151 research outputs found

    Revisiting epsilon serializabilty to improve the database state machine

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    Recently, a large body of research has been exploiting group communication based techniques to improve the dependability and performance of synchronously replicated database systems

    Evaluation of water use, yield and water productivity of a high-density orchard (cv. Cobrançosa) subjected to different irrigation regimes – An account of four years

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    The impact of different irrigation scheduling regimes on the water use, yield and water productivity from a high-density olive grove cv. Cobrançosa in southern Portugal was assessed during the irrigation seasons of 2011, 2012, 2013 and 2014. The experiments were conducted in a commercial olive orchard at the Herdade Álamo de Cima, near Évora (38o 29' 49.44'' N, 7o 45' 8.83'' W; alt. 75 m) in southern Alentejo, Portugal. The orchard was established with 10-year old Cobrançosa trees in grids of 8.0 x 4.2 m (300 trees ha-1) in the E-W direction, and experiments conducted on a shallow sandy loam Regosoil Haplic soil. From mid-May to the end of September the orchard was irrigated and three plots were subjected to one of two irrigation treatments: a control treatment A, irrigated to replace 100% ETc, a moderate deficit irrigation treatment B irrigated to 70% of ETc, and a more severe deficit irrigation treatment C that provided for approximately 50% of ETc. Daily tree transpiration rates were obtained by continuously monitoring of sap flow in representative trees per treatment. Among the irrigated treatments, water use efficiency (WUE, ratio of water used to irrigation- water applied) of treatment C was the highest, with a value of 0.89, being treatment B slightly lower, with a WUE of 0.76. Olive harvest for 2012 was an exceptional “on year”. Bearing yields showed contrasting differences within years where an “on year” was followed by an “off year”. In 2011 and 2012 treatment B yields were 41 and 50% higher than treatment C, respectively. In 2013 treatment B yield was 45% higher than yield of the fully irrigated treatment A, and treatment C showed practically the same yield than treatment A. In the “on year” of 2014 treatment B averaged 48% higher yield than treatment C. Treatment B farm irrigation water productivity (WPI-Farm, ratio of yield to water applied) was the highest among all treatments. Treatment A showed the lowest conversion efficiency of all treatments, indicating treatment B as the adequate deficit irrigation treatment for our Cobrançosa orchar

    Neospora caninum: high susceptibility to the parasite in C57BL/10ScCr mice

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    Neospora caninum: high susceptibility to the parasite in C57BL/10ScCr miceC57BL/10ScCr mice, lack Toll-like receptor 4 and a functional Interleukin-12 receptor. Taking this into account, susceptibility of these mice to Neospora caninum infection was assessed comparatively to that of immunocompetent C57BL/10ScSn mice. C57BL/10ScCr mice inoculated intraperitoneally with 5 x 10(5) N. caninum tachyzoites showed a high Susceptibility to this parasite. All infected C57BL/10ScCr mice were dead by day 8 post-infection whereas all control C57BL/10ScSn mice survived this parasitic challenge. Immunohistochemical analysis of infected C57BL/10ScCr mice showed N. caninum tachyzoites spread in the pancreas, liver, lung, intestine, heart and brain whereas no parasites were detected in similarly infected C57BL/10ScSn controls. The higher susceptibility of C57BL/10ScCr mice to neosporosis correlates with reduced interferon-gamma mRNA expression and increased IL-4 mRNA expression, comparatively to C57BL/10ScSn controls, detected in the spleen after the parasitic challenge. C57BL/10ScCr mice could thus be used as a new experimental model where to study immunobiological mechanisms associated with host Susceptibility to neosporosis.info:eu-repo/semantics/publishedVersio

    Avaliação de um SGBD replicado usando simulação de redes

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    A replicação de sistemas de gestão de bases de dados (SGBD) é um mecanismo fundamental para a fiabilidade de sistemas de informação. Em sistemas geograficamente distribuídos é ainda útil na recuperação de desas- tres e disponibilidade ubíqua de dados. Uma técnica de replicação recentemente proposta é a Database State Ma- chine (DBSM), que promete aliar fiabilidade a elevado desempenho tirando partido de sistemas de comunicação em grupo. A avaliação do desempenho desta técnica tem no entanto sido efectuada com redes de comunicação demasiado simples ou irrealistas e com uma carga não representativa. Este artigo propõe uma avaliação rigorosa de uma concretização desta técnica de replicação, aliando um modelo de simulação realista de redes de comunicação com uma geração de carga efectuada de acordo com os padrões elaborados pelo Transaction Processing Council (TPC). Os resultados obtidos confirmam o interesse desta técnica em redes locais, mas mostram que o seu desempenho é condicionado pelas características da rede e da carga.FCT no âmbito do projecto ESCADA - POSI-CHS-33792-

    Pectus Excavatum postsurgical outcome based on preoperative soft body dynamics simulation

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    Pectus excavatum is the most common congenital deformity of the anterior chest wall, in which an abnormal formation of the rib cage gives the chest a caved-in or sunken appearance. Today, the surgical correction of this deformity is carried out in children and adults through Nuss technic, which consists in the placement of a prosthetic bar under the sternum and over the ribs. Alth ough this technique has been shown to be safe and reliable, not all patients have achieved adequate cosmetic outcome. This often leads to psyc hological problems and social stress, before and after the surgical correction. This paper targets this particular problem by presenting a method to predict the patient surgical outcome based on pre-surgical imagiologic information and chest skin dynamic modulation. The proposed approach uses the patient pre-surgical thoracic CT scan and anatomical-surg ical references to perform a 3D segmentation of the left ribs, right ribs, sternum and skin. The technique encompasses three steps: a) approximation of the cartilages, between the ribs and the sternum, trough b-spline interpolation; b) a volu metric mass spring model that connects two layers - inner skin layer based on the outer pleura contour and the outer su rface skin; and c) displacement of the sternum according to the prosthetic bar position. A dynamic model of the skin around the chest wall region was generated, capable of simulating the effect of the movement of the prosthetic bar along the sternum. The results were compared and validated with patient postsurgical skin surface acquired with Polhemus FastSCAN system.Fundação para a Ciência e Tecnologi

    Numerical solution of time-dependent Maxwell’s equations for modeling scattered electromagnetic wave’s propagation

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    We present the discontinuous Galerkin method combined with a low-storage Runge-Kutta method as an accurate and efficient way to numerically solve the time-dependent Maxwell’s equations. We investigate the numerical scheme in the context of modeling scattered electromagnetic wave’s propagation through human eye’s structures

    Data mining approach for unconfined compression strength prediction of laboratory soil cement mixtures

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    A previsão da resistência à compressão uniaxial (qu) de misturas solo-cimento é de elevada importância durante a fase de projeto. Para a sua quantificação são realizados ensaios laboratoriais, os quais consomem muito tempo e recursos. Neste artigo é apresentada uma nova abordagem para avaliação da qu ao longo do tempo tirando proveito das elevadas capacidades de aprendizagem das técnicas de Inteligência Artificial (IA). Três algoritmos de IA, nomeadamente as Redes Neuronais Artificiais (RNAs), as Máquinas de Vetores de Suporte (MVSs) e Regressões Múltiplas (RMs), foram treinados utilizando uma base de dados composta por 444 registos contemplando solos não coesivos, coesivos e orgânicos, assim como diferentes ligantes, condições de mistura e tempos de cura. Os resultados obtidos evidenciam um desempenho promissor na previsão da qu de misturas laboratoriais de solo-cimento, sendo o melhor desempenho conseguido através da média das previsões obtidas pelas MVSs e RNAs (R2=0.95). Estes modelos reproduzem eficazmente os principais efeitos das variáveis de entrada, nomeadamente da razão água/cimento, teor em cimento, teor em matéria orgânica e tempo de cura, as quais são conhecidas como preponderantes no comportamento de misturas solo-cimento.info:eu-repo/semantics/publishedVersio

    Thoracic wall reconstruction using ultrasound images to model/bend the thoracic prosthesis for correction of pectus excavatum

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    Pectus excavatum is the most common congenital deformity of the anterior thoracic wall. The surgical correction of such deformity, using Nuss procedure, consists in the placement of a personalized convex prosthesis into sub-sternal position to correct the deformity. The aim of this work is the CT-scan substitution by ultrasound imaging for the pre-operative diagnosis and pre-modeling of the prosthesis, in order to avoid patient radiation exposure. To accomplish this, ultrasound images are acquired along an axial plane, followed by a rigid registration method to obtain the spatial transformation between subsequent images. These images are overlapped to reconstruct an axial plane equivalent to a CT-slice. A phantom was used to conduct preliminary experiments and the achieved results were compared with the corresponding CT-data, showing that the proposed methodology can be capable to create a valid approximation of the anterior thoracic wall, which can be used to model/bend the prosthesis.Fundação para a Ciencia e Tecnologia (FCT
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