Adapting Quality Assurance to Adaptive Systems: The Scenario Coevolution Paradigm

From formal and practical analysis, we identify new challenges that self-adaptive systems pose to the process of quality assurance. When tackling these, the effort spent on various tasks in the process of software engineering is naturally re-distributed. We claim that all steps related to testing need to become self-adaptive to match the capabilities of the self-adaptive system-under-test. Otherwise, the adaptive system's behavior might elude traditional variants of quality assurance. We thus propose the paradigm of scenario coevolution, which describes a pool of test cases and other constraints on system behavior that evolves in parallel to the (in part autonomous) development of behavior in the system-under-test. Scenario coevolution offers a simple structure for the organization of adaptive testing that allows for both human-controlled and autonomous intervention, supporting software engineering for adaptive systems on a procedural as well as technical level.Comment: 17 pages, published at ISOLA 201

Influência da quebra de dormência na germinação in vitro de sementes de paricá.

O Schizolobium amazonicum Huber, vulgarmente conhecido como paricá, pertencente à Família Leguminosae, é uma das espécies amazônicas que despertam o interesse de produtores rurais e madeireiros devido à viabilidade econômica e boa qualidade de sua madeira, com grande potencial para a recuperação de áreas degradadas, reflorestamento e inserção em sistemas agroflorestais. Considerando a cultura de tecidos uma alternativa para propagação clonal rápida de plantas de qualidade, livres de patógenos e em menor espaço e tempo, o objetivo deste trabalho foi avaliar diferentes métodos de quebra de dormência para germinação in vitro e formação de plântulas doadoras de explantes visando o desenvolvimento de protocolo de micropropagação do paricá para dar suporte ao programa de clonagem de plantas selecionados dentro do programa de melhoramento genético. As sementes foram submetidas a quatro tratamentos de quebra de dormência e semeadas in vitro em meio básico de cultura MS completo. As avaliações ocorreram ao longo do cultivo quanto à emissão da radícula até a formação da plântula. As sementes oriundas da escarificação química com ácido sulfúrico por 60 minutos, responderam com índices mais altos de germinação e desenvolvimento da plântula em relação aos demais tratamentos após 20 dias de cultivo in vitro. Portanto, para a quebra de dormência e germinação in vitro de sementes de paricá recomenda-se a escarificação com ácido sulfúrico por 60 minutos e semeio em meio de cultura MS completo

Holographic superfluids as duals of rotating black strings

We study the breaking of an Abelian symmetry close to the horizon of an uncharged rotating Anti-de Sitter black string in 3+1 dimensions. The boundary theory living on R^2 x S^1 has no rotation, but a magnetic field that is aligned with the axis of the black string. This boundary theory decribes non-rotating (2+1)-dimensional holographic superfluids with non-vanishing superfluid velocity. We study these superfluids in the grand canonical ensemble and show that for sufficiently small angular momentum of the dual black string and sufficiently small superfluid velocity the phase transition is 2nd order, while it becomes 1st order for larger superfluid velocity. Moreover, we observe that the phase transition is always 1st order above a critical value of the angular momentum independent of the choice of the superfluid velocity.Comment: 9 pages including 5 figures: v2: 12 pages including 7 figures; 2 figures added, discussion on free energy added; accepted for publication in JHE

The Asymptotic Dynamics of two-dimensional (anti-)de Sitter Gravity

We show that the asymptotic dynamics of two-dimensional de Sitter or anti-de Sitter Jackiw-Teitelboim (JT) gravity is described by a generalized two-particle Calogero-Sutherland model. This correspondence is established by formulating the JT model of (A)dS gravity in two dimensions as a topological gauge theory, which reduces to a nonlinear 0+1-dimensional sigma model on the boundary of (A)dS space. The appearance of cyclic coordinates allows then a further reduction to the Calogero-Sutherland quantum mechanical model.Comment: 16 pages, LaTeX, no figures, uses JHEP.cls. v2: Some references and comments added. v3: Minor errors correcte

Higher dimensional radiation collapse and cosmic censorship

We study the occurrence of naked singularities in the spherically symmetric collapse of radiation shells in a higher dimensional spacetime. The necessary conditions for the formation of a naked singularity or a black hole are obtained. The naked singularities are found to be strong in the Tipler's sense and thus violating cosmic censorship conjecture.Comment: 4 pages, ReVTeX, Phys Rev D Vol 62 107502 (2000

Magnetic strings in anti-de Sitter General Relativity

We obtain spacetimes generated by static and spinning magnetic string sources in Einstein Relativity with negative cosmological constant. Since the spacetime is asymptotically a cylindrical anti-de Sitter spacetime, we will be able to calculate the mass, momentum, and electric charge of the solutions. We find two families of solutions, one with longitudinal magnetic field and the other with angular magnetic field. The source for the longitudinal magnetic field can be interpreted as composed by a system of two symmetric and superposed electrically charged lines with one of the electrically charged lines being at rest and the other spinning. The angular magnetic field solution can be similarly interpreted as composed by charged lines but now one is at rest and the other has a velocity along the axis. This solution cannot be extended down to the origin.Comment: Latex, 26 page