The Zoramite narratives of Alma 31-35 and Alma 43-44 are richly symbolic accounts woven with many... more The Zoramite narratives of Alma 31-35 and Alma 43-44 are richly symbolic accounts woven with many subtle details regarding the importance of costly apparel and riches as an outward evidence of pride. This literary analysis focuses on how Mormon as editor structured the Zoramite narrative and used clothing as a metaphor to show the dangers of pride and the blessings afforded by humble adherence to God's teachings and covenants. The Zoramites' pride-as evidenced by their focus on costly apparel, gold, silver, and fine goods (Alma 31:24-25, 28)-competes with the foundational Book of Mormon teaching that the obedient will "prosper in the land" (1 Nephi 4:14; Mosiah 1:7). The story develops this tension between pride and true prosperity by employing the metaphor of clothing to set up several dramatic ironies.
Magnetized collimated plasma jets are created in the laboratory to extend our understanding of pl... more Magnetized collimated plasma jets are created in the laboratory to extend our understanding of plasma jet acceleration and collimation mechanisms with particular connection to astrophysical jets. In this study, plasma collimated jets are formed from supersonic unmagnetized flows, mimicking a stellar wind, subject to currents and magnetohydrodynamic forces. It is found that an external poloidal magnetic field, like the ones found anchored to accretion disks, is essential to stabilize the jets against current-driven instabilities. The maximum jet length before instabilities develop is proportional to the field strength and the length threshold agrees well with Kruskal-Shafranov theory. The plasma evolution is modeled qualitatively using MHD theory of current-carrying flux tubes showing that jet acceleration and collimation arise as a result of electromagnetic forces.
Polarization states of the underwater light field were measured by a hyperspectral and multiangul... more Polarization states of the underwater light field were measured by a hyperspectral and multiangular polarimeter and a video polarimeter under various atmospheric, surface, and water conditions, as well as solar and viewing geometries, in clear oceanic waters near Port Aransas, Texas. Some of the first comprehensive comparisons were made between the measured polarized light, including the degree and angle of linear polarization and linear Stokes parameters (Q and U), and those from Monte Carlo simulations that used concurrently measured water inherent optical properties and particle volume scattering functions as input. For selected wavelengths in the visible spectrum, measured and modelsimulated polarization characteristics were found to be consistent in most cases. Measured degree and angle of linear polarization are found to be largely determined by an in-water single-scattering model. Model simulations suggest that the degree of linear polarization (DoLP) at horizontal viewing directions is highly dependent on the viewing azimuth angle for a low solar elevation. This implies that animals can use the DoLP signal for orientation.
for his time, discussion, direction and most of all his ICCD camera. I am grateful for Dr. Prasha... more for his time, discussion, direction and most of all his ICCD camera. I am grateful for Dr. Prashant Valanhu, for his ideas for the experiment and his theoretical help. I also thank Professor Wendell Horton for his encouragement for the work on magnetospheres. Second I would like to thank all of my coworkers who gave me a lot of help over the years. Greg Hays gave me priceless instruction in construct the YOGA laser, as well as his share of "elbow grease" in its construction. I would like to thank Allen Dalton for his help in assisting me with my experiment and for taking over the YOGA laser. The YOGA glass heads have served many generations of graduate students and may they continue to serve for generations to come. Matt McCormick gave valuable assistance during the critical part of this experiment. I am grateful for Hernan Quevedo for his priceless physics and experimental knowledge to help me push forward and finish my work. He gave me a lot of time and encouragement, without which many of the goals met in this thesis would not be achieve. Will Grigsby and Gillis Dyre were always willing to help me out with whatever in the lab, gave me useful Igor programs, and took the time to teach me their Igor secrets. Sean Keely gave me a lot of help with the electrical and software part of this project. Kort Travis helped me out with a lot of practical things in the lab v Abstract vii Chapter 1. Introduction xi Chapter 7. Conclusion and Future Directions 278 7.
Plastic pollution in the ocean is an increasingly detrimental issue for marine organisms. As a fo... more Plastic pollution in the ocean is an increasingly detrimental issue for marine organisms. As a form of polarized light pollution, transparent plastic debris may be more visible and pose additional threats to organisms that can detect and interpret polarized light. Plastic can mimic the visual features of common marine prey items, such as transparent gelatinous zooplankton, which may lead to more significant plastic ingestion. We measured, in situ, the polarization and radiance contrast between a transparent plastic bag and gelatinous zooplankton with an underwater video polarimeter. The plastic bag had significantly higher polarization contrast than the gelatinous zooplankton, yet both shared similar radiance contrasts. This higher polarization contrast may contribute to the observed high ingestion rates of transparent plastic by marine organisms. Further study into the connection between polarization-sensitive organisms and plastic ingestion is recommended.
Journal of the Royal Society Interface, Mar 1, 2015
Predator evasion in the open ocean is difficult because there are no objects to hide behind. The ... more Predator evasion in the open ocean is difficult because there are no objects to hide behind. The silvery surface of fish plays an important role in open water camouflage. Various models have been proposed to account for the broadband reflectance by the fish skin that involve one-dimensional variations in the arrangement of guanine crystal reflectors, yet the three-dimensional organization of these guanine platelets have not been well characterized. Here, we report the three-dimensional organization and the optical properties of integumentary guanine platelets in a silvery marine fish, the lookdown (Selene vomer). Our structural analysis and computational modelling show that stacks of guanine platelets with random yaw angles in the fish skin produce broadband reflectance via colour mixing. Optical axes of the guanine platelets and the collagen layer are aligned closely and provide bulk birefringence properties that influence the polarization reflectance by the skin. These data demonstrate how the lookdown preserves or alters polarization states at different incident polarization angles. These optical properties resulted from the organization of these guanine platelets and the collagen layer may have implications for open ocean camouflage in varying light fields.
I present the system PATMOS (paths and tessellated meshes from ORB_SLAM2) for measuring three-dim... more I present the system PATMOS (paths and tessellated meshes from ORB_SLAM2) for measuring three-dimensional paths of animals in situ using two handheld GoPro cameras and a small spatial reference object. Animal paths were triangulated from mobile camera positions obtained from a modified version of ORB_SLAM2, an open-source visual simultaneous localization and mapping software package. In addition to path calculation, this process provided a virtual three-dimensional surface approximation to the environment from which path to environment distances can be quantified. PATMOS can also fit a tranquil water’s surface to an analytic plane if there are a sufficient number of visible objects intersecting the water’s surface and can track objects over the water’s surfaces with a single camera by measuring the object with its reflection. This technology was highly portable, could follow moving animals, and gave comparable spatial and temporal resolutions to fixed camera systems that use commerc...
Reef squids belong to a group reputed for polarization sensitivity, yet polarization patterns of ... more Reef squids belong to a group reputed for polarization sensitivity, yet polarization patterns of reef squid have not been quantifiedin situ. To quantify polarization patterns from video polarimetric data, we developed a protocol to map two-dimensional polarization data onto squid-shaped three-dimensional tessellated surfaces. This protocol provided a robust data container used to investigate three-dimensional regions-of-interest, producing data lineouts derived from the squid's geometry. This protocol also extracted polarimeter and squid body orientations and the solar heading from polarization images. When averaged over the solar heading, the ventral midline gave a low degree of polarization (2.4 ± 5.3%), and the area between the ventral and flank midlines had higher values (9.0 ± 5.3%). These averaged data had a large discontinuity in the angle of polarization (AoP) at the mantle's ventral midline (64 ± 55°), with larger discontinuities measured on individual squid. Ray-tr...
I present the system PATMOS (Paths And Tessellated Meshes from ORB_SLAM2) for measuring three-dim... more I present the system PATMOS (Paths And Tessellated Meshes from ORB_SLAM2) for measuring three-dimensional paths of animals in situ using two handheld GoPro cameras and a small spatial reference object. Animal paths were triangulated from mobile camera positions obtained from a modified version of ORB_SLAM2, an open-source visual simultaneous localization and mapping software package. In addition to path calculation, this process provided a virtual three-dimensional surface approximation to the environment from which path to environment distances can be quantified. PATMOS can also fit a tranquil water's surface to an analytic plane if there are a sufficient number of visible objects intersecting the water's surface and can track objects over the water's surfaces with a single camera by measuring the object with its reflection. This technology was highly portable, could follow moving animals, and gave comparable spatial and temporal resolutions to fixed camera systems that...
Excel files containing the data for the paper titled: "Diffuse blue vs. structural silver—co... more Excel files containing the data for the paper titled: "Diffuse blue vs. structural silver—comparing alternative strategies for pelagic background matching between two coral reef fishes." See Data for creole wrasse vs bar jack.docx for more details
The Zoramite narratives of Alma 31-35 and Alma 43-44 are richly symbolic accounts woven with many... more The Zoramite narratives of Alma 31-35 and Alma 43-44 are richly symbolic accounts woven with many subtle details regarding the importance of costly apparel and riches as an outward evidence of pride. This literary analysis focuses on how Mormon as editor structured the Zoramite narrative and used clothing as a metaphor to show the dangers of pride and the blessings afforded by humble adherence to God's teachings and covenants. The Zoramites' pride-as evidenced by their focus on costly apparel, gold, silver, and fine goods (Alma 31:24-25, 28)-competes with the foundational Book of Mormon teaching that the obedient will "prosper in the land" (1 Nephi 4:14; Mosiah 1:7). The story develops this tension between pride and true prosperity by employing the metaphor of clothing to set up several dramatic ironies.
Magnetized collimated plasma jets are created in the laboratory to extend our understanding of pl... more Magnetized collimated plasma jets are created in the laboratory to extend our understanding of plasma jet acceleration and collimation mechanisms with particular connection to astrophysical jets. In this study, plasma collimated jets are formed from supersonic unmagnetized flows, mimicking a stellar wind, subject to currents and magnetohydrodynamic forces. It is found that an external poloidal magnetic field, like the ones found anchored to accretion disks, is essential to stabilize the jets against current-driven instabilities. The maximum jet length before instabilities develop is proportional to the field strength and the length threshold agrees well with Kruskal-Shafranov theory. The plasma evolution is modeled qualitatively using MHD theory of current-carrying flux tubes showing that jet acceleration and collimation arise as a result of electromagnetic forces.
Polarization states of the underwater light field were measured by a hyperspectral and multiangul... more Polarization states of the underwater light field were measured by a hyperspectral and multiangular polarimeter and a video polarimeter under various atmospheric, surface, and water conditions, as well as solar and viewing geometries, in clear oceanic waters near Port Aransas, Texas. Some of the first comprehensive comparisons were made between the measured polarized light, including the degree and angle of linear polarization and linear Stokes parameters (Q and U), and those from Monte Carlo simulations that used concurrently measured water inherent optical properties and particle volume scattering functions as input. For selected wavelengths in the visible spectrum, measured and modelsimulated polarization characteristics were found to be consistent in most cases. Measured degree and angle of linear polarization are found to be largely determined by an in-water single-scattering model. Model simulations suggest that the degree of linear polarization (DoLP) at horizontal viewing directions is highly dependent on the viewing azimuth angle for a low solar elevation. This implies that animals can use the DoLP signal for orientation.
for his time, discussion, direction and most of all his ICCD camera. I am grateful for Dr. Prasha... more for his time, discussion, direction and most of all his ICCD camera. I am grateful for Dr. Prashant Valanhu, for his ideas for the experiment and his theoretical help. I also thank Professor Wendell Horton for his encouragement for the work on magnetospheres. Second I would like to thank all of my coworkers who gave me a lot of help over the years. Greg Hays gave me priceless instruction in construct the YOGA laser, as well as his share of "elbow grease" in its construction. I would like to thank Allen Dalton for his help in assisting me with my experiment and for taking over the YOGA laser. The YOGA glass heads have served many generations of graduate students and may they continue to serve for generations to come. Matt McCormick gave valuable assistance during the critical part of this experiment. I am grateful for Hernan Quevedo for his priceless physics and experimental knowledge to help me push forward and finish my work. He gave me a lot of time and encouragement, without which many of the goals met in this thesis would not be achieve. Will Grigsby and Gillis Dyre were always willing to help me out with whatever in the lab, gave me useful Igor programs, and took the time to teach me their Igor secrets. Sean Keely gave me a lot of help with the electrical and software part of this project. Kort Travis helped me out with a lot of practical things in the lab v Abstract vii Chapter 1. Introduction xi Chapter 7. Conclusion and Future Directions 278 7.
Plastic pollution in the ocean is an increasingly detrimental issue for marine organisms. As a fo... more Plastic pollution in the ocean is an increasingly detrimental issue for marine organisms. As a form of polarized light pollution, transparent plastic debris may be more visible and pose additional threats to organisms that can detect and interpret polarized light. Plastic can mimic the visual features of common marine prey items, such as transparent gelatinous zooplankton, which may lead to more significant plastic ingestion. We measured, in situ, the polarization and radiance contrast between a transparent plastic bag and gelatinous zooplankton with an underwater video polarimeter. The plastic bag had significantly higher polarization contrast than the gelatinous zooplankton, yet both shared similar radiance contrasts. This higher polarization contrast may contribute to the observed high ingestion rates of transparent plastic by marine organisms. Further study into the connection between polarization-sensitive organisms and plastic ingestion is recommended.
Journal of the Royal Society Interface, Mar 1, 2015
Predator evasion in the open ocean is difficult because there are no objects to hide behind. The ... more Predator evasion in the open ocean is difficult because there are no objects to hide behind. The silvery surface of fish plays an important role in open water camouflage. Various models have been proposed to account for the broadband reflectance by the fish skin that involve one-dimensional variations in the arrangement of guanine crystal reflectors, yet the three-dimensional organization of these guanine platelets have not been well characterized. Here, we report the three-dimensional organization and the optical properties of integumentary guanine platelets in a silvery marine fish, the lookdown (Selene vomer). Our structural analysis and computational modelling show that stacks of guanine platelets with random yaw angles in the fish skin produce broadband reflectance via colour mixing. Optical axes of the guanine platelets and the collagen layer are aligned closely and provide bulk birefringence properties that influence the polarization reflectance by the skin. These data demonstrate how the lookdown preserves or alters polarization states at different incident polarization angles. These optical properties resulted from the organization of these guanine platelets and the collagen layer may have implications for open ocean camouflage in varying light fields.
I present the system PATMOS (paths and tessellated meshes from ORB_SLAM2) for measuring three-dim... more I present the system PATMOS (paths and tessellated meshes from ORB_SLAM2) for measuring three-dimensional paths of animals in situ using two handheld GoPro cameras and a small spatial reference object. Animal paths were triangulated from mobile camera positions obtained from a modified version of ORB_SLAM2, an open-source visual simultaneous localization and mapping software package. In addition to path calculation, this process provided a virtual three-dimensional surface approximation to the environment from which path to environment distances can be quantified. PATMOS can also fit a tranquil water’s surface to an analytic plane if there are a sufficient number of visible objects intersecting the water’s surface and can track objects over the water’s surfaces with a single camera by measuring the object with its reflection. This technology was highly portable, could follow moving animals, and gave comparable spatial and temporal resolutions to fixed camera systems that use commerc...
Reef squids belong to a group reputed for polarization sensitivity, yet polarization patterns of ... more Reef squids belong to a group reputed for polarization sensitivity, yet polarization patterns of reef squid have not been quantifiedin situ. To quantify polarization patterns from video polarimetric data, we developed a protocol to map two-dimensional polarization data onto squid-shaped three-dimensional tessellated surfaces. This protocol provided a robust data container used to investigate three-dimensional regions-of-interest, producing data lineouts derived from the squid's geometry. This protocol also extracted polarimeter and squid body orientations and the solar heading from polarization images. When averaged over the solar heading, the ventral midline gave a low degree of polarization (2.4 ± 5.3%), and the area between the ventral and flank midlines had higher values (9.0 ± 5.3%). These averaged data had a large discontinuity in the angle of polarization (AoP) at the mantle's ventral midline (64 ± 55°), with larger discontinuities measured on individual squid. Ray-tr...
I present the system PATMOS (Paths And Tessellated Meshes from ORB_SLAM2) for measuring three-dim... more I present the system PATMOS (Paths And Tessellated Meshes from ORB_SLAM2) for measuring three-dimensional paths of animals in situ using two handheld GoPro cameras and a small spatial reference object. Animal paths were triangulated from mobile camera positions obtained from a modified version of ORB_SLAM2, an open-source visual simultaneous localization and mapping software package. In addition to path calculation, this process provided a virtual three-dimensional surface approximation to the environment from which path to environment distances can be quantified. PATMOS can also fit a tranquil water's surface to an analytic plane if there are a sufficient number of visible objects intersecting the water's surface and can track objects over the water's surfaces with a single camera by measuring the object with its reflection. This technology was highly portable, could follow moving animals, and gave comparable spatial and temporal resolutions to fixed camera systems that...
Excel files containing the data for the paper titled: "Diffuse blue vs. structural silver—co... more Excel files containing the data for the paper titled: "Diffuse blue vs. structural silver—comparing alternative strategies for pelagic background matching between two coral reef fishes." See Data for creole wrasse vs bar jack.docx for more details
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