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Molecular Theory Applied to Lipid Bilayers and Lipid–Protein Interactions

Chapter
Part of the Handbook of Modern Biophysics book series (HBBT)

Abstract

The fundamental, necessary components of biomembranes are the lipids that form the membrane bilayer. Although a typical plasma membrane is composed of about 50% percent proteins by mass [1], the lipids provide the structure of the membrane through their self-assembly into a bilayer. The self-assembly is driven by the amphiphilic nature of the lipids: they contain a headgroup that is hydrophilic and a tailgroup that is hydrophobic. The basic principles of lipid self-assembly are well understood [2]. The physical properties and behavior of the lipid bilayer have been studied theoretically using a variety of models and techniques. With increasing computational resources available, a popular approach has been to study membranes using atomistic molecular dynamics (MD) simulations. In such simulations, all the atoms are represented explicitly. The interactions between atoms are described by effective potentials which must be obtained through either quantum mechanical calculations or by fitting various properties to experiment. Such simulations istic MD simulations have been able to treat patches of membrane up to a few tens of nanometers in lateral extent, over timescales of a few tens of nanoseconds.

Keywords

Density Functional Theory Lipid Bilayer Chem Phys Density Profile Bilayer Thickness 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    Alberts B, Johnson A, Lewis J, Raff M, Roberts K, Walter P. 2002. Molecular biology of the cell. New York: Garland Science, Taylor & Francis Group.Google Scholar
  2. 2.
    Israelachvili J. 1992. Intermolecular and surface forces. Academic Press.Google Scholar
  3. 3.
    Shelley JC, Shelley MY, Reeder RC, Bandyopadhyay S, Klein ML. 2001. A coarse-grain model for phospholipid simulations. J Phys Chem B 105:4464–4470.CrossRefGoogle Scholar
  4. 4.
    Marrink SJ, Vries AH, Mark AE. 2004. Coarse-grained model for semiquantitative lipid simulations. J Phys Chem B 108:750–760.CrossRefGoogle Scholar
  5. 5.
    Marrink SJ, Risselada HJ, Yefimov S, Tieleman DP, Vries AH. 2007. The MARTINI force field: coarse grained model for biomolecular simulations. J Phys Chem B 111:7812–7824.CrossRefGoogle Scholar
  6. 6.
    Bond PJ, Holyoake J, Ivetac A, Khalid S, Sansom MSP. 2007. Coarse-grained molecular dynamics simulations of membrane proteins and peptides. J Struct Bio 157:593–605.CrossRefGoogle Scholar
  7. 7.
    Orsi M, Haubertin DY, Sanderson WE, Essex JW. 2008. A quantitative coarse-grain model for lipid bilayers. J Phys Chem B 112:802–815.CrossRefGoogle Scholar
  8. 8.
    Venturoli M, Sperotto MM, Kranenburg M, Smit B. 2006. Mesoscopic models of biological membranes. Phys Rep—Rev Sect Phys Lett 437:1–54.Google Scholar
  9. 9.
    Shillcock JC, Lipowsky R. 2006. The computational route from bilayer membranes to vesicle fusion. J Phys Cond Matter 18:S1191–S1219.ADSCrossRefGoogle Scholar
  10. 10.
    Müller M, Katsov K, Schick M. 2006. Biological and synthetic membranes: what can be learned from a coarsegrained description?. Phys Rep—Rev Sect Phys Lett 434:113–176.Google Scholar
  11. 11.
    Helfrich W. 1973. Elastic properties of lipid bilayers—theory and possible experiments. Z Naturforsch 28c:693–703.Google Scholar
  12. 12.
    Safran SA. 1994. Statistical thermodynamics of surfaces, interfaces, and membranes. Reading, MA: Addison-Wesley.Google Scholar
  13. 13.
    May S. 2000. Theories on structural perturbations of lipid bilayers. Curr Opin Colloid Interface Sci 5:244–249.CrossRefGoogle Scholar
  14. 14.
    Frink LJD, Frischknecht AL. 2005. Density functional theory approach for coarse-grained lipid bilayers. Phys Rev E 72:041923.ADSCrossRefGoogle Scholar
  15. 15.
    Frischknecht AL, Frink LJD. 2005. Comparison of density functional theory and simulation of fluid bilayers. Phys Rev E 72:041924.ADSCrossRefGoogle Scholar
  16. 16.
    Frischknecht AL, Frink LJD. 2006. Alcohols reduce lateral membrane pressures: predictions from molecular theory. Biophys J 91:4081–4090.CrossRefGoogle Scholar
  17. 17.
    Frink LJD, Frischknecht AL. 2006. Computational investigations of pore forming peptide assemblies in lipid bilayers. Phys Rev Lett 97:208701.ADSCrossRefGoogle Scholar
  18. 18.
    Marconi UMB, Tarazona P. 1999. Dynamic density functional theory of fluids. J Chem Phys 110:8032–8044.ADSCrossRefGoogle Scholar
  19. 19.
    Fraaije JGEM, Van Vlimmeren BAC, Maurits NM, Postma M, Evers OA, Hoffmann C, Altevogt P, Goldbeck-Wood G. 1997. The dynamic mean-field density functional method and its application to the mesoscopic dynamics of quenched block copoymer melts. J Chem Phys 106:4260–4269.ADSCrossRefGoogle Scholar
  20. 20.
    Chandler D. 1987. Introduction to modern statistical mechanics. Oxford: Oxford UP.Google Scholar
  21. 21.
    Hansen J.-P, McDonald IR. 1986. Theory of simple liquids. Academic Press.Google Scholar
  22. 22.
    Somoza AM, Chacon E, Mederos L, Tarazona P. 1995. A model for membranes, vesicles and micelles in amphiphilic systems. J Phys Cond Matter 7:5753–5776.ADSCrossRefGoogle Scholar
  23. 23.
    Brannigan G, Brown FLH. 2004. Solvent-free simulations of fluid membrane bilayers. J Chem Phys 120:1059–1071.ADSCrossRefGoogle Scholar
  24. 24.
    Marcelja S. 1974. Chain ordering in liquid crystals, II: structure of bilayer membranes. Biochim Biophys Acta 1024:139–151.Google Scholar
  25. 25.
    May S, Ben-Shaul A. 1999. Molecular theory of lipid–protein interaction and the La–HII transition. Biophys J 76:751–767.CrossRefGoogle Scholar
  26. 26.
    May S, Ben-Shaul A. 2000. A molecular model for lipid-mediated interaction between proteins in membranes. Phys Chem Chem Phys 2:4494–4502.CrossRefGoogle Scholar
  27. 27.
    Lague P, Zuckermann MJ, Roux B. 1998. Protein inclusion in lipid membranes: a theory based on the hypernetted chain integral equation. Faraday Discuss 111:165–172.CrossRefADSGoogle Scholar
  28. 28.
    Lague P, Zuckermann MJ, Roux B. 2000. Lipid-mediated interactions between intrinsic membrane proteins: a theoretical study based on integral equations. Biophys J 79:2867–2879.CrossRefGoogle Scholar
  29. 29.
    Lague P, Zuckermann MJ, Roux B. 2001. Lipid-mediated interactions between intrinsic membrane proteins: dependence on protein size and lipid composition. Biophys J 81:276–284.CrossRefGoogle Scholar
  30. 30.
    Fredrickson GH. 2006. The equilibrium theory of inhomogeneous polymers. Oxford: Clarendon Press.Google Scholar
  31. 31.
    Leermakers FAM, Scheutjens JMHM. 1988. Statistical thermodynamics of association colloids, III: the gel to liquid phase transition of lipid bilayer membranes. J Chem Phys 89:6912–6924.ADSCrossRefGoogle Scholar
  32. 32.
    Meijer LA, Leermakers FAM, Lyklema J. 1994. Headgroup conformations in lipid bilayer-membranes. Recl Trav Chim Pays-Bas 113:167–175.CrossRefGoogle Scholar
  33. 33.
    Leermakers FAM, Rabinovich AL, Balabaev NK. 2003. Self-consistent-field modeling of hydrated unsaturated lipid bilayers in the liquid–crystal phase and comparison to molecular dynamics simulations. Phys Rev E 67:011910–1910.ADSCrossRefGoogle Scholar
  34. 34.
    Cantor RS. 1999. Lipid composition and the lateral pressure profile in bilayers. Biophys J 76:2625–2639.CrossRefGoogle Scholar
  35. 35.
    Whitmore MD, Whitehead JP. 1998. Self-consistent field theory of compressible phospholipid membranes at finite pressure. Can J Phys 76:883–898.ADSCrossRefGoogle Scholar
  36. 36.
    Muller M, Schick M. 1998. Calculation of the phase behavior of lipids. Phys Rev E 57:6973–6978.ADSCrossRefGoogle Scholar
  37. 37.
    Li XJ, Schick M. 2000. Fluctuations in mixtures of lamellar- and nonlamellar-forming lipids. J Chem Phys 112:10599–10607.ADSCrossRefGoogle Scholar
  38. 38.
    Li XJ, Schick M. 2000. Distribution of lipids in nonlamellar phases of their mixtures. J Chem Phys 112:6063–6072.ADSCrossRefGoogle Scholar
  39. 39.
    Li XJ, Schick M. 2000. Theory of lipid polymorphism: application to phosphatidylethanolamine and phosphati-dylserine. Biophys J 78:34–46.CrossRefGoogle Scholar
  40. 40.
    Meijer LA, Leermakers FAM, Nelson A. 1994. Modeling of the electrolyte ion phospholipid layer interaction. Langmuir 10:1199–1206.CrossRefGoogle Scholar
  41. 41.
    Li XJ, Schick M. 2001. Theory of tunable pH-sensitive vesicles of anionic and cationic lipids or anionic and neutral lipids. Biophys J 80:1703–1711.CrossRefGoogle Scholar
  42. 42.
    Goetz R, Lipowsky R. 1998. Computer simulations of bilayer membranes: self-assembly and interfacial tension. J Chem Phys 108:7397–7409.ADSCrossRefGoogle Scholar
  43. 43.
    Kremer K, Grest GS. 1990. Dynamics of entangled linear polymer melts: a molecular-dynamics simulation. J Chem Phys 92:5057.ADSCrossRefGoogle Scholar
  44. 44.
    Hohenberg P, Kohn W. 1964. Inhomogeneous electron gas. Phys Rev 136:B864–B871.ADSMathSciNetCrossRefGoogle Scholar
  45. 45.
    Mermin ND. 1965. Thermal properties of the inhomogeneous electron gas. Phys Rev 137:A1441–A1443.ADSMathSciNetCrossRefGoogle Scholar
  46. 46.
    Ebner C, Saam WF, Stroud D. 1976. Density-functional theory of simple classical fluids, I: surfaces. Phys Rev A 14:2264–2273.ADSCrossRefGoogle Scholar
  47. 47.
    Evans R. 1979. The nature of the liquid–vapor interface and other topics in the statistical mechanics of nonuniform classical fluids. Adv Phys 28:143–200.ADSCrossRefGoogle Scholar
  48. 48.
    Davis TH. 1996. Statistical mechanics of phases, interfaces, and thin films. New York: VCH.Google Scholar
  49. 49.
    Henderson D, ed. 1992. Fundamentals of inhomogeneous fluids. New York: Marcel Dekker.Google Scholar
  50. 50.
    Frink LJD, Salinger AG, Sears MP, Weinhold JD, Frischknecht AL. 2002. Numerical challenges in the application of density functional theory to biology and nanotechnology. J Phys Cond Matter 14:12167–12187.ADSCrossRefGoogle Scholar
  51. 51.
    Wu J. 2006. Density functional theory for chemical engineering: from capillarity to soft materials. AIChE J 52:1169–1193.CrossRefGoogle Scholar
  52. 52.
    Wu J. 2007. Density-functional theory for complex fluids. Annu Rev Phys Chem 58:85–112.CrossRefADSGoogle Scholar
  53. 53.
    Rosenfeld Y. 1989. Free-energy model for the inhomogeneous hard-sphere fluid mixture and density-functional theory of freezing. Phys Rev Lett 63:980–983.ADSCrossRefGoogle Scholar
  54. 54.
    Roth R, Evans R, Lang A, Kahl G. 2002. Fundamental measure theory for hard-sphere mixtures revisited: the White Bear version. J Phys Cond Matter 14:12063–12078.ADSCrossRefGoogle Scholar
  55. 55.
    Chandler D, McCoy JD, Singer SJ. 1986. Density functional theory of nonuniform polyatomic systems, I: general formulation. J Chem Phys 85:5971.ADSCrossRefGoogle Scholar
  56. 56.
    Chandler D, McCoy JD, Singer SJ. 1986. Density functional theory of nonuniform polyatomic systems, II: rational closures for integral equations. J Chem Phys 85:5977–5982.ADSCrossRefGoogle Scholar
  57. 57.
    McCoy JD, Singer SJ, Chandler D. 1987. A density functional treatment of the hard dumbbell freezing transition. J Chem Phys 87:4853–4858.ADSCrossRefGoogle Scholar
  58. 58.
    Hooper JB, McCoy JD, Curro JD. 2000. Density functional theory of simple polymers in a slit pore, I: theory and efficient algorithm. J Chem Phys 112:3090.ADSCrossRefGoogle Scholar
  59. 59.
    Hooper JB, Pileggi MT, McCoy JD, Curro JD, Weinhold JD. 2000. Density functional theory of simple polymers in a slit pore, II: the role of compressibility and field type. J Chem Phys 112:3094.ADSCrossRefGoogle Scholar
  60. 60.
    Hooper JB, McCoy JD, Curro JD, van Swol F. 2000. Density functional theory of simple polymers in a slit pore, III: surface tension. J Chem Phys 113:2021–2024.ADSCrossRefGoogle Scholar
  61. 61.
    Donley JP, Curro JD, McCoy JD. 1994. A density functional theory for pair correlation funcitons in molecular liquids. J Chem Phys 101:3205.ADSCrossRefGoogle Scholar
  62. 62.
    Frischknecht AL, Weinhold JD, Salinger AG, Curro JG, Frink LJD, McCoy JD. 2002. Density functional theory for inhomogeneous polymer systems, I: numerical methods. J Chem Phys 117:10385–10397.ADSCrossRefGoogle Scholar
  63. 63.
    Frischknecht AL, Curro JG. 2004. Comparison of random-walk density functional theory to simulation for bead-spring homopolymer melts. J Chem Phys 121:2788–2797.ADSCrossRefGoogle Scholar
  64. 64.
    Schweizer KS, Curro JD. 1989. Integral equation theory of the structure and thermodynamcis of polymer blends. J Chem Phys 91:5059–5081.ADSCrossRefGoogle Scholar
  65. 65.
    Schweizer KS, Curro JG. 1997. Integral equation theories of the structure, thermodynamics and phase transitions of polymer fluids. Adv Chem Phys 98:1.CrossRefGoogle Scholar
  66. 66.
    Heine DR, Grest GS, Curro JG. 2005. Structure of polymer melts and blends: comparison of integral equation theory and computer simulations. Adv Polym Sci 173:209–252.CrossRefGoogle Scholar
  67. 67.
    Jain S, Dominik A, Chapman WG. 2007. Modified interfacial statistical associating fluid theory: a perturbation density funcitonal theory for inhomogeneous complex fluids. J Chem Phys 127:244904.ADSCrossRefGoogle Scholar
  68. 68.
    Rosenfeld Y, Schmidt M, Löwen H, Tarazona P. 1996. Dimensional crossover and the freezing transition in density functional theory. J Phys Cond Matter 8:L577.ADSCrossRefGoogle Scholar
  69. 69.
    Rosenfeld Y, Schmidt M, Löwen H, Tarazona P. 1997. Fundamental-measure free-energy density functional for hard spheres: dimensional crossover and freezing. Phys Rev E 55:4245–4263.ADSCrossRefGoogle Scholar
  70. 70.
    Wertheim MS. 1984. Fluids with highly directional attractive forces, II: thermodynamic perturbation theory and integral equations. J Stat Phys 35:35–47.zbMATHADSMathSciNetCrossRefGoogle Scholar
  71. 71.
    Tripathi S, Chapman WG. 2005. Microstructure of inhomogeneous polyatomic mixtures from a density functional formalism for atomic mixtures. J Chem Phys 122:094506.ADSCrossRefGoogle Scholar
  72. 72.
    Tripathi S, Chapman WG. 2005. Microstructure and thermodynamics of inhomogeneous polymer blends and solutions. Phys Rev Lett 94:087801.ADSCrossRefGoogle Scholar
  73. 73.
  74. 74.
    Heroux MA, Salinger AG, Frink LJD. 2007. Parallel segregated Schur complement methods for fluid density functional theories. SIAM J Sci Comp 29:2059–2077.zbMATHMathSciNetCrossRefGoogle Scholar
  75. 75.
    Keller HB. 1977. Numerical solution of bifurcation and nonlinear eigenvalue problems. In Applications of bifurcation theory, pp. 359–384. Ed PH Rabinowitz. New York, London: Academic Press.Google Scholar
  76. 76.
    Salinger AG, Bou-Rabee NM, Pawlowski RP, Wilkes ED, Burroughs EA, Lehoucq RB, Romero LA. 2002. LOCA 1.0, library of continuation algorithms: theory and implementation manual. Technical Report SAND2002-0396. Albuquerque, NM: Sandia National Laboratories.Google Scholar
  77. 77.
    Petrache HI, Dodd SW, Brown MF. 2000. Area per lipid and acyl length distributions in fluid phosphatidylcho-lines determined by 2H NMR spectroscopy. Biophys J 79:3172–3192.CrossRefGoogle Scholar
  78. 78.
    Stevens MJ. 2004. Coarse-grained simulations of lipid bilayers. J Chem Phys 121:11942–11948.ADSCrossRefGoogle Scholar
  79. 79.
    Armen RS, Uitto OD, Feller SE. 1998. Phospholipid component volumes: determination and application to bilayer structure calculations. Biophys J 75:734–744.CrossRefGoogle Scholar
  80. 80.
    Nagle JF, TristramNagle S. 2000. Structure of lipid bilayers. Biochim Biophys Acta, Rev Biomembr 1469:159–195.Google Scholar
  81. 81.
    Abrams CF, Kremer K. 2001. The effect of bond length on the structure of dense bead-spring polymer melts. J Chem Phys 115:2776–2785.ADSCrossRefGoogle Scholar
  82. 82.
    Barry JA, Gawrisch K. 1994. Direct NMR evidence for ethanol binding to the lipid–water interface of phospholipid bilayers. Biochemistry 33:8082–8088.CrossRefGoogle Scholar
  83. 83.
    Holte LL, Gawrisch K. 1997. Determining ethanol distribution in phospholipid multilayers with MAS-NOESY spectra. Biochemistry 36:4669–4674.CrossRefGoogle Scholar
  84. 84.
    Feller SE, Brown CA, Nizza DT, Gawrisch K. 2002. Nuclear Overhauser enhancement spectroscopy cross-relaxation rates and ethanol distribution across membranes. Biophys J 82:1396–1404.CrossRefGoogle Scholar
  85. 85.
    Patra M, Salonen E, Terama E, Vattulainen R, Faller B, Lee W, Holopainen J, Karttunen M. 2006. Under the influence of alcohol: the effect of ethanol and methanol on lipid bilayers. Biophys J 90:1121–1135.CrossRefGoogle Scholar
  86. 86.
    Ly HV, Longo ML. 2004. The influence of short-chain alcohols on interfacial tension, mechanical properties, area/molecule, and permeability of fluid lipid bilayers. Biophys J 87:1013–1033.ADSCrossRefGoogle Scholar
  87. 87.
    Monticelli L, Kandasamy S, Periole X, Larson R, Tieleman DP, Marrink SJ. 2008. The MARTINI coarse-grained force field: extension to proteins. J Chem Theory Comput 4:819–834.CrossRefGoogle Scholar
  88. 88.
    Bechinger B. 1999. The strucutre, dynamics and orientation of antimicrobial peptides in membranes by multidimensional solid-state NMR spectroscopy. Biochim Biophys Acta, Rev Biomembr 1462:157–183.CrossRefGoogle Scholar
  89. 89.
    Brogden KA. 2005. Antimicrobial peptides: pore formers or metabolic inhibitors in bacteria? Nature Rev Microbiol 3:238–250.CrossRefGoogle Scholar
  90. 90.
    Huang HW. 2006. Molecular mechanism of antimicrobial peptides: the origin of cooperativity. Biochim Biophys Acta 1758:1292–1302.CrossRefGoogle Scholar
  91. 91.
    Oversteegen SM, Barneveld PA, Male J, Leermakers FAM, Lyklema J. 1999. Thermodynamic derivation of mechanical expressions for interfacial parameters. Phys Chem Chem Phys 1:4987–4994.CrossRefGoogle Scholar
  92. 92.
    Gullingsrud J, Schulten K. 2003. Gating of MscL studied by steered molecular dynamics. Biophys J 85:2087–2099.CrossRefGoogle Scholar
  93. 93.
    Gullingsrud J, Schulten K. 2004. Lipid bilayer pressure profiles and mechanosensitive channel gating. Biophys J 86:3496–3509.CrossRefGoogle Scholar
  94. 94.
    Cantor RS. 1997. The lateral pressure profile in membranes: a physical mechanism of general anesthesia. Biochemistry 36:2339–2344.CrossRefGoogle Scholar
  95. 95.
    Cantor RS. 1999. The influence of membrane lateral pressures on simple geometric models of protein conformational equilibria. Chem Phys Lipids 101:45–56.CrossRefGoogle Scholar
  96. 96.
    Attard GS, Templer RH, Smith WS, Hunt AN, Jackowski S. 2000. Modulation of CTP:phosphocholine cytidylyltransferase by membrane curvature elastic stress. Proc Natl Acad Sci USA 97:9032–9036.ADSCrossRefGoogle Scholar
  97. 97.
    Marsh D. 1996. Lateral pressure in membranes. Biochim Biophys Acta 1286:183–223.Google Scholar
  98. 98.
    Rowlinson J, Widom B. 1982. Molecular theory of capillarity. New York: Oxford UP.Google Scholar
  99. 99.
    Lindahl E, Edholm O. 2000. Spatial and energetic-entropic decoposition of surface tension in lipid bilayers from molecular dynamics simulations. J Chem Phys 113:3882–3893.ADSCrossRefGoogle Scholar
  100. 100.
    Yang AJM, Flemming III PD, Gibbs JH. 1976. Molecular theory of surface tension. J Chem Phys 64:3732–3747.ADSCrossRefGoogle Scholar
  101. 101.
    Henderson JR. 1992. Statistical mechanical sum rules. In Fundamentals of inhomogeneous fluids, pp. 23–84. Ed D Henderson. New York: Dekker.Google Scholar
  102. 102.
    Szleifer I, Kramer D, Ben-Shaul A, Gelbart WM, Safran S. 1990. Molecular theory of curvature elasticity in surfactant films. J Chem Phys 92:6800–6817.ADSCrossRefGoogle Scholar
  103. 103.
    Harries D, Ben-Shaul A. 1997. Conformational chain statistics in a model lipid bilayer: comparison between mean field and Monte Carlo simulations. J Chem Phys 106:1609–1619.ADSCrossRefGoogle Scholar
  104. 104.
    Chin JH, Goldstein DB. 1977. Effects of low concentrations of ethanol on fluidity of spin-labeled erythrocyte and brain membranes. Mol Pharmacol 13:435–441.Google Scholar
  105. 105.
    Komatsu H, Okada S. 1997. Effects of ethanol on permeability of phosphatidylcholine/cholesterol mixed liposomal membranes. Chem Phys Lipids 85:67–74.CrossRefGoogle Scholar
  106. 106.
    Chen SY, Yang B, Jacobson K, Sulik KK. 1996. The membrane disordering effect of ethanol on neural crest cells in vitro and the protective role of GM1 ganglioside. Alcohol 13:589–595.CrossRefGoogle Scholar
  107. 107.
    Traube I. 1891. Über die capillaritatsconstanten organischer stoffe in wassriger losung. Liebigs Ann Chem 265:27–55.CrossRefGoogle Scholar
  108. 108.
    Laan E, Chupin V, Killian JA, Kruijff B. 2004. Small alcohols destabilize the KcsA tetramer via their effect on the membrane lateral pressure. Biochemistry 43:5937–5942.CrossRefGoogle Scholar
  109. 109.
    Terama E, Ollila OH Samuli, Salonen E, Rowat AC, Trandum C, Westh P, Patra M, Karttunen M, Vattulainen I. 2008. Influence of ethanol on lipid membranes: from lateral pressure profiles to dynamics and partitioning. J Phys Chem B 112:4131–4139.CrossRefGoogle Scholar

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© Humana Press 2009

Authors and Affiliations

  1. 1.Sandia National LaboratoriesNew MexicoUSA
  2. 2.Colder InsightsMinnesotaUSA

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