Events Archive

Feb
04
2013
Consider the Icicle
Icicles are harmless and picturesque winter phenomena, at least in cold climates.  The shape of an icicle emerges from a subtle feedback between ice formation, which is controlled by the release of latent heat, and the flow of water over the evolving shape.  The water flow, in turn, determines how the heat flows.  The air around the icicle is also flowing, and all forms of heat transfer are active in the air.  Ideal icicles are predicted to have a universal "platonic" shape, independent of growing conditions.  In addition, many natural icicles exhibit a...
Feb
02
2013
Squishy Physics 2013
  FREE TICKETS AVAILABLE FOR A LIMITED TIME AT www.squishyphysics.eventbrite.com  
Feb
02
2013
Phase Transitions in Food
Manipulating the texture of foods is central to cooking.  One common manipulation is to induce a phase transition, for example, from a solid to a liquid state, which can occur both during cooking and eating.  In understanding the phase behavior of food materials, we will consider the protein, carbohydrate, and fat molecules that are components of foods that we eat.  Interestingly, these same molecules can also impart unique physical properties to plants and animals, which are critical...
Jan
31
2013
Detonating Superbursts on Neutron Starts: from a Shocking Start to a Long Tail
Superbursts are the most powerful repeating thermonuclear flashes observed from accreting neutron stars. Runaway thermonuclear burning of carbon ignites deep in the star's envelope. Close to the crust, superbursts are sensitive to the ill-understood nuclear physics processes in dense neutron-rich matter. We present the latest numerical simulations of carbon burning. Comparing the tail of the simulated lightcurve to observations constrains the depth of carbon ignition, whereas the start exhibits the signs of a shock caused by detonation. Recently increasing observational evidence points at interaction between X-ray bursts and the accretion disk. As the most powerful X-ray bursts,...
Jan
31
2013
Interchanging the Roles of Light and Matter
Atom interferometers that use pulses of light for coherent control of matter-wave interference can be used for wide ranging studies of light-matter interactions and for realizing precision measurements in atomic physics. We describe an echo type interferometer that utilizes a relatively simple setup to manipulate laser-cooled Rb atoms in a single ground state manifold. We review progress toward a precise determination of the atomic fine structure constant and gravitational acceleration. *Work supported by CFI, OIT, OCE, NSERC and York University
Jan
30
2013
Direct Determination of Time Varying Flow Structures
PLEASE NOTE: This is a WEBINAR Scientists for years have been trying to better understand the mechanisms that are responsible for transport and mixing in fluid flow.  Mixing is important as it is used in everything from food preparation to energy production to biomedical devices, and is seen in both single and multiphase environments.  While mixing applications are wide ranging, a complete and proper understanding of mixing and transport mechanisms is still lacking....
Jan
29
2013
Biofilms Suck and Epithelial Cells Blow: Forces in Multi-cellular Systems
Multicellular behavior in bacterial biofilms is intimately tied to the production of an extracellular polysaccharide (EPS) matrix that encases the cells and provides physical integrity to the colony as a whole.  As a colony grows from a few cells into a biofilm, a sudden increase in EPS production generates osmotic stresses that cause the biofilm to expand. Moreover, EPS production is triggered by a nutrient depletion gradient that develops in the biofilm due to diffusive mass transport limitations. These polymer physics based biofilm behaviors...
Jan
29
2013
Localized patterns and traveling waves in reaction-diffusion systems
PLEASE NOTE: This is a WEBINAR Two topics in pattern formation for reaction-diffusion equations will be addressed in this talk.  In the first, I will discuss the existence proof for stationary localized spots in the planar and the three-dimensional Swift--Hohenberg equation using geometric blow-up techniques. The spots have a much larger amplitude than that expected from a formal scaling in the far field. One advantage of the...
Jan
28
2013
"How Do Chipper, Kobe, Serena and Rory Do It? What Physics Has to Say About Achievements in Sports"
A great part of physics deals with motion, and the essence of sports is the human body in motion.  The components of the human body that produce motion, namely the skeletal muscles and bones, and the sports equipment itself are bound by the laws of physics.  Aspects of various sports, including baseball, basketball, karate, figure skating, golf, tennis, long jump, and more, will be examined using introductory-level physics.  We will also discuss whether we have reached our limits in human performance in certain sports.  All who appreciate the workings of the human body and the...
Jan
24
2013
The Dark and the Light: Black Holes, Dark Halos, and their Influence on Galaxy Evolution
Supermassive black holes are amazingly exotic and yet ubiquitous objects, residing in the centers of essentially all stellar bulges in galaxies. Recent years have seen remarkable advances in our understanding of how these black holes form and grow over cosmic time, and how energy released by active galactic nuclei (AGN) connects the growth of black holes to their host galaxies and large-scale structures. I will review some recent work that explores these connections, with a focus on statistical studies of AGN clustering and the links between black hole growth and and star formation. I will highlight some new insights into how and when AGN "feedback" is important for galaxy...

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