Development of a mathematical and computer model to assess water quality impacts of hazardous compounds from minor gasoline spills in the inter-tidal zone of the Miami River, Florida

The objective of this study was to develop a model to predict transport and fate of gasoline components of environmental concern in the Miami River by mathematically simulating the movement of dissolved benzene, toluene, xylene (BTX), and methyl-tertiary-butyl ether (MTBE) occurring from minor gasoline spills in the inter-tidal zone of the river. Computer codes were based on mathematical algorithms that acknowledge the role of advective and dispersive physical phenomena along the river and prevailing phase transformations of BTX and MTBE. Phase transformations included volatilization and settling. ^ The model used a finite-difference scheme of steady-state conditions, with a set of numerical equations that was solved by two numerical methods: Gauss-Seidel and Jacobi iterations. A numerical validation process was conducted by comparing the results from both methods with analytical and numerical reference solutions. Since similar trends were achieved after the numerical validation process, it was concluded that the computer codes algorithmically were correct. The Gauss-Seidel iteration yielded at a faster convergence rate than the Jacobi iteration. Hence, the mathematical code was selected to further develop the computer program and software. The model was then analyzed for its sensitivity. It was found that the model was very sensitive to wind speed but not to sediment settling velocity. ^ A computer software was developed with the model code embedded. The software was provided with two major user-friendly visualized forms, one to interface with the database files and the other to execute and present the graphical and tabulated results. For all predicted concentrations of BTX and MTBE, the maximum concentrations were over an order of magnitude lower than current drinking water standards. It should be pointed out, however, that smaller concentrations than the latter reported standards and values, although not harmful to humans, may be very harmful to organisms of the trophic levels of the Miami River ecosystem and associated waters. This computer model can be used for the rapid assessment and management of the effects of minor gasoline spills on inter-tidal riverine water quality. ^

Variables affecting government debt: A comparison of certificates of participation, tax -exempt revenue bonds and tax -exempt general obligation bonds

This dissertation analyzed and compared variables affecting interest rate and yield of certificates of participation, tax-exempt revenue bonds and tax-exempt general obligation bonds. The study employed qualitative and quantitative analysis methods. ^ Qualitative research methods included surveys, interviews and focus groups. The survey solicited debt load information from 67 Florida school districts (21 responded) and addressed the question which districts used certificates of participation and why. Eight individuals with experience dealing with all three debt instruments were interviewed. A follow-up focus group of six school district financial officers gathered additional data. Results from the qualitative methods revealed school districts used certificates of participation based on millage authority amount available relative to overall tax base. Also identified was the belief of a significant difference in certificates of participation costs and the other two debt instrument types. ^ The study's quantitative methods analyzed 1998 and 1999 initial issues of Moody's AAA rated certificates of participation, tax-exempt revenue bonds and tax-exempt general obligation bonds. Through an analysis of covariance (ANCOVA), the study examined interest rates and yields while controlling for the covariates of credit enhancement, issue size, and maturity date. The analysis identified no significant difference between interest rates of certificates of participation and tax-exempt general obligation bonds (p < 0.05). There was a significant difference between interest rates of tax-exempt revenue bonds and tax-exempt general obligation bonds. This study discerned no significant difference between yield on certificates of participation and tax-exempt general obligation bonds. It identified a difference in yield between both certificates of participation and tax-exempt general obligation bonds compared with tax-exempt revenue bonds. ^ The study found COPs to have lesser overall costs than RV bonds. COPs also have a quicker entry into the market resulting in construction cost savings. The study found policy implications such as investment portfolio limitations and public choice issues about using COPs as a mechanism to grow government. ^

Evaluation of the internal structural validity of the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) anxiety disorders in children and adolescents

The purpose of the present dissertation was to evaluate the internal validity of symptoms of four common anxiety disorders included in the Diagnostic and Statistical Manual of Mental Disorders fourth edition (text revision) (DSM-IV-TR; American Psychiatric Association, 2000), namely, separation anxiety disorder (SAD), social phobia (SOP), specific phobia (SP), and generalized anxiety disorder (GAD), in a sample of 625 youth (ages 6 to 17 years) referred to an anxiety disorders clinic and 479 parents. Confirmatory factor analyses (CFAs) were conducted on the dichotomous items of the SAD, SOP, SP, and GAD sections of the youth and parent versions of the Anxiety Disorders Interview Schedule for DSM-IV (ADIS-IV: C/P; Silverman & Albano, 1996) to test and compare a number of factor models including a factor model based on the DSM. Contrary to predictions, findings from CFAs showed that a correlated model with five factors of SAD, SOP, SP, GAD worry, and GAD somatic distress, provided the best fit of the youth data as well as the parent data. Multiple group CFAs supported the metric invariance of the correlated five factor model across boys and girls. Thus, the present study’s finding supports the internal validity of DSM-IV SAD, SOP, and SP, but raises doubt regarding the internal validity of GAD.^

The thermodynamics and statistical mechanics of protein folding

The physics of self-organization and complexity is manifested on a variety of biological scales, from large ecosystems to the molecular level. Protein molecules exhibit characteristics of complex systems in terms of their structure, dynamics, and function. Proteins have the extraordinary ability to fold to a specific functional three-dimensional shape, starting from a random coil, in a biologically relevant time. How they accomplish this is one of the secrets of life. In this work, theoretical research into understanding this remarkable behavior is discussed. Thermodynamic and statistical mechanical tools are used in order to investigate the protein folding dynamics and stability. Theoretical analyses of the results from computer simulation of the dynamics of a four-helix bundle show that the excluded volume entropic effects are very important in protein dynamics and crucial for protein stability. The dramatic effects of changing the size of sidechains imply that a strategic placement of amino acid residues with a particular size may be an important consideration in protein engineering. Another investigation deals with modeling protein structural transitions as a phase transition. Using finite size scaling theory, the nature of unfolding transition of a four-helix bundle protein was investigated and critical exponents for the transition were calculated for various hydrophobic strengths in the core. It is found that the order of the transition changes from first to higher order as the strength of the hydrophobic interaction in the core region is significantly increased. Finally, a detailed kinetic and thermodynamic analysis was carried out in a model two-helix bundle. The connection between the structural free-energy landscape and folding kinetics was quantified. I show how simple protein engineering, by changing the hydropathy of a small number of amino acids, can enhance protein folding by significantly changing the free energy landscape so that kinetic traps are removed. The results have general applicability in protein engineering as well as understanding the underlying physical mechanisms of protein folding. ^

GIS-integrated mathematical modeling of social phenomena at macro- and micro- levels—a multivariate geographically-weighted regression model for identifying locations vulnerable to hosting terrorist safe-houses: France as case study

Adaptability and invisibility are hallmarks of modern terrorism, and keeping pace with its dynamic nature presents a serious challenge for societies throughout the world. Innovations in computer science have incorporated applied mathematics to develop a wide array of predictive models to support the variety of approaches to counterterrorism. Predictive models are usually designed to forecast the location of attacks. Although this may protect individual structures or locations, it does not reduce the threat—it merely changes the target. While predictive models dedicated to events or social relationships receive much attention where the mathematical and social science communities intersect, models dedicated to terrorist locations such as safe-houses (rather than their targets or training sites) are rare and possibly nonexistent. At the time of this research, there were no publically available models designed to predict locations where violent extremists are likely to reside. This research uses France as a case study to present a complex systems model that incorporates multiple quantitative, qualitative and geospatial variables that differ in terms of scale, weight, and type. Though many of these variables are recognized by specialists in security studies, there remains controversy with respect to their relative importance, degree of interaction, and interdependence. Additionally, some of the variables proposed in this research are not generally recognized as drivers, yet they warrant examination based on their potential role within a complex system. This research tested multiple regression models and determined that geographically-weighted regression analysis produced the most accurate result to accommodate non-stationary coefficient behavior, demonstrating that geographic variables are critical to understanding and predicting the phenomenon of terrorism. This dissertation presents a flexible prototypical model that can be refined and applied to other regions to inform stakeholders such as policy-makers and law enforcement in their efforts to improve national security and enhance quality-of-life.

An assessment of computer usage within the Bahamian public school system and recommended guidelines towards the development of a strategic national computer plan

Computers have dramatically changed the way we live, conduct business, and deliver education. They have infiltrated the Bahamian public school system to the extent that many educators now feel the need for a national plan. The development of such a plan is a challenging undertaking, especially in developing countries where physical, financial, and human resources are scarce. This study assessed the situation with regard to computers within the Bahamian public school system, and provided recommended guidelines to the Bahamian government based on the results of a survey, the body of knowledge about trends in computer usage in schools, and the country's needs. ^ This was a descriptive study for which an extensive review of literature in areas of computer hardware, software, teacher training, research, curriculum, support services and local context variables was undertaken. One objective of the study was to establish what should or could be relative to the state-of-the-art in educational computing. A survey was conducted involving 201 teachers and 51 school administrators from 60 randomly selected Bahamian public schools. A random stratified cluster sampling technique was used. ^ This study used both quantitative and qualitative research methodologies. Quantitative methods were used to summarize the data about numbers and types of computers, categories of software available, peripheral equipment, and related topics through the use of forced-choice questions in a survey instrument. Results of these were displayed in tables and charts. Qualitative methods, data synthesis and content analysis, were used to analyze the non-numeric data obtained from open-ended questions on teachers' and school administrators' questionnaires, such as those regarding teachers' perceptions and attitudes about computers and their use in classrooms. Also, interpretative methodologies were used to analyze the qualitative results of several interviews conducted with senior public school system's officials. Content analysis was used to gather data from the literature on topics pertaining to the study. ^ Based on the literature review and the data gathered for this study a number of recommendations are presented. These recommendations may be used by the government of the Commonwealth of The Bahamas to establish policies with regard to the use of computers within the public school system. ^

In God we trust: Faith-based development, spiritual transformation, and economic change in southern Andean indigenous communities

In communities throughout the developing world, faith-based organizations (FBOs) focus on goals such as eradicating poverty, bolstering local economies, and fostering community development, while premising their activities and interaction with local communities on theological and religious understandings. Due to their pervasive interaction with participants, the religious ideologies of these FBOs impact the religious, economic, and social realities of communities. This study investigates the relationship between the international FBO, World Vision International (WVI), and changes to religious, economic, and social ideologies and practices in Andean indigenous communities in southern Peruvian. This study aims to contribute to the greater knowledge and understanding of (1) institutionalized development strategies, (2) faith-based development, and (3) how institutionalized development interacts with processes of socio-cultural change. Based on fifteen months of field research, this study involved qualitative and quantitative methods of participant-observation, interviews, surveys, and document analysis. Data were primarily collected from households from a sample of eight communities in the Pitumarca and Combapata districts, department of Canchis, province of Cusco, Peru where two WVI Area Development Programs were operating. Research findings reveal that there is a relationship between WVI’s intervention and some changes to religious, economic, and social structure (values, ideologies, and norms) and practices, demonstrating that structure and practices change when social systems are altered by new social actors. Findings also revealed that the impacts of WVI’s intervention greatly increased over the course of several years, demonstrating that changes in structure and practice occur gradually and need a period of time to take root. Finally, results showed that the impacts of WVI’s intervention were primarily limited to those most closely involved with the organization, revealing that the ability of one social actor to incite changes in the structure and practice of another actor is associated with the intensity of the relationship between the social actors. The findings of this study should be useful in ascertaining deductions and strengthening understandings of how faith-based development organizations impact aspects of religious, economic, and social life in the areas where they work.

Women and development in Senegal: Microcredit and household well being

The challenging living conditions of many Senegalese families, and the absence of a providing spouse, have led women to covet new economic opportunities, such as microcredit loans. These loans offer Senegalese women the possibility to financially support their households and become active participants in their economies by starting or sustaining their micro businesses. The study takes place in Grand-Yoff, an overpopulated peri-urban area of the Senegalese capital city Dakar, where most people face daily survival issues. This research examines the impact of microcredit activities in the household of Senegalese female loan recipients in Grand-Yoff by examining socioeconomic indicators, in particular outcomes of health, education and nutrition.^ The research total sample is constituted of 166 female participants who engage in microcredit activities. The research combines both qualitative and quantitative methods. Data for the study were gathered through interviews, surveys, participant observation, focus-groups with the study participants and some of their household members, and document analysis.^ While some women in the study make steady profits from their business activities, others struggle to make ends meet from their businesses’ meager or unreliable profits. Some study participants who are impoverished have no choice but to invest their loans directly into their households’ dire needs, hence missing their business prerogative. Many women in the study end up in a vicious cycle of debt by defaulting on their loans or making late payments because they do not have the required household and socioeconomic conditions to take advantage of these loans. Therefore, microcredit does not make a significant impact in the households of the poorest female participants. The study finds that microcredit improves the household well-being - especially nutrition, health and education - of the participants who have acquired significant social capital such as a providing spouse, formal education, training, business experience, and belonging to business or social networks.^ The study finds that microcredit’s household impact is intimately tied to the female borrowers’ household conditions and social capital. It is recommended that microcredit services and programs offer their female clients assistance and additional basic services, financial guidance, lower interest rates, and flexible repayment schedules. ^

A study on uncertain dynamic disaster management tasks, knowledge sharing, and task performance

Each disaster presents itself with a unique set of characteristics that are hard to determine a priori. Thus disaster management tasks are inherently uncertain, requiring knowledge sharing and quick decision making that involves coordination across different levels and collaborators. While there has been an increasing interest among both researchers and practitioners in utilizing knowledge management to improve disaster management, little research has been reported about how to assess the dynamic nature of disaster management tasks, and what kinds of knowledge sharing are appropriate for different dimensions of task uncertainty characteristics. ^ Using combinations of qualitative and quantitative methods, this research study developed the dimensions and their corresponding measures of the uncertain dynamic characteristics of disaster management tasks and tested the relationships between the various dimensions of uncertain dynamic disaster management tasks and task performance through the moderating and mediating effects of knowledge sharing. ^ Furthermore, this research work conceptualized and assessed task uncertainty along three dimensions: novelty, unanalyzability, and significance; knowledge sharing along two dimensions: knowledge sharing purposes and knowledge sharing mechanisms; and task performance along two dimensions: task effectiveness and task efficiency. Analysis results of survey data collected from Miami-Dade County emergency managers suggested that knowledge sharing purposes and knowledge sharing mechanisms moderate and mediate uncertain dynamic disaster management task and task performance. Implications for research and practice as well directions for future research are discussed.^

A longitudinal exploration of the relationship between oral reading fluency and reading comprehension achievement among a sample of diverse young learners

Exploring the relationship between early oral reading fluency ability and reading comprehension achievement among an ethnically and racially diverse sample of young learners from low-income families, attending elementary school within a large public school district in southeast Florida is the purpose of this longitudinal study. Although many studies have been conducted to address the relationship between oral reading fluency ability and reading comprehension achievement, most of the existing research failed either to disaggregate the data by demographic subgroups or secure a large enough sample of students to adequately represent the diverse subgroups. The research questions that guided this study were: (a) To what extent does early oral reading fluency ability measured in first, second, or third grade correlate with reading comprehension achievement in third grade? (b) To what extent does the relationship of early oral reading fluency ability and reading comprehension achievement vary by demographic subgroup membership (i.e., gender, race/ethnicity, socioeconomic status) among a diverse sample of students? A predictive research design using archived secondary data was employed in this nonexperimental quantitative methods study of 1,663 third grade students who attended a cohort of 25 Reading First funded schools. The data analyzed derived from the Dynamic Indicators of Basic Early Literacy Skills Oral Reading Fluency (DIBELS ORF) measure administered in first, second, and third grades and the Florida Comprehensive Assessment Test of the Sunshine State Standards (FCAT-SSS) Reading administered in third grade. Linear regression analyses between each of the oral reading fluency and reading comprehension measures produced significant positive correlations. Hierarchical regression analyses supported the predictive potential of all three oral reading fluency ability measures toward reading comprehension achievement, with the first grade oral reading fluency ability measure explaining the most significant variance in third grade reading comprehension achievement. Male students produced significant overall differences in variance when compared to female students as did the Other student subgroup (i.e., Asian, Multiracial, and Native American) when compared to Black, White, and Hispanic students. No significant differences in variance were produced between students from low and moderate socioeconomic families. These findings are vital toward adding to the literature of diverse young learners.

Role Stress, Emotional Exhaustion, and Job Satisfaction in the Hotel Industry: The Moderating Role of Supervisory Support

The purpose of this study is to investigate supervisory support as a moderator of the effects of role conflict and role ambiguity on emotional exhaustion and job satisfaction. This study also examines the moderating role of supervisory support on the relationship between emotional exhaustion and job satisfaction. Data were collected from a sample of frontline hotel employees in Northern Cyprus. The aforementioned relationships were tested based on hierarchical multiple regression analysis. The results demonstrate that supervisory support mitigates the impact of role conflict on emotional exhaustion and further reveal that supervisory support reduces the effect of emotional exhaustion on job satisfaction. There is no empirical support for the rest of the hypothesized relationships. Implications of the empirical results are discussed, and future research directions are offered.

Effects of Management-Development Practices on Hospitality Management Graduates' Job Satisfaction and Intention to Stay

Companies have long recognized the importance of training and developing their managers to prepare them for their short- and long-term careers. Formal management-development programs and other less formal means of management development abound in the hospitality industry. Therefore, one may ask whether the entry-level managers for whom these programs are designed perceive them to be effective. The present study explores management-development practices, procedures, and techniques, and their effects on job satisfaction and organizational commitment

Empowerment, social support, and self -esteem of parents involved in an elementary school program

Parent involvement (PI) in schooling has consistently been correlated with improved academic achievement in children. However, despite the apparent benefits of parent involvement, many schools serving low-income communities report consistent difficulty in facilitating the involvement of parents in their children's schooling. ^ The purpose of this exploratory pilot study was to examine key variables associated with a PI program at a school that served a low-income community. The program was selected because it sustained the involvement of parents for a prolonged period of time. It was also selected because the program was facilitated by social workers. ^ Derived from the literature, four lines of inquiry were examined: (a) the relationship between PI and parent strengths and development; (b) the relationship between PI and children's academic achievement; (c) facilitators for PI; and (d) barriers to PI. These lines of inquiry yielded the study's four primary research questions. The study employed a cross-sectional research design to address them. ^ Thirty-three parents, representing 16 school-involved (SI) parents and 17 non-school involved (NSI) parents, served as study participants. All 33 parents resided in a high poverty community. ^ Quantitative methods were selected to examine differences between study participants and PI. Measures of parental empowerment, social support, self-esteem, and direct and indirect measures of their children's academic achievement were utilized. Qualitative methods were developed to identify and describe SI and NSI parents' perceptions of facilitators for and barriers to PI. ^ This study's findings suggest that PI may yield important benefits for SI parents. These benefits include parents' perceptions of their empowerment, social support, and self-esteem. This study's findings also suggest a relationship between PI and reduced rates of children's school suspensions. This study did not, however, support relationships between PI and children's standardized test scores. This study concludes that despite the apparent benefits of PI for SI parents, PI may nonetheless be a proxy for several unspecified interventions that effect parents, children, schools and communities alike. More precise specifications and robust measures of PI are needed. ^

Teacher perception of self -determination skills in the inclusive and special education classroom

It has been proposed that special education teachers, who promote self-determination and link it to educational standards, help students with a disability succeed in school. The current school reform movement has focused on accountability through mandates such as the No Child Left Behind Act, 2001, and has emphasized participation in the general curriculum through amendments to the Individuals with Disabilities Education Act (IDEA) of 1997 and 2004. This study informs educators if educational setting, students' type of disability, and subject area taught, influence teachers' opinions about the importance of teaching components leading to self-determination and self-management. ^ The research questions that drive this study are: (1) do secondary school teachers who instruct students with a disability think that self-determination components taught in the classroom will make an important difference in students' school and later postsecondary achievements? and (2) does the type of classroom setting, students' type of disability, or specific subject matter influence teachers' opinions regarding the importance of teaching components related to self-determination and self-management? The collection and interpretation of data were done using descriptive and quantitative methods employing a teacher survey. The survey was administered to secondary teachers who instruct students with disabilities. Data were analyzed using descriptive and inferential statistics. The sample consisted of 97 special education teachers currently teaching at the secondary level. ^ The results of the study indicated that teachers believe that self-determination is important for both school life and post school life. However teachers thought these skills to be more important for post school success. Teachers believe that self-determination is more important than self-management skills. Type of disability, educational environment, and subject area were not significant factors. ^

A comparison study of the English III/American Literature success of African American high school students and that of students whose home language is Haitian Creole

The purpose of the study was to compare the English III success of students whose home language is Haitian Creole (SWHLIHC) with that of the more visible African American high school students in the Miami Dade County Public Schools System, in an effort to offer insight that might assist educators in facilitating the educational success of SWHLIHC in American Literature class.^ The study was guided by two important theories on how students interact with and learn from literature. They are Reader Response Theory which advocates giving students the opportunity to become involved in the literature experience (Rosenblatt, 1995), and Critical Literacy, a theory developed by Paolo Freire and Henry Giroux, which espouses a critical approach to analysis of society that enables people to analyze social problems through lenses that would reveal social inequities and assist in transforming society into a more equitable entity.^ Data for the study: 10th grade reading FCAT scores, English III/American Literature grades, and Promotion to English IV records for the school year 2010-2011 were retrieved from the records division of the Miami Dade County Public Schools System. The study used a quantitative methods approach, the central feature of which was an ex post facto design with hypotheses (Newman, Newman, Brown, & McNeely, 2006). The ex post facto design with hypotheses was chosen because the researcher postulated hypotheses about the relationships that might exist between the performances of SWHLIHC and those of African American students on the three above mentioned variables. This type of design supported the researcher's purpose of comparing these performances.^ One way analysis of variance (ANOVA), two way ANOVAs, and chi square tests were used to examine the two groups' performances on the 10th grade reading FCAT, their English III grades, and their promotion to English IV. ^ The study findings show that there was a significant difference in the performance of SWHLIHC and African American high school students on all three independent variables. SWHLIHC performed significantly higher on English III success and promotion to English IV. African American high school students performed significantly higher on the reading FCAT.^