Propagation of rays in 2D and 3D waveguides: A stability analysis with Lyapunov and reversibility fast indicators.

Propagation of rays in 2D and 3D corrugated waveguides is performed in the general framework of stability indicators. The analysis of stability is based on the Lyapunov and reversibility error. It is found that the error growth follows a power law for regular orbits and an exponential law for chaotic orbits. A relation with the Shannon channel capacity is devised and an approximate scaling law found for the capacity increase with the corrugation depth.

Role of an anti-acetonemic diet in reducing the need for tonsillectomy in children with recurrent tonsillitis.

OBJECTIVE: The aim of this study was to investigate the effectiveness of an anti-acetonemic diet in reducing the need for tonsillectomy especially in the first years of life in children with recurrent tonsillitis. METHODS: From 2002 to 2005 we carried out a prospective randomized study enrolling 1200 children aged 2-10 who were referred to our outpatient services complaining of recurrent tonsillitis. Children were randomly assigned to the case group or to the control group. In case children, clinical signs of persistent ketosis were investigated and a hypolipidic anti-acetonemic diet was prescribed. We compared the mean age of children who underwent tonsillectomy and evaluated the association between an anti-acetonemic diet and avoidance of tonsillectomy. RESULTS: The association between an anti-acetonemic diet and avoidance of tonsillectomy was statistically significant; the mean age of case children who underwent tonsillectomy resulted significantly higher than that of control children. CONCLUSION: By prescribing an appropriate dietetic regimen we obtained a significant decrease in the number of tonsillectomies for recurrent tonsillitis and an increase in the mean age of the children treated surgically.

[Severe adenotonsillar hypertrophy in children: a new modality of surgical treatment]. / Ipertrofia adenotonsillare grave del bambino: una nuova modalità di trattamento chirurgico.

The hyperplasia of the palatine tonsils, which can be often found in children suffering from the so-called "lymphatism", cannot be considered a pathological state; it simply indicates the attempt of the organism to restore a functional balance between the antigenic shock on one hand and the unitary inadequacy of the lymphatic cells to performs their tasks on the other hand. However, this hyperplasia is sometimes so serious to cause respiratory ailments and predispose several pathologies: in these cases, a surgical operation becomes necessary. Since the tonsillectomy deprives these children of the important defensive barrier represented by the palatine tonsils and the results given by the monotonsillectomy have proved to be not completely satisfactory, both for the phlogosis and for the vicarious hypertrophy of the remaining tonsil, the Authors propose a new surgical technique (never suggested before) in cases of mechanical oropharyngeal obstruction due to hyperplasia of the palatine tonsils. This surgical operation, called bilateral tonsillotomia, consists in removing the tonsillary tissue exceeding the ideal connection line between the borders of the tonsillary pillars.