Note on scalars, perfect fluids, constrained field theories, and all that

The relation of a scalar field with a perfect fluid has generated some debate along the last few years. In this paper we argue that shift-invariant scalar fields can describe accurately the potential flow of an isentropic perfect fluid, but, in general, the identification is possible only for a finite period of time. After that period in the evolution the dynamics of the scalar field and the perfect fluid branch off. The Lagrangian density for the velocity-potential can be read directly from the expression relating the pressure with the Taub charge and the entropy per particle in the fluid, whereas the other quantities of interest can be obtained from the thermodynamic relations.Comment: 5 pages, 1 figure. Accepted for publication in Phys. Lett.

The Earlier Wittgenstein on the Notion of Religious Attitude

I defend a new interpretation of Wittgenstein's notion of religious (or ethical) attitude in the Tractatus, one that rejects three key views from the secondary literature: firstly, the view that, for Wittgenstein, the willing subject is a transcendental condition for the religious attitude; secondly, the view that the religious attitude is an emotive response to the world or something closely modelled on this notion of emotive response; and thirdly, the view that, although the religious and ethical pseudo-propositions of the Tractatus are nonsensical, they nevertheless succeed in expressing the religious attitude endorsed by Wittgenstein. In connection to the first, I argue that the notion of willing subject as transcendental condition is abandoned by Wittgenstein in the Notebooks and is no longer a feature of his position in the Tractatus. In connection to the second, I argue that the religious attitude is dispositional rather than emotive for Wittgenstein: it is a disposition to use signs in a way that demonstrates one's conceptual clarity. Finally, in connection to the third, I argue that the religious or ethical attitude is strongly ineffable in that it cannot be described, expressed or conveyed by language at all.Peer reviewe

Las nuevas tecnologías de la información y la comunicación y la investigación educativa

En esta artículo me gustaría exponer de modo conciso algunas ideas que nos ayuden a reflexionar sobre cómo el desarrollo tecnológico y las nuevas formas de comunicación están configurando un nuevo escenario para la investigación y, en concreto, para la investigación educativa.In this article I would like to present some ideas concisely in order to help us to think about how technological development and new forms of communication are shaping a new stage for research and, in particular, for education research

The electro production of d* dibaryon

$d^*$ dibaryon study is a critical test of hadron interaction models. The electro production cross sections of $ed\to ed^*$ have been calculated based on the meson exchange current model and the cross section around 30 degree of 1 GeV electron in the laboratory frame is about 10 nb. The implication of this result for the $d^*$ dibaryon search has been discussed.Comment: 12 pages, 12 figures, Late