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 as- sess 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 coordi- nation 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.