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Trondheim, Norway

Norwegian University of Science and Technology is a public research university located in the city of Trondheim, Norway. NTNU is the second largest of the eight universities in Norway, and, as its name suggests, has the main national responsibility for higher education in engineering and technology. In addition to engineering and the natural and physical science, the university offers advanced degrees in other academic disciplines ranging from the social science, the arts, medicine, architecture and fine art.The current rector is professor dr.med. Gunnar Bovim. Wikipedia.

Overli J.A.,Norwegian University of Science and Technology | Jensen T.M.,Sintef
Engineering Structures | Year: 2014

This study focuses on the ductility of lightweight aggregate concrete (LWAC) in compression. For practical purposes, the well-known brittleness of LWAC compared to normal density concrete has limited the use of the material. Demands for energy dissipation and/or a controlled behaviour after failure may exclude LWAC as the preferred material, while an increase of the ductility in the compression zone in bending is made possible by employing closed links and/or fibre reinforcement. An experimental programme was set up, which consists of eight over-reinforced concrete beams subjected to four-point bending in order to study the ductility. The LWAC had a mass density of approximately 1800kg/m3, with a compressive strength of approximately 35MPa. Four different configurations of the beams were investigated, only with LWAC in the compression zone, closed links with a spacing of 100mm, 1% of steel fibre reinforcement and a combination of closed links and steel fibres. The pre-peak behaviour was approximately the same for all configurations, and as expected, the beams with only LWAC had a very brittle response after peak load. The other beams had different post-peak responses, but all were able to carry the load with quite large deflections after maximum loading. Moreover, the combination with both fibres and links demonstrated highly ductile behaviour. © 2014 Elsevier Ltd. Source

Line M.B.,Norwegian University of Science and Technology
Proceedings - 7th International Conference on IT Security Incident Management and IT Forensics, IMF 2013 | Year: 2013

The power industry faces the implementation of smart grids, which will introduce new information security threats to the power automation systems. The ability to appropriately prepare for, and respond to, information security incidents, is of utmost importance, as it is impossible to prevent all possible incidents from occurring. Current trends even show that the power industry is an attractive target for hackers. A main challenge for the power industry to overcome is the differences regarding culture and traditions, knowledge and communication, between ICT staff and power automation staff. This paper presents the background, research method and preliminary results from a case study identifying current practice on information security incident management in the power industry. © 2013 IEEE. Source

Vladimer G.I.,UMass Medical School | Marty-Roix R.,UMass Medical School | Ghosh S.,UMass Medical School | Weng D.,UMass Medical School | And 2 more authors.
Current Opinion in Microbiology | Year: 2013

The inflammasome has emerged as an important molecular protein complex which initiates proteolytic processing of pro-IL-1β and pro-IL-18 into mature inflammatory cytokines. In addition, inflammasomes initiate pyroptotic cell death that may be independent of those cytokines. Inflammasomes are central to elicit innate immune responses against many pathogens, and are key components in the induction of host defenses following bacterial infection. Here, we review recent discoveries related to NLRP1, NLRP3, NLRC4, NLRP6, NLRP7, NLRP12 and AIM2-mediated recognition of bacteria. Mechanisms for inflammasome activation and regulation are now suggested to involve kinases such as PKR and PKCδ, ligand binding proteins such as the NAIPs, and caspase-11 and caspase-8 in addition to caspase-1. Future research will determine how specific inflammasome components pair up in optimal responses to specific bacteria. © 2012 Elsevier Ltd. Source

Skonhoft A.,Norwegian University of Science and Technology | Vestergaard N.,University of Southern Denmark | Quaas M.,University of Kiel
Environmental and Resource Economics | Year: 2012

An age structured model of a fishery is studied where two fishing fleets, or fishing agents, are targeting two different mature age classes of the fish stock. The agents are using different fishing gear with different fishing selectivity. The model includes young and old mature fish that can be harvested, in addition to an age class of immature fish. The paper describes the optimal harvesting policy under different assumptions on the objectives of the social planner and on fishing selectivity. First, biomass yield is maximized under perfect fishing selectivity, second, equilibrium profit (rent) is maximized under perfect fishing selectivity, and third, equilibrium profit is maximized under imperfect fishing selectivity. The paper provides results that differ significantly from the standard lumped parameter (also surplus production, or biomass) model. © 2011 Springer Science+Business Media B.V. Source

Adaramola M.S.,Norwegian University of Science and Technology | Oyewola O.M.,University of Ibadan
Energy Policy | Year: 2011

The aim of this paper is to review wind speed distribution and wind energy availability in Nigeria and discuss the potential of using this resource for generation of wind power in the country. The power output from a wind turbine is strongly dependent on the wind speed and accurate information about the wind data in a targeted location is essential. The annual mean wind speeds in Nigeria range from about 2 to 9.5m/s and the annual power density range between 3.40 and 520kW/m2 based on recent reported data. The trend shows that wind speeds are low in the south and gradually increases to relatively high speeds in the north. The areas that are suitable for exploitation of wind energy for electricity generation as well as for water pumping were identified. Also some of the challenges facing the development of wind energy and suggested solutions were presented. © 2011 Elsevier Ltd. Source

Razi Naqvi K.,Norwegian University of Science and Technology
Biomedical Optics Express | Year: 2014

Multiwavelength UV-visible spectroscopy, Kramers-Kronig analysis, and several other experimental and theoretical tools have been applied over the last several decades to fathom absorption and scattering of light by suspensions of micron-sized pigmented particles, including red blood cells, but a satisfactory quantitative analysis of the difference between the absorption spectra of suspension of intact and lysed red blood cells is still lacking. It is stressed that such a comparison is meaningful only if the pertinent spectra are free from, or have been corrected for, scattering losses, and it is shown that Duysens' theory can, whereas that of Vekshin cannot, account satisfactorily for the observed hypochromism of suspensions of red blood cells. © 2014 Optical Society of America. Source

Cerasti E.,International School for Advanced Studies | Treves A.,International School for Advanced Studies | Treves A.,Norwegian University of Science and Technology
PLoS Computational Biology | Year: 2010

In the mammalian hippocampus, the dentate gyrus (DG) is characterized by sparse and powerful unidirectional projections to CA3 pyramidal cells, the so-called mossy fibers. Mossy fiber synapses appear to duplicate, in terms of the information they convey, what CA3 cells already receive from entorhinal cortex layer II cells, which project both to the dentate gyrus and to CA3. Computational models of episodic memory have hypothesized that the function of the mossy fibers is to enforce a new, well separated pattern of activity onto CA3 cells, to represent a new memory, prevailing over the interference produced by the traces of older memories already stored on CA3 recurrent collateral connections. Can this hypothesis apply also to spatial representations, as described by recent neurophysiological recordings in rats? To address this issue quantitatively, we estimate the amount of information DG can impart on a new CA3 pattern of spatial activity, using both mathematical analysis and computer simulations of a simplified model. We confirm that, also in the spatial case, the observed sparse connectivity and level of activity are most appropriate for driving memory storage - and not to initiate retrieval. Surprisingly, the model also indicates that even when DG codes just for space, much of the information it passes on to CA3 acquires a non-spatial and episodic character, akin to that of a random number generator. It is suggested that further hippocampal processing is required to make full spatial use of DG inputs. © 2010 Cerasti, Treves. Source

Mai X.-M.,Norwegian University of Science and Technology
American Journal of Epidemiology | Year: 2012

Experimental studies suggest that vitamin D modulates the activity of adipocytes. The authors examined baseline serum 25-hydroxyvitamin D (25(OH)D) level in relation to prevalent and cumulative incident obesity in Norway. A cohort of 25,616 adults aged 19-55 years participated in both the second and third surveys of the Nord-Trøndelag Health Study (HUNT 2 (1995-1997) and HUNT 3 (2006-2008)). Serum 25(OH)D levels measured at baseline and anthropometric measurements taken at both baseline and follow-up were available for a random sample of 2,460 subjects. Overall, 40% of the 2,460 subjects had a serum 25(OH)D level less than 50.0 nmol/L, and 37% had a level of 50.0-74.9 nmol/L. The prevalence and cumulative incidence of obesity, defined as body mass index (weight (kg)/height (m) 2) ≥30, were 12% and 15%, respectively. Lower serum 25(OH)D level was associated with a higher prevalence of obesity. In the 2,165 subjects with baseline BMI less than 30, a serum 25(OH)D level less than 50.0 nmol/L was associated with a significantly increased odds ratio for incident obesity during follow-up (adjusted odds ratio = 1.73, 95% confidence interval: 1.24, 2.41). When prevalent and incident obesity were classified according to waist circumference (≥88 cm for women, ≥102 cm for men), similar results were obtained. In addition to prevalent obesity, a serum 25(OH)D level less than 50.0 nmol/L was significantly associated with new-onset obesity in adults. American Journal of Epidemiology © The Author 2012. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. Source

Hamann T.,Norwegian University of Science and Technology
Phytochemistry | Year: 2015

Some of the most important functions of plant cell walls are protection against biotic/abiotic stress and structural support during growth and development. A prerequisite for plant cell walls to perform these functions is the ability to perceive different types of stimuli in both qualitative and quantitative manners and initiate appropriate responses. The responses in turn involve adaptive changes in cellular and cell wall metabolism leading to modifications in the structures originally required for perception. While our knowledge about the underlying plant mechanisms is limited, results from Saccharomyces cerevisiae suggest the cell wall integrity maintenance mechanism represents an excellent example to illustrate how the molecular mechanisms responsible for stimulus perception, signal transduction and integration can function. Here I will review the available knowledge about the yeast cell wall integrity maintenance system for illustration purposes, summarize the limited knowledge available about the corresponding plant mechanism and discuss the relevance of the plant cell wall integrity maintenance mechanism in biotic stress responses. © 2014 Elsevier Ltd. All rights reserved. Source

Vinnem J.E.,Norwegian University of Science and Technology
Journal of Risk Research | Year: 2014

Prevention of hydrocarbon (HC) leaks is important; they are the most critical precursor events that may lead to major accidents, such as the Piper Alpha catastrophe in 1988. The number of HC leaks on offshore production installations on the Norwegian Continental Shelf peaked just after year 2000, with more than 40 leaks per year with initial rate above 0.1 kg/s. The Norwegian Oil and Gas Association carried out a reduction project from 2003 until 2007, which resulted in 10 HC leaks above 0.1 kg/s in 2007. The number of leaks increased in the years after 2007 and was on average 15 in the period 2008-2010, without any significant increase in the number of installations. A new initiative was launched early in 2011 in order to reduce the number of HC leaks further. A study performed by the project concludes that more than 50% of the leaks are associated with failure of operational barriers during manual intervention into the process systems. Human and organisational factors are dominating with respect to circumstances and root causes. The study has further demonstrated the high importance of verification as an operational barrier and has shown that many of the failures do not have multiple operational barriers in the form of several verifications and a leak test at the end. This finding is crucial in order to understand the criticality of performing the planned verifications, perform them in an independent manner according to the procedures and make sure that the focus is on detecting failures during the verification. This paper presents the analysis of HC leaks, with emphasis on operational barriers and importance of verification. © 2014 © 2014 Taylor & Francis. Source

Tufto J.,Norwegian University of Science and Technology
Evolution | Year: 2010

Domesticated species frequently spread their genes into populations of wild relatives through interbreeding. The domestication process often involves artificial selection for economically desirable traits. This can lead to an indirect response in unknown correlated traits and a reduction in fitness of domesticated individuals in the wild. Previous models for the effect of gene flow from domesticated species to wild relatives have assumed that evolution occurs in one dimension. Here, I develop a quantitative genetic model for the balance between migration and multivariate stabilizing selection. Different forms of correlational selection consistent with a given observed ratio between average fitness of domesticated and wild individuals offsets the phenotypic means at migration-selection balance away from predictions based on simpler one-dimensional models. For almost all parameter values, correlational selection leads to a reduction in the migration load. For ridge selection, this reduction arises because the distance the immigrants deviates from the local optimum in effect is reduced. For realistic parameter values, however, the effect of correlational selection on the load is small, suggesting that simpler one-dimensional models may still be adequate in terms of predicting mean population fitness and viability. © 2009 The Society for the Study of Evolution. Source

Venkatesh G.,Norwegian University of Science and Technology | Elmi R.A.,Oslo Water and Wastewater Authority
Energy | Year: 2013

This paper outlines a methodology for a systematic economic-environmental analysis of realistic and realisable options for recovering and utilising energy from biogas produced in sewage sludge digesters in WWTPs (wastewater treatment plants). Heat, electricity and transport fuel can be produced from biogas, consumed in-plant or even sold to external end-users. The paper initially considers global warming as the environmental impact of concern, but later also stresses on the necessity of avoiding problem shifting by factoring in other environmental impact categories as well. The methodology is subsequently applied to the Bekkelaget WWTP in Oslo (Norway). Five different options for handling biogas are considered, in addition to the status quo - the business-as-usual in year-2012, and a baseline case, where it is assumed that all biogas generated is flared completely and not utilised for energy recovery of any kind. Seven different cost scenarios - for electricity, natural gas, wood pellets, bio-methane and diesel - are constructed. This gives a total of 49 combinations, for each of which the net costs and net environmental impacts (global warming, eutrophication and acidification) are determined for the 10-year period 2012-2021. The changes (in percentages) with respect to the corresponding values for the baseline case, are recorded; suitable weighting factors are considered after interaction with experts and personnel associated with the plant, and the options are evaluated using this double-bottom-line approach (economic and environmental). © 2013 Elsevier Ltd. Source

Zhao Q.,Norwegian University of Science and Technology
Scripta Materialia | Year: 2014

We consider the elastic effect of clusters and propose a size misfit strengthening model. Our approach is similar to solute strengthening, where the size misfit of clusters is assumed to be the sum of elementary atomic misfits. The proposed model is compared to the coherency strengthening model, and the results indicate that our model is applicable to clusters ∼<1 nm in diameter. The prediction of the model is reasonably consistent with the reported experiments of aluminium alloys. © 2014 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Source

Cherubini F.,Norwegian University of Science and Technology
Energy Conversion and Management | Year: 2010

A great fraction of worldwide energy carriers and material products come from fossil fuel refinery. Because of the on-going price increase of fossil resources, their uncertain availability, and their environmental concerns, the feasibility of oil exploitation is predicted to decrease in the near future. Therefore, alternative solutions able to mitigate climate change and reduce the consumption of fossil fuels should be promoted. The replacement of oil with biomass as raw material for fuel and chemical production is an interesting option and is the driving force for the development of biorefinery complexes. In biorefinery, almost all the types of biomass feedstocks can be converted to different classes of biofuels and biochemicals through jointly applied conversion technologies. This paper provides a description of the emerging biorefinery concept, in comparison with the current oil refinery. The focus is on the state of the art in biofuel and biochemical production, as well as discussion of the most important biomass feedstocks, conversion technologies and final products. Through the integration of green chemistry into biorefineries, and the use of low environmental impact technologies, future sustainable production chains of biofuels and high value chemicals from biomass can be established. The aim of this bio-industry is to be competitive in the market and lead to the progressive replacement of oil refinery products. © 2010 Elsevier Ltd. All rights reserved. Source

Cherubini F.,Norwegian University of Science and Technology
Renewable Energy | Year: 2010

This paper deals with a methodology for calculating the greenhouse gas (GHG) balances of bioenergy systems producing electricity, heat and transportation biofuels from biomass residues or crops. Proceeding from the standard Life-Cycle Assessment (LCA) as defined by ISO 14040 norms, this work provides an overview of the application of the LCA methodology to bioenergy systems in order to estimate GHG balances. In this paper, key steps in the bioenergy chain are identified and the bioenergy systems are compared with fossil reference systems producing the same amount of final products/services. The GHG emission balances of the two systems can thus be compared. Afterwards, the most important methodological assumptions (e.g. functional unit, allocation, reference system, system boundaries) and key aspects affecting the final outcomes are discussed. These key aspects are: changes in organic carbon pools, land-use change effects (both direct and indirect), N 2O and CH 4 emissions from agricultural soils and effects of crop residue removal for bioenergy use. This paper finally provides some guidelines concerning the compilation of GHG balances of bioenergy systems, with recommendations and indications on how to show final results, address the key methodological issues and give homogenous findings (in order to enhance the comparison across case studies). © 2009 Elsevier Ltd. All rights reserved. Source

Klockner C.A.,Norwegian University of Science and Technology | Friedrichsmeier T.,Ruhr University Bochum
Transportation Research Part F: Traffic Psychology and Behaviour | Year: 2011

The presented study analyses travel mode choice in a student sample on four frequent trips: To the university, to work, to the favourite leisure activity, and to the favourite shop. The decision to use the car in contrast to alternative travel modes is modelled for each individual trip using a two-level structural equation model with trip specific attributes on Level 1 and person specific attributes on Level 2. Data was gathered in an online travel survey on a student sample of the Ruhr-University in Bochum. Three thousand five hundred and sixty students reported their mode choice for 26,865 individual trips. On the person level a comprehensive action determination model was applied to explain variation in person specific car preference, whereas on the situation level car availability, trip duration, day of travel, disruption in public transportation, weather, daylight, and purpose of the trip were included as predictors. The proposed two-level model is supported by the data, Level 1 predictors explain 62% of Level 1 variation, the Level 2 model explains 48% of Level 2 variance. The intraclass-correlation of car preference is .535. In a final step, interactions between person and trip specific variables were explored. © 2011 Elsevier Ltd. All rights reserved. Source

Holgersen K.H.,Norwegian University of Science and Technology
Journal of traumatic stress | Year: 2010

Findings on posttraumatic growth (PTG) and distress have not been consistent. This study examines the relationship in a very long-term perspective. The Posttraumatic Growth Inventory was completed by 46 survivors from a single disaster 27 years posttrauma. Posttraumatic stress was measured by the Impact of Event Scale (IES) immediately after the event, and after 1, 5, and 27 years. In the final follow-up, general mental health was also assessed. Strong positive associations were found between PTG and concurrent posttraumatic stress. Although weaker associations were found for the past, concurrent problems in general mental health clearly coexisted with PTG decades after a disaster, yet mediated by IES. Source

Callanan M.,Norwegian University of Science and Technology
Arctic | Year: 2012

Over nearly a century, a large assemblage of archaeological artifacts has been collected from some high-lying snow patches in a number of mountain areas in central Norway. The regional collection now comprises 234 individual artifacts that include both organic and inorganic elements. Many of these are arrowheads, shafts, and other equipment from past hunting expeditions on alpine snow patches. This article outlines three different phases of artifact recovery in the region: Phase I (1914-43) began with the initial snow patch discovery and included large numbers of finds in the 1930s and early 1940s; Phase II (1944-2000) had relatively few discoveries; and Phase III (2001-11) included discovery of 17 new sites and a record number of 145 artifacts. Local reindeer hunters and hikers have recovered many of the artifacts. There are close links between reindeer hunting and snow patch surveying in the region. The majority of snow patch finds were recovered during the period from mid-August through mid-September. The collection can best be viewed as a cohesive long-term record of melting snow patches. © The Arctic Institute of North America. Source

Sonnewald U.,Norwegian University of Science and Technology
Journal of Neurochemistry | Year: 2014

The central process in energy production is the oxidation of acetyl-CoA to CO2 by the tricarboxylic acid (TCA, Krebs, citric acid) cycle. However, this cycle functions also as a biosynthetic pathway from which intermediates leave to be converted primarily to glutamate, GABA, glutamine and aspartate and to a smaller extent to glucose derivatives and fatty acids in the brain. When TCA cycle ketoacids are removed, they must be replaced to permit the continued function of this essential pathway, by a process termed anaplerosis. Since the TCA cycle cannot act as a carbon sink, anaplerosis must be coupled with cataplerosis; the exit of intermediates from the TCA cycle. The role of anaplerotic reactions for cellular metabolism in the brain has been studied extensively. However, the coupling of this process with cataplerosis and the roles that both pathways play in the regulation of amino acid, glucose, and fatty acid homeostasis have not been emphasized. The concept of a linkage between anaplerosis and cataplerosis should be underscored, because the balance between these two processes is essential. The hypothesis that cataplerosis in the brain is achieved by exporting the lactate generated from the TCA cycle intermediates into the blood and perivascular area is presented. This shifts the generally accepted paradigm of lactate generation as simply derived from glycolysis to that of oxidation and might present an alternative explanation for aerobic glycolysis. © 2014 International Society for Neurochemistry. Source

Sletvold N.,Norwegian University of Science and Technology | Agren J.,Uppsala University
International Journal of Plant Sciences | Year: 2010

Floral diversification and specialization are thought to be driven largely by interactions with pollinators, but the extent to which current selection on floral traits is mediated by pollinators has rarely been determined experimentally. We documented selection through female function on floral traits in two populations of the rewarding orchid Gymnadenia conopsea in two years and quantified pollinator-mediated selection (δβpoll) by subtracting estimates of selection gradients for plants receiving supplemental hand pollination from estimates obtained for open-pollinated control plants. There was directional selection for taller plants, more flowers, larger corollas, and longer spurs in the study populations. Pollinator-mediated selection ranged from weak to moderately strong (δβpoll, range -0.01-0.21, median 0.08). All observed selection on spur length could be attributed to interactions with pollinators, while the proportion of observed selection on plant height (0%-77%), number of flowers (13%-42%), and corolla size (13%-97%) caused by pollinators varied among populations and years. Our results demonstrate that pollinators can mediate selection on both traits likely to be involved in pollinator attraction and traits affecting pollination efficiency. They further show that spatiotemporal variation in the strength of pollinator-mediated selection can contribute substantially to differences in selection between years and populations. © 2010 by The University of Chicago. Source

Grimes B.A.,Norwegian University of Science and Technology
Journal of Dispersion Science and Technology | Year: 2012

A population balance model for the separation of emulsions in a batch gravity settler is presented. Within the context of the model development, possible methodologies were elucidated for incorporating a) the physical properties of the bulk liquids, b) the physical properties of the phase interface, and c) the presence and functioning of interfacially active compounds. The model presented explicitly accounts for interfacial coalescence and the deformation of the emulsion zone due to the dynamic growth of the resolved dispersed phase; interfacial coalescence is modeled in terms of physically meaningful film drainage models and an approach for incorporating the accumulated buoyancy force in the dense packed layer is also discussed. Hydrodynamically hindered sedimentation is also considered in the model. The model is well suited to predict experimental batch settling data, especially data obtained from low-frequency NMR measurements of emulsion destabilization. The model predicts the evolution of the volume fraction of the dispersed phase at any axial position and time in the separator. Furthermore, the model predicts the location of the resolved dispersed phase interface as a function of time. Additionally, for any axial position and time in the settler, the model predicts the evolution of the average number density of droplets, the average volume/radius of droplets, the standard deviation of the droplet volume/radius, and the rate of growth of the droplets. The model is compared directly with experimental data for crude oil separations in Part II of this article. © 2012 Copyright Taylor and Francis Group, LLC. Source

Fors E.A.,Norwegian University of Science and Technology
Psycho-oncology | Year: 2011

This systematic review aimed to determine the effectiveness of psychoeducation, cognitive behavioural therapy (CBT) and social support interventions used in the rehabilitation of breast cancer (BC) patients. We conducted a systematic literature search to identify randomised controlled trials of female BC patients who underwent different psychosocial interventions during or after primary cancer treatment. The methodological quality of all studies was independently assessed by two reviewers. Studies with low quality, less than 20 participants in each group, patients with metastatic cancer, data not presented separately for BC and studies that included other cancer types were excluded. Among 9617 identified studies, only 18 RCTs published between 1999 and 2008, including 3272 patients were finally included in this systematic evaluation. Outcome measures were categorised into quality of life (QoL), fatigue, mood, health behaviour and social function. Six trials examined psychoeducation had inconsistent results, both during and after the primary treatment. Seven trials examined the effect of CBT, four of which given after primary treatment (range 6-12 weeks) demonstrated improvements in QoL; the other three CBT studies given during primary treatment (range 9-20 weeks) had inconsistencies. Five studies addressed social support and showed no conclusive impacts of this intervention. Limited documentation exists on the efficacy of psychosocial rehabilitation interventions among BC patients. However, we found that patients might have QoL benefits from CBT given after primary BC treatment. More documentation is needed regarding the effects of CBT during primary treatment and the effects of psychoeducation and social support. Copyright © 2010 John Wiley & Sons, Ltd. Source

Chen Y.,Norwegian University of Science and Technology
Journal of Rock Mechanics and Geotechnical Engineering | Year: 2014

A new method was developed to apply pull-and-shear loads to the bolt specimen in order to evaluate the anchorage performance of the rebar bolt and the D-Bolt. In the tests, five displacing angles (0°, 20°, 40°, 60°, and 90°), two joint gaps (0mm and 30mm), and three kinds of host rock materials (weak concrete, strong concrete, and concrete-granite) were considered, and stress-strain measurements were conducted. Results show that the ultimate loads of both the D-Bolt and the rebar bolt remained constant with any displacing angles. The ultimate displacement of the D-Bolt changed from 140mm at the 0° displacing angle (pure pull) to approximately 70mm at a displacing angle greater than 40°. The displacement capacity of the D-Bolt is approximately 3.5 times that of the rebar bolt under pure pull and 50% higher than that of the rebar bolt under pure shear. The compressive stress exists at 50mm from the bolt head, and the maximum bending moment value rises with the increasing displacing angle. The rebar bolt mobilises greater applied load than the D-Bolt when subjected to the maximum bending. The yielding length (at 0°) of the D-Bolt is longer than that of the rebar bolt. The displacement capacity of the bolts increased with the joint gap. The bolt subjected to joint gap effect yields more quickly with greater bending moment and smaller applied load. The displacement capacities of the D-Bolt and the rebar bolt are greater in the weak host rock than that in the hard host rock. In pure shear condition, the ultimate load of the bolts slightly decreases in the hard rock. The yielding speed in the hard rock is higher than that in the weak rock. © 2014 Institute of Rock and Soil Mechanics, Chinese Academy of Sciences. Source

Dahl T.,Norwegian University of Science and Technology | Olsen E.,University of Stavanger
Safety Science | Year: 2013

Accident analyses and investigations regularly identify a lack of compliance with rules and procedures as a central contributing factor to workplace accidents. This underlines the importance of identifying the organizational factors that affect the level of safety compliant behavior. The purpose of the present study was to examine how workers' perception of leadership involvement in daily work operations affects the level of safety compliant behavior among workers employed on offshore platforms operating on the Norwegian Continental Shelf. The effect that leadership involvement exerts on safety compliance was measured both directly and indirectly through the intervening variable work climate. Using survey data from six different measure periods (N=10003), exploratory and confirmatory factor analysis identified three dimensions of work climate; (1) workers' competence and involvement, (2) role clarity and (3) follow-up of contractors. The following SEM analyses revealed that leadership involvement in daily work operations has a significant positive influence on the level of safety compliance on offshore platforms. The effect of leadership involvement was found to be both direct and indirect, mediated by the three work climate dimensions selected for this study. Theoretical and managerial implications of the findings are discussed. © 2012 Elsevier Ltd. Source

Liu Y.,Norwegian University of Science and Technology
Reliability Engineering and System Safety | Year: 2014

Staggered testings are effective in improving the availability of redundant safety instrumented systems, and the optimal staggered time of testings for a system of two homogeneous components with the same testing interval has been proved as half of the testing interval. In this study, the impact of staggered time on the effectiveness of staggered testings for heterogeneous systems is examined, and the optimal staggered time is found still as half of the testing interval for systems with components different in failure rates but same in testing interval. In terms of systems with two components different in testing intervals, the optimal testing time is revealed as half of the shorter interval. Case studies of safety instrument systems present the same results. And then, Monte Carlo simulation based on Petri net models for these systems also confirms the conclusions obtained by numerical formulas. Such findings are helpful to effectively apply staggered testing strategies in more redundant systems. © 2014 Elsevier Ltd. Source

Brantberg K.,Norwegian University of Science and Technology
Journal of Neurology, Neurosurgery and Psychiatry | Year: 2010

Hyperactive disorders related to neurovascular compression have been described for several cranial nerves of which trigeminal neuralgia and hemifacial spasm are the best known. The present report on four patients, in conjunction with previous reports, suggests that paroxysmal staccato tinnitus might be considered an auditory hyperactivity disorder of the eighth cranial nerve. The present patients reported attacks, usually lasting 10e20 s, of loud monaural tinnitus with a staccato character (eg, clattering or sounding like a machine gun). The attacks occurred very frequently, sometimes every minute. The attacks were spontaneous but they were also provoked by certain head positions or by exposure to loud sounds. Most of the patients did not reveal any significant eighth cranial nerve sensory loss and thus it is probably not advisable to rely on any specific test result for this diagnosis. Instead, it is suggested that a diagnosis of paroxysmal staccato tinnitus can be based on the history as the symptoms are both stereotypic and very specific. Furthermore, low doses of carbamazepine, although not effective for the general population of tinnitus patients, relieved the symptoms. Source

Violations of rules and procedures are commonly identified as an important causal factor in workplace accidents. Essentially, there are two different types of violations: intentional and unintentional violations. Whereas the former term refers to deliberate violations of rules and procedures that are known and understood by the actor, the latter refers to violations of rules and procedures that the actor has no awareness or knowledge of and therefore operates without any reference to. The vast majority of previous research has been concerned with intentional rather than unintentional violations. This implies that researchers have put a particular focus on the aspects of work that affect workers' safety motivation and their attitudes towards compliant behavior, and that they have been less concerned with the factors that affect workers' knowledge of rules and procedures. On the basis of semi-structured interviews of 24 contract workers within the Norwegian petroleum industry, this research gap is addressed in the present paper. The objective is to identify, categorize and gain a comprehension of the most significant factors that affect workers' knowledge of rules and procedures. Analysis revealed that eight different factors within the workers' organizational context are important. These are sorted into three paramount categories: the safety management system, work characteristics and social interaction. The theoretical and practical implications of the findings are discussed. © 2013 Elsevier Ltd. Source

Teigen K.E.,Norwegian University of Science and Technology | Munkejord S.T.,Sintef
Physics of Fluids | Year: 2010

The deformation of a surfactant-covered, viscous drop suspended in a viscous fluid under the influence of an electric field is investigated using numerical simulations. The full Navier-Stokes equations are solved in both fluid phases, and the motion of the interface and the interfacial discontinuities are handled using the level-set method. The leaky-dielectric model is used to take into account the effect of an electric field. The surfactant is assumed to be insoluble, and an evolution equation for the motion of surfactant is solved along the drop surface. The surfactant concentration and the interfacial tension are coupled through a nonlinear equation of state. The numerical results show that the effect of surfactant strongly depends on the relative permittivity and conductivity between the fluids. The presence of surfactant can both increase and reduce the deformation, depending on the shape of the deformation and the direction of the electrically induced circulation. © 2010 American Institute of Physics. Source

Jiang Y.,Norwegian University of Science and Technology
2012 International Conference on Computing, Networking and Communications, ICNC'12 | Year: 2012

Stochastic network calculus is a theory for performance guarantee analysis of Internet networks. Originated in early 1990s, stochastic network calculus has its foundation on the min-plus convolution and max-plus convolution queueing principles. Although challenging, it has shown tremendous potential in dealing with queueing type problems encountered in Internet networks. By focusing on bounds, stochastic network calculus compliments the classical queueing theory. This paper provides an overview of stochastic network calculus from the queueing principle perspective and presents an outlook by discussing crucial yet still open challenges in the area. © 2012 IEEE. Source

Fayers P.M.,University of Aberdeen | Fayers P.M.,Norwegian University of Science and Technology | Hays R.D.,University of California at Los Angeles
Value in Health | Year: 2014

Background Profile instruments are frequently used to assess health-related quality of life and other patient-reported outcomes. However, preference-based measures are required for health-economic cost-utility evaluations. Results Although regression-based approaches are commonly used to map from profile measures to preference measures, we show that this results in biased estimates because of regression to the mean. Conclusions Linking (scale-aligning) is proposed as an alternative. © 2014 International Society for Pharmacoeconomics and Outcomes Research (ISPOR). Published by Elsevier Inc. Source

Sonnewald U.,Norwegian University of Science and Technology | Sonnewald U.,University of Sfax
Journal of Neurochemistry | Year: 2014

The central process in energy production is the oxidation of acetyl-CoA to CO2 by the tricarboxylic acid (TCA, Krebs, citric acid) cycle. However, this cycle functions also as a biosynthetic pathway from which intermediates leave to be converted primarily to glutamate, GABA, glutamine and aspartate and to a smaller extent to glucose derivatives and fatty acids in the brain. When TCA cycle ketoacids are removed, they must be replaced to permit the continued function of this essential pathway, by a process termed anaplerosis. Since the TCA cycle cannot act as a carbon sink, anaplerosis must be coupled with cataplerosis; the exit of intermediates from the TCA cycle. The role of anaplerotic reactions for cellular metabolism in the brain has been studied extensively. However, the coupling of this process with cataplerosis and the roles that both pathways play in the regulation of amino acid, glucose, and fatty acid homeostasis have not been emphasized. The concept of a linkage between anaplerosis and cataplerosis should be underscored, because the balance between these two processes is essential. The hypothesis that cataplerosis in the brain is achieved by exporting the lactate generated from the TCA cycle intermediates into the blood and perivascular area is presented. This shifts the generally accepted paradigm of lactate generation as simply derived from glycolysis to that of oxidation and might present an alternative explanation for aerobic glycolysis. © 2014 International Society for Neurochemistry. Source

Jasaityte R.,Catholic University of Leuven | Heyde B.,Catholic University of Leuven | D'Hooge J.,Catholic University of Leuven | D'Hooge J.,Norwegian University of Science and Technology
Journal of the American Society of Echocardiography | Year: 2013

With the developments in ultrasound transducer technology and both hardware and software computing, real-time volumetric imaging has become widely available, accompanied by various methods of assessing three-dimensional (3D) myocardial strain, often referred to as 3D speckle-tracking echocardiographic methods. Indeed, these methods should provide cardiologists with a better view of regional myocardial mechanics, which might be important for diagnosis, prognosis, and therapy. However, currently available 3D speckle-tracking echocardiographic methods are based on different algorithms, which introduce substantial differences between them and make them not interchangeable with each other. Therefore, it is critical that each 3D speckle-tracking echocardiographic method is validated individually before being introduced into clinical practice. In this review, the authors discuss differences and similarities of the currently available 3D strain estimation approaches and provide an overview of the current status of their validation. © 2013 by the American Society of Echocardiography. Source

Svendsen K.,Norwegian University of Science and Technology
European journal of pain (London, England) | Year: 2012

The aim of this study was to develop definitions to identify persons with clinically different patterns of persistent opioid use based on data from prescription databases. The study is based on data from the Norwegian Prescription Database using all dispensed opioid prescriptions during 2005-2008. Three definitions of persistent opioid use were developed using the following patient criteria: different levels of dispensed opioid amounts, number of prescriptions and the number of quarters out of the year in which prescriptions were dispensed. The three definitions each have some typical patient characteristics attached to them. The strict definition describes a typical patient using opioids to achieve a continuous serum concentration in the therapeutic range, the intermediate definition represents a typical patient using opioids daily but not around the clock and the wide definition describes a typical patient who uses opioids most of the days. To study whether the definitions accurately represent long-term use, the patient population was followed for 3 years, and the retention rate within each definition was measured. The point prevalence of persistent opioid use in Norway (4,681,134 inhabitants) as defined by the strict, intermediate and wide definitions was 0.16% (n = 7663), 0.50% (n = 23,498) and 1.08% (n = 50,791), respectively, as of 31 December 2007. At the end of the 3-year study period, the retention within any of the definitions was 83%, 84% and 68% for patients who met the criteria of the strict, intermediate and wide definitions, respectively. In the patient populations identified by the three definitions, a high rate of retention was observed, indicating that the proposed definitions can identify patients with long-term persistent use of opioids. © 2011 European Federation of International Association for the Study of Pain Chapters. Source

Foss B.,Norwegian University of Science and Technology
Control Engineering Practice | Year: 2012

This paper presents some key operational challenges in the upstream petroleum industries in which advanced control and model-based optimization has or may have a significant impact. A broad array of distinct applications are discussed and opportunities for process control methods are identified. This includes stabilizing control on an individual well level, model-based optimization for production allocation and long term recovery control. © 2012 Elsevier Ltd. Source

Hillestad M.,Norwegian University of Science and Technology
Chemical Engineering Science | Year: 2010

The foundation and implementation of a method for systematic reactor design is described. The reactor path is sectioned into stages where each stage is designed so as to optimize an overall objective. This is a further development of a previously proposed method for designing chemical reactors (Hillestad, 2004, 2005). Reactants pass through a series basic operations or functions to form the desired products. The basic operations are represented by design functions on the path volume. The design functions are fluid mixing (dispersion), distribution of extra feed points, distribution of heat transfer area and coolant temperature, catalyst dilution distribution and more. The conceptual reactor design problem is solved as an optimal control problem. A direct method is applied where both the design functions and the state variables are discretized. The realization of the optimization is a staged process string of multi-functional units. A kinetic model of the gas phase methanol synthesis is used as an example. By applying the method on the model, a staged reactor design with less heat transfer area and higher production is possible. © 2010 Elsevier Ltd. All rights reserved. Source

Krogstad P.-T.,Norwegian University of Science and Technology
International Journal of Heat and Fluid Flow | Year: 2012

Wind tunnel turbulence generated by a conventional and two multi-scale grids has been investigate. The grids were all designed to produce turbulence with the same integral scale, so that a direct comparison could be made between the flows, both in physical and scaled space. It has been suggested in the literature (e.g. Hurst and Vassilicos, 2007) that for a particular class of multi fractal grids, the turbulence decay depends exponentially on the distance from the grid. After a short distance where the flow is highly dependent of the geometry, it was found that the exponential decay is not unique to a particular geometry, but may be found over the same streamwise distances also behind the multi-scale grids, as well as for the conventional grid. By comparing the probability density functions measured using laser Doppler and hot wire anemometry it is shown that hot wire measurements may contain severe errors if taken too close to the grid. It is shown that negative streamwise velocity components may occasionally be found as far as 10 times the mesh widths downstream of the grid. Since hot wire anemometry is not able to measure the sign of the velocity vector, this leads to a folding of the data which artificially increases the derived mean velocity and, more seriously, reduces the width of the probability distribution. Hence the interpreted turbulent stress is reduced. © 2012 Elsevier Inc. Source

Brataas A.,Norwegian University of Science and Technology | Rashba E.I.,Harvard University
Physical Review Letters | Year: 2012

Nuclear spin polarization can be pumped into spin-blockaded quantum dots by multiple Landau-Zener passages through singlet-triplet anticrossings. By numerical simulations of realistic systems with 107 nuclear spins during 105 sweeps, we uncover a mechanism of dynamical self-quenching which results in a fast saturation of the nuclear polarization under stationary pumping. This is caused by screening the random field of the nuclear spins. For moderate spin-orbit coupling, self-quenching persists but its patterns are modified. Our finding explains low polarization levels achieved experimentally and calls for developing new protocols that break the self-quenching limitations. © 2012 American Physical Society. Source

Holter K.G.,Norwegian University of Science and Technology
Rock Mechanics and Rock Engineering | Year: 2015

The bonded property of multi-layered sprayed concrete tunnel linings (SCL) waterproofed with sprayed membranes means that the constituent materials will be exposed to the groundwater without any draining or mechanically separating measures. Moisture properties of the sprayed concrete and membrane materials are therefore important in order to establish the system properties of such linings. Ethyl-vinyl-acetate based sprayed membranes exhibit high water absorption potential under direct exposure to water, but are found to be significantly less hygroscopic and exhibit lower sorptivity (water absorption rate) than sprayed concrete. This material behavior explains the relatively dry in situ condition of the membrane that was observed. Measured in situ moisture content levels of the membrane material in tunnel linings have been found to vary within the range of 30–40 % of the maximum water absorption potential, and show a decreasing trend over the first 4 years after construction has been completed. A model for the mechanical loading, moisture condition and thermal exposure of the membrane and the resulting realistic parameters to be tested is presented. Laboratory testing methods for the membrane materials are evaluated considering possible loads, moisture and freezing exposure. Material testing of membrane materials was conducted with preconditioning to realistic moisture contents and under different temperature conditions including relevant freezing temperatures for tunnel linings. The main effects of the in situ moisture condition of the tested membrane materials are favorable tensile strengths in the range of 1.1–1.5 MPa and low risk of freeze–thaw damage. The crack bridging capacity of the tested membranes is found to be sensitive to temperature. With membrane thicknesses in the range of 3–4 mm, crack bridging capacity up to 4–6 mm opening of the crack width at 23 °C and approximately 1 mm opening at −3 °C was measured for the tested membranes. No significant reduction of the tensile bond strength could be demonstrated after 35 freeze–thaw cycles with −3 °C minimum temperature at the membrane location in the lining. Further work is required to verify the performance of the SCL system under exposure to high hydrostatic pressures and the effects of long term mechanical exposure. © 2015 The Author(s) Source

Haavik T.K.,Norwegian University of Science and Technology
Cognition, Technology and Work | Year: 2011

Lack of shared understanding is frequently found to be the main cause when accidents are investigated. Still, few studies explicitly explore and document the causal effects of shared understanding in successful work. Thus, the attribution of insufficient shared understanding as an accident cause lacks the substantiation of shared understanding as a contributor to successful work. In this article a case of measurement discrepancies in an offshore drilling operation is studied, and in the elaboration of the case shared understanding is found not to qualify as a condition with significant impact on the collaborative work. One important reason for this is the epistemological inadequacy of the different concepts of shared understanding. Although more critical research on shared understanding is needed before one can conclude more generic on this topic, the findings are important to the current development of Integrated Operations where shared understanding is pointed out as an important target area. © 2010 The Author(s). Source

Von Soest T.,University of Oslo | Von Soest T.,Norwegian Social Research | Wichstrom L.,Norwegian University of Science and Technology
Journal of Abnormal Child Psychology | Year: 2014

Several survey studies among adolescents have shown increasing rates of depressive symptoms over the last two to three decades. We know however little about mechanisms that might explain this increase. The present study uses data from three nationwide representative surveys of 16-17 year-old Norwegian adolescents that were conducted according to identical procedures in 1992, 2002, and 2010 (response rates 97.0, 91.0, 84.3 %, respectively). At each time point, approximately 3,000 adolescents participated (48.8 % girls and 51.2 % boys). Questionnaire data on depressive symptoms and a variety of potential risk and protective factors that might explain time trends in such symptoms were assessed at all time points. The results showed that the prevalence of high scores on depressive symptoms increased significantly between 1992 and 2002 among both boys and girls. No significant changes were observed between 2002 and 2010. The increase from 1992 to 2002 among girls and boys could be partially attributed to increases in eating problems and cannabis use, while reduced satisfaction with own appearance among girls contributed as well. Although the study does not provide information about the causal direction between putative risk factors and depressive symptoms, the results provide some indication that eating problems, cannabis use, and appearance related factors may contribute in explaining secular trends in depressive symptoms. © 2013 Springer Science+Business Media New York. Source

Hoyvik I.-M.,Norwegian University of Science and Technology | Jorgensen P.,University of Aarhus
Chemical Reviews | Year: 2016

The scope of this review article is to discuss the locality of occupied and virtual orthogonal Hartree-Fock orbitals generated by localization function optimization. Locality is discussed from the stand that an orbital is local if it is confined to a small region in space. Focusing on locality measures that reflects the spatial extent of the bulk of an orbital and the thickness of orbital tails, we discuss, with numerical illustrations, how the locality may be reported for individual orbitals as well as for sets of orbitals. Traditional and more recent orbital localization functions are reviewed, and the locality measures are used to compare the locality of the orbitals generated by the different localization functions, both for occupied and virtual orbitals. Numerical illustrations are given also for large molecular systems and for cases where diffuse functions are included in the atomic orbital basis. In addition, we have included a discussion on the physical and mathematical limitations on orbital locality. © 2016 American Chemical Society. Source

Strasunskas D.,Norwegian University of Science and Technology
Information and Software Technology | Year: 2012

Context: Dependency management often suffers from labor intensity and complexity in creating and maintaining the dependency relations in practice. This is even more critical in a distributed development, in which developers are geographically distributed and a wide variety of tools is used. In those settings, different interpretations of software requirements or usage of different terminologies make it challenging to predict the change impact. Objective: is (a) to describe a method facilitating change management in geographically distributed software engineering by effective discovery and establishment of dependency links using domain models; (b) to evaluate the effectiveness of the proposed method. Method: A domain model, providing a common reference point, is used to manage development objects and to automatically support dependency discovery. We propose to associate (annotate) development objects with the concepts from the model. These associations are used to compute dependency among development objects, and are stepwise refined to direct dependency links (i.e. enabling product traceability). To evaluate the method, we conducted a laboratory-based randomized experiment on two real cases. Six participants were using an implemented prototype and two comparable tools to perform simulated tasks. Results: In the paper we elaborate on the proposed method discussing its functional steps. Results from the experiment show that the method can be effectively used to assist in discovery of dependency links. Users have discovered on average fourteen percent more dependency links than by using the comparable tools. Conclusions: The proposed method advocates the use of domain models throughout the whole development life-cycle and is apt to facilitate multi-site software engineering. The experimental study and results suggest that the method is effective in the discovery of dependencies among development objects. © 2012 Elsevier B.V. All rights reserved. Source

Vigran T.E.,Norwegian University of Science and Technology
Applied Acoustics | Year: 2010

In a recent paper by the present author the effect of finite structural connections on the sound reduction index of double walls was predicted by modifying a model based on the transfer matrix technique. However, the model did not include any means to account for the flexibility of the studs; they were assumed to be of infinite stiffness. Based on data for the effective stiffness of flexible steel studs, the model is extended to take account of this flexibility. A number of comparisons are performed, mainly with the measured sound reduction index of lightweight double walls with gypsum boards. Cases include walls with cavity filling as well as with empty (air-filled) cavities. In the latter cases, the energy losses of the cavity are simulated using a model of a porous layer with a minute flow resistivity. Predicted results compare favourably with measurement results. It is assumed that different basic types of studs, i.e. other than the TC-type simulated here may successfully be included in the model. © 2010 Elsevier Ltd. All rights reserved. Source

Bailey J.L.,Norwegian University of Science and Technology
Marine Policy | Year: 2012

Whale watching is now reputed to be a 2 billion a year industry. This industry has the potential to impact the politics of whaling, specifically the moratorium on all commercial whaling in three ways: by creating political and economic counterweights to whalers, by countering claims about who may legitimately manage whales and to what end and by transforming views about whales and whaling both within whaling states and beyond. This article examines whale watching in Latin America and the Caribbean and the alliance of Latin American and Caribbean members of the International Whaling Commission (IWC) known as the Buenos Aires Group (BAG). The BAG group has emerged as coherent group opposing the ending of the moratorium and championing the views of whale watchers. The article finds that whale watching creates a politically important interest group in an area lacking whaling operations; it argues that these regional opponents of whaling provide a counter weight to charges that opposition to whaling is exclusively the providence of rich, urban citizens of developed countries and draw upon politically powerful frames in justifying their opposition to the lifting of the moratorium. Finally, it finds limited evidence that whale-watching is associated with a rise in general concern for marine mammals in the region. There remains the question, however, of what the future of whale watching in the region will be over the longer term. © 2011. Source

Vigran T.E.,Norwegian University of Science and Technology
Applied Acoustics | Year: 2010

The transfer matrix technique is an efficient tool for calculating sound transmission through multilayered structures. Recent developments, as to the calculation of the sound reduction index, have given better fit to measurement data, e.g. due to the simulation of finite size samples by the spatial windowing technique. In practice, however, finite size structural connections (points or lines) normally do exist between leaves in wall constructions and these are not "natural" elements in the transfer matrix method. The paper describes a simple method to account for the effect of point- and line-connections in double-leaf constructions in a transfer matrix setup. To cover the frequency range above the critical frequency of the constituent plates, some new developments as to the forced radiation from plates were needed. Predicted results compare favorably with measurement results for a number of different cases, also including a heavy wall. © 2009 Elsevier Ltd. All rights reserved. Source

Ostapchenko S.,Norwegian University of Science and Technology | Ostapchenko S.,Moscow State University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2011

The construction of a Monte Carlo generator for high energy hadronic and nuclear collisions is discussed in detail. Interactions are treated in the framework of the Reggeon Field Theory, taking into consideration enhanced Pomeron diagrams which are resummed to all orders in the triple-Pomeron coupling. Soft and "semihard" contributions to the underlying parton dynamics are accounted for within the "semihard Pomeron" approach. The structure of cut enhanced diagrams is analyzed; they are regrouped into a number of subclasses characterized by positively-defined contributions which define partial weights for various "macro-configurations" of hadronic final states. An iterative procedure for a Monte Carlo generation of the structure of final states is described. The model results for hadronic cross sections and for particle production are compared to experimental data. © 2011 American Physical Society. Source

Wang A.I.,Norwegian University of Science and Technology
Computers and Education | Year: 2015

The Bring Your Own Device (BYOD) wave and advancement in technical infrastructures and in learning technology opens for new ways of teaching in the classroom. The teachers' laptops connected to a video projector, access to wireless network and the students smartphones, tablets or laptops can be utilized to enhance the interaction between the teacher and students, as well as boost the students motivation, engagement and learning. The introduction of new learning technology in the classroom normally results in immediate enthusiasm and excitement both from the teacher and the students. However, the immediate positive effects might fade when the new learning technology has become familiar to the teacher and the students. This paper shows the results from investigating the wear off effect of using the game-based student response system Kahoot! in classroom teaching. More specifically, it compares the results from students using Kahoot! for the first time in a single motivational lecture vs. using Kahoot! in every lecture in a class for five months. The quasi-experiment focused on how the students' perception changed in relation to user-friendliness, engagement, motivation, classroom dynamics, concentration, and perceived learning. The results show a slight reduction in the students motivation and engagement, but the only statistically significant wear out effect found was related to classroom dynamics. At large, the game-based student response system managed to boost students engagement, motivation and learning after using it repeatedly for five months. The core factor to keep the students attention after heavy repeated usage was found to be the competitive nature of Kahoot!. © 2014 Elsevier Ltd. Source

Gjelsvik R.,Norwegian Radiation Protection Authority | Steinnes E.,Norwegian University of Science and Technology
Journal of Environmental Radioactivity | Year: 2013

In order to follow the turnover of 137Cs in natural soils and estimate future trends in exposure of livestock, samples of natural surface soils were collected at 0-3cm depth at 464 sites in 1995 and 463 sites in 2005 covering the country. In both cases the geographical pattern observed was similar to the original distribution from 1986, but the decline of 137Cs activity in the surface soil was not the same everywhere. In 1995 the 137Cs reduction since 1986 was found to be considerably greater in coastal areas than farther inland. The main reason for this appears to be the much greater deposition of marine cations such as Mg2+ and Na+ in the coastal areas, replacing Cs ions fixed on soil particle surfaces. This cation exchange appeared to be particularly strong near the southern coast where deposition of NH4+ from transboundary air pollution is evident in addition to the marine cations. During 1995-2005 the 137Cs decline in the surface soil was more uniform over the country than in the preceding 10-year period but still significantly higher in coastal areas than inland. Differences in precipitation chemistry may have influenced the uptake of 137Cs in terrestrial food chains. © 2013 Elsevier Ltd. Source

Rosvold J.,Norwegian University of Science and Technology
Journal of Biogeography | Year: 2016

Aim: To investigate the role of perennial ice and snow-covered land in the environment of birds and mammals, and to what degree vertebrates are parts of terrestrial glacial ecosystems. Location: Global. Methods: The synthesis was based on a review of existing literature. Results: The relationship between perennial ice and snow-covered land and birds and mammals is generally poorly known and behaviours associated with such areas are likely underreported. Nevertheless, the review revealed that a relatively large range of species actively use and spend large amounts of time on ice covered land. Foraging or seeking relief from both climatic and different biotic factors are the main behaviours associated with these landscapes, but for some species they are also important areas for food caching, water, play and travel, and even as nesting grounds. In well-used sites, birds and mammals are likely important contributors to the nutrient cycling of glacial ecosystems. Main conclusions: Despite increased global temperatures and rapid glacial melting in recent years, perennial ice and snow-covered landscapes have largely escaped management attention, likely due to them being viewed as inhospitable. It is, however, becoming increasingly clear that a large range of organisms inhabit and make use of the ice, and that these areas constitute high-quality parts of their habitats. It is therefore essential that glacierized areas are properly described, classified and managed as threatened ecosystems. © 2016 John Wiley & Sons Ltd. Source

Otte P.P.,Norwegian University of Science and Technology
Energy Policy | Year: 2013

In developing countries households and institutions heavily rely on biomass to satisfy their energy needs. The unsustainable use of biomass is accompanied by several negative health and environmental impacts. As a clean energy source, solar cooking presents one alternative solution. In spite of its multiple benefits; however, solar cookers have experienced little success. Curiously, there has been little discussion about this in academic circles. Most research concerns technical improvements of solar cookers, rather than on the reasons why these cookers are not actually adopted in the field. This paper fills the gap by developing a comprehensive list of variables that influence the adoption of solar cooking: (1) economic, (2) social, (3) cultural, (4) environmental, (5) political and (6) technical. Furthermore, we can see that some solar cooking promoters are able to control for some of the variables (e.g., environmental factors), but not others (e.g. technical, social and cultural factors). The latter can only be captured through a needs assessment of the target group. This sort of assessment is a demanding but necessary step for the successful outcome of a solar cooking project. © 2013 Elsevier Ltd. Source

Johansen P.-O.,EmmaSofia | Krebs T.S.,Norwegian University of Science and Technology
Journal of Psychopharmacology | Year: 2015

A recent large population study of 130,000 adults in the United States failed to find evidence for a link between psychedelic use (lysergic acid diethylamide, psilocybin or mescaline) and mental health problems. Using a new data set consisting of 135,095 randomly selected United States adults, including 19,299 psychedelic users, we examine the associations between psychedelic use and mental health. After adjusting for sociodemographics, other drug use and childhood depression, we found no significant associations between lifetime use of psychedelics and increased likelihood of past year serious psychological distress, mental health treatment, suicidal thoughts, suicidal plans and suicide attempt, depression and anxiety. We failed to find evidence that psychedelic use is an independent risk factor for mental health problems. Psychedelics are not known to harm the brain or other body organs or to cause addiction or compulsive use; serious adverse events involving psychedelics are extremely rare. Overall, it is difficult to see how prohibition of psychedelics can be justified as a public health measure. © The Author(s) 2015. Source

Hernandez-Palacio F.,Norwegian University of Science and Technology
Environmental Innovation and Societal Transitions | Year: 2016

This paper analyses urban densification in Norway as a key element of sustainable city policies. The city is viewed as a system in which changes of material aspects, such as density, are linked with social and technological aspects. Densification targets in Trondheim are used as a case study to explore the main actors and factors involved in urban development. A multilevel perspective approach used in sustainability transitions studies is applied as a model to describe them. The aim is to illustrate interactions and barriers arising in the implementation of densification policies. The argument suggests that despite a shift of paradigm in planning towards sustainability, urban regimes have remained rather stable. Some progress has been made, but further advancing the sustainability agenda may require new rules in the regime - for example, new planning policies integrated with taxation and financial instruments, and transport regulations - and a stronger emphasis on niche developments. © 2016 Elsevier B.V. Source

Nydal O.J.,Norwegian University of Science and Technology
Energy Procedia | Year: 2014

"Solar salt" (potassium and sodium nitrate mixture) is an option for a latent heat storage to be used with solar heat collectors. As the salt melts at about 210 degrees C it can be suitable as a heat storage for cooking applications. A solar salt container to be illuminated directly by the sun rays in should be heated from the top. One way of achieving this is to position the storage below a primary parabolic dish, this having a center hole to allow the rays from a secondary reflector to hit the top plate of the storage. A double reflector system becomes more sensitive to surface imperfections and to the solar tracking accuracy. A 2m diameter parabolic dish with a secondary 0.2 m diameter reflector has been considered as a test system for direct illumination of a heat storage. The optical performance of the system is investigated by means of a ray tracer. The ray tracer is described and a sensitivity study is made with respect to solar tracking accuracy, the effect of mirror tiles instead of smooth surfaces, the positioning and size of the secondary reflector and the effect of illumination of a the top plate from the side (the top plate remaining horizontal during the daily sun movements). A focusing effect is obtained by slightly lifting the secondary absorber above the point of the common focus of the primary and the secondary. The primary reflector should be as smooth as possible, the secondary reflector is less sensitive and could be surfaced with 1-2 cm mirror tiles with acceptable performance. A 10 cm diameter absorber dish is the minimum size, a 20 cm dish is more tolerant for tracking accuracy and for low solar angles. A large absorber dish also reduces the risk of superheating the top plate which has conduction based heat transfer to a salt storage. © 2013 The Authors.Published by Elsevier Ltd. Source

Vietri M.,University of Oslo | Schink K.O.,University of Oslo | Campsteijn C.,University of Oslo | Wegner C.S.,University of Oslo | And 7 more authors.
Nature | Year: 2015

At the onset of metazoan cell division the nuclear envelope breaks down to enable capture of chromosomes by the microtubule-containing spindle apparatus. During anaphase, when chromosomes have separated, the nuclear envelope is reassembled around the forming daughter nuclei. How the nuclear envelope is sealed, and how this is coordinated with spindle disassembly, is largely unknown. Here we show that endosomal sorting complex required for transport (ESCRT)-III, previously found to promote membrane constriction and sealing during receptor sorting, virus budding, cytokinesis and plasma membrane repair, is transiently recruited to the reassembling nuclear envelope during late anaphase. ESCRT-III and its regulatory AAA (ATPase associated with diverse cellular activities) ATPase VPS4 are specifically recruited by the ESCRT-III-like protein CHMP7 to sites where the reforming nuclear envelope engulfs spindle microtubules. Subsequent association of another ESCRT-III-like protein, IST1, directly recruits the AAA ATPase spastin to sever microtubules. Disrupting spastin function impairs spindle disassembly and results in extended localization of ESCRT-III at the nuclear envelope. Interference with ESCRT-III functions in anaphase is accompanied by delayed microtubule disassembly, compromised nuclear integrity and the appearance of DNA damage foci in subsequent interphase. We propose that ESCRT-III, VPS4 and spastin cooperate to coordinate nuclear envelope sealing and spindle disassembly at nuclear envelope-microtubule intersection sites during mitotic exit to ensure nuclear integrity and genome safeguarding, with a striking mechanistic parallel to cytokinetic abscission. © 2015 Macmillan Publishers Limited. Source

Linde M.,Norwegian University of Science and Technology
The Cochrane database of systematic reviews | Year: 2013

Some antiepileptic drugs but not others are useful in clinical practice for the prophylaxis of migraine. This might be explained by the variety of actions of these drugs in the central nervous system. The present review is part of an update of a Cochrane review first published in 2004, and previously updated (conclusions not changed) in 2007. To describe and assess the evidence from controlled trials on the efficacy and tolerability of gabapentin/gabapentin enacarbil or pregabalin for preventing migraine attacks in adult patients with episodic migraine. We searched the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library 2012, Issue 12), PubMed/MEDLINE (1966 to 15 January 2013), MEDLINE In-Process (current week, 15 January 2013), and EMBASE (1974 to 15 January 2013) and handsearched Headache and Cephalalgia through January 2013. Studies were required to be prospective, controlled trials of gabapentin/gabapentin enacarbil or pregabalin taken regularly to prevent the occurrence of migraine attacks, to improve migraine-related quality of life, or both. Two review authors independently selected studies and extracted data. For headache frequency data, we calculated mean differences (MDs) between gabapentin and comparator (placebo, active control, or gabapentin in a different dose) for individual studies and pooled these across studies. For dichotomous data on responders (patients with ≥ 50% reduction in headache frequency), we calculated odds ratios (ORs) and numbers needed to treat (NNTs). We also summarised data on adverse events from all single dosage studies and calculated risk differences (RDs) and numbers needed to harm (NNHs). Five trials on gabapentin and one trial on its prodrug gabapentin enacarbil met the inclusion criteria; no reports on pregabalin were identified. In total, data from 1009 patients were considered. One trial each of gabapentin 900 mg (53 patients), and gabapentin titrated to 1200 mg (63 patients) and 1800 mg (122 patients) failed to show a statistically significant reduction in headache frequency in the active treatment group as compared to the placebo group, whereas one trial of gabapentin titrated to 1800 to 2400 mg (113 patients) demonstrated a small but statistically significant superiority of active treatment for this outcome (MD -0.80; 95% confidence interval (CI) -1.55 to -0.05). The pooled results of these four studies (MD -0.44; 95% CI -1.43 to 0.56; 351 patients) do not demonstrate a significant difference between gabapentin and placebo. One trial of gabapentin titrated to 1800 mg (122 patients) failed to demonstrate a significant difference between active treatment and placebo in the proportion of responders (OR 0.97; 95% CI 0.45 to 2.11), whereas one trial of gabapentin titrated to 1800 to 2400 mg (113 patients) demonstrated a small but statistically significant superiority of active treatment for this outcome (OR 2.79; 95% CI 1.09 to 7.17). The pooled results of these two studies (OR 1.59; 95% CI 0.57 to 4.46; 235 patients) do not demonstrate a significant difference between gabapentin and placebo. Comparisons from one study (135 patients) suggest that gabapentin 2000 mg is no more effective than gabapentin 1200 mg. One trial of gabapentin enacarbil (523 participants) failed to demonstrate a significant difference versus placebo or between doses for gabapentin enacarbil titrated to between 1200 mg and 3000 mg with regard to proportion of responders; there was also no evidence of a dose-response trend. Adverse events, most notably dizziness and somnolence, were common with gabapentin. The pooled evidence derived from trials of gabapentin suggests that it is not efficacious for the prophylaxis of episodic migraine in adults. Since adverse events were common among the gabapentin-treated patients, it is advocated that gabapentin should not be used in routine clinical practice. Gabapentin enacarbil is not efficacious for the prophylaxis of episodic migraine in adults. There is no published evidence from controlled trials of pregabalin for the prophylaxis of episodic migraine in adults. Source

Efstathiou S.,Norwegian University of Science and Technology
Studies in History and Philosophy of Science Part C :Studies in History and Philosophy of Biological and Biomedical Sciences | Year: 2016

This paper argues that challenges that are grand in scope such as "lifelong health and wellbeing", "climate action", or "food security" cannot be addressed through scientific research only. Indeed scientific research could inhibit addressing such challenges if scientific analysis constrains the multiple possible understandings of these challenges into already available scientific categories and concepts without translating between these and everyday concerns. This argument builds on work in philosophy of science and race to postulate a process through which non-scientific notions become part of science. My aim is to make this process available to scrutiny: what I call founding everyday ideas in science is both culturally and epistemologically conditioned. Founding transforms a common idea into one or more scientifically relevant ones, which can be articulated into descriptively thicker and evaluatively deflated terms and enable operationalisation and measurement. The risk of founding however is that it can invisibilise or exclude from realms of scientific scrutiny interpretations that are deemed irrelevant, uninteresting or nonsensical in the domain in question-but which may remain salient for addressing grand-in-scope challenges. The paper considers concepts of "wellbeing" in development economics versus in gerontology to illustrate this process. © 2015 Elsevier Ltd. Source

De Grandis G.,Norwegian University of Science and Technology
Studies in History and Philosophy of Science Part C :Studies in History and Philosophy of Biological and Biomedical Sciences | Year: 2016

The paper uses two historical examples, public health (1840-1880) and town planning (1945-1975) in Britain, to analyse the challenges faced by goal-driven research, an increasingly important trend in science policy, as exemplified by the prominence of calls for addressing Grand Challenges. Two key points are argued. (1) Given that the aim of research addressing social or global problems is to contribute to improving things, this research should include all the steps necessary to bring science and technology to fruition. This need is captured by the idea of practical integration, which brings this type of research under the umbrella of collective practical reason rather than under the aegis of science. Achieving practical integration is difficult for many reasons: the complexity of social needs, the plurality of values at stake, the limitation of our knowledge, the elusive nature of the skills needed to deal with uncertainty, incomplete information and asymmetries of power. Nevertheless, drawing from the lessons of the case studies, it is argued that (2) practical integration needs a proper balance between values, institutions and knowledge: i.e. a combination of mutual support and mutual limitation. Pursuing such a balance provides a flexible strategy for approximating practical integration. © 2015 Elsevier Ltd. Source

Linde M.,Norwegian University of Science and Technology
The Cochrane database of systematic reviews | Year: 2013

Some antiepileptic drugs but not others are useful in clinical practice for the prophylaxis of migraine. This might be explained by the variety of actions of these drugs in the central nervous system. The present review is part of an update of a Cochrane review first published in 2004, and previously updated (conclusions not changed) in 2007. To describe and assess the evidence from controlled trials on the efficacy and tolerability of antiepileptic drugs other than gabapentin, pregabalin, topiramate, and valproate (which are the subjects of separate Cochrane reviews) for preventing migraine attacks in adult patients with episodic migraine. We searched the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library 2012, Issue 12), PubMed/MEDLINE (1966 to 15 January 2013), MEDLINE In-Process (current week, 15 January 2013), and EMBASE (1974 to 15 January 2013) and handsearched Headache and Cephalalgia through January 2013. Studies were required to be prospective, controlled trials of antiepileptic drugs other than gabapentin, pregabalin, topiramate, and valproate taken regularly to prevent the occurrence of migraine attacks, to improve migraine-related quality of life, or both. Two review authors independently selected studies and extracted data. For headache frequency data, we calculated mean differences (MDs) between antiepileptic drugs and comparators (placebo, active control, or same drug in a different dose) for individual studies and pooled these across studies. For dichotomous data on responders (patients with ≥ 50% reduction in headache frequency), we calculated odds ratios (ORs) and numbers needed to treat (NNTs). We also summarised data on adverse events from placebo-controlled trials and calculated risk differences (RDs) and numbers needed to harm (NNHs). Eleven papers describing 10 unique trials met the inclusion criteria. The 10 trials reported results for nine antiepileptic drugs other than gabapentin, pregabalin, topiramate, and valproate. Six of the eight drugs investigated in placebo-controlled trials were not better than placebo in reducing headache frequency per 28-day period during treatment (clonazepam, lamotrigine, oxcarbazepine, and vigabatrin) and/or in the proportion of responders (acetazolamide, carisbamate, lamotrigine, oxcarbazepine). One prospective, randomised, double-blind, single cross-over trial of 48 patients demonstrated a significant superiority of carbamazepine over placebo in the proportion of responders (OR 11.77; 95% confidence interval (CI) 3.92 to 35.32). The NNT was 2 (95% CI 2 to 3). In a small prospective, randomised, double-blind, parallel-group trial, levetiracetam 1000 mg was significantly superior to placebo in reducing headache frequency per 28-day period during treatment (MD -2.40; 95% CI -4.52 to -0.28; 26 patients), as well as in the proportion of responders (OR 26.07; 95% CI 1.30 to 521.91; 26 patients). The NNT was 2 (95% CI 1 to 4). The same trial examined levetiracetam 1000 mg versus topiramate 100 mg and found a small but significant difference favouring topiramate in headache frequency per 28-day period during treatment (MD 1.40; 95% CI 0.14 to 2.66; 28 patients). There was no significant difference between levetiracetam and topiramate in the proportion of responders (OR 0.71; 95% CI 0.16 to 3.23; 28 patients). Finally, one trial with 75 participants examined zonisamide versus topiramate (200 and 100 mg, respectively) and found no significant difference between them in reduction of headache frequency from baseline during the third month of treatment. Adverse events for active treatment versus placebo were available for all investigated drugs except levetiracetam, vigabatrin, and zonisamide. A high prevalence of adverse events was noted for carbamazepine, with a NNH of only 2 (95% CI 2 to 4). Available evidence does not allow robust conclusions regarding the efficacy of antiepileptic drugs other than gabapentin, pregabalin, topiramate, and valproate in the prophylaxis of episodic migraine among adults. Acetazolamide, carisbamate, clonazepam, lamotrigine, oxcarbazepine, and vigabatrin were not more effective than placebo in reducing headache frequency. In one trial each, carbamazepine and levetiracetam were significantly superior to placebo in reducing headache frequency, and there was no significant difference in proportion of responders between zonisamide and active comparator. These three positive studies suffer from considerable methodological limitations. Source

Linde M.,Norwegian University of Science and Technology
The Cochrane database of systematic reviews | Year: 2013

Some antiepileptic drugs but not others are useful in clinical practice for the prophylaxis of migraine. This might be explained by the variety of actions of these drugs in the central nervous system. The present review is part of an update of a Cochrane review first published in 2004, and previously updated (conclusions not changed) in 2007. To describe and assess the evidence from controlled trials on the efficacy and tolerability of valproate (valproic acid or sodium valproate or a combination of the two) for preventing migraine attacks in adult patients with episodic migraine. We searched the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library 2012, Issue 12), PubMed/MEDLINE (1966 to 15 January 2013), MEDLINE In-Process (current week, 15 January 2013), and EMBASE (1974 to 15 January 2013) and handsearched Headache and Cephalalgia through January 2013. Studies were required to be prospective, controlled trials of valproate taken regularly to prevent the occurrence of migraine attacks, to improve migraine-related quality of life, or both. Two review authors independently selected studies and extracted data. For headache frequency data, we calculated mean differences (MDs) between valproate and comparator (placebo, active control, or valproate in a different dose) for individual studies and pooled these across studies. For dichotomous data on responders (patients with ≥ 50% reduction in headache frequency), we calculated odds ratios (ORs) and, in select cases, risk ratios (RRs); we also calculated numbers needed to treat (NNTs). We calculated MDs for Migraine Disability Assessment (MIDAS) scores. We also summarised data on adverse events from placebo-controlled trials and calculated risk differences (RDs) and numbers needed to harm (NNHs). Ten papers describing 10 unique trials met the inclusion criteria. Analysis of data from two trials (63 participants) showed that sodium valproate reduced headache frequency by approximately four headaches per 28 days as compared to placebo (MD -4.31; 95% confidence interval (CI) -8.32 to -0.30). Data from four trials (542 participants) showed that divalproex sodium (a stable combination of sodium valproate and valproic acid in a 1:1 molar ratio) more than doubled the proportion of responders relative to placebo (RR 2.18; 95% CI 1.28 to 3.72; NNT 4; 95% CI 2 to 11). One study of sodium valproate (34 participants) versus placebo supported the latter findings (RR for responders 2.83; 95% CI 1.27 to 6.31; NNT 3; 95% CI 2 to 9). There was no significant difference in the proportion of responders between sodium valproate versus flunarizine (one trial, 41 participants) or between divalproex sodium versus propranolol (one trial, 32 participants). Pooled analysis of post-treatment mean headache frequencies in two trials (88 participants) demonstrates a slight but significant advantage for topiramate 50 mg over valproate 400 mg (MD -0.90; 95% CI -1.58 to -0.22). For placebo-controlled trials of sodium valproate and divalproex sodium, NNHs for clinically important adverse events ranged from 7 to 14. Valproate is effective in reducing headache frequency and is reasonably well tolerated in adult patients with episodic migraine. Source

Linde M.,Norwegian University of Science and Technology
The Cochrane database of systematic reviews | Year: 2013

Some antiepileptic drugs but not others are useful in clinical practice for the prophylaxis of migraine. This might be explained by the variety of actions of these drugs in the central nervous system. The present review is part of an update of a Cochrane review first published in 2004, and previously updated (conclusions not changed) in 2007. To describe and assess the evidence from controlled trials on the efficacy and tolerability of topiramate for preventing migraine attacks in adult patients with episodic migraine. We searched the Cochrane Central Register of Controlled Trials (CENTRAL; The Cochrane Library 2012, Issue 12), PubMed/MEDLINE (1966 to 15 January 2013), MEDLINE In-Process (current week, 15 January 2013), and EMBASE (1974 to 15 January 2013) and handsearched Headache and Cephalalgia through January 2013. Studies were required to be prospective, controlled trials of topiramate taken regularly to prevent the occurrence of migraine attacks, to improve migraine-related quality of life, or both. Two review authors independently selected studies and extracted data. For headache frequency data, we calculated mean differences (MDs) between topiramate and comparator (placebo, active control, or topiramate in a different dose) for individual studies and pooled these across studies. For dichotomous data on responders (patients with ≥ 50% reduction in headache frequency), we calculated odds ratios (ORs) and, in select cases, risk ratios (RRs); we also calculated numbers needed to treat (NNTs). We calculated MDs for selected quality of life instruments. Finally, we summarised data on adverse events from placebo-controlled trials and calculated risk differences (RDs) and numbers needed to harm (NNHs). Twenty papers describing 17 unique trials met the inclusion criteria. Analysis of data from nine trials (1737 participants) showed that topiramate reduced headache frequency by about 1.2 attacks per 28 days as compared to placebo (MD -1.20; 95% confidence interval (CI) -1.59 to -0.80). Data from nine trials (1190 participants) show that topiramate approximately doubled the proportion of responders relative to placebo (RR 2.02; 95% CI 1.57 to 2.60; NNT 4; 95% CI 3 to 6). Separate analysis of different topiramate doses produced similar MDs versus placebo at 50 mg (-0.95; 95% CI -1.95 to 0.04; three studies; 520 participants), 100 mg (-1.15; 95% CI -1.58 to -0.71; six studies; 1620 participants), and 200 mg (-0.94; 95% CI -1.53 to -0.36; five studies; 804 participants). All three doses significantly increased the proportion of responders relative to placebo; ORs were as follows: for 50 mg, 2.35 (95% CI 1.60 to 3.44; three studies; 519 participants); for 100 mg, 3.49 (95% CI 2.23 to 5.45; five studies; 852 participants); and for 200 mg, 2.49 (95% CI 1.61 to 3.87; six studies; 1025 participants). All three doses also significantly improved three or more domains of quality of life as compared to placebo. Meta-analysis of the three studies that included more than one dose of topiramate suggests that 200 mg is no more effective than 100 mg. With regard to mean headache frequency and/or responder rate, seven trials using active comparators found (a) no significant difference between topiramate and amitriptyline (one study, 330 participants); (b) no significant difference between topiramate and flunarizine (one study, 83 participants); (c) no significant difference between topiramate and propranolol (two studies, 342 participants); (d) no significant difference between topiramate and relaxation (one study, 61 participants); but (e) a slight significant advantage of topiramate over valproate (two studies, 120 participants). Relaxation improved migraine-specific quality of life significantly more than topiramate. In trials of topiramate against placebo, seven adverse events (AEs) were reported by at least three studies. These were usually mild and of a non-serious nature. Except for taste disturbance and weight loss, there were no significant differences in the frequency of AEs in general, or of the seven specific AEs, between placebo and topiramate 50 mg. AEs in general and all of the specific AEs except nausea were significantly more common on topiramate 100 mg than on placebo, with NNHs varying from 3 to 25, and the RDs versus placebo were even higher for topiramate 200 mg, with NNHs varying from 2 to 17. Meta-analysis demonstrates that topiramate in a 100 mg/day dosage is effective in reducing headache frequency and reasonably well-tolerated in adult patients with episodic migraine. This provides good evidence to support its use in routine clinical management. More studies designed specifically to compare the efficacy or safety of topiramate versus other interventions with proven efficacy in the prophylaxis of migraine are needed. Source

Aytac A.,Norwegian University of Science and Technology
Journal of Materials Science | Year: 2010

A group of Cu(II), Ni(II) and Co(II) complexes of -Br and -OCH 2CH3 substituted Schiff bases as a new class of corrosion inhibitors for aluminium has been studied in 0.1 M HCl by the addition of 10 ppm compound using potentiodynamic polarization, electrochemical impedance spectroscopy, linear polarization methods and gas evolution tests at 25 °C. The inhibition efficiencies obtained from all methods employed are in good agreement. Results show Ni(II) complex of -OCH2CH3 substituted Schiff bases was the best inhibitor with a mean efficiency of 69% at 10 ppm additive concentration. The potentiodynamic polarization curves showed both the cathodic and the anodic processes of aluminium corrosion were suppressed, and the Nyquist plots of impedance gave mainly a capacitive loop. Scanning electron microscopy (SEM) was done from the surface of the exposed sample indicating uniform film on the surface. © 2010 Springer Science+Business Media, LLC. Source

Donato F.,Friedrich Miescher Institute for Biomedical Research | Donato F.,Norwegian University of Science and Technology | Chowdhury A.,Friedrich Miescher Institute for Biomedical Research | Lahr M.,Friedrich Miescher Institute for Biomedical Research | Caroni P.,Friedrich Miescher Institute for Biomedical Research
Neuron | Year: 2015

Brain networks can support learning by promoting acquisition of task-relevant information or by adhering to validated rules, but the mechanisms involved are poorly understood. Upon learning, local inhibitory parvalbumin (PV)-expressing Basket cell networks can switch to opposite configurations that either favor or interfere with further learning, but how this opposite plasticity is induced and relates to distinct learning requirements has remained unclear. Here, we show that PV Basket cells consist of hitherto unrecognized subpopulations, with distinct schedules of neurogenesis, input connectivities, output target neurons, and roles in learning. Plasticity of hippocampal early-born PV neurons was recruited in rule consolidation, whereas plasticity of late-born PV neurons was recruited in new information acquisition. This involved regulation of early-born neuron plasticity specifically through excitation, and of late-born neuron plasticity specifically through inhibition. Therefore, opposite learning requirements are implemented by distinct local networks involving PV Basket cell subpopulations specifically regulated through inhibition or excitation. © 2015 Elsevier Inc. Source

Aamo O.M.,Norwegian University of Science and Technology
IEEE Transactions on Automatic Control | Year: 2013

Many interesting problems in the oil and gas industry face the challenge of responding to disturbances from afar. Typically, the disturbance occurs at the inlet of a pipeline or the bottom of an oil well, while sensing and actuation equipment is installed at the outlet, only, kilometers away from the disturbance. The present paper develops an output feedback control law for such cases, based on modelling the transport phenomenon as a 2 x 2 linear partial differential equation (PDE) of hyperbolic type and the disturbance as a finite-dimensional linear system affecting the left boundary of the PDE. Sensing and actuation are co-located at the right boundary of the PDE. The design provides a separation principle, allowing a disturbance attenuating full-state feedback control law to be combined with an observer. The results are applied to a relevant problem from the oil and gas industry and demonstrated in simulations. © 2012 IEEE. Source

Donaire A.,University of Newcastle | Perez T.,University of Newcastle | Perez T.,Norwegian University of Science and Technology
Automatica | Year: 2012

Dynamic positioning of marine craft refers to the use of the propulsion system to regulate the vessel position and heading. This type of motion control is commonly used in the offshore industry for surface vessels, and it is also used for some underwater vehicles. In this paper, we use a port-Hamiltonian framework to design a novel nonlinear set-point-regulation controller with integral action. The controller handles input saturation and guarantees internal stability, rejection of unknown constant disturbances, and (integral-)input-to- state stability. © 2012 Elsevier Ltd. All rights reserved. Source

Stovner L.J.,Norwegian University of Science and Technology | Andree C.,CRP Sante | Andree C.,University of Basel
Journal of Headache and Pain | Year: 2010

The main aim of the present study was to do an update on studies on headache epidemiology as a preparation for the multinational European study on the prevalence and burden of headache and investigate the impact of different methodological issues on the results. The study was based on a previous study, and a systematic literature search was performed to identify the newest studies. More than 50% of adults indicate that they suffer from headache in general during the last year or less, but when asked specifically about tension-type headache, the prevalence was 60%. Migraine occurs in 15%, chronic headache in about 4% and possible medication overuse headache in 1-2%. Cluster headache has a lifetime prevalence of 0.2-0.3%. Most headaches are more prevalent in women, and somewhat less prevalent in children and youth. Some studies indicate that the headache prevalence is increasing during the last decades in Europe. As to methodological issues, lifetime prevalences are in general higher than 1-year prevalences, but the exact time frame of headache (1 year, 6 or 3 months, or no time frame stated) seems to be of less importance. Studies using personal interviews seem to give somewhat higher prevalences than those using questionnaires. © The Author(s) 2010. Source

Mesiti F.,Norwegian University of Science and Technology | Balasingham I.,University of Oslo
IEEE Journal on Selected Areas in Communications | Year: 2013

The recent advancements in nanotechnology have been instrumental in initiating research and development of intelligent nanomachines, in a variety of different application domains including healthcare. The stimulation of the cerebral cortex to assist the treatment of brain diseases have been investigated with growing interest in the past, where nanotechnology offers a dramatic breakthrough. In this paper, we discuss the feasibility of a nanomachine-to-neuron interface to design a nanoscale stimulator device called synaptic nanomachine (SnM), compatible with the neuronal communication paradigm. An equivalent neuron-nanomachine model (EqNN) is proposed to describe the behavior of neurons excited by a network of SnMs. Sample populations of neurons are simulated under different stimulation scenarios. The assessment of the existing correlation between SnM stimulus and response, as well as between neurons and clusters of neurons, has been performed using statistical methods. The obtained results reveal that a controlled nanoscale stimulation induces apparently an oscillatory behavior in the neuronal activity and localized synchronization between neurons. Both effects are expected to have the basis of important cognitive and behavioral functions such as learning and brain plasticity. © 1983-2012 IEEE. Source

Rolstadas A.,Norwegian University of Science and Technology
Journal of Intelligent Manufacturing | Year: 2013

An e-learning approach for project management using the hybrid model has been developed, tested and improved. Two Norwegian universities have developed a continuing education programme at two levels. The client has been three industrial companies in the oil and gas sector. For delivery another two universities outside Norway has participated. The hybrid model contains two plenary sessions using traditional teaching methods. In addition there are a number of virtual sessions using technology enhanced learning including multimedia technology. In addition there is a project assignment to be solved by groups of three course participants. Experience has shown that training based on a combination of on-campus and Web-based is an effective approach. This concept may be significantly more effective than traditional programs with plenary sessions only or with virtual content only. © 2011 The Author(s). Source

Okoh P.,Norwegian University of Science and Technology
Process Safety and Environmental Protection | Year: 2015

Riser system failure in relation to major accidents is one of the potential undesirable events in the offshore petroleum industry. It has the potential for high consequence such as several fatalities/injuries, severe environmental impact or gross economic loss. Besides, it may be related to maintenance being insufficient, incorrect, a new hazard source or a triggering event for an accident scenario. Furthermore, there has been a paradigm shift in the design of unmanned platforms following the Piper Alpha disaster in 1988. Firefighting systems are usually not installed anymore based on the reason that the risk reduction benefit they offer to maintenance personnel is not commensurate with their frequency of visits unlike in manned facilities, i.e. a negative risk balance. In manned facilities, where such safety systems are installed, maintenance personnel are subject to major hazard exposure due to the visits required of them. Hence, there is the need to reduce the risk to personnel as much as reasonable. Maintenance grouping optimization can serve as an alternative contributor to the reduction of maintenance frequencies which should reduce the risk, but on the other hand, as the human error opportunities increase, the likelihood of making errors increases which increases risk. The main objective of this paper is to investigate how maintenance grouping optimization and the potential human error can be balanced in relation to reducing the major accident risk. The paper builds on a review of literature on maintenance optimization, human reliability and risk. © 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved. Source

Kusnierczyk A.,Norwegian University of Science and Technology
BMC genomics | Year: 2011

Phloem-feeding aphids deprive plants of assimilates, but mostly manage to avoid causing the mechanical tissue damage inflicted by chewing insects. Nevertheless, jasmonate signalling that is induced by infestation is important in mediating resistance to phloem feeders. Aphid attack induces the jasmonic acid signalling pathway, but very little is known about the specific impact jasmonates have on the expression of genes that respond to aphid attack. We have evaluated the function that jasmonates have in regulating Arabidopsis thaliana responses to cabbage aphid (Brevicoryne brassicae) by conducting a large-scale transcriptional analysis of two mutants: aos, which is defective in jasmonate production, and fou2, which constitutively induces jasmonic acid biosynthesis. This analysis enabled us to determine which genes' expression patterns depend on the jasmonic acid signalling pathway. We identified more than 200 genes whose expression in non-challenged plants depended on jasmonate levels and more than 800 genes that responded differently to infestation in aos and fou2 plants than in wt. Several aphid-induced changes were compromised in the aos mutant, particularly genes connected to regulation of transcription, defence responses and redox changes. Due to jasmonate-triggered pre-activation of fou2, its transcriptional profile in non-challenged plants mimicked the induction of defence responses in wt. Additional activation of fou2 upon aphid attack was therefore limited. Insect fitness experiments revealed that the physiological consequences of fou2 mutation contributed to more effective protection against B. brassicae. However, the observed resistance of the fou2 mutant was based on antibiotic rather than feeding deterrent properties of the mutant as indicated by an analysis of aphid feeding behaviour. Analysis of transcriptional profiles of wt, aos and fou2 plants revealed that the expression of more than 200 genes is dependent on jasmonate status, regardless of external stimuli. Moreover, the aphid-induced response of more than 800 transcripts is regulated by jasmonate signalling. Thus, in plants lacking jasmonates many of the defence-related responses induced by infestation in wt plants are impaired. Constant up-regulation of jasmonate signalling as evident in the fou2 mutant causes reduction in aphid population growth, likely as a result of antibiotic properties of fou2 plants. However, aos mutation does not seem to affect aphid performance when the density of B. brassicae populations on plants is low and aphids are free to move around. Source

Representing an environment globally, in a coarse way, and locally, in a fine-grained way, are two fundamental aspects of how our brain interprets the world that surrounds us. The neural correlates of these representations have not been explicated in humans. In this study we used fMRI to investigate these correlates and to explore a possible functional segregation in the hippocampus and parietal cortex. We hypothesized that processing a coarse, global environmental representation engages anterior parts of these regions, whereas processing fine-grained, local environmental information engages posterior parts. Participants learned a virtual environment and then had to find their way during fMRI. After scanning, we assessed strategies used and representations stored. Activation in the hippocampal head (anterior) was related to the multiple distance and global direction judgments and to the use of a coarse, global environmental representation during navigation. Activation in the hippocampal tail (posterior) was related to both local and global direction judgments and to using strategies like number of turns. A structural shape analysis showed that the use of a coarse, global environmental representation was related to larger right hippocampal head volume and smaller right hippocampal tail volume. In the inferior parietal cortex, a similar functional segregation was observed, with global routes represented anteriorly and fine-grained route information such as number of turns represented posteriorly. In conclusion, moving from the anterior to the posterior hippocampus and inferior parietal cortex reflects a shift from processing coarse global environmental representations to processing fine-grained, local environmental representations. Source

Paunonen S.,Norwegian University of Science and Technology
BioResources | Year: 2013

Cellulose derivatives, i.e. cellulose functionalized in a solvent state with various side groups, are an important source of biomaterials for food packaging. This review considers the following materials: i) cellophane, ii) cellulose acetate, iii) methylcellulose, and iv) carboxymethylcellulose. Mechanical and barrier properties are important for freestanding packaging films as well as for coatings. The potential of the selected cellulose derivatives and cellophane is thus examined from the viewpoint of their tensile properties as well as their moisture and oxygen barrier properties. The capacity of microcrystalline cellulose and nano-sized celluloses to reinforce the films and to help impede gas diffusion is examined for microfibrillar celluloses, nanocrystalline celluloses, and whiskers. Very good oxygen barrier properties have been reported for cellophane. Nanocellulose fillers have regularly been shown to enhance the tensile properties of several cellulose derivatives, but the effects on the water vapor permeability (WVP) have been studied less often. Source

Thimm J.C.,Norwegian University of Science and Technology | Thimm J.C.,Psychiatric Center
Journal of Behavior Therapy and Experimental Psychiatry | Year: 2010

In schema therapy (ST), early maladaptive schemas (EMS) are proposed to be the defining core of personality disorders. Adverse relational experiences in childhood are assumed to be the main cause for the development of EMS. The present study explored the links between perceived parental rearing behaviours, EMS, and personality disorder symptoms in a clinical sample (N = 108). Results from mediation analyses suggest that EMS mediate the relationships between recalled parenting rearing behaviours and personality disorder symptoms. Findings give support to the theoretical model ST is based on. © 2009 Elsevier Ltd. All rights reserved. Source

Lovstad A.,Norwegian University of Science and Technology | Cawley P.,Imperial College London
NDT and E International | Year: 2011

Localised corrosion is a major concern in the petrochemical industry, and often occurs as clusters of pits. A study of the reflection from two and three small circular holes in pipes with the fundamental torsional guided wave incident is presented. FE analyses with both part and through thickness holes at different relative positions are presented, and are a step towards estimation of the scattering behaviour of multiple and random defects. The validity of employing the superposition technique in estimating reflection coefficients is assessed. Results show that the reflection coefficient for the T(0,1) mode is dependent on absolute frequency and axial separation, and independent of circumferential position. Employing superposition is found to be valid down to defect centre to centre separation distances of two diameters in the worst case, with improved validity with shallower defects. Results from the FE analyses are validated experimentally. © 2011 Elsevier Ltd. Source

Andersen J.O.,Norwegian University of Science and Technology | Mogliacci S.,Bielefeld University | Su N.,Bielefeld University | Vuorinen A.,Bielefeld University
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2013

We evaluate the second and fourth order quark number susceptibilities in hot QCD using two variations of resummed perturbation theory. On one hand, we carry out a one-loop calculation within hard-thermal-loop perturbation theory, and on the other hand perform a resummation of the four-loop finite density equation of state derived using a dimensionally reduced effective theory. Our results are subsequently compared with recent high precision lattice data, and their agreement thoroughly analyzed. © 2013 American Physical Society. Source

Lohre A.,Norwegian University of Science and Technology
BMC public health | Year: 2010

Determinants of children's school wellbeing have not been extensively studied. In this cross-sectional study of school children we assessed how factors assumed to promote wellbeing and factors assumed to adversely influence wellbeing were associated with self-reported wellbeing in school. Children from five schools, 230 boys and 189 girls in grades 1-10, responded to the same set of questions. We used proportional odds logistic regression to assess the associations of promoting and restraining factors with school wellbeing. In a multivariable analysis, degree of school wellbeing in boys was strongly and positively related to enjoying school work (odds ratio, 3.84, 95% CI 2.38 to 6.22) and receiving necessary help (odds ratio, 3.55, 95% CI 2.17 to 5.80) from teachers. In girls, being bothered during lessons was strongly and negatively associated with school wellbeing (odds ratio, 0.43, 95% CI 0.22 to 0.85). Different factors may determine school wellbeing in boys and girls, but for both genders, factors relevant for lessons may be more important than factors related to recess. Especially in boys, the student-teacher relationship may be of particular importance. Source

Rudyk S.,Norwegian University of Science and Technology | Spirov P.,University of Aalborg
Applied Energy | Year: 2014

The current experimental study describes the recovery of bitumen from Nigerian tar sand by the supercritical carbon dioxide method, which has the advantages of a substantial reduction in water consumption, an absence of chemicals, and an upgrading of the bitumen through the rejection of solids, petcokes and asphaltenes. The bitumen extraction from 50g piece of tar sand was carried out at 50, 60 and 65MPa and 110°C by pure carbon dioxide and with the addition of 10mL of fresh or salty water. The recovery decreased in the following order: with salty water, with fresh water, pure CO2. The maximum recovery of 29.6% was obtained at 50MPa with the addition of salty water declining at higher pressures. The heaviest fractions were extracted by pure carbon dioxide at 60 and 65MPa. The presence of bisnorhopane, a biomarker typical for source rocks formed in marine depositional environment, was detected in crude bitumen and all extracts by GC-MS TIC analysis. © 2013 Elsevier Ltd. Source

Botero C.A.,North Carolina State University | Botero C.A.,Washington University in St. Louis | Weissing F.J.,University of Groningen | Wright J.,Norwegian University of Science and Technology | Rubenstein D.R.,Columbia University
Proceedings of the National Academy of Sciences of the United States of America | Year: 2015

In an era of rapid climate change, there is a pressing need to understand how organisms will cope with faster and less predictable variation in environmental conditions. Here we develop a unifying model that predicts evolutionary responses to environmentally driven fluctuating selection and use this theoretical framework to explore the potential consequences of altered environmental cycles. We first show that the parameter space determined by different combinations of predictability and timescale of environmental variation is partitioned into distinct regions where a single mode of response (reversible phenotypic plasticity, irreversible phenotypic plasticity, bet-hedging, or adaptive tracking) has a clear selective advantage over all others. We then demonstrate that, although significant environmental changes within these regions can be accommodated by evolution, most changes that involve transitions between regions result in rapid population collapse and often extinction. Thus, the boundaries between response mode regions in our model correspond to evolutionary tipping points, where even minor changes in environmental parameters can have dramatic and disproportionate consequences on population viability. Finally, we discuss how different life histories and genetic architectures may influence the location of tipping points in parameter space and the likelihood of extinction during such transitions. These insights can help identify and address some of the cryptic threats to natural populations that are likely to result from any natural or human-induced change in environmental conditions. They also demonstrate the potential value of evolutionary thinking in the study of global climate change. © 2015, National Academy of Sciences. All rights reserved. Source

Fehske A.,TU Dresden | Fettweis G.,IBM | Malmodin J.,RBS Basic Technology Research Unit | Biczok G.,Norwegian University of Science and Technology
IEEE Communications Magazine | Year: 2011

This article quantifies the global carbon footprint of mobile communication systems, and discusses its ecological and economic implications. Using up-to-date data and life cycle assessment models, we predict an increase of CO2 equivalent emissions by a factor of three until 2020 compared to 2007, rising from about 86 to 235 Mto CO2e, suggesting a steeper increase than predicted in the well-known SMART2020 report. We provide a breakdown of the global carbon footprint, which reveals that production of mobile devices and global radio access network operation will remain the major contributors, accompanied by an increasing share of emissions due to data transfer in the backbone resulting from rising mobile traffic volumes. The energy bill due to network operation will gain increasing importance in cellular business models. Furthermore, technologies to reduce energy consumption are considered a key enabler for the spread of mobile communications in developing countries. Taking into account several scenarios of technological advancement and rollout, we analyze the overall energy consumption of global radio access networks and illustrate the saving potential of green communication technologies. We conclude that, conditioned on quick implementation and alongside other "classical" improvements of spectral efficiency, these technologies offer the potential to serve three orders of magnitude more traffic with the same overall energy consumption as today. © 2011 IEEE. Source

Paso K.G.,Norwegian University of Science and Technology
Journal of Dispersion Science and Technology | Year: 2014

A conservative analytical method is presented to provide reliable predictions for waxy oil pipeline shut-in and restart. A comprehensive bench-top characterization regimen establishes in situ gel properties, utilizing thermodynamic modeling, differential scanning calorimetry, and rheometry to forecast the wax-gel mechanical response. For flow commencement modeling, pressure wave propagation simulators have recently emerged with correct predictions for the acoustic, viscous, and gel degradation regimes. Scaling analysis shows that the viscous wave is determinative for achieving timely restart in long pipelines. The informed rheology serves as a useful input to simulate restart flows. For gelation and shut-in flow predictions, a heuristic approach is currently recommended. © 2014 Copyright Taylor & Francis Group, LLC. Source

Weston K.S.,University of Queensland | Wisloff U.,Norwegian University of Science and Technology | Coombes J.S.,University of Queensland
British Journal of Sports Medicine | Year: 2014

Background/Aim Cardiorespiratory fitness (CRF) is a strong determinant of morbidity and mortality. In athletes and the general population, it is established that high-intensity interval training (HIIT) is superior to moderate-intensity continuous training (MICT) in improving CRF. This is a systematic review and metaanalysis to quantify the efficacy and safety of HIIT compared to MICT in individuals with chronic cardiometabolic lifestyle diseases. Methods The included studies were required to have a population sample of chronic disease, where poor lifestyle is considered as a main contributor to the disease. The procedural quality of the studies was assessed by use of a modified Physiotherapy Evidence Base Database (PEDro) scale. A meta-analysis compared the mean difference (MD) of preintervention versus postintervention CRF (VO2peak) between HIIT and MICT. Results 10 studies with 273 patients were included in the meta-analysis. Participants had coronary artery disease, heart failure, hypertension, metabolic syndrome and obesity. There was a significantly higher increase in the VO2peak after HIIT compared to MICT (MD 3.03 mL/kg/ min, 95% CI 2.00 to 4.07), equivalent to 9.1%. Conclusions HIIT significantly increases CRF by almost double that of MICT in patients with lifestyle-induced chronic diseases. Source

Yilmaz A.E.,Abant Izzet Baysal University | Gencoz T.,Middle East Technical University | Wells A.,Norwegian University of Science and Technology
Journal of Anxiety Disorders | Year: 2011

According to the metacognitive theory of psychological disorder, metacognitions are vulnerability factors in predicting development of psychological symptoms. The present study investigated metacognitive factors and life stress in a prospective test of their proposed temporal precedence in the development of anxiety and depression symptoms. Participants were 172 students and adults recruited in Ankara and Bolu, Turkey. Two separate sets of hierarchical regression analyses were conducted. In these analyses, Time 2 anxiety or depression was regressed on the main and interaction effects of metacognition and stress after controlling for baseline symptom levels measured at Time 1, age, and gender. Results revealed that negative metacognitive beliefs about the uncontrollability and danger of worry significantly predicted residual change in both anxiety and depression after controlling for the negative effect of stressful life events. Furthermore, lack of cognitive confidence interacted with daily hassles to predict the change in anxiety, when the baseline level of anxiety and other individual differences were controlled. Our results support the metacognitive theory of psychopathology. © 2010 Elsevier Ltd. Source

Haavik T.K.,Norwegian University of Science and Technology
Journal of Contingencies and Crisis Management | Year: 2012

Integrated operations (IO) is an operating mode in the offshore oil and gas industry that is expected to lead to safer, faster and better operations. This article presents an analysis of the anticipated impacts of increased instrumentation on the safety of drilling operations. The instrumentation is related to the change process of IO, and is exemplified by a group of IO tools for interpretation, diagnosis and automation. An important finding in the study is the identification of a set of controversies that reflect characteristic challenges of drilling operations. These controversies involve the quantity and accessibility of information, the issue of centralized and decentralized control, the relation between standardized and unique interpretation of data, and the heterogeneous nature of engineering work. It is argued that the impact of the IO tools on safety will depend on how these controversies are taken into account when the tools are adopted. It is also argued that the cognitive control of the operations is distributed across a range of human and nonhuman actors and that the impact of the IO tools thus depends on how they are adapted to the system of distributed cognition rather than on the properties of the tools themselves. © 2012 Blackwell Publishing Ltd. Source

Tukker A.,Applied Scientific Research | Tukker A.,Norwegian University of Science and Technology
Journal of Cleaner Production | Year: 2013

There is widespread concern that the 'economy is crashing against the Earth', already causing problems in terms of climate change, water depletion and loss of biodiversity. Yet, the global economy still will have to grow two- to four-fold to provide all future global inhabitants with the average yearly income of $10,000 that is needed to have a reasonable life expectancy and human development index. Rio+20 was intended to reconcile the need for poverty eradication with a green economy, but had limited perceived success. This paper analyses how some of the major international sustainability programs that contributed to Rio+20 could have supported a more far-reaching outcome. Two problems are identified: the programs showed significant overlap, and the programs themselves were often incremental in nature, seeking compromises and avoiding more radical approaches such as the 'degrowth agenda'. To address the first problem, we suggest how a natural process of mutual collaboration, learning and strengthening could occur: the UN Green Economy Initiative could focus on providing the socio-economic rationale for sustainability; bodies like the IPCC and the UNEP Resources Panel could focus on providing the environmental rationale and planetary limits related to sustainability; programs in the field of sustainable consumption and production as well as resource-efficient and cleaner production could focus on providing hands-on support and proof of how to change direction. There seems no clear-cut answer for the second problem. Some authors suggest relying more on action outside formal policy systems that, by nature, seek compromises. However, they also see a required role for government action, which is exactly what Rio+20 and its supportive policy programs failed to achieve and negotiate. © 2013 Elsevier Ltd. All rights reserved. Source

Nes P.G.,Norwegian University of Science and Technology
Signal Processing | Year: 2012

In this article we suggest a fast multi-scale edge-detection scheme for medical ultrasound signals. The edge-detector is based on well-known properties of the continuous wavelet transform. To achieve both good localization of edges and detect only significant edges, we study the maxima-lines of the wavelet transform. One can obtain the maxima-lines between two scales by computing the wavelet transform at several intermediate scales. To reduce computational effort and time we suggest a time-scale filtering procedure which uses only few scales to connect modulus-maxima across time-scale plane. The design of this procedure is based on a study of maxima-lines corresponding to edges typical for medical ultrasound signals. This study allows us to construct an algorithm for medical ultrasound signals which meets the demand for speed, but not on expense of reliability. The edge-detection algorithm has been applied to a large class of medical ultrasound signals including tumour-, liver- and artery-images. Our results show that the proposed algorithm effectively detects major features in such signals, including edges with low contrast. © 2012 Elsevier B.V. All rights reserved. Source

Giannakos M.N.,Norwegian University of Science and Technology
Computers and Education | Year: 2013

Educational games have enhanced the value of instruction procedures in institutions and business organizations. Factors that increase students' adoption of learning games have been widely studied in past; however, the effect of these factors on learners' performance is yet to be explored. In this study, factors of Enjoyment, Happiness, and Intention to Use were chosen as important attitudes in learning educational games and increasing learning performance. A two-step between group experiment was conducted: the first study compared game-based learning and traditional instruction in order to verify the value of the game. 41 Gymnasium (middle school) students were involved, and the control and experimental groups were formed based on a pretest method. The second study, involving 46 Gymnasium students, empirically evaluates whether and how certain attitudinal factors affect learners' performance. The results of the two-part experiment showed that a) the game demonstrated good performance (as compared to traditional instruction) concerning the gain of knowledge, b) learners' enjoyment of the game has a significant relation with their performance, and c) learners' intention to use and happiness with the game do not have any relation with their performance. Our results suggest that there are attitudinal factors affecting knowledge acquisition gained by a game. © 2013 Elsevier Ltd. All rights reserved.. Source

Eggen T.,Norwegian Institute for Agricultural And Environmental Research Bioforsk | Moeder M.,Helmholtz Center for Environmental Research | Arukwe A.,Norwegian University of Science and Technology
Science of the Total Environment | Year: 2010

Landfills have historically remained the most common methods of organized waste disposal and still remain so in many regions of the world. Thus, they may contain wastes resulting from several decades of disposal and decomposition with subsequent release of organic compounds that may have environmental, wildlife and human health consequences. Products containing different types of additives with unique beneficial improvement properties are in daily use. However, when these products are decomposed, additives are release into the environment, some of which have been shown to have negative environmental impacts, resulting in the ban or at least restricted application of some chemicals. New and emerging compounds are continuously discovered in the environment. Herein, we report qualitative and quantitative data on the occurrence of new and emerging compounds with increasing environmental and public health concern in water- and particle phase of landfill leachates. Under normal environmental conditions, several of these chemicals are persistent high-volume products. Identified chemicals in the leachates at nanogram (ng) or microgram (μg) per liter levels include - chlorinated alkylphosphates such as tris(1-chloro-2-propyl) phosphate (TCPP), N-butyl benzensulfonamide (NBBS), the insect repellent diethyl toluamide (DEET) and personal care products such as the non-steroidal anti-inflammatory drug ibuprofen and polycyclic musk compounds. Among new and emerging contaminants, perfluorinated compounds (PFCs) were measured in the water phase at concentrations up to 6231. ng/L. Compared with the other chemicals, PFCs were primarily distributed in water phase. An effective removal method for PFCs and other polar and persistent compounds from landfill leachates has been a major challenge, since commonly used treatment technologies are based on aeration and sedimentation. Thus, the present study has shown that municipal landfill leachates may represent a significant source of concern for legacy, new and emerging chemicals in groundwater. © 2010 Elsevier B.V. Source

Jelle B.P.,Sintef | Jelle B.P.,Norwegian University of Science and Technology
Energy and Buildings | Year: 2013

The challenge of removing snow downfall on photovoltaic solar cell roofs, also including solar thermal panels and walls, in order to maximize the solar energy efficiency, is investigated. A special emphasis is given on possible research opportunities for the future. As the application of building integrated photovoltaic (BIPV) products is increasing, it is becoming more important to solve this challenge in order to maximize the solar energy harvesting from buildings, e.g. when attempting to reach the goals of zero energy and zero emission buildings. In addition, a solution within this field, may also be utilized in other areas, e.g. for window roofs and traffic signs which are often concealed by snow and ice. Various ideas and possible steps toward a solution of the challenge are discussed, which may then in turn set in motion creative thinking and problem solving paths with new follow-up investigations. Several aspects with snow covering solar panels are treated and discussed, including possible paths toward a working solution, where different material surface solutions like e.g. self-cleaning surfaces with origin in photocatalytic hydrophilic surfaces, superhydrophobic or ultrahydrophobic surfaces and coarse microstructured or nanostructured surfaces are reviewed and treated in particular. Furthermore, this work presents the compilation and discussion of an experimental method for measuring friction between snow/ice and various building roof surfaces. Some results from these experimental investigations are discussed, including a slip angle and a friction coefficient classification system for roofing types and material surfaces with respect to snow and ice. © 2013 Elsevier B.V. All rights reserved. Source

Strandberg R.,Teknova AS | Worren Reenaas T.,Norwegian University of Science and Technology
Progress in Photovoltaics: Research and Applications | Year: 2012

A model based on detailed balance principles is developed to study how the thermalized nature of the electrons in the intermediate band (IB) affects the efficiency of intermediate band solar cells. Published work on intermediate band solar cells with finite IB width has focused on the fundamental case when the absorptivity is assumed to be high for all photon energies above the smallest band gap. In this work, an attempt is made to incorporate variations in the absorptivity due to the thermal distribution of the IB electrons. In a wide IB with a thermalized electron population, there will be a low density of electrons close to the upper band edge. The density of unoccupied electron states close to the lower band edge will also be low. As a consequence, the absorption coefficients for photon energies where the only energetically allowed transitions involve exciting electrons from or to, respectively, such states can be expected to be low. The presented model incorporates the effect of the thermalized electron population in an idealized way. In some cases, the calculated efficiency is well above the limit for single band gap cells, whereas in other cases it is not. It is concluded that absorption coefficients rising rapidly from very low values to higher values are advantageous, that overlap between the absorption coefficients can be beneficial when the IB becomes sufficiently wide, and finally, that a case-by-case study probably is required to evaluate whether a particular IB material can give cells with high efficiency. Copyright © 2011 John Wiley & Sons, Ltd. Source

Am H.,Norwegian University of Science and Technology
Environmental Innovation and Societal Transitions | Year: 2015

This study contributes to transition studies through an empirical analysis of scientists at the Norwegian Research Center for Solar Cell Technology. From a policy perspective, this research centre is a concrete undertaking within transitions politics. How do solar energy scientists make sense of this mission and what strategies do they adopt? The analysis adopts a bottom-up perspective focusing on the politics involved in actor-networks constructing and empowering sustainable innovations. I suggest the micro/macro-divide characterising transition studies may be discarded, if we recognise that actors operate both on niche, regime, and landscape level. Instead of presuming a multi-level perspective, transition studies could analyse the multi-actor politics of translations in arenas of development. Adopting this approach, I argue that solar scientists pursue mainly two lines of activities: improving efficiency (translations to fit and conform) and challenging negative hegemonic representations of solar energy (translations to stretch and transform). © 2015 Elsevier B.V. All rights reserved. Source

Anca-Couce A.,TU Berlin | Zobel N.,TU Berlin | Jakobsen H.A.,Norwegian University of Science and Technology
Fuel | Year: 2013

Modeling fixed-bed thermo-chemical processes of biomass should be considered as a multi-scale problem. The molecular, particle and reactor level should be considered together in the models. A framework for a multi-scale model for dynamic fixed-bed/ moving-bed thermo-chemical conversion processes and the respective numerical solution method is introduced: the Representative Particle Model (RPM). In the RPM approach an intra-particle model is solved for each finite volume element of the reactor. All particles within a finite volume element are assumed to obey the same characteristics as the one for which the intra-particle model is solved, which is why it can be considered as representative. The particle level is then considered, as opposed to quasi-continuous models, that are just appropriate when intra-particle gradients of temperatures and concentrations are negligible. And compared to the Discrete Particle Model (DPM), where a model for each particle in the bed (up to 10 5-106 particles in technical scale fixed-bed gasification) is solved simultaneously with the fluid-phase balances in the reactor domain, the computational effort is significantly smaller. The RPM is applied to fixed-bed pyrolysis and compared to experimental results available in the literature. The RPM is able to predict the experimental results, describing intra-particle gradients, in a much more feasible time compared to the DPM. The importance of intra-particle gradients in fixed-bed pyrolysis is also highlighted, showing differences in the conversion time of more than 30% when the particle size is doubled, from a particle diameter of 1.24-2.48 cm. Therefore the RPM is a feasible way to include the particle level in a multi-scale description of fixed-bed pyrolysis. © 2012 Elsevier Ltd. All rights reserved. Source

Muhammad Fuad M.M.,Norwegian University of Science and Technology
Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) | Year: 2012

Time series data appear in a broad variety of economic, medical, and scientific applications. Because of their high dimensionality, time series data are managed by using representation methods. Symbolic representation has attracted particular attention because of the possibility it offers to benefit from algorithms and techniques of other fields in computer science. The symbolic aggregate approximation method (SAX) is one of the most important symbolic representation techniques of times series data. SAX is based on the assumption of "high Gaussianity" of normalized time series which permits it to use breakpoints obtained from Gaussian lookup tables. The use of these breakpoints is the heart of SAX. In this paper we show that this assumption of Gaussianity oversimplifies the problem and can result in very large errors in time series mining tasks. We present an alternative scheme, based on the genetic algorithms (GASAX), to find the breakpoints. The new scheme does not assume any particular distribution of the data, and it does not require normalizing the data either. We conduct experiments on different datasets and we show that the new scheme clearly outperforms the original scheme. © 2012 Springer-Verlag. Source

Hertwich E.G.,Norwegian University of Science and Technology
Environmental Science and Technology | Year: 2013

The ability of hydropower to contribute to climate change mitigation is sometimes questioned, citing emissions of methane and carbon dioxide resulting from the degradation of biogenic carbon in hydropower reservoirs. These emissions are, however, not always addressed in life cycle assessment, leading to a bias in technology comparisons, and often misunderstood. The objective of this paper is to review and analyze the generation of greenhouse gas emissions from reservoirs for the purpose of technology assessment, relating established emission measurements to power generation. A literature review, data collection, and statistical analysis of methane and CO2 emissions are conducted. In a sample of 82 measurements, methane emissions per kWh hydropower generated are log-normally distributed, ranging from micrograms to 10s of kg. A multivariate regression analysis shows that the reservoir area per kWh electricity is the most important explanatory variable. Methane emissions flux per reservoir area are correlated with the natural net primary production of the area, the age of the power plant, and the inclusion of bubbling emissions in the measurement. Even together, these factors fail to explain most of the variation in the methane flux. The global average emissions from hydropower are estimated to be 85 gCO2/kWh and 3 gCH4/kWh, with a multiplicative uncertainty factor of 2. GHG emissions from hydropower can be largely avoided by ceasing to build hydropower plants with high land use per unit of electricity generated. © 2013 American Chemical Society. Source

Saugstad O.D.,University of Oslo | Aune D.,Norwegian University of Science and Technology | Aune D.,Imperial College London
Neonatology | Year: 2013

Background: The optimal oxygen saturation for extremely low birth weight infants in the postnatal period beyond the delivery room is not known. Objectives: To summarize and discuss the results of the randomized trials, constituting the NEOPROM (Neonatal Oxygenation Prospective Meta-analysis) collaborative study, examining the effect of low versus high functional oxygen saturation targets in the postnatal period in premature infants with gestational age <28 weeks. Methods: A meta-analysis of SUPPORT (Surfactant, Positive Pressure and Pulse Oximetry Randomized Trial), the three BOOST II (Benefits of Oxygen Saturation Targeting) studies and the COT (Canadian Oxygen Trial) was performed including a total of 4,911 infants randomized to either a low (85-89%) or high (91-95%) functional oxygen saturation (SpO2) within the first 24 h after birth. Results: Relative risks (RR; 95% CIs) comparing a low versus a high oxygen saturation target were 1.41 (1.14-1.74) for mortality at discharge or at follow-up, 0.74 (0.59-0.92) for severe retinopathy of prematurity, 0.95 (0.86-1.04) for physiologic bronchopulmonary dysplasia, 1.25 (1.05-1.49) for necrotizing enterocolitis, 1.02 (0.88-1.19) for brain injury, and 1.01 (0.95-1.08) for patent ductus arteriosus. RR >1.0 favors a high oxygen saturation. Conclusions: RRs for mortality and necrotizing enterocolitis are significantly increased and severe retinopathy of prematurity significantly reduced in low compared to high oxygen saturation target infants. There are no differences regarding physiologic bronchopulmonary dysplasia, brain injury or patent ductus arteriosus between the groups. Based on these results, it is suggested that functional SpO2 should be targeted at 90-95% in infants with gestational age <28 weeks until 36 weeks' postmenstrual age. However, there are still several unanswered questions in this field. © 2013 S. Karger AG, Basel. Source

Odegard S.S.,Norwegian University of Science and Technology
The journal of headache and pain | Year: 2010

The aim of the study was to evaluate the association between sleep disturbance and headache type and frequency, in a random sample of participants in the third Nord-Trøndelag Health Survey. The headache diagnoses were set by neurologists using the ICHD-2 criteria performing a semi structured face-to-face interview. Sleep problems were measured by the two validated instruments Karolinska Sleep Questionnaire (KSQ) and Epworth Sleepiness Scale (ESS). Among 297 participants, 77 subjects were headache-free, whereas 135 were diagnosed with tension-type headache (TTH), 51 with migraine, and 34 with other headache diagnoses. In the multivariate analyses, using logistic regression, excessive daytime sleepiness, defined as ESS >or= 10, was three times more likely among migraineurs compared with headache-free individuals (OR = 3.3, 95% CI 1.0-10.2). Severe sleep disturbances, defined as KSQ score in the upper quartile, was five times more likely among migraineurs (OR = 5.4, 95% CI 2.0-15.5), and three times more likely for subjects with TTH (OR = 3.3, 1.4-7.3) compared with headache-free individuals. Subjects with chronic headache were 17 times more likely to have severe sleep disturbances (OR = 17.4, 95% CI 5.1-59.8), and the association was somewhat stronger for chronic migraine (OR = 38.9, 95% CI 3.1-485.3) than for chronic TTH (OR = 18.3, 95% CI 3.6-93.0). In conclusion, there was a significant association between severe sleep disturbances and primary headache disorders, most pronounced for those with chronic headache. Even though one cannot address causality in the present study design, the results indicate an increased awareness of sleep problems among patients with headache. Source

Buhaug H.,Peace Research Institute Oslo PRIO | Buhaug H.,Norwegian University of Science and Technology | Urdal H.,Peace Research Institute Oslo PRIO
Global Environmental Change | Year: 2013

For the first time in history, the majority of the world population now lives in cities. Global urbanization will continue at high speed; the world's urban population is projected to increase by more than 3 billion people between 2010 and 2050. Some of this increase will be the result of high urban fertility rates and reclassification of rural land into urban areas, but a significant portion of future urbanization will be caused by rural-to-urban migration. This migration is expected to be particularly prevalent in countries and regions most affected by the changing climate. While urban populations generally enjoy a higher quality of life, many cities in the developing world have large slums with populations that are largely excluded from access to resources, jobs, and public services. In the environmental security literature, great rural resource scarcity, causing rural to urban migration, is seen as an important source of violent conflict. This study investigates how population growth affects patterns of public unrest in urban centers within the context of crucial intervening factors like democracy, poverty, economic shocks. It utilizes a newly collected event dataset of urban social disturbance covering 55 major cities in Asia and Sub-Saharan Africa since 1960. The empirical analysis provides little support for the notion that high and increasing urban population pressure leads to a higher risk or frequency of social disorder. Instead, we find that urban disorder is primarily associated with a lack of consistent political institutions, economic shocks, and ongoing civil conflict. © 2012 Elsevier Ltd. Source

Nilsen B.,Norwegian University of Science and Technology
Rock Mechanics and Rock Engineering | Year: 2014

Water ingress represents one of the main challenges in subsea tunnelling, particularly when this occurs in sections with poor rock mass quality. This paper is discussing the main characteristics of water ingress in subsea hard rock tunnels based on the experience from almost 50 such tunnels that have been built in Norway. Following a brief description of the geological conditions and the basic design of the subsea tunnels, pre-construction investigations and investigations during excavation are discussed with particular emphasis on prediction of water ingress. Two cases with particularly difficult conditions; the Bjorøy tunnel and the Atlantic Ocean tunnel, are discussed in detail. In these cases, large water inflow with pressure of up to 2.4 MPa was encountered at major faults/weakness zones during excavation, and special procedures were required to cope with the problems. Based on the experience from the Norwegian projects, it is concluded that continuous follow-up by experienced engineering geologists, probe drilling with the drilling jumbo and pre-grouting where required are the most important factors for coping with water ingress and ensuring stability. © 2012 Springer-Verlag. Source

Nossum A.S.,Norwegian University of Science and Technology
Cartography and Geographic Information Science | Year: 2011

Efforts within cartography on indoor maps have previously not received a lot of attention. Work that has been carried out on indoor maps often focus on map design very similar to an architectural style (Klippel et al. 2006; Ciavarella and Paternò 2004). In some cases the design has been of a more novel character where approaches with augmented and virtual realities have been carried out (Radoczky 2007; Müller et al. 2006). Common to these approaches is the depiction of one floor per map. As well, the primary user task is often solely personal navigation. In this article I present an innovative approach to indoor maps. The design is directly inspired by underground tube maps first developed by Harry Beck (Garland 1994) and today a common design for public transport maps. The main advantages of the map design are its simplicity and the possibility of including all floors in one map \iew. This allows the map user to easier comprehend the structure of the building without using several maps, as commonly needed with today's indoor map designs. I present several different map styles each intended to satisfy different user groups and tasks depending on the user's familiarity with the environment. In addition the article motivate for new application areas suitable for indoor maps, especially large hospitals. I hypothesize that the design proposed in this article leans very well to displaying real-time dynamic geospatial information, such as patients, staff, equipment and room availability within hospitals. Due to the early phase of the work presented here I outline the needed further work and possibilities of technological platforms as well as evaluations necessary in order for the design to gain acceptance and success. Source

Lindgren F.,University of Bath | Rue H.,Norwegian University of Science and Technology
Journal of Statistical Software | Year: 2015

The principles behind the interface to continuous domain spatial models in the R-INLA software package for R are described. The integrated nested Laplace approximation (INLA) approach proposed by Rue, Martino, and Chopin (2009) is a computationally effective alternative to MCMC for Bayesian inference. INLA is designed for latent Gaussian models, a very wide and exible class of models ranging from (generalized) linear mixed to spatial and spatio-temporal models. Combined with the stochastic partial differential equation approach (SPDE, Lindgren, Rue, and Lindström 2011), one can accommodate all kinds of geographically referenced data, including areal and geostatistical ones, as well as spatial point process data. The implementation interface covers stationary spatial models, non-stationary spatial models, and also spatio-temporal models, and is applicable in epidemiology, ecology, environmental risk assessment, as well as general geostatistics. Source

Vaa Z.,Czech Technical University | Preisig H.A.,Norwegian University of Science and Technology
Systems and Control Letters | Year: 2012

Model identification plays a central role in any activity associated with process operations. With control being done on different levels, different models are required for the same plant, each for a different range of dynamics. Besides that most identification methods apply to the linear models, they also do not allow for selecting a frequency range. Wavelet-based methods have the intrinsic ability to select time and frequency windows, and, to some extent, are also applicable to non-linear processes. The paper presents an approach, in which the wavelet transform is employed for system identification enabling the selection of the particular frequency range of interest. We will show the use of some wavelet filters with a property of superior selectivity in the frequency domain and having compact support in the time domain, which, in turn, influences an accurate implementation. These properties provide us with a possibility of the measured data analysis in the frequency domain without any loss of information. Selection of a proper filter allows us to identify the system on a desired frequency range, or to identify a number of systems for distinct frequency ranges. This is specifically convenient for the systems with dominant modes, such as singularly perturbed systems. The possibility of selection of the specific frequency range can be utilized for application-based identification such as control, when only a limited frequency range is required. We conclude with a case study, where the proposed algorithms are tested and results are presented. © 2012 Elsevier B.V. All rights reserved. Source

Linde M.,Norwegian University of Science and Technology
Cephalalgia : an international journal of headache | Year: 2011

Preliminary reports regarding injections in the neck of onabotulinum toxin A have been positive in cervicogenic headache (CeH). The aim was to perform the first methodologically rigorous trial. A randomised, placebo-controlled, patient-, injector- and evaluator-blinded crossover study included 28 adult patients with a long-standing and treatment-resistant CeH. After a baseline period, injections of either onabotulinum toxin A or placebo were given in fixed sites in the neck muscles on the pain side. Second injections were given after ≥8 weeks. Patients were thereafter followed for another 8 weeks. A detailed headache calendar was filled in, and patients were followed with quality-of-life (QoL) questionnaires, algometry and neck mobility measurements. There was no significant difference between verum and placebo in a mixed linear model analysis (p=0.084) with regard to the primary end-point, reduction of days with moderate to severe headache. Six patients withdrew from the study before the second injections, but an intention-to-treat (ITT) analysis gave a similar result (p=0.27). There were no significant differences favouring verum in any of the secondary efficacy measures. Side-effects of onabotulinum toxin A were minor and short-lasting. Onabotulinum toxin A in neck muscles does not seem to be beneficial in CeH. Source

Raiborg C.,University of Oslo | Wenzel E.M.,University of Oslo | Stenmark H.,University of Oslo | Stenmark H.,Norwegian University of Science and Technology
EMBO Journal | Year: 2015

Recent studies have revealed the existence of numerous contact sites between the endoplasmic reticulum (ER) and endosomes in mammalian cells. Such contacts increase during endosome maturation and play key roles in cholesterol transfer, endosome positioning, receptor dephosphorylation, and endosome fission. At least 7 distinct contact sites between the ER and endosomes have been identified to date, which have diverse molecular compositions. Common to these contact sites is that they impose a close apposition between the ER and endosome membranes, which excludes membrane fusion while allowing the flow of molecular signals between the two membranes, in the form of enzymatic modifications, or ion, lipid, or protein transfer. Thus, ER-endosome contact sites ensure coordination of molecular activities between the two compartments while keeping their general compositions intact. Here, we review the molecular architectures and cellular functions of known ER-endosome contact sites and discuss their implications for human health. Membrane contact sites, defined as sites of close apposition between two membranes, are crucial for the direct exchange of information between distinct endomembrane compartments. This review highlights the diverse functions of ER-endosome contact sites. © 2015 The Authors. Source

Fomel S.,University of Texas at Austin | Stovas A.,Norwegian University of Science and Technology
Geophysics | Year: 2010

Reflection moveout approximations are commonly used for velocity analysis, stacking, and time migration. A novel functional form for approximating the moveout of reflection traveltimes at large offsets is introduced. In comparison with the classic hyperbolic approximation, which uses only two parameters (zero-offset time and moveout velocity), this form involves five parameters that can be determined, in a known medium, from zero-offset computations and from tracing one nonzero-offset ray. It is called a generalized approximation because it reduces to some known three-parameter forms with a particular choice of coefficients. By testing the accuracy of the proposed approximation with analytical and numerical examples, the new approximation is shown to bring an improvement in accuracy of several orders of magnitude compared to known analytical approximations, which makes it as good as exact for many practical purposes. © 2010 Society of Exploration Geophysicists. Source

Andreassen T.,Norwegian University of Science and Technology
Medicine, Health Care and Philosophy | Year: 2015

Patents on biotech products have a scope that goes well beyond what is covered by the most widely applied ethical justifications of intellectual property. Neither natural rights theory from Locke, nor public interest theory of IP rights justifies the wide scope of legal protection. The article takes human genes as an example, focusing on the component that is not invented but persists as unaltered gene information even in the synthetically produced complementary DNA, the cDNA. It is argued that patent on cDNA holds this information captive, or illegitimately appropriates it in limiting other researchers and inventors’ opportunity to explore new functions and uses based on this non-invented information. A tighter connection between legal IP protection and the use description stated in the patent claim is suggested. By binding protection to the product’s foreseeable functions and use, instead of the product itself and all future uses of it, legitimacy of biotech product patents is restored. © 2015, Springer Science+Business Media Dordrecht. Source

Tran K.-Q.,Norwegian University of Science and Technology
Bioresource Technology | Year: 2016

Hydrothermal liquefaction (HTL) is a promising technology for converting wet plant biomass directly to liquid fuels and chemicals. However, some aspects of the technology are not fully understood and still disputed. The reactor material constraints and difficulties coupled with the formation of unwanted products are the main challenges limiting the applications of the technology. In addition, heat and mass transfer limitations in the reaction system result in a lower conversion efficiency and selectivity, of which the later would make it difficult and expensive for products separation, purification, and/or modification of the products. This paper discusses the challenges and current status of possible solutions to the challenges, focusing on the need of developing a special plug-flow reactor for scaling up of the HTL process. © 2016 Elsevier Ltd. Source

Houle D.,Florida State University | Pelabon C.,Norwegian University of Science and Technology | Wagner G.P.,Yale University | Hansen T.F.,University of Oslo
Quarterly Review of Biology | Year: 2011

Measurement-the assignment of numbers to attributes of the natural world-is central to all scientific inference. Measurement theory concerns the relationship between measurements and reality; its goal is ensuring that inferences about measurements reflect the underlying reality we intend to represent. The key principle of measurement theory is that theoretical context, the rationale for collecting measurements, is essential to defining appropriate measurements and interpreting their values. Theoretical context determines the scale type of measurements and which transformations of those measurements can be made without compromising their meaningfulness. Despite this central role, measurement theory is almost unknown in biology, and its principles are frequently violated. In this review, we present the basic ideas of measurement theory and show how it applies to theoretical as well as empirical work. We then consider examples of empirical and theoretical evolutionary studies whose meaningfulness have been compromised by violations of measurement-theoretic principles. Common errors include not paying attention to theoretical context, inappropriate transformations of data, and inadequate reporting of units, effect sizes, or estimation error. The frequency of such violations reveals the importance of raising awareness of measurement theory among biologists. © 2011 by The University of Chicago Press. Source

Joodaki G.,Norwegian University of Science and Technology | Wahr J.,University of Colorado at Boulder | Swenson S.,U.S. National Center for Atmospheric Research
Water Resources Research | Year: 2014

Data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission are used to estimate monthly changes in total water storage across the Middle East during February 2003 to December 2012. The results show a large negative trend in total water storage centered over western Iran and eastern Iraq. Subtracting contributions from the Caspian Sea and two large lakes, Tharthar and Urmiah, and using output from a version of the CLM4.5 land surface model to remove contributions from soil moisture, snow, canopy storage, and river storage, we conclude that most of the long-term water loss is due to a decline in groundwater storage. By dividing the region into seven mascons outlined along national boundaries and fitting them to the data, we find that the largest groundwater depletion is occurring in Iran, with a mass loss rate of 25 ± 3 Gt/yr during the study period. The conclusion of significant Iranian groundwater loss is further supported by in situ well data from across the country. Anthropogenic contributions to the groundwater loss are estimated by removing the natural variations in groundwater predicted by CLM4.5. These results indicate that over half of the groundwater loss in Iran (14 ± 3 Gt/yr) may be attributed to human withdrawals. © 2014. American Geophysical Union. All Rights Reserved. Source

Jacobsen M.G.,ABB | Skogestad S.,Norwegian University of Science and Technology
Journal of Natural Gas Science and Engineering | Year: 2013

Optimal operation of liquefaction processes is little studied in the open literature. In particular, the issue of how optimal operation changes with disturbances has received very little attention. This paper addresses optimal operation of a simple natural gas liquefaction process - the PRICO process. The focus is on how the active process constraints change with disturbances. It is shown that the feasible part of the disturbance space can be divided into five regions with different sets of active constraints. We also suggest control structures for the process, and find that as little as two control structures may be needed despite of the fact that there are five regions. It is suggested to use compressor speed to control the margin to surge at minimum, and to keep the turbine outlet stream at saturation at all times. © 2012 Elsevier B.V. Source

Ubolli A.,Norwegian University of Science and Technology | Gustavsen B.,Sintef
IEEE Transactions on Power Delivery | Year: 2012

This paper presents a multiport implementation of the time-domain-vector- fitting algorithm (TD-VF) for achieving a common-pole rational model approximation from simulated time-domain responses. Similar to the frequency-domain counterpart of the algorithm, a fast realization of TD-VF is achieved based on QR-factorization with consideration of sparsity. The computational speed is further increased by an adaptive downsampling procedure which removes rows from the system matrices. The required model order is reduced by low-pass filtering the input responses, giving a model that is essentially free of spurious Gibbs-like oscillations. The resulting model is directly compatible with Electromagnetic Transients Program-type simulation programs. The multiport TD-VF is applied for the calculation of a frequency-dependent network equivalent (FDNE) of two subnetworks: a 24-kV distribution system and a 145-kV regional transmission system. We show that the procedure offers advantages by achieving faster simulations and reduced memory requirements. In addition, the procedure often enables the use of a shorter time-step length than with the detailed subnetwork representation, thereby achieving further reductions in computational time. © 2012 IEEE. Source

Karimirad M.,Norwegian University of Science and Technology
Renewable Energy | Year: 2013

This paper deals with the numerical modeling of a catenary moored spar-type wind turbine in the integrated coupled analyses. The current spar-type wind turbine is inspired by the Hywind concept. In this paper, different hydrodynamic models based on the Morison formula, Pressure integration method and Panel method considering the mean drift, first and second order forces are studied. A floating wind turbine in deep water depth supporting a 5-MW turbine system is considered. Simo-Riflex (DeepC), HAWC2 and FAST codes are used to carry out the coupled wave-wind-induced analyses. The results show that the damping and inertia forces of the mooring lines are important for the tension responses; especially, the damping of the mooring lines can help to damp-out the high-frequency elastic-deformations of the mooring system. However, the motion responses are not significantly affected by the mooring line damping-effects. The drift and second order forces do not significantly affect the motion and tension responses. However, the heave motion is more affected by the drift and second order forces. The results indicate that either the Morison formula considering the instantaneous position of the structure or first order hydrodynamic forces based on the Panel method and considering the quadratic viscous forces can provide accurate results for the slender spar-type wind turbines. Considering the second order forces is found to be 10-15 times more time consuming while the responses are not significantly affected for the present floating wind turbine. The coupled aero-hydro-servo-elastic code-to-code comparison of HAWC2 and FAST codes shows that the dynamic motion responses, structural responses at the tower-spar interface and at the blade root as well as the power production are in good agreement. © 2012 Elsevier Ltd. Source

Merz K.O.,Norwegian University of Science and Technology
Wind Energy | Year: 2015

A fast and effective loads analysis method was developed for the preliminary design of stall-regulated blades. Calculations are conducted in the frequency domain, including a three-dimensional representation of turbulence, for a rapid evaluation of lifetime loads. The structural model is simplified, consisting of a single flexible blade on a rigid drivetrain. Load cases are defined which consider ultimate, extreme operating (with and without tip brake deployment), and lifetime fatigue loads. It is shown, by comparison with time-domain simulations, that the load cases provide a reasonable estimate of design-driving loads. The method described in Part 1 of this article forms the basis for a novel optimization method in Part 2. Copyright © 2014 John Wiley & Sons, Ltd. Source

Friberg S.E.,Norwegian University of Science and Technology
Journal of Colloid and Interface Science | Year: 2014

The potential for a catastrophic inversion of one phase in a Janus emulsion drop was investigated by local equilibrium calculations of a single Janus drop of two mutually insoluble oils, O1 and O2, in an infinite aqueous continuous phase, (O1. +. O2)/W. The relative volume of the oil with less interfacial tension towards water, O2, was increased, while the radius of the O1 part of the drop was held constant at unity. The limiting fraction of O1 covered by O2 was calculated for infinite O2 volume for a selected interfacial tension combination. After the O2 volume reached infinity, the volume of the continuous aqueous phase was reduced to finite values, leading to a selective inversion of the emulsion from (O1. +. O2)/W to (W. +. O1)/O2. Thenceforward, further removal of the water led to an additional reduction of the size and radius of the water cap. © 2013 Elsevier Inc. Source

Nydal O.J.,Norwegian University of Science and Technology
Energy and Fuels | Year: 2012

Transport of oil and gas mixtures in pipelines involves flow dynamics on a wide range of time and length scales. Liquid slugs and waves occur at scales extending from diameters ("hydrodynamic slug flow") and up to riser lengths ("severe slugging"). The approach in one-dimensional dynamic multiphase flow models for analysis of flow dynamics depends upon the scale to be resolved. Types of models are discussed, and a hybrid two-fluid model and a slug tracking model are in particular described. A two-fluid model is applied on a stationary grid in the gas-liquid stratified flow region until a slug is formed (or initiated), when a slug tracking method with a moving grid takes over. The performance of the model is demonstrated in relation to three types of cases with different time and length scales: Two- and three-phase severe slugging, hydrodynamic slugging after a bend, and a pigging case to simulate the rapid release of a hydrate plug. The computations are compared to experimental laboratory data. © 2012 American Chemical Society. Source

Miwa J.A.,University of Aarhus | Hofmann P.,University of Aarhus | Simmons M.Y.,University of New South Wales | Wells J.W.,Norwegian University of Science and Technology
Physical Review Letters | Year: 2013

We directly measure the band structure of a buried two dimensional electron gas (2DEG) using angle resolved photoemission spectroscopy. The buried 2DEG forms 2 nm beneath the surface of p-type silicon, because of a dense delta-type layer of phosphorus n-type dopants which have been placed there. The position of the phosphorous layer is beyond the probing depth of the photoemission experiment but the observation of the 2DEG is nevertheless possible at certain photon energies where emission from the states is resonantly enhanced. This permits direct access to the band structure of the 2DEG and its temperature dependence. © 2013 American Physical Society. Source

Krebs T.S.,Norwegian University of Science and Technology
PloS one | Year: 2013

The classical serotonergic psychedelics LSD, psilocybin, mescaline are not known to cause brain damage and are regarded as non-addictive. Clinical studies do not suggest that psychedelics cause long-term mental health problems. Psychedelics have been used in the Americas for thousands of years. Over 30 million people currently living in the US have used LSD, psilocybin, or mescaline. To evaluate the association between the lifetime use of psychedelics and current mental health in the adult population. Data drawn from years 2001 to 2004 of the National Survey on Drug Use and Health consisted of 130,152 respondents, randomly selected to be representative of the adult population in the United States. Standardized screening measures for past year mental health included serious psychological distress (K6 scale), mental health treatment (inpatient, outpatient, medication, needed but did not receive), symptoms of eight psychiatric disorders (panic disorder, major depressive episode, mania, social phobia, general anxiety disorder, agoraphobia, posttraumatic stress disorder, and non-affective psychosis), and seven specific symptoms of non-affective psychosis. We calculated weighted odds ratios by multivariate logistic regression controlling for a range of sociodemographic variables, use of illicit drugs, risk taking behavior, and exposure to traumatic events. 21,967 respondents (13.4% weighted) reported lifetime psychedelic use. There were no significant associations between lifetime use of any psychedelics, lifetime use of specific psychedelics (LSD, psilocybin, mescaline, peyote), or past year use of LSD and increased rate of any of the mental health outcomes. Rather, in several cases psychedelic use was associated with lower rate of mental health problems. We did not find use of psychedelics to be an independent risk factor for mental health problems. Source

Phattaranawik J.,SCG Chemicals Co. | Leiknes T.,Norwegian University of Science and Technology
Water Research | Year: 2011

Non-biodegradable solid wastes of non-intact membrane fibres/flatsheets and modules disposed from membrane bioreactor (MBR) plants are in a great concern for environmental impact. Estimated cumulative amount of the module solid wastes from European countries in the next five years should be larger than 1000 tons in which a proper management strategy and reuse for the disposed solid waste are urgently required. This article was aimed to propose an alternative to make uses of the non-intact membrane fibres for the aerobic biofilm supports and to study the feasibility on process operation of novel moving-fiber biofilm MBR. A system of moving-fiber biofilm membrane bioreactor was designed and evaluated experimentally, including an upflow anaerobic sludge reactor, an aerobic moving-fiber biofilm reactor, and a submerged membrane filtration unit. Start-up method and operating conditions to control the biofilms growing on the moving fibers were investigated. Organic removal rates, optimum operating conditions for the system, and membrane fouling rates at various membrane aeration rates and permeate fluxes were monitored to evaluate the performance of the proposed BF-MBR process. © 2011 Elsevier Ltd. Source

Zhang S.J.,Norwegian University of Science and Technology
Philosophical transactions of the Royal Society of London. Series B, Biological sciences | Year: 2014

The mammalian space circuit is known to contain several functionally specialized cell types, such as place cells in the hippocampus and grid cells, head-direction cells and border cells in the medial entorhinal cortex (MEC). The interaction between the entorhinal and hippocampal spatial representations is poorly understood, however. We have developed an optogenetic strategy to identify functionally defined cell types in the MEC that project directly to the hippocampus. By expressing channelrhodopsin-2 (ChR2) selectively in the hippocampus-projecting subset of entorhinal projection neurons, we were able to use light-evoked discharge as an instrument to determine whether specific entorhinal cell groups--such as grid cells, border cells and head-direction cells--have direct hippocampal projections. Photoinduced firing was observed at fixed minimal latencies in all functional cell categories, with grid cells as the most abundant hippocampus-projecting spatial cell type. We discuss how photoexcitation experiments can be used to distinguish the subset of hippocampus-projecting entorhinal neurons from neurons that are activated indirectly through the network. The functional breadth of entorhinal input implied by this analysis opens up the potential for rich dynamic interactions between place cells in the hippocampus and different functional cell types in the entorhinal cortex (EC). Source

Fossoy F.,Norwegian University of Science and Technology
PloS one | Year: 2012

Sex allocation theory and empirical evidence both suggest that natural selection should favour maternal control of offspring sex ratio in relation to their ability to invest in the offspring. Generalist parasites constitute a particularly interesting group to test this theory as different females commonly utilize different host species showing large variation in provisioning ability. The common cuckoo (Cuculus canorus) is a generalist brood parasite that lays its eggs in the nest of many different passerine birds, but each female tends to specialize on one particular host species giving rise to highly specialized host races. The different host species show large variation in their ability to invest in the parasitic offspring, presenting an opportunity for female cuckoos to bias offspring sex ratio in relation to host species quality. Here, we investigate host-race specific sex allocation controlling for maternal identity in the common cuckoo. We found no evidence of any significant relationship between host race and sex ratio in one sympatric population harbouring three different host races, or in a total of five geographically separated populations. There was also no significant association between host quality, as determined by species-specific female host body mass, and cuckoo sex ratio. Finally, we found no significant relationship between individual cuckoo maternal quality, as determined by her egg volume, and sex ratio within each host race. We conclude that the generalist brood-parasitic common cuckoo show no significant sex-ratio bias in relation to host race and discuss this finding in light of gene flow and host adaptations. Source

Hoverstad B.A.,Norwegian University of Science and Technology
Artificial Life | Year: 2011

We study the selective advantage of modularity in artificially evolved networks. Modularity abounds in complex systems in the real world. However, experimental evidence for the selective advantage of network modularity has been elusive unless it has been supported or mandated by the genetic representation. The evolutionary origin of modularity is thus still debated: whether networks are modular because of the process that created them, or the process has evolved to produce modular networks. It is commonly argued that network modularity is beneficial under noisy conditions, but experimental support for this is still very limited. In this article, we evolve nonlinear artificial neural network classifiers for a binary classification task with a modular structure. When noise is added to the edge weights of the networks, modular network topologies evolve, even without representational support. © 2011 Massachusetts Institute of Technology. Source

Navid A.,Lawrence Livermore National Laboratory | Almaas E.,Norwegian University of Science and Technology
BMC Systems Biology | Year: 2012

Background: Constraint-based computational approaches, such as flux balance analysis (FBA), have proven successful in modeling genome-level metabolic behavior for conditions where a set of simple cellular objectives can be clearly articulated. Recently, the necessity to expand the current range of constraint-based methods to incorporate high-throughput experimental data has been acknowledged by the proposal of several methods. However, these methods have rarely been used to address cellular metabolic responses to some relevant perturbations such as antimicrobial or temperature-induced stress. Here, we present a new method for combining gene-expression data with FBA (GX-FBA) that allows modeling of genome-level metabolic response to a broad range of environmental perturbations within a constraint-based framework. The method uses mRNA expression data to guide hierarchical regulation of cellular metabolism subject to the interconnectivity of the metabolic network.Results: We applied GX-FBA to a genome-scale model of metabolism in the gram negative bacterium Yersinia pestis and analyzed its metabolic response to (i) variations in temperature known to induce virulence, and (ii) antibiotic stress. Without imposition of any a priori behavioral constraints, our results show strong agreement with reported phenotypes. Our analyses also lead to novel insights into how Y. pestis uses metabolic adjustments to counter different forms of stress.Conclusions: Comparisons of GX-FBA predicted metabolic states with fluxomic measurements and different reported post-stress phenotypes suggest that mass conservation constraints and network connectivity can be an effective representative of metabolic flux regulation in constraint-based models. We believe that our approach will be of aid in the in silico evaluation of cellular goals under different conditions and can be used for a variety of analyses such as identification of potential drug targets and their action. © 2012 Navid and Almaas; licensee BioMed Central Ltd. Source

Aanensen N.S.,Norwegian University of Science and Technology
IEEE Transactions on Power Delivery | Year: 2015

Replacing SF6 with air as the arc quenching medium in switching equipment is favorable from an environmental point of view, but may be technically difficult for compact devices. Medium-voltage load break switches have modest current and voltage ratings, typically 630 A/24 kV, and are thus expected to be an earlier application area for air-filled devices than, for example, high-voltage circuit breakers. It is still necessary to understand how the various design parameters affect the interrupting capability. The influence of the air-flow parameters has been investigated through 970 interruption tests with three different contact and nozzle sizes and at three different load currents. The effect of increased air-flow rate versus reduced upstream pressure and air velocity is examined. By increasing the contact and nozzle sizes, lower upstream pressure is required to interrupt the current. According to simple cold gas-flow calculations, increased volume flow rate can, to a certain degree, compensate for reduced air velocity. © 2014 IEEE. Source

Baden M.P.,Center for Quantum Technologies | Arnold K.J.,Center for Quantum Technologies | Grimsmo A.L.,Norwegian University of Science and Technology | Parkins S.,University of Auckland | And 2 more authors.
Physical Review Letters | Year: 2014

We realize an open version of the Dicke model by coupling two hyperfine ground states using two cavity-assisted Raman transitions. The interaction due to only one of the couplings is described by the Tavis-Cummings model and we observe a normal mode splitting in the transmission around the dispersively shifted cavity. With both couplings present the dynamics are described by the Dicke model and we measure the onset of superradiant scattering into the cavity above a critical coupling strength. © 2014 American Physical Society. Source

Lovstad A.,Norwegian University of Science and Technology | Cawley P.,Imperial College London
NDT and E International | Year: 2012

Localised corrosion is a major problem in the oil and gas industry, and is difficult to detect using conventional inspection methods. This paper studies the reflection coefficient (RC) from pit clusters using the fundamental torsional guided wave. The clusters consist of a random number of pits that have developed randomly in size and depth following certain growth rules. The relationship between maximum pit depth and maximum RC is assessed for a large number clusters. Problematic cases where low maximum RCs are obtained from pit clusters with deep maximum pit depth are investigated in detail. Results show that the majority of such clusters consist of a single small and deep pit, with otherwise shallow attack only; such corrosion morphologies are unlikely to occur in practice. With more realistic pit cluster morphologies, where the pit clusters are part of a larger, wider corrosion attack, fewer cases with deep maximum pit depth result in a low maximum RC. The main findings are validated experimentally. © 2011 Elsevier Ltd. All rights reserved. Source

Jelle B.P.,Sintef | Jelle B.P.,Norwegian University of Science and Technology
Solar Energy Materials and Solar Cells | Year: 2013

Window panes, glass structures and electrochromic windows in buildings may be characterised by a number of solar radiation glazing factors, i.e. ultraviolet solar transmittance, visible solar transmittance, solar transmittance, solar material protection factor, solar skin protection factor, external visible solar reflectance, internal visible solar reflectance, solar reflectance, solar absorbance, emissivity, solar factor and colour rendering factor. Comparison of these solar quantities for different glass fabrications enables one to evaluate and thus select the most appropriate glass material or system for the specific buildings and applications. Measurements and calculations were carried out on various glass materials, including three electrochromic window devices, and several two-layer and three-layer window pane configurations. © 2013 Elsevier B.V. Source

Engstrom M.,Norwegian University of Science and Technology
The journal of headache and pain | Year: 2013

The mechanisms associating sleep and migraine are unknown. No previous polysomnographic (PSG) or pain-threshold (PT) study has compared patients with sleep-related migraine attacks (SM), non-sleep related migraine attacks (NSM) and healthy controls. We have performed a blinded, prospective exploratory study with case-control design. Thirty-four healthy controls, 15 patients with SM and 18 patients with NSM had interictal PSG heat-, cold- and pressure PT (HPT, CPT, PPT) recordings and completed diary- and questionnaire on sleep and headache related aspects. NSM patients had more slow-wave sleep (SWS) and more K-bursts than SM patients (K-bursts: p = 0.023 and SWS: p = 0.030) and controls (K-bursts: p = 0.009 and SWS: 0.041). NSM patients also had lower HPT and CPT than controls (p = 0.026 and p = 0.021). In addition, SM patients had more awakenings and less D-bursts than controls (p = 0.025 and p = 0.041). SM- and NSM patients differed in objective-, but not subjective sleep quality. NSM patients had PSG findings indicating foregoing sleep deprivation. As foregoing sleep times were normal, a relative sleep deficit might explain reduced PT among NSM patients. The SM patients had signs of slightly disturbed sleep. Source

Utne I.B.,Norwegian University of Science and Technology
Journal of Quality in Maintenance Engineering | Year: 2010

Purpose - The objective of this paper is to outline a framework that guides the development of sound maintenance strategies and policies for deep-sea offshore wind turbines. Design/methodology/approach - An important challenge with offshore wind energy production is to reduce the high operation and maintenance costs. To decrease complexity, and structure the maintenance strategy developing process, systems engineering principles are used. Findings - The framework facilitates integration of fragmented but valuable information from different disciplines in the development of sound maintenance strategies. In addition, the framework may be used to identify knowledge gaps, and areas for further research. Research limitations/implications - The paper refers to research on deep-sea offshore wind turbines, which is in its infancy, with a limited amount of data yet available for verification and validation. Deep-sea offshore installations are not commercialized, and few pilot installations have been installed. Originality/value - The design of the offshore wind turbines determines operation and maintenance features. Reducing operation and maintenance costs is necessary to make deep-sea offshore wind projects viable in the first place. The framework contributes to the complicated development of maintenance strategies for a system not yet realized. © Emerald Group Publishing Limited. Source

Bailey J.,Norwegian University of Science and Technology
Marine Policy | Year: 2016

This article explores whether the "Grand Strategy" (GS) approach is useful in the field of fisheries management. GS is derived from the study of warfare and its advocates argue that its lessons can be applied to a wide variety of fields and institutions. This article presents and evaluates the usefulness to fisheries management of five principles recommended by the Yale Grand Strategy program for application in the field of Global Health: (1) start with the ends in mind; (2) take an ecological approach; (3) recognize that tactics matter; (4) use positive deviance to characterize practical solutions and foster scale-up and (5) understand the importance of integrating timely intelligence. It adds a sixth principle, suggested by the literature that prompted the GS approach: always anticipate friction. It argues that while many of the principles offered by the GS approach have long been recognized in fisheries management and closely related fields, GS offers support for these and some new insights. Central among these is the importance of clear policy goals and the lack of natural harmony at various levels of action. The weakness of the GS approach is a lack of recognition of the political difficulties involved in adopting a Grand Strategy. © 2015 Published by Elsevier Ltd. Source

Tsatsaronis G.,Norwegian University of Science and Technology | Varlamis I.,Harokopio University | Vazirgiannis M.,Athens University of Economics and Business
Journal of Artificial Intelligence Research | Year: 2010

The computation of relatedness between two fragments of text in an automated manner requires taking into account a wide range of factors pertaining to the meaning the two fragments convey, and the pairwise relations between their words. Without doubt, a measure of relatedness between text segments must take into account both the lexical and the semantic relatedness between words. Such a measure that captures well both aspects of text relatedness may help in many tasks, such as text retrieval, classification and clustering. In this paper we present a new approach for measuring the semantic relatedness between words based on their implicit semantic links. The approach exploits only a word thesaurus in order to devise implicit semantic links between words. Based on this approach, we introduce Omiotis, a new measure of semantic relatedness between texts which capitalizes on the word-to-word semantic relatedness measure (SR) and extends it to measure the relatedness between texts. We gradually validate our method: we first evaluate the performance of the semantic relatedness measure between individual words, covering word-to-word similarity and relatedness, synonym identification and word analogy; then, we proceed with evaluating the performance of our method in measuring text-to-text semantic relatedness in two tasks, namely sentence-to-sentence similarity and paraphrase recognition. Experimental evaluation shows that the proposed method outperforms every lexicon-based method of semantic relatedness in the selected tasks and the used data sets, and competes well against corpus-based and hybrid approaches. © 2010 AI Access Foundation. All rights reserved. Source

Svanaes D.,Norwegian University of Science and Technology
ACM Transactions on Computer-Human Interaction | Year: 2013

In 2001, Paul Dourish proposed the term embodied interaction to describe a new paradigm for interaction design that focuses on the physical, bodily, and social aspects of our interaction with digital technology. Dourish used Merleau-Ponty's phenomenology of perception as the theoretical basis for his discussion of the bodily nature of embodied interaction. This article extends Dourish's work to introduce the human-computer interaction community to ideas related to Merleau-Ponty's concept of the lived body. It also provides a detailed analysis of two related topics: (1) embodied perception: the active and embodied nature of perception, including the body's ability to extent its sensory apparatus through digital technology; and (2) kinaesthetic creativity: the body's ability to relate in a direct and creative fashion with the "feel" dimension of interactive products during the design process. © 2013 ACM. Source

Sletvold N.,Norwegian University of Science and Technology | Gren J.A.,Uppsala University
Ecology | Year: 2011

Pollinators may mediate selection on traits affecting pollinator attraction and effectiveness, and while nonadditive effects of traits influencing the two components of pollination success are expected when seed production is pollen limited, they have been little studied. In a factorial design, we manipulated one putative attraction trait (number of flowers) and one putative efficiency trait (spur length) previously shown to be subject to pollinatormediated selection in the deceptive orchid Dactylorhiza lapponica. Removal of half of the flowers reduced pollen removal, proportion of flowers receiving pollen, fruit set, and fruit mass compared to unmanipulated plants, while spur-tip removal increased fruit set and fruit mass but did not affect pollen removal or proportion of flowers receiving pollen. The effect of spurtip removal on fruit mass was stronger among plants with intact number of flowers compared to plants with experimentally reduced number of flowers. The results demonstrate that number of flowers and spur length are direct targets of selection and may affect female fitness nonadditively. More generally, they show that the adaptive value of a given trait can depend on floral context and illustrate how experimental approaches can advance our understanding of the evolution of trait combinations. © 2011 by the Ecological Society of America. Source

Lawson J.M.,University of Cambridge | Dawson J.R.,Norwegian University of Science and Technology
Physics of Fluids | Year: 2013

An investigation is made into the mechanism of pinch-off for turbulent vortex rings formed by a synthetic jet using time resolved particle image velocimetry measurements in air. During formation, measurements of the material acceleration field show a trailing pressure maximum (TPM) forms behind the vortex core. The adverse pressure gradient behind this TPM inhibits vorticity transport into the ring and the TPM is spatially coincident with the termination of vorticity flux into a control volume moving with the ring. A Lagrangian Coherent Structures (LCS) analysis is shown to be in agreement with the role of the TPM in pinch-off and in identifying the vortex ring before separation. The LCS analysis provides physical insights which form the basis of a revised model of pinch-off, based on kinematics, which predicts the time of formation (formation number) well for the present dataset. The delivery of impulse to the vortex ring is also considered. Two equally important mechanisms are shown to play a role: a material flux and a vortex force. In the case of long maximum stroke ratio, it is demonstrated that a vortex force continues to deliver impulse to the ring after the material flux is terminated at pinch-off and that this contribution may be substantial. This shows that the pinch-off and separation process cannot be considered impulse invariant, which has important implications for unsteady propulsion, present models of vortex ring formation, and existing explanations for vortex ring pinch-off. © 2013 AIP Publishing LLC. Source

Dammyr O.,Norwegian University of Science and Technology
Rock Mechanics and Rock Engineering | Year: 2016

Prediction of spalling and rock burst is especially important for hard rock TBM tunneling, because failure can have larger impact than in a drill and blast tunnel and ultimately threaten excavation feasibility. The majority of research on brittle failure has focused on rock types with isotropic behavior. This paper gives a review of existing theory and its application before a 3.5-m-diameter TBM tunnel in foliated granitic gneiss is used as a case to study brittle failure characteristics of anisotropic rock. Important aspects that should be considered in order to predict brittle failure in anisotropic rock are highlighted. Foliation is responsible for considerable strength anisotropy and is believed to influence the preferred side of v-shaped notch development in the investigated tunnel. Prediction methods such as the semi-empirical criterion, the Hoek–Brown brittle parameters, and the non-linear damage initiation and spalling limit method give reliable results; but only as long as the angle between compression axis and foliation in uniaxial compressive tests is relevant, dependent on the relation between tunnel trend/plunge, strike/dip of foliation, and tunnel boundary stresses. It is further demonstrated that local in situ stress variations, for example, due to the presence of discontinuities, can have profound impact on failure predictions. Other carefully documented case studies into the brittle failure nature of rock, in particular anisotropic rock, are encouraged in order to expand the existing and relatively small database. This will be valuable for future TBM planning and construction stages in highly stressed brittle anisotropic rock. © 2016 Springer-Verlag Wien Source

Kidd M.,Yale University | Gustafsson B.I.,Norwegian University of Science and Technology
Current Gastroenterology Reports | Year: 2012

Gastric neuroendocrine neoplasms of the stomach can be divided into the usually well-differentiated, hypergastrinemia-dependent type I and II lesions and the more aggressively behaving gastrin-independent type III lesions. Mainly due to better diagnostics and awareness of this tumor, the observed incidence has increased more than tenfold over the last 30 years. Small (<15-20 mm) localized type I and II lesions that are slowly proliferating (Ki67<2%) can usually be managed conservatively with endoscopic surveillance. Reducing hypergastrinemia by surgical removal of an underlying gastrinoma is important in inhibiting growth and induce reduction of type II lesions, while the specific gastrin receptor antagonist YF476 or gastrin antibodies may become useful for both type I and II lesions. Infiltrating and metastasized tumors and type III lesions require a more aggressive approach with surgical resection and consideration of modalities such as somatostatin analogs, cytotoxics, and peptide receptor targeted treatment. © Springer Science+Business Media, LLC 2012. Source

Phattaranawik J.,King Mongkuts University of Technology Thonburi | Leiknes T.,Norwegian University of Science and Technology
Bioresource Technology | Year: 2011

Hybrid biofilm membrane bioreactor (BF-MBR) system featuring new mechanisms for recovering the excess energy from air bubbling flow in the biofilm reactor and for controlling membrane biofouling was preliminarily investigated in this study. Alternative design of the biofilm reactor was developed to utilize the bubbling flow from the lower aerobic chamber to generate a mechanical mixing in the upper anoxic chamber in the vertical biofilm reactor. Suspended solid (SS) concentration in the system was hydrodynamically controlled to be lower than 70 mg/L. The ultraviolet (UV) inactivation unit was integrated with the membrane filtration tank to limit biological activities for biofoulant productions and to decelerate the unwanted biofilm formation in the permeate tube. Membrane relaxations at various operating conditions were studied for optimum membrane fouling reductions under low SS environment. Combinations of membrane relaxation and the UV inactivation significantly prolonged sustainable operation periods of the membrane filtration in the BF-MBR process. © 2010 Elsevier Ltd. Source

Environmental factors such as tobacco exposure, indoor climate and diet are known to be involved in the development of allergy related diseases. The aim was to determine the impact of altered exposure to these factors during pregnancy and infancy on the incidence of allergy related diseases at 2 years of age. Children from a non-selected population of mothers were recruited to a controlled, multicenter intervention study in primary health care. The interventions were an increased maternal and infant intake of n-3 PUFAs and oily fish, reduced parental smoking, and reduced indoor dampness during pregnancy and the children's first 2 years of life. Questionnaires on baseline data and exposures, and health were collected at 2 years of age. The prevalence of smoking amongst the mothers and fathers was approximately halved at 2 years of age in the intervention cohort compared to the control cohort. The intake of n-3 PUFA supplement and oily fish among the children in the intervention cohort was increased. There was no significant change for indoor dampness. The odds ratio for the incidence of asthma was 0.72 (95% CI, 0.55-0.93; NNTb 53), and 0.75 for the use of asthma medication (95% CI, 0.58-0.96). The odds ratio for asthma among girls was 0.41 (95% CI 0.24-0.70; NNTb 32), and for boys 0.93 (95% CI 0.68-1.26). There were no significant change for wheeze and atopic dermatitis. Reduced tobacco exposure and increased intake of oily fish during pregnancy and early childhood may be effective in reducing the incidence of asthma at 2 years of age. The differential impact in boys and girls indicates that the pathophysiology of asthma may depend on the sex of the children. Current Controlled Trials ISRCTN28090297. Source

Brevik I.,Norwegian University of Science and Technology
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2014

As shown in the experiment of She [Phys. Rev. Lett. 101, 243601 (2008)PRLTAO0031-900710.1103/PhysRevLett.101.243601], a weak laser beam sent through a vertically hanging fiber exerts a transverse force and produces a lateral displacement of the fiber's lower end. The experiment is of obvious theoretical interest in connection with the electromagnetic theory of media. Suggested explanations given for this effect in the past include the famous Abraham-Minkowski issue concerning the "correct" photon momentum in matter. In our opinion such an explanation is most likely not right. Instead, we propose a very simple description of the effect implying that the sideways deflection is caused by the radiation force on the obliquely cut lower end face of the fiber. From a calculation based upon geometrical optics, we find quite good agreement with the observations. We present also, as an alternative approach, a calculation involving wave optics instead of geometrical optics, and find comparable results. © 2014 American Physical Society. Source

Giacinti G.,University of Oxford | Kachelriess M.,Norwegian University of Science and Technology | Semikoz D.V.,AstroParticle and Cosmology APC
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2014

We investigate the possibility that the cosmic ray (CR) knee is entirely explained by the energy-dependent CR leakage from the Milky Way. We test this hypothesis calculating the trajectories of individual CRs with energies between E/Z=1014eV and 1017eV propagating them in the regular and turbulent Galactic magnetic field. We find a knee-like structure of the CR escape time τesc(E) around E/Z=few×1015eV for a coherence length lc≃2pc of the turbulent field, while the decrease of τesc(E) slows down around E/Z≃1016eV in models with a weak turbulent magnetic field. Assuming that the injection spectra of CR nuclei are power laws, the resulting CR intensities in such a turbulence are consistent with the energy spectra of CR nuclei determined by KASCADE and KASCADE-Grande. We calculate the resulting CR dipole anisotropy as well as the source rate in this model. © 2014 American Physical Society. Source

Vigran T.E.,Norwegian University of Science and Technology
Journal of the Acoustical Society of America | Year: 2014

A model for the acoustic properties of a plate perforated with slots of rectangular shape is proposed. The model is based on known expressions for the complex density and compressibility of a pore of rectangular shape together with the radiation impedance of a rectangular shaped piston in a baffle. For the so-called end correction of a rectangular aperture in a plate, an approximate solution is shown to fit an exact solution for the imaginary part of the radiation impedance, the latter solution based on the work of Lindemann [J. Acoust. Soc. Am, 55, 708-717 (1974)]. Two different procedures are tested to calculate the mutual influence of the apertures on the end correction, the one calculating the mutual impedance of neighboring pistons in the plate, the other by calculating the end correction of a piston placed in the end of an infinitely long tube. The model is used calculating the input impedance and absorption coefficient of a Helmholtz resonator with such a plate, comparing with measurement results. The fit between predicted and measured results, using plates with narrow slits, is good, but it is believed that the model also cover a wider range of dimensions for such a slotted plate. © 2014 Acoustical Society of America. Source

Haland E.,Norwegian University of Science and Technology
Sociology of Health and Illness | Year: 2012

Today's healthcare sector is being transformed by several ongoing processes, among them the introduction of new technologies, new financial models and new ways of organising work. The introduction of the electronic patient record (EPR) is representative and part of these extensive changes. Based on interviews with health personnel and office staff in a regional hospital in Norway, and with health administrators and information technology service-centre staff in the region, the article examines how the introduction of the EPR, as experienced by the participants, affects the work practices and boundaries between various professional groups in the healthcare system and discusses the implications this has for the understanding of medical practice. The article shows how the EPR has become part of the professionals' boundary work; expressing shifting constructions of professional identities. © 2011 Foundation for the Sociology of Health & Illness/Blackwell Publishing Ltd. Source

Giacinti G.,University of Oxford | Kachelriess M.,Norwegian University of Science and Technology | Semikoz D.V.,AstroParticle and Cosmology APC
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

We show that the cosmic ray (CR) knee can be entirely explained by energy-dependent CR leakage from the Milky Way, with an excellent fit to all existing data. We test this hypothesis calculating the trajectories of individual CRs in the Galactic magnetic field. We find that the CR escape time τesc(E) exhibits a knee-like structure around E/Z=few×1015eV for small coherence lengths and strengths of the turbulent magnetic field. The resulting intensities for different groups of nuclei are consistent with the ones determined by KASCADE and KASCADE-Grande, using simple power laws as injection spectra. The transition from Galactic to extragalactic CRs is terminated at ≈2×1018eV, while extragalactic CRs contribute significantly to the subdominant proton flux already for 2×1016eV. The natural source of extragalactic CRs in the intermediate energy region up to the ankle are in this model normal and starburst galaxies. The escape model provides a good fit to ln(A) data; it predicts that the phase of the CR dipole varies strongly in the energy range between 1×1017 and 3×1018eV, while our estimate for the dipole magnitude is consistent with observations. © 2015 American Physical Society. Source

Fougner A.,Norwegian University of Science and Technology
Conference proceedings : ... Annual International Conference of the IEEE Engineering in Medicine and Biology Society. IEEE Engineering in Medicine and Biology Society. Conference | Year: 2011

For decades, electromyography (EMG) has been used for diagnostics, upper-limb prosthesis control, and recently even for more general human-machine interfaces. Current commercial upper limb prostheses usually have only two electrode sites due to cost and space limitations, while researchers often experiment with multiple sites. Micro-machined inertial sensors are gaining popularity in many commercial and research applications where knowledge of the postures and movements of the body is desired. In the present study, we have investigated whether accelerometers, which are relatively cheap, small, robust to noise, and easily integrated in a prosthetic socket; can reduce the need for adding more electrode sites to the prosthesis control system. This was done by adding accelerometers to a multifunction system and also to a simplified system more similar to current commercially available prosthesis controllers, and assessing the resulting changes in classification accuracy. The accelerometer does not provide information on muscle force like EMG electrodes, but the results show that it provides useful supplementary information. Specifically, if one wants to improve a two-site EMG system, one should add an accelerometer affixed to the forearm rather than a third electrode. Source

Engstrom M.,Norwegian University of Science and Technology
The journal of headache and pain | Year: 2013

Our aim was to compare subjective and objective sleep quality and arousal in migraine and to evaluate the relationship between sleep quality and pain thresholds (PT) in controls, interictal, preictal and postictal migraine. Polysomnography and PT (to pressure, heat and cold) measurements were done in 34 healthy controls and 50 migraineurs. Subjective sleep quality was assessed by sleep diaries, Epworth sleepiness scale, Karolinska sleep questionnaire and Pittsburgh sleep quality index. Migraineurs who had their sleep registration more than 48 h from an attack were classified as interictal while those who were less than 48 h from an attack were classified as either preictal or postictal. Migraineurs reported more insomnia and other sleep-related symptoms than controls, but the objective sleep differences were smaller and we found no differences in daytime sleepiness. Interictal migraineurs had more awakenings (p=0.048), a strong tendency for more slow-wave sleep (p=0.050), lower thermal pain thresholds (TPT) (heat pain thresholds p=0.043 and cold pain thresholds p=0.031) than controls. Migraineurs in the preictal phase had shorter latency to sleep onset than controls (p=0.003). Slow-wave sleep correlated negatively with pressure PT and slow bursts correlated negatively with TPT. Lower PT in interictal migraineurs seems related to increased sleep pressure. We hypothesize that migraineurs on the average suffer from a relative sleep deprivation and need more sleep than healthy controls. Lack of adequate rest might be an attack-precipitating- and hyperalgesia-inducing factor. Source

Haavik T.K.,Norwegian University of Science and Technology
Journal of Contingencies and Crisis Management | Year: 2011

The way sociotechnical systems are conceptually understood influences the result of the safety assessments of such systems. In the literature on the safety of sociotechnical systems, the starting point for the descriptions is often the system components, while the relations are seen as resulting from these components. In this article, it is argued that the relations of a sociotechnical system should be understood as primary entities, defining and shaping the components. A consequence of such a relational focus, it is argued, is that system evaluations become more labour-demanding than approaches that take generic, pre-defined components as the point of departure. In return, they become more relevant and precise to the specific system in question. © 2011 Blackwell Publishing Ltd. Source

Evgrafov A.,Technical University of Denmark | Evgrafov A.,Norwegian University of Science and Technology
Computer Methods in Applied Mechanics and Engineering | Year: 2014

We introduce a new algorithm for solving certain classes of topology optimization problems, which enjoys fast local convergence normally achieved by the full space methods while working in a smaller reduced space. The computational complexity of Newton's direction finding subproblem in the algorithm is comparable with that of finding the steepest descent direction in the traditional first order nested/reduced space algorithms for topology optimization. That is, the space reduction is computationally inexpensive, and more importantly it does not ruin the sparsity of the full-space system of optimality conditions.The fast local convergence of the algorithm allows one to efficiently solve a sequence of optimization problems for varying parameters (numerical continuation). This can be utilized for eliminating the errors introduced by the approximate enforcement of the boundary conditions or 0/1-type constraints on the design field through penalties in many topology optimization approaches.We test the algorithm on the benchmark problems of dissipated power minimization for Stokes flows, and in all cases the algorithm outperforms the traditional first order reduced space/nested approaches by a factor varying from two to almost twenty in terms of the number of iterations while attaining an almost unprecedented accuracy in solving the discretized topology optimization problem. Finally we present a few extensions to the algorithm, one involving computations on adaptively refined meshes and another related to solving topology optimization problems for non-Newtonian fluids. © 2014 Elsevier B.V. Source

Marchetti J.M.,Norwegian University of Science and Technology
Topics in Catalysis | Year: 2010

Four different Me/Al2O3 (Me = Na, Ba, Ca, and K) powder catalysts prepared by incipient-wetness impregnation, and a K/Al 2O3-cordierite monolithic catalyst produced by the dipcoating technique were used for biodiesel production. The samples were characterized and studied in the transesterification of soybean oil with methanol at 120 °C and 500 rpm, with a alcohol/oil molar ratio = 32, and a catalyst load = 1 wt% for the powder catalyst and 0.5 wt% for the monolith. The Ca/Al2O3, Na/Al2O3 and K/Al 2O3 powder catalysts reported a FAME (fatty acid methyl esters) formation of 94.7, 97.1, and 98.9% respectively after 6 h of reaction. On the other hand, Ba/Al2O3 showed little activity (7.6%). The leaching of the alkali and alkaline earth metal species during reaction was important, what indicates that the activity could be explained in terms of a homogeneous-heterogeneous catalyst effect. When the monolithic sample and the powder catalyst were compared (under identical reaction conditions), the production of FAME for the latter was 89.5-59.1% for the monolithic catalyst. After two consecutive runs, the monolithic catalyst presented a partial deactivation of 8% in the FAME yield. The present work shows that the use of monolithic catalysts in the transesterification of vegetable oils is a viable alternative. © 2010 Springer Science+Business Media, LLC. Source

Bensnes S.S.,Norwegian University of Science and Technology
Journal of Health Economics | Year: 2016

Pollen is known to cause allergic reactions and affect cognitive performance in around 20% of the population. Although pollen season peaks when students take high-stakes exams, the effect of pollen allergies on school performance has received nearly no attention from economists. Using a student fixed effects model and administrative Norwegian data, this paper finds that increasing the ambient pollen levels by one standard deviation at the mean leads to a 2.5% standard deviation decrease in test scores, with potentially larger effects for allergic students. There also appear to be longer-run effects. The findings imply that random increases in pollen counts reduce test scores for allergic students relative to their peers, who consequently will be at a disadvantage when competing for jobs or higher education. This paper contributes to the literature by illuminating the interplay between individual health and human capital accumulation, which in turn can impact long-run economic growth. © 2016 Elsevier B.V. Source

Naess E.,Norwegian University of Science and Technology
Applied Thermal Engineering | Year: 2010

An experimental investigation of the heat transfer and pressure drop performance of ten finned tube bundles using serrated fins is presented. All tube bundles had staggered layouts, and the influence on varying tube bundle layout, tube and fin parameters are presented. The heat transfer coefficient experienced a maximum when the flow areas in the transversal and diagonal planes were equal. An increase in the fin pitch increased the heat transfer coefficient; the same was observed with an increase in fin height. The pressure drop coefficient showed no influence of the tube bundle layout for small pitch ratios, but dropped significantly for higher ratios. Increasing fin pitch reduced the pressure drop, whereas varying fin height had insignificant effect. None of the literature correlations were able to reproduce the experiments for the entire range of tested conditions. A set of correlations were developed, reproducing the experimental data to within ±5% at a confidence interval of 95%. © 2010 Elsevier Ltd. All rights reserved. Source

Aalberg A.,Norwegian University of Science and Technology
Journal of Constructional Steel Research | Year: 2015

Abstract Here, the reaction force capacity of I-section steel beam ends with top flange copes was investigated experimentally and numerically, with a focus on local web buckling. An experimental test series was carried out on unstiffened top coped beam ends that were subjected to reaction forces under the bottom flange. Experimental results are given for beam ends with five sizes of cope and for a reference beam without a cope. The investigated beam section was a standard IPE 300 in steel grade S355. The test results were compared with existing design models for coped beams and with models primarily developed for triangular stiffener brackets. A new design formula is proposed for top coped beams supported at the bottom flange, which allows the capacity to be determined as a function of capacity of uncoped beam end with a reduction based on the size of the cope. Finite element models were verified against the experiments and used to extend the experimental data and investigate parameters affecting the web buckling resistance, such as web slenderness and the restraints provided by connection devices. © 2015 Elsevier Ltd. Source

Adaramola M.S.,Norwegian University of Science and Technology | Oyewola O.M.,University of Ibadan
Renewable Energy | Year: 2011

The wind speed distribution and wind energy potential are investigated in three selected locations in Oyo state using wind speed data that span between 12 and 20 years measured at 10 m height. In addition, the performance of selected small to medium size wind turbines in these sites were examined. The annual energy output and capacity factor for these turbines were determined. It was found that the monthly mean wind speeds in Oyo state ranges from 2.85 m/s to 5.20 m/s. While the monthly mean power density varies between 27.08 W/m2 and 164.48 W/m2, while the annual mean power density is in the range of 67.28 W/m2 and 106.60 W/m2. Based on annual energy output, wind turbines with cut-in wind speed of about 2.5 m/s and moderate rated wind speeds will be best suited for all the sites. © 2011 Elsevier Ltd. Source

Pfuhl G.,Norwegian University of Science and Technology
Animal Cognition | Year: 2012

There are simple co-occurrences as well as functional relationships between events. One may assume that animals detect and use causation rather than mere co-variation. However, understanding causation often requires concepts of hidden forces. In string pulling, obstacles may hamper the access to food. Here, I studied whether ravens have an abstract concept of effort. First, in a competitive situation, ravens (Corvus corax) could choose one out of two strings. The strings differed in whether they were baited with meat and in how far away the meat was. Ravens pulled mainly the string containing meat and where the meat was nearer to the perch, respectively. Second, ravens could choose between two strings that had either a functional obstacle or a non-functional obstacle. Optimal performance required the integration of at least two cues: object and height. In 5 ravens, the model that best matched behaviour took into account only that meat was on a string, ignoring the obstacle. However, 2 ravens' performance was best explained by a model that took into account both an object's identity (meat or wood) and its height on the string. Third, one string out of two was loaded with a heavy meat piece. In this overloaded string condition, 5 out of 7 ravens did not try to pull the heavy meat piece but went straight for pulling the smaller piece. The pattern of results indicated that ravens can judge the effort required to pull a string. © 2012 Springer-Verlag. Source

Engstrom M.J.,Norwegian University of Science and Technology
Breast cancer research and treatment | Year: 2013

Molecular subtyping of breast cancer may provide additional prognostic information regarding patient outcome. However, its clinical significance remains to be established. In this study, the main aims were to discover whether reclassification of breast cancer into molecular subtypes provides more precise information regarding outcome compared to conventional histopathological grading and to study breast cancer-specific survival in the different molecular subtypes. Cases of breast cancer occurring in a cohort of women born between 1886 and 1928 with long-term follow-up were included in the study. Tissue microarrays were constructed from archival formalin-fixed, paraffin-embedded tissue from 909 cases. Using immunohistochemistry and in situ hybridisation as surrogates for gene expression analyses, all cases were reclassified into the following molecular subtypes: Luminal A; Luminal B (HER2-); Luminal B (HER2+); HER2 subtype; Basal phenotype; and five negative phenotype. Kaplan-Meier survival curves and Cox proportional hazards models were used in the analyses. During the first 5 years after diagnosis, there were significant differences in prognosis according to molecular subtypes with the best survival for the Luminal A subtype and the worst for HER2 and five negative phenotype. In this historic cohort of women with breast cancer, differences in breast cancer-specific survival according to subtype occur almost exclusively amongst the histopathological grade 2 tumours. From 5 years after time of diagnosis until the end of follow-up, there appears to be no difference in survival according to molecular subtype or histopathological grade. Source

Einum S.,Norwegian University of Science and Technology
American Naturalist | Year: 2014

Genetically based variation in metabolic rates of resting animals (RMR) suggests a potential role for evolutionary adaptations, but mechanistic models yielding evolutionary predictions are lacking. Here I utilize the increasingly recognized genetic correlation between RMR and activity metabolism and propose that optimality of the former is simply an outcome of selection on the latter. I develop a model for temporally stable environmental conditions that describes how the rate of acquisition of energy that can be converted into somatic growth and reproductive output can be expressed as a function of activity metabolism. One of the parameters in the model describes how food intake depends on activity and is hence a measure of food abundance. In contrast to the previously proposed hypothesis that individuals with a high RMR are at an advantage when environmental conditions are favorable, the model predicts that the optimal RMR is highest at an intermediate food abundance. © 2014 by The University of Chicago. Source

Haugan G.,Norwegian University of Science and Technology
Scandinavian Journal of Caring Sciences | Year: 2014

Background: Spiritual dimensions such as hope, meaning in life and self-transcendence have been found to be predictors of successful ageing, life satisfaction and well-being in older individuals. Connectedness and communicating with others have been seen to facilitate hope, meaning in life and self-transcendence among nursing home patients. Aims: This study aimed to investigate the associations between hope, meaning in life, self-transcendence and nurse-patient interaction in a nursing home population. Design and methods: A cross-sectional design was employed, collecting data in 44 different Norwegian nursing homes (NHs) from 250 patients who met the inclusion criteria. Approval by all regulatory institutions dealing with research issues in Norway and the Management Unit at the 44 NHs was obtained. A sample of 202 cognitively intact nursing home patients responded to the Herth Hope Index, the Purpose in Life test, the Self-Transcendence Scale and the Nurse-Patient Interaction Scale. A structural equation model (SEM) of the hypothesized relationships between the constructs was tested. Results: The SEM model fit well with the present data. Significant direct relationships of nurse-patient interaction on hope, meaning in life and self-transcendence were displayed. Meaning and the interconnectedness dimension of hope appeared to be particularly dynamic resources, revealing significant influences on all the constructs in the SEM model tested. Conclusion: Nurse-patient interaction influences hope, meaning in life and self-transcendence in cognitively intact nursing home patients and might be an important resource in relation to patients' health and global well-being. Thus, care providers are above all fundamental for nursing home patients. Advancing caregivers' interacting and communicating skills might facilitate patients' health and global well-being and inspire professional caregivers as they perform their daily care practices. More research of the effectiveness of such strategies is greatly needed. Limitations: The SEM model tested comprised 20 variables, indicating a desirable sample size of n = 200, while the present effective sample was n = 187. Also, cross-sectional data do not allow making conclusion on the causality. © 2013 Nordic College of Caring Science. Source

Haugan G.,Norwegian University of Science and Technology
Journal of Advanced Nursing | Year: 2014

Aim: To investigate the associations between nurse-patient interaction and meaning-in-life in a nursing home population. Background: Meaning has been found to be a strong individual predictor of successful ageing and life satisfaction as well as an important psychological variable that promotes well-being. Meaning seems to serve as a mediating variable in both psychological and physical health. Connecting and communicating with others have been seen to facilitate meaning-in-life among older individuals. Design: Cross-sectional descriptive study. Methods: The data were collected in 2008-2009 using the Nurse-Patient Interaction Scale and the Purpose-in-Life test. A total of 250 cognitively intact nursing home patients met the inclusion criteria and 202 (81%) participated. A structural equation model of the hypothesized relationship between nurse-patient interaction and meaning was tested by means of LISREL 8.8. Findings: The structural equation model fit well with the data. A significant direct relationship between nurse-patient interaction and meaning-in-life in cognitively intact nursing home patients was displayed. Conclusion: Nurse-patient interaction significantly relates to meaning and purpose-in-life among cognitively intact nursing home patients and might be an important resource in relation to the patient's mental health and global well-being. High-quality nurse-patient interaction and in-house activities aiming to increase patients' meaning might increase psychological and physical health, well-being and psycho-spiritual functioning in this vulnerable population. © 2013 John Wiley & Sons Ltd. Source

Haugan G.,Norwegian University of Science and Technology
Journal of Clinical Nursing | Year: 2014

Aims and objectives: To investigate the associations between meaning-in-life and physical, emotional, functional and social well-being in a cognitively intact nursing-home population. Background: Meaning-in-life is understood as an influential psychological variable that promotes health and well-being; meaning-in-life has been found to be a mediating variable in both psychological and physical health. Design and methods: The study employed a cross-sectional design. Data were collected in 2008 and 2009 using the purpose-in-life test and the FACT-G quality-of-life questionnaire. A total of 250 cognitively intact nursing-home patients who met the inclusion criteria were approached and 202 attended. The hypothesised relationships between meaning and multidimensional well-being were tested by means of structural equation modelling. Results: The structural equation modelling model fit well with the present data, showing significant direct relationships between meaning-in-life and emotional and functional well-being, and a significant mediated influence of meaning on social and physical well-being. Conclusion: Meaning-in-life is associated with all dimensions of well-being and likely plays an important role in both emotional and physical well-being. Relevance to clinical practice: Facilitating patients' perceived meaning-in-life might help ease emotional distress and physical symptoms, thus fostering well-being in cognitively intact nursing-home patients. Therefore, advancing staff nurses' competence in facilitating meaningful involvement, connectedness, nurse-patient interaction and symptom management is important for care quality and global well-being in nursing homes. © 2013 John Wiley & Sons Ltd. Source

OBJECTIVE:: Knowledge on how changing risk factors influence the progression of albuminuria over time is still limited. Furthermore, large population-based cohorts are needed to study the association between albuminuria change and mortality risk in nondiabetic study participants. METHODS:: We evaluated changes of albuminuria in 6282 nondiabetic individuals from the Norwegian population-based Nord-Tr⊘ndelag Health study. Using three albumin/creatinine ratios (ACR), we studied the influence of cardiovascular risk factors on ACR change from baseline to follow-up 11 years later. We evaluated the next 8-year mortality risk by using flexible parametric methods to identify nonlinear main effects and their two-way interactions. RESULTS:: Mean albuminuria increased significantly over 11 years (1.82–3.02?mg/mmol, P? Source

Witter M.P.,Norwegian University of Science and Technology
Philosophical transactions of the Royal Society of London. Series B, Biological sciences | Year: 2014

The hippocampal region contains several principal neuron types, some of which show distinct spatial firing patterns. The region is also known for its diversity in neural circuits and many have attempted to causally relate network architecture within and between these unique circuits to functional outcome. Still, much is unknown about the mechanisms or network properties by which the functionally specific spatial firing profiles of neurons are generated, let alone how they are integrated into a coherently functioning meta-network. In this review, we explore the architecture of local networks and address how they may interact within the context of an overarching space circuit, aiming to provide directions for future successful explorations. Source

Li C.C.,Norwegian University of Science and Technology
Rock Mechanics and Rock Engineering | Year: 2015

An inflatable bolt is integrated in the rock mass through the friction and mechanical interlock at the bolt–rock interface. The pullout resistance of the inflatable bolt is determined by the contact stress at the interface. The contact stress is composed of two parts, termed the primary and secondary contact stresses. The former refers to the stress established during bolt installation and the latter is mobilized when the bolt tends to slip in the borehole owing to the roughness of the borehole surface. The existing analysis of the inflatable rock bolt does not appropriately describe the interaction between the bolt and the rock since the influence of the folded tongue of the bolt on the stiffness of the bolt and the elastic rebound of the bolt tube in the end of bolt installation are ignored. The interaction of the inflatable bolt with the rock is thoroughly analysed by taking into account the elastic displacements of the rock mass and the bolt tube during and after bolt installation in this article. The study aims to reveal the influence of the bolt tongue on the contact stress and the different anchoring mechanisms of the bolt in hard and soft rocks. A new solution to the primary contact stress is derived, which is more realistic than the existing one in describing the interaction between the bolt and the rock. The mechanism of the secondary contact stress is also discussed from the point of view of the mechanical behaviour of the asperities on the borehole surface. The analytical solutions are in agreement with both the laboratory and field pullout test results. The analysis reveals that the primary contact stress decreases with the Young’s modulus of the rock mass and increases with the borehole diameter and installation pump pressure. The primary contact stress can be easily established in soft and weak rock but is low or zero in hard and strong rock. In soft and weak rock, the primary contact stress is crucially important for the anchorage of the bolt, while in hard and strong rock it is the secondary contact stress that plays a vital role. © 2015 Springer-Verlag Wien Source

Halvorsen T.,Norwegian University of Science and Technology
Regional Studies | Year: 2012

Halvorsen T. Size, location and agglomeration of inward foreign direct investment (FDI) in the United States, Regional Studies. Since the late 1970s a range of economic development policies to attract foreign direct investments (FDIs) have been tried out. Despite a policy reorientation from a large-size bias to policies also favouring smaller investments, little empirical work has been performed on the determinants of investment size. This paper presents empirical evidence on how the size of FDIs is determined by agglomeration and other state-level factors. The results indicate that FDI agglomeration and urbanization affect investment size and that taxes, markets, labour, land and the concentration of scientific knowledge are important determinants in the size composition of FDI. © 2012 Copyright Regional Studies Association. Source

Modlin I.M.,Yale University | Pavel M.,Charite Campus Virchow Klinikum | Kidd M.,Yale University | Gustafsson B.I.,Norwegian University of Science and Technology
Alimentary Pharmacology and Therapeutics | Year: 2010

Background The discovery of somatostatin (SST) and the synthesis of a variety of analogues constituted a major therapeutic advance in the treatment of gastroenteropancreatic neuroendocrine (carcinoid) tumours (GEP-NETs). They currently provide the most efficient treatment to achieve symptomatic relief and have recently been demonstrated to inhibit tumour growth. Aim To review 35 years of experience regarding the clinical application and efficacy of SST analogues. Methods The PubMed database (1972-2009) was searched using somatostatin as a search term with combinations of terms including 'treatment'; 'neuroendocrine'; 'carcinoid'; 'tumor'; 'octreotide'; 'lanreotide' and 'pasireotide'. Results In a review of 15 studies including 481 patients, the slow-release formulations Sandostatin LAR and Somatuline SR/Autogel achieved symptomatic relief in 74.2% (61.9-92.8%) and 67.5% (40.0-100%), biochemical response in 51.4% (31.5-100%) and 39.0% (17.9-58%), and tumour response in 69.8% (47.0-87.5%) and 64.4% (48.0-87.0%) respectively. Novel SST analogues like SOM230 (pasireotide) that exhibit pan SST receptor activity and analogues with high affinity to specific somatostatin receptor (sstr) subtypes may further advance the field, but efficacy studies are lacking. Conclusion As more precise understanding of NET cell biology evolves and molecular biological tools advance, more accurate identification of individual tumours sstr profile will probably facilitate a more precise delineation of SST analogue treatment. Source

Persson J.R.,Norwegian University of Science and Technology
Atomic Data and Nuclear Data Tables | Year: 2013

This table is a compilation of experimental values of magnetic hyperfine anomaly in atomic and ionic systems. The last extensive compilation was published in 1984 by Büttgenbach [S. Büttgenbach, Hyperfine Int. 20 (1984) 1] and the aim here is to make an up to date compilation. The literature search covers the period up to January 2011. © 2012 Elsevier Inc. Source

Venkatesh G.,Norwegian University of Science and Technology
Problemy Ekorozwoju | Year: 2014

The first two words in the headline allude to a never-ending pursuit of something which is elusive - say sustaina-bility, with this endless and dogged keeping-on taking the name sustainable development. The last two would indicate that what we are talking about could be a zero-sum game. Whether or not even a Pyrrhic victory would be attained when it comes to sustaining the water resources on Terra Firma, is difficult to say, realistically speaking. A struggle it promises to be, nevertheless... partly-Sisyphean. As the Norwegian explorer, scientist and environmentalist Thor Heyerdahl said, Life originated in the sea. All life on land is dependent on the unique hydrological cycle which has been designed so meticulously by Nature. Mankind needs to work together with Nature, so that both are saved. Source

Edvinsson L.,Lund University | Linde M.,Norwegian University of Science and Technology | Linde M.,Gothenburg University
The Lancet | Year: 2010

Although the triptan drugs provide effective relief from migraine for many patients, a substantial number of affected individuals are unresponsive to these compounds, and such therapy can also lead to a range of adverse effects. Telcagepant represents a new class of antimigraine drug - the calcitonin gene-related peptide receptor blockers. This compound exerts its effects by blocking receptors for the calcitonin-gene-related peptide at several sites in the trigeminal and central nervous systems, resulting in pain relief. Telcagepant does not cause vasoconstriction, a major limitation in the use of triptans. Comparisons with triptans in clinical trials for acute treatment of migraine attacks revealed clinical effects similar to those of triptans but better than those of placebo. Telcagepant might provide hope for those who have a poor response to, or are unable to use, older drugs. In patients who need prophylaxis because of frequent attacks of migraine, topiramate is a first-line drug for migraine prevention in many countries; it is generally safe and reasonably well tolerated. Data suggest that topiramate could aid reversion of chronic migraine to episodic migraine. © 2010 Elsevier Ltd. Source

Vatn J.,Norwegian University of Science and Technology | Aven T.,University of Stavanger
Reliability Engineering and System Safety | Year: 2010

The starting point for this paper is a traditional approach to maintenance optimization where an object function is used for optimizing maintenance intervals. The object function reflects maintenance cost, cost of loss of production/services, as well as safety costs, and is based on a classical cost-benefit analysis approach where a value of prevented fatality (VPF) is used to weight the importance of safety. However, the rationale for such an approach could be questioned. What is the meaning of such a VPF figure, and is it sufficient to reflect the importance of safety by calculating the expected fatality loss VPF and potential loss of lives (PLL) as being done in the cost-benefit analyses? Should the VPF be the same number for all type of accidents, or should it be increased in case of multiple fatality accidents to reflect gross accident aversion? In this paper, these issues are discussed. We conclude that we have to see beyond the expected values in situations with high safety impacts. A framework is presented which opens up for a broader decision basis, covering considerations on the potential for gross accidents, the type of uncertainties and lack of knowledge of important risk influencing factors. Decisions with a high safety impact are moved from the maintenance department to the "Safety Board" for a broader discussion. In this way, we avoid that the object function is used in a mechanical way to optimize the maintenance and important safety-related decisions are made implicit and outside the normal arena for safety decisions, e.g. outside the traditional "Safety Board". A case study from the Norwegian railways is used to illustrate the discussions. © 2009 Elsevier Ltd. All rights reserved. Source

Kittelsaa A.M.,Norwegian University of Science and Technology
Scandinavian Journal of Disability Research | Year: 2014

The aim of this article is to demonstrate how some young individuals who are labelled as having intellectual disabilities present themselves and how they understand and relate to the fact that they are included in the category of intellectual disability. The article draws on findings from a study based on participant observation and semi-structured interviews with seven young adults about their self-understanding and daily life experiences. During the data gathering period, which lasted for two years, the participants were followed in their daily activities, at home, at work, and in their leisure time. The study shows that the participants were well aware of their impairments. However, they resisted the notion that intellectual disability should be central to defining who they are. © 2013 Nordic Network on Disability Research. Source

Bayat F.,University of Zanjan | Johansen T.A.,Norwegian University of Science and Technology
IEEE Transactions on Automatic Control | Year: 2013

This paper deals with the explicit solution and approximation of the constrained linear finite time optimal control problem for systems with fast sampling rates. To this aim, the recently developed explicit model predictive control (eMPC) is reformulated and characterized using the $\delta $-operator to enjoy its promising advantages compared to the time-shift operator. Using the proposed $\delta $-model eMPC formulation, a systematic method is proposed for first designing a low-complexity approximate eMPC solution and then improving its closed loop action without first determining an exact optimal solution that might be of prohibitive complexity. It is shown that the stability and feasibility of the proposed sub-optimal solution is guaranteed. © 2013 IEEE. Source

Brekke E.,Norwegian University of Science and Technology | Chitre M.,National University of Singapore
International Journal of Robotics Research | Year: 2015

We propose a multi-hypothesis solution to the simplified problem of simultaneous localization and mapping (SLAM) that arises when only two measurement frames are available. The proposed solution is obtained through direct evaluation of the posterior density as given by finite set statistics. We show that hypothesis probabilities can be evaluated within reasonable accuracy by means of a closed-form expression. Consistency properties are discussed extensively. We overcome inconsistency problems of the extended Kalman filter by means of natural gradient optimization, and we demonstrate through implementations on simulated and real data that the proposed approach has better consistency properties than alternative approaches when applied to the two-frame SLAM problem. © The Author(s) 2014. Source

Roe O.D.,Norwegian University of Science and Technology | Roe O.D.,University of Aalborg | Stella G.M.,University of Pavia
European Respiratory Review | Year: 2015

Asbestos is the term for a family of naturally occurring minerals that have been used on a small scale since ancient times. Industrialisation demanded increased mining and refining in the 20th century, and in 1960, Wagner, Sleggs and Marchand from South Africa linked asbestos to mesothelioma, paving the way to the current knowledge of the aetiology, epidemiology and biology of malignant pleural mesothelioma. Pleural mesothelioma is one of the most lethal cancers, with increasing incidence worldwide. This review will give some snapshots of the history of pleural mesothelioma discovery, and the body of epidemiological and biological research, including some of the controversies and unresolved questions. Translational research is currently unravelling novel circulating biomarkers for earlier diagnosis and novel treatment targets. Current breakthrough discoveries of clinically promising noninvasive biomarkers, such as the 13-protein signature, microRNAs and the BAP1 mesothelioma/cancer syndrome, are highlighted. The asbestos history is a lesson to not be repeated, but here we also review recent in vivo and in vitro studies showing that manmade carbon nanofibres could pose a similar danger to human health. This should be taken seriously by regulatory bodies to ensure thorough testing of novel materials before release in the society. ©ERS 2015. Source

Hoftun G.B.,University of Sfax | Romundstad P.R.,Norwegian University of Science and Technology | Rygg M.,University of Sfax
Journal of Pain | Year: 2012

The aim of this study was to assess the association of chronic pain with different lifestyle factors and psychological symptoms in a large, unselected adolescent population. Pain was evaluated as chronic non-specific pain, chronic multisite pain, and in additional analyses, chronic pain with high disability. The study was performed during 2006 to 2008 in Nord-Trondelag County, Norway. Adolescents aged 13 to 18 years were invited to participate. The response rate was 78%. The final study population consisted of 7,373. Sedentary behavior and pain were associated only in girls. In both sexes, overweight and obesity were associated with increased odds of pain. Whereas both smoking and alcohol intoxication showed strong associations with pain, the associations were attenuated after adjustments for psychosocial factors. Symptoms of anxiety and depression showed the strongest associations with pain (odds ratio 4.1 in girls and 3.7 in boys). The odds of pain increased gradually by number of unfavorable lifestyle factors reported. This study revealed consistent associations between lifestyle factors, anxiety and depression, and chronic pain, including multisite pain and pain with high disability. The consistency across the different pain categories suggests common underlying explanatory mechanisms, and despite the cross-sectional design, the study indicates several modifiable targets in the management of adolescent chronic pain. Perspective: This study showed a clear and consistent relation between different lifestyle factors, anxiety and depression, and the pain categories chronic non-specific pain, multisite pain, and also pain with high disability. Independent of causality, it underlines the importance of a broad perspective when studying, preventing, and treating chronic pain in adolescents. © 2012 by the American Pain Society. Source

Muskulus M.,Norwegian University of Science and Technology
Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences | Year: 2015

The aim of rotor load models is to characterize and generate the thrust loads acting on an offshore wind turbine. Ideally, the rotor simulation can be replaced by time series from a model with a few parameters and state variables only. Such models are used extensively in control system design and, as a potentially new application area, structural optimization of support structures. Different rotor load models are here evaluated for a jacket support structure in terms of fatigue lifetimes of relevant structural variables. All models were found to be lacking in accuracy, with differences of more than 20% in fatigue load estimates. The most accurate models were the use of an effective thrust coefficient determined from a regression analysis of dynamic thrust loads, and a novel stochastic model in state-space form. The stochasticmodel explicitly models the quasi-periodic components obtained from rotational sampling of turbulent fluctuations. Its state variables follow a mean-reverting Ornstein-Uhlenbeck process. Although promising, more work is needed on how to determine the parameters of the stochastic model and before accurate lifetime predictions can be obtained without comprehensive rotor simulations. © 2015 The Author(s) Published by the Royal Society. All rights reserved. Source

Grimsmo A.L.,Norwegian University of Science and Technology | Grimsmo A.L.,University of Auckland | Parkins S.,University of Auckland
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

We propose a quantum simulation of a two-level atom coupled to a single mode of the electromagnetic field in the ultrastrong-coupling regime based upon resonant Raman transitions in an atom interacting with a high finesse optical cavity mode. We show by numerical simulation the possibility of realizing the scheme with a single rubidium atom, in which two hyperfine ground states make up the effective two-level system, and for cavity QED parameters that should be achievable with, for example, microtoroidal whispering-gallery-mode resonators. Our system also enables simulation of a generalized model in which a nonlinear coupling between the atomic inversion and the cavity photon number occurs on an equal footing with the (ultrastrong) dipole coupling and can give rise to critical-type behavior even at the single-atom level. Our model takes account of dissipation, and we pay particular attention to observables that would be readily observable in the output from the system. © 2013 American Physical Society. Source

Kachelriess M.,Norwegian University of Science and Technology | Neronov A.,University of Geneva | Semikoz D.V.,Paris West University Nanterre La Defense
Physical Review Letters | Year: 2015

The locally observed cosmic ray spectrum has several puzzling features, such as the excess of positrons and antiprotons above ∼20 GeV and the discrepancy in the slopes of the spectra of cosmic ray protons and heavier nuclei in the TeV-PeV energy range. We show that these features are consistently explained by a nearby source which was active approximately two million years ago and has injected (2-3)×1050 erg in cosmic rays. The transient nature of the source and its overall energy budget point to the supernova origin of this local cosmic ray source. The age of the supernova suggests that the local cosmic ray injection was produced by the same supernova that has deposited Fe60 isotopes in the deep ocean crust. © 2015 American Physical Society. © 2015 American Physical Society. Source

Skonhoft A.,Norwegian University of Science and Technology
Environmental and Resource Economics | Year: 2016

During the last few decades, the number of large carnivores (wolf, bear, lynx and wolverines) has increased significantly in Scandinavia. As a result of more predation of livestock, conflicts with livestock farmers have deepened. We model this conflict using sheep farming as an example, and in instances in which farmers are given compensation for the predation loss. The compensation scheme is composed of a fixed per animal loss value (ex-post), but also a compensation just for the presence of the carnivores (ex-ante). Ex-post compensation payment is practiced in many countries where farmers are affected by killed and injured livestock, but also damages to crops. Ex-ante payment implies payment for environmental services and is also widely practiced. In the first part of the paper, the stocking decision of a group of farmers is analyzed. In a next step, the Directorate for Natural Resource Management (DNRM), managing the carnivores and compensation scheme, is introduced. The strategic interaction between the sheep farmers and DNRM is modelled as a Stackelberg game with DNRM as the leader. We find that it is not beneficial for DNRM to use ex-post, but only ex-ante compensation. The solution to the game is compared to the social planner solution, and numerical illustrations indicate that the efficiency loss of the ex-ante compensation scheme to be small. © 2016 Springer Science+Business Media Dordrecht Source

Materstvedt L.J.,Norwegian University of Science and Technology
Progress in Palliative Care | Year: 2013

The performing of euthanasia is now offered as an option by certain palliative care service institutions in Belgium. The approach is known as the 'integral' model. Although it is understandable that some physicians are in favour of it, the model is rejected in this article, for both clinical and ethical reasons. Furthermore, the idea of 'palliative futility' associated with the model is shown to be incoherent. In countries where assisted dying is legal, palliative care providers should refrain from participating in such practices if they are to remain true to the basic values of such care. The widespread conception that withholding and withdrawing treatment amounts to a 'hastening' of death is also rejected. © W. S. Maney & Son Ltd 2013. Source

Aksnes V.,Norwegian University of Science and Technology
Cold Regions Science and Technology | Year: 2011

A semi-empirical method for calculating local ice forces on moored ships was described in Part 1 and is implemented for a real hull in this article. The method splits the ice actions into actions in the vicinity of the waterline caused by breaking of intact ice and rotation of broken ice floes, and actions below the waterline caused by ice-hull friction. The hull was discretized into flat panels and ice forces were calculated for each panel and summed to obtain the total ice action. The resolution of the discretization was studied and stable results were obtained with relatively few panels.The model was compared with model test data and satisfactory agreement was found for the mean mooring forces. Surge oscillations were larger in the simulations than in the model tests, probably due to underestimated ice-induced damping forces in the simulations.The dynamic surge response of the ship was investigated by varying the ice drift speed and the surge natural period. The coefficient of variation for the surge motions was largest for speeds around 0.10-0.15. m/s for all surge natural periods. The importance of parameterizing the ice forces in terms of the penetration of the ship into the ice is highlighted, as this strongly affects the dynamic response of moored ships in level ice.The model can be applied in studies of dynamic response of moored ships in level ice with constant drift direction and it can be extended to variable ice drift direction. © 2010 Elsevier B.V. Source

Gao T.,Norwegian University of Science and Technology | Wang T.,Hunan University
Crystal Growth and Design | Year: 2010

A one-dimensional (1D) to two-dimensional (2D) topotactic transformation has been proposed for the synthesis of 2D CdS nanosheets by promoting the lateral growth of 1D CdS nanobelts. The as-prepared nanosheets are single crystal with hexagonal structure, usually 20-100 nm in thickness, 20-100 μm in width, and up to several millimeters in length. CdS nanosheets show enhanced multiphonon responses and exciton-phonon couplings, which are correlated to their extraordinary anisotropic geometry. Photoluminescence measurement reveals three emission bands at about 1.61, 2.39, and 2.45 eV, which are attributed to the radiative transitions related to surface states, bandgap, and excitonic molecules, respectively; moreover, the formation of the surface states and the excitonic molecules are significantly enhanced due to the anisotropic geometry of the 2D nanosheets. CdS nanosheets show also pronounced photoconduction under visible light irradiation, indicating potentials in assembly of optoelectronic nanodevices. © 2010 American Chemical Society. Source

Tedeschi E.,Norwegian University of Science and Technology | Santos-Mugica M.,Tecnalia
IEEE Transactions on Power Systems | Year: 2014

This paper presents a complete wave-to-wire approach to the modeling of wave energy farms. It captures all the main peculiarities of such applications, from the variability of sea waves to the issues related to the grid integration of a multi-MW wave farm, including the hydrodynamic modeling of wave energy converters (WECs). The paper specifically discusses the different levels of control of a wave farm and their integration and coordination. These are crucial to meet the power quality requirements at the point of common coupling (PCC) and ensure the efficiency of the power transfer from the waves to the main electric grid. A specific real-time technique for the centralized control of a wave farm is also proposed, which is exemplified with reference to the PCC voltage control in the real test case of bimep. Critical cases of weaker grids are also considered to extend the validity of the analysis. © 1969-2012 IEEE. Source

Evgrafov A.,Norwegian University of Science and Technology
Structural and Multidisciplinary Optimization | Year: 2015

We present a locally cubically convergent algorithm for topology optimization of Stokes flows based on a Chebyshev’s iteration globalized with Armijo linesearch. The characteristic features of the method include the low computational complexity of the search direction calculation, evaluation of the objective function and constraints needed in the linesearch procedure as well as their high order derivatives utilized for obtaining higher order rate of convergence. Both finite element and finite volumes discretizations of the algorithm are tested on the standard two-dimensional benchmark problems, in the case of finite elements both on structured and quasi-uniform unstructured meshes of quadrilaterals. The algorithm outperforms Newton’s method in nearly all test cases. Finally, the finite element discretization of the algorithm is tested within a continuation/adaptive mesh refinement framework. © 2015, Springer-Verlag Berlin Heidelberg. Source

Giacinti G.,University of Hamburg | Giacinti G.,Norwegian University of Science and Technology | Giacinti G.,University Paris Diderot | Sigl G.,University of Hamburg
Physical Review Letters | Year: 2012

In the energy range from ∼1012eV to ∼1015eV, the Galactic cosmic ray flux has anisotropies both on large scales, with an amplitude of the order of 0.1%, and on scales between ≃10° and ≃30°, with amplitudes smaller by a factor of a few. With a diffusion coefficient inferred from Galactic cosmic ray chemical abundances, the diffusion approximation predicts a dipolar anisotropy of comparable size, but does not explain the smaller scale anisotropies. We demonstrate here that energy dependent smaller scale anisotropies naturally arise from the local concrete realization of the turbulent magnetic field within the cosmic ray scattering length. We show how such anisotropies could be calculated if the magnetic field structure within a few tens of parsecs from Earth were known. © 2012 American Physical Society. Source

Steiner T.J.,Norwegian University of Science and Technology
The journal of headache and pain | Year: 2014

BACKGROUND: In medicine, research misconduct is historically associated with laboratory or pharmaceutical research, but the vulnerability of epidemiological surveys should be recognized. As these surveys underpin health policy and allocation of limited resources, misreporting can have far-reaching implications. We report how fraud in a nationwide headache survey occurred and how it was discovered and rectified before it could cause harm.METHODS: The context was a door-to-door survey to estimate the prevalence and burden of headache disorders in Pakistan. Data were collected from all four provinces of Pakistan by non-medical interviewers and collated centrally. Measures to ensure data integrity were preventative, detective and corrective. We carefully selected and trained the interviewers, set rules of conduct and gave specific warnings regarding the consequences of falsification. We employed two-fold fraud detection methods: comparative data analysis, and face-to-face re-contact with randomly selected participants. When fabrication was detected, data shown to be unreliable were replaced by repeating the survey in new samples according to the original protocol.RESULTS: Comparative analysis of datasets from the regions revealed unfeasible prevalences and gender ratios in one (Multan). Data fabrication was suspected. During a surprise-visit to Multan, of a random sample of addresses selected for verification, all but one had been falsely reported. The data (from 840 cases) were discarded, and the survey repeated with new interviewers. The new sample of 800 cases was demographically and diagnostically consistent with other regions.CONCLUSION: Fraud in community-based surveys is seldom reported, but no less likely to occur than in other fields of medical research. Measures should be put in place to prevent, detect and, where necessary, correct it. In this instance, had the data from Multan been pooled with those from other regions before analysis, a damaging fraud might have escaped notice. Source

Halvorsen T.G.,Norwegian University of Science and Technology | Sorensen T.M.,University of Oslo
Nuclear Physics B | Year: 2012

We propose a general formulation of simplicial lattice gauge theory inspired by the finite element method. Numerical tests of convergence towards continuum results are performed for several SU(2) gauge fields. Additionally, we perform simplicial Monte Carlo quantum gauge field simulations involving measurements of the action as well as differently sized Wilson loops as functions of β. © 2011 Elsevier B.V. Source

Halvorsen T.,Sintef | Martinussen P.E.,Norwegian University of Science and Technology
Social Science and Medicine | Year: 2014

Research on chronic obstructive pulmonary disease (COPD) that includes geographic information is important in order to improve care and appropriate allocation of resources to patients suffering from COPD. The purpose of this study is to investigate the geography of COPD and factors associated with the spatial patterns of COPD prevalence. Particular emphasis is put on the role of the local socioeconomic environment. Utilising information from the Norwegian Prescription Database on all lung medication prescribed in 2009 we identified 62,882 persons with COPD in the Norwegian population. Patterns of spatial clustering in the prevalence of COPD are clearly evident, even when age and gender are controlled for. Gender and age are strongly related to COPD risk. Socio-economic characteristics of the community such as education and unemployment are also significantly correlated with COPD risk. People living in rural parts of the country are generally associated with less risk than people in urban settings, and in particular people living in communities with high levels of farm and fisheries employment. © 2014 Elsevier Ltd. Source

Schielzeth H.,Bielefeld University | Husby A.,Norwegian University of Science and Technology
Annals of the New York Academy of Sciences | Year: 2014

A considerable challenge in evolutionary genetics is to understand the genetic mechanisms that facilitate or impede evolutionary adaptation in natural populations. For this, we must understand the genetic loci contributing to trait variation and the selective forces acting on them. The decreased costs and increased feasibility of obtaining genotypic data on a large number of individuals have greatly facilitated gene mapping in natural populations, particularly because organisms whose genetics have been historically difficult to study are now within reach. Here we review the methods available to evolutionary ecologists interested in dissecting the genetic basis of traits in natural populations. Our focus lies on standing genetic variation in outbred populations. We present an overview of the current state of research in the field, covering studies on both plants and animals. We also draw attention to particular challenges associated with the discovery of quantitative trait loci and discuss parallels to studies on crops, livestock, and humans. Finally, we point to some likely future developments in genetic mapping studies. © 2014 New York Academy of Sciences. Source

You J.,Christian Michelsen Research | Ebrahimi T.,Ecole Polytechnique Federale de Lausanne | Perkis A.,Norwegian University of Science and Technology
IEEE Transactions on Image Processing | Year: 2014

Contrast sensitivity of the human visual system to visual stimuli can be significantly affected by several mechanisms, e.g., vision foveation and attention. Existing studies on foveation based video quality assessment only take into account static foveation mechanism. This paper first proposes an advanced foveal imaging model to generate the perceived representation of video by integrating visual attention into the foveation mechanism. For accurately simulating the dynamic foveation mechanism, a novel approach to predict video fixations is proposed by mimicking the essential functionality of eye movement. Consequently, an advanced contrast sensitivity function, derived from the attention driven foveation mechanism, is modeled and then integrated into a wavelet-based distortion visibility measure to build a full reference attention driven foveated video quality (AFViQ) metric. AFViQ exploits adequately perceptual visual mechanisms in video quality assessment. Extensive evaluation results with respect to several publicly available eye-tracking and video quality databases demonstrate promising performance of the proposed video attention model, fixation prediction approach, and quality metric. © 1992-2012 IEEE. Source

Tonder K.,Norwegian University of Science and Technology
Tribology International | Year: 2010

Surface texturing effects on the properties of pivoted plane hydrodynamic bearings are studied by numerical simulation based on the Reynolds equation. The texturing, in the form of dimples, covers the whole bearing surface. The calculations employed are more dependable than those previously used by the author. It is found that under certain operating conditions, friction is increased but the specific load capacity is increased even more. This results in a reduction in the coefficient of friction. Dynamic coefficients such as lubricant film stiffness and damping may also be improved under certain conditions. However, it is found that conditions giving high stiffness also give high coefficients of friction. © 2010 Elsevier Ltd. Source

Simonsen I.,Norwegian University of Science and Technology
Physica Status Solidi (B) Basic Research | Year: 2010

The scattering of light from a weakly rough random silver surface characterized by a double rectangular power spectrum is studied by numerical simulations. This power spectrum can support both the enhanced back and forward scattering phenomena, which for weakly rough surfaces, are both related to the excitation of surface plasmon polaritons. Here we review these phenomena and present new results from a numerical study of the dependence of the diffuse scattering on the amplitudes (γi, i = 1, 2) of the two rectangular portions of the power spectrum. It is found that there exist an optimal range of ratios, γ2/γ1, over which forward scattering peaks can be observed. By just changing the correlations along the interface, while keeping all other parameters like roughness, polarization, and angle of incidence unchanged, the fraction of the incident light that is scattered diffusely can be as large as 16%, while for other parameters as small as 1%. Moreover, a change in the correlation function only, can result in a 3.5 times increase in the amount of light that is absorbed at the weakly rough metal interface (σ = 10 nm). © 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

Olsen Y.,Norwegian University of Science and Technology
Aquaculture Environment Interactions | Year: 2011

There is a growing concern about the ability to produce enough nutritious food to feed the global human population in this century. Environmental conflicts and a limited freshwater supply constrain further developments in agriculture; global fisheries have levelled off, and aquaculture may have to play a more prominent role in supplying human food. Freshwater is important, but it is also a major challenge to cultivate the oceans in an environmentally, economically and energyfriendly way. To support this, a long-term vision must be to derive new sources of feed, primarily taken from outside the human food chain, and to move carnivore production to a lower trophic level. The main aim of this paper is to speculate on how feed supplies can be produced for an expanding aquaculture industry by and beyond 2050 and to establish a roadmap of the actions needed to achieve this. Resources from agriculture, fish meal and fish oil are the major components of pellet fish feeds. All cultured animals take advantage of a certain fraction of fish meal in the feed, and marine carnivores depend on a supply of marine lipids containing highly unsaturated fatty acids (HUFA, with ≥3 double bonds and ≥20 carbon chain length) in the feed. The availability of HUFA is likely the main constraint for developing carnivore aquaculture in the next decades. The availability of fish meal and oil will decrease, and the competition for plant products will increase. New harvested resources are herbivore zooplankton, such as Antarctic krill and red feed, and new produced resources are macroalgae, transgenic higher HUFA-producing plants and bacterial biomass. These products are to a limited extent components of the human food chain, and all these resources will help to move cultured carnivores to lower trophic levels and can thereby increase the production capacity and the sustainability of the production. Mariculture can only become as successful as agriculture in the coming century if carnivores can be produced at around Trophic Level 2, based mainly on plant resources. There is little potential for increasing the traditional fish meal food chain in aquaculture. © Inter-Research 2011. Source

Krogstad P.-A.,Norwegian University of Science and Technology | Davidson P.A.,University of Cambridge
Journal of Fluid Mechanics | Year: 2010

There has been a longstanding debate as to whether the large scales in grid turbulence should be classified as of the Batchelor or Saffman type. In the former, the integral scales, u and l, satisfy u2l5 constant, while in Saffman turbulence we have u2l3 = constant. For strictly homogeneous turbulence the energy decay rates in these two types of turbulence differ, with u2 ̃ t10/7 in Batchelor turbulence and u2 ̃ t6/5 in Saffman turbulence. We present high-resolution measurements of grid turbulence taken in a large wind tunnel. The particularly large test section allows us to measure energy decay exponents with high accuracy. We find that the turbulence behind the grid is almost certainly of the Saffman type, with u2l 3 = constant. The measured energy decay exponent, however, is found to lie slightly below the theoretical prediction of u2 ̃ t 1.2. Rather we find u2 ̃ tn, with n = 1.130.02. This discrepancy is shown to arise from a weak temporal decay of the dimensionless energy dissipation coefficient, εl/u3, which is normally taken to be constant in strictly homogeneous turbulence, but which varies very slowly in grid turbulence. © 2010 Cambridge University Press. Source

Solli J.,Norwegian University of Science and Technology
Engineering Studies | Year: 2013

Standards and regulations can play a central role in policies to achieve environmentally sound and energy-efficient buildings. This paper sets out to explore how consulting engineers relate to standards designed to impose sustainability in the construction of new buildings and in waste management. The paper addresses four cases of engineering practices. The first case describes practical skills and tools involved in what the engineers considered as 'normal' practices when performing energy calculations in the development of new buildings. The second and third cases deal with energy in new buildings as well, but address practices that supported or enabled the engineers to go beyond minimum standards. Case four explores a heat production project and more specifically, how the engineer deals with solving a problem related to calculating energy substitution. Together, the cases represent situations with quite different degrees of uncertainty as to how to relate to standards, from relative certainty represented in the first case to relative uncertainty in the last case. We shall look closer at the practices such situations entail and how they constitute different types of consulting engineering practices. © 2013 © 2013 Taylor & Francis. Source

Cherubini F.,Norwegian University of Science and Technology | Jungmeier G.,Joanneum Research
International Journal of Life Cycle Assessment | Year: 2010

Background, aim, and scope: The availability of fossil resources is predicted to decrease in the near future: they are a non-renewable source, they cause environmental concerns, and they are subjected to price instability. Utilization of biomass as raw material in a biorefinery is a promising alternative to fossil resources for production of energy carriers and chemicals, as well as for mitigating climate change and enhancing energy security. This paper focuses on a biorefinery concept which produces bioethanol, bioenergy, and biochemicals from switchgrass, a lignocellulosic crop. Results are compared with a fossil reference system producing the same products/services from fossil sources. Materials and methods: The biorefinery system is investigated using a Life Cycle Assessment approach, which takes into account all the input and output flows occurring along the production chain. This paper elaborates on methodological key issues like land use change effects and soil N2O emissions, whose influence on final outcomes is weighted in a sensitivity analysis. Since climate change mitigation and energy security are the two most important driving forces for biorefinery development, the assessment has a focus on greenhouse gas (GHG) emissions and cumulative primary energy demand (distinguished into fossil and renewable), but other environmental impact categories (e.g., abiotic depletion, eutrophication, etc.) are assessed as well. Results: The use of switchgrass in a biorefinery offsets GHG emissions and reduces fossil energy demand: GHG emissions are decreased by 79% and about 80% of non-renewable energy is saved. Soil C sequestration is responsible for a large GHG benefit (65 kt CO2-eq/a, for the first 20 years), while switchgrass production is the most important contributor to total GHG emissions of the system. If compared with the fossil reference system, the biorefinery system releases more N2O emissions, while both CO2 and CH4 emissions are reduced. The investigation of the other impact categories revealed that the biorefinery has higher impacts in two categories: acidification and eutrophication. Discussion: Results are mainly affected by raw material (i.e., switchgrass) production and land use change effects. Steps which mainly influence the production of switchgrass are soil N2O emissions, manufacture of fertilizers (especially those nitrogen-based), processing (i.e., pelletizing and drying), and transport. Even if the biorefinery chain has higher primary energy demand than the fossil reference system, it is mainly based on renewable energy (i.e., the energy content of the feedstock): the provision of biomass with sustainable practices is then a crucial point to ensure a renewable energy supply to biorefineries. Conclusions: This biorefinery system is an effective option for mitigating climate change, reducing dependence on imported fossil fuels, and enhancing cleaner production chains based on local and renewable resources. However, this assessment evidences that determination of the real GHG and energy balance (and all other environmental impacts in general) is complex, and a certain degree of uncertainty is always present in final results. Ranges in final results can be even more widened by applying different combinations of biomass feedstocks, conversion routes, fuels, end-use applications, and methodological assumptions. Recommendations and perspectives: This study demonstrated that the perennial grass switchgrass enhances carbon sequestration in soils if established on set-aside land, thus, considerably increasing the GHG savings of the system for the first 20 years after crop establishment. Given constraints in land resources and competition with food, feed, and fiber production, high biomass yields are extremely important in achieving high GHG emission savings, although use of chemical fertilizers to enhance plant growth can reduce the savings. Some strategies, aiming at simultaneously maintaining crop yield and reduce N fertilization application through alternative management, can be adopted. However, even if a reduction in GHG emissions is achieved, it should not be disregarded that additional environmental impacts (like acidification and eutrophication) may be caused. This aspect cannot be ignored by policy makers, even if they have climate change mitigation objectives as main goal. © 2009 Springer-Verlag. Source

Ellingsen S.A.,Norwegian University of Science and Technology
Physics of Fluids | Year: 2012

It was recently shown theoretically that it is possible to pull a spherical dielectric body towards the source of a laser beam [J. Chen, J. Ng, Z. Lin, and C. T. Chan, "Optical pulling force," Nat. Photonics5, 531 (2011)], a result with immediate consequences to optical manipulation of small droplets. Optical pulling can be realized, e.g., using a diffraction-free Bessel beam, and is expected to be of great importance in manipulation of microscopic droplets in micro- and nanofluidics. Compared to conventional optical pushing, however, the ratio of optical net force to stress acting on a droplet is much smaller, increasing the importance of oscillations. We describe the time-dependent surface deformations of a water microdroplet under optical pulling to linear order in the deformation. Shape oscillations have a lifetime in the order of microseconds for droplet radii of a few micrometers. The force density acting on the initially spherical droplet is strongly peaked near the poles on the beam axis, causing the deformations to take the form of jet-like protrusions. © 2012 American Institute of Physics. Source

Ehlers S.,Norwegian University of Science and Technology | Tabri K.,Tallinn University of Technology
Marine Structures | Year: 2012

Ship collisions are increasingly simulated with numerical methods predicting the structural damage, respectively the ships' safety, in such accidental event. The latest analyses techniques can take the non-linear structural behaviour and the motions of the colliding vessels into account, however using time-consuming numerical models. Hence, a single dynamic collision can be analysed with a fair degree of accuracy, but at high computational cost. Therefore, this article presents a combined numerical and analytical procedure to assess ship collision damage with significantly lower computational cost. Numerical quasi-static collision simulations estimate the non-linear structural behaviour for a given vessel colliding at selected vertical locations. This provides the force versus penetration curves, which thus depends on the structural arrangement at the striking location. Hence, the semi-analytical collision analysis is calibrated based on these structural resistance curves in order to estimate the change in available energy for structural deformation considering different longitudinal striking locations and angles. As a result, the collision damage, respectively penetration depth and length, can be estimated for vessels of different dimensions and mass ratio's subjected to various collision situations if the presented procedure is applied. © 2012 Elsevier Ltd. Source

Aune I.,Norwegian University of Science and Technology | Moller A.,Nordic School of Public Health
Midwifery | Year: 2012

Objective: to increase our understanding of how pregnant women experience early ultrasound examination that includes a risk assessment for chromosomal anomalies and how such women perceive the test results. Design/setting: qualitative study at St. Olavs Hospital in Norway. Both pre- and post-examination interviews were conducted with ten pregnant women who underwent risk assessment for chromosomal anomalies. Grounded theory was used to analyse the results. Findings: the study generated a core category (I want a choice, but I don't want to decide), which related to the conflict between choice and decision making. There were also five main categories (existential choices, search for knowledge, anxiety, feeling of guilt and counselling and care). The main categories describe the complex feelings experienced by the women regarding the risk assessment. Factors contributing to the difficulty of choice included loss of control and coping, emotional connection to the fetus and social pressure. As the women sought independent choices without any external influence, they also felt greater responsibility. The women's understanding of the actual risk varied, and they used different types of logic and methods to evaluate the risk and reach a decision. Conclusions: the pregnant women in this study wanted prenatal diagnostic information and easy access to specialty services. Stress-related feelings and non-transparent information about the actual and perceived risks as well as personal moral judgments made the decision-making process complicated. Improved distribution of information and frequent contact with health professionals may help such women to make informed choices in accordance with their values and beliefs. © 2010 Elsevier Ltd. Source

Baas N.A.,Norwegian University of Science and Technology
International Journal of General Systems | Year: 2013

We discuss the nature of structure and organization and the process of making new things. Hyperstructures are introduced as binding and organizing principles, and we show how they can transfer from one situation to another. A guiding example is the hyperstructure of higher order Brunnian rings and similarly structured many-body systems. © 2013 Copyright Taylor and Francis Group, LLC. Source

Alsberg B.K.,Norwegian University of Science and Technology
Chemometrics and Intelligent Laboratory Systems | Year: 2012

Chemical images which are often computed from hyperspectral images contain the spatial distribution of chemical information of a scene. For many applications visualizing such images on computer screens is sufficient, however there are cases where there is a need to combine the chemical images more naturally with human vision. This is especially true for interactive work where chemical images are being rapidly updated to the user. Effective integration of spatial information in general from external sources with vision is a challenge. One approach is to overlay the view of the real physical world with computer-generated graphics as in augmented reality. However such cluttering of the visual field with computer-generated graphics may confuse the user and reduce functionality. Another is projecting the chemical images back onto the scene under study in order to render the chemical information . in situ to the user. This approach, however has challenges in connection with very small and very large scenes under investigation. An alternative approach is here investigated based on the possibility of enhancing the human vision system using a sensory substitution device. Such devices enables a person to sense spatial information conveyed through sensory channels other than the eye, such as hearing and sense of touch. Results presented support the claim that spatial chemical information from a hyperspectral camera can be conveyed to the brain through a sensory channel different from the eyes. As this is tested on a sighted subject it effectively provides an extension of the human vision system to incorporate chemical information which otherwise is invisible to the naked eye. © 2012 Elsevier B.V.. Source

Krogstie J.,Norwegian University of Science and Technology
Lecture Notes in Business Information Processing | Year: 2012

Processes modeling is done for a number of reasons in relation to enterprise modeling, business process modeling and information systems development in general, and this paper will give an overview of main approaches to different types of process modeling. Modeling approaches are structured according to the main modeling perspective being used. In conceptual modeling in general, one can identify 8 modeling perspectives; behavioral, functional, structural, goal-oriented, object-oriented, language action, organizational and topological. In the paper we will present both historical and current examples of process modeling according to these different perspectives, and discuss what perspectives are most appropriate to achieve the different goals of modeling. © 2012 Springer-Verlag Berlin Heidelberg. Source

Yurchenko D.,Heriot - Watt University | Naess A.,Norwegian University of Science and Technology | Alevras P.,Heriot - Watt University
Probabilistic Engineering Mechanics | Year: 2013

This paper considers rotational motion of a nonlinear Mathieu equation with a narrow-band stochastic excitation. The path integration technique is utilized to obtain the joint probability density function of the response, which is used to construct domains of rotational motion in parameter space. © 2012 Elsevier Ltd. All rights reserved. Source

Natland Fagerhaug T.,Norwegian University of Science and Technology
BMC public health | Year: 2013

Recent studies suggest that lactation has long-term effects on risk for cardiovascular disease in women, but the effects on cardiovascular mortality are less well known. In a Norwegian population-based prospective cohort study, we studied the association of lifetime duration of lactation with cardiovascular mortality in 21,889 women aged 30 to 85 years who attended the second Nord-Trøndelag Health Survey (HUNT2) in 1995-1997. The cohort was followed for mortality through 2010 by a linkage with the Cause of Death Registry. Adjusted hazard ratios (HR) for death from all causes and cardiovascular disease were calculated using Cox regression. During follow-up, 1,246 women died from cardiovascular disease. Parous women younger than 65 years who had never lactated had a higher cardiovascular mortality than the reference group of women who had lactated 24 months or more (HR 2.77, 95% confidence interval [CI]: 1.28, 5.99). There was some evidence of a U-shaped association, where women who reported lactating 7-12 months had a HR of 0.55 (95% CI: 0.27, 1.09). No clear associations were observed among women 65 years or older. Excess cardiovascular mortality rates were observed among parous women younger than 65 years who had never lactated. These findings support the hypothesis that lactation may have long-term influences on maternal cardiovascular health. Source

Rekkedal A.M.,Norwegian University of Science and Technology
Scandinavian Journal of Disability Research | Year: 2014

The objective of this study is to examine factors that can explain teachers' use of assistive listening devices in inclusive schools for pupils with hearing loss (HL). Assistive listening devices, such as teacher-microphones and pupil-microphones, can ensure an enhanced listening environment for such pupils and thus induce a higher level of participation in the teaching. The study included 167 teachers of pupils with HL in fifth through tenth grades. The analyses indicated that factors related to the teachers, pupils, parents and technology influenced the teachers' use of microphones. Teachers with positive attitudes toward the microphones tend to integrate them regularly in classroom communications compared with teachers who are negatively inclined. Frequent use of the microphones also occurred if pupils had severe HL. Furthermore, parents who tend to be highly involved in the children's school performance indirectly affected the teachers' microphone use. Additionally, frequent use of pupil-microphones seems to be dependent of the number of microphones; a high-density of microphones promoted their use. © 2013 Nordic Network on Disability Research. Source

Linder J.,Norwegian University of Science and Technology
Physical Review B - Condensed Matter and Materials Physics | Year: 2013

Using the Lagrangian formalism, we solve analytically the equations of motion for current-induced domain wall dynamics in a ferromagnet with Rashba spin-orbit coupling. An exact solution for the domain wall velocity is provided, including the effect of nonequilibrium conduction electron spin density, Gilbert damping, and the Rashba interaction parameter. We demonstrate explicitly that the influence of spin-orbit interaction can be qualitatively different from the role of nonadiabatic spin torque in the sense that the former is sensitive to the chirality of the domain wall whereas the latter is not: the domain wall velocity shows a reentrant behavior upon changing the chirality of the domain wall. This could be used to experimentally distinguish between the spin-orbit and nonadiabatic contribution to the wall speed. A quantitative estimate for the attainable domain wall velocity is given, based on an experimentally relevant set of parameters for the system. © 2013 American Physical Society. Source

Ellingsen S.A.,Norwegian University of Science and Technology
Journal of the Optical Society of America B: Optical Physics | Year: 2013

The theory for linear deformations of fluid microparticles in a laser beam of Gaussian profile is presented, when the beam focus is at the particle center as in optical trapping. Three different fluid systems are considered: water microdroplet in air, air microbubble in water, and a special oil-emulsion in water system used in experiments with optical deformation of fluid interfaces. We compare interface deformations of the three systems when illuminated by wide (compared to particle radius) and narrow laser beams and analyze differences. Deformations of droplets are radically different from bubbles under otherwise identical conditions, due to the opposite lensing effect (converging and diverging, respectively) of the two; a droplet is deformed far more than a bubble, cetera paribus. Optical contrast is found to be of great importance to the shape obtained when comparing the relatively low-contrast oil-emulsion system to that of water droplets. We finally analyze the dynamics of particle motion when the laser beam is turned on, and compare a static beam to the case of a short pulse. The very different surface tension coefficient implies a very different time scale for dynamics: microseconds for the water-air interface and tens of milliseconds for the oil-emulsion. Surface oscillations of a water microdroplet are found always to be underdamped, while those of the oil-emulsion are overdamped; deformations of a microbubble can be either, depending on physical parameters. © 2013 Optical Society of America. Source

Baas N.A.,Norwegian University of Science and Technology
International Journal of General Systems | Year: 2013

We extend the well-known Borromean and Brunnian rings to new higher order versions. Then we suggest an extension of the connection between Efimov states in cold gases and Borromean and Brunnian rings to these new higher order links. This gives rise to a whole new hierarchy of possible states with Efimov states at the bottom. © 2013 Copyright Taylor and Francis Group, LLC. Source

Good C.,Norwegian University of Science and Technology
Renewable and Sustainable Energy Reviews | Year: 2016

In a hybrid photovoltaic-thermal (PV/T or PVT) module, electricity and thermal energy are generated simultaneously in the same module. By combining a PV module and a solar thermal collector, more of the solar radiation can be harvested, and the total efficiency of the module is increased. The combination of two technologies in one module also has the potential to reduce the use of materials and the required space. In order to assess and quantify these possibilities, several research groups have presented life cycle assessments (LCA) of different PV/T concepts and installations. This paper presents a review of the published results, and aims to find a common ground. In general, the payback time for both energy and greenhouse gas emissions of the PV/T systems are much shorter than their expected lifetime. However, due to the use of different methods and unclear data sources, it is difficult to make any wide-ranging conclusions about the environmental impact of PV/T modules. © 2015 Elsevier Ltd. Source

Li Y.J.,Sintef | Zhang W.Z.,Tsinghua University | Marthinsen K.,Norwegian University of Science and Technology
Acta Materialia | Year: 2012

The habit plane, orientation relationship (OR) and interfacial structure between the plate-shaped Al 6(Mn,Fe) dispersoids and Al matrix in an AA 5182 alloy have been systematically studied by transmission electron microscopy, selected-area electron diffraction and crystallographic simulation. The published OR data about the dispersoids precipitated in different Al alloys has been critically assessed. A precise OR has been determined as (0 0 1) p//(3 -1 5) m and [-1 1 0] p//[2 1 -1] m, while the habit planes are determined as (0 0 1) p and (3 -1 5) m. The OR and habit plane have been discussed in terms of the Δg approach. The dislocation arrangements at the interphase boundary of the habit planes are calculated by using O-lattice theory, which has been used to explain the mechanism of the OR selection and morphology development of dispersoids. It is revealed that an atom-to-atom matching exists in the good matching regions between the dislocations in the habit plane. © 2012 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Source

Cheng R.,University of Texas at Austin | Xiao J.,Fudan University | Niu Q.,University of Texas at Austin | Niu Q.,Peking University | Brataas A.,Norwegian University of Science and Technology
Physical Review Letters | Year: 2014

Spin pumping and spin-transfer torques are two reciprocal phenomena widely studied in ferromagnetic materials. However, pumping from antiferromagnets and its relation to current-induced torques have not been explored. By calculating how electrons scatter off a normal metal-antiferromagnetic interface, we derive pumped spin and staggered spin currents in terms of the staggered field, the magnetization, and their rates of change. For both compensated and uncompensated interfaces, spin pumping is of a similar magnitude as in ferromagnets with a direction controlled by the polarization of the driving microwave. The pumped currents are connected to current-induced torques via Onsager reciprocity relations. © 2014 American Physical Society. Source

Bar N.,Norwegian University of Science and Technology
Canadian Journal of Fisheries and Aquatic Sciences | Year: 2014

Starvation periods are common for many animals, including fish, birds, and mammals. Many fish species exhibit extraordinary resilience to prolonged starvation, but the reasons for that and the mechanisms employed during these periods are poorly understood. This study shows that similar to mammals and birds, many fish species undergo three phases during starvation: (I) a short transient phase, (II) a long, protein conservation steady state phase with mainly fat oxidation as the primary energy source, and (III) a shift to protein mobilization as a main energy source. These starvation states and their transitions were quantified by a meta-analysis of large empirical data available in the literature, revealing that low critical levels of fat reserves trigger the transition to the third state. The critical fat level, denoted as γ (percentage of total lipid in body mass), ranges between 0.7% and 5%, depending on the species. It appears that these transitions in the energy mobilization phases are regulated by hormonal changes, including growth hormone (GH), leptin, cortisol, and ghrelin, but the exact mechanisms are still unclear and should be further investigated. Simulations in silico of starvation periods at various temperatures using a dynamic model indicated that temperature affects the length of Phase II because of changes in protein metabolism, with consequences on the ability to withstand prolonged starvation. © 2014 Can. J. Fish. Aquat. Sci. All rights reserved. Source

Pharoah J.G.,Queens University | Burheim O.S.,Norwegian University of Science and Technology
Journal of Power Sources | Year: 2010

This paper presents 2D thermal model of a fuel cell to elucidate some of the issues and important parameters with respect to temperature distributions in PEM fuel cells. A short review on various properties affecting the temperature profile and the heat production in the polymer electrolyte fuel cell is included. At an average current density of 1 A cm-2, it is found that the maximum temperature of the MEA is elevated by between 4.5 and 15 K compared to the polarisation plate temperature. The smallest deviation corresponds to one dimensional transport, while the largest corresponds to the two dimensional transport considering anisotropic thermal conductivity. The two dimensional thermal model further predicts increased lost work. While most of the heat generation is allocated in the cathode, it is shown that the heat effect may be balanced by the water phase change in the anode. The most significant factor in determining the temperature distribution is the gas channel geometry (width and channel type), followed by the thermal conductivity of the porous transport layer and state of the water in the cell. © 2010 Elsevier B.V. All rights reserved. Source

Mjolstad O.C.,Norwegian University of Science and Technology
European heart journal cardiovascular Imaging | Year: 2013

To study the feasibility and reliability of pocket-size hand-held echocardiography (PHHE) by medical residents with limited experience in ultrasound. A total of 199 patients admitted to a non-university medical department were examined with PHHE. Six out of 14 medical residents were randomized to use a focused protocol and examine the heart, pericardium, pleural space, and abdominal large vessels. Diagnostic corrections were made and findings were confirmed by standard diagnostics. The median time consumption for the examination was 5.7 min. Each resident performed a median of 27 examinations. The left ventricle was assessed to satisfaction in 97% and the pericardium in all patients. The aortic and atrioventricular valves were assessed in at least 76% and the abdominal aorta in 50%, respectively. Global left-ventricular function, pleural, and pericardial effusion showed very strong correlation with reference method (Spearman's r ≥ 0.8). Quantification of aortic stenosis and regurgitation showed strong correlation with r = 0.7. Regurgitations in the atrioventricular valves showed moderate correlations, r = 0.5 and r = 0.6 for mitral and tricuspid regurgitation, respectively, similar to dilatation of the left atrium (r = 0.6) and detection of regional dysfunction (r = 0.6). Quantification of the abdominal aorta (aneurysmatic or not) showed strong correlation, r = 0.7, while the inferior vena cava diameter correlated moderately, r = 0.5. By adding a PHHE examination to standard care, medical residents were able to obtain reliable information of important cardiovascular structures in patients admitted to a medical department. Thus, focused examinations with PHHE performed by residents after a training period have the potential to improve in-hospital diagnostic procedures. Source

Medby C.,Norwegian University of Science and Technology
Shock | Year: 2014

Crystalloids and colloids are used in prehospital fluid resuscitation to replace blood loss and preserve tissue perfusion until definite surgical control of bleeding can be achieved. However, large volumes of fluids will increase bleeding by elevating blood pressure, dislodging blood clots, and diluting coagulation factors and platelets. Hypotensive fluid resuscitation strategies are used to avoid worsening of uncontrolled bleeding. This is largely supported by animal studies. Most clinical evidence suggests that restricting fluid therapy is associated with improved outcome. Remote damage control resuscitation emphasizes the early use of blood products and restriction of other fluids to support coagulation and tissue oxygenation. Controversy regarding the optimal choice and composition of resuscitation fluids is ongoing. Compared with crystalloids, less colloid is needed for the same expansion of intravascular volume. On the other hand, colloids may cause coagulopathy not only related to dilution. The most important advantage of using colloids is logistical because less volume and weight are needed. In conclusion, prehospital fluid resuscitation is considered the standard of care, but there is little clinical evidence supporting the use of either crystalloids or colloids in remote damage control resuscitation. Alternative resuscitation fluids are needed. Copyright © 2014 by the Shock Society. Source

Haavik T.K.,Norwegian University of Science and Technology
Safety Science | Year: 2014

This article explores the philosophical foundations of a selection of safety science approaches through investigating the modus operandi of their development and use. It explicitly addresses the importance of distinguishing ontology from epistemology, a claim expressed in the call for papers for this special issue. The importance of rigorous methods when comparing scientific traditions is emphasised, a rigorousness that in this article is ensured by analysing the different safety science approaches from the same point of reference. The underlying ontology of Normal Accident Theory, High Reliability Organisations and Resilience Engineering is explored, as seen through the lens of the prevailing ontology of science and technology studies (STS). The article draws two conclusions. The first is of a theoretical nature: Slightly counterintuitive perhaps, especially considering the enduring debate between Normal Accident Theory and High Reliability Organisations, the three approaches are all found to be based on the same sociotechnical constructivist ontology. The second conclusion explains the ontological difference between the safety theoretical approaches as not grounded in their philosophical underpinnings, but in the way that the results from the 'original' studies are adopted and operationalised. This conclusion also illuminates a common and fundamental relational aspect of these safety theories and the danger of compromising their philosophical underpinnings when key concepts of the approaches are decontextualised, black-boxed and adopted uncritically in a new context. © 2013 Elsevier Ltd. Source

Kolbeinsen L.,Norwegian University of Science and Technology
Steel Research International | Year: 2010

The concept of DRI is understood as reduction of iron ore (oxide) without the occurrence of a liquid phase, and where the means of reduction is either coal or natural gas. This method for making iron has existed since the Iron Age, but had its renaissance in the 1960s. Today's DRI production is of a magnitude of 60 million metric tons a year, and is rapidly growing. The MIDREX ® and HyL® processes are based on reduction in a packed bed (shaft furnace), something that requires the ore to be pelletized. The reduction of fine grain ore directly, typically fluidized beds with multiple reactors in series like in the FINMET® process, constitutes another process family. In both cases the gas doing the reduction-work will be a synthesis-gas (SynGas/SG), but with variations in the H2/CO-ratio from process to process. Use of the top-gas from the reduction as an oxygen source in the SynGas generation is common. Mathematical modelling is considered essential for development and optimization of such processes. Reduction of single pellets can be described using various models, e.g. the well known Shrinking Core Model (SCM). The classical SCM needs to be modified both with respect to the solids to include the intermediate products magnetite and wü stite that exist between hematite and metallic iron, but also with respect to the gas to handle two different reactants; hydrogen and carbon monoxide, and should also include the possible internal gas reactions like the water gas shift reaction (WGSR). The use of oxygen potentials can replace gas compositions in modelling of such systems. In this paper a model for the reduction of a single iron ore pellet is described; and further a description is given of how such a model is incorporated into a full process model as well as experimental methods of how to determine model parameters. © 2010 Wiley-VCH Verlag GmbH & Co. Source

Karimirad M.,Norwegian University of Science and Technology
Scientia Iranica | Year: 2010

Like other offshore structures, floating wind turbines are subjected to stochastic wave and wind loads that cause a dynamic response in the structures. Wind turbines should be designed for different conditions, such as Operational and Survival conditions. In high sea states, the response can be quite different from the operational condition. The present paper deals with coupled wave and wind induced motion in harsh conditions, up to 15 m significant wave height and 50 m/sec average wind speed. There are several ways to deal with the dynamic response of floating wind turbines. The Coupled Time domain dynamic response analysis for a moored spar wind turbine subjected to wave and wind loads is carried out using DeepG. DeepC is well known software for calculating the coupled dynamic response of moored floating structures. The aerodynamic forces on a parked wind turbine are calculated, based on the strip theory, and imported to the Deep C through a MATLAB interface. At each time step, the relative wind velocity, based on the response of the structure is calculated. © Sharif University of Technology, April 2010. Source

Gansmo H.J.,Norwegian University of Science and Technology
Building Research and Information | Year: 2012

How can researchers and planners best facilitate the transition to low-carbon societies? In particular, can they initiate better dialogue in order to foster stakeholder engagement in planning, building and living in low-carbon settlements? These challenges inform a municipal planning process for a new neighbourhood in Trondheim, Norway: Brset, as well as for an interdisciplinary research project exploring the role of action research in supporting the transition to low-carbon societies. The processes are described for identifying the central actors and applying the dialogue strategies in the early planning project phase. Researchers and planners collaborated to contribute to new knowledge production and practice to support the transition to low-carbon societies. The utility of the co-produced results is their potential contribution to both standards of rigour as well as the timely dissemination of research and knowledge sharing within and across research communities and to different stakeholders involved in the project. This case study provides interesting lessons about why and how other projects can consider similar action research processes as a viable approach for sustaining the transition to low-carbon economies, particularly in the early planning phase. © 2012 Taylor & Francis. Source

Borges K.,University of Queensland | Sonnewald U.,Norwegian University of Science and Technology
Epilepsy Research | Year: 2012

The triglyceride of heptanoate (C7 fatty acid), triheptanoin, is a tasteless oil used to treat rare metabolic disorders in USA and France. Heptanoate is metabolized by β-oxidation to provide propionyl-CoA, which after carboxylation can produce succinyl-CoA, resulting in anaplerosis - the refilling of the tricarboxylic acid cycle. Heptanoate is also metabolized by the liver to the C5 ketones, β-ketopentanoate and/or β-hydroxypentanoate, which are released into the blood and thought to enter the brain via monocarboxylate transporters. Oral triheptanoin has recently been discovered to be reproducibly anticonvulsant in acute and chronic mouse seizures models. However, current knowledge on alterations of brain metabolism after triheptanoin administration and anaplerosis via propionyl-CoA carboxylation in the brain is limited. This review outlines triheptanoin's unique anticonvulsant profile and its clinical potential for the treatment of medically refractory epilepsy. Anaplerosis as a therapeutic approach for the treatment of epilepsy is discussed. More research is needed to elucidate the anticonvulsant mechanism of triheptanoin and to reveal its clinical potential for the treatment of epilepsy and other disorders of the brain. © 2011 Elsevier B.V. Source

Vigran T.E.,Norwegian University of Science and Technology
Applied Acoustics | Year: 2012

For the determination of the transmission loss of samples in an impedance tube, two different approaches is found in the literature, one based on determining the full transfer matrix (TM method) of the acoustic element, the other based on the wavefield decomposition theory (WD method). In this paper both methods are implemented and measured results are compared using samples which includes different types of perforated plates, also combined with porous material. Measurements are conducted in a tube of square cross section with dimensions 200 × 200 mm, thereby limiting the workable frequency range upwards to approximately 850 Hz. The main purpose of the paper is, however, to compare measured results with predictions using the transfer matrix method. For a bare plate with cylindrical apertures two models are compared as well; a "classical" one and another based on modeling the perforated plate as a porous material having a rigid frame. As for these transmission loss measurements, the two measurement approaches turn out to give identical results within the numerical accuracy. The fit between measured and predicted results are reasonably good with a maximum deviation mostly within 2 dB. © 2011 Elsevier Ltd. All rights reserved. Source

Djuric N.,Sintef | Novakovic V.,Norwegian University of Science and Technology
Energy and Buildings | Year: 2012

The aim of the study was to identify driving variables of energy use in a low energy office building by integrating building energy management system (BEMS) and energy use data. To take a further step towards zero emission buildings, it is necessary to identify what contributes the most to building energy use. Further, the idea was to encourage a smart use of BEMS data for energy use analysis. Multivariable analysis was used for the data analysis. Databases of 76 and 41 variables respectively, which included occupancy level, control signals, and water and air temperatures, were used to explain heating, electricity, and fan energy use. The results showed that important variables were different for different months in the case of heating energy use. The total electricity and fan electricity use could be defined with the same variables in different months. The total electricity use could be defined by using occupancy level and input fan signals. The suggested approach could be used by building operators to identify opportunities for decreasing energy use and for energy use estimation when data are lost due to data transmission issues or other problems. A relationship between building information and energy use was established. © 2011 Elsevier B.V. Source

Dal L.A.,University of Oslo | Kachelriess M.,Norwegian University of Science and Technology
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We calculate the antideuteron yield in dark matter annihilations on an event-by-event basis using the herwig++ MonteCarlo generator. We present the resulting antideuteron fluxes for quark and gauge boson final states. As deuteron production in the coalescence model depends on momentum differences between nucleons that are small compared to Λ QCD, it is potentially very sensitive to the hadronization model employed. We therefore compare our antideuteron yields to earlier results based on pythia, thereby estimating their uncertainties. We also briefly discuss the importance of n>2 final states for annihilations of heavy dark matter particles. © 2012 American Physical Society. Source

Andersen J.O.,Norwegian University of Science and Technology | Andersen J.O.,Niels Bohr Institute
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2012

We use chiral perturbation theory for SU(2) to compute the leading loop corrections to the thermal mass of the pions and the pion decay constant in the presence of a constant magnetic field B. The magnetic field gives rise to a splitting between M π0 and Mπ ± as well as F π0 and Fπ ±. We also calculate the free energy and the quark condensate to next-to-leading order in chiral perturbation theory. The results suggest that the critical temperature T c for the chiral transition is larger in the presence of a constant magnetic field, in agreement with most model calculations but in disagreement with recent lattice calculations. © 2012 American Physical Society. Source

Vagia M.,Norwegian University of Science and Technology
ISA Transactions | Year: 2013

In this study, an adaptive robust tracking control scheme for a nanomechanical beam is proposed. The mathematical nanobeam model takes into consideration the presence of parametric uncertainties, and external disturbances, and fringing field effects and intermolecular forces, are also incorporated. The proposed backstepping controller is enhanced with an adaptive dynamic surface technique and an H∞ control scheme. The overall effectiveness of the designed controller is checked and illustrated with the presented results. These results show that the desired transient output tracking performance is achieved, and that the closed loop system exhibits good robustness to system uncertainties. Particular attention has been paid, so as to identify any relevance between the variations in the controller's design parameter and the system's output response and performance. © 2012 ISA. Source

Brataas A.,Norwegian University of Science and Technology | Kent A.D.,New York University | Ohno H.,Tohoku University
Nature Materials | Year: 2012

The magnetization of a magnetic material can be reversed by using electric currents that transport spin angular momentum. In the reciprocal process a changing magnetization orientation produces currents that transport spin angular momentum. Understanding how these processes occur reveals the intricate connection between magnetization and spin transport, and can transform technologies that generate, store or process information via the magnetization direction. Here we explain how currents can generate torques that affect the magnetic orientation and the reciprocal effect in a wide variety of magnetic materials and structures. We also discuss recent state-of-the-art demonstrations of current-induced torque devices that show great promise for enhancing the functionality of semiconductor devices. © 2012 Macmillan Publishers Limited. All rights reserved. Source

Grosse S.,Norwegian University of Science and Technology
Toxicology in vitro : an international journal published in association with BIBRA | Year: 2013

Silver nanoparticles (AgNPs) are among the most widely commercialised engineered nanomaterials, because of their antimicrobial properties. They are already commonly used in medical devices, household products and industry. Concerns have been raised about potential adverse health effects due to increasing dispersion of AgNPs in the environment. The present study examined the cytotoxic effects of spherical, citrate-coated AgNPs (10, 50 and 100 nm) in rat brain endothelial (RBE4) cells and investigated whether the observed effects can be explained by the intrinsic toxicity of the particles or the silver ions released from the particles. The results indicated that exposure of RBE4 cells to AgNPs lead to significant reduction in dye uptake as measured with the Neutral red (NR) assay. The effect was found to be related to particle size, surface area, dose and exposure time. In contrast, silver ions increased NR uptake (ca. 10%) in RBE4 cells after 1h, while a reduction in NR uptake was observed after 24h exposure at high concentrations (20-30 μM). Colony formation, as an indicator of proliferation ability, was completely inhibited by AgNPs at concentrations higher than 1 μg/ml. Silver ions had less effect on the colony formation of RBE4 cells than AgNPs. Copyright © 2012 Elsevier Ltd. All rights reserved. Source