El ciclo de la materia en el medio interestellar : procesamiento energético del polvo y el hielo

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Ciencias Físicas, leída el 05-05-2017El objetivo de esta tesis doctoral es el de profundizar en el conocimiento de los procesos que tienen lugar en el medio interestelar (MI) relacionados con el procesamiento energético de granos de polvo interestelares y los mantos de hielo que los recubren, y en particular, de los procesos de desorción inducida por fotones de las moléculas del hielo en las regiones frías del MI que son necesarios para explicar las abundancias de ciertas especies observadas en la fase gaseosa. En astrofísica no sólo se utilizan las observaciones astronómicas, sino que también se usan simulaciones experimentales en condiciones relevantes para la astrofísica y simulaciones teóricas para complementar la información obtenida a través de las observaciones y conseguir así un mejor entendimiento de los procesos que ocurren en el espacio en general y el MI en particular. Los resultados presentados en esta tesis han sido obtenidos combinando estas tres metodologías, aunque la astrofísica de laboratorio ha tenido un peso mayor. Tras los capítulos de introducción, en el capítulo 5 se presenta el estudio experimental del procesamiento por fotones UV de partículas análogas a los granos de polvo carbonáceos que se encuentran en el MI, a distintas temperaturas. La irradiación produce la formación de moléculas de H2 que luego difunden a través de las partículas y pasan a la fase gaseosa. Este proceso está controlado por el coeficiente de difusión, cuya dependencia con la temperatura fue el objeto de estudio, obteniéndose una energía de activación de 1660 K. Es en la superficie de estos granos de polvo donde se forman los mantos de hielo en las regiones más frías y más densas del MI. En el capítulo 6 se demuestra que las condiciones en las que se forman los hielos de CO afectan a las energías de enlace entre las moléculas, y por tanto a la morfología de los mismos. Sin embargo, las diferencias se desvanecen cuando los hielos son calentados. Los capítulos 7 -10 están dedicados al procesamiento con fotones UV de los mantos de hielo, prestando especial atención a los procesos de desorción inducidos por los fotones, que constituyen el núcleo de la tesis. En el capítulo 8 se estudia la irradiación de un hielo puro de CO2. Gracias a la combinación del espectrómetro IR (que observa la composición del hielo) y el cuadrupolo de masas (que monitoriza el gas) se pudo obtener una cuantificación completa de los procesos fotoquímicos y de fotodesorción. En los capítulos 9 y 10 se usaron un hielo puro de etanol, y una mezcla binaria rica en agua con moléculas de metano, más realista para explorar la posible formación (a temperaturas muy bajas en torno a 8 K) y la consiguiente desorción de moléculas de metanol y otras especies relacionadas. La formación de metanol sólo se produjo durante la irradiación de la mezcla binaria, pero no se detectó su fotodesorción. A pesar de todo se observó que la fotodesorción de otros fotoproductos puede seguir dos patrones distintos a medida que aumenta el tiempo de irradiación, según el mecanismo a través del es inducida la fotodesorción...The aim of this PhD thesis is to expand our knowledge of particular processes taking place in the interstellar medium (ISM). These processes are related in one way or another to the energetic processing of the interstellar dust grains and the ice mantles on top of them, and to the interplay between the solid and the gaseous phases of the ISM. In particular, photon-induced desorption processes of ice molecules in cold regions of the ISM are needed to explain the observed gas-phase abundances of several species. It is therefore a paradigmatic case of the interaction between the two phases of the ISM, and its importance is nowadays beyond any doubt. The core of this thesis (Part IV) is devoted to the study of such processes. Astrophysics is no longer about observations only. Both experimental simulations under astrophysically relevant conditions, and theoretical models are used to complement the observations and get a better understanding of the processes that are taking place in space and the ISM in particular. The results presented in this thesis have been obtained using a combination of these three methodologies, although more attention is paid to laboratory astrophysics. Parts III (Chapter 5 and IV (Chapters 6 - 11) deal with experimental simulations carried out in a high-vacuum (HV) and an ultra-high-vacuum (UHV) chambers. These chambers have base pressures slightly over (in the case of the HV) or similar (UHV) to those found in the densest regions of the ISM. A closed-cycle helium cryostat is used in both cases to reach the temperatures typically found in the cold and warm ISM (below 100 K, and as low as 10 K in the densest and coldest regions). Under these conditions, dust or ice analogs can be grown onto a substrate in order to simulate the energetic processing (photoprocessing in most chapters, but also thermal processing) of the solid component of the ISM...Fac. de Ciencias FísicasTRUEunpu

MICA-BBVA: A factor model of economic and financial indicators for short-term GDP forecasting

In this paper we extend the Stock and Watson's (Leading economic indicators, new approaches and forecasting records, 1991) single-index dynamic factor model in an econometric framework that has the advantage of combining information from real and financial indicators published at different frequencies and delays with respect to the period to which they refer. We find that the common factor reflects the behavior of the Spanish business cycle well.We also show that financial indicators are useful for forecasting output growth, particularly when certain financial variables lead the common factor. Finally, we provide a simulated real-time exercise and prove that the model is a very useful tool for the short-term analysis of the Spanish Economy

Vacuum ultraviolet photolysis of hydrogenated amorphous carbons. III. Diffusion of photo-produced H2 as a function of temperature

Hydrogenated amorphous carbon (a-C:H) has been proposed as one of the carbonaceous solids detected in the interstellar medium. Energetic processing of the a-C:H particles leads to the dissociation of the C-H bonds and the formation of hydrogen molecules and small hydrocarbons. Photo-produced H2 molecules in the bulk of the dust particles can diffuse out to the gas phase and contribute to the total H2 abundance. We have simulated this process in the laboratory with plasma-produced a-C:H and a-C:D analogs under astrophysically relevant conditions to investigate the dependence of the diffusion as a function of temperature. Plasma-produced a-C:H analogs were UV-irradiated using a microwave-discharged hydrogen flow lamp. Molecules diffusing to the gas-phase were detected by a quadrupole mass spectrometer, providing a measurement of the outgoing H2 or D2 flux. By comparing the experimental measurements with the expected flux from a one-dimensional diffusion model, a diffusion coefficient D could be derived for experiments carried out at different temperatures. Dependance on the diffusion coefficient D with the temperature followed an Arrhenius-type equation. The activation energy for the diffusion process was estimated (ED(H2)=1660+-110 K, ED(D2)=2090+-90 K), as well as the pre-exponential factor (D0(H2)=0.0007+0.0013-0.0004 cm2 s-1, D0(D2)=0.0045+0.005-0.0023 cm2 s-1) The strong decrease of the diffusion coefficient at low dust particle temperatures exponentially increases the diffusion times in astrophysical environments. Therefore, transient dust heating by cosmic rays needs to be invoked for the release of the photo- produced H2 molecules in cold PDR regions, where destruction of the aliphatic component in hydrogenated amorphous carbons most probably takes place

Creative industries in Spain: a first view

La creatividad es la habilidad de generar algo nuevo, de combinar\ud datos, percepciones y materiales para producir cosas nuevas y útiles. El 22% de la población ocupada española forma parte de la llamada «clase creativa» y el 5,7% de la producción española tiene su origen en las «industrias creativas». A pesar de estos datos, los estudios generalistas relacionados con la economía creativa en España son escasos. El objetivo del artículo es cubrir una parte de este vacío y ofrecer una visión panorámica de la economía de la creatividad en España, focalizada sobre una de sus partes, las llamadas «industrias creativas». El artículo introduce los aspectos teóricos básicos, la medición de la creatividad, los datos comparados sobre producción,\ud ocupación y localización de las industrias creativas, y el debate de políticas.Creativity is the ability to generate something new, merging data,\ud perceptions and matters in order to produce new and useful things. About 22% of the Spanish employees belong to the «creative class» and about 5.7% of the production comes from the «creative industries». Despite these data, the general research focusing on the creative economy in Spain is poor. The aim of this article is to fill\ud this space by providing a general view of the creative economy in Spain, focused on the «creative industries». The article introduces the basic theoretical aspects, the measurement of creativity, compared data about production, employment and the location of creative industries, as well as the discussion about policy

Service regulations, input prices and export volumes : evidence from a panel of manufacturing firms

Utilizando datos de panel, este trabajo muestra que una mejor regulación en el sector servicios reduce el precio de los consumos intermedios que soportan las empresas de manufacturas, especialmente aquellas de mayor tamaño. El beneficio de un marco regulatorio que fomenta la competencia en el sector servicios se extiende a los mercados internacionales. Entre 1991 y 2007, las reformas en servicios habrían permitido a las grandes compañías industriales españolas incrementar sus exportaciones reales de bienes alrededor de un 22 % en términos acumulados, a lo largo de este período, frente a un hipotético escenario sin reformas. Más aun, si se hubiera producido la convergencia en materia regulatoria al marco de mejores prácticas en 2007, el volumen de exportación de las grandes empresas hubiera sido un 10 % superior, en términos acumulados, frente al valor observado. No obstante, no se observa evidencia robusta de este efecto en el caso de las pymes. El estudio muestra que el tamaño de la empresa es relevante para estudiar el vínculo que existe entre las reformas regulatorias, los precios de los consumos intermedios y el volumen de exportaciónUsing a panel of firm-level data from Spanish manufacturers, this study shows that better service regulation reduces the price of intermediate inputs paid by downstream firms. The beneficial cost effects of services reforms extend to both large and small-to-medium sized corporations (SMEs), but the former tend to enjoy greater gains. This feature also manifests itself in international markets. We identify an input cost channel through which service regulations affect the volume of exports of large manufacturers, while the evidence of such channel is weaker for SMEs. Our estimates indicate that, from 1991 till 2007, large firms increased their volume of exports by an average of 22% as a result of the direct input cost effect of services reforms, such that the firms that benefited the most typically belonged to industries more dependent on service inputs. Furthermore, convergence to the “best practice” regulatory framework in services would have raised exports at least by an additional 10%. We conclude that firm size is relevant for the connection between services reforms, intermediate input prices and export volume

Innovative business groups: territory-based industrial policy in Spain

On the last decades, European countries have increased their focus on local production systems as a matter of industrial policy measures. Based on the works related to industrial districts of Becatini (1989), Brusco (1990), Ybarra (1991 and 1996) and Dei Ottati (1994), or the later contributions of Porter (1998a) about productive clusters, Governments have taken measures to stimulate the creation and strengthening of clusters. However, the progressive extension of cluster policies has highlighted the constraints of rationality on which it is based and the criteria used to evaluate their impact and effectiveness. Consequently, the traditional arguments based on the neoclassical concept of efficiency and the advantages of external economies have given way to a new paradigm that gives a central role to organizational learning, collective decision-making and networks as governance structure. The new approach to the analysis of production networks exceeds the territorial or sectorial boundaries to highlight the dynamic and complex nature of the relationships established between actors in the cluster. The approach of governance, as a starting point for the analysis of production networks, opens a new perspective in the assessment of the potential impact of cluster development and the effectiveness of measures aimed to their promotion. Based on the theoretical premises above mentioned, this paper aims to the analysis and valuation of the aid scheme of Innovative Business Partnerships (AEI) sponsored by the Spanish government. This study is based both on traditional analysis of the implementation and impact indicators, as in the analysis of the AEI program's ability to promote the adoption of models of governance and collective action to enhance the competitive capabilities of the cluster

Inferencia en modelos dinámicos uniecuacionales con variables integradas

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A two-parameter design storm for Mediterranean convective rainfall

[EN] The following research explores the feasibility of building effective design storms for extreme hydrological regimes, such as the one which characterizes the rainfall regime of the east and south-east of the Iberian Peninsula, without employing intensity-duration-frequency (IDF) curves as a starting point. Nowadays, after decades of functioning hydrological automatic networks, there is an abundance of high-resolution rainfall data with a reasonable statistic representation, which enable the direct research of temporal patterns and inner structures of rainfall events at a given geographic location, with the aim of establishing a statistical synthesis directly based on those observed patterns. The authors propose a temporal design storm defined in analytical terms, through a two-parameter gamma-type function. The two parameters are directly estimated from 73 independent storms identified from rainfall records of high temporal resolution in Valencia (Spain). All the relevant analytical properties derived from that function are developed in order to use this storm in real applications. In particular, in order to assign a probability to the design storm (return period), an auxiliary variable combining maximum intensity and total cumulated rainfall is introduced. As a result, for a given return period, a set of three storms with different duration, depth and peak intensity are defined. The consistency of the results is verified by means of comparison with the classic method of alternating blocks based on an IDF curve, for the above mentioned study case.This work was supported by the Regional Government of Valencia (Generalitat Valenciana, Conselleria d'Educacio, Investigacio, Cultura i Esport) through the project "Formulacion de un hietograma sintetico con reproduccion de las relaciones de dependencia entre variables de evento y de la estructura interna espacio-temporal" (reference GV/2015/064).García Bartual, RL.; Andrés Doménech, I. (2017). A two-parameter design storm for Mediterranean convective rainfall. HYDROLOGY AND EARTH SYSTEM SCIENCES. 21(5):2377-2387. https://doi.org/10.5194/hess-21-2377-2017S23772387215Adams, B. J. and Howard, C. D. D.: Design Storm Pathology, Can. Water Resour. J., 11, 49–55, https://doi.org/10.4296/cwrj1103049, 1986.Alfieri, L., Laio, F., and Claps, P.: A simulation experiment for optimal design hyetograph selection, Hydrol. Process., 22, 813–820, https://doi.org/10.1002/hyp.6646, 2008.Andrés-Doménech, I., Montanari, A., and Marco, J. B.: Stochastic rainfall analysis for storm tank performance evaluation, Hydrol. Earth Syst. Sci., 14, 1221–1232, https://doi.org/10.5194/hess-14-1221-2010, 2010.Andrés-Doménech, I., García-Bartual, R., Rico Cortés, M., and Albentosa Hernández, E.: A Gaussian design-storm for Mediterranean convective events. Sustainable Hydraulics in the Era of Global Change, edited by: Erpicum, S., Dewals, B., Archambeau, P., and Pirotton, M., Taylor & Francis, London, ISBN 978-1-138-02977-4, 2016.Ball, J. E.: The influence of storm temporal patterns on catchment response, J. Hydrol., 158, 285–303, 1994.Barnolas, M., Rigo, T., and Llasat, M. C.: Characteristics of 2-D convective structures in Catalonia (NE Spain): an analysis using radar data and GIS, Hydrol. Earth Syst. Sci., 14, 129–139, https://doi.org/10.5194/hess-14-129-2010, 2010.Bonta, J. V. and Rao, R.: Factors affecting the identification of independent storm events, J. Hydrol., 98, 275–293, 1988.Brummer, J.: Rainfall events as paths of a stochastic process: Problems of design storm analysis, Water Sci. Technol., 16, 131–138, 1984.Capsoni, C., Luini, L., Paraboni, A., Riva, C., and Martellucci A.: A new prediction model of rain attenuation that separately accounts for stratiform and convective rain, IEEE T. Antenn. Propag., 57, 196–204, 2009.Chow, V. T., Maidment, D. R., and Mays, L. W.: Applied hydrology, Mc Graw-Hill, New York, 1988.De Luca, D. L.: Analysis and modelling of rainfall fields at different resolutions in southern Italy, Hydrolog. Sci. J., 59, 1536–1558, https://doi.org/10.1080/02626667.2014.926013, 2014.Di Baldassarre, G., Brath, A., and Montanari, A.: Reliability of different depth-duration-frequency equations for estimating short-duration design storms, Water Resour. Res., 42, W12501, https://doi.org/10.1029/2006WR004911, 2006.Dunkerley, D.: Identifying individual rain events from pluviography records: a review with analysis of data from an Australian dryland site, Hydrol. Process., 22, 5024–5036, 2008.Frances, F., García-Bartual, R., and Bussi, G.: High return period annual maximum reservoir water level quantiles estimation using synthetic generated flood events, in: “Risk Analysis, Dam Safety, Dam Security and Critical Infrastructure Management”, Taylor and Francis, ISBN 978-0-415-62078-9, 185–190, 2012.French, R. and Jones, M.: Design rainfall temporal patterns in Australian Rainfall and Runoff: Durations exceeding one hour, Australian Journal of Water Resources, 16, 21–27, 2012.Froehlich, D. C.: Mathematical formulations of NRCS 24-hour design storms, J. Irrig. Drain E.-ASCE, 135, 241–247, https://doi.org/10.1061/(ASCE)0733-9437(2009)135:2(241), 2009.García-Bartual, R. and Marco, J.: A stochastic model of the internal structure of convective precipitation in time at a raingauge site, J. Hydrol., 118, 129–142, https://doi.org/10.1016/0022-1694(90)90254-U, 1990.García-Bartual, R. and Schneider, M.: Estimating maximum expected short-duration rainfall intensities from extreme convective storms, Phys. Chem. Earth Pt. B, 26, 675–681, https://doi.org/10.1016/S1464-1909(01)00068-5, 2001.Hicks, W. I.: A method of computing urban runoff, T. Am. Soc. Civ. Eng., 109, 1217–1253, 1944.Hogg, W. D.: Time distribution of short duration rainfall in Canada, in: Proceedings Canadian Hydrology Symposium, 80, Ottawa, Ontario, 53–63, 1980.Hogg, W. D.: Distribution of design rainfall with time: design considerations. American Geophysical Union Chapman on Rainfall Rates, Urbana, Illinois, 27–29 April 1982.Hoppe, H.: Impact of input data uncertainties on urban drainage models: climate change – a crucial issue? In Proceedings of the 11th International Conference on Urban Drainage, Edinburgh, UK, 31 August–5 September, 10 pp., 2008.Huff, F. A.: Time distribution of rainfall in heavy storms, Water Resour. Res., 3, 1007–1019, https://doi.org/10.1029/WR003i004p01007, 1967.Huff, F. A. and Angel, J. R.: Rainfall Distributions and Hydroclimatic Characteristics of Heavy Rainstorms in Illinois (Bulletin 70), Illinois State Water Survey, 1989.Keifer, C. J. and Chu, H. H.: Synthetic storm pattern for drainage design, J. Hydraul. Eng-ASCE, 83, 1–25, 1957.Kuichling, E.: The relation between rainfall and the discharge in sewers in populous districts, T. Am. Soc. Civ. Eng., 20, 37–40, 1889.Llasat, M. C.: . An objective classification of rainfall events on the basis of their convective features: application to rainfall intensity in the northeast of Spain, Int. J. Climatol., 21, 1385–1400, 2001.McCuen, R. H.: Hydrologic analysis and design, Prentice-Hall, Englewood Cliffs, N. J., 1989.McPherson, M. B.: Urban runoff control planning, EPA-600/9-78-035, Environmental Protection Agency, Washington D.C., 1978.Northrop, P. J. and Stone, T. M.: A point process model for rainfall with truncated gaussian rain cells. Research Report No. 251, Department of Statistical Science, University College London, 2005.Packman, J. C. and Kidd, C. H. R.: A logical approach to the design storm concept, Water Resour. Res., 16, 994–1000, https://doi.org/10.1029/WR016i006p00994, 1980.Pilgrim, D. H.: Australian rainfall and runoff, a guide to flood estimation. The Institution of Engineers, ACT, Australia, 1987.Pilgrim, D. H. and Cordery, I.: Rainfall temporal patterns for design floods, J. Hydr. Eng. Div.-ASCE, 101, 81–95, 1975.Restrepo-Posada, P. J. and Eagleson, P. S.: Identification of independent rainstorms, J. Hydrol., 55, 303–319, 1982.Rigo, T. and Llasat, M. C.: Radar analysis of the life cycle of Mesoscale Convective Systems during the 10 June 2000 event, Nat. Hazards Earth Syst. Sci., 5, 959–970, https://doi.org/10.5194/nhess-5-959-2005, 2005.Salsón, S. and Garcia-Bartual, R.: A space-time rainfall generator for highly convective Mediterranean rainstorms, Nat. Hazards Earth Syst. Sci., 3, 103–114, https://doi.org/10.5194/nhess-3-103-2003, 2003.Témez, J.: Cálculo Hidrometeorológico de caudales máximos en pequeñas cuencas naturales, Dirección General de Carreteras, Madrid, España, 1978.Vaskova, I.: Cálculo de las curvas IDF mediante la incorporación de las propiedades de escala y de dependencia temporales, PhD Thesis, Universitat Politècnica de València, 2001 (in Spanish).Walesh, S. G., Lau, D. H., and Liebman, M. D.: Statistically based use of event models. Proceedings of the International Symposium on Urban Storm Runoff, University of Kentucky, Lexington, 75–81, 1979.Watt, E. and Marsalek, J.: Critical review of the evolution of design storm event concept, Can. J. Civil. Eng., 40, 105–113, https://doi.org/10.1139/cjce-2011-0594, 2013

Convergencia real y envejecimiento: retos y propuestas

España se enfrenta en las próximas décadas a dos grandes retos económicos y sociales: completar el proceso de convergencia en renta y bienestar con los países de nuestro entorno y asegurar la sostenibilidad del Estado del bienestar en un contexto demográfico desfavorable. La superación de estos retos exigirá reformas en muchos ámbitos para cuya implementación sería muy deseable contar con un amplio consenso político y social. Tras examinar la situación actual de la economía española y su evolución durante las últimas décadas desde una perspectiva comparada con la OCDE, en el presente trabajo se examinan las reformas necesarias en tres ámbitos que consideramos cruciales: educación, mercados de trabajo y de bienes y servicios, y sistema de pensiones.

El impacto sobre el gasto de la reforma de las pensiones: una primera estimación

En este trabajo se presenta una primera estimación del impacto de la reforma del sistema de pensiones acordada por el Gobierno y los agentes sociales en enero de 2011. Tras actualizar las proyecciones de gasto en pensiones realizadas por de la Fuente y Doménech (2009) para el período 2008-60, se analiza el impacto sobre esta variable de la elevación de la edad de jubilación hasta los 67 años, la ampliación del período de cómputo de las pensiones y el aumento en el número de años de cotización necesarios para alcanzar el 100% de la base reguladora. Condicionados a los supuestos realizados sobre la evolución del empleo, la productividad y la demografía, los resultados sugieren que estas medidas tendrán un impacto apreciable sobre el gasto en pensiones, con un ahorro que ascenderá a dos puntos de PIB al final del período transitorio en 2027. No obstante, dadas las incertidumbres existentes sobre la evolución futura de muchas de las variables que afectan a los resultados, sería deseable adelantar la introducción del llamado factor de sostenibilidad al inicio de la reforma, de forma que exista un mecanismo claro para modular el ritmo y el alcance de las reformas previstas si así lo exige la situación financiera del sistema antes del final del período transitorio.