Following Weyl on Quantum Mechanics: the contribution of Ettore Majorana

After a quick historical account of the introduction of the group-theoretical description of Quantum Mechanics in terms of symmetries, as proposed by Weyl, we examine some unpublished papers by Ettore Majorana. Remarkable results achieved by him in frontier research topics as well as in physics teaching point out that the Italian physicist can be well considered as a follower of Weyl in his reformulation of Quantum Mechanics.Comment: LaTeX, 15 pages, 1 ps figur

Ettore Majorana's course on Theoretical Physics: a recent discovery

We analyze in some detail the course of Theoretical Physics held by Ettore Majorana at the University of Naples in 1938, just before his mysterious disappearance. In particular we present the recently discovered "Moreno Paper", where all the lecture notes are reported. Six of these lectures are not present in the collection of the original manuscripts conserved at the Domus Galilaeana in Pisa, consisting of only ten lectures.Comment: AMS-latex, 16 pages, 2 figure

Color Superconductivity in Compact Stars and Gamma Ray Bursts

We study the effects of color superconductivity on the structure and formation of compact stars. We show that it is possible to satisfy most of recent observational boundaries on masses and radii if a diquark condensate forms in a hybrid or a quark star. Moreover, we find that a huge amount of energy, of the order of $10^{53}$ erg, can be released in the conversion from a (metastable) hadronic star into a (stable) hybrid or quark star, if the presence of a color superconducting phase is taken into account. Accordingly to the scenario proposed in Astrophys.J.586(2003)1250, the energy released in this conversion can power a Gamma Ray Burst. This mechanism can explain the recent observations indicating a delay, of the order of days or years, between a few Supernova explosions and the subsequent Gamma Ray Burst.Comment: 15 pages, 4 figures, 1 tabl

Formation of Quark Phases in compact stars and their connection to Gamma-Ray-Bursts

We analyse the occurrence of quiescent times in the temporal structure of the Gamma-Ray-Bursts (GRBs) light curves. We show that if a long quiescent time is present, it is possible to divide the total duration of GRBs into three periods: the pre-quiescence emission, the quiescent time and the post-quiescence emission. We then discuss a model of the GRBs inner engine based on the formation of quark phases during the life of an hadronic star. Within this model the pre-quiescence emission is interpreted as due to the deconfinement of quark inside an hadronic star and the formation of 2SC quark matter. The post-quiescence emission is due to the conversion of 2SC into the Color-Flavor-Locking (CFL) phase. The temporal delay between these two processes is connected with the nucleation time of the CFL phase in the 2SC phase and it can be associated with the observed quiescent times in the GRBs light curves. The stability of CFL cores in compact stars is also discussed.Comment: 6 pages, 3 figures, to appear in the proceedings of 3th International Conference on Nuclear Physics in Astrophysics (NPAIII), 26 - 31 March 2007 Dresden, German

Reflecting on reflection: scale extension and a comparison of undergraduate business students in the United States and the United Kingdom

In the Peltier, Hay, and Drago (2005) article entitled “The Reflective Learning Continuum: Reflecting on Reflection,” a reflective learning continuum was conceptualized and tested. This is a follow-up article based on three extensions: (1) determine whether the continuum could be expanded, (2) further validating the continuum using additional schools, and (3) determining whether the continuum could also be applied to undergraduate business education. The findings from a study of U.S. and UK students show that the revised scale is valid and reliable and that U.S. students in the sample universities rated their educational experience higher and were more likely to use reflective thinking practices

Non-Standard Time Reversal for Particle Multiplets and the Spin-Flavor Structure of Hadrons

We show that a system of quarks interacting with chiral fields provides a physical representation of a ``non-standard'' time reversal for particle multiplets proposed by Weinberg. As an application, we argue that, if the internal structure of hadrons is described by a chiral lagrangian, the so-called time-reversal-odd quark distribution functions might not be forbidden by time-reversal invariance.Comment: 2 pages, proceedings of "The Spin Structure of the Proton", ECT - Trento, July 2001. Eds. S Bass, A De Roeck and A Deshpand