Fractal analysis highlights analogies in arenaceous tubes of Sabellaria alveolata (Metazoa, Polychaeta) and agglutinated tests of foraminifera (Protista).

Bioconstructions of Sabellaria alveolata (Polychaeta Sabellariidae) from southern Sicily (Central Mediterranean) were sampled and analysed through a multidisciplinary approach in order to unravel the construction pattern of arenaceous tubes and explore possible analogies existing between the worm tubes and the agglutinated tests of benthic foraminifera (Protista). Scanning Electron Microscopy and Energy Dispersive Spectroscopy analyses were carried out on entire tubes as well as sectioned ones. Results show that arenaceous tubes are built following a rigorous architectural framework, based on selection and methodical arrangement of the agglutinated grains, and show surprising analogies with the test microstructure previously observed in agglutinated foraminifera. The grain distribution detected in both model species bioconstructions was analysed using a fractal numerical model (Hausdorff fractal dimension). Collected data show that in both organisms the grains were distributed according to a fractal model, indicating that the evolutionary process may have led to finding the same optimal constructive strategy across organisms with an independent evolutionary history, notwithstanding different geometrical scales. Furthermore, in sectioned tubes we observed microplastic fragments agglutinated within the arenaceous wall and in the inter-tube area. This unexpected finding shows that marine animals can be affected by microplastic pollution not only in soft tissues, but also engineered hard structures, and suggests the problem is more pervasive than estimated so far.

[De Quervain's tenosynovitis and work with hand tools: a case study]. / Tenosinovite di De Quervain e lavoro con utensili. Discussione di un caso clinico.

Work-related musculoskeletal disorders of the upper limbs are a frequent complaint and their pathogenetic mechanism is often related to mechanical overload of the body region involved without traumatic events. The occupational origin of such disorders is much debated, since the clinical pictures are often not specific and may be found in subjects who do not perform hazardous work tasks. A better understanding of the relationship between clinical symptoms, diagnosis, and functional capacity would provide a deeper knowledge in decision making for return to work and rehabilitation strategies. In this paper we present a case study of a worker using scissors who developed De Quervain's syndrome in the dominant hand. A methodology for the biomechanical investigation of the work task and the possible occupational aetiology of the clinical picture are discussed according to the findings of the specific literature.