9,575 research outputs found

    Making Sustainable Agriculture Real in CAP 2020: The Role of Conservation Agriculture

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    Europe is about to redefine its Common Agriculture Policy (CAP) for the near future. The question is whether this redefinition is more a fine-tuning of the existing CAP or whether thorough changes can be expected. Looking back to the last revision of CAP the most notable change is, undoubtedly, the concern about EU and global food security. The revival of the interest in agricultural production already became evident during the Health Check as a consequence of climbing commodity prices in 2007/08. It is therefore no surprise that “rising concerns regarding both EU and global food security” is the first topic to appear in the list of justifications for the need for a CAP reform. Other challenges mentioned in this list such as sustainable management of natural resources, climate change and its mitigation, improvement of competitiveness to withstand globalization and rising price volatility, etc., while not new are considered worthwhile enough to be maintained and reappraised

    Analysis of the quark sector in the 2HDM-III with a four-zero Yukawa texture using the most recent data on the CKM matrix

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    In this letter we analyse, in the context of the general 2-Higgs Doublet Model, the structure of the Yukawa matrices, Y~1,2q\widetilde{ \bf Y}_{ _{1,2} }^{q}, by assuming a four-zero texture ansatz for their definition. In this framework, we obtain compact expressions for Y~1,2q\widetilde{ \bf Y}_{ _{1,2} }^{q}, which are reduced to the Cheng and Sher ansatz with the difference that they are obtained naturally as a direct consequence of the invariants of the fermion mass matrices. Furthermore, in order to avoid large flavour violating effects coming from charged Higgs exchange, we consider the main flavour constraints on the off-diagonal terms of Yukawa texture {{(χ~jq)kl\left( \widetilde{\chi}_{j}^q \right)_{kl}}} (klk\neq l). We perform a χ2\chi^2-fit based on current experimental data on the quark masses and the Cabibbo-Kobayashi-Maskawa mixing matrix VCKM{ \bf V}_{\rm CKM }. Hence, we obtain the allowed ranges for the parameters Y~1,2q\widetilde{ \bf Y}_{ _{1,2} }^{q} at 1σ\sigma for several values of tanβ\tan \beta. The results are in complete agreement with the bounds obtained taking into account constraints on Flavour Changing Neutral Currents reported in the literature.Comment: 12 pages, 1 figure. Version accepted in Phys. Lett.

    Census of HII regions in NGC 6754 derived with MUSE: Constraints on the metal mixing scale

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    We present a study of the HII regions in the galaxy NGC 6754 from a two pointing mosaic comprising 197,637 individual spectra, using Integral Field Spectrocopy (IFS) recently acquired with the MUSE instrument during its Science Verification program. The data cover the entire galaxy out to ~2 effective radii (re ), sampling its morphological structures with unprecedented spatial resolution for a wide-field IFU. A complete census of the H ii regions limited by the atmospheric seeing conditions was derived, comprising 396 individual ionized sources. This is one of the largest and most complete catalogue of H ii regions with spectroscopic information in a single galaxy. We use this catalogue to derive the radial abundance gradient in this SBb galaxy, finding a negative gradient with a slope consistent with the characteristic value for disk galaxies recently reported. The large number of H ii regions allow us to estimate the typical mixing scale-length (rmix ~0.4 re ), which sets strong constraints on the proposed mechanisms for metal mixing in disk galaxies, like radial movements associated with bars and spiral arms, when comparing with simulations. We found evidence for an azimuthal variation of the oxygen abundance, that may be related with the radial migration. These results illustrate the unique capabilities of MUSE for the study of the enrichment mechanisms in Local Universe galaxies.Comment: 13 pages, 7 Figurs, accepted for publishing in A&

    Chemical abundances of stars with brown-dwarf companions

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    It is well-known that stars with giant planets are on average more metal-rich than stars without giant planets, whereas stars with detected low-mass planets do not need to be metal-rich. With the aim of studying the weak boundary that separates giant planets and brown dwarfs (BDs) and their formation mechanism, we analyze the spectra of a sample of stars with already confirmed BD companions both by radial velocity and astrometry. We employ standard and automatic tools to perform an EW-based analysis and to derive chemical abundances from CORALIE spectra of stars with BD companions. We compare these abundances with those of stars without detected planets and with low-mass and giant-mass planets. We find that stars with BDs do not have metallicities and chemical abundances similar to those of giant-planet hosts but they resemble the composition of stars with low-mass planets. The distribution of mean abundances of α\alpha-elements and iron peak elements of stars with BDs exhibit a peak at about solar abundance whereas for stars with low-mass and high-mass planets the [Xα_\alpha/H] and [XFe_{\rm Fe}/H] peak abundances remain at 0.1\sim -0.1~dex and +0.15\sim +0.15~dex, respectively. We display these element abundances for stars with low-mass and high-mass planets, and BDs versus the minimum mass, mCsinim_C \sin i, of the most-massive substellar companion in each system, and we find a maximum in α\alpha-element as well as Fe-peak abundances at mCsini1.35±0.20m_C \sin i \sim 1.35\pm 0.20 jupiter masses. We discuss the implication of these results in the context of the formation scenario of BDs in comparison with that of giant planets.Comment: Accepted for publication in Astronomy & Astrophysic

    Effect on hatchability of length of time for turning eggs during the incubation in Red-legged partridge (Alectoris rufa)

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    El volteo de los huevos en la incubación artificial es clave para lograr buenas tasas de eclosión y pollos viables. En la producción de perdiz roja (Alectoris rufa) la duración recomendada para el periodo durante el que los huevos deben ser volteados en la incubación no se ha comprobado experimentalmente. Para contribuir al conocimiento de la duración óptima del periodo de volteo, se incubaron 74 huevos divididos en tres grupos: huevos volteados hasta el día 18 ó 19, volteados hasta el día 20 ó 21 y volteados hasta el día 22 de incubación. La tasa de eclosión fue mayor en los huevos volteados durante 20 días o másTurning of the eggs during the artificial incubation is critical in order to obtain a good hatchability and viable one-day-old chicks. In Red-legged partridge (Alectoris rufa) farming, the recommended length of time during which the eggs should be turned along the incubation process has not been experimentally tested. With the aim of improving knowledge on the optimum length of time for the eggs to be turned during the incubation, seventy four eggs were incubated, divided into three groups: eggs that were turned until day 18 or 19, eggs that were turned until day 20 or 21, and eggs that were turned until day 22 of incubation. The hatchability of the eggs was higher for the eggs that were turned during the incubation over at least 20 days

    Chiral transition-metal complexes as Brønsted-acid catalysts for the asymmetric Friedel-Crafts hydroxyalkylation of indoles.

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    The Friedel-Crafts reaction between 3,3,3-trifluoropyruvates and indoles is efficiently catalysed by the iridium complex [(η5-C 5Me5)Ir{(R)-Prophos}(H2O)][SbF 6]2 (1) with up to 84% ee. Experimental data and theoretical calculations support a mechanism involving the Brønsted-acid activation of the pyruvate carbonyl by the protons of the coordinated water molecule in 1. Water is not dissociated during the process and, therefore, the catalytic reaction occurs with no direct interaction between the substrates and the metal. This journal is © the Partner Organisations 2014.The authors acknowledge the Ministerio de Economía y Competitividad (MINECO, Grants CTQ2006-03030/BQU, CTQ2009-10303/BQU, CTQ2011-27033 and Consolider Ingenio 2010 CSD2006-003), Gobierno de Aragón (Grupo Consolidado: Catálisis Homogénea Enantioselectiva), Generalitat de Catalunya (2009SGR0259) and the ICIQ foundation for financial support. A. S. and R. R. acknowledge MINECO for predoctoral fellowships. S. D.-G. acknowledges MINECO for a “Torres Quevedo” contract.Peer Reviewe

    Estudio farmacológico de la acción sináptica del bretilio y de su posible mecanismo de acción

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    [spa] Con la realización de esta Tesis, nos proponemos ampliar el estudio del mecanismo de acción del bretilio y puesto que no se han descrito para este fármaco acciones postsinápticas adrenérgicas, pensamos que sería una herramienta farmacológica adecuada que contribuiría a ampliar el conocimiento de los procesos fisiológicos que tienen lugar en la porción presináptica de la terminación adrenérgica. Los trabajos iniciales sobre bretilio (Boura y Green, 1965) demostraron que esta substancia interfiere la liberación del mediador adrenérgico, pero sin disminuir el contenido en catecolaminas de los depósitos en la terminación adrenérgica. Por otra parte, se ha postulado que el bretilio, al igual que los derivados guanetidínicos, actúa inicialmente como simpaticomimético indirecto, liberando catecolaminas de las terminaciones adrenérgicas. Corroboran esta hipótesis las experiencias de Boura y cols. (1960) que demostraron que el bretilio se acumula selectivamente en las neuronas simpáticas

    Photoelectrochemical characterization of anatase-rutile mixed TiO2 nanosponges

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    This work studies the influence of using hydrodynamic conditions during anodization on the morphology and electrochemical properties of anatase/rutile mixed TiO2 nanotubes (Reynolds number, Re = 0) and nanosponges (Re > 0). To this purpose different techniques were used, such as: microscopy techniques (Field-Emission Scanning Electron Microscope, FE-SEM, and Confocal Laser-Raman Spectroscopy), Electrochemical Impedance Spectroscopy (EIS), Mott Schottky (MS) analysis and photoelectrochemical water splitting tests. This investigation demonstrates that the morphology of TiO2 nanostructures may be greatly affected due to the hydrodynamic conditions and it can be adjusted in order to increase the efficiency for energy and environmental applications
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