| 1. |
- 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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| 2. |
- 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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| 3. |
- Bressan, Alberto, et al.
(författare)
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Global conservative solutions of the Camassa-Holm equation
- 2007
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Ingår i: Archive for Rational Mechanics and Analysis. - : Springer Science and Business Media LLC. - 0003-9527 .- 1432-0673. ; 183:2, s. 215-239
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Tidskriftsartikel (refereegranskat)abstract
- This paper develops a new approach in the analysis of the Camassa-Holm equation. By introducing a new set of independent and dependent variables, the equation is transformed into a semilinear system, whose solutions are obtained as fixed points of a contractive transformation. These new variables resolve all singularities due to possible wave breaking. Returning to the original variables, we obtain a semigroup of global solutions, depending continuously on the initial data. Our solutions are conservative, in the sense that the total energy equals a constant, for almost every time.
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| 4. |
- Bressan, Alberto, et al.
(författare)
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Global dissipative solutions of the Camassa-Holm equation
- 2007
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Ingår i: Analysis and Applications. - 1793-6861. ; 5:1, s. 1-27
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Tidskriftsartikel (refereegranskat)abstract
- This paper is devoted to the continuation of solutions to the Camassa-Holm equation after wave breaking. By introducing a new set of independent and dependent variables, the evolution problem is rewritten as a semilinear hyperbolic system in an L-infinity space, containing a non-local source term which is discontinuous but has bounded directional variation. For a given initial condition, the Cauchy problem has a unique solution obtained as fixed point of a contractive integral transformation. Returning to the original variables, we obtain a semigroup of global dissipative solutions, defined for every initial data (u) over bar epsilon H-1(IR), and continuously depending on the initial data. The new variables resolve all singularities due to possible wave breaking and ensure that energy loss occurs only through wave breaking.
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| 5. |
- Chang, Dan, et al.
(författare)
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The evolutionary and phylogeographic history of woolly mammoths : a comprehensive mitogenomic analysis
- 2017
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 7
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Tidskriftsartikel (refereegranskat)abstract
- Near the end of the Pleistocene epoch, populations of the woolly mammoth (Mammuthus primigenius) were distributed across parts of three continents, from western Europe and northern Asia through Beringia to the Atlantic seaboard of North America. Nonetheless, questions about the connectivity and temporal continuity of mammoth populations and species remain unanswered. We use a combination of targeted enrichment and high-throughput sequencing to assemble and interpret a data set of 143 mammoth mitochondrial genomes, sampled from fossils recovered from across their Holarctic range. Our dataset includes 54 previously unpublished mitochondrial genomes and significantly increases the coverage of the Eurasian range of the species. The resulting global phylogeny confirms that the Late Pleistocene mammoth population comprised three distinct mitochondrial lineages that began to diverge ~1.0–2.0 million years ago (Ma). We also find that mammoth mitochondrial lineages were strongly geographically partitioned throughout the Pleistocene. In combination, our genetic results and the pattern of morphological variation in time and space suggest that male-mediated gene flow, rather than large-scale dispersals, was important in the Pleistocene evolutionary history of mammoths.
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| 6. |
- Constantin, Adrian
(författare)
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A Hamiltonian formulation for free surface water waves with non-vanishing vorticity
- 2005
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Ingår i: Journal of Nonlinear Mathematical Physics. - : Springer Science and Business Media LLC. - 1402-9251 .- 1776-0852. ; 12:Suppl. 1, s. 202-211
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Tidskriftsartikel (refereegranskat)abstract
- We describe the derivation of a formalism in the context of the governing equations for two-dimensional water waves propagating over a flat bed in a flow with non-vanishing vorticity. This consists in providing a Hamiltonian structure in terms of two variables which are scalar functions.
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| 7. |
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| 8. |
- Constantin, Adrian, et al.
(författare)
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Exact periodic traveling water waves with vorticity
- 2002
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Ingår i: Comptes Rendus Mathématique. - 1631-073X. ; 335:10, s. 797-800
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Tidskriftsartikel (refereegranskat)abstract
- For the classical inviscid water wave problem under the influence of gravity, described by the Euler equation with a free surface over a flat bottom, we construct periodic traveling waves with vorticity. They are symmetric waves whose profiles are monotone between each crest and trough. We use global bifurcation theory to construct a connected set of such solutions. This set contains flat waves as well as waves that approach flows with stagnation points.
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| 9. |
- Constantin, Adrian, et al.
(författare)
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Exact steady periodic water waves with vorticity
- 2004
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Ingår i: Communications on Pure and Applied Mathematics. - : Wiley. - 0010-3640 .- 1097-0312. ; 57:4, s. 481-527
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Tidskriftsartikel (refereegranskat)abstract
- We consider the classical water wave problem described by the Euler equations with a free surface under the influence of gravity over a flat bottom. We construct two-dimensional inviscid periodic traveling waves with vorticity. They are symmetric waves whose profiles are monotone between each crest and trough. We use bifurcation and degree theory to construct a global connected set of such solutions. (C) 2004 Wiley Periodicals, Inc.
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| 10. |
- Constantin, Adrian
(författare)
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Finite propagation speed for the Camassa-Holm equation
- 2005
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Ingår i: Journal of Mathematical Physics. - : AIP Publishing. - 0022-2488 .- 1089-7658. ; 46:2
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Tidskriftsartikel (refereegranskat)abstract
- We prove that any classical solution of the Camassa-Holm equation will have compact support if its initial data has this property.
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| 11. |
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| 12. |
- Constantin, Adrian, et al.
(författare)
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Geodesic flow on the diffeomorphism group of the circle
- 2003
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Ingår i: Commentar II Mathematici Helvetici. - : Research Institute for Mathematical Sciences, Kyoto University. - 1420-8946 .- 0010-2571. ; 78:4, s. 787-804
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Tidskriftsartikel (refereegranskat)abstract
- We show that certain right-invariant metrics endow the infinite-dimensional Lie group of all smooth orientation-preserving diffeomorphisms of the circle with a Riemannian structure. The study of the Riemannian exponential map allows us to prove infinite-dimensional counterparts of results from classical Riemannian geometry: the Riemannian exponential map is a smooth local diffeomorphism and the length-minimizing property of the geodesics holds.
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| 13. |
- Constantin, Adrian, et al.
(författare)
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Global existence for fully parabolic boundary value problems
- 2006
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Ingår i: Nodea. Nonlinear Differential Equations and Applications. - : Springer Science and Business Media LLC. - 1021-9722 .- 1420-9004. ; 13:1, s. 91-118
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Tidskriftsartikel (refereegranskat)abstract
- We present some results on the global existence of classical solutions for quasilinear parabolic equations with nonlinear dynamic boundary conditions in bounded domains with a smooth boundary.
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| 14. |
- Constantin, Adrian
(författare)
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Global existence for parabolic systems by Lyapunov functions
- 2005
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Ingår i: Nodea. Nonlinear Differential Equations and Applications. - : Springer Science and Business Media LLC. - 1021-9722 .- 1420-9004. ; 12:3, s. 383-389
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Tidskriftsartikel (refereegranskat)abstract
- We present a result on the global existence of classical solutions for quasilinear parabolic systems with homogeneous Dirichlet boundary conditions in bounded domains with a smooth boundary. Our method relies on the use of Lyapunov functions.
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| 15. |
- Constantin, Adrian, et al.
(författare)
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Global solutions for quasilinear parabolic problems
- 2002
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Ingår i: Journal of Evolution Equations. - : Springer Science and Business Media LLC. - 1424-3199 .- 1424-3202. ; 2:1, s. 97-111
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Tidskriftsartikel (refereegranskat)abstract
- Results on the global existence of classical solutions for quasilinear parabolic equations in bounded domains with homogeneous Dirichlet or Neumann boundary conditions are presented. Besides quasilinear parabolic equations, the method is also applicable to some weakly-coupled reaction-diffusion systems and to elliptic equations with nonlinear dynamic boundary conditions.
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| 16. |
- Constantin, Adrian, et al.
(författare)
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Global solutions for quasilinear parabolic systems
- 2004
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Ingår i: Journal of Differential Equations. - 0022-0396. ; 197:1, s. 73-84
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Tidskriftsartikel (refereegranskat)abstract
- We present an approach for proving the global existence of classical solutions of certain quasilinear parabolic systems with homogeneous Dirichlet boundary conditions in bounded domains with a smooth boundary. (C) 2003 Elsevier Inc. All rights reserved.
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| 17. |
- Constantin, Adrian, et al.
(författare)
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H-k metrics on the diffeomorphism group of the circle
- 2003
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Ingår i: Journal of Nonlinear Mathematical Physics. - : Springer Science and Business Media LLC. - 1402-9251 .- 1776-0852. ; 10:4, s. 424-430
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Tidskriftsartikel (refereegranskat)abstract
- Each H-k inner product, kis an element ofN, endows the diffeomorphism group of the circle with a Riemannian structure. For kgreater than or equal to1 the Riemannian exponential map is a smooth local diffeomorphism and the length-minimizing property of geodesics holds.
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| 18. |
- Constantin, Adrian, et al.
(författare)
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Integrability of invariant metrics on the Virasoro group
- 2006
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Ingår i: Physics Letters A. - : Elsevier BV. - 0375-9601 .- 1873-2429. ; 350:1-2, s. 75-80
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Tidskriftsartikel (refereegranskat)abstract
- Each right-invariant metric on the Virasoro group induces a Hamiltonian vector field on the dual of the Lie algebra vir equipped with the canonical Lie-Poisson structure. We show that the Hamiltonian vector fields Xk induced by the metrics given at the identity by the Hk Sobolev inner products, k≥0, are bi-Hamiltonian relative to a modified Lie-Poisson structure only for k=0 and k=1.
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| 19. |
- Constantin, Adrian
(författare)
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Introduction: some recent developments of nonlinear water wave theory
- 2007
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Ingår i: Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Science. - : The Royal Society. - 1364-503X .- 1471-2962. ; 365:1858, s. 2195-2201
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The opening article of this issue is intended to provide a review of some relevant topics of the mathematical theory of water waves that have recently received considerable attention in the research literature. We also provide a brief discussion about the content and contribution of the articles that make up this issue.
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| 20. |
- Constantin, Adrian, et al.
(författare)
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On an integrable two-component Camassa-Holm shallow water system
- 2008
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Ingår i: Physics Letters. Section A: General, Atomic and Solid State Physics. - : Elsevier BV. - 0375-9601. ; 372:48, s. 7129-7132
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Tidskriftsartikel (refereegranskat)abstract
- The interest in the Camassa-Holm equation inspired the search for various generalizations of this equation With interesting properties and applications. In this Letter we deal with such a two-component integrable system Of Coupled equations. First we derive the system in the context of shallow water theory. Then we show that while small initial data develop into global Solutions, for some initial data wave breaking Occurs. We also discuss the Solitary Wave Solutions. Finally, we present all explicit construction for the peakon Solutions in the short wave limit of system. (C) 2008 Elsevier B.V. All rights reserved.
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| 21. |
- Constantin, Adrian, et al.
(författare)
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On geodesic exponential maps of the Virasoro group
- 2007
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Ingår i: Annals of Global Analysis and Geometry. - : Springer Science and Business Media LLC. - 1572-9060 .- 0232-704X. ; 31:2, s. 155-180
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Tidskriftsartikel (refereegranskat)abstract
- We study the geodesic exponential maps corresponding to Sobolev type right-invariant (weak) Riemannian metrics mu((k)) (k >= 0) on the Virasoro group Vir and show that for k >= 2, but not for k = 0, 1, each of them defines a smooth Frechet chart of the unital element e is an element of Vir. In particular, the geodesic exponential map corresponding to the Korteweg - de Vries (KdV) equation ( k = 0) is not a local diffeomorphism near the origin.
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| 22. |
- Constantin, Adrian
(författare)
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On the existence of positive solutions of second order differential equations
- 2005
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Ingår i: Annali di Matematica Pura ed Applicata. - : Springer Science and Business Media LLC. - 0373-3114 .- 1618-1891. ; 184:2, s. 131-138
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Tidskriftsartikel (refereegranskat)abstract
- Using the fixed point method we prove an existence result for positive solutions of nonlinear second order ordinary differential equations. An application to semilinear Schrodinger equations in exterior domains is also presented.
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| 23. |
- Constantin, Adrian, et al.
(författare)
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On the geometric approach to the motion of inertial mechanical systems
- 2002
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Ingår i: Journal of Physics A: Mathematical and General. - : IOP Publishing. - 0305-4470. ; 35:32, s. 51-79
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Forskningsöversikt (refereegranskat)abstract
- According to the principle of least action, the spatially periodic motions of one-dimensional mechanical systems with no external forces are described in the Lagrangian formalism by geodesics on a manifold-configuration space, the group D of smooth orientation-preserving diffeomorphisms of the circle. The periodic inviscid Burgers equation is the geodesic equation on D with the L-2 right-invariant metric. However, the exponential map for this right-invariant metric is not a C-1 local diffeomorphism and the geometric structure is therefore deficient. On the other hand, the geodesic equation on D for the H-1 right-invariant metric is also a re-expression of a model in mathematical physics. We show that in this case the exponential map is a C-1 local diffeomorphism and that if two diffeomorphisms are sufficiently close on D, they can be joined by a unique length-minimizing geodesic-a state of the system is transformed to another nearby state by going through a uniquely determined flow that minimizes the energy. We also analyse for both metrics the breakdown of the geodesic flow.
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| 24. |
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| 25. |
- Constantin, Adrian, et al.
(författare)
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On the inverse scattering approach to the Camassa-Holm equation
- 2003
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Ingår i: Journal of Nonlinear Mathematical Physics. - : Springer Science and Business Media LLC. - 1402-9251 .- 1776-0852. ; 10:3, s. 252-255
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Tidskriftsartikel (refereegranskat)abstract
- A simple algoritm for the inverse scattering approach to the Camassa-Holm equation is presented.
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