Search results for "PPI"

Teacher ability evaluation and changes in elementary student profiles of motivation and performance in mathematics

2018

Abstract The aim of this person-centered study is to identify the profiles of interest value, self-concept, and performance in the domain of mathematics among elementary school students and to examine the stability and changes in these profiles from grade 1 to grade 2. Teacher-reported evaluations of students' mathematical ability and gender were examined as predictors of changes in the student profiles. The sample consisted of 237 students (46.8% girls). The latent profile analysis identified four profiles: 1) low levels of interest value, medium levels of self-concept and performance; 2) low levels of interest value, self-concept and performance; 3) high levels of interest value, self-con…

Design principles for learning analytics information systems in higher education

2020

This paper reports a design science research (DSR) study that develops, demonstrates and evaluates a set of design principles for information systems (IS) that utilise learning analytics to support learning and teaching in higher education. The initial set of design principles is created from theory-inspired conceptualisation based on the literature, and they are evaluated and revised through a DSR process of demonstration and evaluation. We evaluated the developed artefact in four courses with a total enrolment of 1,173 students. The developed design principles for learning analytics information systems (LAIS) to establish a foundation for further development and implementation of learning…

Protein mapping by two-dimensional high performance liquid chromatography.

2000

Current developments in drug discovery in the pharmaceutical industry require highly efficient analytical systems for protein mapping providing high resolution, robustness, sensitivity, reproducibility and a high throughput of samples. The potential of two-dimensional (2D) HPLC as a complementary method to 2D-gel electrophoresis is investigated, especially in view of speed and repeatability. The method will be applied for proteins of a molecular mass <20 000 which are not well resolved in 2D-gel electrophoresis. The 2D-HPLC system described in this work consisted of anion- or cation-exchange chromatography in the first dimension and reversed-phase chromatography in the second dimension. We …

Contribution to the adsorption voltammetric determination of manganese

1994

The adsorption voltammetric determination of Mn(II) with Bromopyrogallol Red (BPR) and Mordant Red 19 (MDR) has been investigated using a hanging drop mercury electrode. In NH3/NH4Cl solution, ligands and Mn(II) complexes give well separated voltammetric peaks after enrichment onto the electrode. The conditions for determining manganese by adsorption voltammetry with these reagents have been investigated in detail, as has the influence of foreign ions on the determination. The detection limits are 4·10−10 mol/L Mn for BPR and 8·10−10 mol/L Mn for MDR, respectively.

Study on the determination of trace rhenium (VII) by the adsorption differential pulse polarography

1989

The determination of trace rhenium (VII) by differential pulse polarography in the system of H2SO4-(NHsOH)2 · H2SO4-TeO2−4 is markedly improved by the addition of Nitron, which is adsorbed on the surface of mercury electrode. The limit of detection is down to 2 × 1010 M. The adsorptive peak potential is −0.80 V (vs. SCE). In the ranges of 5 × 1010—10−8, 1 × 10−5—10−7 and 1 × 10−7—10−6M, there are good linear relationships between the peak current increment and the concentration, of which the relative standard deviations are 9.5, 6.6, 1.8% respectively with the correlation coefficients of linear regression of 0.995–0.999. The results relating to this polarographic wave show that it is an ads…

Vanadium and molybdenum concentrations in particulate from Palermo (Italy): analytical methods using voltammetry

2014

The main purpose of this work was to develop a reliable method for the determination of vanadium (V) and molybdenum (Mo) in atmosphere particles or aerosols because they can not be readily measured using conventional techniques. For this research, 30 particulate samples were collected from five different stations located at Palermo, Italy. We used the catalytic adsorptive stripping voltammetry and differential pulsed voltammetry to measure Vand Mo in atmospheric particulate, respectively. The represented method includes advantages of high sensitivity, high selectivity, simplicity, reproducibility, speed and low costs. The quantification limits for V and Mo are, respectively, 0.57 and 0.80 n…

Voltammetric behavior and assay of the contraceptive drug levonorgestrel in bulk, tablets, and human serum at a mercury electrode.

2004

The cyclic voltammograms of levonorgestrel (LNG) in Britton-Robinson buffers of pH 2-11 at the hanging mercury drop electrode showed a single two-electron irreversible cathodic peak over the whole pH range. This peak may be attributed to the reduction of the 3-keto-delta-4-group in the A-ring of the LNG molecule. The interfacial adsorptive character of levonorgestrel onto the surface of the hanging mercury drop electrode was identified by means of both cyclic voltammetry and chronocoulometry techniques. A simple, sensitive, and selective square-wave adsorptive cathodic stripping voltammetric procedure was developed for the quantitation of levonorgestrel. Under the optimized operational cond…

Voimaantumisen mahdollisuuksia verkko-opiskeluympäristöissä

2002

Teacher orchestration of classroom interaction in science: exploring dialogic and authoritative passages in whole-class discussions

2019

Whereas science is fundamentally a result of a dialogic debate, the authoritative approach has been conceived of as a fundamental part of school science. Dialogic interactions encompass the mutual appreciation of different ideas manifested in teacher supportiveness toward students and, in authoritative interactions, the focus is more on the science’s or teacher’s point of view. Whereas dialogic and authoritative interactions have been viewed as oppositional in recent educational research, authoritative interactions could well be the seed for and give strength and meaning to dialogic interactions, and thus, to the overall dialogue. The focus in this study is on the interplay between authorit…

Assessing (for) Understanding in the CLIL Classroom

2020

In this chapter, we conceptualise CLIL assessment as a dialogic activity in which teachers and learners share the responsibility for building learners’ understanding of subject-specific issues. We illustrate such a conceptualisation by first studying how secondary school CLIL teachers perceive classroom assessment in interviews collected in Finland and Austria. Then, by examining video data from a CLIL lesson, we show how opportunities for assessing to support learning can emerge in routine instructional interaction, and how a teacher can attend to learner talk both to develop his or her own understanding of the learner’s abilities and to promote these same abilities. Our data suggest that,…