Processing arctic eddy-flux data using a simple carbon-exchange model embedded in the ensemble Kalman filter

Author Posting. © Ecological Society of America, 2010. This article is posted here by permission of Ecological Society of America for personal use, not for redistribution. The definitive version was published in Ecological Applications 20 (2010): 1285–1301, doi:10.1890/09-0876.1.Continuous time-series estimates of net ecosystem carbon exchange (NEE) are routinely made using eddy covariance techniques. Identifying and compensating for errors in the NEE time series can be automated using a signal processing filter like the ensemble Kalman filter (EnKF). The EnKF compares each measurement in the time series to a model prediction and updates the NEE estimate by weighting the measurement and model prediction relative to a specified measurement error estimate and an estimate of the model-prediction error that is continuously updated based on model predictions of earlier measurements in the time series. Because of the covariance among model variables, the EnKF can also update estimates of variables for which there is no direct measurement. The resulting estimates evolve through time, enabling the EnKF to be used to estimate dynamic variables like changes in leaf phenology. The evolving estimates can also serve as a means to test the embedded model and reconcile persistent deviations between observations and model predictions. We embedded a simple arctic NEE model into the EnKF and filtered data from an eddy covariance tower located in tussock tundra on the northern foothills of the Brooks Range in northern Alaska, USA. The model predicts NEE based only on leaf area, irradiance, and temperature and has been well corroborated for all the major vegetation types in the Low Arctic using chamber-based data. This is the first application of the model to eddy covariance data. We modified the EnKF by adding an adaptive noise estimator that provides a feedback between persistent model data deviations and the noise added to the ensemble of Monte Carlo simulations in the EnKF. We also ran the EnKF with both a specified leaf-area trajectory and with the EnKF sequentially recalibrating leaf-area estimates to compensate for persistent model-data deviations. When used together, adaptive noise estimation and sequential recalibration substantially improved filter performance, but it did not improve performance when used individually. The EnKF estimates of leaf area followed the expected springtime canopy phenology. However, there were also diel fluctuations in the leaf-area estimates; these are a clear indication of a model deficiency possibly related to vapor pressure effects on canopy conductance.This material is based upon work supported by the U.S. National Science Foundation under grants OPP-0352897, DEB-0423385, DEB-0439620, DEB-0444592, and OPP- 0632139

A framework for evaluating edited cell libraries created by massively parallel genome engineering

AbstractGenome engineering methodologies are transforming biological research and discovery. Approaches based on CRISPR technology have been broadly adopted and there is growing interest in the generation of massively parallel edited cell libraries. Comparing the libraries generated by these varying approaches is challenging and researchers lack a common framework for defining and assessing the characteristics of these libraries. Here we describe a framework for evaluating massively parallel libraries of edited genomes based on established methods for sampling complex populations. We define specific attributes and metrics that are informative for describing a complex cell library and provide examples for estimating these values. We also connect this analysis to generic phenotyping approaches, using either pooled (typically via a selection assay) or isolate (often referred to as screening) phenotyping approaches. We approach this from the context of creating massively parallel, precisely edited libraries with one edit per cell, though the approach holds for other types of modifications, including libraries containing multiple edits per cell (combinatorial editing). This framework is a critical component for evaluating and comparing new technologies as well as understanding how a massively parallel edited cell library will perform in a given phenotyping approach.</jats:p

Global Law Schools on U.S. Models: Emerging Models of Consensus-Based Internationalization or Markets-Based Americanization Models of Global Legal Education

This article examines two substantially irreconcilable approaches to internationalization that are emerging in the United States. The first focuses on globalizing the law school curriculum through internationalization. This approach is congruent with emerging trends in legal education internationalization in Europe. The second approaches internationalization as a market driven competition for influence among dominant domestic legal orders, that is, as nationalist globalization. Internationalization is understood as the extension of the influence of national law outside the national territory and is nicely illustrated by recent efforts to globalize the law school curriculum by internationalizing the conventional U.S. law school curriculum. The principle thesis is this: The global legal education community, led by the Europeans, has been constructing a vision of globalization of legal education that has as its basis the idea of harmonization and convergence of different systems and the development of a new institutional model grounded in harmonized global trends in law. The United States appears to be taking two approaches to this development. After an Introduction, Part II examines the internationalization efforts of U.S. law schools following one of five models: (1) integration; (2) segregation; (3) aggregation; (4) immersion; and (5) multi-disciplinary department models. This project seeks a newer framework for the construction of shared legal structures grounded in joint effort that is not dominated by the approaches off any one state. Part III then examines the ways in which American institutions are also working against this general trend by positing a form of nationalist globalization that has as its foundation the idea that national legal education can go global without globalizing the law taught. Nationalist globalization takes three forms: a focus on the training of lawyers for domestic service whose pedagogical methodologies can be exported, the extraterritorial extension of the U.S. law school system, and the management of post graduate degrees in law for foreign law graduates. In place of harmonization and globalization of law, the American nationalist globalization model grounded in extraterritorial competition for socialization in the laws of the domestic legal order of dominant states. The article ends with an analysis of the consequences of these competing forms of global engagement in legal education. While much of the attention on changes to the American law school environment has focused on internationalization within consensus-based and supplementary programs founded on the internationalization ideal, American law schools have also been developing market-based strategies that are, at their core, fundamentally inconsistent with the internationalization framework.En este artículo se examina dos enfoques sustancialmente incompatibles de la interna-cionalización que están surgiendo en los Estados Unidos. La primera se centra en la globalización del currículo escolar a través de la ley de internacionalización. Este enfo-que es congruente con las nuevas tendencias en la internacionalización de la educa-ción legal en Europa. La internacionalización de los enfoques en segundo lugar como la competencia por el mercado por la influencia entre dominante ordenamientos jurídi-cos nacionales, es decir, la globalización nacionalista. La internacionalización es enten-dida como la extensión de la influencia de la legislación nacional fuera del territorio nacional y está muy bien ilustrado por los recientes esfuerzos para globalizar el currícu-lum escolar la ley por la internacionalización del derecho convencional EE.UU. currículo escolar. La tesis de principio es el siguiente: La comunidad global de educación legal, liderado por los europeos, ha sido la construcción de una visión de la globalización de la educación jurídica, que tiene como base la idea de la armonización y convergencia de los diferentes sistemas y el desarrollo de un nuevo modelo institucional basado en la armonización de las tendencias mundiales de la ley. Los Estados Unidos parecen estar tomando dos enfoques para este desarrollo. Por un lado, algunas instituciones están participando en la internacionalización de la educación. Sin embargo, las institu-ciones estadounidenses también están trabajando en contra de esta tendencia general al plantear una forma de globalización que tiene como fundamento la idea de que la enseñanza del derecho nacional puede ser globalizada y el rechazo de la necesidad de crear y enseñar derecho más allá del derecho nacional. En lugar de la armonización y la globalización del derecho, los estadounidenses de un modelo basado en la competen-cia extraterritorial para la socialización de las leyes del ordenamiento jurídico interno de los estados dominantes