56 resultados para C–C reversible bond
em Consorci de Serveis Universitaris de Catalunya (CSUC), Spain
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This manuscript reports the study of the carbon-halide bond cleavage in 4-nitrobenzyl halides, taking special attention to the iodide and fluoride derivatives. The electrochemical reduction mechanism has been disclosed for both compounds by terms of cyclic voltammetry and controlled potential electrolysis. In the case of 4-nitrobenzyl iodide, a first one electron irreversible wave leads to the corresponding 4-nitrobenzyl radical and iodide. However, in the case of 4-nitrobenzyl fluoride, a first one-electron reversible wave appears at –1.02 vs. SCE followed by one electron irreversible wave. In this second electron transfer process, the cleavage of the C-F bond is taking place, so the bond cleavage reaction occurs at the dianion level. To disclose and understand the electrochemical reduction mechanisms that allows to obtain important thermodynamic and kinetic data that would help in the understanding of C-X bond cleavage. This type of bond dissociation reactions are involved in the metabolism pathways of the human body.
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This paper measures the connectedness in EMU sovereign market volatility between April 1999 and January 2014, in order to monitor stress transmission and to identify episodes of intensive spillovers from one country to the others. To this end, we first perform a static and dynamic analysis to measure the total volatility connectedness in the entire period (the system-wide approach) using a framework recently proposed by Diebold and Yılmaz (2014). Second, we make use of a dynamic analysis to evaluate the net directional connectedness for each country and apply panel model techniques to investigate its determinants. Finally, to gain further insights, we examine the timevarying behaviour of net pair-wise directional connectedness at different stages of the recent sovereign debt crisis.
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We analyse volatility spillovers in EMU sovereign bond markets. First, we examine the unconditional patterns during the full sample (April 1999-January 2014) using a measure recently proposed by Diebold and Yılmaz (2012). Second, we make use of a dynamic analysis to evaluate net directional volatility spillovers for each of the eleven countries under study, and to determine whether core and peripheral markets present differences. Finally, we apply a panel analysis to empirically investigate the determinants of net directional spillovers of this kind.
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"Vegeu el resum a l'inici del document del fitxer adjunt."
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Report for the scientific sojourn at the Research Institute for Applied Mathematics and Cybernetics, Nizhny Novgorod, Russia, from July to September 2006. Within the project, bifurcations of orbit behavior in area-preserving and reversible maps with a homoclinic tangency were studied. Finitely smooth normal forms for such maps near saddle fixed points were constructed and it was shown that they coincide in the main order with the analytical Birkhoff-Moser normal form. Bifurcations of single-round periodic orbits for two-dimensional symplectic maps close to a map with a quadratic homoclinic tangency were studied. The existence of one- and two-parameter cascades of elliptic periodic orbits was proved.
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We analyse the implications of optimal taxation for the stochastic behaviour of debt. We show that when a government pursues an optimal fiscal policy under complete markets, the value of debt has the same or less persistence than other variables in the economy and it declines in response to shocks that cause the deficit to increase. By contrast, under incomplete markets debt shows more persistence than other variables and it increases in response to shocks that cause a higher deficit. Data for US government debt reveals diametrically opposite results from those of complete markets and is much more supportive of bond market incompleteness.
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Abstract: We scrutinize the realized stock-bond correlation based upon high frequency returns. We use quantile regressions to pin down the systematic variation of the extreme tails over their economic determinants. The correlation dependence behaves differently when the correlation is large negative and large positive. The important explanatory variables at the extreme low quantile are the short rate, the yield spread, and the volatility index. At the extreme high quantile the bond market liquidity is also important. The empirical fi ndings are only partially robust to using less precise measures of the stock-bond correlation. The results are not caused by the recent financial crisis. Keywords: Extreme returns; Financial crisis; Realized stock-bond correlation; Quantile regressions; VIX. JEL Classifi cations: C22; G01; G11; G12
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Abstract: We analyze the realized stock-bond correlation. Gradual transitions between negative and positive stock-bond correlation is accommodated by the smooth transition regression (STR) model. The changes in regime are de ned by economic and financial transition variables. Both in sample and out-of- sample results document that STR models with multiple transition variables outperform STR models with a single transition variable. The most important transition variables are the short rate, the yield spread, and the VIX volatility index. Keywords: realized correlation; smooth transition regressions; stock-bond correlation; VIX index JEL Classifi cations: C22; G11; G12; G17
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Report for the scientific sojourn at the the Philipps-Universität Marburg, Germany, from september to december 2007. For the first, we employed the Energy-Decomposition Analysis (EDA) to investigate aromaticity on Fischer carbenes as it is related through all the reaction mechanisms studied in my PhD thesis. This powerful tool, compared with other well-known aromaticity indices in the literature like NICS, is useful not only for quantitative results but also to measure the degree of conjugation or hyperconjugation in molecules. Our results showed for the annelated benzenoid systems studied here, that electron density is more concentrated on the outer rings than in the central one. The strain-induced bond localization plays a major role as a driven force to keep the more substituted ring as the less aromatic. The discussion presented in this work was contrasted at different levels of theory to calibrate the method and ensure the consistency of our results. We think these conclusions can also be extended to arene chemistry for explaining aromaticity and regioselectivity reactions found in those systems.In the second work, we have employed the Turbomole program package and density-functionals of the best performance in the state of art, to explore reaction mechanisms in the noble gas chemistry. Particularly, we were interested in compounds of the form H--Ng--Ng--F (where Ng (Noble Gas) = Ar, Kr and Xe) and we investigated the relative stability of these species. Our quantum chemical calculations predict that the dixenon compound HXeXeF has an activation barrier for decomposition of 11 kcal/mol which should be large enough to identify the molecule in a low-temperature matrix. The other noble gases present lower activation barriers and therefore are more labile and difficult to be observable systems experimentally.
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El projecte comporta l'anàlisi i la creació d'una nova versió del lloc web de la secció sindical de Comissions Obreres (CCOO) del Grup Banc Sabadell partint d'un disseny centrat en l'usuari.
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En el marc de les accions que està portant a terme la Biblioteca de la Universidad Complutense de Madrid per promocionar l'ús del " Archivo institucional de E-Prints Complutense" entre els seus professors i investigadors, la Biblioteca de la Facultat de Ciències Geològiques de la UCM ha posat en marxa una iniciativa, recolzada pels Serveis Centrals de la BUCM, destinada a dipositar a l'arxiu institucional de la universitat la producció científica de la Facultat. L'aspecte clau d'aquesta iniciativa consisteix a emfatitzar el pes institucional i patrimonial de la producció investigadora d'una institució i en demanar el suport de l'equip deganal del centre perquè sigui ell qui comuniqui als seus investigadors l'oportunitat de dipositar tot aquest patrimoni, fent-lo més visible i augmentant amb això el seu impacte, en el dipòsit que a l'efecte ha creat la universitat. La Biblioteca de la Facultat de Ciències Geològiques de la UCM està procedint, en conseqüència, a dipositar a l'arxiu institucional de la universitat tots aquells resultats de recerca del centre que, dins del respecte a la legalitat, sigui possible introduir sense que, fins al present, investigador algun d'aquest centre s'hagi manifestat contrari a la proposta deganal.
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La present memòria descriu processos d'electroisomerització en compostos fotocròmics, [2.2]metaciclofans i naptopirans. Els estudis electroquímics i espectroelectroquímics mostren la formació d'enllaços C-C i C-O pels [2.2]metaciclofans i naptopirans, respectivament.
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El proyecto de Registro Automatizado de Incidencias tiene como objeto el desarrollo de un software que permita realizar el procedimiento de notificación, gestión y respuesta ante las incidencias. Se considerarán como "incidencias de seguridad", entre otras, cualquier incumplimiento de la normativa desarrollada en el Documento de Seguridad, así como a cualquier anomalía que afecte o pueda afectar a la seguridad de los datos de carácter personal.