Postings List Compression with Run-length and Zombit Encodings

Inverted indices is a core index structure for different low-level structures, like search engines and databases. It stores a mapping from terms, numbers etc. to list of location in document, set of documents, database, table etc. and allows efficient full-text searches on indexed structure. Mapping location in the inverted indicies is usually called a postings list. In real life applications, scale of the inverted indicies size can grow huge. Therefore efficient representation of it is needed, but at the same time, efficient queries must be supported. This thesis explores ways to represent postings lists efficiently, while allowing efficient nextGEQ queries on the set. Efficient nextGEQ queries is needed to implement inverted indicies. First we convert postings lists into one bitvector, which concatenates each postings list's characteristic bitvector. Then representing an integer set efficiently converts to representing this bitvector efficiently, which is expected to have long runs of 0s and 1s. Run-length encoding of bitvector have recently led to promising results. Therefore in this thesis we experiment two encoding methods (Top-k Hybrid coder, RLZ) that encode postings lists via run-length encodes of the bitvector. We also investigate another new bitvector compression method (Zombit-vector), which encodes bitvectors by finding redundancies of runs of 0/1s. We compare all encoding to current state-of-the-art Partitioned Elisa-Fano (PEF) coding. Compression results on all encodings were more efficient than the current state-of-the-art PEF encoding. Zombit-vector nextGEQ query results were slighty more efficient than PEF's, which make it more attractive with bitvectors that have long runs of 0s and 1s. More work is needed with Top-k Hybrid coder and RLZ, so that those encodings nextGEQ can be compared to Zombit-vector and PEF

Building the Big Society

Papers are a contribution to the debate and set out the authors ’ views only Localism and the Big Societ

Using Assessment Feedback for Motivation Among Early Adolescents: A Grounded Theory Study

The purpose of this grounded theory study was to develop a general theory explaining how verbal or written teacher feedback on formative assessments may influence early adolescent motivation for academic achievement, along the SDT continuum. I based this study on Deci and Ryan’s (2000) self-determination theory (SDT), and to a lesser degree expectancy-value theory (Wigfield & Eccles, 2000) and self-efficacy theory (Bandura, 1993). I also used Tunstall and Gipps’ (1996) typology research as a framework for describing and classifying feedback in the data. Related literature and research findings are presented to lay a foundation for the study and identify the gap in the literature. Philosophical assumptions and interpretive framework are identified, as they guide how the problem is delineated, the purpose of the study and its significance in adding to existing knowledge. Four northeast Ohio public school teachers and four to 12 students selected from each of their respective fifth or sixth-grade classes participated in this study via self-determination theory questionnaires for students, teacher demographic surveys, and interviews, student focus groups and classroom observations. This data was analyzed to determine codes and their link to one another in relation to a core theme. Corbin and Strauss’ (2015) grounded theory methodology was utilized, to answer the question of how feedback from a teacher on formative assessments influences student motivation for academic achievement. The study revealed that teacher feedback that is descriptive impacts students’ sense of competence and relatedness and, thus, improves students’ controlled motivation. Similarly, though to a lesser degree, evaluative feedback impacts students’ sense of competence too, but it can also lead to amotivation

Prediction of cardiovascular disease risk by cardiac biomarkers in 2 United Kingdom cohort studies: does utility depend on risk thresholds for treatment?

We tested the predictive ability of cardiac biomarkers N-terminal pro B-type natriuretic peptide (NT-proBNP), high-sensitivity troponin T, and midregional pro adrenomedullin for cardiovascular disease (CVD) events using the British Regional Heart Study (BRHS) of men aged 60 to 79 years, and the MIDSPAN Family Study (MFS) of men and women aged 30 to 59 years. They included 3757 and 2226 participants, respectively, and during median 13.0 and 17.3 years follow-up the primary CVD event rates were 16.6 and 5.3 per 1000 patient-years, respectively. In Cox models adjusted for basic classical risk factors, 1 SD increases in log-transformed NT-proBNP, high-sensitivity troponin T, and midregional pro adrenomedullin were generally associated with increased primary CVD risk in both the studies (P<0.006) except midregional pro adrenomedullin in MFS (P=0.10). In BRHS, QRISK2 risk factors yielded a C-index of 0.657, which was improved by 0.017 (P=0.005) by NT-proBNP, but not by other biomarkers. Using 28% 14-year risk as a proxy for 20% 10-year risk, NT-proBNP improved risk classification for primary CVD cases (case net reclassification index, 5.9%; 95% confidence interval, 2.8%–9.2%), but only improved classification of noncases at a 14% 14-year risk threshold (4.6%; 2.9%–6.3%). In MFS, ASSIGN risk factors yielded a C-index of 0.752 for primary CVD; none of the cardiac biomarkers improved the C-index. Improvements in risk classification were only seen using NT-proBNP and high-sensitivity troponin T among cases using the 28% 14-year risk threshold (4.7%; 1.0%–9.2% and 2.6%; 0.0%–5.8%, respectively). In conclusion, the improvement in treatment allocation gained by adding cardiac biomarkers to risk scores seems to depend on the risk threshold chosen for commencing preventative treatments

Liderazgo pedagógico en directores nóveles en Chile: Prácticas de observación de clases y retroalimentación a profesores

El rol de los directores escolares es clave para movilizar la mejora de los centros escolares. A través de un enfoque cualitativo-longitudinal utilizando la técnica thin-slice, este artículo examinó la calidad de las prácticas asociadas con la observación en el aula y la retroalimentación proporcionada por 10 directores nóveles al final de su primer y su segundo año en el cargo. Los resultados de este estudio señalan que el patrón de observación de los directores nóveles experimenta cambios desde el primer al segundo año en el cargo, desde un foco en los docentes y el contenido hacia un foco en la interacción contenidos-estudiantes. Respecto del tipo de retroalimentación en el año 2 se observa mayor uso de una retroalimentación más descriptiva que evaluativa. Los resultados de esta investigación muestran cómo con más experiencia los directores fortalecen su liderazgo pedagógico. No obstante, las limitaciones observadas el año 1 y el escaso uso de retroalimentación que promueva la metacognición y reflexión en los docentes sugieren que la observación en aula y retroalimentación a los docentes son prácticas a desarrollar por los programas de formación para directores.The role of school principals is key to mobilizing the improvement of schools. Through a qualitative-longitudinal approach, using the thin-slice technique, this paper examined the quality of practices associated with classroom observation and the feedback provided by 10 novice principals at the end of their first and second year in office. Results show that from year 1 to year 2, participants changed the focus of their observation from greater attention to content and teachers to more attention to the interactions between content and students. They also changed the type of feedback they would provide to teachers, decreasing the use of evaluative feedback and increasing the use of descriptive feedback. The results of this study show how with more experience principals strengthen their pedagogical leadership. Notwithstanding, the limitations observed in year 1 and the limited use of feedback that promotes teachers’ metacognitive and reflective engagement suggest that classroom observation and feedback to teachers are practices that need to be explicitly developed by principal preparation programs

Gender differences in trends of acute myocardial infarction events: The Northern Sweden MONICA study 1985 – 2004

<p>Abstract</p> <p>Background</p> <p>The registration of non-fatal and fatal MI events initiated 1985 in the WHO MONICA project has been ongoing in northern Sweden since the end of the WHO project in 1995. The purpose of the present study was to analyze gender differences in first and recurrent events, case fatality and mortality in myocardial infarction (MI) in Northern Sweden during the 20-year period 1985 – 2004.</p> <p>Methods</p> <p>Diagnosed MI events in subjects aged 25–64 years in the Counties of Norrbotten and Västerbotten were validated according to the MONICA protocol. The total number of events registered up to January 1, 2005 was 11,763: 9,387 in men and 2,376 in women.</p> <p>Results</p> <p>The proportion of male/female events has decreased from 5.5:1 to 3:1. For males the reductions were 30% and 70% for first and recurrent MI, respectively, and for women 0% and 40% in the 55–64 year group. For both sexes a 50% reduction in 28-day case fatality was seen in the 25–64 year-group. Mortality was reduced by 69% and 45% in men and women, respectively.</p> <p>Conclusion</p> <p>First and recurrent events of myocardial infarction was markedly reduced in men over the 20-year observation period, but for women the reduction was seen only for recurrent infarctions. Case fatality, on the other hand, was markedly reduced for both sexes. As a result of the positive effects on incidence and case fatality a substantial reduction was seen in total mortality, most pronounced for men.</p