| 41. |
- Berg, Björn, et al.
(författare)
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Reduction of decomposition rates of Scots pine needle litter due to heavy-metal pollution
- 1991
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Ingår i: Water, Air and Soil Pollution. - 1573-2932. ; 59:1-2, s. 165-177
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Tidskriftsartikel (refereegranskat)abstract
- Decomposition of unpolluted Scots pine needle litter was studied in two heavy-metal-pollution gradients in Sweden; one near a brass mill and the other around a primary smelter. In the latter area locally collected polluted Scots pine needle litter was also incubated. Decomposition rates were strongly influenced by the metal pollution and a decrease in the rate of mass-loss occurred. In the brass-mill gradient this occurred until about 1 km from the pollution source which corresponded to about 500-mu-g Cu and 1000-mu-g Zn g-1 soil. Data are presented to indicate that lignin decomposition was more sensitive to pollution than decomposition of whole litter and affected further away from the pollution sources. At the smelter sites, the metal-polluted needle litter decomposed more slowly than the unpolluted needle litter, and this difference was enhanced close to the smelter. The results indicate that heavy metals accumulated in needles prior to shedding have a long-term impact on the subsequent decomposition of the litter. Both litter quality and soil factors thus contribute to the reduced litter decomposition rate in metal-polluted forests. A new non-linear model with decreasing decay rate was used in the statistical evaluation. The model can be used to characterize the effects of pollution on decomposition rate.
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| 42. |
- Berg, Benita
(författare)
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Undervisningsbegreppets innebörd i förskolan utifrån ett läroplansteoretiskt perspektiv
- 2022
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Ingår i: Educare. - Malmö : Educare - Vetenskapliga Skrifter. - 1653-1868 .- 2004-5190. ; :3, s. 75-97
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the study is to contribute knowledge about how teaching in preschool can be understood in relation to how teaching is described by preschool teachers. The following research questions were posed:How do preschool teachers describe teaching and its meaning in preschool? and What didactic questions appear in preschool teachers’ descriptions of teaching in preschool? The empirical data consist of reflective texts that were analysed through content analysis with the help of Bernstein’s concepts: classification and framing, and visible and invisible pedagogy. The results show that the preschool teachers in the study perceived the introduction of the concept of teaching in preschool as an opportunity, which allowed them to become more aware of their actions in different learning situations. That the preschool teachers described teaching taking place through play and in everyday situations based on children's interests and needs hints at an organization with invisible pedagogy, weak classification and weak framing. Strong classification and strong framing, on the other hand, became manifest when the preschool teachers described that they plan what they do with the children and use materials, organize children’s groups and design environments to promote children’s learning. Furthermore, the preschool teachers focused mainly on the didactic questions of how and why, while the what-question received less attention.
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| 43. |
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| 44. |
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| 45. |
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| 46. |
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| 47. |
- Berg, Cecilia
(författare)
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Environmental pollutants and the reproductive system in birds : Developmental effects of estrogenic compounds
- 2000
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A number of environmental pollutants have been shown to mimick the action of the female sex hormone estrogen and are, therefore, suspected to be responsible for reproductive abnormalities seen in wildlife. Test systems which can be used in hazard and risk assessment of chemicals with estrogenic effects are consequently needed. In this thesis, I propose the avian egg as an in vivo test system for estrogenic compounds. I conclude that malformation of the left testis and the Müllerian ducts (MDs: embryonic oviducts) in avian embryos can be used as endpoints to examine estrogenic activity of chemicals. MD malformation is more easily determined and thereby faster to use as an endpoint than histologically observed feminization of the testis. The usefulness of MD/oviduct malformations as biomarkers for estrogenic effects in wild birds should be considered. The environmental pollutants bisphenol A (BPA) and o,p´-DDT induced similar effects as the synthetic estrogens, ethynylestradiol and diethylstilbestrol. BPA caused MD malformations in quail embryos and ovotestis formation in chicken embryos. o,p´-DDT induced MD malformations in both quail and chicken embryos and ovotestis in chicken embryos. The flame retardant, tetrabromobisphenol A did not induce estrogen-like effects in quail or chicken embryos, but showed a relatively high embryolethality. Embryonic exposure to estrogen caused persisting malformations of the oviduct, as well as a changed distribution pattern of the enzyme carbonic anhydrase in the shell gland of adult females. Considering the crucial role of carbonic anhydrase in shell formation, such changes could result in decreased shell quality. I propose that eggshell thinning in avian wildlife could reflect a functional malformation in the shell gland that is induced by xeno-estrogens during embryonic development, rather than being caused by exposure of the adult bird to environmental pollutants. This hypothesis opens new possibilities for studying the mechanisms behind contaminant-induced eggshell thinning in birds.
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| 48. |
- Berg, Carin, 1979, et al.
(författare)
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Hamas’ Musical Resistance Practices: Perceptions, Production, and Usage
- 2013
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Ingår i: Moslih Kanaaneh, Stig-Magnus Thorsén, Heather Bursheh and David A.. McDonald, 2013, Palestinian Music and Song, in Indiana University Press.. - : Indiana University Press. - 9780253011060
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Bokkapitel (refereegranskat)
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| 49. |
- Berg, Christina, 1963
(författare)
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Influences on schoolchildren's dietary selection : focus on fat and fibre at breakfast
- 2002
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- One important aim of the Swedish Action Programme for Nutrition is to increase the consumption of dietary fibre and decrease fat intake. The currently available extensive range of fat-reduced and fibre-enriched foods makes these dietary practices possible, but also makes the selection of a health promoting diet more complex. This thesis aims to contribute to the understanding of psychosocial influences on schoolchildren?s food choice, with specific attention to fat and fibre content. The focus was on breakfast because typical Swedish breakfast foods are important sources of fat and fibre. The Theory of Planned Behaviour formed the theoretical basis of the studies. All pupils in the 5th, 7th and 9th grades in M?lndal municipality (N=1730) were asked to complete a questionnaire and a 7-day food record. Interviews were performed with 181 of those subjects. A picture-sort interview technique, the ?stacking box methodology?, was employed to describe perceptions and habitual choices. Assessing diets of children and adolescents is not an easy task. As in all dietary surveys, reporting and participation biases may exist. The present study using food records illustrates several such biases, which should be taken into consideration in the design, analysis and interpretation of future studies. The ?stacking box methodology? seems promising, and appeared to have some advantages compared to traditional methods. However, the two dietary assessment methods generally yielded similar results. Reduced-fat choices of milk and margarine were common, although a considerable number of subjects consumed full-fat products. When it comes to the consumption of bread and cereals, the low-fibre alternatives dominated. At the age of 11 as well as 15, children?s own attitudes and underlying beliefs were of importance for breakfast food choices, as was parental influence. Parents influenced food choice by controlling food availability, acting as models and encouraging the child to consume. The perceived parental norms supported dietary changes towards products with more fibre but not towards fat-reduced products. However, the perception of parents? own consumption seemed to favour consumption of fat-reduced milk. Participants? attitudes were associated with health beliefs as well as taste perceptions. In general, the results suggest that taste may be a barrier to the consumption of high-fibre products, while consumption of low-fat products appears to be impeded by health beliefs. Contrary to several other studies, the present results suggest that some aspects of young people?s dietary behaviour are related to their knowledge. Specifically, the choice of high-fibre products was associated with knowledge of fibre sources and the choice of fat-reduced milk products was associated with a positive attitude towards limited fat intake.
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| 50. |
- Bergdahl, Basti, et al.
(författare)
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Engineering yeast hexokinase 2 for improved tolerance toward xylose-induced inactivation.
- 2013
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Ingår i: PLoS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 8:9
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Tidskriftsartikel (refereegranskat)abstract
- Hexokinase 2 (Hxk2p) from Saccharomyces cerevisiae is a bi-functional enzyme being both a catalyst and an important regulator in the glucose repression signal. In the presence of xylose Hxk2p is irreversibly inactivated through an autophosphorylation mechanism, affecting all functions. Consequently, the regulation of genes involved in sugar transport and fermentative metabolism is impaired. The aim of the study was to obtain new Hxk2p-variants, immune to the autophosphorylation, which potentially can restore the repressive capability closer to its nominal level. In this study we constructed the first condensed, rationally designed combinatorial library targeting the active-site in Hxk2p. We combined protein engineering and genetic engineering for efficient screening and identified a variant with Phe159 changed to tyrosine. This variant had 64% higher catalytic activity in the presence of xylose compared to the wild-type and is expected to be a key component for increasing the productivity of recombinant xylose-fermenting strains for bioethanol production from lignocellulosic feedstocks.
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