Search results for "Matematikk"
showing 10 items of 707 documents
Visual fish assemblage inventory of outer Oslo fjord, with special emphasis on young-of-the-year Atlantic cod (Gadus morhua)
2021
Master's thesis in Coastal ecology (BIO501) The coastal zone along the outer Oslofjord is physically unique and home to many ecologically depleted and economically important species, including Atlantic cod (Gadus morhua). Coastal cod in Skagerrak is divided into two ecotypes that co-exist in outer Oslofjord. Remnant local populations are considered sensitive to climate disturbances and anthropogenic influences. Recruitment of cod in Skagerrak is monitored in the annual beach seine sampling. A strong year-class of cod recruited to nursery areas in outer Oslo fjord in 2017. Although recruitment of cod has been monitored extensively in Skagerrak, studies have only recently begun to examine the…
Long term effects of activated carbon on benthic communities
2021
Master's thesis in Coastal ecology (BIO501) Thin-layer capping with activated carbon (AC) has a potential as situ remediation method for sediments exposed to hydrophobic organic compounds (HOCs). This treatment was applied at two test fields; one in the Eidangerfjord (95 m) and the other in the Ormerfjord (30 m) in 2009. These two fjords are a part of the Grenland fjord system which have a long history of contaminated sediments. In this study we will address long-term effects of thin-layer capping with AC on the benthic community nine years later. Number of individuals, species and biomass was significantly reduced in both test fields compared to their corresponding reference fields. The di…
Methods for studying coastal bivalves in a changing world : A review and implications for management
2021
Master's thesis in Coastal ecology (BIO501) Anthropogenic activities such as pollution, CO2 emission, and overfishing, are among leading reasons for global environmental change and negative impacts on the marine environment including loss of biodiversity. Marine bivalves are an example of species that suffers from such consequences while they have high value in both aquaculture and marine ecosystems. With the existence of many threats including overharvesting, invasive species, parasites, and diseases, coastal bivalves such as flat oysters (Ostrea edulis) and blue mussels (Mytilus spp) are in many places endangered. The existing knowledge gaps in the historic and current distribution, howev…
Do cold-water corals spatially correlate with submarine canyons in the Bay of Biscay? : A GIS study analysing the spatial distribution of cold-water …
2020
Master's thesis in Coastal ecology (BIO501) The seascape of the Bay of Biscay is a mysterious place. It is located to the west of France and the north of Spainand is often defined as well-differentiated geomorphological unit. The continental margin of the BoB is incised with many submarine canyons and is also thought to be a hotspot for cold-water corals.Unfortunately, it is an area under high anthropogenic pressure where intense fishing activity, bottom trawling especially, is causing major disturbances to benthic habitats such as cold-water corals. Cold-water corals have been well studied along the European margin and have more frequently been recorded in the northeastAtlantic than any ot…
Tick-borne pathogens in Ixodes ricinus ticks collected from migratory birds in southern Norway
2020
Birds are important hosts for the first life stages of the Ixodes ricinus tick and they can transport their parasites over long distances. The aim of this study was to investigate the prevalence of Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum, Neoehrlichia mikurensis and Rickettsia helvetica in ticks collected from migratory birds in Norway. A total of 815 Ixodes ricinus ticks from 216 birds trapped at Lista Bird Observatory in southern Norway during spring and autumn migration in 2008 were analysed by real-time PCR. B. burgdorferi s. l. was the most prevalent pathogen, detected in 6.1% of the ticks. The prevalence of N. mikurensis, A. phagocytophilum and R. helvetica was 1.2%…
Autonomous Operation of Stationary Battery Energy Storage Systems—Optimal Storage Design and Economic Potential
2021
Global warming requires a changeover from fossil fuel based to renewable energy sources on the electrical supply side and electrification of the demand side. Due to the transient nature of renewables and fluctuating demand, buffer capacities are necessary to compensate for supply/demand imbalances. Battery energy storage systems are promising. However, the initial costs are high. Repurposing electric vehicle batteries can reduce initial costs. Further, storage design optimization could significantly improve costs. Therefore, a battery control algorithm was developed, and a simulation study was performed to identify the optimal storage design and its economic potential. The algorithm used is…
Home range and excursive post-breeding movements of Eurasian Eagle-owls revealed by GPS satellite transmitters
2021
Investigating space use of wild birds provides important knowledge of bird behavior and ecology, which is crucial in the management and conservation of threatened species. In the present study, we used GPS satellite telemetry to investigate space use and movements of seven adult Eurasian Eagle-Owls (Bubo bubo) in Norway during breeding and post-breeding seasons. Breeding adults had a mean home range size of 42.9 km2 (SD ± 35.1 km2; 95% kernel density estimation Had hoc), and five individuals performed long (>20 km) excursive movements away from their breeding territories during autumn. Such wide-ranging behavior has not previously been reported for adults of the nominate subspecies B. b. bu…
Energy compensation and adiposity in humans
2021
Publisher Copyright: © 2021 The Authors Understanding the impacts of activity on energy balance is crucial. Increasing levels of activity may bring diminishing returns in energy expenditure because of compensatory responses in non-activity energy expenditures.1–3 This suggestion has profound implications for both the evolution of metabolism and human health. It implies that a long-term increase in activity does not directly translate into an increase in total energy expenditure (TEE) because other components of TEE may decrease in response—energy compensation. We used the largest dataset compiled on adult TEE and basal energy expenditure (BEE) (n = 1,754) of people living normal lives to fi…
On Science Museums, Science Capital, and the Public Understanding of Mathematical Modelling
2020
Students’ opportunities to learn informally (e.g. by watching documentaries, visiting museums) explain socio-economic inequities in school performances. To explore informal learning about mathematical modelling, I studied two science museums, as these are environments typically visited by middle-class families. I framed the study by using the notions science capital and the public understanding of mathematical modelling (PUMM) and explored how these are mediated in science museums. The research method entailed observations of displays, artefacts, and visitors. One science museum completely detached mathematics from its use value, whereas the other offered histories of how people used mathem…
Chemical Vapour Deposition of Pure Titanium Using a Heated Wire Reactor and TiI4
2017
Master's thesis Renewable Energy ENE500 - University of Agder 2017 An experimental reactor system has been optimized throughout a series of experiments for making titanium tubes from an electrically heated titanium coil filament by a chemical vapour deposition method, based on the original van Arkel-de Boer -process. The titanium is thermally decomposed on the filament from vapourized titanium tetraiodide in a method not seen in similar experiments. The small-scale reactor is built for this purpose, and the associated systems and methods are developed to maintain the optimal conditions for a continuous metal deposition. A filament current control system is made of an Arduino micro-controlle…