Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 158 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: The empirical testing of theories is an important component of research in any field. Yet despite the long history of science, the extent to which theories are supported or contradicted by the results of empirical research remains ill defined. Quite commonly, support or contradiction is based solely on the "reject" or "fail to reject" decisions that result from tests of null hypotheses that are derived from aspects of theory. Decisions and recommendations based on this forced and often artificial dichotomy have been scrutinized in the past. Such an overly simplified approach to theory testing has been vigorously challenged in the past. Theories differ in the extent to which they provide precise predictions about observations. The precision of predictions derived from theories is proportional to the strength of support that may be provided by empirical evidence congruent with the prediction. / ABSTRACT: However, the notion of precision linked to strength of support is surprisingly absent from many discussions regarding the appraisal of theories. In the early 1990s, Meehl presented an index of corroboration to summarize the extent to which empirical tests of theories provide support or contradiction of theories. This index is comprised of a closeness component and an estimate of precision. The purpose of this study was to evaluate the utility of this index of corroboration and its behavior when employing path analytic methods in the context of social science research. The performance of a multivariate extension of Meehl's Corroboration Index (Ci) was evaluated using Monte Carlo methods by simulating traditional path analysis. Five factors were included in the study: model complexity, level of intolerance, verisimilitude, sample size and level of collinearity. Results were evaluated in terms of the mean and standard error of the resulting multivariate Ci values. / ABSTRACT: Of the five central design factors investigated, the level of intolerance was observed to be the strongest influence on mean Ci. Verisimilitude and model complexity were not observed to be strong determinants of the mean Ci. The lack of sensitivity of the index to the other design factors led to a proposed alternative conceptualization of the multivariate corroboration index to guide future research efforts. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 236 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Particulate nitrates play important roles in the atmosphere. They consist mainly of NH4NO3 and NaNO3, products from the reactions of gaseous HNO3 with gaseous NH3 and sea salt, respectively. The gas-to-particle phase conversion of nitrate changes its deposition characteristics and ultimately changes the transport and deposition rates of the locally produced species. Studies were conducted to develop background information on the particle concentrations and size distributions and the chemistry and kinetics behind the interactions. The predominant nitrate species in the Tampa Bay area was identified as coarse mode NaNO3. NH4NO3 was not detected as it has high volatility at ambient temperatures. Spatial distribution sampling determined a gradient of NaCl and NaNO3 with increased distance from the coastal shore and an increase in the gas-to-particle conversion of nitric acid along a predominant air mass trajectory. / ABSTRACT: The EQUISOLV II thermodynamic equilibrium model was evaluated. It was determined that the model can be used to predict gas and size-distributed particulate matter concentrations. The model was also used to examine the gas-to-particle partitioning of nitric acid to nitrate by NaCl and CaCO3. Both sodium and calcium partitioned nitrate to the particle phase. The magnitude of the partitioning was directly dependent on the equilibrium coefficients. The fine mode percentage of the total nitrate was determined using two methods. The results were used to expand the current data set to account for the coarse mode nitrate, and they indicated that particle nitrate accounted for 9% of the total nitrogen deposition flux to Tampa Bay. The formation of particle nitrate was examined using a nitrate accumulation model. / ABSTRACT: Results indicated that the equilibrium time for particles less than 10 um in diameter was significantly less than their atmospheric residence time, with fastest conversion occurring under the highest relative humidity conditions. This information is vital in the development of atmospheric nitrogen dry deposition estimates, which are used to assess water quality and nutrient loading. These data can be used to determine air-monitoring strategies and to develop models that account for the coarse particle nitrogen species. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 145 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: In this dissertation we introduce several novel techniques for performing data mining on web documents which utilize graph representations of document content. Graphs are more robust than typical vector representations as they can model structural information that is usually lost when converting the original web document content to a vector representation. For example, we can capture information such as the location, order and proximity of term occurrence, which is discarded under the standard document vector representation models. Many machine learning methods rely on distance computations, centroid calculations, and other numerical techniques. Thus many of these methods have not been applied to data represented by graphs since no suitable graph-theoretical concepts were previously available. We introduce the novel Graph Hierarchy Construction Algorithm (GHCA), which performs topic-oriented hierarchical clustering of web search results modeled using graphs. / ABSTRACT: The system we created around this new algorithm and its prior version is compared with similar web search clustering systems to gauge its usefulness. An important advantage of this approach over conventional web search systems is that the results are better organized and more easily browsed by users. Next we present extensions to classical machine learning algorithms, such as the k-means clustering algorithm and the k-Nearest Neighbors classification algorithm, which allows the use of graphs as fundamental data items instead of vectors. We perform experiments comparing the performance of the new graph-based methods to the traditional vector-based methods for three web document collections. Our experimental results show an improvement for the graph approaches over the vector approaches for both clustering and classification of web documents. / ABSTRACT: An important advantage of the graph representations we propose is that they allow the computation of graph similarity in polynomial time; usually the determination of graph similarity with the techniques we use is an NP-Complete problem. In fact, there are some cases where the execution time of the graph-oriented approach was faster than the vector approaches. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Title from PDF of title page. / Document formatted into pages; contains 124 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: As technology scales down and CMOS circuits are powered by lower supply voltages, standby leakage current becomes significant. A behavioral level framework for the synthesis of data-paths with low leakage power is presented. There has been minimal work done on the behavioral synthesis of low leakage datapaths. We present a fast architectural simulator for leakage (FASL) to estimate the leakage power dissipated by a system described hierarchically in VHDL. FASL uses a leakage power model embedded into VHDL leafcells. These leafcells are characterized for leakage accurately using HSPICE. We present results which show that FASL measures leakage power significantly faster than HSPICE, with less than a 5% loss in accuracy, compared to HSPICE. We present a comprehensive framework for synthesizing low leakage power data-paths using a parameterized Multi-threshold CMOS (MTCMOS) component library. / ABSTRACT: The component library has been characterized for leakage power and delay as a function of sleep transistor width. We propose four techniques for minimization of leakage power during behavioral synthesis: (1) leakage power management using MTCMOS modules; (2) an allocation and binding algorithm for low leakage based on clique partitioning; (3) selective binding to MTCMOS technology, allowing the designer to have control over the area overhead; and (4) a performance recovery technique based on multi-cycling and introduction of slack, to alleviate the loss in performance attributed to the introduction of MTCMOS modules in the data-path. Finally, we propose two iterative search based techniques, based on Tabu search, to synthesize low leakage data-paths. The first technique searches for low leakage scheduling options. The second technique simultaneously searches for a low leakage schedule and binding. It is shown that the latter technique of unified search is more robust. / ABSTRACT: The quality of results generated bytabu-based technique are superior to those generated by simulated annealing (SA) search technique. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 223 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: This study addresses research reporting practices and protocols by bridging the gap from the theoretical and conceptual debates typically found in the literature with more realistic applications using data from published research. Specifically, the practice of using findings of statistical analysis as the primary, and often only, basis for results and conclusions of research is investigated through computing effect size and confidence intervals and considering how their use might impact the strength of inferences and conclusions reported. Using a sample of published manuscripts from three peer-rviewed journals, central quantitative findings were expressed as dichotomous hypothesis test results, point estimates of effect sizes and confidence intervals. Studies using three different types of statistical analyses were considered for inclusion: t-tests, regression, and Analysis of Variance (ANOVA). / ABSTRACT: The differences in the substantive interpretations of results from these accomplished and published studies were then examined as a function of these different analytical approaches. Both quantitative and qualitative techniques were used to examine the findings. General descriptive statistical techniques were employed to capture the magnitude of studies and analyses that might have different interpretations if althernative methods of reporting findings were used in addition to traditional tests of statistical signficance. Qualitative methods were then used to gain a sense of the impact on the wording used in the research conclusions of these other forms of reporting findings. It was discovered that tests of non-signficant results were more prone to need evidence of effect size than those of significant results. / ABSTRACT: Regardless of tests of signficance, the addition of information from confidence intervals tended to heavily impact the findings resulting from signficance tests. The results were interpreted in terms of improving the reporting practices in applied research. Issues that were noted in this study relevant to the primary focus are discussed in general with implicaitons for future research. Recommendations are made regarding editorial and publishing practices, both for primary researchers and editors. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Professional research project (Au.D.)--University of South Florida, 2003. / Title from PDF of title page. / Document formatted into pages; contains 25 pages. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Understanding speech in background noise is occasionally difficult for normal hearing listeners and is often impossible for the listener with sensorineural hearing loss. The ability to understand speech in noise depends upon multiple factors such as the characteristics of the speech signal, the signal-to-noise ratio, and the listener's degree of hearing impairment. A routine hearing evaluation usually does not provide ample information about a listener's functional communication abilities. The Hearing-in-Noise Test (HINT) developed by The House Ear Institute provides an efficient and reliable method for evaluating an individual's suprathreshold speech understanding ability in quiet and in noise. / ABSTRACT: The purpose of this pilot study was to investigate monaural speech reception thresholds for sentences (RTS) in quiet and in noise using the standardized Hearing-in-Noise Test (HINT). Data was collected from one clinical setting using twenty-five subjects with bilateral normal hearing (WNL) and twenty subjects with bilaterally symmetrical sensorineural hearing loss (SNHL). Subject age ranged from 40 to 65 years. The study results were generally in agreement with the HINT norms. It was concluded that administering the HINT monaurally under headphones could differentiate between normal hearing individuals and individuals with cochlear hearing loss. The SNHL group exhibited higher RTSs than the WNL group in both quiet and in noise. The mean RTS difference between the two groups in quiet was 14.56 dB while the mean RTS difference in noise was only 2.85 dB. Surprisingly, the difference between the two subject groups in quiet was greater than was expected. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 241 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Genetic changes likely occur in wild fish populations as a consequence of interactions with cultured fish, but to what extent do those changes threaten the maintenance of natural genetic diversity and population viability? Following a review and categorization of numerous processes suspected of being agents of post-release genetic change in recipient wild populations (Chapter 1), I focus on risks relating to the magnitude and duration of releases -- but with a twist. That is, I assume that the mean fitness of released, cultured individuals does not differ from that of the recipient natural population. Throughout, attention is devoted to potential post-release changes in inbreeding (NeI) and variance (NeV) effective population sizes -- indicators of expected rates of population-level change in inbreeding and drift variance, respectively. The reductive effect that large-scale releases exert on NeI in recipient populations can be significant. / ABSTRACT: The effect is shown to be a threshold process (Chapter 2) and thus suggestive of an approach for determining risk-adverse stocking (or release) rates. This approach is utilized in Chapter 3, which describes genetic recommendations for an incipient marine stocking program. Several discordant contemporary NeI models are examined mathematically and by computer simulation (Chapter 4). I show that certain published results pertaining to the effect of multiple paternity on NeI are erroneous; a general model is described which accounts for inbreeding and relatedness in and among parents. That model is utilized in an empirical study of gene correlation in a hatchery cohort (Chapter 5). Propagation-related causes of reductions in NeI are also investigated in this cohort. / ABSTRACT: Finally, extending mutational meltdown theory to accommodate fluctuating population sizes and recessive selective effects, I show that when large reductions in NeV occur (such as those that accompany admixtures of cultured and wild fish), the expected time to population inviability is significantly reduced (Chapter 6). Although a more comprehensive theoretical approach is needed, a precautionary inference may be drawn -- aquaculture-induced reductions in Ne, even though they may be transient, can lead to adverse genetic impacts. Avoidance of Ne-reductions cannot be accomplished, in a practical sense, without considering the stocking or release rates of cultured fish. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 173 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: N-Methylthio beta-lactams represent a promising new family of antibacterial agents whose in vitro activity is confined largely to Staphylococcus species, including multidrug-resistant forms of S. aureus. Originally developed in the 1980's for use as synthetic intermediates, N-methylthio beta-lactams have recently been shown in these laboratories to possess intriguing biological properties which are addressed in Chapters I-IV. In terms of the antibacterial activities, the structural features and species specificities exhibited by these compounds are unlike those of any existing family of beta-lactam drugs. The lactams seem to exert their effects intracellularly, requiring passage of the bioactive species through the cellular membrane, rather than acting extracellularly on cell wall components in the manner of penicillin and related antibiotics. / ABSTRACT: The lipophilic nature of these molecules, which lack the polar side chain functionality of all other microbially-active Beta-lactams, suggests the compounds do not target the penicillin binding proteins within bacterial membranes. The most active members of this Beta-lactam class appear to be those bearing an aryl (Ar) substituent at C4 of the ring. The synthesis and structure-activity relationship of these analogues is discussed in Chapter III. Moreover, microscopy and 3H pulse-labeling studies, which are described in Chapter IV, demonstrate that N-methylthio beta-lactams appear to be inhibitors of protein biosynthesis. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 141 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: The factor structure of the work/family conflict scale developed by Carlson, Kacmar, & Williams (2000) was analyzed for measurement invariance between a US and an Australian/New Zealand (ANZ) sample using a multisample confirmatory factor analysis procedure. Results indicated that factor pattern fit between the female samples on the common model was good-to-mediocre, and factor pattern fit between the male samples and the common model was mediocre-to-poor. Both samples exhibited significant changes in chi square when testing for the more restrictive factor loading equivalence. Partial measurement invariance revealed a better fit between the male samples when three of the items were unconstrained, and when eight items were unconstrained between the female samples. Finally, males and females in the ANZ sample exhibited factor pattern invariance, but required two items to be unconstrained before factor loading invariance was achieved. / ABSTRACT: Mean differences on the six scales revealed higher levels of time-based work interference with family and family interference with work for males than for females in the ANZ sample. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.

Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 172 pages. / Thesis (PH.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Modeling methods are required for predicting the chemical stability of macromolecular materials used in critical spacecraft components of satellites orbiting in the high-energy radiation environment of near earth and deep space planetary magnetic belts. Methods for establishing degradation mechanisms and predicting and simulating the total absorbed dose and ionization for long term space missions are presented herein. This investigation evaluates cross-linking, main-chain scission and elimination products in a linear series of narrowly dispersed poly(methyl methacrylate) (PMMA) and polystyrene (PS) polymers. A comparison is made of the scission radiation yield (Gs) and crosslinking (Gx) predicted for the simulated ionization data to the results of degradation in a ground-based simulation of the space radiation environment using a 60Co source. / ABSTRACT: The influence of molecular weight on the stability of post-irradiated polymer is evident in the degree of change observed for each molecular weight series with respect to the degradation products produced by exposure to gamma radiation. The analysis of the specific polymer degradation products and changes in the average molecular weight (Mw) were performed using chemical analysis (FTIR and GPC) and thermal analysis (DSC). The analytical results for PMMA and polystyrene radiation-induced degradation products demonstrate that, depending on Mw, the amount and types of degradation products will vary with respect to crosslinking, chain scission and other oxidative pathways. The results support the preference for end group loss with free volume properties driving the observed differences in the G(s) and (Gx) values. / ABSTRACT: The cross-linking observed for polystyrene is controlled by molecular weight as well wherein the lowest molecular weight molecules display greater resistance to cross-linking. This research investigation employs proven tools of analysis (NASA AP8 and AE8) that accurately predict the amount of energy applied to spacecraft materials during a typical near-earth, aggressive mission environment . Another model (SPENVIS) is applied to determine the amount of total energy absorbed by the spacecraft materials from proton, electron and Brehmsstralung radiation throughout the mission life. Another set of models (SRIM and CASINO) are used to asses the range of penetration of particles into the materials and the extent of ionization caused by the particle spectrum and fluence. The absorption coefficients for the PS and PMMA structure are determined to ensure good correlation between ground simulation and the true space environment. / ABSTRACT: The total dose values are used to establish the total dose that is to be deposited during the ground simulation experiments. A 60Co irradiator was used as the ground simulation source. Dosimetry was used to determine the exposure time needed to deposit an equivalent amount of dose accumulation needed to simulate the total dose modeled for the space mission. Using gel permeation chromatography, previous studies have demonstrated that the characteristic Gaussian distribution of narrowly-dispersed PS and PMMA is perturbed by the accumulation of degradation products following irradiation. The change in distribution provides insight into the preferred path of degradation. The role of free volume in the glass transition temperature are reported with respect to Tg variation with molecular weight. Using differential scanning calorimetry. / ABSTRACT: The role of free volume in the determination of the mechanism of radiation-induced degradation is a primary focus of this investigation when considering the ability of the main chain to recombine or undergo abstraction as opposed to crosslinking or scission where motion is restricted in the solid state. The subtle distinction of structural changes brought about by the loss of side groups, double bond formation and crosslinking have been characterized by infrared spectroscopy. The resultant spectra of irradiated polymers offer considerable information on verifying the extent of competing reactions that involve structural features of the molecule. These instrumental methods are the tools of research that will assess the affect of molecular structure on polymer radiation resistance, and will support the rationale explaining the preference for one degradation mechanism over another. / ABSTRACT: This research investigation has yielded information on the affect of polymer molecular structure on radiation resistance. The work goes beyond previous studies that define empirical observations for a change in radiation resistance by virtue of a change in side group. The effect of free volume, stabilized intermediates and reactive intermediates are related to molecular weight and side group functionality. The understanding of the mechanistic rationale behind the effect of structural features on polymer radiation resistance are essential to the development of modeling systems for predicting polymer stability in space mission environments. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.