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HOW MY PRACTICE OF USING MANIPULATIVES IN TEACHING MULTIPLYING AND DIVIDING FRACTIONS INFLUENCES THE STUDENTS' CONCEPTUAL UNDERSTANDING OF THESE OPERATIONS
Title
HOW MY PRACTICE OF USING MANIPULATIVES IN TEACHING MULTIPLYING AND DIVIDING FRACTIONS INFLUENCES THE STUDENTS' CONCEPTUAL UNDERSTANDING OF THESE OPERATIONS.
Creator
Bale, Vickie, Dixon, Juli, University of Central Florida
Abstract / Description
This qualitative study examined how my practice of using manipulatives to teach multiplying and dividing fractions to 8th grade students facilitated their conceptual understanding of those operations. The students who participated in the study were enrolled in one of my intensive mathematics classes. Before the lessons began, I interviewed the students and gave them a pre-assessment to determine their content knowledge and comfort level with manipulatives. The students engaged in activities...
Show moreThis qualitative study examined how my practice of using manipulatives to teach multiplying and dividing fractions to 8th grade students facilitated their conceptual understanding of those operations. The students who participated in the study were enrolled in one of my intensive mathematics classes. Before the lessons began, I interviewed the students and gave them a pre-assessment to determine their content knowledge and comfort level with manipulatives. The students engaged in activities that included solving problems using various manipulatives. During the activities, I made observations of their problem solving techniques and how they used the manipulatives. At the conclusion of the unit I gave them a post assessment and conducted post interviews to determine any change in their content knowledge and comfort level with using manipulatives. I concluded through my research that by giving the students a hands-on, minds-on approach to learning they were able to develop an understanding of the concepts and apply that knowledge to multiplying and dividing fractions.
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Date Issued
2006
Identifier
CFE0001068, ucf:46812
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001068
PRESERVICE ELEMENTARY TEACHERS' DEVELOPMENT OF RATIONAL NUMBER UNDERSTANDING THROUGH THE SOCIAL PERSPECTIVE AND THE RELATIONSHIP AMONG SOCIAL AND INDIVIDUAL ENVIRONMENTS
Title
PRESERVICE ELEMENTARY TEACHERS' DEVELOPMENT OF RATIONAL NUMBER UNDERSTANDING THROUGH THE SOCIAL PERSPECTIVE AND THE RELATIONSHIP AMONG SOCIAL AND INDIVIDUAL ENVIRONMENTS.
Creator
Tobias, Jennifer, Dixon, Juli, University of Central Florida
Abstract / Description
A classroom teaching experiment was conducted in a semester-long undergraduate mathematics content course for elementary education majors. Preservice elementary teachers' development of rational number understanding was documented through the social and psychological perspectives. In addition, social and sociomathematical norms were documented as part of the classroom structure. A hypothetical learning trajectory and instructional sequence were created from a combination of previous...
Show moreA classroom teaching experiment was conducted in a semester-long undergraduate mathematics content course for elementary education majors. Preservice elementary teachers' development of rational number understanding was documented through the social and psychological perspectives. In addition, social and sociomathematical norms were documented as part of the classroom structure. A hypothetical learning trajectory and instructional sequence were created from a combination of previous research with children and adults. Transcripts from each class session were analyzed to determine the social and sociomathematical norms as well as the classroom mathematical practices. The social norms established included a) explaining and justifying solutions and solution processes, b) making sense of others' explanations and justifications, c) questioning others when misunderstandings occur, and d) helping others. The sociomathematical norms established included determining what constitutes a) an acceptable solution and b) a different solution. The classroom mathematical practices established included ideas related to a) defining fractions, b) defining the whole, c) partitioning, d) unitizing, e) finding equivalent fractions, f) comparing and ordering fractions, g) adding and subtracting fractions, and h) multiplying fractions. The analysis of individual students' contributions included analyzing the transcripts to determine the ways in which individuals participated in the establishment of the practices. Individuals contributed to the practices by a) introducing ideas and b) sustaining ideas. The transcripts and student work samples were analyzed to determine the ways in which the social classroom environment impacted student learning. Student learning was affected when a) ideas were rejected and b) ideas were accepted. As a result of the data analysis, the hypothetical learning trajectory was refined to include four phases of learning instead of five. In addition, the instructional sequence was refined to include more focus on ratios. Two activities, the number line and between activities, were suggested to be deleted because they did not contribute to students' development.
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Date Issued
2009
Identifier
CFE0002737, ucf:48165
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002737
FRACTION MODELS THAT PROMOTE UNDERSTANDING FOR ELEMENTARY STUDENTS
Title
FRACTION MODELS THAT PROMOTE UNDERSTANDING FOR ELEMENTARY STUDENTS.
Creator
Hull, Lynette, Dixon, Juli, University of Central Florida
Abstract / Description
This study examined the use of the set, area, and linear models of fraction representation to enhance elementary students' conceptual understanding of fractions. Students' preferences regarding the set, area, and linear models of fractions during independent work was also investigated. This study took place in a 5th grade class consisting of 21 students in a suburban public elementary school. Students participated in classroom activities which required them to use manipulatives to represent...
Show moreThis study examined the use of the set, area, and linear models of fraction representation to enhance elementary students' conceptual understanding of fractions. Students' preferences regarding the set, area, and linear models of fractions during independent work was also investigated. This study took place in a 5th grade class consisting of 21 students in a suburban public elementary school. Students participated in classroom activities which required them to use manipulatives to represent fractions using the set, area, and linear models. Students also had experiences using the models to investigate equivalent fractions, compare fractions, and perform operations. Students maintained journals throughout the study, completed a pre and post assessment, participated in class discussions, and participated in individual interviews concerning their fraction model preference. Analysis of the data revealed an increase in conceptual understanding. The data concerning student preferences were inconsistent, as students' choices during independent work did not always reflect the preferences indicated in the interviews.
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Date Issued
2005
Identifier
CFE0000552, ucf:46428
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000552
Influence of using context supportive of the area model on sixth grade students' performance when writing word problems for fraction subtraction and multiplication
Title
Influence of using context supportive of the area model on sixth grade students' performance when writing word problems for fraction subtraction and multiplication.
Creator
Friske, Monica, Dixon, Juli, Andreasen, Janet, Ortiz, Enrique, University of Central Florida
Abstract / Description
The purpose of this action research study was to evaluate my own practice of teaching writing word problems with fraction subtraction and fraction multiplication using appropriate context. I wanted to see how focusing my instruction on the use of the area model and manipulatives could develop students' understanding of fractions when writing word problems. I chose this topic because Florida has adopted the Common Core State Standards and will be implementing them in the coming years. These...
Show moreThe purpose of this action research study was to evaluate my own practice of teaching writing word problems with fraction subtraction and fraction multiplication using appropriate context. I wanted to see how focusing my instruction on the use of the area model and manipulatives could develop students' understanding of fractions when writing word problems. I chose this topic because Florida has adopted the Common Core State Standards and will be implementing them in the coming years. These standards encourage the development of deeper understanding of mathematics, including fractions. I hoped this research would give my students the opportunity to make sense of fraction subtraction and fraction multiplication word problems on a deeper level, while giving me insight into my own practice in teaching context within word problems. Through this study, I learned that my students continued to switch the context of subtraction with multiplication within word problems. Students did make clear gains in their writing of fraction subtraction and fraction multiplication word problems. Although there is a limited amount of research on students mixing their context within fraction word problems, this study offers additional insight into a teacher's practice with writing fraction word problems.
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Date Issued
2011
Identifier
CFE0004111, ucf:49112
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004111
EXAMINING SOCIOMATHEMATICAL NORMS WITHIN THE CONTEXT OF DECIMALS AND FRACTIONS IN A SIXTH GRADE CLASSROOM
Title
EXAMINING SOCIOMATHEMATICAL NORMS WITHIN THE CONTEXT OF DECIMALS AND FRACTIONS IN A SIXTH GRADE CLASSROOM.
Creator
Nardelli, Marino, Dixon, Juli, University of Central Florida
Abstract / Description
Social norms are patterns of behavior expected within a particular society in a given situation. Social norms can be shared belief of what is normal and acceptable shapes and enforces the actions of people in a society. In the educational classroom, they are characteristics that constitute the classroom participation structure. Sociomathematical norms are fine-grained aspects of general social norms specifically related to mathematical practices. These can include, but are not limited to, a...
Show moreSocial norms are patterns of behavior expected within a particular society in a given situation. Social norms can be shared belief of what is normal and acceptable shapes and enforces the actions of people in a society. In the educational classroom, they are characteristics that constitute the classroom participation structure. Sociomathematical norms are fine-grained aspects of general social norms specifically related to mathematical practices. These can include, but are not limited to, a student-centered classroom that includes the expectation that the students should present their solution methods by describing actions on mathematical objects rather than simply accounting for calculational manipulations. For this action research study, my goal was to determine if the role of the teacher would influence the social and sociomathematical norms in a mathematics classroom and in what ways are sociomathematical norms reflected in students' written work. I focused specifically on students' mathematics journal writing and taped conversations. I discovered that students tended to not justify their work. Also, I discovered that my idea of justification was not really justification. I learned from this and was able to change my idea of justification. By encouraging the students to socialize in mathematics class, I found that the quality of their dialogue improved. Students readily discussed mathematical concepts within small groups and whole class discussions.
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Date Issued
2007
Identifier
CFE0001650, ucf:47245
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0001650
FOSTERING TEACHER'S CONCEPTUAL UNDERSTANDING OF ORDERING, ADDING, AND SUBTRACTING FRACTIONS THROUGH SCHOOL-BASED PROFESSIONAL DEVELOPMENT
Title
FOSTERING TEACHER'S CONCEPTUAL UNDERSTANDING OF ORDERING, ADDING, AND SUBTRACTING FRACTIONS THROUGH SCHOOL-BASED PROFESSIONAL DEVELOPMENT.
Creator
Maguhn , Jessica, Dixon , Juli, University of Central Florida
Abstract / Description
In an attempt to examine my practice of providing conceptually-based professional development on fractions to fifth grade teachers, I conducted a series of four one hour professional development workshops. I focused on the conceptual understanding of ordering, adding, and subtracting fractions. I examined the solution process that teachers used to solve fraction problems and their abilities to explain and justify their solutions in an attempt to interpret their understanding. My data showed...
Show moreIn an attempt to examine my practice of providing conceptually-based professional development on fractions to fifth grade teachers, I conducted a series of four one hour professional development workshops. I focused on the conceptual understanding of ordering, adding, and subtracting fractions. I examined the solution process that teachers used to solve fraction problems and their abilities to explain and justify their solutions in an attempt to interpret their understanding. My data showed the effects of this workshop series. The study helped determine the effects of conceptually-based professional development on fractions as demonstrated in the teachers' discussions, participation, and written explanations.
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Date Issued
2009
Identifier
CFE0002608, ucf:48259
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002608
AN ACTION RESEARCH STUDY INVOLVING FIFTH-GRADE STUDENTS LEARNING FRACTIONS THROUGH A SITUATIVE PERSPECTIVE WITH STORY PROBLEMS
Title
AN ACTION RESEARCH STUDY INVOLVING FIFTH-GRADE STUDENTS LEARNING FRACTIONS THROUGH A SITUATIVE PERSPECTIVE WITH STORY PROBLEMS.
Creator
Allen, Colleen, Dixon, Juli, University of Central Florida
Abstract / Description
ABSTRACT The purpose of this action research study was to investigate the affects of teaching through a situative perspective with story problems on students' understanding of fraction concepts and operations in my fifth-grade mathematics classroom. Students participated in twelve weeks of instruction. Data was collected in the form of pre and post tests, audiotaped and videotaped recordings of instructional sessions, and student work samples. Data analysis revealed that my students...
Show moreABSTRACT The purpose of this action research study was to investigate the affects of teaching through a situative perspective with story problems on students' understanding of fraction concepts and operations in my fifth-grade mathematics classroom. Students participated in twelve weeks of instruction. Data was collected in the form of pre and post tests, audiotaped and videotaped recordings of instructional sessions, and student work samples. Data analysis revealed that my students constructed their own knowledge about various fraction concepts and operations because students engaged in discussions, after solving story problems, that developed, extended and restructured their knowledge. One example of this occurred after students had solved an equal-sharing problem. Two students came up with different answers and another student explained why both answers were equivalent. Student work samples and post test results indicated that the one student's explanation was understood, adopted and extended by all the students in my class. The data also revealed that students' pictures typically represented the context and action of the story problems. For example, subtraction problems dealing with length were usually represented by number lines or horizontal rectangles with crossed-out markings to show the subtraction operation. Throughout this research study, I discovered that my students were capable of learning from each other and solving problems for which they have no preconceived algorithm. I also learned that analyzing students' work and listening to their discussions in ways that focused on their thinking, not their answers, provided me with information about what my students were grasping and not grasping.
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Date Issued
2005
Identifier
CFE0000538, ucf:46423
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0000538
USING COMMUNICATION TECHNIQUES IN THE LOW-PERFORMING MATHEMATICS CLASSROOM: A STUDY OF FRACTIONS,DECIMALS,PERFORMANCE AND ATTITUDES
Title
USING COMMUNICATION TECHNIQUES IN THE LOW-PERFORMING MATHEMATICS CLASSROOM: A STUDY OF FRACTIONS,DECIMALS,PERFORMANCE AND ATTITUDES.
Creator
Guyton, Pamela, Ortiz, Enrique, University of Central Florida
Abstract / Description
Within a low-performing seventh grade mathematics classroom, communication techniques including discourse, collaborative groups, listening, reading, and writing were implemented during a six week period. This study shows how the use of these techniques led to the twenty four students' conceptual understanding of fraction and decimal concepts. This research study provides insight to the deep-seeded beliefs of low-performing students. It provides a record of how the teacher used...
Show moreWithin a low-performing seventh grade mathematics classroom, communication techniques including discourse, collaborative groups, listening, reading, and writing were implemented during a six week period. This study shows how the use of these techniques led to the twenty four students' conceptual understanding of fraction and decimal concepts. This research study provides insight to the deep-seeded beliefs of low-performing students. It provides a record of how the teacher used communication techniques in the classroom and had a strong positive impact on the attitudes and performance of these struggling students.
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Date Issued
2008
Identifier
CFE0002146, ucf:47928
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002146
THE EFFECTS OF A RATIO-BASED TEACHING SEQUENCE ON PERFORMANCE IN FRACTION EQUIVALENCY FOR STUDENTS WITH MATHEMATICS DISABILITIES
Title
THE EFFECTS OF A RATIO-BASED TEACHING SEQUENCE ON PERFORMANCE IN FRACTION EQUIVALENCY FOR STUDENTS WITH MATHEMATICS DISABILITIES.
Creator
Hunt, Jessica, Dieker, Lisa, University of Central Florida
Abstract / Description
This study examined the effects of a ratio-based supplemental teaching sequence on third grade students' equivalent fraction performance as measured by a curriculum-based measure and a standardized test. Participants included students identified as being learning disabled in mathematics (MLD), struggling (SS), or typically achieving (TA). Nineteen students were assigned to the experimental group and 19 additional students formed the control group. The difference between the two groups was...
Show moreThis study examined the effects of a ratio-based supplemental teaching sequence on third grade students' equivalent fraction performance as measured by a curriculum-based measure and a standardized test. Participants included students identified as being learning disabled in mathematics (MLD), struggling (SS), or typically achieving (TA). Nineteen students were assigned to the experimental group and 19 additional students formed the control group. The difference between the two groups was that the experimental group received the ratio-based teaching sequence. Both groups continued to receive textbook based instruction in fraction equivalency concepts in their regular mathematics classroom. Qualitative interviews were employed to further investigate the thinking of each of the three types of students in the study. Analysis of the data indicated that students in the experimental group outperformed the control group on both the curriculum-based measure and the standardized measure of fraction equivalency All students who participated in ratio-based instruction had a higher performance in fraction equivalency than those who did not. Performance on the CBM and the standardized measure of fraction equivalency improved significantly from pre to post test for students who struggled; their performance also transferred to standardized measures. Qualitative analysis revealed that a focal student with MLD, while improving his ability to think multiplicatively, had misconceptions about fractions as ratios that persisted even after the intervention was completed. Implications for instruction, teacher preparation, and future research are provided.
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Date Issued
2011
Identifier
CFE0004003, ucf:49170
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0004003
TUNNELING CONDUCTANCE CHARACTERIZATION OF A QUANTUM DOT IN THE FRACTIONAL QUANTUM HALL REGIME
Title
TUNNELING CONDUCTANCE CHARACTERIZATION OF A QUANTUM DOT IN THE FRACTIONAL QUANTUM HALL REGIME.
Creator
Willard, Douglas, Johnson, Michael, University of Central Florida
Abstract / Description
This work represents a first-principles calculation of the electron tunneling current into quantum dots in the fractional quantum Hall effect regime. The system under consideration consists of an idealized Scanning Tunneling Microscope (STM) tip and a quantum dot with disk geometry and interacting electrons in a transverse magnetic field. Within the context of this model the tunneling current between the STM tip and the dot is examined for spin-polarized electrons at and around a filling...
Show moreThis work represents a first-principles calculation of the electron tunneling current into quantum dots in the fractional quantum Hall effect regime. The system under consideration consists of an idealized Scanning Tunneling Microscope (STM) tip and a quantum dot with disk geometry and interacting electrons in a transverse magnetic field. Within the context of this model the tunneling current between the STM tip and the dot is examined for spin-polarized electrons at and around a filling factor of 1/3. The current expression is based on a second-quantized Hamiltonian in which electrons in the dot are interacting, confined, and restricted to the lowest Landau level, necessary to capture the physics of the fractional quantum Hall effect. The Hamiltonian includes simple approximations for the STM tip and the tip-dot tunneling. An exact analytic expression for the first-order tunneling current is derived using a Green's function approach. To calculate the tunneling current numerically the infinite Hilbert space of the dot is truncated to have a finite dimension within the lowest Landau level. This simplification is appropriate for a low temperature system in the fractional quantum Hall regime because of the finite size of the quantum dot and the large energy gap between Landau levels. The tunneling current is then solved in two steps. First, many-electron energy eigenstates are calculated from the truncated Hamiltonian by numerical diagonalization. This is carried out for varying numbers of electrons N. The energy eigenstates form a set of complete basis states of the system and are used in the expression for the tunneling current. In the second step, the chemical potential in the dot is chosen to select a desired number of electrons and the tunneling current evaluated. We have carried out this program for filling factors near 1/3 while modulating the system parameters of interest to determine functional dependencies.
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Date Issued
2011
Identifier
CFE0003990, ucf:48677
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0003990
Teaching Fractions Procedurally and Conceptually to Pre-Service Elementary Education Teachers
Title
Teaching Fractions Procedurally and Conceptually to Pre-Service Elementary Education Teachers.
Creator
Edwards, Deborah, Hopp, Carolyn, Vitale, Thomas, Ortiz, Enrique, French, Jonathan, University of Central Florida
Abstract / Description
The purpose of this Dissertation in Practice was to inform pre-service elementary education teachers of conceptual and procedural methods for teaching fractions. The problem of practice began when the researcher noticed a deficiency in fraction addition knowledge for a remedial mathematics program at a local private university. Further exposure of fraction knowledge for the 2014 third-grade Florida Comprehensive Assessment Test scores at a local elementary charter school ascertained slightly...
Show moreThe purpose of this Dissertation in Practice was to inform pre-service elementary education teachers of conceptual and procedural methods for teaching fractions. The problem of practice began when the researcher noticed a deficiency in fraction addition knowledge for a remedial mathematics program at a local private university. Further exposure of fraction knowledge for the 2014 third-grade Florida Comprehensive Assessment Test scores at a local elementary charter school ascertained slightly above 50% of those students making a 70% percentile or higher. Now that Florida State Standards are aligned with the Common Core Standards, pre-service elementary teachers need to know how to teach fractions procedurally and conceptually. This research-based model was used to determine the level of fraction knowledge, math anxiety level, and present NCTM videos aligned with Common Core Standards. A key element of the model was the performance assessment of the participants teaching randomly selected fraction problems they had already encountered confirming the need for more professional development in this essential mathematics domain.
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Date Issued
2015
Identifier
CFE0006215, ucf:51098
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006215
A Multiple Case Study Examining How Third-Grade Students Who Struggle in Mathematics Make Sense of Fraction Concepts
Title
A Multiple Case Study Examining How Third-Grade Students Who Struggle in Mathematics Make Sense of Fraction Concepts.
Creator
Gault, Rebecca, Ortiz, Enrique, Dixon, Juli, Nickels, Megan, Little, Mary, University of Central Florida
Abstract / Description
A qualitative multiple case study was conducted to reveal the sense-making processes third-grade students who struggle in mathematics used to build an understanding of fraction concepts. Purposive sampling identified three participants who were struggling in a local school's third grade mathematics classes. This research describes how these participants made sense of fraction concepts through their strengths and struggles while engaged in 15 small-group intervention sessions. Vygotsky's (1934...
Show moreA qualitative multiple case study was conducted to reveal the sense-making processes third-grade students who struggle in mathematics used to build an understanding of fraction concepts. Purposive sampling identified three participants who were struggling in a local school's third grade mathematics classes. This research describes how these participants made sense of fraction concepts through their strengths and struggles while engaged in 15 small-group intervention sessions. Vygotsky's (1934/1986/2012) theory that children's optimal learning is supported by teacher-student interactions was used as an interpretive framework. Tasks were developed over the course of the intervention sessions with consideration of a model developed by Lesh, Post, and Behr (1987) for connecting mathematical representations and the Common Core State Standards for Mathematics (National Governors Association Center for Best Practices (&) Council of Chief State School Officers, 2010). Data, including transcripts, tapes, and artifacts, were analyzed using two frameworks. These were Geary's (2003) classification of three subtypes of learning disabilities in mathematics and Anghileri's (2006) descriptions of social-constructivist scaffolding techniques. The first analysis resulted in a description of each participant's strengths and struggles, including alignment with Geary's subtypes, and how these strengths and struggles interacted with participant's construction of knowledge about fractions. The second analysis described episodes of learning that were supported by social-constructivist scaffolding techniques and revealed how participants made sense of fractions through their interactions with each other, the researcher, and intervention tasks. The researcher found that each participant's learning process, including struggles, was unique, with each interacting in different ways with tasks, manipulatives, pictorial representations, and questioning. For each participant, however, scaffolding techniques oriented around prompting and probing questions, participant verbalizations, and interactions with connected fraction representations were critical in their learning process.
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Date Issued
2016
Identifier
CFE0006307, ucf:51587
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006307
The African Puzzle: A Study of Democratic Backsliding in Sub Saharan Africa
Title
The African Puzzle: A Study of Democratic Backsliding in Sub Saharan Africa.
Creator
Rice, Ailbhe, Powell, Jonathan, Boutton, Andrew, Bledsoe, Robert, University of Central Florida
Abstract / Description
The following study examines the future of democratization and the apparent trend towards autocratization within the context of democratic backsliding in Sub-Saharan Africa. Initially, the findings indicate that regionally, backsliding is not acting fundamentally different in Sub-Saharan Africa when compared to other regions. The analysis finds that regime duration and civil conflict are both significant when it comes to the study of democratic backsliding. The variable for the prior military...
Show moreThe following study examines the future of democratization and the apparent trend towards autocratization within the context of democratic backsliding in Sub-Saharan Africa. Initially, the findings indicate that regionally, backsliding is not acting fundamentally different in Sub-Saharan Africa when compared to other regions. The analysis finds that regime duration and civil conflict are both significant when it comes to the study of democratic backsliding. The variable for the prior military regime's is extremely significant in all of the models and is, therefore, a strong indicator of backsliding in Africa. The chief takeaway from the study is in the variable for economic growth and finds that as economic growth increases the likelihood of backsliding decreases. This variable is negative and significant for all of the models, but if Africa is taken out of the analysis the trend ultimately disappears, which indicates that Africa is potentially driving this trend of economic growth and backsliding.
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Date Issued
2018
Identifier
CFE0007360, ucf:52080
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007360
STRUCTURAL CAUSES OF SOCIAL CONFLICT IN AFRICA
Title
STRUCTURAL CAUSES OF SOCIAL CONFLICT IN AFRICA.
Creator
Charland, Lucien, Dolan, Thomas, University of Central Florida
Abstract / Description
Social conflict, as opposed to armed conflict, has received less attention in the field of quantitative research. This paper investigates the structural causes of political violence in 35 African states using data from the Social Conflict in Africa dataset and the Beck and Katz panel corrected standard errors time series regression model. Theoretically, a closed political opportunity structure, combined with a weak state unable to provide public goods, should together produce high levels of...
Show moreSocial conflict, as opposed to armed conflict, has received less attention in the field of quantitative research. This paper investigates the structural causes of political violence in 35 African states using data from the Social Conflict in Africa dataset and the Beck and Katz panel corrected standard errors time series regression model. Theoretically, a closed political opportunity structure, combined with a weak state unable to provide public goods, should together produce high levels of social conflict. The independent variables attempt to operationalize these concepts from four different angles. In this analysis Access to Education and Infrastructure (AEI), Ethno Linguistic Fractionalization (ELF), Freedom in the World Political Rights (FIW), and National Material Capabilities (NMC) were all significant predictors of social conflict. This study found that as the level of ethnic fractionalization and material capabilities within states rose, the frequency of social conflict events also increased. However, as access to infrastructure and political rights declined, the number of social conflict events increased. Wald chi-square and R-square values suggest that the model is complete and has substantial explanatory power.
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Date Issued
2014
Identifier
CFH0004663, ucf:45314
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH0004663
A Joint Econometric Approach for Modeling Crash Counts by Collision Type
Title
A Joint Econometric Approach for Modeling Crash Counts by Collision Type.
Creator
Bhowmik, Tanmoy, Eluru, Naveen, Abdel-Aty, Mohamed, Yasmin, Shamsunnahar, University of Central Florida
Abstract / Description
In recent years, there is growing recognition that common unobserved factors that influence crash frequency by one attribute level are also likely to influence crash frequency by other attribute levels. The most common approach employed to address the potential unobserved heterogeneity in safety literature is the development of multivariate crash frequency models. The current study proposes an alternative joint econometric framework to accommodate for the presence of unobserved heterogeneity ...
Show moreIn recent years, there is growing recognition that common unobserved factors that influence crash frequency by one attribute level are also likely to influence crash frequency by other attribute levels. The most common approach employed to address the potential unobserved heterogeneity in safety literature is the development of multivariate crash frequency models. The current study proposes an alternative joint econometric framework to accommodate for the presence of unobserved heterogeneity (-) referred to as joint negative binomial-multinomial logit fractional split (NB-MNLFS) model. Furthermore, the study undertakes a first of its kind comparison exercise between the most commonly used multivariate model (multivariate random parameter negative binomial model) and the proposed joint approach by generating an equivalent log-likelihood measure. The empirical analysis is based on the zonal level crash count data for different collision types from the state of Florida for the year 2015. The model results highlight the presence of common unobserved effects affecting the two components of the joint model as well as the presence of parameter heterogeneity. The equivalent log-likelihood and goodness of fit measures clearly highlight the superiority of the proposed joint model over the commonly used multivariate approach.
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Date Issued
2018
Identifier
CFE0007392, ucf:52740
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007392
Supporting Middle School Students with Emotional or Behavioral Disorders in Blended Learning: A Fraction Intervention using Virtual Manipulatives
Title
Supporting Middle School Students with Emotional or Behavioral Disorders in Blended Learning: A Fraction Intervention using Virtual Manipulatives.
Creator
Serianni, Barbara, Dieker, Lisa, Marino, Matthew, Vasquez, Eleazar, Basham, James, University of Central Florida
Abstract / Description
Students with emotional or behavioral disorders (EBD) are more likely than other students with disabilities to drop out of school (Blackorby (&) Wagner, 1996) and suffer societal consequences that include higher probabilities and rates of incarceration, poverty, drug abuse, homelessness, low wages, and unemployment (Bradley, Doolittle, (&) Bartolotta, 2008; Wagner, 1995). High school graduation is a critical factor to improve post-secondary outcomes for students with EBD; yet it is often...
Show moreStudents with emotional or behavioral disorders (EBD) are more likely than other students with disabilities to drop out of school (Blackorby (&) Wagner, 1996) and suffer societal consequences that include higher probabilities and rates of incarceration, poverty, drug abuse, homelessness, low wages, and unemployment (Bradley, Doolittle, (&) Bartolotta, 2008; Wagner, 1995). High school graduation is a critical factor to improve post-secondary outcomes for students with EBD; yet it is often mathematics, specifically algebra, that stands in the way of graduation (Blackorby (&) Wagner). Students with EBD often enter middle school lacking foundational mathematics skills, such as fractions, which sets them up to struggle with pre-algebra and ultimately fail algebra (U.S. Department of Education, 2008). The purpose of this study was to improve the ability of middle school students with EBD to access online grade-level mathematics content by providing fraction remediation to improve conceptual fraction knowledge and procedural fluency. The intervention consisted of Initial Fraction Ideas, an intervention curriculum from the Rational Number Project (RNP; Cramer, Behr, Post, (&) Lesh, 2009), in conjunction with three online virtual manipulatives (VM). The unique blended learning environment of this study provided the opportunity to evaluate the use of an evidence-based fraction intervention, in conjunction with VMs, in a single subject, multiple baseline across subjects design. Fluency data was gathered from daily fraction addition assessments (FAA) administered after each intervention session. A second component of the study featured a non-experimental repeated measures design that assessed student conceptual understanding of fraction equivalency through the administration of pre, post, and delayed-post Equivalent Fraction Tests (EFT). The intervention was effective in producing increases in median group fluency with high effect sizes, across three replications, establishing a functional relationship between the intervention and the dependent variable for these groups of students with EBD. In addition, all groups posted mean gains in equivalent fraction knowledge from pre to post-EFT, and maintained those gains for at least 15 days after the intervention concluded.
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Date Issued
2014
Identifier
CFE0005415, ucf:50435
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0005415
Size, Charge and Dose Dependent In-vitro Kinetics of Polystyrene Nanoparticles
Title
Size, Charge and Dose Dependent In-vitro Kinetics of Polystyrene Nanoparticles.
Creator
Abdellatif, Yasmine, Gesquiere, Andre, Kang, Hyeran, Rajaraman, Swaminathan, University of Central Florida
Abstract / Description
The aim of the study described herein is to quantify the in-vitro kinetics of internalization of polystyrene nanoparticles (PS NPs) by cells. We used different charges, sizes and doses of fluorescently labelled PS NPs. Nanoparticles were characterized with UV-Vis, Fluorescence emission Dynamic Light Scattering (DLS) and Zeta potential for knowing their absorption, fluorescence spectra, size, charge, respectively. Additionally, cell viability was tested to know the toxicity of PS NPs. The...
Show moreThe aim of the study described herein is to quantify the in-vitro kinetics of internalization of polystyrene nanoparticles (PS NPs) by cells. We used different charges, sizes and doses of fluorescently labelled PS NPs. Nanoparticles were characterized with UV-Vis, Fluorescence emission Dynamic Light Scattering (DLS) and Zeta potential for knowing their absorption, fluorescence spectra, size, charge, respectively. Additionally, cell viability was tested to know the toxicity of PS NPs. The quantitative uptake, the kinetics profile and rate of uptake were studied by using a new in-vitro fluorescence assay. This was achieved quantitatively and qualitatively by fluorescent plate reader and confocal imaging, respectively. It was found that the amine PS NPs are higher in cytotoxicity than the carboxy PS NPs due to the proton sponge phenomenon. It was observed that the fraction uptake of PS NPs changes by changing the physiochemical properties as charge, size (&) dose. The fraction uptake of neutral and amine PS NPs was higher than that of carboxy PS NPs. For the neutral PS NPs, the uptake depends on the macropinocytosis. For the amine PS NPs, the uptake depends on the electrostatic interaction and the rapid regeneration of new binding sites. Regarding the dose of PS NPs, for the amine PS NPs, it was found that the concentrations lower and higher than 5nM had lower fraction uptake, because the 5nM achieved the balance between the available number of binding sites and the rapid regeneration of new binding sites. For the kinetics profile of the amine and carboxy PS NPs, by comparing both of them, it was observed that the rate of uptake of applied doses lower than 5nM was different, but higher than 5nM was similar. However, for the neutral Ps NPs, they exhibit a steady state of rate of uptake in between the amine and carboxy PS NPs. Also, it was confirmed by the confocal images that as the concentration of amine PS NPs increase, the stress on the cells increase, leading to the cell death. These results were aligned with the results obtained from the cytotoxicity test.
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Date Issued
2018
Identifier
CFE0007386, ucf:52744
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0007386
An Analysis of Undergraduate Elementary School Pre-Service Teachers' Ability to Contextualize Fraction Expressions and Decontextualize Fraction Word Problems
Title
An Analysis of Undergraduate Elementary School Pre-Service Teachers' Ability to Contextualize Fraction Expressions and Decontextualize Fraction Word Problems.
Creator
Tapp, Laura, Ortiz, Enrique, Andreasen, Janet, Dixon, Juli, Witta, Eleanor, University of Central Florida
Abstract / Description
The focus of this research was to expand on existing literature by providing information on elementary school pre-service teachers' ability to contextualize fraction expressions and decontextualize fraction word problems. The elementary school pre-service teachers who participated in this study were enrolled in a mathematics for elementary school teachers content course in a college of education at a large university during the Spring 2016 semester. In this mixed-method study, the...
Show moreThe focus of this research was to expand on existing literature by providing information on elementary school pre-service teachers' ability to contextualize fraction expressions and decontextualize fraction word problems. The elementary school pre-service teachers who participated in this study were enrolled in a mathematics for elementary school teachers content course in a college of education at a large university during the Spring 2016 semester. In this mixed-method study, the participants were given the Contextualization and Decontextualization of Fractions Instrument (CDFI) which assessed elementary school pre-service teachers' ability to solve fraction word problems and identify decontextualized fraction word problems into expressions and contextualized fraction expressions into word problems. The elementary school pre-service teachers were given the CDFI before and after they completed a unit on fractions. Of the 52 participants who completed both the pre- and post- CDFI, 11 were selected to participant in think aloud interviews in which they decontextualized fraction expressions from word problems and solved and contextualized fraction word problems from expressions. Quantitative results showed an overall statistically significant difference in the elementary school pre-service teachers' pre- and post- test scores. With the exception of two questions, all questions on the CDFI showed a statistically significant difference between the pre- and the post- test scores. No statistical significance was found in the responses to the question that required the elementary school pre-service teachers to identify the expression that matched the given fraction subtraction word problem. A large number of participants correctly identified the correct subtraction expression on the pre-test, and only slightly more of them were able to identify the correct subtraction expression on the post-test. No statistical significance was found in the responses to the question that required the elementary school pre-service teachers to explain their selection of a contextualized fraction multiplication expression. Though there was an increase in the elementary school pre-service teachers' ability to explain their selection of the contextualized fraction multiplication expression, it was not statistically significant. The qualitative analysis of the think aloud interview data showed that some of the elementary school pre-service teachers struggled with contextualizing fraction expressions. Most of the elementary school pre-service teachers did not struggle with solving the fraction word problems, but did struggle with decontextualizing fraction multiplication word problems.
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Date Issued
2016
Identifier
CFE0006506, ucf:51405
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006506
Chlamydia trachomatis Transformants Show a Significant Reduction in Rates of Invasion upon Removal of Key Tarp Domains
Title
Chlamydia trachomatis Transformants Show a Significant Reduction in Rates of Invasion upon Removal of Key Tarp Domains.
Creator
Parrett, Christopher, Jewett, Travis, Roy, Herve, Moore, Sean, University of Central Florida
Abstract / Description
Chlamydia trachomatis is an obligate, intracellular bacterium which is known to cause multiple human infections including nongonococcal urethritis (serovars D-K), lymphogranuloma venereum (serovars L1, L2, L3) and trachoma (serovars A-C). The infectious form of the bacterium, called the elementary body (EB), harbors a type III secreted effector known as Tarp (translocated actin recruiting phosphoprotein) which is a candidate virulence factor and is hypothesized to play a role in C....
Show moreChlamydia trachomatis is an obligate, intracellular bacterium which is known to cause multiple human infections including nongonococcal urethritis (serovars D-K), lymphogranuloma venereum (serovars L1, L2, L3) and trachoma (serovars A-C). The infectious form of the bacterium, called the elementary body (EB), harbors a type III secreted effector known as Tarp (translocated actin recruiting phosphoprotein) which is a candidate virulence factor and is hypothesized to play a role in C. trachomatis' ability to invade and grow within epithelial cells in a human host. C. trachomatis L2 Tarp harbors five unique protein domains which include the Phosphorylation Domain, the Proline Rich Domain, the Actin Binding Domain, and two F-Actin Binding Domains. Tarp has been biochemically characterized in vitro, but it has yet to be characterized in vivo due to a lack of genetic tools in C. trachomatis. Through the recent generation of a chlamydial transformation system, we have created transformants which express epitope tagged wild type or mutant Tarp effectors. In this thesis, C. trachomatis transformants expressing Tarp lacking one of the five biochemically defined protein domains were used to examine both bacterial invasion and bacterial development within mammalian host cells. Our results demonstrate that those EBs which harbor mutant Tarp missing either its Phosphorylation Domain or its Actin Binding Domain were less capable of host cell invasion. However, these transformants, once internalized, were capable of normal development when compared to wild type C. trachomatis or C. trachomatis harboring an epitope tagged wild type Tarp effector. These results suggest that transformant expressed Tarp lacking the Phosphorylation Domain or Actin Binding Domain may be acting as a dominant-negative effector protein. Ultimately, these results support the hypothesis that Tarp is a virulence factor for Chlamydia trachomatis. Furthermore, this data indicates that through the manipulation of the Tarp effector, C. trachomatis pathogenesis may be attenuated.
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Date Issued
2016
Identifier
CFE0006159, ucf:51142
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0006159