Navigating the Turbulent Waters of School Reform Guided by Complexity Theory

The goal of this research study has been to develop, implement, and evaluate a school reform design experiment at a continuation high school with low-income, low-performing underrepresented minority students. The complexity sciences served as a theoretical framework for this design experiment. Treating an innovative college preparatory program as a nested complex adaptive system within a larger complex adaptive system, the school, we used features of complex adaptive systems (equilibrium, emergence, self-organization, and feedback loops) as a framework to design a strategy for school reform. The goal was to create an environment for change by pulling the school far from equilibrium using a strategy we call “purposeful perturbations” to disrupt the stable state of the school in a purposeful way. Over the four years of the study, several tipping points were reached, and we developed agent-based simulation models that capture important dynamic properties of the reform at these points. The study draws upon complexity theory in multiple ways that have supported improved education for low-achieving students

Some Heteroskedasticity Consistent Covariance Matrix Estimators with Improved Finite Sample Properties

We examine several modified versions of the heteroskedasticity-consistent covariance matrix estimator of Hinkley and White. On the basis of sampling experiments which compare the performance of quasi t statistics, we find that one estimator, based on the jackknife, performs better in small samples than the rest. We also examine finite-sample properties using modified critical values based on Edgeworth approximations, as proposed by Rothenberg. In addition, we compare the power of several tests for heteroskedasticity and find that it may be wise to employ the jackknife heteroskedasticity-consistent covariance matrix even in the absence of detected heteroskedasticity.Jackknife, Heteroskedasticity, HCCME, Edgeworth approximations

Seasonal changes in metabolic rates in muskoxen following twenty- four hours of starvation

Timing of seasonal trends in post-prandial energy expenditure (EE) was measured in muskoxen (2 males and 1 female) given a standardized meal followed by a 24-26 h starvation during 10 months over the course of a year. EE was significantly lower in winter than summer. CH4 production (EctM) was reversed with winter highs and summer lows. Ratio of ECH4:EE indicates a change in dietary efficiency but this difference was not associated with a seasonal shift in RQ which was constant. The main increase in EE from winter to summer occurred between April and May and the summer to winter decrease between August and Septembet

The Chediak-Higashi Syndrome: Spectrum of Giant Organelles in Peripheral Blood Cells

The presence of giant organelles in the cytoplasm of peripheral blood elements is diagnostic for the Chediak-Higashi syndrome. These abnormal cytoplasmic inclusions are found within neutrophils, eosinophils, basophils, lymphocytes, monocytes, and platelets. Their fine structural characteristics differ. Neutrophils demonstrate striking variability in the size, shape, and internal features of their giant organelles. Lymphocytes contain two different types of giant inclusions, one with a smoothly homogeneous substructure, the other with structures resembling microtubules. Emphasizing the ultrastructural similarities and differences of these anomalous granulations may provide valuable clues for understanding the basic defect of this inherited disorder