Evaluación de la carga de fallo por tracción diagonal en vigas de hormigón armado sin cercos a través del estudio del efecto de tamaño

This paper proposes an expression to evaluate the load causing diagonal-tension failure of reinforced concrete beams without stirrups. The study is based on experimental tests results and basic concepts of Fracture Mechanics. It is observed that longitudinal reinforced bars modify the trend in size effect as compared to the one shown by un-reinforced notched beams. To quantify this effect, a theoretical model is established and validated against tests of reinforced concrete beams. From the proposed model, an expression is developed to determine the diagonal-tension strength in beams without stirrups. To facilitate the application in structural design, a series of simplifications has been done, so that the final expression is based on the parameters conventionally used in the design of concrete structures.El presente trabajo propone una expresión para evaluar la carga de fallo por traccion diagonal en vigas de hormigón armado sin cercos. El estudio se fundamenta en resultados experimentales y en conceptos básicos de Mecánica de Fractura con el fin de analizar el efecto de tamaño. Se comprueba que la armadura longitudinal modifica el efecto de tamaño respecto al de elementos entallados sin armadura. Para cuantificar este efecto establecemos un modelo teórico que se contrasta con ensayos de vigas de hormigón armado. A partir del modelo propuesto se presenta una formulación para determinar la carga de fallo por tracción diagonal en vigas de hormigón sin cercos. Para facilitar la aplicación de la formulación se realizan una serie de simplificaciones y finalmente se obtiene una expresión en función de los parámetros convencionalmente utilizados en el diseño de estructuras de hormigón

Discovery of 36 eclipsing EL CVn binaries found by the Palomar Transient Factory

We report the discovery and analysis of 36 new eclipsing EL CVn-type binaries, consisting of a core helium-composition pre-white dwarf and an early-type main-sequence companion, more than doubling the known population of these systems. We have used supervised machine learning methods to search 0.8 million lightcurves from the Palomar Transient Factory, combined with SDSS, Pan-STARRS and 2MASS colours. The new systems range in orbital periods from 0.46-3.8 d and in apparent brightness from ~14-16 mag in the PTF $R$ or $g^{\prime}$ filters. For twelve of the systems, we obtained radial velocity curves with the Intermediate Dispersion Spectrograph at the Isaac Newton Telescope. We modelled the lightcurves, radial velocity curves and spectral energy distributions to determine the system parameters. The radii (0.3-0.7 $\mathrm{R_{\odot}}$) and effective temperatures (8000-17000 K) of the pre-He-WDs are consistent with stellar evolution models, but the masses (0.12-0.28 $\mathrm{M_{\odot}}$) show more variance than models predicted. This study shows that using machine learning techniques on large synoptic survey data is a powerful way to discover substantial samples of binary systems in short-lived evolutionary stages

Analysis of spiral structure in the accretion disc of the novalike Cataclysmic Variable EC21178--5417

We present an extensive Doppler tomography study of the eclipsing novalike EC21178--5417, which exhibits the classic accretion disc signature in the form of double-peak emission lines in its spectrum. Doppler tomograms confirm the presence of a strong, two-armed spiral pattern visible in the majority of the spectral lines studied. This makes EC21178--5417 one of the very few novalikes that show spiral structure in their discs. We also report night-to-night changes in the position and relative strength of the spiral arms, revealing fluctuations on the conditions in the accretion disc.Comment: 13 pages, 8 figure

Peritoneal repairing cells: A type of bone marrow derived progenitor cells involved in mesothelial regeneration

The peritoneal mesothelium exhibits a high regenerative ability. Peritoneal regeneration is concomitant with the appearance, in the coelomic cavity, of a free-floating population of cells whose origin and functions are still under discussion. We have isolated and characterized this cell population and we have studied the process of mesothelial regeneration through flow cytometry and confocal microscopy in a murine model lethally irradiated and reconstituted with GFP-expressing bone marrow cells. In unoperated control mice, most free cells positive for mesothelin, a mesothelial marker, are green fluorescent protein (GFP). However, 24 hrs after peritoneal damage, free mesothelin+/ GFP+ cells appear in peritoneal lavages. Cultured lavage peritoneal cells show colocalization of GFP with mesothelial (mesothelin, cytokeratin) and fibroblastic markers. Immunohistochemical staining of the peritoneal wall also revealed colocalization of GFP with mesothelial markers and with procollagen-1 and smooth muscle α-actin. This was observed in the injured area as well as in the surrounding not-injured peritoneal surfaces. These cells, which we herein call peritoneal repairing cells (PRC), are very abundant 1 week after surgery covering both the damaged peritoneal wall and the surrounding uninjured area. However, they become very scarce 1 month later, when the mesothelium has completely healed. We suggest that PRC constitute a type of monocyte-derived cells, closely related with the tissue-repairing cells known as 'fibrocytes' and specifically involved in peritoneal reparation. Thus, our results constitute a synthesis of the different scenarios hitherto proposed about peritoneal regeneration, particularly recruitment of circulating progenitor cells and adhesion of free-floating coelomic cells. © 2011 The Authors Journal of Cellular and Molecular Medicine © 2011 Foundation for Cellular and Molecular Medicine/Blackwell Publishing Ltd.(Ministerio de Ciencia e Innovación), RD06/0010/0015 (TerCel network, ISCIII), P06-CTS-01614, P08-CTS-03618 (Junta de AndalucÌa) and LSHM-CT-2005–018630 (VI framework, UE)Peer Reviewe

Caracterización de aceites de macadamia y de nuez pecanera y detección de mezclas con otros aceites de semillas comestibles por espectroscopía Raman

Authenticating fats and detecting their adulteration with substantially cheaper fats can pose major problems for producers of high-value oils for nutritional and cosmetic use. In this work, we used Raman spectroscopy to discriminate macadamia and pecan oils from other, cheaper vegetable oils including corn and sunflower oils. This technique additionally allows one to detect and assess the adulteration of macadamia oil with another vegetable oil.La autentificación de grasas para detectar su adulteración con otras grasas más baratas es uno de los principales problemas a los que se enfrentan los productores de aceites de alto valor, ya sea para uso alimentario o para uso cosmético. En este trabajo se emplea la espectroscopia Raman, por un lado, para caracterizar los aceites de macadania y de nuez pecanera, de alto valor y diferenciarlos de otros más baratos, como los de maíz y de girasol, y por otro, para detectar mezclas del aceite de macadamia con estos aceites vegetales más baratos

Switching from natalizumab to fingolimod: an observational study

Background – Multiple sclerosis patients who discontinue using natalizumab are at risk of a rebound in disease activity. However, the optimal alternative therapy is not currently known. Aims of the study – We report on clinical and MRI data and patient safety in a group of relapsing–remitting multiple sclerosis patients who tested seropositive for the JC virus and who have switched from natalizumab to fingolimod because of concerns regarding PML risks. Methods – The test for JC virus antibodies was performed in 18 relapsing–remitting multiple sclerosis patients who were being treated with natalizumab for more than 1 year. Eight seropositive patients switched to fingolimod while the seronegative patients continued with natalizumab. Results – After switching to fingolimod, five of eight patients (63%) experienced clinical relapses, and MRI activity was detected in six of eight patients (75%). Neither clinical relapses nor MRI activity was observed in the patients who continued with natalizumab. No serious adverse effects were detected. Conclusions – Natalizumab is an effective treatment for relapsing–remitting multiple sclerosis, but its discontinuation continues to be a complex problem. All of the therapies tried thus far, including fingolimod, have been unable to control the reactivation of the disease. Further studies addressing alternative therapies after natalizumab discontinuation are necessary