Dynamic data retrieval on the World Wide Web

Methods for accessing data on the Web have been the focus of active research over the past few years. In this thesis we propose a method for representing Web sites as data sources. We designed a Data Extractor data retrieval solution that allows us to define queries to Web sites and process resulting data sets. Data Extractor is being integrated into the MSemODB heterogeneous database management system. With its help database queries can be distributed over both local and Web data sources within MSemODB framework. ^ Data Extractor treats Web sites as data sources, controlling query execution and data retrieval. It works as an intermediary between the applications and the sites. Data Extractor utilizes a twofold “custom wrapper” approach for information retrieval. Wrappers for the majority of sites are easily built using a powerful and expressive scripting language, while complex cases are processed using Java-based wrappers that utilize specially designed library of data retrieval, parsing and Web access routines. In addition to wrapper development we thoroughly investigate issues associated with Web site selection, analysis and processing. ^ Data Extractor is designed to act as a data retrieval server, as well as an embedded data retrieval solution. We also use it to create mobile agents that are shipped over the Internet to the client's computer to perform data retrieval on behalf of the user. This approach allows Data Extractor to distribute and scale well. ^ This study confirms feasibility of building custom wrappers for Web sites. This approach provides accuracy of data retrieval, and power and flexibility in handling of complex cases. ^

Selecting a college or university: A study of students and their parents

This case study investigated the decision-making process of high-achieving high school students and their parents in selecting a college or university. The conceptual framework that guided this study included theoretical and empirical research framed around a three-phase model of college choice. Parental influence dominated the first phase of this model. The search phase, which was the second and the most crucial one, included financial considerations related to this decision, admissions considerations during the search phase, the psychology of decision making, and advertising strategies for teenagers. Once students completed the search phase they developed expectations of the institutions they considered prior to making the final decision. The study employed qualitative methods using individual interviews with students and their parents. ^ Six high-achieving high school seniors from a South Florida high school and their parents were selected to participate in this study. Of these students, four were female and two were male. Participants were individually interviewed on two separate occasions over a three-month period. Students and their parents were interviewed separately, with one exception, during the first set of interviews and together during the second. The data obtained from these interviews were transcribed and these transcripts were coded, categorized, analyzed, and sorted into major themes and submitted to interpretive analysis. ^ In-depth descriptions of participants' experiences during the decision-making process are described in the study. Financial factors—which included the cost of college, the socio-economic status of the family, and scholarship possibilities—drove the selection process for these students and their parents, most of whom reported their family incomes between the lower-middle to upper-middle class range. All of these students took advantage of the Bright Futures Scholarship Program, other scholarship opportunities, and the lower tuition costs of in-state public institutions. The effectiveness of recruitment techniques, such as brochures, campus visits, the development of college Web sites, and the overall impact of Internet resources, was assessed by the researcher. ^ As these students had progressed through the search phase, they developed perceptions of potential institutions as they were assisted by those around them. The value of familiarity with institutions and the use of heuristics were quite evident in the final analysis of this study, based on what the students communicated about how their knowledge of and comfort in these institutions affected their decisions. Parental influence played an important role in the selection process for the students in this study as the parents clearly directed the process, by the constant advice they gave their children and by the financial limitations they communicated to them. ^

Defining the role of floating periphyton mats in shaping food-web dynamics in the Florida Everglades

Expansive periphyton mats are a striking characteristic of the Florida Everglades. Floating periphyton mats are home to a diverse macroinvertebrate community dominated by chironomid and ceratopogonid larvae and amphipods that use the mat as both a food resource and refuge from predation. While this periphyton complex functions as a self-organizing system, it also serves as a base for trophic interactions with larger organisms. The purpose of my research was to quantify variation in the macroinvertebrate community inhabiting floating periphyton mats, describe the role of mats in shaping food-web dynamics, and describe how these trophic interactions change with eutrophication. ^ I characterized the macroinvertebrate community inhabiting periphyton through a wet-season by describing spatial variation on scales from 0.2 m to 3 km. Floating periphyton mats contained a diverse macroinvertebrate community, with greater taxonomic richness and higher densities of many taxa than adjacent microhabitats. Macroinvertebrate density increased through the wet season as periphyton mats developed. While some variation was noted among sites, spatial patterns were not observed on smaller scales. I also sampled ten sites representing gradients of hydroperiod and nutrient (P) levels. The density of macroinvertebrates inhabiting periphyton mats increased with increasing P availability; however, short-hydroperiod P-enriched sites had the highest macroinvertebrate density. This pattern suggests a synergistic interaction of top-down and bottom-up effects. In contrast, macroinvertebrate density was lower in benthic floc, where it was negatively correlated with hydroperiod. ^ I used two types of mesocosms (field cages and tanks) to manipulate large consumers (fish and grass shrimp) with inclusion/exclusion cages over an experimental P gradient. In most cases, periphyton mats served as an effective predation refuge. Macroinvertebrates were consumed more frequently in P-enriched treatments, where mats were also heavily grazed. Macroinvertebrate densities decreased with increasing P in benthic floc, but increased with enrichment in periphyton mats until levels were reached that caused disassociation of the mat. ^ This research documents several indirect trophic interactions that can occur in complex habitats, and emphasizes the need to characterize dynamics of all microhabitats to fully describe the dynamics of an ecosystem. ^

Hydrological dynamics between a coastal aquifer and the adjacent estuarine system, Biscayne Bay, South Florida

Geochemical and geophysical approaches have been used to investigate the freshwater and saltwater dynamics in the coastal Biscayne Aquifer and Biscayne Bay. Stable isotopes of oxygen and hydrogen, and concentrations of Sr2+ and Ca2+ were combined in two geochemical mixing models to provide estimates of the various freshwater inputs (precipitation, canal water, and groundwater) to Biscayne Bay and the coastal canal system in South Florida. Shallow geophysical electromagnetic and direct current resistivity surveys were used to image the geometry and stratification of the saltwater mixing zone in the near coastal (less than 1km inland) Biscayne Aquifer. The combined stable isotope and trace metal models suggest a ratio of canal input-precipitation-groundwater of 38%–52%–10% in the wet season and 37%–58%–5% in the dry season with an error of 25%, where most (20%) of the error was attributed to the isotope regression model, while the remaining 5% error was attributed to the Sr2+/Ca2+ mixing model. These models suggest rainfall is the dominate source of freshwater to Biscayne Bay. For a bay-wide water budget that includes saltwater and freshwater mixing, fresh groundwater accounts for less than 2% of the total input. A similar Sr 2+/Ca2+ tracer model indicates precipitation is the dominate source in 9 out of 10 canals that discharge into Biscayne Bay. The two-component mixing model converged for 100% of the freshwater canal samples in this study with 63% of the water contributed to the canals coming from precipitation and 37% from groundwater inputs ±4%. There was a seasonal shift from 63% precipitation input in the dry season to 55% precipitation input in the wet season. The three end-member mixing model converged for only 60% of the saline canal samples possibly due to non-conservative behavior of Sr2+ and Ca2+ in saline groundwater discharging into the canal system. Electromagnetic and Direct Current resistivity surveys were successful at locating and estimating the geometry and depth of the freshwater/saltwater interface in the Biscayne Aquifer at two near coastal sites. A saltwater interface that deepened as the survey moved inland was detected with a maximum interpreted depth to the interface of 15 meters, approximately 0.33 km inland from the shoreline. ^

Habitat use and foraging ecology of a batoid community in Shark Bay, Western Australia

Worldwide declines in populations of large elasmobranchs and the potential cascading effects on marine ecosystems have garnered considerable attention. Far less appreciated are the potential ecological impacts of changes in abundances of small to medium bodied elasmobranchs mesopredators. Crucial to elucidating the role of these elasmobranchs is an understanding of their habitat use and foraging ecology in pristine conditions. I investigated the trophic interactions and factors driving spatiotemporal variation in abundances of elasmobranch mesopredators in the relatively pristine ecosystem of Shark Bay, Australia. First, I describe the species composition and seasonal habitat use patterns of elasmobranch mesopredator on the sandflats of Shark Bay. Juvenile batoids dominated this diverse community and were extremely abundant in nearshore microhabitats during the warm season. Stomach content analysis and stable isotopic analysis revealed that there is a large degree of dietary overlap between common batoid species. Crustaceans, which tend to be found in seagrass habitats, dominated diets. Despite isotopic differences between many species, overlap in isotopic niche space was high and there was some degree of individual specialization. I then, investigated the importance of abiotic (temperature and water depth) and biotic (prey and predator abundance) factors in shaping batoid habitat use. Batoids were most abundant and tended to rest in shallow nearshore waters when temperatures were high. This pattern coincides with periods of large shark abundance suggesting batoids were seeking refuge from predators rather than selecting optimal temperatures. Finally, I used acoustic telemetry to examine batoid residency and diel use of the sandflats. Individual batoids were present on the sandflats during both the warm and cold seasons and throughout the diel cycle, suggesting lower sandflat densities during the cold season were a result of habitat shifts rather than migration out of Shark Bay. Combined, habitat use and dietary results suggest that batoids have the potential to seasonally impact sandflat dynamics through their presence, although foraging may be limited on the sandflats. Interestingly, my results suggest that elasmobranch mesopredators in pristine ecosystems probably are not regulated by food supply and their habitat use patterns and perhaps ecosystem impacts may be influenced by their predators.

A large-scale dynamic vector and raster data visualization geographic information system based on parallel map tiling

With the exponential increasing demands and uses of GIS data visualization system, such as urban planning, environment and climate change monitoring, weather simulation, hydrographic gauge and so forth, the geospatial vector and raster data visualization research, application and technology has become prevalent. However, we observe that current web GIS techniques are merely suitable for static vector and raster data where no dynamic overlaying layers. While it is desirable to enable visual explorations of large-scale dynamic vector and raster geospatial data in a web environment, improving the performance between backend datasets and the vector and raster applications remains a challenging technical issue. This dissertation is to implement these challenging and unimplemented areas: how to provide a large-scale dynamic vector and raster data visualization service with dynamic overlaying layers accessible from various client devices through a standard web browser, and how to make the large-scale dynamic vector and raster data visualization service as rapid as the static one. To accomplish these, a large-scale dynamic vector and raster data visualization geographic information system based on parallel map tiling and a comprehensive performance improvement solution are proposed, designed and implemented. They include: the quadtree-based indexing and parallel map tiling, the Legend String, the vector data visualization with dynamic layers overlaying, the vector data time series visualization, the algorithm of vector data rendering, the algorithm of raster data re-projection, the algorithm for elimination of superfluous level of detail, the algorithm for vector data gridding and re-grouping and the cluster servers side vector and raster data caching.

Applying stable isotopes to examine food-web structure: an overview of analytical tools

Stable isotope analysis has emerged as one of the primary means for examining the structure and dynamics of food webs, and numerous analytical approaches are now commonly used in the field. Techniques range from simple, qualitative inferences based on the isotopic niche, to Bayesian mixing models that can be used to characterize food-web structure at multiple hierarchical levels. We provide a comprehensive review of these techniques, and thus a single reference source to help identify the most useful approaches to apply to a given data set. We structure the review around four general questions: (1) what is the trophic position of an organism in a food web?; (2) which resource pools support consumers?; (3) what additional information does relative position of consumers in isotopic space reveal about food-web structure?; and (4) what is the degree of trophic variability at the intrapopulation level? For each general question, we detail different approaches that have been applied, discussing the strengths and weaknesses of each. We conclude with a set of suggestions that transcend individual analytical approaches, and provide guidance for future applications in the field.

Biotic and abiotic determinants of intermediate-consumer trophic diversity in the Florida everglades

Food-web structure can shape population dynamics and ecosystem functioning and stability. We investigated the structure of a food-web fragment consisting of dominant intermediate consumers (fishes and crayfishes) in the Florida Everglades, using stable isotope analysis to quantify trophic diversity along gradients of primary production (periphyton), disturbance (marsh drying) and intermediate-consumer density (a possible indicator of competition). We predicted that trophic diversity would increase with resource availability and decrease after disturbance, and that competition could result in greater trophic diversity by favouring resource partitioning. Total trophic diversity, measured by niche area, decreased with periphyton biomass and an ordination axis representing several bluegreen algae species. Consumers’ basal resource diversity, estimated by δ13C values, was similarly related to algal community structure. The range of trophic levels (δ15N range) increased with time since the most recent drying and reflooding event, but decreased with intermediate-consumer density, and was positively related to the ordination axis reflecting increases in green algae and decreases in filamentous bluegreen algae. Our findings suggest that algal quality, independent of quantity, influences food-web structure and demonstrate an indirect role of nutrient enrichment mediated by its effects on periphyton palatability and biomass. These results reveal potential mechanisms for anthropogenic effects on Everglades communities.

Hypertension, poor glycemic control, and microalbuminuria in Cuban Americans with type 2 diabetes

Purpose: To investigate to what degree the presence of hypertension (HTN) and poor glycemic control (GC) influences the likelihood of having microalbuminuria (MAU) among Cuban Americans with type 2 diabetes (T2D).Methods: A cross-sectional study conducted in Cuban Americans (n = 179) with T2D. Participants were recruited from a randomly generated mailing list purchased from KnowledgeBase Marketing, Inc. Blood pressure (BP) was measured twice and averaged using an adult size cuff. Glycosylated hemoglobin (A1c) levels were measured from whole blood samples with the Roche Tina-quant method. First morning urine samples were collected from each participant to determine MAU by a semiquantitative assay (ImmunoDip).Results: MAU was present in 26% of Cuban Americans with T2D. A significantly higher percentage of subjects with MA had HTN (P = 0.038) and elevated A1C (P = 0.002) than those with normoalbuminuria. Logistic regression analysis showed that after controlling for covariates, subjects with poor GC were 6.76 times more likely to have MAU if they had hypertension compared with those without hypertension (P = 0.004; 95% confidence interval [CI]: 1.83, 23.05). Conclusion: The clinical significance of these findings emphasizes the early detection of MAU in this Hispanic subgroup combined with BP and good GC, which are fundamentals in preventing and treating diabetes complications and improving individuals’ renal and cardiovascular outcomes.

Exploratory Study of the Download Speed of Leading University Hospitality and Tourism Department Websites Worldwide

Increased broadband penetration (BP) rates around the world have encouraged web designers to include more web content and additional functions on their web sites, thereby enhancing the richness and playfulness of the information. However, it is often very difficult for web surfers who are still using narrowband connections to access such web sites. Many university web sites target international audiences; therefore their download performance should be considered, as it may directly influence the user experience. This exploratory study examined 331 university hospitality and tourism department web sites in 37 countries. The empirical results showed that entry web pages of universities in Asia, with a medium BP rate (mid-BP), have the slowest download speeds, and those in Australia and New Zealand perform the best. The adoption rate of the Cascade Style Sheet (CSS) in Asia is relatively lower than that of other regions.

Relationships between gifted selection criteria and performance in sixth -grade gifted science

This study examined the relationships between gifted selection criteria used in the Dade County Public Schools of Miami, Florida and performance in sixth grade gifted science classes.^ The goal of the study was to identify significant predictors of performance in sixth grade gifted science classes. Group comparisons of performance were also made. Performance in sixth grade gifted science was defined as the numeric average of nine weeks' grades earned in sixth grade gifted science classes.^ The sample consisted of 100 subjects who were formerly enrolled in sixth grade gifted science classes over two years at a large, multiethnic public middle school in Dade County.^ The predictors analyzed were I.Q. score (all scales combined), full scale I.Q. score, verbal scale I.Q. score, performance scale I.Q. score, combined Stanford Achievement Test (SAT) score (Reading Comprehension plus Math Applications), SAT Reading Comprehension score, and SAT Math Applications score. Combined SAT score and SAT Math Applications score were significantly positively correlated to performance in sixth grade gifted science. Performance scale I.Q. score was significantly negatively correlated to performance in sixth grade gifted science. The other predictors examined were not significantly correlated to performance.^ Group comparison results showed the mean average of nine weeks grades for the full scale I.Q. group was greater than the verbal and performance scale I.Q. groups. Females outperformed males to a highly significant level. Mean g.p.a. for ethnic groups was greatest for Asian students, followed by white non-Hispanic, Hispanic, and black. Students not receiving a lunch subsidy outperformed those receiving subsidies.^ Comparisons of performance based on gifted qualification plan showed the mean g.p.a. for traditional plan and Plan B groups were not different. Mean g.p.a. for students who qualified for gifted using automatic Math Applications criteria was highest, followed by automatic Reading Comprehension criteria and Plan B Matrix score. Both automatic qualification groups outperformed the traditional group. The traditional group outperformed the Plan B Matrix group. No significant differences in mean g.p.a. between the Plan B subgroups and the traditional plan group were found. ^

Un -equal opportunity: Sex and school among first and second generation Mexican immigrant adolescent girls

The purpose of this dissertation was to determine the interactions of sexuality and education among low socioeconomic status first and second generation Mexican immigrant adolescent girls. Much of the existing research differentiates between immigrant generations with little examination of the differences within a particular immigrant generation. This study utilized qualitative methods to examine how various social institutions intersected to influence the young women's decisions about education and sexuality. The methodology included more than three years of participant observation in a South Florida high school and surrounding community; structured and unstructured interviews with twenty young women, their family members, school personnel, and community activists; and surveys conducted with the young women and their parent or guardian. ^ Moving beyond the limits of essentialist immigration theories, this project revealed within group (i.e. immigrant generation) complexities as well as between group similarities. The data included in this dissertation delineate how relationships of power and control permeated the lives of first and second generation Mexican immigrant adolescent girls. The lens of this dissertation is focused on the salient issues of sexuality and education: two dominant forces in many adolescent lives. ^ I found the young women represented a variety of positions on the academic orientation and sexuality continuums and engaged in activities that both reinforced and countered their stated positions on each of these issues. Specifically, first and second generation immigrants are often viewed as maintaining opposing viewpoints about both education and female sexuality however, for these young women the within group variation was larger than the between group variation. While all the young women in this study expressed a belief in the value of education, they engaged in activities that both fortified and contradicted that expressed position. Additionally, although acculturation can lead to increased sexual activity and decreased engagement with education, the first generation immigrant young women in this study became pregnant and/or withdrew from school in equal proportions to their second generation counterparts. In summary, structural forces combined, often inadvertently, and contributed to these young women's spiraling negative academic orientation and/or rational choice of motherhood. Finally, the findings are linked to policy implications. ^

Slow Isotope Turnover Rates and Low Discrimination Values in the American Alligator: Implications for Interpretation of Ectotherm Stable Isotope Data

Stable isotope analysis has become a standard ecological tool for elucidating feeding relationships of organisms and determining food web structure and connectivity. There remain important questions concerning rates at which stable isotope values are incorporated into tissues (turnover rates) and the change in isotope value between a tissue and a food source (discrimination values). These gaps in our understanding necessitate experimental studies to adequately interpret field data. Tissue turnover rates and discrimination values vary among species and have been investigated in a broad array of taxa. However, little attention has been paid to ectothermic top predators in this regard. We quantified the turnover rates and discrimination values for three tissues (scutes, red blood cells, and plasma) in American alligators (Alligator mississippiensis). Plasma turned over faster than scutes or red blood cells, but turnover rates of all three tissues were very slow in comparison to those in endothermic species. Alligator δ15N discrimination values were surprisingly low in comparison to those of other top predators and varied between experimental and control alligators. The variability of δ15N discrimination values highlights the difficulties in using δ15N to assign absolute and possibly even relative trophic levels in field studies. Our results suggest that interpreting stable isotope data based on parameter estimates from other species can be problematic and that large ectothermic tetrapod tissues may be characterized by unique stable isotope dynamics relative to species occupying lower trophic levels and endothermic tetrapods.

Public perception of carbon capture and storage in relation to hydraulic fracturing: content analyses, survey results, and policy proposals

Carbon capture and storage (CCS) can contribute significantly to addressing the global greenhouse gas (GHG) emissions problem. Despite widespread political support, CCS remains unknown to the general public. Public perception researchers have found that, when asked, the public is relatively unfamiliar with CCS yet many individuals voice specific safety concerns regarding the technology. We believe this leads many stakeholders conflate CCS with the better-known and more visible technology hydraulic fracturing (fracking). We support this with content analysis of media coverage, web analytics, and public lobbying records. Furthermore, we present results from a survey of United States residents. This first-of-its-kind survey assessed participants’ knowledge, opinions and support of CCS and fracking technologies. The survey showed that participants had more knowledge of fracking than CCS, and that knowledge of fracking made participants less willing to support CCS projects. Additionally, it showed that participants viewed the two technologies as having similar risks and similar risk intensities. In the CCS stakeholder literature, judgment and decision-making (JDM) frameworks are noticeably absent, and public perception is not discussed using any cognitive biases as a way of understanding or explaining irrational decisions, yet these survey results show evidence of both anchoring bias and the ambiguity effect. Public acceptance of CCS is essential for a national low-carbon future plan. In conclusion, we propose changes in communications and incentives as programs to increase support of CCS.

Movement Effects on the Flow Physics and Nutrient Delivery in Engineered Valvular Tissues

Mechanical conditioning has been shown to promote tissue formation in a wide variety of tissue engineering efforts. However the underlying mechanisms by which external mechanical stimuli regulate cells and tissues are not known. This is particularly relevant in the area of heart valve tissue engineering (HVTE) owing to the intense hemodynamic environments that surround native valves. Some studies suggest that oscillatory shear stress (OSS) caused by steady flow and scaffold flexure play a critical role in engineered tissue formation derived from bone marrow derived stem cells (BMSCs). In addition, scaffold flexure may enhance nutrient (e.g. oxygen, glucose) transport. In this study, we computationally quantified the i) magnitude of fluid-induced shear stresses; ii) the extent of temporal fluid oscillations in the flow field using the oscillatory shear index (OSI) parameter, and iii) glucose and oxygen mass transport profiles. Noting that sample cyclic flexure induces a high degree of oscillatory shear stress (OSS), we incorporated moving boundary computational fluid dynamic simulations of samples housed within a bioreactor to consider the effects of: 1) no flow, no flexure (control group), 2) steady flow-alone, 3) cyclic flexure-alone and 4) combined steady flow and cyclic flexure environments. We also coupled a diffusion and convention mass transport equation to the simulated system. We found that the coexistence of both OSS and appreciable shear stress magnitudes, described by the newly introduced parameter OSI-t , explained the high levels of engineered collagen previously observed from combining cyclic flexure and steady flow states. On the other hand, each of these metrics on its own showed no association. This finding suggests that cyclic flexure and steady flow synergistically promote engineered heart valve tissue production via OSS, so long as the oscillations are accompanied by a critical magnitude of shear stress. In addition, our simulations showed that mass transport of glucose and oxygen is enhanced by sample movement at low sample porosities, but did not play a role in highly porous scaffolds. Preliminary in-house in vitro experiments showed that cell proliferation and phenotype is enhanced in OSI-t environments.