Matching Items (8)
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- All Subjects: Astrophysics
- All Subjects: Marriage
- Creators: Department of Physics
Description
Supernovae are vital to supplying necessary elements to forming bodies in our solar systems. This project studies the creation of a subset of these necessary elements, called short-lived radionuclides (SLRs). SLRs are isotopes with relatively short half-lives and can serve as heat sources for forming planetary bodies, and their traces can be used to date stellar events. Computational models of asymmetric supernovae provide opportunities to study the effect of explosion geometry on the SLR yields. We are most interested in the production of \iso{Al}{26}, \iso{Fe}{60}, and \iso{Ca}{41}, whose decayed products are found in our own solar system. To study the effect of explosion asymmetries in supernovae, we use TYCHO stellar evolution code, SNSHP smooth particle hydrodynamics code for 3D explosion simulations, Burn code for nucleosythesis post-processing, and Python code written to analyze the output of the post-processing code.
ContributorsJohnson, Charlotte (Author) / Young, Patrick (Thesis director) / Lunardini, Cecilia (Committee member) / Department of Physics (Contributor) / Barrett, The Honors College (Contributor)
Created2018-05
Description
Observations of four times ionized iron and nickel (Fe V & Ni V) in the G191-B2B white dwarf spectrum have been used to test for variations in the fine structure constant, α, in the presence of strong gravitational fields. The laboratory wavelengths for these ions were thought to be the cause of inconsistent conclusions regarding the
variation of α as observed through the white dwarf spectrum. This thesis presents 129 revised Fe V wavelengths (1200 Å to 1600 Å) and 161 revised Ni V wavelengths (1200 Å to 1400 Å) with uncertainties of approximately 3 mÅ. A systematic calibration error
is identified in the previous Ni V wavelengths and is corrected in this work. The evaluation of the fine structure variation is significantly improved with the results
found in this thesis.
variation of α as observed through the white dwarf spectrum. This thesis presents 129 revised Fe V wavelengths (1200 Å to 1600 Å) and 161 revised Ni V wavelengths (1200 Å to 1400 Å) with uncertainties of approximately 3 mÅ. A systematic calibration error
is identified in the previous Ni V wavelengths and is corrected in this work. The evaluation of the fine structure variation is significantly improved with the results
found in this thesis.
ContributorsWard, Jacob Wolfgang (Author) / Treacy, Michael (Thesis director) / Alarcon, Ricardo (Committee member) / Nave, Gillian (Committee member) / Department of Physics (Contributor) / Computer Science and Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-05
Description
The LOw Frequency ARray (LOFAR) is a new and innovative radio telescope designed and constructed by the Netherlands Institute for Radio Astronomy (ASTRON). LOFAR unique capable of operating in very low frequencies (10-240 MHz) and consists of an extensive interferometry array of dipole antenna stations distributed throughout the Netherlands and Europe which allows it to achieve superb angular resolution. I investigate a part of the northern sky to search for rare radio objects such as radio haloes and radio relics that may have not been able to have been resolved by other radio telescopes.
ContributorsNguyen, Dustin Dinh (Author) / Scannapieco, Evan (Thesis director) / Butler, Nathaniel (Committee member) / School of Earth and Space Exploration (Contributor) / Department of Physics (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
Radio astronomy is a subfield in astronomy that deals with objects emitting frequencies around 10 MHz to 100 GHz. The Low Frequency Array (LOFAR) is a array of radio antennas in Europe that can reach very low frequencies, roughly between 10-240 MHz. Our project was to image and clean a field from LOFAR. The data was a 10 degree square in the sky centered at a right ascension of 10:19:34.608 and a declination +49.36.52.482. It was observed for 600 seconds at 141 MHz. To clean the field, we had to flag and remove any stations that were not responding. Using a program called FACTOR, we cleaned the image and reduced the residuals. Next we checked the validity of our sources. We checked positional offsets for our sources using the TGSS survey at 150 MHz, and corrected the declination of our LOFAR sources by a factor of 0.0002 degrees. We also fixed the LOFAR fluxes by a factor of 1.15. After this systematic check, we calculated the spectral index of our sources using the FIRST survey at 1435 MHz. We plotted this spectral index against LOFAR flux as well as redshift of the sources, and compared these to literature.
ContributorsStawinski, Stephanie Mae (Author) / Scannapieco, Evan (Thesis director) / Windhorst, Rogier (Committee member) / Karen, Olsen (Committee member) / Department of Physics (Contributor) / School of International Letters and Cultures (Contributor) / School of Earth and Space Exploration (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
The Epoch of Reionization (EoR) is the period in the evolution of the universe during which neutral hydrogen was ionized by the first luminous sources, and is closely linked to the formation of structure in the early universe. The Hydrogen Epoch of Reionization Array (HERA) is a radio interferometer currently under construction in South Africa designed to study this era. Specifically, HERA is dedicated to studying the large-scale structure during the EoR and the preceding Cosmic Dawn by measuring the redshifted 21-cm line from neutral hydrogen. However, the 21-cm signal from the EoR is extremely faint relative to galactic and extragalactic radio foregrounds, and instrumental and environmental systematics make measuring the signal all the more difficult. Radio frequency interference (RFI) from terrestrial sources is one such systematic. In this thesis, we explore various methods of removing RFI from early science-grade HERA data and characterize the effects of different removal patterns on the final 21-cm power spectrum. In particular, we focus on the impact of masking narrowband signals, such as those characteristic of FM radio and aircraft or satellite communications, in the context of the algorithms currently used by the HERA collaboration for analysis.
ContributorsWhitler, Lily (Author) / Jacobs, Daniel (Thesis director) / Bowman, Judd (Committee member) / Beardsley, Adam (Committee member) / School of Mathematical and Statistical Sciences (Contributor) / Department of Physics (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Racial and ethnic differences in marriage outcomes are well established in the previous literature. In addition, variation in the social structure in which individuals reside has an impact on the context in which mate selection and marriage occur. The purpose of this dissertation is to determine how these variations shape marriage outcomes for Non-Hispanic Whites, Non-Hispanic Blacks, Hispanics and Non-Hispanic Asians. Beyond racial and ethnic characteristics, this series of studies take into account temporal metropolitan characteristics. Study 1 uses U.S. Census and American Community Survey data to predict metropolitan marriage prevalence at three time points: 1990, 2000 and 2010. Study 2 predicts the odds that individuals across the four racial/ethnic groups have never married, taking into account structural characteristics including region of residence. Study 3 predicts the odds that currently married women are racially or ethnically intermarried, with emphasis on race/ethnicity and region of residence. The results suggest that metropolitan structural characteristics matter somewhat, but individuals' race/ethnicity is the strongest predictor of both the odds of having never married and intermarriage. There is also evidence that region serves as a moderator impacting the overall marriage outcomes of racial/ethnic minority groups to a greater extent in comparison to Non-Hispanic Whites.
ContributorsWalker, Laquitta M (Author) / Glick, Jennifer E. (Thesis advisor) / Yabiku, Scott (Committee member) / Diaz McConnell, Eileen (Committee member) / Arizona State University (Publisher)
Created2016
Description
In this paper, I first explain the legal theory which leads up to Obergefell v. Hodges, and then analyze Obergefell v. Hodges itself. My analysis leads me to conclude that the legal reasoning, or the argument used to come to the decision, is flawed for it relies too heavily upon public opinion and is a legislative action of the Supreme Court. Therefore, I offer three alternatives: each of which improve upon the legal reasoning in different ways. Furthermore, my analysis of these three arguments\u2014and particularly the Free Exercise Argument\u2014leads me to postulate that there is in fact a Freedom to Practice embedded in the penumbral, or unstated, rights of the United States Constitution. While the full extent of the implications of such a right must be explored in another paper, I establish the legal reasoning for the freedom by four routes, showing that although precedent has yet to materialize, there are several arguments for the freedom.
ContributorsMartin, Daniel Brockie (Author) / Kramer, Zachary (Thesis director) / Graff, Sarah (Committee member) / Department of Physics (Contributor) / Barrett, The Honors College (Contributor)
Created2015-12
Description
This dissertation explores changes in fertility and family formation in South Korea, a setting in which rapid demographic changes have taken place since the early twentieth century. Despite active debate and discussion among experts and policymakers, knowledge is still limited in regards to the country’s significant demographic changes. I take advantage of Korean census samples data from 1966 to 2010, which span birth cohorts from pre- and early-transitional stages to post-transitional stages, which comprise the entry stage of the second demographic transition. From a cohort perspective, I use diverse demographic methods to analyze three different aspects of fertility and family formation—fertility differentials, marriage delay, and fertility concentration.
The findings illustrate how fertility and marriage patterns have changed over generations and range from a politically tumultuous period, which includes World War II, liberation, and the Korean War, to an advanced economic period. By and large, the three studies suggest that until 1960, fertility and family formation converged as per social norms and leadership guidelines. Then, marriage and childbearing behaviors began to diversify and variation by social groups increased for cohorts born during and after the 1960s. The phrase “convergence towards diversity” captures the reversal of demographic trends within the country. Taken together, this dissertation advances our understanding of how fertility and family formation have changed in South Korea, which has been on an intense demographic journey from pre-transitional fertility through very low fertility, and currently headed toward another destination.
The findings illustrate how fertility and marriage patterns have changed over generations and range from a politically tumultuous period, which includes World War II, liberation, and the Korean War, to an advanced economic period. By and large, the three studies suggest that until 1960, fertility and family formation converged as per social norms and leadership guidelines. Then, marriage and childbearing behaviors began to diversify and variation by social groups increased for cohorts born during and after the 1960s. The phrase “convergence towards diversity” captures the reversal of demographic trends within the country. Taken together, this dissertation advances our understanding of how fertility and family formation have changed in South Korea, which has been on an intense demographic journey from pre-transitional fertility through very low fertility, and currently headed toward another destination.
ContributorsYoo, Sam Hyun (Author) / Sarah, Hayford (Thesis advisor) / Agadjanian, Victor (Committee member) / Yabiku, Scott (Committee member) / Arizona State University (Publisher)
Created2015