295 research outputs found

    Redescription of Aorolaimus capsici Jiménez Millan, Arias & Fijo, 1964 (Nematoda : Tylenchida)

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    La redescription d'#Aorolaimus capsici Jiménez Millan, Arias & Fijo, 1964 et une étude comparative du matériel type de cette espèce et de trois populations d'#A. perscitus (Doucet, 1980) Fortuner, 1987 ont été réalisées. Les faibles différences morphométriques montrées par les populations étudiées ne justifiant pas l'existence de deux espèces, il est proposé de considérer #A. persicus comme un synonyme mineur d'#A. capsici. (Résumé d'auteur

    El Neógeno del Empordà y Baix Ebre (CAtalunya): estudio comparativo

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    The Neogene infill of the Empordà and Baix Ebre basins was undifferentiated up to now. In Empordhthere are five sedimentary systems and in Baix Ebre six lithostratigraphic units are distinguished. In the Empordà, Esponellà conglomerates are continental diposits of Upper Miocene (Turolian) and coastal sediments are Tortonian (GEOT-1 borehole). Pliocene sedimentation shows a similarity in both basins. In the Empordà basin deltaic (Avinyonet, Vilamalla, etc.) and bay environments (Siurana marls) are dominant, while littoral (Lower Marine Detrital Unit) and bay (Campredó marls) environrnents appear in the Baix Ebre. The Pliocene series culminate withlacustrine-aliuvial facies (Sant Onofre limestone and Roca Corba conglomerate units) in the Baix Ebre basin and with alluvial facies (Sant Climent-Perelada and Cistelia systems) in the Empordà basin. We propose a similarity between Siurana and Campredó marls, and we consider it as a guide leve1 in the catalonian marine pliocene

    Mathematical modelling of the restenosis process after stent implantation

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    The stenting procedure has evolved to become a highly successful technique for the clinical treatment of advanced atherosclerotic lesions in arteries. However, the development of in-stent restenosis remains a key problem. In this work, a novel two-dimensional continuum mathematical model is proposed to describe the complex restenosis process following the insertion of a stent into a coronary artery. The biological species considered to play a key role in restenosis development are growth factors, matrix metalloproteinases, extracellular matrix, smooth muscle cells and endothelial cells. Diffusion–reaction equations are used for modelling the mass balance between species in the arterial wall. Experimental data from the literature have been used in order to estimate model parameters. Moreover, a sensitivity analysis has been performed to study the impact of varying the parameters of the model on the evolution of the biological species. The results demonstrate that this computational model qualitatively captures the key characteristics of the lesion growth and the healing process within an artery subjected to non-physiological mechanical forces. Our results suggest that the arterial wall response is driven by the damage area, smooth muscle cell proliferation and the collagen turnover among other factors

    Effects of Randomness on the Field-Induced Phase Transition in the S=1 Bond-Alternating Spin Chain NTENP

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    We report novel effects of randomness in the S=1 bond-alternating antiferromagnetic chain compound with a dimer-singlet ground state [Ni(N,N'-bis(3-aminopropyl)propane-1,3-diamine(mu-NO2]ClO4 abbreviated as NTENP. The 15N NMR spectra develop a continuum with sharply peaked edges at low temperatures, indicating an inhomogeneous staggered magnetization induced by magnetic field. We attribute this to random anisotropic interactions due to disorder of NO2 groups in the chains. The field-induced antiferromagnetic transition exhibits remarkably anisotropic behavior. We propose that a field-induced incoherent magnetization is transformed into a coherent antiferromagnetic moment with spatially fluctuating amplitude.Comment: 4pages, 5 figues, submitted to J. Phys. Soc. Jp

    Single-Ion Anisotropy and Intramolecular Interactions in CeIIIand NdIIIDimers

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    [Image: see text] This article reports the syntheses, characterization, structural description, together with magnetic and spectroscopic properties of two isostructural molecular magnets based on the chiral ligand N,N′-bis((1,2-diphenyl-(pyridine-2-yl)methylene)-(R,R/S,S)-ethane-1,2-diamine), L1, of general formula [Ln(2)(RR-L1)(2)(Cl(6))]·MeOH·1.5H(2)O, (Ln = Ce (1) or Nd (2)). Multifrequency electron paramagnetic resonance (EPR), cantilever torque magnetometry (CTM) measurements, and ab initio calculations allowed us to determine single-ion magnetic anisotropy and intramolecular magnetic interactions in both compounds, evidencing a more important role of the anisotropic exchange for the Nd(III) derivative. The comparison of experimental and theoretical data indicates that, in the case of largely rhombic lanthanide ions, ab initio calculations can fail in determining the orientation of the weakest components, while being reliable in determining their principal values. However, they remain of paramount importance to set the analysis of EPR and CTM on sound basis, thus obtaining a very precise picture of the magnetic interactions in these systems. Finally, the electronic structure of the two complexes, as obtained by this approach, is consistent with the absence of zero-field slow relaxation observed in ac susceptibility

    Host Range of Meloidogyne Arenaria (NEAL, 1889) Chitwood, 1949 (Nematoda: Meloidogynidae) in Spain

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    11 páginas, ilustraciones y tablas estadísticas.The distribution of Meloidogyne arenaria in Spain was revised and new samples collected from representative areas. Species and races of the populations were determined by morphometrics, differential host tests and SCAR-PCR. Meloidogyne arenaria was found most often in warm areas, but it can occur in Northern Spain in greenhouses. A total of 125 citations were found, corresponding to 45 different host plants, of which 41 new reports (32.8%) are from this study. The populations studied belong to race 2, which reproduces on tomato plants carrying the Mi gene, or race 3, which reproduces on both resistant pepper and tomato. The most frequent hosts were vegetables, fruit trees, tobacco, grapevine, and weeds.INIA OT- 03-006C7-4 and RTA2007-00099-C00-00; Castilla La Mancha PAI09-0010-4701, INCRECYT CICyT CTM2006-07309.Peer reviewe

    Smelling in the dark: Phylogenomic insights into the chemosensory system of a subterranean beetle

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    The chemosensory system has experienced relevant changes in subterranean animals, facilitating the perception of specific chemical signals critical to survival in their particular environment. However, the genomic basis of chemoreception in cave-dwelling fauna has been largely unexplored. We generated de novo transcriptomes for antennae and body samples of the troglobitic beetle Speonomus longicornis (whose characters suggest an extreme adaptation to a deep subterranean environment) in order to investigate the evolutionary origin and diversification of the chemosensory gene repertoire across coleopterans through a phylogenomic approach. Our results suggested a diminished diversity of odourant and gustatory gene repertoires compared to polyphagous beetles that inhabit surface habitats. Moreover, S. longicornis showed a large diversity of odourant-binding proteins, suggesting an important role of these proteins in capturing airborne chemical cues. We identified a gene duplication of the ionotropic coreceptor IR25a, a highly conserved single-copy gene in protostomes involved in thermal and humidity sensing. In addition, no homologous genes to sugar receptors or the ionotropic receptor IR41a were detected. Our findings suggest that the chemosensory gene repertoire of this cave beetle may result from adaptation to the highly specific ecological niche it occupies, and that gene duplication and loss may have played an important role in the evolution of gene families involved in chemoreception. Altogether, our results shed light on the genomic basis of chemoreception in a cave-dwelling invertebrate and pave the road towards understanding the genomic underpinnings of adaptation to the subterranean lifestyle at a deeper level

    Aplicación del Modelo Delta: La Terminal

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    El estudio se va a desarrollar siguiendo el manual “El Modelo Delta y su modelo Triangular” realizado por los autores Arnoldo C. Hax y Dean L. Wilde II del MIT (Massachusetts).Se ha elegido la empresa La Terminal, incubadora/aceleradora municipal gestionada por Hiberus Tecnología con el apoyo estratégico de Fundación Ibercaja.El trabajo se estructura primordialmente en tres grandes módulos. En el primer módulo se realiza una síntesis de los fundamentos teóricos a través e los mayores exponentes que han trabajado en la materia en cuestión. En el segundo módulo, se realiza una aplicación práctica, en la que se estudian algunos de los clientes principales de La Terminal y se estudian siguiendo el modelo triangular, situándolos dentro del triangulo y explicando la relación, el “bonding”, que existe entre la empresa y el cliente. Por último, en el tercer módulo, se recogen las principales conclusiones que se han obtenido en el estudio de la estrategia seguida por La Terminal.<br /

    A Ferromagnetic Salicylaldoximate/Azide MnII2MnIII6 Cluster with an S = 17 Ground State and a Single-Molecule-Magnet Response

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    One new MnII 2MnIII 6 cluster exhibiting an S = 17 spin ground state and single-molecule-magnet properties has been designed linking MnIII 3-salicylaldoximate triangles and tetracoordinated MnII cations by means of end-on azido bridges. The ferromagnetic coupling has been rationalized as a function of their structural parameters

    Nuclear Spin-Lattice Relaxation in One-Dimensional Heisenberg Ferrimagnets: Three-Magnon versus Raman Processes

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    Nuclear spin-lattice relaxation in one-dimensional Heisenberg ferrimagnets is studied by means of a modified spin-wave theory. We consider the second-order process, where a nuclear spin flip induces virtual spin waves which are then scattered thermally via the four-magnon exchange interaction, as well as the first-order process, where a nuclear spin directly interacts with spin waves via the hyperfine interaction. We point out a possibility of the three-magnon relaxation process predominating over the Raman one and suggest model experiments.Comment: to be published in J. Phys. Soc. Jpn. 73, No. 6 (2004
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