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A three-dimensional model of the Belousov-Zhabotinskyi reaction was obtained by applying a global vector field reconstruction method starting from the measured time dependence of [CeIV]. This reconstructed model was verified by comparing the topological characteristics of the related attractor to the ones directly reconstructed from the time series by applying derivative coordinates. The template characterizing the reconstructed model was compatible with the one extracted from the data. However, it was not compatible with the template related to the normal-form model.

Radiation pressure exerted on a spherical particle by one extremely focused Gaussian beam is investigated by the use of generalized Lorenz-Mie theory (GLMT). Particular attention is devoted to reverse radiation pressure. GLMT predictions for different descriptions of the incident beam are compared with electrostriction predictions when the particle size is smaller than the wavelength and with geometric-optics predictions when the particle size is larger than the wavelength.

Axisymmetric light beams are defined as light beams for which the component of the Poynting vector in the direction of propagation does not depend on the azimuthal angle in suitably chosen coordinate systems to reveal the symmetric property of the beam. It is shown that such beams are encoded in a set of beam-shape coefficients [g.sub.n] that are, however, defined in a more general way than usual in the case of Gaussian beams. Partial-wave expansions and properties of such beams are studied.

A comparison between two quadrature methods of evaluating beam-shape coefficients in generalized Lorenz-Mie theory, in the case of incident Gaussian beams, is carried out. It is shown that, when the electromagnetic description of the Gaussian beams does not perfectly satisfy Maxwell's equations, both quadrature methods are basically flawed. These flaws do not prevent an accurate evaluation of beam-shape coefficients when their nature is correctly identified, because they produce artifacts that can easily be identified and removed.

The forward scattering of a Gaussian laser beam by a spherical particle located along the beam axis is analyzed with the generalized Lorenz-Mie theory (GLMT) and with diffraction theory. Forward-scattering and near-forward-scattering profiles from electrodynamically levitated droplets, 51.6 [[micro]meter] in diameter, are also presented and compared with GLMT-based predictions. The total intensity in the forward direction, formed by the superposition of the incident and the scattered fields, is found to correlate with the particle-extinction cross section, the particle diameter, and the beam width. Based on comparison with the GLMT, the diffraction solution is accurate when beam widths that are approximately greater than or equal to the particle diameter are considered and when large particles that have an extinction efficiency near the asymptotic value of 2 are considered. However, diffraction fails to describe the forward intensity for more tightly focused beams. The experimental observations, which are in good agreement with GLMT-based predictions, reveal that the total intensity profile about the forward direction is quite sensitive to particle axial position within a Gaussian beam. These finite beam effects are significant when the ratio of the beam to the particle diameter is less than approximately 5:1. For larger beam-to-particle-diameter ratios, the total field in the forward direction is dominated by the incident beam. Key words: Elastic light scattering, generalized Lorenz-Mie theory, Gaussian beam, diffraction.

Experimental near-forward-scattering diagrams obtained with one particle in optical levitation are recorded and compared with scattering diagrams computed by using the generalized Lorenz-Mie theory. Comparisons concern the particular case of an off-axis location of the particle. Agreement between experimental and computed diagrams is found to be satisfactory. Key words: Laser beam scattering, Lorenz-Mie theory, optical levitation., Optical levitation experiments are performed in a study to evaluate the generalized Lorenz-Mie theory as an optical measuring tool. In the study, scattering diagrams recording an optical levitation of a single particle irradiated by a laser beam are contrasted to scattering charts derived from the use of the generalized Lorenz-Mie theory. Comparisons focused on the off-axis position of the particle.