Search results for "Toro"
showing 10 items of 266 documents
Magnetic braking and damping of differential rotation in massive stars
2018
Fragmentation of highly differentially rotating massive stars that undergo collapse has been suggested as a possible channel for binary black hole formation. Such a scenario could explain the formation of the new population of massive black holes detected by the LIGO/VIRGO gravitational wave laser interferometers. We probe that scenario by performing general relativistic magnetohydrodynamic simulations of differentially rotating massive stars supported by thermal radiation pressure plus a gas pressure perturbation. The stars are initially threaded by a dynamically weak, poloidal magnetic field confined to the stellar interior. We find that magnetic braking and turbulent viscous damping via …
Termination of the magnetorotational instability via parasitic instabilities in core-collapse supernovae
2016
The magnetorotational instability (MRI) can be a powerful mechanism amplifying the magnetic field in core-collapse supernovae. Whether initially weak magnetic fields can be amplified by this instability to dynamically relevant strengths is still a matter of debate. One of the main uncertainties concerns the process that terminates the growth of the instability. Parasitic instabilities of both Kelvin-Helmholtz and tearing-mode type have been suggested to play a crucial role in this process, disrupting MRI channel flows and quenching magnetic field amplification. We perform two-dimensional and three-dimensional sheering-disc simulations of a differentially rotating protoneutron star layer in …
Non-linear evolutions of magnetized thick discs around black holes: dependence on the initial data
2020
We build equilibrium solutions of magnetised thick discs around a highly spinning Kerr black hole and evolve these initial data up to a final time of about 100 orbital periods. The numerical simulations reported in this paper solve the general relativistic magnetohydrodynamics equations using the BHAC code and are performed in axisymmetry. Our study assumes non-self-gravitating, polytropic, constant angular momentum discs endowed with a purely toroidal magnetic field. In order to build the initial data we consider three approaches, two of which incorporate the magnetic field in a self-consistent way and a third approach in which the magnetic field is included as a perturbation on to an othe…
Magnetorotational Instability in Core-Collapse Supernovae
2017
We discuss the relevance of the magnetorotational instability (MRI) in core-collapse supernovae (CCSNe). Our recent numerical studies show that in CCSNe, the MRI is terminated by parasitic instabilities of the Kelvin-Helmholtz type. To determine whether the MRI can amplify initially weak magnetic fields to dynamically relevant strengths in CCSNe, we performed three-dimensional simulations of a region close to the surface of a differentially rotating proto-neutron star in non-ideal magnetohydrodynamics with two different numerical codes. We find that under the conditions prevailing in proto-neutron stars, the MRI can amplify the magnetic field by (only) one order of magnitude. This severely …
From Spain to Sicily after the Expulsion: Conversos between Economic Networks and the Aristocratic Elite
2018
Abstract This article focuses on a group of conversos families from Spain, who established themselves in Palermo after the Expulsion of the Jews in 1492. There they supported financial activities of the Nazione Catalana and established strong relationships with the local aristocracy. Thanks to this alliance, they managed to avoid persecution by the Spanish Inquisition, “cleanse” their “impure” blood and reach high positions within politics and society: feudal titles, political and financial offices, habits of military orders, ecclesiastical appointments and sometimes even sainthood. Firstly, the paper will give a brief sketch of the phenomenon of conversos in Sicily as well as the activitie…
Anverso y reverso de la nación: el discurso de la antiespañolada durante los primeros años 40
2015
During the immediate postwar years, different voices from the new francoist regime produced a discourse relatively spontaneous but, at the same time, recognizable enough addressed to denounce what they considered as an unacceptable deformation of the Spanishness. Basically, and in spite of the ideological differences amongst its producers, the critic raised from a common and painful nationalism which pointed at the foreign look —specially, the French romantic look— as creator and supporter of what they called España de pandereta. This look supposed a distortion and mystification of Spain as a picturesque nation that resulted in the españolada. The aim of this article is to explore this disc…
Ein neues captorhinomorphes reptil aus dem thüringischen rotliegend (Unter-Perm; Ost-Deutschland)
1991
Thuringothyris mahlendorffae n.gen. n.sp. is described on the basis of the skull roof, palate, stapes and much of the postcranial skeleton from the Upper Rotliegend (Tambach-Schichten) of the Thuringian Forest in eastern Germany. The new taxon shows both protorothyridid and some captorhinid features. The interrelationships of the »Protorothyrididae«, primitive Captorhinidae, and earliest Diapsida are reviewd. The tetrapod material is used to reassess the biostratigraphic position of the fossil-bearing horizon.
Hardy’s inequality and the boundary size
2002
We establish a self-improving property of the Hardy inequality and an estimate on the size of the boundary of a domain supporting a Hardy inequality.
On improved fractional Sobolev–Poincaré inequalities
2016
We study a certain improved fractional Sobolev–Poincaré inequality on domains, which can be considered as a fractional counterpart of the classical Sobolev–Poincaré inequality. We prove the equivalence of the corresponding weak and strong type inequalities; this leads to a simple proof of a strong type inequality on John domains. We also give necessary conditions for the validity of an improved fractional Sobolev–Poincaré inequality, in particular, we show that a domain of finite measure, satisfying this inequality and a ‘separation property’, is a John domain.
Gli Heraia di Olimpia e le donne di Elide. Riti di passaggio e inni tra Era e Dioniso
2012
Gli agoni dedicati ad Era che si tenevano ad Olimpia ogni quattro anni (Paus. V, 16, 2-4), in cui erano previste competizioni atletiche e musicali femminili contrapposte e complementari a quelle maschili delle Olimpiadi, non solo illustrano alcune caratteristiche fondamentali del culto di Era, che rimanda alla sfera femminile delle nozze, ma rivelano anche interessanti aspetti del culto di Dioniso, divinità alla quale Era appare connessa da quella che W. Burkert ha definito una “strana intimità”. La presenza dei culti di Era e di Dioniso negli Heraia, i cui agoni si configuravano come fasi di riti di passaggio per le fanciulle che vi prendevano parte, ben rappresenta i reciproci condizionam…