733 research outputs found

    Möglichkeiten verstärkter Nord-Süd-Technologiekooperation im Klimaregime: Studie auf Grundlage einer Analyse für das Bundesministerium für Umwelt, Naturschutz und Reaktorsicherheit im Rahmen des Projekts Wirtschaftliche Chancen der internationalen Klimapolitik

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    Dieses Papier gibt einen Überblick über die verschiedenen Formen der Technologiekooperation und prüft ihre Verwendbarkeit für die internationalen post-2012-Klimaverhandlungen. Es plädiert für einen umfassenden Ansatz unter Einbeziehung aller Elemente, also des gemeinsamen RD&D, der gemeinsamen Standardsetzung und der Finanzierung neuer Technologien. Die Vor- und Nachteile eines separaten Technologieprotokolls werden abgewogen - wobei die Nachteile überwiegen. Abschließend wird, unter Verweis auf die Verhandlungen in Bali, die Gründung einer Technologieallianz für Klimaschutz mit den Entwicklungs- und insbesondere den Schwellenländern empfohlen. Dies würde die post-2012-Verhandlungen entscheidend voranbringen, die diplomatische und technologische Zusammenarbeit mit den aufstrebenden Schwellenländern stärken und die Führungsrolle der Europäischen Union in der Klimapolitik - aber nicht nur dort - festigen. -- This paper provides an overview on the different forms of inter-governmental technology cooperation and examines their usefulness for the international climate negotiations post-2012. It advocates a comprehensive approach including all elements, i.e. common research and development, common setting of standards, technology transfer and financing of new technologies. The pros and cons of a separate technology protocol are evaluated: in the end, it is only a second-best option. Finally, taking the negotiations in Bali as a starting point, the paper envisions a technology alliance for climate protection with the developing countries - especially the emerging economies. This would significantly boost the post-2012 negotiations, strengthen diplomatic and technological cooperation and consolidate the European Union's leading role in climate politics - and other policy fields.

    Results from the CERN pilot CLOUD experiment

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    During a 4-week run in October–November 2006, a pilot experiment was performed at the CERN Proton Synchrotron in preparation for the Cosmics Leaving OUtdoor Droplets (CLOUD) experiment, whose aim is to study the possible influence of cosmic rays on clouds. The purpose of the pilot experiment was firstly to carry out exploratory measurements of the effect of ionising particle radiation on aerosol formation from trace H2SO4 vapour and secondly to provide technical input for the CLOUD design. A total of 44 nucleation bursts were produced and recorded, with formation rates of particles above the 3 nm detection threshold of between 0.1 and 100 cm -3 s -1, and growth rates between 2 and 37 nm h -1. The corresponding H2O concentrations were typically around 106 cm -3 or less. The experimentally-measured formation rates and htwosofour concentrations are comparable to those found in the atmosphere, supporting the idea that sulphuric acid is involved in the nucleation of atmospheric aerosols. However, sulphuric acid alone is not able to explain the observed rapid growth rates, which suggests the presence of additional trace vapours in the aerosol chamber, whose identity is unknown. By analysing the charged fraction, a few of the aerosol bursts appear to have a contribution from ion-induced nucleation and ion-ion recombination to form neutral clusters. Some indications were also found for the accelerator beam timing and intensity to influence the aerosol particle formation rate at the highest experimental SO2 concentrations of 6 ppb, although none was found at lower concentrations. Overall, the exploratory measurements provide suggestive evidence for ion-induced nucleation or ion-ion recombination as sources of aerosol particles. However in order to quantify the conditions under which ion processes become significant, improvements are needed in controlling the experimental variables and in the reproducibility of the experiments. Finally, concerning technical aspects, the most important lessons for the CLOUD design include the stringent requirement of internal cleanliness of the aerosol chamber, as well as maintenance of extremely stable temperatures (variations below 0.1 °C

    André Gide II

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    La restauración de la razón

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    Monte Carlo Methods for Estimating Interfacial Free Energies and Line Tensions

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    Excess contributions to the free energy due to interfaces occur for many problems encountered in the statistical physics of condensed matter when coexistence between different phases is possible (e.g. wetting phenomena, nucleation, crystal growth, etc.). This article reviews two methods to estimate both interfacial free energies and line tensions by Monte Carlo simulations of simple models, (e.g. the Ising model, a symmetrical binary Lennard-Jones fluid exhibiting a miscibility gap, and a simple Lennard-Jones fluid). One method is based on thermodynamic integration. This method is useful to study flat and inclined interfaces for Ising lattices, allowing also the estimation of line tensions of three-phase contact lines, when the interfaces meet walls (where "surface fields" may act). A generalization to off-lattice systems is described as well. The second method is based on the sampling of the order parameter distribution of the system throughout the two-phase coexistence region of the model. Both the interface free energies of flat interfaces and of (spherical or cylindrical) droplets (or bubbles) can be estimated, including also systems with walls, where sphere-cap shaped wall-attached droplets occur. The curvature-dependence of the interfacial free energy is discussed, and estimates for the line tensions are compared to results from the thermodynamic integration method. Basic limitations of all these methods are critically discussed, and an outlook on other approaches is given

    Un juicio acerca de José Ortega y Gasset

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    Experimental particle formation rates spanning tropospheric sulfuric acid and ammonia abundances, ion production rates, and temperatures

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    Binary nucleation of sulfuric acid and water as well as ternary nucleation involving ammonia are thought to be the dominant processes responsible for new particle formation (NPF) in the cold temperatures of the middle and upper troposphere. Ions are also thought to be important for particle nucleation in these regions. However, global models presently lack experimentally measured NPF rates under controlled laboratory conditions and so at present must rely on theoretical or empirical parameterizations. Here with data obtained in the European Organization for Nuclear Research CLOUD (Cosmics Leaving OUtdoor Droplets) chamber, we present the first experimental survey of NPF rates spanning free tropospheric conditions. The conditions during nucleation cover a temperature range from 208 to 298K, sulfuric acid concentrations between 5x10(5) and 1x10(9)cm(-3), and ammonia mixing ratios from zero added ammonia, i.e., nominally pure binary, to a maximum of -1400 parts per trillion by volume (pptv). We performed nucleation studies under pure neutral conditions with zero ions being present in the chamber and at ionization rates of up to 75ion pairs cm(-3)s(-1) to study neutral and ion-induced nucleation. We found that the contribution from ion-induced nucleation is small at temperatures between 208 and 248K when ammonia is present at several pptv or higher. However, the presence of charges significantly enhances the nucleation rates, especially at 248K with zero added ammonia, and for higher temperatures independent of NH3 levels. We compare these experimental data with calculated cluster formation rates from the Atmospheric Cluster Dynamics Code with cluster evaporation rates obtained from quantum chemistry.Peer reviewe
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