11,471 research outputs found

    Utilizing Expert Knowledge in Estimating Future STS Costs

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    A method of estimating the costs of future space transportation systems (STSs) involves classical activity-based cost (ABC) modeling combined with systematic utilization of the knowledge and opinions of experts to extend the process-flow knowledge of existing systems to systems that involve new materials and/or new architectures. The expert knowledge is particularly helpful in filling gaps that arise in computational models of processes because of inconsistencies in historical cost data. Heretofore, the costs of planned STSs have been estimated following a "top-down" approach that tends to force the architectures of new systems to incorporate process flows like those of the space shuttles. In this ABC-based method, one makes assumptions about the processes, but otherwise follows a "bottoms up" approach that does not force the new system architecture to incorporate a space-shuttle-like process flow. Prototype software has been developed to implement this method. Through further development of software, it should be possible to extend the method beyond the space program to almost any setting in which there is a need to estimate the costs of a new system and to extend the applicable knowledge base in order to make the estimate

    Los depósitos de talco y clorita magnesiana de la Sierra de las Estancias (Cordillera Bética, Almería, España)

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    15 páginas, 11 figuras, 5 tablas.[ES] Los depósitos de talco y clorita magnesiana de la Sierra de las Estancias se enclavan en metapelitas y mármoles, pertenecientes a la cobertera triásica de la Unidad de Granja (Complejo Alpujárride). El metamorfismo de esta Unidad alcanza el grado medio. Las mineralizaciones están constituidas por tres tipos principales de rocas: talcocitas, clorititas talcosas y clorititas. Los talcos son de composición química muy próxima a la ideal [Mg3Si4010(OH)2]. Las cloritas corresponden a clinocloro y se caracterizan por poseer una razón Mg/(Mg + Fe) extremadamente alta ( > 0,98). Se establecen dos grupos principales de mineralizaciones: estratoligadas y filonianas. Las mineralizaciones estratoligadas se localizan en la zona de tránsito entre metapelitas (muro) y mármoles (techo), y en la parte inferior del paquete marmóreo. De muro a techo, las mineralizaciones muestran una variación gradual mineralógica y química, esta última caracterizada por un progresivo aumento en Mg y razón Mg/(Mg + Fe), y una disminución en el contenido en K20 y razón Al/Mg. La mayor parte de las mineralizaciones estratoligadas se han formado, durante el metamorfismo alpino, por transformación de sedimentos de composición muy rica en magnesio (probablemente «mudstones» evaporíticos). Una pequeña parte de este tipo de mineralizaciones y las de carácter filoniano se originan por removilización de los depósitos estratoligados.[EN] The talc and magnesium chlorite deposits of Sierra de Las Estancias occur in metapelites and marbles belonging to the Triassic cover of the Granja Unit (Alpujarride Complex). Metamorphism of this Unit reaches medium grade. The mineralizations are composed of talcites, talc chloritites and chloritites. The talc has a chemical composition very close to the ideal formula Mg3Si4010(OH)2]. The chlorite correspond to clinochloro and is characterized by an extremely high Mg/(Mg + Fe) ratio ( > 0.98). Two main groups of mineralizations are established: strata-bound and vein deposits. The first one is located in the transition zone between metapelites (bottom) and marbles (top) and in the lower part of the marble member. From botton to top, the mineralizations show a gradual mineralogical and chemical variation, the latter characterized by a progressive increase in Mg and in the Mg/(Mg + Fe) ratio, and by a decrease in K20 content and in the Al/Mg ratio. Most of the strata-bound mineralizations were formed during the Alpine metamorphism by the transformation of sediments very rich in magnesium (probably evaporite mudstones). A small part of this type of mineralizations and those of vein character originate by remobilization of the strata-bound deposits.Este trabajo ha sido subvencionado por el Instituto de Fomento de Andalucía, por el Proyecto n.O PB85-0385 de la CAICYT y los Grupos de Investigación de la Junta de Andalucía n. OS 4028 y 4065. Agradecemos al Dr. J. M. Martínez Martínez, del Inst. Andaluz de Geología Mediterránea (CSIG-Univ. Granada), la ayuda prestada en los trabajos de campo. Asimismo, agradecemos las útiles sugerencias y comentarios efectuados por el Dr. E. Galán, de la Universidad de Sevilla.Peer reviewe

    Myristic acid potentiates palmitic acid-induced lipotoxicity and steatohepatitis associated with lipodystrophy by sustaning de novo ceramide synthesis.

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    Palmitic acid (PA) induces hepatocyte apoptosis and fuels de novo ceramide synthesis in the endoplasmic reticulum (ER). Myristic acid (MA), a free fatty acid highly abundant in copra/palmist oils, is a predictor of nonalcoholic steatohepatitis (NASH) and stimulates ceramide synthesis. Here we investigated the synergism between MA and PA in ceramide synthesis, ER stress, lipotoxicity and NASH. Unlike PA, MA is not lipotoxic but potentiated PA-mediated lipoapoptosis, ER stress, caspase-3 activation and cytochrome c release in primary mouse hepatocytes (PMH). Moreover, MA kinetically sustained PA-induced total ceramide content by stimulating dehydroceramide desaturase and switched the ceramide profile from decreased to increased ceramide 14:0/ceramide16:0, without changing medium and long-chain ceramide species. PMH were more sensitive to equimolar ceramide14:0/ceramide16:0 exposure, which mimics the outcome of PA plus MA treatment on ceramide homeostasis, than to either ceramide alone. Treatment with myriocin to inhibit ceramide synthesis and tauroursodeoxycholic acid to prevent ER stress ameliorated PA plus MA induced apoptosis, similar to the protection afforded by the antioxidant BHA, the pan-caspase inhibitor z-VAD-Fmk and JNK inhibition. Moreover, ruthenium red protected PMH against PA and MA-induced cell death. Recapitulating in vitro findings, mice fed a diet enriched in PA plus MA exhibited lipodystrophy, hepatosplenomegaly, increased liver ceramide content and cholesterol levels, ER stress, liver damage, inflammation and fibrosis compared to mice fed diets enriched in PA or MA alone. The deleterious effects of PA plus MA-enriched diet were largely prevented by in vivo myriocin treatment. These findings indicate a causal link between ceramide synthesis and ER stress in lipotoxicity, and imply that the consumption of diets enriched in MA and PA can cause NASH associated with lipodystrophy

    Decoherence in a double-slit quantum eraser

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    We study and experimentally implement a double-slit quantum eraser in the presence of a controlled decoherence mechanism. A two-photon state, produced in a spontaneous parametric down conversion process, is prepared in a maximally entangled polarization state. A birefringent double-slit is illuminated by one of the down-converted photons, and it acts as a single-photon two-qubits controlled not gate that couples the polarization with the transversal momentum of these photons. The other photon, that acts as a which-path marker, is sent through a Mach-Zehnder-like interferometer. When the interferometer is partially unbalanced, it behaves as a controlled source of decoherence for polarization states of down-converted photons. We show the transition from wave-like to particle-like behavior of the signal photons crossing the double-slit as a function of the decoherence parameter, which depends on the length path difference at the interferometer.Comment: Accepted in Physical Review

    THE ROLE OF QMS IN THE RELATIONSHIP BETWEEN INNOVATION CLIMATE AND PERFORMANCE

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    The emergence of new global competitors, the convergence of high-technology industries and the increasing speed and cost of technological development promise an increasingly uncertain environment for organizations, making adaptation to changes in the environment a central theme in the study of the organization for both organization theory and strategic management. This paper is thus seeks principally to verify that, while innovation and QM alone do not possess the qualities required to provide organizations with sustainable competitive advantages, the bundle of innovation and QM together with other resources and competencies will allow organizations to obtain a competitive advantage and adapt to their environment. The results show that the factors determining innovation—such as resistance to change, cohesion, and workload pressures—have repercussions for the firms’ capacity to adapt to their environment, and that a QM context facilitates this adaptation. Finally, we can conclude that a climate of support for innovation is positively related to the organization’s performance

    Crónicas de una derrota. La vista del águila

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    Difícilmente se podría calificar de crisis de la cultura la actual sobreabundancia de ofertas culturales, la exigencia también creciente de la demanda o el mismo interés de los programadores en acertar con su público. Sin embargo, no siempre un aumento del consumo implica satisfacción. Cabría preguntarse, por supuesto, si ese cierto pesimismo que empieza a prender en los gestores culturales por los dudosos resultados, digamos educativos, de su trabajo, sólo lo padecen ellos y la general opinión es que, por el contrario, estamos en el buen camino de podar la cultura de cualquier voluntad social. Si así fuera, estas crónicas de una derrota, que todavía quiero creer provisional, serían más bien una necrológica. Y este tipo de iniciativas periféricas de poner en valor, y en cuestión, las ideas de cada gestor voluntarioso, una perfecta reserva india que se extinguirá sola por la degeneración de esas especies animales que sólo se cruzan con parientes. Pero tiempo habrá de hablar de nosotros.   Chronicles of a defeat. The view of the Eagle   Abstract: The current overabundance of cultural offerings, the also growing demand for demand or the same interest of programmers in hitting their audience could hardly be described as a cultural crisis. However, an increase in consumption does not always imply satisfaction. One might wonder, of course, if that certain pessimism that is beginning to ignite in cultural managers due to the dubious results, let's say educational, of their work, only they suffer and the general opinion is that, on the contrary, we are on the right track to prune the culture of any social will. If so, these chronicles of a defeat, which I still want to believe provisional, would be rather an obituary. And this type of peripheral initiatives to put in value, and in question, the ideas of each willful manager, a perfect Indian reservation that will become extinct by itself due to the degeneration of those animal species that only interbreed with relatives. But time will have to talk about us.    Artículo recibido: 07/04/2008. Aceptado: 09/06/2008      

    Control of quantum interference in the quantum eraser

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    We have implemented an optical quantum eraser with the aim of studying this phenomenon in the context of state discrimination. An interfering single photon is entangled with another one serving as a which-path marker. As a consequence, the visibility of the interference as well as the which-path information are constrained by the overlap (measured by the inner product) between the which-path marker states, which in a more general situation are non-orthogonal. In order to perform which-path or quantum eraser measurements while analyzing non-orthogonal states, we resort to a probabilistic method for the unambiguous modification of the inner product between the two states of the which-path marker in a discrimination-like process.Comment: Submitted to New Journal of Physics, March 200
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