2,030 research outputs found
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Characterization of atomic and molecular impurity sources and transport at the tokamak edge
The characterization of impurity sources in the tokamak edge is challenging because of the highly localized nature of impurity generation. Detailed, spatially resolved, diagnostic information is needed, and three-dimensional (3-D) modeling is required for interpretation. There is also a need for a more extensive atomic and molecular data base for the conditions encountered in this region. The availability of new measurements of photon efficiencies for some relevant hydrocarbon molecules for plasma conditions typical for the tokamak edge and the development of a 3-D Monte Carlo impurities code have enabled the successful modeling of spatially resolved measurements in the vicinity of the pump limiter neutralizer plate and near the inner wall of Tore Supra
The Evolution of Grocery Wholesaling and Grocery Wholesalers in Ireland and Britain since the 1930s
Studies of industry evolution are relatively scarce outside of industries defined by narrow technological bases. Studies of wholesaling are rarer still. These are curious features given that it is probable that service industries behave differently to manufacturing ones and that wholesaling is such a key function of many economies. This paper looks at the evolution of grocery wholesaling and grocery wholesalers in Ireland and Britain since 1930. It focuses on the processes and drivers of the wholesale industry. Similarities and differences between the two countries are discussed. Particular emphasis is placed on the role of government action as a triggering mechanism for change and on the role of trade associations and industry leaders in developing and following through on market and non-market strategies. The pathways of industry evolution identified differ from those seen in manufacturing. They therefore raise a number of issues for the development of understanding and conceptualisation in industry evolution studies
Innovation and the creative destruction of trade :Â a study of the intensive and extensive margins of trade for French firms
Our study of French exporters examines the causal relationship between innovation and extensive and intensive margins of trade using a propensity score matching and differenceâinâdifferences approach. Results show innovation has a positive impact on total exports driven primarily through the intensive margin. To understand the absence of an extensive margin effect, we show new and terminated productâcountry transactions increase at similar rates in the year of innovation for the treated and control groups but net trade creation for innovators outstrips that of nonâinnovators in the following two years implying firms need to innovate in order to survive in export markets
Churn, Baby, Churn: Strategic Dynamics Among Dominant and Fringe Firms in a Segmented Industry
This paper integrates and extends the literatures on industry evolution and dominant firms to develop a dynamic theory of dominant and fringe competitive interaction in a segmented industry. It argues that a dominant firm, seeing contraction of growth in its current segment(s), enters new segments in which it can exploit its technological strengths, but that are sufficiently distant to avoid cannibalization. The dominant firm acts as a low-cost Stackelberg leader, driving down prices and triggering a sales takeoff in the new segment. We identify a âchurnâ effect associated with dominant firm entry: fringe firms that precede the dominant firm into the segment tend to exit the segment, while new fringe firms enter, causing a net increase in the number of firms in the segment. As the segment matures and sales decline in the segment, the process repeats itself. We examine the predictions of the theory with a study of price, quantity, entry, and exit across 24 product classes in the desktop laser printer industry from 1984 to 1996. Using descriptive statistics, hazard rate models, and panel data methods, we find empirical support for the theoretical predictions
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Visible spectroscopy in the DIII-D divertor
Spectroscopy measurements in the DIII-D divertor have been carried out with a survey spectrometer which provides simultaneous registration of the visible spectrum over the region 400--900 nm with a resolution of 0.2 nm. Broad spectral coverage is achieved through use of a fiberoptic transformer assembly to map the curved focal plane of a fast (f/3) Rowland-circle spectrograph into a rastered format on the rectangular sensor area of a two-dimensional CCD camera. Vertical grouping of pixels during CCD readout integrates the signal intensity over the height of each spectral segment in the rastered image, minimizing readout time. For the full visible spectrum, readout time is 50 ms. Faster response time (< 10 ms) may be obtained by selecting for readout just a small number of the twenty spectral segments in the image on the CCD. Simultaneous recording of low charge states of carbon, oxygen and injected impurities has yielded information about gas recycling and impurity behavior at the divertor strike points. Transport of lithium to the divertor region during lithium pellet injection has been studied, as well as cumulative deposition of lithium on the divertor targets from pellet injection over many successive discharges
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