5,976 research outputs found

    Chemistry and Apparent Quality of Surface Water and Ground Water Associated with Coal Basins

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    Personnel of the Arkansas Mining and Mineral Resources Research Institute conducted preliminary investigations on the chemistry and quality of surface and ground water associated with 12 coal-bearing sub-basins in the Arkansas Valley coal field. The coal field is approximately 60 miles long and 33 miles wide but only in 12 areas coal is thick enough and has proper quality to be termed commercial. Both surface and underground sample sites were established in each of the sub-basins with some minor variations in four areas where not all types of sites could be located. Water was collected from 19 surface points and 19 underground points in the established areas. Both field and laboratory analyses were made and elemental contents are reported herein. In the main, the chemistry and water quality suggests that all water is suitable for agricultural and industrial uses. To obtain potable water, treatment must be made to reduce calcium, magnesium, sodium sulfate and iron. The mineral content of the water is due to its contact with coal-bearing zones and, as such, reflects the mineral content of the coal. However, it is recommended that additional studies on the petrography and geochemistry of the coal, overburden and underburden is in order. Also, it is recommended that at least one detailed study be made of one of the coal sub-basins where geologic parameters can be completely established with regard to hydrogeology. This report is an important first step in determining the character and quality of Arkansas coal which must be fully understood to fully utilize this important mineral resource

    Variability in wrist-tilt accelerometer based gesture interfaces

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    In this paper we describe a study that examines human performance in a tilt control targeting task on a PDA. A three-degree of freedom accelerometer attached to the base of the PDA allows users to navigate to the targets by tilting their wrist in different directions. Post hoc analysis of performance data has been used to classify the ease of targeting and variability of movement in the different directions. The results show that there is an increase in variability of motions upwards from the centre, compared to downwards motions. Also the variability in the x axis component of the motion was greater than that in the y axis. This information can be used to guide designers as to the ease of various relative motions, and can be used to reshape the dynamics of the interaction to make each direction equally easy to achieve

    State Humanities Committees (1979-1982): Correspondence 20

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    Treatment of peptic ulcer

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    Isolation of mip (microtubule interacting protein) mutations of Aspergillus nidulans

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    This is the publisher's version, also available electronically from "http://mcb.asm.org".We identified four mutations in two previously undescribed loci involved in microtubule function in Aspergillus nidulans as extragenic suppressors of benA33, a heat-sensitive beta-tubulin mutation. Three of the four mutations map to a locus closely linked to riboB on linkage group VIII; we designated this locus mipA (for microtubule-interacting protein). We were not able to map the remaining suppressor because of chromosomal rearrangements. However, since it recombines with riboB at a significantly higher frequency than the mipA alleles, it is unlikely to be in mipA; thus, we designated it mipB1. The mip mutations are not allelic to the previously identified loci that encode alpha- and beta-tubulin, and it is likely that mipA and mipB encode previously unidentified nontubulin proteins involved in microtubule function. Each of the mip mutations suppresses the heat sensitivity conferred by benA33 and suppresses the blockage of nuclear division and movement conferred by this mutation at high temperatures. Interactions between mipA and benA are allele specific. All of the mipA mutations are cryptic in a wild-type benA background but cause cold sensitivity in combination with benA33. These mutations also confer cold sensitivity in combination with benA31 and benA32 and reduce the resistance conferred by these mutations to the antimicrotubule agent benomyl but do not suppress the heat sensitivity conferred by these alleles. Finally, the mipA alleles suppress the heat sensitivity conferred by benA11, benA17, and benA21 but do not confer cold sensitivity in combination with these alleles

    Shock accelerated vortex ring

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    The interaction of a shock wave with a spherical density inhomogeneity leads to the development of a vortex ring through the impulsive deposition of baroclinic vorticity. The present fluid dynamics videos display this phenomenon and were experimentally investigated at the Wisconsin Shock Tube Laboratory's (WiSTL) 9.2 m, downward firing shock tube. The tube has a square internal cross-section (0.25 m x 0.25 m) with multiple fused silica windows for optical access. The spherical soap bubble is generated by means of a pneumatically retracted injector and released into free-fall 200 ms prior to initial shock acceleration. The downward moving, M = 2.07 shock wave impulsively accelerates the bubble and reflects off the tube end wall. The reflected shock wave re-accelerates the bubble (reshock), which has now developed into a vortex ring, depositing additional vorticity. In the absence of any flow disturbances, the flow behind the reflected shock wave is stationary. As a result, any observed motion of the vortex ring is due to circulation. The shocked vortex ring is imaged at 12,500 fps with planar Mie scattering.Comment: For Gallery of Fluid Motion 200

    A mutation in aspergillus nidulans that blocks the transition from interphase to prophase

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    In order to develop a method for obtaining mitotic synchrony in aspergillus nidulans, we have characterized previously isolated heat-sensitive nim mutations that block the nuclear division cycle in interphase at restrictive temperature. After 3.5 h at restrictive temperature the mitotic index of a strain carrying one of these mutations, nimA5, was 0, but when this strain was subsequently shifted from restrictive to permissive temperature the mitotic index increased rapidly, reaching a maximum of 78 percent after 7.5 min. When this strain was examined electron-microscopically, mitotic spindles were absent at restrictive temperature. From these data we conclude that at restrictive temperature nimA5 blocks the nuclear division cycle at a point immediately preceding the initiation of chromosomal condensation and mitotic microtubule assembly, and upon shifting to permissive control over the initiation of microtubule assembly and chromosomal condensation in vivo through a simple temperature shift and, consequently, nimA5 should be a powerful tool for studying these processes. Electron-microscopic examination of spindles of material synchronized in this manner reveals that spindle formation, although very rapid, is gradual in the sense that spindle microtubule numbers increase as spindle formation proceeds

    Provenance Threat Modeling

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    Provenance systems are used to capture history metadata, applications include ownership attribution and determining the quality of a particular data set. Provenance systems are also used for debugging, process improvement, understanding data proof of ownership, certification of validity, etc. The provenance of data includes information about the processes and source data that leads to the current representation. In this paper we study the security risks provenance systems might be exposed to and recommend security solutions to better protect the provenance information.Comment: 4 pages, 1 figure, conferenc

    The role of microtubules in rapid hyphal tip growth of Aspergillus nidulans

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    This is the publisher's version, also available electronically from "http://www.molbiolcell.org".The filamentous fungus Aspergillus nidulans grows by polarized extension of hyphal tips. The actin cytoskeleton is essential for polarized growth, but the role of microtubules has been controversial. To define the role of microtubules in tip growth, we used time-lapse microscopy to measure tip growth rates in germlings of A. nidulans and in multinucleate hyphal tip cells, and we used a green fluorescent protein-α-tubulin fusion to observe the effects of the antimicrotubule agent benomyl. Hyphal tip cells grew ≈5 times faster than binucleate germlings. In germlings, cytoplasmic microtubules disassembled completely in mitosis. In hyphal tip cells, however, microtubules disassembled through most of the cytoplasm in mitosis but persisted in a region near the hyphal tip. The growth rate of hyphal tip cells did not change significantly in mitosis. Benomyl caused rapid disassembly of microtubules in tip cells and a 10× reduction in growth rate. When benomyl was washed out, microtubules assembled quickly and rapid tip growth resumed. These results demonstrate that although microtubules are not strictly required for polarized growth, they are rate-limiting for the growth of hyphal tip cells. These data also reveal that A. nidulans exhibits a remarkable spatial regulation of microtubule disassembly within hyphal tip cells
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