PHYS2018RAY7452 PHYS
Type: Graduate
Author(s):
Amy Ray
Physics & Astronomy
Advisor(s):
Peter Frinchaboy
Physics & Astronomy
View PresentationStar clusters are key chemical and age tracers of Milky Way evolution. The use of star clusters to provide significant constraints on galaxy evolution, however, has been limited due to discrepancies between different studies. This work seeks to add additional open clusters into an existing large, uniform chemical abundance system. We analyze spectra of giant stars in 31 open clusters and, using a machine learning method called The Cannon, determine iron abundances. This uniform analysis is compared with previous results, and we present new chemical abundances of 12 star clusters.
PHYS2018REEKS5125 PHYS
Type: Graduate
Author(s):
John Reeks
Physics & Astronomy
Bao Thach
Engineering
Advisor(s):
Yuri Strzhemechny
Physics & Astronomy
View PresentationNanoscale zinc oxide (ZnO) is an inexpensive, widely accessible material used in numerous well-established and emerging applications due to the unique optoelectronic, structural and chemical properties as well as the variety of synthesis methods. One of these emerging applications of ZnO nanostructures is in the field of antibacterial tools. The antibacterial nature of this material is being actively investigated, yet the mechanisms behind remain largely unknown. Some studies indicate that there is an influence of the polarity of exposed ZnO surfaces on their antibacterial action. Crystalline ZnO forms hexagonal prisms due to an anisotropic hexagonal lattice, which in turn produces three primary surface types: Zn-polar, O-polar and nonpolar. The hexagonal faces of these prism-shaped crystals are polar while the rectangular surfaces are nonpolar. In this study we employ a hydrothermal chemical method for growing ZnO nanocrystals having tunable morphology with the aim of obtaining a reliable control of the predominant polarity of the exposed nanocrystalline surfaces. This in turn can serve as a platform to investigate mechanisms of antibacterial action. Using Scanning Electron Microscopy as a probe of the microcystal morphology we demonstrate that the predominant ZnO surface polarity can be affected through the variations in the chemical precursors of the hydrothermal process. The ability to control the morphology and prominent surface polarity of ZnO nanocrystals would allow us to investigate fundamental phenomena governing antibacterial characteristics of nanoscale ZnO.
PHYS2018RICHSTEIN7035 PHYS
Type: Undergraduate
Author(s):
Hannah Richstein
Physics & Astronomy
Jing Sun
Physics & Astronomy
Advisor(s):
Kat Barger
Physics & Astronomy
(Presentation is private)Galaxies are not alone in space; often, they have neighboring galaxies with which they gravitationally interact. These interactions foster diverse characteristics, such as size, morphology, and color. This project studies the properties of galaxies in the context of their neighbors and environment. More specifically, I examine how the proximity between galaxies affects their evolution. I do this by exploring two samples: 1) galaxy pairs within a few galactic diameters of each other and 2) isolated galaxies separated from the next nearest galaxy by more than ~450,000 light years. Using existing Mapping Nearby Galaxies at Apache Point Observatory observations, part of the Sloan Digital Sky Survey IV, I determine the various types of ionization conditions present at different radii throughout each galaxy. Through these efforts, I explore which processes promote and hinder star formation within galaxies.
PHYS2018RODRIGUEZ18820 PHYS
Type: Graduate
Author(s):
Thalia Rodriguez
Physics & Astronomy
Advisor(s):
Hana Dobrovolny
Physics & Astronomy
View PresentationIn vitro experiments are necessary to understand the processes driving viral infections and to develop antivirals and vaccines. However, experiments do not completely replicate the in vivo environment, and not all cell lines used in these experiments have the components necessary to support viral replication. In these cases, the missing elements are added to the medium to facilitate viral infections. Trypsin is an enzyme usually added to facilitate influenza infections in cell cultures. We use data from infections of influenza in different cell lines in the presence and absence of trypsin to parameterize a within-host mathematical model of influenza infection, and in this way understand the impact of trypsin in the dynamics of the infection.
PHYS2018RYAN16053 PHYS
Type: Undergraduate
Author(s):
Conor Ryan
Physics & Astronomy
Fabian Grote
Physics & Astronomy
Anton Naumov
Physics & Astronomy
Thomas Paz
Physics & Astronomy
Advisor(s):
Anton Naumov
Physics & Astronomy
View PresentationGraphene is a promising material, due to its various inherent properties that will lead to better, smaller, faster, or flexible electronics. Graphene doesn’t exhibit optical emission, limiting its potential use in optoelectronics. However, graphene’s functional derivative Graphene Oxide (GO) maintains many of graphene’s properties and exhibits optical fluorescence emission in the visible/near-infrared, which makes it a candidate for novel applications such as optoelectronic transistors, light emitting diodes (LEDs), and solar cells. Therefore, finding a way to alter optical and electronic properties of GO will lead to more versatility and control among the aforementioned applications.
In this work, we studied the potential use of GO for microelectronic applications by observing the fluorescence of this material under the electric field. A dried GO/PVP film was subject up to 1.6 V/µm in between transparent conductive ITO electrodes resulting in observable quenching of fluorescence emission as the field was applied. The emission was further partially restored at 0 field. Additionally, microscopic flakes of graphene oxide deposited onto interdigitated 10 µm electrodes were subject to 100V/µm with no breakdown current detected. The fluorescence of individual flakes, observed via visible fluorescence microscopy, experienced substantial field-dependent quenching. In aqueous suspensions GO flakes exhibited electrophoretic migration signifying of charge separation. As a result of this work we suggest the potential of varying electronic and optical properties of graphene oxide via the electric field for the advancement and control over its optoelectronic device applications.
PHYS2018SENGER4580 PHYS
Type: Undergraduate
Author(s):
Brian Senger
Physics & Astronomy
Advisor(s):
Kat Barger
Physics & Astronomy
View PresentationWithin the Large Magellanic Cloud (LMC) galaxy, there are huge gaseous outflows that originated from violent supernovae explosions within this galaxy. Observing this outflow that is being kicked out from the LMC reveals that there is ionized gas present, which can be trace by using Ha emission. Using observations from the Wisconsin Ha Mapper (WHAM) in Chile, we are mapping out the Ha emission that is being kicked out of the LMC. In this project, I am removing the imprint of the Earth’s atmosphere in order to isolate the gas cloud. This will be used to determine how much gas is being thrown out of the galaxy. The more gas the galaxy loses, the more it would not be able to make stars in the future.
PHYS2018SUN34899 PHYS
Type: Graduate
Author(s):
Jing Sun
Physics & Astronomy
Hannah Richstein
Physics & Astronomy
Advisor(s):
Kat Barger
Physics & Astronomy
View PresentationInteraction between galaxies is of critical importance to the formation and evolution of galaxies. We are conducting a study on both isolated and interacting low-mass galaxies to determine how their environment impacts their star-formation ability. We compare the features of gas and stars in isolated and interacting galaxies to examine the differences and similarities. The interaction-triggered star-formation activity will be further discussed to analyse how the internal properties of galaxies are influenced by the outer environment. This investigation is based on data from the fourth-generation Sloan Digital Sky Survey (SDSS-IV) / Mapping Nearby Galaxies at Apache Point Observatory (MaNGA), and is part of the project No.0285 in SDSS-IV.
PHYS2018TULADHAR48357 PHYS
Type: Graduate
Author(s):
Binaya Tuladhar
Physics & Astronomy
Advisor(s):
Hana Dobrovolny
Physics & Astronomy
View PresentationRestitution describes a functional relationship between the action potential duration (APD) and the preceding diastolic interval (DI). It plays an important role in the function of the heart and is believed to determine the stability of heart rhythms. We investigate the effects of various antiarrhythmic drugs on dynamic and standard (S1-S2) restitution properties of APD of ventricular cells by using a canine ventricular cell model. The restitution hypothesis suggests that the slope of the restitution curve governs the transition to alternans, believed to be a precursor to the development of ventricular arrhythmias, particularly ventricular fibrillation (VF). Our study examines the slope of these restitution curves for three classes of drug to determine whether they are proarrhythmic or antiarrhythmic and to test the hypothesis for the prediction of alternans.
PHYS2018TURNER45316 PHYS
Type: Undergraduate
Author(s):
Cole Turner
Physics & Astronomy
Advisor(s):
Hana Dobrovolny
Physics & Astronomy
View PresentationRespiratory tract infections are easily among the most diagnosed illnesses in modern medicine, especially involving infants and the elderly. Lower respiratory tract infections (LRTIs) are especially dangerous, often capable of producing lasting respiratory problems, increased hospitalization, and life-threatening illness. Our research is targeted towards uncovering a possible mechanism behind the spreading of LRTIs, in hopes of illuminating the connection between the diffusion of a given virus and the speed of mucous transfer within the respiratory tract. This project more specifically focuses on a system of nonlinear ordinary and partial differential equations which simulate the diffusion and advection driven dynamics of an infected respiratory system. With a more realistic spatiotemporal approach, we hope to find possible relationships between given rates of advection and diffusion, and the depth and duration of infection; a potential framework for understanding and preventing an otherwise refractory human affliction.
PSYC2018ARROWOOD64252 PSYC
Type: Graduate
Author(s):
Robert Arrowood
Psychology
Caroline Angell
Psychology
Jill Hoffman
Psychology
Maddie Weinstock
Psychology
Advisor(s):
Cathy Cox
Psychology
View PresentationTerror Management Theory suggests that individuals rely on worldview defenses to contend with mortality concerns. Similarly, religious individuals bolster their specific beliefs in order to defend against the awareness of death. Five studies examined the intersection between quest religiosity (e.g., individuals whose religious worldviews are to doubt and question), worldview defense, and existential anxieties. We hypothesized that quest individuals have weakened religious beliefs causing greater death thought accessibility. Additionally, quest individuals should display heightened secular worldview striving following mortality salience and less certainty in their own religiosity.