Browsing by Subject "Light"
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Item A study of diffraction of light by a dielectric straight edge(Texas Tech University, 1964-05) Linder, Robert EarlNot availableItem "Christian conversion" as a radical philosophical turn : Lukan literary efforts in describing Paul's "Conversion" in Acts 9, 22, and 26(2015-05) Kim, Jin Young, M.A.; White, L. Michael; Friesen, Steven JThe present report analyzes the three Lukan accounts on Paul's "conversion" in Acts 9:1-31, 22:6-21, and 26:12-17 in consideration of the contemporary literary milieu of the Greek philosophical and Hellenistic Jewish discourses on one's "conversion," i.e., a radical change as discarding his/her former thoughts. Through this analysis, I argue that Luke redescribed Paul’s experience of the risen Christ as a "conversion," and in doing so, constructed the concept of "Christian conversion" as a radical philosophical turn. In his undisputed letters, we find that Paul understood his encounter with the risen Christ as a "calling" within the Hebrew prophetic tradition. On the contrary, Luke stresses the radical rupture between Paul's before and after the revelatory experience by making it an immediate change and adding details such as Saul’s activities as a persecutor and his name change. In recasting Paul's experience as a "conversion," Luke utilized two main literary elements to characterize the nature of his experience as a radical cognitive shift. One is the metaphor of transition from darkness to light, which is applied to Paul in Acts 9 and 22 as he becomes blind after seeing the light and to the gentile conversion in Acts 26 that they should "turn from darkness to light (v.18)." Another is the notion of repentance that Luke applies directly to Paul in Acts 9 and 22 in his baptism and to the gentile conversion in Acts 26. These two motifs are what we often find in the Greek philosophical and Hellenistic Jewish texts discussing one's radical cognitive shift to a new philosophical system or the Jewish monotheism upon the revelation of a true teaching. By applying these motifs to the "conversion" of Saul, Luke identifies Paul's experience and "Christian conversion" as a radical philosophical turn from ignorance to a correct understanding of the messiah and the God. With the Lukan literary and conceptual efforts in Acts, Paul now becomes a paradigmatic "Christian convert" and a philosopher in Acts whose radical cognitive shift can be followed by Jews and gentiles in the Roman world.Item Cluster model calculations for photodisintegration of p6sLi.(Texas Tech University, 1974-08) Wood, Kathryn ElizabethNot availableItem Effect of temperature, dissolved inorganic carbon and light intensity on the growth rates of two microalgae species in monocultures and co-cultures(2014-05) Almada-Calvo, Fernando; Kinney, Kerry A.; Katz, Lynn E.The enormous biodiversity of microalgae as well as their high photosynthetic rates can be exploited for a wide variety of applications including the production of high value chemicals, nutraceuticals, aquaculture feed, and most recently, biofuels. Regardless of the application, the productivity of the microalgae culture must be optimized in order to make the systems economically feasible. One environmental factor that greatly affects the productivity of mass cultivation systems is temperature since it can be prohibitively expensive to control in outdoor systems. Temperature affects microalgae growth rates both directly by its effect on metabolic rates, and indirectly, by changing the bioavailability of the inorganic carbon present in solution. In the first part of this research, the effects of dissolved inorganic carbon (DIC) concentration (varied by sparging CO₂-enriched air) and temperature on the growth of a model microalga species (Nannochloris sp., UTEX LB1999) were investigated in a turbidostat bioreactor. The results indicate that increasing DIC concentration yields higher microalgae growth rates up to an optimum value (around 3 mM for Nannochloris sp.) but higher concentrations actually inhibited growth. Since increasing the temperature decreases the DIC concentration for a given gas pCO₂, it is necessary to adjust the pCO₂ to maintain the target DIC concentration in the optimal range for growth. In the next phase of the research, the effect of average light intensity (Gav) and temperature on the growth rate of two microalgae species (Nannochloris sp., UTEX1999. and Phaeodactylum tricornutum, UTEX646) was investigated. Growth rates were measured over a range of average light intensities and temperatures using a turbidostat bioreactor. A multiplicative model was developed to describe growth as a function of both average light intensity and temperature. In the third phase of this research, both microalgae species were grown together to explore the effects of temperature fluctuations on the population dynamics of the co-culture. It was observed that Nannochloris was inhibited by the presence of P. tricornutum in the medium, probably due to the excretion of secondary metabolites into the medium that affected Nannochloris growth (allelopathic effects). The temperature and average light intensity model developed under monoculture conditions was modified to incorporate the allelopathic effects observed. The resulting model provided a reasonable fit to the dynamic behavior of a Nannochloris/P. tricornutum co-culture subjected to temperature variations in chemostat experiments.Item High resolution retinal imaging to evaluate laser and light safety in the retina for near and long term health effects(2012-12) Pocock, Ginger Madeleine; Snodderly, D. Max; Rylander, H. Grady (Henry Grady), 1948-; Markey, Mia K.; Milner, Tom E.; Oliver, Jeffrey W.The purpose of this research was to investigate detect and monitor laser-tissue interactions at threshold and potentially sub-threshold levels of injury. High resolution imaging modalities can provide a deeper understanding of candidate biomarkers disease and injury at the molecular, cellular, and tissue-levels which can be used to identify and diagnose early stages disease and damage. In addition, multi-scale and multi-modal imaging have also been used to identify inherent biomarkers of retinal disease and injury. Monitoring tissue changes can be mapped back to biological changes at the cellular and sub-cellular level. Diseases often alter tissue on the ultra-structural level yet retinal clinical diagnosis often monitor changes in tissue at the organ level. If injury and disease is detected and diagnosed during an “early” stage of development, treatments and drug interventions may prevent further spread of the pathology. Non-invasive imaging is expected to be a valuable tool for in vivo medical research as well as for the diagnosis and management of disease. In addition to developing new imaging tools and techniques to image the retina, the identification of inherent biomarkers of disease and health using diagnostic methods are almost equally as important. Using the inherent optical properties of retinal tissue, we can non- invasively quantify differences in the absorption and reflection of light to gauge the risk for visual disability or worse yet irreversible vision loss as a result of retinal disease and chronic light exposure. The research presented with in this dissertation is three separate studies aimed at identifying light injury and potential biomarkers indicating the risk of light mediated development of disease.Item LAMBDA(2013-05) Andrus, Ryan Charles; Habeck, Michelle M.LAMBDA was an exploration of science and art in two components: a performance-lecture and an art installation. This project asserted that performance and art are effective methods of delivering scientific information to a general audience. The first component was a solo performance-lecture that used lights, projection, costumes, props, and sound in a hybrid classroom space. The performance-lecture covered the topics of light, the Aurora Borealis, gravitational lensing, and the cosmic microwave background. The art installation used light emitting objects to visually represent the gravitational disturbances that exist within a section of space-time.Item Lightspace and the city of perpetual moonlight(2013-05) Conquest, Julie Marie; Campbell, Craig A. R., 1973-Anthropological research discusses the potential of light to act as a social agent, influence culture and substantially effect the ways that people interact. To enrich this scholarship with ethnographic engagement the following analysis applies and expands upon these concepts while discussing a database documentary about the moonlight towers of Austin, Texas. Moonlight towers are historic street lights dating from the late 19th century that are no longer necessary to light the city and yet they remain as fine engineered sentinels, shedding mercury vapor luminance over the city. This is a meditative inquiry into the types of agency light has in particular spaces referred to in this work as the ruminating concept of lightspace. As a concept, lightspace refers to the experience of light in space and is concerned with how light illuminates and shapes the everyday, tracing fissures between inclusion and exclusion. This work acknowledges the existence of lightspace in order to show there are ways that light shapes our experiences of which we are only partially aware. In the midst of this attunement to the experience of light are valid ideas about how people in Austin, Texas relate to space and to each other. The work of Henri Lefebvre is used as a point of departure to develop the concept of lightspace. In The Production of Space, Lefebvre arrives at the conclusion that the experience of geographical space is fundamentally social by making connections between perceived space and conceived space to create lived space of the imagination (1978: 70). In this philosophy, perceived space as constitutes our lived, everyday experience of space, while conceived space is a translation of perceived space using knowledge, signs, and codes, such as a map. Lived space then is our own unique, individual negotiation of perceived space using conceived space. This introduction to lightspace shows how connecting perceived and conceived lightspace in Austin reveals a lived experience of light in the imagination.Item Structural Basis for Signal Transduction in LOV Blue Light Photoreceptors(2011-08-26T17:33:55Z) Nash, Abigail I.; Gardner, Kevin H.This research focused on studying the mechanisms of signal transduction within Light-Oxygen-Voltage domains, a subset of the PAS domain family. The first of two projects addressed intradomain signaling from the hydrophobic core to the domain surface. In this study, we addressed the role of a specific conserved residue in transmitting activating signal from the domain core to surface structural elements. Through biophysical and biochemical studies of LOV proteins containing point mutations at key residues, we determined that structural strain placed on the domain following light-induced covalent adduct formation regulates both structural based signal transduction as well as dark state recovery kinetics. In the second project, I characterized a novel LOV containing protein comprised of an N-terminal LOV domain and a C-terminal DNA binding helix-turn-helix (HTH) domain. Following initial characterization of this protein, I was able to determine how light-induced covalent adduct formation in the N-terminus leads to interdomain separation through release of inhibitory contacts with the HTH domain, allowing for DNA binding. Comparisons of this protein with other known HTH proteins highlight the conserved signal transduction pathways of both the LOV domain and the HTH domain.Item The identification and characterization of seedlings hyper-responsive to light 2 (SHL2), a gene implicated in developmental responses to light(Texas A&M University, 2007-04-25) Seong, Mi-SeonMutants showing developmental hyper-responsiveness to limited light were screened and designated as seedlings hyper-responsive to light (shl). These mutants showed an etiolated phenotype similar to wild type in the dark, yet had shorter hypocotyls, larger cotyledons, and more advanced development of true leaves than wild type in low light. The SHL genes act (genetically) as light-dependent negative regulators of photomorphogenesis, possibly in a downstream signaling or developmental pathway that is shared by the major photoreceptor genes (CRY1, PHYA, and PHYB) and other photoreceptors (CRY2, PHYC, PHYD, and PHYE). shl1 and shl2 were shown to be partially dependent on HY5 activity for their light-hyperresponsive phenotypes. shl1-1 showed a defect in responding to auxin in its root development in both white and yellow light conditions, and showed a defect in responding to auxin in hypocotyl elongation in yellow light. Compared to wild type, both shl1-1 and shl2-2 showed increased hypocotyl length in response to cytokinin in white light. Gibberellin (GA) partially recovered shl1-1 mutant phenotype in yellow light, whereas showed no effect on hypocotyl elongation of shl2-2 in this light condition. These altered responses of shl1-1 and shl2-2 to multiple phytohormones in different light regimes suggests that cross-talks among light and hormones regulate SHL1 and SHL2. One of the SHL genes, SHL2 was cloned by map-based positional cloning and shown to be allelic to the previously identified locus designated murus3(mur3) and katamari1(kam1). MUR3/KAM1 encodes a XyG galactosyltransferase. Sequence analysis demonstrated that our original EMS generated reference allele shl2-2 is probably not a null mutant, therefore the phenotypes of T-DNA insertion null mutant in SHL2, SALK_074435 were studied in different light conditions. Unlike shl2-2, SALK_074435 had a slightly short hypocotyl phenotype in the dark (though not to the extent of the det/cop/fus mutants). A consideration of the phenotypes and molecular lesions of shl2-2 and mur3 alleles, along with the phenotypes of null alleles kam1 and SALK_74435, suggests that SHL2/MUR3/KAM1 may be involved in hypocotyl elongation in low light through the modification of xyloglucan in the plant cell wall, and may play a role in hypocotyl elongation in the dark through proper organization of the endomembrane.Item The Investigation of the Effects of Low Light Laser Therapy on Insulin Secretion in Porcine Islets, a Pilot StudyRaptis, Darren James; Huang, Floyd; Mason, Carolyn; Moore, KellyLED light technology is used in this pilot study to demonstrate the ability to create a cost effective light apparatus using 1-watt LEDs with wavelengths of 740nm,850nm, and 940nm to test for an increased insulin response using porcine islet of Langerhans cells. This is building on recent research showing increased insulin response in rat islet cells when exposed to LED light. However, due to the high variance and low sample size, statistically significant changes were not measured when irradiating cells with 740nm, 850nm, and 940nm LED light using 7.9 J/cm2 and 15.8 J/cm2 dosages along with low and high glucose conditions. There are however possible trends of increased insulin secretion that may become significant with increased sample size. There is a need to repeat this study to definitively determine if increased insulin secretion does occur in porcine islet of Langerhans cells along with any potential negative effects and what the optimal wavelengths and dosages would be. Using the cost effective light apparatus, additional wavelengths can be experimented with to cover between 300nm to over 1600nms. The information garnered from this research has the potential to improve islet of Langerhans cell transplantation for type one diabetes (T1D) patients by decreasing the number of cells needed to be therapeutic and increasing insulin release.Item Using Light-Activated EFG to Control Cell Behavior with Automated Instrumentation(2008-05-13) Miller, Danielle Suzanne; Luebke, Kevin J.A key interest in cell biology is the ability to control cell behavior, particularly for creating functional assemblies of cells to restore, maintain or enhance tissue and organ function. Success in controlling cell behavior must include techniques that provide signals which influence the organization, growth and activities of cells. Growth factors are naturally occurring proteins that act as external chemical signals and which play a key role in regulation and control of a variety of cellular processes, such as differentiation, proliferation and migration. One of the challenges in controlling these processes using growth factors is the ability to spatially direct their timed release to the cellular environment. Another challenge then becomes the continued ability to influence these processes with the dynamic flexibility to meet the changing cellular demands during tissue development. We have developed a technology that uses light-activated epidermal growth factor (EGF) to influence cell behavior. We used peptide synthesis to incorporate a photolabile caging group on a critical residue. The caged-growth factor was inactive until converted with light, which enabled the management of its effects with the precision with which light could be directed. Since the factor was a soluble, diffusible species, it was not limited to a static pattern or substrate. Thus, dynamic control over its mitogenic and chemotactic effects on cell behavior was achieved. To utilize the light-activated EGF we developed a device for its delivery and activation. The system was a fully automated machine capable of maintaining the strict requirements of cell culture, integrated with components that achieved interchangeable, high resolution patterns, along with an optical system for photo-activating caged growth factors. The instrument was designed, characterized and then used to investigate the effect of light-activated EGF on cell patterning and mobility. Using this device, spatially resolved fibroblast cell patterning and migration were achieved.