295 research outputs found

    Measuring international skilled migration: new estimates controlling for age of entry

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    Recent data on international skilled migration define skilled migrants according to education level independently of whether education has been acquired in the home or in the host country. In this paper we use immigrants’ age of entry as a proxy for where education has been acquired. Data on age of entry are available from a subset of receiving countries which together represent more than 3/4 of total skilled immigration to the OECD. Using these data and a simple gravity model, we estimate the age-of-entry structure of skilled immigration and propose alternative brain drain measures by excluding those arrived before age 12, 18 and 22. The results for 2000 show that on average, 68% of the global brain drain is accounted for by emigration of people aged 22 or more upon arrival (78% and 87% for the 18 and 12 year old thresholds, respectively). For some countries this indeed makes a substantial difference. However, cross-country differences are globally maintained, resulting in extremely high correlation levels between corrected and uncorrected rates. Similar results are obtained for 1990

    Is there a Common European Business Cycle? New Insights from a Frequency Domain Analysis

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    To assess the synchronization of business cycles in Europe we extract the cyclical component of industrial production in five European countries using the filter of Baxter and King (1999). The hypothesis of a joint business cycle is tested by using the frequency domain common cycle test suggested by Breitung and Candelon (2000). The common cycle hypothesis is clearly rejected for U.K. data whereas some weak evidence for a joint cyclical pattern is found for France, The Netherlands, Austria and Germany. Zusammenfassung Gibt es einen gemeinsamen europäischen Konjunkturzyklus? Neue Erkenntnisse durch eine Spektralanalyse Um die Synchronität der Konjunkturzyklen in Europa zu bewerten, wird die Zykluskomponente der Industrieproduktion in fünf europäischen Ländern identifiziert, indem der Baxter-King-Filter (1999) angewendet wird. Die Hypothese eines gemeinsamen Konjunkturzyklus wird durch einen Test auf einen gemeinsamen Zyklus im Frequenzbereich nach Breitung und Candelon (2000) überprüft. Ein gemeinsamer Konjunkturzyklus muss demnach für Großbritannien klar zurückgewiesen werden, wohingegen einige schwache Anzeichen für ein gemeinsames Konjunkturmuster für Frankreich, die Niederlande, Österreich und Deutschland gefunden werden konnten

    Kinetics of isothermal and non-isothermal precipitation in an Al-6at%Si alloy

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    A novel theory which describes the progress of a thermally activated reaction under isothermal and linear heating conditions is presented. It incorporates nucleation, growth and impingement and takes account of temperaturedependent solubility. The model generally fits very well to isothermal calorimetry and differential scanning calorimetry data on precipitation in an Al-6 at.% Si alloy. Analysis of the data shows that two processes occur in this precipitation reaction: growth of large Si particles and growth of pre-existing small nuclei. Determination of the sizes of Si precipitates by transmission electron microscopy indicates that interfacial energy contributions are small and have a negligible influence on solubilit

    An overview of snow photochemistry: Evidence, mechanisms and impacts

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    It has been shown that sunlit snow and ice plays an important role in processing atmospheric species. Photochemical production of a variety of chemicals has recently been reported to occur in snow/ice and the release of these photochemically generated species may significantly impact the chemistry of the overlying atmosphere. Nitrogen oxide and oxidant precursor fluxes have been measured in a number of snow covered environments, where in some cases the emissions significantly impact the overlying boundary layer. For example, photochemical ozone production (such as that occurring in polluted mid-latitudes) of 3-4 ppbv/day has been observed at South Pole, due to high OH and NO levels present in a relatively shallow boundary layer. Field and laboratory experiments have determined that the origin of the observed NO x flux is the photochemistry of nitrate within the snowpack, however some details of the mechanism have not yet been elucidated. A variety of low molecular weight organic compounds have been shown to be emitted from sunlit snowpacks, the source of which has been proposed to be either direct or indirect photo-oxidation of natural organic materials present in the snow. Although myriad studies have observed active processing of species within irradiated snowpacks, the fundamental chemistry occurring remains poorly understood. Here we consider the nature of snow at a fundamental, physical level; photochemical processes within snow and the caveats needed for comparison to atmospheric photochemistry; our current understanding of nitrogen, oxidant, halogen and organic photochemistry within snow; the current limitations faced by the field and implications for the future

    An Overview of Snow Photochemistry: Evidence, Mechanisms and Impacts

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    It has been shown that sunlit snow and ice plays an important role in processing atmospheric species. Photochemical production of a variety of chemicals has recently been reported to occur in snow/ice and the release of these photochemically generated species may significantly impact the chemistry of the overlying atmosphere. Nitrogen oxide and oxidant precursor fluxes have been measured in a number of snow covered environments, where in some cases the emissions significantly impact the overlying boundary layer. For example, photochemical ozone production (such as that occurring in polluted mid-latitudes) of 3-4 ppbv/day has been observed at South Pole, due to high OH and NO levels present in a relatively small boundary layer. Field and laboratory experiments have determined that the origin of the observed NOx flux is the photochemistry of nitrate within the snowpack, however some details of the mechanism have not yet been elucidated. A variety of low molecular weight organic compounds have been shown to be emitted from sunlit snowpacks, the source of which has been proposed to be either direct or indirect photo-oxidation of natural organic materials present in the snow. Although myriad studies have observed active processing of species within irradiated snowpacks, the fundamental chemistry occurring remains poorly understood. Here we consider the nature of snow at a fundamental, physical level; photochemical processes within snow and the caveats needed for comparison to atmospheric photochemistry; our current understanding of nitrogen, oxidant, halogen and organic photochemistry within snow; the current limitations faced by the field and implications for the future

    Dynamic linkages between stock markets : the effects of crises and globalization

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    This paper investigates changes in the dynamics of linkages between selected national stock markets during the period 1995–2009. The analysis focuses on the possible effects of globalization and differences between crisis and non-crisis periods. We model the dynamics of dependencies between the series of daily returns on selected stock indices over different time periods, and compare strength of the linkages. Our tools are dynamic copula models and a formal sequential testing procedure based on the model confidence set methodology. We consider two types of dependencies: regular dependence measured by means of the conditional Spearman’s rho, and dependencies in extremes quantified by the conditional tail dependence coefficients. The main result consists of a collection of rankings created for the considered subperiods, which show how the mean level of strength of the dependencies have been changing in time. The rankings obtained for Spearman’s rho and tail dependencies differ, which allows us to distinguish between the results of crises and the effect of globalization.info:eu-repo/semantics/publishedVersio
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