A note on an Umayyad carved ivory plaque kept at the Walters Art Gallery

This paper proposes an iconographical and stylistic analysis of a carved ivory plaque kept at the Walters Art Gallery in Baltimore (acc. no. 71.62). It will show that it is not a Coptic artefact featuring a Sasanian king, as assumed until now, but an Umayyad artefact which must be contextualised within a specific tradition of imagery related to the expression of the Umayyad concept of Caliphal authority

How fertility and union stability interact in shaping new family patterns in Italy and Spain

In this paper we investigate the interrelationships between fertility decisions and union dissolution in Italy and Spain. We argue that there might exist a spurious relationship between these two life trajectories. The analysis is based on the 1996 Fertility and Family Survey data for Italy and Spain. Results show that there is a spurious relationship between fertility and union dissolution in Italy but not in Spain. Nevertheless, in both countries, there is an evident direct effect of each process on the other: union dissolution decreases the risk of further childbearing, while childbirth decreases the risk of union dissolution.Italy, Spain, divorce rate, fertility

Estimating expectations of shocks using option prices

The jump-diffusion model introduced by Merton is used to price a cross- section of options at different dates. At any point in time, the parameters of the model are estimated by minimizing the sum of squared implied volatility errors, and their informational content is compared with the widely used Black and Scholes implied volatility, calculated on at-the-money options. While in normal conditions the parameters of Merton's model do not seem to provide any additional information, in periods of high variability of asset prices the jump-diffusion approach may help to disentangle the cases in which volatility reflects only uncertainty on economic fundamentals from those in which it is fuelled by fears of ¯nancial crisis.jump-diffusion stochastic processes, option pricing, volatility

Hellenistic Gymnasia in the Heart of Athens: Change and Continuity

Während die alten Gymnasia (Akademie, Lykaion, Kynosarges) außerhalb der Stadtmauern Athens lagen, wurden kurz nach 229 v. Chr. zwei neue Gymnasia im Zentrum der Stadt errichtet: das Diogeneion und das Ptolemaion. In diesem Beitrag werden die Geschichte, Architektur und Funktion dieser beiden Gymnasia untersucht, auf Basis einer systematischen Analyse aller relevanten literarischen, epigraphischen und archäologischen Quellen. Die Komplexe waren wichtig für das Stadtbild, weil sie dem chaotischen, altmodischen Zentrum einen Hauch von Modernität verliehen. Ihre exakte Lage bleibt zwar umstritten, aber sie waren topographisch und ideologisch fest mit dem alten Stadtzentrum verbunden und dienten als Zentren für die Ausbildung der Epheben in der gesamten hellenistischen und römischen Zeit

Optimal marketing decision in a duopoly: a stochastic approach

Let us consider two new perfect substitute durable products which are produced and sold in a market by two competing firms. Looking at a potential buyer, we build a stochastic rule by which she purchases the good from one of the two firms (so that she becomes an adopter). The model is considered discrete in time and space. The probability of transition from the non adopter state to the adopter one depends on an imitation mechanism (word-ofmouth) as well as on the pricing and advertising policies of the producers/sellers. It is assumed that only actual information about the market determine the evolution in the subsequent time step so that a Markov process arises. Both firms maximize their expected discounted profits by choosing optimal marketing strategies. Suitable equilibria are characterized and, because of the lack of convexity in the model, the simulated annealing algorithm is proposed to compute them.

From 'Alī to Dante's «Alì» : a Western Medieval Understanding of «Shī'a»

This paper focuses on the figure of Alì, found along with Maometto and sowers of scandal and schism in Dante's Divina Commedia (Inferno 28). While early commentators on the poem variously identify Alì as a companion or disciple of Maometto's, or his heretical teacher, modern commentators identify him as 'Alī b. Abī Ṭālib, Muḥammad's cousin and son-in-law. Both explain his condemnation as due to a religious schism he caused: according to the former, Alì inspired or pursued the division of Christianity provoked by Maometto; according to the latter, he was responsible for the division of the Muslim community into Sunnites and Shi'ites. Nevertheless, these interpretations do not clarify why Alì is not condemned by Dante along with heresiarchs but rather alongside characters responsible for violent divisions within social and political contexts. An analysis of the sources on 'Alī and the Shī'a available in Europe up to the beginning of the 14th century shows that Dante, unlike his early commentators, relied on pseudo-historical biographies of Muḥammad in which the division between Sunnites and Shi'ites, ascribed to 'Alī, was interpreted as a political phenomenon concerning the dispute over authority and territorial control between Sunni Caliphs in the East and Shi'i imams in the West. By reading Inferno 28 from this perspective, through the social and political view expressed by Dante in the Monarchia, it is possible to infer that Dante considered Muḥammad as responsible for the subversion of the universal empire, and 'Alī as responsible for a further fragmentation of the imperial authority.Esta contribución estudia la figura de Alí, condenado junto a Maometto, como diseminadores de escándalo y de cisma en el Infierno de Dante. Mientras los comentadores antiguos han identificadao este personaje bien como un compañero o bien como un discípulo de Maometto, los comentadores modernos opinan que se trata de 'Alī b. Abī Ṭālib, primo y yerno de Muḥammad. En ambos casos, su condena es atribuida al cisma religioso que causó: según los comentaristas antiguos Alí habría inspirado o perseguido la división de la cristiandad provocada por Maometto; pero, según los modernos, habría sido considerado como responsable de la división de la comunidad islámica en Sunnitas y Sci'itas. Sin embargo, estas interpretaciones no dejan en claro por qué Dante no situó a Alí entre los heresiarcas sino entre personajes responsables de violentas divisiones en un contexto social y político. El análisis de las fuentes sobre 'Alī y la Shī'a difundidas en Europa hasta los inicios del siglo XIV, y esto se evidencia en Dante, muestra que en la biografía pseudo histórica de Muḥammad la división entre Sunnitas y Shi'itas atribuida a 'Alī había sido interpretada como un fenómeno relativo a la disputa sobre la autoridad y el control territorial entre los califas de oriente, Sunnitas, y los imam de occidente, Shi'itas. A partir de la lectura del canto XXVIII del Infierno según esta perspectiva, mediante la visión socio-política expresada por Dante en su Monarchia, se puede formular la hipótesis que Dante considerase a Muḥammad responsable de la subversión del imperio universal y a 'Alī de la ulterior fragmentación de la autoridad imperial. En consecuencia, los cismas que le son imputados a 'Alī y Muḥammad tendrían una dimensión social y política más que religiosa

An analysis of the determinants of credit default swap spread changes before and during the subprime financial turmoil

This paper analyzes the determinants of credit default swap spread changes for a large sample of US non-financial companies over the period between January 2002 and March 2009. In our analysis we use variables that the literature has found have an impact on CDS spreads and, in order to account for possible non-linear effects, the theoretical CDS spreads predicted by the Merton model. We show that our set of variables is able to explain more than 50% of CDS spread variations both before and after July 2007, when the current financial turmoil began. We also document that since the onset of the crisis CDS spreads have become much more sensitive to the level of leverage while volatility has lost its importance. Using a principal component analysis we also show that since the beginning of the crisis CDS spread changes have been increasingly driven by a common factor, which cannot be explained by indicators of economic activity, uncertainty, and risk aversion.credit default swaps, bond spreads, credit risk, Merton model