Context. The identification of the sources that reionized the Universe and their specific contribution to this process are key missing pieces of our knowledge of the early Universe. Faint star-forming galaxies may be the main contributors to the ionizing photon budget during the epoch of reionization, but their escaping photons cannot be detected directly due to inter-galactic medium opacity. Hence, it is essential to characterize the properties of faint galaxies with significant Lyman continuum photon leakage up to z 4 to (...) define indirect indicators allowing analogues to be found at the highest redshift. Aims. Long gamma-ray bursts explode typically in star-forming regions of faint, star-forming galaxies. Through LGRB afterglow spectroscopy it is possible to detect directly LyC photons. Our aim is to use LGRBs as tools to study LyC leakage from faint, star-forming galaxies at high redshift. Methods. Here we present the observations of LyC emission in the afterglow spectra of GRB 191004B at z = 3:5055, together with those of the other two previously known LyC-emitting LGRB, to determine their LyC escape fraction and compare their properties. Results. From the afterglow spectrum of GRB 191004B we determine a neutral hydrogen column density at the LGRB redshift of og =17:2 0:15, and negligible extinction. The only metal absorption lines detected are C iv and Si iv. In contrast to GRB 050908 and GRB 060607A, the host galaxy of GRB 191004B displays significant Ly emission. From its Ly emission and the non-detection of Balmer emission lines we constrain its star-formation rate to 1 SFR 4:7 M yr. 1. We fit the Ly emission with a shell model and find parameters values consistent with the observed ones. The absolute LyC escape fractions we find for GRB 191004B, GRB 050908 and GRB 060607A are of 0:35+0:10.0:11, 0:08+0:05.0:04 and :20+0:05.0:05, respectively. We compare the LyC escape fraction of LGRBs to the values of other LyC emitters found from the literature, showing that LGRB afterglows can be powerful tools to study LyC escape for faint high-redshift star-forming galaxies. Indeed we could push LyC leakage studies to much higher absolute magnitudes. The host galaxies of the three LGRB presented here have all M1600 >.19:5 mag, with the GRB 060607A host at M1600 >.16 mag. LGRB hosts may therefore be particularly suitable for exploring the ionizing escape fraction in galaxies that are too faint or distant for conventional techniques. Furthermore the time investment is very small compared to galaxy studies. (shrink)

We present six significant open problems in Pure Inductive Logic, together with their background and current status, with the intention of raising awareness and leading ultimately to their resolution.

Plato's "Politicus" (Statesman) stands, both in date and in political thought, between the "Republic" and the "Laws". It presents his thought at the point when he was chastened by disappointment with his attempts to put theory into practice at Syracuse. The dialogue reflects contemporary controversies on the method of definition; but its logical exercises and the impressive 'myth' of the two cosmic eras serve to bring out its essential political teaching. This volume contains the text in translation. In this second (...) edition, Skemp made corrections to his extensive introduction and running commentary, and added a new appendix taking into account scholarship since the first (1952) edition. (shrink)

This is the fourth volume of the Clarendon edition of Robert Burton's Anatomy of Melancholy and the first of three volumes of Commentary. It contains commentary on the text up to p. 327 of volume one - i.e. The Argument of the Frontispeice, Democritus to the Reader, and Partition 1 as far as the end of Section 2, Member 3, Subsection 15: 'Misery of Schollers'. In his study of morbid psychology as it was understood in his day, Burton cites many (...) other writers. No previous edition of the Anatomy has identified all of these or verified all his quotations. In addition to explanatory notes and translations of all the passages in Latin, this edition attempts to locate all Burton's sources in the actual books he himself owned or to which he probably had access. The last of the three volumes of commentary will contain a Biobibliography listing over 1,500 authorities referred to by Burton, many very obscure, and will give not only bibliographical details but information about the writers. (shrink)

Prior thinks that Edwards' argument depends on a metaphysical turn of phrase. Edwards, he says, subsumes "all happenings, or anyhow... all changes, under the idea of the 'beginning to be' either of concrete objects or of abstract ones". We are not to say, "My head began to ache," we are to say, "My headache began to exist." The shift may seem trivial, but actually it is "of the very first importance": Edwards' argument "depends on it." The reason is the following. (...) Edwards says that objects or substances cannot begin to be without a cause; that if they could, it would be prima facie implausible to hold that substances of only one kind, of all the millions of kinds of substance, should causelessly come to be; and that the implausibility cannot be removed by appealing to the nature of what thus comes to be, because until it actually exists there is nothing there to explain anything. Prior agrees with all that. But he holds that it is not impossible that some already existing substances should have a special kind of property which would make it possible for them to change or act causelessly. Of course, if we have to say that a change or an act is just another kind of coming to be of a substance, this too is impossible. Hence Prior thinks that by showing that changes and acts need not be construed as Edwards construes them, he will have made room for the possibility of limited indeterminism. (shrink)