| 1. |
- Aaron, F. D., et al.
(författare)
-
Multi-leptons with high transverse momentum at HERA
- 2009
-
Ingår i: Journal of High Energy Physics. - : Springer Science and Business Media LLC. - 1029-8479. ; :10
-
Tidskriftsartikel (refereegranskat)abstract
- Events with at least two high transverse momentum leptons (electrons or muons) are studied using the H1 and ZEUS detectors at HERA with an integrated luminosity of 0.94 fb(-1). The observed numbers of events are in general agreement with the Standard Model predictions. Seven di- and tri-lepton events are observed in e(+)p collision data with a scalar sum of the lepton transverse momenta above 100 GeV while 1.94 +/- 0.17 events are expected. Such events are not observed in e(-)p collisions for which 1.19 +/- 0.12 are predicted. Total visible and differential di-electron and di-muon photoproduction cross sections are extracted in a restricted phase space dominated by photon-photon collisions.
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| 2. |
- Abazov, V. M., et al.
(författare)
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The upgraded DO detector
- 2006
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 565:2, s. 463-537
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Tidskriftsartikel (refereegranskat)abstract
- The DO experiment enjoyed a very successful data-collection run at the Fermilab Tevatron collider between 1992 and 1996. Since then, the detector has been upgraded to take advantage of improvements to the Tevatron and to enhance its physics capabilities. We describe the new elements of the detector, including the silicon microstrip tracker, central fiber tracker, solenoidal magnet, preshower detectors, forward muon detector, and forward proton detector. The uranium/liquid -argon calorimeters and central muon detector, remaining from Run 1, are discussed briefly. We also present the associated electronics, triggering, and data acquisition systems, along with the design and implementation of software specific to DO.
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| 3. |
- Amoignon, Olivier, 1969-
(författare)
-
Numerical Methods for Aerodynamic Shape Optimization
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gradient-based aerodynamic shape optimization, based on Computational Fluid Dynamics analysis of the flow, is a method that can automatically improve designs of aircraft components. The prospect is to reduce a cost function that reflects aerodynamic performances.When the shape is described by a large number of parameters, the calculation of one gradient of the cost function is only feasible by recourse to techniques that are derived from the theory of optimal control. In order to obtain the best computational efficiency, the so called adjoint method is applied here on the complete mapping, from the parameters of design to the values of the cost function. The mapping considered here includes the Euler equations for compressible flow discretized on unstructured meshes by a median-dual finite-volume scheme, the primal-to-dual mesh transformation, the mesh deformation, and the parameterization. The results of the present research concern the detailed derivations of expressions, equations, and algorithms that are necessary to calculate the gradient of the cost function. The discrete adjoint of the Euler equations and the exact dual-to-primal transformation of the gradient have been implemented for 2D and 3D applications in the code Edge, a program of Computational Fluid Dynamics used by Swedish industries.Moreover, techniques are proposed here in the aim to further reduce the computational cost of aerodynamic shape optimization. For instance, an interpolation scheme is derived based on Radial Basis Functions that can execute the deformation of unstructured meshes faster than methods based on an elliptic equation.In order to improve the accuracy of the shape, obtained by numerical optimization, a moving mesh adaptation scheme is realized based on a variable diffusivity equation of Winslow type. This adaptation has been successfully applied on a simple case of shape optimization involving a supersonic flow. An interpolation technique has been derived based on a mollifier in order to improve the convergence of the coupled mesh-flow equations entering the adaptive scheme.The method of adjoint derived here has also been applied successfully when coupling the Euler equations with the boundary-layer and parabolized stability equations, with the aim to delay the laminar-to-turbulent transition of the flow. The delay of transition is an efficient way to reduce the drag due to viscosity at high Reynolds numbers.
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| 4. |
- Graae, Bente J., et al.
(författare)
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Germination requirements and seed mass of slow- and fast-colonizing temperate forest herbs along a latitudinal gradient
- 2009
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Ingår i: Écoscience. - : Informa UK Limited. - 1195-6860 .- 2376-7626. ; 16:2, s. 248-257
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Tidskriftsartikel (refereegranskat)abstract
- Predictions on displacement of suitable habitats due to climate change suggest that plant species with poor colonization ability may be unable to move fast enough to match forecasted climate-induced changes in habitat distribution. However, studies on early Holocene plant migration show fast migration of many plant species that are poor colonizers today We hypothesize that warmer temperatures during the early Holocene yielded higher seed quality, contributing to explaining the fast migration. We studied how the 3 seed quality variables, seed mass, germinability, and requirements for break of seed dormancy, vary for seeds of 11 forest herb species with varying colonization capacity collected along a 1400-km latitudinal gradient. Within species, seed mass showed a positive correlation with latitude, whereas germinability was more positively correlated with temperature (growing degree hours obtained at time of seed collection). Only slow-colonizing species increased germinability with temperature, whereas only fast-colonizing species increased germinability with latitude. These interactions were only detectable when analyzing germinability of the seeds, even though this trait and seed mass were correlated. The requirement for dormancy break did not correlate with latitude or temperature. The results indicate that seed development of slow colonizers may be favoured by a warmer climate, which in turn may be important for their migration capacity.
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| 5. |
- Koning, Olivier H. J., et al.
(författare)
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Fluoroscopic Roentgen stereophotogrammetric analysis (FRSA) to study three-dimensional stent graft dynamics
- 2009
-
Ingår i: Journal of Vascular Surgery. - : Elsevier BV. - 1097-6809 .- 0741-5214. ; 50:2, s. 407-412
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Tidskriftsartikel (refereegranskat)abstract
- We report the clinical feasibility of fluoroscopic Roentgen stereophotogrammetric analysis (FRSA), a validated method to quantify, real time three-dimensional (3D) dynamic motion of stent grafts and the first clinical results after abdominal and thoracic endovascular repair (EVAR). Stent graft motion was measured at 30 (stereo) frames per second, during the cardiac cycle and in the patient after abdominal EVAR, due to respiratory action. Translational motions of the center of mass, diameter change, and rotational and axial motion could be measured. Quantification of 3D motion was not available until now. FRSA can provide crucial information on the forces exerted oil stent grafts and will, therefore, provide essential information for improvements in stent graft design. (J Vasc Surg 2009;50:407-12.)
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| 6. |
- Aaron, F. D., et al.
(författare)
-
Deeply virtual Compton scattering and its beam charge asymmetry in e(+/-)p collisions at HERA
- 2009
-
Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 681:5, s. 391-399
-
Tidskriftsartikel (refereegranskat)abstract
- A measurement of elastic deeply virtual Compton scattering gamma*p --> gamma p using e(+) p and e(-) p collision data recorded with the HI detector at HERA is presented. The analysed data sample corresponds to an integrated luminosity of 306 pb(-1), almost equally shared between both beam charges. The cross section is measured as a function of the virtuality Q(2) of the exchanged photon and the centre-of-mass energy W of the gamma*p system in the kinematic domain 6.5 < Q(2) < 80 GeV2, 30 < W < 140 GeV and |t| < 1 GeV2, where t denotes the squared momentum transfer at the proton vertex. The cross section is determined differentially in t for different Q(2) and W values and exponential t-slope parameters are derived. Using e(+) p and e(-) p data samples, a beam charge asymmetry is extracted for the first time in the low Biorken x kinematic domain. The observed asymmetry is attributed to the interference between Bethe-Heitler and deeply virtual Compton scattering processes. Experimental results are discussed in the context of two different models, one based on generalised parton distributions and one based on the dipole approach. (C) 2009 Elsevier B.V. All rights reserved.
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| 7. |
- Aaron, F. D., et al.
(författare)
-
Observation of the hadronic final state charge asymmetry in high Q(2) deep-inelastic scattering at HERA
- 2009
-
Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 681:2, s. 125-133
-
Tidskriftsartikel (refereegranskat)abstract
- A first measurement is presented of the charge asymmetry in the hadronic final state from the hard interaction in deep-inelastic ep neutral current scattering at HERA. The measurement is performed in the range of negative squared four momentum transfer 100 < Q(2) < 8000 GeV2. The difference between the event normalised distributions of the scaled momentum, x(p), for positively and negatively charged particles, measured in the current region of the Breit frame, is studied together with its evolution as a function of Q. The results are compared to Monte Carlo models at the hadron and parton levels. (C) 2009 Elsevier B.V. All rights reserved.
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| 8. |
- Aaron, F. D., et al.
(författare)
-
Search for single top quark production at HERA
- 2009
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Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 678:5, s. 450-458
-
Tidskriftsartikel (refereegranskat)abstract
- A search for single top quark production is performed in the full e(+/-)p data sample collected by the H1 experiment at HERA, corresponding to an integrated luminosity of 474 pb(-1). Decays of top quarks into a b quark and a W boson with Subsequent leptonic or hadronic decay of the W are investigated. A multivariate analysis is performed to discriminate top quark production from Standard Model background processes. An upper limit on the top quark production cross section via flavour changing neutral current processes sigma(ep -> et X) < 0.25 pb is established at 95% CL. Limits on the anomalous coupling K-tu gamma are derived. (C) 2009 Elsevier B.V. All rights reserved.
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| 9. |
- Aktas, A, et al.
(författare)
-
A direct search for stable magnetic monopoles produced in positron-proton collisions at HERA
- 2005
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Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 41, s. 133-141
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Tidskriftsartikel (refereegranskat)abstract
- A direct search has been made for magnetic monopoles produced in e(+)p collisions at a centre of mass energy of 300 GeV at HERA. The beam pipe surrounding the interaction region in 1995-1997 was investigated using a SQUID magnetometer to look for stopped magnetic monopoles. During this time an integrated luminosity of 62 pb(-1) was delivered. No magnetic monopoles were observed and charge and mass dependent upper limits on the e(+)p production cross section are set.
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| 10. |
- Aktas, A, et al.
(författare)
-
Inclusive production of D+, D-0, D-s(+) and D*(+) mesons in deep inelastic scattering at HERA
- 2005
-
Ingår i: European Physical Journal C. Particles and Fields. - : Springer Science and Business Media LLC. - 1434-6044. ; 38:4, s. 447-459
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Tidskriftsartikel (refereegranskat)abstract
- Inclusive production cross sections are measured in deep inelastic scattering at HERA for meson states composed of a charm quark and a light antiquark or the charge conjugate. The measurements cover the kinematic region of photon virtuality 2 < Q(2) < 100 GeV2, inelasticity 0.05 < y < 0.7, D meson transverse momenta p(t)( D) greater than or equal to 2.5 GeV and pseudorapidity |eta( D)| less than or equal to 1.5. The identification of the D-meson decays and the reduction of the combinatorial background profit from the reconstruction of displaced secondary vertices by means of the H1 silicon vertex detector. The production of charmed mesons containing the light quarks u, d and s is found to be compatible with a description in which the hard scattering is followed by a factorisable and universal hadronisation process.
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| 11. |
- Aktas, A, et al.
(författare)
-
Measurement of charm and beauty photoproduction at HERA using D*mu correlations
- 2005
-
Ingår i: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 621:1-2, s. 56-71
-
Tidskriftsartikel (refereegranskat)abstract
- A measurement of charm and beauty photoproduction at the electron proton collider HERA is presented based on the simultaneous detection of a D*(+/-) meson and a muon. The correlation between the D* meson and the muon serves to separate the charm and beauty contributions and the analysis provides comparable sensitivity to both. The total and differential experimental cross sections are compared to LO and NLO QCD calculations. The measured charm cross section is in good agreement with QCD predictions including higher order effects while the beauty cross section is higher.
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| 12. |
- Amoignon, Olivier, et al.
(författare)
-
Adjoint of a median-dual finite-volume scheme : Application to transonic aerodynamic shape optimization
- 2006
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The sensitivity analysis is a crucial step in algorithms for gradient-based aerodynamic shape optimization. The analysis involves computing the gradient of functionals such as drag, lift, or aerodynamic moments, with respect to the parameters of the design. Gradients are efficiently calculated by solving adjoints of the linearized flow equations. The flow is modeled by the Euler equations of gas dynamics, solved in Edge, a Computational Fluid Dynamics (CFD) code for unstructured meshes. The adjoint equations and expressions for the gradients are derived here in the fully discrete case, that is, the mappings from the design variables to the functional's values involve the discretized flow equations, a mesh deformation equation, and the parameterization of the geometry. We present a formalism and basic properties that enable a compact derivation of the adjoint for discretized flow equations obeying an edge-based structure, such as the vertex-centered median-dual finite volume discretization implemented in Edge. This approach is applied here to the optimization of the RAE 2822 airfoil and the ONERA M6 wing. In particular, we show a method to parameterize the shape, in 2D, in order to enforce smoothness and linear geometrical constraints.
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| 13. |
- Amoignon, Olivier, et al.
(författare)
-
Shape optimization for delay of laminar-turbulent transition
- 2006
-
Ingår i: AIAA Journal. - : American Institute of Aeronautics and Astronautics (AIAA). - 0001-1452 .- 1533-385X. ; 44:5, s. 1009-1024
-
Tidskriftsartikel (refereegranskat)abstract
- A method using gradient-based optimization is introduced for the design of wing profiles with the aim of natural laminar How, as well as minimum wave drag. The Euler equations of gasdynamics, the laminar boundary-layer equations for compressible flows on infinite swept wings, and the linear parabolized stability equations (PSE) are solved to analyze the evolution of convectively unstable disturbances. Laminar-turbulent transition is assumed to be delayed by minimizing a measure of the disturbance kinetic energy of a chosen disturbance, which is computed using the PSE. The shape gradients of the disturbance kinetic energy are computed based on the solutions of the adjoints of the state equations just named. Numerical tests are carried out to optimize the RAE 2822 airfoil with the aim to delay simultaneously the transition, reduce the pressure drag coefficient, and maintain the coefficients of lift and pitch moments. Constraints are also applied on the geometry. Results show a reduction of the total amplification of a large number of disturbances, which is assumed to represent a delay of the transition in the boundary layer. Because delay of the transition implies reduction of the viscous drag, the present method enables shape optimization to perform viscous drag reduction.
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| 14. |
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| 15. |
- Ewert, Frank, et al.
(författare)
-
A methodology for enhanced flexibility of integrated assessment in agriculture
- 2009
-
Ingår i: Environmental Science and Policy. - : Elsevier BV. - 1462-9011. ; 12:5, s. 546-561
-
Tidskriftsartikel (refereegranskat)abstract
- Agriculture is interrelated with the socio-economic and natural environment and faces increasingly the problem of managing its multiple functions in a sustainable way. Growing emphasis is on adequate policies that can support both agriculture and sustainable development. Integrated Assessment and Modelling (IAM) can provide insight into the potential impacts of policy changes. An increasing number of Integrated Assessment (IA) models are being developed, but these are mainly monolithic and are targeted to answer specific problems. Approaches that allow flexible IA for a range of issues and functions are scarce. Recently, a methodology for policy support in agriculture has been developed that attempts to overcome some of the limitations of earlier IA models. The proposed framework (SEAMLESS-IF) integrates relationships and processes across disciplines and scales and combines quantitative analysis with qualitative judgments and experiences. It builds on the concept of systems analysis and attempts to enable flexible coupling of models and tools. The present paper aims to describe progress in improving flexibility of IAM achieved with the methodology developed for SEAMLESS-IF. A brief literature review identifying limitations in the flexibility of IAM is followed by a description of the progress achieved with SEAMLESS-IF. Two example applications are used to illustrate relevant capabilities of SEAMLESS-IF. The examples refer to (i) the impacts on European agriculture of changes in world trade regulations and (ii) regional impacts of the EU Nitrates Directive in combination with agro-management changes. We show that improving the flexibility of IAM requires flexibility in model linking but also a generic set up of all IA steps. This includes problem and scenario definition, the selection and specification of indicators and the indicator framework, the structuring of the database, and the visualization of results. Very important is the flexibility to integrate, select and link models, data and indicators depending on the application. Technical coupling and reusability of model components is greatly improved through adequate software architecture (SEAMLESS-IF uses OpenMI). The use of ontology strongly supports conceptual consistency of model linkages. However, the scientific basis for linking models across disciplines and scales is still weak and requires specific attention in future research. We conclude that the proposed framework significantly advances flexibility in IAM and that it is a good basis to further improve integrated modelling for policy impact assessment in agriculture. (C) 2009 Elsevier Ltd. All rights reserved.
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| 16. |
- Hell, Martin, et al.
(författare)
-
The Grain family of stream ciphers
- 2008
-
Ingår i: New Stream Cipher Designs - The eSTREAM Finalists. - 0302-9743 .- 1611-3349. - 9783540683506 ; , s. 179-190
-
Bokkapitel (refereegranskat)abstract
- Abstract in UndeterminedA new family of stream ciphers, Grain, is proposed. Two variants, a 80-bit and a 128-bit variant are specified, denoted Grain and Grain-128 respectively. The designs target hardware environments where gate count, power consumption and memory are very limited. Both variants are based on two shift registers and a nonlinear output function. The ciphers also have the additional feature that the speed can be easily increased at the expense of extra hardware.
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| 17. |
- Klug, Stefanie J, et al.
(författare)
-
TP53 codon 72 polymorphism and cervical cancer : a pooled analysis of individual data from 49 studies
- 2009
-
Ingår i: The Lancet Oncology. - 1470-2045 .- 1474-5488. ; 10:8, s. 772-784
-
Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Cervical cancer is caused primarily by human papillomaviruses (HPV). The polymorphism rs1042522 at codon 72 of the TP53 tumour-suppressor gene has been investigated as a genetic cofactor. More than 80 studies were done between 1998 and 2006, after it was initially reported that women who are homozygous for the arginine allele had a risk for cervical cancer seven times higher than women who were heterozygous for the allele. However, results have been inconsistent. Here we analyse pooled data from 49 studies to determine whether there is an association between TP53 codon 72 polymorphism and cervical cancer. METHODS: Individual data on 7946 cases and 7888 controls from 49 different studies worldwide were reanalysed. Odds ratios (OR) were estimated using logistic regression, stratifying by study and ethnic origin. Subgroup analyses were done for infection with HPV, ethnic origin, Hardy-Weinberg equilibrium, study quality, and the material used to determine TP53 genotype. FINDINGS: The pooled estimates (OR) for invasive cervical cancer were 1.22 (95% CI 1.08-1.39) for arginine homozygotes compared with heterozygotes, and 1.13 (0.94-1.35) for arginine homozygotes versus proline homozygotes. Subgroup analyses showed significant excess risks only in studies where controls were not in Hardy-Weinberg equilibrium (1.71 [1.21-2.42] for arginine homozygotes compared with heterozygotes), in non-epidemiological studies (1.35 [1.15-1.58] for arginine homozygotes compared with heterozygotes), and in studies where TP53 genotype was determined from tumour tissue (1.39 [1.13-1.73] for arginine homozygotes compared with heterozygotes). Null results were noted in studies with sound epidemiological design and conduct (1.06 [0.87-1.29] for arginine homozygotes compared with heterozygotes), and studies in which TP53 genotype was determined from white blood cells (1.06 [0.87-1.29] for arginine homozygotes compared with heterozygotes). INTERPRETATION: Subgroup analyses indicated that excess risks were most likely not due to clinical or biological factors, but to errors in study methods. No association was found between cervical cancer and TP53 codon 72 polymorphism when the analysis was restricted to methodologically sound studies.
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| 18. |
- Motte, Damien, et al.
(författare)
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Mechanical embodiment design with digital desktops
- 2007
-
Ingår i: Interactive Tables Workshop at the 19th AFIHM Conference. - 9781595937919 ; Appendix, s. 31-34
-
Konferensbidrag (refereegranskat)abstract
- This paper describes the potential help that the interactive desktop concept can bring to the execution of embodiment design tasks. The presented project is still in its infancy. The research framework is the following: once a product concept has been approved, the mechanical design engineer develops the product architecture and product part (also called embodiment design). Sketches at that level are essential both for synthesis and analysis purposes. Moreover, the designer has often to collaborate with the production department. The current CAD tools do not allow the same freedom, sensitivity nor the same possibility of communication and understanding the sketch. The interactive desktop is a technical mean that would allow taking into account the majority of the mechanical design engineer needs during embodiment design.
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| 19. |
- Peter, Yves-Alain, et al.
(författare)
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Introduction to the Issue on Nanophotonics and Optical MEMS
- 2009
-
Ingår i: IEEE Journal of Selected Topics in Quantum Electronics. - : IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC. - 1077-260X .- 1558-4542. ; 15:5, s. 1307-1309
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 20. |
- Petit, Olivier, 1980, et al.
(författare)
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The ERCOFTAC centrifugal pump OpenFOAM case-study
- 2009
-
Ingår i: IAHR International Meeting of the Workgroup on Cavitation and Dynamic Problems in Hydraulic Machinery and Systems. - 9788021439474 ; , s. 523-532
-
Konferensbidrag (refereegranskat)abstract
- This work investigates the rotor-stator interaction features of OpenFOAM-1.5-dev, such as frozenrotor and sliding grid. The case studied is the ERCOFTAC Test Case U3: Centrifugal Pump with aVaned Diffuser, a testcase from the ERCOFTAC Turbomachinery Special Interest Group. The casewas presented by Combès at the ERCOFTAC Seminar and Workshop on Turbomachinery FlowPrediction VII, in Aussois, 1999. It is a valid test case for evaluation of rotor-stator interactionfeatures, as detailed experimental data is available.The investigation shows that OpenFOAM gives results that are comparable to the experimental data,in particular for the sliding grid case. The results are less accurate in the frozen rotor simulation due tothe improper treatment of the impeller wakes that is part of the frozen rotor formulation.The ERCOFTAC centrifugal pump OpenFOAM case-study was developed as a contribution to theOpenFOAM Turbomachinery Working Group, and was presented and discussed at the FourthOpenFOAM Workshop in Montréal, 2009. The complete set-up of the case-study is available from theOpenFOAM-extend project at SourceForge, and instructions and comments are available from theOpenFOAM Wiki.
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| 21. |
- Post, Eric, et al.
(författare)
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Ecological Dynamics Across the Arctic Associated with Recent Climate Change
- 2009
-
Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 1095-9203 .- 0036-8075. ; 325:5946, s. 1355-1358
-
Forskningsöversikt (refereegranskat)abstract
- At the close of the Fourth International Polar Year, we take stock of the ecological consequences of recent climate change in the Arctic, focusing on effects at population, community, and ecosystem scales. Despite the buffering effect of landscape heterogeneity, Arctic ecosystems and the trophic relationships that structure them have been severely perturbed. These rapid changes may be a bellwether of changes to come at lower latitudes and have the potential to affect ecosystem services related to natural resources, food production, climate regulation, and cultural integrity. We highlight areas of ecological research that deserve priority as the Arctic continues to warm.
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| 22. |
- Therond, Olivier, et al.
(författare)
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Methodology to translate policy assessment problems into scenarios: the example of the SEAMLESS integrated framework
- 2009
-
Ingår i: Environmental Science and Policy. - : Elsevier BV. - 1462-9011. ; 12:5, s. 619-630
-
Tidskriftsartikel (refereegranskat)abstract
- Scenario-based approaches in environmental and policy assessment studies are increasingly applied within integrated assessment and modelling frameworks. The SEAMLESS project develops such an integrated framework (SEAMLESS-IF) aiming to assess, ex-ante, impacts of alternative agro-environmental policies on the sustainability of agricultural systems. A particular challenge in this context is the consistent translation of a wide range of policy questions into scenarios that a modelling framework can assess. The present work defines a methodology for scenario-development in integrated policy assessment with specific emphasis on SEAMLESS-IF. After a general overview on scenario concepts for integrated policy assessment the adopted scenario concept and its development procedure is presented. They allow building integrated scenarios capturing the range of drivers of the assessed agricultural system in a consistent way across temporal and spatial scales. Then focus is on the particular procedures to translate the policy assessment questions into scenario parameters and to implement these parameters into SEAMLESS-IF. Two examples targeted at European and regional level combining integrated assessments of policy changes and technological innovations are considered to illustrate the SEAMLESS scenario concept. We conclude that the proposed methodology to translate policy assessment problems into scenarios effectively supports integrated assessment in SEAMLESS-IF or even in other modelling frameworks. (C) 2009 Elsevier Ltd. All rights reserved.
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| 23. |
- van de Pavert, Serge A., et al.
(författare)
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Chemokine CXCL13 is essential for lymph node initiation and is induced by retinoic acid and neuronal stimulation
- 2009
-
Ingår i: Nature Immunology. - : Springer Science and Business Media LLC. - 1529-2908 .- 1529-2916. ; 10:11, s. 78-1193
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Tidskriftsartikel (refereegranskat)abstract
- The location of embryonic lymph node development is determined by the initial clustering of lymphoid tissue-inducer (LTi) cells. Here we demonstrate that both the chemokine CXCL13 and the chemokine CCL21 attracted LTi cells at embryonic days 12.5-14.5 and that initial clustering depended exclusively on CXCL13. Retinoic acid (RA) induced early CXCL13 expression in stromal organizer cells independently of lymphotoxin signaling. Notably, neurons adjacent to the lymph node anlagen expressed enzymes essential for RA synthesis. Furthermore, stimulation of parasymphathetic neural output in adults led to RA receptor (RAR)-dependent induction of CXCL13 in the gut. Therefore, our data show that the initiation of lymph node development is controlled by RA-mediated expression of CXCL13 and suggest that RA may be provided by adjacent neurons.
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| 24. |
- Vellend, Mark, et al.
(författare)
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Homogenization of forest plant communities and weakening of species–environment relationships via agricultural land use
- 2007
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 95, s. 565-573
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Tidskriftsartikel (refereegranskat)abstract
- 1Disturbance may cause community composition across sites to become more or less homogenous, depending on the importance of different processes involved in community assembly. In north-eastern North America and Europe local (alpha) diversity of forest plants is lower in forests growing on former agricultural fields (recent forests) than in older (ancient) forests, but little is known about the influence of land-use history on the degree of compositional differentiation among sites (beta diversity).2Here we analyse data from 1446 sites in ancient and recent forests across 11 different landscapes in north-eastern North America and Europe to demonstrate decreases in beta diversity and in the strength of species–environment relationships in recent vs. ancient forests.3The magnitude of environmental variability among sites did not differ between the two forest types. This suggests the difference in beta diversity between ancient and recent forests was not due to different degrees of environmental heterogeneity, but rather to dispersal filters that constrain the pool of species initially colonizing recent forests.4The observed effects of community homogenization and weakened relationships between species distributions and environmental gradients appear to persist for decades or longer. The legacy of human land-use history in spatial patterns of biodiversity may endure, both within individual sites and across sites, for decades if not centuries.
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