Breaking the mass / anisotropy degeneracy in the Coma cluster

We provide the first direct lifting of the mass/anisotropy degeneracy for a cluster of galaxies, by jointly fitting the line of sight velocity dispersion and kurtosis profiles of the Coma cluster, assuming an NFW tracer density profile, a generalized-NFW dark matter profile and a constant anisotropy profile. We find that the orbits in Coma must be quasi-isotropic, and find a mass consistent with previous analyses, but a concentration parameter 50% higher than expected in cosmological N-body simulations. We then test the accuracy of our method on realistic non-spherical systems with substructure and streaming motions, by applying it to the ten most massive structures in a cosmological N-body simulation. We find that our method yields fairly accurate results on average (within 20%), although with a wide variation (factor 1.7 at 1 sigma) for the concentration parameter, with decreased accuracy and efficiency when the projected mean velocity is not constant with radius.Comment: 5 pages, oral presentation at IAU Colloquium 195, Outskirts of Galaxy Clusters: intense life in the suburbs, ed. A. Diaferi

Structure, mass and distance of the Virgo cluster from a Tolman-Bondi model

We have applied a relativistic Tolman-Bondi model of the Virgo cluster to a sample of 183 galaxies with measured distances within a radius of 8 degrees from M87. We find that the sample is significantly contaminated by background galaxies which lead to too large a cluster mean distance if not excluded. The Tolman-Bondi model predictions, together with the HI deficiency of spiral galaxies, allows one to identify these background galaxies. One such galaxy is clearly identified among the 6 calibrating galaxies with Cepheid distances. As the Tolman-Bondi model predicts the expected distance ratio to the Virgo distance, this galaxy can still be used to estimate the Virgo distance, and the average value over the 6 galaxies is 15.4 +- 0.5 Mpc. Well-known background groups of galaxies are clearly recovered, together with filaments of galaxies which link these groups to the main cluster, and are falling into it. No foreground galaxy is clearly detected in our sample. Applying the B-band Tully-Fisher method to a sample of 51 true members of the Virgo cluster according to our classification gives a cluster distance of 18.0 +- 1.2 Mpc, larger than the mean Cepheid distance. Finally, the same model is used to estimate the Virgo cluster mass, which is M = 1.2 10^{15} Msun within 8 degrees from the cluster center (2.2 Mpc radius), and amounts to 1.7 virial mass.Comment: 12 pages, 7 figures. Astronomy and Astrophysics, in press (accepted May 31, 2001

Disaggregated Productivity Growth and Technological Progress in the interpretation of Spanish Economic Growth, 1958-1975

Spanish economic records in terms of GDP growth and convergence to European levels in the sixties, provide an excellent opportunity to look at a central question underlying in the interpretation of any process of economic growth. The relevance of industrial specific technological progress is confronted to a general and multifaceted productivity change coming from a variety of sectors and causes. This paper exploits sectoral growth accounting methodology in two different ways in order to answer this crucial question revisited recently by historiography with reference to British Industrial Revolution and to Information and Telecommunications Technologies. First, we calculate TFP growth following the Kendrick approach (1961) and using four input-output tables corresponding to 1958, 1962, 1970 and 1975 disaggregated at 25 productive branches. And Second, we examine the impact of electricity and electric machinery and equipment as a General Purpose Technology (GPT) in Spanish economic growth.

El coste de uso del capital en la explicación del boom de la inversión europea de posguerra

Post-war Europe provides an opportunity to study the importance of relative prices of capital, and the user cost of capital in particular, in explaining the convergence in investment rates between countries of similar “social capabilities” and income levels. After Second World War, at time as a new international order was established, European countries experienced a rapid process of income growth and convergence. In the interpretation of this process a prominent role has been attributed to technological progress and “catch-up” to the technological leader, the United States. Investment decisions are the way for embodying new technological progress, but investment takes place only when incentive exists. Among these incentives, recent empirical literature on economic growth highlights the role of relative prices of capital in explaining differences in investment rates and income growth between countries with very different income levels. But when we reduce the sample to countries closed in income levels and “social capabilities”, we can demonstrate that, although the relative cost of capital converged over time and could help to explain income convergence, other factors were more significant in explaining the increase in investment rates. More important than the user cost of capital in the investment decision, was general prosperity caused by the demand increase.

The effect of foreign and domestic patents on total factor productivity during the second half of the 20th century

This paper analyses the relationship between total factor productivity (TFP) and innovation-related variables during the second half of the 20th century. We perform this analysis for several European countries (France, Germany, the United Kingdom, and Spain) and the U.S., extending Coe and Helpman’s (1995) empirical specification to include human capital. We use a new dataset of patents data for the past 150 years to calculate the stock of knowledge using the perpetual inventory method. Our time series empirical analysis confirms the heterogeneous relationship between innovation variables (domestic stock of knowledge, imports of knowledge, and human capital) and productivity. Our results reveal the extent to which observed differences in technology adoption patterns and the levels of endowment of such resources can explain differences in TFP dynamics across countries. The estimated coefficients confirm the considerable gap that still exists between the European countries and the U.S. in innovation-related variables. Furthermore, we obtain a finding that may have important implications for innovation policies: the higher the level of investment in human capital, the higher the level of investment in domestic innovation, and the higher the response of TFP to a 1% increase in any of the aforementioned variablesEste trabajo analiza la relación entre la productividad total de los factores (PTF ) y las variables relacionadas con la innovación durante la segunda mitad del siglo XX . Este análisis se lleva a cabo en varios países europeos (Francia, Alemania, el Reino Unido y España) y en Estados Unidos, ampliando el trabajo de Coe y Helpman (1995) sobre la especificación empírica para incluir el capital humano. Utilizamos un nuevo conjunto de datos de patentes durante los últimos 150 años para calcular el stock de conocimiento mediante el método de inventario permanente. Nuestro análisis empírico con series temporales confirma la relación heterogénea entre las variables de innovación (stock de conocimiento nacional, importaciones de conocimiento y capital humano) y la productividad. Nuestros resultados ponen de manifiesto hasta qué punto las diferencias observadas en los patrones de adopción de tecnología y los niveles de dotación de esos recursos pueden explicar las diferencias en la dinámica de la PTF entre países. Los coeficientes estimados confirman la brecha considerable que aún existe entre los países europeos y EE.UU. en las variables relacionadas con la innovación. Además, se obtiene un hallazgo que puede tener importantes implicaciones para las políticas de innovación: cuanto mayor sea el nivel de inversión en capital humano, mayor es el nivel de inversión en innovación nacional y mayor será la respuesta de la PTF a un aumento del 1 % en alguna de las variables mencionadas previament

The effect of foreign and domestic patents on total factor productivity during the second half of the 20th century

This paper analyses the relationship between total factor productivity (TFP) and innovation-related variables during the second half of the 20th century. We perform this analysis for several European countries (France, Germany, the United Kingdom, and Spain) and the U.S., extending Coe and Helpman’s (1995) empirical specification to include human capital. We use a new dataset of patents data for the past 150 years to calculate the stock of knowledge using the perpetual inventory method. Our time series empirical analysis confirms the heterogeneous relationship between innovation variables (domestic stock of knowledge, imports of knowledge, and human capital) and productivity. Our results reveal the extent to which observed differences in technology adoption patterns and the levels of endowment of such resources can explain differences in TFP dynamics across countries. The estimated coefficients confirm the considerable gap that still exists between the European countries and the U.S. in innovation-related variables. Furthermore, we obtain a finding that may have important implications for innovation policies: the higher the level of investment in human capital, the higher the level of investment in domestic innovation, and the higher the response of TFP to a 1% increase in any of the aforementioned variablesEste trabajo analiza la relación entre la productividad total de los factores (PTF ) y las variables relacionadas con la innovación durante la segunda mitad del siglo XX . Este análisis se lleva a cabo en varios países europeos (Francia, Alemania, el Reino Unido y España) y en Estados Unidos, ampliando el trabajo de Coe y Helpman (1995) sobre la especificación empírica para incluir el capital humano. Utilizamos un nuevo conjunto de datos de patentes durante los últimos 150 años para calcular el stock de conocimiento mediante el método de inventario permanente. Nuestro análisis empírico con series temporales confirma la relación heterogénea entre las variables de innovación (stock de conocimiento nacional, importaciones de conocimiento y capital humano) y la productividad. Nuestros resultados ponen de manifiesto hasta qué punto las diferencias observadas en los patrones de adopción de tecnología y los niveles de dotación de esos recursos pueden explicar las diferencias en la dinámica de la PTF entre países. Los coeficientes estimados confirman la brecha considerable que aún existe entre los países europeos y EE.UU. en las variables relacionadas con la innovación. Además, se obtiene un hallazgo que puede tener importantes implicaciones para las políticas de innovación: cuanto mayor sea el nivel de inversión en capital humano, mayor es el nivel de inversión en innovación nacional y mayor será la respuesta de la PTF a un aumento del 1 % en alguna de las variables mencionadas previament

El coste de uso del capital en la explicación del boom de la inversión europea de posguerra.

Post-war Europe provides an opportunity to study the importance of relative prices of capital, and the user cost of capital in particular, in explaining the convergence in investment rates between countries of similar "social capabilities" and income levels. After Second World War, at time as a new international order was established, European countries experienced a rapid process of income growth and convergence. In the interpretation of this process a prominent role has been attributed to technological progress and "catch-up" to the technological leader, the United States. Investment decisions are the way for embodying new technological progress, but investment takes place only when incentive exists. Among these incentives, recent empirical literature on economic growth highlights the role of relative prices of capital in explaining differences in investment rates and income growth between countries with very different income levels. But when we reduce the sample to countries closed in income levels and "social capabilities", we can demonstrate that, although the relative cost of capital converged over time and could help to explain income convergence, other factors were more significant in explaining the increase in investment rates. More important than the user cost of capital in the investment decision, was general prosperity caused by the demand increase.

Are the HI deficient galaxies on the outskirts of Virgo recent arrivals?

The presence on the Virgo cluster outskirts of spiral galaxies with gas deficiencies as strong as those of the inner galaxies stripped by the intracluster medium has led us to explore the possibility that some of these peripheral objects are not newcomers. A dynamical model for the collapse and rebound of spherical shells under the point mass and radial flow approximations has been developed to account for the amplitude of the motions in the Virgo I cluster (VIC) region. According to our analysis, it is not unfeasible that galaxies far from the cluster, including those in a gas-deficient group well to its background, went through its core a few Gyr ago. The implications would be: (1) that the majority of the HI-deficient spirals in the VIC region might have been deprived of their neutral hydrogen by interactions with the hot intracluster medium; and (2) that objects spending a long time outside the cluster cores might keep the gas deficient status without altering their morphology.Comment: Accepted for publication in ApJ. 4 pages, 3 figures. Uses emulateapj

Series resistance in organic bulk-heterojunction solar devices: Modulating carrier transport with fullerene electron traps

Series resistance is one of the key parameters affecting the performance of organic photovoltaic devices. Several electronic mechanisms arising from different structures within the solar cell can contribute to increasing it. We focus on the series resistance origin by altering the acceptor transport properties trough the incorporation of fullerene traps located at energies below the transporting electron levels. Indene-C60 bisadduct as acceptor molecule blended with poly(3-hexylthiophene) forms the active layer in which small amounts of [6,6]-phenyl-C61-butyric acid methyl ester have been added as trapping sites. A complete analysis of the impedance response has allowed identifying bulk transport resistive circuit elements in the high-frequency part of the spectra. Series resistance is observed to be dependent on the concentration of fullerene traps, thus indicating a connection between bulk transport processes and resistive elements. By comparing different contacts it has been discarded that outer cathode interfaces influence the series resistance experimentally extracted from impedance spectroscopy