329 research outputs found
Women Readers and Female Genres in the 18th century: The Female Quixote and Northanger Abbey
Engelsk mastergradsoppgaveENG350MAHF-LÆFRMAHF-EN
Mass Spectrometry Based Metabolomic and Lipidomic Analyses of Algal Biomass.
Background: In a project at UiT - the Arctic University of Norway, the lipid profile of the
microalgal biomass from the specie Porosira glacialis is mapped using HRMS lipidomic
analyses to evaluate the potential for the biomass to be used as fish feed. At the same time, it is
desired to screen the same biomass for bioactivities using bioassays in combination with HRMS
metabolomic analyses. The two processes use two different extraction methods. To evaluate
the differences between the extraction methods, a comparison between one of each extract was
done in this thesis. Fractions from extracts are also tested for bioactivity and analysed on HRMS
to initiate the mapping of bioactivity.
Method: Microalgal biomass of P. glacialis was extracted using two different extraction
methods, yielding an aqueous, an organic and a lipid extract. The metabolic and lipidomic
profile of the organic and the lipid extract was compared using HRMS metabolomic and
lipidomic analyses. The aqueous and the organic extracts were fractionated using flash
chromatography, before being tested for various bioactivities and analysed using HRMS.
Observed activity was investigated and a potential bioactive compound was isolated and tested
for anti-cancer activity.
Results: There were no obvious differences in the metabolomic and lipidomic profiles between
the organic and the lipid extracts, but some trends could be observed. The lipidomic analyses
showed low lipid detection not consistent with previous research, which needs further
investigation. In fractions obtained from the microalgal biomass from P. glacialis, anticancer
activity against human melanoma A2058 cancer cells and growth inhibition against the bacteria
Streptococcus agalactiae were observed, as well as anti-inflammatory activity in an ELISA
immunoassay. An isolated potential bioactive compound showed no activity against human
melanoma A2058 cancer cells at five different test concentrations.
Conclusion: None of the extraction methods can be considered favourable over the other based
on the comparison in this thesis. Various bioactivities were observed for fractions derived from
the microalgal biomass of P. glacialis, but more investigation must be done to identify the
compounds responsible for the activity
The Bipartite Structure of the tRNA m\u3csup\u3e1\u3c/sup\u3eA58 Methyltransferase from \u3cem\u3eS. cerevisiae\u3c/em\u3e is Conserved in Humans
Among all types of RNA, tRNA is unique given that it possesses the largest assortment and abundance of modified nucleosides. The methylation at N1 of adenosine 58 is a conserved modification, occurring in bacterial, archaeal, and eukaryotic tRNAs. In the yeast Saccharomyces cerevisiae, the tRNA 1-methyladenosine 58 (m1A58) methyltransferase (Mtase) is a two-subunit enzyme encoded by the essential genes TRM6 (GCD10) and TRM61 (GCD14). While the significance of many tRNA modifications is poorly understood, methylation of A58 is known to be critical for maintaining the stability of initiator tRNAMet in yeast. Furthermore, all retroviruses utilize m1A58-containing tRNAs to prime reverse transcription, and it has been shown that the presence of m1A58 in human tRNA3 Lys is needed for accurate termination of plus-strand strong-stop DNA synthesis during HIV-1 replication. In this study we have identified the human homologs of the yeast m1A Mtase through amino acid sequence identity and complementation of trm6 and trm61 mutant phenotypes. When coexpressed in yeast, human Trm6p and Trm61p restored the formation of m1A in tRNA, modifying both yeast initiator tRNAMet and human tRNA3 Lys. Stable hTrm6p/hTrm61p complexes purified from yeast maintained tRNA m1A Mtase activity in vitro. The human m1A Mtase complex also exhibited substrate specificity—modifying wild-type yeast tRNAi Met but not an A58U mutant. Therefore, the human tRNA m1A Mtase shares both functional and structural homology with the yeast tRNA m1A Mtase, possessing similar enzymatic activity as well as a conserved binary composition
The cash-for-care benefit and daycare use : a quasi-experimental approach
This paper sets out to explore the effects of a cash incentive on parents’ choice of
daytime care for children in the age group 1-3 years. By studying the Norwegian
Cash-for-Care reform from 1998/1999 we are able to able to examine this through a
natural experiment. The results show a statistical significant decrease in use of
daycare for the total population, an effect that is stronger for families of low
socioeconomic status. This may work against stated long-term national goals. We are
not able to identify any changes in demand for the immigrant families in the sample
VR in RE and moral education: report from a conference symposium at the NCRE 2022
This paper reports from a symposium exploring the application of Virtual Reality (VR) in RE. The contributors presented empirical casestudies of interventions and instructional designs that had been tested in classroom settings ranging from primary to teacher education. The presentations illustrate the ways in which VR can be understood as a rapidly developing family of technologies that, as teaching and learning material, offers a new form of mobility and the shifting of grounds in the RE classroom: It can bring learners to places of worship across the globe or provide immersive experiences of being at the receiving end of bullying as a starting point for ethical reflection. VR and 360-images enable us to encounter religion and worldview, oneself and different ways of exploring our subject in ways that strengthen the relevance of RE. The larger picture that emerges from the symposium is not one of revolutionary change but definite enrichment of the RE toolkit with rich avenues for future research.VR in RE and moral education: report from a conference symposium at the NCRE 2022publishedVersionPaid Open Acces
An innovative asphalt patch repair pre–heating method using dynamic heating
In hot mix asphalt patch repair, inadequate temperature at the interfaces is one of the influencing factors for inferior compaction and poor interface bonding. To enhance repair performance, a precisely controlled infrared pre-heating method for patch repair has been investigated. Asphalt slabs with 45 mm, 75 mm and 100 mm deep pothole excavations were subjected to dynamic heating with infrared heater operating power from 6.6 kW to 7.7 kW. The heater was kept either stationary or moving slowly across the excavations at 130 mm and 230 mm offsets. The tests included evaluating temperature increase throughout the excavations and inside the slab, recording heat power of infrared heater and heating time to avoid burning the asphalt. Irrespective of excavation depth, heating power and offset, the temperature distribution was found non-uniform in the pothole excavations and into the asphalt slab. The temperatures were higher at the faces of the excavation than inside the slab. Dynamic heating for approximately 10 min yielded better heat distribution while minimising the possibility of asphalt overheating and long pre-heating time. It has been concluded that 45 mm and 100 mm deep pothole excavations can be pre-heated with 6.6 kW and stationary heater or 7.5 kW and moving heater at 230 mm and 130 mm offset respectively. 75 mm deep excavation can be pre-heated with 7.1 kW and stationary heater at 230 mm offset
Evaluation of the Algorithms and Parameterizations for Ground Thawing and Freezing Simulation in Permafrost Regions
Ground thawing and freezing depths (GTFDs) strongly influence the hydrology and energy balances of permafrost regions. Current methods to simulate GTFD differ in algorithm type, soil parameterization, representation of latent heat, and unfrozen water content. In this study, five algorithms (one semiempirical, two analytical, and two numerical), three soil thermal conductivity parameterizations, and three unfrozen water parameterizations were evaluated against detailed field measurements at four field sites in Canada’s discontinuous permafrost region. Key findings include: (1) de Vries’ parameterization is recommended to determine the thermal conductivity in permafrost soils; (2) the three unfrozen water parameterization methods exhibited little difference in terms of GTFD simulations, yet the segmented linear function is the simplest to be implemented; (3) the semiempirical algorithm reasonably simulates thawing at permafrost sites and freezing at seasonal frost sites with site-specific calibration. However, large interannual and intersite variations in calibration coefficients limit its applicability for dynamic analysis; (4) when driven by surface forcing, analytical algorithms performed marginally better than the semiempirical algorithm. The inclusion of bottom forcing improved analytical algorithm performance, yet their results were still poor compared with those achieved by numerical algorithms; (5) when supplied with the optimal inputs, soil parameterizations, and model configurations, the numerical algorithm with latent heat treated as an apparent heat capacity achieved the best GTFD simulations among all algorithms at all sites. Replacing the observed bottom temperature with a zero heat flux boundary condition did not significantly reduce simulation accuracy, while assuming a saturated profile caused large errors at several sites
Methane gas hydrate effect on sediment acoustic and strength properties
Author Posting. © The Author(s), 2006. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Petroleum Science and Engineering 56 (2007): 127-135, doi:10.1016/j.petrol.2006.02.003.To improve our understanding of the interaction of methane gas hydrate with host
sediment, we studied: (1) the effects of gas hydrate and ice on acoustic velocity in
different sediment types, (2) effect of different hydrate formation mechanisms on
measured acoustic properties (3) dependence of shear strength on pore space contents,
and (4) pore-pressure effects during undrained shear.
A wide range in acoustic p-wave velocities (Vp) were measured in coarse-grained
sediment for different pore space occupants. Vp ranged from less than 1 km/s for gascharged
sediment to 1.77 - 1.94 km/s for water-saturated sediment, 2.91 - 4.00 km/s for
sediment with varying degrees of hydrate saturation, and 3.88 - 4.33 km/s for frozen
sediment. Vp measured in fine-grained sediment containing gas hydrate was substantially
lower (1.97 km/s). Acoustic models based on measured Vp indicate that hydrate which
formed in high gas flux environments can cement coarse-grained sediment, whereas
hydrate formed from methane dissolved in the pore fluid may not.
The presence of gas hydrate and other solid pore-filling material, such as ice,
increased the sediment shear strength. The magnitude of that increase is related to the
amount of hydrate in the pore space and cementation characteristics between the hydrate
and sediment grains. We have found, that for consolidation stresses associated with the
upper several hundred meters of subbottom depth, pore pressures decreased during shear
in coarse-grained sediment containing gas hydrate, whereas pore pressure in fine-grained
sediment typically increased during shear. The presence of free gas in pore spaces
damped pore pressure response during shear and reduced the strengthening effect of gas
hydrate in sands.This
work was supported by the Coastal and Marine Geology, and Energy Programs of the
U.S. Geological Survey and funding was provided by the Gas Hydrate Program of the
U.S. Department of Energy
Growing Pollen Tubes Possess a Constitutive Alkaline Band in the Clear Zone and a Growth-dependent Acidic Tip
Using both the proton selective vibrating electrode to probe the extracellular currents and ratiometric wide-field fluorescence microscopy with the indicator 2′,7′-bis-(2-carboxyethyl)-5-(and-6)-carboxyfluorescein (BCECF)-dextran to image the intracellular pH, we have examined the distribution and activity of protons (H+) associated with pollen tube growth. The intracellular images reveal that lily pollen tubes possess a constitutive alkaline band at the base of the clear zone and an acidic domain at the extreme apex. The extracellular observations, in close agreement, show a proton influx at the extreme apex of the pollen tube and an efflux in the region that corresponds to the position of the alkaline band. The ability to detect the intracellular pH gradient is strongly dependent on the concentration of exogenous buffers in the cytoplasm. Thus, even the indicator dye, if introduced at levels estimated to be of 1.0 μM or greater, will dissipate the gradient, possibly through shuttle buffering. The apical acidic domain correlates closely with the process of growth, and thus may play a direct role, possibly in facilitating vesicle movement and exocytosis. The alkaline band correlates with the position of the reverse fountain streaming at the base of the clear zone, and may participate in the regulation of actin filament formation through the modulation of pH-sensitive actin binding proteins. These studies not only demonstrate that proton gradients exist, but that they may be intimately associated with polarized pollen tube growth
- …