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PHYS2018SENGER4580 PHYS

Observing Massive Gas Outflow from Supernovae Explosions around the Large Magellanic Cloud Galaxy

Type: Undergraduate
Author(s): Brian Senger Physics & Astronomy
Advisor(s): Kat Barger Physics & Astronomy

Within 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.

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PHYS2018SUN34899 PHYS

Star-formation activity in isolating and interacting low-mass galaxies

Type: Graduate
Author(s): Jing Sun Physics & Astronomy Hannah Richstein Physics & Astronomy
Advisor(s): Kat Barger Physics & Astronomy

Interaction 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.

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PHYS2018TULADHAR48357 PHYS

Studying the effects of antiarrhythmic drugs on restitution properties of action potential duration of canine ventricular cells.

Type: Graduate
Author(s): Binaya Tuladhar Physics & Astronomy
Advisor(s): Hana Dobrovolny Physics & Astronomy

Restitution 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.

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PHYS2018TURNER45316 PHYS

Spatiotemporal Analysis of Respiratory Tract Infection Dynamics

Type: Undergraduate
Author(s): Cole Turner Physics & Astronomy
Advisor(s): Hana Dobrovolny Physics & Astronomy

Respiratory 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.

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PHYS2017CIAMPA7324 PHYS

Supernovae in Large Magellanic Cloud Drive Massive Winds Toward Milky Way Galaxy

Type: Graduate
Author(s): Drew Ciampa Physics & Astronomy
Advisor(s): Kat Barger Physics & Astronomy

Located inside the Large Magellanic Cloud, fierce explosions called supernovae have thrown out massive amounts of gas in every direction. A portion of this gas is aimed toward the Milky Way and is on a crash course with our galaxy. We are observing this gas with the Wisconsin H-Alpha Mapper, which provides a window into how the gas is distributed. These observations show two periods of supernovae explosions that created two distinct gas winds. One of these winds is currently active while the other was produced roughly 300 Million years old. Studying these gas clouds will provide information on how massive these winds are and the rate at which they are produced. The ejected gas is headed toward the Milky Way could supply our galaxy with additional gas to form stars in the future.

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PHYS2017HASAN32286 PHYS

Tuning the Optical Band Gap of Graphene Oxide by Ozone Treatment

Type: Graduate
Author(s): Md Tanvir Hasan Physics & Astronomy Roberto Gonzalez-Rodriguez Chemistry & Biochemistry Anton Naumov Physics & Astronomy Conor Ryan Physics & Astronomy Brian Senger Physics & Astronomy
Advisor(s): Anton Naumov Physics & Astronomy

Graphene oxide (GO) inherits high transparency, substantial conductivity, high tensile strength from its parent materials graphene. Apart from these properties, it emits fluorescence which makes it a potential material to use in optoelectronics and bio-sensing applications. In this work, we have utilized systematic ozone treatment to alter the optical band gap of single-layered graphene oxide in aqueous suspensions. Due to controlled ozonation, additional functionalization takes place in GO graphitic sheet which changes GO electronic structure. This is confirmed by the increase in vibrational transitions of a number of oxygen-containing functional groups with treatment and the appearance of the prominent carboxylic group feature at c.a. 1700 1/cm. Albeit, timed ozone induction introduces only slight change in color and absorption spectra of GO samples, the emission spectra show a gradual increase in intensity with a significant blue shift up to 100 nm from deep red to green. This large blue shift suggests an increase in optical band gap with additional functionalization introduced by ozone treatment. We utilize a semi-empirical theoretical approach to describe the effects of functionalization-induced changes. This model attributes the origins of fluorescence emission to the quantum confined sp² carbon islands in GO encircled by the functional groups. As we decrease the graphitic carbon cluster size on the GO sheet, the optical bandgap calculated via HyperChem molecular modeling increases, which supports the experimentally observed blue shifts in emission. This theoretical result is further supported by the TEM measurement of ozone-treated samples, which shows a decreasing trend of average ordered graphitic carbon cluster size on GO sheets with treatment time. Theoretical modeling, as well as the experimental results, indicate that the optical bandgap and emission intensity of GO are alterable with controlled ozone treatment, which allows tailoring the optical properties of GO for specific applications in optoelectronics and bio-sensing.

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PHYS2017MELENDEZ16706 PHYS

The Open Cluster Chemical Abundances and Mapping (OCCAM) Survey: Optical Extension for Neutron Capture Elements

Type: Graduate
Author(s): Matthew Melendez Physics & Astronomy John Donor Physics & Astronomy Peter Frinchaboy Physics & Astronomy Julia O'Connell Physics & Astronomy
Advisor(s): Peter Frinchaboy Physics & Astronomy

The Open Cluster Chemical Abundances and Mapping (OCCAM) survey is a systematic survey of Galactic open clusters using data primarily from the SDSS-III/APOGEE-1 survey. However, neutron capture elements are limited in the IR region covered by APOGEE. In an effort to fully study detailed Galactic chemical evolution, we are conducting a high resolution (R~60,000) spectroscopic abundance analysis of neutron capture elements for OCCAM clusters in the optical regime to complement the APOGEE results. As part of this effort, we present Ba II, La II, Ce II and Eu II results for a few open clusters without previous abundance measurements using data obtained at McDonald Observatory with the 2.1 m Otto Struve telescope and Sandiford Echelle Spectrograph.

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PHYS2017RAY20657 PHYS

A Survey of Nearby M-dwarfs with Robo-AO

Type: Graduate
Author(s): Amy Ray Physics & Astronomy Angelle Tanner Physics & Astronomy
Advisor(s): Peter Frinchaboy Physics & Astronomy

The goal of this study was to conduct a survey of 913 M-dwarf stars from the Lepine and Shara Proper Motion(LSPM) catalog within 33 parsecs. This research was conducted to improve upon the statistics of nearby multiple M-dwarf star systems. Identifying and confirming multiple systems at both wide and small separations will expand understanding of M-dwarf formation by comparing these results to existing star formation models. Data for these targets was collected with the Robo-AO camera on the Palomar 60in telescope. Separation and position angles were determined and compared for two epochs of the images containing multiple stars, one taken in 2012 and the other taken in 2014, to look for changes in these values. Stars with little change in position with respect to one another suggest they are common proper motion pairs. The Washington Double Star(WDS) catalog and other resources were used to further determine binarity. There were 50 multiple star system candidates found with a multiplicity fraction of 28.6±3.0 and a companion star fraction of 34.7±2.1.

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PHYS2017SUN7458 PHYS

Star formation in galaxies

Type: Graduate
Author(s): Jing Sun Physics & Astronomy
Advisor(s): Kat Barger Physics & Astronomy

A galaxy environment influences its internal properties. All galaxies start out small and grow bigger after merging with other galaxies. We are conducting a statistical study on isolated and interacting galaxies to determine how their environment impacts on their star-formation ability. We are using observations from the Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey, which has already observed more than 3000 galaxies. We are examining the differences and similarities of the gas and stars in isolated and interacting galaxies to explore their past and current star formation activity. From these comparisons, we will identify which conditions promote and hinder star formation to learn how different types of galaxies evolved. An example of an isolated galaxy is shown here.

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