Events at Physics |
Events on Tuesday, October 6th, 2009
- Women of Wisconsin Strengthening Astronomy and Physics Colloquium
- The Two-Body Problem: Dual Career Couples in Science
- Time: 11:00 am
- Place: 3425 Sterling Hall (refreshments at 10:45)
- Speaker: Marc Sher, Department of Physics, The College of William and Mary
- Abstract: A decade ago, Laurie McNeil (now Chair of Physics at UNC) and I conducted a survey concerning dual career couples in physics. The response was overwhelming, and an extensive report was written (which has now been downloaded 40,000 times, and has had a significant impact on policy within federal agencies). The survey results will be discussed in detail, including the extent of the problem, a number of &quot;horror stories&quot;, and various suggested solutions (and, yes, some success stories). Recent developments in academia will also be discussed, as the institutional responses to the &quot;two-body problem&quot; have changed substantially in recent years.<br><br>
- Host: WOWSAP (Women of Wisconsin Strengthening Astronomy and Physics)
- Chaos & Complex Systems Seminar
- Simulation of swarming behavior using anti-Newtonian forces
- Time: 12:05 pm
- Place: 4274 Chamberlin (Refreshments will be served)
- Speaker: Vladimir Zhdankin, UW Department of Physics
- Abstract: The emergent behavior of swarming is investigated by using computer simulation. Each biological agent can be represented as a particle being influenced by forces due to the other agents in the system. A short-range repulsive force and long-range attractive force results in cohesive swarming behavior. However, more complicated dynamics can occur when two distinct species are defined to interact with different force laws. In order to recreate predator and prey swarming behavior that has been observed in nature, an "anti-Newtonian" force will be used between the two species, which violates Newton's Third Law. The resulting dynamics display a lush variety of features, including chaos and emergent behavior. The interesting cases will be demonstrated visually through animations that show the simulations unfold.
- Astronomy Colloquium
- Planetary Nebulae and the Structure and Kinematics of Galactic Disks
- Time: 3:30 pm
- Place: 3425 Sterling Hall
- Speaker: Robin Ciradullo, Penn State
- Abstract: Much of our understanding of dark matter halos comes from the largely-untested assumption that the mass-to-light ratio of spiral disks is constant is radius. To test this hypothesis, we have used planetary nebula kinematics to measure the disk mass surface density of five nearby, low-inclination spiral galaxies. We show that, in general, disks do have a constant M/L out to ~ 3 optical scale lengths, but once outside this radius, the vertical velocity dispersion of old disk stars is independent of distance. We suggest that this is due to the increased importance of a thick disk, and possible disk heating of the thin disk by dark halo substructure. We show that the disks of early type spirals have higher M/L values and are closer to maximal than the disks of later-type spirals, and that the residual unseen dark halos are better fit by pseudo-isothermal laws than by NFW profiles.