1,255 research outputs found

    Structure of Madrid basin (NE zone) derived from gravity data

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    [Abstract] Modelling of five profiles in the NE area of Madrid Basin shows that low anomalies are related to both the thicker sediments infill of the Basin and the basement rocks like gneiss and granites. The highs are related to thick sequences ofalternating slates and quarzites, outcropping or underlaying a thin cover. The main gradients are related to the marginal faults of the Basin. The existence of a granitic body and a NE-SW striking fault, was also detected. Out of the data obtained in the models, an isobaths map has been depicted of Madrid Basin which shows a fault bounded structure

    Fast ferrous heme-NO oxidation in nitric oxide synthases.

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    International audienceDuring catalysis, the heme in nitric oxide synthase (NOS) binds NO before releasing it to the environment. Oxidation of the NOS ferrous heme-NO complex by O2 is key for catalytic cycling, but the mechanism is unclear. We utilized stopped-flow methods to study the reaction of O2 with ferrous heme-NO complexes of inducible and neuronal NOS enzymes. We found that the reaction does not involve heme-NO dissociation, but instead proceeds by a rapid direct reaction of O2 with the ferrous heme-NO complex. This behavior is novel and may distinguish heme-thiolate enzymes, such as NOS, from related heme proteins

    Stability of the hard-sphere icosahedral quasilattice

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    The stability of the hard-sphere icosahedral quasilattice is analyzed using the differential formulation of the generalized effective liquid approximation. We find that the icosahedral quasilattice is metastable with respect to the hard-sphere crystal structures. Our results agree with recent findings by McCarley and Ashcroft [Phys. Rev. B {\bf 49}, 15600 (1994)] carried out using the modified weighted density approximation.Comment: 15 pages, 2 figures available from authors upon request, (revtex), submitted to Phys. Rev.

    Coherent and non-coherent processing of multiband radar sensor data

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    Increasing resolution is an attractive goal for all types of radar sensor applications. Obtaining high radar resolution is strongly related to the signal bandwidth which can be used. The currently available frequency bands however, restrict the available bandwidth and consequently the achievable range resolution. As nowadays more sensors become available e.g. on automotive platforms, methods of combining sensor information stemming from sensors operating in different and not necessarily overlapping frequency bands are of concern. It will be shown that it is possible to derive benefit from perceiving the same radar scenery with two or more sensors in distinct frequency bands. Beyond ordinary sensor fusion methods, radar information can be combined more effectively if one compensates for the lack of mutual coherence, thus taking advantage of phase information. <P> At high frequencies, complex scatterers can be approximately modeled as a group of single scattering centers with constant delay and slowly varying amplitude, i.e. a set of complex exponentials buried in noise. The eigenanalysis algorithms are well known for their capability to better resolve complex exponentials as compared to the classical spectral analysis methods. These methods exploit the statistical properties of those signals to estimate their frequencies. Here, two main approaches to extend the statistical analysis for the case of data collected at two different subbands are presented. One method relies on the use of the band gap information (and therefore, coherent data collection is needed) and achieves an increased resolution capability compared with the single-band case. On the other hand, the second approach does not use the band gap information and represents a robust way to process radar data collected with incoherent sensors. Combining the information obtained with these two approaches a robust estimator of the target locations with increased resolution can be built

    Open charm meson in nuclear matter at finite temperature beyond the zero range approximation

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    The properties of open charm mesons, DD, Dˉ\bar D, DsD_s and Dˉs\bar D_s in nuclear matter at finite temperature are studied within a self-consistent coupled-channel approach. The interaction of the low lying pseudoscalar mesons with the ground state baryons in the charm sector is derived from a tt-channel vector-exchange model. The in-medium scattering amplitudes are obtained by solving the Lippmann-Schwinger equation at finite temperature including Pauli blocking effects, as well as DD, Dˉ\bar D, DsD_s and Dˉs\bar D_s self-energies taking their mutual influence into account. We find that the in-medium properties of the DD meson are affected by the DsD_s-meson self-energy through the intermediate DsYD_s Y loops coupled to DNDN states. Similarly, dressing the Dˉ\bar{D} meson in the DˉY\bar{D}Y loops has an influence over the properties of the Dˉs\bar{D}_s meson.Comment: 23 pages, 9 figures, 2 table

    Étale Covers and Fundamental Groups of Schematic Finite Spaces

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    [EN] We introduce the category of finite étale covers of an arbitraryschematic space X and show that, equipped with an appropriate naturalfiber functor, it is a Galois Category. This allows us to define the étale fundamental group of schematic spaces. If X is a finite model of a schemeS, we show that the resulting Galois theory on X coincides with theclassical theory of finite étale covers on S, and therefore, we recover the classical étale fundamental group introduced by Grothendieck. Toprove these results, it is crucial to find a suitable geometric notion ofconnectedness for schematic spaces and also to study their geometric points. We achieve these goals by means of the strong cohomologicalconstraints enjoyed by schematic spaces.Publicación en abierto financiada por el Consorcio de Bibliotecas Universitarias de Castilla y León (BUCLE), con cargo al Programa Operativo 2014ES16RFOP009 FEDER 2014-2020 DE CASTILLA Y LEÓN, Actuación:20007-CL - Apoyo Consorcio BUCLE
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