Search results for "VDP::Mathematics and natural science: 400"
showing 10 items of 421 documents
Lake size and fish diversity determine resource use and trophic position of a top predator in high-latitude lakes
2015
Prey preference of top predators and energy flow across habitat boundaries are of fundamental importance for structure and function of aquatic and terrestrial ecosystems, as they may have strong effects on production, species diversity, and food-web stability. In lakes, littoral and pelagic food-web compartments are typically coupled and controlled by generalist fish top predators. However, the extent and determinants of such coupling remains a topical area of ecological research and is largely unknown in oligotrophic high-latitude lakes. We analyzed food-web structure and resource use by a generalist top predator, the Arctic charr Salvelinus alpinus (L.), in 17 oligotrophic subarctic lakes…
Effect of Heat on the Adsorption Properties of Silica Gel
2012
Published version of an article in the journal: International Journal of Engineering and Technology. Also available from the publisher at: http://www.ijetch.org/papers/416-T886.pdf Open access. Adsorption properties of silica gel have been attributed to the surface hydroxyl groups of silica gel. Some hydroxyl groups are free standing and called free silanol groups. Some are hydrogen bonded to neighbouring silanol groups. Christy has shown that a high silanol number and a balanced concentration proportionality between these two different types of hydroxyl groups is necessary for effective adsorption of water molecules. Thermal treatment of silica gel samples alters the proportions of these g…
Pyrolytic formation of polycyclic aromatic hydrocarbons from sesquiterpenes
2012
Author's version of an article in the journal: Food Chemistry. Also available from the publisher at: http://dx.doi.org/10.1016/j.foodchem.2012.06.033 The products of the pyrolysis of four sesquiterpenes, β-caryophyllene, α-cedrene, longifolene and valencene, have been examined. Pyrolysis was carried out at 300, 400 and 500 °C, the products determined by GC–MS and then examined for similarities and differences using multivariate data analysis. Analysis showed that longifolene was most resistant and caryophyllene least resistant to pyrolysis with cedrene and valencene occupying intermediate positions. While the compounds were largely unchanged at 300 °C, polycyclic aromatic hydrocarbons (PAHs…
Modeling and Backstepping Control of the Electronic Throttle System
2013
Published version of an article in the journal: Mathematical Problems in Engineering. Also available from the publisher at: http://dx.doi.org/10.1155/2013/871674 Open access Electronic throttle is widely used in modern automotive engines. An electronic throttle system regulates the throttle plate angle by using a DC servo motor to adjust the inlet airflow rate of an internal combustion engine. Its application leads to improvements in vehicle drivability, fuel economy, and emissions. In this paper, by taking into account the dynamical behavior of the electronic throttle, the mechanism model is first built, and then the mechanism model is transformed into the state-space model. Based on the s…
Effects of UV Radiation and Diet on Polyunsaturated Fatty Acids in the Skin, Ocular Tissue and Dorsal Muscle of Atlantic Salmon (Salmo salar) Held in…
2010
Article published in Photochemistry and Photobiology, 86 (4): 909-919 JUL-AUG 2010 The effect of UV radiation (UVR) on juvenile Atlantic salmon (Salmo salar) was assessed by measuring the fatty acid (FA) profiles of muscle, dorsal and ventral skin, and ocular tissues following 4-month long exposures to four different UVR treatments in outdoor rearing tanks. Fish were fed two different diets (Anchovy- and Herring-oil based) that differed in polyunsaturated fatty acid (PUFA) concentrations. Anchovy-fed salmon had higher concentrations of ALA (alpha-linoleic acid; 18:3n-3), EPA (eicosapentaenoic acid; 20:5n-3) and DPA (docosapentaenoic acid, 22:5n-3) in their muscle tissues than fish fed the H…
Læringspotensial i en digital interaktiv matematikkundervisning : en analyse av læringspotensialet i geometriundervisningen på 8. trinn med utstrakt …
2016
Masteroppgave matematikkdidaktikk – Universitetet i Agder 2016 The theme of this master thesis is learning potential in mathematical tasks designed for geometry teaching in GeoGebra in 8th grade. This thesis is written in connection to the project Digital interactive mathematics teaching (DIM), where the goal is to create innovative mathematics teaching by using digital tools in a pedagogic context. Previous research has documented that students learning outcome of the teaching is largely influenced and limited by the tasks that are given. In this context analysis of the tasks learning potential is particular interesting. Therefore, my research question is: What learning potential is it in …
Den Virtuelle Matematikkskolen - Ungdomstrinnet : En studie av hvilke pedagogiske konsekvenser bruk av nettressursen DVM-U kan føre med seg
2016
Masteroppgave matematikkdidaktikk – Universitetet i Agder 2016 Many lower secondary school students struggle with mathematics and with motivation in the subject. To improve student achievement and motivation in mathematics, The Norwegian Centre for ICT in Education and The Norwegian Centre for Mathematics Education have developed an online learning resource that contains mathematical examples, exercises and games, called The Virtual School of Mathematics – Lower Secondary (DVM-U). The Norwegian Centre for ICT in Education suggest that DVM-U can be used in preparation of a topic, or as something students can work with if they do not benefit on a satisfactory level from the classroom teaching…
Tilpasset opplæring i matematikk på ungdomsskolen : to læreres begrunnelser for sine tilpasninger
2016
Masteroppgave matematikkdidaktikk – Universitetet i Agder 2016 The theme of this thesis is adapted education with an emphasis on adapting the teaching of mathematics. I have also decided to direct my attention toward students with low attainers. My research question is: "What arguments gives two mathematics teachers in their adaptations in teaching students with low attainers in middle school?" The study discusses how teachers adapt lessons to students with low attainers in the subject. The empirical basically are two mathematics teachers who teach in the same middle school. In this study I have used qualitative methods. The data is collected through a semi-structured interview. The aim has…
Ungdomsskoleelevers bruk av symboler i algebra
2016
Masteroppgave matematikkdidaktikk – Universitetet i Agder 2016 The thesis investigates the challenges students in 10th grade face while learning algebra, algebraic symbols and how they assess the subject. With the use of a theoretical test and semistructured interviews, the thesis aims to answer the following research questions: 1. What challenges do students from lower secondary education encounter while learning algebra? 2. How do these students engage with algebra and what are their views and aspects towards the subject? The thesis serves primarily as a qualitative case study, of three students from lower secondary school. In addition, quantitative research methods have been undertaken b…
Pytagoras si setning på 10. trinn : ei analyse av tre lærebøkers framstilling og ein elevs bruk av ei av lærebøkene
2016
Masteroppgave matematikkdidaktikk – Universitetet i Agder 2016 This text answers two research questions. The first research question is about how three different textbooks for grade 10 presents the Pythagorean theorem through different representations. These representations are geometric, algebraic and textual. The textbooks are Tetra, Faktor and Maximum. The precision of individual representations and the precision between representations is studied. The chronology in the presentation of the representations has also been studied. The conclusion is that the textbooks have different presentations of the Pythagorean theorem. A geometric representation is presented first in all three textbooks…