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«Strengthening the Nation through Diversity, Innovation & Leadership in STEM San Antonio,Texas · October 3-6, 2013 Get Connected! Connect with the ...»

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Interplay between upper ocean heat content, sea ice cover, and incoming solar radiation determines the perennial ice cover in the Arctic Ocean. Because of this balance, the local open water fraction strongly influences upper ocean heat flux. Determining floe size distribution is important for modeling the incoming solar radiation, since solar radiation readily heats the ocean in the absence of ice cover. Very high-resolution visible and synthetic aperture radar images are now available that show ice floes in great detail. We hypothesize that this imagery can be used to measure open water fraction in the ice pack at scales of 1 to 5000 m. We are developing algorithms in MATLAB to extract open water fraction data and floe size distribution from images taken near oceanographic buoys of interest. The algorithms combine image-processing techniques and manual input to accurately identify boundaries of ices floes within an image. Choices of thresholds to distinguish open water, melt ponds, and ice floes are described. The satellite images allow us to determine relationships between ocean heat fluxes and open water. With these algorithms we will be able to apply quantitative measures of open water fraction to assess the solar heat flux entering the ocean.

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SAT-181

SHELLS AND SWIMMING BEHAVIOR: ANALYSIS OF OLYMPIA OYSTER LARVAE EXPOSED TO OCEAN

ACIDIFICATION

Samantha Peart1, Shawn Arellano2.

North Carolina State University, Raleigh, NC, 2Shannon Point Marine Center, Western Washington University, 1 Anacortes, WA.

Drastic declines in native Olympia oyster populations along the West Coast of the United States have led to recent intensive restoration efforts. In addition to the inherent challenges of restoration, regional and global ocean acidification poses a threat to the reestablishment of native shellfish. Studies have shown that ocean acidification can decrease shell lengths of Olympia oyster larvae. The larval shell is a significant contributor to the larval swimming behavior of Olympia oysters and changes in the larval shell may cause changes in these behaviors. Cultures of 2-day-old larvae were cultured under high (1,000 ppm), moderate (750 ppm), and control (350 ppm) concentrations of CO2. After 4 days of exposure, larval swimming patterns were video recorded for later analysis of swimming behaviors. Larval samples were also collected from each treatment every 2 days to measure shell growth. There was a significant effect of treatment on length and number of swimmers (p 0.05), with significantly fewer in the high than in the moderate treatment. We could not detect a significant effect of treatment on swimming directional changes (p = 0.47). Preliminary results suggest that exposure to ocean acidification during the larval life of Olympia oysters may affect shell size and behavioral activity. Determining Olympia oyster larvae swimming behavior in response to future and regional climate changes will contribute to determining where these larvae move through the water column in order to identify where restoration efforts should be focused.

PHYSICS (EXCEPT BIOPHYSICS)

SAT-208

SPACETIME GEOMETRY AROUND AN ACCRETING, SPINNING BLACK HOLE

Kristina Pardo1, Edmund Bertschinger2.

Furman University, Greenville, SC, 2Massachusetts Institute of Technology, Cambridge, MA.

1 Spinning black holes and their accretion disks are objects of intense study by astrophysicists. The curved spacetime around a black hole, as well as the effects of its gravitation, are described by a mathematical object called the metric. While the metric of an isolated, spinning black hole has been known for decades, a metric that includes the gravitational effects of the accretion disk has yet to be found. Using the Kerr metric in Doran coordinates, we will solve for the motion of a spinning dust cloud near an uncharged, spinning black hole. We will then apply these equations of motion and the gravitational field equations to determine the effects of the gas cloud on the spacetime metric. Our goal is to find an approximate metric describing the accretion of a spinning gas cloud around a spinning black hole.

This metric will enable astrophysicists to more accurately predict the gravitational effects of an accreting, spinning black hole, and thus, more reliably identify accreting, compact objects.

SAT-207

EVALUATING THE FIELD EMISSION CHARACTERISTICS OF AL AND CU ELECTRODES FOR DC HIGH

VOLTAGE PHOTO-ELECTRON GUNS

Rhys Taus1, Matt Poelker2, Eric Forman2.

Loyola Marymount University, Los Angeles, CA, 2Center for Advanced Studies of Accelerators, Thomas Jefferson 1 National Accelerator Facility, Newport News, VA.

High-current photoguns require high power laser light, but only a small portion of the laser light illuminating the photocathode produces an electron beam. Most of the laser light (~65%) simply serves to heat the photocathode, which leads to evaporation of the chemicals required to create the negative electron affinity condition necessary for photoemission. Photocathode cooling techniques have been employed to address this problem, but active cooling of the photocathode is complicated because the cooling apparatus must float at high voltage. In this work, we evaluate





the field emission characteristics of cathode electrodes manufactured from materials with high thermal conductivity:

aluminum and copper. These electrodes could serve as effective heat sinks to passively cool the photocathode that resides within such a structure. However, literature suggests “soft” materials like aluminum and copper are ill suited for photogun applications because of excessive field emission when biased at high voltage. Our work provides an

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evaluation of aluminum and copper electrodes inside a high voltage field emission test stand before and after coating with titanium nitride, a coating that is very effective at enhancing surface hardness.

FRI-207

CHARACTERIZATION OF ULTRASHORT LASER PULSES USING OPTICAL AUTOCORRELATION ON A FREEELECTRON LASER

Daniel Inafuku, Eric Szarmes.

University of Hawaii at Manoa, Honolulu, HI.

Many everyday processes, from chemical reactions and molecular interactions such as photosynthesis to more specialized processes such as X-ray generation, occur on nearly imperceptible timescales. However, investigation into these short events requires even shorter events to measure them, presenting great challenges when studying phenomena on the order of trillionths of seconds. Some of the shortest man-made events are laser pulses, and using laser pulses to produce X-rays, in particular, poses interesting and troublesome problems due to the high power and optical resolution needed to produce these X-rays. Solutions to these problems can lead to new innovations in both basic and applied research, such as in the field of nonlinear optics, surface and photochemistry, interactions between radiation and biological systems, and new imaging capabilities for medical applications. In this study, we conducted an experiment using a broadly-tunable, free-electron laser (FEL) capable of producing a high-repetition-rate train of picosecond optical pulses. The temporal duration of these pulses was inferred from their spatial dimensions by generating autocorrelation functions after splitting the laser beam in an optical autocorrelator and examining the resulting signal after recombination. Introducing a series of time delays by altering the autocorrelator’s path length difference enabled us to produce a function that indicated the duration of the optical pulses, which we estimate on a theoretical basis to be less than 5 picoseconds. We present the results of these measurements and describe their application to X-ray generation at the University of Hawaii at Manoa.

FRI-205

STRANGENESS PRODUCTION IN JETS WITH ALICE AT THE LHC

Rodney Carmona Jr.1, Austin Harton1, Ron Soltz2, Abelev Betty2, Edmundo Garcia1.

Chicago State University, Chicago, Chicago, IL, 2Lawrence Livermore National Laboratory, Livermore, CA.

1 The study of strangeness production is integral to understanding high energy relativistic heavy ion Sciences Physical collisions. The measurement of production yields and particle ratios, dominated by the low energy region of the spectra, helps to understand the properties of the QCD medium created during the collisions. The baryon over meson ratio at intermediate pT allows the study of hadronization taking place as the medium evolves. Furthermore, the study of strange particles in collisions provides information on parton fragmentation, a fundamental QCD process. To establish a baseline, measurements are first performed in proton-proton (pp) data. However, the role of high-momentum observables is equally important to understanding QCD matter. Low- and midpT strangeness measurements are already in progress at RHIC (Relativistic Heavy Ion Collider) and the LHC (Large Hadron Collider), and it is imperative to extend these observables to higher pT. We propose to extract flavor characteristics, specifically strangeness, of jets, the high-pT early probes of heavy ion collisions. Starting with pp, we will measure the strangeness yields in jets to understand the particle fragmentation process, setting the basis for a study in the heavy ion data. In this poster, we will introduce the ALICE experiment (A Large Ion Collider Experiment). We will describe the methodology used for the data analysis and the current status of the data analysis will be presented.

SAT-206

CHARACTERIZING PLASMA GLOBE FILAMENTS

Gary Simmons, Michael Burin.

California State University, San Marcos, San Marcos, CA.

Plasma, the fourth state of matter, is defined as an ionized gas. Commonplace plasmas can be found in nature, such as lightning and auroras, and industry, such as fluorescent and neon lights. Filamentary structures have been

257 UNDERGRADUATE POSTER ABSTRACTS

observed as an interesting phenomenon in plasmas; yet, various aspects of filament formation physics remain unclear. An example of plasma filamentation can be found in toy plasma globes. Commonly available commercial globes are 95% neon and 5% xenon at a pressure near 740 Torr. Plasma globes are typically supplied with a 5kV, 60 kHz electric signal. However, the reason why these conditions are favorable for filamentary structures is unknown. This research will investigate if the ratio of xenon to neon gas affects plasma filament characteristics. In particular, the work will test whether filament morphology (i.e., thickness and branching as a function of radius) alters gradually as xenon percentage increases, or alternately requires a threshold percentage of Xenon for a significant observable change. A sensitive CCD camera will be used to analyze filament number and morphology. These filament characteristics will be measured at various xenon-neon ratios inside a 1.8 liter custom plasma globe. Thus, the study expects to find characteristics such as average filament diameter, branching radius, and filament number changing as a physical function proportional to the xenon-neon gas ratio. Our characterization of the filaments will be ultimately used to understand plasma filamentation phenomena in both nature (e.g., atmospheric sprites) and industry (e.g., dielectric barrier discharges).

FRI-209

KA PIKO O O‘AHU, KŪKANILOKO: THE CENTER OF O‘AHU, KŪKANILOKO

Maria Petelo, Tiffanee Pahia, Herve Collin, Keolani Noa.

Kapiolani Community College, Honolulu, HI.

In the Kanaka Maoli (Hawaiian) culture, Kūkaniloko is one of Hawai‘i’s most sacred places. This location is designated as the birthplace for all ali‘i, or chiefs, dating back to the 12th century, and, as such, represents the Piko, or source of life, of the island of Oʻahu. Kūkaniloko contains many different stones, some of which were calendrical markers noting the dates of conception and predicted birthdates of chiefs. The connection between Kanaka Maoli and the ʻāina, or land, is familial and, because of this, Kūkaniloko is particularly sacred in the Hawaiian culture as it signifies the center from which life springs forth. The purpose of this research is to confirm the location of Kūkaniloko as the center of mass of the island of O‘ahu using the scientific method. Grid references, global positioning system (GPS), and calculation of center of mass were applied to validate that Hawaiians have an understanding of the scientific concept of mass and applied this knowledge in designating Kūkaniloko as the Piko of Oʻahu, both literally and culturally.

Assuming the Earth’s density to be an invariant quantity, elevations were measured at the center of each grid square using Google earth and applied as weighted position coordinates. Results show that the center of mass of O‘ahu, computed using scientific tools, converges towards Kūkaniloko’s location as the precision of the grid is increased.

Preliminary outcomes suggest ancient Hawaiian knowledge of scientific methods for choosing Kūkaniloko as the Piko of Oʻahu.

FRI-206

ENHANCING THERMOELECTRIC EFFICIENCY WITH GATED SILICON NANOWIRES

Emilio Codecido, Benjamin Curtin, John Bowers.

University of California Santa Barbara, Santa Barbara, CA.



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