Events at Physics |
Events During the Week of September 14th through September 21st, 2014
Monday, September 15th, 2014
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Part I: Sustained spheromaks with ideal n = 1 kink stability and pressure confinement and Part II: The development of validation metrics using biorthogonal decomposition
- Time: 12:00 pm - 1:00 pm
- Place: 2255 Engineering Hall
- Speaker: Brian Victor, University of Washington
- Cosmology Journal Club
- An Informal discussion about a broad variety of arXiv papers related to Cosmology
- Time: 12:15 pm
- Place: 5242 Chamberlin Hall
- Abstract: Please visit the following link for more details:
http://cmb.physics.wisc.edu/journal/index.html
Please feel free to bring your lunch!
If you have questions or comments about this journal club, would like to propose a topic or volunteer to introduce a paper, please email Le Zhang (lzhang263@wisc.edu) - Host: Peter Timbie
- Council Meeting
- Canceled
- Time: 4:00 pm
- Place: 2314 Chamberlin (Chair's Conference Room)
Tuesday, September 16th, 2014
- Chaos & Complex Systems Seminar
- Cyclin-dependent kinase-confined cortical chaos
- Time: 12:05 pm - 1:00 pm
- Place: 4274 Chamberlin Hall (Refreshments will be served)
- Speaker: Bill Bement, UW Department of Zoology
- Abstract: Cytokinesis--the final step in cell division--is restricted to a discrete point in the cell division cycle referred to as "C-phase". In C-phase, the cortex of the cell is uniquely competent to respond to signals from the spindle by assembling the cytokinetic apparatus. C-phase follows anaphase onset and varies in length according to cell type. We have discovered that anaphase onset in frog and echinoderm embryos is associated with cortical excitability, manifest as waves of Rho activity and F-actin that traverse the underside of the plasma membrane. The waves are suppressed by cyclin dependent kinase 1 (Cdk1) and can be driven into a chaotic form when Cdk1 activity is experimentally suppressed. Remarkably, the excitability entails F-actin mediated Rho inhibition. We propose that C-phase is explained by the development of cortical excitability which is normally restricted to a discrete portion of the cell cycle Cdk1 and that excitability provides the cell with the means to balance the conflicting needs of speed, precision and flexibility during cell fission.
- Host: Clint Sprott
Wednesday, September 17th, 2014
- Department Meeting
- Canceled
- Time: 12:15 pm
- Place: 5310 Chamberlin Hall
Thursday, September 18th, 2014
- R. G. Herb Condensed Matter Seminar
- Continuum methods for understanding membrane protein stability
- Time: 10:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Michael Grabe, UC San Francisco
- Abstract: Experimental and computational studies have shown that cellular membranes deform to stabilize the inclusion of transmembrane (TM) proteins harboring charge. Recent analysis suggests that membrane bending helps to expose charged and polar residues to the aqueous environment and polar head groups. We previously used elasticity theory to identify membrane distortions that minimize the insertion of charged TM peptides into the membrane. Here, we extend our work to consider the energetics of ion and small peptide penetration into the membrane as well as large protein complexes. First, we show that our continuum method accurately reproduces energy profiles and membrane shapes generated from molecular simulations of bare ion permeation at a fraction of the computational cost. Importantly, we find that the energetics of membrane deformation strongly depend on membrane patch size both for ions and peptides. Finally, we present experimental and theoretical analysis that suggests that the antibacterial protein RegIIIa, a C-type lectin, forms channel like complexes that disrupt cellular homeostasis by inserting into membranes containing anionic lipids. We believe that our work presents a novel, computationally efficient method to simulate the effects of small molecules, peptides and large complexes with the membrane.
- Host: Robert McDermott
- Garage Physics Kickoff
- Time: 5:00 pm - 6:30 pm
- Place: B613 Sterling
- Speaker: Duncan Carlsmith, UW - Madison
- Abstract: Garage Physics is a flexible space for innovative student-focused research, education, and entrepreneurship.
- Host: Duncan Carlsmith & Brett Unks
Friday, September 19th, 2014
- Physics Department Colloquium
- Shedding Light on Distant Galaxies with 200,000 Quasars
- Time: 3:30 pm - 4:30 pm
- Place: 2241 Chamberlin Hall (coffee at 4:30 pm)
- Speaker: Britt Lundgren, UW Astronomy
- Abstract: Distant quasars backlight the Universe across most of cosmic time and can be used to reveal the evolving content and distribution of the cosmic web. Absorption features in quasar spectra mark the locations of gas in the intergalactic medium and provide sensitive physical tracers of many of the gaseous processes understood to regulate the evolution of galaxies. However, studying these distant absorbers in the context of their luminous counterparts (i.e., stellar populations) has long presented an observational challenge, which has hindered the ability of quasar absorption data to usefully inform galaxy evolution models.
The ~200,000 quasars observed to date by the Sloan Digital Sky Survey (SDSS) have recently catalyzed our understanding of the host galaxies and physical environments of the most prolific absorption species detected in optical quasar spectra. I will present recent statistical measurements made possible by the vast quasar absorption line samples from the SDSS, and present new, direct observations of absorber host galaxies at high redshift using the Hubble Space Telescope. Together these studies reveal compelling links between metal-rich absorbers and large-scale star formation-driven outflows, providing new insights into the role of feedback in the evolution of galaxies over the past 10 Billion years. - Host: Lawler