Phase field theory modeling of CH4/CO2 gas hydrates in gravity fields

Natural gas hydrates in reservoirs are thermodynamically unstable due to the interactions with surrounding fluids (aqueous, gas) and mineral surfaces. Depending on the local flow hydrate will dissociate as well as reform. If the dissociation rate is faster than the capacity of the surrounding fluids to dissolve the released gas, the gas will form bubbles. Depending on the rate of released gas and possible fracture patterns this may lead to venting of gas. The proper implementation of hydrodynamics will provide a deeper insight of the hydrate kinetics involved during dissociation and formation processes which involve hydrate former phase as smaller or larger bubbles or even continuous gas phase. In this work the phase field theory coupled with hydrodynamics model is implemented with variable density using the relative composition, phase field parameter and flow, which is an extension of our previous work which considers a constant density.publishedVersio

Modernisation of the Norwegian Tide Gauge Network

The modernization of the Norwegian Tide Gauge Network using technologies of the 1980s is presented. Technical and organizational challenges are described in detail together with cost-estimates and possible future developments

Genetic analysis redraws the management boundaries for the European sprat

Sustainable fisheries management requires detailed knowledge of population genetic structure. The European sprat is an important commercial fish distributed from Morocco to the Arctic circle, Baltic, Mediterranean, and Black seas. Prior to 2018, annual catch advice on sprat from the International Council for the Exploration of the Sea (ICES) was based on five putative stocks: (a) North Sea, (b) Kattegat–Skagerrak and Norwegian fjords, (c) Baltic Sea, (d) West of Scotland—southern Celtic Seas, and (e) English Channel. However, there were concerns that the sprat advice on stock size estimates management plan inadequately reflected the underlying biological units. Here, we used ddRAD sequencing to develop 91 SNPs that were thereafter used to genotype approximately 2,500 fish from 40 locations. Three highly distinct and relatively homogenous genetic groups were identified: (a) Norwegian fjords; (b) Northeast Atlantic including the North Sea, Kattegat–Skagerrak, Celtic Sea, and Bay of Biscay; and (c) Baltic Sea. Evidence of genetic admixture and possibly physical mixing was detected in samples collected from the transition zone between the North and Baltic seas, but not between any of the other groups. These results have already been implemented by ICES with the decision to merge the North Sea and the Kattegat–Skagerrak sprat to be assessed as a single unit, thus demonstrating that genetic data can be rapidly absorbed to align harvest regimes and biological units

Phenomenological Continuum Theory of Asphaltene-Stabilized Oil/Water Emulsions

This document is the Accepted Manuscript version of a Published Work that appeared in final form in Energy & Fuels, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see https://doi.org/10.1021/acs.energyfuels.6b02430.In this paper we use a phenomenological continuum theory of the Ginzburg-Landau type to address emulsion formation in water/light hydrocarbon/asphaltene systems. Based on the results of recent molecular dynamics simulations, we first calibrate the model parameters and show, that the theory produces a reasonable equation of state. Next, the coalescence of oil droplets is studied by a convection-diffusion dynamics as a function of both the surface coverage and the viscosity contrast between the as- phaltene and the bulk liquids. We show, that, besides the traditional thermodynamic interpretation of emulsion formation, the timescale of drop coalescence can be con- trolled independently from the interfacial tension drop, which offers an alternative, solely kinetic driven mechanism of emulsion formation

Does increasing packing density using larger caliber coils improve angiographic results of embolization of intracranial aneurysms at 1 year: A randomized trial

© 2020 American Society of Neuroradiology. All rights reserved. BACKGROUND AND PURPOSE: The impact of increased aneurysm packing density on angiographic outcomes has not been studied in a randomized trial. We sought to determine the potential for larger caliber coils to achieve higher packing densities and to improve the angiographic results of embolization of intracranial aneurysms at 1 year. MATERIALS AND METHODS: Does Embolization with Larger Coils Lead to Better Treatment of Aneurysms (DELTA) was an investigator-initiated multicenter prospective, parallel, randomized, controlled clinical trial. Patients had 4- to 12-mm unruptured aneurysms. Treatment allocation to either 15- (experimental) or 10-caliber coils (control group) was randomized 1:1 using a Web-based platform. The primary efficacy outcome was a major recurrence or a residual aneurysm at follow-up angiography at 12 6 2 months adjudicated by an independent core lab blinded to the treatment allocation. Secondary outcomes included indices of treatment success and standard safety outcomes. Recruitment of 564 patients was judged necessary to show a decrease in poor outcomes from 33% to 20% with 15-caliber coils. RESULTS: Funding was interrupted and the trial was stopped after 210 patients were recruited between November 2013 and June 2017. On an intent-to-treat analysis, the primary outcome was reached in 37 patients allocated to 15-caliber coils and 36 patients allocated to 10-caliber coils (OR = 0.931; 95% CI, 0.528–1.644; P = .885). Safety and other clinical outcomes were similar. The 15-caliber coil group had a higher mean packing density (37.0% versus 26.9%, P = .0001). Packing density had no effect on the primary outcome when adjusted for initial angiographic results (OR = 1.001; 95% CI, 0.981–1.022; P = .879). CONCLUSIONS: Coiling of aneurysms randomized to 15-caliber coils achieved higher packing densities compared with 10-caliber coils, but this had no impact on the angiographic outcomes at 1 year, which were primarily driven by aneurysm size and initial angiographic results

Methods for specifying the target difference in a randomised controlled trial : the Difference ELicitation in TriAls (DELTA) systematic review

Peer reviewedPublisher PD

Reading religion in Norwegian textbooks: are individual religions ideas or people?

Different religions are treated in different ways in Norwegian sixth form textbooks. We carried out an exhaustive content analysis of the chapters devoted to individual religions in textbooks for the Religion and Ethics course currently available in Norway, using rigorous indicators to code each word, image and question according to whether they were treated the religion as a set of ideas or a group of people. After adjusting for trends in the different kinds of data (word, image, question), we found that Buddhism and Christianity receive significantly more attention for their ideas than Hinduism, Islam and Judaism, which are treated more as people. This difference cannot be explained by the national syllabus or the particularities of the individual religions. The asymmetry also has implications for the pupils’ academic, moral and pedagogical agency for which teachers play a critical role in compensating.acceptedVersio