Volume 5 Issue 1 June 2006


Guest Comment: Early Years Are Important in the STEM Pipeline



Robert D. Koob


Department of Chemistry, University of Northern Iowa, Cedar Falls, Iowa 50614 USA

Using Molecular Dynamics Simulations to Model the DC Electrical Behavior of Confined Layers


Authors and Affiliations:

Nathan G. Beougher, Jason McIntosh, Jason A. Djuren, and M.W. Roth
Department of Physics, University of Northern Iowa, Cedar Falls, Iowa 50614 USA

Carlos Wexler
Department of Physics and Astronomy, University of Missouri, Columbia, Missouri 65211 USA

Carl Thurman
Department of Biology, University of Northern Iowa, Cedar Falls, Iowa 50614-0421 USA


A Molecular Dynamics (MD) computer simulation is utilized to qualitatively understand the DC electrical conduction behavior of pentadecane (CH) layers confined between two graphite slabs as related to the dynamics of the layer. At low temperatures the patch remains together and perpendicular to the confining layers. Then, as temperature is increased, tilting of the molecules begins. The molecules tend to remain straight as they tilt with increasing temperature which, in our model, affects the capacitance somewhat but the resistance little. As temperature is increased further, the molecules exhibit gauche defects which accompany patch collapse. During patch collapse, the system shows dramatic changes in its calculated DC resistance and capacitance. Calculated specific capacitance values are in remarkable agreement with recent experimental measurements. Results for two different confining layer separations are discussed as well as future work related to lipid bilayer systems.

Visualizing Bond Types with Electron Density Models: How Informative is Electronegativity?



Heath D. Stotts and J. Conceicao


Division of Natural Sciences, Northwestern Oklahoma State University, 709 Oklahoma Blvd., Alva, Oklahoma 73717 USA


Electron densities are used to visualize pure covalent, polar covalent and ionic bonds in binary compounds. The rationale for this study stems in part from the observations that within the same bond type, for example pure covalent, a variety of bond properties exist. Simple ΔEN predictions by Pauling do not adequately explain differences within the same bond type, nor determine covalent or ionic bonding. In this study, a series of electron density maps for binary compounds have been calculated to compare the characteristics of the maps to ΔEN predictions.

Comparing 6th Grade Science Classrooms: Inner-City versus Suburb



Nida Syed


Department of Behavioral Sciences, University of Michigan-Dearborn, Dearborn, Michigan 48128-1491 USA


Do teachers in the inner-city have different expectations of their students than teachers in the suburbs? Ethnographic studies of the classroom such as one by Wilcox in 1982 suggest they do. Wilcox describes education as “primarily a process of cultural transmission”. In other words, schools in a particular setting or neighborhood aim to instill in their students the cultural norms and behaviors accepted and expected in that setting. This project is an ethnographic study of two sixth grade science classrooms; one in an urban inner-city Detroit, Michigan neighborhood and one in the neighboring suburb of Dearborn. The study examines the way the two classrooms are run by the teachers and their teaching styles by comparing the types of assignments that are given to students and the implications they have on the students’ learning development. Other factors such as a comparison of school funding per pupil and the effect it has on the availability of resources necessary for learning in each classroom were also examined. We found that the Dearborn school students learned how to work individually and in groups whereas the Detroit school students learned only how to work in groups. We also found that Dearborn students were encouraged to read out loud to the class individually whereas Detroit students were often read to by the teacher.