12,979 research outputs found

    Online ready reference in the public library

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    Online computer databases can serve as excellent and cost effective resources for ready reference in public libraries. In the following discussion some philosophical and cost factors as well as staffing patterns connected with online searching will be examined. The primary source for this information comes from a three-year attempt to maximize usage of online searching, given existing cost constraints, in a medium-sized public library.published or submitted for publicatio

    Progress of research to identify rotating thunderstorms using satellite imagery

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    The possibility of detecting potentially tornadic thunderstorm cells from geosynchronous satelite imagery is determined. During the life of the contract, we examined eight tornado outbreak cases which had a total of 124 individual thunderstorm cells, 37 of which were tornadic.These 37 cells produced a total of 119 tornadoes. The outflow characteristics of all the cells were measured. Through the use of a 2-D flow field model, we were able to simulate the downstream developmemt of an anvil cloud plume which was emitted by the storm updraft at or near the tropopause. We used two parameters to characterize the anvil plume behavior: its speed of downstream propagation (U max) and the clockwise deviation of the centerline of the anvil plume from the storm relative ambient wind at the anvil plume outflow level (MDA). U max was the maximum U-component of the anvil wind parameter required to successfully maintain an envelope of translating particles at the tip of the expanding anvil cloud. MDA was the measured deviation angle acquired from McIDAS, between the storm relative ambient wind direction and the storm relative anvil plume outflow direction; tha latter being manipulated by controlling a tangential wind component to force the envelope of particles to maintain their position of surrounding the expanding outflow cloud

    An investigation of the detection of tornadic thunderstorms by observing storm top features using geosynchronous satellite imagery

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    The number of tornado outbreak cases studied in detail was increased from the original 8. Detailed ground and aerial studies were carried out of two outbreak cases of considerable importance. It was demonstrated that multiple regression was able to predict the tornadic potential of a given thunderstorm cell by its cirrus anvil plume characteristics. It was also shown that the plume outflow intensity and the deviation of the plume alignment from storm relative winds at anvil altitude could account for the variance in tornadic potential for a given cell ranging from 0.37 to 0.82 for linear to values near 0.9 for quadratic regression. Several predictors were used in various discriminant analysis models and in censored regression models to obtain forecasts of whether a cell is tornadic and how strong tornadic it could be potentially. The experiments were performed with the synoptic scale vertical shear in the horizontal wind and with synoptic scale surface vorticity in the proximity of the cell

    The Kadison-Singer problem for the direct sum of matrix algebras

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    Let MnM_n denote the algebra of complex n×nn\times n matrices and write MM for the direct sum of the MnM_n. So a typical element of MM has the form x=x1x2.˙.xn.˙.,x = x_1\oplus x_2 \... \oplus x_n \oplus \..., where xnMnx_n \in M_n and x=supnxn\|x\| = \sup_n\|x_n\|. We set D={{xn}M:xnD= \{\{x_n\} \in M: x_n is diagonal for all N}N\}. We conjecture (contra Kadison and Singer (1959)) that every pure state of DD extends uniquely to a pure state of MM. This is known for the normal pure states of D, and we show that this is true for a (weak*) open, dense subset of all the singular pure states of DD. We also show that (assuming the Continuum hypothesis) MM has pure states that are not multiplicative on any maximal abelian *-subalgebra of MM
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