Aquatic environments contain a great diversity of microorganisms, some of which may be aerosolized and transported long distances through the atmosphere. The bacterium Pseudomonas syringae can be found in aquatic environments and in the atmosphere and may express an ice nucleation protein (bacteria expressing the protein are Ice+ and bacteria not expressing the protein are Ice-). Ice+ bacteria may be involved in cloud formation and precipitation processes due to their ability to freeze water at warmer temperatures. Freshwater aerosolization processes are not well understood, particularly the role the Ice+ phenotype may play. Water samples were collected from Claytor Lake, Virginia, USA and screened for Ice+ P. syringae. Results indicated that between 6% and 15% of Pseudomonas colonies assayed were Ice+. Preliminary phylogenetic analysis of cts (citrate synthase) sequences from strains of P. syringae showed a surprising diversity of phylogenetic subgroups present in the lake. A Collison nebulizer was used to aerosolize an Ice+ and an Ice- strain of P. syringae under artificial laboratory conditions. The aerosolization of P. syringae was not influenced by water temperature between 5° and 30°C. In general, the culturability (viability) of P. syringae in aerosols increased with temperature between 5 and 30°C. The Ice+ strain was aerosolized in greater numbers than the Ice- strain at all temperatures studied, suggesting a possible connection between the Ice+ phenotype and aerosol production. A quantitative empirical assessment of aerosolized droplets was generated using a laboratory flume and high-speed video. Droplet diameter and initial velocity upon leaving the water surface were examined at four wind speeds (3.5, 4.0, 4.5, and 5.0 m/s), and the results showed that droplet diameter and velocity had a gamma distribution and droplet mass flux increased exponentially with wind speed. An estimate of the potential amount of bacteria capable of aerosolizing was made for each wind speed. An interdisciplinary unit for advanced high school students has been developed presenting biological aerosolization and ice nucleation. This interdisciplinary work combines modeling and experimental approaches across biology and engineering interfaces, with the goal of increasing our understanding of microbial aerosols from aquatic environments that may impact our planet's water cycle. / Ph. D.

This study examines the subject civics (social studies) in interaction with other subjects in interdisciplinary projects. By studying three different integrated projects in the grades 7-9, the study examines how subjects interact with one another. The aim of the study is to describe and analyze the character and function of civics in interdisciplinary projects. The results are used to discuss the relationship between subject and integration. In the world of education, there are two endeavors that may seem to counteract each other: on the one hand, focus on more clearly subject-specific knowledge and, on the other, the pursuit of cooperation and interaction between subjects in different forms of interdisciplinary organization of teaching and learning. Integration between subjects can be seen as an opportunity to address the complex problems and challenges of today's citizens in a changing global world. The results of the study describe three dynamic interdisciplinary projects that all contain a movement between different types of interaction between subjects with various degrees of integration. These types are predisciplinary, helping, correlated, shared and reconstructed. In addition, the study shows that civics in the three projects is emerging as an obvious main subject that aims to develop the pupils’ abilities to orientate (facts and concepts), analyze and discuss. So far integrated teaching appears to result in both what subject-specific teaching reaches and, moreover, it seems to form a synthesis knowledge that can be difficult to measure, but that relates to the main goals of the curriculum beyond subjects. These abilities to act can be used to describe the synthesized knowledge citizens need in order to act in the world. / Baksidestext I denna studie av hur samhällskunskapsämnet tar sig uttryck i ämnesintegrerade projekt i grundskolans årskurs 7-9, undersöks de till synes motstående strävandena att dels fokusera ämnesspecifika kunskaper, dels ge utrymme för samspel och integration mellan ämnen.  Resultaten visar en ömsesidig relation där ämne och ämnesintegration förutsätter varandra. Projekten innehåller en rörelse mellan olika typer av ämnessamspel – förvetenskapligt, hjälpande, sammankopplande, förenande, omskapande – med olika grad av integration mellan ämnen. Delar av projekten domineras av ämnesspecifika kunskaper där samhällskunskapsämnet framträder som tydligt huvudämne utifrån de ämnesdidaktiska profilerna orienteringsämne, analysämne och diskussionsämne. Andra delar av projekten domineras istället av integrerade synteskunskaper som relaterar till övergripande läroplansmål. Begreppet handlingsämne används för att beskriva denna syntetiserade kunskap medborgare behöver för att kunna agera i världen. Licentiatuppsatsen har skrivits inom CSD-FL, Forskarskolan för lärare i geografi, historia, religionskunskap och samhällskunskap, en särskild fortbildningssatsning för yrkesverksamma lärare. Centrum för de samhällsvetenskapliga ämnenas didaktik (CSD) vid Karlstads universitet har ansvarat för forskarskolan.