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In recent years, many U.S. states have introduced growth models as part of their educational accountability systems. Although the validity of growth‐based accountability models has been evaluated for the general population, the impact of those models for English language learner (ELL) students, a growing segment of the student population, has not received sufficient attention. We evaluated three commonly used growth models: value tables or transition matrices, projection models, and student growth percentiles (SGP). The value table model identified more ELL students as on track to proficiency, but with lower accuracy for ELL students. The projection and SGP models were more accurate overall, but classified the fewest ELL students as on track and were less likely to identify ELL students who would later be proficient. We found that each model had significant trade‐offs in terms of the decisions made for ELL students. These findings should be replicated in additional state contexts and considered in the development of future growth‐based accountability policies. 相似文献
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EDITORS' PREFACE 总被引:1,自引:0,他引:1
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Attitudes and approaches toward the collection, use, and care of color photographs have evolved enormously since the official arrival of commercially viable color photographic processes in the early twentieth century. This article traces the evolution of collection, exhibition, and preservation practices for works of art in color photography over the last few decades, as represented by one institution, The Metropolitan Museum of Art. 相似文献
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Comparison of oil and egg tempera paint systems using time-of-flight secondary ion mass spectrometry
Zachary E. Voras Kristin deGhetaldi Brian Baade Eric Gordon Glenn Gates Thomas P. Beebe 《文物保护研究》2016,61(4):222-235
Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is quickly becoming a critical tool in the field of art conservation. This technique provides high-resolution spatial maps of both inorganic and organic components located within cross-sectional samples collected from works of art. With recent advances in surface analysis, ToF-SIMS can now be used to identify specific amino acids present in protein-containing materials as well as fatty acids in drying oils. For example, the detection of the ion fragment associated with the amino acid hydroxyproline can be used to confirm the use of animal glue in a paint sample. As an analytical technique, ToF-SIMS avoids the need for derivatization/silylation reagents, with no interference by the presence of pigments. Furthermore, the layered systems that are often encountered in historical paint samples remain intact throughout the analytical procedure. This allows for the co-localization of organic and inorganic species in specific layers (e.g. egg yolk paint atop a glue ground). Because of this ability to localize the analytical signal to approximately 6?µm or less, the mass spectral information can be used to produce mass-resolved and spatially-resolve images which can be correlated to previous studies of the same samples. In this study, ToF-SIMS was used to analyze a paint cross section obtained from a painting attributed to Raphael, and another from a painting by the Sienese artist Matteo di Giovanni. 相似文献
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