10,705 research outputs found

    A multiphase model describing vascular tumour growth

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    In this paper we present a new model framework for studying vascular tumour growth, in which the blood vessel density is explicitly considered. Our continuum model comprises conservation of mass and momentum equations for the volume fractions of tumour cells, extracellular material and blood vessels. We include the physical mechanisms that we believe to be dominant, namely birth and death of tumour cells, supply and removal of extracellular fluid via the blood and lymph drainage vessels, angiogenesis and blood vessel occlusion. We suppose that the tumour cells move in order to relieve the increase in mechanical stress caused by their proliferation. We show how to reduce the model to a system of coupled partial differential equations for the volume fraction of tumour cells and blood vessels and the phase averaged velocity of the mixture. We consider possible parameter regimes of the resulting model. We solve the equations numerically in these cases, and discuss the resulting behaviour. The model is able to reproduce tumour structure that is found `in vivo' in certain cases. Our framework can be easily modified to incorporate the effect of other phases, or to include the effect of drugs

    ANALYSIS OF MARKETING MARGINS IN THE U.S. LAMB INDUSTRY

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    Factors affecting marketing margins were identified and assessed using a relative price spread technique. Margins were disaggregated into slaughter-to-wholesale and wholesale-to-retail for a more complete understanding. Marketing costs, concentration, demand, and price were used to explain variations within these margins. Results showed that packer concentration had a significant effect on margins. Forces of supply and demand (as represented by production and market price) and changes in marketing costs also explained the variation in margins. A higher degree of price transmission from slaughter-to-wholesale level was observed in comparison to the wholesale-to-retail level.Marketing,

    Wave climate model of the Mid-Atlantic shelf and shoreline (Virginian Sea): Model development, shelf geomorphology, and preliminary results

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    A computerized wave climate model is developed that applies linear wave theory and shelf depth information to predict wave behavior as they pass over the continental shelf as well as the resulting wave energy distributions along the coastline. Reviewed are also the geomorphology of the Mid-Atlantic Continental Shelf, wave computations resulting from 122 wave input conditions, and a preliminary analysis of these data

    Laser application to measure vertical sea temperature and turbidity, design phase

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    An experiment to test a new method was designed, using backscattered radiation from a laser beam to measure oceanographic parameters in a fraction of a second. Tyndall, Rayleigh, Brillouin, and Raman scattering all are utilized to evaluate the parameters. A beam from a continuous argon ion laser is used together with an interferometer and interference filters to gather the information. The results are checked by direct measurements. Future shipboard and airborne experiments are described

    Modelling spatially regulated B-catenin dynamics & invasion in intestinal crypts

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    Experimental data (e.g., genetic lineage and cell population studies) on intestinal crypts reveal that regulatory features of crypt behavior, such as control via morphogen gradients, are remarkably well conserved among numerous organisms (e.g., from mouse and rat to human) and throughout the different regions of the small and large intestines. In this article, we construct a partial differential equation model of a single colonic crypt that describes the spatial distribution of Wnt pathway proteins along the crypt axis. The novelty of our continuum model is that it is based upon assumptions that can be directly related to processes at the cellular and subcellular scales. We use the model to predict how the distributions of Wnt pathway proteins are affected by mutations. The model is then extended to investigate how mutant cell populations can invade neighboring crypts. The model simulations suggest that cell crowding caused by increased proliferation and decreased cell loss may be sufficient for a mutant cell population to colonize a neighboring healthy crypt

    Development of the dry tape battery concept

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    High energy anode and cathode for dry tape battery - incapsulation of electrolyte - manufacturing and testing of devic

    Climate cosmopolitics and the possibilities for urban planning

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    Cosmopolitical action in a climate-changed city represents different knowledges and practices that may seem disconnected but constellate to frame stories and spaces of a climate-just city. The question this article asks is: how might we as planners identify and develop counter-hegemonic praxes that enable us to re-imagine our experience of, and responses to, climate change? To explore this question, we draw on Isabelle Stengers's (2010) idea of cosmopolitics-where diverse stories, perspectives, experiences, and practices can connect to create the foundation for new strategic possibilities. Our article is empirically informed by conversations with actors from three Australian cities (Sydney, Brisbane, and Perth) who are mobilizing different approaches to this ideal in various grassroots actions on climate change
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