The following posters by CUWIP participants will be on display during the conference. A formal poster session will take place on Saturday from 3-5pm.
1. Phoretic motion of Marangoni isotropic emulsion droplets
Suzanna Ackroyd (UC Santa Barbara), Jasna Brujic, and Pepijn Moerman
Small, liquid particles suspended in fluid can self-propel by expelling their contents and interacting with the solute; a chemical gradient of oil and surfactant induced by diffusion of oil into the solution causes an unstable state whose symmetry can be broken by an initial velocity for a critical particle size (or Peclet number) and surfactant concentration, resulting in locomotion. We study a system of isotropic, spherical droplets [10 micons – 200 microns] of diethyl phthalate (DEP) suspended in a solution of sodium dodecyl sulfate (SDS) where the motion is driven by Marangoni flow. We investigate several novel aspects of the system, including the motion due to its Non-Markovian nature (caused by chemical trail memory) and seek to build a theoretical model to describe 1) the ballistic, random, and oscillatory diffusiophoretic motion through the decay of the motion’s angular correlation 2) the attractive behavior of the large particles. We will use this model to produce a pseudo-phase diagram of the motion as a function of the droplet size and surfactant concentration parameters. We also seek to functionalize the self-assembling, geometric packing of the particles to construct superstructures using specific adhesive molecules, including DNA and other proteins. After achieving the intended geometry, the DEP oil droplets can be polymerized, forming solid particles to make new materials.
2. Comparing Binary Black Hole Collisions Produced by Numerical Methods with Approximations
Nousha Afshari (CSU Fullerton) and Geoffrey Lovelace
Detecting astronomical gravitational waves will soon open a new window on the universe. The effects of gravitational waves have already been seen indirectly, but a direct observation of these waves will test Einstein’s theory of general relativity under the most extreme conditions. The Laser Interferometer Gravitational-Wave Observatory, or LIGO, will soon begin searching for gravitational waves, and the first direct detections are likely in the next few years. To help LIGO detect as many gravitational waves as possible, a major research effort is underway to accurately predict the expected waves. In this presentation, I will explore how the gravitational-wave sound produced by a long binary-black-hole inspiral is affected by how fast the larger black hole spins. I completed this simulated experiment using the Spectral Einstein Code (black-holes.org/SpEC.html). I compared the resulting gravitational waveforms, finding as expected that different spins lead to different sounds. One long resulting gravitational waveform was compared to several approximations; this waveform turns out to agree much better with some approximations than others.
3. Phenomenology of Grand Unified Theories
Nima Assad (UC San Diego) and Benjamin Grinstein
The establishment of neutrino flavor oscillations rendered the Standard Model of particle physics an effective theory of strong and electroweak interactions. Attempts at extending the Standard Model to account for these recent developments has often involved invoking new physics which cannot be probed directly at energy scales currently accessible experimentally. Beyond the Standard Model (BSM) theories, however, may have implications on the low-energy scattering cross sections of particle interactions. Grand Unified Theories (GUTs) are a class of BSM models based on the postulated convergence of the Standard Model’s three gauge couplings at energy scales on the order of 1015 GeV. By embedding the Standard Model into larger gauge groups, GUTs are able to achieve both a reduction in the number of free parameters and an increase in the predictivity of the model. Here, I will address the phenomenological implications of intermediate breaking scales in a non-minimal SU(5) model of grand unification on low-energy scattering cross sections. These results may be used to guide experiments like the LHC in identifying events of interest for use in testing the viability of such candidate theories.
4. Witnessing Entanglement
Marisol Beck (Harvey Mudd College) and Mark Beck
An entangled state of a two-particle system is a quantum state that cannot be separated?it cannot be written as the product of states of the individual particles. One way to tell if a system is entangled is to use it to violate a Bell inequality (such as the Clauser-Horne-Shimony-Holt, CHSH, inequality), because entanglement is necessary to violate these inequalities. However, there are other, more efficient measurements that determine whether or not a system is entangled; an operator that corresponds to such a measurement is referred to as an entanglement witness. We present the theory of witness operators, and an undergraduate experiment that measures an entanglement witness for the joint polarization state of two photons. We are able to produce states for which the expectation value of the witness operator is entangled by more than 380 standard deviations.
5. Breaking Friedel’s Law in 2D Materials
Pratiti Deb (Cornell University), Megan E. Holtz, Robert M. Hovden, Celesta S. Chang, and David A. Muller
Recent developments in high dynamic range detectors for electron microscopy have provided new opportunities for studying localized phenomena in crystal structures. To better understand the physics behind electron diffraction patterns observed, we simulate diffraction patterns for 2D materials and find that they violate Friedel’s Law. Friedel’s Law, which is commonly used in crystallography, states that the diffraction pattern that results from waves interacting with a crystal will have equal intensities for both the positive and negative hkl points. In the diffraction pattern, the squared amplitudes of the wave will be centrosymmetryic, with antisymmetric phase. Here, we find that Friedel’s law is violated for electron scattering in 2D materials and explore this effect as a function of incident beam energies and of atomic numbers of the material. By simulating the electron beam as it propagates through a monolayer of MoS2, we find that the diffraction pattern is non-symmetric, while for a monolayer of graphene, it is centrosymmetric. The breaking of symmetry in the diffraction pattern for MoS2 suggests that this effect can be used to measure the polarity of the material.
6. A New Apparatus for Studies of Low Energy Electron Collisions with Nucleotide Molecules
Jessica Duron (CSU Fullerton) and Leigh Hargreaves
Low-energy electrons, the most copiously produced by-product of radiation cancer therapy, have been shown to be a strong driver of DNA damage in living cells [1]. Quantitative data describing these collisions are presently rare due to technological challenges in performing electron scattering measurements from the nucleobases, e.g. uracil, thymine, guanine, etc. These challenges include the low-vapor pressure of commercial samples (which are powders at room temperature), and the difficulty in making accurate flow measurements from heated gas sources, required to establish the absolute scale of the measured data. Based on techniques pioneered in positron collision physics [2], a new apparatus is presently undergoing commissioning at the California State University Fullerton, which aims to address these issues. We will make the first cross-section measurements for slow (E0 < 30eV) electron collisions with nucleotides. We will report design parameters and ongoing progress in the commissioning of this new experiment. [1] Boudiffa et al., Science, 87, 3 (2000) [2] Sullivan et al., Phys Rev A, 68, 042708 (2002)
7. A Survey of Cryovolcanic Domes on Jupiter’s Moon Europa
Sierra Ferguson (Northern Arizona University), Lynnae Quick and Lori Glaze
Domical features have previously been seen on the surface of Europa and have been classified as having formed by methods of diapirism. Our study surveys the E15 and E17 orbits form the Galileo spacecraft in order to investigate the possibility of some of these domes being formed by extrusive cryovolcanism. We surveyed the surface for domes that met our defined characteristics that would indicate formation by extrusive cryovolcanism instead of dipirism, such as the relative albedo of the dome in question being lower than the surrounding terrain. We mapped these features using ArcGis and found that the domes which were classified as extrusive in origin tended to form closer to the equator than the domes formed by diapirism. This could indicate that tidal heating from Jupiter plays a larger role in the formation of these domes. In total, we found 33 domes which were consistent with characteristics which would suggest formation from extrusive cryovolcanism. The results of this study can be further used to obtain physical parameters to be used in formation models of these domes.
8. Making and testing models of gravitational waves from colliding black holes
Alyssa Garcia (CSU Fullerton) and Geoffrey Lovelace
Gravitational waves are ripples in space and time and were predicted by Albert Einstein, but they have not yet been directly measured. The Laser Interferometer Gravitational-wave Observatory (LIGO) is a detector that is currently working to observe gravitational waves from astronomical sources, such as colliding black holes, which are among LIGO’s most promising sources. Observing as many waves as possible requires accurate predictions of what the waves look like, which are only possible with numerical simulations. I am running simulations of binary black holes using the Spectral Einstein Code (SpEC). I am also taking complete waveforms (my own and others’) and using an open-source library to extend the waves. Inexpensive, approximate, Post-Newtonian calculations are used to model the gravitational waveforms from binary black holes that are still far away from each other, while expensive, numerical relativity simulations are used to calculate the waveforms of black holes near merger, since there the post-Newtonian approximation breaks down. To construct a waveform that spans the frequency range where LIGO is most sensitive, we combine the post-Newtonian and numerical relativity method, making a hybrid gravitational waveform. I am also checking the accuracy of the numerical waveforms (original and hybridized) with the analytical approximations using match filtering, a noise-weighted inner product that measures how alike two waveforms are. I found that our numerical simulations have at least a 90% match with several approximations, such as TaylorT4 and SEOBNR (Spinning Effective One Body Numerical Relativity). I also found that the spin direction and alignment can affect the match between waveforms much more than the magnitude of the spin.
9. The Core-Collapse Supernovae Rate within the Local Universe
Jasmine Gill (Embry-Riddle Aeronaut Univ) and Michele Zanolin
Core-Collapse supernovas (CCSNe) mark the dynamic and explosive end of the lives of massive stars by emitting the gravitational wave that is detectable by detectors such as the Laser Interferometer Gravitational-Wave Observatory (LIGO). LIGO has been one of the first collaborations to create ways to collect and analyze data that would distinguish the gravitational waves from background noise produced on Earth. Optical observations of supernovas in the Local Universe provide trigger times (with a typical uncertainty of a few days) and precise sky locations, while an electromagnetic observation would provide a core-collapse trigger time (with an uncertainty of a few seconds) and a sky location. We describe a method that takes into account optical and electromagnetic observational techniques for detection of CCSNe within the Local Universe, which encompasses a volume of 20 Mpc. Providing distance sensitivity estimates for the rate of CCSNe within the Local Field and the Virgo Cluster specializes the implementation of the CCSNe rate toward specifically gravitational wave detection.
10. Energetic Particles in Star Forming Galaxies
Cee Gould (UC Berkeley) and Tonia Venters
An exciting result from the Fermi Gamma-ray Space Telescope is the detection of star-forming galaxies at gamma-ray energies. In star-forming galaxies, gamma rays are produced through the interactions of highly energetic cosmic rays with interstellar gas and radiation. Nearby star-forming galaxies, such as NGC 253, have been the subject of multi-wavelength observations by telescopes such as Fermi (at GeV energies), NuSTAR (in X-rays), VLBA (radio), and HESS and VERITAS (at TeV energies). Even so, the details surrounding the mechanism for producing the gamma rays remain elusive. Do the gamma rays originate from interactions from interstellar gas and radiation and cosmic ray electrons, or cosmic ray protons?
11. Type IIP Supernovae and their Progenitors
Goni Halevi (UC Berkeley) and Dovi Poznanski
A set of approximately 15 well-studied IIP supernovae are examined in relation to the mass constraints placed on their progenitors. Light curves and spectra are obtained from a variety of sources and the shape and rate of the post-plateau light curve decline was cross-examined with the mass of the progenitor. Though the uncertainties are too large for a definitive conclusion, there appears to be some correlation between the Ni56 mass and the progenitor mass.

12. The Arecibo Galaxy Environment Survey: Observations towards the NGC 7817/7798 Galaxy Pair
Amanda Harrison () and Robert Minchin
The Arecibo Galaxy Environment Survey (AGES) examines the environment of neutral hydrogen gas in the interstellar medium. AGES uses the 305m Arecibo Radio Telescope and the Arecibo L-Band Feed Array to create a deep field neutral hydrogen survey which we used to detect galaxies in an area five square degrees around the galaxy pair NGC 7817/7798. By finding and investigating hydrogen rich galaxies we hope to gain a better understanding of how the environment affects galaxy evolution. H1 line profiles were made for the detected H1 emission and ten galaxies which had the characteristic double-horned feature were found. NGC 7798 was not detected, but NGC 7817 and the other galaxies were cross-identified in NASA/IPAC Extragalactic Database as well as in Sloan Digital Sky Survey to obtain optical data. Out of the ten, two of the sources were uncatalogued. We analyzed the hydrogen spectra and aperture photometry to learn about the characteristics of these galaxies such as their heliocentric velocity, flux, and mass of the neutral hydrogen. Furthermore, we graphed the Tully-Fisher and the Baryonic Tully-Fisher of the ten sources and found that most followed the relation. One that is the biggest outlier is suspected be a galaxy cluster while other outliers may be caused by ram pressure stripping deforming the galaxy.
13. The Effect of Substrate Choice on Graphene and Oxygen Plasma Interactions
Charlotte Johnson (Arizona State University) and Anna Zaniewski
Graphene is a two dimensional, single atomic layer of carbon atoms bonded hexagonally. This material has many potential applications in industry due to its strength and thermal and electrical conductivity. Graphene is also uniquely sensitive to its environment. Nearby materials will shift the electron energy levels in graphene, also impacting the electron availability. This project explores this characteristic, determining how substrate choice affects graphene plasma interaction, specifically oxygen plasma etching of graphene. To do this, graphene is first transferred from its original copper substrate to various other substrates such as silicon, quartz, and periodically polarized lithium niobate (PPLN). These samples are then exposed to oxygen plasma. To determine the effects of exposure to the oxygen plasma, each sample is analyzed using X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM), and Raman spectroscopy. These analytical methods characterize graphene quality to determine how substrate choice influences oxygen plasma etching of graphene.
14. Barnacle thermodynamics: modeling the body temperature of balanus glandula
Rachel Kahn (Scripps College) and Sarah Gilman
One of the most pressing questions that ecologists face today is how organisms will respond to global climate change. A first step to predicting how animals will respond to the changing climate is understanding the influences of environmental factors on their body temperature. Ectotherms are organisms whose body temperature is determined by the immediate environment. Heat exchange between an organism and its surroundings is governed by the principles of thermodynamics. By mathematically modeling the temperature of intertidal ectotherms, the most significant biophysical influences may be determined. The ultimate goal is to be able to predict the temperature of organisms using commonplace measurements of weather conditions. This study presents a steady state heat budget model for Balanus glandula, a barnacle commonly found along the West Coast of North America. The model includes several mechanisms for heat exchange between the barnacle and its surroundings. These include heat received from short-wave solar radiation, heat exchanged via long-wave radiation, heat conducted between the barnacle and the ground, heat convected between the barnacle and the air, and heat lost through the evaporation of water from the barnacle. Heat exchange via most of these mechanisms was approximated, however heat loss via convection (wind) was determined empirically. The heat loss was measured in barnacle shells of varying sizes filled with silicone at a range of wind speeds. A relationship was determined between the size and shape of the barnacle and how it losses heat convectively. Consequently, the convective heat loss could be calculated given easily obtained measurements of barnacle size and surrounding wind speed. The steady state model was found to closely match measured body temperatures for silicone-filled barnacle shells. Future work will involve fine-tuning of the model and testing on live barnacles in the field.
15. Prototyping a Tilt-Free Seismometer
Megan Kelley (UC Santa Barbara), Kate Dooley, and Rana Adhikari
The Laser Interferometer Gravitational-wave Observatory (LIGO) aims to be the first experiment to directly detect gravitational waves. It consists of a Michelson interferometer constructed to measure the changing distance between two test masses on the order of 10−21 meters. This level of precision requires excellent noise reduction, including passive and active isolation from seismic events. LIGO’s current seismometers function well at high (>100Hz) frequencies, but become less effective at low (<10Hz) frequencies. At these lower frequencies, tilt of the ground begins to contaminate measurements of the translation of the ground. This summer’s project consists of prototyping a seismometer that is mechanically insensitive to tilt in the frequency ranges in which LIGO is sensitive. The first component of the project is the construction of a Michelson interferometer to measure the motion of the seismometer when subjected to ground motion, and the second component is the construction of a thermal enclosure and associated temperature control system in order to isolate the system from large temperature fluctuations.
16. Developing High-Contrast Gratings for Spectrum-Splitting Multijunction Photovoltaics
Stephanie Kwan (California Institute of Technology), Harry A. Atwater, and Sunita Darbe
High refractive index contrast gratings (HCG) are two dimensional arrays of high refractive index dielectric subwavelength scale structures on the surface of a low refractive index substrate. HCG have been shown to display near perfect reflection over 200-nm wide tunable bands in the near IR range under idealized condition (e.g. for normal incidence light of a given polarization). This remarkable phenomenon is attributed to Mie electromagnetic resonances and has inspired research on applications of HCG in solar energy conversion. In spectrum splitting photovoltaics, optical elements divide white sunlight into multiple frequency bands, which are coupled into laterally separated solar cells with bandgaps tuned to best convert the target band of light. In this project, HCG are explored as long pass filters for the Atwater Full Spectrum team?s ultra high efficiency spectrum splitting photovoltaic module. Rigorous Coupled Wave Analysis simulations are used to identify geometric parameters for TiO2, GaP, and a-Si HCG. In parallel, we experimentally measure the angle dependent reflectance properties of the gratings over the visible and near IR spectrum. The long term goal is to identify and fabricate seven high efficiency HCG that can replace the costly and angle sensitive Bragg reflectors currently implemented in the submodule prototype.
17. Inverted P3HT:PCBM Organic Photovoltaic Cells: Fabrication and Stability
Sabrina Li (Pomona College) and David Tanenbaum
Organic solar cells provide a potential solution to growing energy demands. Organic photovoltaics (OPV) is based on an organic semiconductor, in this case a mixture of two organic chemicals P3HT, a polymer, and PCBM, a fullerene derivative. While organic semiconductors will theoretically be more cost effective in the long run compared to inorganic semiconductors (e.g. silicon, and GaAs), they are also more chemically reactive and therefore less stable when exposed to open air. Thus, stability is an important aspect of OPV research. Inverted P3HT:PCBM devices were fabricated with six solar cells each. The structure of glass/ITO/ZnO/P3HT:PCBM/HTL/Ag was created using a spin coater and thin-film thermal evaporator. The HTL (hole transport layer) was either nothing, evaporated MoO3 (eMoO3), or solution processed MoO3 (sMoO3). The sMoO3 process still requires refinement as it has not been applied on inverted cells prior to this project. The solar cells fabricated between Dec. 2013 and this summer were studied over time. Some devices improved while others degraded. Cells that improved drastically compared to their initial power conversion efficiency (PCE) maintained their higher PCE, but degraded over time similarly to those cells that did not see a jump in PCE. A cell fabricated in summer of 2014 showed PCE improvement from 1.641% to 3.554%, over twice the original PCE. The cause of improvement is not yet understood and warrants further study.
18. Strongly Interacting C60/Ir(111) Interface: Transformation of C60 into Graphene and Influence of Graphene Interlayer
Vanessa Lopez (CSU Northridge), Xiangmin Fei, Xu Zhang, Vanessa Lopez, Gang Lu, Hong-Jun Gao, and Li Gao
The adsorption, electronic structure, and thermodynamics of C60 molecules on Ir(111) and graphene/Ir(111) surfaces have been investigated by combining scanning tunneling microscopy and spectroscopy as well as density functional theory calculations. C60 is found to interact strongly with the Ir surface, leading to a spontaneous formation of graphene on the Ir surface at elevated temperatures. The introduction of a graphene interlayer at the C60/Ir(111) interface dramatically affects the interface properties, including the formation of larger molecular islands, improvement in ordering of molecular arrangements, suppression of charge transfer between C60 and Ir, and thermal desorption of C60 from the surface without decomposition or polymerization. We also find that C60 is an effective solid precursor for preparing small-sized graphene quantum dots as well as graphene layers on the Ir surface.
19. The End State of Stellar Evolution in Triple Systems
Xinyu Lu (UC Los Angeles) and Smadar Naoz
This research aims to establish a model for triple system, more specifically, binary star orbital behavior under the influence of small third body perturbations. Many short-period compact binaries (such as black holes, neutron stars, and white dwarfs; Thompson 2011) are likely produced through triple evolution. Secular effects (i.e., coherent interactions on timescales long compared to the orbital period), and specifically Kozai-Lidov cycling (Kozai 1962; Lidov 1962), have been proposed as a dynamical driver in the evolution of triple stars, especially hierarchical triples, in which the (inner) binary is orbited by a third body on a much wider orbit.The stars with masses larger than one solar mass undergo supernovae when massive stars collapse under their self-gravitation after depleting their nuclear fuels. The end states, such as neutron stars and black holes, are reached after supernova. Such hypotheses matches up with the observational evidences from x-ray binaries: supernova changes the eccentricity and inclinations of binaries’ orbits, and thus retrigger Kozai-Lidov Mechanism in the formations of x-ray binaries.This research anticipates generalized mathematical descriptions of the relationships between pre-supernova and post-supernova orbital parameters, which include orbital eccentricity, semi-major axis, periapse and inclination. With generalized equations of motions, several cases of hypothetical supernova kicks initial conditions will be applied to the model. The results are further expected to demonstrate retriggered Kozai-Lidov Mechanism during end-state revolutions.
21. Does TMAO Promote Microtubule Stability over DMSO?
Tegan Marianchuk Marianchuk (Arizona State University), Adrienne Hester, Dan Sackett, and Taviare Hawkins
Trimethylamine N-oxide (TMAO) is a natural osmolyte that stimulates the polymerization of tubulin dimers and counters destabilizing stresses. In this study we investigated the mechanics – specifically the persistence length – of Taxolstabilized microtubules in varying concentrations of TMAO. We employed thin chamber (¡3 micrometer) in vitro assays to restrict microtubule movement within two dimensions and used fluorescence microscopy to acquire footage. Each frame underwent image analysis using Fourier decomposition written in Matlab. A commonly used alternative to TMAO is Dimethyl Sulfoxide (DMSO). In conjunction with Taxol it promotes the stability of microtubules. In vivo, DMSO is used as a vehicle to transport Taxol through the cell membrane, and in vitro it is used as a cosolvent due to the poor water-solubility of taxanes. While studies show that the use of Taxol diluted in DMSO decreases the persistence length to stabilize microtubules, our study using TMAO investigates further into the relationship between persistence length and stability.
22. Investigating Dislocation Impurity interactions Using Colloidal Crystals
Maya Martirossyan (Harvey Mudd College), Jeremy Wang, Sharon Gerbode
Crystal structures often contain many defects, such as impurities and dislocations, and these defects play a large part in determining the properties of the crystal. Dislocation and impurity motion are well studied in large crystals, but are not as well understood in smaller crystals. Our research investigates the relationship between impurities and dislocations in order to better understand how they interact. Studying defects directly can be difficult in atomic crystals, as atoms are too small and move too fast to collect reliable data. To do this, we model these atomic crystals using colloidal crystals, which we can observe using a standard light microscope. Crystals are assembled from colloidal suspensions that contain silica beads of two different sizes, 1 micron and 1.2 microns, the larger size representing impurities in a crystal. Our experimental method consisted of disrupting our crystal with an IR laser, and collecting images after the laser is turned off. In looking at high impurity and no impurity regions, we found that the number of defects over time for the two regions differed. The crystal grain without impurities gained about twice as many dislocations while being blasted by our laser, suggesting that the presence of impurities may limit dislocation production.
23. Refining a Polarization- and Entanglement-Based Quantum Eraser for Undergraduate Lab Courses
Morgan Mastrovich (Harvey Mudd College), Siddarth Srinivasan, and Theresa W. Lynn
The quantum eraser is a powerful tool for conveying the essentials of quantum physics. In an apparatus in our upper-level teaching labs, a polarization-based quantum eraser experiment is performed with single photons produced as members of entangled pairs, via spontaneous parametric down conversion. Furthermore, the which-way information is obtained not from the signal photons that traverse the interferometer, but from the idler photons that are polarization entangled with the signal photons. This experiment has made many fundamentals of quantum mechanics and quantum information directly accessible to undergraduate students in their coursework. However, this style of polarization-based quantum eraser experiment, both at our campus and elsewhere, has exhibited unexpected partial persistence of interference fringes in the presence of which-way information. We report on recent investigations of this phenomenon and progress in eliminating the persistent fringes, thus increasing the experiment?s value as a pedagogical tool.
24. A Preliminary DPIV Based Investigation of Ruellia ciliatiflora Seeds
Molly Mosher (Pomona College), David Vejar, Sophie Zagerman, and Dwight Whitaker
The small disk-like seeds of Ruellia ciliatiflora pose an interesting fluid dynamics puzzle. High-speed video analyses show that the flower ejects the little DNA packets at speeds upwards of 10 m/s and with significant backspin while generating high lift and low drag. The rotation and irregular shape of the seed make it a poor candidate for mathematical modeling, so this project uses data collected using a technique called DPIV (Digital Particle Image Velocimetry) to analyze the flow of fluid around a 3D printed model, along with an exploration of literature concerning flow around objects of similar shapes, in order to better understand the seeds? efficient flight. Preliminary data collected from wake profile integrations on the PIV vector fields suggests that the seeds may fly in the range just before the transition from skin friction to pressure dominant drag. That said, the calculations proved difficult due to deficits in the previously collected data sets, which led the team to agree that more data, especially at lower speeds, is necessary. The literature survey was challenging, as studies concerning similarly shaped objects proved sparse. Future work includes construction of a small towing tank to acquire more data, possible 3D flow surveys, and work with other species of exploding plants to explore the role of seed morphology in efficient flight.
25. Spin Dependent Thermoelectric Transport in T-shaped Double-quantum-dot Systems
Kristen Rigsby (CSU Fullerton), Alexander Gauf, Kristen Rigsby, Mircea Crisan, and Ionel Tifrea
We investigate the thermoelectric properties of a T-shaped double-quantumdot system connected to two ferromagnetic electrodes whose magnetic moments are oriented at an angle Θ with respect to each other. The system is modeled using a generalized Anderson Hamiltonian that accounts for finite on-site Coulomb interaction in each of the system?s component quantum dots. The system‘s electrical conduction, G, and the fundamental thermoelectric parameters such as the Seebeck coefficient, S, and the thermal conductivity, κ, along with the system‘s thermoelectric figure of merit, ZT, are numerically estimated based on a Green‘s function formalism that includes contributions up to the Hartree-Fock level. Our results account for finite onsite Coulomb interaction terms in both component quantum dots and discuss various ways leading to an enhanced thermoelectric figure of merit for the system. We demonstrate that the presence of Fano resonances in the Coulomb blockade regime is responsible for a strong violation of the Wiedemann-Franz law and a considerable enhancement of the system’s figure of merit ZT.
27. Evolution of Strong CIV and MgII-Selected Absorption Systems at 1.48 < z < 2.28
Jasmin Silva (University of Hawaii at Hilo) and Kathy Cooksey
28. Testing and Optimization of a Wireless Handheld Gamma Camera
Brianna Thorpe (Arizona State University) and John McKisson
One of the ways to image an object such as a tumor is to inject a radiopharmaceutical tracer into a patient and map the distribution of the radioactive isotope in the body. Gamma cameras, devices that detect the gamma rays emitted by the tracer, can help in mapping this distribution. Many gamma cameras use a photomultiplier detector array. Photons entering the photomultiplier detector cause a signal event in the form of an electron cascade. In imaging detectors the arriving events are reconstructed into an image which is ultimately displayed using a monitor. Due to the material of the photomultiplier, these devices have been historically large and not easily portable, but recently one handheld gamma camera has been constructed which is attached to a monitor by a cable. In this project, the data processing module and radio module of a wireless handheld gamma camera containing a new photomultiplier material have been tested to determine the most efficient rate of receiving data for these components. In this particular device, the data processing module sends streams of information into the Radio Frequency (RF) Module, which is a microprocessing board radio compatible with conventional WiFi protocols. For testing purposes, the data processing module is replaced by a microprocessing board which sends simulated data to the RF Module board via a Serial Peripheral Interface (SPI). The most efficient rate of receiving data is determined by measuring the desktop Central Processing Unit (CPU) event rate, the Field-Programmable Gate Array (FPGA) event rate, the packet loss rate, and the data channel availability. With this information, we have determined and optimized the performance of the data channel. These results show the most efficient rate of receiving data. This information will be used to enhance the design and establish limitations on the current performance of the device.
29. Properties of Maser Generated Alfven Wave in a Large Laboratory Device
Ziyan Zhu (UC Los Angeles), Seth Dorfman, Troy Carter, George Morales, Mary Clark, and Giovanni Rossi
This research is motivated by the investigations of the natural Alfven wave maser, which refers to the resonant amplification of Alfven wave in the Earth-surrounding plasmas. A resonant cavity that results from applying a locally non-uniform magnetic field to a plasma source region between the anode and cathode of the Large Plasma Device creates the maser. In this research, a lanthanum hexaboride (LaB6) cathode is used as the plasma source. Above an excitation threshold, selective amplification produces a highly coherent, large amplitude Alfven wave that propagates out of the resonator through a semitransparent mesh anode into the plasma column where the magnetic field is uniform [1]. The excitation threshold is dependent on the discharge voltage, and it increases as background magnetic field strength B0 increases; this threshold influences the maser behaviors, including amplitude modulations. The LaB6 maser wavenumber decreases as B0 increases, suggesting a change in boundary condition as B0 varies. The maser with LaB6 source has only m = 1 mode, while the maser with BaO source has a mode transition from m = 0 to m = 1 mode. The mode exhibits a right-handed rotation, which is consistent with the electron diamagnetic drift rotation, supporting the possibility of a drift Alfven wave maser. The experimental results will motivate future Alfven wave study in laboratory device and thus help better understand space plasma physics such as testing the theory of Alfven-wave-induced heating of stellar atmosphere. [1] J. E. Maggs and G. J. Morales and T.A. Carter, Phys. Plasmas. 12, 013103 (2005)
30. Using Swift’s X-ray Observations to Explore the Circumstellar Medium of the Progenitor Systems of Various Types of Core-Collapse Supernovae
Destiny Murillo (Whittier College) and Brock Russell
We have analyzed 26 various types of core-collapse supernovae observed by the Swift X-Ray Telescope (XRT). With Swift’s observations starting, on average, within just a few days after the event of the supernova, we obtain information about the star’s life just prior to the explosion. After detecting an X-Ray source at the specified location of a certain supernova and further analyzing its observed x-ray data using the ximage software package (version 4.5.1), we obtain the luminosity of the material surrounding the star, the density of the material surrounding the star, and the mass-loss rate of the progenitor of the supernova. We have determined that the CSM density scales with the distance of the CSM by a factor of -1.557, for the 26 core-collapse supernovae observed for our analysis. The overall results we present allow us to further understand the circumstellar medium (CSM) and possible progenitor system of each of the supernovae that have been observed by Swift, from 2005 to present.
31. Thermodynamic Calculation of Ferroelectric Thin Film
Hongling Lu (UC Berkeley) and Lane W. Martin
Ferroelectric thin films grown epitaxially with respect to a crystalline substrate layer can demonstrate properties that are not present in bulk materials. Past decades have seen rapid progress in algorithms and calculations for analyzing thin-film ferroelectrics. In this study, the use of phenomenological models based on Landau-Ginzburg-Devonshire(LGD) theory to study such systems is described and demonstrated. Because of the presence of mechanical interactions between the ferroic oxide and substrate, modifications to the regular LGD theory are required. With appropriate transformation and minimization of such a thermodynamic potential, the equilibrium state of a film can be found and phase diagrams can be plotted. We observe shifts in the transition temperatures which imply that the strain in the film may change the properties considerably. We investigate the application of such thermodynamic calculations to compositionally-graded films and the limitations of calculations using primitive thermodynamic theories.
