Silicon consumption and population density changes of dominant planktonic diatoms in Lake Constance

(1) Interactions between silicon concentration and diatom growth have been studied in Lake Constance with data on number and volume of cells per unit volume of water and concentration of dissolved reactive silicon. (2) Concentration of dissolved reactive silicon was found to decrease markedly during the spring and summer growth period of diatoms in 1979 and 1980. (3) Amounts of silicon taken up per cell and per unit cell volume have been calculated from the changes in silicon concentration and the increases in population density for several diatom species. The silicon to cell quotient (mg per million cells) varied over a wide range from 0.005 for Stephanodiscus hantzschii to 0.72 for Synedra acus, while that of silicon per unit cell volume (mg mm-3) varied over a narrower range from 0. 10 for Stephanodiscus hantzschii and Fragilaria crotonesis to 0.36 for Synedra acus. (4) A four-compartment model, that allows estimates of the rates of growth and of loss of diatom populations to be calculated, is outlined. (5) Summer succession from Asterionellaformosa to either Fragilaria crotonensis (in 1979) or Stephanodiscus binderanus (in 1980) is explained by interspecific differences in the effects of silicon concentration on growth and death. For Asterionellaformosa, silicon depletion did not stop cell-division but led to the death of most of the population. For Fragilaria crotonensis and Stephanodiscus binderanus cell division stopped but cells did not die and population growth continued after the concentration of dissolved silicon had increased agai

Fungi for Future : Biotechnological application of anaerobic fungi

Der Verwendung Lignocellulose-haltiger Rohstoffe wird eine essentielle Rolle beim Übergang von einer auf fossilen Rohstoffen basierenden zu einer biobasierten Ökonomie beigemessen. Die für die biotechnologische und chemische Nutzbarmachung von Lignocellulose als Ausgangssubstrat nötige Vorbehandlung ist jedoch energieintensiv und/oder produziert toxische Abfälle und Nebenprodukte. Wasserstoff ist ein vielversprechender Energieträger für eine zukünftige Bioökonomie, der jedoch zurzeit hauptsächlich aus fossilen Rohstoffen gewonnen wird. Eine Alternative bietet die biologische Wasserstoffproduktion auf Basis von Lignocellulose, die jedoch zurzeit durch den hohen Energiebedarf der Lignocellulose-Vorbehandlung sowie niedriger Ausbeuten bisher eher unbedeutend ist. Anaerobe Pilze des Phylums Neocallimastigomycota können durch die Sekretion einer Vielzahl von Lignocellulose abbauenden Enzymen auf unvorbehandelter Biomasse wachsen und produzieren hierbei Wasserstoff und andere Plattformchemikalien wie Acetat, Formiat, Lactat, Ethanol und Succinat als metabolische Endprodukte. Trotz des hohen biotechnologischen Potenzials sind diese Organismen und ihre Enzyme weitgehend unerforscht. So sind grundlegende Wachstumsvoraussetzungen nahezu unbekannt und Kenntnisse über ihre Stoffwechselwege und deren Regulierung sind noch begrenzt. Durch Untersuchung dieser Aspekte soll diese Arbeit den Grundstein für eine biotechnologische Anwendung von anaeroben Pilzen legen. Die Nichtverfügbarkeit anaerober Pilz-Stämme in Stammsammlungen stellt eine der Herausforderungen bei der Arbeit mit diesen Organismen da. Der erste Schritt war daher eine Isolation aus dem Kot unterschiedlicher Zootiere, was zum Erhalt von sechs verschiedenen Isolaten führte. Ein aus Alpakakot isolierter Stamm stellte sich als eine neue Pilzgattung und -art heraus, die zuvor nur als SK4-Klade von sequenzierten Umweltproben bekannt war. Interessanterweise wurde der gleiche Stamm gleichzeitig aus dem Pansen eines Mähnenspringers in Texas, USA isoliert. Die Kooperation unserer Forschergruppen mündete in einer gemeinsamen Publikation, welche Kapitel 3 bildet. Isolate von beiden Orten waren nahezu identisch. Sie bildeten mittelgroße (2-5 mm) Kolonien mit einem weißen Zentrum aus Sporangien auf Agar und einen Biofilm aus Myzel in flüssigem Medium. Mikroskopisch waren monozentrische Thalli und sphärische poly-flagellierte Zoosporen mit 7-20 Flagellen zu erkennen. Sowohl die Öffnung einer apikalen Pore des Sporangiums wie auch das Aufbrechen der sporangialen Zellwand führten zur Freisetzung der Zoosporen. Dieser duale Mechanismus ist bisher einzigartig unter allen derzeit beschriebenen anaeroben Pilz-Stämmen. Ein phylogenetischer Vergleich anhand der Sequenzen der D1-D2 28S Untereinheit des rRNA Gens (LSU) und des internal transcribed spacer 1 (ITS1) wies hohe Identitätsübereinstimmungen zwischen allen Isolaten (geringste Identität jeweils 99,07 % und 96,96 %) aber geringe Übereinstimmung zu den nächsten Verwandten auf (jeweils 92,4 % und 86.7 %). Anhand der LSU konstruierte phylogenetische Bäume ordneten die Isolate als neue monophyletische Gruppe in der Orpinomyces-Neocallimastix-Pecoramyces-Feramyces-Ghazallamyces Klade ein. Sowohl die LSU wie auch die ITS1 Sequenzen der Isolate wiesen eine hohe Sequenzidentität zu Umweltproben aus Schafen und verschiedenen anderen Herbivoren auf. Interessanterweise wurden diese Proben der SK4-Klade hauptsächlich bei Tieren gefunden, die auf Sommerweiden grasten, woraus sich die Benennung der neuen Gattung, Aestipascuomyces (abgeleitet vom lateinischen Wort für „Sommerweide“), und der Spezies, A. dubliciliberans, ableitete. Die übrigen fünf Isolate konnten, wie in Kapitel 4 beschrieben, den bereits bekannten Neocallimastigomycota Gattungen und Spezies Neocallimastix cameroonii, Caecomyces spec., Orpinomyces joyonii, Pecoramyces ruminantium, und Khoyollomyces ramosus zugeordnet werden. Während der phylogenetischen Analyse wurde eine hohe Ähnlichkeit zwischen Spezies der Gattung Neocallimastix bemerkt, was zur Neuzuweisung von Neocallimastix californiae und Neocallimastix lanati zu Neocallimastix cameroonii führte. Die Daten befürworteten ebenfalls eine Neuzuweisung der Gattung Cyllamyces als Spezies der Gattung Caecomyces. Kapitel 4 beschreibt ebenfalls die biochemische Charakterisierung aller Isolate inklusive des in Kapitel 3 beschriebenen. Die Pilze wurden auf verschiedenen Kohlenstoffquellen kultiviert und die Produktion der Metabolite Wasserstoff, Acetat, Formiat, Lactat, Ethanol und Succinat, analysiert. Unter den getesteten Bedingungen produzierte Orpinomyces joyonii kein Succinat und Khoyollomyces ramosus kein Lactat. Die Ergebnisse wiesen des Weiteren auf eine sequenzielle Produktion der Metabolite unter Bevorzugung von Wasserstoff, Acetat und Formiat hin. Beim Vergleich der Metabolitproduktion während des Wachstum auf Monosacchariden und auf Stroh fiel eine höhere Wasserstoffproduktion bei letzterem auf. Dies könnte auf eine Reaktion des Metabolismus auf erhöhte Zuckerkonzentrationen hindeuten. Für das robusteste Isolat, Neocallimastix cameroonii G341, wurde ein Dunkelfermentationsprozess im Rührkessel-Bioreaktor entwickelt, was in Kapitel 5 beschrieben ist. Dazu wurden im Vorfeld weitere Optimierungen bezüglich Medienzusammensetzung und Kultivierungsbedingungen vorgenommen. Beim Testen verschiedener Stickstoffquellen führten nur Glutamin und Ammonium zum Wachstum des Isolates. Der Pilz wuchs optimal in einem Temperaturbereich von 38,5 °C bis 41,5 °C und präferierte initiale pH-Werte zwischen 6,6 und 6,8. Die höchste Wasserstoffproduktion fand jedoch bei einem initialen pH-Wert von 6,4 bis 6,6 statt. Zugabe von Wasserstoff zu Beginn des Experiments verringerte die Wasserstoffproduktion. Im Gegensatz dazu konnte durch Erhöhung des Kopfraumvolumens oder durch Agitation die Wasserstoffproduktion erhöht werden, was mit einem Abfall der gebildeten Lactat- und Ethanol-Konzentrationen einherging. Durch Kombination beider Parameter sanken Lactat- und Ethanolproduktion soweit, dass Wasserstoff, Acetat und Formiat nahezu die einzigen Produkte waren. Succinat konnte, wenn überhaupt, nur in Spuren nachgewiesen werden. Nach Etablierung des Prozesses im Rührkesselreaktor konnten die Ergebnisse aus dem Flaschenversuch bestätigt werden. Die Wasserstoffproduktion stieg mit steigender Rührgeschwindigkeit an. Während der Anstieg von 0 rpm auf 250 rpm mit einem Anstieg der Geschwindigkeit der Wasserstoffproduktion einherging, verlangsamte eine weitere Steigerung auf 600 rpm dessen Produktion. Ein ähnlicher Effekt trat beim Vergleich von Fermentationsprozessen mit und ohne pH Regulation auf. Wurde der pH-Wert konstant bei 6,8 gehalten, verdoppelte sich im direkten Vergleich zu nicht-pH regulierten Prozessen die Produktion aller Metabolite mit Ausnahme von Lactat. Diese Ergebnisse führten zu dem Schluss, dass Wasserstoff der präferierte Elektronenendakzeptor von Neocallimastix cameroonii sein könnte. In diesem Fall würden Lactat und Ethanol nur produziert, falls eine thermodynamische Beeinträchtigung der Wasserstoffbildung vorliegt. Die höchste Wasserstoffausbeute (2,406 mmol/g = 58,84 ml/g) resultierte aus Flaschenversuchen mit 5 g/l Stroh als einziger Kohlenstoffquelle mit erhöhtem Kopfraumvolumen und Agitation. Im Literaturvergleich entspricht dies ungefähr 33-50 % der für die Dunkelfermentation angegebenen Wasserstoffausbeuten auf Basis von Stroh. Allerdings wurden bei diesen Studien diese Ausbeuten nur nach einer intensiven Vorbehandlung des Strohs erzielt. Weiterhin ist der hier beschriebene Prozess mit anaeroben Pilzen noch nicht optimiert. Auch wenn das Potential anaerober Pilze, lignocellulose-haltige Biomasse effizient zu hydrolysieren, weithin bekannt ist, und eine Vielzahl ihrer Enzyme bereits heterolog exprimiert wurden, sind die wenigsten biochemisch charakterisiert. Dies betrifft besonders hemicellulolytische Enzyme, welche verglichen mit cellulolytischen Enzymen weit weniger erforscht sind. Kapitel 6 behandelt daher die Expression von Neocallimastigomycota Hemicellulasen und deren biochemische Charakterisierung. Nach ihrer Identifikation im Pilzproteom von Neocallimastix californiae konnten die GH43 Xylosidase Xyl43Nc und die GH11 Endoxylanase X11Nc in Escherichia coli exprimiert werden. Xyl43Nc wies eine hohe Aktivität gegen 4-Nitrophenol-Xylopyranosid (Km = 0,72 mM und kcat = 29,28 s-1) bei einem Temperaturoptimum von 32 °C und einem pH Optimum von 6 auf. Bei gemeinsamer Verwendung von Xyl43Nc und X11Nc konnte Xylose aus Buchenholzxylan und Weizen-Arabinoxylan freigesetzt werden. Phylogenetische Analysen von Xyl43Nc zeigten einen gemeinsamen Ursprung mit Enzymen aus Spirochaeten. Das Enzym bildete eine monophyletische Gruppe abseits der Sequenzen von Ascomyceten im phylogenetischen Baum. Hieraus ließ sich ein Ursprung des Enzyms aus horizontalem Gentransfer ableiten. Zusammengefasst legt diese Arbeit den Grundstein für eine zukünftige biotechnologische Anwendung anaerober Pilze und deren Enzyme

Chapter Unlikely followers of fashion? Dressing the poor in late medieval Bruges

Surprisingly little is known about the way the poor strata of urban society in the late medieval period used dress to express social identities. Systematic empirical data have not been available, and sources tend to illustrate the opinion of the elites about poverty. Through the analysis of cloth distribution by charitable institutions and, above all, of a unique set of inventories for fifteenth-century Bruges, it becomes clear that dress was not only an important element in the material culture and the construction of social identity of the poor, but that instead of being a passive player depending on charity and alternative commercial circuits, the poor used dress to conform to fashion cycles set by the wealthier groups in urban society. In late medieval Bruges, they were wearing the same typology of dress, the same colours and the same fabrics, displaying in this way a willingness to participate and invest in fashion cycles. In assessing both urban economies and social dialogue, scholars should therefore not focus on elite demand alone

„Sztuka nauczania” – prezentacja programu kształcenia nauczycieli Waldorf w Rudolf Steiner University College w Oslo, Norwegia

-

Supported to Stay in School: How Students’ Perceptions of the Psychosocial Learning Environment are Related to Intentions to Quit Upper Secondary School

Background: National and international research has repeatedly shown that many late adolescents have poor motivation for school. Moreover, the fact that a considerable proportion of youth do not complete upper secondary education is an insistent challenge with severe costs for the individual and society. This thesis concentrates on upper secondary students’ intentions to quit school, which is considered an indicator of a negative motivational process that can lead to dropout from school. From a motivation theory perspective (self-determination theory, in particular), intentions to quit school is considered a persistence-related academic outcome. A theoretical rationale based on self-determination theory (SDT) and achievement goal theory (AGT) of how and why perceptions of the psychosocial learning environment may contribute to the development of such intentions is proposed. Emanating from this theoretical ground and previous evidence, research questions considering how the following aspects of the psychosocial learning environment are related to intentions to quit school were posed: perceived teacher support (emotional support, autonomy granting, and feedback quality), loneliness among peers, and perceived mastery climate. Thus, while decades of research on school dropout have focused on demographic factors and students’ academic achievement level, the current approach scrutinizes the potential in the learning environment on a process that do not limit itself to the final “pass or fail” (dropout vs. completion) yet acknowledges the broader and gradual process of the individual’s more or less prominent intentions to quit school. Enhanced knowledge regarding this process can be vital from a dropout preventive perspective, but also for increased understanding of how the psychosocial learning environment in upper secondary school is related to student motivation. Aims: The overall aim was to empirically investigate how students’ perceptions of the psychosocial learning environment in upper secondary school are related to their intentions to quit school. Three separate studies had specific aims subordinate to this. Hopefully, knowledge derived from this work can contribute to inform measures to optimize students’ motivation and increase their likelihood of completing upper secondary education. Methodology: The thesis has a quantitative approach, and all three studies were empirical investigations of a sample of 1379 students in upper secondary schools in Rogaland, Norway. The main data source was self-reports from these students on three occasions during upper secondary school: T1 in the second semester of the first year, T2 in the first semester of the second year, and T3 in the second semester of the second year, giving a total timespan of 13 months. In addition to self-reports, register data on students’ previous academic achievement, gender, and study track in upper secondary were obtained from county administration, which were applied as control variables in the structural models. Study I had a cross sectional design, and Study Ⅱ and Study Ⅲ had longitudinal panel designs. To investigate the specific research questions, different statistical methods were applied, primarily types of structural equation modeling (SEM) in Mplus. This included confirmatory factor analyses (CFA), mediation models, multigroup testing of moderation, latent growth curve models (LGCM), and growth mixture models (GMM). Results: In the cross-sectional design of Study Ⅰ, the main aim was to investigate the degree to which three aspects of perceived teacher support (i.e., emotional support, autonomy granting, and feedback quality) were related to intentions to quit school, directly, and/or indirectly via emotional engagement and academic boredom. Relevant individual background variables (gender, prior academic achievement, immigrant background, as well as study track) were accounted for. The SEM results showed that all three aspects of perceived teacher support were indirectly negatively associated with intentions to quit school. In addition, emotional support showed a direct negative association with intentions to quit and thus appeared to be a particularly important aspect of perceived teacher support. In Study Ⅱ, the main aim was to investigate intentions to quit school longitudinally, and specifically scrutinize how individual change in intentions to quit was related to initial levels and changes in perceived emotional support from teachers and loneliness among peers at school. Initially, unconditional latent growth curve models indicated an average increase in intentions to quit school and loneliness among peers during the study period, and no average change in emotional support from teachers. However, substantial individual differences were found in the trajectories of all these three concepts. A multivariate latent growth curve model with the rate of change in intentions to quit as the final outcome showed no significant prediction from initial levels of either emotional support or loneliness; however, a substantial inverse associated change with perceived emotional support from teachers and a strong positive association with change in loneliness among peers was found. In Study Ⅲ, individual change in intentions to quit school was kept as the focal outcome yet investigated from the outset of potential trajectory subgroups of perceived emotional support from teachers. The substantial between-student differences in individual trajectories of perceived emotional support detected in Study Ⅱ served as an important ground for this person-centered approach. Furthermore, change in perceived mastery climate was theorized to function as an intermediate variable in a hypothesized association with change in intentions to quit school. Three distinct trajectory subgroups of perceived emotional support from teachers were identified: stable-high (84.9%; the normative group), decreasing (7.8%), and low-increasing (7.3%). Compared to the normative group, membership in the decreasing emotional support trajectory subgroup was indirectly associated with more increase in intentions to quit, and this association was fully mediated by a more negative development in perceived mastery climate. Membership in the low-increasing group was associated with more positive development in mastery climate, but no significant indirect association with change in intentions to quit was found. Conclusion: Prominent in all three studies, was the central role of perceived emotional support from teachers as negatively associated with students’ intentions to quit school. This was also persistent when accounting for background variables, and predominantly when investigating longitudinal relationships. Students with decreasing trajectories of perceived emotional support during the first and second years of upper secondary school were more likely to have steeper increase in intentions to quit school during this phase. However, the opposite route was not supported and requires further research. In addition to emotional support from teachers, individual trajectories of loneliness among peers were closely related to individual trajectories of intentions to quit school, and these results add to previous research conducted in cross-sectional designs. In sum, the current work contributes to empirical support for psychosocial factors in school having a substantial potential to keep students motivated to continue upper secondary school, and this should be considered in all efforts to enhance late adolescents’ academic motivation and to increase upper secondary completion rates

Entrance to and advancement within the Swedish medical labour market for physicians with a medical degree from outside the European Union

Background Many physicians who migrate wish to continue practicing medicine in their destination country. However, they may meet barriers and obstacles that prolong the process of entering and advancing within the destination country’s medical labour market. Migrant physicians’ competences are needed, and if fully utilised, it will be beneficial for them, the patients, the medical workforce, and for society. Aim The aim was to explore the entrance to and the advancement within the Swedish medical labour market for physicians with a medical degree from outside of the EU/EEA. Method The study participants were mainly physicians who had enrolled in a complementary programme for physicians with a medical degree from outside the EU/EEA and Switzerland. Both qualitative and quantitative methods were used. Study I included semi-structured interviews with 24 physicians. Study II was a cross-sectional study that included questionnaire data from 283 respondents. Study III included test data from physicians with a medical degree from outside the EU/EEA who had taken a licensing exam 2013–2019 (n = 564), and 14 semi-structured interviews. Study IV included questionnaire data from 101 respondents, and four semi-structured interviews. Interview transcripts and questionnaire free-text answers were thematically analysed. For Study II, the statistical data were descriptively analysed. For Study III, linear and logistic regression analysis were used. In Study IV, descriptive and inferential statistical analyses were performed on the data. To understand and discuss how MPs enter and advance within the medical labour market in Sweden, Bourdieu’s concepts of the social field, symbolic capital and doxa were used as a lens. As a complement to Bourdieu’s theory, self-determination theory (SDT) was used. Results In Study I, several conceptions about working in rural and remote areas in Sweden were identified. These regarded the themes finding work, work content and tasks, and living. Conceptions about working in a certain type of area gave rise to conceptions about what it would be like to live in the same area. The participants’ conceptions derived from their own and from others’ experiences; and conceptions influenced study participants’ motivation of where to work, negatively or positively. In Study II, 88% of the respondents held a position as a physician when answering the questionnaire, but they were in varying stages of their careers from one another; as they also had begun the complementary programme at different times. The respondents had mainly found their first job after the programme via spontaneous job applications, during internships or via friends or other programme participants. Barriers and facilitating aspects as well as the different strategies they used were explored. During their job-seeking process, the respondents reported experiencing discrimination or having their competences undervalued. To increase job prospects, the respondents had, for example, worked as assistant nurses or medical assistants before beginning the complementary programme. Respondents had developed their language by using different resources. Due to high labour market conditions, respondents had moved or changed specialty to increase job prospects. Study III revealed that age was a predictor for succeeding on the licensing exam, and that the complementary programme seemed to reduce the negative age effect for participants aged 45 years or older. In the qualitative material, perceived influential aspects for succeeding or failing on the exam related to the two themes preparations and biographical aspects, and to the exam and exam situation. Study IV explored aspects that influenced choices of employment and specialty, and found that the most important aspects related to choosing employment were the ability to combine work with family, and possibilities for developing competences. The majority of the respondents had specialised in general medicine, and women were more likely to specialise in general medicine than men. Influencers on the interviewees’ motivation and choice to specialise in general medicine related to the themes of job opportunities, positive experiences from PHC, working conditions and family conditions. Conclusions Barriers and limiting circumstances may derive from the micro and meso levels, and influence on a micro level; however, individuals still have agency. They can influence their paths to the labour market and advance within it through certain strategies and/or facilitating aspects. Many barriers and facilitating aspects corresponded to one another and were two sides of the same proverbial coin. The social context and environment influenced the study participants’ choices regarding where to work and in which specialty. Aspects relating to work life and private life collaborated to influence motivation and choices. As a group, these MPs could be interpreted as being hierarchically positioned lower in the Swedish medical field than physicians who trained in the country. However, on an individual level, this may not hold true, as the group is heterogeneous in terms of gender, ethnicity, country of origin, country for medical education, and age. Influential aspects on the macro, meso and micro levels may change over time