Lyapunov stability of competitive cells dynamics in tumor mechanobiology

Acta Mechanica Sinica - Poromechanics plays a key role in modelling hard and soft tissue behaviours, by providing a thermodynamic framework in which chemo-mechanical mutual interactions among fluid...     

Locally finite groups with all subgroups either subnormal or nilpotent-by-Chernikov

Let G be a locally finite group satisfying the condition given in the title and suppose that G is not nilpotent-by-Chernikov. It is shown that G has a section S that is not nilpotent-by-Chernikov, where S is either a p-group or a semi-direct product of the additive group A of a locally finite field F by a subgroup K of the multiplicative group of F, where K acts by multiplication on A and generates F as a ring. Non-(nilpotent-by-Chernikov) extensions of this latter kind exist and are described in detail.     

Numerical simulations of traffic data via fluid dynamic approach

In this paper we introduce a simulation algorithm based on fluid dynamic models to reproduce the behavior of traffic in a portion of the urban network in Rome. Numerical results, obtained comparing experimental data with numerical solutions, show the effectiveness of our approximation.     

Midinfrared dielectric coated metallic waveguides

The transmission characteristics of planar dielectric coated metallic waveguides are investigated. In addition, the coupling of a gaussian beam into the normal modes of these devices and the far field radiated from an open end are discussed in detail.     

Power semiconductor laser diode arrays characterization

Nowadays, power semiconductor laser diode arrays are becoming a widespread source for a large variety of industrial applications. In particular, the availability of low-cost high-power laser diode arrays makes their use possible in the industrial context for material cutting, welding, diagnostics and processing. In the above applications, the exact control of the beam quality plays a very important role because it directly affects the reliability of the final result. In this paper, we present two different approaches useful for the characterization of the beam quality in laser diode arrays. The first one, starting from total intensity measurements on planes orthogonal to the beam propagation path, is able to deduce the working conditions of each laser setting up the array. The second one is aimed at the measurement of a global quality factor of the array itself; to this end, the empirical extension of the M² concept to composite beams is presented along with some experimental results. As the first technique is especially intended for the non-destructive detection of design problems in the array itself and in the bias circuitry, the second one represents a powerful tool for the rapid on-line diagnostics of the laser beam during its use.     

Separation of bulk lifetime and surface recombination velocity obtained by transverse optical probing and multi-wavelength technique

In this paper, a contactless, all-optical and non-destructive technique for simultaneous measurement of minority carrier recombination lifetime and surface recombination velocity is presented. The principle is based upon measurement, at low injection level, of the free carrier optical absorption transient probed by an infrared beam following electron–hole pairs excitation by a pulsed laser beam working at several wavelengths. Being contactless and non-destructive with respect to the surface to be analyzed, the method is appealing for routine lifetime characterization. A brief review of the theory underlying the measurement technique, aimed to emphasize its advantages and limits, and preliminary experimental data proving the applicability of the new scheme are presented.     

On the possibility of simplifying the thermoelastic equation

By some very simple algebraic manipulations, it is shown as the linear thermoelastic equation can be solved by looking for the solutions of much simpler vectorial equations. As an example the displacements of the reflecting surface of a mirror illuminated by a high power laser beam have been evaluated.

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Sommario Utilizzando alcuni semplici passaggi algebrici, viene mostrato come l'equazione degli spostamenti termoelastici possa essere risolta cercando le soluzioni di equazioni vettoriali molto più semplici. Come esempio vengono calcolate le deformazioni della superficie riflettente di uno specchio investito da un fascio laser di grande potenza.

     

Measurements of the waist and the power distribution across the transverse modes of a laser beam

We describe a novel apparatus which measures the waist, its position and the amplitudes of the transverse modes in a laser system starting from intensity measurements. The validity of our approach is confirmed by many numerical simulations and by preliminary experimental results.     

Self-induced mismatching effects in harmonic generation with ultra-short laser pulses

Relying on exact numerical calculations, we report some simple formulae by which it is possible to take into account any self-induced mismatch effect in second harmonic generation with high power ultra-short laser pulses. In particular, we have considered the following effects: bandwidth effect, thermal effect, frequency chirping, angular tilting, pulse lengthening.     

Growth and remodeling in highly stressed solid tumors

Meccanica - Growing biological media develop residual stresses to make compatible elastic and inelastic growth-induced deformations, which in turn remodel the tissue properties modifying the actual...