ill the past three decades there has been enonnous progress in identifying the es­ sential role that "nonlinearity" plays in physical systems. Classical nonlinear wave equations can support localized, stable "soliton" solutions, and nonlinearities in quantum systems can lead to self-trapped excitations, such as polarons. Since these nonlinear excitations often dominate the transport and response properties of the systems in which they exist, accurate modeling of their effects is essential to interpreting a wide range of physical phenomena. Further, the dramatic de­ velopments in "deterministic chaos", including the recognition that even simple nonlinear dynamical systems can produce seemingly random temporal evolution, have similarly demonstrated that an understanding of chaotic dynamics is vital to an accurate interpretation of the behavior of many physical systems. As a conse­ quence of these two developments, the study of nonlinear phenomena has emerged as a subject in its own right. During these same three decades, similar progress has occurred in understand­ ing the effects of "disorder". Stimulated by Anderson''s pioneering work on "dis­ ordered" quantum solid state materials, this effort has also grown into a field that now includes a variety of classical and quantum systems and treats "disorder" arising from many sources, including impurities, random spatial structures, and stochastic applied fields. Significantly, these two developments have occurred rather independently, with relatively little overlapping research.

ill the past three decades there has been enonnous progress in identifying the es­ sential role that "nonlinearity" plays in physical systems. Classical nonlinear wave equations can support localized, stable "soliton" solutions, and nonlinearities in quantum systems can lead to self-trapped excitations, such as polarons. Since these nonlinear excitations often dominate the transport and response properties of the systems in which they exist, accurate modeling of their effects is essential to interpreting a wide range of physical phenomena. Further, the dramatic de­ velopments in "deterministic chaos", including the recognition that even simple nonlinear dynamical systems can produce seemingly random temporal evolution, have similarly demonstrated that an understanding of chaotic dynamics is vital to an accurate interpretation of the behavior of many physical systems. As a conse­ quence of these two developments, the study of nonlinear phenomena has emerged as a subject in its own right. During these same three decades, similar progress has occurred in understand­ ing the effects of "disorder". Stimulated by Anderson's pioneering work on "dis­ ordered" quantum solid state materials, this effort has also grown into a field that now includes a variety of classical and quantum systems and treats "disorder" arising from many sources, including impurities, random spatial structures, and stochastic applied fields. Significantly, these two developments have occurred rather independently, with relatively little overlapping research.

In the past three decades there has been enormous progressin identifying the essential role that nonlinearity playsin physical systems, including supporting soliton-likesolutions and self-trapped sxcitations such as polarons.during the same period, similarly impressive progress hasoccurred in understanding the effects of disorder in linearquantum problems, especially regarding Anderson localizationarising from impurities, random spatial structures,stochastic applied fields, and so forth.These striking consequences of disorder, noise andnonlinearity frequently occur together in physical systems.Yet there have been only limited attempts to developsystematic techniques which can include all of theseingredients, which may reinforce, complement or frustrateeach other. This book contains a range of articles whichprovide important steps toward the goal of systematicunderstanding and classification of phenomenology.Experts from Australia, Europe, Japan, USA, and the USSRdescribe both mathematical and numerical techniques -especially from soliton and statistical physics disciplines- and applicaations to a number of important physicalsystems and devices, including optical and electronictransmission lines, liquid crystals, biophysics andmagnetism.

In the past three decades there has been enormous progressin identifying the essential role that nonlinearity playsin physical systems, including supporting soliton-likesolutions and self-trapped sxcitations such as polarons.during the same period, similarly impressive progress hasoccurred in understanding the effects of disorder in linearquantum problems, especially regarding Anderson localizationarising from impurities, random spatial structures,stochastic applied fields, and so forth.These striking consequences of disorder, noise andnonlinearity frequently occur together in physical systems.Yet there have been only limited attempts to developsystematic techniques which can include all of theseingredients, which may reinforce, complement or frustrateeach other. This book contains a range of articles whichprovide important steps toward the goal of systematicunderstanding and classification of phenomenology.Experts from Australia, Europe, Japan, USA, and the USSRdescribe both mathematical and numerical techniques -especially from soliton and statistical physics disciplines- and applicaations to a number of important physicalsystems and devices, including optical and electronictransmission lines, liquid crystals, biophysics andmagnetism.

ill the past three decades there has been enonnous progress in identifying the es­ sential role that "nonlinearity" plays in physical systems. Classical nonlinear wave equations can support localized, stable "soliton" solutions, and nonlinearities in quantum systems can lead to self-trapped excitations, such as polarons. Since these nonlinear excitations often dominate the transport and response properties of the systems in which they exist, accurate modeling of their effects is essential to interpreting a wide range of physical phenomena. Further, the dramatic de­ velopments in "deterministic chaos", including the recognition that even simple nonlinear dynamical systems can produce seemingly random temporal evolution, have similarly demonstrated that an understanding of chaotic dynamics is vital to an accurate interpretation of the behavior of many physical systems. As a conse­ quence of these two developments, the study of nonlinear phenomena has emerged as a subject in its own right. During these same three decades, similar progress has occurred in understand­ ing the effects of "disorder". Stimulated by Anderson''s pioneering work on "dis­ ordered" quantum solid state materials, this effort has also grown into a field that now includes a variety of classical and quantum systems and treats "disorder" arising from many sources, including impurities, random spatial structures, and stochastic applied fields. Significantly, these two developments have occurred rather independently, with relatively little overlapping research.

ill the past three decades there has been enonnous progress in identifying the es­ sential role that "nonlinearity" plays in physical systems. Classical nonlinear wave equations can support localized, stable "soliton" solutions, and nonlinearities in quantum systems can lead to self-trapped excitations, such as polarons. Since these nonlinear excitations often dominate the transport and response properties of the systems in which they exist, accurate modeling of their effects is essential to interpreting a wide range of physical phenomena. Further, the dramatic de­ velopments in "deterministic chaos", including the recognition that even simple nonlinear dynamical systems can produce seemingly random temporal evolution, have similarly demonstrated that an understanding of chaotic dynamics is vital to an accurate interpretation of the behavior of many physical systems. As a conse­ quence of these two developments, the study of nonlinear phenomena has emerged as a subject in its own right. During these same three decades, similar progress has occurred in understand­ ing the effects of "disorder". Stimulated by Anderson's pioneering work on "dis­ ordered" quantum solid state materials, this effort has also grown into a field that now includes a variety of classical and quantum systems and treats "disorder" arising from many sources, including impurities, random spatial structures, and stochastic applied fields. Significantly, these two developments have occurred rather independently, with relatively little overlapping research.

In the past three decades there has been enormous progressin identifying the essential role that nonlinearity playsin physical systems, including supporting soliton-likesolutions and self-trapped sxcitations such as polarons.during the same period, similarly impressive progress hasoccurred in understanding the effects of disorder in linearquantum problems, especially regarding Anderson localizationarising from impurities, random spatial structures,stochastic applied fields, and so forth.These striking consequences of disorder, noise andnonlinearity frequently occur together in physical systems.Yet there have been only limited attempts to developsystematic techniques which can include all of theseingredients, which may reinforce, complement or frustrateeach other. This book contains a range of articles whichprovide important steps toward the goal of systematicunderstanding and classification of phenomenology.Experts from Australia, Europe, Japan, USA, and the USSRdescribe both mathematical and numerical techniques -especially from soliton and statistical physics disciplines- and applicaations to a number of important physicalsystems and devices, including optical and electronictransmission lines, liquid crystals, biophysics andmagnetism.

In the past three decades there has been enormous progressin identifying the essential role that nonlinearity playsin physical systems, including supporting soliton-likesolutions and self-trapped sxcitations such as polarons.during the same period, similarly impressive progress hasoccurred in understanding the effects of disorder in linearquantum problems, especially regarding Anderson localizationarising from impurities, random spatial structures,stochastic applied fields, and so forth.These striking consequences of disorder, noise andnonlinearity frequently occur together in physical systems.Yet there have been only limited attempts to developsystematic techniques which can include all of theseingredients, which may reinforce, complement or frustrateeach other. This book contains a range of articles whichprovide important steps toward the goal of systematicunderstanding and classification of phenomenology.Experts from Australia, Europe, Japan, USA, and the USSRdescribe both mathematical and numerical techniques -especially from soliton and statistical physics disciplines- and applicaations to a number of important physicalsystems and devices, including optical and electronictransmission lines, liquid crystals, biophysics andmagnetism.