Events

## SMARTech Video Archive

Dec

06

Advances in microscopy have enabled measurements in living cells, but there is a wealth of biologically relevant dynamical information contained in experimental data that has not been utilized. Existing analysis methods either coarse grain too much or cannot overcome some technical challenges inherent to *in vivo* measurements. The importance of more fully utilizing information “hidden” in noisy 3D *in vivo* measurements will be emphasized in several problems. In this talk, I demonstrate how recent advances in time series analysis can be used to estimate stochastic differential equations (SDEs) and construct hypothesis tests checking the consistency...

Nov

30

We consider the Universe to be fundamentally quantum and statistical, the many-paths/many-worlds information-theoretic story. This lecture uses Cosmic Information Theory and Analysis, CITA, as a unifying theme to explore the vast sweep of our current ideas of the Universe and the experiments we use to probe them, ranging from the ultra-early beginnings to our far-future fate. I describe the intimate entanglement of theory with precision "first-light" and other cosmic data, in particular from the satellite Planck and the Andes-based ACT. Such data are the BITs in IT informing us of the physics that defines the BIT of the Universe...

Nov

17

We present a Hamiltonian derivation of a class of reduced models in plasma physics obtained by imposing dynamical constraints on a parent Hamiltonian model. We will consider MHD equations and Maxwell-Vlasov equations as parent models. It is shown that the Poisson bracket associated with these reduced models is the Dirac bracket obtained from the Poisson bracket of the parent model.

Nov

16

A cell is not just a small test tube in which biochemical reactions take place, but it also has a complex and highly dynamic mechanical structure. I will discuss the underlying physical principles that govern cellular mechanics on the nanoscale, and explore how DNA mechanics, on its own and within the context of a heavily crowded, constrained and perpetually fluctuating cellular environment, affects biological function. For example, forces of less than hundred femtonewtons can mechanically switch genes on and off by preventing the formation of regulatory DNA-protein complexes. Special emphasis will be placed on the role of intracellular fluctuations and...

Nov

10

The Kepler Mission, NASA Discovery mission #10, is specifically designed to survey a portion of our region of the Milky Way galaxy to discover dozens of Earth-size planets in or near the habitable zone and determine how many of the billions of stars in our galaxy have such planets. Results from this mission will allow us to place our solar system within the continuum of planetary systems in the Galaxy.

Nov

10

Superconducting Josephson Junctions are one of the most active areas of research in Condensed Matter Physics today. One unique aspect of Josephson Junctions is the nonlinear relation between the phase of the wave function and the supercurrent flowing though the junction. This manifests itself in a nonlinear, pendulum-like equation for the dynamics of the phase when the junction is placed in circuit. Josephson junctions can be fabricated with adjustable parameters, measured in a straightforward fashion, and easily scaled to large network sizes. In addition, a large Josephson junction circuit measured over a long time contains dynamics...

Nov

09

Most biological processes are mediated by mediated by protein association, and often are under kinetic rather than thermodynamic control. We have developed the transient-complex theory for protein association, which presents a framework for elucidating the mechanisms of protein association and for predicting the association rates. The transient complex refers to an intermediate along the association process, in which the two associating molecules have near-native separation and relative...

Nov

08

Ion channels play vital cellular functions. How an external simulation (e.g., cross-membrane voltage, binding of a ligand, or decrease in external pH) triggers the opening of an ion channel is at the core of its functional mechanism. We have used molecular dynamics simulations and other computational techniques to develop models for the functional mechanisms of several ion channels, including a nicotinic acetylcholine receptor, an AMPA-subtype glutamate receptor, and the M2 proton channel of the influenza virus. A very useful way to validate these mechanistic models is to compare changes in residue solvent...

Nov

07

The Vlasov-Poisson and Vlasov-Maxwell equations possess various variational formulations or action principles. I will discuss a particular variational principle that is based on a Hamiltonian-Jacobi formulation of Vlasov theory, a formulation that is not widely known. I will show how this formulation can be reduced for describing the Vlasov-Poisson system. The resulting system is of Hamilton-Jacobi form, but with nonlinear global coupling to the Poisson equation. A description of phase (function)space geometry and relation to Hamilton-Jacobi PDE methods and weak KAM will be given.

H. Ye and P. J. Morrison Phys. Fluids 4B, 771 (1992). D. Pfirsch, Z. Naturforsch....

Nov

02

Oct

31

Winner of the Nobel Prize in Physics in 2007, Fert speaks about his work in spintronics.

Oct

31

*Albert Fert, Nobel Prize in Physics 2007*

*Joint colloquium between the School of Physics and MRSEC*

Spintronics exploits the influence of the electron spin orientation on electronic transport. It is mainly known for the “giant magnetoresistance” (GMR) and the large increase of the hard disc capacity obtained with read heads based on the GMR, but it has...

Oct

28

A quantum computer uses superposition states to accomplish tasks (e.g., database search and factoring of integers) more efficiently than any known classical computing strategy. In conventional registers for quantum information processing, quantum bits are associated with individual two-level quantum systems. Separate addressing and interaction with these systems permit one-bit gates, while an interaction between systems is needed

to accomplish two-bit gates.

The seminar will review recent theoretical proposals to implement quantum computing in collective excitation degrees of freedom in ensembles of

identical quantum systems. In these proposals one does not address...