| 1. |
- Acciari, V. A., et al.
(författare)
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Radio Imaging of the Very-High-Energy gamma-Ray Emission Region in the Central Engine of a Radio Galaxy
- 2009
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 325:5939, s. 444-448
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Tidskriftsartikel (refereegranskat)abstract
- The accretion of matter onto a massive black hole is believed to feed the relativistic plasma jets found in many active galactic nuclei (AGN). Although some AGN accelerate particles to energies exceeding 10(12) electron volts and are bright sources of very-high-energy (VHE) gamma-ray emission, it is not yet known where the VHE emission originates. Here we report on radio and VHE observations of the radio galaxy Messier 87, revealing a period of extremely strong VHE gamma-ray flares accompanied by a strong increase of the radio flux from its nucleus. These results imply that charged particles are accelerated to very high energies in the immediate vicinity of the black hole.
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| 2. |
- Lukasik, J., et al.
(författare)
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Discriminant analysis and secondary-beam charge recognition
- 2008
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Ingår i: Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. - : Elsevier BV. - 0168-9002. ; 587:2-3, s. 413-419
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Tidskriftsartikel (refereegranskat)abstract
- The discriminant-analysis method has been applied to optimize the exotic-beam charge recognition in a projectile fragmentation experiment. The experiment was carried out at the GSI using the fragment separator (FRS) to produce and select the relativistic secondary beams, and the ALADIN setup to measure their fragmentation products following collisions with Sn target nuclei. The beams of neutron poor isotopes around La-124 and Sn-107 were selected to study the isospin dependence of the limiting temperature of heavy nuclei by comparing with results for stable Sn-124 projectiles. A dedicated detector to measure the projectile charge upstream of the reaction target was not used, and alternative methods had to be developed. The presented method, based on the multivariate discriminant analysis, allowed to increase the efficacy of charge recognition up to about 90%, which was about 20% more than achieved with the simple scalar methods.
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| 3. |
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| 4. |
- Trautmann, W., et al.
(författare)
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Isotopic dependence of the caloric curve
- 2009
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Ingår i: Progress in Particle and Nuclear Physics. - : Elsevier BV. - 0146-6410. ; 62:2, s. 407-412
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Tidskriftsartikel (refereegranskat)abstract
- Isotopic effects in projectile fragmentation at relativistic energies have been studied with the ALADIN forward spectrometer at SIS. Stable and radioactive Sn and La beams with an incident energy of 600 MeV per nucleon have been used in order to explore a wide range of isotopic compositions. Chemical freeze-out temperatures are found to be nearly invariant with respect to the A/Z ratio of the produced spectator sources, consistent with predictions for expanded systems. Consequences for the proposed interpretation of chemical breakup temperatures as representing the limiting temperatures predicted by microscopic models are discussed. (C) 2009 Elsevier B.V. All rights reserved.
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| 5. |
- Eckstein, Rolf Lutz, et al.
(författare)
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Genetic structure among and within peripheral and central populations of three endangered floodplain violets
- 2006
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Ingår i: Molecular Ecology. - 0962-1083 .- 1365-294X. ; 15:9, s. 2367-2379
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the partitioning of genetic variance in peripheral and central populations may shed more light on the effects of genetic drift and gene flow on population genetic structure and, thereby, improve attempts to conserve genetic diversity. We analysed genetic structure of peripheral and central populations of three insect-pollinated violets (Viola elatior, Viola pumila, Viola stagnina) to evaluate to what extent these patterns can be explained by gene flow and genetic drift. Amplified fragment length polymorphism was used to analyse 930 individuals of 50 populations. Consistent with theoretical predictions, peripheral populations were smaller and more isolated, differentiation was stronger, and genetic diversity and gene flow lower in peripheral populations of V. pumila and V. stagnina. In V. elatior, probably historic fragmentation effects linked to its specific habitat type were superimposed on the plant geographic (peripheral-central) patterns, resulting in lower relative importance of gene flow in central populations. Genetic variation between regions (3-6%), among (30-37%) and within populations (60-64%) was significant. Peripheral populations lacked markers that were rare and localized in central populations. Loss of widespread markers in peripheral V. stagnina populations indicated genetic erosion. Autocorrelation within populations was statistically significant up to a distance of 10-20 m. Higher average genetic similarity in peripheral populations than in central ones indicated higher local gene flow, probably owing to management practices. Peripheral populations contributed significantly to genetic variation and contained unique markers, which made them valuable for the conservation of genetic diversity.
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| 6. |
- Morris, A, et al.
(författare)
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The Development of a Multidisciplinary System to Understand Causal Factors in Road Crashes
- 2006
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Ingår i: 42nd Annual Human Factors and Ergonomics Society of Australia Conference 2006, HFESA 2006. - 9781622769599 ; , s. 31-38
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The persistent lack of crash causation data to help inform and monitor road and vehicle safety policy is a major obstacle. Data are needed to assess the performance of road and vehicle safety stakeholders and is needed to support the development of further actions. A recent analysis conducted by the European Transport Safety Council identified that there was no single system in place that could meet all of the needs and that there were major gaps including in-depth crash causation information. This paper describes the process of developing a data collection and analysis system designed to fill these gaps. A project team with members from 7 countries was set up to devise appropriate variable lists to collect crash causation information under the following topic levels: accident, road environment, vehicle, and road user, using two quite different sets of resources: retrospective detailed police reports (n=1300) and prospective, independent, on-scene accident research investigations (n=1000). Data categorisation and human factors analysis methods based on Cognitive Reliability and Error Analysis Method (Hollnagel, 1998) were developed to enable the causal factors to be recorded, linked and understood. A harmonised, prospective "on-scene" method for recording the root causes and critical events of road crashes was developed. Where appropriate, this includes interviewing road users in collaboration with more routine accident investigation techniques. The typical level of detail recorded is a minimum of 150 variables for each accident. The project will enable multidisciplinary information on the circumstances of crashes to be interpreted to provide information on the causal factors. This has major applications in the areas of active safety systems, infrastructure and road safety, as well as for tailoring behavioural interventions. There is no direct model available internationally that uses such a systems based approach.
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| 7. |
- Otte, J, et al.
(författare)
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Formation of amyloid-like fibrils upon limited proteolysis of bovine alpha-lactalbumin
- 2005
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Ingår i: International Dairy Journal. - : Elsevier BV. - 0958-6946. ; 15:3, s. 219-229
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Tidskriftsartikel (refereegranskat)abstract
- Bovine alpha-lactalbumin (alpha-LA) (10 g L-1) was incubated with a protease from Bacillus licheniformis at pH 7.5 and 50 degreesC. The reaction was biphasic consisting of an initial hydrolysis of intact alpha-LA and formation of dimers from large hydrolysis products within 60 min followed by aggregation of dimers into aggregates of 500 kDa. The aggregates consisted primarily of fibrillar strands with a diameter of 5 nm. Formation of these strands was accompanied by a change in secondary structure towards higher beta-sheet content and strong binding of thioflavin, features shared with amyloidal fibrils. The main components in these fibrils were fragments of 8.8 and 9.8 kDa shown to occur in a monomer-dimer equilibrium. These fragments were identified and a molecular mechanism involving side-by-side assembly of dimers of these fragments into fibrils is proposed.
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