34,352 research outputs found

    The FTC’s Annual Line-of-Business Reporting Program

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    Agent-based modeling: a systematic assessment of use cases and requirements for enhancing pharmaceutical research and development productivity.

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    A crisis continues to brew within the pharmaceutical research and development (R&D) enterprise: productivity continues declining as costs rise, despite ongoing, often dramatic scientific and technical advances. To reverse this trend, we offer various suggestions for both the expansion and broader adoption of modeling and simulation (M&S) methods. We suggest strategies and scenarios intended to enable new M&S use cases that directly engage R&D knowledge generation and build actionable mechanistic insight, thereby opening the door to enhanced productivity. What M&S requirements must be satisfied to access and open the door, and begin reversing the productivity decline? Can current methods and tools fulfill the requirements, or are new methods necessary? We draw on the relevant, recent literature to provide and explore answers. In so doing, we identify essential, key roles for agent-based and other methods. We assemble a list of requirements necessary for M&S to meet the diverse needs distilled from a collection of research, review, and opinion articles. We argue that to realize its full potential, M&S should be actualized within a larger information technology framework--a dynamic knowledge repository--wherein models of various types execute, evolve, and increase in accuracy over time. We offer some details of the issues that must be addressed for such a repository to accrue the capabilities needed to reverse the productivity decline

    Coherent structures: Comments on mechanisms

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    There is now overwhelming evidence that in most turbulent flows there exist regions moving with the flow where the velocity and vorticity have a characteristic structure. These regions are called coherent structures because within them the large-scale distributions of velocity and/or vorticity remain coherent even as these structures move through the flow and interact with other structures. Since the flow enters and leaves the bounding surfaces of these structures, a useful definition for coherent structures is that they are open volumes with distinctive large-scale vorticity distributions. Possible fruitful directions for the study of the dynamics of coherent structures are suggested. Most coherent structures research to data was concentrated on measurement and kinematical analysis; there is now a welcome move to examine the dynamics of coherent structures, by a variety of different methods. A few of them will be described

    Quantifying the Impact of Exogenous Non-Economic Factors on UK Transport Oil Demand

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    This paper attempts to quantify the impact of exogenous non-economic factors on UK transport oil demand (in addition to income, price, and fuel efficiency) by estimating the demand relationship for oil transport for 1960-2007 using the Structural Time Series Model. From this, the relative impact on UK transport oil demand from income, price, and efficiency are quantified. Moreover, the impact of the non-economic factors is also quantified, based on the premise that the estimated stochastic trend represents behavioural responses to changes in socio-economic factors and changes in lifestyles and attitudes. The estimated elasticities for income, price and efficiency are 0.6, -0.1, and -0.3 respectively and it is shown that for efficiency and price the overall contribution is relatively small, whereas the contribution from income and non-economic factors is relatively large. This has important implications for policy makers keen to reduce transport oil consumption and associated emissions, but not willing to reduce the trend rate of economic growth. Taxes and improved efficiency only have a limited impact; hence, a major thrust of policy should perhaps be on educating and informing consumers to persuade them to change their lifestyle and attitudes and thus reduce their consumption through the non-economic instruments route.Transport oil demand; Structural Time Series Model, STSM; Underlying Energy Demand Trend, UEDT; Exogenous Non-Economic Factors, ExNEF.

    Granular Flow in a Vertically Vibrating Hopper

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    The behavior of the flow of glass spheres in a vertically vibrating hopper is examined. A two-dimensional hopper is mounted on a shaker that provides sinusoidal, vertical vibrations. Both the frequency and amplitude of the vibrations are adjustable. Hopper discharge rates and flow patterns are measured as the acceleration amplitude of the vibrations is increased from 0 to 4g's. Comparisons are made with unvibrated hopper flows and with a two-dimensional discrete element simulation model

    Multimode interference devices for focusing in microfluidic channels

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    Low-cost, compact, automated optical microsystems for chemical analysis, such as microflow cytometers for identification of individual biological cells, require monolithically integrated microlenses for focusing in microfluidic channels, to enable high-resolution scattering and fluorescence measurements. The multimode interference device (MMI), which makes use of self-imaging in multimode waveguides, is shown to be a simple and effective alternative to the microlens for microflow cytometry. The MMIs have been designed, realized, and integrated with microfluidic channels in a silica-based glass waveguide material system. Focal spot sizes of 2.4 ”m for MMIs have been measured at foci as far as 43.7 ”m into the microfluidic channel
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