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

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

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

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

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

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 childbirths decrease the risk of union dissolution.fertility, Italy, Spain, union dissolution

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.

Optimal Control Problems Arising In Marketing Models

The diffusion in time of a new product in a monopolistic or oligopolistic market can be described by a system of evolution equations (PDE, ODE, DDE) containing one or more control parameters (advertising, prices, plant locations, ...). The productors choose the control parameters in order to maximize their (discounted) prots. Hence an optimal control problems (in the case of a monopoly) or a dynamic game (in the case of an oligopoly) has to be solved. A specic model is proposed and an exhaustive description of its solution is given.