profile of the expanding bulk matter and in conjunction with bulk fluctuations demonstrate sensitivity to the basic degrees of freedom prevalent in the Quark Gluon Plasma.

4:00 pm:
Speaker: Barry C. Barish, Caltech
Subject: The Next Great Particle Accelerator: The International Linear Collider
Refreshments served in Room 216 Physics at 3:30 p.m.

There is a consensus among the worldwide high energy physics community that a TeV scale linear electron positron collider should be the highest priority long term goal for the field. This next great particle accelerator, together with the Large Hadron Collider (LHC) at CERN, will enable a comprehensive exploration of the TeV energy scale where many of the new phenomena we seek, like supersymmetry or possibly even extra dimensions could reveal themselves. The international community has chosen the superconducting rf technology to be the basis of the international linear collider final design, in anticipation of a construction project to begin in about 2012. A global design effort has been created to guide the R&D and technical design toward construction of the ILC. In this presentation, I will discuss the science motivation, the technology, and will review recent progress and plans toward this exciting future international facility.


Friday, March 23rd 2007
3:35 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Karen Leighly, Ohio State U, on sabbatical from the University of Oklahoma
Subject: Quasar Broad Line Region Emission and Kinetics
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics
Speaker: William Ashworth, Linda Hall Library, Kansas City, MO
Subject: Bucculentus: The Underside of the Scientific Revolution
Refreshments served in Room 216 Physics at 3:15 p.m.

Monday, March 26th 2007
Speaker: Crystal Austin

Tuesday, March 27th 2007
1:00 pm:
Space Physics Seminar in 236A Physics
Speaker: Bob Lysak, University of Minnesota
Subject: Alfven wave propagation in the Io plasma torus.

Wednesday, March 28th 2007
4:00 pm:
Speaker: Gary Horowitz
Subject: Quantum Black Holes
Refreshments served in Room 216 Physics at 3:30 p.m.

Black holes are a continuing source of mystery. Although their classical properties have been understood since the 1970's, their quantum properties raise some of the deepest questions in theoretical physics. Some of these questions have recently been answered using string theory. I will review these fundamental questions, and the aspects of string theory needed to answer them. I will then explain the recent developments and new insights into black holes that they provide. Some puzzles remain, and I will discuss the prospects for further progress.


Thursday, March 29th 2007
12:10 pm:
Speaker: Gerry Ruch, University of Minnesota
12:15 pm:
Speaker: Joel Giedt, FTPI
Subject: Single-sector gauge mediation, warped extra dimensions, and the Large Hadron Collider

We propose a gravitational dual for ``single-sector'' models. These are supersymmetric extensions to the Standard Model where some particles of the Minimal Supersymmetric Standard Model MSSM)
are composites of a strongly-coupled gauge theory. The composite states feel supersymmetry-breaking directly. As a consequence, the spectrum of the MSSM is split: first and second generation squarks and sleptons obtain masses of order 5-10 TeV. The remaining MSSM fields experience gauge mediation. In our work, the single-sector scenario is expressed in a dual gravitational
AdS(5)-like description, inspired by flux-background solutions of Type IIB supergravity. These backgrounds have all supersymmetry broken in the depths of the ``throat,'' equivalent to the vicinity of the infrared brane. Specifically, the metric deviates from AdS(5) near the IR brane. A single parameter
characterizes the supersymmetry-breaking of the background in this MSSM-in-the-bulk model. Thus, the model is highly predictive. The collider signals are investigated and are shown
to be similar to gauge mediation with a neutralino NLSP that decays promptly to a gravitino LSP, but with rates that are lower by a factor of a few; the single-sector models can be detected and distinguished from mSUGRA and conventional gauge mediation with 1-10 1/fb of LHC data.

1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Kevin Dorfman CEMS, University of Minnesota
Subject: DNA electrophoresis in periodically constricted geometries
2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Alex Heger, Los Alamos National Lab and University of California, Santa Cruz
Subject: Nucleosynthesis in the First Stars
Alex Heger is a candidate for the faculty position

According to modern theory and cosmological simulations, the very
first generation of stars that formed in the universe typically
were much more massive than stars forming today. These first stars formed from the material left behind by the big bang, almost exclusively hydrogen and helium. Their resulting evolution and explosive deaths were much different from modern supernovae, with a different central engine and a much more powerful explosion. The resulting nucleosynthesis signatures, the ashes of the explosion, are predicted to show the fingerprint of this peculiar initial condition and evolution. No such fingerprint has ever been found in the observations, however. On the other hand, it will be shown that some not so massive stars with not so powerful explosions seem to be able to explain much of what was observed and considered to be the ashes of the first stars.


Friday, March 30th 2007
Speaker: C. Kenneth Waters, Dept. of Philosophy, University of Minnesota
Subject: "Causes that Make a Difference"
Refreshments served in Room 216 Physics at 3:15 p.m.

Biologists studying complex causal systems identify some factors as causes and treat other factors as background. For example, when geneticists explain biological phenomena, they often identify certain genes as the phenotypic causes and relegate other factors to the background. But many of the factors relegated to the background are causally necessary for the production of phenotypic traits, even traits at the molecular level such as the amino acid sequences in polypeptides. Critics have charged that because there is parity among causes, the privileging of genes reflects only reductionist bias, not a difference based in reality. The idea that there is an ontological parity among causes is related to a philosophical puzzle identified by John Stuart Mill: what, other than interests or biases, could possibly justify identifying some causes as the actual or operative ones, and other causes as mere background? The aim of my talk is to solve this conceptual puzzle. It turns out that my solution helps answer a seemingly unrelated philosophical question: what kind of causal generality matters in biology?

4:00 pm:
Subject: Come meet some prospective graduate students in the Astronomy Reading Room
Refreshments served.

Monday, April 2nd 2007
Speaker: Michael DuVernois
Subject: ANITA and high-energy radio neutrino detection

Tuesday, April 3rd 2007
12:20 pm:
Speaker: LiDong Pan
Subject: Optical Investigation of Novel Bent-Core Liquid Crystal Phases
1:00 pm:
Space Physics Seminar in 236A Physics
Speaker: Yukitoshi Nishimura, Tohoku University
Subject: Storm-time large-scale electric fields observed by the Akebono satellite

Wednesday, April 4th 2007
4:00 pm:
Speaker: No speaker this week due to illness.
Refreshments served in Room 216 Physics at 3:30 p.m.

Thursday, April 5th 2007
12:10 pm:
Speaker: Andrew Helton and Chick Woodward, University of Minnesota
12:15 pm:
Speaker: Ryuichiro Kitano, SLAC
Subject: Sweet Spot Supersymmetry
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Michael Garwood, Center for Magnetic Resonance Research, University of Minnesota
Subject: Novel MRI using a swept radiofrequency
2:30 pm:
Nuclear Physics Seminar in 435 Physics
No Seminar this week.

Friday, April 6th 2007
3:35 pm:
Astrophysics Colloquium in 210 Physics
Subject: No colloquium this week.
Subject: No Colloquium this week.

Monday, April 9th 2007
Speaker: Clay Hogen-Chin
Subject: Cosmic Ray Composition at High Energies: The TRACER Project
Speaker: Boris Ivlev - U. South Carolina/U. San Luis Potosi
Subject: Enhanced tunneling through nonstationary barriers

The process of quantum tunneling through a static potential barrier is well described by the theory of Wentzel, Kramers, and Brillouin. When, due to external electric field ξ(t), the barrier is nonstationary the tunneling scenario becomes very delicate. First of all, an electron can absorb a number of quanta of the external field and to tunnel in a more transparent part (with a higher energy) of the barrier. This process is known as photon-assisted tunneling. The probability of this process can be calculated by the method of classical trajectories in complex time. In this case analytical properties of the function ξ(t), which can be sinusoidal or of a pulsed type, in the complex plane of time play a crucial role. In addition to photon-assisted tunneling, which has no conflict with intuition, there is another under-barrier process which is counter-intuitive and is called Euclidean resonance. A new branch of the wave function is created under the barrier due to nonstationary conditions. As a result, the tunneling probability strongly enhances and can be not exponentially small even for almost classical barriers. Remarkable, that an electron loses its energy under the barrier. Classical trajectories in complex time are also applicable to description of Euclidean resonance. Analytical methods and a direct numerical solution of Schroedinger equation are used to study photon-assisted tunneling and Euclidean resonance. The above phenomena can be used for control of tunneling: in scanning tunneling microscopy, for selective destruction of chemical bonds, in nanostructures, etc.

PACS numbers: 74.25.Nf, 74.40.+k, 74.72.Hs


Tuesday, April 10th 2007
12:20 pm:
No seminar this week.
1:00 pm:
Space Physics Seminar in 236A Physics
Speaker: Professor Roberta Humphries, University of Minnesota
Subject: Hypergiant Stars: The Evidence for Episodic Mass Loss, Convective Activity and Magnetic Fields.

Wednesday, April 11th 2007
4:00 pm:
Speaker: Aharon Kapitulnik
Subject: Search for Gravity-like Forces at sub-mm distance
Refreshments served in Room 216 Physics at 3:30 p.m.

Recent theories of physics beyond the standard model have predicted deviations from Newtonian gravity at short distances. In order to test these theories, we have a built an apparatus that can measure attonewton-scale forces between small masses separated by distances on the order of 25 microns. A micromachined silicon cantilever was used as the force sensor, and its displacement was measured with a fiber interferometer. We have used our measurements to set bounds on the magnitude alpha and length scale lambda of Yukawa-type deviations from Newtonian gravity; our results presented here yield the best experimental
limit in the range of lambda between 5 and 50 microns. We also discuss initial results from new experiments in which substantial improvements are expected.

1. S.J. Smullin, A.A. Geraci, D.M. Weld, J. Chiaverini, S. Holms, and A. Kapitulnik, Phys. Rev. D 72, 122001-1-20 (2005).


Thursday, April 12th 2007
12:10 pm:
Speaker: Pete Mendygral and Liliya Williams, University of Minnesota
12:15 pm:
Speaker: Daniel Chung, University of Wisconsin
Subject: Cuscuton: A New Constraint System Applied to Modifying Gravity

A new class of constraint system applicable to continuous covariant field theories is explained. When coupled to gravity, it modifies the constraints of Einstein equations. Cosmological implications are also presented.

1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Aharon Kapitulnik, Stanford University
Subject: Polar Kerr Effect Measurements of Novel Superconductors: Evidence for Broken Time Reversal Symmetry in the Superconducting States

Strontium ruthenate Sr2RuO4 is an odd-parity superconductor, shown to exhibit p-wave pairing. Some of the possible p-wave states can further break time-reversal symmetry (TRS). However, unlike other known TRS breaking effects in solids, this case does not imply a "magnetic effect" since any such signal will be screened by the Meissner effect (except for surfaces, domain walls and imperfections). In the past two years, we have pursued a direct test of the broken time-reversal-symmetry in the bulk of Sr2RuO4 and other superconductors with potentially broken time reversal symmetry state, without relying on imperfections and defects by measuring the Polar Kerr effect (PKE). PKE is sensitive to TRS breaking since it measures the existence of an antisymmetric contribution to the real and imaginary parts of the frequency-dependent dielectric tensor, and such a contribution is necessarily absent if TRS is not broken in the material. In order to measure the very small static TRS-breaking effect in superconductors, we have developed a new PKE technique based on a fiber Sagnac interferometer with a zero-area Sagnac loop. Results on Sr2RuO4 as well as other unconventional superconductors will be shown.

1. Jing Xia, Maeno Yoshiteru, Peter T. Beyersdorf, M. M. Fejer,
Aharon Kapitulnik, Phys. Rev. Lett. 97 (2006),167002.

2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Todd Springer, University of Minnesota
Subject: Cosmological Black Hole Formation and the QCD Phase Transition

Friday, April 13th 2007
3:35 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Knut Olson, CTIO. NOAO
Subject: The Structure and Kinematics of the LMC.
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics
Subject: No Colloquium this week.

Monday, April 16th 2007
No seminar this week.

Tuesday, April 17th 2007
12:20 pm:
Speaker: Eric Garlid
Subject: The Spin Hall Effect in Fe/GaAs Heterostructures
1:00 pm:
Space Physics Seminar in 236A Physics
Speaker: Lei Dai, University of Minnesota
Subject: Hall conductivity in a collisionless plasma.

Wednesday, April 18th 2007
4:00 pm:
Speaker: Fran Bagenal, University of Colorado
Subject: Exploring the Giant Magnetosphere of Jupiter
Refreshments served in Room 216 Physics at 3:30 p.m.

Jupiter is a planet of superlatives: it is the most massive planet in the solar system, rotates the fastest, has the strongest magnetic field, and has the most massive satellite system of any planet. These unique properties lead to active volcanoes on Io, a ton per second of sulfur and oxygen being spewed out of the moon, a vast population of energetic plasma trapped in the planet's strong magnetic field, and intense auroral emissions in Jupiter's polar atmosphere. The giant magnetosphere of Jupiter has been explored by telescopes on Earth, Hubble Space Telescope, several spacecraft flying past the planet plus the Galileo spacecraft that spent seven years in orbit. This talk will discuss our current understanding of this huge, dynamic structure and present what we hope to learn from the New Horizons spacecraft as it flies down Jupiter's magnetotail on its way to Pluto (spring 2007) and from the Juno mission (launch due in 2011) that will skim over Jupiter's poles.


Thursday, April 19th 2007
12:10 pm:
Speaker: Shea Brown, University of Minnesota
12:15 pm:
Speaker: Joshua Elliott, McGill Univ./Univ. of Chicago
Subject: 3D N=1 SYM with a Chern-Simons term on the Lattice

I will discuss our formalism for implementing N=1 SYM on a 3D
lattice and our plans to test a conjecture by Witten - hep-th/9903005 - that SUSY is spontaneously broken for certain values of the Chern-Simons coupling.

1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Alex Kamenev, University of Minnesota
Subject: What is a Fermi-Luttinger liquid?
2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Philippe de Forcrand, ETH Zurich and CERN
Subject: The QCD Phase Diagram at Finite Temperature and Density

I review the progress towards the determination of the QCD phase diagram by lattice simulations, and the difficulties encountered.


Friday, April 20th 2007
3:35 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Sumner Starrfield, Arizona State University
Subject: The 2006 Oubturst of RS Oph - A Hot Flash on a Degenerate Dwarf
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

RS Oph was observed in outburst on February 12, 2006 and, for at least the fifth time in recorded history, reached naked eye visibility. RS Oph is a member of a class of stars called recurrent novae because their outbursts have been detected more than once. We jumped at the opportunity to observe this system both with the large number of satellites now in orbit and ground based facilities that had far superior detectors to those available for its last outburst in January 1985. This system has a white dwarf (probably massive) in a 455 day orbit around a cool giant. The giant is transferring hydrogen rich matter onto the white dwarf at a rate that is sufficient for an explosion every 20 years or so. In contrast, a classical nova binary system also contains a white dwarf star but the mass losing star is a low mass star (like the sun) in a few hour orbit around the white dwarf and the time between explosions may be as long as 100,000 years or more. I will report on the unprecedented data that we obtained with X-ray satellites such as Chandra and Swift plus discuss the possible relationship between RS Oph and Supernovae of Type Ia. These latter explosions are thought responsible for the iron group elements in the Solar System and are now being used to study the evolution of the Universe.

Speaker: Alan Beyerchen, Department of History, Ohio State University
Subject: Clausewitz and the Quest for a Science of War
Refreshments served in Room 216 Physics at 3:15 p.m.

There has long been a debate about the nature of war. It is well known that Carl von Clausewitz (1780-1831) and others at end of the 18th and beginning of the 19th centuries sought to found a "scientific" understanding of this phenomenon. It was an important and even urgent goal, given the protracted and devastating wars of the Revolutionary and Napoleonic eras. Yet it is also clear that, after a lifetime of experience and contemplation, Clausewitz concluded this was an impossible quest. In line with others of his time, what did Clausewitz think a science of war would entail? Why did he believe it could not be achieved? What was the best we could accomplish in the real world? Are his concerns still relevant today?


Monday, April 23rd 2007
Speaker: Taylor Childers
Subject: Preliminary data from the 1st and 2nd CREAM flights: Reaching the knee of the cosmic ray energy spectrum with a balloon experiment
Speaker: Igor Lerner, Birmingham University
Subject: Resonant Level in a Luttinger Liquid

Tuesday, April 24th 2007
12:20 pm:
Speaker: Charlie Blackwell, University of Minnesota
Subject: Effects of nanocrystalline inclusions on the electronic properties of thin film amorphous silicon
1:00 pm:
Space Physics Seminar in 236A Physics
Speaker: Prof. Doug Ernie, ECE Department, U of M
Subject: Plasma Induced Neutral Flows - Theory and Applications
1:30 pm:
Thesis Defense in Physics Room 435
Speaker: Xiaohua Lou
Subject: Electrical detection of spin transport in ferromagnet/semiconductor heterostructures

Wednesday, April 25th 2007
4:00 pm:
Speaker: Meigan Aronson, Brookhaven National Laboratory and Stony Brook University
Subject: Increasing Faculty Diversity: The Michigan Experience
Refreshments served in Room 216 Physics at 3:30 p.m.

A generation ago, few universities had faculties which reflected the gender and ethnic diversity of the US population. While these
differences have subsequently become less pronounced among social
science and humanity faculties, the composition of science and engineering faculties have been slower to diversify. In this talk I will discuss our efforts at the University of Michigan to improve recruiting and retention of women and minority faculty members. This undertaking is viewed as an institutional transformation, and involves both administrative initiatives, modifications of hiring and promotion policies, and as well faculty development and training. I will review progress so far, and discuss the future of these efforts in light of the Michigan Civil Rights Initiative.


Thursday, April 26th 2007
12:10 pm:
Speaker: Sebastian Hidalgo, University of Minnesota
Subject: Theoretical planetary mass spectra - a prediction for COROT
12:15 pm:
Speaker: Jim Cline, McGill University
Subject: Imprints of Tachyonic Preheating on the CMB
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Meigan Aronson, Brookhaven National Laboratory and Stony Brook University
Subject: Neutron scattering investigations of exchange biased Co/CoO core shell nanoparticles
2:30 pm:
Nuclear Physics Seminar in 435 Physics
No seminar this week.

Friday, April 27th 2007
3:35 pm:
Astrophysics Colloquium in 210 Physics
Subject: No Colloquium this week.
Subject: No Colloquium this week.

Monday, April 30th 2007
No Seminar this week.

Tuesday, May 1st 2007
12:20 pm:
No seminar this week.
1:00 pm:
Space Physics Seminar in 236A Physics
Speaker: Prof. Paul Kellogg, University of Minnesota
Subject: The in-situ plasma wave experiment on STEREO

Wednesday, May 2nd 2007
4:00 pm:
Speaker: Ivan Schuller, University of California-San Diego
Subject: Pathological Science
Refreshments served in Room 216 Physics at 3:30 p.m.

I describe and categorize instances in which scientific research
can be categorized as "pathological". Several of these have become "cause celebre" and have received recent extensive attention in the published media. Out of these I draw the 13 Schuller Rules for Pathological Science and describe useful ways in which to judge scientific research.


Thursday, May 3rd 2007
12:10 pm:
Speaker: Tea Temim and Yong Qian, University of Minnesota
1:00 pm:
Thesis Defense in Physics Room 435
Speaker: Ben Speakman
Subject: Atmospheric Electron Neutrinos in the MINOS Far Detector
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Ivan Schuller, University of California-San Diego
Subject: Superconducting-Magnetic Hybrids
2:30 pm:
Nuclear Physics Seminar in 435 Physics
No Seminar this week.

Friday, May 4th 2007
09:00 am:
Subject: Bio '07: Physics Inspired by Biology
May 4 - 6, 2007, www.ftpi.umn.edu/bio07/
3:35 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Rogier Windhorst, Arizona State University
Subject: The James Webb Space Telescope: How can it measure First Light, Reionization, and Galaxy Assembly?
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

The capabilities of the 6.5 meter James Webb Space Telescope (JWST) --- slated for launch to a halo L2 orbit in 2013 --- are reviewed, including the considerations to make this an optimized infrared telescope that can deploy automatically in space. The main science themes of this telescope are to measure First Light, Reionization, Galaxy Assembly, as well as the process of Star-formation and the origin of Planetary Systems. The talk will outline how the JWST will go about measuring First Light, Reionization, and Galaxy Assembly, building on lessons learned from the Hubble Space Telescope. In detail, JWST will map the epoch of First light through Pop III star clusters at redshifts z=8--20, and its transition to the first Pop II stars in dwarf galaxies that likely finished cosmic reionization at redshifts z=6-7. I will show what deep JWST images may look like compared to the Hubble UltraDeep Field, and what nearby galaxies observed in their restframe UV--optical light would look like to JWST at very high redshifts. I'll demonstrate an interactive web-tool that lets the user zoom 3-D into the Hubble UltraDeep Field --- and beyond into the epoch of First Light --- with all galaxy
images sorted versus redshift. Time permitting, I will discuss issues of the natural confusion limit as they may apply to JWST, and algorithms that may be needed to automatically detect objects in crowded ultradeep JWST fields.

Speaker: Jessica Wang
Subject: Social Science and the American State: From the Social Survey to the New Deal
Refreshments served in Room 216 Physics at 3:15 p.m.

The fusion of social science and state power represents a dominant theme in the history of the modern American state. The meaning of the "science" in social science, however, has changed markedly throughout the decades, from the qualitative traditions of the early twentieth century to the scientism of the post-World War II period. The combination of social investigation and advocacy as represented in the various social survey movements of the 1900s and 1910s, in which the scientific identification of social facts did not rule out subjectivity and political engagement, persisted well into the New Deal years. This paper will examine the path from the social survey movement, to reformist currents in legal thought in the 1910s and 1920s, to securities regulation within the Securities and Exchange Commission in the 1930s in order to explore the vitality of qualitative forms of social inquiry in the early decades of the twentieth century. Although advocates of scientific rigor strongly criticized New Deal methods, in the political context of the 1930s, the qualitative search for social facts nonetheless allowed the state to "see" new areas of national economic life and provided powerful justification and means for trying to regulate a chaotic, dysfunctional marketplace.


Monday, May 7th 2007
No seminar this week.

Tuesday, May 8th 2007
12:20 pm:
No seminar this week.
1:00 pm:
Space Physics Seminar in 236A Physics
No seminar this week.

Wednesday, May 9th 2007
4:00 pm:
This colloquium will resume in the fall.

Thursday, May 10th 2007
12:10 pm:
This seminar will resume in the fall.
12:15 pm:
No seminar this week
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Jianping Wang, University of Minnesota
Subject: New magnetic nanoparticles and spintronic devices
2:30 pm:
Nuclear Physics Seminar in 435 Physics
This seminar will resume in the fall.

Friday, May 11th 2007
3:35 pm:
Astrophysics Colloquium in 210 Physics
This colloquium will resume in the fall.
This colloquium will resume in the fall.

Tuesday, May 29th 2007
1:00 pm:
Ph. D Thesis Defense in Physics Room 170
Speaker: Hyuk-Jae Jang
Subject: Magnetization Reversal Study on Patterned Ferromagnetic and Exchange-Biased Systems
2:00 pm:
Physics Seminar in Physics 166
Speaker: Vladimir Rekovic, University of New Mexico
Subject: Search for Chargino/Neutralino Production Using Low Pt Di-Muon Triggers of CDF on Tevatron

Thursday, May 31st 2007
12:15 pm:
Speaker: Martin Reiris (MIT)
Subject: Large scale behavior of cosmological models
Please note location.

In the first part of the talk I will describe the large scale behavior of general cosmological solutions under a priori bounds of the space time curvature and show how, at large scales, these universes evolve toward "geometrized ones". In the second part I will concentrate on a more accurate and predictive description of the evolution, paying quantitative attention to the gravitational and material energy an their contributions in the universe deceleration. I will do so by studying a Friedman-Lemaitre equation for the volume-averaged cosmological parameters. These results in particular extend the large scale and long time behavior of the standard compact Friedman-Lemaitre-Robertson-Walker models to general non-homogeneous and non-isotropic cosmologies.


Tuesday, June 5th 2007
Subject: The Dark Side of the Universe 2007
June 5-10, 2007. For more information: http://www.ftpi.umn.edu/dsu07

Wednesday, June 6th 2007
4:00 pm:
Speaker: Dr. Sergey Y. Tetin, Abbott Laboratories
Subject: Antigenic Epitopes on Peptides and Proteins

Antigenic Epitopes on Peptides and Proteins
by Sergey Y. Tetin (Core R&D, Diagnostic Division, Abbott)
An antigenic epitope is the area on protein surface that interacts with the complementary area (paratope) on the surface of the antibody binding domains. It participates in electrostatic interactions, hydrophobic interactions and hydrogen bonding with the antibody and also contains residues responsible for the correct geometry of the surface, its malleability and structural dynamics. There are also buried "second sphere" residues that carry a strong supporting role. In this presentation I will discuss various experimental approaches including combinations of fluorescence based techniques, site-directed mutagenesis and protein NMR that can be used for epitope identification and structure-function analysis.


Thursday, June 14th 2007
12:15 pm:
Speaker: Jean-Francois Dufaux, University of Toronto
Subject: Stochastic gravitational wave background from preheating after inflation

The origin of matter in the universe from a decaying inflaton field is a basic feature of the inflationary paradigm. In many models, the first stage of this process, called preheating, is dominated by an explosive and non-perturbative production of highly inhomogeneous, non-thermal field fluctuations. These act in particular as a classical source for gravitational radiation.

In this talk, I will first review some aspects of preheating and of the subsequent evolution of the inflaton decay products towards thermal equilibrium. I will then discuss the computation of the resulting background of gravitational waves. The corresponding spectrum has a higher amplitude than the one generated during inflation, and it may fall into the range accessible for direct detection experiments (LIGO/VIRGO or BBO) if inflation occurs at a low enough energy scale. The discovery of such a background would open a new observational window into the dynamics of the very early universe.


Friday, June 15th 2007
2:00 pm:
Thesis Defense in Physics Room 435
Speaker: Weimin Deng
Subject: Studies of Wall-Film Superfluidity in 3He/4He Mixtures

The main purpose of the project is to study the onset and growth of superfluidity in a thin 3He/4He mixture film (wall film) near the surface of a container. The main experimental technique is to use a thin quartz crystal immersed in a liquid 3He/4He mixture, vibrating in a transverse mode at frequencies near 25M, 35M and 105MHz. By measuring the resonant frequency and peak amplitude as a function of temperature from 0.5 K to 1.5 K, the acoustic impedance of the mixture can be obtained. The experimental results can be used to study the superfluidity properties of the wall film. A capacitor in the experimental cell has been used to measure the dielectric constant of the mixtures for reference. Experiments have been conducted having mixtures with 3He mole fractions of 0.750, 0.705, 0.6735 and 0.644. Results are analyzed based on dynamic Kosterlitz-Thouless theory and local continuum theory. The analysis shows that the wall film has a dynamic Kosterlitz-Thouless type superfluid transition and can be treated as a quasi-2D system. The results of simulation based on a modified hydrodynamic model show good agreement with the experimental results.


Monday, June 25th 2007
1:30 pm:
Thesis Defense in Physics 236A
Speaker: Peanut McCoy
Subject: Surface structures and reentrant transitions in tilted smectic phases of chiral liquid crystals

Using a series of binary mixtures, we have determined the dependence of the phase sequence upon doping for two compounds with similar chemical structures but inverted phase sequences in one of the pure compounds. The SmC_FI2 phase is favored over the SmC phase on both sides of the mixing phase diagram. In two of these binary mixtures, we observed a reentrant SmC_FI2-SmC-SmC_FI2 transition. Resonant x-ray diffraction identifies the SmC_FI2 phase below SmC and null transmission ellipsometry shows that the phases on either side of SmC have the same structure. The reentrant transition only occurs in thin films.


Tuesday, July 10th 2007
10:15 am:
THESIS DEFENSE in Physics, Room 358B
Speaker: Zengqiang (John) Liu
Subject: Optical and resonant x-ray studies of chiral smectic-C liquid crystals structures and transitions

Applying resonant x-ray diffraction and differential optical reflectivity, we determined that the phase transition between the SmC phase and SmC_alpha phase is a first-order transition that ends at a critical point. We reported observation of the critical point in binary mixtures of homologous liquid crystal compounds. We also determined the order parameter and two critical exponents associated with the transition. Comparison with the mean-field calculations suggested that long-range interactions are present in the critical region of the transition. With the same experimental probes, we studied the pitch evolution with temperature in the SmC_alpha phase near 4 layers. A theoretical model developed by Olson et al. predicted that the SmC_FI2 phase intervenes in the Sm_alpha phase where the pitch is near 4 layers. Our observation showed that the pitch in the SmC_alpha phase decreased continuously and strictly across 4 layers upon cooling while the SmC_FI2 phase appeared at a lower temperature than the SmC_alpha phase. We also found linear relation between the pitch and the layer spacing, which was not observed in other systems. Comparison with a newer theoretical model by Hameneh and Taylor suggested the presence of long-rang interactions in smectic liquid crystals.


Tuesday, July 24th 2007
12:00 pm:
Thesis Defense in Physics 435
Speaker: Roman Lutchyn
Subject: Kinetics of Superconducting Quantum Circuits

Superconducting circuits exhibit quantum properties on a
macroscopic scale, and are natural candidates for solid state
quantum computing. Their low-energy physics can be described in
terms of the phase of the order parameter, a single collective
degree of freedom associated with billions of coherently paired
electrons. In practice, however, on top of the superfluid
condensate there are single-particle excitations (quasiparticles)
with a continuous energy spectrum; the quasiparticles are coupled
to the phase degree of freedom. The presence of quasiparticles in
the system sets serious constraints on the performance of
superconducting charge qubits. In the thesis, I study the
kinetics of superconducting quantum circuits, and discuss the
fundamental limitations on the energy and phase relaxation times
in the presence of quasiparticles.


Monday, August 6th 2007
12:15 pm:
Johns Hopkins University in Physics 435
Speaker: Takemichi Okui
Subject: ``The 't Hooft Model As A Hologram.''

Wednesday, August 15th 2007
1:00 pm:
PhD Thesis Defense in Physics 133
Speaker: Sean O'Neill
Subject: Three-Dimensional Magnetohydrodynamic Simulations of Interactions Between Radio Galaxies and Their Environments

Thursday, August 16th 2007
10:00 am:
PhD Thesis Defense in Physics 435
Speaker: Rob Compton
Subject: Pinning and Dynamics of a Magnetic Vortex Core
2:00 pm:
PhD Thesis Defense in Physics 435
Speaker: Alexey Kobrinskii
Subject: Exchange bias in epitaxial manganite bilayers

Tuesday, August 28th 2007
2:30 pm:
HEP Seminar in Physics 435
Speaker: Maury Goodman (Argonne National Lab)
Subject: The Double Chooz Experiment

Monday, September 3rd 2007

Tuesday, September 4th 2007

Thursday, September 6th 2007
12:15 pm:
Speaker: Takemichi Okui, Johns Hopkins University
Subject: The 't Hooft Model As A Hologram
4:00 pm:
Electrical Engineering Colloquium in 3-210 EECS Building
Speaker: M. Mansuripur, University. Arizona
Subject: Radiation Pressure and the Momentum of Light in Dielectric Media
Please note: There is no Condensed Matter Seminar today, please attend EEC event.

Friday, September 7th 2007
2:30 pm:

Monday, September 10th 2007
Speaker: Pearl Sandick
Subject: Neutralino Dark Matter from GUT-less SUSY

Tuesday, September 11th 2007
12:20 pm:
Speaker: Andrew Thompson
Subject: Measuring Distances, Orientation and Structural Dynamics in Muscle Proteins Using Electron Paramagnetic Resonance
1:00 pm:
Space Physics Seminar in 236A Physics
No Seminar This Week

Wednesday, September 12th 2007
4:00 pm:
Speaker: Juan Collar, Enrico Fermi Institute
Subject: Something Old, Something New
Refreshments served in Room 216 Physics at 3:30 p.m.

We'll discuss two initiatives in astroparticle and neutrino physics at the University of Chicago, both sharing in common the revival and revision of old technologies to address new experimental challenges. COUPP employs ultra-clean heavy liquid bubble chambers to search for WIMP dark matter. COGENT aims at the detection of faint (sub-keV) signals in detectors large enough to allow searches for rare processes, using recently developed p-type point contact Germanium detectors.


Thursday, September 13th 2007
12:10 pm:
Speaker: Andrew Helton and Terry Jones. both from the University of Minnesota
12:15 pm:
Speaker: Andreas Karch, University of Washington
Subject: "The N=4 super Yang-Mills plasma"
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Joe Skinner, University of Minnesota
Subject: Fluorescence Fluctuation Spectroscopy Extended Beyond Diffusion: Flow and Immobilization
This talk is also his final Ph.D. Thesis

Fluorescence fluctuation spectroscopy (FFS) extracts information about the transport and assembly of proteins from the signal fluctuations of fluorescently labeled biomolecules diffusing through a small optical observation volume. FFS was mainly developed for studies in aqueous solution, but has found an increasing number of applications measuring diffusion and protein association directly inside living cells. However, unlike in solution, proteins in cells are not only undergoing random diffusion, but also exist in immobile form when bound to large structures, such as the chromosome. The presence of immobile fluorophores in the observation volume presents new challenges for FFS that need to be addressed to allow a quantitative interpretation of cellular experiments. Two extreme cases of immobilization exist. The first is very sparse immobilization requiring the ability to detect single immobile molecules. The second is uniform distribution of immobilized molecules creating background fluorescence which biases the interpretation of fluctuation data. I present new approaches that extend FFS in order to quantify systems which contain these two types of immobilization. The first approach, based on periodic scanning of the laser beam, is also capable of characterizing hydrodynamic flow, which will be experimentally demonstrated. In addition, I will show that immobilization, at both extremes, can be quantitatively differentiated from mobile molecules by the modified FFS techniques. Finally, I will demonstrate the robustness of the methods by applying them to measure proteins in living cells.

2:30 pm:
Nuclear Physics Seminar in 435 Physics
No seminar this week.

Friday, September 14th 2007
2:30 pm:
FTPI Seminar in Physics 435
Speaker: Alon Faraggi, University of Liverpool
Subject: "Novel Symmetries in Heterotic Vacua"
2:30 pm:
Speaker: Priscilla Cushman
Subject: Cryogenic Dark Matter Search
This is intended to introduce research projects within the department to new graduate students.

We are looking for WIMPs in the Soudan Underground Lab in Northern Minnesota using ultra-cold solid state detectors. The next step, SuperCDMS, will be installed in a mine in Canada that is even deeper. Data from our last run should be announced in late October. I'll explain our techniques and what it is like to play pingpong half a mile underground.

3:00 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Michael Kelley, U. Central Florida
Subject: The Size Distribution and Surface Properties of Comet Nuclei
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

Comet nuclei coalesced from the refractories and ices present in the outer-planets region of the proto-solar system. The interiors of comets have remained at low temperatures in the Kuiper Belt or Oort Cloud that over the past 4.5 Gyr of solar system history. Thus, comets are time capsules -- records of the thermal, chemical, and dynamical environment of the protoplanetary disk. However, comets are not wholly pristine and before we can definitively link their dust and ice properties to the conditions of the early solar system, we must understand their ensemble histories. To that end, we compare the physical properties of comet nuclei to related planetesimals to probe the evolution of small bodies in the solar system. Jupiter-family comets are well-suited to the study of comet surfaces because their nuclei are more accessible than those of the long-period comets. We have an optical/mid-infrared survey of 100 Jupiter-family comets (nearly one-third of all known JFCs) designed to measure their sizes and albedos. We use our completed mid-infrared survey to derive a new and independent estimate of the current Jupiter-family comet size distribution. The optical component of the survey is in progress. The albedo and size distributions are important characteristics in comparisons of comets to their dynamically related bodies: Trojans, Centaurs, and transneptunian objects.

Speaker: Daniel Kennefick, Department of Physics, University of Arkansas
Subject: Traveling at the Speed of Thought: Theorists Attempt to Prove the Existence of Gravitational Waves
Refreshments served in Room 216 Physics at 3:15 p.m.

Gravitational Waves represent a nearly unique instance of unfinished business in the history of modern physics. One of the slew of novel concepts which arose in the revolutionary period of the early 20th century, they retained their place in the new physics for nearly a century in the total absence of any kind of experimental confirmation. It was only natural, therefore, that their theoretical development was marked by repeated debate over whether they really existed, or played any kind of role in astrophysical systems such as binary stars. The course of these controversies (including the quadrupole formula controversy) is briefly recounted, and it is argued that both confidence in and skepticism of their existence were nourished by the nature of the analogy with electromagnetic waves which enabled their conceptualization in the first place.


Monday, September 17th 2007
Speaker: Matthew Sexton, University of Minnesota
Subject: "Nonperturbative Decay of Supersymmetric Flat Directions During Preheating with "realistic" Gauged Lagrangians"
3:00 pm:
Thesis Defense in Walter Library, Room 402
Speaker: Dale Jackson, Dept. of Astronomy
Subject: Dust at Low Metallicity: A Spitzer Survey of Local Group Dwarf Galaxies
Speaker: Dr. Matthias Bode, Argonne National Laboratory
Subject: Imaging Magnetic Surfaces with Atomic Resolution

Fueled by the ever increasing data density in magnetic storage and the need for a better understanding of the physical properties of magnetic nanostructures there exists a strong demand for high-resolution magnetically sensitive microscopy techniques. The technique with the highest available resolution is spin-polarized scanning tunneling microscopy (SP-STM) which combines the atomic-resolution capability of conventional STMs with spin-sensitivity. Beyond the investigation of ferromagnetic surfaces, thin films, and epitaxial nanostructures with unforeseen precision, it also allows the achievement of a long standing dream, i.e. the real space imaging of atomic spins in antiferromagnetic surfaces. The lecture addresses a wide variety of phenomena in surface magnetism which in most cases could not be imaged directly before the advent of SP-STM. After starting with a brief introduction to basics of the contrast mechanism, recent major achievements will be presented, like the direct obser-vation of the atomic spin structure of domain walls in antiferromagnets and the visualization of thermally driven switching events in superparamagnetic particles consisting of a few hundreds atoms only. To conclude the lecture, recently observed complex spin structures containing 15 or more atoms will be presented.


Tuesday, September 18th 2007
12:20 pm:
Speaker: Alex Levchenko
Subject: Coulomb Drag Resistance and Zero Temperature
1:25 pm:
Space Physics Seminar in 143 Physics
Speaker: Cynthia Cattell, University of Minnesota
Subject: STEREO observations of large amplitude whistler wave in the Van Allen belts: Implications for electron energization
2:30 pm:
Speaker: Kregg Arms
Subject: New results from the MINOS experiment

Wednesday, September 19th 2007
4:00 pm:
Speaker: Nigel Cooper, Cambridge University
Subject: Spinning Topological Phases out of Cold Atomic Gases
Refreshments served in Room 216 Physics at 3:30 p.m.

One of the most remarkable properties of a superfluid is its response to rotation. The formation of an array of quantized vortex lines is a dramatic manifestation of the macroscopic quantum nature of the superfluid. But what happens if one spins the superfluid so rapidly that the vortex lines become very closely spaced? I shall describe theoretical predictions of the appearance of novel and exotic phases in cold atomic gases at high vortex densities. These include topological phases exhibiting so-called "non-abelian" exchange statistics, with the potential to support universal topological quantum computation.


Thursday, September 20th 2007
12:00 pm:
Speaker: Dr. Randy Jokipii, University of Arizona
Subject: Implications of Recent Remote and In Situ Observations of the Outer Heliosphere and the Local Interstellar Medium

Recent in situ observations from the Voyager spacecraft and remote observations from SOHO have both increased our understanding of the interaction of the solar wind with the interstellar medium and provided new information about the very local interstellar medium. Voyage data have revealed a very dynamic, blunt solar-wind terminations shock. The combination of Voyager and remote sensing observations of neutral atoms from the SOHO spacecraft have provided the first measurements of the very local interstellar magnetic field. The direction of this local field is quite different from previous measurements which averaged over parsec scales. The implications of these data will be discussed.

12:15 pm:
Speaker: Erich Poppitz, University of Toronto
Subject: "Lattice chirality and the decoupling of mirror fermions"
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Nigel Cooper, Cambridge
Subject: Pumping and Probing Nuclear Spins in Semiconductor Quantum Wires
2:30 pm:
Nuclear Physics Seminar in 435 Physics
No Seminar This Week

Friday, September 21st 2007
2:30 pm:
Speaker: Vuk Mandic
Subject: Searching for Stochastic Gravitational-Wave Background with LIGO
This is intended to introduce research projects within the department to new graduate students.

Laser Interferometer Gravitational-wave Observatory (LIGO) has built three multi-km interferometers designed to search for gravitational waves. LIGO has reached its design sensitivity, and the first year-long run is expected to end on October 1, 2007. The data from this run will be thoroughly searched in the coming years for different sources of gravitational radiation. At the same time, detector upgrades will be commissioned with the goal of improving interferometer sensitivity by a factor of 10 and of increasing the sensitive frequency band of the interferometers. We will review the current status of LIGO and the expected future improvements, as well as the most recent results of the search for stochastic gravitational-wave background.

3:00 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Jan-Uwe Ness, Arizona State University
Subject: The X-ray view of Classical Novae
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

Classical Novae are thermonuclear explosions that occur in stellar binary systems consisting of a solar-like star and a so-called White Dwarf, an old stellar object that has shrunk to a degree of compactness that it consists only of degenerate matter after having lost all of its hydrogen. Mass transfer from the solar-like star to the White Dwarf provides new hydrogen-rich material that will ignite a nuclear fusion reaction chain. While this principle is always the same, all Classical Novae observed so far have been quite different in their evolution. X-ray observations reveal central pieces of information as they allow insights into the hottest processes. I will give a description of the typical evolution of Classical Novae and show examples of X-ray spectra during the different phases of evolution. A more detailed view also illustrates how different the evolution can be when different system parameters are given.

Speaker: Staffan Mueller-Wille, The ESRC Centre for Genomics in Society (EGENIS), Univ. of Exeter. Cosponsored by the Minnesota Center for Philosophy of Science
Subject: Fleck and Kuhn on Scientific Change
Refreshments served in Room 216 Physics at 3:15 p.m.

Ludvik Fleck is often quoted as one of the inspirations for Thomas S. Kuhn's Structure of Scientific Revolutions. I will argue that there were some fundamental differences between their models of scientific change. While Kuhn was concerned with the production of knowledge within local communities, Fleck focussed on the translation of knowledge among such communities.


Monday, September 24th 2007
Speaker: Yong-Zhong Qian
Subject: "Chemical Evolution of Heavy Elements: Implications for Stellar Sources"

Tuesday, September 25th 2007
12:20 pm:
Speaker: Greg McKusky
Subject: Differential Conductance Measurements of Magnetic Tunnel Junctions
1:00 pm:
Space Physics Seminar in 143 Physics
No Seminar This Week
2:30 pm:
No seminar this week.

Wednesday, September 26th 2007
4:00 pm:
Speaker: Susan Coppersmith
Subject: Quantum computing: Opportunities and challenges
Refreshments served in Room 216 Physics at 3:30 p.m.

Quantum-mechanical phenomena such as quantum coherence, interference, nonlocality, and entanglement can be exploited to build new electronic devices and systems that differ fundamentally from current ones. Achieving these advances requires fundamental advances in a variety of disciplines as well as close interdisciplinary collaboration. This talk will discuss how close cooperation between researchers in different disciplines has enabled substantial new progress in the development of quantum dots in silicon/silicon-germanium heterostructures for quantum computing applications.


Thursday, September 27th 2007
12:10 pm:
Speaker: Dan Polsgrove and Larry Rudnick
12:15 pm:
Speaker: Dan Hooper, Fermilab
Subject: "Evidence of Dark Matter Annihilations in the WMAP Sky"
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Sue Coppersmith, University of Wisconsin
Subject: Computational complexity and complex systems

In this talk I will discuss how physics concepts can be useful for understanding issues arising in the field of computational complexity, the study of the amount of computational resources needed to solve different problems. In particular, I will show how a renormalization group construction similar to those used to provide insight into phase transitions in physical systems can provide new insight into how to distinguish computational problems that can and cannot be solved efficiently.

2:30 pm:
Nuclear Physics Seminar in 435 Physics
No seminar this week.

Friday, September 28th 2007
2:30 pm:
Speaker: James Kakalios
Subject: Conductance Fluctuations: From Amorphous Silicon to the Cerebral Cortex
This is intended to introduce research projects within the department to new graduate students.
3:00 pm:
Astrophysics Colloquium in 210 Physics
Subject: No colloquium this week.
Speaker: Kenneth Lipartito, Department of History, Florida International University
Subject: It's Not Rocket Science: Operations Engineering and Human Space Flight
Refreshments served in Room 216 Physics at 3:15 p.m.

Most images of spaceflight stress the flight and living and working in space. Few give attention to the work that goes on before liftoff, to the ground operations that take place at the Kennedy Space Center. In contrast to the emphasis given systems engineering and program management by scholars such as Thomas Hughes, this paper will explore the operational side of the technology of space flight.

Questioning the highly rational view of management structures and the designed centered logic of systems engineering, I argue that significant new knowledge is generated at the operational level. Differences in the culture of the operations and design communities have, however, obscured the importance of hands on learning and the highly innovative and even experimental nature of operational work. The Challenger and Columbia accidents and the failure of the space shuttle to live up to its promises reflect the subordination of operations and the overly abstract systems engineering and management structures of the space program.


Monday, October 1st 2007
Speaker: Shaul Hanany, University of Minnesota
Subject: "Science and Politics of a CMB polarization satellite"

Tuesday, October 2nd 2007
12:20 pm:
Speaker: Craig Zaspel University of Montana–Western
Subject: Spin Dynamics from a Spin-Polarized Current in Vortex State Magnetic Disks
2:30 pm:
Speaker: Alexander Scott, University of Minnesota
Subject: Measuring Quantum Correlations in Entangled D0-D0bar Decays at CLEO-c

Wednesday, October 3rd 2007
4:00 pm:
Speaker: Leo P. Kadanoff
Subject: The Good, the Bad and the Awful - Scientific Simulation and Prediction
Refreshments served in Room 216 Physics at 3:30 p.m.

Worthwhile computer simulations are done to explore uncharted territory, resolve a well-posed scientific or technical question, or to make a design choice. Some excellent work is reviewed. Some less happy stories are recounted. I then concentrate my attention upon astrophysical simulations, showing how they can explore possible scenarios for stellar explosions.


Thursday, October 4th 2007
12:10 pm:
Speaker: Paul Edmon and Chuck Woodward, University of Minnesota
12:15 pm:
Speaker: Shufang Su, University of Arizona
Subject: Left-Right Twin Higgs Models: Collider Phenomenology and Dark Matter Implication
1:25 pm:
Condensed Matter Seminar in 210 Physics
No Condensed Matter Seminar today. Attendance at the Meisel Lecture at 4:45 by Leo Kadanoff in Room 150 is recommended.
2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Scott Bowman, University of Minnesota
Speaker: Leo P. Kadanoff
Subject: Making a Splash; Breaking a Neck: The Development of Complexity in Physical Systems

The fundamental laws of physics are very simple. They can be written on the top half of an ordinary piece of paper. The world about us is very complex. Whole libraries hardly serve to describe it. Indeed, any living organism exhibits a degree of complexity quite beyond the capacity of our libraries. This complexity has led some thinkers to suggest that living things are not the outcome of physical law but instead the creation of a (super)-intelligent designer.

In this talk, we examine the development of complexity in fluid flow. Examples include splashing water, necking of fluids, swirls in heated gases, and jets thrown up from beds of sand. We watch complexity develop in front of our eyes. Mostly, we are able to understand and explain what we are seeing. We do our work by following a succession of very specific situations. In following these specific problems, we soon get to broader issues: predictability and chaos, mechanisms for the generation of complexity and of simple laws, and finally the question of whether there is a natural tendency toward the formation of complex 'machines'.


Friday, October 5th 2007
2:30 pm:
Speaker: Marco Peloso
Subject: Cosmological Inflation
This is intended to introduce research projects within the department to new graduate students.
3:00 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. David Ciardi, Caltech
Subject: A Search for Dust in the Habitable Zones Around Solar-like Stars
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

As part of a program to search for and characterize the presence of warm dust in the habitable zones around nearby solar like stars, we have search for dust within a few AU of the central stars. We have observed 152 FGKM stars with the Spitzer short-low and long-low IRS modules, and using the FLUOR instrument on the CHARA interferometer, we have observed the main sequence A stars beta Leo and zeta Lep, which are known to have a debris disk. I will present an overview of our results.

Speaker: Michael Weisberg, Department of Philosophy, University of Pennsylvania. Cosponsored by the Minnesota Center for Philosophy of Science
Subject: Three Kinds of Idealization
Refreshments served in Room 216 Physics at 3:15 p.m.

Philosophers of science increasingly recognize the importance of idealization, yet there is little consensus on some of the most basic questions about idealization, or even the best characterization of the practice. Despite this high degree of variation, some consensus has clustered around three types of positions, or three kinds of idealization. I will argue that all three kinds of idealization play important roles in scientific research traditions. There is no single purpose for idealization and hence there is not a single set of rules that theorists ought to follow when idealizing. While all three kinds of idealization can be found in scientific practice, they share enough in common that they can be characterized and studied in a unified way. The key is to focus not just on the practice and products of idealization, but on the goals governing and guiding it. I call these goals the representational ideals of theorizing and although they vary between the three kinds of idealization, attending to them gives a more unified picture of the practice.


Monday, October 8th 2007
Speaker: Keith Olive, University of Minnesota

Tuesday, October 9th 2007
12:20 pm:
Speaker: Masaya Nishioka
Subject: Magnetoresistance of Graphene Spin Valves
1:00 pm:
Space Physics Seminar in 143 Physics
Speaker: Professor Gordon Rostoker, University of Alberta, Edmonton
Subject: Substorms: the Evolution of a Concept
2:30 pm:
Speaker: Oleg Kamaev, Center for Accelerator and Particle Physics, Illinois Institute of Technology
Subject: Rare nonleptonic decays of the Omega hyperon: measurement of the branching ratios for Omega -> Xi*(1530) pi and Omega -> Xi pi pi

Wednesday, October 10th 2007
4:00 pm:
Speaker: Bonnie Fleming
Subject: Unexpected Results from MiniBooNE
Refreshments served in Room 216 Physics at 3:30 p.m.

The MiniBooNE neutrino oscillation experiment at Fermilab has reported first results ruling out a two neutrino oscillation interpretation of the LSND signal. The LSND experiment observed electron anti-neutrino appearance in a muon anti-neutrino beam. Taken with other evidence for neutrino oscillations, the LSND measurement suggests the existence of physics beyond the standard model in the neutrino sector. MiniBooNE has performed two independent and blind oscillation searches for electron neutrino appearance in a muon neutrino beam. In both, analysis selections and fitting procedures were determined before candidate electron neutrino events were examined. While MiniBooNE did not observe oscillations as expected in the analysis region, an excess of events was observed at low energy. There are a number of models suggesting these events could signal new physics. Ongoing studies to understand these events will be presented. A follow-on experiment to address this low energy excess will be described.


Thursday, October 11th 2007
12:10 pm:
Speaker: Dan Weisz and Liliya Williams, University of Minnesota
12:15 pm:
Speaker: Raymond Bishop, University of Manchester, University of Minnesota
Subject: "The Hamiltonian Lattice: Towards a Many-Body Treatment of SU(N) Gauge Theory"
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Matteo Cococcioni, Department of Chemical Engineering and Materials Science, University of Minnesota
Subject: Improved numerical methods for transition-metal compounds

Hubbard U-corrected LDA or GGA have proven very effective in describing several systems characterized by strongly localized electronic states for which standard (approximate) DFT functionals fail. In this talk I will present our scheme to evaluate the effective electronic interaction of the "+U" functional in a fully consistent way using linear-response theory. The successful application of this approach to the study of several transition-metal compounds will be discussed presenting the improvements in the description of their structural, electronic, chemical and electro-chemical properties. Examples will include minerals in the Earth's interior [1], cathode candidate materials for lithium-ion batteries [2] and catalytic reactions on molecules [3,4]. [1] M. Cococcioni and S. de Gironcoli, PRB (2005). [2] F. Zhou, M. Cococcioni, A. C. Marianetti, D. Morgan and G. Ceder, PRB (2004).

2:30 pm:
Nuclear Physics Seminar in 435 Physics
No seminar this week.

Friday, October 12th 2007
2:30 pm:
Speaker: Joachim Mueller
Subject: Fluorescence Fluctuation Spectroscopy of Biological Systems: What optical noise can teach us about proteins, cells and viruses?
This is intended to introduce research projects within the department to new graduate students.

Fluorescence Fluctuation Spectroscopy of Biological Systems: What optical noise can teach us about proteins, cells and viruses?

Every cellular process involves a complex network of protein interactions. The rules and design of these networks are currently poorly understood. It is our goal to directly visualize these interaction networks on the molecular level to contribute to the physical and biological understanding of living systems. We exploit optical signal fluctuations originating from single protein molecules to learn about the assembly, transport, and interaction of biomolecules. I’ll explain the technique and discuss applications ranging from gene regulation to the assembly of the HIV virus.

3:00 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Jason Harris, Steward Observatory
Subject: Magellanic Mystery Tour
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

As the nearest actively star-forming galaxies, the Magellanic Clouds offer a unique opportunity to study the physical processes that drive galaxy evolution. Years of effort have produced great strides in our understanding of these galaxies, and with comprehensive surveys of the Clouds in both optical and infrared bands coming online, it is truly an exciting time to be a Magellanic researcher. However, the Clouds don't give up their secrets easily, and many fundamental aspects of their nature remain shrouded in mystery. I will present some of these mysteries, and the present and future lines of research which will lead to their resolution.

No Colloquium This Week

Monday, October 15th 2007
Speaker: Larry Rudnick
Subject: The Square Kilometer Array and the Early Universe

Tuesday, October 16th 2007
12:20 pm:
No Seminar This Week
1:00 pm:
Space Physics Seminar in 143 Physics
Speaker: Ed Smith, Jet Propulsion Lab, NASA
Subject: The Heliospheric Plasma Sheet: Structure and Dynamics

The Heliospheric Current Sheet (HCS) separating magnetic fields from the Sun’s north and south magnetic poles is surrounded by the Heliospheric Plasma Sheet (HPS). The current sheet is usually identified as an abrupt reversal in field polarity but also by a reversal in flow direction of the electron heat flux. The plasma sheet is identified as a decrease in field strength (B) and a simultaneous increase in plasma density (n) or by an increase in plasma beta or entropy.

A fundamental aspect of HCS- HPS structure is their thicknesses and how they vary with radial distance. Ulysses observations provided an opportunity to determine these thicknesses at 3 and 5 AU during solar minimum and to then compare them with the thicknesses at 1 AU using ACE data. Surprisingly, HCS thickness is found to decrease with distance whereas HPS thickness increases. These results will be presented along with a discussion of the HCS-HPS identifications and their relation to heat flux.

The Ulysses data near 5 AU also provided an opportunity to investigate the dynamics of the HPS, i.e., the presence or absence of waves or turbulence. Observations of the HPS near 5 AU are advantageous because the spacecraft spends longer intervals inside the thicker plasma sheet. Simultaneous magnetic field and plasma data were analyzed, the resolution of the plasma analyzer limiting the periods under investigation to > 10 minutes. The diagnosis involved distinguishing between various possibilities including non-propagating structures such as mirror modes. Comparison of changes in magnetic field and solar wind velocity components show that the dominant mode is not Alfvenic but involves the anti-correlations between B and n. Therefore, a subsequent analysis was based on relations between magnetic pressure, thermal or kinetic pressure and total pressure that distinguish between the various possibilities. In the examples analyzed, the fluctuations are dominated by the slow magnetosonic mode, an interesting result since slow mode waves are not commonly identified in the solar wind.

2:30 pm:
Speaker: Bob Zwaska, Fermilab
Subject: Fermilab Accelerator Improvements for Neutrino Beams

Wednesday, October 17th 2007
4:00 pm:
Speaker: Ed Smith, Jet Propulsion Lab, NASA
Subject: The Heliospheric Magnetic Field: Origin, Structure and Interaction with the Solar Wind and Interstellar Medium
Refreshments moved to Main Hall in front or room 148 at 3:30 p.m.

Parts of the solar corona accelerate into space to form the supersonic solar wind that pushes interstellar material out of the solar system to distances beyond 100 AU creating the "bubble" known as the Heliosphere. The solar wind also transports part of the Sun�s dipole magnetic field into the Heliosphere filling it with magnetized plasma. The Heliospheric Magnetic Field (HMF) prevents the interstellar plasma and magnetic field from penetrating into the Heliosphere leading to a sharp boundary separating the solar and interstellar plasmas. Solar wind outflow leaves �holes� in the corona because of the depletion of the coronal density. When solar activity is low, the Sun�s magnetic poles coincide with two large coronal holes in the north and south polar caps that emit high- speed solar wind while lower speed wind originates at lower latitudes. The magnetic dipole and coronal holes are tilted relative to the Sun�s rotation axis and, as the Sun rotates, the fast and slow wind interact introducing large scale heliospheric structure and dynamics involving the HMF and consisting of alternating compression and rarefaction regions. The distinctive compression regions are bounded by collision-less shocks that accelerate solar particles to high energies. Helisopheric dynamics are further enhanced by the penetration of some interstellar constituents into the Heliosphere, namely, neutral gas, electrically- charged interstellar dust and Galactic Cosmic Rays. Both the structure and dynamics of the heliosphere are profoundly affected by the solar cycle. During maximum solar activity, the Sun�s magnetic dipole effectively rotates equator-ward and eventually reverses polarity while the polar coronal holes vanish and then reappear. An overview of these physical phenomena will be presented based principally on 17 years of 3D observations by Ulysses, the first spacecraft to follow a polar orbit carrying it over and under the Sun.


Thursday, October 18th 2007
12:10 pm:
Speaker: Shea Brown and Tom Jones, University of Minnesota
12:15 pm:
Speaker: Philip Mannheim, University of Conneticut
Subject: Conformal Gravity Challenges String Theory

The cosmological constant problem and the compatibility of gravity with quantum mechanics are the two most pressing problems in all of gravitational theory. While string theory nicely addresses the latter, it has so far failed to provide any compelling solution to the former. On the other hand, while conformal gravity nicely addresses the cosmological constant problem (by naturally quenching the amount by which the cosmological constant gravitates rather than by quenching the cosmological constant itself), the fourth order derivative conformal theory has long been thought to possess a ghost when quantized. However, it has recently been shown by Bender and Mannheim that not only do theories based on fourth order derivative equations of motion not have ghosts, they actually never had any to begin with, with the apparent presence of ghosts being due entirely to treating operators which were not Hermitian on the real axis as though they were. When this is taken care of via an underlying PT symmetry that such theories are found to possess, there are then no ghosts at all and the S-matrix is fully unitary. Conformal gravity is thus advanced as a fully consistent four-dimensional alternative to ten-dimensional string theory.

1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Baruch Meerson, Racah Institute of Physics, Hebrew University of Jerusalem, Israel
Subject: Particle Clustering in Granular Flows: Hydrodynamic Singularities in a Box of Sand?

An assembly of inelastically colliding hard spheres - the granular gas - is a simple model of °ow of granular materials. It provides a fascinating example of a complex system far from equilibrium. Granular gases exhibit a spontaneous clustering instability: development of clusters of particles and voids between them. A similar instability appears in gases and plasmas that cool by their own radiation. Nonlinear theory of the clustering instability has been a major unresolved problem of granular dynamics. We simplified this problem by considering a channel geometry, so that the coarse -grained °ow is one-dimensional. We found that, in the framework of idealized hydrodynamic equations, the gas exhibits a ¯nite-time density blowup. The \attempted" singularities are usually arrested only when the close packing density of hard spheres is reached. Molecular dynamics simulations support the hydrodynamic predictions until close to the time of attempted density blowup. In a certain limit of the instability, the dynamics is describable by a zero-viscosity Burgers equation which makes this system a distant cousin of a structure forming expanding Universe.

2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Yong Qian, University of Minnesota
Subject: Neutrino Mass Hierarchy and Stepwise Spectral Swapping of Supernova Neutrino Flavors

Friday, October 19th 2007
2:30 pm:
FTPI Seminar in Physics 435
Speaker: Ken Intriligator, University of California, San Diego
Subject: "IR Free or Interacting? Proposed diagnostics."
2:30 pm:
Speaker: Robert Lysak
Subject: Plasma Physics in the Solar System and Beyond
This is intended to introduce research projects within the department to new graduate students.

The space between the Sun and the planets in the solar system is not empty; instead, it is filled with a very tenuous, ionized gas known as plasma. This plasma is strongly influenced by the magnetic fields produced in the Sun and the various planets. The Space Plasma Physics group at the University of Minnesota studies these plasmas in a variety of ways. We have designed and built instruments measuring electric fields and waves on a variety of NASA spacecraft studying the solar wind, the Earth’s magnetosphere and radiation belts, and the processes that produce the aurora. Our research is focused on two main questions: (1) How do the electric and magnetic fields in space accelerate charged particles to high energies (e.g., up to MeV in the radiation belts)? (2) How do magnetic fields reorganize themselves when, for example, the magnetic field in the solar wind interacts with the magnetic field of Earth, a process known as magnetic reconnection? These questions are answered not only with direct spacecraft measurements but with theory and modeling to understand the complex plasma interactions that can take place in the solar system, as well as in other astrophysical systems.

3:00 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Robert Benjamin, U. Wisconsin, White Water
Subject: The Milky Way Galaxy: A (Re)Introduction
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

I will provide an overview on progress and problems in understanding the structure of the Milky Way, with a focus on recent results on the stellar structure of the Galaxy using the Spitzer Space Telescope. This will include the most recent estimates on the distance to the center of the Galaxy (shorter than you might have thought), the parameters of the stellar bar(s) of the Galaxy (more complicated than you might have assumed), the number of stellar spiral arms of the Galaxy (fewer than you may have heard). I will also present recent work on the vertical scaleheight (and radial dependence) of the different components of the stellar Galaxy. The relation between the mass density of the Galaxy, traced by the mid-infrared light, and the galactic scale star formation will also be discussed.

Speaker: Stuart McCook, Department of History, University of Guelph
Subject: The 'Malaria of Coffee': Hemileia vastatrix and Changing Ideas about Health and Disease in Plants, 1870-1930
Refreshments served in Room 216 Physics at 3:15 p.m.

The nineteenth-century epidemic erupted at a moment when both popular and scientific ideas of disease -- in humans, plants, and animals -- were changing dramatically. Scientists such as Louis Pasteur and Anton de Bary and their disciples argued for a pathogenic model of disease. The scientists who visited the devastated coffee farms in India and Ceylon explained the epidemic in pathogenic terms, repudiating earlier models of disease that focused on the susceptibility of hosts. While the coffee planters accepted aspects of the pathogenic model of disease, they continued to insist that host susceptibility played an important role in shaping the epidemics. The coffee planters' field observations ultimately changed the scientists' strictly pathogen-centered model of disease.


Monday, October 22nd 2007
Speaker: Shea Brown, University of Minnesota
Subject: "A 280 Mpc Void and the WMAP Cold Spot"

Tuesday, October 23rd 2007
12:20 pm:
Speaker: Dr. Tsuyoshi Kondo
Subject: Tunneling Anisotropic Magnetoresistance in Fe/GaAs Heterostructures
1:00 pm:
Space Physics Seminar in 143 Physics
Speaker: Paul Kellogg, University of Minnesota
Subject: How to measure density and electric field with only 3 antennas
2:30 pm:
No seminar this week.

Wednesday, October 24th 2007
4:00 pm:
No Colloquium This Week

Thursday, October 25th 2007
12:10 pm:
Speaker: Steve Warren, University of Minnesota and Ken Rines, Harvard Center for Astrophysics
12:15 pm:
Speaker: Jose Cembranos, University of Minnesota
Subject: "Goldstones and Solitons in Brane Worlds"
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Matthieu Wyart, Harvard University
Subject: Soft Modes, Rigidity and Relaxation in Amorphous Solids

We poorly understand the microscopic properties of amorphous solids, such as transport, force propagation or even the nature of their mechanical stability. These questions are related to the presence of soft modes in their vibrational spectrum. We explain the nature of these modes in repulsive, short-range systems. This enables to derive a microscopic criterion of rigidity which extends a previous result of Maxwell. This implies that rigidity is not a local property, but is characterized by a length which depends on the packing geometry, and which can be large and even diverge, e.g. near the random close packing. We argue that this description applies to granular media, silica and colloidal glasses. We propose a description of the glass transition in hard sphere systems in terms of these soft modes.
This leads to several predictions, in particular a non-trivial power law scaling characterizing the packing geometry in the glass phase, that we check numerically.

2:30 pm:
Nuclear Physics Seminar in 435 Physics
No seminar this week.

Friday, October 26th 2007
2:30 pm:
Speaker: Allen Goldman
Subject: Superconductivity: What It Is and What We Know
This is intended to introduce research projects within the department to new graduate students.
3:00 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Dean Townsley, University of Chicago
Subject: Explosions in Mass Transferring White Dwarf Stellar Binaries
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

White Dwarf (WD) stars are the most common stellar remnant, being produced by all stars below about 8 times the mass of our sun. Put in a close binary, a WD can gain mass from a companion and undergo a variety of bright, dynamic outburst phenomenon driven by both accretion and thermonuclear explosion. I will discuss how we study the WDs in these systems, during both outburst and quiescence, and what we are learning about their population as a whole and how these binaries form and evolve. I will highlight the ignition of the brightest outbursts they make: Classical Novae -- due to thermonuclear runaway in hydrogen-rich material on the WD surface -- and Supernovae -- due to carbon-burning thermonuclear runaway in the deep interior. Particular attention will be paid to how the features of the evolution of the binary might determine aspects of the explosions. These systems are thought to produce the Supernovae of Type Ia, which have remarkably regular characteristics and are therefore of great interest as standard candles for cosmology. Interesting puzzles remain in our theoretical understanding of these systems and their remarkable outbursts.

Speaker: Amit Hagar, Indiana Univ., Don Howard, Univ. of Notre Dame, Chris Smeenk, Univ. of Western Ontario
Subject: Einstein's Distinction between Principle Theories and Constructive Theories
Please see comments in Abstract section

This Friday's colloquium in History and Philosophy of Science is part of a two-day symposium (Friday and Saturday) of the Institute for Advanced Study (IAS), University of Minnesota, on "Time and Relativity." On Thursday there are two related events. The symposium was organized by Antigone Nounou (Philosophy of Science) and Michel Janssen (History of Science). Below is some basic information about all three events. More details can be found at:

http://www.ias.umn.edu/timeandrelativity.php

3:30-4:10 Amit Hagar, Department of History and Philosophy of Science, Indiana University
Subject: "Length Matters: The Einstein-Swann Correspondence and the Constructive Approach to Special Relativity"

4:10-4:50 Don Howard, Department of Philosophy, University of Notre Dame
Subject: "Einstein on the Principle Theories/Constructive Theories Distinction"

4:50-5:10 Coffee

5:10-5:20
Chris Smeenk, Department of Philosophy, University of Western Ontario
Commentator

5:20-6:00 Discussion


Monday, October 29th 2007
Speaker: Vuk Mandic
Subject: LIGO: Status and Plans

Tuesday, October 30th 2007
12:20 pm:
Speaker: Chunyong He
Subject: Heat Capacity Investigation of Phase Separation and Spin-State Transitions in La1-xSrxCoOx
1:00 pm:
Space Physics Seminar in 143 Physics
Speaker: Dr. Yan Song, University of Minnesota
Subject: Magnetic Reconnection or Irreversible Reactive Interaction in Cosmic Plasmas?
2:30 pm:
Speaker: Jason Haupt, University of Minnesota
Subject: Electron Efficiencies from Data in the CMS detector

Wednesday, October 31st 2007
4:00 pm:
Speaker: Larry Rudnick, Liliya Williams, Marco Peloso, Shaul Hanany, Shea.Brown
Subject: The CMB, Dark Energy, and the Giant Void in the Universe
Refreshments served in Room 216 Physics at 3:30 p.m.

The recent discovery of a giant, 280 Mpc diameter void in the universe involved a number of puzzle pieces - fluctuations in the cosmic microwave background, radio surveys of the nearby universe, the evolution of dark-matter dominated large scale structures, and the role of dark energy in this evolution. We will show how these puzzle pieces come together to create the "late integrated Sachs-Wolfe" effect, one of the perturbations on the CMB as it propagates through the universe and then leads to the discovery of the giant void. We will briefly discuss the implications of this void for our understanding of the development of large scale structure in the universe.


Thursday, November 1st 2007
12:10 pm:
Speaker: Pete Mendygral and Sebastian Hidalgo, both University of Minnesota
12:15 pm:
Speaker: Witold Skiba, Yale University
Subject: "Light Scalar at LHC: the Higgs or the Dilaton?"
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Raymond Bishop, Manchester
Subject: Quantum Phase Transitions in Spin-Lattice Systems With and Without Frustration

The coupled cluster method (CCM) has become one of the most pervasive and most powerful of all ab initio formulations of quantum many-body theory. It has yielded numerical results which are among the most accurate available for a wide range of both finite and extended physical systems defined on a spatial continuum. This widespread success has spurred recent applications to similar quantum-mechanical systems defined on an extended regular spatial lattice. In particular, we have shown how the systematic inclusion of multispin correlations for a wide variety of quantum spin-lattice problems can be very efficiently implemented with the CCM. The method is not restricted to bipartite lattices, to spin-half systems, or to non-frustrated systems, and can thus deal with problems where, for example, the quantum Monte Carlo (QMC) techniques would be faced with the infamous "minus-sign problem." In this talk I briefly review the CCM itself and then discuss an illustrative example from among many applications made to quantum spin-lattice systems, for a model with two types of interactions which exhibits competition between magnetic order and dimerization. As in all other cases the CCM may readily be implemented to high (LSUBm) orders using computer-algebraic techniques. Values for ground- and excited-state properties are obtained which are fully competitive with those from other state-of-the-art methods, including the much more computationally intensive QMC techniques, in the special cases where the latter can be applied. The raw LSUBm results are themselves generally excellent. They converge rapidly and can be extrapolated in the truncation index, m. The CCM can also provide valuable information on the quantum phase transitions, quantum order, and quantum criticality, as we show in our example. For such strongly correlated models of magnetism with competing interactions in two (or higher) dimensions, the CCM probably now represents the most powerful general method available, as I hope to show.

2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Jim Kneller, University of Minnesota
Subject: The Lithium-6 Plateau

Friday, November 2nd 2007
2:30 pm:
Speaker: Mikhail Shifman
Subject: HEP theory
This is intended to introduce research projects within the department to new graduate students.
3:00 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Doug Leonard, SDSU
Subject: Seeking the Type Ia Supernova Progenitor
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

Despite intense scrutiny, the progenitor system(s) that gives rise to Type Ia supernovae has remained remarkably unconstrained by direct observation. The favored theory invokes a carbon-oxygen white dwarf accreting hydrogen-rich material from a close companion until a thermonuclear runaway ensues that incinerates the white dwarf. However, simulations resulting from this single-degenerate, binary channel demand the presence of low-velocity H-alpha emission in spectra taken during the late nebular phase, since a portion of the companion's envelope becomes entrained in the ejecta. This hydrogen has never been detected, but has only rarely been sought. In this talk I will present results from an ongoing campaign to obtain deep, multi-epoch, nebular-phase spectroscopy of nearby Type Ia supernovae in an effort to detect this telltale signature of the companion star. Results from two additional investigations that each seek different observational signatures resulting from popular progenitor system models will also be discussed.

3:35 pm:
History of Science and Technology Colloquium in Carlson School of Management, Room: t.b.a.
Speaker: Kenneth Manders, Department of Philosophy, University of Pittsburgh. Cosponsored by the Minnesota Center for Philosophy of Science
Subject: Representation vs Ontology in Mathematics
Note: Different Place

I will argue that representation (and correspondences between representations) should replace ontology as the central explainer in the philosophy of mathematics. The argument has two parts. The core of the argument shows how distinctive qualities of competing representations help explain the ability of their users to grasp (and prove) mathematical relationships. I refer to several case studies (Descartes vs Euclid, but especially: ways of representing knots). The closing argument contrasts ways in which traditional ontology-oriented inquiries are unproductive in explaining the intellectual power of mathematics.


Monday, November 5th 2007
Speaker: Terry Jay Jones, University of Minnesota
Subject: Fundamental constants, not so variable after all
Speaker: Igor Burmistrov, L.D. Landau Institute for Theoretical Physics
Subject: Energy relaxation in the spin-polarized disordered electron liquid

The energy relaxation in the spin-polarized disordered electron liquid is studied in the diffusive regime. We derived the quantum kinetic equation in which the kernel of electron-electron collision integral explicitly depends on the electron magnetization. As the consequence, the inelastic scattering rate is found to have non-monotonic dependence on spin-polarization of the electron system. Based on arxiv:0708.0523


Tuesday, November 6th 2007
12:20 pm:
Speaker: Yu Chen, University of Minnesota
Subject: Trapping carriers in organic field-effect transistors by metal nanoparticles
2:30 pm:
Speaker: Deborah Harris, Fermi National Accelerator Laboratory
Subject: The MINERvA Experiment

The MINERvA Experiment is designed to measure low energy neutrino interactions in exquisite detail both in support of neutrino oscillation experiments and also to study the strong dynamics of the nucleon and nucleus. This talk will briefly describe the suite of oscillation measurements that motivates the MINERvA experiment, and then show the expected performance of the detector and the current status of prototyping and construction.


Wednesday, November 7th 2007
4:00 pm:
Speaker: Walter Gekelman
Subject: Three-dimensional current systems produced by colliding plasmas in a background Magnetoplasma
Refreshments served in Room 216 Physics at 3:30 p.m.

Results are presented from an experiment in which two plasmas, initially far denser than a background magnetoplasma, collide as they move across the magnetic field. The dense plasmas are formed when laser beams, nearly orthogonal to the background magnetic field strike two targets. The merging plasmas are observed to carry large diamagnetic currents. The interaction spawns the generation of intense waves in the plasma. The first burst of waves observed, are whistler waves and their dispersion and spatio-temporal structure will be presented. Less than a microsecond after the collision a "magnetic reconnection" event is triggered by the collision and the electric field induced in this event generates a field aligned current. This is the first step in the development of a fully three-dimensional current system. After several ion gyro-periods the current systems become those of shear Alfven waves. As local currents move, small reconnection "flares" occur at many locations throughout the plasma volume. Magnetic field lines associated with these waves are shown in the figure above. The data clearly show that the induced electric field is carried though the system by shear Alfven waves. The relation of this experiment to phenomena in space and astrophysics will be discussed.


Thursday, November 8th 2007
10:00 am:
Thesis Defense in Physics 358B (Astronomy Reading Room)
Speaker: Jeremy Gogos
Subject: An Atmospheric Muon Neutrino Disappearance Measurement with the MINOS Far Detector
10:10 am:
Space Physics Seminar in 170 Physics
Speaker: Walter Gekelman from UCLA
Subject: Experiments relevant to space at the UCLA Basic Plasma Science Facility
Please note different time and place.
12:10 pm:
Speaker: Karl Isensee and Yong Qian, University of Minnesota
12:15 pm:
Speaker: Yuri Shirman, University of California, Irvine
Subject: Low energy gauge mediation from metastable vacua
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Daniel Sheehy, Iowa State
Subject: The Low-Temperature Phases of Polarized Fermionic Superfluids

A number of recent experiments have achieved paired superfluidity of trapped fermionic atomic gases. Such pairing, occurring between two atomic hyperfine-state species (forming a pseudo-spin-1/2 system), is possible due to the strong attractive interactions provided by a magnetic field tuned Feshbach resonance (FR). At equal populations, the superfluidity of resonantly interacting Fermi gases undergoes the well-studied crossover between Bardeen-Cooper-Schrieffer (BCS) pairing and Bose-Einstein condensation (BEC) as a function of FR detuning (or
interaction strength). I will discuss recent work aimed at
understanding the case of unequal populations (i.e., imposed
spin polarization), an easily controllable experimental knob that is predicted to interrupt the continuous equal-population BCS-BEC
crossover, yielding a variety of distinct phenomena including regions of singlet paired superfluid, unpaired polarized normal Fermi liquid, polarized Fulde-Ferrell-Larkin-Ovchinnikov superfluid, polarized magnetic superfluid, and phase-separated mixtures of these uniform states.

2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Yang Li, Iowa State
Subject: Gluon recombination in high parton density QCD

We argue that the collinear factorization of the fragmentation functions in high energy hadron and nuclear collisions breaks down at transverse momenta k_T ~ Q_s/g due to high parton densities in the colliding hadrons and/or nuclei. We then argue that gluon recombination, which is basically the merging of two classical fields, should dominate in that k_T regime. We calculate, at next-to-leading order in projectile parton density and to all orders in target parton density, the double-inclusive cross-section for production of a pair of gluons in the scalar J^{PC} = 0^{++} channel. We then generalize our results to AuAu collisions at RHIC energy. Using the low energy theorems of QCD we find the inclusive cross-section for pion meson and baryon production. Finally, we compare our results for baryon to meson ratio with the experimental data from RHIC.


Friday, November 9th 2007
2:30 pm:
Speaker: Roger Rusack
Subject: CMS experiment
This is intended to introduce research projects within the department to new graduate students.
3:00 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Dean C. Hines, NM Office, Space Science Institute
Subject: The Formation and Evolution of Planetary Systems
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

The advent of powerful ground- and space-based telescopes and extremely sensitive detectors has enabled the development of a comprehensive picture of the formation and evolution of planetary systems, enabling us to better place our solar system in a broad astrophysical context. In this presentation, I will briefly summarize our current understanding of these processes and their intimate connection with stellar evolution. I will
highlight this overview with many new results from the Hubble and Spitzer Space Telescopes that capture the formation and evolutionary processes in action.

Speaker: John P. Jackson, Department of Communication, University of Colorado-Boulder
Subject: The Boundary Work of the ‘Blank Slate’: Creating the Disciplines of Evolutionary Psychology and Cultural Anthropology
Refreshments served in Room 216 Physics at 3:15 p.m.

This talk will compare the boundary work of evolutionary psychologists and cultural anthropologists as they create their scientific disciplines. I will argue that each group attempted to put forth a different argument about what counted as a proper explanation of culture and the kinds of definitional moves each group made differed substantially. Here at the dawn of the twenty-first century, some psychologists are creating a new discipline called "evolutionary psychology." The evolutionary psychologists maintain that all of our explanations for social and cultural behavior are truncated because these explanations are not grounded in Darwinian evolution. Evolutionary psychologists point to Boasian cultural anthropology as the worst offender for non-Darwinian explanations of culture. At the dawn of the twentieth century, cultural anthropologists, particularly Alfred Kroeber (1879-1960) did indeed argue that cultural explanations should not invoke biology. However, a close examination of Kroeber’s claims reveals that Darwinian thought was a necessary part of Kroeber’s separation of culture from biology.


Monday, November 12th 2007
Speaker: Liliya Williams
Subject: Cosmology WITHOUT Supernova and CMB

Tuesday, November 13th 2007
12:20 pm:
No Seminar This Week
1:00 pm:
Space Physics Seminar in 143 Physics
Speaker: Scott Thaller, University of Minnesota
Subject: Survey and Significance of Bipolar Electric Fields observed near a Magnetic Reconnection Region in the Geomagnetic tail
2:30 pm:
Speaker: Mark Kos, Queen's University
Subject: Low Energy Threshold Analysis of the Sudbury Neutrino Observatory Salt phase Data

The addition of salt into the heavy water (D2O) volume of the Sudbury Neutrino Observatory (SNO) has greatly increased the sensitivity to the neutral current (NC) neutrino interaction. A large part of the uncertainty on the charged current (CC) and NC flux measurements in the pure D2O phase was the correlation between NC and CC events. In the salt phase the Cherenkov light produced by the NC interaction is much more isotropic than for CC interactions. This has enhanced our ability to separate between the NC and CC interactions.

The SNO collaboration has to date published a neutrino spectrum for the CC neutrino interaction in the salt phase down to an electron energy of 5.5MeV (Phys. Rev. C 72, 055502 (2005)). This energy threshold was chosen to minimize the radioactive background contamination in the extracted neutrino signal. The CC energy spectrum above 5.5MeV shows little difference in shape between the undistorted 8B neutrino spectrum and the 8B spectrum distorted by the Large Mixing Angle (LMA) solution for neutrino oscillations. The LMA solution predicts an upturn in the CC spectrum at lower energies. By accounting for the internal and external radioactive backgrounds the CC energy spectrum was extracted down to an energy threshold of 4MeV.

The physics results from extracting the CC spectrum at lower energies are potentially very interesting. Not only does it offer a better test of the LMA solution, but allows for the test of potential "new physics". A lack of upturn in the CC spectrum below 5.5MeV for example could be explained by some sterile mixing theories or non-standard neutrino interactions.


Wednesday, November 14th 2007
4:00 pm:
Speaker: Prof.Earl Peterson and Prof.Keith Ruddick
Subject: History of High Energy Physics at Minnesota
Refreshments served in Room 216 Physics at 3:30 p.m.

Thursday, November 15th 2007
12:10 pm:
Speaker: Crystal Austin and Bob Gehrz, University of Minnesota
12:15 pm:
Speaker: Michael Ramsey-Musolf, University of Wisconsin
Subject: Baryogenesis, Electric Dipole Moments, and the Higgs Boson

Explaining the predominance of visible matter over antimatter
remains one of the outstanding puzzles at the interface of cosmology with particle and nuclear physics. Although the Standard Model cannot account for the matter-antimatter asymmetry, new physics at the electroweak scale may provide the solution. In this talk, I discuss the general requirements for successful electroweak scale baryogenesis; recent theoretical work in computations of the matter-antimatter asymmetry; and implications for experimental searches for permanent electric dipole moments of the electron and neutron and for the Higgs
boson at future colliders.

1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Dr. Eugene Tsiper, Scientific Perfect LLC, St. Paul, MN
Subject: Application of Lanczos technique to Hermitian and certain non-Hermitian problems in Physics

Large Hermitian eigenvalue problems appear frequently in electronic structure theory. The underlying quantum many-body problem is often referred to as "incomputable" since it involves Hilbert spaces whose dimensionality grows exponentially with the number of particles. This complexity is, in fact, key to the idea of quantum computer, since a moderately large quantum many-body system possesses an amount of information greater than any conventional computer can handle. Yet, exact diagonalization of finite clusters using conventional computers is a valuable tool that helps us understand many physical phenomena.

In this presentation I will review the Lanczos recursion and related Krylov subspace methods that allow us to solve ultra-large Hermitian eigenvalue problems. I will also discuss a complementary classical problem that leads to Hamiltonian (non-Hermitian) eigenvalue equation, and an intricate relation that exists between its eigenvalues and the eigenvalue differences, or excitation energies, of the quantum system.

I will present a generalization of Rayleigh-Ritz minimum principle and of Lanczos recursion to this class of problems and discuss implications to time-dependent (TD) quantum ansatz methods, such as TD density functional theory (TD-DFT), TD Hartree Fock (TDHF), etc.

2:30 pm:
Nuclear Physics Seminar in 435 Physics
No Seminar This Week

Friday, November 16th 2007
2:30 pm:
Speaker: Dan Cronin-Hennessy
Subject: MINOS/NOvA experiment
This is intended to introduce research projects within the department to new graduate students.
3:00 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Andy Sheinis, U. Wisconsin, Madison
Subject: Host Galaxies of Luminous Quasars: Structural Properties and the Fundamental Plane
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

We explore the relationship of the hosts of luminous quasars to normal giant elliptical galaxies in order to look for evidence of evolutionary trends. We use measured stellar velocity dispersions combined with effective radii and magnitudes from the literature to place the host galaxies of 8 luminous quasars (MV < -23) on the Fundamental Plane (FP), where their properties are compared to other types of galaxies. We find that the radio-loud (RL) QSO hosts have similar properties to massive elliptical galaxies, while the radio-quiet (RQ) hosts are more similar to intermediate mass galaxies. The RL hosts lie at the upper extreme of the FP due to their large velocity dispersions , low surface brightness , and large effective radii and M/L = 14.1. Our data support previous results that PG QSOs are related to gas-rich galaxy mergers that form intermediate-mass galaxies, while RL QSOs reside in massive early-type galaxies, some of which also show signs of recent mergers. Most previous work has drawn these conclusions by using estimates of the black hole mass and inferring host galaxy properties from that, while here we have relied purely on directly measured host galaxy properties.

Speaker: Lillian Hoddeson, Department of Physics, University of Illinois, Urbana
Subject: Analogy and Inventive Style: Stanford Ovshinsky's Radical Approach to Inventing Alternative Energy Technologies
Refreshments served in Room 216 Physics at 3:15 p.m.

Examining the American inventor Stanford Ovshinsky's fruitful analogy between a human nerve cell and an adaptive machine and the steps he took from this analogy to his “threshold” switch and subsequent inventions offers new perspectives on analogy as a motor of invention.


Monday, November 19th 2007
Speaker: Barun Kumar Dhar
Subject: "Reconstructing Dark Matter halos in Clusters of galaxies: A new approach"

Tuesday, November 20th 2007
12:20 pm:
No seminar this week.
1:00 pm:
Space Physics Seminar in 143 Physics
Speaker: Lynn Wilson, University of Minnesota
Subject: Waves at Interplanetary Shocks: New Results from Wind and STEREO

Wednesday, November 21st 2007
4:00 pm:
No Colloquium This Week

Thursday, November 22nd 2007
No events scheduled for today.

Friday, November 23rd 2007
No events scheduled for today.

Monday, November 26th 2007
10:00 am:
Thesis Defense in Walter Library, Room 404
Speaker: Longhua Hu
Subject: Statistical Mechanics Problems in Biopolymer Physics
Speaker: Marco Peloso, University of Minnesota
Subject: Nonperturbative reheating after inflation: is it testable?

Tuesday, November 27th 2007
12:20 pm:
Speaker: Mike Erickson, University of Minnesota
Subject: Spin injection, transport, and detection in lateral metallic spin valves
1:00 pm:
Space Physics Seminar in 143 Physics
Speaker: Dr. John Dombeck, University of Minnesota
Subject: Intense, Earthward, Broadband Electron Events Observed at Low Latitude During Major Geomagnetic Storms at FAST
2:30 pm:
No seminar this week.
3:00 pm:
Special Astrophysics Seminar in Astronomy Reading Room (358)
Speaker: Massimo Marengo, Harvard Center for Astrophysics
Subject: A Spitzer View of the epsilon Eridani Planetary System

When a "radial velocity" planet was discovered orbiting our neighbor star epsilon Eridani, it was thought that the home of the Star Trek "Vulcans" was finally found. Even though it was later determined that Dr. Spock was originally from a different stellar system, epsilon Eridani remains the best available example to study a younger, dustier solar system analog.

With an age of 850 Myr and a spectral type of K2V, it is a young main sequence star with a mass just below that of the Sun. Apart for the Jupiter-size planet detected with radial velocity techniques, it also harbors a dusty "debris disk" found by IRAS and first imaged at sub-mm wavelengths, roughly the size of our own Kuiper belt. These characteristics, and the proximity of epsilon Eridani to the Sun (just 3.2 pc), make it the ideal subject to study what could have been the early history of our own solar system. The Spitzer Space Telescope, with its high sensitivity and stability, offers a unique perspective to complete this picture, at wavelengths where the dust emission from the disk are stronger, and it is easier to search for direct emission from sub-stellar companions.


Wednesday, November 28th 2007
4:00 pm:
Speaker: Timothy Newman, Arizona State University, Center for Biological Physics
Subject: Discrete, mesoscale, stochastic dynamics in biological systems: applications to embryogenesis and biochemical networks
Refreshments served in Room 216 Physics at 3:30 p.m.

I will argue that the theory of stochastic processes provides a solid framework for describing biological systems. I will present two applications. The first concerns the development of algorithms capable of modeling large-scale multi-cellular systems, such as the early embryo. I will discuss the Subcellular Element Model (SEM), which is designed to simulate the interactions between thousands of three-dimensional, visco-elastic, deformable cells. The use of the SEM to understand one of the most fundamental embryonic processes - extension of the primitive streak - will be described. The second application is to cycling phenomena. I will discuss a new theoretical mechanism which predicts that intrinsic noise can induce oscillations in populations of small to intermediate size. I will illustrate this phenomena at two very different length scales, using the famous predator-prey system from ecology and non-linear feedback loops in genetic networks.


Thursday, November 29th 2007
12:10 pm:
Speaker: Jessica Ennis and Evan Skillman, University of Minnesota
12:15 pm:
Speaker: Kenji Kadota, University of Minnesota
Subject: Cosmology in warped extra dimensions
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Chris Leighton, CEMS, University of Minnesota
Subject: Tunable spin polarization in Co1-xFexS2: Engineering half-metallic ferromagnets

The essence of the emerging field of spin-electronics or “spintronics” is to utilize electron spin to create new microelectronic devices or increase the functionality of existing ones. One thing common to all such devices is a source of spin-polarized electrical current, most commonly a ferromagnetic material. It has therefore become a priority to develop materials that have high spin polarization at the Fermi level, P. The ideal case would be a 100 % polarized material, known as a “half-metallic ferromagnet”. Although numerous materials have been predicted to be half-metallic, an extensive experimental search has yielded few viable candidates. In this talk I will present a different approach. The idea is to “engineer” a highly polarized ferromagnet by alloy control over the electronic band structure, rather than simply searching for one based on the predictions of band structure calculations. Using a model system, Co1-xFexS2, we have demonstrated the feasibility of this concept and have achieved tunable spin polarization in the range –56 % < P < +85 %. The system has allowed us to probe the electronic, magnetic and thermodynamic properties as a controlled function of the spin polarization. I will end with a summary of our efforts to improve on this P value by increases in material quality (in stoichiometric single crystals) as well as growth of epitaxial thin films for inclusion in heterostructured devices such as GaAs-based spin injection structures.

2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Todd Springer, University of Minnesota
Subject: Thermodynamics and Transport Coefficients from Gauge/Gravity Duality

Friday, November 30th 2007
2:30 pm:
Speaker: Dan Dahlberg (changed from Dec 7)
Subject: Experimental Condensed Matter
This is intended to introduce research projects within the department to new graduate students.
3:00 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Kris Davidson, University of Minnesota, Astronomy Department
Subject: ETA and the Supernova Impostors
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

In the past five years several trends have synergistically enhanced the importance of the most massive stars for astrophysics and cosmology. The GRB and first-stars connections remain valid, but now we also have the recognition of a class of Supernova Impostors, a revolution in our understanding of the Eddington Limit, recent theoretical models of ultra-high-energy supernovae, and other unexpected developments. Collectively, stars above 100 Msun have become essential both for cosmology and for astrophysical processes in general. A large fraction of everything known about such objects is based on Eta Carinae, which is far easier to observe than any other object in the class. Eta's bizarre phenomena have repeatedly exposed gaps and errors in existing theory. Observations of this object have undergone another revolution in the past decade, while, independently, it shows signs of changing to a different physical state. Here I shall review the current significance of the most massive stars, of supernova impostors, and recent surprises concerning Eta Carinae.

Speaker: Evelynn Hammonds, Holyoke Center, Harvard University
Subject: The Marginalization of Experience
Refreshments served in Room 216 Physics at 3:15 p.m.

This talk addresses the problem of the underrepresentation of women of color in STEM fields from a historical perspective.


Monday, December 3rd 2007
4:00 pm:
Thesis Defense in 435 Physics
Speaker: Alexander Scott
Subject: Measuring Quantum Correlations in Entangled D Decays at CLEO-c

Tuesday, December 4th 2007
12:20 pm:
Speaker: Shun Wang
Subject: Unexpected Phenomenon in Smectic A Liquid Crystalline Phase
1:00 pm:
Space Physics Seminar in 143 Physics
Speaker: Lei Dai, University of Minnesota
Subject: Cluster observation of extremely oblique low frequency waves in the magnetic reconnection jet in the geomagnetic tail.
2:30 pm:
No seminar this week.

Wednesday, December 5th 2007
4:00 pm:
Speaker: Thomas Delworth, Geophysical Fluid Dynamics Laboratory, National Oceanic and Atmospheric Administration (NOAA)
Subject: Decadal-scale changes in the Atlantic Ocean - natural variability and human-induced climate change
Refreshments served in Room 216 Physics at 3:30 p.m.

The Atlantic Ocean is an integral component of the global climate
system, transporting in excess of 1 PW of heat poleward. It is anticipated that fluctuations or changes in that heat transport might have important climatic impacts. Here we review observational estimates of past variability and change in the Atlantic, including recent rapid warming. Part of the decadal scale variability in the Atlantic appears to be associated with natural variability of the ocean circulation, modulating the transport of heat poleward, and having a significant impact on the atmosphere. This impact includes modulation of the African and Indian monsoonal systems, tropical Atlantic atmospheric circulation changes of relevance for hurricanes, and an influence on summer climate over North America and Western Europe. While natural variability may have contributed to the most recent rapid warming, a substantial fraction of the recent warming is likely attributable to human-induced climate change. Future projections of Atlantic change are influenced by both anthropogenic forcing and natural variability.


Thursday, December 6th 2007
12:10 pm:
Speaker: Martha Boyer and Roberta Humphreys, University of Minnesota
12:15 pm:
Speaker: Alex Kusenko, UCLA
Subject: "Dark matter and sterile neutrinos: the dark side of the light fermions"
1:25 pm:
Condensed Matter Seminar in 210 Physics
Speaker: Russell Holmes,CEMS, U of M
Subject: Small molecular weight organic photovoltaic cells – Recent progress, current challenges, and future potential

Organic materials have received considerable attention in the context of future sources of inexpensive, renewable energy. Photovoltaic devices constructed from organic thin films are amenable to high throughput processing techniques using lightweight and flexible substrates, potentially enabling the low-cost fabrication of large area devices. While qualitatively similar to their inorganic semiconductor counterparts, the van der Waals bonding of organic solids leads to the formation of excitonic bound states upon optical excitation. As such, architectures for photoconversion must dissociate the exciton into its constituent charge carriers. This additional requirement for efficient operation is an important consideration in the design of candidate active materials and device architectures. This talk will examine recent progress in the development of organic photovoltaic cells, as well as the potential for further improvement in device performance and an improved understanding of device physics.

2:30 pm:
Nuclear Physics Seminar in 435 Physics
Speaker: Scott Bowman, University of Minnesota
Subject: Linear Sigma Model at Finite Temperature and Isospin Chemical Potential

In relativistic heavy ion collisions large numbers of pions are created. It may be possible for these pions to condense into the zero-momentum state, i.e. form a Bose-Einstein condensate. Pions have the special property of being Goldstone bosons of the spontaneously broken chiral symmetry of QCD. The O(N)-symmetric linear sigma model is used as an effective low energy model for QCD to understand the relationship between chiral symmetry breaking and Bose-Einstein condensation. This has recently been studied by Shu and Li and by Andersen. Shu and Li use the framework of the Cornwall-Jackiw-Tomboulis formalism and the 1/N approximation, while Andersen uses the 2PI (Phi derivable) method. I will review their work and attempt to go further in understanding the thermodynamic properties of the sytem.


Friday, December 7th 2007
2:30 pm:
Speaker: Vincent Noireaux (Changed from Nov 30)
Subject: In vitro expression in synthetic vesicles: expressing, feeding, degrading
This is intended to introduce research projects within the department to new graduate students.

We use the translation machinery of a cell-free expression system to reconstruct genetic circuits in vitro. Expression of elementary gene circuits can be carried out in batch mode or continuous mode to study quantitatively the properties of genetic circuits. The extract can be also encapsulated in synthetic phospholipids vesicles. This system is used as a model of protocell programmable with DNA. One of the challenges of this engineering approach is to reach homeostasis by (1) maintaining efficient in vitro expression on long period of time by feeding the vesicles, (2) degrading selectively the synthesized messengers and proteins. Perspectives and limitations of this approach will be discussed.

3:00 pm:
Astrophysics Colloquium in 210 Physics
Speaker: Dr. Cynthia Cattell, University of Minnesota, Physics
Subject: STEREO observations of large amplitude whistler-mode waves in Earth’s radiation belts: Implications for relativistic electron acceleration and loss
Refreshments served following the talk in the Astronomy Reading Room, 358 Physics

A key longstanding problem in space and astrophysical plasmas is determining the mechanism that accelerates electrons to relativistic energies. It is critical to understanding the dynamics of the Van Allen radiation belts, where MeV electrons can damage spacecraft systems. We report the discovery, in STEREO S/WAVES data, of obliquely-propagating whistler-mode waves in the radiation belt with electric field amplitudes more than an order of magnitude larger than other whistlers. Simulations show that these large amplitude waves can energize an electron by an MeV in less than 0.1s, explaining the rapid enhancement in electron intensities observed between the STEREO-A and STEREO-B passages through the belt. Our results show that the usual theoretical models of electron energization and scattering via small-amplitude waves, with timescales of hours to days, are inadequate for understanding radiation belt dynamics.

Speaker: Laura Snyder, Department of Philosophy, St. John’s University. Cosponsored by the Minnesota Center for Philosophy of Science.
Subject: Bold Leaps: Guesses or Inferences? Analogical Reasoning in Science
Refreshments served in Room 216 Physics at 3:15 p.m.

In his Preliminary Discourse on the Study of Natural Philosophy (1830), the astronomer and philosopher J.F.W. Herschel claimed that it was sometimes acceptable to invent a theory by making a "bold leap" to a hypothesis, so long as this hypothesis was then tested deductively. Because of this comment, Herschel has generally been considered a proponent of the "hypothetical-deductive" or "hypothetical" method of science. It has been argued by commentators that because Herschel was well-versed in science, he realized that the science of his day relied on unobservable entities, such as light waves, ethers, and tiny particles of matter; Herschel, it is said, correctly recognized that theoretical science requires a hypothetical method. In my paper, I will show that this interpretation of Herschel is just one of a number of instances in which modern philosophers of science have erred in attributing a hypothetical method to writers of the past. I will demonstrate that Herschel, like these other writers, believed that analogical reasoning was a key part of scientific discovery. Scattered comments about "bold leaps" are meant to refer to instances of analogical inference, not conjectures or guesswork. Herschel, and other misunderstood writers such as Francis Bacon in the seventeenth century and Herschel's friend William Whewell in the nineteenth, believed that analogical inference played a large role in scientific discovery, even for theoretical science. And they were right. Part of the reason for these misinterpretations is historical: commentators have ignored the context of these comments within the work of the writer and within his intellectual and social framework. And part is philosophical: analogical inference is very often overlooked or undervalued as a part of inductive reasoning. I will argue here that, by debunking this "myth" about "bold leaps" in the scientific method proposed in the past, we can learn important lessons for philosophy of science in the present.


Monday, December 10th 2007
12:00 pm:
History of Science and Technology Colloquium in Carlson School of Management, Room: TBA
Speaker: Giovanni Giorgini, Department of Ancient History, University of Bologna. Cosponsored by the Minnesota Center for Philosophy of Science
Subject: Relativism and Its Discontents
Refreshments served in Room 216 Physics at 3:15 p.m.

Relativism, the view that all knowledge is relative to some percipient subject and that there is no universal, objective truth, is a product of knowledge. Historically, it was probably the result of a generalisation of some observations made by Greek mariners and merchants: laws and customs in distant (and not so distant) countries were different, sometimes opposite, from those of the Greeks. Knowledge of different customs brought about a challenge to knowledge itself. Some daring thinkers argued that there was thus an obvious contrast between what is valid by nature, always and everywhere, and what is valid by custom or law, and is therefore situated in a specific time and place. From a notion about knowledge, relativism quickly and naturally expanded into a full-fledge theory about everything: moral values, education and civilization, political arrangements, the existence of the gods.

Nowadays, it is especially moral and cultural relativism that hold the sway, because of the strong immigration fluxes and the exposure to different cultures not mediated by that typical attitude of Western superiority that was still dominant until a few decades ago. The problem of relativism, when applied to practical matters, is still more interesting and commands our attention for its consequences. Is there any standard, beside our preferences, likes and dislikes, by which we may evaluate competing claims about entities of the utmost importance (values, political arrangements, religion, scientific theories about man and the universe)?

In my paper I will examine historically the origins of relativism and the first consistent relativist thinker, Protagoras, in order to show how his theory about knowledge contains an explicit non-relativist part when it comes to value-judgements. I then move on to maintain that relativism, although an attractive theory for its deconstructionist slant, it is untenable as a general outlook on reality.

Speaker: Michael Milligan
Subject: "Stars Powered by Dark Matter"

Tuesday, December 11th 2007
12:20 pm:
No seminar this week. This event will resume spring semester.
1:00 pm:
Space Physics Seminar in 143 Physics
No seminar this week. This event will resume spring semester.

Wednesday, December 12th 2007
4:00 pm:
Speaker: Bob Pepin, U of M
Subject: Stardust Mission
Refreshments served in Room 216 Physics at 3:30 p.m.

Comets are frozen, largely unaltered reservoirs of dust and gases present in the early solar nebula. They are likely to contain well-preserved records of the chemical, mineralogic, and isotopic character of primordial solar-system matter. On January 15, 2006, the Stardust Mission returned to Earth with a cargo of particles collected from the coma of comet Wild 2, the first samples of indisputably cometary matter available for laboratory study. Among these investigations, the noble gases provide unique data on contributions to comets from various solar-system volatile reservoirs, and of physical processing of gases acquired from these reservoirs. In this talk we discuss the first measurements of helium and neon in Stardust material.

One of the surprises in samples collected from an icy object forming, and, for most of its lifetime, residing in the cold outer reaches of the solar system was the discovery in other laboratories that many of its constituent particles are igneous, refractory “rocklets” formed at very high temperatures, presumably close to the early Sun, which were then somehow transported to the trans-Neptunian Kuiper Belt and incorporated into Wild 2 at about the time of the solar system’s birth 4.5 billion years ago. (In retrospect the “rocklets” shouldn’t have been all that astonishing: Ed Ney, Louis Rose and others at Minnesota argued three decades ago from IR spectroscopic data that igneous grains were present in comets). A second and completely unanticipated feature of Stardust matter is the finding here of enormous concentrations of He and Ne that, of known gas acquisition mechanisms, only intense ion irradiation seems able to explain. These two observations, together with isotopic data pointing to Ne similar to that found in primitive meteorites, suggest that gases in Stardust grains were implanted from an ancient, energetic nebular reservoir near the young evolving Sun.


Thursday, December 13th 2007
12:10 pm:
No seminar this week. This event will resume spring semester.
12:15 pm:
Speaker: Veronica Sanz, Boston University
Subject: "Benchmarks for new strong interactions at the LHC"

New strong interactions at the LHC may exhibit a richer structure than a rescaled version of QCD at the electroweak scale. This departure from rescaled QCD is required to construct scenarios of strong interactions compatible with electroweak constraints. In this talk we use a simple framework, based on a 5D model with a modification of AdS geometry in the infrared, to navigate among these scenarios and propose two points with particularly interesting phenomenology. Within these benchmark points we explore the discovery of vector and axial resonances in the Drell-Yan, associated production and vector boson fusion channels.

1:25 pm:
Condensed Matter Seminar in 210 Physics
No seminar this week. This event will resume spring semester.
2:30 pm:
Nuclear Physics Seminar in 435 Physics
No seminar this week. This event will resume spring semester.

Friday, December 14th 2007
1:00 pm:
Speaker: Tom Bing, University of Maryland, College Park
Subject: Upper Level Physics Students' Framing of Math Use

Mathematics is central to a professional physicist's work and, by extension, to a physics student's studies. It provides a language for abstraction, definition, computation, and connection to physical reality. This power of mathematics in physics is also the source of many of the difficulties it presents students. Simply put, many different activities could all be described as "using math in physics". Framing is a mental process that helps students navigate such a wide range of possibilities. At any given moment, the mind makes a judgment (often subconsciously) regarding the nature of the present activity. What kind of activity is this? This judgment primes a subset of the student's available resources while inhibiting others. The student's attention is focused while other possible responses are temporarily bracketed away from their conscious consideration. Localized coherencies evolve in the students' thinking. This talk will present a way of identifying and analyzing the effects of framing in upper level physics students' mathematical thinking. It uses an epistemic lens, one that looks at the type of justification the students are offering for their mathematical claims, to do so. Such a focus offers a convenient way of parsing students' thought. Several video clips are offered as examples. This framing analysis is then applied to address the sample research question "What effect does a powerful calculator like Mathematica have on physics students' thinking?"

2:30 pm:
No seminar this week. This event will resume spring semester.
3:00 pm:
Astrophysics Colloquium in 210 Physics
No colloquium this week. This event will resume spring semester.

Tuesday, December 18th 2007
This event will resume spring semester.
1:00 pm:
Speaker: Joss Ives, University of British Columbia
Subject: Reforming a Large Introductory Physics Course at the University of British Columbia

The Department of Physics and Astronomy at the University of British Columbia has recently completed the first year of an expected three-year cycle to reform one of our large courses. In addition to reforms of instructional methods and assessment based on student learning goals and learning outcomes, the course curriculum was shifted to present the physics content in the context of energy production and consumption. I will discuss the motivation, methods and assessment of this reform.

This event will resume spring semester.
2:30 pm:
Speaker: Sinjini Sengupta, University of Minnesota
Subject: W and Z Boson Asymmetries at the Tevatron

Wednesday, December 19th 2007
10:00 am:
Thesis Defense in 435 Physics
Speaker: Paul Barsic
Subject: Thermodynamics, Triplets, and Transport: The Proximity Effect in Superconductor/Ferromagnet Nanostructures
This event will resume spring semester.

Thursday, December 20th 2007
This event will resume spring semester.
This event will resume spring semester.
This event will resume spring semester.

Friday, December 21st 2007
This event will resume spring semester.
This event will resume spring semester.
This event will resume spring semester.

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