526 research outputs found

    Class Size Reduction: A Facilitator of Instructional Program Coherence

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    This case study evaluation explored how class size reduction (CSR) combined with other reform initiatives and contextual factors to affect student achievement. The evaluand was an elementary school that implemented Wisconsin\u27s fortified CSR program named SAGE. Evidence was collected from existing records and purposively selected teachers via a focus group. A three-phase cut and paste analysis strategy was used to reduce data, display data, and draw and verify conclusions. Main and interaction effects are reported. Findings suggest smaller classes may affect student achievement by facilitating the coherence of school-level instructional programs

    Pictures in their minds : an analysis of student nurses' images of nursing

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    Examining the Cost-Outcome Relationship of a Fortified Class-Size Reduction Program

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    Class-size reduction initiatives have been criticized for producing modest achievement gains for the resources they consume. Wisconsinā€™s Student Achievement Guarantee in Education (SAGE) was designed to amplify the achievement benefits of smaller classes by requiring complementary changes in the teaching and learning environment and accountability for results. This study examined SAGE in an urban school district. The achievement benefits realized by the evaluand were marginalized by high per-student costs and similar performance of comparison groups on a state-mandated reading test. Suggestions for improving the cost-outcome relationship were presented

    A Comparative Study of Electoral Systems: Majoritarian Rules and Electoral Violence in Africa

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    An increasing trend of violent elections is undermining the former optimism over multi-party elections in Africa. Electoral systems are frequently associated with election violence, but the effects of different systems are relatively unknown. This study addresses this gap and assesses whether conditions for electoral violence are greater under certain electoral systems compared to others. Using a new time-series cross sectional (TSCS) dataset, I conduct an analysis of election violence in sub-Saharan Africa from 1995-2013. Overall, I find evidence for the violence-permitting nature of majoritarian systems, and the violence-constraining nature of proportional representation systems. These findings remain after controlling for the timing of violence (in relation to the election), the effect of informal institutions, and the presence of violence-mobilizing factors

    The causes and control of damping-off of tomato seedlings

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    K band Spectroscopy of Ultraluminous Infrared Galaxies: The 2 Jy Sample

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    We present near-infrared spectroscopy for a complete sample of 33 ultraluminous infrared galaxies at a resolution of R\approx 1000. Most of the wavelength range from 1.80-2.20 microns in the rest frame is covered, including the Pa-alpha and Br-gamma hydrogen recombination lines, and the molecular hydrogen vibration-rotation 1-0 S(1) and S(3) lines. Other species, such as He I, [Fe II], and [Si VI] appear in the spectra as well, in addition to a number of weaker molecular hydrogen lines. Nuclear extractions for each of the individual galaxies are presented here, along with spectra of secondary nuclei, where available. The Pa-alpha emission is seen to be highly concentrated on the nuclei, typically with very little emision extending beyond a radius of 1 kpc. Signatures of active nuclei are rare in the present sample, occurring in only two of the 33 galaxies. It is found that visual extinctions to the nuclei via the Pa-alpha/Br-gamma line ratio in excess of 10 magnitudes are relatively common among ULIRGs, and that visual extinctions greater than 25 mag are necessary to conceal a QSO emitting half the total bolometric luminosity. The vibration-rotation lines of molecular hydrogen appear to be predominantly thermal in origin, with effective temperatures generally around 2200 K. The relative nuclear velocities between double nucleus ULIRGs are investigated, through which it is inferred that the maximum deprojected velocity difference is about 200 km/s. This figure is lower than the velocities predicted by physical models of strong interactions/mergers of large, gas-rich galaxies.Comment: 52 pages (19 with just figures), 9 figures, accepted for publication in the Astronomical Journal; Table 3 not formatted properly on astro-ph: get source and print Murphy.tab3.p

    Fabrication and transport critical currents of multifilamentary MgB2/Fe wires and tapes

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    Multifilamentary MgB2/Fe wires and tapes with high transport critical current densities have been fabricated using a straightforward powder-in-tube (PIT) process. After annealing, we measured transport jc values up to 1.1 * 105 A/cm2 at 4.2 K and in a field of 2 T in a MgB2/Fe square wire with 7 filaments fabricated by two-axial rolling, and up to 5 * 104 A/cm2 at 4.2 K in 1 T in a MgB2/Fe tape with 7 filaments. For higher currents these multifilamentary wires and tapes quenched due to insufficient thermal stability of filaments. Both the processing routes and deformation methods were found to be important factors for fabricating multifilamentary MgB2 wires and tapes with high transport jc values.Comment: 13 pages, 7 figure

    EBImageā€”an R package for image processing with applications to cellular phenotypes

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    Summary: EBImage provides general purpose functionality for reading, writing, processing and analysis of images. Furthermore, in the context of microscopy-based cellular assays, EBImage offers tools to segment cells and extract quantitative cellular descriptors. This allows the automation of such tasks using the R programming language and use of existing tools in the R environment for signal processing, statistical modeling, machine learning and data visualization

    Effects of land markets and land management on ecosystem function: A framework for modelling exurban land-change

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    This paper presents the conceptual design and application of a new land-change modelling framework that represents geographical, sociological, economic, and ecological aspects of a land system. The framework provides an overarching design that can be extended into specific model implementations to evaluate how policy, land-management preferences, and land-market dynamics affect (and are affected by) land-use and land-cover change patterns and subsequent carbon storage and flux. To demonstrate the framework, we implement a simple integration of a new agent-based model of exurban residential development and land-management decisions with the ecosystem process model BIOME-BGC. Using a stylized scenario, we evaluate the influence of different exurban residential-land-management strategies on carbon storage at the parcel level over a 48-year period from 1958 to 2005, simulating stocks of carbon in soil, litter, vegetation, and net primary productivity. Results show 1) residential parcels with management practices that only provided additions in the form of fertilizer and irrigation to turfgrass stored slightly more carbon than parcels that did not include management practices, 2) conducting no land-management strategy stored more carbon than implementing a strategy that included removals in the form of removing coarse woody debris from dense tree cover and litter from turfgrass, and 3) the removal practices modelled had a larger impact on total parcel carbon storage than our modelled additions. The degree of variation within the evaluated land-management practices was approximately 42,104 kg C storage on a 1.62 ha plot after 48 years, demonstrating the substantial effect that residential land-management practices can have on carbon storag
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