Multiple Markets and Spatial Agglomeration in a One Shopping Trip Model

This paper analyzes a spatial competitive monopolistic model of agglomeration in which households make only one shopping trip per period, and there are several firms in each industry. The model is a version of a model by Fujita (1988), but unlike his, in this model no equilibrium mixed district is possible, and a number of firm districts may appear. It is shown that allowing several firms in each industry may lead to a Mall equilibrium or an equilibrium with multiple shopping centers.agglomeration, bid-rent, land use, residential district, firm district

Barter Economies and Centralized Merchants

The main goal of this essay is to analyze the emergence of a barter economy, and the rise of centralized merchants and a barter redistribution system out of a primitive barter system. The environment is a spatial general equilibrium model where exchange is costly. Since exchange becomes more complicated as the scope of the economy increases, we prove that, after the economy reaches a critical size, the cost of trade expansion surpasses its benefits. This imposes limitations on the scope of the economy and the production level. To overcome these limitations, rational individuals can develop a more advanced barter system leading to the appearance of centralized merchants. This more sophisticated system is the redistribution system. We also show that under some circumstances, in the presence of transaction costs it may be optimal for individuals to keep using barter instead of adopting a monetary system. This result explains why some primitive economies, like the Incas in Peru and ancient Egypt, did not evolve to a monetary system, and kept barter as their main exchange system.

Inflation and Capital Structure

This essay is a contribution to the empirical literature on the effect of inflation tax on capital structure. A simple empirical model considering the main results of the current theoretical development is studied, using microdata from a number of American corporations.inflation tax, capital structure, firm value, debt-capital ratio

Multiple Markets and Spatial Agglomeration in a One Shopping Trip Model

This paper analyzes a spatial competitive monopolistic model of agglomeration in which households make only one shopping trip per period, and there are several firms in each industry. The model is a version of a model by Fujita (1988), but unlike his, in this model no equilibrium mixed district is possible, and a number of firm districts may appear. It is shown that allowing several firms in each industry may lead to a Mall equilibrium or an equilibrium with multiple shopping centers.

Inflation and Capital Structure

This essay is a contribution to the empirical literature on the effect of inflation tax on capital structure. A simple empirical model considering the main results of the current theoretical development is studied, using microdata from a number of American corporations.

Solution of some problems in the arithmetical complexity of first-order fuzzy logics

This short paper addresses the open problems left in a previous paper by Franco Montagna and Carles Noguera. Besides giving solutions to these two problems, some clarification concerning the role of the full vocabulary (including functional symbols) in the proofs there given is also discussed.Comment: 5 page

Distribution amplitude for the photon-pion transition

The exclusive production of \pi\pi and \pi\rho in hard \gamma^{\star}\gamma scattering in the forward kinematical region where the virtual photon is highly off-shell are studied through the \gamma\to\pi^- Transition Distribution Amplitudes. The calculation is based on a covariant Bethe-Salpeter approach, applied to the Nambu - Jona-Lasinio model, for the determination of the pion bound state. In particular it is shown that the pion pole contribution produces a large enhancement of the differential cross section for the pion pair production with respect to previous estimates.Comment: To appear in the proceedings of Light Cone 2008: Relativistic Nuclear and Particle Physics (LC2008), Mulhouse, France, 7-11 Jul 200

The Pion-Photon Transition Distribution Amplitudes in the Nambu-Jona Lasinio Model

We define the pion-photon Transition Distribution Amplitudes (TDA) in a field theoretic formalism from a covariant Bethe-Salpeter approach for the determination of the bound state. We apply our formalism to the Nambu - Jona Lasinio model, as a realistic theory of the pion. The obtained vector and axial TDAs satisfy all features required by general considerations. In particular, sum rules and polynomiality condition are explicitly verified. We have numerically proved that the odd coefficients in the polynomiality expansion of the vector TDA vanish in the chiral limit. The role of PCAC and the presence of a pion pole are explicitly shown.Comment: 14 pag. and 6 fig, final version (to appear in Phys. Rev. D

How open are journalists on Twitter? Trends towards the end-user journalism

The many activities of journalists on Twitter should be analyzed. Are they doing a different kind of journalism? With a content analysis of 1125 tweets, this study reveals trends of some Spanish journalists using Twitter. A traditional role like gatekeeping can be highly amplified in terms of transparency and accountability with actions as retweeting or linking. The landscape offered by this platform is framed with the "ambient journalism", which will help to understand the proposal of this study: the end-user journalism. The findings will show the level of opening with the audience in aspects about replies, requests and linking