Wabash College

About: Wabash College is a education organization based out in Crawfordsville, Indiana, United States. It is known for research contribution in the topics: Casimir effect & Casimir pressure. The organization has 422 authors who have published 754 publications receiving 17960 citations.

An Improved Empirical Potential Energy Function for Molecular Simulations of Phospholipids

Abstract: Improvements in the CHARMM all-atom force field for atomic-level molecular simulations of lipids are reported. Substantial adjustments have been made to the Lennard-Jones (LJ) hydrocarbon and torsional parameters and to the partial atomic charges and torsional parameters of the phosphate moiety. These changes were motivated by a combination of unexpected simulation results and recent high-level ab initio quantum mechanical calculations. The parameter optimization procedure is described, and the resulting energy function validated by an 11 ns molecular dynamics simulation of a hydrated phospholipid bilayer. Of note is the influence of the hydrocarbon LJ parameters on the conformational properties of the aliphatic tails, emphasizing the importance of obtaining the proper balance between the bonded and nonbonded portions of the force field. Compatibility with the CHARMM all-atom parameter sets for proteins and nucleic acids has been maintained such that high quality simulations of biologically interesting me...

Is actual similarity necessary for attraction? A meta-analysis of actual and perceived similarity

Abstract: To evaluate the impact of actual and perceived similarity on interpersonal attraction, we meta-analyzed 460 effect sizes from 313 laboratory and field investigations. Results indicated that the associations between interpersonal attraction and both actual similarity (r = .47) and perceived similarity (r = .39) were significant and large. The data also indicate that (i) actual similarity was important in no-interaction and short-interaction studies, (ii) there was a significant reduction in the effect size of actual similarity beyond no-interaction studies, and (iii) the effect of actual similarity in existing relationships was not significant. Alternatively, perceived similarity predicted attraction in no-interaction, short-interaction, and existing relationship studies. The implications of perceived similarity, rather than actual similarity, being predictive of attraction in existing relationships are discussed.

Polyunsaturated fatty acids in lipid bilayers: intrinsic and environmental contributions to their unique physical properties.

Abstract: Polyunsaturated lipids are an essential component of biological membranes, influencing order and dynamics of lipids, protein-lipid interaction, and membrane transport properties. To gain an atomic level picture of the impact of polyunsaturation on membrane properties, quantum mechanical (QM) and empirical force field based calculations have been undertaken. The QM calculations of the torsional energy surface for rotation about vinyl-methylene bonds reveal low barriers to rotation, indicating an intrinsic propensity toward flexibility. Based on QM and experimental data, empirical force field parameters were developed for polyunsaturated lipids and applied in a 16 ns molecular dynamics (MD) simulation of a 1-stearoyl-2-docosahexaenoyl-sn-glyerco-3-phosphocholine (SDPC) lipid bilayer. The simulation results are in good agreement with experimental data, suggesting an unusually high degree of conformational flexibility of polyunsaturated hydrocarbon chains in membranes. The detailed analysis of chain conformation and dynamics by simulations is aiding the interpretation of experimental data and is useful for understanding the unique role of polyunsaturated lipids in biological membranes. The complete force field is included as Supporting Information and is available from http://www.pharmacy.umaryland.edu/faculty/amackere/research.html.

Tests of new physics from precise measurements of the Casimir pressure between two gold-coated plates

Abstract: A micromechanical torsion oscillator has been used to strengthen the limits on new Yukawa forces by determining the Casimir pressure between two gold-coated plates. By significantly reducing the random errors and obtaining the electronic parameters of the gold coatings, we were able to conclusively exclude the predictions of large thermal effects below $1\text{ }\text{ }\ensuremath{\mu}\mathrm{m}$ and strengthen the constraints on Yukawa corrections to Newtonian gravity in the interaction range from 29.5 nm to 86 nm.