| 191. |
- Rónaszéki, Aladár, et al.
(författare)
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Pharmacological cardioversion of atrial fibrillation--a double-blind, randomized, placebo-controlled, multicentre, dose-escalation study of AZD1305 given intravenously.
- 2011
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Ingår i: Europace : European pacing, arrhythmias, and cardiac electrophysiology : journal of the working groups on cardiac pacing, arrhythmias, and cardiac cellular electrophysiology of the European Society of Cardiology. - : Oxford University Press (OUP). - 1532-2092.
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Tidskriftsartikel (refereegranskat)abstract
- Aim AZD1305 is a combined ion channel blocker developed for the treatment of atrial fibrillation (AF). The aim of this study was to determine whether AZD1305 was effective in converting AF to sinus rhythm (SR). Methods and results Patients with AF episodes of duration 3 h to 3 months were randomized in a 3:1 ratio to receive a maximum 30 min intravenous infusion of AZD1305 or matching placebo. The primary efficacy endpoint was the proportion of patients converting within 90 min of the start of infusion, after which patients who had not converted were to undergo direct current (DC) cardioversion. Four ascending AZD1305 dose groups were assigned sequentially, with dose rates of 50, 100, 130, and 180 mg/h. A total of 171 patients were randomized. Pharmacological conversion was achieved in 0 of 43 patients (0%) in the placebo group, and in 2 of 26 (8%; P= 0.14 vs. placebo), 8 of 45 (18%; P= 0.006), 17 of 45 (38%; P< 0.001), and 6 of 12 patients (50%; P< 0.001) in AZD1305 dose groups 1-4, respectively. Maximum QTcF (QT interval corrected according to Fridericia's formula) generally increased dose-dependently up to a plateau, although there was wide variation between patients. Two patients experienced torsade de pointes (TdP): one patient without symptoms in dose group 3, and one patient requiring DC defibrillation in dose group 4. Both patients recovered without sequelae. Conclusions AZD1305 was effective in converting AF to SR, but was associated with QT prolongation and TdP. The benefit-risk profile was judged as unfavourable and the AZD1305 development programme was discontinued. Clinical trial registration: http://clinicaltrials.gov identifier NCT00915356.
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| 192. |
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| 193. |
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| 194. |
- Sandström, Carl, 1978, et al.
(författare)
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A two-scale finite element formulation of Stokes flow in porous media
- 2013
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Ingår i: Computer Methods in Applied Mechanics and Engineering. - : Elsevier BV. - 0045-7825. ; 261, s. 96-104
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Tidskriftsartikel (refereegranskat)abstract
- Seepage through saturated porous material with an open pore system is modeled as a non-linear Stokes flow through a rigid matrix. Based on variationally consistent homogenization, the resulting macroscale problem becomes a Darcy-type flow. The prolongation of the Darcy flow fulfills a macrohomogeneity condition, which in a Galerkin context implies a symmetric macroscale problem. The homogenization is of 1st order and periodic boundary conditions are adopted on a Representative Volume Element. A nonlinear nested multiscale technique, in which the subscale problem is used as a constitutive model, is devised. In the presented numerical investigation, the effects of varying physical parameters as well as of the discretization are considered. In particular, it is shown that the two-scale results agree well with those of the fully resolved fine-scale problem.
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| 195. |
- Sandström, Carl, 1978, et al.
(författare)
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Homogenization of Stokes Flow in Porous Media
- 2012
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Ingår i: ECCOMAS 2012, European Congress on Computational Methods in Science and Engineering, (1 p. abstract).
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 196. |
- Sandström, Carl, 1978, et al.
(författare)
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Multiscale modeling of porous media
- 2011
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Ingår i: Proceedings of NSCM-24, the 24th Nordic Seminar on Computational Mechanics. ; , s. 111-114
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Konferensbidrag (refereegranskat)
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| 197. |
- Sandström, Carl, 1978, et al.
(författare)
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MULTISCALE MODELING OF POROUS MEDIA
- 2010
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Ingår i: Proceedings of NSCM-23, Anders Eriksson och Gunnar Tibert, Nordic Seminar on Computational Mechanics, Sockholm, 21-22 October 2010. - 0348-467X. ; 2010, s. 177-180
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Konferensbidrag (refereegranskat)abstract
- Homogenization of flow in porous media is studied. The continuity equation in conjunction with Darcy’s law as a constitutive relation on the macroscale, where the permeability is a function of the pressure gradient, is applied to a macroscopic domain. On the heterogenousmesoscale, a Stokes flow problem is formulated on a Representative Volume Element with a prescribed pressure gradient and suitable boundary condition. The numerical procedure for finite element simulations of the two-scale problem is outlined and illustrated by a few exampleproblems.
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| 198. |
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| 199. |
- Schmidt, Kenneth A., et al.
(författare)
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Consequences of information use in breeding habitat selection on the evolution of settlement time
- 2015
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Ingår i: Oikos. - : Wiley. - 1600-0706 .- 0030-1299. ; 124:1, s. 69-80
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Tidskriftsartikel (refereegranskat)abstract
- The role of temporal changes and spatial variability in predation risk and prey's means of mitigating such risks is poorly understood in the context of potential threats of global climate change for migratory birds. Yet nest predation, for example, represents a primary source of reproductive mortality in birds. To assess risk birds must spend time prospecting potential breeding sites for cues or signals of predator presence. However, competition for breeding sites with advantage to prior residency poses an evolutionary dilemma as individuals also benefit from early settling. We develop a model to examine adaptive prospecting time for predator cues on breeding grounds characterized by spatial heterogeneity in nest predation risk. We study how populations respond to environmental change represented by variation in habitat specific levels of nest predation, habitat composition, population vital rates, and availability of information (via prospecting) in the form of acoustic predator cues. We identify two mechanisms that regulate and buffer impacts of environmental change on populations. First, the adaptive response to lower population abundance under deteriorating environmental conditions is to increase prospecting time, which in turn increases individuals nest success to counteract population declines. This occurs because reduced competition for sites decreases the benefit of early settlement. Second, per capita success in site choice increases during population declines owing to reduced competition that increases the availability of good sites. We also show that the increased benefit to settling early when competition increases can lead to the paradoxical result that with greater spatial heterogeneity, less effort is placed on discerning good and bad sites. Our analysis thus contributes several novel results by which nest predation, settlement phenology, prospecting time and information gathering can influence species capacity to adapt to changing environments.
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| 200. |
- Schmidt, Kenneth A., et al.
(författare)
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Information-Mediated Allee Effects in Breeding Habitat Selection
- 2015
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Ingår i: American Naturalist. - : University of Chicago Press. - 0003-0147 .- 1537-5323. ; 186:6, s. 162-171
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Tidskriftsartikel (refereegranskat)abstract
- Social information is used widely in breeding habitat selection and provides an efficient means for individuals to select habitat, but the population-level consequences of this process are not well explored. At low population densities, efficiencies may be reduced because there are insufficient information providers to cue high-quality habitat. This constitutes what we call an information-mediated Allee effect. We present the first general model for an information-mediated Allee effect applied to breeding habitat selection and unify personal and social information, Allee effects, and ecological traps into a common framework. In a second model, we consider an explicit mechanism of social information gathering through prospecting on conspecific breeding performance. In each model, we independently vary personal and social information use to demonstrate how dependency on social information may result in either weak or strong Allee effects that, in turn, affect population extinction risk. Abrupt transitions between outcomes can occur through reduced information transfer or small changes in habitat composition. Overall, information-mediated Allee effects may produce positive feedbacks that amplify population declines in species that are already experiencing environmentally driven stressors, such as habitat loss and degradation. Alternatively, social information has the capacity to rescue populations from ecological traps.
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