The sea louse Caligus elongatus (Caligidae). Genetic variation and host use by its two genotypes

Caligus elongatus (Caligidae: Siphonostomatoida) is a common ectoparasite of fish in the north Atlantic. Unlike the salmon louse (Lepeophtheirus salmonis) which is specific to salmonids, C. elongatus infects more than 80 fish species and is considered an unspecific generalist parasite. It is registered on most common fish species in Norway, including farmed fish like Atlantic salmon (Salmo salar), Atlantic cod (Gadus morhua), Atlantic halibut (Hippoglossus hippoglossus) and lumpfish (Cyclopterus lumpus). Sudden infections with high intensities of adult C. elongatus on these farmed fish have been observed, without a preceding infection with chalimus larvae. Therefore, it is likely that these adult lice originate from wild fish outside the farms. We raise the question what role small-sized fish acting as intermediate hosts could play into the infections on farmed fish. It was recently discovered that C. elongatus actually consists of two (mtDNA) genotypes, genotype 1 and 2, which may be sibling species. This discovery necessitates renewed research into the ecology of the two C. elongatus variants, since much past work could have concerned a mix of these. Some recent studies provide indications of different host use, temporal occurrence and geographical distribution of the genotypes. The aim of the present work was to examine the genetic variation, morphology and aspects of the ecology of the C. elongatus genotypes. A likely intermediate host, the two-spotted goby (Gobiusculus flavescens), was sampled throughout a year to assess the infection dynamics of C. elongatus at a locality in western-Norway. Lice from these gobies, and additional ones from various sympatric hosts and from other locations from the north-east Atlantic, were genotyped. A novel primer assay based on the cytrochrome oxidase 1 (CO1) gene was tested. The CO1 gene was sequenced from 94 lice, and compared to reference sequences in GenBank. The prevalence of C. elongatus on two-spotted gobies peaked in May (10%) and October (5%). Nearly all were attached stages, mostly chalimi. Adults developing on the gobies must leave them to find another host for reproduction. It is demonstrated that this phenomenon can be responsible for high densities of free adult C. elongatus in the water. Such lice may also infect farmed fish. All juvenile lice found on two-spotted gobies throughout the year was genotype 2. Adults from Atlantic cod were mostly genotype 2, while all adult C. elongatus from farmed Atlantic salmon were genotype 1. Chalimi from lumpfish were genotype 1. Novel genotyping assays for genotyping with PCR readily distinguished the genotypes. We found 21 nucleotide positions defining the two genotypes based on the mtCO1 sequences. Morphometric comparison of major body proportions of copepodites and adult females from the two genotypes revealed significant differences: Genotype 1 C. elongatus were generally larger than genotype 2 and the cephalothorax shape of genotype 1 copepodids were more oblong than genotype 2. The present findings corroborate previous knowledge on the genotypes and their hosts, demonstrate the infection dynamics of genotype 2 on an intermediate host, and suggest morphological characters that should be examined further for their ability to distinguish these C. elongatus variants. The findings support the belief that the two genotypes could represent two species.Masteroppgave i fiskehelseFISK399MAMN-FIS

Modelling breakdown of industrial thermal insulation during fire exposure

The aging of many of the installations in the oil and gas industry may increase the likelihood of loss of containment of flammable substances, which could lead to major accidents. Flame temperatures in a typical hydrocarbon fire may reach 1100–1200 °C, which are associated with heat flux levels between 250 and 350 kW/m2. To limit or delay the escalation of an initial fire, passive fire protection (PFP) can be an effective barrier. Additionally, both equipment and piping may require thermal insulation for heat or cold conservation. Previous studies have investigated whether thermal insulation alone may protect the equipment for a required time period, e.g., until adequate depressurization is achieved. The present study entails the development of a numerical model for predicting the heat transport through a multi-layer wall of a distillation column exposed to fire. The outer surface is covered by stainless-steel weather protective cladding, followed by PFP, thermal insulation, and finally an inner column of carbon steel of variable thicknesses. The model for the breakdown of thermal insulation is based on observed dimensional changes and independent measurements of the thermal conductivity of the insulation after heat treatment. The calculated temperature profiles of thermally insulated carbon steel during fire exposure are compared to fire test results for carbon steel with thicknesses of 16, 12, 6 and 3 mm. The model's predictions agree reasonably well with the experiments. The degradation of the thermal insulation at temperatures above 1100 °C limits its applicability as fire protection, especially for low carbon-steel thickness. However, the model predicts that adding a 10-mm layer of more heat-resistant insulation (PFP) inside the fire-exposed cladding may considerably extend the time to breakdown of the thermal insulation.publishedVersio

Tocqueville's Christian Citzen

Tocqueville's Christian Citizen Marinus Ossewaarde Introduction Alexis De Tocqueville is well known for his critique of democracy. A French statesman, he was left with the legacy of the French Revolution that had torn his fatherland and had changed the course of human history for good. Tocqueville, unlike many of his contemporaries, believed that the Revolution ought not to be seen as incidental or unexpected, despite the fact that it was without precedent in human history and so tarnished with human blood. The French Revolution is part of a trend that traces the path of democracy. Living in the revolutionary France of the nineteenth century, he hoped to find out what France may expect from its course of civilization, what it may expect from its democracy. Tocqueville was a social critic: he deplored what he saw happening around him in France. He believed that France was poorly governed. He was critical of the rise of the bourgeoisie and believed that everything had become vulgar, low, and mean. He rejected the rising materialism as "a dangerous disease of the human mind," which he found in positivism (Comte and St. Simon) and socialism (Proudhon and Blanc). He believed that scientific and economic determinisms were serious threats to liberty and human

Approximating Bin Packing within O(log OPT * log log OPT) bins

For bin packing, the input consists of n items with sizes s_1,...,s_n in [0,1] which have to be assigned to a minimum number of bins of size 1. The seminal Karmarkar-Karp algorithm from '82 produces a solution with at most OPT + O(log^2 OPT) bins. We provide the first improvement in now 3 decades and show that one can find a solution of cost OPT + O(log OPT * log log OPT) in polynomial time. This is achieved by rounding a fractional solution to the Gilmore-Gomory LP relaxation using the Entropy Method from discrepancy theory. The result is constructive via algorithms of Bansal and Lovett-Meka

The Learning Log, January 2022

The Learning Log is the electronic newsletter of the Lindenwood University Learning Academy

Analysis of a Costly Fiberglass-Polyester Air Filter Fire

In September 2020, a fire at a liquefied natural gas (LNG) plant in the Arctic areas of Norway received national attention. In an unengaged air intake, the heat exchanger designed to prevent ice damage during production mode, was supplied hot oil at 260 °C. In sunny weather, calm conditions, and 14 °C ambient temperature, overheating of the unengaged air intake filters (85% glass fiber and 15% polyester) was identified as a possible cause of ignition. Laboratory heating tests showed that the filter materials could, due to the rigid glass fibers carrying the polymers, glow like smoldering materials. Thus, self-heating as observed for cellulose-based materials was a possible ignition mechanism. Small-scale testing (10 cm × 10 cm and 8 cm stacked height) revealed that used filters with collected biomass, i.e., mainly pterygota, tended to self-heat at 20 °C lower temperatures than virgin filters. Used filter cassettes (60 cm by 60 cm and 50 cm bag depth) caused significant self-heating at 150 °C. At 160 °C, the self-heating took several hours before increased smoke production and sudden transition to flaming combustion. Since the engaged heat exchanger on a calm sunny day of ambient temperature 14 °C would result in temperatures in excess of 160 °C in an unengaged air intake, self-heating and transition to flaming combustion was identified as the most likely cause of the fire. Flames from the burning polymer filters resulted in heat exchanger collapse and subsequent hot oil release, significantly increasing the intensity and duration of the fire. Due to firewater damages, the plant was out of operation for more than 1.5 years. Better sharing of lessons learned may help prevent similar incidents in the future.publishedVersio

Reducing Wooden Structure and Wildland-Urban Interface Fire Disaster Risk through Dynamic Risk Assessment and Management

In recent years, severe and deadly wildland-urban interface (WUI) fires have resulted in an increased focus on this particular risk to humans and property, especially in Canada, USA, Australia, and countries in the Mediterranean area. Also, in areas not previously accustomed to wildfires, such as boreal areas in Sweden, Norway, and in the Arctic, WUI fires have recently resulted in increasing concern. January 2014, the most severe wooden town fire in Norway since 1923 raged through Lærdalsøyri. Ten days later, a wildfire raged through the scattered populated community of Flatanger and destroyed even more structures. These fires came as a surprise to the fire brigades and the public. We describe and analyze a proposed way forward for exploring if and how this increasing fire incidence can be linked to concomitant changes in climate, land-use, and habitat management; and then aim at developing new dynamic adaptive fire risk assessment and management tools. We use coastal Norway as an example and focus on temporal changes in fire risk in wooden structure settlements and in the Norwegian Calluna vulgaris L. dominated WUI. In this interface, the fire risk is now increasing due to a combination of land-use changes, resulting in large areas of early successional vegetation with an accumulation of biomass, and the interactive effects of climatic changes resulting in increased drought risk. We propose a novel bow-tie framework to explore fire risk and preventive measures at various timescales (years, months, weeks, hours) as a conceptual model for exploring risk contributing factors and possibilities for risk management. Ignition is the top event of the bow-tie which has the potential development towards a fire disaster as a worst case outcome. The bow-tie framework includes factors such as changes in the built environment and natural habitat fuel moisture content due to the weather conditions, WUI fuel accumulation, possibly improved ecosystem management, contribution by civic prescribed burner groups, relevant fire risk modeling, and risk communication to the fire brigades and the public. We propose an interdisciplinary research agenda for developing this framework and improving the current risk understanding, risk communication, and risk management. This research agenda will represent important contributions in paving the road for fire disaster prevention in Norway, and may provide a model for other systems and regions.publishedVersio