Undergraduate Research Symposium May 21, 2010 Mary Gates Hall Online Proceedings

Silicon Nanophotonic Waveguides for the Mid-Infrared POSTER SESSION 1 Alexander Weber (Alexander) Spott, Senior, Electrical Balcony, Easel 134 Engineering, Mathematics (Comprehensive) Mary Gates Scholar 12:00 PM to 1:00 PM Andrew Weber (Andrew) Spott, Senior, Physics In Situ Calibration of Magnetic Probes in a Flux Mary Gates Scholar Conserver Mentor: Michael Hochberg, Electrical Engineering Cosmo Lucas (Cosmo) Smith, Senior, Physics, Computer It has been demonstrated that silicon nanophotonic waveg- Science, English (Creative Writing) uides can be used to construct all of the components of a pho- Mary Gates Scholar, NASA Space Grant Scholar tonic data transmission system on a single chip. Complex Mentor: Simon Woodruff, Woodruff Scientific electro-photonic integrated circuits can be constructed from With an exponentially increasing global population, the ne- the integration of nanophotonic waveguides and CMOS elec- cessity of finding renewable and sustainable energy sources tronics. It has also been shown that the high field confinement is becoming unavoidable. Plasma fusion provides a highly of silicon nanoscale guides enables a variety of new applica- promising, virtually inexhaustible and environmentally be- tions, including chip-scale nonlinear optics, as well as biosen- nign energy source by using particles heated to over 100 mil- sors and light-force activated devices. Currently, the majority lion degrees Celsius to run a power plant. Fusion is still in de- of experiments with silicon waveguides have been at wave- velopment, however, due to a number of technical difficulties, lengths in the near-infrared, between 1.1-2 µm. Our research chief among which is confinement and sustainment of the su- demonstrates that by using a material system which lacks a perheated particles, also known as plasma. In the analysis of high index substrate, single-mode silicon nano-waveguides confined plasma, magnetic inductive probes are essential for can be used at mid-infrared wavelengths, in particular at 4.5 their ability to reveal information about plasma shape, posi- µm, or 2222.2 cm−1. This idea has appeared in theoretical tion and current density without physically interacting with literature, but experimental realization has been elusive. This the plasma. Magnetic inductive probes are vital to sphero- result represents the first practical integrated waveguide sys- maks – devices used to contain plasma - for real-time control tem for the mid-infrared in silicon, and enables a range of of the plasma along with reconstruction of its equilibrium. new applications. The magnetic diagnostic system in our experiment includes 50 probes embedded in the surface of a copper flux conserver surrounding the plasma. These probes are arranged in 25 POSTER SESSION 1 probe-pairs that measure both toroidal and poloidal magnetic MGH 241, Easel 180 fields. Due to attenuation effects on the magnetic field by the 12:00 PM to 1:00 PM copper, the probes on the flux conserver must be calibrated in situ. This is accomplished by performing two simulations in Model of Chromosome Movement During Cell Division which a toroidal and a poloidal field are independently gen- Suggests that a Viscoelastic Linkage Coordinates Paired erated. By testing at several different frequencies, the attenu- Sister Chromatids ation effect on the magnetic probes can be characterized and Carol Jessica Huseby, Senior, Physics, Biology (Physiology) the probes can be accurately calibrated. Proper calibration is NASA Space Grant Scholar a necessary step towards precise plasma measurements and, Mentor: Charles Asbury, Physiology and Biophysics ultimately, towards an understanding of how confined plas- Mentor: Anton Andreev mas can be sustained. Birth defects and cancers can occur if the genetic material in cells, the DNA, is not segregated properly during cell divi- POSTER SESSION 1 sion. Replicated DNA is packaged into joined chromosome pairs, called ‘sisters’, which make attachments to the tips of Balcony, Easel 123 microtubule filaments through specialized structures, called 12:00 PM to 1:00 PM kinetochores. Sister kinetochore pairs then make oscillatory movements driven by the stochastic lengthening and shorten-

Undergraduate Research Program 1 exp.washington.edu/urp ing of the microtubules to which they are attached. To explain how the movements of sisters are coordinated, a ‘push-pull’ POSTER SESSION 1 model has been proposed where the dynamics of kinetochore- Commons West, Easel 70 attached filaments are regulated by forces transmitted through 12:00 PM to 1:00 PM the packaged DNA that links the sisters together. Here we show that the simplest version of this model, in which the An Examination of K-12 Teacher Understanding of linkage is assumed to be purely elastic, fails in computer sim- Limits in the Context of Kinematics ulations to reproduce the near-perfect coordination of sisters Alexis Rebecca Werner (Alexis) Olsho, Fifth Year, Physics seen in cells. Furthermore, by tracking sister kinetochores in NASA Space Grant Scholar high-resolution movies of live cells, we find that the prob- Mentor: Peter Shaffer, Physics ability for a kinetochore to reverse direction correlates not Mentor: MacKenzie Stetzer, Physics only with the distance separating it from its sister, but also The Physics Education Group (PEG) in the Physics Depart- with the direction that its sister is moving. The latter im- ment at the University of Washington is involved in research, plies that microtubules attached to one kinetochore somehow curriculum development, and instruction aimed at improving ‘sense’ whether those attached to the sister kinetochore are student learning in physics. Part of the work involves helping growing or shrinking. This effect, and the highly coordinated prepare K-12 teachers of physics and physical science. To movement of sisters observed in cells, can be reproduced in this end, the group is developing an inquiry-based curricu- computer simulations assuming the sisters are connected with lum, Physics by Inquiry (PbI), designed to strengthen subject a material in which its effective stiffness can change with the matter background in physics and physical science. I worked rate of sister separation. We therefore propose that sister kine- at the 2009 NSF Summer Institute for Inservice Teachers, an tochore movements during cell division are coordinated by intensive 5-week program that used the PbI curriculum. I in- inter-kinetochore forces transmitted through viscoelastic ma- vestigated participant conceptual understanding of mathemat- terial between sisters. ical limits primarily in the context of kinematics, as well as in the context of electric circuits. The project began by con- POSTER SESSION 1 ducting a detailed examination of pretests and post-tests from Commons West, Easel 53 previous summers. These indicated that many K-12 teachers are unable to use limiting procedures when presented with 12:00 PM to 1:00 PM information in non-graphical form. By developing additional Sharing the Sky: Using Social Technologies for Scientific pretests and post-tests that were administered to the 2009 par- Collaboration ticipants, we gained insight into participant understanding be- Ian Michael (Ian) Smith, Junior, Physics, Astronomy fore, during, and after instruction. The in-depth analysis of Mentor: Andrew Connolly, Astronomy participant responses throughout the summer helped us assess the effectiveness of the PbI curriculum in kinematics in As enormous amounts of data are collected by the large mul- general, with a particular focus on the teaching of limit con- tispectral survey programs such as Sloan Digital Sky Sur- cepts in the context of velocity and acceleration. This detailed vey (SDSS), and soon the Large Synoptic Survey Telescope analysis of the prevalence of various types of errors has pro- (LSST), we are faced with the challenge of finding a way to vided a deeper understanding of the difficulties that teachers meaningfully interact with this data to maximize scientific face when learning the material, is guiding the further de- return. Our goal is to create a flexible environment that or- velopment of curriculum, and is contributing to the existing ganizes disparate data sources, such as streamed images and research base on the learning and teaching of physics. database services, to be analyzed visually through the coordination of simple tools that work on common data. We envi- sion a framework that allows users to personalize their access POSTER SESSION 1 to data and to easily create custom tools to interact with and Commons West, Easel 72 import data from new sources. The web browser is a natural 12:00 PM to 1:00 PM place to create such an environment, and by leveraging the OpenSocial API we extend our model to allow collaboration A High-Power 556nm Source for Laser Cooling of between astronomers remotely. In addition to enhancing ac- Ytterbium Atoms cess to data among astronomers, the web application will be Jiawen Pi, Senior, Physics available to the public, encouraging exploration of the sky. Mentor: Subhadeep Gupta, Physics Mentor: Vladyslav Ivanov, Physics

The ﬁne structure constant is a fundamental scientiﬁc quan- tity because it characterizes the strength of the fundamental

2 interaction between light and matter. Cold ytterbium (Yb) tified as BAL QSOs in SDSS and we subsequently observe atoms are promising candidates for accurate measurements them with FAST across 3 consecutive nights, and then on day of this constant using atom interferometry techniques. It is 9, 27, and 81. Additional observations are acquired for 1 and possible to cool Yb atoms to temperatures of few micro- 2 year cadences. We also obtain a set of control non-BAL Kelvin using coherent laser radiation. This is achieved by us- quasar spectra, in which we expect to see little or no variabil- ing laser cooling, where atomic motion is cooled by counter- ity. We assess the magnitude of the variability in the observed propagating resonant laser light at 556nm (green), a wave- spectra of our BAL QSOs and determine which constraints length not easily reachable by common laser sources. There- our investigations can put on the outflows impacting the BAL fore, a laser source should be developed to perform laser cool- region. ing of Yb on this transition. Light at 556nm can be pro- duced by second harmonic generation (SHG) or “frequency doubling” of light at 1112nm (the fundamental). In SHG, POSTER SESSION 1 a medium doubles the frequency of incident light through Commons West, Easel 51 a non-linear process. In this project, we use a lithium tri- 12:00 PM to 1:00 PM borate (LBO) crystal heated to 100 degree C to achieve the phase-matching for frequency doubling of an 1112nm fiber Twinkle, Twinkle Little Star, or are You a Quasar? laser source. Since the efficiency of the non-linear process Keira Jayne (Keira) Brooks, Senior, Astronomy, Physics is strongly dependent on the intensity of the fundamental, NASA Space Grant Scholar we will increase the available 1112nm intensity using a res- Mentor: Zeljko Ivezic, Astronomy onant build-up cavity around the LBO crystal. So far, we Mentor: Chelsea MacLeod, Astronomy have constructed a temperature stabilized crystal oven, and Quasars are fascinating objects whose abundant optical emis- set up the build-up cavity without the LBO crystal. We will sion comes from an accretion disk around a black hole. Due install the crystal-oven assembly into the cavity shortly to test to their large distances and bright centers, quasars appear as the performance of the complete SHG system for production point sources from our telescopes on Earth and in orbit. Cur- of 556nm light. We expect to produce sufficient power at rently spectroscopic observations are the best way to clas- this wavelength for laser cooling of ytterbium. This system sify quasars from stars, but for upcoming large-area imag- will form a part of the atom interferometry apparatus to mea- ing sky surveys, where spectra are not available, we want sure the fine structure constant, of fundamental importance to implement another selection technique. New techniques in condensed matter physics, atomic physics, and quantum- will use time-domain information to separate quasars from electrodynamics. stars, which show different variability characteristics. How- ever, it is not yet clear how exactly variability will be used in POSTER SESSION 1 a quantitative fashion to achieve this goal. We analyzed data from the Sloan Digital Sky Survey, which provides both spec- Commons West, Easel 52 troscopy and time-domain information for a large number of 12:00 PM to 1:00 PM objects, with the aim of quantifying the criteria for selecting Variable High Velocity Winds from Broad Absorption quasars. Using a sample of over 10,000 variable objects, in- Line Quasars cluding 1,419 spectroscopically confirmed quasars, we mod- Kenza Sigrid Arraki, Senior, Astronomy, Physics eled their light curves using quasar light curve models. By EIP Scholar comparing the quality of light curve best fits, we are able Mentor: Scott Anderson, Astronomy to distinguish quasars from stars with a less than 20% con- Mentor: Daryl Haggard, Astronomy tamination using variability information alone. Since a large fraction of the contaminants are expected to be unconfirmed Galaxies with a growing black hole are known as “active quasars, we provide a list of targets for spectroscopic follow galaxies” and, if they are extremely bright, “quasars.” Our up. research group studies broad absorption line quasars (BAL QSOs) because these objects, in particular, probe the high velocity gas very close to the central black hole. Our project POSTER SESSION 1 aims to determine the appropriate timescales for probing vari- Balcony, Easel 110 ability in BAL QSO spectra. The variability timescales can 12:00 PM to 1:00 PM constrain the size of the emitting and absorbing gas cloud near the supermassive black hole. We have observations of seventeen BAL QSOs from the Sloan Digital Sky Survey (SDSS) and the Fred Lawrence Whipple Observatory’s 1.5m telescope’s FAST Spectrograph. These objects are first iden-

3 Student Perspectives on the Undergraduate Engineering Experience POSTER SESSION 1 Matthew Allen Hicks, Junior, Informatics (Human-Computer Commons West, Easel 71 Interaction), Comparative History of Ideas 12:00 PM to 1:00 PM Tia Hsiao Lee, Sophomore, Communication Robin Alexandra Jones, Senior, Sociology Saturated Absorption Laser Spectroscopy of Ytterbium Laura Marie Julich, Junior, Chemical Engineering Jason Allen Grad, Senior, Physics Zinnia Siyun Xu, Junior, Bioengineering, Computer Mentor: Subhadeep Gupta, Physics Engineering Mentor: Anders Hansen, Physics Mary Gates Scholar Maria Katharina (Maria) Clow, Junior, Psychology Recent advancements in laser cooling techniques have helped Robert Haven (Rob) Thompson, Senior, Physics, Computer provide access to the extremely low temperatures, necessary Science to create Bose-Einstein Condensates (BEC’s). Laser cool- Mary Gates Scholar, NASA Space Grant Scholar ing relies upon the interactions of light with atoms which re- Mentor: Ken Yasuhara, Center for Engineering Learning & sults in a slowing force. For light to interact with atoms it Teaching must be controllable and near a resonance frequency of that atom. Thus cooling techniques are sensitive to fluctuations in Recognizing that there is a critical need to investigate engi- the laser’s frequency. To reduce such fluctuations, stabilizing neering education from the student’s perspective, the Center the cooling laser to a particular frequency is required. This for the Advancement of Engineering Education, funded by project involves the development of a saturated absorption the National Science Foundation, conducted the Academic laser spectroscopy (SALS) apparatus for stabilizing lasers to Pathways Study. This longitudinal study surveyed, inter- optical transitions in the ytterbium atom. A vacuum chamber viewed, and administered engineering design tasks to a to- has been constructed to house the sample and includes glass tal of 160 students from four institutions as they progressed viewports to let in the laser light for spectroscopy. To perform through four years of their undergraduate engineering edu- SALS the sample must be heated to a few hundred degrees cation. Between July 2009 and February 2010, the Cen- Celsius in order to create sufficient vapor density for a usable ter for Engineering Learning and Teaching undergraduate re- optical signal. SALS is a two beam method, which exploits searchers examined each of the interview transcripts. This the saturation of atomic transitions caused by the absorption poster presents selected themes emerging from a prelimi- of light. The beams are counter-propagating and result in a nary inductive analysis of the interviews. One of the com- Doppler free signal, which yields a stable reference source. mon themes exhibited throughout the study was the differ- Considerable attention has to be paid to the vacuum chamber ence between engineers and non-engineers. Students at all design to simultaneously achieve proper spectroscopic sig- four institutions made important distinctions between them- nals and avoid unwanted interactions of the hot vapor with the selves and students in other majors. These distinctions were glass viewports. I will report on the design and construction evident in many aspects of the students’ lives, from their of the vacuum chamber and the performance of our ytterbium academic experience to their social lives. One institution laser spectroscopy setup. even developed specific vocabulary, labeling humanities and engineering-related majors as ”fuzzies” and ”techies,” respectively. Another theme common to many of the interviews SESSION 1N was the challenges that students experienced as engineering majors. These challenges ranged from the rigid structure ENVIRONMENTAL SCIENCESAND of the undergraduate engineering curriculum to the competi- tive nature of applying to the different engineering major de- SURFACE PROCESSES:METHODS partments during the students’ sophomore year. One sopho- AND RESULTS more stated, ”I’m in to the whole very structured prerequisite schedule. You can’t miss a class... [and] most the classes Session Moderator: Joanne (Jody) Bourgeois, Earth & are only offered one semester per year. So if you can’t get Space Sciences in ’em [sic] one semester, you’re pretty much a year behind.” Mary Gates Hall Room 284 This study sheds light on the student’s perspective throughout 1:00 PM to 2:30 PM their undergraduate engineering education. With a better un- * Note: Titles in order of presentation. derstanding of the engineering undergraduate experience, we hope to help improve engineering education.

4 The Space-Time Evolution of Episodic Tremor and Slip A New Tool for Studying Climate Change: The and the Discovery of Rapid Tremor Reversal Ice-Penetrating Probe Brent Gregory (Brent) Delbridge, Senior, Applied & Elizabeth Landicho (Elizabeth) Wicks, Sophomore, Computational Mathematical Sciences (Engineering & Astronomy, Physics, Mathematics (Comprehensive) Physical), Physics, Pre Engineering Mentor: Dale Winebrenner, Earth & Space Sciences Mary Gates Scholar Mentor: W. T. Elam, Applied Physics Laboratory Mentor: Heidi Houston, Earth And Space Sciences Gathering reliable data about the rapidly shrinking sea ice Episodic Tremor and Slip is a recently discovered spatiotem- cover of the Arctic is crucial to the study of climate change. poral correlation between subtle seismic signals, and slow Expanding our knowledge of processes beneath sea ice would slip events on subduction zones. Understanding ETS could expand our knowledge of features that significantly affect the be a valuable tool as a real time indicator of stress loading in global environment, such as ice thickness, melt rate, and ice the Cascadia earthquake zone and help predict times of high and ocean temperatures. Yet we currently have no means of probabilities for large earthquakes near Seattle [Dagert and deploying instrumentation beneath sea ice short of landing on Rogers, 2003]. Further, understanding the character and loca- the ice and operating it manually, which is not practical for tions of tremor epicenters could facilitate locating the locked long-term measurements. To meet the demand for long-term segments of the Juan de Fuca plate [Wech and Creager, 2008]. data on sub-ice processes, our research team is developing We analyze data from 5 major ETS episodes since 2004 in an autonomous ice-penetrating probe. We will use the same Northern Washington on the Cascadia subduction zone. They deployment method as previous researchers, who have suc- occur every 13-16 months and persist for 15-20 days. Dur- ceeded in deploying instrumentation on the ice surface via air- ing an ETS episode, a reversal in direction of the displace- plane. Other researchers have developed electrically powered ment of the tectonic plate revealed by GPS data is accom- ice penetrating probes, which were successfully deployed in panied by weak seismic waves (tremor). Although ETS dif- glaciers on land to depths of hundreds of meters. However, fers qualitatively from regular earthquakes, the total amount these probes required manual operation and were inefficient of slip in major ETS episodes corresponds to a magnitude because of their large size, which was limited by the size of 6.6-6.7 earthquake spread out over 15-20 days. In Casca- the electronics available at the time. Advances in technol- dia this coupled process of tremor and slip migrates slowly ogy have greatly reduced the size of the electronics required along the interface between the subducting Juan de Fuca plate to make useful measurements, enabling our research team to and the overriding North American plate. Our analysis of construct an electrically powered ice-penetrating probe that is 16000 individual tremor locations reveals a new feature of smaller, more efficient, and autonomous. We are constructing ETS, termed “Rapid Tremor Reversal” (RTR). Occasionally such a probe by creating and testing a succession of design pulses of tremor reverse direction from the general migration prototypes that are providing insight into the dynamics of ice and zip backwards over already ruptured regions of the plate penetration. Our successful first test article is faster and more interface with velocities 10-20 times greater than the average efficient than previous models, penetrating through about 40 propagation speed. We suggest that fluid pressure fluctuations centimeters of saline ice at a rate of 6.6 meters per hour with can move faster through previously ruptured regions than they an average power input of 500 watts. The final probe de- can advance through a region that has not yet tremored and sign will be capable of deployment via airplane and will au- slipped. Our preliminary results appear consistent with a fluid tonomously penetrate through sea ice to reach the ocean be- mechanism of tremor generation. neath, enabling the study of sub-ice processes.

SESSION 1N SESSION 1P

ENVIRONMENTAL SCIENCESAND ASTRONOMYAND PLANETARY SURFACE PROCESSES:METHODS SCIENCE AND RESULTS Session Moderator: Eric Agol, Astronomy Mary Gates Hall Room 288 Session Moderator: Joanne (Jody) Bourgeois, Earth & 1:00 PM to 2:30 PM Space Sciences Mary Gates Hall Room 284 * Note: Titles in order of presentation. 1:00 PM to 2:30 PM * Note: Titles in order of presentation.

5 Searching for Milky Way Planetary Nebulae tions predict an isotopic ratio for sulfur-33 (33S) to sulfur- Thomas Alexander (Thomas) Gomez, Senior, Astronomy, 32 (32S) that may be up to 150 times that of the solar ratio. Physics This prediction could allow for clear identification of presolar EIP Scholar grains from novae, but is subject to uncertainty due to a lack Mentor: Bruce Balick, Astronomy of data on the main destruction mechanism for 33S in novae, In the Milky Way, there are very few planetary nebulae (PNe) the 33S(p,γ) 34Cl reaction. This is a reaction in which a pro- known to be in the halo, less than a dozen. Studies of the ton combines with 33S to form an excited state of chlorine-34 Andromeda Galaxy have shown that there are more than 700 (34Cl) that promptly decays to a lower energy state of 34Cl PNe in the thick disk alone. By analogy, we would expect to by emitting a gamma ray. We are currently using a Van de find several thousand PNe in the halo. We are using surveys Graff accelerator to accelerate protons toward a copper target such as SDSS and 2MASS to identify new planetary neb- that is implanted with 33S. The objective of this experiment is ulae candidates at high latitudes in the absence of suitable to measure the resulting gamma rays to determine the gamma emission-line imaging surveys. Our recent research shows ray branching ratios of resonances pertinent to nova reaction that it is possible to refine the search using near-infrared col- rates. When combined with data from a planned experiment ors from 2MASS. Combining 2MASS and SDSS were able to at TRIUMF in Canada this will lead to a more accurate pre- produce several viable candidates. In addition we have started diction for isotopic ratios of sulfur in presolar nova grains. a search for halo PN candidates using a narrowband [OIII] Additionally our data may contribute to predicting whether or filter and a Sloan g’ filter at the 0.5m ARCSAT telescope at not gamma rays emitted from decay of the 34Cl meta-stable APO and the 0.75-melescope at Manastash Ridge Observa- state in nova outflows may be observed by telescopes orbiting tory (MRO). Once we identify survey candidates with appro- the Earth. priate broad-band optical and IR colors and morphologies, or identified others with strong [OIII] emission, confirmation POSTER SESSION 2 spectra will be observed on the Apache Point Observatory Commons West, Easel 68 (APO) 3.5m telescope. There have been a couple of candi- 2:30 PM to 3:30 PM dates come out of the SDSS queries, those so far have turned out to be interesting objects. Climate Change in Washington: Current Thinning Rates at Blue Glacier Sean Alan Michael, Junior, Earth & Space Sciences ESSION S 1P (Physics), Physics Mentor: T.J. Fudge, Earth And Space Sciences ASTRONOMYAND PLANETARY Mentor: Edwin Waddington, Earth And Space Sciences SCIENCE Alpine glaciers are important because they contribute to sea Session Moderator: Eric Agol, Astronomy level rise and record climate change in remote areas. A Mary Gates Hall Room 288 glacier’s health can be monitored by making annual mass bal- 1:00 PM to 2:30 PM ance measurements, which is the difference between snow * Note: Titles in order of presentation. accumulation and melting. A positive mass balance indicates the glacier is growing whereas a negative mass balance in- Measurement of 33S(p,γ) 34Cl Gamma Ray Branching dicates shrinking. Blue Glacier, located on Mt Olympus, is Ratios of Resonances at Nova Temperatures of particular interest because it has one of the longest mass Blake Michael (Blake) Freeman, Senior, Mathematics balance records in the Pacific Northwest. Blue Glacier grew (Comprehensive), Physics slightly from the 1950’s until the mid-1970’s and has been Mentor: Christopher Wrede, Physics shrinking since. Measurements of the glacier’s surface were taken by walking across the lower glacier with a GPS receiver Presolar grains are small grains of material, found in mete- in September 2009. The amount of thinning can then be de- orites, with isotopic ratios differing from those in the solar termined by calculating the change in surface elevation be- system at large. They are believed to have originated from tween our measurements made in 2009 and three different distinct astrophysical events such as novae before the forma- data sets: a USGS map from 1987, laser altimetry profiles tion of our solar system. A nova is caused by the accretion of from 1996, and GPS tracks walked in 2003 and 2004. Re- hydrogen onto a white dwarf star from a larger neighboring sults are expected to show a continued decrease in surface star in a binary star system, which results in a thermonuclear elevation. runaway on the surface of the white dwarf that ejects material into space. Novae are currently being modeled on computers using existing experimental data and theory. These calcula-

6 anti-de-Sitter (AdS) space (M) crossed with an internal space POSTER SESSION 2 (N). In the simplest terms, an AdS space is a manifold with Commons West, Easel 59 constant negative curvature. The solutions to these equations 2:30 PM to 3:30 PM would describe the shape that D-branes take in such a space (M x N). We have derived the general equations and have ex- M Dwarf Flares: Exoplanet Implications panded them to first order. Others have solved special cases Benjamin Michael (Ben) Tofflemire, Junior, Physics, for M and N. Our generalized equations reduce to these spe- Astronomy cial cases. Mary Gates Scholar Mentor: John Wisniewski, Astronomy POSTER SESSION 2 Low mass stars such as M dwarfs are prime targets for ex- Commons West, Easel 60 oplanet transit searches as their low luminosities and small 2:30 PM to 3:30 PM stellar radii could enable detection of super-Earths residing in their habitable zones. While promising targets for transit Mysterious Disturbances of Stellar ”Frisbees” searches, M dwarfs are also inherently variable and can ex- Zachary Harrison (Zack) Draper, Sophomore, Astronomy, hibit up to 6.0 magnitude flux enhancements in the optical Physics U-band. This is significantly higher than the predicted tran- Undergraduate Research Conference Travel Awardee sit depths of super-Earths (0.005 magnitude flux decrease). Mentor: John Wisniewski, Astronomy The behavior of flares at infrared (IR) wavelengths, particularly those likely to be used to study and characterize M dwarf Classical ”Be” stars are massive, rapidly rotating stars hav- exoplanets using facilities such as the James Web Space Tele- ing gaseous circumstellar decretion disks which are known scope, remains largely unknown. To address these uncertain- to sometimes dissipate and regenerate. Since the mechanism ties, we have executed a coordinated, contemporaneous mon- for forming these disks is not known, observing these stars itoring program of the optical and IR flux of M dwarfs known when they transition between a ”Be” phase and a normal B to regularly flare. A suite of telescopes located at the Kitt star phase can help constrain what causes the disks to form. Peak National Observatory and the Apache Point Observatory We have analyzed 15 years of spectroscopic and spectropo- were used for the observations. We present the initial results larimetric data from the Ritter and Pine Bluff Observatories of of this program and discuss how flare events could influence two ”Be” stars, 60 Cygni (Cyg) and Pi Aquarii (Aqr), during future exoplanet detection and characterization studies in the which such a transition phase from Be to B star occurred. The IR. time-scale of 60 Cyg’s disk loss was 1000 days, during which the disk emission declined monotonically, while Pi Aqr’s disk loss episode lasted 2440 days and was interrupted by two ma- POSTER SESSION 2 jor injection events of new disk material. We used the wave- Balcony, Easel 139 length dependence of polarization during each stars disk-less 2:30 PM to 3:30 PM phase to determine the interstellar polarization. Analysis of the intrinsic polarization and H-alpha equivalent width mea- Minimal Surfaces in Asymptotically AdS Spaces Crossed surements show that both disks faded in an inside-out manner, with an Internal Space with timescales much longer than the orbital periods of their Michael Kevin (Michael) Spillane, Senior, Physics, binary companions. We also detect small deviations away Mathematics from the overall disk position angle in our polarization data; Mentor: Andreas Karch, Physics, University of Texas at we speculate that this might be indicative of either a warp in Austin the inner disk region or the injection of new disk material at Minimal surfaces (i. e., a surface with zero mean curvature) an inclined orbit to the plane of the pre-existing disk. We also have been a topic of interest in both pure and applied mathe- present our initial efforts to model time dependent behavior of matics since the 18th Century. Plateau’s problem, that a min- our spectropolarimetric data using 3D Monte Carlo Radiative imal surface can be found spanning any given boundary, is transfer codes. the most general problem and was solved for three spatial dimensions in the 1930s. Mathematicians continued working POSTER SESSION 2 on the topic in higher dimensions, while physicists lost inter- Balcony, Easel 138 est. Physicists once again became interested in the problem 2:30 PM to 3:30 PM after research began in string theory and particularly in D- branes, the surfaces where strings terminate. Our research involves finding the equations for minimal area surfaces (i. e., minimal surfaces with minimal area) in an asymptotically

7 Prototype Design of a Precision Electron Energy gle molecular layer on the outside surface of the bundles. We Measurement System for the Project 8 Neutrino Mass will compare these observations to adsorption measurements Experiment we have done on flat exfoliated graphite. Timur Rustamovich (Timur) Rikhsiev, Senior, Physics Mentor: Gray Rybka, Physics POSTER SESSION 2 Neutrinos must have mass to explain neutrino oscillations. Current neutrino mass experiments place an upper bound on Commons West, Easel 61 the neutrino mass of about 1 eV. A precise energy measure- 2:30 PM to 3:30 PM ment of the electron emitted from tritium beta decay would Exploring the Detectability of Terrestrial Exoplanet lead to a measurement of the neutrino mass. One new electron Characteristics energy measurement method under study involves the detec- Nicole Elaine Evans, Junior, Physics, Astronomy tion of the electron’s cyclotron radiation in a strong magnetic Mary Gates Scholar, NASA Space Grant Scholar field. Power emitted in cyclotron radiation is very small, so it Mentor: Victoria Meadows, Astronomy is important to maximize the gain of the receiver. We sim- Mentor: Shawn Domagal-Goldman, Astronomy ulated electromagnetic properties of several microwave receiver configurations in order to maximize the signal to noise Of the 400+ extrasolar planets that have been discovered to from a single electron. The results will be used to design pro- date, the vast majority are massive gas giants. This is largely totype electron energy measurement system at the University due to the inherent difficulty of detecting terrestrial plan- of Washington. ets, which are small and faint by comparison. Both NASA and ESA have proposed space-based observatories (Terres- trial Planet Finder [TPF] and Darwin, respectively) capable of POSTER SESSION 2 detecting these planets by suppressing the light of their host Balcony, Easel 140 stars, in order to discern the light reflected by the planetary 2:30 PM to 3:30 PM companion. Following a successful detection, TPF/Darwin will then analyze the planet’s spectrum to determine its chem- Survey of Adsorption of Gases on Carbon Nanotube ical composition, and whether it may be capable of support- Bundles ing life. Prior to the launch of such missions, we will need Evan Richard Mattson, Junior, Physics, Mathematics to understand the spectral characteristics of the planets we Mentor: Oscar Vilches, Physics may find, and how detectable these characteristics will be. We are currently studying the adsorption of various gases on The Virtual Planetary Laboratory (VPL) has generated syn- identical samples of carbon nanotube bundles at temperatures thetic spectra for a variety of possible planets, including the that range from 4K to 100K. It is known for a classical sys- early and modern-day Earth, other planets in our solar system, tem that dimensionality reduces the vapor-liquid critical point and model planets around other stars. Using these spectra to 40% and the solid-liquid-vapor triple point to 60% of the and a TPF-C simulator (provided by S. Heap and D. Lindler, 3D value. In addition, quantum mechanical effects for light GSFC), our project aims to determine the required spectral mass atoms and molecules reduce these numbers even fur- resolution and sensitivity needed to detect signs of habitabil- ther. The purpose of our research is to explore how dimen- ity and life, such as the presence of oxygen and liquid water. sionality and quantum effects affect the actual area occupied The information acquired from this analysis will be helpful by a single molecule or atom on a curved surface. We are in determining the detectability of key spectral characteristics in the process of building two apparatuses that will allow us within the limitations of the instruments involved, and thus in to do this. The first set-up is being built around a cryogenic carrying out these and future planet-characterizing missions. cooler and a vacuum system, where we are running adsorption isotherms of nitrogen, deuterium, deuterium hydride, and SESSION 2E hydrogen gases. The second system houses another vacuum system and a helium bath to measure adsorption isotherms of nitrogen, helium-3 and helium-4 at 77.4K and 4.2K on nan- IMAGINGIN BIOMEDICINE otube bundles from the same batch as those that used in the Session Moderator: Kristin Swanson, Pathology cryocooler experiments. We have measured already the ad- Mary Gates Hall Room 231 sorption of nitrogen gas on the carbon nanotube bundles at 3:30 PM to 5:00 PM 77.4K for the cryocooler setup, and we will use the data as a * Note: Titles in order of presentation. standard of measurement for all other isotherms. We have observed features corresponding to the formation of three lines of nitrogen molecules and to the completion of a sin-

8 Diffusion-Weighted MRI for Early Detection of 500K and in vacuum below 10−6 Torr. An AFM uses an Treatment Response in Breast Tumors ultra-sharp tip to image materials on the nano-scale. With the Brian E (Brian) Clarke, Senior, Physics implementation of scattering Scanning Near-field Optical Mi- NASA Space Grant Scholar croscopy (s-SNOM), we can measure the optical response of Mentor: Savannah Partridge, Radiology nano-scale materials and structures with an optical and spa- Diffusion-weighted imaging (DWI), a specialized form of tial resolution of 10nm. A pulsed infrared laser is focused magnetic resonance imaging (MRI), has shown promise for onto the tip (pulse duration ˜200 femtoseconds), and the tip- early detection of treatment response in tumors. DWI mea- scattered near-field radiation is analyzed interferometrically. sures the mobility of water molecules in vivo and is sensi- The laser pulses are generated using a mode-locked titanium- tive to tissue characteristics such as cell density, membrane sapphire laser, and converted to tunable mid-infrared light permeability, and microstructure. DWI studies of the breast using an Optical Parametric Oscillator (OPO) and Differ- have shown decreased diffusivity in malignant breast lesions, ence Frequency Generation (DFG). The instrument allows for primarily attributed to the increased cell density associated spectroscopic nanoimaging of the plasmon response of nano- with breast tumors. Previous studies have found that the DWI structures, or the different crystal phases in nano-wires. Vana- apparent diffusion coefficient (ADC) in tumors increases in dium oxides wires, for example, undergo a metal to insula- response to treatment earlier than detectable changes in tu- tor transition at specific low temperatures, switching from the mor size or vascularity found through conventional imaging monoclinic M1 phase to the metallic rutile phase. Studying techniques. This increase in ADC is thought to be due to vanadium oxides will give insight into other strongly corre- cell death and necrosis, and may be a valuable early indi- lated electron materials, an interesting and newly developing cator of treatment efficacy. In this study we used DWI to material family. In this talk, I will discuss the design, con- measure the ADC of tumors in patients undergoing preop- struction, and scientific principles of our system. I will also erative chemotherapy. Serial changes in breast tumor ADC review preliminary data and discuss upcoming experiments were measured by region-of-interest (ROI) analysis, which on the instrument. involves using a computer program to trace the border of the tumor on an MR image of the breasts and to calculate ADC for the pixels within the region. We compared the changes in tumor ADC throughout treatment with the pathological find- ings of the removed breast tissue to find the relationship between changes in ADC and the efficacy of treatment. A better understanding of the relationship between changes in ADC and treatment response will allow treatment regimens to be tailored for maximum benefit to the individual patient. This would not only allow the patients to be put on regimens that are more likely to treat the disease, it prevents them from go- ing through toxic treatments that have no survival benefit.

SESSION 2I

POWERAND ELECTRICITY Session Moderator: John Sahr, Electrical Engineering Mary Gates Hall Room 248 3:30 PM to 5:00 PM * Note: Titles in order of presentation.

Design of a Low Temperature Atomic Force Microscope (AFM) for the study of Correlated Electron Materials Erik Josberger, Senior, Electrical Engineering, Physics Mary Gates Scholar Mentor: Markus Raschke, Chemistry Mentor: Ryan Murdick, Chemistry

We have designed an Atomic Force Microscope (AFM) system capable of operating at temperatures between 20K and