Publications of David G Schaeffer

Books

  1. Two phase flows and waves, edited by Joseph, Daniel D. and Schaeffer, David G., pp. xii+164, 1990, Springer-Verlag, New York
  2. Golubitsky, Martin and Stewart, Ian and Schaeffer, David G., Singularities and groups in bifurcation theory. Vol. II, pp. xvi+533, 1988, Springer-Verlag, New York
  3. Golubitsky, Martin and Schaeffer, David G., Singularities and groups in bifurcation theory. Vol. I, pp. xvii+463, 1985, Springer-Verlag, New York

Papers Published

  1. D.G. Schaeffer, X. Zhao, Alternate pacing of border-collision period-doubling bifurcations, Nonlinear Dynamics, vol. 50 (2007), pp. 733--742
  2. D.G. Schaeffer, C. Berger, D. Gauthier, X. Zhao, Small-signal amplification of period-doubling bifurcations in smooth iterated mappings, Nonlinear Dynamics, vol. 48 (2007), pp. 381--389
  3. D.G. Schaeffer, M Shearer, and T. Witelski, Boundary-value problems for hyperbolic partial differential equations related to steady granular flow, Math. and Mech. of Solids, vol. 12 (2007), pp. 665--699
  4. D.G. Schaeffer, J. Cain, D. Gauthier,S. Kalb, W. Krassowska, R. Oliver, E. Tolkacheva, W. Ying, An ionically based mapping model with memory for cardiac restitution, Bull Math Bio, vol. 69 (2007), pp. 459--482
  5. D.G. Schaeffer, M. Matthews, P. Gremaud, On the computation of steady hopper flows III: Comparison of von Mises and Matsuoka-Nakai materials", J Comp. Phy., vol. 219 (2006), pp. 443-454
  6. D.G. Schaeffer, S. Kalb, E. Tolkacheva, D. Gauthier, W. Krassowska, Features of the restitution portrait for mapping models with an arbitrary amount of memory, Chaos, vol. 15 (2005), pp. 023701--
  7. D.G. Schaeffer, B. Tighe, J. Socolar, G. Michener, M. Huber, Force distribution in granular media, PRE, vol. 72 (2005), pp. 031306
  8. D.G. Schaeffer, J. Cain, E. Tolkacheva, D. Gauthier, Rate-dependent waveback velocity of cardiac action potentials in a done-dimensional cable, Phys Rev E, vol. 70 (2004), pp. 061906--?
  9. David G. Schaeffer, J.V. Matthews, A steady-state, hyperbolic free boundary problem for a granular-flow model, SIAM J. Math Analysis, vol. 36 (2004), pp. 256-271
  10. David G. Schaeffer, M. Shearer, T. Witelski, One-dimensional solutions of an elastoplasticity model of granular material, Math. Models and Methods in Appl. Sciences, vol. 13 (2003), pp. 1629--1671
  11. Colleen C. Mitchell, David G. Schaeffer, A two-current model for the dynamics of cardiac membrane, Bulletin Math Bio, vol. 65 (2003), pp. 767--793
  12. David G. Schaeffer, E. Tolkacheva, D. Gauthier, W Krassowska, Condition for alternans and stability of the 1:1 response pattern in a 'memory' model of paced cardiac dynamics, Phys Rev E, vol. 67 (2003), pp. 031904
  13. David G. Schaeffer, Review of W. Cheney's "Analysis for applied mathematics", Amer. Math Monthly, vol. 110 (2003), pp. 550
  14. Pierre Gremaud, John V. Matthews, David G. Schaeffer, Secondary circulation in granular flow through a nonaxisymmetric hopper, SIAM J Appl. Math, vol. 64 (2003), pp. 583--600
  15. D.G. Schaeffer, E. Tolkacheva, D. Gauthier, W. Krassowska, Condition for alternans and stability of the 1:1 response pattern in a memory model of paced cardiac dynamics, Phys Rev E, vol. 67 (2003), pp. 031904
  16. David G. Schaeffer, Elena Tolkacheva, Colleen Mitchell, Analysis of the Fenton-Karma model through a one-dimensional map, Chaos, vol. 12 (2002), pp. 1034-1042
  17. David G. Schaeffer, J. Socolar, P. Claudin, J.-P. Bouchard, Directed force chain models and stress reponse in static granular materials, Euro. Phys. J. E, vol. 7 (2002), pp. 353--370
  18. D.G. Schaeffer, E. Tolkacheva, D. Gauthier, and C. Mitchell, Analysis of the Fenton-Karma model through approximation by a one-dimensional map, Chaos, vol. 12 (2002), pp. 1034
  19. Witelski, Thomas P. and Schaeffer, David G. and Shearer, Michael, A discrete model for an ill-posed nonlinear parabolic PDE, Phys. D, vol. 160, no. 3-4, pp. 189--221, 2001
  20. G. Metcalfe, L. Kondic, D. Schaeffer, S. Tennakoon, and R. Behringer, Granular friction and the fluid-solid transition for shaken granular materials, Phys. Rev. E 65 (2002)
  21. Hayes, Brian T. and Schaeffer, David G., Stress-controlled shear waves in a saturated granular medium, European J. Appl. Math., vol. 11, no. 1, pp. 81--94, 2000
  22. David G Schaeffer, M. Sexton, J. Socolar, Force Distribution in a Scalar Model for Non-Cohesive Granular Material, Phys. Rev. Lett. E 60 (1999), 1999-2008
  23. Gremaud, Pierre Alain and Schaeffer, David G. and Shearer, Michael, Numerical determination of flow corrective inserts for granular materials in conical hoppers, Internat. J. Non-Linear Mech., vol. 35, no. 5, pp. 869--882, 2000
  24. Hayes, Brian T. and Schaeffer, David G., Plane shear waves under a periodic boundary disturbance in a saturated granular medium, Phys. D, vol. 121, no. 1-2, pp. 193--212, 1998
  25. Howle, Laurens and Schaeffer, David G. and Shearer, Michael and Zhong, Pei, Lithotripsy: the treatment of kidney stones with shock waves, SIAM Rev., vol. 40, no. 2, pp. 356--371 (electronic), 1998
  26. Schaeffer, David G. and Shearer, Michael, A simple model for stress fluctuations in plasticity with application to granular materials, SIAM J. Appl. Math., vol. 58, no. 6, pp. 1791--1807 (electronic), 1998
  27. David G Schaeffer, M. Shearer, A Simple Model for Stress Fluctuations in Plasticity, with Application to Granular Materials, SIAM J. Appl. Math. 58(1998), 1791-1807.
  28. G. Tardos, M.I. Khan, David G Schaeffer, Forces On a Slowly Rotating, Rough Cylinder in a Couette Device Containing a Dry, Frictional Powder, Physics of Fluids 10(1998), 335-341.
  29. Schaeffer, David G. and Shearer, Michael, The influence of material non-uniformity preceding shear-band formation in a model for granular flow, European J. Appl. Math., vol. 8, no. 5, pp. 457--483, 1997
  30. M. K. Gordon, David G Schaeffer, M. Shearer, Plane Shear Waves in a Fully Saturated Granular Medium with Velocity-and Stress-Controlled Boundary Conditions, Int. J. Nonlinear Mechancis 32(1997), 489-503.
  31. P. Gremaud, David G Schaeffer, Ml. Shearer, Granular Flow Past a Binsert, Report to Jenike & Johanson, Inc.
  32. David G Schaeffer, M. Shearer, Models of Stress Fluctuations in Granular Materials, Powders and Grains, R.P. Behringer and J. Jenkins (eds.), Balkema, 1997.
  33. Shearer, Michael and Schaeffer, David G., Riemann problems for $5\times 5$ systems of fully non-linear equations related to hypoplasticity, Math. Methods Appl. Sci., vol. 19, no. 18, pp. 1433--1444, 1996
  34. Schaeffer, David G., A survey of granular flow, Hyperbolic problems: theory, numerics, applications (Stony Brook, NY, 1994), pp. 63--80, 1996, World Sci. Publishing, River Edge, NJ
  35. David G Schaeffer, Memoirs From a Small-Scale Course On Industrial Math, Notices AMS, 43(1996), 550-557.
  36. Shearer, Michael and Schaeffer, David G., A class of fully nonlinear $2\times 2$ systems of partial differential equations, Comm. Partial Differential Equations, vol. 20, no. 7-8, pp. 1105--1131, 1995
  37. Shearer, Michael and Schaeffer, David G., Fully nonlinear hyperbolic systems of partial differential equations related to plasticity, Comm. Partial Differential Equations, vol. 20, no. 7-8, pp. 1133--1153, 1995
  38. Garaizar, F. Xabier and Schaeffer, David G., Numerical computations for shear bands in an antiplane shear model, J. Mech. Phys. Solids, vol. 42, no. 1, pp. 21--50, 1994
  39. Gardner, Carl L. and Schaeffer, David G., Numerical simulation of uniaxial compression of a granular material with wall friction, SIAM J. Appl. Math., vol. 54, no. 6, pp. 1676--1692, 1994
  40. Shearer, Michael and Schaeffer, David G., Unloading near a shear band in granular material, Quart. Appl. Math., vol. 52, no. 3, pp. 579--600, 1994
  41. F.X. Garzizar, David G Schaeffer, M. Shearer, J. Trangenstein, Formation and Development of Shear Bands in Granular Material, Trans. of 11th Army Conf. on Appl. Math. & Computing.
  42. Shearer, Michael and Schaeffer, David G., The initial value problem for a system modelling unidirectional longitudinal elastic-plastic waves, SIAM J. Math. Anal., vol. 24, no. 5, pp. 1111--1144, 1993
  43. Schaeffer, David G. and Shearer, Michael, Unloading near a shear band: a free boundary problem for the wave equation, Comm. Partial Differential Equations, vol. 18, no. 7-8, pp. 1271--1298, 1993
  44. Schaeffer, David G. and Schecter, Stephen and Shearer, Michael, Non-strictly hyperbolic conservation laws with a parabolic line, J. Differential Equations, vol. 103, no. 1, pp. 94--126, 1993
  45. Schaeffer, David G., A mathematical model for localization in granular flow, Proc. Roy. Soc. London Ser. A, vol. 436, no. 1897, pp. 217--250, 1992
  46. Schaeffer, David G. and Shearer, Michael, Scale-invariant initial value problems in one-dimensional dynamic elastoplasticity, with consequences for multidimensional nonassociative plasticity, European J. Appl. Math., vol. 3, no. 3, pp. 225--254, 1992
  47. An, Lian Jun and Schaeffer, David G., The flutter instability in granular flow, J. Mech. Phys. Solids, vol. 40, no. 3, pp. 683--698, 1992
  48. Wang, Feng and Gardner, Carl L. and Schaeffer, David G., Steady-state computations of granular flow in an axisymmetric hopper, SIAM J. Appl. Math., vol. 52, no. 4, pp. 1076--1088, 1992
  49. Schaeffer, David G. and Shearer, Michael, Loss of hyperbolicity in yield vertex plasticity models under nonproportional loading, Nonlinear evolution equations that change type, pp. 192--217, 1990, Springer, New York
  50. Schaeffer, David G., Mathematical issues in the continuum formulation of slow granular flow, Two phase flows and waves (Minneapolis, MN, 1989), pp. 118--129, 1990, Springer, New York
  51. Schaeffer, David G., Instability and ill-posedness in the deformation of granular materials, Internat. J. Numer. Anal. Methods Geomech., vol. 14, no. 4, pp. 253--278, 1990
  52. Schaeffer, David G. and Shearer, Michael and Pitman, E. Bruce, Instability in critical state theories of granular flow, SIAM J. Appl. Math., vol. 50, no. 1, pp. 33--47, 1990
  53. Shearer, Michael and Schaeffer, David G., The quasidynamic approximation in critical state plasticity, Arch. Rational Mech. Anal., vol. 108, no. 3, pp. 267--280, 1989
  54. Pitman, E. Bruce and Schaeffer, David G., Instability and ill-posedness in granular flow, Current progress in hyberbolic systems: Riemann problems and computations (Brunswick, ME, 1988), pp. 241--250, 1989, Amer. Math. Soc., Providence, RI
  55. Schaeffer, David G. and Pitman, E. Bruce, Ill-posedness in three-dimensional plastic flow, Comm. Pure Appl. Math., vol. 41, no. 7, pp. 879--890, 1988
  56. Beale, J. Thomas and Schaeffer, David G., Nonlinear behavior of model equations which are linearly ill-posed, Comm. Partial Differential Equations, vol. 13, no. 4, pp. 423--467, 1988
  57. Schaeffer, David G. and Shearer, Michael, Riemann problems for nonstrictly hyperbolic $2\times 2$ systems of conservation laws, Trans. Amer. Math. Soc., vol. 304, no. 1, pp. 267--306, 1987
  58. Pitman, E. Bruce and Schaeffer, David G., Stability of time dependent compressible granular flow in two dimensions, Comm. Pure Appl. Math., vol. 40, no. 4, pp. 421--447, 1987
  59. Schaeffer, David G., Instability in the evolution equations describing incompressible granular flow, J. Differential Equations, vol. 66, no. 1, pp. 19--50, 1987
  60. Shearer, M. and Schaeffer, D. G. and Marchesin, D. and Paes-Leme, P. L., Solution of the Riemann problem for a prototype $2\times 2$ system of nonstrictly hyperbolic conservation laws, Arch. Rational Mech. Anal., vol. 97, no. 4, pp. 299--320, 1987
  61. Schaeffer, David G. and Shearer, Michael, The classification of $2\times 2$ systems of nonstrictly hyperbolic conservation laws, with application to oil recovery, Comm. Pure Appl. Math., vol. 40, no. 2, pp. 141--178, 1987
  62. Shearer, Michael and Schaeffer, David G., Recent developments in nonstrictly hyperbolic conservation laws, Transactions of the fourth Army conference on applied mathematics and computing (Ithaca, N.Y., 1986), pp. 43--52, 1987, U.S. Army Res. Office, Research Triangle Park, NC
  63. Schaeffer, David G. and Shearer, Michael, Three phase flow in a porous medium and the classification of nonstrictly hyperbolic conservation laws, International workshop on applied differential equations (Beijing, 1985), pp. 154--162, 1986, World Sci. Publishing, Singapore
  64. Shearer, Michael and Schaeffer, David G., Three-phase flow in a porous medium and the classification of non-strictly hyperbolic conservation laws, Transactions of the third Army conference on applied mathematics and computing (Atlanta, Ga., 1985), pp. 509--517, 1986, U.S. Army Res. Office, Research Triangle Park, NC
  65. Schaeffer, David G., Instability in the flow of granular materials, Mathematics applied to fluid mechanics and stability (Troy, N.Y., 1985), pp. 274, 1986, SIAM, Philadelphia, PA
  66. Golubitsky, M. and Marsden, J. and Schaeffer, D., Bifurcation problems with hidden symmetries, Partial differential equations and dynamical systems, pp. 181--210, 1984, Pitman, Boston, MA
  67. Holder, E. J. and Schaeffer, D., Boundary conditions and mode jumping in the von K\'arm\'an equations, SIAM J. Math. Anal., vol. 15, no. 3, pp. 446--458, 1984
  68. Schaeffer, David G., Topics in bifurcation theory, Systems of nonlinear partial differential equations (Oxford, 1982), pp. 219--262, 1983, Reidel, Dordrecht
  69. Golubitsky, Martin and Schaeffer, David, A discussion of symmetry and symmetry breaking, Singularities, Part 1 (Arcata, Calif., 1981), pp. 499--515, 1983, Amer. Math. Soc., Providence, RI
  70. Ball, J. M. and Schaeffer, D. G., Bifurcation and stability of homogeneous equilibrium configurations of an elastic body under dead-load tractions, Math. Proc. Cambridge Philos. Soc., vol. 94, no. 2, pp. 315--339, 1983
  71. Golubitsky, Martin and Schaeffer, David, Bifurcations with ${\rm O}(3)$\ symmetry including applications to the B\'enard problem, Comm. Pure Appl. Math., vol. 35, no. 1, pp. 81--111, 1982
  72. Schaeffer, David, General introduction to steady state bifurcation, Dynamical systems and turbulence, Warwick 1980 (Coventry, 1979/1980), pp. 13--47, 1981, Springer, Berlin
  73. Golubitsky, Martin and Keyfitz, Barbara Lee and Schaeffer, David G., A singularity theory analysis of a thermal-chainbranching model for the explosion peninsula, Comm. Pure Appl. Math., vol. 34, no. 4, pp. 433--463, 1981
  74. Schaeffer, David G. and Golubitsky, Martin A., Bifurcation analysis near a double eigenvalue of a model chemical reaction, Arch. Rational Mech. Anal., vol. 75, no. 4, pp. 315--347, 1980/81
  75. Golubitsky, Martin and Keyfitz, Barbara L. and Schaeffer, David, A singularity theory approach to qualitative behavior of complex chemical systems, New approaches to nonlinear problems in dynamics (Proc. Conf., Pacific Grove, Calif., 1979), pp. 257--270, 1980, SIAM, Philadelphia, Pa.
  76. Golubitsky, Martin and Schaeffer, David, A singularity theory approach to steady-state bifurcation theory, Nonlinear partial differential equations in engineering and applied science (Proc. Conf., Univ. Rhode Island, Kingston, R.I., 1979), pp. 229--254, 1980, Dekker, New York
  77. Golubitsky, Martin and Schaeffer, David, A qualitative approach to steady-state bifurcation theory, New approaches to nonlinear problems in dynamics (Proc. Conf., Pacific Grove, Calif., 1979), pp. 43--51, 1980, SIAM, Philadelphia, Pa.
  78. Schaeffer, David G., Qualitative analysis of a model for boundary effects in the Taylor problem, Math. Proc. Cambridge Philos. Soc., vol. 87, no. 2, pp. 307--337, 1980
  79. Schaeffer, David and Golubitsky, Martin, Boundary conditions and mode jumping in the buckling of a rectangular plate, Comm. Math. Phys., vol. 69, no. 3, pp. 209--236, 1979
  80. Golubitsky, M. and Schaeffer, D., An analysis of imperfect bifurcation, Bifurcation theory and applications in scientific disciplines (Papers, Conf., New York, 1977), pp. 127--133, 1979, New York Acad. Sci., New York
  81. Golubitsky, M. and Schaeffer, D., A theory for imperfect bifurcation via singularity theory, Comm. Pure Appl. Math., vol. 32, no. 1, pp. 21--98, 1979
  82. Golubitsky, M. and Schaeffer, D., Imperfect bifurcation in the presence of symmetry, Comm. Math. Phys., vol. 67, no. 3, pp. 205--232, 1979
  83. Schaeffer, David G., An application of the Nash-Moser theorem to a free boundary problem, Nonlinear partial differential equations and applications (Proc. Special Sem., Indiana Univ., Bloomington, Ind., 1976-1977), pp. 129--143, 1978, Springer, Berlin
  84. Schaeffer, David G., Non-uniqueness in the equilibrium shape of a confined plasma, Comm. Partial Differential Equations, vol. 2, no. 6, pp. 587--600, 1977
  85. Schaeffer, David G., Some examples of singularities in a free boundary, Ann. Scuola Norm. Sup. Pisa Cl. Sci. (4), vol. 4, no. 1, pp. 133--144, 1977
  86. Schaeffer, David G., One-sided estimates for the curvature of the free boundary in the obstacle problem, Advances in Math., vol. 24, no. 1, pp. 78--98, 1977
  87. Guillemin, Victor and Schaeffer, David, On a certain class of Fuchsian partial differential equations, Duke Math. J., vol. 44, no. 1, pp. 157--199, 1977
  88. Schaeffer, David G., Supersonic flow past a nearly straight wedge, Duke Math. J., vol. 43, no. 3, pp. 637--670, 1976
  89. Schaeffer, David G., A new proof of the infinite differentiability of the free boundary in the Stefan problem, J. Differential Equations, vol. 20, no. 1, pp. 266--269, 1976
  90. Schaeffer, David G., Singularities and the obstacle problem, Differential geometry (Proc. Sympos. Pure Math., Vol. XXVII, Stanford Univ., Stanford, Calif., 1973), Part 2, pp. 339--340, 1975, Amer. Math. Soc., Providence, R.I.
  91. Schaeffer, David G., On the existence of discrete frequencies of oscillation in a rotating fluid, Studies in Appl. Math., vol. 54, no. 3, pp. 269--274, 1975
  92. Schaeffer, David G., An example of generic regularity for a non-linear elliptic equation, Arch. Rational Mech. Anal., vol. 57, pp. 134--141, 1975
  93. Guillemin, V. and Schaeffer, D., Fourier integral operators from the Radon transform point of view, Differential geometry (Proc. Sympos. Pure Math., Vol. XXVII, Stanford Univ., Stanford, Calif., 1973), Part 2, pp. 297--300, 1975, Amer. Math. Soc., Providence, R.I.
  94. Schaeffer, David G., A stability theorem for the obstacle problem, Advances in Math., vol. 17, no. 1, pp. 34--47, 1975
  95. Golubitsky, Martin and Schaeffer, David G., Stability of shock waves for a single conservation law, Advances in Math., vol. 16, pp. 65--71, 1975
  96. Schaeffer, David G., The capacitor problem, Indiana Univ. Math. J., vol. 24, no. 12, pp. 1143--1167, 1974/75
  97. Guillemin, V. and Schaeffer, D., Remarks on a paper of D. Ludwig, Bull. Amer. Math. Soc., vol. 79, pp. 382--385, 1973
  98. Schaeffer, David G., An application of von Neumann algebras to finite difference equations, Partial differential equations (Proc. Sympos. Pure Math., Vol. XXIII, Univ. California, Berkeley, Calif., 1971), pp. 183--194, 1973, Amer. Math. Soc., Providence, R.I.
  99. Schaeffer, David G., A regularity theorem for conservation laws, Advances in Math., vol. 11, pp. 368--386, 1973
  100. Schaeffer, David G., An index theorem for systems of difference operators on a half space, Inst. Hautes \'Etudes Sci. Publ. Math., no. 42, pp. 121--127, 1973
  101. Schaeffer, David G., Approximation of the Dirichlet problem on a half space, Acta Math., vol. 129, no. 3--4, pp. 281--295, 1972
  102. Schaeffer, David G., An application of von Neumann algebras to finite difference equations, Ann. of Math. (2), vol. 95, pp. 117--129, 1972
  103. Coburn, L. A. and Douglas, R. G. and Schaeffer, D. G. and Singer, I. M., $C\sp{\ast} $-algebras of operators on a half-space. II. Index theory, Inst. Hautes \'Etudes Sci. Publ. Math., no. 40, pp. 69--79, 1971
  104. Schaeffer, David G., Wiener-Hopf factorization of the symbol of an elliptic difference operator, J. Functional Analysis, vol. 5, pp. 383--394, 1970
  105. Schaeffer, David G., An extension of Hartogs' theorem for domains whose boundary is not smooth, Proc. Amer. Math. Soc., vol. 25, pp. 714--715, 1970
  106. Schaeffer, David G., The Dirichlet problem with generalized functions as data, Ann. Mat. Pura Appl. (4), vol. 83, pp. 153--174, 1969
  107. Schaeffer, David G., A note on the representation of a solution of an elliptic differential equation near an isolated singularity, Proc. amer. Math. Soc., vol. 23, pp. 450--454, 1969

Papers Accepted

  1. D.G. Schaeffer, A. Catlla, T. Witelski, E. Monson, A. Lin, On spiking models of synaptic activity and impulsive differential equations, SIAM Review (2007)
  2. D.G. Schaeffer, W. Ying, X. Zhao, Asymptotic spproximation of an ionic model for cardiac restitution, Nonlinear Dynamics (2007)
  3. D.G. Schaeffer, J. Cain, Shortening of action potential duraction near an insulating boundary, Math Medicine and Biology (2007)
  4. D.G. Schaeffer, C. Berger, D. Gauthier, H. Dobrovolny, W. Krassowska, X. Zhao, Period-doubling bifurcation to alternans in paced cardiac tissue: crossover from smooth to border-collision characteristics, Phys. Rev. Lett, vol. 99 (2007), pp. 058101

Papers Submitted

  1. D.G. Schaeffer, M. Beck, C. Jones, and M. Wechselberger, Electrical waves in a one-dimensional model of cardiac tissue, SIAM Applied Dynamical Systems (2007)
  2. D.G. Schaeffer and Shu Dai, Spectrum of a linearized amplitude equation for alternans in a cardiac fiber, SIAM Analysis (2007)
  3. D.G. Schaeffer and R. Iverson, Steady and intermittent slipping in a model of landslide motion regulated by pore-pressure feedback, SIAM Applied Math (2007)
  4. David G. Schaeffer, D. Gauthier, W. Krassowska, Defibrillation with small shocks: myth or reality, Chaos , submitted 2002

Preprints

  1. D.G. Schaeffer, A. Catlla, T. Witelski, E. Monson, A. Lin, Annular patterns in reaction-diffusion systems and their implications for neural-glial interactions (2007)