| 1. |
- Feroci, M., et al.
(författare)
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The large observatory for x-ray timing
- 2014
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE. - 9780819496126
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Konferensbidrag (refereegranskat)abstract
- The Large Observatory For x-ray Timing (LOFT) was studied within ESA M3 Cosmic Vision framework and participated in the final downselection for a launch slot in 2022-2024. Thanks to the unprecedented combination of effective area and spectral resolution of its main instrument, LOFT will study the behaviour of matter under extreme conditions, such as the strong gravitational field in the innermost regions of accretion flows close to black holes and neutron stars, and the supranuclear densities in the interior of neutron stars. The science payload is based on a Large Area Detector (LAD, 10 m2 effective area, 2-30 keV, 240 eV spectral resolution, 1° collimated field of view) and a Wide Field Monitor (WFM, 2-50 keV, 4 steradian field of view, 1 arcmin source location accuracy, 300 eV spectral resolution). The WFM is equipped with an on-board system for bright events (e.g. GRB) localization. The trigger time and position of these events are broadcast to the ground within 30 s from discovery. In this paper we present the status of the mission at the end of its Phase A study.
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| 2. |
- Feroci, M., et al.
(författare)
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LOFT - The large observatory for x-ray timing
- 2012
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Ingår i: Proceedings of SPIE - The International Society for Optical Engineering. - : SPIE - International Society for Optical Engineering. - 9780819491442 ; , s. 84432D-
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Konferensbidrag (refereegranskat)abstract
- The LOFT mission concept is one of four candidates selected by ESA for the M3 launch opportunity as Medium Size missions of the Cosmic Vision programme. The launch window is currently planned for between 2022 and 2024. LOFT is designed to exploit the diagnostics of rapid X-ray flux and spectral variability that directly probe the motion of matter down to distances very close to black holes and neutron stars, as well as the physical state of ultradense matter. These primary science goals will be addressed by a payload composed of a Large Area Detector (LAD) and a Wide Field Monitor (WFM). The LAD is a collimated (<1 degree field of view) experiment operating in the energy range 2-50 keV, with a 10 m2 peak effective area and an energy resolution of 260 eV at 6 keV. The WFM will operate in the same energy range as the LAD, enabling simultaneous monitoring of a few-steradian wide field of view, with an angular resolution of <5 arcmin. The LAD and WFM experiments will allow us to investigate variability from submillisecond QPO's to yearlong transient outbursts. In this paper we report the current status of the project.
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| 6. |
- Bodin, Per, et al.
(författare)
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Comparing the performance of different stomatal conductance models using modelled and measured plant carbon isotope ratios (δ(13) C): implications for assessing physiological forcing
- 2013
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013. ; 19:6, s. 1709-1719
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Tidskriftsartikel (refereegranskat)abstract
- Accurate modelling of long-term changes in plant stomatal functioning is vital to global climate change studies because changes in evapotranspiration influence temperature via physiological forcing of the climate. Various stomatal models are included in land surface schemes, but their robustness over longer timescales is difficult to validate. We compare the performance of three stomatal models, varying in their degree of complexity, and coupled to a land surface model. This is done by simulating the carbon isotope ratio of tree leaves (δ(13) Cleaf ) over a period of 53 years, and comparing the results with carbon isotope ratios obtained from tree rings (δ(13) Cstem ) measured at six sites in northern Europe. All three stomatal models fail to capture the observed inter-annual variability in the measured δ(13) Cstem time series. However, the Soil-Plant-Atmosphere (SPA) model performs significantly better than the Ball-Berry (BB) or COX models when tested for goodness of fit against measured δ(13) Cstem . The δ(13) Cleaf time series simulated using the SPA model are significantly positively correlated (p < 0.05) with measured results over the full time period tested, at all six sites. The SPA model underestimates inter-annual variability measured in δ(13) Cstem , but is no worse than the BB model and significantly better than the COX model. The inability of current models to adequately replicate changes in stomatal response to rising levels of CO2 concentrations, and thus to quantify the associated physiological forcing, warrants further investigation. © 2013 Blackwell Publishing Ltd.
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| 7. |
- Maury, O., et al.
(författare)
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A global science-policy partnership for progress toward sustainability of oceanic ecosystems and fisheries
- 2013
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Ingår i: Current Opinion in Environmental Sustainability. - : Elsevier BV. - 1877-3435 .- 1877-3443. ; 5:3-4, s. 314-319
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Forskningsöversikt (refereegranskat)abstract
- Oceanic ecosystems support livelihoods and supply food for hundreds of millions of people. But these ecosystems are deteriorating rapidly and many of the world's oceanic fisheries are in a precarious condition. In addition to well-known and pressing fishery management issues, economic globalization is connecting fisheries beyond the frontiers of the organizations responsible for their management and climate-associated changes are deeply modifying ecosystems, pushing them toward new states and no return situations. The status quo is not a sustainable option, and improved international governance is urgently needed to address this situation. Our proposition consists of an inclusive global science-policy process combining major improvements to the present governance systems, including new incentives for international cooperation and coordination, with an ambitious scientific program to help anticipate threats and opportunities and integrate complex information regarding long-term issues. It would constitute a major step toward sustainability.
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| 8. |
- Meng, Xinzhu, et al.
(författare)
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Dynamics and management of stage-structured fish stocks
- 2013
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Ingår i: Bulletin of Mathematical Biology. - : Springer. - 0092-8240 .- 1522-9602. ; 75:1, s. 1-23
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Tidskriftsartikel (refereegranskat)abstract
- With increasing fishing pressures having brought several stocks to the brink of collapse, there is a need for developing efficient harvesting methods that account for factors beyond merely yield or profit. We consider the dynamics and management of a stage-structured fish stock. Our work is based on a consumer-resource model which De Roos et al. (in Theor. Popul. Biol. 73, 47-62, 2008) have derived as an approximation of a physiologically-structured counterpart. First, we rigorously prove the existence of steady states in both models, that the models share the same steady states, and that there exists at most one positive steady state. Furthermore, we carry out numerical investigations which suggest that a steady state is globally stable if it is locally stable. Second, we consider multiobjective harvesting strategies which account for yield, profit, and the recovery potential of the fish stock. The recovery potential is a measure of how quickly a fish stock can recover from a major disturbance and serves as an indication of the extinction risk associated with a harvesting strategy. Our analysis reveals that a small reduction in yield or profit allows for a disproportional increase in recovery potential. We also show that there exists a harvesting strategy with yield close to the maximum sustainable yield (MSY) and profit close to that associated with the maximum economic yield (MEY). In offering a good compromise between MSY and MEY, we believe that this harvesting strategy is preferable in most instances. Third, we consider the impact of harvesting on population size structure and analytically determine the most and least harmful harvesting strategies. We conclude that the most harmful harvesting strategy consists of harvesting both adults and juveniles, while harvesting only adults is the least harmful strategy. Finally, we find that a high percentage of juvenile biomass indicates elevated extinction risk and might therefore serve as an early-warning signal of impending stock collapse.
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| 9. |
- Ray, Jeremy, 1969, et al.
(författare)
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Heritability of dental fear.
- 2010
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Ingår i: Journal of dental research. - : SAGE Publications. - 1544-0591 .- 0022-0345. ; 89:3, s. 297-301
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Tidskriftsartikel (refereegranskat)abstract
- The objective was to test a hypothesized genetic component (i.e., monozygotic being more similar compared with dizygotic twins) in dental fear/anxiety by comparing the probandwise concordance. We analyzed data based on a dichotomous measure of Dental Fear/Anxiety and a continuous measure of Dental Fear Intensity from over 2000 twins, collected when participants were 13-14 years old and once again three years later. The hypothesis was confirmed, but heritability of Dental Fear/Anxiety was estimated to be higher for girls (0.77 at time 1 and 0.55 at time 2) than for boys (0.14 and 0.0 at times 1 and 2, respectively). Heritability of Dental Fear Intensity, however, was similar for girls (0.30 and 0.40 at times 1 and 2, respectively) and boys (0.47, 0.44). Studies of the etiology of dental fear/anxiety should take genetic vulnerability into account and include molecular biology measures. Possible heritability differences between girls and boys need attention.
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