| 1. |
- Elmhagen, Bodil, 1973-, et al.
(författare)
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Top predators, mesopredators and their prey : interference ecosystems along bioclimatic productivity gradients
- 2010
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Ingår i: Journal of Animal Ecology. - : Wiley. - 0021-8790 .- 1365-2656. ; 79:4, s. 785-794
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Tidskriftsartikel (refereegranskat)abstract
- 1. The Mesopredator Release Hypothesis (MRH) suggests that top predator suppression of mesopredators is a key ecosystem function with cascading impacts on herbivore prey, but it remains to be shown that this top-down cascade impacts the large-scale structure of ecosystems.2. The Exploitation Ecosystems Hypothesis (EEH) predicts that regional ecosystem structures are determined by top-down exploitation and bottom-up productivity. In contrast to MRH, EEH assumes that interference among predators has a negligible impact on the structure of ecosystems with three trophic levels.3. We use the recolonisation of a top predator in a three-level boreal ecosystem as a natural experiment to test if large-scale biomass distributions and population trends support MRH. Inspired by EEH, we also test if top-down interference and bottom-up productivity impact regional ecosystem structures.4. We use data from the Finnish Wildlife Triangle Scheme which has monitored top predator (lynx Lynx lynx), mesopredator (red fox Vulpes vulpes) and prey (mountain hare Lepus timidus) abundance for 17 years in a 200 000 km2 study area which covers a distinct productivity gradient.5. Fox biomass was lower than expected from productivity where lynx biomass was high, while hare biomass was lower than expected from productivity where fox biomass was high. Hence, where interference controlled fox abundance, lynx had an indirect positive impact on hare abundance as predicted by MRH. The rates of change indicated that lynx expansion gradually suppressed fox biomass.6. Lynx status caused shifts between ecosystem structures. In the “interference ecosystem”, lynx and hare biomass increased with productivity whilst fox biomass did not. In the “mesopredator release ecosystem”, fox biomass increased with productivity but hare biomass did not. Thus, biomass controlled top-down did not respond to changes in productivity. This fulfils a critical prediction of EEH.7. We conclude that the cascade involving top predators, mesopredators and their prey can determine large-scale biomass distribution patterns and regional ecosystem structures. Hence, interference within trophic levels has to be taken into account to understand how terrestrial ecosystem structures are shaped.
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| 2. |
- Sorensen, Per Soelberg, et al.
(författare)
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Simvastatin as add-on therapy to interferon beta-1a for relapsing-remitting multiple sclerosis (SIMCOMBIN study): a placebo-controlled randomised phase 4 trial.
- 2011
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Ingår i: Lancet neurology. - 1474-4465. ; 10:8, s. 691-701
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Treatment of relapsing-remitting multiple sclerosis with interferon beta is only partly effective. We aimed to establish whether add-on of simvastatin, a statin with anti-inflammatory properties, improves this efficacy. METHODS: We enrolled treatment-naive patients with relapsing-remitting multiple sclerosis in a multicentre, placebo-controlled, double-blind, randomised, parallel-group trial of simvastatin (80 mg daily) as add-on treatment to intramuscular interferon beta-1a (30 μg weekly). After starting treatment with interferon beta, patients were randomly assigned (in computer-generated blocks of four patients) to simvastatin 80 mg per day or placebo for 1-3 years. Patients and treating and evaluating physicians were masked to treatment allocation. The primary outcome measure was annual rate of documented relapses; analysis was by intention to treat. This trial is registered at ClinicalTrials.gov, NCT00492765. FINDINGS: We randomly assigned 307 patients to interferon beta plus simvastatin (n=151) or plus placebo (n=156). Annual rate of documented relapses was 0·19 (95% CI 0·13 to 0·28) in the simvastatin group and 0·14 (95% CI 0·09 to 0·23) in the placebo group (absolute difference 0·059, 95% CI -0·21 to 0·09; p=0·35). Time to first documented relapse (20th percentile) was 18·1 months in patients on simvastatin and 21·5 months in those on placebo (hazard ratio 1·21, 95% CI 0·74 to 1·99; p=0·51). Mean number of new or enlarging T2 lesions was 2·96 in the simvastatin group and 2·52 in the placebo group (ratio of new lesions, 1·17, 95% CI 8·89 to 1·55; p=0·25). Eight (6%) patients on simvastatin and 17 (13%) on placebo had no disease activity (odds ratio 0·42, 95% CI 0·17 to 1·00; p=0·05). No unexpected adverse events were seen. Generally, adverse events were mild and there were no group differences in infections or musculoskeletal disorders, including myalgia (five [3%] patients on simvastatin and nine [6%] on placebo). Rhabdomyolysis and myoglobinuria were not reported and there were no differences in serum creatine phosphokinase. INTERPRETATION: We found no beneficial effect of simvastatin as add-on therapy to interferon beta-1a. Although unlikely, we can not exclude that combination of other statins with other disease-modifying drugs still could be beneficial. FUNDING: Biogen Idec.
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| 3. |
- Vinnik, Lev, et al.
(författare)
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Anisotropic lithosphere under the Fennoscandian shield from P receiver functions and SKS waveforms of the POLENET/LAPNET array
- 2014
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Ingår i: Tectonophysics. - : Elsevier BV. - 0040-1951 .- 1879-3266. ; 628, s. 45-54
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Tidskriftsartikel (refereegranskat)abstract
- Seismic azimuthal anisotropy is the key evidence of the past and present strains in the upper mantle. The standard analysis of shear-wave splitting with the SKS techniques is useful in mapping lateral variations but it is insensitive to depth of anisotropy and to variations of anisotropy with depth. To retrieve the depth localized anisotropy under the Fennoscandian shield, we inverted P-wave receiver functions of the POLENET/LAPNET array in northern Finland jointly with SKS recordings. Shear-wave anisotropy of similar to 2.5% with the fast direction of 40 degrees-60 degrees in a depth range from the Moho to similar to 110 km is a robust result of the inversion. The obtained direction is nearly normal to the azimuth of the maximum horizontal compressional stress in the lithosphere, but a recent origin of this anisotropy is in doubt. This anisotropy may be frozen since the Precambrian, but it shows no clear relation with the trends of the Precambrian tectonics. The upper anisotropic layer accounts for similar to 40% of shear-wave splitting in SKS, and to explain the rest another anisotropic layer is required. The top of the second layer with a practically similar fast direction is found at a depth of 200-240 km. This direction is close to the current APM direction of the lithosphere with implication that the inferred anisotropy may be related with the current plate motion, and the anisotropic layer belongs to the asthenosphere. The bottom of this layer is uncertain, but it is at least 320 km deep. In a depth range from 160 km to 200-240 km the fast anisotropy direction is 110-150 degrees. Origin of this direction is unclear.
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