The Carr−Hermans method [Macromolecules 1978, 11, 46−50], often used for determining the fibers diameter d and density ρ in fibrin or other filamentous networks from turbidity data, is found to be remarkably inaccurate when the system's mass fractal dimension D m is >1. An expanded approach based on the knowledge of the system D m and pore size ξ, which can be accurately recovered from low-angle elastic light scattering data or estimated from confocal microscopy, is proposed. By fitting the turbidity data with a function obtained by numerically integrating the fibrin-optimized scattering form factor of a network of cylindrical elements, both d and ρ can be independently recovered. Numerical simulations were employed to validate the reliability and accuracy of the method, which is then applied to evolving fibrin gels data. More in general, this method is extendible to the analysis of other filamentous networks that can be represented as ensembles of cylindrical elements.
The asymmetry in the angular distribution of Drell-Yan dilepton pairs in collisions where just one nucleon is transversely polarised has been examined in the literature with a variety of results, differing mainly by factors of 2. We re-evaluate the asymmetry via twist-3 contributions in collinear factorisation. In order to allow complete and indepth comparison with existing calculations, we supply all calculational details.
We present a method for fluid velocimetry based on a single-exposure analysis of the streak speckle pattern generated by sub-micron tracking particles illuminated with coherent light. It works in real-time and provides two dimensional velocity mappings in the direction orthogonal to the optical axis, independently of particle concentration and size. It is immune of any spurious light acting as undesired heterodyne signal and can probe velocities much higher (∼three orders of magnitude) than methods based on double-exposure analysis. The method has been tested by using rigid diffusers of different heterodyne strength and applied to map the flow of a confined fluid
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