Dr. Joe's Neighborhood
(205) 934-1559, jgharrison@uab.edu

My work utilizes various theoretical methods to address a wide range of issues, from the origin of disease in the human body to the electronic wavefunction in ionic crystals. In collaboration with biochemistry, we use electronic cluster calculations to study the cis and trans conformations of peroxynitrite and protonated peroxynitrate because the decomposition of the latter leads to the type of tissue damage associated with nerve disorders such as Lou Gehrig's disease. Also, we are performing numerical simulations utilizing finite elements to test the effect of RF heating in magnetic resonance imaging at 4.1 T.In another area, we are implementing a density-functional theory of positron bound states in electronic systems to study lifetime shifts related to crystal-field effects in systems involving point defects in ionic crystals. Jointly with the experimental EPR studies of Dr. Tiit Tohver's students at UAB and colleagues at Oak Ridge National Lab, we are using the embedded cluster method to investigate possible distortions in the ground state of the defects MgO:H2- and CaO:H2- 57atom .In collaboration with Dr. Thomas Wdowiak, we examined a variety of molecular species to compare calculated IR spectra with those seen in laboratory measurements and in spectra from circumstellar atmospheres. One of particular interest is 1,1'-Binaphthyl which exhibits an interesting torsional-pendulum spectrum at low frequencies.

1,1' Binaphthyl

In collaboration with Dr. Yogesh Vohra, we simulate the complex hydrocarbon chemistry and kinetics in low-pressure diamond CVD. In particular we see the role of small amounts of O2 in increasing the CH3/C2H2 ratio, an indicator of diamond rather than graphitic growth.

2% CH4 0.4% O2 at 1Tor

5.6% CH4 0.4% O2 at 1 Tor

6% CH4 at 1 Tor

 

 

In collaboration with Dr. S. C. Ke, we simulated protein crystal growth using a stochastic model. The simulation showed that the use of larger aggregate units in the growth yielded results in closer agreement with experiment. See reference below.

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Computer Facilities:

• Dell Precision 470n  3.4 GHz  1MB L2 Cache
  
• UltraSparc I 167MHz 128 MB RAM
• Access to the Alabama Supercomputer Authority computers (SGI Altix 350 and Cray XD1).

Collaboration:

• UAB Departments of Anesthesiology, Cardiology (MRI) and Chemistry
• Massachussetts General Hospital (Harvard U.), Magnetic Resonance Center

Recent Publications:

• The Role of Conformation of Peroxynitrite Anion (OONO-) in its Stability, J. M. Tsai, J.G. Harrison, J.C. Martin, T.P. Hamilton, M. van der Woerd, M.J. Jablonsky, and J.S. Beckman, JACS 116, 4145 (1994).
• High Frequency Coils for Clinical Nuclear Magnetic Resonance Imaging and Spectroscopy, J.T. Vaughan, H.P. Hetherington, J.G. Harrison, J.O. Otu, J.W. Pan, P.J. Noa, and G.M. Pohost, Physica Medica, Sept. 1993.

 
• Finite-Element Model of Coil for MRI Applications
• Computed Temperature Elevation in Brain Tissue
• Computed Temperature Elevation in Non-perfused head
• Computed RF-Induced heat flux in Non-perfused head
• Model of 16-element Head Coil for MRI Applications
• B-field Contours for 16-element Head Coil @ 174.5 MHz
• Power Deposition for 16-element Head Coil
• Displacement Current @ 174.5 MHz 9 Watts
• Conduction Current @174.5 MHz 9 Watts


• A Density Functional LCAO Embedded-Cluster Calculation on the Jahn-Teller Distorted States of H^-- in CaO Crystal, S. C. Ke, D. C. Patton, J. G. Harrison and H. T. Tohver, J. Phys.: Condensed Matter 7, 9625 (1995).
• Finite Element Modeling of Head Coils for High-Frequency Magnetic Resonance Imaging Applications, J.G. Harrison and J.T. Vaughan, Annual Rev. of Prog. in Applied Computational Electromagnetics 12, 1220 (1996).
• Density functional calculations of positron annihilation lifetimes from positron bound states in atoms, K. Kim and J. G. Harrison, J. Phys. B, 29, 595 (1996).
• The effect of crystal field on density functional calculations of positron lifetimes in alkali halides, K. Kim and J. G. Harrison, J. Phys.: Condens. Matter 9, 3583-3600 (1997).
• Computer simulations of protein crystal growth using aggregates as the growth unit,, S.C. Ke, L.J. DeLucas and J.G. Harrison, J. of Physics D: App. Phys., 31 1064-1070 (1998).



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