2,592 research outputs found

    Three-dimensional wakes in linearly stratified liquids.

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    Massachusetts Institute of Technology. Dept. of Civil Engineering. Thesis. 1966. M.S.MICROFICHE COPY ALSO AVAILABLE IN BARKER ENGINEERING LIBRARY.Bibliography: p. 80.M.S

    Plant evolution:Streptophyte multicellularity, ecology, and the acclimatisation of plants to life on land

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    Land plants are celebrated as one of the three great instances of complex multicellularity, but new phylogenomic and phenotypic analyses are revealing deep evolutionary roots of multicellularity among algal relatives, prompting questions about the causal basis of this major evolutionary transitio

    Occurrence of the Brackish Water Asellote Isopod Munna (Uromunna) reynoldsi in Texas

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    The asellote isopod Munna (Uromunna) reynoldsi Frankenberg and Menzies, previously known from coastal swamps a t Sapelo Island, Georgia, is reported from Texas. Several specimens were collected in grab samples from Fence Lake, a small brackish marsh lake (salinity 0 to 2.7 ppt) in Sca Rim State Park, and in a nearby coastal marsh (salinity 4.4 ppt). The present records indicate that the species is a brackish water form

    Occurrence of the Brackish Water Asellote Isopod Munna (Uromunna) reynoldsi in Texas

    Get PDF
    The asellote isopod Munna (Uromunna) reynoldsi Frankenberg and Menzies, previously known from coastal swamps a t Sapelo Island, Georgia, is reported from Texas. Several specimens were collected in grab samples from Fence Lake, a small brackish marsh lake (salinity 0 to 2.7 ppt) in Sca Rim State Park, and in a nearby coastal marsh (salinity 4.4 ppt). The present records indicate that the species is a brackish water form

    Electron impact ionization loading of a surface electrode ion trap

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    We demonstrate a method for loading surface electrode ion traps by electron impact ionization. The method relies on the property of surface electrode geometries that the trap depth can be increased at the cost of more micromotion. By introducing a buffer gas, we can counteract the rf heating assocated with the micromotion and benefit from the larger trap depth. After an initial loading of the trap, standard compensation techniques can be used to cancel the stray fields resulting from charged dielectric and allow for the loading of the trap at ultra-high vacuum.Comment: 4 pages, 5 eps figures. Shift in focus, minor correction

    Size isn’t everything:rates of genome size evolution, not C value, correlate with speciation in angiosperms

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    Angiosperms represent one of the key examples of evolutionary success, and their diversity dwarfs other land plants; this success has been linked, in part, to genome size and phenomena such as whole genome duplication events. However, while angiosperms exhibit a remarkable breadth of genome size, evidence linking overall genome size to diversity is equivocal, at best. Here, we show that the rates of speciation and genome size evolution are tightly correlated across land plants, and angiosperms show the highest rates for both, whereas very slow rates are seen in their comparatively species-poor sister group, the gymnosperms. No evidence is found linking overall genome size and rates of speciation. Within angiosperms, both the monocots and eudicots show the highest rates of speciation and genome size evolution, and these data suggest a potential explanation for the megadiversity of angiosperms. It is difficult to associate high rates of diversification with different types of polyploidy, but it is likely that high rates of evolution correlate with a smaller genome size after genome duplications. The diversity of angiosperms may, in part, be due to an ability to increase evolvability by benefiting from whole genome duplications, transposable elements and general genome plasticity

    Fiber optic temperature sensor

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    A fiber optic temperature sensor uses a light source which transmits light through an optical fiber to a sensor head at the opposite end of the optical fiber from the light source. The sensor head has a housing coupled to the end of the optical fiber. A metallic reflective surface is coupled to the housing adjacent the end of the optical fiber to form a gap having a predetermined length between the reflective surface and the optical fiber. A detection system is also coupled to the optical fiber which determines the temperature at the sensor head from an interference pattern of light which is reflected from the reflective surface
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