Local plasticity of Al thin films as revealed by x-ray microdiffraction

Grain-to-grain interactions dominate the plasticity of Al thin films and establish effective length scales smaller than the grain size. We have measured large strain distributions and their changes under plastic strain in 1.5-microm-thick Al 0.5% Cu films using a 0.8-microm-diameter white x-ray probe at the Advanced Light Source. Strain distributions arise not only from the distribution of grain sizes and orientation, but also from the differences in grain shape and from stress environment. Multiple active glide plane domains have been found within single grains. Large grains behave like multiple smaller grains even before a dislocation substructure can evolve.     

Philosophical Implications of Kadanoff’s Work on the Renormalization Group

This paper investigates the consequences for our understanding of physical theories as a result of the development of the renormalization group. Kadanoff’s assessment of these consequences is discussed. What he called the “extended singularity theorem” (that phase transitons only can occur in infinite systems) poses serious difficulties for philosophical interpretation of theories. Several responses are discussed. The resolution demands a philosophical rethinking of the role of mathematics in physical theorizing.     

Non-linear static and dynamic deformations of shells of revolution†

The rate equation method, previously developed by the authors, is extended to the analysis of static and dynamic finite deformations of shells of revolution. As an example of the technique, the static and dynamic response of an initially flat plate under spatially uniform, but time varying pressure, is analyzed. Full non-linear shell equations are used in the analysis, and results are presented for large static deflections as well as for large amplitude free and forced vibrations.

The accuracy of the rate equation method is verified by comparison with known solutions obtained by other methods. This comparison also establishes the superiority of the rate equation method over other existing methods as far as calculation times and computer storage requirements are concerned.     

Emergence,Singularities, and Symmetry Breaking

This paper looks at emergence in physical theories and argues that an appropriate way to understand socalled “emergent protectorates” is via the explanatory apparatus of the renormalization group. It is argued that mathematical singularities play a crucial role in our understanding of at least some well-defined emergent features of the world.