RESUMO
The HVSR (Horizontal to Vertical Spectral Ratio) technique is very popular in the context of seismic microzonation and for the mapping of shallow seismic reflectors, such as the sediment/bedrock transition surface. This easy-to-deploy single station passive seismic technique permits the collection of a considerable amount of HVSR data in a cost-effective way. It is not surprising that some recent studies have adopted single station micro-tremor analyses in order to retrieve information on geological structures in 1D, 2D or even 3D reconstructions. However, the interpolation approaches followed in these studies for extending the punctual HVSR data spatially are not supported by a detailed spatial statistical analysis. Conversely, in order to exploit the informative content and quantify the related uncertainty of HVSR data it is necessary to utilize a deep spatial statistical analysis and objective interpolation approaches. Moreover, the interpolation approach should make it possible to use expert knowledge and auxiliary information. Accordingly, we present an integrated geostatistical approach applied to HVSR data, collected for retrieving information on the morphology of a buried bedrock surface. The geostatistical study is conducted on an experimental dataset of 116 HVSR data collected in a small thermal basin located in the Venetian Plain (Caldiero Basin, N-E Italy). The explorative geostatistical analysis of the data coupled with the use of interpolation kriging techniques permit the extraction of relevant information on the resonance properties of the subsoil. The utilized approach, based on kriging with external drift (or its extension, i.e. regression kriging), permits the researcher to take into account auxiliary information, evaluate the related prediction uncertainty, and highlight abrupt variations in subsoil resonance frequencies. The results of the analysis are discussed, also with reflections pertaining to the geo-engineering and geo-environmental context.
RESUMO
Proximal tibial fractures are difficult lesions to treat because of the involvement of the articular surface, the often occurring comminution, and the precarious condition of the soft tissues, especially following high-energy trauma. Aim of the treatment is to restore the congruence of the articular surface supporting the tibial plateau cartilage which is usually depressed; to fix the fracture with a stable device; to allow early rehabilitation. We present our treatment strategy, utilising closed or open reduction and internal fixation, angle-stable polyaxial plates, immediate osteointegration, when necessary, with autologous bone graft or other osteoconductive material augmented with autologous platelet gel. Surgery is soft-tissue dependent in terms of timing, and it is usually performed directly or under supervision of an experienced surgeon utilising, whenever possible, a tissue sparing technique. A cohort of 58 proximal tibial fractures, surgically treated, from January 2004 to June 2007, was retrospectively reviewed. Fractures were classified according the OTA/AO classification. The assessment of the functional outcome with the use of the Rasmussen score identified good to excellent results in 78% of the cohort 12 months post-surgery. Internal fixation with locking plates, following the principles of MIPO (Minimally Invasive Percutaneous Osteosynthesis), provides satisfactory fracture reduction with good results regarding the mid-term clinical outcome.