• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 330
  • 207
  • Tagged with
  • 537
  • 537
  • 537
  • 537
  • 47
  • 45
  • 41
  • 34
  • 34
  • 32
  • 26
  • 26
  • 21
  • 21
  • 21
  • 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.
11

Naturvårdsbränningens effekter på botten- och fältskiktsvegetation

Andersson, Madelen January 2018 (has links)
Forest fires are an important part of the boreal forest ecosystem but have become very reduced in Sweden over the past 100 years. To recreate this feature in nature, prescribed forest fire has become a management method used to promote biodiversity. The purpose of this study was to investigate the effects of prescribed forest fire on the ground and field layer vegetation in terms of vegetation structure, species composition, coverage ratio, biomass and soil pH. The study was conducted in the Brännan Nature Reserve where prescribed forest fires have been implemented on several occasions during the past 21 years, which also made it possible to compare several areas and investigate effects over time. Four sub-areas were studied, three previously fire-affected areas and one control area. The result shows that prescribed forest fires influence the ground and field layer vegetation, and there were significant differences between the areas. The vegetation structure changed, and new conditions were created for subsequent successional processes. The effective number of species decreased after the fire but subsequently increased over time. The percentage of vegetation cover showed the same result with a rapid re-establishment rate, especially during the 6 following years. Biomass production reached the highest value 21 years after the fire, but showed a declining trend compared to the control area. There was no significant difference regarding soil pH, which was expected. There are many factors that may affect the short- and long-term effects of prescribed forest fires, such as fire intensity and the soil depth reached by the fire, but despite variations among the areas, some trends were found.
12

Stressnivå hos öring (Salmo trutta) - effekt  temperatur och predatornärvaro : Kortisolnivåer hos öring i akvariemiljö vid minskad temperatur och vid närvaro av lake (Lota lota) / Stress level in trout (Salmo trutta) - effect of temperature and predator presence : Cortisol levelsin in trout in aquarium environment at reduced temperatures and in presence of Burbot (Lota lota)

Batool, Mustafa Kamil January 2018 (has links)
No description available.
13

Inhibition of SIRT1 Alters Apoptotic and Sex Related Genes in Zebrafish (Danio rerio)

Aarseth Larsson, Kim January 2014 (has links)
Sirtuin 1 (SIRT1) is a nicotinamide adenine dinucleotide - dependent deacetylase that belongs to the sirtuin protein family. The protein has been linked to both cancer through its effect on p53 and age related illnesses through its effect on peroxisome proliferator-activated receptor gamma (PPAR-γ). Recent data have shown a correlation between SIRT1, male fertility and spermatogenesis. Because the mechanism of sex differentiation in zebrafish is still not wellunderstood the sirt1 gene is an attractive target to study in order to improve our understanding of this topic. Zebrafish of different age were exposed to various concentrations of EX-527 toinhibit the SIRT1 protein. This was followed by qRT-PCR analysis of apoptotic and sex-related genes. Both apoptotic and sex-related gene expression levels were affected by the exposure. There were differences in genes that were affected, both between the concentrations of EX-527, and between the ages of the exposed zebrafish. The male- specific gene sexdetermining region Y box 9A (sox9a) was down-regulated at both studied EX-527 concentrations in both zebrafish larvae and juveniles. The exposure of the EX-527 resulted in no significant difference in sex-ratio. Further studies are required to describe the pathway for SIRT1 gene regulation in zebrafish. / Sirtuin 1 (SIRT1) är ett nicotinamide adenine dinucleotide-beroende deacetylas som tillhör proteinfamiljen sirtuiner. Proteinet har kopplats till både cancer genom sin effekt på p53 och åldersrelaterade sjukdomar genom sin effekt på PPAR-γ (Peroxisome Proliferator-Activated Receptor gamma). Ny data har även visat ett samband mellan SIRT1, manlig fertilitet och spermatogenes. Då mekanismen för sexdifferentiering hos zebrafiskar fortfarande inte är väl förstådd är sirt1 genen ett intressant mål att studera för att öka förståelsen kring detta ämne. Zebrafiskar av olika ålder exponerades för olika koncentrationer av EX-527 för att inhibera SIRT1 proteinet. Därefter gjordes qRT-PCR analys av apoptotiska och sexrelaterade gener. Både apoptotiska och sexrelaterade geners utrycksnivåer påverkades av exponeringen. Vilka gener som påverkades och hur, skiljde sig i de flesta fall både mellan koncentrationerna av EX-527 som de utsatts för, och mellan åldern på zebrafiskarna. Den han-specifika genen sox9a (sex determining region Y box 9A) var nedreglerad i båda undersökta EX-527 koncentrationerna hos både zebrafiskar i larvstadiet och hos juvenila. Exponeringen av EX-527 gav ingen signifikant skillnad av könskvoten. Vidare studier krävs för att kunna beskriva signalvägen för SIRT1 genreglering i zebrafiskar.
14

Rörelseaktiviteter och barns koncentrationsförmåga : Pedagogers upplevda samband mellan barns koncentrationsförmåga och fysisk aktivitet / Movement activities and children’s concentration ability : Educator’s experienced relationship between children’s ability to concentrate and their access to physical activity

Sanhueza, Helena January 2018 (has links)
No description available.
15

BACTpipe : Characterization of bacterial isolates based on whole-genome sequence data

Álvarez-Carretero, Sandra January 2016 (has links)
The technological advances have led to faster and more cost-effective sequencing platforms, making it quicker and more affordable to generate genomic sequence data. For the study of bacterial genome, two main methods can be used, whole-genome sequencing and metagenomic shotgun sequencing, of which the first is the mostly used in the past years. As a consequence of these advances, a vast amount of data is currently available and the need of bioinformatics tools to efficiently analyse and interpret it has dramatically increased. At present, there is a great quantity of tools to use in each step of bacterial genome characterization: (1) pre-processing, (2) de novo assembly, (3) annotation, and (4) taxonomic and functional comparisons. Therefore, it is difficult to decide which tools are better to use and the analysis is slowed down when changing from one tool to another. In order to tackle this, the pipeline BACTpipe was developed. This pipeline concatenates both bioinformatics tools selected based on a previous testing and additional scripts to perform the whole bacterial analysis at once. The most relevant output generated by BACTpipe are the annotated de novo assembled genomes, the newick file containing the phylogenetic relationships between species, and the gene presence-absence matrix, which the users can then filter according to their interests. After testing BACTpipe with a set of bacterial whole-genome sequence data, 60 genes out of the 18195 found in all the Lactobacillus species analysed were classified as core genes, i.e. genes shared among all these species. Housekeeping genes or genes involved in the replication, transcription, or translation processes were identified
16

On the determination of early cell differentiation in amphibian embryos

Landström, Ulf January 1977 (has links)
digitalisering@umu.se
17

Sambandet mellan vattenflöde och täthet av lax- och öringsyngel i Gullspångsälven : Vilka åtgärder med avseende på vattenflödet kan stärka populationen?

Björn, Malin January 2017 (has links)
Hydropower is a renewable energy source that can be regulated when needed, but it creates barriers in rivers and causes hydrological changes in water flow. This reduces biodiversity and prevents migratory fish from completing their lifecycle. This threat from humans has reduced salmon populations worldwide. The rate of water flow can affect smolt production, and this will be investigated in this report for Atlantic salmon and Borwn trout in the river Gullspångsälven. In addition, I will suggesting which measures should be prioritized to sstabilize the population. The flow in the river Gullspångsälven is regulated by the hydropower plant at Gullspång. A correlation between the density of salmon and trout and water flow in januari, when waterflow is high, May, when the salmonids swim up from their spawning gravel and august, when waterflow is low. I found no distinct trend between the waterflow and density in the river. There were significant differences for salmon in January and May. This result may be due to species-specific properties that are influenced different by water flow or in Gullspångsälven there is a short-term regulation that probably affects salmon and trout populations negatively.
18

Urban biologisk mångfald - En jämförelse av sex europeiska städer

Andreasson, Tor January 2020 (has links)
Samtidigt som den biologiska mångfalden fortsätter att minska har urbaniseringen en motsatt trend. Som ett av de största hoten mot den biologiska mångfalden krävs det att städerna anpassas på ett sätt som gör att det finns en möjlighet för att förlusten av biodiversitet kan avta. Syftet med studien har av den anledningen varit att undersöka hur sex städer i Europa arbetar för att gynna biologisk mångfald och framförallt i vilken utsträckning deras strategier stämmer överens med aktuell forskning.Studien består av en litteratursammanställning, där resultatet utgör grunden för en analys och jämförelse av sex europeiska städers naturvårdsplaner. Från sammanställningen kunde fem faktorer och åtgärder identifieras som viktigast för att gynna biologisk mångfald i urbana miljöer – skydd av viktiga habitat, anslutning av grönområden, restaurering av habitat och grönområden, allmänhetens deltagande och ett artspecifikt perspektiv. De sex europeiska städerna som inkluderades i studien är Berlin, Bryssel, Hamburg, Köpenhamn, London och Malmö. Resultatet från jämförelsen av städerna visar att det finns stora skillnader i hur de arbetar för att gynna biologisk mångfald i urbana miljöer, både gentemot varandra och den aktuella forskningen. Ingen av städerna har med samtliga fem faktorer i sina naturvårdsplaner. / While biodiversity continues to decrease, urbanization has an opposite trend. As one of the greatest threats towards biodiversity it demands for the cities to adjust in a way that creates opportunity for the biodiversity loss to stagnate. The purpose of the study is therefore to analyze how six European cities work to support biodiversity and mainly to what extent their strategies correspondent to current research.The study consists of a systematic literature review, where the result constitutes the basis of an analysis and comparison of six European cities strategies for biodiversity. From the review, five factors could be identified as the most important to support biodiversity in urban environments – protection of important habitats, connectivity of green areas, restoration of habitats and green areas, public participation and a species-specific perspective. The six European cities that was included in the study is Berlin, Brussels, Hamburg, Copenhagen, London and Malmö. The result from the comparison shows that there are differences in how the cities work to support biodiversity in urban environments, towards each other as well as to current research. None of the cities include all five factors in their strategies.
19

Upplevelser av att arbeta med brukarstyrda inläggningar på en slutenvårdsavdeling

Meybohm Björkman, Elina, Gustle, Ivar January 2018 (has links)
No description available.
20

Transcriptomic analysis on freshwater mussels for identification of potential biomarkers to monitor water ecosystems

Joyon, Md Mehedi Hasan January 2020 (has links)
Stress-specific expression of cellular proteins in responses to exogenous exposure and resulting physiological alteration provides important insight into the field of ecological research. Due to its habitat, feeding, lifestyle and physiologic properties, mussel has become an important indicative measure of aquatic environment pollution in order to assess effect of these pollution in aquatic life. In order to minimize the threats imposed on the aquatic ecosystem and advancement of sustainable lifestyle for human, recent ecological studies are more concern about monitoring different bioindicative properties. In this study, two widely distributed freshwater bivalve mussel species Anodonta anatina and Unio tumidus was used to conduct comparative study on the transcriptome of these species in order to identify and quantify the expressed transcripts on both species and investigate their biomarker properties in mussels for monitoring heavy metal or toxic exposure. mRNA was isolated and converted to cDNA through reverse transcription PCR. Quality and quantity assessments of purity, fragment size and concentration was performed. Each cDNA sample was barcoded and amplified for cDNA library preparation and nanopore sequencing. Basic bioinformatics tools were used to identify the transcripts for transcriptomic analysis. The findings shows some common mitochondrial and ribosomal transcripts along with a wide range of conserved and abundant transcript variants in mussels with important biomarker properties. Some of the transcripts exhibits expression in multiple samples suggesting characteristic bioindicator properties. Also in this study, a pipeline for transcriptomic analysis was generated and critical steps in the procedure were identified and discussed.

Page generated in 0.1041 seconds