Matching Items (12)
Filtering by
- Creators: Arizona State University
- Creators: Chakraborty, Bijeta
- Member of: ASU Electronic Theses and Dissertations
Description
Ethnic identity has consistently been associated with Latino youths' psychosocial well-being; however, an area that has received much less attention is how parents' characteristics inform their ethnic socialization efforts and, in turn, youths' ethnic identity. In addition, we know little about how this process unfolds in specific at-risk samples of youth, such as adolescent mothers. Thus, the current prospective study examined how mothers' cultural characteristics informed adolescents' and mothers' reports of ethnic socialization, and how this, in turn, informed adolescents' ethnic identity exploration and resolution among a sample of 193 adolescent mothers and their mothers. In addition, the current study tested whether mothers' ethnic identity affirmation was directly related to adolescents' ethnic identity affirmation over time. Results indicated that mothers' familism was associated with increases in mothers' reports of maternal ethnic socialization, and, in turn, with increases in ethnic identity exploration for foreign-born adolescents, and decreases in ethnic identity exploration for U.S.-born adolescents. In addition, adolescents' reports of familial ethnic socialization were associated with increases in their ethnic identity exploration and resolution. Finally, mothers' ethnic identity affirmation was associated with increases in adolescents' ethnic identity affirmation. Findings are discussed with special attention to the importance of mothers' cultural values in how they socialize their adolescents, and this impact on adolescents' ethnic identity, as well as the implications this study has for interventions focused on bolstering positive outcomes for adolescent mothers.
ContributorsDerlan, Chelsea L (Author) / Umaña-Taylor, Adriana J. (Thesis advisor) / Knight, George P. (Committee member) / Updegraff, Kimberly A. (Committee member) / Arizona State University (Publisher)
Created2012
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
Mexican-origin adolescent females have the highest birthrate of all other ethnic groups in the U.S. Further, teen mothers are at significant risk for poor outcomes, including low educational attainment. Therefore, examining predictors of Mexican-origin teen mothers' educational attainment was the main goal of the current study. Future-oriented beliefs such as educational aspirations and expectations are suggested to have positive implications for adolescents' educational attainment in general. Therefore, guided by bioecological, social capital, status attainment, social learning, and collective socialization of neighborhood theories, the current study examined neighborhood, maternal, and cultural predictors of 190 Mexican-origin parenting adolescents' educational aspirations, expectations, and attainment. With respect to maternal predictors, the study examined mother figures' (i.e., grandmothers') educational attainment, and aspirations and expectations for the adolescent as predictors of adolescents' educational attainment. Using a multi-informant, longitudinal analytic model, results suggest that adolescents' educational expectations, rather than aspirations, significantly predicted adolescents' attainment one year later. Additionally, grandmothers' educational attainment was indirectly associated with adolescents' educational attainment via the educational expectations of both the grandmother and the adolescent. Further, the neighborhood context indirectly informed adolescents' educational attainment via both grandmothers and adolescents' educational expectations. Finally, adolescents' ethnic identity affirmation was significantly associated with adolescents' educational attainment two years later. Implications regarding the importance of educational expectations and ethnic identity affirmation for at-risk parenting adolescents' educational attainment will be discussed.
ContributorsHarvey-Mendoza, Elizabeth C (Author) / Umaña-Taylor, Adriana J. (Thesis advisor) / Updegraff, Kimberly A. (Committee member) / White, Rebecca (Committee member) / Arizona State University (Publisher)
Created2014
Description
The primary aim of this study was to investigate resilient profiles in low-income Mexican American (MA) mothers. MA mothers are part of an under researched population, the fastest growing ethnic minority group, and have the highest birth rate in the United States, presenting a significant public health concern. The transition to motherhood can be an emotionally and physically complex time for women, particularly in the context of a stressful low-income environment. Although most low-income women navigate this transition well, a significant number of mothers develop moderate to severe depressive symptoms. The proposed research investigated profiles of resilience during the prenatal period using a person-centered approach via latent profile analysis. In alignment with current resilience theories, several domains of resilience were investigated including psychological, social, and cultural adherence (e.g., maintaining specific cultural traditions). Concurrent prenatal depressive symptoms and stress were correlated with the profiles in order to establish validity. Six week postpartum depressive symptoms and physiological processes (e.g., overall cortisol output, heart rate variability, and sleep) were also predicted by the prenatal resilient profiles. The resulting data revealed three separate profiles: low-resource, high-resource Anglo, and high-resource Mexican. These resilience profiles had differential associations with concurrent depressive symptoms and stress, such that women in the high-resource profiles reported less depressive symptoms and stress prenatally. Further, profile differences regarding cortisol output, resting heart rate variability, were also found, but there were no differences in insomnia symptoms. Profile classification also moderated the effects of prenatal economic stress on postpartum depressive symptoms, such that women in the high-resource Mexican profile were at risk for higher postpartum depressive symptoms under high economic stress compared to the high-resource Anglo group, which demonstrated a more resilient response. Overall, the results suggest the presence of multiple clusters of prenatal resilience within a sample of MA mothers facing health disparities, with various effects on perinatal mental health and postpartum physiological processes. The results also highlight the need for multi-dimensional models of resilience and the possible implications for interventions.
ContributorsGress Smith, Jenna L (Author) / Luecken, Linda J. (Thesis advisor) / Gonzales, Nancy (Committee member) / Okun, Morris (Committee member) / Zautra, Alex (Committee member) / Arizona State University (Publisher)
Created2014
Description
Low-income Mexican American women face significant risk for poor health during the postpartum period. Chronic stressors are theorized to negatively impact mental and physical health outcomes. However, physiological factors associated with increased self-regulatory capacity, such as resting heart rate variability, may buffer the impact of stress. In a sample of 322 low-income Mexican American women (mother age 18-42; 84% Spanish-speaking; modal family income $10,000-$15,000), the interactive influence of resting heart rate variability and three chronic prenatal stressors (daily hassles, negative life events, economic stress) on maternal cortisol output, depressive symptoms, and self-rated health at 12 weeks postpartum was assessed. The hypothesized interactive effects between resting heart rate variability and the chronic prenatal stressors on the health outcomes were not supported by the data. However, results showed that a higher number of prenatal daily hassles was associated with increased postpartum depressive symptoms, and a higher number of prenatal negative life events was associated with lower postpartum cortisol output. These results suggest that elevated chronic stress during the prenatal period may increase risk for poor health during the postpartum period.
ContributorsJewell, Shannon Linda (Author) / Luecken, Linda J. (Thesis advisor) / Lemery-Chalfant, Kathryn (Committee member) / Perez, Marisol (Committee member) / Arizona State University (Publisher)
Created2015
Description
Postpartum depression (PPD) is a significant public health concern affecting up to half a million U.S. women annually. Mexican-American women experience substantially higher rates of PPD, and represent an underserved population with significant health disparities that put these women and their infants at greater risk for substantial psychological and developmental difficulties. The current study utilized data on perceived stress, depression, maternal parenting behavior, and infant social-emotional and cognitive development from 214 Mexican-American mother-infant dyads. The first analysis approach utilized a latent intercept (LI) model to examine how overall mean levels and within-person deviations of perceived stress, depressive symptoms, and maternal parenting behavior are related across the postpartum period. Results indicated large, positive between- and within-person correlations between perceived stress and depression. Neither perceived stress nor depressive symptoms were found to have significant between- or within-person associations with the parenting variables. The second analysis approach utilized an autoregressive cross-lagged model with tests of mediation to identify underlying mechanisms among perceived stress, postpartum depressive symptoms, and maternal parenting behavior in the prediction of infant social-emotional and cognitive development. Results indicated that increased depressive symptoms at 12- and 18-weeks were associated with subsequent reports of increased perceived stress at 18- and 24-weeks, respectively. Perceived stress at 12-weeks was found to be negatively associated with subsequent non-hostility at 18-weeks, and both sensitivity and non-hostility were found to be associated with infant cognitive development and social-emotional competencies at 12 months of age (52-weeks), but not with social-emotional problems. The results of the mediation analyses showed that non-hostility at 18- and 24-weeks significantly mediated the association between perceived stress at 12-weeks and infant cognitive development and social-emotional competencies at 52-weeks. The findings extend research that sensitive parenting in early childhood is as important to the development of cognitive ability, social behavior, and emotion regulation in ethnic minority cultures as it is in majority culture families; that maternal perceptions of stress may spillover into parenting behavior, resulting in increased hostility and negatively influencing infant cognitive and social-emotional development; and that symptoms of depressed mood may influence the experience of stress.
ContributorsCiciolla, Lucia (Author) / Crnic, Keith A (Thesis advisor) / West, Stephen G. (Thesis advisor) / Luecken, Linda J. (Committee member) / Presson, Clark C. (Committee member) / Arizona State University (Publisher)
Created2014
Description
This multiple case study examined Mexican mothers' beliefs on social and moral development in light of their adaptation to the United States. Super and Harkness' (1986, 2002) ecocultural framework and more specifically, the concept of the developmental niche, guided the analysis. Participants were five Mexican immigrant mothers living in the Phoenix metropolitan area with children between three and four years old. Using participant observation, mothers were shadowed during the day for a period of nine months and were interviewed four times. Additionally, a Q-sort activity on cultural values and a vignette activity were conducted. Evidence of continuity in the importance given to traditional beliefs such as being "bien educado" (proper demeanor) and showing "respeto" (respect) was found. However, the continuity on the teaching of cultural values was accompanied by changes in beliefs and practices. The traditional construct of a "chipil child" (a needy, whiny child) was connected to the idea that mothers somehow need to restrict how much affection, time and gifts they give to their children. This concern was in turn related to the higher access to consumption goods in the United States. It is argued that acculturation is lived differently by mothers, according to their educational attainment, use of expert advice and contact and knowledge with American mainstream culture.
ContributorsFuster, Delia Tamara (Author) / Arzubiaga, Angela (Thesis advisor) / Tobin, Joseph (Committee member) / Nakagawa, Kathryn (Committee member) / Arizona State University (Publisher)
Created2012
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
The goal of this study is to contribute to the understanding of Mexican-American three- to five-year-old children’s effortful control (EC) and negative emotionality (NE) development by examining whether Mexican-American adolescent mothers’ parenting transacts with their three- to five-year-old children’s EC and NE and by exploring whether mothers’ familism acts as a protective factor. I hypothesized that mothers’ harshness and warmth would transact with EC and NE over time. I further hypothesized that mothers’ familism values would (a) positively predict mothers’ warmth and negatively predict mothers’ harshness, and (b) act as a buffer between low EC and high NE, and high harshness and low warmth. These hypotheses were tested within a sample of Mexican-American adolescent mother-child dyads (N = 204) and assessed longitudinally when children were 36, 48, and 60 months. Mothers were predominantly first generation (i.e., mothers’ parents were born in Mexico; 67%) and spoke English (65%). When children were 36 months, average family income (i.e., wages, public assistance, food stamps) was $24,715 (SD = $19,545) and mothers had started community college (13%) or completed high school/GED (30%), 11th grade (19%), 10th grade (8%), or less than 9th grade (14%). In this sample, transactions between harshness or warmth and EC or NE were not found, but a bidirectional association between NE and harshness was found. Familism marginally negatively predicted harshness, but not warmth. Familism moderated the relation between NE and harshness such that there was only a negative relation between NE and harshness when familism was high. However, familism did not moderate the relations between NE and warmth, or EC and harshness or warmth. The results of this study are discussed with respect to (a) current methodological limitations in the field, such as the need to test or develop parent-report measures of Mexican-American children’s temperament and value-driven socialization goals, (b) future avenues for research, such as person-centered studies of clusters of mothers’ values and how those relate to clusters of parenting behaviors, and (c) implications for interventions addressing parenting behavior of adolescent mothers.
ContributorsBerger, Rebecca H (Author) / Wilkens, Natalie (Thesis advisor) / Spinrad, Tracy (Committee member) / Updegraff, Kimberly (Committee member) / Crnic, Keith (Committee member) / Arizona State University (Publisher)
Created2018
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