3,637 research outputs found

    Sobre los experimentos de creación de vida de Andrew Crosse

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    Uno de los personajes más exitosos y conocidos de la historia de la literatura y el cine de ficción es el creado por la escritora Mary Shelley en 1817 en su libro "Frankenstein o el moderno Prometeo". Paradójicamente, uno de los científicos menos conocidos y más misteriosos de la historia de la ciencia británica es Andrew Crosse, el individuo real en el que, según se suele afirmar, Mary Shelley basó su historia(Haining, 1979). Durante los trabajos de documentación científica de la exposición “CRISTALES: UN MUNDO POR DESCUBRIR” hemos topado con varios artículos sobre este experto en electrocristalización que protagonizó uno de los episodios más controvertidos de la historia de la ciencia del siglo XIX, cuando se dieron a conocer sus experimentos sobre creación de vida en el laboratorio. Los enigmáticos experimentos que dieron lugar a la polémica son muy similares desde el punto de vista químico a los experimentos conocidos como jardines químicos. En este trabajo discuto esta propuesta y su relevancia en el contexto histórico de las investigaciones sobre creación de vida.European Research Council dentro del European Union's Seventh Framework Programme (FP7/2007-2013)/ERC grant agreement nº 340863Peer reviewe

    Identifying microbial life in rocks: Insights from population morphometry

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    The identification of cellular life in the rock record is problematic, since microbial life forms, and particularly bacteria, lack sufficient morphologic complexity to be effectively distinguished from certain abiogenic features in rocks. Examples include organic pore-fillings, hydrocarbon-containing fluid inclusions, organic coatings on exfoliated crystals and biomimetic mineral aggregates (biomorphs). This has led to the interpretation and re-interpretation of individual microstructures in the rock record. The morphologic description of entire populations of microstructures, however, may provide support for distinguishing between preserved micro-organisms and abiogenic objects. Here, we present a statistical approach based on quantitative morphological description of populations of microstructures. Images of modern microbial populations were compared to images of two relevant types of abiogenic microstructures: interstitial spaces and silica–carbonate biomorphs. For the populations of these three systems, the size, circularity, and solidity of individual particles were calculated. Subsequently, the mean/SD, skewness, and kurtosis of the statistical distributions of these parameters were established. This allowed the qualitative and quantitative comparison of distributions in these three systems. In addition, the fractal dimension and lacunarity of the populations were determined. In total, 11 parameters, independent of absolute size or shape, were used to characterize each population of microstructures. Using discriminant analysis with parameter subsets, it was found that size and shape distributions are typically sufficient to discriminate populations of biologic and abiogenic microstructures. Analysis of ancient, yet unambiguously biologic, samples (1.0 Ga Angmaat Formation, Baffin Island, Canada) suggests that taphonomic effects can alter morphometric characteristics and complicate image analysis; therefore, a wider range of microfossil assemblages should be studied in the future before automated analyses can be developed. In general, however, it is clear from our results that there is great potential for morphometric descriptions of populations in the context of life recognition in rocks, either on Earth or on extraterrestrial bodies.This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 Research and Innovation Program (grant agreement no. 646894 to MVZ) and under the ERC Seventh Framework Programme FP7/2007- 2013 (grant agreement no. 340863 to JMG-R). JMG-R also acknowledges the Ministerio de Economía y Competitividad of Spain through the project CGL2016-78971-P. We are grateful to seven anonymous reviewers for their helpful comments. We thank four anonymous reviewers for their useful comments which greatly improved a previous version of the manuscript. This is IPGP contribution n°4098

    Localized Crystallization of Calcium Phosphates by Light- Induced Processes

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    Medical treatment options for bones and teeth can be significantly enhanced by taking control over the crystallization of biomaterials like hydroxyapatite in the healing process. Light-induced techniques are particularly interesting for this approach as they offer tremendous accuracy in spatial resolution. However, in the field of calcium phosphates, lightinduced crystallization has not been investigated so far. Here, proof of principle is established to successfully induce carbonate-hydroxyapatite precipitation by light irradiation. Phosphoric acid is released by a photolabile molecule exclusively after irradiation, combining with calcium ions to form a calcium phosphate in the crystallization medium. 4-Nitrophenylphosphate (4NPP) is established as the photolabile molecule and the system is optimized and fully characterized. A calcium phosphate is crystallized exclusively by irradiation in aqueous solution and identified as carbonate apatite. Control over the localization and stabilization of the carbonate apatite is achieved by a pulsed laser, triggering precipitation in calcium and 4NPP-containing gel matrices. The results of this communication open up a wide range of new opportunities, both in the field of chemistry for more sophisticated reaction control in localized crystallization processes and in the field of medicine for enhanced treatment of calcium phosphate containing biomaterials.European Research Council for funding project 101069348 – INPATTOpen Access funding enabled and organized by Projekt DEA

    Privacy-Preserving Reengineering of Model-View-Controller Application Architectures Using Linked Data

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    When a legacy system’s software architecture cannot be redesigned, implementing additional privacy requirements is often complex, unreliable and costly to maintain. This paper presents a privacy-by-design approach to reengineer web applications as linked data-enabled and implement access control and privacy preservation properties. The method is based on the knowledge of the application architecture, which for the Web of data is commonly designed on the basis of a model-view-controller pattern. Whereas wrapping techniques commonly used to link data of web applications duplicate the security source code, the new approach allows for the controlled disclosure of an application’s data, while preserving non-functional properties such as privacy preservation. The solution has been implemented and compared with existing linked data frameworks in terms of reliability, maintainability and complexity

    Do trade and financial linkages foster business cycle synchronization in a small economy?

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    We estimate a system of equations to analyze whether bilateral trade and financial linkages influence business cycle synchronization directly and/or indirectly. Our paper builds upon the existing literature by using bilateral trade and financial flows for a small, open economy (Spain) as benchmark for the results, instead of the US as generally done in the literature. We find that both the similarity of productive structure and trade links promote the synchronization of cycles. However, bilateral financial links are inversely related to the co movement of output. This might point to financial integration allowing an easiertransfer of resources between two economies, which could enable their decoupling, as predicted by a standard model of international business cycles. Both the effects of trade and financial links on output synchronization are statistically significant and economically relevan

    Teoría del crecimiento de cristales en geles : precipitación polimórfica y agregados cristalinos de morfología inducida

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    Tesis presentada en la Universidad Complutense de Madrid, Facultad de Ciencias Geológicas, leída el día 21 de julio de 1980.ProQuestDepto. de Mineralogía y PetrologíaFac. de Ciencias GeológicasTRUEpu

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