SUNMONTUEWEDTHUFRISAT
Conferences, Lectures, & Seminars
Events for January
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AME Dept. Seminar
Wed, Jan 12, 2011 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Elisa Franco , Graduate Student
Talk Title: Programming Molecular Networks
Abstract: How do living organisms process information and implement their responses to external stimuli? Even in the simplest cells, sensing, computation and actuation are structurally embedded in the biochemistry of complex molecular networks, and we need to develop new paradigms to explain and engineer such structures. Quoting Richard Feynman, what we cannot create, we do not understand: by programming and building simple molecular networks from the bottom-up, scientists have an opportunity to gain insight into the design principles of more complicated, naturally occurring circuits.
In this talk, I will describe how DNA and RNA can be used as simple building blocks to construct molecular circuits encoding complex functionalities, because their interactions can be predicted and specified with high confidence. In particular, we have used nucleic acids to investigate two challenges: synchronization and scalability of biochemical networks. I will describe how the activity of two synthetic genes can be matched, by using their outputs to create positive or negative feedback loops. Scaling up our perspective, to synchronize the operations of a larger number of circuits we may need "timing" devices: for instance, digital clock generators coordinate the state transitions of millions of silicon circuits. I will describe how a tunable synthetic oscillator can be used to time the conformation of a DNA nano-mechanical device called "DNA tweezers," evaluating several modes of connection. Because the biochemical interconnections are created by stoichiometric binding of our oscillator components and its "load" components, we observed a remarkable deterioration of the oscillator behavior as we increased its load concentration. To reduce this undesired retroactivity we engineered an "insulator circuit", the molecular equivalent of an operational amplifier, which improves the modularity and scalability of the system. To our knowledge, this is the first experimental attempt to use a synthetic biochemical oscillator to drive several types of downstream processes, in a plug-and-play fashion.
Biography: Elisa Franco is currently a graduate student at the California Institute of Technology, in the Department of Control and Dynamical Systems. She got her Laurea degree in Power Systems Engineering from the University of Trieste, Italy, where she also earned a PhD in Automatic Control. Her current research interests are in the field of synthetic and systems biology.
Host: Prof. Eva Kanso
More Info: http://ame-www.usc.edu/seminars/1-12-11-franco.shtmlLocation: Seaver Science Library (SSL) - 150
Audiences: Everyone Is Invited
Contact: April Mundy
Event Link: http://ame-www.usc.edu/seminars/1-12-11-franco.shtml
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AME Dept. Seminar
Wed, Jan 19, 2011 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Prof. Alfredo Sedun, University of Southern California
Talk Title: Engineering the Human Eye
Abstract:
The human eye reflects elements of design that represent an interesting tension between the rules of evolution (you need a path between steps and each step must at least not have a negative value added) and all sorts of tradeoffs between benefits that would have selection value. We will look at this process by asking how we might design such a system taking the following steps.
1) How big should it be?
a. Too small and you have >1.2mm aperture limit of diffraction
b. Too large and itâs neurologically (and metabolically) expensive
2) Do you grow it after birth (axial length changes require new focal lengths)?
3) How many pixels (separation of less than 30 seconds of arc = diffraction gratings)?
4) Scotopic vs Photopic (predator or prey)?
5) Transient or sustained (integrating over space or time)?
6) Duality approach of M & P cells (How is the hawk eye superior?)
7) Color vs B&W
8) How many color cones do we want (predator vs prey)?
9) Did you forget the heat sink?
10) Super-sustained RGCs (melanopsin) for
a. Pupils
b. Circadian rhythms
How do you get there from here: 10 step plan notwithstanding that evolution doesnât have a trajectory.
1) Discriminating light vs dark = photopigment on a membrane (phototaxis and circadian rhythm)
2) Direction of light (light wall or just a cup)
3) Focus for better resolution (almost close the cup for pinhole aperture)
4) Maintain transparency (close with cornea, use aqueous and vitreous and IOP for sphere).
5) Movable iris to increase light
6) Lens to focus when pupil is not a pinhole
7) Deal with optic nerve that leaves the eye and makes a big blind spot (how do you keep the pressure in when you have an exit?).
8) Put psychophysical filters into the eye to decrease data and limit optic nerve head size by using Bipolars, Horizontals, Amacrine). Edges matter more than filler.
9) Fovea and eye movements
10) M & P cell parallel processing
Biography: Flora Thornton Chair of Vision Research, Professor of Ophthalmology and Neurological Surgery, Doheny Eye Institute, USC-Keck School of Medicine
Host: Professor Firdaus Udwadia
Location: Seaver Science Library (SSL) - 150
Audiences: Everyone Is Invited
Contact: April Mundy
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AME Department Seminar
Wed, Jan 26, 2011 @ 03:30 PM - 04:30 PM
Aerospace and Mechanical Engineering
Conferences, Lectures, & Seminars
Speaker: Joanna M. Austin, Assistant Professor, Department of Aerospace Engineering, College of Engineering, University of Illinois at Urbana-Champaign, IL
Talk Title: The Role of Thermochemistry in Hypersonic Shear Flows
Abstract: In high enthalpy hypersonic flight, thermochemical relaxation times are typically comparable to flow residence times, leading to nonlinear coupling between chemical reactions, vibrational excitation, and fluid mechanics. The chemical species and internal energy of the gas depart significantly from equilibrium. Experimental data in hypervelocity flows are scarce, partly because creating high enthalpy conditions in ground test facilities is extremely challenging and flight tests are expensive.
A new expansion tube facility capable of test gas Mach numbers from 3.0 to 7.4 has been built at Illinois and carefully characterized with experimental measurements and numerical simulations. Two canonical shear flows are being examined in the high enthalpy free stream: triple-point generated free shear layers and boundary layers flows. Initial experiments identified an opposing wedge configuration used to generate a Mach reflection with associated triple-point shear layers. The experimental configuration is chosen to give well-characterized inflow and boundary conditions. In addition, a Mach reflection results in a shear layer that separates a gas stream that has passed through a normal shock from a gas stream that has passed through two oblique shocks, leading to dramatically different temperatures and degree of dissociation across the shear layer. Key diagnostic tools include spectroscopic measurements confirming the presence of dissociated NO behind the Mach reflection, flow visualizations, and temperature measurements benchmarked against calculations using detailed and reduced chemical kinetic mechanisms.
The experimental work is complemented by spatial linear stability analysis. This study is the first linear stability analysis of a hypersonic shear layer to include detailed modeling of molecular effects. An existing molecular-molecular energy transfer rate model is extended to higher collisional energies. Non-equilibrium model results are compared with calculations assuming equilibrium and frozen flow over a range of (frozen) convective Mach numbers from 0.341 to 1.707. Non-equilibrium effects appear in the creation of nitrous oxide due to dissociation. Dissociation and vibration transfer effects on the perturbation evolution remain closely correlated at all convective Mach numbers.
Biography: Joanna Austin is an Assistant Professor in the Aerospace Engineering Department at the University of Illinois at Urbana-Champaign. She received B.E. (Mechanical and Space Engineering) and B.Sc. (Mathematics) degrees from the University of Queensland, Australia in 1996 and 1997, and M.S. and Ph.D. degrees from GALCIT at the California Institute of Technology in 1998 and 2003. She directs the Compressible Fluid Mechanics Laboratory at Illinois, where her research interests include hypervelocity flows, bubble collapse under dynamic loading, detonation, compressible geological flows, and experimental fluid mechanics. Honors and awards include the Richard Bruce Chapman award for distinguished research in hydrodynamics in the Engineering and Applied Sciences Division at Caltech, 2003, the Young Investigator Award from the Air Force Office of Scientific Research, 2007, and the National Science Foundation CAREER award in 2010.
Host: Prof. V. Eliasson
More Info: http://ame-www.usc.edu/seminars/1-26-11-austin.shtmlLocation: Seaver Science Library (SSL) - 150
Audiences: Everyone Is Invited
Contact: April Mundy
Event Link: http://ame-www.usc.edu/seminars/1-26-11-austin.shtml