Analyzing imbalance among homogeneous index servers in a web search system

The performance of parallel query processing in a cluster of index servers is crucial for modern web search systems. In such a scenario, the response time basically depends on the execution time of the slowest server to generate a partial ranked answer. Previous approaches investigate performance issues in this context using simulation, analytical modeling, experimentation, or a combination of them. Nevertheless, these approaches simply assume balanced execution times among homogeneous servers (by uniformly distributing the document collection among them, for instance)—a scenario that we did not observe in our experimentation. On the contrary, we found that even with a balanced distribution of the document collection among index servers, correlations between the frequency of a term in the query log and the size of its corresponding inverted list lead to imbalances in query execution times at these same servers, because these correlations affect disk caching behavior. Further, the relative sizes of the main memory at each server (with regard to disk space usage) and the number of servers participating in the parallel query processing also affect imbalance of local query execution times. These are relevant findings that have not been reported before and that, we understand, are of interest to the research community.     

Copyright or copyleft?: An analysis of property regimes for software development

Two property regimes for software development may be distinguished. Within corporations, on the one hand, a Private Regime obtains which excludes all outsiders from access to a firm's software assets. It is shown how the protective instruments of secrecy and both copyright and patent have been strengthened considerably during the last two decades. On the other, a Public Regime among hackers may be distinguished, initiated by individuals, organizations or firms, in which source code is freely exchanged. It is argued that copyright is put to novel use here: claiming their rights, authors write ‘open source licenses’ that allow public usage of the code, while at the same time regulating the inclusion of users. A ‘regulated commons’ is created. The analysis focuses successively on the most important open source licenses to emerge, the problem of possible incompatibility between them (especially as far as the dominant General Public License is concerned), and the fragmentation into several user communities that may result.     

Opportunity knocks

Research on technological opportunity has typically focused on the impact of broad industry characteristics on R&D intensity of firms. This study complements such approaches by examining the impact of a multidimensional vector that measures technological opportunity on independent inventors’ decisions to patent and commercialize inventions. Using data from 559 inventions and controlling for demand, appropriability, and competitive conditions, we found two of four tested dimensions of technological opportunity - technical performance and technical uncertainty - to be significant and important determinants of the likelihood of commercialization. Technical feasibility appears important in affecting patenting but unimportant in affecting commercialization. Technical significance carries a negative, although insignificant, sign conditioning commercialization.     

Analytic Frameworks for Assessing Dialogic Argumentation in Online Learning Environments

Over the last decade, researchers have developed sophisticated online learning environments to support students engaging in dialogic argumentation. This review examines five categories of analytic frameworks for measuring participant interactions within these environments focusing on (1) formal argumentation structure, (2) conceptual quality, (3) nature and function of contributions within the dialogue, (4) epistemic nature of reasoning, and (5) argumentation sequences and interaction patterns. Ultimately, the review underscores the diversity of theoretical perspectives represented within this research, the nature of dialogic interaction within these environments, the importance of clearly specifying theoretical and environmental commitments throughout the process of developing or adopting an analytic framework, and the role of analytic frameworks in the future development of online learning environments for argumentation.

A summer program designed to educate college students for careers in bioinformatics

A summer program was created for undergraduates and graduate students that teaches bioinformatics concepts, offers skills in professional development, and provides research opportunities in academic and industrial institutions. We estimate that 34 of 38 graduates (89%) are in a career trajectory that will use bioinformatics. Evidence from open-ended research mentor and student survey responses, student exit interview responses, and research mentor exit interview/survey responses identified skills and knowledge from the fields of computer science, biology, and mathematics that are critical for students considering bioinformatics research. Programming knowledge and general computer skills were essential to success on bioinformatics research projects. General mathematics skills obtained through current undergraduate natural sciences programs were adequate for the research projects, although knowledge of probability and statistics should be strengthened. Biology knowledge obtained through the didactic phase of the program and prior undergraduate education was adequate, but advanced or specific knowledge could help students progress on research projects. The curriculum and assessment instruments developed for this program are available for adoption by other bioinformatics programs at http://www.calstatela.edu/SoCalBSI.     

Infant joint attention, temperament, and social competence in preschool children

Infant joint attention has been observed to be related to social-emotional outcomes in at-risk children. To address whether this relation is also evident in typically developing children, 52 children were tested at 12, 15, 24, and 30 months to examine associations between infant joint attention and social outcomes. Twelve-month initiating and responding to joint attention were related to 30-month social competence and externalizing behavior, even when accounting for 15-month temperament ratings, 24-month cognition and language, and demographic variables. These results suggest that, in addition to associations with language and cognition, infant joint attention reflects robust aspects of development that are related to individual differences in the emergence of social and behavioral competence in childhood.     

Engaging adolescents with LD in higher order thinking about history concepts using integrated content enhancement routines

The understanding and use of historical concepts specified in national history standards pose many challenges to students. These challenges include both the acquisition of content knowledge and the use of that knowledge in ways that require higher order thinking. All students, including adolescents with learning disabilities (LD), are expected to understand and use concepts of history to pass high-stakes assessments and to participate meaningfully in a democratic society. This article describes Content Enhancement Routines (CERs) to illustrate instructional planning, teaching, and assessing for higher order thinking with examples from an American history unit. Research on the individual components of Content Enhancement Routines will be illustrated with data from 1 of the routines. The potential use of integrated sets of materials and procedures across grade levels and content areas will be discussed.     

An Expanded View of Joint Attention: Skill,Engagement, and Language in Typical Development and Autism

This study provides an expanded view of joint attention and its relation to expressive language development. A total of 144 toddlers (40 typically developing, 58 with autism spectrum disorder [ASD], 46 with developmental delay [DD]) participated at 24 and 31 months. Toddlers who screened positive for ASD risk, especially those subsequently diagnosed with ASD, had poorer joint attention skills, joint engagement during parent–toddler interaction, and expressive language. Findings highlight the dynamic relation between joint attention and language development. In the ASD and DD groups, joint engagement predicted later expressive vocabulary, significantly more than predictions based on joint attention skills. Joint engagement was most severely impacted when toddlers did not talk initially and improved markedly if they subsequently began to speak.     

Discrimination and Ethnic–Racial Identity: Understanding Direction of Effects Using Within- and Between-Person Analyses

Ethnic–racial identity (ERI) development and ethnic–racial discrimination are two salient experiences among adolescents in the United States. Despite growing awareness of the costs and benefits of these experiences individually, we know little about how they may influence one another. The current study examined competing hypotheses relating discrimination and components of ERI (i.e., exploration, resolution, affirmation) among a sample of Mexican-origin adolescent mothers (N = 181; M_age at Wave 1 = 16.83, SD = 1.01) across six waves of data. Findings revealed that within-person changes in discrimination predicted subsequent ERI resolution and affirmation; however, ERI did not predict subsequent discrimination. Between-person effects of discrimination on affirmation were significant. Our findings underscore the importance of discrimination experiences in shaping Mexican-origin adolescent mothers’ normative developmental competencies.     

Getting a Read on Ready To Learn Media: A Meta-analytic Review of Effects on Literacy

Most U.S. preschoolers have consumed media created with funding from the U.S. Department of Education's Ready To Learn (RTL) initiative, which was established to promote school readiness among children ages 2–8. Synthesizing data from 45 evaluations (N = 24,624 unique child participants), this meta-analysis examined the effects of RTL media exposure on young children's literacy skills. Results indicate positive effects of RTL media exposure on children's literacy outcomes, especially vocabulary and phonological concepts. These effects are equivalent to about one-and-a-half months of literacy learning above and beyond typical growth. Findings are robust across a variety of research designs and for exposure to both television and new media. These results are discussed in terms of accountability evidence for RTL and larger debates in scholarly understanding of educational media effects.