14,884 research outputs found

    The 12 prophets dataset

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    The "Ajeijadinho 3D" project is an initiative supported by the University of S\~ao Paulo (Museum of Science and Dean of Culture and Extension), which involves the 3D digitization of art works of Brazilian sculptor Antonio Francisco Lisboa, better known as Aleijadinho. The project made use of advanced acquisition and processing of 3D meshes for preservation and dissemination of the cultural heritage. The dissemination occurs through a Web portal, so that the population has the opportunity to meet the art works in detail using 3D visualization and interaction. The portal address is http://www.aleijadinho3d.icmc.usp.br. The 3D acquisitions were conducted over a week at the end of July 2013 in the cities of Ouro Preto, MG, Brazil and Congonhas do Campo, MG, Brazil. The scanning was done with a special equipment supplied by company Leica Geosystems, which allowed the work to take place at distances between 10 and 30 meters, defining a non-invasive procedure, simplified logistics, and without the need for preparation or isolation of the sites. In Ouro Preto, we digitized the churches of Francisco of Assis, Our Lady of Carmo, and Our Lady of Mercy; in Congonhas do Campo we scanned the entire Sanctuary of Bom Jesus de Matosinhos and his 12 prophets. Once scanned, the art works went through a long process of preparation, which required careful handling of meshes done by experts from the University of S\~ao Paulo in partnership with company Imprimate.Comment: Full dataset online at http://aleijadinho3d.icmc.usp.br/data.htm

    Efficiency of low versus high airline pressure in stunning cattle with a pneumatically powered penetrating captive bolt gun

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    The efficiency of stunning cattle was assessed in 443 animals (304 pure Zebu and 139 crossbred cattle), being mainly mature bulls and cows. Cattle were stunned using a Jarvis pneumatically powered penetrating captive bolt gun operating with low (160–175 psi, N = 82) and high (190 psi, N = 363) airline pressure, which was within the manufactures specifications. Signs of brain function and the position of the shots on the heads were recorded after stunning. Velocity of the captive bolt and its physical parameters were calculated. Cattle shot with low pressures showed more rhythmic respiration (27 vs. 8%, P < 0.001), less tongue protrusion (4 vs. 12%, P = 0.03) and less masseter relaxation (22 vs. 48%, P < 0.001). There was an increased frequency of shots in the ideal position when cattle were shot with the low compared to high airline pressures (15.3 vs. 3.1%). Bolt velocity and its physical parameters were significantly (P < 0.01) higher when using high pressure. Airline pressures below 190 psi are inappropriate when shooting adult Zebu beef cattle with pneumatically powered penetrating captive bolt guns

    Energy metabolism in human pluripotent stem cells and their differentiated counterparts

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    Background: Human pluripotent stem cells have the ability to generate all cell types present in the adult organism, therefore harboring great potential for the in vitro study of differentiation and for the development of cell-based therapies. Nonetheless their use may prove challenging as incomplete differentiation of these cells might lead to tumoregenicity. Interestingly, many cancer types have been reported to display metabolic modifications with features that might be similar to stem cells. Understanding the metabolic properties of human pluripotent stem cells when compared to their differentiated counterparts can thus be of crucial importance. Furthermore recent data has stressed distinct features of different human pluripotent cells lines, namely when comparing embryo-derived human embryonic stem cells (hESCs) and induced pluripotent stem cells (IPSCs) reprogrammed from somatic cells. Methodology/Principal Findings: We compared the energy metabolism of hESCs, IPSCs, and their somatic counterparts. Focusing on mitochondria, we tracked organelle localization and morphology. Furthermore we performed gene expression analysis of several pathways related to the glucose metabolism, including glycolysis, the pentose phosphate pathway and the tricarboxylic acid (TCA) cycle. In addition we determined oxygen consumption rates (OCR) using a metabolic extracellular flux analyzer, as well as total intracellular ATP levels by high performance liquid chromatography (HPLC). Finally we explored the expression of key proteins involved in the regulation of glucose metabolism. Conclusions/Findings: Our results demonstrate that, although the metabolic signature of IPSCs is not identical to that of hESCs, nonetheless they cluster with hESCs rather than with their somatic counterparts. ATP levels, lactate production and OCR revealed that human pluripotent cells rely mostly on glycolysis to meet their energy demands. Furthermore, our work points to some of the strategies which human pluripotent stem cells may use to maintain high glycolytic rates, such as high levels of hexokinase II and inactive pyruvate dehydrogenase (PDH). © 2011 Varum et al

    Generalization of Dirac Non-Linear Electrodynamics, and Spinning Charged Particles

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    In this note we generalized the Dirac non-linear electrodynamics, by introducing two potentials (namely, the vector potential A and the pseudo-vector potential gamma^5 B of the electromagnetic theory with charges and magnetic monopoles) and by imposing the pseudoscalar part of the product omega.omega* to be zero, with omega = A + gamma^5 B. We show that the field equations of such a theory possess a soliton-like solution which can represent a priori a "charged particle", since it is endowed with a Coulomb field plus the field of a magnetic dipole. The rest energy of the soliton is finite, and the angular momentum stored in its electromagnetic field can be identified --for suitable choices of the parameters-- with the spin of the charged particle. Thus this approach seems to yield a classical model for the charged (spinning) particle, which does not meet the problems met by earlier attempts in the same direction.Comment: standard LaTeX file; 16 pages; it is a corrected version of a paper appeared in Found. Phys. (issue in honour of A.O.Barut) 23 (1993) 46

    Gravitation and Electromagnetism as Geometrical Objects of a Riemann-Cartan Spacetime Structure

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    In this paper we first show that any coupled system consisting of a gravitational plus a free electromagnetic field can be described geometrically in the sense that both Maxwell equations and Einstein equation having as source term the energy-momentum of the electromagnetic field can be derived from a geometrical Lagrangian proportional to the scalar curvature R of a particular kind of Riemann-Cartan spacetime structure, where those fields are identified as geometrical objects of the structure. We show moreover that the contorsion tensor of the particular Riemann-Cartan spacetime structure of our theory encodes the same information as the one contained in Chern-Simons term that is proportional to the spin density of the electromagnetic field. Next we show that by adding to the geometrical Lagrangian a term describing the interaction of a electromagnetic current with a general electromagnetic plus the gravitational field and a term describing the matter carrier of the current we get Maxwell equations with source term and Einstein equation having as source term the sum of the energy-momentum tensors of the electromagnetic and matter terms. Finally modeling by dust charged matter the carrier of the electromagnetic current we get the Lorentz force equation. Moreover, we prove that our theory is gauge invariant. We also briefly discuss our reasons for the present enterprise.Comment: In this version some few misprints have been corrected and a remark has changed place. Paper will appear in Advances in Applied Clifford Algebra

    Origin of anomalously long interatomic distances in suspended gold chains

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    The discovery of long bonds in gold atom chains has represented a challenge for physical interpretation. In fact, interatomic distances frequently attain 3.0-3.6 A values and, distances as large as 5.0 A may be seldom observed. Here, we studied gold chains by transmission electron microscopy and performed theoretical calculations using cluster ab initio density functional formalism. We show that the insertion of two carbon atoms is required to account for the longest bonds, while distances above 3 A may be due to a mixture of clean and one C atom contaminated bonds.Comment: 4 pages, 4 Postscript figures, to be published in Physical Review Letter

    MAXIMIZAÇÃO DO USO DA URÉIA EM LAVOURA DE Coffea canephora

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    Objetivou-se determinar as perdas de nitrogênio por volatilização de amônia, de uréias com eficiências aumentadas bem como o desenvolvimento e a produtividade do cafeeiro Conilon manejadas com tais uréias. O experimento foi instalado em outubro de 2010 em cafeeiro Conilon cultivar Vitória INCAPER 8142. Foram avaliadas no experimento cinco fontes de adubos nitrogenados: T1= uréia perolada comum (45% N); T2= Uréia (45% N) + NBPT - (Super N®); T3= uréia (44,6% N) + 0,15% de Cu2+ e 0,4% de B (Nitro Mais®); T4= uréia (37% N) + enxofre (17%) (Nitro Gold®); e T5= nitrato de amônio (34% N). Os tratamentos T2, T3 e T4 são considerados com eficiência aumentada. Os coletores de perdas por amônia foram instalados, em cada parcela experimental, imediatamente após a aplicação do fertilizante em três épocas distintas, sendo em outubro, dezembro de 2011 e março de 2012. As esponjas foram trocadas aos 5, 10 e 15 dias, obtendo-se a volatilização. Foram avaliadas diversas características associadas à fluorescência da clorofila a. Essas avaliações foram realizadas em outubro antes da adubação e em janeiro e março 20 dias após as adubações. O crescimento de ramos foi avaliado mensalmente por marcação de dois grupos de ramos em crescimento escolhido ao acaso. Foram marcados quatro ramos plagiotrópicos por parcela. O primeiro grupo de ramos foi marcado e avaliado a partir de 05 de agosto de 2011 e o segundo grupo a partir de 09 de dezembro de 2011 e o terceiro grupo a partir de 12 de abril de 2012. O nitrato de amônio foi à fonte de nitrogênio que obteve menor perda de nitrogênio por volatilização entre as demais fontes nitrogenadas. O Nitro Gold® e a uréia perolada comum foram às fontes de nitrogênio que apresentaram maior perda de nitrogênio por volatilização na segunda avaliação. Dessa forma, sugere-se que a precipitação não foi suficiente para dissolver e incorporar os adubos, permanecendo o solo úmido, aumentando assim a atividade da enzima urease sobre os fertilizantes. Em geral o adubo Super N® e o Nitro Mais® apresentaram as menores perdas por volatilização em relação aos adubos com eficiência aumentada. Não houve diferença estatística nas produções das safras 2011 e 2012 entre as diferentes fontes de nitrogênio aplicadas na adubação do cafeeiro. Constatou-se que valores de fluorescência máxima da clorofila a, não diferiram em nenhuma das épocas analisadas, propondo que as fontes nitrogenadas não alteraram a eficiência do fotossistema II. Percebeu-se que os valores de Índice Relativo de Clorofila (IRC) alternaram suas significâncias com relação aos tratamentos ao longo das datas de avaliação. Presume-se que somente as fontes de N não foram responsáveis, sozinhas, pelas alterações do IRC, uma vez que existem outros fatores que afetam a absorção e as perdas por volatilização de amônia nos solos. Em relação ao crescimento dos três grupos de ramos não foi observado diferença estatística significativa entre as fontes de adubos nitrogenados, na média de crescimento de ramos, em todas as avaliações realizadas. Palavras-chave: Volatilização, características morfofisiológicas, nitrogênio, Coffea canephora L.
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