94,901 research outputs found

    Technique for producing bipolar and MOS field effect transistors on a single chip

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    Several cycles of photoetching, dopant deposition, and drive-in produce selectively-doped regions and semiconductor junctions within a single chip

    Glycosylphosphatidylinositols: More than just an anchor?

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    There is increasing interest in the role of glycosylphosphatidylinositol (GPI) anchors that attach some proteins to cell membranes. Far from being biologically inert, GPIs influence the targeting, intracellular trafficking and function of the attached protein. Our recent paper demonstrated the role of sialic acid on the GPI of the cellular prion protein (PrPC). The ā€œprion diseasesā€ arise following the conversion of PrPC to a disease-associated isoform called PrPSc or ā€œprionā€. Our paper showed that desialylated PrPC inhibited PrPSc formation. Aggregated PrPSc creates a signaling platform in the cell membrane incorporating and activating cytoplasmic phospholipase A2 (cPLA2), an enzyme that regulates PrPC trafficking and hence PrPSc formation. The presence of desialylated PrPC caused the dissociation of cPLA2 from PrP-containing platforms, reduced the activation of cPLA2 and inhibited PrPSc production. We concluded that sialic acid contained within the GPI attached to PrPC modifies local membrane microenvironments that are important in PrP-mediated cell signaling and PrPSc formation

    Non-destructive method for applying and removing instrumentation on helicopter rotor blades

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    A nondestructive method of applying and removing instrumentation on airfoils

    The color of sea level: importance of spatial variations in spectral shape for assessing the significance of trends

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    We investigate spatial variations in the shape of the spectrum of sea level variability, based on a homogeneously-sampled 12-year gridded altimeter dataset. We present a method of plotting spectral information as color, focusing on periods between 2 and 24 weeks, which shows that significant spatial variations in the spectral shape exist, and contain useful dynamical information. Using the Bayesian Information Criterion, we determine that, typically, a 5th order autoregressive model is needed to capture the structure in the spectrum. Using this model, we show that statistical errors in fitted local trends range between less than 1 and more than 5 times what would be calculated assuming ā€œwhiteā€ noise, and the time needed to detect a 1 mm/yr trend ranges between about 5 years and many decades. For global-mean sea level, the statistical error reduces to 0.1 mm/yr over 12 years, with only 2 years needed to detect a 1 mm/yr trend. We find significant regional differences in trend from the global mean. The patterns of these regional differences are indicative of a sea level trend dominated by dynamical ocean processes, over this perio

    Introduction to the Economics of Changing Markets and Evolving Technologies

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    Agricultural and Food Policy, International Relations/Trade, Marketing,

    Study of foldable elastic tubes for large space structure applications

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    Various modifications were made to the tube design. The tubes were retested and analyzed, and the results are presented. One type of modified tube, the slotted tube, deployed successfully and reliably, and became the focus of detailed tests. Optimal design criteria, taking into consideration deployment as well as strength and buckling behavior were established

    Study of foldable elastic tubes for large space structure applications, phase 1

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    Structural members that might be suitable for strain energy deployable structures, are discussed with emphasis on a thin-walled cylindrical tube with a cross-section that is called 'bi-convex'. The design of bi-convex tube test specimens and their fabrication are described as well as the design and construction of a special purpose testing machine to determine the deployment characteristics. The results of the first series of tests were quite mixed, but clearly revealed that since most of the specimens failed to deploy completely, due to a buckling problem, this type of tube requires some modification in order to be viable
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