1,971 research outputs found

    Aloinjertos y autoinjertos de ligamento cruzado anterior de la rodilla: estudio experimental en el perro

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    Hemos realizado un trabajo de cirugía experimental en perros, en el que comparamos el comportamiento de los autoinjertos frescos de ligamento cruzado anterior de la rodilla (LCA), con lo aloinjertos crioconservados. Con la ayuda de una guía y trefinas, se extrae el LCA con sus inserciones, unido a un taco óseo en cada extremo. Los autoinjertos se reimplantan tras unos minutos en suero fisiológico. Los aloinjertos son sometidos a congelación y, almacenamiento a —80 °C y descongelación rápida, antes de su implantación. Se realiza una fijación de los tacos óseos con tornillos de esponjosa de 6,5 mm, lo que nos permite prescindir de la inmovilización. Los animales se sacrifican a las 3, 6, 12, 24 y 36 semanas, realizando estudio vascular con técnica de transparencia de tejidos de Spalteholz y estudios histológicos. Se demuestra que ambos injertos sufren los mismos procesos biológicos de reparación. Células mesenquimales indiferenciadas y brotes capilares del receptor, invaden los componentes del injerto; se produce una diferenciación polarizada a osteoblastos en el hueso y a fibroblastos en el ligamento, que por mecanismo de sustitución por yuxtaposición, restauran un LCA similar al normal, bien vascularizado. Esta remodelación llega a las zonas profundas, en los autoinjertos a las 12 semanas y en los aloinjertos a las 24 semanas. A las 36 semanas, ambos injertos están maduros. No ha habido rechazo inmunológico. En nuestra opinión el aloinjerto de LCA, con hueso en sus extremos, puede ser el sustituto ideal para las roturas de LCA.Experimental surgery was performed on the dog to compare the behavior of fresh autografts with freeze-stored allografts of the anterior cruciate ligament (ACL). In both cases, drill holes were made at the ACL insertion sites with a cannulated bit and the ligament with a plug of bone attached to each end was extracted with the aid of a guide wire. Prior to implantation, autografts were inmersed in a saline solution for a few minutes. Allografts deeply frozen to -80 °C with liquid nitrogen were quickly thawed before surgery. At implantation, the bone plugs at the ends of the ligament were firmly anchored with 6,5 mm. cancellous bone screws, so inmobilization of the animals was not necessary. Animals were killed at 3, 6, 12, 24 and 36 week after surgery. To study graft vascularity the tissue transparency technique developed by Spalteholz was employed. Both type of grafts underwent the same biological reconstruction process. Indifferentiated mesenchymal cells and capillar buds from the host tissues invaded the implant. Through a mechanism of creeping substitution induced by fibroblastic and osteoblastic differentiation, the grafts gradually took the apparence of normal, well-vascularized ACL. The remodeling process reached the innermost zones of the autografts in 12 weeks and the allografts in 24 weeks. Both type of groups showed a normal mature appearance 36 weeks after surgery. There were no signs of inmunological rejection. In our opinion, the ideal substitution for repair of ACL injurie could be an allograft of the same ligament, removed with bone attached to each end

    Técnicas de biopsia para el diagnóstico de lesiones mamarias no palpables

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    Facing a non-palpable mammary lesion requiring a diagnostic biopsy, consideration must be given to the most suitable guiding method for obtaining the latter. Three methods are employed at present: stereotaxy (basically in cases of microcalcifications), echography (above all in the nodules), and magnetic resonance (for lesions not made visible through the previous systems). The next step is to select the most suitable biopsy technique. The most classical and reliable technique is the surgical biopsy with prior marking using a metallic harpoon, but, besides its high cost, it has the drawback of being an aggressive technique for the diagnosis of a benign pathology. Numerous systems of puncture have been developed as alternatives. Puncture with a fine needle is technically simple to carry out and can provide good results in the mammary nodules, but the existence of positive and negative false results has progressively limited its use. As an alternative, the systems of biopsy with a broad needle have made it possible to obtain multiple cylinders with a high diagnostic reliability, above all in the case of mammary nodules. However, their use in microcalcifications continues to show negative false results. The arrival of systems of vacuum-assisted biopsy has made it possible to obtain cylinders of greater quality, above all in cases of microcalcifications. Finally, the systems of percutaneous resection biopsy by means of cannulas with a diameter of 22 mm make it possible to completely extract lesions of a size below that of the cannula, with a reliability similar to that of the surgical biopsy

    Perspectivas Ignacianas para ser un buen docente en la Universidad

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    Existe el concepto social que “saber” transforma al experto en un buen docente, peroprobablemente “saber” es la condición básica para ejercer la docencia. El objetivo de este trabajo es analizarlas características que superan al conocimiento para transformarse en un buen docente enriquecido por laVisión Ignaciana de esta actividad.MATERIAL Y MÉTODO: Para elaborar este informe se trabajó sobre tres documentos de alto impacto ennuestro hacer: 1) el paradigma Paradigma Ledesma – Kolvenbach; 2) Constitución apostólica sobre lasUniversidades Católicas de SS Juan Pablo II y 3) La pedagogía Ignaciana.DISCUSIÓN Y CONCLUSIÓN: Ser buen docente, parte del saber especifico, pero es mucho más quesimplemente saber, implica compromiso con la realidad y la capacidad de crear espacios, que favorecen laapropiación crítica del conocimiento y la actitud de búsqueda permanente por parte de la comunidadestudianti

    Mass Production and Morphology of Brauna Brachiaria Under Different Nitrogen Rates in the Brazilian Savannah

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    Nitrogen is the nutrient that most contributes to increase forage productivity and quality. The objective was to evaluate Brauna brachiaria (Urochloa brizantha cv. Brauna) submitted to nitrogen doses in the Brazilian savannah through the total and green mass production, leaf:stem and brachiaria:weed ratio. Plots were established in a randomized block design, with four replications and four N doses 0, 50, 100 and 150 kg N/ha). After the uniformization cut, the data collect cycles occurred when the canopy reached 30 cm average height. Samples were taken until 15 cm from the ground in an area of 0.25 m2 . Fractions were separated according botanical (brachiaria and weeds) and morphological (leaf, stem, dead material and inflorescence) components. The maximum and minimum response points were calculated by derivative. Samples were weighed and dried and values were used to calculate components mass production and ratios. The highest value of dry matter production occurred at 100 kg N/ha dose (2,606 kg DM/ha). Below or above this value the mass production decreased. The highest value of relation green mass:dead material was 4.24 at 131 kg N/ha dose. Brauna was able to control the weeds, and the best performance (4.68) was observed at 86 kg N/ha dose. The highest accumulation rate occurred at 87.5 kg N/ha dose. Brauna had higher leaf:stem ratio with higher nitrogen doses but above 131 kg N/ha the dead mass can result in energy loss per respiration. Above 86 kg/N the mass accumulation rate decreases which means that the fertilization cost is not favorable over this dose

    Gaia23bab: a new EXor

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    © 2024 The Author(s). Published by the American Astronomical Society. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY), https://creativecommons.org/licenses/by/4.0/On March 6 2023, the Gaia telescope has alerted a 2-magnitude burst from Gaia23bab, a Young Stellar Object in the Galactic plane. We observed Gaia23bab with the Large Binocular Telescope obtaining optical and near-infrared spectra close in time to the peak of the burst, and collected all public multi-band photometry to reconstruct the historical light curve. This latter shows three bursts in ten years (2013, 2017 and 2023), whose duration and amplitude are typical of EXor variables. We estimate that, due to the bursts, the mass accumulated on the star is about twice greater than if the source had remained quiescent for the same period of time. Photometric analysis indicates that Gaia23bab is a Class,II source with age < 1 Myr, spectral type G3-K0, stellar luminosity 4.0 L_sun, and mass 1.6 M_sun. The optical/near infrared spectrum is rich in emission lines. From the analysis of these lines we measured the accretion luminosity and the mass accretion rate L_acc(burst)=3.7 L_sun, M_acc(burst) 2.0 10 $^(-7) M_sun/yr, consistent with those of EXors. More generally, we derive the relationships between accretion and stellar parameters in a sample of EXors. We find that, when in burst, the accretion parameters become almost independent of the stellar parameters and that EXors, even in quiescence, are more efficient than classical T Tauri stars in assembling mass.Peer reviewe

    Practicalities of BVID detection on aerospace-grade CFRP materials with optical fibre sensors

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    Several reports have recently shown the capability of optical fibre sensors for the detection of barely visible impact damage (BVID) on CFRP laminates, based on changes in the optical signal before and after impact. Although this approach was shown to work well in lab conditions, little attention has been paid so far to its practicality when considering realistic ambient conditions or to the detection range. In this work we attempt to derive BVID detection thresholds for fibre Bragg grating-based sensors, by considering standardized temperature and vibration levels for aerospace applications. To the best of our knowledge this is the first practical threshold assessment for BVID detection on aerospace-grade CFRP for such sensors. We have put our detection thresholds to the test by analysing a total of 24 BVIDs on 12 panels made from 4 different CFRP material systems and derived commendable sizes for the detection range on the different material systems

    Spectroscopy of 28^{28}Na: shell evolution toward the drip line

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    Excited states in 28^{28}Na have been studied using the β\beta-decay of implanted 28^{28}Ne ions at GANIL/LISE as well as the in-beam γ\gamma-ray spectroscopy at the NSCL/S800 facility. New states of positive (Jπ^{\pi}=3,4+^+) and negative (Jπ^{\pi}=1-5^-) parity are proposed. The former arise from the coupling between 0d_5/2\_{5/2} protons and a 0d_3/2\_{3/2} neutron, while the latter are due to couplings with 1p_3/2\_{3/2} or 0f_7/2\_{7/2} neutrons. While the relative energies between the Jπ^{\pi}=1-4+^+ states are well reproduced with the USDA interaction in the N=17 isotones, a progressive shift in the ground state binding energy (by about 500 keV) is observed between 26^{26}F and 30^{30}Al. This points to a possible change in the proton-neutron 0d_5/2\_{5/2}-0d_3/2\_{3/2} effective interaction when moving from stability to the drip line. The presence of Jπ^{\pi}=1-4^- negative parity states around 1.5 MeV as well as of a candidate for a Jπ^{\pi}=5^- state around 2.5 MeV give further support to the collapse of the N=20 gap and to the inversion between the 0f_7/2\_{7/2} and 1p_3/2\_{3/2} levels below Z=12. These features are discussed in the framework of Shell Model and EDF calculations, leading to predicted negative parity states in the low energy spectra of the 26^{26}F and 25^{25}O nuclei.Comment: Exp\'erience GANIL/LISE et NSCL/S80
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