Parabolic dish reflectors for solar applications approximated by simple surfaces

Two different concentrating mirrors have been constructed that resemble parabolic dish reflectors. Both mirrors are made of slightly curved strips of flat, bendable material. The strips of the most simplified mirror have only large-radius circles and straight lines as boundaries. The necessary equations for making the mirrors have been derived. Also a simple way to make a stiff, lightweight frame and support for the mirror strips has been developed. Models of the mirrors have been built and successfully used for cooking and baking.This report is an extended version of a paper to be published in Solar Energy that contains complete derivations of all mirror design equations.

Motstånd och stöd : en studie av svenska muslimska församlingar

Opposition and Support: A Study of Swedish Muslim Congregations Anti-Islamic attitudes are deeply rooted in Western Europe, and Muslims have, especially in the post-September 11 context, experienced discrimination and demonization. But how do anti-Islamic attitudes affect practicing Muslims and their congregations? The aim of this study, the first of its kind in Europe, is to present a statistically representative view of how Muslim congregations in Sweden experienced the reactions from the surrounding community. The results of the survey carried out show that according to the representatives of the local congregations (n=105) half of the congregations have experienced opposition from the local community and in 40 percent of the congregations criminal offences have been committed against active Muslims or their places of worship.  This opposition is closely connected with two types of situations: either international occurrences (i.e. terrorist bombings in, for example, London, Madrid) or local events that have emphasized the presence of Islam in the public sphere. A multivariate analysis of the results of the study shows that the strongest opposition has taken place in small municipalities with a large proportion of immigrants. However, opposition does not preclude support. On the contrary, opposition appears to have a mobilizing effect on those who support the right of Muslims to exercise freedom of religion. However, neither opposition nor support are the key factors affecting whether congregations see themselves as established in the local community. The degree of anchorage depends on the demographic composition of the congregation and on the degree of contact that the members have with the surrounding community.

Dichlorvos exposure impedes extraction and amplification of DNA from insects in museum collections

Background: The insecticides dichlorvos, paradichlorobenzene and naphthalene have been commonly used to eradicate pest insects from natural history collections. However, it is not known how these chemicals affect the DNA of the specimens in the collections. We thus tested the effect of dichlorvos, paradichlorobenzene and naphthalene on DNA of insects (Musca domestica) by extracting and amplifying DNA from specimens exposed to insecticides in two different concentrations over increasing time intervals. Results: The results clearly show that dichlorvos impedes both extraction and amplification of mitochondrial and nuclear DNA after relatively short time, whereas paradichlorobenzene and naphthalene do not. Conclusion: Collections treated with paradichlorobenzene and naphthalene, are better preserved concerning DNA, than those treated with dichlorvos. Non toxic pest control methods should, however, be preferred due to physical damage of specimens and putative health risks by chemicals.

Att skriva sig till läsning : En kvalitativ studie om möjligheter och begränsningar med ASL ur ett lärarperspektiv

Syftet med denna studie var att undersöka ett antal lärarens förhållningssätt till metoden att skriva sig till läsning (ASL). Metoden går ut på att eleverna använder dator istället för penna i som första skrivverktyg. Den frågeställning studien avsett att besvara är på vilka sätt det pedagogiska arbetet med metoden ASL kan bedrivas i årskurs 1-3. För att söka svar på studiens frågeställning har fem lärare i en kommun intervjuats via kvalitativa strukturerade intervjuer. Intervjuerna har sedan analyserats med hjälp av analyssättet innehållsanalys, vilket innebär att intervjuerna transkriberades för att sedan kodas och kategoriseras. Resultatet visade att de fem lärarna har deltagit vid samma föreläsningar och/eller studiebesök och att de flesta lärarna arbetar med så kallade mönstertexter och olika teman men tar även inspiration från andra metoder och läromedel. De slutsatser som dras av denna studie är att de intervjuade lärarna anser att ASL bidrar till att elevernas skrivförmåga förbättras men att tekniken ibland kan upplevas som problematiskt. Samtliga lärare kommer att fortsätta med ASL och det verkar som att de anser att fördelarna väger tyngre än nackdelarna.