1,355,995 research outputs found
Maspero Triangle Masterplan
No full text1 – We propose an exchange of properties that will allow private investors to develop the Nile waterfront – with the exception of a New Museum – and will at the same time allow the public sector to secure property of the popular neighbourhood in order to upgrade this area using the revenues of the sales of the land along the waterfront and the taxation on real estate profits. This exchange allows not to displace the inhabitants of the popular neighbourhood.
2 – Inside the popular neighbourhood – that after the property exchange will be entirely owned by the public sector – we propose a series of small interventions (restorations, completions). These interventions will not compromise the identity of the area, on the contrary they will bring new life to the neighbourhood by introducing new productive activities such as workshops for craftsmen and services. New construction technologies will be experimented in the upgrading of the area.
3 – In the spaces between the popular neighbourhood and the waterfront we propose to develop a series of new residential settlements, where the Cairene middle class – that in the last years abandoned Downtown Cairo – could come back to a new, intense, metropolitan life, directly linked with the attractions of the centre and of the new waterfront.
4 – We propose a new waterfont made of residential towers that ends with a new hotel at the northern end of Maspero Triangle. At the centre of the waterfront there will be a New Museum. The New Museum (that could be developed in close partnership with similar international institutions) will combine a new public square open onto the Nile, an elevated platform for laboratories, ateliers and artistic production and a system of exhibition spaces grouped in a circular volume.
5 – We imagine a system of new green islands along the river that will contain public spaces open to the city and a new, elevated Botanical Garden covering the colossal road interchange which separates Maspero Triangle form the Egyptian Museum
Tame majorant analyticity for the Birkhoff map of the defocusing nonlinear Schrödinger equation on the circle
No full textFor the defocusing nonlinear Schrö dinger equation on the circle, we construct a Birkhoff map Φ which is tame majorant analytic in a neighborhood of the origin. Roughly speaking, majorant analytic means that replacing the coefficients of the Taylor expansion of Φ by their absolute values gives rise to a series (the majorant map) which is uniformly and absolutely convergent, at least in a small neighborhood. Tame majorant analytic means that the majorant map of Φ fulfills tame estimates. The proof is based on a new tame version of the Kuksin-Perelman theorem (2010 Discrete Contin. Dyn. Syst. 1 1-24), which is an infinite dimensional Vey type theorem
Generic Transporters for the Linear Time-Dependent Quantum Harmonic Oscillator on R
No full textIn this paper we consider the linear, time-dependent quantum Harmonic Schrdinger equation i partial derivative(t)u = 1/2(-partial derivative(x)(2) + x(2 ))u + V(t,x,d)u,x epsilon R, where v(t,x,D) is classical pseudodifferential operator of order 0, self-adjoint, and 2 pi periodic in time. We give sufficient conditions on the principal symbol of V(t,x,D) ensuring the existence of solutions displaying infinite time growth of Sobolev norms. These conditions are generic in the Frechet space of symbols. This shows that generic, classical pseudodifferential, 2 pi-periodic perturbations provoke unstable dynamics. The proof builds on the results of [36] and it is based on pseudodifferential normal form and local energy decay estimates. These last are proved exploiting Mourre's positive commutator theory
Long time stability of small finite gap solutions of the cubic nonlinear Schrödinger equation on T2
No full textIn this paper we study long time stability of a class of nontrivial, quasi-periodic solutions depending on one spacial variable of the cubic defocusing non-linear Schrödinger equation on the two dimensional torus. We prove that these quasi-periodic solutions are orbitally stable for finite but long times, provided that their Fourier support and their frequency vector satisfy some complicated but explicit condition, which we show holds true for most solutions. The proof is based on a normal form result. More precisely we expand the Hamiltonian in a neighborhood of a quasi-periodic solution, we reduce its quadratic part to diagonal constant coefficients through a KAM scheme, and finally we remove its cubic terms with a step of nonlinear Birkhoff normal form. The main difficulty is to impose second and third order Melnikov conditions; this is done by combining the techniques of reduction in order of pseudo-differential operators with the algebraic analysis of resonant quadratic Hamiltonians
Growth of Sobolev norms in linear Schrödinger equations as a dispersive phenomenon
No full textIn this paper we consider linear, time dependent Schrödinger equations of the form i∂tψ=K0ψ+V(t)ψ, where K0 is a strictly positive selfadjoint operator with discrete spectrum and constant spectral gaps, and V(t) a smooth in time periodic potential. We give sufficient conditions on V(t) ensuring that K0+V(t) generates unbounded orbits. The main condition is that the resonant average of V(t), namely the average with respect to the flow of K0, has a nonempty absolutely continuous spectrum and fulfills a Mourre estimate. These conditions are stable under perturbations. The proof combines pseudodifferential normal form with dispersive estimates in the form of local energy decay. We apply our abstract construction to the Harmonic oscillator on R and to the half-wave equation on T; in each case, we provide large classes of potentials which are transporters
Freezing of Energy of a Soliton in an External Potential
No full textIn this paper we study the dynamics of a soliton in the generalized NLS with a small external potential ϵV of Schwartz class. We prove that there exists an effective mechanical system describing the dynamics of the soliton and that, for any positive integer r, the energy of such a mechanical system is almost conserved up to times of order ϵ−r. In the rotational invariant case we deduce that the true orbit of the soliton remains close to the mechanical one up to times of order ϵ−r
Homme libre – Homme livre: François Maspero
No full textThe blog post "Homme libre – Homme livre: François Maspero" explores the life and works of François Maspero, a notable French editor and writer. The author discusses the serendipitous timing of receiving a book about Maspero and learning of his death. The book, "François Maspero et les paysages humains," is described as a detailed tribute, covering Maspero\u27s literary contributions and personal experiences, including his time in Algeria. The post emphasizes the book\u27s value as a collection of testimonies and documents, providing insights into Maspero\u27s life, his publishing endeavors, and his influence on French intellectual and political scenes. The author also mentions Maspero\u27s role as a geographer, highlighting how his writings offer a unique perspective on human landscapes. Additionally, the post notes the limited recognition of Maspero in Germany and underscores the significance of his work in amplifying the voices of dissident movements in Eastern Europe during the 1970s.
Le billet de blog "Homme libre – Homme livre : François Maspero" explore la vie et les œuvres de François Maspero, un éditeur et écrivain français renommé. L\u27auteur évoque la coïncidence troublante entre la réception d\u27un livre sur Maspero et l\u27annonce de son décès. Le livre, "François Maspero et les paysages humains," est décrit comme un hommage exhaustif, détaillant les contributions littéraires de Maspero et ses expériences personnelles, y compris son séjour en Algérie. Le billet met en avant la valeur de cet ouvrage en tant que recueil de témoignages et de documents, offrant un aperçu de la vie de Maspero, de sa maison d\u27édition et de son influence sur les paysages intellectuels et politiques français. L\u27auteur souligne également le rôle de Maspero en tant que géographe, montrant comment ses écrits offrent une perspective unique sur les paysages humains. En outre, le billet note la reconnaissance limitée de Maspero en Allemagne et insiste sur l\u27importance de son travail dans l\u27amplification des voix des mouvements dissidents en Europe de l\u27Est durant les années 1970
Reducibility for a fast-driven linear Klein–Gordon equation
No full textWe prove a reducibility result for a linear Klein–Gordon equation with a quasi-periodic driving on a compact interval with Dirichlet boundary conditions. No assumptions are made on the size of the driving; however, we require it to be fast oscillating. In particular, provided that the external frequency is sufficiently large and chosen from a Cantor set of large measure, the original equation is conjugated to a time-independent, diagonal one. We achieve this result in two steps. First, we perform a preliminary transformation, adapted to fast oscillating systems, which moves the original equation in a perturbative setting. Then, we show that this new equation can be put to constant coefficients by applying a KAM reducibility scheme, whose convergence requires a new type of Melnikov conditions
Birkhoff coordinates for the Toda lattice in the limit of infinitely many particles with an application to FPU
No full textIn this paper we study the Birkhoff coordinates (Cartesian action angle coordinates) of the Toda lattice with periodic boundary condition in the limit where the number N of the particles tends to infinity. We prove that the transformation introducing such coordinates maps analytically a complex ball of radius R/Nα (in discrete Sobolev-analytic norms) into a ball of radius R′/Nα (with R,R′>0 independent of N) if and only if α≥2. Then we consider the problem of equipartition of energy in the spirit of Fermi-Pasta-Ulam. We deduce that corresponding to initial data of size R/N2, 0<R≪1, and with only the first Fourier mode excited, the energy remains forever in a packet of Fourier modes exponentially decreasing with the wave number. Finally we consider the original FPU model and prove that energy remains localized in a similar packet of Fourier modes for times one order of magnitude longer than those covered by previous results which is the time of formation of the packet. The proof of the theorem on Birkhoff coordinates is based on a new quantitative version of a Vey type theorem by Kuksin and Perelman which could be interesting in itself
Ora Maspero
No full textPoster. Ora Maspero (cigarettes). LL in image: lekem. LL border: lit. A. Kaufman T-A. Sun, two cigarettes and box of 20. THE MILDER CIGARETTE MASPERO (PALESTINE) LTD TEL AVIV.Digital imagedigitize
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