Events at Physics

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Events During the Week of April 3rd through April 10th, 2011

Monday, April 4th, 2011

Plasma Physics (Physics/ECE/NE 922) Seminar
"Have Process will Travel: Adventures in Plasma Astrophysics"
Time: 12:05 pm
Place: 2241 Chamberlin Hall
Speaker: Anatoly Spitkovsky, Princeton University
Abstract: As plasmas underly most of astrophysical phenomena, understanding how
the relevant plasma processes operate in detail can, in principle,
provide powerful constraints on astrophysical models. In practice,
such applications have been non-trivial due to the disparity of scales
between plasma microphysics and astronomical environments. I will
present several examples of situations where the intrinsically
microscopic physics has a direct imprint on macroscopic
observables, and show how the improved models of plasma physics can
guide the development of astronomical scenarios. Examples will be
drawn from particle acceleration in collisionless shocks, relativistic
reconnection in pulsars, and the decay of magnetized turbulence in
accretion disks.
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Tuesday, April 5th, 2011

Chaos & Complex Systems Seminar
"A New Dynamical Mechanism for Major Climate Shifts"
Time: 12:00 pm
Place: 4274 Chamberlin Hall
Speaker: Anastasios Tsonis, UW-Milwaukee Department of Mathematical Sciences
Abstract: We construct a network of observed climate indices in the period 1900-2000 and investigate their collective behavior. The results indicate that this network synchronized several times in this period. We find that in those cases where the synchronous state was followed by a steady increase in the coupling strength between the indices, the synchronous state was destroyed, after which a new climate state emerged. These shifts are associated with significant changes in global temperature trend and in ENSO variability. The latest such event is known as the great climate shift of the 1970s. We also find the evidence for such type of behavior in three climate simulations using a state-of-the-art model. This is the first time that this mechanism, which appears consistent with the theory of synchronized chaos, is discovered in a physical system of the size and complexity of the climate system.
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Wednesday, April 6th, 2011

No events scheduled

Thursday, April 7th, 2011

No events scheduled

Friday, April 8th, 2011

Physics Department Colloquium
Ingersoll Lecture
Beauty in Complexity: Low Friction and Adsorption Properties of Quasicrystal Surfaces
Time: 4:00 pm
Place: 2241 Chamberlin Hall (coffee at 3:30 pm)
Speaker: Pat Thiel, Iowa State University
Abstract: Quasicrystals are metallic alloys or intermetallics which have an unconventional atomic structure. They are well-ordered on an atomic scale, but not periodic, and they often exhibit so-called forbidden rotational symmetries. This atomic structure engenders unusual surface properties and surface phenomena. Examples come from the morphology of films grown on quasicrystals. The unusual features include nucleation at trap sites that are intrinsic to the surface structure, and a quantum size effect that drives the formation of mesa-like structures. Another example is low friction, which arises (at least in part) from the quasiperiodic atomic structure. Yet another example is the development of defect sites, which can form at the surface and propagate a defective stacking sequence in toward the bulk These unusual features all are consequences of the beautiful - and sometimes maddeningly complex - atomic structure of these metallic alloys.
Host: Bruch
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