Collective rearrangement at the onset of flow of a polycrystalline hexagonal columnar phase

Creep experiments on polycrystalline surfactant hexagonal columnar phases show a power law regime, followed by a drastic fluidization before reaching a final stationary flow. The scaling of the fluidization time with the shear modulus of the sample and stress applied suggests that the onset of flow involves a bulk reorganization of the material. This is confirmed by X-ray scattering under stress coupled to \textit{in situ} rheology experiments, which show a collective reorientation of all crystallites at the onset of flow. The analogy with the fracture of heterogeneous materials is discussed.Comment: to appear in Phys. Rev. Let

Environmental problems and opportunities of the peri-urban interface and their impact upon the poor

The objective of this document is to provide an overview of the problems and opportunities of the peri-urban interface (PUI) with regard to the broad concerns of environmentalsustainability and poverty

Constrained Minimization Under Vector-Valued Criteria in Linear Topological Spaces

Constrained minimization under vector valued criteria in linear topological space

Sacrifice and Efficiency of the Income Tax Schedule

We investigate the efficiency of equal sacrifice tax schedules in an economywhich primitives are exactly those in Mirrlees (1971): a continuum of individualswith identical preferences defined over consumption and leisure who differ withrespect to their labor market productivity. Using a separable specification forpreferences we derive the minimum equal sacrifice allocation and recover thetax schedule that implements it. The separable specification allows us to usethe methodology developed by Werning (2007b) to check whether the scheduleis efficient, that is, whether there is no alternative tax schedule that raises morerevenue while delivering less utility to no one. We find that inefficiency does notarise for most parametrizations we use to approximate the US economy. For thefew cases for which inefficiency does arise, it does so only for very high levels ofincome and marginal tax rates.

Topological first-order solitons in a gauged CP(2)CP(2) model with the Maxwell-Chern-Simons action

We verify the existence of radially symmetric first-order solitons in a gauged $CP(2)$ scenario in which the dynamics of the Abelian gauge field is controlled by the Maxwell-Chern-Simons action. We implement the standard Bogomol'nyi-Prasad-Sommerfield (BPS) formalism, from which we obtain a well-defined lower bound for the corresponding energy (i.e. the Bogomol'nyi bound) and the first-order equations saturating it. We solve these first-order equations numerically by means of the finite-difference scheme, therefore obtaining regular solutions of the effective model, their energy being quantized according the winding number rotulating the final configurations, as expected. We depict the numerical solutions, whilst commenting on the main properties they engender.Comment: 8 pages, 9 figure

Generalised verification of the observer property in discrete event systems

The observer property is an important condition to be satisfied by abstractions of Discrete Event Systems (DES) models. This paper presents a generalised version of a previous algorithm which tests if an abstraction of a DES obtained through natural projection has the observer property. The procedure called OP-verifier II overcomes the limitations of the previously proposed verifier while keeping its computational complexity. Results are illustrated by a case study of a transfer line system

Generalised verification of the observer property in discrete event systems

The observer property is an important condition to be satisfied by abstractions of Discrete Event Systems (DES) models. This paper presents a generalised version of a previous algorithm which tests if an abstraction of a DES obtained through natural projection has the observer property. The procedure called OP-verifier II overcomes the limitations of the previously proposed verifier while keeping its computational complexity. Results are illustrated by a case study of a transfer line system

Flight trajectories around planets with return to earth

Close flyby trajectory calculations around planets with return to earth capabilit