4,731 research outputs found

    The Development of a School Board Policies Manual for the Campbell, Nebraska, Public School System

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    In recent years written statements of official school board policies have played an important role in the operation of public school systems. Relationship between boards of education and administrators, teachers, and non-certified personnel have been rapidly changing and have brought about the need for formal Board Policy Manuals rather than the informal, unwritten policy statements which had prevailed until recent years

    A smoke generator system for aerodynamic flight research

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    A smoke generator system was developed for in-flight vortex flow studies on the F-18 high alpha research vehicle (HARV). The development process included conceptual design, a survey of existing systems, component testing, detailed design, fabrication, and functional flight testing. Housed in the forebody of the aircraft, the final system consists of multiple pyrotechnic smoke cartridges which can be fired simultaneously or in sequence. The smoke produced is ducted to desired locations on the aircraft surface. The smoke generator system (SGS) has been used successfully to identify vortex core and core breakdown locations as functions of flight condition. Although developed for a specific vehicle, this concept may be useful for other aerodynamic flight research which requires the visualization of local flows

    Impact of ocean stratification on submarine melting of a major Greenland outlet glacier

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    Submarine melting is an important balance term for tidewater glaciers1,2 and recent observations point to a change in the submarine melt rate as a potential trigger for the widespread acceleration of outlet glaciers in Greenland3-5. Our understanding of the dynamics involved, and hence our ability to interpret past and predict future variability of the Greenland Ice Sheet, however, is severely impeded by the lack of measurements at the ice/ocean interface. To fill this gap, attempts to quantify the submarine melt rate and its variability have relied on a paradigm developed for tidewater glaciers terminating in fjords with shallow sills. In this case, the fjords’ waters are mostly homogeneous and the heat transport to the terminus, and hence the melt rate, is controlled by a single overturning cell in which glacially modified water upwells at the ice edge, driving an inflow at depth and a fresh outflow at the surface1. Greenland’s fjords, however, have deep sills which allow both cold, fresh Arctic and warm, salty Atlantic waters, circulating around Greenland, to reach the ice sheet margin3,6,7. Thus, Greenland’s glaciers flow into strongly stratified fjords and the generic tidewater glacier paradigm is not applicable. Here, using new summer data collected at the margins of Helheim Glacier, East Greenland, we show that melting is driven by both Atlantic and Arctic waters and that the circulation at the ice edge is organized in multiple, overturning cells that arise from their different properties. Multiple cells with different characteristics are also observed in winter, when glacial run off is at a minimum and there is little surface outflow. These results indicate that stratification in the fjord waters has a profound impact on the melting dynamics and suggest that the shape and stability of Greenland’s glaciers are strongly influenced by layering and variability in the Arctic and Atlantic waters. 


    A Computational Intelligence Approach to System-of-Systems Architecting Incorporating Multi-Objective Optimization

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    A computational intelligence approach to system-of-systems architecting is developed using multi-objective optimization. Such an approach yields a set of optimal solutions (the Pareto set) which has both advantages and disadvantages. The primary benefit is that a set of solutions provides a picture of the optimal solution space that a single solution cannot. The primary difficulty is making use of a potentially infinite set of solutions. Therefore, a significant part of this approach is the development of a method to model the solution set with a finite number of points allowing the architect to intelligently choose a subset of optimal solutions based on criteria outside of the given objectives. The approach developed incorporates a meta-architecture, multi-objective genetic algorithm, and a corner search to identify points useful for modeling the solution space. This approach is then applied to a network centric warfare problem seeking the optimum selection of twenty systems. Finally, using the same problem, it is compared to a hybrid approach using single-objective optimization with a fuzzy logic assessor to demonstrate the advantage of multi-objective optimization

    Inhibition of interleukin-1β-stimulated collagenase and stromelysin expression in human tendon fibroblasts by epigallocatechin gallate ester

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    The medicinal benefits of green tea (Camellia sinensis) consumption have been attributed to bioavailable polyphenols, notably epigallocatechin gallate (EGCG). We have assessed the effects of EGCG and its non-esterified counterpart EGC on the expression of the collagenases, matrix metalloproteinases (MMP)-1 and -13, and the stromelysin, MMP-3, in human tendon-derived fibroblasts. Interleukin (IL)-1ß increased MMP-1, -3 and -13 mRNA and output at least 30-fold. EGCG reduced this stimulation, by 20–30% at 2.5 µM and more than 80% at 25 µM, and had a smaller effect on MMP-2 mRNA expression, which was not stimulated by IL-1ß. In all experiments EGCG was at least 10-fold more potent than EGC. EGCG reduced the stimulation of p54 JNK/SAPK phosphorylation by IL-1ß but did not affect p38 MAPK phosphorylation, the degradation of I?B or the activating phosphorylation of NF?B. We conclude that EGCG reduces the IL-1-stimulated expression of both collagenase and stromelysin mRNA species, an effect which may be mediated by inhibition of the JNK/SAPK pathway. Taken together with previous reports of EGCG effects on the expression and/or activity of gelatinases and aggrecanases, our results underline the importance of extracellular matrix breakdown as a potential target for the actions of green tea polyphenols
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