Student Presentations

Poster Session

The poster session is a forum for student participants to present their research. All conference participants are invited to view the posters and interact with the presenters to learn about the research of their peers.  The authors, titles, and abstracts of accepted posters are below.  

Poster set up will be from 4:15-4:45 PM on Saturday Jan 13 at the second floor of the Old Main building, and the presentations will be from 5:00-6:30 PM. 

We will supply easels, foam poster boards (30"x40"), and binder clips for displaying posters. The poster presentations will be judged, and the top five posters will be recognized with Outstanding Poster Awards.  There will also be one Grand Prize of $50.  We hope that all presenters benefit from the experience of presenting  and the feedback from the judges.

Computational Physics

Computational Physics

#1.
DNA Copy-Number Alterations in GBM Survival Times
Kaitlin McLean, University of Utah

By using spectral decomposition techniques in genomic data, my lab uses tensor GSVD to compare tumor and normal genomic signals to a find a characteristic cancer signal for high grade brain cancer, or glioblastoma (GBM). Then this signal can be compared to new signals from new patients to predict, more accurately than existing standards, the survival time for a patient. 

 

#2
Foraging in Herds: The Effects of Noise and Hierarchies
Taryn Kay, University of St. Thomas

The role of Noise and Random Motion in animal behavior is beginning to grow and become an instrumental tool in accurately portraying animal movements.  To further this expanding idea of randomness of movement within animals, we created a simulation of a foraging herd in order to evaluate what effects incorporating noise has on numerous variables within the herd. These variables included: number of time steps needed to reach a specific target, the mean median distance to the center of the herd (MMDC), and consumption trends. It was determined that by incorporating noise into the system: the herd moved more cohesively and had increased consumption. After determining that noise was an essential factor in simulating the movements and foraging patterns of a herd, we set out to determine what the optimal range of noise would be. When the weighting of noise levels exceeded both the weightings for the influence herd members had on each other and the herd’s overall movement, the herd’s speed and food intake both increased significantly, regardless of whether or not the animals followed a hierarchy.

 

Biophysics

Biophysics

#3
Survey of Ion Coordination Geometries of Structures in the Protein Data Bank
Kathleen Clark, Arizona State University

According to some estimates, between 30% and 40% of all proteins depend on interactions with ions to perform their function. Ions can be a part of an active site in an enzyme, part of a substrate, or play a structural role. In order to understand the molecular mechanisms in all of these cases, it is important to have an accurate description of the interactions of these ions with amino acid sidechains, the protein backbone, water molecules, and cofactors. An automated analysis method was developed to analyze cations contained in crystal structures in the RCSB Protein Data Bank (PDB). The ion coordination geometries of the most prevalent  monovalent cations in the PDB (sodium, potassium, lithium, and thallium) were analyzed from the radial distribution functions of oxygen atoms around ions. Monovalent cations coordinate oxygen atoms within about a 6 Å radius, with a clear first “hydration shell,” similar to the first hydration shell in bulk water, and a secondary shell also typically visible. However, oxygen atoms are not the only atoms that can be coordinated by cations, and coordinating atoms for anions are much less well characterized than those for cations. We therefore analyzed all atoms within 6 Å of the cations as well as chloride anions using distance and force-field derived partial charges as criteria to identify atoms that are likely a part of the coordination shells. The code is written in Python and is freely available under the GNU Public License v3 at https://github.com/Becksteinlab/PDB_Ion_Survey.

 

#4
Photophysics of New Fluorescent Proteins and Applications for Super-Resolution Imaging
Emma Simmerman, University of Colorado, Boulder

Near-infrared fluorescent proteins (RFPs) are ideal candidates for sensitive in-vivo super-resolution imaging techniques. They require relatively low-energy excitation wavelengths and emit in the "optical window" where auto-fluorescence is low. The "blinking" phenomena resulting from the transition of the excited chromophore to a non-fluorescent "dark" electronic state can be used to improve the spatial resolution of conventional microscopy by orders of magnitude. In this project, the photophysical properties of a new RFP developed from bacterial phytochrome photoreceptors are characterized using time-domain excitation techniques. A kinetic model is being developed of the transitions between the various electronic states.

 

#5
Emergence of Complexity in an Ensemble of Cellular Automata
Angelica Berner, Arizona State University

In biological systems, emergence is the collective behavior of the combined interactions of different, lower-level parts of a system. The mechanisms that drive emergence are currently unknown and describing these mechanisms proves to be one of the largest problems in modern biology. This project attempts to use cellular automata, a classic abstract biological model, to examine emergence in a simple, dynamical system at a fundamental level. In this project, we use a modified version of an ensemble of cellular automata that interact by sharing their boundaries. By having mutual boundaries, cellular automata interact directly thereby eliminating the need for arbitrary interaction function. This ensemble is composed of cellular automata that exploit state-dependent rules, which allow the system to evolve over time by updating the individual cellular automata’s update rule as a function of its previous state. We will measure the collective behavior of the system by means of it’s complexity as it evolves over time.

Materials/Nanoscience

Materials/Nanoscience

#6
Surface Plasmon Polariton Beams with Uniform Profiles
Lauren Zundel, University of New Mexico

Characterized by their uniform intensity and square profile shape, flat top beams are well known in the context of paraxial optical beams, but have remained unexplored with regard to surface plasmon polaritons (SPPs). SPPs, which have emerged as exceptional tools for manipulating light below the diffraction limit, are collective oscillations of the conduction electrons in a metallic material, coupled to electromagnetic waves. These excitations can propagate for hundreds of wavelengths while remaining confined to a small volume around the interface between the metal and its surrounding dielectric environment. Here, we introduce and characterize SPP beams with flat top profiles for the first time.  We accomplish this by using a set of SPP Hermite Gauss modes that form, in the paraxial approximation, a complete basis for the solutions of Maxwell’s equations for a metal-dielectric interface.  We also comprehensively analyze the evolution of the intensity and shape of the described flat top beams over hundreds of wavelengths of propagation. This introduction of flat top beams to SPPs provides a new path toward advancements of applications of SPPs by enabling uniform coupling and excitation scenarios that are not possible using conventional SPP profiles.

 

#7
Following the Nucleation Pathway of Gyroid
Maile Burnett, University of Utah

Nanostructures and the manufacturing of them are being researched for applications in areas such as controlled drug release, bio-sensors, solar cells, and data storage. The nanostructure known as the gyroid is particularly promising for application in these areas because of the continuous, fully connected channels that spiral through it periodically and uniformly. The gyroid can be manufactured through self-assembling block-copolymers or surfactants, but the mechanism for the assembly is not well understood. A better understanding of the parameters that control the formation of this structure will tell us how we can better control the formation of the gyroid structure. <br>Our goal is to use molecular dynamics simulations to find the mechanism behind the formation of the gyroid in a model system. We were able to simulate its spontaneous formation and tested the efficiency of a number of order parameters, something that can distinguish between the gyroid and the surrounding mixture. As the gyroid forms, it passes through a transition state: the point where it has a 50% probability of forming or melting. The complexity of the gyroid structure makes it difficult to find an order parameter that can capture the structure at the transition state. However, by using committor analysis methods we were able to identify the transition state. We developed several order parameters that can distinguish gyroid from the isotropic mixture and, using Aimless Shooting and Maximum Likelihood Optimization, we ranked these parameters according to their effectiveness.

 

#8
Diamond Detectors for uses in a Proton Therapy Beam
Holly Johnson

Proton beam therapy is a form of cancer treatment that allows us to target and treat cancerous cells. High-energy protons deposit most of their energy immediately before they come to rest, forming a peak of energy deposition called a “Bragg Peak”. Thus, beams of protons can be tuned to pass through skin and healthy tissue to release their energy inside the tumor, leaving the healthier cells around it unaffected. However, precise knowledge of the beam’s position and energy is required for this targeting. Yet, current detectors, based on silicon, wear down and need to be replaced often, need frequent calibration and are susceptible to noise, having a band gap of 1.14 eV. A diamond’s band gap of 5.45 eV means that it is not susceptible to thermal noise, and its structure is more robust to radiation damage than silicon. In this project we present a diamond-based proton detector. This detector is made with an optical-grade diamond sample cleaned thoroughly with Piranha (70% sulfuric acid and 30% hydrogen peroxide), ozone, and plasma before having metal electrode layers of titanium, platinum, and gold deposited on either side of it using an E-beam evaporator. The sample is then cleaned again with plasma and ozone, and then tested with radioactive sources. 

 

#9
Crystal Diffraction Simulations for a Compact X-Ray Light Source
Rick Hewitt, Arizona State University

The pioneering of femtosecond x-ray crystallography has allowed for the probing of biological molecules at atomic resolution. However, the x-ray free electron lasers (XFEL) that can produce the hard x-rays at the needed repetition rates are quite costly and require large facilities to operate them. The development of a compact x-ray light source (CXLS) based on inverse Compton scattering promises to greatly reduce the cost and needed facilities to perform crystallographic experiments. These simulations seek to determine the limitations imposed on these experiments due to the high divergence and lower flux of the CXLS.

 

#10
Materials Processing using Vortex Flow of Inductively Coupled Plasma
Keegan Karbach, Metropolitan State University of Denver

Using a counter-rotating vortex flow in a cyclonic separator, we hope to segregate particle size down to the sub-micron size for materials processing purposes. This poster will mainly go over the computational modelling of the apparatus as well as the concept of generation of an inductively coupled plasma in the device. This poster will be a summary of ongoing work. 

Electronics

Electronics

#11
Micromegas Front-End Electronics for the New Small Wheel in ATLAS
Casey Frantz, University of Arizona

In order to maintain muon detection performance with the increasing luminosity of the Large Hadron Collider, a New Small Wheel for the ATLAS experiment at CERN is being constructed using Micromegas detectors and small strip Thin Gap Chambers. Custom application-specific integrated circuits (VMMs) are used to amplify and digitize signals from the Micromegas detectors. An FPGA is used for ASIC configuration and readout. Demonstrator front-end electronics for Micromegas detectors in the New Small Wheel have been developed and tested. Results are presented for the noise performance on the bench and on Micromegas test detectors.  Data collected with an Fe-55 source is also presented.  Future plans for these electronics are given.

 

#12
Exploring Nonlinear Dynamics in Electronic Oscillators
Courtney Fleming, University of Colorado, Denver

Mathematical models of coupled oscillators provide the theoretical basis for describing an incredibly diverse range of nonlinear systems. These methods have been used to describe everything from oscillating chemical reactions to animal gates, but they are particularly powerful in the analysis of complex biological systems. The focus of our research has been to construct a versatile experimental model for systems of this nature using nonlinear electronic oscillators. In particular, we have built a Wien bridge oscillator circuit with the eventual goal of physically coupling multiple circuits and observing a variety of nonlinear phenomena. The generalized van der Pol equation is used describe a Hopf bifurcation within the Wien bridge, whereby the circuit transitions from a static state to one of sustained oscillations. In our case, the bifurcation parameter is resistance within a variable feedback resistor that acts as a nonlinear damping term. According to our mathematical model, this transition should occur suddenly when the resistance reaches threshold, however we have observed an unexpected transition state. The content of the poster to be presented will focus on characterizing these unexpected near-threshold fluctuations and summarizing our attempts to resolve and/or explain the phenomena as well as outlining next steps to couple a system of two oscillators.

Nuclear Physics

Nuclear Physics

#13
Experimental evaluation of the extended Dytlewski-style dead time correction formalism for neutron multiplicity counting
Madeline Lockhart, Texas Tech Univeristy

Over the past few decades, neutron multiplicity counting has played an integral role in Special Nuclear Material (SNM) characterization pertaining to nuclear safeguards. Current neutron multiplicity analysis techniques use singles, doubles, and triples count rates because a methodology to extract and dead time correct higher order count rates (i.e. quads and pents) was not fully developed. This limitation is overcome by the recent extension of a popular dead time correction method developed by Dytlewski. This extended dead time correction algorithm, named Dytlewski–Croft–Favalli(DCF), is detailed in reference Croft and Favalli (2017), which gives an extensive explanation of the theory and implications of this new development. Dead time corrected results can then be used to assay SNM by inverting a set of extended point model equations which as well have only recently been formulated. The current paper discusses and presents the experimental evaluation of practical feasibility of the DCF dead time correction algorithm to demonstrate its performance and applicability in nuclear safeguards applications. In order to test the validity and effectiveness of the dead time correction for quads and pents, 252Cf and SNM sources were measured in high efficiency neutron multiplicity counters at the Los Alamos National Laboratory (LANL) and the count rates were extracted up to the fifth order and corrected for dead time. In order to assess the DCF dead time correction, the corrected data is compared to traditional dead time correction treatment within INCC. The DCF dead time correction is found to provide adequate dead time treatment for broad range of count rates available in practical applications.

 

Astrophysics/Planetary Science

Astrophysics/Planetary Science

#14
Upgrading the Arecibo Potassium Lidar Receiver for Meridional Wind Measurements 
Ashley Piccone, Colorado School of Mines

Lidar can be used to measure a plethora of variables: temperature, density of metals, and wind. This REU project is focused on the set up of a semi steerable telescope that will allow the measurement of meridional wind in the mesosphere (80-105 km) with Arecibo Observatory’s potassium resonance lidar. This includes the basic design concept of a steering system that is able to turn the telescope to a maximum of 40°, alignment of the mirror with the telescope frame to find the correct focusing, and the triggering and programming of a CCD camera. <br>The CCD camera’s purpose is twofold: looking though the telescope and matching the stars in the field of view with a star map to accurately calibrate the steering system and determining the laser beam properties and position. Using LabVIEW, the frames from the CCD camera can be analyzed to identify the most intense pixel in the image (and therefore the brightest point in the laser beam or stars) by plotting average pixel values per row and column and locating the peaks of these plots. The location of this pixel can then be plotted, determining the jitter in the laser and position within the field of view of the telescope.

#15
Examining the Outer Solar System Through Analysis of Telescope Data
Teddy Anderson, University of Utah

There are over 2300 known Trans-Neptunian Objects (TNOs) in the outer solar system, including Pluto, its moon, and 200 other minor planets.  In recent years, a pattern emerged in the orbits of several of these TNOs with similar eccentricities and periods: the aphelia of their orbits are all oriented in the same direction.  This pattern is deemed by many astronomers to be unlikely due to chance alone.  A distant, unknown ninth planet has been invoked to explain the clustering of these orbits: Planet Nine (P9).  The model suggests P9 is about ten Earth masses, and averages 700 Astronomical Units (AUs) from the sun, with an orbital period of 15,000. years.  Our project searched for P9 by examining existing data from the Wide-Field Infrared Survey Explorer telescope, which is in low-Earth orbit, and has been gathering data in the infrared spectrum for seven years.  We examined this data by use of a code that called upon millions of combinations of these data, and culled them into about 2700 objects whose movement fits an orbit consistent with P9.  We looked at each of these moving objects individually and ruled out the possibility that any were P9.  However, some interesting and possibly undiscovered objects remain in our files which we are now examining more closely.  

#16
Using the Matched Runs Method to Observe an Extended Gamma-ray Source TEV J2032
Rylee Cardon, University of Utah

Very Energetic Radiation Imaging Telescope Array System (VERITAS) has been observing a wide variety of TeV-GeV gamma-ray sources for the last 10 years. This research observed an extended gamma-ray object TEV J2032 with a new analysis method called the Matched Runs Method (MRM). The MRM uses an observation taken under the same conditions as the run you are using to try to estimate the background. This technique for estimating the background increases the VERITAS sensitivity to extended sources. TEV J2032 is an extended source with an extent about 0.9°. This research utilized the MRM to observe TEV J2032. This paper will discuss why the standard analysis is at a disadvantage when analyzing extended sources, highlight the advantages of the MRM, sanity checks to confirm the background is correctly estimated, and the results of the TEV J2032 analysis.

#17
Mapping the Massive Dusty Outflow in the Perturbed Galaxy Zw049.057
Lauren Laufman, University of Wisconsin, Madison

The location and movement of gas and dust in galaxies is critical in understanding their evolution and formation. In Zw049.057, specific features such as a highly obscured nucelus and a massive yet slow outflow of dust and gas are indicative of an unusual history. By investigating the location and movement of the dust and gas in the outer regions, we can determine masses and infer how these flows relate to the obscured inner region.  We perform a method similar to that of overlapping galaxies by overlapping a mirrored image of Zw049.057 on itself to investigate dust features. Taking advantage of symmetry, we can then use the relative intensity of the dust obscured regions compared to ideally unobscured regions to estimate the amount of dust absorption in the visual, red, and infrared Hubble Space Telescope (HST) images. Dust opacities are estimated using a simple slab model with constant volume emissivity and no scattering. A galactic extinction curve gives the ratios of optical depths in each filter. From the opacities and extinction curves, we calculate a mean volume density of 24 atoms/cm^3. Several regions appear to be part of a thick linear dust feature extending a significant distance from the nucleus, which we estimate to contain on the order of 10^7 solar masses. We present evidence of a massive collimated outflow of dust and gas from the innermost regions, indicating the galaxy is in a phase of unusually rapid evolution.

#18
Radiation From the Stars
Bianca Giorgi, Grand Canyon University

Demonstration of Plank`s and Rayleigh-Jeans Law in regard to blackbodies and their behavior. <br>A blackbody is defined as a system which absorbs completely all the radiation that falls onto it; it then reaches some equilibrium temperature, and re-emits that energy as quickly as it absorbs it. In order to observe and understand this system, two formulas were released. First the Rayleigh-Jeans Law attempted to describe the behavior of a blackbody; however, it strongly disagrees with nature, thus leading to the prediction of the so-called ultraviolet catastrophe. The second equation which is congruent with the comportment of such a body was formulated by Max Plank. To show how this latter constitutes a better model as far as short wavelengths are concerned—which was also where the first law failed, the limit of Plank’s Law was taken as the wavelength approached both zero (from the right) and infinity. In both cases, the limit approaches zero. This results in a better representative model for short wavelengths of blackbody radiation because if the limit were to approach infinity—as in the case of the Rayleigh-Jeans Law, the consequence would be the ultraviolet catastrophe. As far as long wavelengths are concerned, both laws lead to approximately the same results. To demonstrate this concept, the first thing that needs to be achieved is the representation of Plank’s Law in terms of a Taylor Polynomial. Moreover, two stars were studied and analyzed: Betelgeuse and Sirius. The importance of the latter topic is relevant if one considers these two celestial bodies as the future of our own Sun. 

#19
Uncovering the Past with Red Giant Stars in the Andromeda Galaxy
Candace Bryan, University of Utah

The oldest stars in a galaxy can tells us about the early stages of that galaxies history. Discovering the ages of stars plays an important role in research about the early universe and our origins. However, measuring the ages of stars is complicated.  The goal of my project is to age date old, bright red giant stars in the Andromeda galaxy, the nearest large galaxy to our own Milky Way.  The age of these red giant stars can be measured if we know their luminosity, temperature, and composition.  We measure their temperature and luminosity using the PHAT survey, a Hubble Space Telescope imaging survey of Andromeda.  However, to obtain information on the composition of a star, known as its metallicity (the total amount of heavy elements in a star), we need additional information.  This information comes from spectra of stars from the Keck telescope.  Because the stars are faint, we combine or “stack” spectra to measure the average composition and infer the average age of stars at different compositions. We present our preliminary results in this poster.

#20
Using Photometry to Determine IMF in Low-Metallicity Environments
Emily Apel, Arizona State University

Our project aims to determine whether the initial mass function (IMF) of star clusters in low metallicity galaxies varies with cooling. . Metal poor environments, which we define as environments comprised of primarily hydrogen and helium, lack metals that are efficient for cooling, and it is environments such as this that we expect to see in star-forming regions of the early universe. We will use spectroscopy to measure the 158-micron CII line, which is a prominent spectral line in star-forming regions, to trace the strength of cooling in these regions. Low cooling should skew the IMF towards higher masses, so expect to see very high mass stars in these metal poor regions..We will use photometry to determine the IMF in our target galaxies. I present on the development of our methods for performing photometry on a well-studied tested galaxy. We utilize IDL as a tool for the data reduction required to produce a clean science image ready for analysis. To determine stellar flux, DAOPHOT best handles spatial confusion of the stars, but it does not fully account for the light scattered due to the optics of the instruments. Performing aperture photometry on isolated stars in our images will thus offset these effects.<br>Determining adjustments that must be made in our measurements will be critical in the development of accurate methods to determine the IMF. We will use photometry on our test galaxy to examine the flux of stars in different filters, allowing us to determine not only the magnitudes but also the color of the stars. With the color, we can determine the temperature and mass of these stars and from these quantities, we produce an IMF. Once we have a well-tested, fully developed method for determining the IMF in our test galaxy, we will be able to apply it to our other target galaxies to further examine the IMF

#21
Classifying the Fundamental Plane in the Shapley Supercluster
Kira Simpson, Swarthmore College

The Shapley Supercluster is one of two closeby candidates that serve as cluster interaction laboratories. It has been observed recently that the supercluster consists of twelve clusters that appear to be gravitationally bound, but the evolution of the supercluster is as yet unknown. The emphasis of this project is to classify the galaxies and their effective radii by fitting the Kormendy relation, a scale relation between surface brightness and effective radii, to the galaxies within the region observed. Inferring radii from this relation, we can then classify the fundamental plane of elliptical galaxies within the cluster and infer the velocity dispersion. Seeing that velocity dispersion is dependent on the distance from the center of the supercluster, we have a way to better classify the kinematics and see if the various substructures are collapsing toward the center or moving away from each other.<br>This project involves data taken by the IMACS camera at the Las Campanas observatory. This camera`s photon-collecting surface is made of eight charge-coupled device (CCD) chips. The challenge of performing photometric analysis on the images comes in the assembly of the images. Each field consists of the images taken by each of the eight chips, which must be put together and corrected to perform photometric analysis. Our job is to assemble the images and then perform photometric analysis in order to find the surface brightness and effective radii, thus bringing us one step closer to determining the relative positions of the substructures of the supercluster.

#22
Determining the Ages and Distances of 4 Open Clusters 
Erica Sawczynec, University of Hawaii at Manoa

The study of nearby young open clusters can give insight into star formation and potentially the local rate of metal enrichment. Presented is a BVRI photometric analysis of 4 open clusters; NGC 2509, NGC 2483, NGC 2482, and NGC 6705, in order to reevaluate previously published ages and distances using modern CCD photometry, and newer stellar models. Observations were obtained from the Cerro Tololo node of the Las Cumbres Observatory 1.0 meter network. Color magnitude diagrams were compared to modeled PARSEC and Dartmouth isochrones and the updated ages and distances determined. An interesting stellar association was found in the color magnitude diagram of NGC 6705. The structure is suggestive of two epochs of stellar formation.  Members of this structure were evaluated using the Gaia Archive in order to explore the possibility of a heterogeneous population. The status of NGC 2483 as an open cluster has been debated; however, it has been noted that there is a high concentration of Be stars found in the region. It is concluded that NGC 2483 is an open cluster.

#23
Short-lived Radionuclides in Assymetric Supernovae
Charlotte Johnson, Arizona State University

Supernovae are vital to supplying necessary elements to forming bodies in solar systems. This project is interested in the creation of a subset of these necessary elements, called short-lived radionuclides (SLRs). These isotopes with short half-lives can serve as heat sources for forming planets, and their traces can be used to determine when stellar explosions occured. In this project, nucleosynthesis postprocessing analysis is performed on existing 3D supernovae simulations to computationally study the creation of SLRs. The SLRs we are particularly interested in are 26Al, 60Fe, and 41Ca, traces of which can be found in our own solar system. Another aspect of this project studies the ratio of these SLRs to other supernovae elements whose spectra are more observable with a goal of finding ratios of spectrally observable elements that indicate the presence of one or more SLR, leading to better chances of observational detection of SLRs.

 

#24
A Comparison of Mixing in Stellar Evolution Codes Tycho and Geneva
Cierra Huff, Arizona State University

This paper compares the Tycho and Geneva stellar evolution codes. Standard stellar evolution models do not match observations without adjusting free parameters, yet predictive models are essential. We examine the level at which Tycho’s addition of hydrodynamic mixing affects massive star evolution by comparing models with the widely-used Geneva tracks. <br>Geneva utilizes mixing-length theory (MLT) and the Schwarzschild criterion to determine the stability and size of a star’s convective zone. MLT is a local theory and thus does not provide an accurate description at the zone’s boundaries; in order to achieve the mixing inferred from observations, models need to be tuned using a free parameter (convective overshooting). Tycho aims to improve this calibrated approach by accounting for hydrodynamics and using the same convection and boundary methods for the entire star. It considers the stability of the medium relative to all energy inputs, including energy from convective motions and rotation. The size of the convective zone is determined using the velocities calculated from the added hydrodynamics (buoyancy force and turbulent dissipation). The Richardson criterion is utilized to evaluate the extent of the turbulently mixed region. These parameters provide a smooth transition from zone to zone through the star.<br>Nine models of different masses and metallicities were computed using Tycho and compared to the publicly available Geneva tracks. The Tycho models did not include rotation for this initial study, but were compared to both rotating (Vinit/Vcrit= 0.4) and non-rotating (Vinit/Vcrit= 0) Geneva models. It was found that Tycho produced systematically higher stellar luminosities and lifetimes compared to equivalent models. Tycho also showed the main sequence systematically going to lower temperatures than Geneva. Lastly, the non-rotating Tycho models were found to differ from non-rotating Geneva tracks by an amount comparable to the rotating Geneva tracks.

#25
Simulating Galaxy Outflow Effects in the Circumgalactic Medium
Gabby Huckabee, Arizona State University

The properties of galaxy outflows can be indicative of the history of a galaxy, implying periods of starburst or stagnation depending on the strength and composition of the outflows.  These hot outflows affect the circumgalactic medium (CGM) surrounding a galaxy, leaving observable traces in the cold CGM gas that can be analyzed in order to infer a galactic evolution.  This study builds on previous hydrodynamic simulations of hot gas flowing over cold gas clouds with varied parameters, such as wind velocity and the presence or absence of physical effects like thermal conduction, radiative cooling, and certain non-negligible chemical reactions.  Currently, detailed analyses of completed thermal conduction runs are being conducted using Python packages yt and Trident to produce ion distribution graphs and spectra which could possibly be observed in an actual CGM image.  The next step in this project is to mesh together previous findings in a single hydrodynamic simulation that accounts for chemistry and thermal conduction simultaneously in order to produce results more true to reality that could potentially be observed with a telescope like the James Webb.  One future step for this study is including magnetic fields in a similar simulation.

 

 

Quantum Physics

Quantum Physics

#26
Mass renormalisation in Phi-fourth Theory
Bilgai Almeida-Zamora

In this work we calculate the 2-point Green function for a Phi-fourth  Quantum Field Theory. Using this Green function we find that in the interacting theory the mass of the scalars (bosons) has a divergence that can be renormalised. Finally, we discuss about the renormalisation program for this theory and its implications for the calculation of observables.

 

#27
Spontaneous Symmetry Breaking in  Scalar Quantum Electrodynamics
Paulina Valenzuela, Universidad de Sonora

In this work analyze the spontaneous symmetry breaking (SSB) in a phi^4 theory. Using this study, we explore SSB for scalar  quantum electrodynamics (sQED). As the classic phi^4  theory, we also found in sQED that a Goldstone boson emerges after SSB,  hand in hand with a massive scalar boson and a massive vector boson.

Flash Talks

Flash talks are 10 minute talks given by undergraduate students, describing their own research. They will be given at a plenary session on Sunday morning. The below are the talk titles, abstracts and authors selected for this session.

Graphene Nanodisk Arrays for Biosensing with Spatial Resolution
Lauren Zundel, The University of New Mexico

The collective oscillations of conduction electrons in a metallic material, known as surface plasmons, have emerged as a powerful sensing tool because of their extraordinary ability to confine and enhance light. Nanostructures made of graphene, which have been shown to support strong plasmon resonances in the infrared part of the spectrum, have shown strong potential to be used for the development of versatile biosensors, due to the unique ability to tune their resonances by means of electrical doping. Here, we take advantage of these properties to design an optical sensor with sub-diffraction limit spatial resolution. To this end, we propose a device consisting of an array of identical nanodisks divided into subarrays, or pixels, each of which can be tuned individually to a uniform doping level. Therefore, by adjusting the doping level of each one of these pixels separately, they can be sequentially brought into resonance with the spectrum of an analyte, thus enabling the detection of both its presence and location. The results of this work help to set the foundations for the development of novel label-free infrared sensors, opening doors for new applications to sense the chemical composition of complex biological structures with temporal and spatial resolution.

Radiation From the Stars
Bianca Giorgi, Grand Canyon University

Demonstration of Plank`s and Rayleigh-Jeans Law in regard to blackbodies and their behavior. <br>A blackbody is defined as a system which absorbs completely all the radiation that falls onto it; it then reaches some equilibrium temperature, and re-emits that energy as quickly as it absorbs it. In order to observe and understand this system, two formulas were released. First the Rayleigh-Jeans Law attempted to describe the behavior of a blackbody; however, it strongly disagrees with nature, thus leading to the prediction of the so-called ultraviolet catastrophe. The second equation which is congruent with the comportment of such a body was formulated by Max Plank. To show how this latter constitutes a better model as far as short wavelengths are concerned—which was also where the first law failed, the limit of Plank’s Law was taken as the wavelength approached both zero (from the right) and infinity. In both cases, the limit approaches zero. This results in a better representative model for short wavelengths of blackbody radiation because if the limit were to approach infinity—as in the case of the Rayleigh-Jeans Law, the consequence would be the ultraviolet catastrophe. As far as long wavelengths are concerned, both laws lead to approximately the same results. To demonstrate this concept, the first thing that needs to be achieved is the representation of Plank’s Law in terms of a Taylor Polynomial.

Examining the Outer Solar System Through Analysis of Telescope Data
Teddy Anderson, University of Utah

There are over 2300 known Trans-Neptunian Objects (TNOs) in the outer solar system, including Pluto, its moon, and 200 other minor planets. In recent years, a pattern emerged in the orbits of several of these TNOs with similar eccentricities and periods: the aphelia of their orbits are all oriented in the same direction. This pattern is deemed by many astronomers to be unlikely due to chance alone. A distant, unknown ninth planet has been invoked to explain the clustering of these orbits: Planet Nine (P9). The model suggests P9 is about ten Earth masses, and averages 700 Astronomical Units (AUs) from the sun, with an orbital period of 15,000. years. Our project searched for P9 by examining existing data from the Wide-Field Infrared Survey Explorer telescope, which is in low-Earth orbit, and has been gathering data in the infrared spectrum for seven years. We examined this data by use of a code that called upon millions of combinations of these data, and culled them into about 2700 objects whose movement fits an orbit consistent with P9. We looked at each of these moving objects individually and ruled out the possibility that any were P9. However, some interesting and possibly undiscovered objects remain in our files which we are now examining more closely.

Survey of Ion Coordination Geometries of Structures in the Protein Data Bank
Kathleen Clark, Arizona State University

According to some estimates, between 30% and 40% of all proteins depend on interactions with ions to perform their function. Ions can be a part of an active site in an enzyme, part of a substrate, or play a structural role. In order to understand the molecular mechanisms in all of these cases, it is important to have an accurate description of the interactions of these ions with amino acid sidechains, the protein backbone, water molecules, and cofactors. An automated analysis method was developed to analyze cations contained in crystal structures in the RCSB Protein Data Bank (PDB). The ion coordination geometries of the most prevalent monovalent cations in the PDB (sodium, potassium, lithium, and thallium) were analyzed from the radial distribution functions of oxygen atoms around ions. Monovalent cations coordinate oxygen atoms within about a 6 Å radius, with a clear first “hydration shell,” similar to the first hydration shell in bulk water, and a secondary shell also typically visible. However, oxygen atoms are not the only atoms that can be coordinated by cations, and coordinating atoms for anions are much less well characterized than those for cations. We therefore analyzed all atoms within 6 Å of the cations as well as chloride anions using distance and force-field derived partial charges as criteria to identify atoms that are likely a part of the coordination shells. The code is written in Python and is freely available under the GNU Public License v3 at https://github.com/Becksteinlab/PDB_Ion_Survey.