Thermal hadron production in high energy collisions

It is shown that hadron abundances in high energy e+e-, pp and p{\bar p} collisions, calculated by assuming that particles originate in hadron gas fireballs at thermal and partial chemical equilibrium, are in very good agreement with the data. The freeze-out temperature of the hadron gas fireballs turns out to be nearly constant over a large center of mass energy range and not dependent on the initial colliding system. The only deviation from chemical equilibrium resides in the incomplete strangeness phase space saturation. Preliminary results of an analysis of hadron abundances in S+S and S+Ag heavy ion collisions are presented.Comment: 10 pages, 1 .eps figure, talk given at the Strangeness and Quark Matter 97 conferenc

Neutrinos from supernovae: experimental status and perspectives

I discuss the state of the art in the search for neutrinos from galactic stellar collapses and the future perspectives of this field. The implications for the neutrino physics of a high statistics supernova neutrino burst detection by the network of detectors operating around the world are also reviewed.Comment: 19 pages, 12 figures. Extended version of talk given at IInd International Workshop on Matter, Anti-Matter and Dark Matter, Trento (Italy), 29-30 October 2001. A reduced version will appear in Int. J. of Mod. Phys.

Positioning systems in Minkowski space-time: Bifurcation problem and observational data

In the framework of relativistic positioning systems in Minkowski space-time, the determination of the inertial coordinates of a user involves the {\em bifurcation problem} (which is the indeterminate location of a pair of different events receiving the same emission coordinates). To solve it, in addition to the user emission coordinates and the emitter positions in inertial coordinates, it may happen that the user needs to know {\em independently} the orientation of its emission coordinates. Assuming that the user may observe the relative positions of the four emitters on its celestial sphere, an observational rule to determine this orientation is presented. The bifurcation problem is thus solved by applying this observational rule, and consequently, {\em all} of the parameters in the general expression of the coordinate transformation from emission coordinates to inertial ones may be computed from the data received by the user of the relativistic positioning system.Comment: 10 pages, 7 figures. The version published in PRD contains a misprint in the caption of Figure 3, which is here amende

El Crown Hall no es transparente. Mies van der Rohe y el recinto inexpugnable

La historiografía tradicional ha alabado el edificio para la escuela de Arquitectura del IIT, finalizado en 1956, como el más claro ejemplo de los paradigmáticos pabellones transparentes y sin pilares intermedios construidos por Mies van der Rohe, la ejecución racional de una urna de vidrio confiadamente abierta al exterior. Un análisis indagador y novedoso descubre las profundas claves proyectivas de un edificio que ahora se muestra marcadamente distinto

Cabrero y el mar. Edificio para la Escuela de Formación Profesional José Antonio Girón de Barcelona, 1968

El artículo rescata un edificio prácticamente desconocido hasta la fecha. Construido en tan sólo tres meses en 1968, constituye la única obra de Francisco Cabrero en Barcelona. A través de una profunda investigación realizada a partir de fuentes originales y en el propio edificio, el texto –desde la perspectiva del arquitecto– analiza el proyecto y lo ubica en la trayectoria de su autor. Aporta, además, abundante documentación inédita

Mineral oil paraffins in jute bags and cocoa butter

Jute bags and cocoa butter (CB) were analysed by gas chromatography (GC-FID/MS) to detect and quantify mineral oil saturated hydrocarbons (MOSH). Extraction clean-up on silica gel SPE (10 g/60 ml) was developed, as a unique sample preparation step for the determination of linear and branched n-alkanes in the range C14 to C31. The size of CB sample (500 mg) was sufficient for the detection of batching oil at levels of 2 mg kg−1, with satisfactory recovery and repeatability. MOSH from batching oil form a hump of unresolved components and the shape reflect balanced molecular-mass distribution between even and odd carbon atoms (from C14 to C22n-alkanes), expressed with the Carbon Preference Index (CPI=∑odd homologs/∑even homologs). Contaminated raw CB extracted from cocoa beans, transported and stored in jute bags during 2000 and 2001, showed MOSH (average 42 mg kg−1). However, only the 7.5% of the samples analysed of deodorized CB from 2007 to 2009 contained MOSH −1. High CPI values (>1.26) were attributed to natural hydrocarbons with a strong predominance of odd-numbered paraffins, situated between C22 and C31n-alkanes (average 31.7±5.37 mg kg−1). The results confirmed that MOSH components below n-C20 were fully eliminated by the deodorization process