The Crystallography of Color Superconductivity

We develop the Ginzburg-Landau approach to comparing different possible crystal structures for the crystalline color superconducting phase of QCD, the QCD incarnation of the Larkin-Ovchinnikov-Fulde-Ferrell phase. In this phase, quarks of different flavor with differing Fermi momenta form Cooper pairs with nonzero total momentum, yielding a condensate that varies in space like a sum of plane waves. We work at zero temperature, as is relevant for compact star physics. The Ginzburg-Landau approach predicts a strong first-order phase transition (as a function of the chemical potential difference between quarks) and for this reason is not under quantitative control. Nevertheless, by organizing the comparison between different possible arrangements of plane waves (i.e. different crystal structures) it provides considerable qualitative insight into what makes a crystal structure favorable. Together, the qualitative insights and the quantitative, but not controlled, calculations make a compelling case that the favored pairing pattern yields a condensate which is a sum of eight plane waves forming a face-centered cubic structure. They also predict that the phase is quite robust, with gaps comparable in magnitude to the BCS gap that would form if the Fermi momenta were degenerate. These predictions may be tested in ultracold gases made of fermionic atoms. In a QCD context, our results lay the foundation for a calculation of vortex pinning in a crystalline color superconductor, and thus for the analysis of pulsar glitches that may originate within the core of a compact star.Comment: 41 pages, 13 figures, 1 tabl

Reasoning About Alternative Requirements Options

This paper elaborates on some of the fundamental contributions made by John Mylopoulos in the area of Requirements Engineering. We specifically focus on the use of goal models and their soft goals for reasoning about alternative options arising in the requirements engineering process. A personal account of John’s qualitative reasoning technique for comparing alternatives is provided first. A quantitative but lightweight technique for evaluating alternative options is then presented. This technique builds on mechanisms introduced by the qualitative scheme while overcoming some problems raised by it. A meeting scheduling system is used as a running example to illustrate the main ideas

Alguns grupos de microrganismos em manteigas vendidas no município de São Paulo Microorganism groups found in butter sold in the City of S. Paulo, Brazil

Foram colhidas 105 amostras de manteiga de 5 marcas diferentes vendidas em supermercados da cidade de São Paulo (Brasil) com a finalidade de verificar as condições microbiológicas de manteigas e compará-las com os padrões recomendados. Semanalmente foi colhida uma amostra de cada marca, durante 21 semanas. A partir da parte aquosa de cada amostra, foram realizadas as contagens de bactérias mesófilas e psicrófilas (em ágar padrão e ágar gelisato), coliformes, proteolíticas e de bolores e leveduras e os resultados comparados com alguns parâmetros propostos por vários pesquisadores. Os valores obtidos nas contagens dos vários grupos de microrganismos estudados, em muitos casos podem ser considerados altos, os quais podem ser resultado do processamento e/ou conservação, realizados em condições não satisfatórias.<br>One hundred and five samples of five different brands of butter in the supermarkets of the City of S. Paulo, Brazil were brought in for testing every week for 21 weeks. From the aqueous phase, counts were made for mesophilic and psichrophilic (using the standard plate count, agar and gelysate agar), coliform, proteolytic, and lipolytic bacteria, as well as for yeasts and molds. Results were compared with parameters proposed by several researchers. In many cases, the count values can be considered high, but these high counts may be due to inadequate processing and/or inadequate storage

Shame, scientist! Degradation rituals in science

Reputations are crucially important to scientists, so it is valuable to examine processes by which reputations come under attack. One potent method is a degradation ritual, an event or process that stigmatises the target and often results in feelings of shame and humiliation. Anthropologists and other scholars from a range of disciplines have examined degradation rituals and ceremonies, but their use in science has received little attention, perhaps because of the focus on the rational features of the issues involved. Degradation rituals can be described in terms of various features, including degrading agents, contexts, means and severity. Attacks on scientists in a variety of fields can be usefully interpreted through the lens of degradation rituals.