| 1. |
- Aamodt, K., et al.
(author)
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The ALICE experiment at the CERN LHC
- 2008
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In: Journal of Instrumentation. - 1748-0221. ; 3:S08002
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Research review (peer-reviewed)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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| 3. |
- Power, M. J., et al.
(author)
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Changes in fire regimes since the Last Glacial Maximum : an assessment based on a global synthesis and analysis of charcoal data
- 2008
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In: Climate Dynamics. - : Springer Science and Business Media LLC. - 0930-7575 .- 1432-0894. ; 30:7-8, s. 887-907
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Journal article (peer-reviewed)abstract
- Fire activity has varied globally and continuously since the last glacial maximum (LGM) in response to long-term changes in global climate and shorter-term regional changes in climate, vegetation, and human land use. We have synthesized sedimentary charcoal records of biomass burning since the LGM and present global maps showing changes in fire activity for time slices during the past 21,000 years (as differences in charcoal accumulation values compared to pre-industrial). There is strong broad-scale coherence in fire activity after the LGM, but spatial heterogeneity in the signals increases thereafter. In North America, Europe and southern South America, charcoal records indicate less-than-present fire activity during the deglacial period, from 21,000 to ∼11,000 cal yr BP. In contrast, the tropical latitudes of South America and Africa show greater-than-present fire activity from ∼19,000 to ∼17,000 cal yr BP and most sites from Indochina and Australia show greater-than-present fire activity from 16,000 to ∼13,000 cal yr BP. Many sites indicate greater-than-present or near-present activity during the Holocene with the exception of eastern North America and eastern Asia from 8,000 to ∼3,000 cal yr BP, Indonesia and Australia from 11,000 to 4,000 cal yr BP, and southern South America from 6,000 to 3,000 cal yr BP where fire activity was less than present. Regional coherence in the patterns of change in fire activity was evident throughout the post-glacial period. These complex patterns can largely be explained in terms of large-scale climate controls modulated by local changes in vegetation and fuel load.
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| 4. |
- Tomasi, C., et al.
(author)
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Aerosols in polar regions : A historical overview based on optical depth and in situ observations
- 2007
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In: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 112:D16, s. D16205-
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Research review (peer-reviewed)abstract
- Large sets of filtered actinometer, filtered pyrheliometer and Sun photometer measurements have been carried out over the past 30 years by various groups at different Arctic and Antarctic sites and for different time periods. They were examined to estimate ensemble average, long-term trends of the summer background aerosol optical depth AOD(500 nm) in the polar regions ( omitting the data influenced by Arctic haze and volcanic eruptions). The trend for the Arctic was estimated to be between -1.6% and -2.0% per year over 30 years, depending on location. No significant trend was observed for Antarctica. The time patterns of AOD( 500 nm) and angstrom ngstrom's parameters a and beta measured with Sun photometers during the last 20 years at various Arctic and Antarctic sites are also presented. They give a measure of the large variations of these parameters due to El Chichon, Pinatubo, and Cerro Hudson volcanic particles, Arctic haze episodes most frequent in winter and spring, and the transport of Asian dust and boreal smokes to the Arctic region. Evidence is also shown of marked differences between the aerosol optical parameters measured at coastal and high-altitude sites in Antarctica. In situ optical and chemical composition parameters of aerosol particles measured at Arctic and Antarctic sites are also examined to achieve more complete information on the multimodal size distribution shape parameters and their radiative properties. A characterization of aerosol radiative parameters is also defined by plotting the daily mean values of a as a function of AOD( 500 nm), separately for the two polar regions, allowing the identification of different clusters related to fifteen aerosol classes, for which the spectral values of complex refractive index and single scattering albedo were evaluated.
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| 5. |
- Batson, C. Daniel, et al.
(author)
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An additional antecedent of empathic concern : Valuing the welfare of the person in need
- 2007
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In: Journal of Personality and Social Psychology. - : American Psychological Association (APA). - 0022-3514 .- 1939-1315. ; 93:1, s. 65-74
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Journal article (peer-reviewed)abstract
- Two experiments examined the role of valuing the welfare of a person in need as an antecedent of empathic concern. Specifically, these experiments explored the relation of such valuing to a well-known antecedent - perspective taking. In Experiment 1, both perspective taking and valuing were manipulated, and each independently increased empathic concern, which, in turn, increased helping behavior. In Experiment 2, only valuing was manipulated. Manipulated valuing increased measured perspective taking and, in part as a result, increased empathic concern, which, in turn, increased helping. Valuing appears to be an important, largely overlooked, situational antecedent of feeling empathy for a person in need.
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| 6. |
- de Almeida, J. S., et al.
(author)
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On the dynamical stability and metallic behavior of YH3 under pressure
- 2009
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In: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 94:25, s. 251913-
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Journal article (peer-reviewed)abstract
- Wereport on the behavior of structural and electronic properties ofyttrium trihydride under pressure using first principles calculations. We showthat YH3 undergoes a structural transformation and its high pressurephase is dynamically stable under pressure since the peak atthe imaginary frequencies of the phonon density of states, whichaccount for the structural instability disappears at high pressure. Additionally,our GW calculations indicate a metallization of the high pressurecubic phase of YH3.
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| 8. |
- Klintenberg, Mattias, et al.
(author)
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Evolving properties of two-dimensional materials : from graphene to graphite
- 2009
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In: Journal of Physics. - : IOP Publishing. - 0953-8984 .- 1361-648X. ; 21:33, s. 335502-
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Journal article (peer-reviewed)abstract
- We have studied theoretically, using density functional theory, several material properties when going from one C layer in graphene to two and three graphene layers and on to graphite. The properties we have focused on are the elastic constants, electronic structure (energy bands and density of states), and the dielectric properties. For any of the properties we have investigated the modification due to an increase in the number of graphene layers is within a few per cent. Our results are in agreement with the analysis presented recently by Kopelevich and Esquinazi (unpublished).
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| 9. |
- Molina, E., et al.
(author)
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Integrated stratigraphy and chronostratigraphy across the Ypresian-Lutetian transition in the Fortuna Section (Betic Cordillera Spain)
- 2006
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In: Newsletters on Stratigraphy. - : Schweizerbart. - 0078-0421. ; 42:1, s. 1-19
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Journal article (peer-reviewed)abstract
- This integrated study across the Ypresian/Lutetian boundary in the Fortuna Section (Spain) allowed us to recognize a bundle of events in the transitional interval between the Ypresian and Lutetian stages. Planktic foraminifera show an apparently continuous succession spanning the planktic foraminiferal zones P9, P10 and P11. Calcareous nannofossils allowed the recognition of the nannofossil subzones NP14b, NP15a, NP15b and of zone NP16. Small benthic foraminiferal assemblages may indicate a hyperthermal event as evidenced by a bloom of Aragonia aragonensis, which is coeval with a major change in clay mineralogy. This event coincides with the first occurrence of Hantkenina specimens at the base of planktonic foraminiferal zone P10 in the uppermost part of nannofossil subzone NP14b, which could be used to define the Ypresian/Lutetian boundary.
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