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| 2. |
- Brooker, R.W., et al.
(författare)
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Facilitation in plant communities: the past, the present, and the future
- 2008
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 96:1, s. 18-34
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Tidskriftsartikel (refereegranskat)abstract
- 1. Once neglected, the role of facilitative interactions in plant communities has received considerable attention in the last two decades, and is now widely recognized. It is timely to consider the progress made by research in this field.2. We review the development of plant facilitation research, focusing on the history of the field, the relationship between plant–plant interactions and environmental severity gradients, and attempts to integrate facilitation into mainstream ecological theory. We then consider future directions for facilitation research.3. With respect to our fundamental understanding of plant facilitation, clarification of the relationship between interactions and environmental gradients is central for further progress, and necessitates the design and implementation of experiments that move beyond the clear limitations of previous studies.4. There is substantial scope for exploring indirect facilitative effects in plant communities, including their impacts on diversity and evolution, and future studies should connect the degree of non-transitivity in plant competitive networks to community diversity and facilitative promotion of species coexistence, and explore how the role of indirect facilitation varies with environmental severity.5. Certain ecological modelling approaches (e.g. individual-based modelling), although thus far largely neglected, provide highly useful tools for exploring these fundamental processes.6. Evolutionary responses might result from facilitative interactions, and consideration of facilitation might lead to re-assessment of the evolution of plant growth forms.7. Improved understanding of facilitation processes has direct relevance for the development of tools for ecosystem restoration, and for improving our understanding of the response of plant species and communities to environmental change drivers.8. Attempts to apply our developing ecological knowledge would benefit from explicit recognition of the potential role of facilitative plant–plant interactions in the design and interpretation of studies from the fields of restoration and global change ecology.9. Synthesis: Plant facilitation research provides new insights into classic ecological theory and pressing environmental issues. Awareness and understanding of facilitation should be part of the basic ecological knowledge of all plant ecologists.
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| 3. |
- Everett, K. V., et al.
(författare)
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Linkage and association analysis of CACNG3 in childhood absence epilepsy
- 2007
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Ingår i: Eur J Hum Genet. - : Springer Science and Business Media LLC. - 1018-4813 .- 1476-5438. ; 15:4, s. 463-72
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Tidskriftsartikel (refereegranskat)abstract
- Childhood absence epilepsy (CAE) is an idiopathic generalised epilepsy characterised by absence seizures manifested by transitory loss of awareness with 2.5-4 Hz spike-wave complexes on ictal EEG. A genetic component to aetiology is established but the mechanism of inheritance and the genes involved are not fully defined. Available evidence suggests that genes encoding brain expressed voltage-gated calcium channels, including CACNG3 on chromosome 16p12-p13.1, may represent susceptibility loci for CAE. The aim of this work was to further evaluate CACNG3 as a susceptibility locus by linkage and association analysis. Assuming locus heterogeneity, a significant HLOD score (HLOD = 3.54, alpha = 0.62) was obtained for markers encompassing CACNG3 in 65 nuclear families with a proband with CAE. The maximum non-parametric linkage score was 2.87 (P < 0.002). Re-sequencing of the coding exons in 59 patients did not identify any putative causal variants. A linkage disequilibrium (LD) map of CACNG3 was constructed using 23 single nucleotide polymorphisms (SNPs). Transmission disequilibrium was sought using individual SNPs and SNP-based haplotypes with the pedigree disequilibrium test in 217 CAE trios and the 65 nuclear pedigrees. Evidence for transmission disequilibrium (P < or = 0.01) was found for SNPs within a approximately 35 kb region of high LD encompassing the 5'UTR, exon 1 and part of intron 1 of CACNG3. Re-sequencing of this interval was undertaken in 24 affected individuals. Seventy-two variants were identified: 45 upstream; two 5'UTR; and 25 intronic SNPs. No coding sequence variants were identified, although four variants are predicted to affect exonic splicing. This evidence supports CACNG3 as a susceptibility locus in a subset of CAE patients.
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| 4. |
- Jonsson, P., et al.
(författare)
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Development of fluorescence-based LIDAR technology for biological sensing
- 2005
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Ingår i: 2005 MRS Spring Meeting - Symposium FF. - : Materials Research Society. ; , s. 51-62
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Konferensbidrag (refereegranskat)abstract
- Results of our on-going development of biological warfare agents (BWA) detection systems based on spectral detection of ultraviolet (UV) laser induced fluorescence (LIF) are presented. A compact optical parametric oscillator (OPO) with intracavity sum-frequency mixing (SFM) to generate 293 nm UV laser irradiation was developed. The OPO/SFM device was pumped by a diode-pumped Nd:YAG laser (1064 nm), including subsequent second-harmonic generation (SHG) in an external periodically poled KTiOPO4 (PPKTP) crystal. The laser generated 1.8 ns pulses at 100 Hz with an average power of 44 mW at 532 nm. The whole system could be used to deliver approximately 30 μJ laser irradiation per pulse (100 Hz) at 293 nm. The spectral detection part of the system consists of a grating and a photomultiplier tube (PMT) array with 32 channels, which can measure fluorescence spectra in the wavelength band from 250 nm to 800 nm. The detector system was designed along with a trigger laser to enable measurement of fluorescence spectra from an individual aerosol particle of simulants for BWA upon excitation with a single nanosecond laser pulse. We demonstrate the successful detection and spectral characterization of simulants for BWA, i.e., Bacillus atrophaeus (BG), Bacillus thuringiensis (BT), and Ovalbumin (OA).
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| 5. |
- Lu, X., et al.
(författare)
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Wax morphology in bitumen
- 2005
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Ingår i: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 40:8, s. 1893-1900
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Tidskriftsartikel (refereegranskat)abstract
- Wax crystallisation and melting in bitumen is usually considered detrimental to bitumen quality and asphalt performance. The objectives of this paper are to study wax morphology in bitumen and to investigate effects of time, temperature, and thermal cycling on wax crystallisation. Various samples were selected, including eight waxy bitumens of different sources and three laboratory blends prepared by adding a slack wax and two isolated bitumen waxes to the non-waxy bitumen. Test methods used were differential scanning calorimetry (DSC), polarised light microscopy (PLM), confocal laser scanning microscopy (CLSM), and freeze etching (fracture) in combination with transmission electron microscopy (FF-TEM). The DSC results indicated that the selected bitumen samples differ widely in wax content and wax crystallisation starting and melting out temperatures. It was found that non-waxy bitumen displayed no structure or crystals neither in PLM, CLSM or FF-TEM, while waxy bitumens from different crude origins showed a large variation of structures. The morphology of wax crystals was highly dependent on crystallisation temperature as well as temperature history. The wax which has been isolated from waxy bitumen and mixed into non-waxy bitumen displayed similar morphology as the wax in the original bitumen. It was also found that bitumen wax usually melted at temperatures lower than 60°C although in one case a temperature of 80°C was needed until complete melting of the wax. © 2005 Springer Science + Business Media, Inc.
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| 6. |
- Minier, V., et al.
(författare)
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Evidence of triggered star formation in G327.3-0.6. Dust-continuum mapping of an infrared dark cloud with P-ArTéMiS
- 2009
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 501, s. L1-L4
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Tidskriftsartikel (refereegranskat)abstract
- Aims: Expanding HII regions and propagating shocks are common in the environment of young high-mass star-forming complexes. They can compress a pre-existing molecular cloud and trigger the formation of dense cores. We investigate whether these phenomena can explain the formation of high-mass protostars within an infrared dark cloud located at the position of G327.3-0.6 in the Galactic plane, in between two large infrared bubbles and two HII regions. Methods: The region of G327.3-0.6 was imaged at 450 μ m with the CEA P-ArTéMiS bolometer array on the Atacama Pathfinder EXperiment telescope in Chile. APEX/LABOCA and APEX-2A, and Spitzer/IRAC and MIPS archives data were used in this study. Results: Ten massive cores were detected in the P-ArTéMiS image, embedded within the infrared dark cloud seen in absorption at both 8 and 24 μm. Their luminosities and masses indicate that they form high-mass stars. The kinematical study of the region suggests that the infrared bubbles expand toward the infrared dark cloud. Conclusions: Under the influence of expanding bubbles, star formation occurs in the infrared dark areas at the border of HII regions and infrared bubbles.
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| 8. |
- Olofsson, Henrik, 1972, et al.
(författare)
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Profiling the EMBRACE tile beam using GPS satellite carriers
- 2009
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Ingår i: Proceedings of Science. - 1824-8039. ; 132, s. 253-257
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Konferensbidrag (refereegranskat)abstract
- All rights reserved. The L2C carriers of multiple GPS satellites have been used to trace out a nearly complete beam pattern out to 45 away from the main lobe centre for a horizontally mounted single EMBRACE tile. The beam was formed along its bore-sight direction, i.e., staring at the local sky zenith. The result is very close to design specifications although there is evidence for at least one side lobe rising above the achieved noise level. We have also used the older L2 carrier to estimate the system temperature, although an exact figure in addition requires knowledge of the aperture efficiency. © 2018 Sissa Medialab Srl.
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| 9. |
- Olofsson, P. S., et al.
(författare)
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A functional interleukin-1 receptor antagonist polymorphism influences atherosclerosis development - The interleukin-1β : Interleukin-1 receptor antagonist balance in atherosclerosis
- 2009
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Ingår i: Circulation Journal. - : Japanese Circulation Society,Nihon Junkanki Gakkai. - 1346-9843 .- 1347-4820. ; 73:8, s. 1531-1536
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Tidskriftsartikel (refereegranskat)abstract
- Background: Interleukin (JL)-β plays a central role in inflammation and atherosclerosis, but levels of IL-1β, its natural antagonist, IL-1Ra, and their balance in human atherosclerotic lesions, are unknown. Knowledge of protein levels in atherosclerosis and the influence of a functional IL-1Rα polymorphism would increase the understanding of atherosclerosis pathogenesis.Methods and Results: Fresh and endotoxin-stimulated explanted human atherosclerotic and normal arteries were analyzed for IL-1β, IL-1Ra and IL-1 receptor 1 (IL-1R1) using TaqMan PCR and enzyme-linked immunosorbent assay. Two hundred forty-three survivors of a first myocardial infarction were genotyped for a polymorphism in IL-1Ra and their coronary atherosclerosis analyzed by using coronary angiography. Levels of IL-1β, IL-1Ra and IL-1R1 mRNA were significantly increased in atherosclerotic arteries compared with normal arteries. Endotoxin stimulation increased IL-1β levels more than IL-1Ra levels (ie, promoted a pro-inflammatory state). A polymorphism in IL-1Ra known to increase levels of IL-1Ra was associated with decreased mean coronary artery plaque area.Conclusions: Activation of innate immunity changed the balance between IL-1β and IL-1Ra in atherosclerotic arteries towards a more pro-inflammatory state. In line with this, the presence of an IL-1Ra intron 2 polymorphism known to increase IL-1Ra levels, and possibly the IL-1Ra:IL-1β ratio, was associated with reduced coronary atherosclerosis.
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| 10. |
- Olofsson, P. S., et al.
(författare)
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Genetic variants of TNFSF4 and risk for carotid artery disease and stroke
- 2009
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Ingår i: Journal of Molecular Medicine. - New York : Springer. - 0946-2716 .- 1432-1440. ; 87:4, s. 337-346
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Tidskriftsartikel (refereegranskat)abstract
- In two independent human cohorts, the minor allele of SNP rs3850641 in TNFSF4 was significantly more frequent in individuals with myocardial infarction than in controls. In mice, Tnfsf4 expression is associated with increased atherosclerosis. The expression of TNFSF4 in human atherosclerosis and the association between genotype and cerebrovascular disease have not yet been investigated. TNFSF4 messenger RNA (mRNA) levels were significantly higher in human atherosclerotic lesions compared with controls (730∈±∈30 vs 330∈±∈65 arbitrary units, p∈<∈0.01). TNFSF4 was mainly expressed by macrophages in atherosclerotic lesions. In cell culture, endothelial cells upregulated TNFSF4 in response to tumor necrosis factor alpha (TNF-α; 460∈±∈110 vs 133∈±∈8 arbitrary units, p∈<∈0.001 after 6 h of stimulation). We analyzed the TNFSF4 gene in 239 patients who had undergone carotid endarterectomy and 138 matching controls from The Biobank of Karolinska Carotid Endarterectomies and Stockholm Heart Epidemiology Program cohorts and 929 patients and 1,382 matching controls from the Sahlgrenska Academy Study on Ischemic Stroke and Case Control Study of Stroke cohorts, limiting inclusion to patients with ischemic stroke. Participants were genotyped for the rs3850641 SNP in TNFSF4. Genotype associations were neither found with TNFSF4 mRNA levels nor with atherosclerosis associated systemic factors or risk for stroke. This study shows that TNFSF4 is expressed on antigen-presenting cells in human carotid atherosclerotic lesions but provides no evidence for an association of TNFSF4 gene variation with the risk for ischemic stroke.
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