Conformance relations for distributed testing based on CSP

Copyright @ 2011 Springer Berlin HeidelbergCSP is a well established process algebra that provides comprehensive theoretical and practical support for refinement-based design and verification of systems. Recently, a testing theory for CSP has also been presented. In this paper, we explore the problem of testing from a CSP specification when observations are made by a set of distributed testers. We build on previous work on input-output transition systems, but the use of CSP leads to significant differences, since some of its conformance (refinement) relations consider failures as well as traces. In addition, we allow events to be observed by more than one tester. We show how the CSP notions of refinement can be adapted to distributed testing. We consider two contexts: when the testers are entirely independent and when they can cooperate. Finally, we give some preliminary results on test-case generation and the use of coordination messages. © 2011 IFIP International Federation for Information Processing

Bell inequalities for continuous-variable correlations

We derive a new class of correlation Bell-type inequalities. The inequalities are valid for any number of outcomes of two observables per each of n parties, including continuous and unbounded observables. We show that there are no first-moment correlation Bell inequalities for that scenario, but such inequalities can be found if one considers at least second moments. The derivation stems from a simple variance inequality by setting local commutators to zero. We show that above a constant detector efficiency threshold, the continuous variable Bell violation can survive even in the macroscopic limit of large n. This method can be used to derive other well-known Bell inequalities, shedding new light on the importance of non-commutativity for violations of local realism.Comment: 4 pages, 1 figure. v2: New results on detector efficiencies and macroscopic limit, new co-author, changed title and abstract, changed figure, added journal reference and DO

Indexação de plantas básicas de citros da Embrapa Mandioca e Fruticultura para a presença de viróides.

Os citros são hospedeiros naturais de espécies de viróides: viróide da exocorte dos citros (Citrus exocortis viroid, CEVd), viróide do nanismo do lúpulo (Hop stunt viroid, HSVd), Citrus bark cracking viroid (CBCVd), viróide da folha curvada dos citros (Citrus bent leaf viroid, CBLVd), viróide do nanismo dos citros (Citrus dwarfing viroid, CDVd) e, mais recentemente, também foi descrita a ocorrência do Citrus Viroid V (CVd-V) e Citrus viroid VI (CVd-VI). Somente o CEVd e variantes do HSVd são agentes causais de doenças, exocorte e xiloporose, respectivamente. No Brasil já foram identificados as espécies CEVd, HSVd e o CDVd

Geometrically induced singular behavior of entanglement

We show that the geometry of the set of quantum states plays a crucial role in the behavior of entanglement in different physical systems. More specifically it is shown that singular points at the border of the set of unentangled states appear as singularities in the dynamics of entanglement of smoothly varying quantum states. We illustrate this result by implementing a photonic parametric down conversion experiment. Moreover, this effect is connected to recently discovered singularities in condensed matter models.Comment: v2: 4 pags, 4 figs. A discussion before the proof of Proposition 1 and tomographic results were included, Propostion 2 was removed and the references were fixe

Microbiological and colour changes in umbu (Spondias tuberosa Arr. Cam.) in the mature green stage, during storage under accelerated conditions.

The objective ofthis study was to study the microbiological and colour changes in pasteurized umbu pulp during 120 days of storage at 40°C.Resumo 657

Casimir effect for the scalar field under Robin boundary conditions: A functional integral approach

In this work we show how to define the action of a scalar field in a such a way that Robin boundary condition is implemented dynamically, i.e., as a consequence of the stationary action principle. We discuss the quantization of that system via functional integration. Using this formalism, we derive an expression for the Casimir energy of a massless scalar field under Robin boundary conditions on a pair of parallel plates, characterized by constants $c_1$ and $c_2$. Some special cases are discussed; in particular, we show that for some values of $c_1$ and $c_2$ the Casimir energy as a function of the distance between the plates presents a minimum. We also discuss the renormalization at one-loop order of the two-point Green function in the $\lambda\phi^4$ theory submitted to Robin boundary condition on a plate.Comment: 16 pages, 2 figures. Version 2: contains a new section on the renormalization of the two-point Green function in the presence of a flat boundary. Accepted for publication in J. Phys.

Electron localization by a magnetic vortex

We study the problem of an electron in two dimensions in the presence of a magnetic vortex with a step-like profile. Dependending on the values of the effective mass and gyromagnetic factor of the electron, it may be trapped by the vortex. The bound state spectrum is obtained numerically, and some limiting cases are treated analytically.Comment: 8 pages, latex, 4 figure