Anisotropic jump reorientation occurs in glasses, polymers, and plastic crystals. A general theoretical frame to describe such processes is presented. It generalizes previous work by Ivanov [Sov. Phys. JETP 18, 1041 (1964)]. A tractable model is given by a simple phenomenological assumption on the jump distribution. Analytical results and fast numerical methods to evaluate the relevant quantities are derived. The model is validated by comparing the predictions with ESR experiments on stiff, cylindrical tracers dissolved in the glassformer o-terphenyl. (C) 2001 American Institute of Physics

Aims of this commentary is to report the most recent views about epidemiology, diagnostic procedures, malignancy risk factors and clinical management of thyroid nodules in children. On the basis of our personal experiences and recent literature evidences, we conclude that: a) if nodule is accompanied by lymphadenopathy and/or other alert findings, fine-needle aspiration biopsy (FNAB) should be recommended; b) if no lymphadenopathy and no other clinical and ultrasonographic alert signs are observed, work-up can progress to FNAB only if nodule persists or grows over time, even under levo-thyroxine therapy.

The detection of communities of peers characterized by similar interests is currently a challenging research area. To ease the diffusion of relevant data to interested peers, similarity based overlays define links between similar peers by exploiting a similarity function. However, existing solutions neither give a clear definition of peer communities nor define a clear strategy to partition the peers into communities. As a consequence, the spread of the information cannot be confined within a well defined region of an overlay. This paper proposes a distributed protocol for the detection of communities in a P2P network. Our approach is based on the definition of a distributed voting algorithm where each peer chooses the more similar peers among those in a limited neighbourhood range. The identifier of the most representative peer is exploited to identify a community. The paper shows the effectiveness of our approach by presenting a set of experimental results.The research leading to these results has received funding from CONTRAIL (EU-FP7-257438),RECOGNITION (EU-FP7-257756) and SCUBE (EU-FP7-215483) EU projects.

S2 New technologies, new opportunities, new interpretative challenges in molecular genetics of Cystic Fibrosis Alessandra Coiana

The article describes the case of a 4-year-old girl present-ing with fever and dyspnea. Blood tests showed neutrophilic leukocytosis and a significant increase in inflammation markers. The antibiotic therapy (macrolide and amoxicillin) did not produce any clinical improvement. A chest X-ray and CT showed a pleural empyema associated to trilobar right pneumonia. An evacuative videothoracoscopy was then performed. Clinical evolution was positive with full remission. The real-time polymerase chain reaction enabled to isolate genetic sequences of Streptococcus pneumoniae type 3, one of the serotypes involved in the invasive pneumococcal disease and contained in the pneumococcal 13-valent conjugate vaccine (PCV13). The patient had completed a full PCV13 vaccination before two years of age. Despite antibiotic treatment and the spread of vaccinations, pleural empyema is still a frequent complication of pneumonia to date. Several studies suggest a poor effective-ness of the pneumococcal vaccine against the serotype 3. Moreover, the implementation of PCV13 may have influenced the distribution of serotypes of S. pneumoniae not included in this vaccine and the phenomenon of serotype replacement. Nonetheless, the phenomenon of serotype replacement does not seem to be exclusively due to the effect of vaccination programmes.