S. Nemiah Ladd

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Growing concerns over the inadequate achievement of U.S. students have led to proposals to reward good teachers and penalize (or fire) bad ones. The leading method for assessing teacher quality is “value added” modeling (VAM), which decomposes students’ test scores into components attributed to student heterogeneity and to teacher quality. Implicit in the(More)
With the likelihood that carbon dioxide and other greenhouse-gas levels in the atmosphere will continue to increase for the next decades, and that the planet as a whole will likely warm as a result, we expect the oceanography and climate of the Galapagos to change. Based on an analysis of observational studies and climate models, the main changes are likely(More)
Hydrogen isotope ratios in lipids derived frommangroves have the potential to be used for paleohydrologic reconstructions and could serve as a much needed tool for establishing past climate variability in the tropics. We assessed the effect of salinity on the apparent fractionation factor, aa, between mangrove derived n-alkanes and their source water for(More)
For decades, colleges and universities have struggled to increase participation of minority and disadvantaged students. Urban school districts confront a parallel challenge; minority and disadvantaged students are underrepresented in selective programs that use merit-based admission. In their referral and admission policies to such selective programs,(More)
OBJECTIVE Correct labeling of twin fetuses is needed for consistency in assigning and interpreting longitudinal scan and prenatal screening/diagnostic results. The aim of this study was to describe a standard method of twin labeling in the first trimester of pregnancy and to assess the robustness of such a technique in predicting the presenting twin in(More)
Well-preserved sediment from closed water bodies of atolls such as Lib Pond are rare opportunities to reconstruct the past regional climate, which pieced together across a latitude and longitude range identify the range of movement patterns of wider scale climate phenomena such as the Intertropical Convergence Zone (ITCZ) and El Niño Southern Oscillation(More)
and UIUC, all of whom provided helpful comments and advice. Thanks also to Daniel Sheehan and Lisa Sweeney of GIS Services at MIT and David Cobb and Patrick Florance of the Harvard Map Library for creating the digital map images and teaching me how to use them. Abstract At the metropolitan level there is a striking negative correlation between residential(More)
Hydrogen isotope ratios ((2) H/(1) H, δ(2) H) of leaf waxes covary with those in precipitation and are therefore a useful paleohydrologic proxy. Mangroves are an exception to this relationship because their δ(2) H values are also influenced by salinity. The mechanisms underlying this response were investigated by measuring leaf lipid δ(2) H and leaf and(More)
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