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Lewis, Bonnie Emma. "Growth and Calcification of Reef-Building Coralline Algae and Their Response to Ocean Acidification." Thesis, Griffith University, 2016. http://hdl.handle.net/10072/366854.
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Coralline algae play a central role in tropical reef ecology helping to build and stabilise the reef framework. Due to their high Mg-calcite skeleton, coralline algae are also one of the most sensitive marine calcifying organisms to ocean acidification, and potential indicators for assessing the impacts of climate change. However, despite their importance in reef ecology, basic information on coralline algae, such as their growth and calcification rates, are relatively unknown. The reason for this scarcity of information is, in part, due to the lack of effective and efficient methods for obtaining these rates in the field, and the slow growth of coralline algae necessitating lengthy studies. Therefore, the aims of this study were to establish more effective methods to determine in situ growth and calcification rates of coralline algae, to determine baseline growth and calcification rates of a key reef-building coralline algae species on the Great Barrier Reef (GBR), and to investigate the effects future climate change scenarios may have on these growth rates.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
Griffith School of Environment
Science, Environment, Engineering and Technology
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Webster, Jody Michael. "The response of coral reefs to sea level change: evidence from the Ryukyu Islands and the Great Barrier Reef." Thesis, The University of Sydney, 1999. https://hdl.handle.net/2123/28076.
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This thesis defines the response in two time frames, of individual reefs and coral reef ecosystems to sea-level change, through the bio-geological analysis of such reefs, on both active and passive margins. The raised Holocene reefs at Kikai-jima, Japan (Central Ryukyu Islands, ie. active margin) were examined for horizontal and vertical variation in exposed sections, and in drill core to determine the biological response of reefs to sea level fall. Holocene palaeoclimatic signals from a massive fossil coral at Kikai-jima were also investigated and their implications for reef growth and palaeoceanography discussed. Finally, two high-resolution cores from the Northern Great Barrier Reef (ie. passive margin) were examined to determine the biological response of reefs to repeated sea-level rise and fall over the last ~3 50 ky.
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Solihuddin, Tubagus. "Holocene reef accretion of the inshore Kimberley Bioregion and response to sea-level changes." Thesis, Curtin University, 2016. http://hdl.handle.net/20.500.11937/2433.
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The Kimberley Bioregion of Northwest Australia is one of the world’s last great pristine marine environments and is broadly recognised as a “biodiversity hostspot” but is poorly known and studied. This project completed a comprehensive description of reef geomorphology and associated habitats, stratigraphy, palaeoecology, geochronology, accretion history along with shallow seismic profile. A combination of the data collected and interpreted provides the foundation for a scientifically based management plan of the Bioregion.
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Pitts, Kelly A. "Early Life History Response of Reef Building Coral, Orbicella faveolata, to Ocean Acidification and Warming." Thesis, NSUWorks, 2018. https://nsuworks.nova.edu/occ_stuetd/490.
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Ocean warming and acidification pose major threats to coral reef organisms. It is unknown how the early life history stages of Atlantic corals cope with the combined effects of these two global environmental stressors. Here, I investigate how these stressors influence the fertilization success, larval survivorship, and settlement of the threatened Atlantic coral, Orbicella faveolata. Gametes from O. faveolata were subjected to a factorial combination of present and future scenarios of oceanic temperatures (28.5° C and 30° C) and pH (8.2 and 8.0) predicted to occur by 2050. Results indicate that treatment type did not significantly affect fertilization success. Elevated temperature caused complete larval mortality and inhibited the settlement of O. faveolata. Interestingly, these negative effects of high temperature were partially mitigated when combined with ocean acidification. Overall, both the larval survivorship and settlement in the combined treatment was reduced to approximately half when compared to ambient treatment. Although ocean acidification may partially mitigate the negative effects of ocean warming during the larval stage, the overall reduced survival and settlement of larvae under future oceanic conditions, coupled to reduced calcification in adults, portends devastating effects on the health of this threatened species.
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Wei, Jingxian. "Reconstruction of palaeoenvironmental changes and the response of the Great Barrier Reef (GBR) ecosystem since 30,000 BP: implications from REY (rare earth elements and yttrium) and element ratios of reef-building carbonates." Thesis, The University of Sydney, 2021. https://hdl.handle.net/2123/25980.
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Our understanding of the development of the Great Barrier Reef (GBR) in response to sediment inputs over the past 30 ka is limited. Geochemical proxies including rare earth elements and yttrium (REY) along with element ratios (Pr/Yb, Y/Ho, Mn/Ca, Nd/Yb and Ce anomalies) are known to be closely related to sediment and nutrient input. This research conducts novel geochemical analysis on almost 200 fossil reef building samples that formed since the Late Pleistocene, the last 30 ka.
The first part of this research focuses on improving the methodology for ICP-MS analysis. Then a series of experiments are conducted to evaluate factors that may bias REY results, including the inter-taxa differences of genera within a specific family, sampling position and potential influence meteoric diagenesis effects. The results indicate the REY are not affected by these factors, which greatly expands the range of samples available for the reconstruction of palaeo-water quality.
Both coral and microbialite samples from the GBR since 30 ka show typical geochemical features of well-oxygenated, shallow ambient seawater. However, both spatial and temporal differences exist in these geochemical signals. The northern-central GBR samples record higher values for ΣREY and other geochemical proxies than southern-central GBR samples. The reasons include differences in shelf geomorphology, timing and rates of shelf flooding, and palaeo-mangrove development near the northern-central GBR as an additional source for the sediments. Temporally, five distinct geochemical peaks in ΣREY and other geochemical proxies are observed, at 22-20 ka, 18-17 ka, 16-15 ka, 12-10 ka and 8-6 ka. These peaks are associated with a degradation in reef development, characterised by major changes in coral-algal assemblages, decreases in accretion rates and even death events, that are consistent with previous studies, including those on downhole gamma ray and palaeoecology work.
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Boonstra, Roxane K. "Latitudinal Patterns in the Distribution of Algal Symbionts (Symbiodinium spp.) in Reef Corals of Madagascar, and their Response to Thermal Disturbance." Scholarly Repository, 2011. http://scholarlyrepository.miami.edu/oa_theses/269.
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The island continent of Madagascar spans nearly 13.5o of latitude in the SW Indian Ocean. Its coastline includes a number of well developed coral reefs, ranging from tropical Nosy Bé (NW Madagascar, 12oS) and Vohemar (Volhmarina, NE Madagascar, 13oS) to subtropical Tuléar (Toliara , SW Madagascar, 23.5oS), as well as temperate coral communities at Fort Dauphin (Tolagnaro, SE Madagascar, 25oS). Given the range of environmental conditions experienced by reef corals at these different sites, Madagascar represents an ideal location to study the distribution of algal symbionts (Symbiodinium spp.) in these coral hosts. To investigate the effect of latitudinal gradients in temperature on Symbiodinium distributions, 220 samples from 27 coral genera in 12 families were collected from these 4 sites in September 2001. To test the stability of these distributions over time, a further 337 samples were collected from the Nosy Bé and Tuléar regions in March 2007 and November 2009. Symbiodinium communities were screened using Denaturing Gradient Gel Electrophoresis (DGGE) to analyze the internal transcribed spacer-2 (ITS-2) region of Symbiodinium ribosomal DNA, with individual symbiont taxa identified by sequencing individual DGGE bands. Significant differences were found in the Symbiodinium cladal composition of reef corals at different sites, with corals at northern sites containing a higher relative frequency of Symbiodinium in clade D (occurring as mixed clade C+D communities) than southern sampling sites. Nominal logistic analysis of the distribution of symbionts found a significant effect of coral taxa and site, but not of sea surface temperature metrics (environmental data obtained from NOAA’s Coral Reef Watch satellite-derived data) in determining the distribution of different symbionts. Rarefaction analysis indicated there were no differences in Symbiodinium richness (at either the clade or the subtype level) between different sites, or between different sampling intervals. Differences existed in the subcladal composition of dominant ITS-2 types found in congeners at different latitudes, with corals in the genus Acropora being dominated by Symbiodinium C3 (specifically subtype C3z) in northern sites, and C1 in southern sites. Symbiont communities changed between 2001 and 2007/2009, with increases in mixed Symbiodinium C+D assemblages occurring at southern sites that had experienced temperature stress during the intervening period. Decreases in mixed Symbiodinium communities occurred at northern sites, which were not as severely affected by thermal stress. It is suggested that the latitudinal gradients in Symbiodinium found in Madagascar, and the environmental controls on community structure described here, provide important insight into how coral species in this understudied area can adapt or acclimatize to changing environmental conditions through shifts in the composition of their symbiont communities. This will help improve our understanding of how projected climate change in the SW Indian Ocean will affect survival trajectories for coral reefs in the region.
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Cardenas, Anny [Verfasser], Astrid [Akademischer Betreuer] [Gutachter] Gärdes, and Christian [Gutachter] Voolstra. "Bacterial Response to Elevated Dissolved Organic Carbon in Coral Reef Ecosystems / Anny Cardenas ; Gutachter: Astrid Gärdes, Christian Voolstra ; Betreuer: Astrid Gärdes." Bremen : Staats- und Universitätsbibliothek Bremen, 2017. http://d-nb.info/1124131418/34.
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Eddleman, James L. "Elevation, Longitudinal Profile, And Schmidt Hammer Analysis Of Strath Terraces Through Capitol Reef National Park, Utah: Bedrock Channel Response To Climate Forcing?" Diss., CLICK HERE for online access, 2005. http://contentdm.lib.byu.edu/ETD/image/etd936.pdf.
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Egner, Sarah A. "Auditory Sensitivity of Sergeant Majors (Abudefduf saxatilis) from Post-settlement Juvenile to Adult." Scholar Commons, 2004. https://scholarcommons.usf.edu/etd/1023.
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There is much evidence supporting the idea that pelagic larvae of coral reef fishes are active participants in their dispersal and return to a reef, however, the mechanisms used to navigate are still uncertain. It has been proposed that sensory cues, such as hearing, play a role. Sound is a potentially important cue for organisms in marine environments, especially in noisy environments like coral reefs. Sensory organs, including otolithic organs, of most coral reef fish form within the first few days of life. The auditory brainstem response (ABR) technique was used to measure hearing on a wide size range of sergeant majors (Abudefduf saxatilis). Complete audiograms were measured for 32 fish ranging in size from 11-121 mm. Significant effects of standard length on hearing thresholds at 100 and 200 Hz were detected. At these lower frequencies, thresholds increased with an increase in size. All fish were most sensitive to the lower frequencies (100-400 Hz). The frequency range that fish could detect sounds was dependent upon the size of the fish; the larger fish (>50mm) were more likely to respond to higher frequencies (1000-1600 Hz). A. saxatilis have poor hearing sensitivity in comparison to audiograms of other hearing generalists including other species of Pomacentrids. Due to the high hearing thresholds found in this study in comparison to recorded ambient reef noise, it is unlikely that sound plays a significant role in the navigation of the pelagic larvae of sergeant majors to the return of the reef from large distances.
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Lewis, Brett Maxwell. "Clast assimilation and substrate attachment in Acropora millipora." Thesis, Queensland University of Technology, 2019. https://eprints.qut.edu.au/127345/2/__qut.edu.au_Documents_StaffHome_StaffGroupH%24_halla_Desktop_Brett_Lewis_Thesis.pdf.
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Tropical storms cause large sediments to settle on top of and between the branches of coral colonies where they cannot be removed, leading to disease and higher rates of mortality. It is imperative that we understand how corals respond to fragmentation and large clast sedimentation as tropical storms are projected to intensify as earth's climate changes. This study identifies the complex physiological and immune response leading to the assimilation of the sediment into the coral colony and how coral fragments attach to a substrate in the reef-building coral Acropora millipora. Thereby providing a baseline for coral transplantation restoration practices.
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Isaack, Anja [Verfasser], Eberhard [Gutachter] Gischler, and Gilbert F. [Gutachter] Camoin. "A multi-proxy approach considering reef, sand apron and lagoon development in response to late quaternary geomorphological and environmental changes / Anja Isaack ; Gutachter: Eberhard Gischler, Gilbert F. Camoin." Frankfurt am Main : Universitätsbibliothek Johann Christian Senckenberg, 2017. http://d-nb.info/1138276723/34.
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Kilfoyle, Audie Kirk. "Exploring the Potential for Artificial Reefs in Coral Reef Restoration: Responses and Interactions of Associated Biota to Varying Experimental Treatments in the Mexican Caribbean." NSUWorks, 2017. http://nsuworks.nova.edu/occ_stuetd/440.
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Coral reefs are being negatively impacted by various causes worldwide, and direct intervention is often warranted following disturbance to restore or replace lost ecosystem structure and function. An experimental coral reef restoration study involving standardized artificial reef modules (ReefballsTM) was conducted in Mexico’s Yucatan Peninsula in the towns of Puerto Morelos and Akumal. The purpose was to explore the use of artificial structure for restoration and mitigation applications in a highly diverse and dynamic Caribbean coral reef environment by applying and evaluating the performance of select experimental treatments hypothesized to accelerate development of the associated biota. The first treatment consisted of invertebrate enhancing artificial substrate padding material, which provided structurally complex refuge space for mobile epifaunal/infaunal invertebrates and other benthic organisms. The second treatment consisted of coral transplants, intended to provide additional structural complexity and kick-start development of stony coral populations. The third treatment consisted of settlement plates which were intended to provide data on coral recruitment and survival rates. Multiple hypotheses relating to the interactions between experimental treatments and the resulting macroalgal, non-coral invertebrate, stony coral, and coral reef fish assemblages were examined, and comparisons were made between natural and artificial substrates. In Puerto Morelos there were 40 modules; 10 controls and 10 of each of 3 treatments: substrate pads, coral transplants, and settlement plates. In Akumal there were 12 modules; 6 controls and 3 of each of 2 treatments: substrate pads and settlement plates. Following module deployment, 6 biannual monitoring trips were made over the course of three years to assess the development of the biota, with a final 7th trip made six years post-deployment. Divers conducted non-destructive visual surveys to evaluate total abundance, species richness, size class distribution, and assemblage structure of coral reef fishes. Other monitoring work included coral recruit surveys, mobile epifaunal invertebrate collections from substrate pads, and digital imaging of coral transplants, natural reef reference corals, and benthic quadrat areas. Hurricane Dean compromised the Akumal study site during the first year of the study, but Puerto Morelos was unaffected. There the modules developed biotic assemblages that differed from what was found on the natural reef, and the data suggests that the substrate pads may have had an effect on the development of faunal assemblages. Lobophora variegata macroaglae and Desmapsamma anchorata sponge were the major contributors to benthic community composition, and both had significantly greater coverage on the substrate pads treatment modules. Lobophora grew rapidly and peaked within the first year, while sponges increased steadily throughout the first three years of the study, surpassing the coverage of macroalgae before the end of the second year, much to the detriment of coral transplants and many coral recruits. By the end of the study, over 75% of the transplants were overgrown by D. anchorata, and density of new coral recruits on the Pads treatment modules was lower than the other treatments and controls. Coral recruitment was dominated by Porites astreoides on all treatments and controls, and the number of corals increased steadily throughout the study. The controls had consistently greater numbers of corals than the treatments, as well as lower percent coverage of macroalgae and sponges. Total abundance and species richness of reef fishes was generally unaffected by the treatments. However, at the family and species level, several differences were detected, particularly for the substrate pads treatment and to a lesser extent for the coral transplants treatment. For future restoration or mitigation efforts utilizing similar or identical treatments to artificial substrates, this study suggests that, in the absence of routine maintenance, greater success may be achieved after waiting several years post-deployment for the initial wave of unchecked growth by benthic organisms (i.e., macroalgae and sponges) to reach a balance point before a large investment of resources is devoted to coral transplanting. Further recommendations include routine monthly or quarterly on-site maintenance to enhance transplant survival, as well as a longer monitoring window to assess community development in response to experimental treatments. The results of this study suggest that the experimental treatments did indeed have an effect on the biota, but whether or not the effect was beneficial largely depends upon perspective. The Pads treatment in particular had the greatest effect on both reef fish and benthic community development, however, it was not beneficial for stony coral recruitment. Additional research is needed to fully understand the long-term performance and effects of the padding material on biotic assemblage development for future restoration or mitigation projects.
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Morgan, Michael Boyce. "Assessing coral stress responses at the level of gene expression." Diss., Georgia Institute of Technology, 2001. http://hdl.handle.net/1853/27985.
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Gouraguine, Adam. "Habitat driven responses of reef fish : temporal change, niche partitioning and selection." Thesis, University of Essex, 2018. http://repository.essex.ac.uk/22278/.
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Shallow water tropical and temperate marine habitats are changing dramatically in response to many stressor-driven effects. The change in turn threatens the associated fish communities relying on their maintenance for habitat provision. At present, a much better understanding of the interaction between changing habitats and the associated fish is necessary. To address the lack of understanding of the habitat – fish association, mechanisms which underpin the habitat driven responses of reef fish were examined, from entire communities down to species level, across tropical and temperate ecosystems. Using a highly biodiverse ecosystem as the model system, effects of changing habitat on the associated fish community were observed, consequently demonstrating how important, in terms of shelter and food resources, the overall habitat is in structuring the fish community. Furthermore, patterns of habitat use of certain fish species within and across tropical and temperate ecosystems were examined. Variation in the size of the habitat used and its overlap between species within systems, and uniform patterns in habitat use and comparable fish habitat size and overlap across systems, were discovered. By looking at fish habitat use within systems, invaluable knowledge was gained on ecological interactions between habitat and fish on a small scale. At the same time, detection of similar mechanisms of fish habitat use across ecosystems indicates to possible uniform response of fish communities to habitat change at a large-scale. Finally, by looking at fish habitat selection using olfaction, in a temperate model system, a range of subtle behavioural responses displayed during habitat selection were detected. These results highlighted the extent of complexity of the mechanisms used in fish habitat selection and the ubiquitous importance of the habitat and its properties for the associated fish. In addition to, and based on the ecological significance of the findings, a number of potential management and conservational applications of the research were given within the thesis.
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Page, Tessa. "Understanding the Molecular and Physiological Responses of Tropical Coralline Algae to a Changing Ocean." Thesis, Griffith University, 2021. http://hdl.handle.net/10072/406520.
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Coral reefs are amongst the most biologically diverse ecosystems on our planet, supporting the livelihoods of millions of people globally. Despite their economic and ecological importance, human-driven global change is posing a major threat to the integrity of coral reefs worldwide. Ocean warming (OW) and ocean acidification (OA), both brought on by increased atmospheric CO2, are adversely affecting coral reefs and the organisms that inhabit them, particularly those organisms that calcify. Crustose coralline algae (CCA) are calcifying red macroalgae that provide essential ecosystem functions to coral reefs worldwide. CCA help to build and stabilise the coral reef framework and contribute to reef resilience and recovery by inducing the settlement of coral larvae to the reef. Previous research has shown CCA to be vulnerable to OW and OA, with resulting changes to their physiology and biology (i.e., reductions in calcification, abundance, survival). However, research on CCA lags behind other coral reef organisms, particularly in terms of their acclimatisation potential and knowledge of molecular, cellular, and metabolic processes. Given the known vulnerability of CCA, urgent research is required to understand how CCA will respond across molecular and physiological levels to global change drivers and this could directly aid in reef restoration efforts.
The first data chapter of my thesis (Chapter 2) provides previously missing molecular information for CCA. De novo transcriptomes were compiled for four species, Porolithon cf. onkodes, Sporolithon cf. durum, Lithophyllum cf. insipidum, and Lithothamnion proliferum, that commonly occur in Australia’s Great Barrier Reef (GBR). Analyses of orthologous genes were conducted between CCA species and two noncalcifiying red algae, Chondrus crispus and Gracilariopsis chorda. Functional enrichment analysis of CCA orthologous proteins revealed a higher-than-expected number of sequences in categories relating to regulation of biological and cellular processes, such as actin related proteins, heat shock proteins, and adhesion proteins. This study allowed me to create reference transcriptomes that can be used in future studies investigating molecular responses of CCA to OW and OA and offered insight into the evolution of coralline algae.
In Chapter 3 I investigated the differential physiological and transcriptomic responses of two species of CCA, P. cf. onkodes and S. cf. durum, to global change drivers (OW and OA). Previous literature investigating the responses of CCA species to global change drivers found variable results and these have been largely speciesspecific. The two species used in this study have been documented to have contrasting responses to OW and OA. Species-specific responses were seen in both the metabolic rate measurements and in the number of differentially expressed genes (DEGs) detected, indicating resilience in one species and not in the other. This study was also the first to reveal pathways and proteins that are differentially regulated in response to global change drivers. This work will help to predict the fate and functioning of different CCA species in future ocean conditions.
Early life history stages of organisms are thought to be more impacted by climatic stressors than their adult stages, therefore, I investigated the responses across different life history stages of the CCA species S. cf. durum to varying levels of temperature and pCO2 (Chapter 4). In this study, I used adults and germlings of their first generation (F1). The findings suggest that adult stages of S. cf. durum are largely robust to end of century levels of temperature and pH, in terms of their survival and metabolic rates, and indicate that adult stages may be able to acclimatise to global change. On the other hand, the data show early life history stages of this species are highly sensitive to global change stressors with reductions in their survival and growth. This could impact the persistence of this species in future oceans.
How an acclimation history to predicted, future levels of temperature and/or pH affects the physiological responses to chronic and acute thermal stress was investigated in the last chapter of my thesis (Chapter 5). P. cf. onkodes was acclimated to chronic, varying levels of temperature and pH for 6 weeks and then subjected to an acute, increasing temperature experiment (+ 4 – 6 ºC). The findings from this study suggest that an acclimation history to elevated temperature will reduce the thermal tolerance of P. cf. onkodes to withstand anomalous temperature events, which are projected to increase in number and severity within this century.
Overall, the findings of the work described in this thesis have: 1) Made available the first comprehensive and annotated de novo transcriptomes for any species of CCA; 2) shown that physiological and transcriptomic response to global change drivers is species specific, with some CCA being more resilient and others not, and identified proteins relating to physiological processes that are differentially expressed in response to stress; 3) supported the hypothesis that early life history stages of CCA will be more impacted by global change drivers than adults of the same species, with possible plasticity being seen in adults in response to sustained exposure to stress; and 4) determined an acclimation history of elevated temperature will reduce thermal tolerance and productivity in CCA. My thesis also provides evidence that more anciently diverged genera (e.g., Sporolithon) are physiologically more robust and molecularly less responsive to global change drivers. My thesis demonstrates the strength of incorporating molecular, life history stage, and acclimation type approaches to more holistically understand the future of a critical group of reef-building organisms under global climate change and will ultimately contribute to conservation efforts that are currently being made into saving coral reefs worldwide.Thesis (PhD Doctorate)
Doctor of Philosophy (PhD)
School of Environment and Sc
Science, Environment, Engineering and Technology
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Kegler, Pia [Verfasser], Andreas [Akademischer Betreuer] Kunzmann, and Christian [Akademischer Betreuer] Wild. "Understanding coral reefs in an impacted world: Physiological responses of coral reef organisms to coastal pollution and global warming / Pia Kegler. Betreuer: Andreas Kunzmann. Gutachter: Christian Wild ; Andreas Kunzmann." Bremen : Staats- und Universitätsbibliothek Bremen, 2015. http://d-nb.info/108029421X/34.
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Bird, Paul. "Benthic microalgae on the Heron Island reef flat sediment and responses to nutrient enrichment /." [St. Lucia, Qld.], 2005. http://www.library.uq.edu.au/pdfserve.php?image=thesisabs/absthe19096.pdf.
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Porter, Augustine Gus. "Habitat structural complexity in the 21st century: measurement, fish responses and why it matters." Thesis, The University of Sydney, 2019. http://hdl.handle.net/2123/20457.
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The physical shape or structure of a habitat is a key driver of species’ distributions and central to maintaining diversity through ecological niche differentiation. Anthropogenic influences are changing the structure of habitats and the assemblages of associated organisms globally. Understanding the links between the physical shape of habitats and the organisms they support will be essential to predicting and mitigating anthropogenic impacts. In marine ecosystems climate change, bottom trawling and marine infrastructure drive changes to the structure of habitats. While many of the observed and forecast changes to structure are incidental (e.g. loss of coral or addition of shoreline armouring), there are also concerted efforts to create ecologically beneficial structures. Ecologically informed engineering presents an opportunity to augment local ecology through changes to the physical structure of an environment. Yet much of the hard earned knowledge from past studies is not applicable to the design of habitats because structurally vague summary metrics are the standard. This aim of the research described in this study is to improve the mechanistic understanding of fish responses to structure, both natural and man-made, providing advice for the creation of future habitat and insight into the underlying ecological processes. These improvements in understanding the mechanistic relationships between fish distribution and habitat structural complexity bring us closer to actively managing habitats in the Anthropocene. By creating links between the metrics used for measuring habitat complexity and those used to create it, this thesis paves the way for further insight into building environments to augment local biota.
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Nordemar, Ingrid. "Human Abuses of Coral Reefs- Adaptive Responses and Regime Transitions." Doctoral thesis, Stockholm : Institutionen för systemekologi, Univ, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:su:diva-250.
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Poli, Davide. "Gene expression responses to acute and chronic heat stress in the common reef-building coral Pocillopora verrucosa." Master's thesis, Alma Mater Studiorum - Università di Bologna, 2015. http://amslaurea.unibo.it/8326/.
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Global climate change is impacting coral reefs worldwide, with approximately 19% of reefs being permanently degraded, 15% showing symptoms of imminent collapse, and 20% at risk of becoming critically affected in the next few decades. This alarming level of reef degradation is mainly due to an increase in frequency and intensity of natural and anthropogenic disturbances. Recent evidence has called into question whether corals have the capacity to acclimatize or adapt to climate changes and some groups of corals showed inherent physiological tolerance to environmental stressors. The aim of the present study was to evaluate mRNA expression patterns underlying differences in thermal tolerance in specimen of the common reef-building coral Pocillopora verrucosa collected at different locations in Bangka Island waters (North Sulawesi, Indonesia). Part of the experimental work was carried out at the CoralEye Reef Research Outpost (Bangka Island). This includes sampling of corals at selected sites and at different depths (3 and 12 m) as well as their experimental exposure to an increased water temperature under controlled conditions for 3 and 7 days. Levels of mRNAs encoding ATP synthase (ATPs) NADH dehydrogenase (NDH) and a 70kDa Heat Shock Protein (HSP70) were evaluated by quantitative real time PCR. Transcriptional profiles evaluated under field conditions suggested an adaptation to peculiar local environmental conditions in corals collected at different sites and at the low depth. Nevertheless, high–depth collected corals showed a less pronounced site-to-site separation suggesting more homogenous environmental conditions. Exposure to an elevated temperature under controlled conditions pointed out that corals adapted to the high depth are more sensitive to the effects of thermal stress, so that reacted to thermal challenge by significantly over-expressing the selected gene products. Being continuously exposed to fluctuating environmental conditions, low-depth adapted corals are more resilient to the stress stimulus, and indeed showed unaffected or down-regulated mRNA expression profiles. Overall these results highlight that transcriptional profiles of selected genes involved in cellular stress response are modulated by natural seasonal temperature changes in P. verrucosa. Moreover, specimens living in more variable habitats (low-depth) exhibit higher basal HSP70 mRNA levels, possibly enhancing physiological tolerance to environmental stressors.
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Inman, Robin F. "Item response theory." Honors in the Major Thesis, University of Central Florida, 2001. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/225.
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This item is only available in print in the UCF Libraries. If this is your Honors Thesis, you can help us make it available online for use by researchers around the world by following the instructions on the distribution consent form at http://library.ucf.edu/Systems/DigitalInitiatives/DigitalCollections/InternetDistributionConsentAgreementForm.pdf You may also contact the project coordinator, Kerri Bottorff, at kerri.bottorff@ucf.edu for more information.Bachelors
Arts and Sciences
Psychology
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McCloskey, Bryan. "Foraminiferal responses to arsenic in a shallow-water hydrothermal system in papua new guinea and in the laboratory." [Tampa, Fla] : University of South Florida, 2009. http://purl.fcla.edu/usf/dc/et/SFE0002887.
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Vercelloni, Julie. "Quantifying the state of populations and effects of disturbances at large spatio-temporal scales: The case of coral populations in the great barrier reef." Thesis, Queensland University of Technology, 2015. https://eprints.qut.edu.au/87812/1/Julie_Vercelloni_Thesis.pdf.
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This project was a step forward in applying statistical methods and models to provide new insights for more informed decision-making at large spatial scales. The model has been designed to address complicated effects of ecological processes that govern the state of populations and uncertainties inherent in large spatio-temporal datasets. Specifically, the thesis contributes to better understanding and management of the Great Barrier Reef.
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Hypes, Kaleb Marie. "Docosahexaenoic acid modulates Class I major histocompatibility complex protein function." Huntington, WV : [Marshall University Libraries], 2004. http://www.marshall.edu/etd/descript.asp?ref=433.
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Jupiter, Stacy D. "From cane to coral reefs : ecosystem connectivity and downstream responses to land use intensification /." Diss., Digital Dissertations Database. Restricted to UC campuses, 2006. http://uclibs.org/PID/11984.
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Mohd, Najib Mohd Idris. "Characterisation of THOC4 response to replicative stress." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/122562/1/Mohd%20Idris_Mohd%20Najib_Thesis.pdf.
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Human cells are continuously subject to conditions that cause breaks to DNA. This project explored the interaction between molecules involved in repairing this damage, called hSSB1 and THOC4. Novel discoveries were made that expand our understanding of this important process and identified THOC4 as a potential novel therapeutic target in lung and breast cancer.
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Wu, Yung-Hsun. "FAST RESPONSE LIQUID CRYSTAL DEVICES." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3111.
Full textAbstract:
Liquid crystal (LC) has been widely used for displays, spatial light modulators, variable optical attenuators (VOAs) and other tunable photonic devices. The response time of these devices is mainly determined by the employed liquid crystal material. How to obtain fast response for the LC devices is a fundamentally important and technically challenging task. In this dissertation, we investigate several methods to improve liquid crystal response time, for examples, using dual-frequency liquid crystals, polymer stabilized liquid crystals, and sheared polymer network liquid crystals. We discover a new class of material, denoted as sheared polymer network liquid crystal (SPNLC) which exhibits a submillisecond response time. First, dual-frequency liquid crystals and polymer network methods are demonstrated as examples for the variable optical attenuators. Variable optical attenuator (VOA) is a key component in optical communications. Especially, the sheared PNLC VOA shows the best result; its dynamic range reaches 43 dB while the response time is in the submillisecond range at 1550 nm wavelength, which is 50 times faster than the commercial LC-based VOA. Second, we report a new device called axially-symmetric sheared polymer network liquid crystals (AS-SPNLC) and use it as LC devices. An axially-symmetric sheared polymer network liquid crystal has several attractive features: 1) it is polarization independent, 2) it has gradient phase change, and 3) its response time is fast. It can be used for polarization converter and divergent LC lens. In addition, a new method for simultaneously measuring the phase retardation and optic axis of a compensation film is demonstrated using an axially-symmetric sheared polymer network liquid crystal. This simple technique can be used for simultaneously measuring the optic axis and phase retardations of both A- and C-plates. These compensation films have been used extensively in wide-view LCD industry. Therefore, this method will make an important impact to the LCD industry.Ph.D.
Optics and Photonics
Optics
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Jiao, Meizi. "Fast-response liquid crystal displays." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4580.
Full textAbstract:
After about five decades of extensive material research and device development, followed by massive investment in manufacturing technology, thin-film-transistor liquid-crystal-display (TFT-LCD) has finally become the dominant flat panel display technology. Nowadays, LCD performances, such as viewing angle, contrast ratio, and resolution, have reached acceptable levels. The remaining major technical challenges are response time, light efficiency, and sunlight readability. Fast response time is desired to reduce motion blur and to enable field sequential color displays using red (R), green (G), and blue (B) LEDs (light emitting diodes) without noticeable color breakup. Sequential RGB colors would eliminate the commonly used spatial color filters which in turn enhances light efficiency and resolution density by ~ 3X. In this dissertation, several new approaches for achieving fast-response LCDs are explored. From material viewpoint, the most straightforward approach for achieving fast response time is to employ a thin cell gap with high birefringence and low viscosity liquid crystal (LC). We investigated the thin cell approach theoretically and experimentally. Voltage shielding effect and anchoring energy effect of alignment layers are found to play important roles on operating voltage and response time. Simulations are carried out to understand the underlying physics and confirm the experimental results quantitatively. Another approach to realize fast response time is to explore novel device configuration. Here, we proposed a dual fringing-field switching (DFFS) mode in which small LC domains are formed following the distribution of fringing fields. Therefore, it exhibits submillisecond response time without using thin cell or overdrive/undershoot voltage method. The response time of the DFFS mode is ~20X faster than a conventional vertical aligned LCD.; In addition, high optical efficiency is achieved from the complementary top and bottom active LC domains. Two transmissive and one transflective LCDs using DFFS mode are conceived and their electro-optical properties investigated. A shortcoming of DFFS LCDs is their fabrication complexity. To keep the advantages of this fast-response mode while avoiding the requirement of double-TFTs and pixel registration, we modified the device structure to transflective LCD which uses a single TFT in each pixel and vertical aligned positive dielectric anisotropy LC. Two types of electrodes are considered: fringing-field switching (FFS) and in-plane switching (IPS). Besides fast response time and high transmittance, such a transflective LCD shows good sunlight readability. As nematic LC is gradually approaching to its limit in term of response time, polymer-stabilized blue phase (PSBP) LCD is emerging. It has potential to become next-generation display because of following revolutionary features: submillisecond response time, no need for alignment layer, good dark state and symmetric viewing angle, and cell gap insensitivity if IPS electrode is employed. In this dissertation, we studied the material-property correlation of Kerr effect-induced birefringence in nano-structured PSBP LC composites. Furthermore, a new device configuration of BP LCD with corrugated electrodes is proposed to solve two critical technical issues: high driving voltage and relatively low transmittance. The on-state voltage can be reduced from ~35 Vsubscript rms] to ~10 Vsubscript rms] which will enable TFT addressing, and the transmittance is improved from ~65% to ~85%. This new device configuration will accelerate the emergence of PSBP LCD. Wide view is another important requirement for a high-end display. Several new LCD configurations with negative A-plate and biaxial plate as phase compensation films are proposed to achieve wide view and broadband operation.; The underlying working principles are studied and detailed display performances are included in this dissertation.ID: 030422960; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2010.; Includes bibliographical references (p. 114-122).
Ph.D.
Doctorate
Optics and Photonics
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Haught, Jason D. "Response to intervention and effects on retention." Huntington, WV : [Marshall University Libraries], 2007. http://www.marshall.edu/etd/descript.asp?ref=771.
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Yoke, Holly. "Staff attitude change as a result of Response to Intervention implementation in West Virginia schools." Huntington, WV : [Marshall University Libraries], 2007. http://www.marshall.edu/etd/descript.asp?ref=738.
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Perrin, Frances A. "Progressive Response Effort Preference Assessments." Diss., Temple University Libraries, 2009. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/34629.
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Educational PsychologyPh.D.
The identification of preferred and reinforcing stimuli has long been a focus of behavior analysts in applied settings. Research has primarily focused on different methodologies for assessing whether stimuli are preferred and there has been additional research on identifying under what conditions those stimuli will function as reinforcers. Recently, research has begun to examine responses and reinforcers from a behavioral economic perspective. The present study compared responding in a situation where the price of one item was increased, but the price of alternative items remained the same, to a situation where the price of all available items increased. Multiple stimulus with replacement (MS) preference assessment methodology was used and price was altered by increasing the distance of the stimuli from the participant. During the first assessment, the item chosen most frequently in the first session was systematically moved 6 - 24 inches beyond the other items during subsequent sessions. During the second assessment, all items were systematically moved 6 - 24 inches beyond the starting point in front of the participant during subsequent sessions. Results for the first assessment indicated that for four of the five participants, consumption of the target item decreased as a function of increased price for that item. Results for the second assessment indicated that at high costs, clear preference for one item was observed for three of the five participants. Taken collectively, these results suggest that response effort is a variable that should be taken into consideration when evaluating effective treatments for individuals with disabilities. Preference and reinforcer effectiveness may shift as individuals are presented with tasks that require increased response effort in terms of reaching or moving about their environment.
Temple University--Theses
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Wang, Haiying. "STUDIES OF LIQUID CRYSTAL RESPONSE TIME." Doctoral diss., University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3541.
Full textAbstract:
In this dissertation, the response time issue of the liquid crystal (LC) devices is investigated in meeting the challenges for display and photonic applications. The correlation between the LC director response time and the optical response time is derived theoretically and confirmed experimentally. A major contribution of this thesis is that, based on the small angle approximation, we derive rigorous analytical solutions for correlating the LC director response time to its consequent optical response times (both rise and decay) of a vertical-aligned nematic LC cell. This work successfully fills the gap in the literature of LCD switching dynamics. An important effect related to response time, backflow is analyzed using a homogeneous LC cell in an infrared wavelength. The Leslie viscosity coefficients can hardly be found in the literature. A new effective approach to estimate the Leslie coefficients of LC mixtures based on MBBA data is proposed in this dissertation. Using this method, the Leslie coefficients of the LC material under study can be extracted based on its order parameters. The simulation results agree with the experimental data very well. This method provides a useful tool for analyzing the dynamic response including backflow. Cell gap is an important factor affecting the LC response time. Usually a thinner cell gap is chosen to achieve faster response time, since normally both rise and decay times are known to be proportional to d2. However, they are valid only in the region. In the large voltage region where , the optical decay time is independent of d. In this thesis, we find that between these two extremes the response time is basically linearly proportional to d. Our analytical derivation is validated by experimental results. Therefore, in the whole voltage region, the physical picture of the optical response time as a function of the cell gap is completed. This analysis is useful for understanding the grayscale switching behaviors of the LC phase modulators. In conclusion, this dissertation has solved some important issues related to LC optical response time and supplied valuable tools for scientists and engineers to numerically analyze the LC dynamics.Ph.D.
Department of Electrical and Computer Engineering
Engineering and Computer Science
Electrical Engineering
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Kennedy, Ian. "THE SPUTNIK CRISIS AND AMERICA'S RESPONSE." Master's thesis, University of Central Florida, 2005. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3866.
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On 4 October 1957, the Soviet Union launched Sputnik, the world's first artificial satellite, and the Space Age had arrived. While not an American achievement, Sputnik stands as a significant juncture in United States history. This thesis explores the resulting American political crisis, its development in the final three months of 1957, and the impact Sputnik had on American life. The thesis also examines the social and political context of the Sputnik crisis and will challenge some long-standing analysis of how America's reaction to the Soviet satellite developed. To accomplish this task, it was necessary to consult both primary and secondary sources. Important primary sources include government documents from both the Legislative and Executive Branches of the United States Government, attained from both printed volumes and online archives. The memoirs of key individuals also shed light on the mindset of prominent politicians and policymakers of the period. Newspapers and magazines from the era were examined to explore the media and public reaction to the Sputnik Crisis and related events. Secondary sources are used as both avenues of information and theory regarding the events, and also for the purposes of examining the consensus of others who have explored this topic. The topics covered in the thesis include the flow of events before, during, and after the Sputnik Crisis of 1957; analysis of contextual issues such as missile and satellite development and American culture of the period; and analysis of how the Sputnik Crisis unfolded and how this impacted American culture and national policy.M.A.
Department of History
Arts and Sciences
History
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Graham, Sabrina L. "Effective reading instruction in a Response to Intervention program evaluation." Huntington, WV : [Marshall University Libraries], 2007. http://www.marshall.edu/etd/descript.asp?ref=794.
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Song, Qiong. "FAST RESPONSE DUAL FREQUENCY LIQUID CRYSTAL MATERIALS." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3112.
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Dual frequency liquid crystal (DFLC) exhibits a positive dielectric anisotropy at low frequencies and negative dielectric anisotropy at high frequencies. The frequency where dielectric anisotropy is zero is called crossover frequency. DFLC can achieve fast rise time and fast decay time with the assistance of applied voltage. However, one drawback of DFLC is that it has dielectric heating effect when driven at a high frequency. Thus, the first part of this dissertation is to develop low crossover frequency DFLC materials. The dielectric relaxation and physical properties of some single- and double-ester compounds were investigated. Experimental results indicate that the double-ester compound exhibits a ~ 3 X lower dielectric relaxation frequencies and larger dielectric anisotropy than the single ester, but its viscosity is also higher. More generally, ten groups of dual frequency liquid crystals were compared in terms of dielectric relaxation frequency and dielectric anisotropy. The dielectric relaxation theory was discussed at last. To realize fast response time, high birefringence and low viscosity LC are required. From these two aspects, firstly four new high birefringence laterally difluoro phenyl tolane liquid crystals with a negative dielectric anisotropy were studied. These materials are used to enhance the birefringence of DFLC. They have a fairly small heat fusion enthalpy (~3000 cal/mol) which improves their solubility in a host. We dope 10 wt% of each compound into a commercial negative mixture N1 and measured their birefringence, viscoelastic constant and figure of merit. Birefringence varies very little among homologues while viscoelastic constant increases as alkyl chain length increases. Secondly, we studied the effects of six diluters for lowering the viscosity while stabilizing the vertical alignment (VA) of the laterally difluoro terphenyl host mixture at elevated temperatures. The pros and cons of each diluter are analyzed. These lateral difluoro terphenyls exhibit a high birefringence, fairly low viscosity, and modest dielectric anisotropy, but their molecular alignment in a VA cell is gradually deteriorated at elevated temperatures as their concentration increases. As a result, the device contrast ratio is decreased noticeably due to the light leakage through the crossed polarizers. Finally, liquid crystal doped with metallic nanoparticles, such as Pd, Ag, or Ag-Pd, which are protected with ligand molecules, such as nematic liquid crystal were studied. The metal nanoparticles doped LC exhibit a frequency modulation (FM) electro-optical (EO) response in the millisecond to submillisecond range together with the ordinary root-mean-square voltage response.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
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Kirby, Alicia. "Staff attitude change in a Response to Intervention Program evaluation." Huntington, WV : [Marshall University Libraries], 2006. http://www.marshall.edu/etd/descript.asp?ref=673.
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Zenteno-Hidalgo, Angela Carola. "A Model of Workplace Anger Response Cycles." Diss., Temple University Libraries, 2012. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/185029.
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Business Administration/Human Resource ManagementPh.D.
Anger is considered a basic emotion, evoked typically by something that interferes with the person's execution of plans or attainment of goals, as well as the perception of harm and unfair circumstances or behavior (Shaver, Schwartz, Kirson, & O'Connor, 1987). Research examining anger is largely focused on negative individual and organizational outcomes, such as raised blood pressure and heart disease, decreased productivity, reduced job satisfaction and increased job stress, and aggressive responses (Geddes & Callister, 2007; Gibson, Schweitzer, Callister, & Gray, 2009). However, the paradoxical nature of anger--having the capacity of both negative and positive consequences--is increasingly acknowledged by influential scholars (Geddes & Callister, 2007; Gibson & Callister, 2010; Miron-Spektor & Rafaeli, 2009). For instance, both theory and data point out that anger expression can have important adaptive functions such as signaling that goals are blocked, communicating to others that their actions are viewed as threatening, and mobilizing protective actions when dealing with a perceived threat (Averill, 1983; Izard, 1993; Tafrate, Kassinove, & Dundin, 2002). In addition, most research on consequences of anger expression in the workplace focuses on individuals' characteristics and the intensity of the expression of anger. This focus, however, doesn't capture the significant social components of emotions including how their expression shapes the emotions, thoughts and behaviors of others (Hareli & Rafaeli, 2008; Parkinson, Fischer, & Manstead, 2005). The goal of this dissertation is to advance understanding of the complexity of workplace anger expression, focusing specifically on outcomes and social components of emotions. To do this, the dissertation proposes a Model of Workplace Anger Response Cycles (WARC). The model shows that the outcomes of anger expression are influenced by the interaction of the expresser and a social partner and the context where this interaction occurs--e.g. organizational culture, emotional climate, and anger expression tolerance. In addition, the model proposes that these interactions form emotional cycles and identifies factors that affect the association of anger expression and its positive or negative outcomes, namely, intensity of the message, characteristics of the individuals involved and their relationship. Given the complexity and number of variables included in the WARC model, only some were studied empirically for this dissertation. The empirical study reported here involved collection of data from full and part time employees (n=177) through on-line surveys, which were analyzed using Partial Least Square Structural Equation Modeling (PLS-SEM). The results show the salience of relationship quality, observer response, power, and gender in the explanation of outcomes of anger expression in the workplace. In particular, results support existing evidence that female expressions of anger are negatively judged compared to those by male (e.g., Brescoll & Uhlmann, 2008; Gibson, Schweitzer, Callister, & Gray, 2009; Lewis, 2000). Furthermore, findings indicate that even in organizations where anger expressions are more accepted, in general, expressions of anger by females are less welcome than those from males. Additionally, this study provides further evidence that when anger is expressed to a lower power individual, results are more positive--i.e., anger feelings are reduced and problematic situations improve--than when anger is expressed to a higher power individual (Fitness, 2000; Kuppens, Van Mechelen, & Meulders, 2004; Van Kleef & Côté, 2007). Finally, findings of this study show that relationship quality among the interactants is critical to explain the outcomes of anger expression. Furthermore, results show that relationship quality effects are partially mediated by observer response, and moderated by zone of anger tolerance. Thus, results confirm the underlying general hypothesis of this work, that emotional experiences and consequent related interactions are strongly tied to context characteristics. Therefore, to truly understand this type of phenomena and be able to predict results, consideration of multi-level variables must be integrated to the analysis.
Temple University--Theses
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Russo, Charles. "AVL AND RESPONSE TIME REDUCTION: IMAGE AND REALITY." Doctoral diss., University of Central Florida, 2006. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2647.
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Automatic vehicle locator (AVL) systems, utilizing military's global positioning system, may impact response time to law enforcement calls for service. In order to evaluate the impacts of AVL on response time to calls for service at the Altamonte Springs Police Department (ASPD), computer aided dispatch (CAD) data from years 1999 to 2003 were analyzed. The analysis of each of the data sets consisted of an initial sequence chart, an analysis of variance (ANOVA), a means plot and a linear regression. Interviews of ASPD personnel were conducted to understand user perceptions of AVL. Based on the ANOVA results, trends indicate that weekly response time was significantly lower during the AVL partial implementation period than during the pre or post AVL stages across all categories of data analyzed. Based on the regression results, trends indicate that the overall impact of AVL on response time for all categories analyzed is flat and show AVL as having no overall impact on response time across all calls for service analyzed. An exception to this is the findings related to Priority 3 calls for service; however this exception can be attributed to performance during the pre AVL implementation stage. These results do not suggest a capability for AVL to reduce response time to calls for service in a meaningful comprehensive way. Thus, the study's hypotheses are not supported.Ph.D.
Department of Criminal Justice and Legal Studies
Health and Public Affairs
Public Affairs: Ph.D.
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Sen, Shabori. "BEHAVIORAL RESPONSE TO ENDOGENOUS RISK IN THE LABORATORY." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2658.
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Risk is endogenous when an individual is able to undertake mitigation or self protection actions that reduce the risk that he faces. Most risky environments studied in economics involve endogenous risk. This dissertation studies the conceptual and behavioral implications of introducing endogeneity in the controlled environment of the laboratory. The dissertation consists of three different experiments designed to examine how endogeneity affects risk attitudes and risk perceptions in simple experimental set ups. All three experiments employ a virtual reality scenario where the subject is able to form his own beliefs, based on naturalistic cues provided by the virtual reality experience. In the first experiment, a  short run individual experiment, subjects experience several forest fires that allow them to form beliefs about the probability of a house in the simulated forest being destroyed by fire. The evidence suggests that endogenous risk settings do cause subjects to employ different subjective beliefs than they use in an exogenous risk setting, although risk attitudes appear stable across these settings. Typically, the risk of natural disaster in any area is very small, and an adverse event like a forest fire occurs only once in a couple of decades. This has implications for self-protection expenditure where risk is endogenous. A  long run individual experiment with several rounds of decision making allows the estimation of subjective beliefs about the risk of the property burning when a fire may occur. This design allows for the study of the effect of an actual experience of forest fire on a subject s beliefs. Several mitigation options are collective in nature and require group contributions for the self-protection action to be provided. In an extension of the long run design, we study the effect of an actual experience of fire on beliefs when the risk is faced by a group rather than an individual. This framework also allows us to compare behavior in a public goods game involving risk, with the standard public goods game.Ph.D.
Department of Economics
Business Administration
Economics PhD
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Xiao, Shangyang. "TRANSIENT RESPONSE IMPROVEMENT FOR MULTI-PHASE VOLTAGE REGULATORS." Doctoral diss., University of Central Florida, 2008. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3909.
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Next generation microprocessor (Vcore) requirements for high current slew rates and fast transient response together with low output voltage have posed great challenges on voltage regulator (VR) design . Since the debut of Intel 80X86 series, CPUs have greatly improved in performance with a dramatic increase on power consumption. According to the latest Intel VR11 design guidelines , the operational current may ramp up to 140A with typical voltages in the 1.1V to 1.4V range, while the slew rate of the transient current can be as high as 1.9A/ns [1, 2]. Meanwhile, the transient-response requirements are becoming stringer and stringer. This dissertation presents several topics on how to improve transient response for multi-phase voltage regulators. The Adaptive Modulation Control (AMC) is a type of non-linear control method which has proven to be effective in achieving high bandwidth designs as well as stabilizing the control loop during large load transients. It adaptively adjusts control bandwidth by changing the modulation gain, depending on different load conditions. With the AMC, a multiphase voltage regulator can be designed with an aggressively high bandwidth. When in heavy load transients where the loop could be potentially unstable, the bandwidth is lowered. Therefore, the AMC provides an optimal means for robust high-bandwidth design with excellent transient performance. The Error Amplifier Voltage Positioning (EAVP) is proposed to improve transient response by removing undesired spikes and dips after initial transient response. The EAVP works only in a short period of time during transient events without modifying the power stage and changing the control loop gain. It facilitates the error amplifier voltage recovering during transient events, achieving a fast settling time without impact on the whole control loop. Coupled inductors are an emerging topology for computing power supplies as VRs with coupled inductors show dynamic and steady-state advantages over traditional VRs. This dissertation first covers the coupling mechanism in terms of both electrical and reluctance modeling. Since the magnetizing inductance plays an important role in the coupled-inductor operation, a unified State-Space Averaging model is then built for a two-phase coupled-inductor voltage regulator. The DC solutions of the phase currents are derived in order to show the impact of the magnetizing inductance on phase current balancing. A small signal model is obtained based on the state-space-averaging model. The effects of magnetizing inductance on dynamic performance are presented. The limitations of conventional DCR current-sensing for coupled inductors are addressed. Traditional inductor DCR current sensing topology and prior arts fail to extract phase currents for coupled inductors. Two new DCR current sensing topologies for coupled inductors are presented in this dissertation. By implementation of simple RC networks, the proposed topologies can preserve the coupling effect between phases. As a result, accurate phase inductor currents and total current can be sensed, resulting in excellent current and voltage regulation. While coupled-inductor topologies are showing advantages in transient response and are becoming industry practices, they are suffering from low steady-state operating efficiency. Motivated by the challenging transient and efficiency requirements, this dissertation proposes a Full Bridge Coupled Inductor (FBCI) scheme which is able to improve transient response as well as savor high efficiency at (a) steady state. The FBCI can change the circuit configuration under different operational conditions. Its "flexible" topology is able to optimize both transient response and steady-state efficiency. The flexible core configuration makes implementation easy and clear of IP issues. A novel design methodology for planar magnetics based on numerical analysis of electromagnetic fields is offered and successfully applied to the design of low-voltage high power density dc-dc converters. The design methodology features intense use of FEM simulation. The design issues of planar magnetics, including loss mechanism in copper and core, winding design on PCB, core selections, winding arrangements and so on are first reviewed. After that, FEM simulators are introduced to numerically compute the core loss and winding loss. Consequently, a software platform for magnetics design is established, and optimized magnetics can then be achieved. Dynamic voltage scaling (DVS) technology is a common industry practice in optimizing power consumption of microprocessors by dynamically altering the supply voltage under different operational modes, while maintaining the performance requirements. During DVS operation, it is desirable to position the output voltage to a new level commanded by the microprocessor (CPU) with minimum delay. However, voltage deviation and slow settling time usually exist due to large output capacitance and compensation delay in voltage regulators. Although optimal DVS can be achieved by modifying the output capacitance and compensation, this method is limited by constraints from stringent static and dynamic requirements. In this dissertation, the effects of output capacitance and compensation network on DVS operation are discussed in detail. An active compensator scheme is then proposed to ensure smooth transition of the output voltage without change of power stage and compensation during DVS. Simulation and experimental results are included to demonstrate the effectiveness of the proposed scheme.Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering PhD
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Krenz, Peter. "RESPONSE-CALIBRATION TECHNIQUES FOR ANTENNA-COUPLED INFRARED SENSORS." Doctoral diss., University of Central Florida, 2010. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4334.
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Infrared antennas are employed in sensing applications requiring specific spectral, polarization, and directional properties. Because of their inherently small dimensions, there is significant interaction, both thermal and electromagnetic, between the antenna, the antenna-coupled sensor, and the low-frequency readout structures necessary for signal extraction at the baseband modulation frequency. Validation of design models against measurements requires separation of these effects so that the response of the antenna-coupled sensor alone can be measured in a calibrated manner. Such validations will allow confident extension of design techniques to more complex infrared-antenna configurations. Two general techniques are explored to accomplish this goal. The extraneous signal contributions can be measured separately with calibration structures closely co-located near the devices to be characterized. This approach is demonstrated in two specific embodiments, for removal of cross-polarization effects arising from lead lines in an antenna-coupled infrared dipole, and for removal of distributed thermal effects in an infrared phased-array antenna. The second calibration technique uses scanning near-field microscopy to experimentally determine the spatial dependence of the electric-field distributions on the signal-extraction structures, and to include these measured fields in the computational electromagnetic model of the overall device. This approach is demonstrated for infrared dipole antennas which are connected to coplanar strip lines. Specific situations with open-circuit and short-circuit impedances at the termination of the lines are investigated.Ph.D.
Optics and Photonics
Optics and Photonics
Optics PhD
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Carter, Scott Edward. "Finite impulse response utilizing the principles of superposition." Master's thesis, University of Central Florida, 1995. http://digital.library.ucf.edu/cdm/ref/collection/RTD/id/15187.
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University of Central Florida College of Engineering ThesisWindow functions have been greatly utilized in the synthesis of finite impulse response (FIR) filters implemented using surface acoustic wave (SAW) devices. The critical parameter in any FIR design in the impulse response length, which must be optimized for the given design specifications in order to reduce the size of each device. To this end, many design algorithms have been intorduced such as Remez excange, linear programming, and least mean squares. A new algorithm has been derived which is efficient and accurate for the design of arbitrary filter specifications requiring less computationsthan the current algorithms. The FIR design is applicaable to general SAW filter design and allows two weighted transducers to be designed in a near optimal method without the need to perform zero aplitting of de-convolution. The thesis first provides the definition of the window functions used for the design process. Then the overview of the design process is discussed using a flowchart of the modeling program for designing and FIR without tranducer separation and sample simulation is presented. Next, the effects of monotonically increasing sidelobes on the transition bandwidth are discussed. This is followed by a discussion of the addition of arbitary phase to the filter design requirements. Next, the separation of the response into a two transducer design utilizing the two window function series is explained. Finally, the results are discussed and compared with other design techniques.
M.S.;
Electrical and Computer Engineering
Engineering;
Electrical Engineering
69 p.
ix, 69 leaves, bound : ill. ; 28 cm.
43
CETINKAYA, KENAN. "TURKISH RESPONSE TO THE CHRISTIAN CALL FOR DIALOGUE." Diss., Temple University Libraries, 2014. http://cdm16002.contentdm.oclc.org/cdm/ref/collection/p245801coll10/id/298643.
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ReligionPh.D.
After the Second Vatican Council, which took place in 1962-1965, the Catholic Church reached out to both co-religionists and non-Christians. As the second largest religion in the world (after Christianity), the Muslim world began to react to this call for dialogue. Without a worldwide religious authority, Muslim scholars and communities have tried to understand and respond to this call for dialogue in their own way. Turkey, as one of the most influential and modern Muslim majority states, joined the discussion about interreligious dialogue, especially with Christians. Very diverse in culture, religion, and thought, Turkish scholars' discussions and critiques of the dialogue requested by the Christian world have clearly contributed to interreligious dialogue on a global scale in the last decades. This dissertation examines the development of interreligious dialogue in Turkey and the works of prominent and widely recognized Turkish theologians as a response to the Christian call for dialogue. It explores the problems, challenges, and future of the perception of interreligious dialogue in the Turkish context, in particular, the views of three influential Turkish scholars: Abdurrahman Küçük, Mahmut Aydin, and Davut Aydüz. The conclusion proposes the Turkish Model for interreligious dialogue.
Temple University--Theses
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Hawkins, Alicia. "DECISION-MAKER TRADE-OFFS IN MULTIPLE RESPONSE SURFACE OPTIMIZATION." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/2787.
Full textAbstract:
The focus of this dissertation is on improving decision-maker trade-offs and the development of a new constrained methodology for multiple response surface optimization. There are three key components of the research: development of the necessary conditions and assumptions associated with constrained multiple response surface optimization methodologies; development of a new constrained multiple response surface methodology; and demonstration of the new method. The necessary conditions for and assumptions associated with constrained multiple response surface optimization methods were identified and found to be less restrictive than requirements previously described in the literature. The conditions and assumptions required for a constrained method to find the most preferred non-dominated solution are to generate non-dominated solutions and to generate solutions consistent with decision-maker preferences among the response objectives. Additionally, if a Lagrangian constrained method is used, the preservation of convexity is required in order to be able to generate all non-dominated solutions. The conditions required for constrained methods are significantly fewer than those required for combined methods. Most of the existing constrained methodologies do not incorporate any provision for a decision-maker to explicitly determine the relative importance of the multiple objectives. Research into the larger area of multi-criteria decision-making identified the interactive surrogate worth trade-off algorithm as a potential methodology that would provide that capability in multiple response surface optimization problems. The ISWT algorithm uses an ε-constraint formulation to guarantee a non-dominated solution, and then interacts with the decision-maker after each iteration to determine the preference of the decision-maker in trading-off the value of the primary response for an increase in value of a secondary response. The current research modified the ISWT algorithm to develop a new constrained multiple response surface methodology that explicitly accounts for decision-maker preferences. The new Modified ISWT (MISWT) method maintains the essence of the original method while taking advantage of the specific properties of multiple response surface problems to simplify the application of the method. The MISWT is an accessible computer-based implementation of the ISWT. Five test problems from the multiple response surface optimization literature were used to demonstrate the new methodology. It was shown that this methodology can handle a variety of types and numbers of responses and independent variables. Furthermore, it was demonstrated that the methodology can be successful using a priori information from the decision-maker about bounds or targets or can use the extreme values obtained from the region of operability. In all cases, the methodology explicitly considered decision-maker preferences and provided non-dominated solutions. The contribution of this method is the removal of implicit assumptions and includes the decision-maker in explicit trade-offs among multiple objectives or responses.Ph.D.
Department of Industrial Engineering and Management Systems
Engineering and Computer Science
Industrial Engineering PhD
45
Morris, Christina Shawn. "EFFECTS OF VOLUNTARY CONTROL ON PERFORMANCE RESPONSE UNDER STRESS." Doctoral diss., University of Central Florida, 2004. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4412.
Full textAbstract:
Recent stressful environments within military and non-military domains are producing a new challenge for the lab-based study of stress on task performance, one that requires knowledge of underlying cognitive-motivational and goal orientation factors. Results of recent stress on task performance research traditionally employ metaphorical explanations (i.e., resource theory) in order to rapidly apply stimulus-response outcomes to the real world counterparts. This dissertation provides an alternative perspective about these metaphorical, or black box, interpretations and reveals how they may be confounded with respect to the intended real world counterpart. To examine how voluntary human control can influence traditional stress/no-stress research findings, traditional as well as exploratory paradigms were presented. Both noise and time pressure conditions produced significant differences between experimental and control groups on visual discrimination. However, when analogous cash payment-contingency conditions were employed, the traditional stress/no-stress findings were not evident. In addition, a second experiment revealed that this trend of differences (and non-differences) held consistently over 30 minutes of interrupted task performance time. This study indicates the importance of developing more diagnostic measures that include assessments of how the differences between participants' and the generalized operators' goals and motivations may alter results in stressful task environments.Ph.D.
Department of Psychology
Arts and Sciences
Psychology
46
Yesilyurt, Hamdi. "The response of American police agencies to digital evidence." Doctoral diss., University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/4725.
Full textAbstract:
Little is known about the variation in digital forensics practice in the United States as adopted by large local police agencies. This study investigated how environmental constraints, contextual factors, organizational complexity, and organizational control relate to the adoption of digital forensics practice. This study integrated 3 theoretical perspectives in organizational studies to guide the analysis of the relations: institutional theory, contingency theory, and adoption-of-innovation theory. Institutional theory was used to analyze the impact of environmental constraints on the adoption of innovation, and contingency theory was used to examine the impacts of organizational control on the adoption of innovation. Adoption of innovation theory was employed to describe the degree to which digital forensics practice has been adopted by large municipal police agencies having 100 or more sworn police officers.The data set was assembled primarily by using Law Enforcement Management and Administrative Statistics (LEMAS) 2003 and 1999. Dr. Edward Maguire`s survey was used to obtain 1 variable. The joining up of the data set to construct the sample resulted in 345 large local police agencies. The descriptive results on the degree of adoption of digital forensics practice indicate that 37.7% of large local police agencies have dedicated personnel to address digital evidence, 32.8% of police agencies address digital evidence but do not have dedicated personnel, and only 24.3% of police agencies have a specialized unit with full-time personnel to address digital evidence. About 5% of local police agencies do nothing to address digital evidence in any circumstance. These descriptive statistics indicate that digital evidence is a matter of concern for most large local police agencies and that they respond to varying degrees to digital evidence at the organizational level. Agencies that have not adopted digital forensics practice are in the minority.; Researchers investigating the influence of various factors on the adoption of digital forensics practice should further examine environmental variables. The unexpected results concerning the impact of administrative weight and formalization should be researched with broader considerations.; The structural equation model was used to test the hypothesized relations, easing the rigorous analysis of relations between latent constructs and several indicator variables. Environmental constraints have the largest impact on the adoption of innovation, exerting a positive influence. No statistically significant relation was found between organizational control and adoption of digital forensic practice. Contextual factors (task scope and personnel size) positively influence the adoption of digital forensics. Structural control factors, including administrative weight and formalization, have no significant influence on the adoption of innovation. The conclusions of the study are as follows. Police agencies adopt digital forensics practice primarily by relying on environmental constraints. Police agencies exposed to higher environmental constraints are more frequently expected to adopt digital forensics practice. Because organizational control of police agencies is not significantly related to digital forensics practice adoption, police agencies do not take their organizational control extensively into consideration when they consider adopting digital forensics practice. The positive influence of task scope and size on digital forensics practice adoption was expected. The extent of task scope and the number of personnel indicate a higher capacity for police agencies to adopt digital forensics practice. Administrative weight and formalization do not influence the adoption of digital forensics practice. Therefore, structural control and coordination are not important for large local police agencies to adopt digital forensics practice. The results of the study indicate that the adoption of digital forensics practice is based primarily on environmental constraints. Therefore, more drastic impacts on digital forensics practice should be expected from local police agencies' environments than from internal organizational factors.ID: 030646197; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Thesis (Ph.D.)--University of Central Florida, 2011.; Includes bibliographical references (p. 183-209).
Ph.D.
Doctorate
Health and Public Affairs
Public Affairs
47
Chen, Kuan Ming. "Submillisecond-response blue phase liquid crystals for display applications." Doctoral diss., University of Central Florida, 2012. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/5158.
Full textAbstract:
With exploding growth of information exchanges between people, display has become indispensable in our daily lives. After decades of intensive research and development in materials and devices, and massive investment in manufacturing technologies, liquid crystal display (LCD) has overcome various obstacles and achieved the performance we need, such as wide viewing angle, high contrast ratio, and high resolution, etc. These excellent performances make LCD prevailed in every perspective. Recently, with the demands of energy conservation, a greener LCD with lower power consumption is desired. In order to achieve this goal, new energy-effective driving methods, such as field sequential color display, have been proposed. However, in order to suppress color breakup the LC response time should be faster than 1 ms. To overcome this challenge, various fast-response liquid crystal modes, such as thin cell gap, low viscosity materials, overdrive and undershoot voltages, polymer stabilization, and ferroelectric liquid crystal, are under active investigations. Among these approaches, blue phase liquid crystal (BPLC) shows a greater potential with less fabrication limitations. In this dissertation, the feasibility of polymer-stabilized blue phase liquid crystal for display applications is explored starting from the building blocks of the material system, polymer-stabilization processes, test cell preparations, electro-optical (EO) properties, to suggested approaches for further improvements. Because of the nature of blue phase liquid crystals, delicate balance among system components is critically important. Besides the properties of each composition, the preparation process also dictates the EO performance of the self-assembled nano-structured BPLC composite. After the preparation of test cells, EO properties for display applications are investigated and results described. Approaches for further improvements of the EO properties are also suggested in the final part of this dissertation.ID: 031001409; System requirements: World Wide Web browser and PDF reader.; Mode of access: World Wide Web.; Title from PDF title page (viewed June 12, 2013).; Thesis (Ph.D.)--University of Central Florida, 2012.; Includes bibliographical references (p. 82-89).
Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
48
Sun, Jie. "Fast-Response Liquid Crystals for Photonic and Display Applications." Doctoral diss., University of Central Florida, 2013. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/6025.
Full textAbstract:
Liquid crystals (LCs) are attractive for many applications such as information displays, spatial light modulators, and adaptive optics because the optical properties of these devices are electrically tunable. For most display and photonic applications, response time is a critical parameter especially for spatial light modulators that requires at least 2? phase change. This problem gets more severe as the wavelength increases because a thicker LC layer is needed, which results in a slower response time. A typical E7 nematic liquid crystal cell with 2? phase change shows a response time longer than 100 ms at room temperature, which is too slow. Therefore, solutions for achieving fast response time are in high demand.
In this dissertation, several approaches for achieving submillisecond response time are investigated. In Chapter 2, we begin by introducing dual frequency liquid crystals (DFLCs) which provide possibility to achieve submillisecond rise time and decay time. We developed a DFLC mixture with a record-high birefringence (?n=0.39 at ?=633nm) based on phenyl-tolane compounds, which exhibit a positive dielectric anisotropy (??) and modest dielectric relaxation frequency.
In Chapter 3, a phase modulator with 4? phase change and 400 &"181;s average gray-to-gray response time is demonstrated using a sheared polymer network liquid crystal (SPNLC). This device exhibits a low scattering at ?=532 nm due to the employed material set and shearing technique. We also discuss the application of SPNLCs for 3D displays.
In Chapter 4, we studied the temperature effect on the splay elastic constant of polymer network liquid crystal (PNLC). Due to the existence of polymer network, the temperature dependent splay elastic constant of the LC cell deviates from the model for nematic LCs.
In Chapter 5, we focus on PNLC light modulators. This technology is attractive because it can achieve submillisecond response time while maintaining a large phase change. However, the light scattering loss caused by grain boundaries of liquid crystal multi-domains at voltage-on state hinders the widespread application of PNLCs. By optimizing liquid crystal host, polymer, and proper curing process, we successfully eliminate light scattering from short wave infrared region (1.55 ?m) to visible range.
In Chapter 6, we introduce a reconfigurable fabrication technique of tunable liquid crystal devices. Based on this technique and our scattering-free PNLCs, we developed a series of fast switching LC devices such as LC prism, grating and lens. The application of this technology in 3D lenticular lens development is also discussed. This technique provides a great flexibility for designing and fabricating LC photonic devices with desired refractive index profile.Ph.D.
Doctorate
Optics and Photonics
Optics and Photonics
Optics
49
Bishop, Carlton Delos. "Finite impulse response filter design using cosine series functions." Doctoral diss., University of Central Florida, 1988. http://digital.library.ucf.edu/cdm/ref/collection/RTD/id/43377.
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University of Central Florida College of Engineering ThesisWindow functions have been extensively used for the design of SAW filters. The classical truncated cosine series functions, such as the Hamming and Blackmann functions, are only a few of an infinite set of such functions. The derivation of this set of functions from orthonormal basis sets and the criteria for obtaining the constant coefficients of the functions are presented. These functions are very useful because of the closed-form expressions and their easily recognizable Fourier transform. Another approach to the design of Gaussian shaped filters having a desired sidelobe level using a 40 term cosine series will be presented as well. This approach is again non-iterative and a near equi-ripple sidelobe level filter could be achieved. A deconvolution technique will also be presented. this has the advantage of being non-iterative, simple and fast. This design method produces results comparable to the Dolph-Chebyshev technique.
Ph.D.
Doctorate
Electrical Engineering and Communication
Engineering
Electrical Engineering
41 p.
vii, 41 leaves, bound : ill. ; 28 cm.
50
Torres, Candice. "Sex trafficking Florida's response to the international organized crime." Honors in the Major Thesis, University of Central Florida, 2011. http://digital.library.ucf.edu/cdm/ref/collection/ETH/id/521.
Full textAbstract:
Florida has the second-highest incidence of human trafficking in the country. Sex trafficking of women into and out of the state of Florida is defined by various terms from international, national and local terms. The United Nations defines sex trafficking in Article 3, paragraph (a) of the Protocol to Prevent, Suppress and Punish Trafficking in Persons, especially Women and Children, Supplementing the United Nations Convention against Transnational Organized Crime as: "Trafficking in persons: shall mean the recruitment, transportation, transfer, harboring or receipt of persons, by means of the threat or use of force or other forms of coercion, of abduction, of fraud, of deception, of the abuse of power or of a position of vulnerability or of the giving or receiving of payments or benefits to achieve the consent of a person having control over another person, for the purpose of exploitation". This study explores the experiences of women who have been trafficked as well as the recruitment strategies by which women are trafficked and to what extent their life changes. This study aims to understand the extent to which local nonprofits in the state of Florida have tackled the issue as well as the international, federal and state government laws are enforced. The findings will provide useful guidelines to help nonprofits in the state of Florida work together to combat the issue as well as be used as an informative research proposal for the community to push stronger legislation and raise more awareness.B.A.
Bachelors
Sciences
Political Science