Using Institutional Data to Identify Students at Risk for Leaving Community College: An Event History Approach
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Community colleges have been criticized for having lower graduation rates than four year colleges, but few studies have looked at non-graduation transfer, in which a student leaves the community college for a four-year college without taking an associate degree. The current study utilizes institutional data and a discrete-time event history model to predict non-transfer attrition in community colleges. The data utilized include five years of institutional data from 21,724 first-time freshmen from the six community colleges of the City University of New York. The study includes students who resided in New York City and its two adjacent suburban counties and who matriculated in the fall of the 2004 and 2005 academic years. Multinomial logistic regression was employed in an event history model of student absence and transfer; models were developed for both the first and second spells. Data on students who transferred were obtained from the National Student Loan Clearinghouse (NSLC). Continuation or type of leaving following each semester constituted the dependent variable. Many of the risk factors for leaving were related to academic performance. Students who were writing proficient and who had higher GPAs and more credit completion were more likely to remain enrolled or to transfer; students who failed were more likely to leave. Notably, course withdrawal was a greater risk factor for leaving than course failure. Financial aid in the form of grants and loans was associated with a decreased risk for attrition, and weekly travel was associated with an increased risk for leaving as well as an increased risk for transfer. Smaller class size and time spent on campus and especially in class was associated with lower risks for attrition. Three models were employed, two of these modeled transfer as separate form of leaving; one included transfer together with graduation and continuation as a successful semester outcome. Parameters obtained from the 2004 cohort were applied to the 2005 cohort to assess each model's predictive validity in a naïve dataset. The most successful model for the first spell correctly identified 34.6 percent of the leavers in the semester in which they left, with a 35 percent false positive rate. The most successful model for the second spell identified 49.6 percent of leavers with a 30.8 percent false positive rate. If a false positive rate of 50 percent is allowed, about 60 percent of leavers in the first spell and about 80 percent of the leavers in second spell can be detected. Remedial study does not present a risk, but the data suggest that remedial education may be using too much of a student's grant money. It is suggested that additional study may be needed to determine how to effectively remediate students in math and writing, and that a model for course withdrawal and failure using interim grades be developed. Since withdrawal and failure present acute risks, it is suggested that a student's fitness and prerequisite skills for courses be assessed prior to course enrollment. Since many of the risk factors are interrelated, it is suggested that a structural model may be needed to assess each predictor's relevance.
Conformational features of the human U2-U6 snRNA complex
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The splicing of precursor messenger (pre-m) RNA, during which noncoding intervening sequences are excised and flanking coding regions ligated, is an integral reaction of gene expression. In eukaryotes, it is carried out by a dynamic RNA-protein complex called the spliceosome, in which five small nuclear (sn) RNA components are actively involved in recognition and chemical aspects of the process. A complex formed between U2 and U6 snRNAs is implicated in the chemistry of pre-mRNA splicing. The catalytic activity of the U2-U6 snRNA complex is dependent on the presence of Mg2+ ions, and the complex has been shown to have several specifically bound Mg2+ binding sites in vitro. The overall goal of this research is to characterize the conformational changes of the human U2-U6 snRNA complex upon addition of Mg2+. In order to pursue this question, we attempted to characterize the lowest energy structure of the complex in the absence of spliceosomal proteins using a combination of biophysical and biochemical techniques in the solution state. We first used enzymatic structure probing to evaluate the secondary structural fold of protein-free human U2-U6 snRNA complex. Cleavage patterns resulting from probing reactions were consistent with formation of four stem regions surrounding the junction, therefore favoring the four-helix model consistent with previous results of in vivo studies of the human U2-U6 snRNA complex. However, 19F NMR studies from our laboratory also identified a lesser fraction (up to 14%) of a three- helix conformation. Upon addition of up to 100 mM Mg2+, a slight increase in cleavage by enzymes specific for both single-stranded and double-stranded regions was observed at the junction region, suggesting that this region is becoming more accessible, perhaps because of an increase in the fraction of the three-helix conformation. Analytical ultracentrifugation studies revealed that the Stokes radius of the RNA complex decreased slightly from 31.3 Å to 27.9 Å in the presence of 100 mM Mg2+, suggesting a slight compaction of the tertiary structure in the presence of divalent metal ions. Hydroxyl radical footprinting experiments on this complex showed signs of increased protection in some areas near and more distant from the junction upon addition of Mg2+, suggesting a change in three-dimensional conformation. Therefore, it appears that Mg2+ induces a small three-dimensional conformational change on human U2-U6 snRNA complex. In order to build a three-dimensional model for the four-helix conformation, we designed a mutant that favors the formation of four-helix conformation and performed SAXS experiments on it. The preliminary SAXS studies suggest that the human U2-U6 snRNA complex and the mutant complex may also be amenable to further study by SAXS. These results act as a good starting point to characterize further the overall global conformation of human U2-U6 snRNA complex and effects of spliceosomal proteins on it.
Aesthetic Autobiography and The Poetics of Despair in Post-War American Literature
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This dissertation repositions "aesthetic" in its ancient Greek context, meaning to apprehend by the senses. The project is framed around my idea of the aesthetic autobiography, a creative work that phenomenologically conveys the embodied experience of its author. I do not use "aesthetic" as a transcendentalist term of critical assessment, as defined by Kant; instead, the term denotes the immanent realm of the senses. This move allows me to connect the aesthetic to affect, whose etymology I trace from the mid 18th Century to contemporary affect theory. I theorize the aesthetic as a dynamic and relational biophysical force. I aim to extend the boundaries of autobiographical "truth" in order to accommodate the feeling body, which exists in excess and often beyond the reach of conceptual language. Specifically, I examine how five post-war authors formally confront the challenge of conveying the sensation of depression. By focusing on formal experiments in rhythm, syntax, structure, imagery, and genre, I look at texts by Allen Ginsberg, Joan Didion, Tim O'Brien, Art Spiegelman, and Darryl Cunningham. Grounding the project in mid-twentieth century America, chapter 1 begins with Edmund Wilson's "The Wound and the Bow" (1941), which situates the psychologically wounded artist as a vital and connective social force. In chapters 2 and 3, I juxtapose the respective approaches of Ginsberg and Didion in articulating the physiological experience of a depressive breakdown. Chapter 4 focuses on The Things They Carried, by Tim O'Brien, as a self-consciously constructed aesthetic autobiography: I show how "postmodernism" responds to representing the sensational body after the "death of the subject" and I argue for its affective possibilities. Finally, in chapter 5, I turn to graphic memoir, with Art Spiegelman's "Prisoner on the Hell Planet" and Darryl Cunningham's Psychiatric Tales: 11 Graphic Narratives of Mental Illness. I explore the formal strategies available to cartoonists in conveying the bodily affect of despair
Genetically Modified Collagen-like Triple helix Protein as Biomimetic Template to Fabricate Metal/Semiconductor Nanowires
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Various metal and semiconductor nanowires have been developed as building blocks for electronics, optics, and sensors devices. Among these, new nanowires developed on biomolecular templates got more attention since the molecular recognition functions of these biomolecules with specific ligands can be employed to immobilize nanowires onto specific locations to establish desired device geometries. In order for their application in electronics, optics, and sensors device fabrications, after configuring device geometries with nanowires by the biomolecular recognition, we focused upon the biomineralization function of peptides on the nanotemplate sidewall to develop various material coatings such as metals and semiconductors for electronics and sensor applications. It should be noted that the coating morphology such as particle-domain size and inter-particle distance on the nanotemplates could be tuned by peptide sequences and conformations. We launched the genetically modified recombinant collagen-like triple helix proteins as a biorecognition, size-controlling and rigid biotemplate. This collagen-like triple helix is the genetically engineered polypeptide assembly that contains a fragment from the natural collagen sequence and has attractive features in hybrid nanomaterials. The length of the protein nanowire is uniform since it is determined by the number of amino acids. The length can be flexible if we genetically modify the sequence, which can also add chemical functionality by the genetic engineering procedure. Genetic engineering is more advantageous than the chemical synthesis for the functionalization /deritivization of peptide nanowire because only the desired specific residue of the peptide is functionalized by the genetic approach. The specific sequence can also increase stability so that the mechanical property can be tuned to be suitable for device application in harsh environment. By using the recombinant technology, it is possible to design and amplify a collagen-like triple helix that is monodisperse, easily mineralized with metal/ semiconductor precursors, and therefore can be applied as a rigid biomolecular template for metal/semiconductor nanowire fabrications. Moreover the production of triple helix can be large scaled up by means of the cell multiplication. As continued work based on previous study of the application of C7 glycylglycine bolaamphiphilic peptide, the self-assembly of doughnut-shaped nanoreactors from monomer peptides with silica precursors was studied, and uniform size silica (SiO2) nanoparticles were obtained. Possible mechanism in terms of chelating and catalysis functions of the peptide was formulated.
The Geometry of Gauss' Composition Law
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Gauss' identification of a composition law for primitive integral binary quadratic forms of given discriminant D--which provides the set FD<\sub> of SL2<\sub>(Z) equivalence classes of such forms with a group structure--essentially amounts to the discovery of the class group of an order in a quadratic number field. We consider quadratic extensions of the field of rational functions k(u), where k is an algebraically closed field, and seek an analogue of Gauss composition in this context. A quadratic extension of k(u) corresponds to the function field of a curve C with affine model t2<\super> = D(u) for some polynomial D = D(u) in k[u], which is of odd degree if and only if C has a smooth ramified point at infinity. Focusing on this case--the analogue of quadratic number fields with one complex place at infinity--we extend the notion of the degree of a Weil divisor on a curve to Cartier divisors on C, and find a bijection between the set of SL2<\sub>(k[u])-equivalence classes of primitive forms with coefficients in k[u] of discriminant D, and the group Pic0<\super>(C) of isomorphism classes of degree zero lines bundles on C. In parallel fashion, we reinterpret the arithmetic case using Arakelov's invention of metrics associated to the infinite places of a number field. Given an invertible R-module L for R a quadratic ring of discriminant D and fraction field K, we have for each infinite place v of K a corresponding one-dimensional C-vector space Lv<\sub>, with a positive non-degenerate hermitian metric. Using a notion of degree of an invertible metrized module--which mirrors the notion of degree used in the geometric case, yielding in both cases a "product formula" deg(f) = 0 for a principal divisor (f)--we establish for D < 0 a bijection between FD<\sub> and the compactified Picard group Picc<\sub>0<\super>(R) of isometry classes of degree zero invertible R-modules.
IMPROVING THE TEACHING AND LEARNING OF SCIENCE IN A SUBURBAN JUNIOR HIGH SCHOOL:ACHIEVING PARITY THROUGH COGENERATIVE DIALOGUES
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The research in this dissertation focuses on ways to improve the teaching and learning of science in a suburban junior high school on Long Island, New York. The study is my attempt to find ways to achieve parity in my classroom in terms of success in science. The goal of parity is for all students to have equal opportunity to enjoy a basic education of high quality, achieve at high levels, and enjoy equal benefits from education. I was specifically looking for ways to encourage Black female students in my classroom and in other classrooms to continue their science education into the upper grades. The participants were the 27 students in the class, a friend of one of the students, and I, as the teacher-researcher. In order to examine the ways in which structure mediates the social and historical contexts of experiences in relation to teacher and student practices in the classroom, I used collaborative research; autobiographical reflection; the sociology of emotions; immigration, racialization, and ethnicity, and cogenerative dialogues (hereinafter, cogens, singular cogen) as tools. Cogenerative dialogues are a way for students and teachers to accept shared responsibility for teaching and learning. This study is of importance because of my school's very diverse student body. The school has a large minority population and therefore shares many of the characteristics of urban schools. In my study I look at why there are so few Black female students in the advanced science course offered by our district and how this problem can be addressed. I used a variety of qualitative approaches including critical ethnography and micro analysis to study the teaching and learning of science. In addition to the usual observational, methodological, and theoretical field notes, I videotaped and audiotaped lessons and had discussions with students and teachers, one-on-one and in groups. In the first year the cogenerative group consisted of two Black female students. In the second year of the study there were four Black and one White-Hispanic female students in the cogen group. Below, I discuss my journey toward a career in science education and explain how I became a teacher-researcher. In my research I studied the interactions of the students between lessons and during laboratory activities as well as the cogens themselves in order to get the data needed to identify the role of science cogens in the learning and teaching of science. The students both in my cogen and in my science class collaborated with me as we worked to create new culture through conversations. I also used cogens to examine the influence of immigration, race, ethnicity, and gender in my science class. The students in the cogen were native-born children of immigrants, known as the second generation and/or 1.5 generation. In the first year one of these students was the daughter of Jamaican-born parents and the other native Black. The students in the second year included one each of Haitian and Jamaican descent, one with Dominican parents, and two native Blacks. Interestingly enough, if I had not conducted the cogenerative dialogues, I might never have become aware of their ethnicities. The cogens helped me to become a better teacher by allowing me to understand what racialization was and how it impacted students as well as teachers. The cogens helped students voice their opinions in a manner and in a place that supported their understanding of both the similarities and differences among students in the class in addition to contradictions in their science class as well as in other nested fields. Contradictions are differences between people and groups that arise as a normal part of social life in the classroom (and elsewhere, of course), and I looked for ways to retain these differences as we learned to deal with them. I looked especially for contradictions that were evident between the larger culture of the school and that of the students in the cogen. I studied the dialectical relationship between agency and structure in my science class and within the cogenerative dialogue group. I found that as students gained agency, they were more successful in obtaining entry into accelerated science classes and succeeded in those classes. I found that some marginalized students were shut down in their classrooms. During the common planning time within the science department, we discussed the lack of minority students in our advanced science classes. I introduced the idea of cogens and described how they could encourage more students to become involved in the process of learning. Although my colleagues did not institute cogens with their students, they did listen to the ideas about culturally relevant teaching which I communicated, and, although I have not witnessed it myself, I was told by some of my colleagues that they were trying to address the cultural mismatch found in their classrooms. The science faculty and I spoke to administrative personnel, and they saw how their goals and ours were aligned. Soon, all stakeholders were on board: my chairperson, the science department, and the administration. For many Black female students in our district, access to advanced science classes was largely unavailable because students had not learned to communicate scientific literacy in ways that were recognized and acknowledged in our school district. My research supports the theory and research that point to the desirability of building positive emotional energy through chains of interactions and transactions that produce success among most, if not all, participants. This study increases the understanding of the structure of interactions in a science class by building understanding of the face-to-face encounters associated with organizing, establishing, and maintaining conversations. As a teacher-researcher, I found that cogenerative dialogues also helped to create emotional energy and student engagement as well as synchrony and entrainment among students in the cogen and in the classroom. A community of learners formed, and this contributed to a positive learning environment. This environment in turn produced positive emotional energy and community. Cogenerative dialogues became a tool to build community in my science class. It also became a tool to introduce a new way of teaching and learning to me as well as to my colleagues. I began discussing the use of cogens in my science department meetings so that, by understanding different ways of thinking and being, my colleagues and I might find ways to transform science education at our school. Becoming aware is an important step for teachers and students to use their cultural capital to eliminate practices that prevent students from connecting with science. In cogens teachers and students can identify important shared classroom experiences and together fashion new roles for each of them. Teacher-researchers can effect change in their classrooms and, by letting others in the school and academic community become aware of their research, effect change in other schools as well. The results of the latest Regents exam have convinced the administration, the math, and the science departments as well as other faculty members of my junior high school that, when all stakeholders are involved, change can happen. The students who had been marginalized were as successful in the advanced science classes as those who were not. My school district took note of this and proudly continues the program.
Women in Foreclosure: Social Reproduction & Mortgage Strain in the Subprime Era
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Advisor: Professor Mimi Abramovitz This research captures the experiences of 31 single female homeowners with risky lending markets and mortgage foreclosure in the city of Philadelphia. In-depth, semi-structured interviewing was employed to build knowledge about single women's experiences with seeking a loan, buying a home, entering default and attempting to stall foreclosure. Thematic analysis of the data demonstrated that risky lending and foreclosure did not mark the onset of financial instability among study participants. Instead, it functioned as a tipping point for single women unable to access upward mobility and asset accrual throughout the lifespan. Women's status as the strongest members of a financially fragile network interacted with holes in the social safety net, lack of protective legislation and lending policies that placed them at risk of foreclosure. The research also indicates that the privatization of social reproduction acted as an amplifier and conduit of market risk that extends the responsibility for unpaid care work well into older adulthood. As a result, social reproduction revisited the homeowners either exacerbating or contributing to foreclosure and the early onset of disease and disability before women were eligible for Medicare and Social Security. When homeowners experienced mortgage strain they all negotiated with their lenders, increased hours at work, employed strict household budgeting and sought aid from social services to offset mortgage costs. Black homeowners (n=15) immediately searched for assistance, while White homeowners (n=15) were comparatively slower to contact housing counselors and service agencies. Despite these variations, when and how a homeowner searched for aid did not meaningfully alter the onset of default. To date, foreclosure policy and practice interventions have been predicated on an assumption that the onset of foreclosure is an isolated market event. In contrast, the women's lived experiences within risky markets and their personal encounters with the threat of default are tied to a larger context shaped by the prevailing gender division of labor, the erosion of assets and health within the context of a poorly resourced network, the failing safety net and the resulting shift of market risk onto female homeowners.
Attention shapes our expectations and perceptions: The neural mechanisms of top-down attention during adulthood and development
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Top-down attention is the focusing of attention at one's will through knowledge regarding a current task. There is evidence that top-down attention involves the modulation of sensory cortices by higher order regions. However, the mechanisms of top-down attention across sensory modalities, its influence on early sensory inputs, as well as interactions with motivational systems remain unclear. We performed the following set of electrophysiological experiments in typically developed adults and adolescents to examine these areas. 1) The supramodal attentional theory holds that parietally-based attentional mechanisms are shared across sensory modalities. We tested the supramodal theory by examining if lateralized parieto-occipital alpha-band activity, an established metric of top-down spatial attention, was observed in an audiospatial and visuospatial task. In support of the supramodal theory, we observed similar anticipatory alpha-band processes across auditory and visual tasks, but we also found an interaction of supramodal and sensory-specific attentional control processes. 2) There is evidence that top-down attention influences information immediately upon its arrival to sensory cortices, although there is debate in this area. In the current work, volitionally-driven top-down attention was engaged toward one of several overlapping surfaces in an illusion, in which the perceived brightness of the attended surface was enhanced. We observed the attentional enhancement of early visual evoked potentials, indicating that top-down attention shapes the earliest activations in visual cortices. 3) It is well known that motivation impacts attention, but the neural bases of these interactions remain unclear. We examined how level of interest in stimuli influenced top-down spatial attention mechanisms in typically-developing adolescents. Motivation enhanced established attentional processes during the anticipation of high vs. low interest stimuli, but also independently influenced frontal and parieto-occipital activations. These findings provide potential implications to inform clinical measures to improve impaired attentional processes in clinical populations (e.g. individuals with autism spectrum disorders). In sum, these studies revealed the powerful influence of top-down attentional control and its interacting systems on neural activations through several stages of anticipatory and post-stimulus processing during development and adulthood.
Reclaiming Space: Buildings in Modernist Literature and Film
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This dissertation argues that modernists like Virginia Woolf, T. S. Eliot, and Alain Resnais construct literary and filmic works that rely on interruptions and elliptical narration to gesture towards an aesthetics of modernity that counters the interest in monoliths concurrently shown by architectural modernism. This is particularly evident in the context of the war memorial, where regimented public memory is countered by the artistic works discussed through their emphasis on private memorials that are changeable, contingent, and mutable. This is a fundamentally altered vision of twentieth century modernity than that embraced by the architectural mode.
INTERACTIONS OF EUKARYOTIC TRANSLATION INITIATION FACTORS AND 3' UNTRANSLATED REGION OF BARLEY YELLOW DWARF VIRUS mRNA DURING PROTEIN SYNTHESIS: A STUDY OF EQUILIBRIUM BINDING, KINETICS AND THERMODYNAMICS
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Eukaryotic initiation factor (eIF) 4F binding to mRNA is the first committed step in cap-dependent protein synthesis. Barley Yellow Dwarf Virus (BYDV) employs a cap-independent mechanism of translation initiation which is mediated by a structural element BTE (BYDV translation element) located in the 3' UTR of its mRNA. eIF4F bound the BTE and a translational inactive mutant with high affinity; thus questioning the role of eIF4F in translation of BYDV. To examine the effects of eIF4F in BYDV translation initiation, BTE mutants with widely different in vitro translation efficiencies ranging from 5-164% compared to WT were studied. Using fluorescence anisotropy to obtain quantitative data, we show 1) the equilibrium binding affinity (complex stability) correlated well with translation efficiency, whereas the "on" rate of binding did not. 2) other unidentified proteins or small molecules in wheat germ extract (WGE) prevented eIF4F binding to mutant BTE but not WT BTE. 3) BTE mutants-eIF4F interactions were found to be both enthalpically and entropically favorable with an enthalpic contribution of 52-90% to delta G° at 25°C suggesting hydrogen bonding contributes to stability and 4) in contrast to cap-dependent and tobacco etch virus (TEV) Internal Ribosome Entry Site (IRES) interaction with eIF4F, PABP did not increase eIF4F binding. Further, the eIF4F bound to the 3' BTE with higher affinity than for either m7G cap or TEV IRES, suggesting that the 3' BTE may play a role in sequestering host cell initiation factors and possibly regulating the switch from replication to translation. In another project, we studied the interaction of a deletion mutant of wheat eukaryotic initiation factor 4B (eIF4B320-527) with zinc using the biophysical technique of circular dichroism. eIF4B is suspected to be a metalloprotein and it is known that zinc stimulates eIF4B self-association at physiological concentrations . It was found that in the presence of zinc there is significant change in the secondary structure of eIF4B320-527. There was approximately a 70% change in the presence of 500 &muM zinc and around 38% change in the presence of 500 &muM magnesium in alpha content as compared to native protein. There was a change observed in beta sheet content. The changes in secondary structure caused by zinc may be the one of the causes for the eIF4B self-association or enhanced eIF4B-PABP interaction. These results enhance our understanding of the molecular mechanisms by which cell controls translation initiation which is the rate limiting step of cellular protein synthesis.