A virtual voyage through 3D structures generated by chaotic mixing of magmas and numerical simulations: a new approach for understanding spatial and temporal complexity of magma dynamics

In this contribution, we present a virtual voyage through 3D structures generated by chaotic mixing of magmas and numerical simulations with the aim to highlight the power of 3D representations in the understanding of this geological phenomenon. In particular, samples of mixed juveniles from Salina island (Southern Italy) are reconstructed in 3D by serial lapping and digital montage and numerical simulations are performed by using a 3D chaotic dynamical system. Natural and simulated magma mixing structures are visualized by using several multimedia tools including animations and “virtual reality” models. It is shown that magma interaction processes can generate large spatial and temporal compositional heterogeneities in magmatic systems. The same topological structures are observed in both 3D reconstructed rock samples and chaotic numerical simulations, indicating that the mixing of magmas is governed by chaotic dynamics. The use of 3D multimedia models gives the opportunity to penetrate into magma mixing structures and to understand their significance in the context of magma dynamics. Such an approach is very powerful since multimedia tools can strongly capture the attention of the reader bringing him/her into an interactive and memorable geological experience.     

Virtual integration and endogenous growth in the world economy

This study develops a three-country model of endogenous growth that captures the role of the interconnection of country-specific communications networks (i.e., virtual integration), which affects the productivity of R&D activity through an increase in stock of knowledge capital. The number of countries connected to internationally interconnected networks is found to determine the structure of dynamic comparative advantages. That is, countries with interconnected networks have a dynamic comparative advantage in differentiated products that require communication and activities. In the connected countries, researchers gain from efficient activity through the utilization of the greater stock of knowledge capital. The author acknowledges the comments from the participants at the 56th International Atlantic Economic Conference, held October 16–19, 2003, in Quebec City, Canada. The author is also grateful to the anonymous referee of this journal for helpful comments and suggestions.     

Testing the null hypothesis of no regime switching with an application to GDP growth rates

This paper presents tests for the null hypothesis of no regime switching in Hamilton’s (Econometrica 57:357–384, 1989) regime switching model. The test procedures exploit similarities between regime switching models, autoregressions with measurement errors, and finite mixture models. The proposed tests are computationally simple and, contrary to likelihood based tests, have a standard distribution under the null. When the methodology is applied to US GDP growth rates, no strong evidence of regime switching is found. I thank Don Andrews, Peter Phillips, Yuichi Kitamura, Anat Bracha, Patrik Guggenberger, Orit Whiteman and three anonymous referees for useful comments and suggestions.     

The unanimity rule and religious fractionalisation in the Polish-Lithuanian Republic

This paper analyses the role of the unanimity rule—known as liberum veto—in medieval Poland. We argue that the primary effect of the liberum veto was that it secured religious freedom and established domestic peace in an otherwise deeply divided and fractionalised country. What is more, this institution succeeded in doing so during an era which was characterised by violent religious conflicts and rise of absolutist monarchies throughout the European continent. Even after 1652, when the liberum veto seemed to have practically paralysed the decision-making of Polish-Lithuanian parliament, there were still reasons—related to religious issues—why its use could have been preferable to less inclusive voting rules. It can be argued, however, that the use of unanimity was not warranted in questions related to defence, especially in situations of national emergency, although it is questionable to which extent the sole presence of the liberum veto was susceptible to bring about the demise of the Polish-Lithuanian Republic.

The origins and evolution of democracy: an exercise in history from a constitutional economics approach

In this article the conditions for the rise and fall of representative regimes are explored. High citizen mobility and unexploited opportunities for investment create the need of reassuring factor owners against the tax hunger of the State. This may lead to the emergence of representative institutions of government, a process that reverts when those conditions disappear. Factors that facilitate or restrain the mobility of citizenry are identified, mainly in the domain of military technology. Thus, a number of interrelations between production and war technologies, political development and economic performance are revealed, giving rise to an interpretation of historical evolution.

Industry specific effects in investment performance and valuation of firms

A necessary criterion for a performance measure in corporate governance is the degree to which it mirrors how well the management succeeds in maximizing firm value. Such a performance measure is marginal q which links changes in firm value to the investments undertaken by the management. Empirical studies of investment and performance based on marginal q have demonstrated the usefulness of this measure. Most research however, has mainly focused on long-term performance. This paper takes a short-term perspective and, based on the marginal q-theory, considers how firms’ market values change in the extreme stock price cycle of a stock market bubble. Using a data set of listed Swedish corporations we find an anomaly in form of a new industry specific effect that, in addition to investment, explains changes in firm value.

Economics of externalities and public policy

In this paper we study a particular case of “multiple” externalities associated to the production of a good/activity, whose external effects can change from positive to negative depending on the level of output (intersecting externalities). To analyze their impact on the public policy we propose a very simple two-agent partial equilibrium model in the technological context of externalities. In a static framework, the centralized solution always implies an optimal policy, which may consist of taxation or subsidization depending on the individual optimum and on the technology parameters. In a dynamic model with local knowledge of the efficiency function and instantaneous output adjustments, such an optimal policy can be structurally stable or unstable. In the latter case, under small changes of the parameters the policy may switch from low taxation/subsidization to high taxation/subsidization or vice versa, or even jump discontinuously from taxation to subsidization or vice versa. Furthermore, the decentralized solution based upon “tradable rights” can be economically equivalent to the centralized solution in the form of taxation policy but the two solutions may be not politically equivalent.

Stylised features of consumer price setting behaviour in Portugal: 1992–2001

This paper identifies the empirical stylized features of consumer price setting behavior in Portugal using two micro-datasets underlying the consumer price index. The main conclusions are: one in every four prices change each month; there is a considerable degree of heterogeneity in price setting practices; prices of goods change more often than prices of services; price reductions are common, as they account to around 40% of total price changes; price changes are, in general, sizeable; finally, the price setting patterns seem to depend on the level of inflation as well as on the type of outlet.

Self-ignorance: Towards an extension of the Austrian paradigm

This article argues for an extension of the Austrian paradigm of the ignorance of actors. The idea that will be defended here is that actors are not only confronted with their lack of knowledge of the other person but also with their lack of self-knowledge. From this perspective, the article seeks to understand the implications of this phenomenon in terms of infra-individual coordination and to account for the mental processes mobilized by the individual mind so as to deal with that self-ignorance.

Forecasting inflation with an uncertain output gap

The output gap is a crucial concept in the monetary policy framework, indicating demand pressure that generates inflation. However, its definition and estimation raise a number of theoretical and empirical questions. This paper evaluates a series of univariate and multivariate methods for extracting the output gap in Norway, and compares their value added in predicting inflation. We find that models including the output gap have better predictive power than models based on alternative indicators, and they forecast significantly better than simple benchmark models. Furthermore multivariate measures of the output gap perform better than the univariate gaps. Comments from two anonymous referees, Q. Farooq Akram, Tommy Sveen, Ken West, Fredrik Wulfsberg and seminar participants in Norges Bank are gratefully acknowledged. All mistakes remain our own. The views expressed are those of the authors and do not necessarily represent those of Norges Bank.