Three essays on the impact of student assignment policies

This dissertation is comprised of three essays, which study the impact of student assignment policies. The first two papers investigate the impacts of the removal of school desegregation plans on school racial segregation and on ninth grade repetition rates in the U.S. The third paper examines the impact of the school choice policy in Seoul, Korea on school segregation by academic performance levels. Over the last two decades, half of school districts that were subject to court desegregation orders in the U.S. were released from those court orders. In response, many school districts modified student assignment plans that had been adopted to integrate public schools. Chapter 1 documents the changes in school desegregation plans and examines the effect of the changes on racial school segregation in approximately 100 school districts. Analysis of student enrollment data from 1988 to 2012 suggests that recent changes in student assignment plans caused a moderate increase in school racial segregation. The results of additional analysis of the types of policy changes suggest that the overall effect on school segregation is driven by the school districts that replaced school desegregation plans with neighborhood-based assignment plans. Districts that replaced race considerations with socioeconomic factors and that expanded school choice options did not experience an increase in school segregation. Chapter 2 examines the impact of the changes in school desegregation plans documented in the Chapter 1 on ninth grade repetition rates in the same districts. Analysis of data from 1988 to 2012 suggests that the removal of school desegregation plans caused a statistically significant increase in the ninth grade repetition rates of about 0.2 standard deviations. I also find that the impact on the ninth grade repetition rates is driven by the school districts where school segregation was substantially increased due to the changes in desegregation policies. The impact on the ninth grade repetition rate is driven by the school districts where school segregation was substantially increased by the changes in desegregation policies. In addition, I find no evidence that the desegregation policy changes affect student movements from other districts or private schools. Chapter 3 examines the impact of school choice policy in Seoul, Korea on school segregation by student performance levels. Seoul, Korea replaced random assignment of schools with school choice in 2010. By exploiting the policy change, this paper examines the effect of school choice on student sorting by ability. I find that schools became segregated by student performance levels following the implementation of the school choice policy in Seoul. The results of this paper suggest that school choice increases school segregation by academic performance levels even in a racially homogenous country

Toward a conceptual framework for data sharing practices in social sciences: A profile approach. In the proceedings of the ASIS&T 2016 Annual Meeting

This paper investigates the landscape of data-sharing practices in social sciences via the data sharing profile approach. Guided by two pre-existing conceptual frameworks, Knowledge Infrastructure (KI) and the Theory of Remote Scientific Collaboration (TORSC), we design and test a profile tool that consists of four overarching dimensions for capturing social scientists’ data practices, namely: 1) data characteristics, 2) perceived technical infrastructure, 3) perceived organizational context, and 4) individual characteristics. To ensure that the instrument can be applied in real and practical terms, we conduct a case study by collecting responses from 93 early-career social scientists at two research universities in the Pittsburgh Area, U.S. The results suggest that there is no significant difference, in general, among scholars who prefer quantitative, mixed method, or qualitative research methods in terms of research activities and data-sharing practices. We also confirm that there is a gap between participants’ attitudes about research openness and their actual sharing behaviors, highlighting the need to study the “barrier” in addition to the “incentive” of research data sharing

Network analysis of shared interests represented by social bookmarking behaviors

Social bookmarking is a new phenomenon characterized by a number of features including active user participation, open and collective discovery of resources, and user-generated metadata. Among others, this study pays particular attention to its nature of being at the intersection of personal information space and social information space. While users of a social bookmarking site create and maintain their own bookmark collections, the users' personal information spaces, in aggregate, build up the information space of the site as a whole. The overall goal of this study is to understand how social information space may emerge when personal information spaces of users intersect and overlap with shared interests. The main purpose of the study is two-fold: first, to see whether and how we can identify shared interest space(s) within the general information space of a social bookmarking site; and second, to evaluate the applicability of social network analysis to this end. Delicious.com, one of the most successful instances of social bookmarking, was chosen as the case. The study was carried out in three phases asking separate yet interrelated questions concerning the overall level of interest overlap, the structural patterns in the network of users connected by shared interests, and the communities of interest within the network. The results indicate that, while individual users of delicious.com have a broad range of diverse interests, there is a considerable level of overlap and commonality, providing a ground for creating implicit networks of users with shared interests. The networks constructed based on common bookmarks revealed intriguing structural patterns commonly found in well-established social systems, including a core periphery structure with a high level of connectivity, which form a basis for efficient information sharing and knowledge transfer. Furthermore, an exploratory analysis of the network communities showed that each community has a distinct theme defining the shared interests of its members, at a high level of coherence. Overall, the results suggest that networks of people with shared interests can be induced from their social bookmarking behaviors and such networks can provide a venue for investigating social mechanisms of information sharing in this new information environment. Future research can be built upon the methods and findings of this study to further explore the implication of the emergent and implicit network of shared interests

Information sources cited and relayed in political conversations on Twitter

Using the Twitter data collected prior to the Presidential Election in Korea in 2012, we ask questions regarding influential sources of information in public political discourse. The frequently cited sources, being included as URLs in political tweet messages, are identified and categorized. The result shows that people rely on various sources of information beyond the traditional news media, but the pattern of sharing differ by sources

Best Versus Helpful Health Information: Teens’ Assessments of the Answers to Eating Disorders Questions in Yahoo! Answers

This research project investigated teens’ perspectives on the quality and helpfulness of health information about eating disorders found on Yahoo! Answers, a Social Q&A site. A mixed methods approach was applied, using survey methods and semi-structured group interviews to gather data for the project. Eighteen teens completed a web-based questionnaire using sample question/answer sets about eating disorders from Yahoo! Answers. The teen participants were asked to choose one answer as “best” and then rank its credibility, accuracy, reliability, and helpfulness. Open-ended questions allowed teens to explain the rationale for their choice of “best” answer and to discuss why the chosen answer might (or might not) be helpful for teens. Following the questionnaire, six teens participated in a focus group interview using a semi-structured format that asked open-ended “why” questions in order to draw forth comments on criteria for evaluating the quality and and helpfulness of health information in Yahoo! Answers, as well as to reveal aspects of critical thinking. Findings suggest that, 1) teens make a distinction between health information in Social Q&A that is credible versus that which is helpful, 2) they value health information that isn’t from a credible source if it addresses other needs, and, 3) when making judgments about health information on the Web, they apply an array of heuristics related to information quality, opinion, communication style, emotional support and encouragement, guidance, personal experience, and professional expertise

Linking information and people in a social system for academic conferences

This paper investigates the feasibility of maintaining a social information system to support attendees at an academic conference. The main challenge of this work was to create an infrastructure where users’ social activities, such as bookmarking, tagging, and social linking could be used to enhance user navigation and maximize the users’ ability to locate two important types of information in conference settings: presentations to attend and attendees to meet. We developed Conference Navigator 3, a social conference support system that integrates a conference schedule planner with a social linking service. We examined its potential and functions in the context of a medium-scale academic conference. In this paper, we present the design of the system’s socially enabled features and report the results of a conference-based study. Our study demonstrates the feasibility of social information systems for supporting academic conferences. Despite the low number of potential users and the short timeframe in which conferences took place, the usage of the system was high enough to provide sufficient data for social mechanisms. The study shows that most critical social features were highly appreciated and used, and provides direction for further research

Overexpression and characterization of a thermophilic and hemolytic phospholipase of Vibrio vulnificus cloned in Escherichia coli (phospholipase of V. vulnificus)

A phospholipase (PLase) gene of Vibrio vulnificus was cloned in Escherichia coli and the properties of the gene product were investigated. The PLase structural gene was composed of 1,251 bp, encoding 417 amino acids for a protein with a predicted molecular mass of 47,187 Da including a putative signal sequence. The predicted protein sequence was 87 and 82% identical to those of hemolysins from Vibrio spp. and that of lecithinase from V. cholerae, respectively. A lipid binding motif, GDSL, conserved among various PLases and lipases was also observed. Over-expression of PLase caused inclusion body formation in E. coli, but not that of the PLase subclone without the signal sequence (45 kDa). Purified PLase exhibited hemolytic activity on red blood cells and hydrolyzed phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, and soya-lecithin mainly to fatty acid and 1,2-diacylglycerol, indicating that it was a PLase with unique catalytic activity. PLase from V. vulnificus had temperature and pH optimum at 45°C and 7.0 in 50 mM Tris-HCl buffer, respectively, but was quite active at temperatures up to 55°C and in a broad range of pH 5 to 10. The activity of the enzyme was enhanced by divalent cations such as Ca2+, Co2+, Mg2+, and Mn2+, but not by ethylenediaminetetraacetic acid (EDTA).Key words: Phospholipase, Vibrio vulnificus, hemolytic, VplA

The microwave spectrum and structure of the methanol⋅SO2 complex

The rotational spectra of nine isotopomers of the methanol⋅sulfur dioxide van der Waals complex were observed with a pulsed molecular beam Fourier transform microwave spectrometer. Each rotational transition is split into an A‐state (m=0) and an E‐state (m=±1) transition due to methyl top internal rotation effects. The A and E transitions show an additional inversion splitting ranging from a MHz to a few tens of MHz in seven of the isotopomers. The inversion splitting is absent in the two S16O18O isotopomers. The center frequencies of the inversion doublets were used in a simultaneous fit of both the A‐ and E‐state transitions, producing rotational constants which allowed a complete determination of the structure of the complex. Analysis of the moments of inertia indicate that the complex has a stacked structure. The center of mass distance between the two monomers is 3.08(5) Å. The effective torsional barrier height is V3=128.6(1) cm−1 based on the assumption that the methyl group rotates against a heavy frame. The dipole moment is μT=1.94(3) D. The inversion motion is discussed based on effects on the splitting associated with isotopic substitution and the transition dipole direction. © 1995 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/71010/2/JCPSA6-103-15-6440-1.pd