University of Maryland, Baltimore County
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Stop the Lies. Let the Truth Be Told!: Education Reform and the Save Our Schools March and National Call to Action (SOS)
No full textEmbedded in the Social Constructionist tradition, this study examines the dynamics and interactions of the Discourses and forces of the current U.S. education reform movement as it is shaped by and through Media, Money and Government Discourses which negatively frame teachers as the problem. Using the interview and observation data, this qualitative study uses ethnographic methods to examine the 2011 Save Our Schools March and National Call to Action (SOS), revealing how SOS attempted to complexify the current reform narrative and construct a narrative from the voices of teachers, students and parents in an attempt to present them as legitimate participants in public policy debate and formation. SOS advocates for a reform narrative that includes a Democratic, Grassroots and Sustainable Discourse for and by local stakeholders. An Autoethnography is included as the embodied experience of an American public school teacher and argues for the teachers' right to be critical participants in the narrative of education reform in the United States. Finally, the American Public Education Complex (APEC) is introduced and presented as a framework of factors that contribute to the overall educational development of a student and should be considered in any reform narrative because of the complex and often polarizing ideological American landscape
Efficiency Improvements in Numerical Methods for Studying Connectivity in a Model of a Pancreatic Islet of Heterogeneous Beta Cells
No full textDiabetes is a disease characterized by a high concentration of glucose in a person's blood stream caused by either an insulin deficiency or insulin resistance. Insulin is a hormone produced in the pancreas that regulates the concentration of glucose in the blood stream. The endocrine system of the pancreas contains clusters of cells called islets of Langerhans. In this thesis we study the effects of the distribution of slow bursting and fast bursting beta-cells on the behavior of cells in an islet. We introduce a measure of connectivity based on the fraction of neighboring cells with speed different from the cell's own speed. This quantitative measure of connectivity provides an ordering of the different distributions of slow and fast cells. The dynamics of beta-cells are modeled with a seven variable and a three variable model which consist of coupled ordinary differential equations. A computational islet, a three-dimensional cube of beta-cells, is used to simulate an islet. We find that for both the three variable and seven variable models, as the connectivity of the islet increases the coupling strength at which the burst period of the cells is largest increases. We use Matlab's ode15s function that implements the numerical differentiation formulas, a well-respected and efficient ODE method for stiff initial value problems, in this simulation and demonstrate several orders of magnitude improvement in runtimes by making improvements to the code, in particular by providing a Jacobian in sparse storage mode
Statistical Validation of Surrogate Endpoints Using Equivalence Testing
No full textIn randomized clinical trials, the evaluation of potential surrogate endpoints is very important, since a successful surrogate endpoint will reduce follow-up trial time and/or will reduce the number of patients needed to establish a certain treatment effect. We investigate the statistical validation of different types of surrogate endpoints: continuous and binary. For statistical validation of continuous endpoints, an alternative formulation is proposed for testing the fourth criterion due to Prentice (1989). The set up considered consists of normally distributed endpoints, and the model used is the bivariate normal model in Buyse and Molenberghs (1998). In such a set up, Prentice's fourth criterion involves inference concerning an appropriate regression parameter, and the criterion holds if the regression parameter is zero. Testing such a null hypothesis has been criticized in the literature since it can only be used to reject a poor surrogate, and not to validate a good surrogate. In order to circumvent this, an equivalence hypothesis is formulated for the regression parameter, namely the hypothesis that the parameter is equivalent to zero. Such an equivalence hypothesis is formulated as an alternative hypothesis, so that the surrogate endpoint is statistically validated when the null hypothesis is rejected. Confidence intervals for the regression parameter, and tests for the equivalence hypothesis are proposed using bootstrap methods and small sample asymptotics, and their performances are numerically evaluated and recommendations are made. The choice of the equivalence margin is a regulatory issue that needs to be addressed. The proposed equivalence testing formulation is also adopted for other parameters that have been proposed in the literature on surrogate endpoint validation, namely, the relative effect and proportion explained. For the statistical validation of binary endpoints, we consider the logistic regression model used in Buyse and Molenberghs (1998). In the current literature, the regression coefficient associated with the interaction between treatment and the surrogate endpoint is tested first. If the regression coefficient is found to be close to zero, it is dropped from the model and the regression coefficient associated with the surrogate endpoint is then tested. We propose simultaneous testing of the interaction coefficient and the coefficient associated with the surrogate, formulated as an equivalence hypothesis, which when rejected would ensure that the surrogate endpoint is validated. Tests for the hypothesis are proposed using bootstrap methods and generalized confidence intervals, and their performances are numerically evaluated and recommendations are made
Synthesis of Hydrophobically Modified Nucleotide Analogs and their Incorporation into Oligonucleotides for Enhanced Chromatographic Separations
No full textLipophilic nucleosides and oligonucleotides have been found to have an extensive range of applications. They have shown a wide variety of antiviral and antitumour activities and represent a new class of drug carriers for diagnostic and therapeutic applications. Lipophilic nucleosides and oligonucleotides are involved in the formation of monolayer films, micelles and/or vesicles, organogels or multilamellar layers and have a wide variety of biotechnological (eg. chip technology) and chromatographic applications. The objective of this project was to synthesize hydrophobically modified nucleotide analogs and incorporate them into oligonucleotides with the objective of achieving enhanced chromatographic separations. The synthesis of these analogs was achieved by introducing lipophilic functionalities at the 5'- position of deoxythymidine, a pyrimidine deoxynucleoside, commonly called thymidine. The scheme that evolved over the course of synthesis involved TBS-protection of commercially available Thymidine at both the 3' and 5' hydroxyl groups, selective 5'-deprotection, 5'-tosylation, substitution of tosyloxy group by primary amines (CH3(CH2)nNH2, where n = 3,7,11,17), acylation of the resulting 5'-amino 5'-deoxythymidine analogs with palmitoyl chloride and conversion of each of these analogs into their corresponding 3'-phosphoramidite derivatives. This was followed by incorporating these modified phosphoramidite analogs into an oligomeric sequence at the 5'-end by carrying out solid phase oligonucleotide synthesis. The oligomeric sequence chosen for incorporation of the modified thymidine phosphoramidite analogs was the human telomere nucleotide sequence, namely the telomeric repeat: 5'-TTAGGG-3' resulting in a heptameric sequence of T'TTAGGG where T' stands for the hydrophobically modified deoxythymidine analogs. Thus, the synthesis of four different lipophilically modified heptameric oligonucleotides was achieved and their characterization established using mass spectrometry. The lipophilic oligomers, which have structural similarity to an amphiphile, are proposed to have a reversible non-covalent interaction with the reverse phase surface of the C18-modified sorbent system by insertion of their lipophilic tails into the hydrophobic surface of the sorbent. Both solution and solid phase hybridization/binding studies were carried out. Solution phase binding/hybridization studies showed an interaction/binding between the modified oligonucleotides and their normal complementary strands by recording a decrease in absorbance at 260 nm(A260) with decrease in temperature. Retention/Adsorption properties of the modified as well as normal oligonucleotides on reverse phase sorbent systems were studied. ENVI-C18 discs were used and subsequently abandoned as the sorbent system of choice because they retained both the modified and normal oligonucleotides in equal measure and showed no selectivity. Also the glass microfiber discs lost their physical integrity when exposed to the analyte solution. Reverse Phase ZipTips were used as an alternative sorbent phase and it was found that the percent retention/adsorption of the lipophilic (modified) oligonucleotide under a given condition of temperature and/or ionic strength is appreciably greater than the percent retention of the normal unmodified complementary strand. Also, it was found that the increase in percent retention/adsorption of the modified oligomers with increase in temperature and/or ionic strength was greater than the increase observed with the normal unmodified complementary strands. It was observed that the RP sorbent phase preloaded with the modified oligomer showed a greater percent retention of the normal complementary strand under given conditions of temperature and/or ionic strength relative to the percent complementary strand retained when the RP sorbent phase is preloaded with the unmodified control oligomer . It was also observed that the modified oligomer analog with the longest hydrophobic chain length showed greatest percent retention on the reverse phase sorbent system, namely the RP ZipTips
The Optimism to Overcome: Educational Beliefs and Strategies Of Resilience Among African American College Graduates Who Are Former Teenage Mothers.
No full textThe purpose of this study is to examine the real-life experiences and narratives of African American, former teenage mothers who have earned college degrees. The Resiliency theory and the Intersectionality paradigm provide the framework for this qualitative research study. The Resilience theory explores the processes employed by the women in this study to successfully balance the multiple demands of being a parenting-student. Through the lens of Intersectionality, this study examines how issues of race, class and gender impacted the academic trajectories of African American, former teenage mothers. The 20 women in this study participated in an interview about their experiences as students before, during and after their first childbirth. In addition, the women discussed the impact motherhood had on their academic ambitions. The data first reveals that the attitudes, beliefs and values held about education by the women were not negatively impacted by their pregnancies or childbirth. Instead, early childbearing strengthened their desire to academically excel. In addition, this research shows that the women utilized a variety of strategies of resilience created by both their internal support systems and offered by external structural opportunities, as they successfully managed the numerous and sometimes competing demands of being parenting-students. Lastly, the study examines the psychosocial impact of academic success and social mobility on these women
Detecting cognitive stress and impairment using keystroke and linguistic features of typed text: Toward a method for continuous monitoring of cognitive status
No full textSystems that can detect cognitive decline or harmful levels of stress could assist users in managing their stress and health. However, current assessments are often obtrusive or require specialized equipment, and not suited to continuous monitoring of cognitive status. This research leverages attributes of everyday keyboard interactions to proactively and continuously monitor cognitive function. A laboratory study was conducted where typing samples were collected to explore the effects of stress, age, and cognitive impairment on interaction patterns. Keystroke and linguistic features were extracted from the samples and models were constructed for each group as well as for nine individual participants. Correct classification rates were 60% for stress in younger adults, 60.5% for stress in older adults, 79.1% for age, 78.6% for cognitive impairment, and ranged from 62% to 88% with a mean of 72% for stress in individuals. This research contributes a unique combination of features for text and keystroke analysis, enhances understanding of how stress and cognitive impairment affect typing patterns, and has implications for systems for health monitoring. Further research includes exploration of additional keystroke and linguistic features, further interaction techniques, study of varied levels and types of stress, and a longitudinal study of cognitive decline
The influence of event-level factors and processes of change on safe sex and alcohol use among HIV+ men who have sex with men
No full textThis study involved secondary analyses of data from Positive Choices, a randomized clinical trial of a combined Motivational Interviewing and stage-based peer group intervention designed to reduce alcohol use and unprotected sexual behavior in a sample of 253 HIV+ men who have sex with men (MSM). The primary aims sought to examine factors influencing the occurrence of heavy alcohol use and unprotected anal sex factors across the study, focusing on sexual-event level (i.e., each sexual event day) and participant-level (i.e., participant characteristics) as well as the effects of the intervention and processes of change based on the Transtheoretical Model of Intentional Behavior Change. Major findings included an effect of main partner-type and an interaction between casual partner-type and depressive symptoms on unprotected anal sex at baseline, as well as evidence of complex relations between baseline behavior, younger age, and processes of change for safe sex and alcohol use in predicting same-day heavy alcohol use and unprotected anal sex across the 12-month study follow-up. Implications of these findings for future research and interventions targeting HIV+ MSM are discussed
Hilltop: A Historic African American Community
No full textIn 1969, Howard County built Hilltop, a public housing development for the local African American community who lived on Fels Lane in Ellicott City. This community lived in substandard housing: many houses lacked proper fire safety and sanitation facilities. In the 1960s, the community organized around the issue of decent housing; it created the Fels Lane Neighborhood Association and the Ellicott City Civic Club with the goal of not only appealing to the County to build better housing, but have representation in development planning. When Howard County demolished Hilltop in 2011, it not only dislocated a strong community, but evidence of local African American history. This thesis addresses the history of the Fels Lane community, specifically housing related community activism, and argues that demolished places such as Fels Lane and Hilltop are anchors of memory for local African American communities. Interpreting the history of these places reveals how black communities responded to housing discrimination. Included are oral history transcripts and drafts of historic signage for on-site interpretation of community activism
Metabolic analysis revealed EDS5 being the convergent point of the biosynthesis of salicylic acid and lignin in Arabidopsis
No full textPlant pathogens are responsible for millions of dollars in agriculture loss each year. A thorough understanding of how plants activate defense mechanisms is an essential part to developing strategies to improve plant resistance. The small phenolic compound salicylic acid (SA) plays a key role in the regulation of plant defense. Among the genes that regulate SA accumulation, ENHANCED DISEASE SUSCEPTIBILITY 5 (EDS5), has been shown to play a major role to affect SA biosynthesis. EDS5 encodes a MATE transporter that presumably transports small organic compounds. The lack of eds5 leads to much reduced SA accumulation and enhanced disease susceptibility to pathogens. In contrast, EDS5 overexpression confers enhanced disease resistance in plants. Thus it has been suggested that EDS5 transports a precursor(s) critical for the SA biosynthesis. In an HPLC analysis of the SA profile of the eds5-3 mutant, we noticed that there were extra peaks that presented in eds5-3 but not in wild-type plants. We hypothesize that the extra peaks represent the compounds accumulated in eds5-3 due to the lack of the transporter function and identification of such compounds could lead to the elucidation of EDS5 substrate(s). Therefore, we analyzed the metabolic profile of the eds5-3 mutant and Col-0 as a control, using UPLC-MS. Unexpectedly, we found that eds5-3 completely lacks sinapoyl malate, a secondary metabolite in the phenylpropanoid pathway critical for lignin biosynthesis. Sinapoyl malate protects plants against ultraviolet (UV) light from the sun and causes plant leaves to appear blue-green under UV illumination. Consistent with this role of sinapoyl malate, we found that eds5-3 fluoresces red-orange under UV and is more sensitive to UV-light irradiation. This discovery of eds5-3 suggests that EDS5 represents the convergent point of the biosynthesis of SA and lignin. Further elucidation of the substrate(s) of EDS5 would lead to a better understanding of both SA and lignin biosynthesis pathways, eventually a better control of defense and lignin content of plants