109 research outputs found

    Numerical analysis of the stability of the Electrohydrodynamic (EHD) electroconvection between two plates

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    The time evolution of the problem of Electrohydrodynamic (EHD) convection in a liquid between two plates is analysed numerically. The equations are nondimensionalized using the ion drift velocity and the viscous time scales. Following the non-dimensionalisation of the respective model, two different techniques have been used to describe the charge evolution, namely the Finite-Element Flux-Corrected Transport Method and the Particle-In-Cell technique. The results obtained with the two schemes, apart from showing good agreement, have revealed the appearance of a two-roll structure not described in previous works. This is investigated in detail for both strong and weak injection.Ministerio de ciencia y tecnología FQM-42

    IDENTIFICACIÓN DE LA INTERACCIÓN DE MONOCITOS HUMANOS CON LAS LECTINAS DE Olneya tesota (IF2) Y Phaseolus vulgaris (PHA-L) POR CITOMETRÍA DE FLUJO

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    En este estudio se purificaron tres isolectinas (IF1, IF2 e IF3) de la lectina de palo fierro (PF2) a partir de las semillas de Olneya tesota, usando cromatografía de afinidad, seguida de intercambio iónico. La isoforma más abundante de PF2 (IF2) y la lectina de frijol PHA-L se utilizaron para identificar el patrón de reconocimiento hacia células mononucleares de sangre periférica humana por citometría de flujo. Todos los tipos sanguíneos (ABO) presentaron un perfil de reconocimiento similar por las lectinas. En particular, las estructuras oligosacáridas de los monocitos circulantes fueron reconocidas por IF2 y PHA-L con mayor intensidad que el resto de las células. Los linfocitos B y T presentaron una menor interacción con IF2 que con PHA-L. Los receptores carbohidrato de IF2 pudieran ser usados como marcadores potenciales de monocitos en patologías asociadas con estas células

    The Guadiaro-Baños contourite drifts (SW Mediterranean). A geotechnical approach to stability analysis

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    Two Quaternary plastered contourite drifts, with terraced and low-mounded morphologies, make up the continental slope and base-of-slope in the northwestern Alboran Sea, respectively, between the Guadiaro and Baños turbidite systems, close to the Strait of Gibraltar. Considering their significant lateral extent, the link between the contourite drift deposits and landslides may be particularly important for hazard assessment. The physical properties, composition and geometry of contourite drifts have been proposed as key factors in slope stability, although this relationship still needs to be better constrained. In this work, new in-situ geotechnical data (cone penetration tests; CPTu) has been combined with morphostratigraphic, sedimentological, and (laboratory) geotechnical properties to determine the stability of the Guadiaro-Baños drifts. For the depositional domains of both drifts, the resulting sedimentary and geotechnical model describes low-plasticity granular and silty sands on the erosive terraced domain that evolve seawards to silty and silty-clay deposits with a higher plasticity and uniform geomechanical properties. For the shallower coarse-grained contourite sediments, the cohesion (c') and internal friction angle (ϕ') values are 0–9 kPa and 46–30°, respectively, whereas for the distal fine contourites the undrained shear strength gradient (∇Su) is 2 kPa/m. These properties allow us to establish high factors of safety for all the scenarios considered, including seismic loading. Slope failure may be triggered in the unlikely event that there is seismic acceleration of PGA > 0.19, although no potential glide planes have been observed within the first 20 m below the seafloor. This suggests that the contourite drifts studied tend to resist failure better than others with similar sedimentary characteristics. The interplay of several processes is proposed to explain the enhanced undrained shear strength: 1) the geometry of the drifts, defined by an upper contouritic terrace and lower low-mounded shapes; 2) recurrent low-intensity earthquakes with insufficient energy to trigger landslides, favouring increased strength due to dynamic compaction; and 3) cyclic loading induced by solitons/internal waves acting on the sediment.En prens

    Evaluación de la respuesta inmune en lenguado senegalés conferida por una vacuna inactivada frente a Betanodavirus

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    La necrosis nerviosa viral es una enfermedad que afecta a peces cultivados en todo el mundo. Su agente etiológico es el virus de la necrosis nerviosa, género Betanodavirus, familia Nodaviridae, que presenta un genoma compuesto por dos segmentos de RNA monocatenario. Los betanodavirus se clasifican en cuatro especies, Striped Jack-, Tiger puffer-, Redspotted grouper- y Barfin flonder nervous necrosis virus (SJNNV, TPNNV, RGNNV y BFNNV, respectivamente). En el sur de Europa se han descrito recombinantes de los segmentos genómicos de las especies SJNNV y RGNNV como agentes causantes de epizootías en lenguado senegalés y dorada. El control de esta enfermedad es de gran importancia para la acuicultura europea y la vacunación es una de las estrategias más prometedoras. Sin embargo, solo existen vacunas comercializadas contra la especie RGNNV las cuales no protegen frente a los aislados recombinantes, por lo que se ha desarrollado una vacuna inactivada utilizando el aislado recombinante SpSsIAusc160.03 que produce una moderada protección frente a la infección vírica en lenguado (Valero et al., 2021). El objetivo de este estudio es evaluar la capacidad de dicha vacuna de inducir una respuesta inmune eficaz en lenguado (Solea senegalensis). Se tomaron muestras de cerebro y riñón cefálico de lenguados vacunados y sin vacunar a 2, 3 y 7 días post-vacunación (dpv), analizándose la expresión de 106 inmunogenes mediante la plataforma OpenArray® (Gémez et al., 2020). Se detectó una respuesta inmune temprana en muestras de riñón, expresándose diferencialmente 39 y 29 genes a 2 y 3 dpv, respectivamente. Esta modulación fue significativamente menor a 7 dpv, con solo 3 genes expresados diferencialmente (DEG). En muestras de cerebro, tejido diana de la infección, se observó una menor modulación génica, detectándose expresión diferencial exclusivamente a 2 y 3 dpv (5 y 12 DEG, respectivamente). Financiación: Proyecto RTI2018-094687-B-C21/C22 del MICIU cofinanciado por FEDER.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Inhibiting the stringent response blocks Mycobacterium tuberculosis entry into quiescence and reduces persistence

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    The stringent response enables Mycobacterium tuberculosis (Mtb) to shut down its replication and metabolism under various stresses. Here we show that Mtb lacking the stringent response enzyme RelMtb was unable to slow its replication rate during nutrient starvation. Metabolomics analysis revealed that the nutrient-starved relMtb-deficient strain had increased metabolism similar to that of exponentially growing wild-type bacteria in nutrient-rich broth, consistent with an inability to enter quiescence. Deficiency of relMtb increased the susceptibility of mutant bacteria to killing by isoniazid during nutrient starvation and in the lungs of chronically infected mice. We screened a pharmaceutical library of over 2 million compounds for inhibitors of RelMtb and showed that the lead compound X9 was able to directly kill nutrient-starved M. tuberculosis and enhanced the killing activity of isoniazid. Inhibition of RelMtb is a promising approach to target M. tuberculosis persisters, with the potential to shorten the duration of TB treatment.This work was supported by R01AI083125, R21AI122922, and R21AI114507A to P.C.

    Galaxy and mass assembly (GAMA): refining the local galaxy merger rate using morphological information

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    We use the Galaxy And Mass Assembly (GAMA) survey to measure the local Universe mass dependent merger fraction and merger rate using galaxy pairs and the CAS structural method, which identifies highly asymmetric merger candidate galaxies. Our goals are to determine which types of mergers produce highly asymmetrical galaxies, and to provide a new measurement of the local galaxy major merger rate. We examine galaxy pairs at stellar mass limits down to M=108MM_{*} = 10^{8}M_{\odot} with mass ratios of 4:1) the lower mass companion becomes highly asymmetric, while the larger galaxy is much less affected. The fraction of highly asymmetric paired galaxies which have a major merger companion is highest for the most massive galaxies and drops progressively with decreasing mass. We calculate that the mass dependent major merger fraction is fairly constant at 1.32%\sim1.3-2\% between 109.5<M<1011.5M10^{9.5}<M_{*}<10^{11.5} M_{\odot}, and increases to 4%\sim4\% at lower masses. When the observability time scales are taken into consideration, the major merger rate is found to approximately triple over the mass range we consider. The total co-moving volume major merger rate over the range 108.0<M<1011.5M10^{8.0}<M_{*}<10^{11.5} M_{\odot} is (1.2±0.5)×103(1.2 \pm 0.5) \times 10^{-3} h703h^{3}_{70} Mpc3^{-3} Gyr1^{-1}

    Understanding the complex geomorphology of a deep sea area affected by continental tectonic indentation: the case of the Gulf of Vera (Western Mediterranean)

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    We present a multidisciplinary study of morphology, stratigraphy, sedimentology, tectonic structure, and physical oceanography to report that the complex geomorphology of the Palomares continental margin and adjacent Algerian abyssal plain (i.e., Gulf of Vera, Western Mediterranean), is the result of the sedimentary response to the Aguilas Arc continental tectonic indentation in the Eurasian–Africa plate collision. The inden tation is imprinted on the basement of the margin with elongated metamorphic antiforms that are pierced by igneous bodies, and synforms that accommodate the deformation and create a complex physiography. The basement is partially covered by Upper Miocene deposits sealed by the regional Messinian Erosive Surface characterized by palaeocanyons that carve the modern margin. These deposits and outcropping basement highs are then covered and shaped by Plio-Quaternary contourites formed under the action of the Light Intermediate and Dense Deep Mediterranean bottom currents. Even though bottom currents are responsible for the primary sedimentation that shapes the margin, 97% of this region's seafloor is affected by mass-movements that modified contourite sediments by eroding, deforming, faulting, sliding, and depositing sediments. Mass-movement processes have resulted in the formation of recurrent mass-flow deposits, an enlargement of the submarine canyons and gully incisions, and basin-scale gravitational slides spreading above the Messinian Salinity Crisis salt layer. The Polopo, Aguilas and Gata slides are characterized by an extensional upslope domain that shapes the continental margin, and by a downslope contractional domain that shapes the abyssal plain with diapirs piercing (hemi)pelagites/sheet-like turbidites creating a seafloor dotted by numerous crests. The mass movements were mostly triggered by the interplay of the continental tectonic indentation of the Aguilas Arc with sedimentological factors over time. The indentation, which involves the progressively southeastward tectonic tilting of the whole land-sea region, likely generated a quasi-continuous oversteepening of the entire margin, thus reducing the stability of the contourites. In addition, tectonic tilting and subsidence of the abyssal plain favoured the flow of the underlying Messinian Salinity Crisis salt layer, contributing to the gravitational instability of the overlying sediments over large areas of the margin and abyssal plain

    Hidratos de gas marinos: ¿un recurso futuro de gas natural para Europa? M.

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    Los hidratos de gas son compuestos cristalinos donde una molécula de gas, principalmente metano, queda atrapada en una red de moléculas de agua en forma de hielo. La importancia de los hidratos de gas en la naturaleza es muy alta ya que constituye una fuente alternativa de energía y a su vez juegan un papel importante en el delicado equilibrio del clima a nivel global y en los riesgos geológicos en el ámbito marino. La acción COST MIGRATE está diseñada con el fin de integrar la experiencia de un gran número de grupos de investigación europeos y agentes del sector para promover el desarrollo de conocimientos multidisciplinarios sobre el potencial de los hidratos de gas como fuente de energía en Europa. Dos de los objetivos de esta acción son realizar un inventario europeo de hidratos de gas explotables y evaluar los riesgos ambientales. En este trabajo se muestran los principales indicios de hidratos de gas en los márgenes europeos incluida la Península Ibérica, con una primera aproximación sobre el espesor y situación de la zona de estabilidad de hidratos de gas en el margen Ibérico.Gas hydrates are crystalline compounds where a molecule of gas, mainly methane, is trapped in a cage of icewater molecules. The importance of gas hydrates in nature is very high because it is an alternative source of energy and play a major role in the delicate balance of the global climate and in the marine geological risks. MIGRATE COST action is designed to integrate the experience of a large number of European research groups and industrial players to promote the development of multidisciplinary knowledge on the potential of gas hydrates as energy resource in Europe. Two of the objectives of the action aim to estimate the European inventory of exploitable gas hydrates and to assess environmental risks. In this work we show the occurrences of gas hydrates described in European margins including the Iberian Peninsula, with a first approximation on the thickness and location of the area of stability of gas hydrates in the Iberian margin.COST Action ES1405 (MIGRATE)Versión del edito

    Nuevos datos de actividad tectónica durante el Pleistoceno Superior-Holoceno en el sector oriental de la plataforma continental del Golfo de Cádiz (SO de Iberia)

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    La realización de dos campañas de adquisición de datos geofísicos del suelo y subsuelo marino en el año 2010, mediante la utilización de técnicas acústicas de muy alta resolución, ha permitido ampliar el conocimiento de dos sectores de la plataforma continental española en el Golfo de Cádiz, comprendidos entre la desembocadura del río Guadalquivir y la Bahía de Cádiz, y entre Cádiz y Chiclana de la Frontera, respectivamente. En el primero se han localizado varias zonas de fracturas que se caracterizan en los perfiles de sísmica de muy alta resolución por fallas normales de alto ángulo y pequeño salto que desplaza claramente las unidades sedimentarias de edad Holoceno, se trata por tanto de fallas que se pueden considerar activas, si bien deben ser el reflejo en superficie de fallas profundas de mayor entidad. Mientras que en el segundo se ha analizado la morfología asociada a la actividad emergente de una estructura diapirica principal.Two oceanographic surveys have been carried out using very high resolution acoustic techniques in 2010. These surveys have allowed us to improve the knowledge of two sectors of the Spanish continental shelf in the Gulf of Cadiz: the first one, from the mouth of the Guadalquivir River to the Bay of Cadiz, and the second one, between Cadiz and Chiclana de la Frontera. In the first sector, we have located several fracture zones which are characterized in the seismic profiles as high angle normal faults of small vertical displacement. These faults displace clearly the Holocene sedimentary units. Therefore, these faults could be considered currently actives, although should be the surface expression of deeper and more significance faults. In the second sector, we have analyzed the associated morphology with the emerging activity of a main diapi
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