The Baltic Sea is a unique brackish ecosystem with a pronounced gradient in temperature, salinity, and nutrient limitation from north to south. In the northern regions, such as the Bothnian Bay and Bothnian Sea, conditions resemble freshwater ecosystems with lower temperatures and salinity, where phosphorus (P) is the limiting nutrient. Moving towards the Baltic Proper and southern areas, characteristics become more marine-like with higher temperatures and salinity, shifting nitrogen as the limiting factor. Eutrophication affects the southern basins due to significant nutrient inputs from its extensive drainage area, resulting in seasonal phytoplankton blooms dominated by dinoflagellates and diatoms in spring, cyanobacteria in summer, and small flagellates in autumn. Climate change forecasts indicate rising temperatures could reduce salinity alongside increase P release from sediments—factors likely to worsen eutrophication with more filamentous cyanobacteria and increased microbial P recycling post-blooms. Despite these challenges, there is limited focus on how microbial plankton communities strategize P acquisition. This thesis addresses this gap by examining interactions among phytoplankton and bacterioplankton across different Baltic Sea basins. The interplay between different plankton size-classes, stoichiometry and P-acquisition strategies are crucial to understand factors promoting their co-existence in diverse ecological landscapes. Seasonal dynamics of phytoplankton across three basins—Linnaeus Microbial Observatory (LMO) in the Baltic Proper, Bothnian Bay, and Bothnian Sea revealed significant spatial-temporal variations. In spring, northern diatoms dominance contrast with dinoflagellates prevalence in the Baltic Proper; cyanobacteria become prominent during summer except in Bothnian Bay. Despite the differences in community composition, size-fraction protocols and elemental stoichiometry emphasize nanoplankton (<20µm) and picoplankton (<3µm) as major players in nutrient uptake processes throughout these basins. Metatranscriptomic analyses suggest that despite different compositions among basins, microbial planktonic communities shared similar P acquisition mechanisms. Gene expression associated with the membrane remodelling appears as the main mechanism in eukaryotes, it emerges as an essential secondary process in prokaryotes with transporters having a pivotal role. This highlights the critical function of cellular P pools in response to P deficiency, ensuring cellular adaptability and survival despite fluctuating conditions. Overarching trends emerged community-wide, but nuanced differences between prokaryotes (bacteria) and eukaryotes (phytoplankton) highlighted their capacity for adaptation within the different basins. This complex interplay between environmental drivers and biological adaptability deepens comprehension of ecological dynamics within marine ecosystems like the Baltic Sea. 

Extragalactic transients, such as gamma-ray bursts (GRBs), represent the most energetic phenomena in the Universe. They are characterized by their intense radiation within short timescales. In recent years, significant advances have been made in understanding the emission mechanism of GRBs, with the detection of very-high-energy (VHE; >100 GeV) gamma rays. These observations have improved our understanding of VHE gamma-ray emissions in such extreme environments. So far, five GRBs have been detected in VHE gamma rays, intensifying the search for more such detections. The observation of extragalactic sources in VHE gamma rays is challenging due to extragalactic background light (EBL) absorption, which results in softening the source spectrum to energies below a few TeV.

To address these challenges, the ALTO/CoMET R&D project is proposed. This project aims to design a wide field-of-view observatory to observe soft-spectrum sources continuously in VHE gamma rays. To achieve this goal, a dedicated Monte Carlo simulation study is conducted to optimize the configuration of the proposed detectors. An important part of the simulation study is the development of an analysis method called SEMLA (Signal Extraction using Machine learning for ALTO/CoMET), which enables the proposed array to detect gamma rays at energies down to a few hundred GeV. The results from the simulated data analysis demonstrate that ALTO/CoMET is capable of detecting extragalactic transients like GRBs. 

This thesis presents the analysis methods developed, and the results obtained from the ALTO/CoMET R&D project in detecting extragalactic transients, with a focus on GRBs. The lessons learned from these ALTO/CoMET simulation studies and prototype activities are useful for other future extensive air shower detectors, concerning the observation of soft-spectrum VHE gamma-ray sources.

Additionally, the search for GRB emission is explored using the H.E.S.S. array, analysing follow-up observations of GRBs recorded from its construction in 2004 until 2019 (excluding the two significantly detected GRBs by H.E.S.S.).

Even though teachers of the language of schooling and of foreign languages all teach writing in their respective language classrooms, research has shown that few cross-curricular connections are made in their teaching practices (Forbes, 2020; Haukås, 2016; Vikøy & Haukås, 2023). The present PhD project attends to this gap, aiming at (1) showcasing and explaining the complexity of teaching writing in different languages taught at school, and (2) exploring whether and how teachers of different languages may align their teaching approaches to writing. Data were collected at two secondary schools in Berlin, Germany, where German is the language of schooling, English the first foreign language and French or Spanish the second foreign language. 

Nexus analysis (Scollon & Scollon, 2004) served as the theoretical and methodological framework for this study. Theoretically, nexus analysis provided an understanding of teachers’ social actions as mediated by circulating discourses, among which were the Discourses of Writing (DoW) (Ivanič, 2004). Methodologically, nexus analysis provided concepts to divide the research design into two phases: an ethnographic and a design phase. 

The ethnographic observation phase revealed that teachers of German, English, French and Spanish had divergent teaching approaches: the Genre DoW was foregrounded in most German classrooms while writing tasks in the foreign language classrooms were predominantly motivated by the Skills DoW. In both cases, assessment and upcoming examinations often motivated writing tasks. Multilingual teaching practices happened in the form of grammar and vocabulary comparisons while cross-curricular practices meant that teachers drew on or even coordinated teaching content from other language subjects. However, such practices were few and far between and were more opportunistic than systematic. 

In an attempt to systematize these practices, the design phase involved the development of teaching materials. The materials incorporated already circulating discourses (Genre, Skills, assessment among others) but additionally foregrounded the Social Practice DoW. This discourse promotes writing as a social practice with a communicative purpose and encouraged cross-curricular teaching practices because the same or similar materials were used in all language subjects. The materials were multilingual in German, English, French and Spanish and, where appropriate, left space for any additional languages that students might know. This dissertation discusses to what extent teacher–researcher collaborations can foster change in teaching approaches to writing from autonomous to multilingual and cross-curricular ones. 

Keywords: writing, multilingualism, teaching practice, cross-curricular collaboration, nexus analysis, discourse, educational linguistics