956 research outputs found

    A novel haptic model and environment for maxillofacial surgical operation planning and manipulation

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    This paper presents a practical method and a new haptic model to support manipulations of bones and their segments during the planning of a surgical operation in a virtual environment using a haptic interface. To perform an effective dental surgery it is important to have all the operation related information of the patient available beforehand in order to plan the operation and avoid any complications. A haptic interface with a virtual and accurate patient model to support the planning of bone cuts is therefore critical, useful and necessary for the surgeons. The system proposed uses DICOM images taken from a digital tomography scanner and creates a mesh model of the filtered skull, from which the jaw bone can be isolated for further use. A novel solution for cutting the bones has been developed and it uses the haptic tool to determine and define the bone-cutting plane in the bone, and this new approach creates three new meshes of the original model. Using this approach the computational power is optimized and a real time feedback can be achieved during all bone manipulations. During the movement of the mesh cutting, a novel friction profile is predefined in the haptical system to simulate the force feedback feel of different densities in the bone

    Diagnostico genético prenatal y aborto. Dos cuestiones de eugenesia y discriminación

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    Los avances en genética seguidos de las nuevas tecnologías en la detección temprana de afecciones genéticas conllevan dilemas bioéticos sobre el uso adecuado de estas técnicas, la información que se le da a la mujer embarazada y la decisión que ella tomará al recibirla. Detectar a tiempo anomalías genéticas permite, en algunas ocasiones, el inicio de un tratamiento adecuado que permita que el niño por nacer no desarrolle una enfermedad discapacitante, como el caso de la fenilcetonuria, o una intervención quirúrgica para un feto con espina bífida, pero en caso que no se tenga ningún tratamiento disponible el aborto sigue siendo la última alternativa. Aunque para muchos cualquier tipo de aborto es eugenésico, esto es busca eliminar individuos no deseados, el objetivo de este artículo es revisar los diferentes tipos de aborto y diferenciar entre el aborto propiamente eugenésico del aborto terapéutico, del aborto con fines sociales o demográficos y del realizado por selección de sexo, para al final proponer que en ciertos casos el aborto eugenésico podría considerarse como bioéticamente aceptable. Advances in genetics followed by the new technologies in the early detection of genetic disorders involving bioethical dilemmas about the proper use of these techniques, the information given to pregnant women and the decision that she will take to receive it. Early detection of genetic abnormalities allow, in some cases, the initiation of appropriate treatment to allow the unborn child does not develop a disabling disease, as the case of phenylketonuria, or surgery for a fetus with spina bifida, but If you do not have any treatment available abortion remains the last alternative. Although for many, any type of abortion is eugenics, that is seeking to eliminate unwanted individuals, the aim of this paper is to review the different types of abortion and the difference between eugenic abortion, therapeutic abortion, abortion for social or demographic ends and Sex-selection made for the for the final proposal that in some cases eugenic abortion could be considered acceptable for bioethics

    Evidence for a Very Large-Scale Fractal Structure in the Universe from Cobe Measurements

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    In this work, we analyse the temperature fluctuations of the cosmic microwave background radiation observed by COBE and show that the distribution can be fitted by a fractal distribution with a fractal dimension D=1.43±0.07 D= 1.43 \pm 0.07 . This value is in close agreement with the fractal dimension obtained by Coleman and Pietronero (1992) and Luo and Schramm (1992) from galaxy-galaxy and cluster-cluster correlations up to 100h1Mpc \sim 100 h^{-1} Mpc. The fact that the observed temperature fluctuations correspond to scales much larger than 100h1Mpc 100 h^{-1} Mpc and are signatures of the primordial density fluctuations at the recombination layer suggests that the structure of the matter at the early universe was already fractal and thus non-homogeneous on those scales. This result may have important consequences for the theoretical framework that describes the universe.Comment: 11 pages, postscript file, 2 figures available upon request. To appear in ApJ Letter

    Resistência do milho (Zea mays L.) transgênico (Bt) a lagarta-do-cartucho, Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae).

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    No Brasil, a utilização de milho transgênico (Bt) pode reduzir perdas causadas por vários lepidópteros-pragas, equivalentes a aproximadamente 500 milhões de dólares anuais. O objetivo deste trabalho foi avaliar os híbridos de milho Bt disponíveis no mercado americano para resistência à lagarta-do-cartucho do milho (LCM), Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae). Nove híbridos de milho Bt expressando as toxinas Cry 1F, Cry 1A(b), Cry 1 A(c) e Cry 9C, além de um híbrido (MP 704 X 707) expressando resistência natural para a LCM, foram comparados num experimento, em campo, em blocos ao acaso, com parcela subdividida e quatro repetições. Nas parcelas, foram comparados os dez híbridos e, nas subparcelas, as versões Bt versus não-Bt, ou híbrido com resistência natural versus susceptível. A infestação artificial foi realizada 33 dias após a semeadura e as avaliações basearam-se no número de larvas sobreviventes, aos 10 e 15 dias após a infestação, peso das larvas sobreviventes e notas de danos nas plantas. Para todas as variáveis estudadas, os resultados demonstraram diferenças significativas (P=0,05) entre os híbridos avaliados. Também as testemunhas não-Bts diferiram significativamente dos respectivos híbridos Bts, exceto para aqueles expressando a toxina Cry 9C. O híbrido 2722 IMI, expressando a toxina Cry 1F, foi o mais resistente (imune) e os híbridos expressando a toxina Cry 1A(b) e a resistência natural foram moderadamente resistentes. Em geral, os híbridos transgênicos resistentes produziram cerca de 32% a mais de grãos que as testemunhas suscetíveis

    Effects of wet CO oxidation on the operation of engines and power generators

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    A simplified method is used to determine the optimum water content in the flue gases of charcoal gasifiers to be utilized as alternative fuels in the operation of engines and gas turbines for power generation. Computational models of plug flow reactors and well stirred reactors are employed to simulate the reaction and post-flame zones, adopting different chemical mechanisms. In the simulations reactants enter the reactors at 1000 K, 1 atm and equivalence ratio 0.25. It was observed that mixtures about 3% to 4% in volume of water vapor allow to obtain optimal operation characteristics, including high blowout limit, low ignition delay, maximum reaction zone temperature, high CO2 prodution and low thermal NO formation. It was observed that increasing water contents reduce significantly ignition times up to 3% in volume, while blowout mass flow rates increase continuously up to 6 % in volume, the maximum value considered. Formation of NO decreases continuously with humidity after the flame zone, while there are peaks of NO formation within the flame zone below 1% in volume. Higher water vapor content decreases the final temperatures below 1700 K, leading to a lower thermal efficiency. The method can be used to estimate optimum operational conditions with other input parameters

    Like a skyscraper: a construção da narrativa terapêutica de Demi Lovato e os reflexos em sua comunidade de fãs

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    As dinâmicas da cultura participativa de fãs nos ambientes digitais vêm transformando as estruturas e relações interativas, afetivas e mercadológicas na indústria cultural. Da mesma forma, o universo das celebridades vem delineando novos caminhos em busca da identidade humanizada e autêntica, abandonando o status de perfeição e configurando uma imagem mais íntima do público. Analisando a construção da narrativa da cantora Demi Lovato em seus documentários Stay Strong (2012) e Simply Complicated (2017), além de suas músicas de caráter autobiográfico, a pesquisa investiga como Lovato administrou a sua imagem heróica ao expressar o sofrimento da vida privada na esfera pública, examinando também quais as consequências desse discurso terapêutico em sua comunidade de fãs, os Lovatics. A partir de uma pesquisa netnográfica foram coletados depoimentos do fandom que demonstram a influência dos testemunhos da artista no comportamento e percepção dos fãs em relação aos seus transtornos particulares

    ARCADE 2 Measurement of the Extra-Galactic Sky Temperature at 3-90 GHz

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    The ARCADE 2 instrument has measured the absolute temperature of the sky at frequencies 3, 8, 10, 30, and 90 GHz, using an open-aperture cryogenic instrument observing at balloon altitudes with no emissive windows between the beam-forming optics and the sky. An external blackbody calibrator provides an {\it in situ} reference. Systematic errors were greatly reduced by using differential radiometers and cooling all critical components to physical temperatures approximating the CMB temperature. A linear model is used to compare the output of each radiometer to a set of thermometers on the instrument. Small corrections are made for the residual emission from the flight train, balloon, atmosphere, and foreground Galactic emission. The ARCADE 2 data alone show an extragalactic rise of 50±750\pm7 mK at 3.3 GHz in addition to a CMB temperature of 2.730±.0042.730\pm .004 K. Combining the ARCADE 2 data with data from the literature shows a background power law spectrum of T=1.26±0.09T=1.26\pm 0.09 [K] (ν/ν0)2.60±0.04(\nu/\nu_0)^{-2.60\pm 0.04} from 22 MHz to 10 GHz (ν0=1\nu_0=1 GHz) in addition to a CMB temperature of 2.725±.0012.725\pm .001 K.Comment: 11 pages 5 figures Submitted to Ap

    Diagnóstico genético prenatal y aborto. Dos cuestiones de eugenesia y discriminación

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    Los avances en genética seguidos de las nuevas tecnologías en la detección temprana de afecciones genéticas conllevan dilemas bioéticos sobre el uso adecuado de estas técnicas, la información que se le da a la mujer embarazada y la decisión que ella tomará al recibirla. Detectar a tiempo anomalías genéticas permite, en algunas ocasiones, el inicio de un tratamiento adecuado que permita que el niño por nacer no desarrolle una enfermedad discapacitante, como el caso de la fenilcetonuria, o una intervención quirúrgica para un feto con espina bífida, pero en caso que no se tenga ningún tratamiento disponible el aborto sigue siendo la última alternativa. Aunque para muchos cualquier tipo de aborto es eugenésico, esto es busca eliminar individuos no deseados, el objetivo de este artículo es revisar los diferentes tipos de aborto y diferenciar entre el aborto propiamente eugenésico del aborto terapéutico, del aborto con fines sociales o demográficos y del realizado por selección de sexo, para al final proponer que en ciertos casos el aborto eugenésico podría considerarse como bioéticamente aceptable
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