11,836 research outputs found

    Mediators of Inequity: Online Literate Activity in Two Eighth Grade English Language Arts Classes

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    This comparative case study, framed by Cultural Historical Activity Theory and sociocultural understandings of literacy, investigated students’ online literate activity in two eighth grade English Language Arts classes taught by the same teacher - one with a scripted literacy curriculum and the other without. During a year-long research project, we used ethnographic methods to explore the nature of middle school students’ literate activity in each of these classes, with particular attention to the mediators evident as students engaged in online literate activity. Specifically, this article addresses the following research question: What mediators were evident within and across each of the classes and how did these mediators influence students’ online literate activity? In addressing this question, we illustrate how particular configurations of mediators – even those operating within the context of the same school and same teacher – significantly influenced the nature of students’ online literate activity and the literate identities available to students. This study reinforces the importance of attending to the influence of offline mediators in school settings. Without such attention, students’ formal education is likely to be transferred online rather than transformed online

    Further studies of methods for reducing community noise around airports

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    A simplified method of analysis was used in which all flights at a 'simulated' airport were assumed to operate from one runway in a single direction. For this simulated airport, contours of noise exposure forecast were obtained and evaluated. A flight schedule of the simulated airport which is representative of the 23 major U. S. airports was used. The effect of banning night-time operations by four-engine, narrow-body aircraft in combination with other noise reduction options was studied. The reductions in noise which would occur of two- and three-engine, narrow-body aircraft equipped with a refanned engine was examined. A detailed comparison of the effects of engine cutback on takeoff versus the effects of retrofitting quiet nacelles for narrow-body aircraft was also examined. A method of presenting the effects of various noise reduction options was treated

    Experiments in free shear flows: Status and needs for the future

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    Experiments in free turbulent flows are recommended with the primary concern placed on classical flows in order to augment understanding and for model building. Five classes of experiments dealing with classical free turbulent flows are outlined and proposed as being of particular significance for the near future. These classes include the following: (1) Experiments clarifying the effect of density variation owing to use of different gases, with and without the additional effect of density variation due to high Mach number or other effects; (2) experiments clarifying the role and importance of various parameters which determine the behavior of the near field as well as the condictions under which any of these parameters can be neglected; (3) experiments determining the cumulative effect of initial conditions in terms of distance to fully established flow; (4) experiments for cases where two layers of distinctly different initial turbulence structure flow side by side at the same mean speed; and (5) experiment using contemporary experimental techniques to study structure in free turbulent shear flows in order to compliment and support contemporary work on boundary layers

    Effect of well-width on the electro-optical properties of a quantum well

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    We record photoreflectance from Ge/GeSi modulation doped quantum wells possessing 10410^4 V/cm perpendicular electric fields. Qualitatively very different spectra are obtained from samples of well-width 100 \AA and 250 \AA. Comparing the wavefunctions calculated from an 8×88 \times 8 \textbf{k.p} theory, we find that while they remain confined in the narrower 100 \AA QW, the electric field causes them to tunnel into the forbidden gap in the 250 \AA\ well. This implies that the samples should show a transition from the quantum confined Franz-Keldysh effect to the bulk-like Franz-Keldysh effect. Close to the band-edge where Franz-Keldysh effects are important, simulated photoreflectance spectra reproduce the essential features of the experiment, without any adjustable parameters.Comment: 8 pages, 8 figures. Submitted to Phys. Rev.

    Two-dimensional cascade investigation of a turbine tandem blade design

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    Flow and wake characteristics on turbine tandem blades in two dimensional cascade tunne

    Grown organic matter as a fuel raw material resource

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    An extensive search was made on biomass production from the standpoint of climatic zones, water, nutrients, costs and energy requirements for many species. No exotic species were uncovered that gave hope for a bonanza of biomass production under culture, location, and management markedly different from those of existing agricultural concepts. A simulation analysis of biomass production was carried out for six species using conventional production methods, including their production costs and energy requirements. These estimates were compared with data on food, fiber, and feed production. The alternative possibility of using residues from food, feed, or lumber was evaluated. It was concluded that great doubt must be cast on the feasibility of producing grown organic matter for fuel, in competition with food, feed, or fiber. The feasibility of collecting residues may be nearer, but the competition for the residues for return to the soil or cellulosic production is formidable

    Storing Flaxseed in Farm-type Bins in South Texas.

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    Pipette cleaning in automated systems

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    Low-dimensional dynamics embedded in a plane Poiseuille flow turbulence : Traveling-wave solution is a saddle point ?

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    The instability of a streak and its nonlinear evolution are investigated by direct numerical simulation (DNS) for plane Poiseuille flow at Re=3000. It is suggested that there exists a traveling-wave solution (TWS). The TWS is localized around one of the two walls and notably resemble to the coherent structures observed in experiments and DNS so far. The phase space structure around this TWS is similar to a saddle point. Since the stable manifold of this TWS is extended close to the quasi two dimensional (Q2D) energy axis, the approaching process toward the TWS along the stable manifold is approximately described as the instability of the streak (Q2D flow) and the succeeding nonlinear evolution. Bursting corresponds to the escape from the TWS along the unstable manifold. These manifolds constitute part of basin boundary of the turbulent state.Comment: 5 pages, 6 figure
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