1,409 research outputs found

    A trace inequality for Euclidean gravitational path integrals (and a new positive action conjecture)

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    The AdS/CFT correspondence states that certain conformal field theories are equivalent to string theories in a higher-dimensional anti-de Sitter space. One aspect of the correspondence is an equivalence of density matrices or, if one ignores normalizations, of positive operators. On the CFT side of the correspondence, any two positive operators A,BA,B will satisfy the trace inequality Tr(AB)Tr(A)Tr(B)\operatorname{Tr}(AB) \leq \operatorname{Tr}(A) \operatorname{Tr}(B). This relation holds on any Hilbert space H{\cal H} and is deeply associated with the fact that the algebra B(H)B({\cal H}) of bounded operators on H{\cal H} is a type I von Neumann factor. Holographic bulk theories must thus satisfy a corresponding condition, which we investigate below. In particular, we argue that the Euclidean gravitational path integral respects this inequality at all orders in the semi-classical expansion and with arbitrary higher-derivative corrections. The argument relies on a conjectured property of the classical gravitational action, which in particular implies a positive action conjecture for quantum gravity wavefunctions. We prove this conjecture for Jackiw-Teitelboim gravity and we also motivate it for more general theories.Comment: 65 pages, 14 figure

    Phorbol myristate acetate stimulates microtubule and 10-nm filament extension and lysosome redistribution in mouse macrophages

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    Phorbol myristate acetate (PMA) stimulates cell spreading and fluid-phase pinocytosis in mouse peritoneal macrophages. Colchicine (10(-5) M) and cytochalasin B (10(-5) M) abolish PMA stimulated pinocytosis but have little effect on cellular spreading (Phaire-Washington et al., 1980, J. Cell Biol., 86:634-640). We report here that PMA also alters the organization of the cytoskeleton and the distrubution of organelles in these cells. Neither control nor PMA-treated macrophages contain actin cables. PMA-treated resident thioglycolate-elicited macrophages exhibit beneath their substrate-adherent membranes many randomly distributed punctate foci that stain brightly for actin. The appearance and distribution of these actin-containing foci are not altered by colchicine (10(-5) M) or cytochalasin B (10(-5) M). In thioglycolate-elicited macrophages PMA causes the extension and radial organization of microtubules and 10-nm filaments and promotes the movement of secondary lysosomes from their perinuclear location to the peripheral cytoplasm. Depending upon the concentration of PMA used, 45-71% of thioglycolate-elicited macrophages and 32-44% of proteose-peptone-elicited macrophages and numerous lysosomes, radiating from the centrosphere region, arranged linearly along microtubule and 10-nm filament bundles. Colchicine (10(-5) M) and podophyllotoxin (10(-5) M) prevent the radial redistribution of microtubules, 10-nm filaments, and lysosomes in these cells. Cytochalasins B and D (10(-5) M) have no inhibitory effects on these processes. These findings indicate that microtubules and 10-nm filaments respond in a coordinated fashion to PMA and to agents that inhibit microtubule function; they suggest that these cytoskeletal elements regulate the movement and distribution of lysosomes in the macrophage cytoplasm

    Growth of Nitrogen-Containing Carbon Nanofibers

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    Nitrogen-containing nanofibers are lightweight, can be functionalized for electrical and thermal conductivity, and can be useful for mechanical reinforcement, which are properties that can be used for many practical applications. However, different metals and supports affect the structure of the carbon nanofibers that are formed. Different combinations of supports (MgO and SiO2) and metals (Co, Fe, Ni) were used as catalytic precursors to grow nitrogen-containing carbon nanofibers via acetonitrile decomposition. The products were analyzed using thermal gravimetric analysis (TGA), BET surface area/pore volume analysis (BET standing for Brunauer, Emmet, and Teller, the people who developed the technique for calculating surface area), temperature programmed acetonitrile pyrolysis (TPAP) analysis, temperature programmed oxidation (TPO) analysis, and transmission electron miscopy (TEM). MgO supports were easier to purify making it more favorable than SiO2. Co containing catalysts seemed to produce nanofibers with the highest nitrogen content, with Fe and Ni to follow. Fe and Co loaded catalysts yielded products with a stacked cup shape, which has easily functionalized edge planes. Diameter size distributions of the fibers grown seemed to be independent of the catalytic precursor; however, Co containing catalysts produced fibers with more uniform sizes. Following this study, fibers can now be produced with respect to specifications in shape, size, and nitrogen content.the NSFthe Wright Center for Innovatio

    Business rule extraction using decision tree machine learning techniques:A case study into smart returnable transport items

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    Decision support systems are becoming increasingly sophisticated (e.g., being machine learning-based), attempting to automate decisions as much as possible. However, it remains challenging to extract meaningful value from large quantities of data while also maintaining transparency in seeking justification for the choices made. Instead of creating methods for increasing the interpretability of black box models, one way forward is to design models that are inherently interpretable in the first place. Rule-based methods can automate decisions with great transparency and accuracy, helping to ensure compliance with regulations and adherence to organizational guidelines. In this paper, we propose an approach that uses a decision tree machine learning classification technique for extracting business rules from IoT-generated data to predict the asset status of Smart Returnable Transport Items (SRTIs). We report on an industrial case study that uses two years of historical data, obtained from an SRTI provider in the Netherlands, to predict the status of smart pallets. We compare the performance with the results obtained by using a support-vector machine (SVM) technique. Our experiments show that our solution is both accurate and flexible in terms of business rule elicitation. The obtained decision trees are human-interpretable, can easily be combined with other decision-making techniques, and provide a prediction accuracy marginally higher than an SVM technique

    Interferon suppresses pinocytosis but stimulates phagocytosis in mouse peritoneal macrophages: related changes in cytoskeletal organization

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    Treatment of thioglycolate-elicited macrophages with mouse beta-interferon markedly reduces pinocytosis of horseradish peroxidase and fluorescein isothiocyanate (FITC)-dextran but stimulates phagocytosis of IgG-coated sheep erythrocytes. Experiments with FITC-dextran have revealed that the overall decrease in pinocytosis is due to a nearly complete inhibition of pinocytosis in a large fraction of interferon-treated macrophages. In the remaining cells pinocytosis continues at a rate similar to that in untreated control cells. A considerable reduction in the number of cells pinocytosing FITC-dextran was observed within 12 h from the beginning of interferon treatment. Measurement of the overall level of pinocytic activity with horseradish peroxidase showed a progressive decline through 72 h of treatment. In the interferon-sensitive subpopulation, there were marked changes in cytoskeletal organization. Microtubules and 10-nm filaments were aggregated in the perinuclear region while most of the peripheral cytoplasm became devoid of these cytoskeletal structures as observed by fluorescence and electron microscopy. In addition, interferon treatment of macrophages appeared to disrupt the close topological association between bundles of 10-nm filaments and organelles such as mitochondria, lysosomes, and elements of the Golgi apparatus and endoplasmic reticulum. Such alterations in the distribution of microtubules and 10-nm filaments were not seen in the interferon-insensitive subpopulation. We have investigated the mechanism of the interferon-induced enhancement of phagocytic activity by binding IgG-coated sheep erythrocytes to mouse peritoneal macrophages at 4 degrees C and then initiating a synchronous round of ingestion by warming the cells to 37 degrees C. Thioglycolate-elicited macrophages that had been treated with mouse beta-interferon ingested IgG-coated erythrocytes faster and to a higher level than control cells in a single round of phagocytosis. In interferon-treated cultures, phagocytic cups became evident within 30 s of the shift of cultures from 4 degrees to 37 degrees C, whereas in control cultures, they appeared in 2 min. Cytochalasin D, an inhibitor of actin assembly and polymerization, abolished phagocytic activity in both control and beta-interferon-treated macrophages. However, to inhibit phagocytosis completely in thioglycolate-elicited interferon-treated macrophages, twice as much cytochalasin D was required in the treated as in control cultures.(ABSTRACT TRUNCATED AT 400 WORDS

    Factores clave en la eficiencia de intercambiadores de transporte

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    Los intercambiadores de transporte son pieza clave en la movilidad, en particular cuando se combinan viajes de larga distancia con los de acceso y dispersión. La buena conexión entre ambas partes de un viaje de larga distancia pueden hacer más o menos competitivas las alternativas de transporte público. En el proyecto HERMES del 7 PM de la UE, se ha analizado la eficiencia de varios intercambiadores de transporte. La primera parte del proyecto se centra en analizar la visión de diferentes stakeholders en el diseño, gestión y elementos del intercambiador. Por otra parte, se ha realizado una encuesta a viajeros en los intercambiadores de autobús y ferrocarril, permitiendo identificar la percepción de los usuarios sobre los elementos del intercambiador, así como sus pautas de movilidad de acceso y dispersión, en función de los servicios de transporte utilizados. Se han analizado qué elementos funcionales del intercambiador son más valorados, cuáles son los sistemas de información clave y qué otros servicios se demandan. Por otra parte, se han encontrado relaciones significativas entre algunas variables del viaje y de tipo socioeconómico, como modo principal con el de acceso y dispersión, modo con motivo de viaje y nivel de renta, etc. Se concluye que los intercambiadores deben tener un diseño específico dependiendo del tipo de usuario; así los viajeros del tren de alta velocidad valoran en primer lugar el tiempo de viaje y conexión, mientras que los de autobús valoran sobre todo los precios reducidos. La edad y ocupación de los usuarios también cambia. Los primeros realizan en su mayoría viajes de negocio y tienen una edad media superior a los 40 años, mientras que los de autobús viajan por motivos personales y son más jóvenes
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