Estimating the volume of tephra deposits: a new simple strategy

Volume determination of tephra deposits is necessary for the assessment of the dynamics and hazards of explosive volcanoes. Several methods have been proposed during the past 40 years that include the analysis of crystal concentration of large pumices, integrations of various thinning relationships, and the inversion of field observations using analytical and computational models. Regardless of their strong dependence on tephra-deposit exposure and distribution of isomass/isopach contours, empirical integrations of deposit thinning trends still represent the most widely adopted strategy due to their practical and fast application. The most recent methods involve the best fitting of thinning data using various exponential seg- ments or a power-law curve on semilog plots of thickness (or mass/area) versus square root of isopach area. The exponential method is mainly sensitive to the number and the choice of straight segments, whereas the power-law method can better reproduce the natural thinning of tephra deposits but is strongly sensitive to the proximal or distal extreme of integration. We analyze a large data set of tephra deposits and propose a new empirical method for the deter- mination of tephra-deposit volumes that is based on the integration of the Weibull function. The new method shows a better agreement with observed data, reconciling the debate on the use of the exponential versus power-law method. In fact, the Weibull best fitting only depends on three free parameters, can well reproduce the gradual thinning of tephra deposits, and does not depend on the choice of arbitrary segments or of arbitrary extremes of integration.

Are the antiglobalizers right?: the issue of trade without a Walrasian auctioneer

This paper analyzes the determinants of expectational coordination on the perfect foresight equilibrium of an open economy in the class of one-dimensional models where the price is determined by price expectations. In this class of models, we relate autarky expectational stability conditions to regional integration ones, providing an intuitive open economy interpretation ofthe elasticities condition obtained by Guesnerie [11]. There, we show that the degree of structural heterogeneity trades-off the existence of standard efficiency gains -due to the increase in competition (spatial price stabilization)- and coordination upon the welfare enhancing free-trade equilibrium (stabilizing price expectations). This trade-off provides a new rationale for an exogenous price intervention at the international levei. Through the coordinational concern of the authority, trading countries are ab]e to fully reap the bene:fits from trade. We illustrate this point showing that classical measures evaluating ex-ante the desirability of economic integration (net welfare gains) do not always advise integration between two expectationally stable economies.

A sensor for monitoring the volume of nutrient in a solid substrate-based growth media by using electrochemical admittance spectroscopy

A sensor was fashioned to monitor the volume of nutrient in a solid substrate-based growth media by using electrochemical admittance spectroscopy. Several experimental parameters were investigated (i.e. The use of two- or three-electrode cells, the superficial area of the electrode, the amount of nutrient solution added to the growth media, and the influence of varying the dc and ac potential) to assess how these variables affect the admittance of the system. A linear correlation was observed between the maximum of the imaginary admittance and the volume of nutrient present. The response factor was 2.8 x 10(-5) S cm(-2) ml(-1) and the limit of detection (LOD) was 0.54 ml. The humidity of the growth media does not change the response of the nutrient toward the monitoring measurements. These results demonstrate that the volume of nutrient in this solid substrate-based growth media can be assessed using a ceramic sensor to measure the imaginary admittance. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Analysis of the effects of trade opening on household welfare: an application to Chile, 1999-2006

Incluye bibliografía

Policy alternatives and strategies for the Plurinational State of Bolivia following the end of trade preferences

Include bibliography

Policy alternatives and strategies for the Plurinational State of Bolivia following the end of trade preferences

Includes bibliography

Analysis of the effects of trade opening on household welfare: an application to Chile, 1999-2006

Includes bibliography

The competitiveness of agrifoods in Central American and Caribbean countries in the context of trade liberalization

Includes bibliography

Returning to an external debate: the terms of trade for commodities in the twentieth century

Includes bibliography

La estabilidad de la relación de precios del intercambio en los países poco desarrollados = Stabilizing the terms of trade of underdeveloped countries

Publicado separadamente en cada idioma

The terms of trade for commodities in the twentieth century

Includes bibliography

Resolución 262(AC.58): Actividades de la CEPAL en materia de comercio y desarrollo = Resolution 262(AC.58): ECLA's activities in the field of trade and development = Résolution 262(AC.58): Activités de la CEPAL concernant le commerce et le développement

Incluye Bibliografía