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PHYS2018BARTH2896 PHYS

A Stochastic Differential Equation Model of Virus Replication

Type: Undergraduate
Author(s): Dylan Barth Physics & Astronomy Hana Dobrovolny Physics & Astronomy
Advisor(s): Hana Dobrovolny Physics & Astronomy
Location: Session: 2; Basement; Table Number: 10

poster location

In this experiment we take the differential equation model from Heldt 2012 for the viral life cycle and apply a stochastic algorithm in order to simulate random events on a molecular level. We then introduce a known mechanism by which to mutate the produced virus particles and attempt to understand the relationship between surface proteins and these random mutations. This work will shed light on the efficacy of particular antiviral drugs that act on the binding of surface proteins to the cell membrane.

(Poster is private)

PHYS2018CIAMPA9117 PHYS

Massive Winds Triggered by Supernovae in the Large Magellanic Cloud

Type: Graduate
Author(s): Drew Ciampa Physics & Astronomy
Advisor(s): Kat Barger Physics & Astronomy
Location: Session: 2; 1st Floor; Table Number: 1

poster location

Nearby, the Large Magellanic Cloud galaxy (LMC), has ejected massive amounts of gaseous material, some of which is headed toward the Milky Way. The material consists of ionized hydrogen gas which is a consequence of significantly energetic events that have occurred in the LMC. Such events are not only the cause of the ionized material, but also the immense amount of material being thrown out. This ejected wind holds a substantial amount of information regarding both galaxies in general and the LMC’s physical processes. Studying this ionized outflow will reveal new details concerning the internal processes that produce such massive ejections, the potential for galactic outflows to replenish gas reservoirs for future star formation, and the environments surrounding galaxies. The latter will influence our view of a galaxy’s environment and how it may interact with nearby neighbors such as our Milky Way galaxy.

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PHYS2018DOAN3019 PHYS

Novel Techniques of Estimating the Spectro-Photometer Correcting G-Factor

Type: Graduate
Author(s): Hung Doan Physics & Astronomy Luca Ceresa Physics & Astronomy Jose Chavez Physics & Astronomy Harris To Physics & Astronomy
Advisor(s): Karol Gryczynski Physics & Astronomy
Location: Session: 1; 1st Floor; Table Number: 4

poster location

Fluorescence anisotropy is a common measurement that helps provides important information on molecular mobility, solvent (environment) viscosity, or/and molecular size. Fluorescence anisotropy involves measurement of two orthogonally polarized light emission intensities. One of the common issues of fluorescence anisotropy measurements is that most optical detection systems respond differently to the parallel and perpendicular polarization of light. The challenging task is to estimate the calibration curve, often called as the instrumental G-factor (grating factor), a parameter indicates the contributions and/or distortion of the optical detection system to the parallel and/or perpendicular light polarization, so that one can correct their polarized emission intensity and obtain a proper fluorescence anisotropy result. Here we present novel techniques that we have been developed in our laboratory that help achieve the G-Factor curves for different instruments.

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PHYS2018DONOR57222 PHYS

A Uniform Measurement of the Galactic Abundance Gradient

Type: Graduate
Author(s): John Donor Physics & Astronomy Matthew Melendez Physics & Astronomy Julia O'Connell Physics & Astronomy
Advisor(s): Peter Frinchaboy Physics & Astronomy
Location: Session: 1; 1st Floor; Table Number: 3

poster location

Despite living inside the Milky Way, we do not know well basic quantities such as its detailed chemical makeup at the level needed to fundamentally tie the Milky Way to studies of evolution in other galaxies. One key observable is the radial chemical abundance gradient. Open star clusters provide an age datable sample by which to measure this gradient. This measurement has previously been made using a diverse and regularly conflicting compilation of clusters from various literature studies. We present the first measurement using a large (462 stars in 28 open clusters), uniform sample of open clusters abundances. Our measurements show a general agreement with recent studies of the overall metallicity gradient, with a measured ∆ [Fe/H]/∆ RGC of -0.050 ± 0.004 dex/kpc. We also explore trends with distance from the galactic plane and cluster age, and finally investigate the existence of a "knee" in the overall abundance gradient, between 12-14 kpc, within the range suggested by previous work. We show strong evidence for this phenomenon.

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PHYS2018HASAN12433 PHYS

Multi-Color Bioimaging With Graphene Quantum Dots

Type: Graduate
Author(s): Md Tanvir Hasan Physics & Astronomy Giridhar Akkaraju Biology Roberto Gonzalez-Rodriguez Physics & Astronomy Anton Naumov Physics & Astronomy Elizabeth Sizemore Physics & Astronomy
Advisor(s): Anton Naumov Physics & Astronomy
Location: Session: 2; Basement; Table Number: 5

poster location

Since a number of medical conditions require simultaneous treatment and diagnostics, the field of molecular therapeutics has recently turned to multifunctional approaches allowing for both therapy and biomedical imaging. A number of such molecular and nanoformulations are combined with fluorophores that allow for imaging of the delivery pathways of the drug in the visible. This is optimal for in-vitro or ex-vivo work, however, cannot be utilized well in-vivo. Thus, there is a need in nanoformulations optimized for both in-vitro and in-vivo studies. Graphene quantum dots, possessing intrinsic stable fluorescence in the visible and near-IR stand out as candidates for such complex application.

In this work, we for the first time produce biocompatible graphene quantum dots (GQDs) that exhibit multi-color emission both in visible and NIR possess a capability for biological pH sensing. These GQDs show the crystalline graphitic structure in TEM and average sizes of c.a. 5 nm beneficial for cellular internalization. They show no cytotoxicity even at high doses of 1 mg/mL that are used for imaging. As opposed to related structures such as graphene oxide and other graphene derivatives GQDs show high quantum yield in green (~500 nm) of ~50%. Near-IR emission at ~860 nm is located in the water window with reduced absorption and lower autofluorescence backgrounds providing a promising potential route for in-vivo studies. Emission of GQDs also depends on pH of the surrounding medium. The change in pH of as-prepared GQDs from 2.70 to 8.0 yields an increase of fluorescence intensity up to ~60%. Additionally, pH-dependent shifts of the spectral features allow differentiating between acidic cancerous and neutral healthy exocellular environments allowing to use GQDs for cancer detection. Therefore, our results indicate that GQDs have a significant potential in bio-applications because of their capacity for multi-color green/near-IR imaging for in-vitro/in-vivo studies, pH sensitivity, water solubility, low cytotoxicity and high capacity for cellular internalization.

(Poster is private)

PHYS2018KHAN44160 PHYS

Comparing Infection Parameters for Respiratory Syncytial Virus in Different Aged Cotton Rats

Type: Undergraduate
Author(s): Shaheer Khan Physics & Astronomy
Advisor(s): Hana Dobrovolny Physics & Astronomy
Location: Session: 2; 1st Floor; Table Number: 7

poster location

Respiratory syncytial virus (RSV) is an extremely common viral respiratory infection that currently has no vaccine or treatment. One of the issues in developing a treatment has been that immune system responses in both humans and rats vary in their susceptibility to RSV across different age groups. In this study, we use a mathematical model to quantify the viral kinetics of RSV and analyze its relationship to age. After fitting the model to experimental data, six parameter values were determined and used to calculate the eclipse phase length, infection phase length, basic reproductive number, and infecting time. These values were compared by age and collection site. After running several statistical tests, there was no major trend with the parameter values in relation to either age or collection site. This result provides the foundations for further studies to explore how viral models can better represent RSV and understand the immune response in general.

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PHYS2018MELENDEZ55573 PHYS

Using The Cannon to study the chemistry of the Sagittarius dwarf galaxy

Type: Graduate
Author(s): Matthew Melendez Physics & Astronomy John Donor Physics & Astronomy
Advisor(s): Peter Frinchaboy Physics & Astronomy
Location: Session: 1; 3rd Floor; Table Number: 5

poster location

The Sagittarius (Sgr) dwarf galaxy, a dwarf spheroidal galaxy that is a satellite to the Milky Way, has been identified as being in the process of being tidally torn apart by the Milky Way. To study the kinematical and chemical distribution and history of Sgr we have taken spectra for thousands of stars in the large area of the dwarf galaxy. Previous studies have constrained the membership of stars in Sgr based on radial velocity. We will now explore the chemical history of the galaxy by analyzing the stellar component of Sgr using The Cannon, a data-driven method for determining stellar parameters such as temperature, surface gravity, and chemical abundances from stellar spectra. A subset (~150) of our stars have also been observed as part of SDSS/APOGEE survey, at higher resolution and signal-to-noise, which will allow us to use these spectra to train The Cannon in this region in order to obtain accurate abundances for the remaining data set (~1500) of Sgr member stars. This study will allow us to identify chemical sub-groups of Sgr which will allow us to confidently study the history and evolution of the Sgr dwarf galaxy.

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PHYS2018MURPHY6938 PHYS

Characterizing the Efficiency of Anticancer Drug Treatement Using Mathematical Models

Type: Graduate
Author(s): Hope Murphy Physics & Astronomy Giridhar Akkaraju Biology Hana Dobrovolny Physics & Astronomy Anton Naumov Physics & Astronomy Elizabeth Sizemore Physics & Astronomy
Advisor(s): Hana Dobrovolny Physics & Astronomy
Location: Session: 1; 3rd Floor; Table Number: 6

poster location

In order to determine correct dosage of chemotherapy drugs, the effect of the drug must be properly quantified. There are two important values that characterize the effect of the drug: Emax is the maximum possible effect from a drug, and IC50 is the drug concentration where the effect diminishes by half. Currently, the technique used to measure these quantities gives estimates of the values that depend on the time at which the measurement is made. We use mathematical modeling to test a new method for measuring Emax and IC50 that gives estimates independent of measurement time. We fit treatment data from the literature to determine values for Emax and IC50 using mathematical models under two assumptions: that the drug reduces growth rate, or maximum number of cells. Our method produced IC50 estimates similar to estimates derived using current techniques. This work is intended to characterize the efficacy of anticancer drug treatments and determine the correct doses before trying those in patients to get the most effective therapeutic treatment.

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PHYS2018NUREKEYEV48671 PHYS

Multi-pulse based approach on superresolution microscopy

Type: Graduate
Author(s): Zhangatay Nurekeyev Physics & Astronomy Julian Borejdo Biology Luca Ceresa Physics & Astronomy Jose Chavez Physics & Astronomy Sergey Dzyuba Chemistry & Biochemistry Rafal Fudala Biology Ignacy Gryczynski Physics & Astronomy Sangram Raut Biology
Advisor(s): Zygmunt Gryczynski Physics & Astronomy
Location: Session: 2; 2nd Floor; Table Number: 4

poster location

Since the invention of on optical microscope various biological structures have been observed. Today we have a need to study subcellular structures and their dynamics. Here we encounter diffraction limit – two objects located closer than the half of the wavelength cannot be resolved as two distinct objects. Superresolution techniques have been developed to overcome this limit. They can be divided into two types: stochastic and deterministic. Stochastic ones (STORM, PALM) utilize natural ability of fluorescent molecules to blink. These methods require sparse labeling and significant amount of some time to acquire image. Deterministic ones (STED) utilize an additional pulsed light source to de-excite populated state. These methods require advanced technology. Our method is similar to deterministic superresolution techniques. We utilize long-living fluorescent dyes whose excited state population can be significantly enhanced by bursts of pulses. Enhancement occurs only when time delay between pulses within burst is shorter than the lifetime of the dye. By varying bursts and single pulses one may observe varying intensity of a dye, hence, achieve superresolution. Regular labeling methods become an advantage in this case, and such an experimental setup is not very different from conventional microscopy methods.

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PHYS2018PINKY10563 PHYS

Modeling of Viral Coinfection in Human Respiratory Tract Using Stochastic Method

Type: Graduate
Author(s): Lubna Pinky Physics & Astronomy Hana Dobrovolny Physics & Astronomy Gilberto Gonzalez-Parra Physics & Astronomy
Advisor(s): Hana Dobrovolny Physics & Astronomy
Location: Session: 1; 3rd Floor; Table Number: 1

poster location

Respiratory coinfections are commonly found in patients hospitalized with influenza-like illness, but it is not clear whether these infections are more severe than single infections. Mathematical models can be used to help understand the dynamics of respiratory viral coinfections and their impact on the severity of the illness. Most models of viral infections use ordinary differential equations (ODEs) which reproduce the average behavior of the infection, however, they might not be accurate in predicting certain events because of the stochastic nature of the viral replication cycle. Stochastic simulations of single virus infections have shown that there is an extinction probability that depends on the size of the initial viral inoculum and parameters that describe virus-cell interactions. Thus the coexistence of viruses predicted by the ODEs might be difficult to observe in reality. In this work we develop a stochastic numerical implementation of the deterministic coinfection model using the Gillespie algorithm. Stochastic extinction probabilities for each viruses are calculated analytically and will be verified by stochastic simulations. Preliminary analyses of the model have showed that even if the two viruses are given the same initial growth rates, one virus can have higher probability of extinction than the other, namely competitive exclusion, opposing the coexistence cases predicted by the deterministic model.

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PHYS2018RAY7452 PHYS

A Survey of Nearby M-Dwarfs with Robo-AO

Type: Graduate
Author(s): Amy Ray Physics & Astronomy
Advisor(s): Peter Frinchaboy Physics & Astronomy
Location: Session: 1; 3rd Floor; Table Number: 2

poster location

Low mass stars have been difficult to observe until recently, therefore less is known about distributions in their populations, such as how many are in bound systems. This information is crucial for star formation models because observations are used to make sense of model outputs. In this study, the number of bound systems for a sample of 178 M-dwarfs close to our solar system were determined to reduce this deficit for low mass stars. Images were collected, using the Robotic Adaptive Optics camera on the Palomar 60” telescope, over two years. A total of 50 bound systems were found. Compared to surveys of different stellar types, out results fit the trend of the number of bound systems decreasing with decreasing stellar mass. These results will improve the accuracy of star formations models which will enhance our understanding of stellar evolution.

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PHYS2018REEKS5125 PHYS

Nanoscale ZnO with Controllable Crystal Morphology as a Platform to Investigate Mechanisms of Antibacterial Action

Type: Graduate
Author(s): John Reeks Physics & Astronomy Bao Thach Engineering
Advisor(s): Yuri Strzhemechny Physics & Astronomy
Location: Session: 2; Basement; Table Number: 12

poster location

Nanoscale 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.

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PHYS2018RICHSTEIN7035 PHYS

The effects of dwarf-galaxy tug-of-wars

Type: Undergraduate
Author(s): Hannah Richstein Physics & Astronomy Jing Sun Physics & Astronomy
Advisor(s): Kat Barger Physics & Astronomy
Location: Session: 1; Basement; Table Number: 11

poster location

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.

(Poster is private)

PHYS2018RODRIGUEZ18820 PHYS

Impact of trypsin in dynamics infection.

Type: Graduate
Author(s): Thalia Rodriguez Physics & Astronomy
Advisor(s): Hana Dobrovolny Physics & Astronomy
Location: Session: 1; 3rd Floor; Table Number: 4

poster location

In 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.

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PHYS2018RYAN16053 PHYS

Modifying the Optical Properties of Graphene Oxide via an Electric Field

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
Location: Session: 2; Basement; Table Number: 3

poster location

Graphene 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.

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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
Location: Session: 2; 3rd Floor; Table Number: 4

poster location

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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PHYS2018SIZEMORE56739 PHYS

Graphene Derivatives As Effective Formulations for Drug Delivery, Imaging, and Sensing

Type: Graduate
Author(s): Elizabeth Sizemore Physics & Astronomy Roberto Gonzalez Rodriguez Physics & Astronomy Md. Tanvir Hasan Physics & Astronomy
Advisor(s): Anton Naumov Physics & Astronomy
Location: Session: 1; 1st Floor; Table Number: 2

poster location

A field of molecular therapeutics has significantly advanced the treatment of many complex conditions, including cancer therapeutics. However many molecular formulations still lack the diagnostic power of tomography-guided approaches, and are restricted by dose-limiting toxicity. Nanomaterials provide multifunctional capabilities, safely delivering therapeutics while concomitantly imaging their delivery pathways. Graphene Oxide (GO) is an attractive candidate for bioimaging due to its intrinsic fluorescence in the red/near-infrared spectral region with reduced biological autofluorescence background. This provides the capability of fluorescence imaging without the need for additional fluorophores. Additionally GO has a large platform for functionalization with drug molecules, is water soluble and exhibits pH-mediated response in its fluorescence emission. Nanoscale graphene oxide derivatives (NGO) produced via biocompatible bottom-up synthetic route have properties similar to GO, however, possessing a smaller size for more efficient cellular internalization. We explore these properties to develop a family of graphene-based imaging/sensing/delivery platforms for molecular therapeutics. GO or NGO utilized in our work show little to no cytotoxicity quantified via MTT assay up to the maximum imaging concentrations of 15 ug/mL. We use spectrally-resolved fluorescence imaging for in-vitro detection in the spectral ranges specific to GO or NGO emission. Both GO and NGO exhibit efficient cellular internalization assessed via their emission within HeLa cells, with significantly higher accumulation observed for NGO, suggesting a high potential for drug delivery applications and image-guided therapy. A pH dependence of both GO and NGO emission provides a sensing mechanism for the acidic environments of cancer cells; as many cancer cell types excrete lactic acid, their environments are more acidic than those of healthy cells. The difference between fluorescence in healthy (HEK-293)/cancer (HeLa, MCF-7) cell environments is quantified for graphene derivatives in this work via assessing the shifts in emission and/or variations in emission intensities at different wavelengths. As a result we propose a family of graphene derivatives, including GO and NGO functionalities, as efficient multifunctional candidates for in-vitro delivery of active agents, fluorescence imaging and pH-sensing of cancerous environments.

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
Location: Session: 2; 1st Floor; Table Number: 3

poster location

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
Location: Session: 1; Basement; Table Number: 1

poster location

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
Location: Session: 1; Basement; Table Number: 6

poster location

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.

(Poster is private)

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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