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The concepts of self-siniilarity and scale invariance have arisen independently in the areas of phase transitions and fractal geometry. Now it is well accepted t h a t fractals are all around us and the concept of fractals has extended to quite different fields of science. One convinaiug argument in favour of fractals is their beauty. The advent of coriiputer graphics facilities encouraged several authors t o visualize t h e mathematical concept of fractals. The authors of t h e present book are mathematicians and physicists working in t h e field of chaotic dynamics. The positive response t h a t their first pictures of fractals found in exhibitions led them t o the idea of publishing the inost beautiful examples. The volume is divided into 10 sections, each starting with a special mathematical problem. The headings are: Verhulst Dynamics, Julia Sets, Sullivan's Classification of Critical Points, Mandelbrot Set, Hubbard Trees, Cayley's Problem, Newton's Method for Real Equations, A Discrete Volterra-Lotka System, Yang-Lee Zeros, Renormalization. So, the book is priniaril? a treatise of t h e mathematics and physics of special phenomena.However, readers not interested in maths will find i t exciting to look simply a t the beautiful pictures included. Those who want t o redo them on their own computers get a few hints by t h e authors at the end of the book. The good quality of the present edition may serve as strong argument for non-mathernatically minded readers to buy it. One can be sure t h a t those who are fascinated by t h e idea of connecting a r t and science will enjoy this publication. P. PAUFLER

Pacing and implantable cardioverter-defibrillator leads can safely, effectively, and predictably be extracted. Open-heart extractions can be limited to special cases. The results indicate that the traditional policy of abandoning redundant leads, instead of removing them, may be obsolete in many patients.

A comprehensive analysis of the Euler-Jacobi problem of motion in the field of two fixed attracting centers is given, first classically and then quantum mechanically in semiclassical approximation. The system was originally studied in the context of celestial mechanics but, starting with Pauli's dissertation, became a model for one-electron molecules such as H + 2 (symmetric case of equal centers) or HHe 2+ (asymmetric case of different centers). The present paper deals with arbitrary relative strength of the two centers and considers separately the planar and the three-dimensional problems. All versions represent non-trivial examples of integrable dynamics and are studied here from the unifying point of view of the energy-momentum mapping from phase space to the space of integration constants. The interesting objects are the critical values of this mapping, i.e., its bifurcation diagram, and their pre-images which organize the foliation of phase space into Liouville-Arnold tori. The classical analysis culminates in the explicit derivation of the action variable representation of iso-energetic surfaces. The attempt to identify a system of global actions, smoothly dependent on the integration constants wherever these are non-critical, leads to the detection of monodromy of a special kind which is here described for the first time. The classical monodromy has its counterpart in the quantum version of the two-center problem where it prevents the assignments of unique quantum numbers even though the system is separable. : 05.45.-a nonlinear dynamics and nonlinear dynamical systems; 03.65.sq semiclassical theories and applications; 31.10.+z theory of electronic structure, electronic transitions, and chemical binding

Background: The complex regional pain syndrome (CRPS) and fibromyalgia (FM) are chronic pain syndromes occurring in highly stressed individuals. Despite the known connection between the nervous system and immune cells, information on distribution of lymphocyte subsets under stress and pain conditions is limited. Methods: We performed a comparative study in 15 patients with CRPS type I, 22 patients with FM and 37 age- and sex-matched healthy controls and investigated the influence of pain and stress on lymphocyte number, subpopulations and the Th1/Th2 cytokine ratio in T lymphocytes. Results: Lymphocyte numbers did not differ between groups. Quantitative analyses of lymphocyte subpopulations showed a significant reduction of cytotoxic CD8+ lymphocytes in both CRPS (p < 0.01) and FM (p < 0.05) patients as compared with healthy controls. Additionally, CRPS patients were characterized by a lower percentage of IL-2-producing T cell subpopulations reflecting a diminished Th1 response in contrast to no changes in the Th2 cytokine profile. Conclusions: Future studies are warranted to answer whether such immunological changes play a pathogenetic role in CRPS and FM or merely reflect the consequences of a pain-induced neurohumoral stress response, and whether they contribute to immunosuppression in stressed chronic pain patients.

Recent work has suggested that shell-model x-spectroscopic factors for the decay -+ zO*Pb + 2 are three orders of magnitude too small. This is not the case, as a serious 2 1 2 p o error exists in some of the shell-model calculations.Recent papers by Jackson and Rhoades-Brown (1977a, b, 1978 point out that the published shell-model 2-spectroscopic factors for heavy nuclei are very different from the values derived from experiments. The experimental result is no less than 1000 times the calculated value for the decay '12Po -+ 208Pb + U. This is a quite incredible state of

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