Self-similar ornaments obtained from girih tiles

Contains fulltext : 72610.pdf (publisher's version ) (Open Access)XXI Congress and General Assembly of the International Union of Crystallography, 23 augustus 200

J.J. Burckhardt's contributions to crystallography

Item does not contain fulltextXXI congress and general assembly of the international union of crystallography, 23 augustus 200

On the development of a novel detector for simultaneous imaging and dosimetry in radiotherapy

Radiotherapy uses x-ray beams to deliver prescribed radiation doses that conform to target anatomy and minimise exposure of healthy tissue. Accuracy of dose delivery is essential, thus verification of dose distributions in vivo is desirable to monitor treatments and prevent errors from compromising patient outcomes. Electronic portal imaging devices (EPIDs) are commonly used x-ray imagers, however their non water-equivalent response complicates use for dosimetry. In this thesis, a Monte Carlo (MC) model of a standard EPID was developed and extended to novel water-equivalent configurations based on prototypes in which the high atomic number components were replaced with an array of plastic scintillator fibres. The model verified that full simulation of optical transport is not necessary to predict the standard EPID dose response, which can be accurately quantified from energy deposited in the phosphor screen. By incorporating computed tomography images into the model, its capacity to predict portal dose images of humanoid anatomy was also demonstrated. The prototype EPID’s water-equivalent dose response was characterised experimentally and with the MC model. Despite exhibiting lower spatial resolution and contrast-to-noise ratio relative to the standard EPID, its image quality was sufficient to discern gross anatomical structures of an anthropomorphic phantom. Opportunities to improve imaging performance while maintaining a water-equivalent dose response were identified using the model. Longer fibres increased efficiency and use of an extra-mural absorber maximised spatial resolution. Optical coupling between the scintillator fibres and the imaging panel may further improve performance. This thesis demonstrates the feasibility of developing a next-generation EPID for simultaneous imaging and dosimetry in radiotherapy. Such a detector could monitor treatment deliveries in vivo and thereby facilitate adaptations to treatment plans in order to improve patient outcomes

Web-based progress monitoring in first grade mathematics

The purpose of our research was to examine a web-based tool for mathematics progress monitoring in first grade. The newly developed assessment tool uses several robust indicators and curriculum-based measures forming three competences (Basic Precursors, Advanced Precursors, and Computation) to determine comprehensive early numeracy skills in regular education. 373 students completed a total of eight online tests every two or three weeks. Results indicate that delayed alternate-form reliability was adequate (rM = .78). Repeated measures analyses with post hoc comparisons were used to ascertain the sensitivity to assess learning growth. All three competences showed linear growth rates that were significant over time, but only Computation and overall scores produced dependable increases from test to test. Predictive validity was determined using two standardised school achievement tests (end of first grade, end of second grade). Results indicate high predictive validity of the first four online tests (rM = .67, rM = .66 for 6 months and 18 months prediction). Correlations with teacher ratings of their students' skills confirmed this pattern. Results from student and teacher questionnaires indicate that the students were able to conduct the tests independently and that a three-week interval was adequate for regular‑education use. Teachers stated to use the progress monitoring results diversely for classroom purposes. We conclude that the use of a web-based assessment setting with diverse measures is beneficial with respect to psychometric properties and feasibility for frequent use in regular education

Students´ reading ability moderates the effects of teachers´ beliefs on students´ reading progress

Teachers’ beliefs about teaching have been found to affect students’ learning growth. The aim of this study was to investigate effects of teachers’ constructivist and direct-transmissive beliefs on learners’ reading progress and whether these effects are influenced by prior student achievement. We measured constructivist and direct-transmissive beliefs of 29 teachers and the progress in reading fluency and reading comprehension of their students (N = 568) at eight points of measurement over one school year. Results of three-level latent growth curve modeling revealed that teachers’ constructivist beliefs were positively related to learners’ progress in reading fluency but had no general effect on growth in reading comprehension. Nevertheless, the relation between constructivist beliefs and individual learners’ progress in reading comprehension was affected by students’ level of ability. Teachers with stronger constructivist beliefs effected higher learning growth for high ability compared to low ability learners. No effects were found for direct-transmissive beliefs. Using longitudinal modelling of student learning, this study adds a more differentiated view to findings concerning the effects of teacher beliefs. Results show that effects vary depending on subject of learning (fluency vs. comprehension), and that effects of teacher beliefs may depend on students’ level of ability

Formatives Assessment [Editorial]

[Editorial

Internetplattformen zur Diagnostik von Lernverläufen von Schülerinnen und Schülern in Deutschland. Ein Vergleich der Plattformen Lernlinie, Levumi und quop

Die Lernverlaufsdiagnostik ist ein wesentliches Element zur Prävention von Lernproblemen sowie zur Evaluation von Förderentscheidungen und bildet die Grundlage für datenbasierte pädagogische Entscheidungsfindungsprozesse. Obwohl positive Effekte für die Anwendung einer Lernverlaufsdiagnostik nach aktueller Studienlage auf die Leistung der Schülerinnen und Schüler nachgewiesen sind, ist ihre Anwendung noch nicht weit verbreitet. Aktuell zeigt sich, dass Lehrkräfte Schwierigkeiten damit haben, Lernverlaufsdaten zu interpretieren und adäquate Förderentscheidungen abzuleiten. Internetbasierte Systeme zur Planung, Durchführung und Interpretation von Lernverlaufsdaten können zur Anwendung von Lernverlaufsdiagnostik für Sonder- oder Regelschullehrkräfte eine Hilfe sein. In diesem Kontext werden die drei Internetplattformen www.lernlinie.de, www.levumi.de sowie www.quop.de vorgestellt. Kriteriengeleitet werden jeweils die Grundideen, die Umsetzung in der pädagogischen Praxis und die wissenschaftliche Fundierung der Internetplattformen herausgearbeitet. Progress monitoring is an essential element for the prevention of learning problems as well as for the evaluation of support decisions and forms the basis for data-based decision-making processes. Although positive effects for the application of progress monitoring on student achievement have been proven, their application is not yet widespread. Currently, it appears that teachers have difficulties in interpreting learning progress data and in deriving adequate decisions and interventions. Internet-based systems for planning, conducting, and interpreting data can be of help in applying progress monitoring in research and practice. In this context, the internet platforms www.lernlinie.de, www.levumi.de as well as www.quop.de are presented in this paper. The basic ideas, the implementation in pedagogical practice and the scientific foundation of the Internet platforms are worked out on the basis of set criteria

Detoxifying Escherichia coli for endotoxin-free production of recombinant proteins

Es va publicar un treball amb esmenes a aquest article que es pot consultar a https://ddd.uab.cat/record/185349 (DOI 10.1186/s12934-015-0265-x)Background: lipopolysaccharide (LPS), also referred to as endotoxin, is the major constituent of the outer leaflet of the outer membrane of virtually all Gram-negative bacteria. The lipid A moiety, which anchors the LPS molecule to the outer membrane, acts as a potent agonist for Toll-like receptor 4/myeloid differentiation factor 2-mediated pro-inflammatory activity in mammals and, thus, represents the endotoxic principle of LPS. Recombinant proteins, commonly manufactured in Escherichia coli, are generally contaminated with endotoxin. Removal of bacterial endotoxin from recombinant therapeutic proteins is a challenging and expensive process that has been necessary to ensure the safety of the final product. -Results: as an alternative strategy for common endotoxin removal methods, we have developed a series of E. coli strains that are able to grow and express recombinant proteins with the endotoxin precursor lipid IVA as the only LPS-related molecule in their outer membranes. Lipid IVA does not trigger an endotoxic response in humans typical of bacterial LPS chemotypes. Hence the engineered cells themselves, and the purified proteins expressed within these cells display extremely low endotoxin levels. - Conclusions: this paper describes the preparation and characterization of endotoxin-free E. coli strains, and demonstrates the direct production of recombinant proteins with negligible endotoxin contamination