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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
291

Investigating plant autophagy with new chemical modulators

Ballhaus, Florentine January 2020 (has links)
Autophagy is a major catabolic pathway in which cell components get sequestered in a double membrane vesicle, transported to the vacuole, degraded by vacuolar hydrolases and recycled.  Through this process, cells ensure cell homeostasis and remobilise nutrients. The autophagic flux can be enhanced as an adaptive stress response, improving plants resistance against stress, reducing aging and ultimately increasing yield. However, autophagy regulation in plants remains poorly understood.  Novel plant-specific modulators can be used in a chemical genetic approach for identification of proteins involved in the autophagy pathway. Furthermore, autophagy enhancers can find their application in agriculture for improved plant fitness. Known autophagy modulators have severe off-target effects, affecting plant growth and development. A recent screening identified two potential autophagy modulators. We developed a novel method for photoaffinity labelling and pulldown assay in Arabidopsis thaliana to identify potential interactors of the modulators. The identification of autophagy-related proteins will help to further elucidate the autophagic pathway in plants. The effect of the new autophagy enhancers on plant growth and development was analysed by automated growth assays. In comparison with a currently available autophagy enhancer, treated plants showed higher viability, indicating possible further applications for the new autophagy modulators in planta.
292

Attityder hos lärare som undervisar programmering i grundskolans årskurs 4 – 6

Nyholm, Carl-Eric January 2020 (has links)
No description available.
293

Habitat preference of the threatened short-necked oil beetle Meloe brevicollis on Öland / Habitatpreferenser hos Korthalsad majbagge Meloe brevicollis på Öland

Therese, Jaensson January 2021 (has links)
Fragmentation and destruction of habitats are major factors in the global decline of species, and it is the leading cause of biodiversity loss. This study examines the threats to the short-necked oil beetle Meloe brevicollis in Sweden. The species currently has an action plan as it is noted on the red listas endangered (EN), however, the knowledge about the threats to the species is still poor and increased knowledge is needed to effectively preserve theshort-necked oil beetle. To identify the threats, inventory data was analysed to find the structures in the landscape that govern the occurrence of the species and how the habitat has changed due to land use, globally and locally. Logistic regression was used to analyse the probability of encountering the species at certain land types. The results showed that coverage had a significant positive effect, thus increasing the probability of finding the short-necked oil beetle. The results also showed that groundmoisture had a significant negative effect on the species, indicating that the short-necked oil-beetle prefers dry land types. The habitat that the species requires, such as pastures and hay meadows, has decreased both globally and locally, indicating that habitat loss and habitat reduction is the biggest threat to the survival of the short-necked oil beetle. / Den biologiska mångfalden riskerar att minska både globalt och lokalt. Habitat som fragmenteras och degraderas är den främsta orsaken till att arter försvinner. Den här rapporten undersöker hoten mot den rödlistade arten Korthalsad majbagge Meloe brevicollis. Arten har idag ett åtgärdsprogram då den bedöms vara starkt hotad (EN), kunskapen kring hoten mot arten är dock ännu fragmentarisk och ökad kännedom kring dessa är helt nödvändig för att arten ska kunna bevaras på ett effektivt sätt. För att identifiera hoten har inventeringsdata analyserats, med utgångspunkt att undersöka artens miljökrav, vilka strukturer i landskapet som styr förekomsten av arten och hur dess habitat har förändrats på grund av markanvändning. Analysen av miljökraven gjordes med hjälp av logistisk regression, för att analysera sannolikheten att påträffa arten vid en viss marktyp. Resultatet visade att det är större sannolikhet att påträffa arten vid en marktyp med hög täckningsgrad på buskskikt, samt lägre sannolikhet att påträffa arten i områden med högmarkfuktighet. Den typen av miljö som Korthalsad majbagge kräver är en miljötyp som har minskat både lokalt och globalt, vilket indikerar att det största hotet mot Korthalsad majbagge är just minskade habitat.
294

Vi : En bok om svamp

Myrén Pettersson, Malte January 2021 (has links)
No description available.
295

Utbredningen av den invasiva arten vresros (Rosa rugosa) på fastlandet i Örefjärden-Snöanskärgårdens naturreservat

Hansson, Anna January 2021 (has links)
The shrub (Rosa rugosa) is an invasive species with incredible competitiveness in sand-dominated environments. The establishment of Rosa rugosa in these areas often leads to suppression of the natural vegetation and overgrowth of the area with a strong negative impact on the native species and on local species diversity. The aim of this study was to do an inventory of the establishment and patch size of Rosa rugosa along the mainland in the Örefjärden-Snöanskärdgården nature reserve for The County Administrative Board in Västerbotten. Based on this, I discuss the risk of spread of the species within the investigated area, which may be helpful in future efforts to control the species. To do this coordinates were taken for each patch of Rosa rugosa with a GPS and the type of shrub, occurrence of shoots, habitat type, exposure degree and if there were houses within 100 meters or not were noted. The results show that there is a significant difference in the average patch size between areas of sand compared to those stone/boulder fields. Patches were larger when houses were within 100 meters than without houses in the neighbourhood. My recommendation for The County Administrative Board is to focus control efforts to the sandy beaches on the protected locations. In addition, there should be focus on the shrubs that grow closest to the shoreline to avoid water dispersal of seeds, and the small individual shrubs which do not have a big root system.
296

Investigation of a spinel-based refractory as a carrier for a steel melt temperature sensor

Berglund, Henrik January 2020 (has links)
This master thesis work explored the possibility to measure the temperature in a steel melt for a longer time. A thermocouple was embedded in a ceramic material based on spinel (MgAl2O4), chosen as a sensor. The ceramic material was evaluated with regard to chemical corrosion from slag, thermal shock, and resistivity. Finally, a functional test in a steel melt was done in Sandvik’s experiment furnace. The corrosion study was made with two ceramic materials, one with a large amount of alumina and the other with a large amount of spinel. The materials were synthesised from different raw materials, which were mixed and sintered at 1000°C and 1650°C. This process led to four materials that were tested against two types of slags, at a temperature of 1600°C for 2 hours. One of the slag types had a large amount of calcium oxide (CaO) and the other a mixture of calcium oxide and added fluorspar (CaF2). The study shows that the spinel-rich material can withstand the corrosive slag better than an alumina-rich material. The thermal shock test was done with the two kinds of ceramic materials that were sintered at the higher temperature of 1650°C. The materials were subjected to a cold shock with a temperature difference of 1080°C which decreased the flexural strength with about 90%. The electrical resistivity test was tested by coating platina wireswith two types of electric insulating layers of a dielectric pasteor a type of cement. These two layers increased the resistance between two embedded wires inside the spinel-rich material at temperatures below 1000°C. The final results from the temperature measurements showed that continuous monitoring of the temperature in molten steel can be achieved by the design of a thermocouple embedded into the spinelmaterial, in shapes of cylindrical lances. Two, essentially identical, sensor lances were immersed 10 cm deep into molten steel, through the corrosive slag line, and measured the temperature in a steel melt around 1500°C. One of the sensors measured temperaturesof 1100-1300°C for 18 minutes, the other sensor measured temperatures around 1400°C for 9 minutes.
297

Effects of Ocean Acidification on Species Composition and Biodiversity in the Region of Kongsfjord (Svalbard)

Grandon, Nathalia January 2020 (has links)
Ocean acidification is a great threat to marine ecosystems and the oceans around the poles are first in line to be affected by the increase in CO2 concentration, effectively damaging the living conditions of marine life present here. This paper analysis and discusses whether studies on the effects of ocean acidification on single species can be used to predict future changes in food web dynamics. The results indicate that by looking at effects on different physiological functions on single species, predictions on how the species in question will cope with a more acidic environment can be made. These predictions can in turn hint on possible changes in the food web. The increase in DOC as well as the shift to smaller and more toxic species of phytoplankton will prove advantageous to bacterioplankton who will play a bigger role in future carbon cycling. The toxic HAB’s could present a hazardous future for primary consumers, but especially secondary consumers. If not affected by the toxicity of the more frequent algal blooms, primary consumers will face negative consequences to the larval recruitment of copepods and shell formation of pteropods by ocean acidification. This would mean a decrease in abundance causing eutrophication and smaller amounts of food sources for fish higher up the trophic cascades, such as the endemic polar cod and the Atlantic cod. Regardless of the general scarcity of data available from these areas, all studies point to a shift in species composition. A clear indication of a future of lower diversity and ultimately an Arctic Ocean with lower ecological resilience.
298

NTA- Från blå låda till kunskap : En studie om NTA:s effektivitet ur ett lärar-och elevperspektiv i årskurs 2 och 3

Rossi, Giovanna, Andersson, Madeleine January 2020 (has links)
No description available.
299

NTA- Från blå låda till kunskap : En studie om NTA:s effektivitet ur ett lärar- och elevperspektiv i årskurs 2 och 3

Andersson, Madeleine, Rossi, Giovanna January 2020 (has links)
No description available.
300

Bidrar utomhusundervisning till bättre förståelse av NO-ämnena? : En litteraturstudie om hur undervisning utomhus påverkar grundskoleelevers inlärning i naturvetenskapliga ämnen / Does outdoor education contribute to a better understanding of science studies? : Impact of outdoor education on students’ understanding in sciences studys - a literature review

Vingren, Johanna, Widén, Johanna January 2020 (has links)
Syftet med denna litteraturstudie är att undersöka vad forskningen säger om utomhusundervisning kopplat till NO-ämnena i grundskolan samt utomhusundervisningens påverkan på elevers kunskapsinlärning i dessa ämnen. Forskningsfrågorna för arbetet har varit; “Vad säger forskning om hur undervisning utomhus kan bidra till en förbättrad inlärning inom NO-ämnena?” och “Vilka uppfattningar har elever och lärare om utomhusundervisningens påverkan på inlärningen enligt forskningen?”. De teorier som vi blivit bekanta med genom vår litteraturstudie och som kommer att redovisas i bakgrunden är; konstruktivism, sociokulturell teori, kognitivistisk teori samt ELT (Experiential Learning Theory). Tillvägagångsättet för den här studien är att vi har läst och analyserat vetenskaplig forskning, sorterat materialet i olika kategorier utefter våra forskningsfrågor och sedan gjort en sammanställning av de resultat vi fått fram. Materialet för vår studie består av tidskriftsartiklar, rapporter, litteraturöversikter och doktorsavhandlingar. Slutsatsen av analysen är att elevers kognitiva utveckling i NO-ämnena påverkas positivt. Utifrån våra 11 artiklar ser både elever och lärare ser positivt på utomhusundervisning och dess effekter även om det framkommer att elever ibland kan uppfatta undervisningen som lek snarare än undervisning.

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