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- Aamodt, K., et al.
(författare)
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The ALICE experiment at the CERN LHC
- 2008
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Ingår i: Journal of Instrumentation. - 1748-0221. ; 3:S08002
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Forskningsöversikt (refereegranskat)abstract
- ALICE (A Large Ion Collider Experiment) is a general-purpose, heavy-ion detector at the CERN LHC which focuses on QCD, the strong-interaction sector of the Standard Model. It is designed to address the physics of strongly interacting matter and the quark-gluon plasma at extreme values of energy density and temperature in nucleus-nucleus collisions. Besides running with Pb ions, the physics programme includes collisions with lighter ions, lower energy running and dedicated proton-nucleus runs. ALICE will also take data with proton beams at the top LHC energy to collect reference data for the heavy-ion programme and to address several QCD topics for which ALICE is complementary to the other LHC detectors. The ALICE detector has been built by a collaboration including currently over 1000 physicists and engineers from 105 Institutes in 30 countries, Its overall dimensions are 16 x 16 x 26 m(3) with a total weight of approximately 10 000 t. The experiment consists of 18 different detector systems each with its own specific technology choice and design constraints, driven both by the physics requirements and the experimental conditions expected at LHC. The most stringent design constraint is to cope with the extreme particle multiplicity anticipated in central Pb-Pb collisions. The different subsystems were optimized to provide high-momentum resolution as well as excellent Particle Identification (PID) over a broad range in momentum, up to the highest multiplicities predicted for LHC. This will allow for comprehensive studies of hadrons, electrons, muons, and photons produced in the collision of heavy nuclei. Most detector systems are scheduled to be installed and ready for data taking by mid-2008 when the LHC is scheduled to start operation, with the exception of parts of the Photon Spectrometer (PHOS), Transition Radiation Detector (TRD) and Electro Magnetic Calorimeter (EMCal). These detectors will be completed for the high-luminosity ion run expected in 2010. This paper describes in detail the detector components as installed for the first data taking in the summer of 2008.
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| 4. |
- Spicer, R.A., et al.
(författare)
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The Late Cretaceous continental interior of Siberia: A challenge to climate models
- 2008
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Ingår i: Earth and Planetary Science Letters. - : Elsevier BV. - 1385-013X .- 0012-821X. ; 267:1-2, s. 228-235
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Tidskriftsartikel (refereegranskat)abstract
- Geological evidence from the Late Cretaceous continental interior of the Vilui Basin, Siberia suggests a far wetter, warmer, and more equable annual climate than General Circulation Models (GCMs) can reproduce. The disparity cannot be bridged by the uncertainties inherent in either the models or the geological climate proxies. This implies the mismatch is genuine and that either 1) we have systematic errors in the interpretation/calibration of the climate proxies, and/or 2) lack of full knowledge of the boundary conditions needed for GCM models simulations of this period, and/or 3) an insufficient understanding of the nature of the coupled atmosphere–ocean–biosphere system and its representation within climate models during warm climate epochs. If it is the third explanation, this would have important implications for the prediction of future climates and would suggest that we may currently be underestimating future climate change in such regions.
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| 6. |
- Valdés, A.E., et al.
(författare)
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Developmental stage as a possible factor affecting cytokinin content and cytokinin dehydrogenase activity in Pinus sylvestris.
- 2007
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Ingår i: Biologia plantarum. - : Institute of Experimental Botany. - 0006-3134 .- 1573-8264. ; 51:1, s. 193-197
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Tidskriftsartikel (refereegranskat)abstract
- In the present study cytokinin dehydrogenase (CKX) activity was for the first time found in a conifer species, Pinus sylvestris. The activities were correlated with the endogenous cytokinin contents. Several enzyme substrates and two different electron acceptors were used to search for the enzyme activity in the extract from seeds, seedlings and plantlets. The highest specific activity was found in one-year-old plantlets with isopentenyladenine as the substrate and 2,6-dichlorophenolindophenol as the electron acceptor, at pH 8. An enhancement in the CKX specific activity corresponded to increasing contents of cytokinins, mainly isopentenyladenine and isopentenyladenosine, indicating that the enzyme activity is affected by the endogenous supply of cytokinins. CKX affinity for the ribosylated form of isopentenyladenine was dependent on the developmental stage, being higher in seeds than in seedlings, and not detectable in plantlets. The results are indicative of the presence of different isoenzymes throughout the development.
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