Volume 2 Issue 3 December 2003

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https://doi.org/10.33697/ajur.2003.020

Where Is This Undergraduate Research Wave Taking Us?

https://doi.org/10.33697/ajur.2003.021

Author(s):

Mark Benvenuto

Affiliation:

Department of Chemistry and Biochemistry, University of Detroit Mercy, 4001 W. McNichols Road, Detroit, Michigan 48219-0900 USA


Guest Comment
Science, Technology, Engineering and Mathematics (STEM) Undergraduate Education at the University of Northern Iowa

https://doi.org/10.33697/ajur.2003.022

Author(s):

Kichoon Yang

Affiliation:

College of Natural Sciences, University of Northern Iowa, Cedar Falls, Iowa 50614-0181 USA


Theoretical Neuroscience: Modeling the Activation Mechanism of Potassium Channels in Neurons

https://doi.org/10.33697/ajur.2003.023

Author(s):

Kevin Twedt

Affiliation:

Department of Physics, University of Northern Iowa, Cedar Falls, Iowa 50614-0150 USA

ABSTRACT:

We have modeled the electrostatic interaction between the S4 segment of the potassium channel molecule and the surrounding water molecules on both the intracellular and extracellular sides of the neural axon cell membrane. Two methods were used to approximate this interaction: (i) a macroscopic evaluation in which the water was treated as a dielectric medium with dielectric constant 80; (ii) a microscopic evaluation considering the effects of each individual water molecule fixed in position within the water pockets surrounding the S4 segment. The potential energy of the S4 due to the water pockets was plotted against the rotation of the S4 segment, while keeping the water pockets in their fixed positions. Although the two methods gave some differing results, both methods produced single well potential energy curves of ~6-9 eV depth. Based on this energy curve, we show that other forces on the S4 must create an effective torsional spring force with spring constant k~3-5 eV in order to produce a two well potential energy curve in qualitative agreement with experimental data.


Computerized Data Reduction and Analysis in Positron Annihilation Coincidence Doppler Broadening Spectroscopy

https://doi.org/10.33697/ajur.2003.024

Author(s):

A. Harrich, S. Jagsch, S. Riedler and W. Rosinger

Affiliation:

Department of Automotive Engineering, FH Joanneum University of Applied Sciences, Alte Poststr. 149, A-8020 Graz, Austria

ABSTRACT:

Positron annihilation spectroscopy is a sensitive probe for studying the electronic structure of defects in solids. The high-momentum part of the Doppler-broadened spectra can be used to distinguish different elements at the annihilation site. This can be achieved by using a two-detector coincidence system, which reduces the peak to background ratio dramatically. The coincident events have to be extracted from a two-dimensional spectrum that is recorded by two high-purity germanium detectors. For this purpose the computer program MePASto was developed, which allows an automated data reduction from such Doppler-coincidence spectra, supplemented by a post-processing unit for data analysis. Additionally a case study of the identification of defect sites in an intermetallic compound is presented.


NBA Draft Lottery Probabilities

https://doi.org/10.33697/ajur.2003.025

Author(s):

Chad R. Florke and Mark D. Ecker

Affiliation:

Department of Mathematics, University of Northern Iowa, Cedar Falls, Iowa 50614-0506 USA

ABSTRACT:

We examine the evolution of the National Basketball Association’s (NBA’s) Draft Lottery by showing how the changes implemented by the Board of Governors have impacted the probabilities of obtaining top picks in the ensuing draft lottery. We explore how these changes have impacted the team with the worst record and also investigate the conditional probabilities of the fourth worst team receiving the third pick. These calculations are conditioned upon two specified teams receiving the first two selections. We show that the probability of the fourth worst team receiving the third pick can be made unconditionally. We calculate the probabilities for the fourth worst team to move up in the draft to receive either the first, second, or third selections, along with its chance of keeping the fourth pick or even dropping in the draft. We find there is a higher chance for the fourth worst team to drop to the fifth, sixth or seventh position than to stay at the fourth position or move up.