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- Genre: Masters Thesis
- Creators: Arizona State University
- Creators: Chakraborty, Bijeta
- Member of: ASU Electronic Theses and Dissertations
Description
The development of literacy abilities in young children has been a major concern for authorities and teachers in the USA for the last two decades. Significant effort has been devoted to ensure that preschool settings allow and motivate children to engage in literacy activities before entering kindergarten. Research has found that a rich classroom environment in preschool settings enables teachers to encourage literacy interest in children at a young age. While a large amount of research has concentrated in testing the effect of prescriptive modifications in the classroom environment, few have focused on studying the design process and tools that teachers follow to design their classrooms. Public policy and research studies in the United States, mention the design of the classroom environment among teacher's responsibilities, but they do not include practical or methodological guides for them to use. The purpose of this research was to study the design process and tools that teachers use to design literacy rich classrooms in preschool settings. A case study was conducted at the ASU Mary Lou Fulton Teachers College Preschool at Arizona State University. This setting provides a unique opportunity for an exploratory study of this nature because it is a private child development laboratory with a flexible curriculum. Participant observation sessions and in depth semi-structured interviews were conducted to explore the design process used and experienced by the teachers. Findings revealed an iterative and cyclic design process that is repeated over time adjusting to the influence of numerous factors. Results also suggest that teacher's knowledge and beliefs highly influence the organization of their classrooms. Considering these factors as a standpoint allows for further exploration to determine a design process suitable for teachers when designing their learning environments. The use of a structured yet flexible design process, can be a potential tool for educators to design their classrooms, collaborate, document and transmit their knowledge. Although the findings correspond to a specific site studied, the implications are wide reaching as problems and opportunities expressed by the staff are common to other educational settings with similar characteristics.
ContributorsCortes, Catalina (Author) / Patel, Mookesh (Thesis advisor) / Heywood, William (Committee member) / Christie, James (Committee member) / Arizona State University (Publisher)
Created2013
Description
Efficiency of components is an ever increasing area of importance to portable applications, where a finite battery means finite operating time. Higher efficiency devices need to be designed that don't compromise on the performance that the consumer has come to expect. Class D amplifiers deliver on the goal of increased efficiency, but at the cost of distortion. Class AB amplifiers have low efficiency, but high linearity. By modulating the supply voltage of a Class AB amplifier to make a Class H amplifier, the efficiency can increase while still maintaining the Class AB level of linearity. A 92dB Power Supply Rejection Ratio (PSRR) Class AB amplifier and a Class H amplifier were designed in a 0.24um process for portable audio applications. Using a multiphase buck converter increased the efficiency of the Class H amplifier while still maintaining a fast response time to respond to audio frequencies. The Class H amplifier had an efficiency above the Class AB amplifier by 5-7% from 5-30mW of output power without affecting the total harmonic distortion (THD) at the design specifications. The Class H amplifier design met all design specifications and showed performance comparable to the designed Class AB amplifier across 1kHz-20kHz and 0.01mW-30mW. The Class H design was able to output 30mW into 16Ohms without any increase in THD. This design shows that Class H amplifiers merit more research into their potential for increasing efficiency of audio amplifiers and that even simple designs can give significant increases in efficiency without compromising linearity.
ContributorsPeterson, Cory (Author) / Bakkaloglu, Bertan (Thesis advisor) / Barnaby, Hugh (Committee member) / Kiaei, Sayfe (Committee member) / Arizona State University (Publisher)
Created2013
Description
Preschool teachers have the opportunity to facilitate children's play with a variety of classroom activities. Preschool activities can be categorized as masculine, feminine, and gender-neutral based on children's preferences. Understanding how and why teachers facilitate children's play with feminine, masculine, and gender-neutral activities is important because children's engagement in gender typed activities has been linked to cognitive development. The current study extends previous and outdated research on teachers' engagement in gender-typed classroom activities by using a teacher-focal observational coding system and survey data to assess the frequency at which, with whom, and why teachers facilitate feminine, masculine, and gender-neutral activities. Results reveal teachers facilitate gender-neutral and masculine activities more frequently than feminine activities. However, facilitation of these activities is qualified by with whom the teacher interacts and the classroom context. During free play, teachers facilitate gender-typed activities in stereotypic ways, facilitating masculine activities with boys more than with girls and feminine activities with girls more than with boys. Although, during structured settings, teachers do not facilitate masculine and feminine activities at different frequencies. Finally, in both free play and structured settings, teachers' gender attitudes do not seem to be strong predictors of their facilitation of gender-typed and gender-neutral activities with the exception of teachers' facilitation of feminine activities during structured settings. The present findings address important issues in educational and developmental research by investigating teachers' gendered classroom practices.
ContributorsGranger, Kristen L (Author) / Hanish, Laura (Thesis advisor) / Bradley, Robert (Committee member) / Kornienko, Olga (Committee member) / Arizona State University (Publisher)
Created2014
Description
Class D Amplifiers are widely used in portable systems such as mobile phones to achieve high efficiency. The demands of portable electronics for low power consumption to extend battery life and reduce heat dissipation mandate efficient, high-performance audio amplifiers. The high efficiency of Class D amplifiers (CDAs) makes them particularly attractive for portable applications. The Digital class D amplifier is an interesting solution to increase the efficiency of embedded systems. However, this solution is not good enough in terms of PWM stage linearity and power supply rejection. An efficient control is needed to correct the error sources in order to get a high fidelity sound quality in the whole audio range of frequencies. A fundamental analysis on various error sources due to non idealities in the power stage have been discussed here with key focus on Power supply perturbations driving the Power stage of a Class D Audio Amplifier. Two types of closed loop Digital Class D architecture for PSRR improvement have been proposed and modeled. Double sided uniform sampling modulation has been used. One of the architecture uses feedback around the power stage and the second architecture uses feedback into digital domain. Simulation & experimental results confirm that the closed loop PSRR & PS-IMD improve by around 30-40 dB and 25 dB respectively.
ContributorsChakraborty, Bijeta (Author) / Bakkaloglu, Bertan (Thesis advisor) / Garrity, Douglas (Committee member) / Ozev, Sule (Committee member) / Arizona State University (Publisher)
Created2012
Description
In this thesis, a digital input class D audio amplifier system which has the ability
to reject the power supply noise and nonlinearly of the output stage is presented. The main digital class D feed-forward path is using the fully-digital sigma-delta PWM open loop topology. Feedback loop is used to suppress the power supply noise and harmonic distortions. The design is using global foundry 0.18um technology.
Based on simulation, the power supply rejection at 200Hz is about -49dB with
81dB dynamic range and -70dB THD+N. The full scale output power can reach as high as 27mW and still keep minimum -68dB THD+N. The system efficiency at full scale is about 82%.
to reject the power supply noise and nonlinearly of the output stage is presented. The main digital class D feed-forward path is using the fully-digital sigma-delta PWM open loop topology. Feedback loop is used to suppress the power supply noise and harmonic distortions. The design is using global foundry 0.18um technology.
Based on simulation, the power supply rejection at 200Hz is about -49dB with
81dB dynamic range and -70dB THD+N. The full scale output power can reach as high as 27mW and still keep minimum -68dB THD+N. The system efficiency at full scale is about 82%.
ContributorsBai, Jing (Author) / Bakkaloglu, Bertan (Thesis advisor) / Arizona State University (Publisher)
Created2015
Risk and protective factors of peer victimization: the role of preschoolers' affiliations with peers
Description
Studies of peer victimization typically focus on behavioral characteristics of the victims, and frequently overlook the role that peers may play. The current study extended previous research by examining how time spent with two types of peers (externalizing and socially competent) can serve as a risk or protective factor for preschoolers' victimization, and how victimization may differ for boys and girls. In addition, the study explored how affiliating with same-sex and other-sex externalizing and socially competent peers may differentially relate to victimization. Results showed that girls who affiliated with externalizing female peers were significantly more at risk for victimization. In addition, boys and girls who spent time with socially competent male peers (but not female peers) negatively predicted victimization. The results indicate that children's peers, in certain circumstances, may play an important role in victimization. These findings also highlight the importance of considering children's and peers' gender when studying peer processes.
ContributorsClary, Laura (Author) / Hanish, Laura (Thesis advisor) / Martin, Carol (Committee member) / Updegraff, Kimberly (Committee member) / Arizona State University (Publisher)
Created2011
Description
In preschool, learning often occurs within the context of children’s play activities with various toys and materials. Although much theoretical speculation has occurred, relatively little empirical research has examined how preschoolers’ play activities foster children’s learning and academic skill development. The current study extended previous research on dimensions of adolescent activity involvement to young children in preschool by assessing dimensions of activity involvement across and within curriculum-based and gender-based activity domains. In a longitudinal design, I explored the relation between these dimensions of activity involvement in the fall semester of children’s preschool year and children’s academic outcomes at the end of their preschool year. Participants included preschool children (n = 279; M age = 52 months, 47% girls, 70% Mexican or Mexican-American) from lower socioeconomic status families. Children’s activity involvement was observed, and academic abilities were assessed through child interviews and teacher reports. The results provided little evidence to support the hypotheses that children’s dimensions of activity involvement in the fall semester of their preschool year contributed to their academic abilities in literacy and mathematics at the end of their preschool year. Findings were discussed in terms of the strengths and limitations of the present study. Potentially important steps remain for research on the relation between preschool activity involvement and academic abilities.
ContributorsGoble, Priscilla M (Author) / Hanish, Laura D. (Thesis advisor) / Martin, Carol Lynn (Thesis advisor) / Simpkins-Chaput, Sandra D. (Committee member) / Arizona State University (Publisher)
Created2010
Description
The purpose of this study was to evaluate the effects of parent training in the Enhanced Milieu Teaching with Phonological Emphasis (EMT+PE) intervention program, using telepractice, on parent strategy use and child speech and language outcomes for children with repaired cleft palate with or without lip (CP/L). Four parent child dyads participated in the study. Child participants ranged in age from 28 to 53 months at the beginning of intervention and all had a diagnosis of nonsyndromic CP/L. Participants received two-to-three parent training sessions and twice weekly telepractice intervention sessions. Parents increased their use of EMT+PE strategies throughout intervention with the Modeling and Expansion and Prompting and Recasting strategies resulting in significant intervention effects. Moreover, parents maintained increased strategy use following the conclusion of direct intervention. A positive improvement in child speech and language outcomes was seen across intervention. This study showed that telepractice is an effective service delivery model for parent training and subsequent intervention session in EMT+PE strategy use to support the speech and language development for children with CP/L.
ContributorsEllis, Paige Kathryn (Author) / Scherer, Nancy J (Thesis advisor) / Gray, Shelley (Committee member) / Peter, Beate (Committee member) / Lien, Kari (Committee member) / Arizona State University (Publisher)
Created2022