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TREND Fair 2012

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August 3, 2012

2012 Group
2012 participants.
Top row (l-r): Diego Alcala, Joshua Brulé, Kevin Hu
Middle row: Carlos Blanco, Tyler Holland-Ashford, Michael Pretko. Bottom row: Justine Carryer, Alexandra Day, Emily Lim, Katherine Sytwu

On this page... TREND 2012 Presentations

Winners of TREND Fair 2012

Best Overall Project: "The Effects of Nanoscale Topography on Palladin Dynamics in Human Pancreatic Stellate Cells" by Kevin Hu, Duke University

Two projects were equally deserving to receive the award for Runner-Up for Best Overall Project:
"Explosive Percolation in Directed Networks," Diego Alcala, University of Northern Colorado, and Katherine Sytwu, Rutgers University
"Rejuvenation of a Cesium-Based Dispenser Photocathode in Response to Atmospheric Contamination," Alexandra Day, Wellesley College

HuThe Effects of Nanoscale Topography on Palladin Dynamics in Human Pancreatic Stellate Cells

(Presentation, Poster)

Kevin Hu, Duke University

Advisor: Assistant Professor Arpita Upadhyaya

Cell movement is a fundamental aspect of many cells' survival and functional capabilities. Recently, advances in technology have allowed us to transition from studying cell movement on glass to nanogrooved surfaces, which are more representative of the human body. We investigate the dynamics of the protein palladin, a key protein in the mechanics of cell movement, in human pancreatic stellate cells. The cells are plated onto the nanogrooves and put under a microscope. With a camera that is part of the microscope apparatus, we take time-lapse photos of a cell spreading to generate a movie. Because the palladin is fluorescent, we can then use MATLAB-based tracking software to calculate aspects of the palladin dynamics such as velocity.

trend photoExplosive Percolation in Directed Networks

(Presentation, Poster)

Diego Alcala, University of Northern Colorado & Katherine Sytwu, Rutgers University

Advisors: Assistant Professor Michelle Girvan, Professor Ed Ott, and Professor Thomas Antonsen

Complex networks arise in various areas of interest: power grids, gene regulation, information networks, etc. One important characteristic of complex networks is their ability to percolate, or form a giant component that connects a macroscopic fraction of the total network. Past research has shown that if connections are competitively added in undirected complex networks, the formation of a giant connected component can be delayed, resulting in a first-order transition known as explosive percolation. Generalizing that concept onto directed networks, we show that the giant out component also undergoes explosive percolation. Furthermore, we compare our findings with the corresponding undirected case.

trend photoRejuvenation of a Cesium-Based Dispenser Photocathode in Response to Atmospheric Contamination

(Presentation, Poster)

Alexandra Day, Wellesley College

Advisor: Dr. Eric Montgomery

Photocathodes produce high-energy electron beams that are well suited for use in free electron lasers (FELs). This project describes work to study and improve the quantum efficiency of cesium-based photocathodes for use in ship-based missile defense FELs. Particular emphasis is placed on quantifying the ability of a hybrid dispenser photocathode to recover from intentional atmospheric contamination. External and internal cesium deposition methods were studied throughout the project, as were the effects of different temperatures and pressures. Together the results of this project clarify the tolerance of certain photocathodes to intentional contamination and describe the related effects on quantum efficiency.

trend photoNonlinear Wave Dynamics in Charged Particle Beam Systems

(Presentation, Poster)

Carlos Blanco, Purdue University

Advisors: Dr. Brian Beaudoin and Research Professor Rami Kishek

A unique challenge for both heavy ion fusion drivers and free electron lasers is achieving the sufficiently low emittances and small energy spreads in the presence of intense space-charge to obtain the high deposition densities necessary for pellet ignition as well as the high average optical powers out of the undulator. The nonlinear dynamics of these intensely space-charge-dominated beams are explained by a one-dimensional cold fluid theory and its adaptation into a general form of the Korteweg-de Vries equation. Through systematic studies of both density and velocity perturbations, we were able to characterize and predict the conditions necessary to flatten these modulations by analyzing the structure of the perturbations prior to the onset of a solitary wave, producing precisely controlled and homogeneous charged particle beams scalable to larger machines.

trend photoPotential Flow Model of a Vortex Street near a Fish-Like Body

(Presention, Poster)

Joshua Brulé, University of Maryland College Park

Advisor: Assistant Professor Derek Paley

Kármán and reverse Kármán vortex streets are periodic flow patterns of alternating vortices that represent the flow behind a bluff body and a traveling fish, respectively. Using potential flow theory and Joukowsky airfoils, a simplified model of the vortex street flow near a fish-like body is constructed. The small number of parameters allows for the use of robust estimation techniques - such as recursive Bayesian estimation - to predict the vortex street behavior from velocity and/or pressure measurements. This information can be used to design controls for autonomous underwater vehicles to simulate station-holding behavior behind a bluff object, or to assist in autonomous schooling of several AUVs.

trend photoStudy of Atmospheric Breakdown by High-Power Microwave Pulses

(Presentation, Poster)

Justine Carryer, Colorado College

Advisor: Associate Research Scientist John Rodgers

Townsend discharge in air generated by a high-power microwave source (up to 2 kW) operating in the Ku-Band (12-18 GHz) is under investigation. The transient characteristics of microwave discharges through a tapered waveguide designed to concentrate field will be quantified to determine key plasma dynamical parameters such as permittivity, ionization and collision frequencies, skin depth, group velocity, decay rate, density, and plasma frequency (dispersion relation). A mixer will be used as a phase detector to measure the phase shift of the microwave as a result of transmission through the plasma. The measured phase shift will be the primary quantity characterizing plasma breakdown as a function of pressure, which will range from the sub-torr regime to about 250 torr, namely the high-pressure regime where w = nc. Free parameters are pressure, initial electron and ion densities, power, frequency, and pulse width. Results will be quantified and compared with theoretical predictions.

trend photoEffects of Weak Vacuum on Triboelectric Charging and X-Ray Emissions of Colliding Particles

(Presentation, Poster)

Tyler Holland-Ashford, Harvey Mudd College

Advisor: Professor Daniel Lathrop

Triboelectric charging is a phenomenon in which colliding particles become charged. Recent studies by C. G. Camara, S. J. Puttermanm, and J. R. Hird have shown that triboelectic collisions can also release x-rays when they occur under a vacuum. However, both of these process are not well understood. In this experiment we will expand the past research done on triboelectric charging in the Nonlinear Dynamics Laboratory of IREAP by putting the system in to a vacuum of 10-3 torr. We will determine the effect on charging as a function of pressure and also the effects on x-ray emission, if any.

trend photoStrain Effects on Impact Dynamics

(Presentation, Poster)

Emily Lim, Duke University

Advisor: Associate Professor Wolfgang Losert

We investigate how linear strain affects the impact dynamics of a spherical intruder into granular material by means of refractive index-matched imaging. We immerse glass beads in an index-matched, low-viscosity fluid, in which impacts behave similarly to a dry ensemble, and apply strain using a translatable wall prior to impact. Image processing allows us to plot penetration depth over time, as well as determine velocity flow fields for the perturbed system. Individual particles are tracked and analyzed for affine rearrangements, such as local strain, rotation, and dilation, and for nonaffine, plastic deformation.

trend photoInvestigation of the Transition from Sweet-Parker Magnetic Reconnection with Secondary Islands to Hall Reconnection

(Presentation, Poster)

Michael Pretko, Princeton University

Advisors: Associate Research Scientist Marc Swisdak and Professor James Drake

It has been known for several years that, for certain ranges of parameters, magnetic reconnection is bistable, i.e., a system can undergo either Sweet-Parker or Hall reconnection depending on the history of the system.