4,998 research outputs found

    Guided Tissue Remineralization of Resin-Bonded Acid-Etched Dentin

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    Contemporary biomineralization strategies incorporate non-classical crystallization pathways of fluidic amorphous nanoprecursors and mesoscopic transformation. Using two functional biomimetic molecules, we previously regenerated mineralized dentin from acid-etched dentin using the Guided Tissue Remineralization (GTR) approach, with definitive intrafibrillar remineralization of type-I collagen. Degradation of denuded collagen within dentin adhesive resin-infiltrated dentin is a pertinent problem in dentin bonding. Here, we show that GTR provides a means of salvaging these degrading bonds by remineralizing resin-dentin interfaces. The GTR medium consists of a Portland cement/simulated body fluid that includes polyacrylic acid and polyvinylphosphonic acid biomimetic analogs for amorphous calcium phosphate dimension regulation and collagen targeting. Both interfibrillar and intrafibrillar apatites became readily discernible within the adhesive-bonded dentin after 2-4 months. Amorphous nanoprecursors created by GTR also penetrated the adhesive resin matrix to create nanocomposites. We anticipate GTR to be the starting point for more sophisticated strategies in extending the longevity of resin-dentin bonds

    Global and Regional Sources of Risk in Equity Markets: Evidence from Factor Models with Time-Varying Conditional Skewness

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    This study examines the influence of global and regional factors on the conditional distribution of stock returns from six Asian markets, using factor models in which unexpected returns comprise global, regional and local shocks. Besides conditional heteroskedasticity, the models allow shocks to have time-varying conditional skewness. The global factor appears less important for market volatility in models that permit time-varying conditional skewness. The influence of regional and global factors on risk is small in most of the markets, except in the late 1990s during which the regional factor accounted for a substantial portion of negative skewness in the markets' returns distribution.Asymmetries, Skewness, Volatility, Spillover, Stock returns

    Global and Regional Sources of Risk in Equity Markets: Evidence from Factor Models with Time-Varying Conditional Skewness

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    We examine the influence of global and regional factors on the conditional distribution of stock returns from six Asian markets, using factor models in which unexpected returns comprise global, regional and local shocks. The models allow for conditional heteroskedasticity and time-varying conditional skewness, and permit mean, variance and skewness spillovers to be measured. We find that the pattern of spillovers changed in the late 1990s. When spillovers are allowed to vary with the type of news arriving in a market, we find that local news reduces mean spillovers but increases variance spillovers. News about regional countries increases skewness spilloversAsymmetries, Skewness, Volatility, Spillover, Stock returns, News.

    Swinging and Tumbling of Fluid Vesicles in Shear Flow

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    The dynamics of fluid vesicles in simple shear flow is studied using mesoscale simulations of dynamically-triangulated surfaces, as well as a theoretical approach based on two variables, a shape parameter and the inclination angle, which has no adjustable parameters. We show that between the well-known tank-treading and tumbling states, a new ``swinging'' state can appear. We predict the dynamic phase diagram as a function of the shear rate, the viscosities of the membrane and the internal fluid, and the reduced vesicle volume. Our results agree well with recent experiments.Comment: 4 pages, 4 figure

    The hydrodynamics of the southern basin of Tauranga Harbour

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    The circulation of the southern basin of Tauranga Harbour was simulated using a 3-D hydrodynamic model ELCOM. A 9-day field campaign in 1999 provided data on current velocity, temperature and salinity profiles at three stations within the main basin. The tidal wave changed most in amplitude and speed in the constricted entrances to channels, for example the M2 tide attenuated by 10% over 500 m at the main entrance, and only an additional 17% over the 15 km to the top of the southern basin. The modelled temperature was sensitive to wind mixing, particularly in tidal flat regions. Residence times ranged from 3 to 8 days, with higher residence times occurring in sub-estuaries with constricted mouths. The typical annual storm events were predicted to reduce the residence times by 24%–39% depending on season. Model scenarios of storm discharge events in the Wairoa River varying from 41.69 m3/s to 175.9 m3/s show that these events can cause salinity gradients across the harbour of up to 4 PSU

    Multivariate dynamic kernels for financial time series forecasting

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    The final publication is available at http://link.springer.com/chapter/10.1007/978-3-319-44781-0_40We propose a forecasting procedure based on multivariate dynamic kernels, with the capability of integrating information measured at different frequencies and at irregular time intervals in financial markets. A data compression process redefines the original financial time series into temporal data blocks, analyzing the temporal information of multiple time intervals. The analysis is done through multivariate dynamic kernels within support vector regression. We also propose two kernels for financial time series that are computationally efficient without a sacrifice on accuracy. The efficacy of the methodology is demonstrated by empirical experiments on forecasting the challenging S&P500 market.Peer ReviewedPostprint (author's final draft

    Trace Metal Concentrations in Commercially Important Fishes from some Coastal and Inland Waters in Ghana

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    An assessment was conducted on the concentrations of zinc, copper, manganese, iron, lead and cadmium in 10 different fish species caught from some coastal and inland waters in Ghana, as part of a project on monitoring of pollution in water bodies in Ghana. Shellfish species (Egeria paradoxa galanata and Atya gabonensis) caught from inland waters had higher elemental concentrations than those caught from coastal waters. Mean concentrations of Fe and Mn were higher in E. paradoxa galanata, A. gabonensis and Trachiurus trachiurus, while Panulirus regius and Sardinella eba had higher mean concentrations of Cu. T. trachiurus, Dentex congoensis and T. ovatus had higher mean concentrations of Pb, while T. trachiurus and S. eba had higher mean concentrations of Zn. Mean Cd concentrations in the fish species were relatively low, with mean concentrations of Cynoglossus cadenati, D. congoensis and T. ovatus below detection limits. The mean concentrations of Zn, Cu, Pb and Cd for shell fishes were comparable to those obtained from previous studies in Ghana. However, they were lower than those reported in other areas of the sub-region. The mean concentrations of Zn, Cu, Pb and Cd in fin fishes were higher than those obtained from previous studies in Ghana. However, these values were comparable to those obtained from other areas in the sub-region. Compared to WHO limits, the levels of Zn, Pb, Cu and Cd in the fish species were lower, and, therefore, safe for human consumption. The study also showed that all the fish species except S. eba, Solar crumophthalmus and P. regius are safe for human consumption with respect to Zn, Cu and Fe.West African Journal of Applied Ecology Vol. 13 2008: pp. 27-3

    Video Marketing Strategies for Generation Z

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    If Generation Z is the first generation of digital natives, what is the best strategy for marketing college recruitment to them? Video marketing has been proven to be the most profitable form of marketing, especially short videos that can easily be spread on social media. Generation Z connects with a university most when they are able to see themselves reflected back in a diverse student body. Generation Z doesn\u27t like fluff in their university recruitment marketing; this money-minded generation wants to see that they will quickly be able to get a job, internship, or campus opportunities to advance their career. As of the 2019-2020 school year, college campuses are officially majority Generation Z. Colleges and universities need to adjust their marketing strategies for this new generation

    Red blood cells and other non-spherical capsules in shear flow: oscillatory dynamics and the tank-treading-to-tumbling transition

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    We consider the motion of red blood cells and other non-spherical microcapsules dilutely suspended in a simple shear flow. Our analysis indicates that depending on the viscosity, membrane elasticity, geometry and shear rate, the particle exhibits either tumbling, tank-treading of the membrane about the viscous interior with periodic oscillations of the orientation angle, or intermittent behavior in which the two modes occur alternately. For red blood cells, we compute the complete phase diagram and identify a novel tank-treading-to-tumbling transition at low shear rates. Observations of such motions coupled with our theoretical framework may provide a sensitive means of assessing capsule properties.Comment: 11 pages, 4 figure
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