| 1. |
- Abelev, Betty, et al.
(författare)
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Long-range angular correlations on the near and away side in p-Pb collisions at root S-NN=5.02 TeV
- 2013
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 719:1-3, s. 29-41
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Tidskriftsartikel (refereegranskat)abstract
- Angular correlations between charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV for transverse momentum ranges within 0.5 < P-T,P-assoc < P-T,P-trig < 4 GeV/c. The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity, and expressed as associated yield per trigger particle. Two long-range ridge-like structures, one on the near side and one on the away side, are observed when the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. The excess on the near-side is qualitatively similar to that recently reported by the CMS Collaboration, while the excess on the away-side is reported for the first time. The two-ridge structure projected onto azimuthal angle is quantified with the second and third Fourier coefficients as well as by near-side and away-side yields and widths. The yields on the near side and on the away side are equal within the uncertainties for all studied event multiplicity and p(T) bins, and the widths show no significant evolution with event multiplicity or p(T). These findings suggest that the near-side ridge is accompanied by an essentially identical away-side ridge. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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| 2. |
- Hudson, Lawrence N., et al.
(författare)
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The PREDICTS database : a global database of how local terrestrial biodiversity responds to human impacts
- 2014
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Ingår i: Ecology and Evolution. - : Wiley. - 2045-7758. ; 4:24, s. 4701-4735
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Tidskriftsartikel (refereegranskat)abstract
- Biodiversity continues to decline in the face of increasing anthropogenic pressures such as habitat destruction, exploitation, pollution and introduction of alien species. Existing global databases of species' threat status or population time series are dominated by charismatic species. The collation of datasets with broad taxonomic and biogeographic extents, and that support computation of a range of biodiversity indicators, is necessary to enable better understanding of historical declines and to project - and avert - future declines. We describe and assess a new database of more than 1.6 million samples from 78 countries representing over 28,000 species, collated from existing spatial comparisons of local-scale biodiversity exposed to different intensities and types of anthropogenic pressures, from terrestrial sites around the world. The database contains measurements taken in 208 (of 814) ecoregions, 13 (of 14) biomes, 25 (of 35) biodiversity hotspots and 16 (of 17) megadiverse countries. The database contains more than 1% of the total number of all species described, and more than 1% of the described species within many taxonomic groups - including flowering plants, gymnosperms, birds, mammals, reptiles, amphibians, beetles, lepidopterans and hymenopterans. The dataset, which is still being added to, is therefore already considerably larger and more representative than those used by previous quantitative models of biodiversity trends and responses. The database is being assembled as part of the PREDICTS project (Projecting Responses of Ecological Diversity In Changing Terrestrial Systems - ). We make site-level summary data available alongside this article. The full database will be publicly available in 2015.
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| 3. |
- Abelev, Betty, et al.
(författare)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :11
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Tidskriftsartikel (refereegranskat)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 4. |
- Abelev, Betty, et al.
(författare)
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Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
- 2012
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Ingår i: Journal of High Energy Physics. - 1029-8479. ; :7
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Tidskriftsartikel (refereegranskat)abstract
- We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.
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| 5. |
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| 6. |
- Eriksson, Hampus, 1979-
(författare)
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Managing sea cucumber fisheries and aquaculture : Studies of social-ecological systems in the Western Indian Ocean
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Collecting sea cucumbers to supply the high value Chinese dried seafood market is a livelihood activity available to many people in the Western Indian Ocean (WIO), making it an important part of local economies. These fisheries are generally not successfully managed and tropical sea cucumber fisheries show continuing signs of decline. This thesis takes a social-ecological systems approach to guide better management of sea cucumber fisheries and aquaculture in the WIO. Papers 1 and 2 analyse the fishery situation in Zanzibar and find that in the absence of effective management institutions and income alternatives among fishers, leading to dependence, there are unsustainable expanding processes. Paper 3 compares the unmanaged fishery in Zanzibar to the highly controlled situation in Mayotte. In Mayotte, a protection effect is evident and the commercial value of stocks is significantly higher than in Zanzibar. The analysis of the situation in Mayotte demonstrates the importance of matching the fishery – management temporal scales through prepared and adaptive management to avoid processes that reinforce unsustainable expansion. Paper 4 analyses sea cucumber community spatial distribution patterns at a coastal seascape-scale in Mayotte establishing baseline patterns of habitat utilization and abundance, which can be used as reference in management. Paper 5 reviews the potential for sea cucumber aquaculture in the WIO. The review illustrates that this activity, which is currently gaining momentum, does so based on inflated promises and with significant social-ecological risks. Emphasis for improvements is, in this thesis, placed on the importance of prepared and adaptive institutions to govern and control expanding processes of the fishery. These institutional features may be achieved by increasing the level of knowledge and participation in governance and by integration of sea cucumber resources management into higher-level policy initiatives.
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| 7. |
- García, Ariel, et al.
(författare)
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Dilute sulphuric acid pretreatment and enzymatic hydrolysis of Jatropha curcas fruit shells for ethanol production
- 2014
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Ingår i: Industrial crops and products (Print). - : Elsevier. - 0926-6690 .- 1872-633X. ; 53, s. 148-153
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Tidskriftsartikel (refereegranskat)abstract
- Abstract Jatropha curcas is a promising source of oil for the biodiesel industry, and the shells of its fruits could be considered for ethanol production. In this work, the composition of J. curcas shells is investigated, and the potential of dilute-sulphuric acid pretreatment for improving the enzymatic hydrolysis of cellulose is evaluated. A Box–Behnken experimental design was used for assessing the effect of temperature (110–150 °C), H2SO4 concentration (0.5–2.5%) and pretreatment time (15–45 min) on the formation of sugars during pretreatment and on the enzymatic conversion of cellulose. Cellulose conversions above 80% were achieved both in the separated enzymatic hydrolysis and in the simultaneous saccharification and fermentation of the pretreated materials. Optimal SSF conversions were predicted for pretreatments at low temperature (136 °C) and moderate acid concentrations (1.5%) and reaction time (30 min). The inclusion of an extraction step prior to the pretreatment revealed a further improvement of the enzymatic conversion of cellulose.
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| 8. |
- Ugalde Loo, Carlos Ernesto, et al.
(författare)
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Individual Channel Analysis of the Thyristor-Controlled Series Compensator Performance
- 2010
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Ingår i: International Journal of Emerging Electric Power Systems. - 2194-5756 .- 1553-779X. ; 11:2
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Tidskriftsartikel (refereegranskat)abstract
- The TCSC is the electronically-controlled counterpart of the conventional series bank of capacitors. A mature member of the FACTS technology, the TCSC has the ability to regulate power flows along the compensated line and to rapidly modulate its effective impedance. In this paper its performance is evaluated using Individual Channel Analysis and Design. Fundamental analysis is carried out to explain the generator dynamic behavior as affected by the TCSC. Moreover, a control system design for the system is presented, with particular emphasis in the closed-loop performance and stability and structural robustness assessment. It is formally shown that the incorporation of a TCSC operating in its capacitive range improves the dynamical performance of the synchronous machine by decreasing the electrical distance and therefore considerably reducing the awkward switchback characteristic exhibited by synchronous generators. It is also formally proven in the paper that the inductive operation should be avoided as it impairs system operation. In general, the TCSC inclusion brings on fragility into the global system, making it non-minimum phase and introducing adverse dynamics in the speed channel of the synchronous machine. Moreover, it is shown that the minimum-phase condition may also be present in cases featuring high capacitive compensation levels.
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