GLORIA Slope Approach - Monitoring Plant Community Changes in Mountain Ecosystems

The research described in this presentation is part of the Global Observation Research Initiative in Alpine Environments (GLORIA) whose purpose is to establish and maintain a global, long-term observation network in alpine environments. Despite changes in mountaintop-vegetation due to recent climate change being observed throughout the world, trends are not consistent. Moreover, as plant communities can be impacted by several different factors, it is important to be able to separate what is due to climate change and what is due to e.g. changes in grazing pressure (see additional file below)

Système politique et mobilité sociale

L'analyse des processus de mobilité sociale mobilise l'intérêt des sociologues depuis une trentaine d'années ; pourtant ni ce terme ni les concepts auxquels il fait appel ne font l'objet d'un consensus en sociologie. Le débat qui s'est développé autour de ce problème semble s'ordonner selon deux axes. D'une part, des discussions de type technique, de l'autre des oppositions plus radicales de nature théorique ou épistémologique. Le premier plan concerne tous les problèmes liés à la constitution et à l'interprétation des indicateurs de mobilité sociale : définition de critères permettant de constituer les classes ou groupes sociaux, mesure du flux de mobilité, problèmes liés à l'existence d'une mobilité structurelle, etc. Le second axe, d'une nature différente, met en question la légitimité du concept de mobilité sociale et, par conséquent, l'utilité de ce type de recherche quelles qu'en soient par ailleurs les modalités techniques (...)

Molecular studies of genetic structuring and demography in Arabidopis from Northern Europe

The seed bank is an important part of plant population dynamics, capable of storing genotypes accumulated over several seasons, thereby creating a genetic reservoir which can resupply the above ground population regularly or after disturbance events. Thus, the seed bank can function to increase genetic diversity and effective population size in the population as a whole. Additionally, the seed bank can restore the above ground population if it is reduced or even completely destroyed. Consequently, seed banks may have an impact on both the ecology and evolution of species. In this thesis, I have mainly investigated effective population size, generation time and geographic patterns of structuring in two closely related crucifers, Arabidopsis thaliana and A. lyrata, especially how this is impacted by the presence of a seed bank. They are both naturally occurring in Norway, inhabiting disturbed habitats with low levels of competition. It has been suggested that the species diverged from each other approximately 5-9 million years ago. Due to the availability of molecular tools for this genus, they are widely used in research focusing on e.g. variation in physiological and morphological traits and how this may affect evolutionary processes such as local adaptations to environmental conditions. Both A. thaliana and A. lyrata harbour seed banks, although the density of seedlings and the impact of this cohort on effective population size (Ne) seem to be different. A. thaliana have a higher seedling density as seen from soil sample germination, and its seed bank cohort contribute more to Ne, compared to in A. lyrata. Both species show a geographically structured pattern throughout the Norwegian distribution range, although differentiation between populations is much higher in A. thaliana. This indicates that populations of A. thaliana are more isolated, and this may be due to differences in mating system and habitat characteristics. A. thaliana is an annual species, and population dynamics in this species should therefore be more dependent upon the seed bank than in A. lyrata, which is perennial and therefore should exhibit more stable population size and composition. The latter is also capable of vegetative spread by sending out lateral stolons, thus producing new rosettes genetically identical with the mother plant and further reducing the need for high annual seedling recruitment. The amount of clonal genets, as well as the size of these genets, vary within a population, and are more likely related to resource availability than plant density. Clonality is found to cause fine scale genetic structure in a large population of A. lyrata at Spiterstulen, Norway. However, there was no overall population structure, and topographic features believed to constitute barriers for gene flow did not seem to cause genetic substructures. Still, it is not yet clear how seed flow and pollen flow act separately on spatial genetic structure in the population. Whereas A. lyrata is strictly outcrossing throughout most of its distribution range, A.thaliana is almost exclusively self-pollinating, and plant-pollinator interactions have not been explored thoroughly in this species. It is shown that insect visitation rates in a Central Norwegian population is about ten times higher than a similar study from Germany, but this did apparently not result in outcrossing events during the observation season. However, evaluation of genotypic data from other seasons in this population show that outcrossing events do occur, and this highlights the importance of a more comprehensive sampling regime when trying to describe population genetic structure.PhD i biologiPhD in Biolog

The Effective U(1)×O(3) Theory of Superconductivity and Antiferromagnetism - Derivation and Critical Properties

Vi utvikler og tar i bruk metoder fra feltteori for å forstå koeksisterende og konkurrerende kvantemekaniske tilstander. Utover en fundamental interesse for ikke-relativistiske kvantefeltteorier med flere spontant brutte symmetrier er dette relevant for å beskrive egenskaper ved høytemperatur-superledning. I den første delen av avhandlingen tar vi i bruk funksjonalintegralformalismen i mangepartikkelteori for å studere vekselvirkende fermionsystemer med både magnetisk og superledende orden. Med utgangspunkt i en mikroskopisk teori for fermionene formulerer vi en effektiv lavenergiteori som beskriver konkurransen mellom ordenene. Under milde antakelser for den mikroskopiske modellen utleder vi analytiske uttrykk for alle romlig uniforme ledd i denne teorien. For tilfellet med antiferromagnetisme og superledning studerer vi under hvilke omstendigheter den globale symmetrien til systemet utvides fra $\mathsf{U}(1)\times \mathsf{O}(3)$ til $\mathsf{O}(5)$ ved koeksistens. I den andre delen bruker vi renormaliseringsgruppemetoder til å studere kritiske egenskaper ved lavenergiteorien som beskriver antiferromagnetisme og superledning. Vi demonstrerer eksplisitt at fluktuasjoner i gauge-feltet gjør det umulig å realisere den symmetriutvidede teorien. I likhet med tidligere studier av den Abelske Higgs-modellen finner vi også i denne teorien at $\epsilon$-ekspansjonen predikerer en fluktuasjonsindusert førsteordens faseovergang. Mer spesifikt fremviser teorien et ikke-trivielt ladet fikspunkt som beskriver koeksisterende antiferromagnetisme og superledning hvis antallet komplekse komponenter til den superledende ordensparameteren utvides til $N > N_c \approx 185.4$.We develop and explore field-theoretical techniques for understanding coexisting and competing quantum phases of matter. Apart from the fundamental interest in non-relativistic quantum field theories with multiple spontaneously broken symmetries, our study is relevant for describing properties of high-temperature superconductors. In the first part, the functional integral formalism of many-body theory is employed to study interacting fermionic systems with both magnetic and superconducting orders. Starting out from a microscopic theory of fermions, we formulate a low-energy effective theory describing the competition between the orders. Under mild assumptions on the electron band, we derive closed-form expressions for all the spatially uniform terms of this theory. For the case of antiferromagnetism and superconductivity, we study under what conditions the global symmetry of the theory is enhanced from $\mathsf{U}(1) \times \mathsf{O}(3)$ to $\mathsf{O}(5)$ at coexistence. In the second part, we use renormalisation group methods to study critical properties of the said low-energy theory of antiferromagnetism and superconductivity. We show explicitly how fluctuations of the gauge field make the symmetry-enhanced situation impossible to realise. In line with previous studies of the Abelian Higgs model, the $\epsilon$ expansion predicts a fluctuation-induced first-order superconducting transition also in this model. Specifically, the theory exhibits a non-trivial charged fixed point describing coexisting antiferromagnetism and superconductivity if the number of complex components of the superconducting order parameter is artificially extended to $N > N_c \approx 185.4$

Transglycosylation by Glycoside Hydrolases - Production and modification of alkyl glycosides

To enable the transition to a green, bio-based economy, an extensive enzymatic toolbox competitive to traditional chemical procedures is needed. One strong area for enzymes is carbohydrate chemistry, due to the over-functionalized nature of carbohydrates, difficult to handle in traditional chemistry. Glycosylation can be catalyzed by four main classes of enzymes, glycosyltransferases, glycoside phosphorylases, transglycosylases and glycoside hydrolases. For industrial implementation, transglycosylases are ideal catalysts that do not need the expensive activated donors associated with glycoside phosphorylases and glycosyltransferases. In addition, they completely lack the hydrolytic activity intrinsic in the closely related glycoside hydrolases. Unfortunately, very few transglycosylases with limited substrate specificities exist in nature, while a wide abundance of glycoside hydrolases are available. To expand the enzymatic toolbox for synthetic chemists it would be favorable to convert glycoside hydrolases into transglycosylases, by limiting their hydrolytic activity. This dissertation investigates the transglycosylation activity of glycoside hydrolases with synthesis and modification of alkyl glycosides, a widely applicable type of surfactants, as model reactions. Reduced hydrolysis for β-glycosidases from the thermophilic Thermotoga neapolitana was achieved through protein engineering, limiting water content and increasing pH. Complete elimination of the hydrolytic activity with maintained transglycosylation was achieved for synthesis of hexyl-β-D-glucoside and the factors resulting in the success are discussed. In addition, extension of the glycosidic part of alkyl glycosides through the coupling activity of cyclodextrin glucanotransferases is explored. An enzyme kinetics study was undertaken to deduce the optimal reaction conditions to promote coupling for a commercial enzyme. Moreover, a novel cyclodextrin glucanotransferase from Carboxydocella species was characterized, shown to have good coupling activity with γ-cyclodextrins as donor. This previously poorly studied donor can be used to extend the range of alkyl glycosides that can be produced and thereby the number of applications available

Reducing Energy Cost with Distributed Energy Systems

Det europeiske energimarkedet har i 2022 og 2023 vært preget av betydelig høyere, og til tider mer volatile priser. De fremtidige prisene forventes å være lavere enn dette, men fortsatt høyere og mer volatile enn det historiske gjennomsnittet for det foregående tiåret gjennom i hvert fall 2030-tallet. Industrisektoren møter da økte energikostnader og usikkerhet. Samtidig har kostnadene for solcellepaneler (PV) og batterienergi-lagringssystemer (BESS) sunket mye det siste tiåret. Derfor er det relevant og rettidig å se på om bruk av PV og BESS i et distribuert energisystem (DES) kan bidra til å redusere energikostnadene for fabrikker i industrisektoren. For å undersøke dette gjennomførte vi et casestudie av ‘Hennig-Olsen Is’ (HOI) lokalisert i Hannevika i Kristiansand. Etter et innledende litteraturstudie ble primærdata samlet inn ved fabrikken til HOI gjennom semistrukturerte intervjuer, uformelle møter, og en omfattende fabrikkomvisning. Deretter ble omfanget avgrenset før analysen ble utført. Analysen ble gjort i en spesialisert programvare for DES-analyse kalt HOMER Grid. Fremtidige energiprisprognoser fra Statnett og Norges vassdrags- og energidirektorat ble brukt til å simulere energipriser gjennom prosjektets levetid. Resultatene av analysen indikerer at investering i DES i 2024 trolig ikke er lønnsomt da de fremtidige energiprisene ikke forventes å være høye nok til å rettferdiggjøre investeringskostnadene. Samtidig indikerer analysen av 2030-scenarioene at det kan være lønnsomt å vente med å investere til 2030. Leasing av solcellepaneler ble vurdert som det foretrukne alternativet da det ga en bedre nåverdi og ble ansett som mindre risikabelt enn kjøp. Analysen viser at BESS kan redusere effektleddet gjennom “peak shaving", mens PV reduserer energileddet ved å erstatte elektrisitet fra nettet i sanntid. Imidlertid er disse kostnadsreduksjonene ganske sterkt påvirket av case-spesifikke faktorer som energiforbruksmønstre og strømavtaler. En sensitivitetsanalyse ble utført for å fastslå de nødvendige kostnadsreduksjonene for å gjøre ulike DES-konfigurasjoner lønnsomme. Resultatene viste at det er behov for betydelige kostnadsreduksjoner, særlig angående BESS. Nøkkelord: Distribuert energisystem, lønnsomhetsanalyse, reduksjon av energikostnade