Time filter

Source Type

Reykjavik, Iceland

The University of Iceland is a public research university in Reykjavík, Iceland, and the country's oldest and largest institution of higher education. Founded in 1911, it has grown steadily from a small civil servants' school to a modern comprehensive university, providing instruction for about 14,000 students in twenty-five faculties. Teaching and research is conducted within social science, humanities, medicine, natural science, engineering and teacher education. It has a campus concentrated around Suðurgata street in central Reykjavík, with additional facilities located in nearby areas as well as in the countryside. Wikipedia.

Cano Z.,University of Iceland
Monthly Notices of the Royal Astronomical Society | Year: 2013

The bolometric properties (nickel mass, ejecta mass and kinetic energies) of 61 Ibc supernovae (SNe), including 20 gamma-ray burst and X-ray flash (GRB/XRF), 19 Ib, 13 Ic and nine Ic-BL (broad-lined) SNe are presented. All of the available BVRI photometry in the literature have been collected and used in a new method that utilizes a template supernova (SN 1998bw) and an analytical model to accurately estimate the bolometric properties of each SN. A statistical analysis of the bolometric properties is then performed, where it is found that GRB/XRF SNe are the most energetic, and eject more mass (including nickel content) than Ib, Ic and Ic-BL SNe. The results are then compared to the existing progenitor models of Ibc SNe, where it is concluded that it is highly likely that at least two progenitor channels exist for producing a Ibc SN: most Ibc SNe arise via binary interactions, where the mass of the stellar progenitor is less than what is attributed to a Wolf-Rayet star. Conversely, the progenitors of Ic-BL and GRB/XRF are more massive than those of Ib and Ic SNe, and a key difference between GRB/XRF SNe and Ic-BL SNe is progenitor metallicity, where it is observed that the latter arise from more metal-rich progenitors. As mass loss in massive stars is influenced by metal content, the progenitors of Ic-BL SNe lose more mass, and thereforemore angular momentum, before exploding. It is expected that the explosion mechanism in Ic-BL and GRB/XRF SNe is 'engine-driven' (i.e. an accreting black hole, or amillisecond magnetar), but the increased mass loss of Ic-BL SNe means the central engine is less powerful than in GRB/XRF SNe. Finally, it is found that the SNe that accompany GRBs and XRFs are statistically indistinguishable, and some mechanism other than metallicity is needed to explain the differences in the high-energy components in these events. ©2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Source

Arnason R.,University of Iceland
Review of Environmental Economics and Policy | Year: 2012

Individual transferable quotas (ITQs) are one of the property rights instruments that have been employed to improve economic efficiency in fisheries. ITQs are not high-quality property rights in the basic fundamental marine resources on which fisheries are based. As a result ITQs cannot be expected to generate full efficiency in the use of these resources. This article examines to what extent ITQs are capable of generating economic efficiency in fisheries. It is shown that ITQs can greatly improve efficiency in fishing. Moreover, by including recreational fishers in the system, ITQs can strike an efficient balance between commercial and recreational fishing. On the negative side, it is shown that on their own, ITQs are not capable of generating full efficiency in fisheries. In particular, ITQs are not sufficient for setting the socially optimal total allowable catch, ensuring the optimal use of the ecosystem, or harmonizing fishing with conflicting uses of marine resources such as marine tourism, mining, and conservation. Potentially counteracting these limitations, ITQ holders as a group have an incentive to manage overall ecosystem use for the long-term benefit of their fishery and negotiate the adjustment of their fishing activity toward the interests of conflicting uses of the marine resources.(JEL: Q2, Q22, Q26, Q3). © The Author 2012. Published by Oxford University Press on behalf of the Association of Environmental and Resource Economists. All rights reserved. Source

Magnadottir B.,University of Iceland
Marine Biotechnology | Year: 2010

All metazoans possess innate immune defence system whereas parameters of the adaptive immune system make their first appearance in the gnathostomata, the jawed vertebrates. Fish are therefore the first animal phyla to possess both an innate and adaptive immune system making them very interesting as regards developmental studies of the immune system. The massive increase in aquaculture in recent decades has also put greater emphasis on studies of the fish immune system and defence against diseases commonly associated with intensive fish rearing. Some of the main components of the innate and adaptive immune system of fish are described. The innate parameters are at the forefront of immune defence in fish and are a crucial factor in disease resistance. The adaptive response of fish is commonly delayed but is essential for lasting immunity and a key factor in successful vaccination. Some of the inherent and external factors that can manipulate the immune system of fish are discussed, the main fish diseases are listed and the pathogenicity and host defence discussed. The main prophylactic measures are covered, including vaccination, probiotics and immunostimulation. A key element in the immunological control of fish diseases is the great variation in disease susceptibility and immune defence of different fish species, a reflection of the extended time the present day teleosts have been separated in evolution. Future research will probably make use of molecular and proteomic tools both to study important elements in immune defence and prophylactic measures and to assist with breeding programmes for disease resistance. © Springer Science+Business Media, LLC 2010. Source

Gill J.A.,University of Iceland
Proceedings. Biological sciences / The Royal Society | Year: 2014

Recent advances in spring arrival dates have been reported in many migratory species but the mechanism driving these advances is unknown. As population declines are most widely reported in species that are not advancing migration, there is an urgent need to identify the mechanisms facilitating and constraining these advances. Individual plasticity in timing of migration in response to changing climatic conditions is commonly proposed to drive these advances but plasticity in individual migratory timings is rarely observed. For a shorebird population that has significantly advanced migration in recent decades, we show that individual arrival dates are highly consistent between years, but that the arrival dates of new recruits to the population are significantly earlier now than in previous years. Several mechanisms could drive advances in recruit arrival, none of which require individual plasticity or rapid evolution of migration timings. In particular, advances in nest-laying dates could result in advanced recruit arrival, if benefits of early hatching facilitate early subsequent spring migration. This mechanism could also explain why arrival dates of short-distance migrants, which generally return to breeding sites earlier and have greater scope for advance laying, are advancing more rapidly than long-distance migrants. Source

Koziel S.,University of Iceland
IEEE Transactions on Microwave Theory and Techniques | Year: 2010

A shape-preserving response prediction methodology for microwave design optimization is introduced. The presented technique allows us to estimate the response of the microwave structure being optimized (fine model) using a computationally cheap representation of the structure (coarse model). The change of the coarse model response is described by the translation vectors corresponding to certain (finite) number of characteristic points of the response. These translation vectors are subsequently used to predict the response change of the fine model. The presented method has very good generalization capability and it is not based on any extractable parameters, which makes it easy to implement. Applications for microwave design optimization are discussed. The robustness of the proposed approach is demonstrated by extensive comparison with space mapping, which is one of the most efficient optimization approaches in microwave engineering so far. © 2006 IEEE. Source

Discover hidden collaborations