99 research outputs found

    El uso de expansores tisulares en cirugía reconstructiva : descripción de un caso clínico

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    Los expansores tisulares son instrumentos empleados frecuentemente en cirugia reconstructiva humana, pero su uso en cirugia veterinaria es extremadamente infrecuente. Este articulo pretende presentar algunos aspectos generales de su uso en cirugia humana, discutir sus posibles usos en cirugia veterinaria y descubrir su utilizacion con exito en un caso clinico

    Design methodology for low cost tubular digesters

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    The aim of this paper is to present a novel, universal, methodology for the design of low cost tubular digesters. This method improves on the established methodology by avoiding assumptions that tend to reduce the final hydraulic retention time (HRT) of digesters once installed. This work recommends designing the digester using trench cross-sectional area and proposes an optimization of the trench dimensions with respect to the angle of the walls and the relationship between the length of the biogas bell and the top width of the trench. The influence of the biogas pressure is considered. A simple geometrical analysis is presented that, by parameterization, can be applied in a wide range of situations

    Influencing factors in energy use of housing blocks: a new methodology, based on clustering and energy simulations, for decision making in energy refurbishment projects

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    In recent years, big efforts have been dedicated to identify which are the factors with highest influence in the energy consumption of residential buildings. These factors include aspects such as weather dependence, user behaviour, socio-economic situation, type of the energy installations and typology of buildings. The high number of factors increases the complexity of analysis and leads to a lack of confidence in the results of the energy simulation analysis. This fact grows when we move one step up and perform global analysis of blocks of buildings. The aim of this study is to report a new methodology for the assessment of the energy performance of large groups of buildings when considering the real use of energy. We combine two clustering methods, Generative Topographic Mapping and k-means, to obtain reference dwellings that can be considered as representative of the different energy patterns and energy systems of the neighbourhood. Then, simulation of energy demand and indoor temperature against the monitored comfort conditions in a short period is performed to obtain end use load disaggregation. This methodology was applied in a district at Terrassa City (Spain), and six reference dwellings were selected. Results showed that the method was able to identify the main patterns and provide occupants with feasible recommendations so that they can make required decisions at neighbourhood level. Moreover, given that the proposed method is based on the comparison with similar buildings, it could motivate building occupants to implement community improvement actions, as well as to modify their behaviour

    Performance Analysis of a Small-Scale Biogas-Based Trigeneration Plant: An Absorption Refrigeration System Integrated to an Externally Fired Microturbine

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    Trigeneration or combined cooling, heat and power (CCHP) systems fueled by raw biogas can be an interesting alternative for supplying electricity and thermal services in remote rural areas where biogas can be produced without requiring sophisticated equipment. In this sense, this study considers a performance analysis of a novel small-scale CCHP system where a biogas-fired, 5 kWel externally fired microturbine (EFMT), an absorption refrigeration system (ARS) and heat exchangers are integrated for supplying electricity, refrigeration and hot water demanded by Bolivian small dairy farms. The CCHP solution presents two cases, current and nominal states, in which experimental and design data of the EFMT performance were considered, respectively. The primary energy/exergy rate was used as a performance indicator. The proposed cases show better energy performances than those of reference fossil fuel-based energy solutions (where energy services are produced separately) allowing savings in primary energy utilization of up to 31%. Furthermore, improvements in electric efficiency of the EFMT and coefficient of performance (COP) of the ARS, identified as key variables of the system, allow primary energy savings of up to 37%. However, to achieve these values in real conditions, more research and development of the technologies involved is required, especially for the EFM

    Dynamics of delayed-coupled chaotic logistic maps: influence of network topology, connectivity and delay times

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    We review our recent work on the synchronization of a network of delay-coupled maps, focusing on the interplay of the network topology and the delay times that take into account the finite velocity of propagation of interactions. We assume that the elements of the network are identical (NN logistic maps in the regime where the individual maps, without coupling, evolve in a chaotic orbit) and that the coupling strengths are uniform throughout the network. We show that if the delay times are sufficiently heterogeneous, for adequate coupling strength the network synchronizes in a spatially homogeneous steady-state, which is unstable for the individual maps without coupling. This synchronization behavior is referred to as ``suppression of chaos by random delays'' and is in contrast with the synchronization when all the interaction delay times are homogeneous, because with homogeneous delays the network synchronizes in a state where the elements display in-phase time-periodic or chaotic oscillations. We analyze the influence of the network topology considering four different types of networks: two regular (a ring-type and a ring-type with a central node) and two random (free-scale Barabasi-Albert and small-world Newman-Watts). We find that when the delay times are sufficiently heterogeneous the synchronization behavior is largely independent of the network topology but depends on the networks connectivity, i.e., on the average number of neighbors per node.Comment: 5 pages, 7 figures. Also submitted to Pramana: the journal of the Indian Academy of Sciences. To appear in the Proceedings of "Perspectives on Nonlinear Dynamics 2007

    Testing the predicted mass-loss bi-stability jump at radio wavelengths

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    In this study, we test the theoretically predicted mass-loss behaviour as a function of stellar effective temperature across the so-called `bi-stability' jump (BSJ). We gathered radio observations of 30 OB supergiants (O8-B3). We derived the radio mass-loss rates and wind efficiencies, and compared our results with Halpha mass-loss rates and predictions based on radiation-driven wind models. he wind efficiency shows the possible presence of a local maximum around an effective temperature of 21~000 K -- in qualitative agreement with predictions. We also find that the radio mass-loss rates show good agreement with empirical Halpha rates. However, the empirical mass-loss rates are larger than the predicted rates from radiation-driven wind theory for objects above the BSJ temperature, whilst they are smaller for the rest. A new wind momenta-luminosity relation for O8-B0 stars has been derived.Comment: 13 pages, 13 figures, A&

    Serological diagnosis of chronic Chagas disease: Is it time for a change?

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    Chagas disease has spread to non-endemic areas with human migration. Since no single reference standard test is available, serological diagnosis of chronic Chagas disease requires at least two tests. New generation techniques have significantly improved the accuracy of Chagas disease diagnosis by the use of a large mixture of recombinant antigens with different detection systems, such as chemiluminescence. The aim of the present study was to assess the overall accuracy of a new generation kit, Architect Chagas (cut-off ≥ 1 S/CO, sample relative light units/cut-off value), as a single technique in the diagnosis of chronic Chagas disease. Architect Chagas showed a sensitivity of 100% (95% confidence interval, CI = 99.5-100) and a specificity of 97.6% (95% CI = 95.2-99.9). Five out of six false-positive sera were a consequence of cross-reactivity with Leishmania spp. and all of them achieved results < 5 S/CO. We propose Architect Chagas as a single technique for screening in blood banks and for routine diagnosis in clinical laboratories. Only grey zone and positive sera with a result ≤ 6 S/CO would need to be confirmed by a second serological assay, thus avoiding false-positive sera and the problem of cross-reactivity with Leishmania spp. The application of this proposal would result in important savings in the cost of Chagas disease diagnosis and therefore in the management and control of the disease

    Structure des grands bassins glaciaires dans le nord de la péninsule ibérique: comparaison entre les vallées d'Andorre (Pyrénées orientales), du Gállego (Pyrénées centrales) et du Trueba (Chaîne Cantabrique).

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    Les grandes vallées glaciaires de la Péninsule Ibérique sont situées dans la chaîne pyrénéo-cantabrique, principalement dans le bassin de l'Èbre. Ainsi, les vallées d'Andorre, de la Noguera Pallaresa et de la haute vallée du Gállego, dans les Pyrénées, ont eu des appareils glaciaires longs de 42, 50 et 40 km respectivement. Dans les vallées du Sil (bassin du Miño) et du Trueba, dans la Chaîne Cantabrique, ils atteignaient 42 et 16,5 km (Serrano-Cañadas, 1996 ; Gómez-Ortiz et al., 2001 ; Turu & Peña, 2006a et b ; Redondo-Vega et al., 2006). L'une des caractéristiques géomorphologiques de la plupart de ces vallées est l'existence d'une dépression morphologique du substratum dans les parties moyennes et terminales, interprétée comme la conséquence de l'érosion glaciaire. Dans tous les cas, on observe une architecture litho-stratigraphique commune (Vilaplana & Casas, 1983 ; Bordonau et al., 1989 ; Bordonau, 1992 ; Turu et al., 2002) représentée par trois unités géoélectriques : une unité inférieure très épaisse, avec des résistivités électriques basses (70 - 200 Ohms par mètre), qui traduit la présence de matériaux fins considérés comme d'origine lacustre ; une unité intermédiaire, moins épaisse, avec des valeurs de résistivité plus élevées (400 - 800 Ohms par mètre), pouvant être interprétée comme un système fluvio-deltaïque pro-glaciaire et une unité géoélectrique supérieure, avec des valeurs de résistivité très variables (100 - 1500 Ohms par mètre), constituée de sédiments alluviaux subactuels. La comparaison des données de type géophysique et géomécanique (sismique à réfraction et essais pressiométriques) montre que l'unité intermédiaire, considérée comme d'origine fluvio-deltaïque, présente des valeurs de vitesse sismique anormalement élevées, ainsi que de hautes valeurs de consolidation. Cette observation effectuée pour la première fois dans la vallée d'Andorre (Turu, 2000) montre des remarquables corrélations entre les hautes vitesses sismiques et les valeurs élevées de consolidation, ainsi que la très nette corrélation entre les hautes valeurs de consolidation et les tills sous-glaciaires. Elle permet d'interpréter l'unité intermédiaire comme essentiellement glaciaire et de remettre en question le modèle simple d'une séquence de comblement lacustre et deltaïque proposé jusqu´à maintenant

    A dust-enshrouded tidal disruption event with a resolved radio jet in a galaxy merger

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    Tidal disruption events (TDEs) are transient flares produced when a star is ripped apart by the gravitational field of a supermassive black hole (SMBH). We have observed a transient source in the western nucleus of the merging galaxy pair Arp 299 that radiated >1.5 × 1052 erg in the infrared and radio but was not luminous at optical or x-ray wavelengths. We interpret this as a TDE with much of its emission reradiated at infrared wavelengths by dust. Efficient reprocessing by dense gas and dust may explain the difference between theoretical predictions and observed luminosities of TDEs. The radio observations resolve an expanding and decelerating jet, probing the jet formation and evolution around a SMBH

    A dust-enshrouded tidal disruption event with a resolved radio jet in a galaxy merger

    Get PDF
    Tidal disruption events (TDEs) are transient flares produced when a star is ripped apart by the gravitational field of a supermassive black hole (SMBH). We have observed a transient source in the western nucleus of the merging galaxy pair Arp 299 that radiated >1.5 × 10 erg at infrared and radio wavelengths but was not luminous at optical or x-ray wavelengths. We interpret this as a TDE with much of its emission reradiated at infrared wavelengths by dust. Efficient reprocessing by dense gas and dust may explain the difference between theoretical predictions and observed luminosities of TDEs. The radio observations resolve an expanding and decelerating jet, probing the jet formation and evolution around a SMBH. Copyright © 2018, American Association for the Advancement of ScienceS.M. acknowledges financial support from the Academy of Finland (pmject 8120503). The research leading to these mats has received funding from the European.. Commission Seventh Framework Programme (FP/2007-2013) under grant agreement number & 227290, 283393 (RadioNc-t) and 60725 (HELP). AA., M.P.-T., N.R.-O. and R.H.T. acknowledge support from the Spanish MINECO through grants AYA2012-38491-002-02 and AYA2015 63939 C2 1 P. P.G.J. acknowledges support from European Research Council Consolidator Grant 647208. C.R.-C. acknowledges support by the Ministry of Economy, Development and Tourism's Millennium Science Initiative through grant 10120009, awarded to The Millennium. Institute of Astrophysics, MAS Chile, and from CONICYT through FONDECYT grant 3150238 and China-CON1CYT fund CAS160313. P.M. and M.A.A. acknowledge support from the ERC research grant CAMAP-250276, and partial support from the Spanish MINECO grant AYA2015-66889C2-1P Lard the local Valencia government ghat PROMETE0-11-2014069. FIE. acknowledges support from a Science Foundation Ireland-Royal Society University Research Fellowship. D.L.C. acknowledges support from grants ST/0001901/4 ST/J001368/1, ST/ K001051/1, and st/N0001138/1. P.V. acknowledges support from the National Research Foundation of South Africa.. J.H. acknowledges financial support tom the Finis h ChAth ral Fouridation and the Virile), YIP and Kahle Vais8I8 Foundation. J.K. acknowledges financial support from the Academy of Finland (grant 311138)
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