Att stötta utsatta och ensamma skolkamrater : En tolkande fenomenologisk studie av elevers upplevelser av att vara informellt socialt stöd för andra elever

Syftet med denna studie är att förstå hur ungdomar, som tillfrågats informellt av lärare att utöva socialt stöd till en utsatt skolkamrat, upplever situationen och vilken innebörd socialt stöd har för dem. Genom tolkande fenomenologisk metod har kvalitativa intervjuer med sex ungdomar i åldern 15-18 år genomförts och analyserats. Resultatet visade tre huvudteman i upplevelsen. Dubbla känslor beskriver en kluvenhet inför rollen med såväl positiva som negativa upplevelser. De upplevde förståelse av stödet som en arbetssituation genom att tala om rollen som ett uppdrag, beskriva den utsatte som annorlunda än de själva och markera stödets avgränsning till skoltiden. I informanternas berättelser om stödets utformning framkom deras syn på innebörden av socialt stöd, som att få med den utsatte i gemenskapen. De uttryckte även en önskan att fler elever ska involveras i stödarbetet. Slutsatsen är att rollen kan innebära en utsatt position och att barn och ungdomar, som utövar informellt socialt stöd till en skolkamrat på uppdrag av lärare, behöver uppmärksammas och vikten av stöttning till dem belysas samt beforskas ytterligare. Studien bidrar med ny kunskap om upplevelser av att utöva informellt stöd i skolan.

Adaptation and Constraint in the Plant Reproductive Phase

Conservatism is a central theme of organismic evolution. Related species share characteristics due to their common ancestry. Some concern have been raised among evolutionary biologists, whether such conservatism is an expression of natural selection or of a constrained ability to adapt. This thesis explores adaptations and constraints within the plant reproductive phase, particularly in relation to the evolution of fleshy fruit types (berries, drupes, etc.) and the seasonal timing of flowering and fruiting. The different studies were arranged along a hierarchy of scale, with general data sets sampled among seed plants at the global scale, through more specific analyses of character evolution within the genus Rhamnus s.l. L. (Rhamnaceae), to descriptive and experimental field studies in a local population of Frangula alnus (Rhamnaceae). Apart from the field study, this thesis is mainly based on comparative methods explicitly incorporating phylogenetic relationships. The comparative study of Rhamnus s.l. species included the reconstruction of phylogenetic hypotheses based on DNA sequences. Among geographically overlapping sister clades, biotic pollination was not correlated with higher species richness when compared to wind pollinated plants. Among woody plants, clades characterized by fleshy fruit types were more species rich than their dry-fruited sister clades, suggesting that the fleshy fruit is a key innovation in woody habitats. Moreover, evolution of fleshy fruits was correlated with a change to more closed (darker) habitats. An independent contrast study within Rhamnus s.l. documented allometric relations between plant and fruit size. As a phylogenetic constraint, allometric effects must be considered weak or non-existent, though, as they did not prevail among different subclades within Rhamnus s.l. Fruit size was correlated with seed size and seed number in F. alnus. This thesis suggests that frugivore selection on fleshy fruit may be important by constraining the upper limits of fruit size, when a plant lineage is colonizing (darker) habitats where larger seed size is adaptive. Phenological correlations with fruit set, dispersal, and seed size in F. alnus, suggested that the evolution of reproductive phenology is constrained by trade-offs and partial interdependences between flowering, fruiting, dispersal, and recruitment phases. Phylogenetic constraints on the evolution of phenology were indicated by a lack of correlation between flowering time and seasonal length within Rhamnus cathartica and F. alnus, respectively. On the other hand, flowering time was correlated with seasonal length among Rhamnus s.l. species. Phenological differences between biotically and wind pollinated angiosperms also suggested adaptive change in reproductive phenology.

Structural and Interaction Studies of Bacterial Polysaccharides by NMR Spectroscopy

An introduction to bacterial polysaccharides and the methods for structural determination are described in the first two parts of the thesis. In a structural elucidation of bacterial polysaccharides NMR experiments are important as is component analysis. A short description of immunochemical methods such as enzyme immunoassays is included. Two NMR techniques used for interaction studies, trNOE and STD NMR, are also discussed. The third part of the thesis discusses and summarizes the results from the included papers. The structures of the exopolysaccharides produced by two lactic acid bacteria are determined by one- and two dimensional NMR experiments. One is a heteropolysaccharide produced by Streptococcus thermophilus and the other a homopolysaccharide produced by Propionibacterium freudenreichii. The structure of an acidic polysaccharide from a marine bacterium with two serine residues in the repeating unit is also investigated. The structural and immunological relationship between two O-antigenic polysaccharides from Escherichia coli strain 180/C3 and O5 is discussed and investigated. Finally, interaction studies of an octasaccharide derived from the Salmonella enteritidis O-antigen and a bacteriophage are described which were performed with NMR experiments.