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A Multi-Wavelength Determination Of The Total Luminosity And Star Formation Rate Of The Milky Way, Joshua L. Mascoop

Graduate Theses, Dissertations, and Problem Reports

The star formation rate (SFR) of the Milky Way is poorly understood in comparison to the SFR of other galaxies. In order to better find the Galaxy's place in the universe, it is imperative to understand the star formation activity occurring within it. We characterize the Galactic \hii\ region luminosity function (LF) at multiple infrared and radio wavelengths using a sample of 797 first Galactic quadrant \hii regions compiled from the WISE Catalog of Galactic \hii Regions. This sample is statistically complete for all regions powered by single stars of type O9.5V and earlier.

We find that neither a single …

An Exploration Of Misconceptions In Introductory Physics, Christopher Mattthew Wheatley

Graduate Theses, Dissertations, and Problem Reports

The study of student misconceptions about physics concepts has long been an important area of inquiry in physics education research (PER). The research discussed in this dissertation builds upon the developments in PER by exploring the prevalence of consistently held undergraduate student misconceptions in introductory calculus-based physics. This thesis explores the nature of student misconceptions, mistakes, and naive answering patterns in both introductory undergraduate Newtonian mechanics and electromagnetism by applying a network analytic technique called module analysis to student responses to different concept inventories from institutions of various levels of incoming physics preparation. Each study applying these methods also demonstrates …

Examining The Relations Among Academic And Non-Cognitive Factors And Student Achievement, Dona Sachini Hasanjalie Hewagallage

Graduate Theses, Dissertations, and Problem Reports

Since the 1980s, Physics Education Research (PER) has explored the factors influencing students' success in college. This manuscript reports three different studies to understand the impact of different factors on students' college physics achievement. The first study explored several academic (high school physics preparation, high school preparation, math readiness, and ACT or SAT verbal and mathematics scores) and non-cognitive (self-efficacy, personality, belonging, grade expectation, and demographic) factors using correlation and linear regression analysis to understand their relation to students' physics conceptual understanding measured by the Force and Motion Conceptual Evaluation (FMCE). High school preparation was found to be the most …

Methods For Analyzing Physics Student Retention And Physics Curricula, John Darrell Hansen

Graduate Theses, Dissertations, and Problem Reports

Retention of students in college has been a concern of academic institutions for many years. In the last two decades, the focus on student retention in STEM fields has intensified. The current graduation rate of students in science, technology, engineering and mathematics (STEM) fields is well below that required to fill the projected need of STEM professionals. The work presented in this dissertation investigates the problem of student retention in physics programs. Four studies were performed. The first identifies the relationships between student retention and pre-college and early-college academic factors at an eastern U.S. university using logistic regression and Bayesian …

Characterizing & Mitigating Interstellar Scattering In Radio Observations Of Pulsars, Jacob E. Turner

Graduate Theses, Dissertations, and Problem Reports

Pulsars are rapidly rotating neutron stars that emit concentrated beams of radiation from their magnetic poles. Measuring the arrival of these pulses via pulsar timing is a powerful tool in efforts to detect low frequency gravitational waves (GWs). However, the interstellar medium (ISM) presents a significant source of timing uncertainty that must be mitigated to improve the sensitivity of pulsar timing efforts to these GW signals. By examining the effects of pulsar emission interactions with this medium, we can properly correct for the resulting effects in pulsar timing efforts, as well as study the astronomical unit-to-parsec scale structure and behavior …

Exploring The Diffuse Neutral Hydrogen In And Around Nearby Galaxies, Amy Sardone

Graduate Theses, Dissertations, and Problem Reports

We explore the environment of 36 nearby galaxies in neutral hydrogen (H I) as part of the MeerKAT H I Observations of Nearby Galactic Objects; Observing Southern Emitters (MHONGOOSE) survey with the Robert C. Byrd Green Bank Telescope (GBT), and the Imaging Galaxies Intergalactic and Nearby En- vironment (IMAGINE) survey with the Parkes Radio Telescope. We obtained deep observations of each of these galaxies, reaching column density detection sensitivities as low as NHI ∼ 1e17 cm^−2, which allowed us to quantify the amount of diffuse H I in both samples of galaxies. This allows us to search for evidence of …

The Impact Of Hii Regions On The Interstellar Medium Of Our Galaxy, Matteo Luisi

Graduate Theses, Dissertations, and Problem Reports

The interstellar medium (ISM) of our Galaxy contains low-density diffuse ionized gas known as the warm ionized medium (WIM). O- and B-type stars emit large amounts of ionizing radiation and it is believed that a fraction of this radiation escapes from their fully ionized HII regions and into the ISM where it is responsible for maintaining the ionization of the WIM. Here we aim to better understand how the radiation produced by OB stars is able to leak from the HII regions, how the radiation field changes during this process, and how the radiation affects the ambient ISM. Using Green …

Evaluation Of X-Ray Spectroscopic Techniques For Determining Temperature And Density In Plasmas, Theodore Scott Lane

Graduate Theses, Dissertations, and Problem Reports

Temperature and density measurements of plasmas are important for understanding various phenomena. For example, equations of state, most scaling arguments for Inertial Confinement Fusion and laboratory astrophysics all rely upon accurate knowledge of temperature and density. Spectroscopy is a non-invasive technique to measure these quantities. In this work we establish a new spectroscopic technique by using it to determine temperature. We also compare and contrast the capability of two codes, PrismSPECT and ATOMIC, to infer electron density from experimentally acquired spectra via Stark broadening.

We compare and contrast the capability of isoelectronic line ratios and inter-stage line ratios in an …

Using Machine Learning And Traditional Statistics To Explore Retention And Knowledge Structure In Stem With An Emphasis On Physics, Cabot Alexander Zabriskie

Graduate Theses, Dissertations, and Problem Reports

Retention of Science, Technology, Engineering, and Mathematics (STEM) students is a serious problem as STEM graduation rates continue to lag the growing demand for the skills taught by these degree programs. Critical to fixing this “leaky pipeline” is investment in improving retention in the first two years of college study and increasing and maintaining the interest of K-12 students in STEM. This thesis will address this in three parts. The first is through evaluation of conceptual tests used to evaluate course improvements to determine the structure student knowledge measured by them. The second part uses machine learning to construct early …

A Census Of The Galactic Hii Region Population, William Paul Armentrout

Graduate Theses, Dissertations, and Problem Reports

No abstract provided.

Ion Temperatures In Earth's Inner Magnetosphere: Ring Current Dynamics, Transient Effects, And Data-Model Comparisons, Justin G. Elfritz

Graduate Theses, Dissertations, and Problem Reports

Earth's magnetosphere is an inherently complex, strongly nonlinear system with intrinsic coupling between internal and external drivers. In general, magnetospheric systems can be understood as a balance between multiple regions which all exhibit unique plasma properties. The feedback processes between each region depend on geomagnetic activity levels and the preceding states of the solar wind and the respective magnetospheric regions. Of particular interest is understanding how ion temperatures evolve during geomagnetically active periods, and also understanding the space weather impacts of hot ion populations injected during such periods. Dynamic, spatiotemporally resolved ion temperature boundary conditions have been implemented into the …

An Investigation Of Traveling-Wave Electrophoresis Using A Trigonometric Potential, James Vopal

Graduate Theses, Dissertations, and Problem Reports

Traveling-wave electrophoresis, a technique for microfluidic separations in lab-on-achip devices, is investigated using a trigonometric model that naturally incorporates the spatial periodicity of the device. Traveling-wave electrophoresis can be used to separate high-mobility ions from low-mobility ions in forensic and medical applications, with a separation threshold that can be tuned for specific applications by simply choosing the traveling wave frequency. Our simulations predict plateaus in the average ion velocity verses the mobility, plateaus that correspond to Farey fractions and yield Devil's staircases for non-zero discreteness values. The plateaus indicate that ions with different mobilities can travel with the same average …

Pulsar Populations In The Galaxy And Magellanic Clouds, Joshua P. Ridley

Graduate Theses, Dissertations, and Problem Reports

Pulsars are great tools for studying the Universe. From energetics to radio emission, many of the properties of pulsars can be used to understand other physical phenomena occurring throughout the Universe today. This dissertation examines pulsars and their properties through the use of computer simulations, describes the basic pulsar search procedure, and presents the results of a search for millisecond pulsars (MSPs) and fast radio transients in the Small Magellanic Cloud (SMC).;Using Monte Carlo simulations, a working model of normal pulsars that accurately represents the observed population was created. These simulations allow for changes to be made to the initial …

Modeled Sulfur Dioxide Exposure From A Proposed Coal Fired Power Plant, Using Geographic Information Systems And Air Dispersion Modeling, Steven Jason Hutchens

Graduate Theses, Dissertations, and Problem Reports

This study models the contribution of sulfur dioxide (SO 2) from a proposed coal fired power plant (CFPP) above existing ambient levels. Most vulnerable to SO2 exposure appear to be the elderly, young, and diseased, here identified as sensitive receptors (SR). Epidemiologic studies suggest 260mug/m3 as the lowest toxic threshold for SR exposure. It was hypothesized that added SO2 concentrations to existing ambient levels at regional sensitive receptors, under worst case scenario, would not exceed 260mug/m3.;The methods used identify and quantify density locations of localized SR using geographic information systems. Modeled worst case air dispersion concentration exposure to localized SR …

Coupled Nonlinear Dynamical Systems, Hongyan Sun

Graduate Theses, Dissertations, and Problem Reports

In this dissertation, we study coupled nonlinear dynamical systems that exhibit new types of complex behavior. We numerically and analytically examine a variety of dynamical models, ranging from systems of ordinary differential equations (ODE) with novel elements of feedback to systems of partial differential equations (PDE) that model chemical pattern formation. Chaos, dynamical uncertainty, synchronization, and spatiotemporal pattern formation constitute the primary topics of the dissertation. Following the introduction in Chapter 1, we study chaos and dynamical uncertainty in Chapter 2 with coupled Lorenz systems and demonstrate the existence of extreme complexity in high-dimensional ODE systems. In Chapter 3, we …