2,389 research outputs found

    ¿La felicidad del niño tendrá que ver con la salud del adolescente?

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    Vesicular Tubular Clusters between the ER and Golgi Mediate Concentration of Soluble Secretory Proteins by Exclusion from COPI-Coated Vesicles

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    AbstractWe have determined the concentrations of the secretory proteins amylase and chymotrypsinogen and the membrane proteins KDELr and rBet1 in COPII- and COPI-coated pre-Golgi compartments of pancreatic cells by quantitative immunoelectron microscopy. COPII was confined to ER membrane buds and adjacent vesicles. COPI occurred on vesicular tubular clusters (VTCs), Golgi cisternae, the trans-Golgi network, and immature secretory granules. Both secretory proteins exhibited a first, significant concentration step in noncoated segments of VTC tubules and were excluded from COPI-coated tips. By contrast, KDELr and rBet1 showed a first, significant concentration in COPII-coated ER buds and vesicles and were prominently present in COPI-coated tips of VTC tubules. These data suggest an important role of VTCs in soluble cargo concentration by exclusion from COPI-coated domains

    Floquet stability analysis of a two-layer oscillatory flow near a flexible wall

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    We investigate the linear Floquet stability of two fluid layers undergoing oscillations in the direction parallel to the flexible wall that separates them. This canonical configuration is inspired by the cerebrospinal fluid flow in the spinal canal of subjects with hydromyelia/syringomyelia. The analysis focuses on the marginal conditions for the onset of instability, and how these depend on the spatial wavelength of the perturbation, and on the values of the control parameters, which are the two channel widths, the Reynolds number and the wall stiffness. Unstable perturbations are found to oscillate synchronous with the base flow. The wavelength of the most unstable perturbation, of the order of the stroke length of the basic oscillatory motion, depends strongly on the wall stiffness, but is only weakly influenced by the channel widths and the Reynolds number. In general, around criticality, it was found that increasing the Reynolds number has a destabilizing effect, and that decreasing the canal widths stabilizes the instability. The wall stiffness on the other hand has a non-monotonic effect, exhibiting an intermediate value for which the instability is maximally amplified. The present analysis is a first step towards a better understanding of the physical mechanisms that govern many (bio)fluid mechanical problems that involve oscillatory flows near compliant walls.Coordinated project, PID2020-115961RB-C31, PID2020-115961RBC32 and PID2020-115961RA-C33, financed by MCIN/AEI/10.13039/501100011033Junta de Andalucía and European Funds, project no. P18-FR-4619Funding for open access charge provided by Universidad de Granad

    Phase Transitions in Two-Dimensional Traffic Flow Models

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    We introduce two simple two-dimensional lattice models to study traffic flow in cities. We have found that a few basic elements give rise to the characteristic phase diagram of a first-order phase transition from a freely moving phase to a jammed state, with a critical point. The jammed phase presents new transitions corresponding to structural transformations of the jam. We discuss their relevance in the infinite size limit.Comment: RevTeX 3.0 file. Figures available upon request to e-address [email protected] (or 'dopico' or 'molera' or 'anxo', same node

    Sistema compacto, híbrido e integrado GAMMA/RF para la formación de imágenes simultáneas PETSPECT/MR

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    Sistema compacto, híbrido e integrado GAMMA/RF para la formación de imágenes simultáneas PET-SPECT/MR. El sistema compacto, híbrido e integrado GAMMA-RF para la formación de imágenes simultáneas PET-SPECT/MR de la invención comprende un dispositivo GAMMA-RF que integra una bobina RF, del tipo empleado en sistemas MR convencionales, con unos módulos detectores de radiación GAMMA del tipo utilizado en sistemas PET o SPECT, de modo que se obtienen imágenes combinadas de las técnicas PET o SPECT y MR.Peer reviewedConsejo Superior de Investigaciones Científicas (España), Universidad de Valencia, Universidad Politécnica de Valencia, General Equipment for Medical Imaging SA, Exploraciones Radiológicas Especiales SA (ERESA)A1 Solicitud de patente con informe sobre el estado de la técnic

    Stability of Liquid Bridges between Equal Disks in an Axial Gravity Field

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    The stability of axisymmetric liquid bridges spanning two equal-diameter solid disks subjected to an axial gravity field of arbitrary intensity is analyzed for all possible liquid volumes. The boundary of the stability region for axisymmetric shapes (considering both axisymmetric and nonaxisymmetric perturbations) have been calculated. It is found that, for sufficiently small Bond numbers, three different unstable modes can appear. If the volume of liquid is decreased from that of an initially stable axisymmetric configuration the bridge either develops an axisymmetric instability (breaking in two drops as already known) or detaches its interface from the disk edges (if the length is smaller than a critical value depending on contact angle), whereas if the volume is increased the unstable mode consists of a nonaxisymmetric deformation. This kind of nonaxisymmetric deformation can also appear by decreasing the volume if the Bond number is large enough. A comparison with other previous partial theoretical analyses is presented, as well as with available experimental results

    Rectification of electronic heat current by a hybrid thermal diode

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    We report the realization of an ultra-efficient low-temperature hybrid heat current rectifier, thermal counterpart of the well-known electric diode. Our design is based on a tunnel junction between two different elements: a normal metal and a superconducting island. Electronic heat current asymmetry in the structure arises from large mismatch between the thermal properties of these two. We demonstrate experimentally temperature differences exceeding 6060 mK between the forward and reverse thermal bias configurations. Our device offers a remarkably large heat rectification ratio up to 140\sim 140 and allows its prompt implementation in true solid-state thermal nanocircuits and general-purpose electronic applications requiring energy harvesting or thermal management and isolation at the nanoscale.Comment: 8 pages, 6 color figure

    Progradation of a shallow carbonate platform developed on a fault-block in the Western Tethys (lower Aptian, Sierra de Bedmar-Jódar, Prebetic of Jaén, Spain).

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    The Middle Member of the Llopis Fm in the Sierra de Bedmar-Jódar Unit of the Prebetic Zone of Jaén (southern Spain) was deposited on a shallow-marine platform of the Southern Iberian Continental Margin during the earliest Aptian. Detailed field logging of nine stratigraphic sections and facies mapping have allowed seven lithofacies associations (L1–L6) to be distinguished, one siliciclastic (L1) and five carbonate facies (L2–6). The succession is composed of eight consecutive elemental sequences of lithofacies associations L1–L6. Each elemental sequence is interpreted as representing one episode of shallowing-upwards carbonate deposition in a very shallow platform-lagoon that was bounded shoreward by clastic/ooid bars and passed seaward either to stromatoporoid bioconstructions (bioherms and biostromes) or rudist biostromes. The successive elemental sequences show north-eastward progradational geometries. Three phases of platform development are identified: (1) installation of the shallow platform; (2) development of a lagoon bounded by a stromatoporoid barrier and (3) development of an Urgonian-type platform dominated by rudists. During the early Aptian, the Bedmar-Jódar platform was partially isolated from the rest of the Prebetic platform and showed overall progradation towards the NE, in contrast to the general south-eastward progradational trend of the Prebetic platform. Sedimentation was controlled by rift-generated extensional tectonics that resulted in tilting of the platform block, causing the deviation of progradation from the general trends of the Prebetic Platform. In addition, climatic influence is inferred from the presence of siliciclastic sediments derived from weathering of the hinterland, which restricted the carbonate factory.Depto. de Geodinámica, Estratigrafía y PaleontologíaFac. de Ciencias GeológicasTRUEUniversidad de JaénSecretaría de Estado de I + D + iJunta de Andalucíapu

    Convectively driven sinks and magnetic fields in the quiet-Sun

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    ©2017 The American Astronomical Society. All rights reserved. We study the relation between mesogranular flows, convectively driven sinks and magnetic fields using high spatial resolution spectropolarimetric data acquired with the Imaging Magnetograph eXperiment on board Sunrise. We obtain the horizontal velocity flow fields of two quiet-Sun regions (31.2 × 31.2 Mm2) via local correlation tracking. Mesogranular lanes and the central position of sinks are identified using Lagrange tracers. We find 6.7×1026.7\times {10}^{-2} sinks per Mm2 in the two observed regions. The sinks are located at the mesogranular vertices and turn out to be associated with (1) horizontal velocity flows converging to a central point and (2) long-lived downdrafts. The spatial distribution of magnetic fields in the quiet-Sun is also examined. The strongest magnetic fields are preferentially located at sinks. We find that 40% of the pixels with longitudinal components of the magnetic field stronger than 500 G are located in the close neighborhood of sinks. In contrast, the small-scale magnetic loops detected by Martínez González et al. in the same two observed areas do not show any preferential distribution at mesogranular scales. The study of individual examples reveals that sinks can play an important role in the evolution of quiet-Sun magnetic features.The work by I.S.R. has been funded by the Basque Government under a grant from Programa Predoctoral de Formación de Personal Investigador del Departamento de Educación, Universidades e Investigación. This work has been partially funded by the Spanish Ministerio de Economía y Competitividad, through Projects No. ESP2013-47349-C6-1-R and ESP2014-56169-C6-1-R, including a percentage from European FEDER funds. The German contribution has been funded by the Bundesministerium für Wirtschaft und Technologie through Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR), grant number 50 OU 0401, and by the Innovationsfond of the President of the Max Planck Society (MPG). This work was partly supported by the BK21 plus program through the National Research Foundation (NRF) funded by the Ministry of Education of Korea.Peer reviewe
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