Helping the surgeon: epicardial 3D echocardiography in aortic dissection

A74-year-old woman was admitted to the emergency room with acute severe chest pain, dyspnoea and a history of giant cell arteritis and polymyalgia rheumatica. Her heart rate was 95 beats/min, arterial blood pressure was 100/60 mm Hg, and a diastolic murmur was present along the right upper sternal border. She was neurologically intact, with clear lungs, palpable normal pulses in the right radial and in both femoral arteries, and a filiform left radial pulse. Transthoracic echocardiography revealed aortic dissection type A with moderate aortic regurgitation. Aortography confirmed the diagnosis and the extension of the dissection. The patient was taken into the operating room where, after sternotomy, real-time threedimensional (RT3DE) epicardial echocardiography was carried out (iE33, Philips) with the new probe X5-1, demonstrating the tear (panel A). The exact location and dimension of the tear were easily pointed out, 5 mm from the sinotubular junction, with the false lumen reaching the aortic root above the coronary ostia (panel B). The patient underwent aortic dissection repair with a ‘‘button Bentall’’ procedure with a biologic prosthesis. RT3DE offered to the surgeon an impressive, dynamic, precise assessment of the tear and a realistic representation of the anatomical dissection, which was useful for surgical planning

Resistivity Tomography of a traces test experiment and local hydraulic properties assessment from data

none5noComputational Methods in Water Resources XVII International Conference, San Francisco, CA , AbstractnoneCAMPORESE M; CASSIANI G; DEIANA R; FABBRI P.; SALANDIN SCamporese, Matteo; Cassiani, G; Deiana, Rita; Fabbri, Paolo; Salandin, S

Hydrological modeling in swelling/shrinking peat soils

Peatlands respond to natural hydrologic cycles of precipitation and evapotranspiration with reversible deformations due to variations of water content in both the unsaturated and saturated zone. This phenomenon results in short-term vertical displacements of the soil surface that superimpose to the irreversible long-term subsidence naturally occurring in drained cropped peatlands because of bio-oxidation of the organic matter. These processes cause changes in the peat structure, in particular, soil density and void ratio. The consequential changes in the hydrological parameters need to be incorporated in water flow dynamical models. In this paper, we present a new constitutive relationship for the soil shrinkage characteristic (SSC) in peats by describing the variation of porosity with moisture content. This model, based on simple physical considerations, is valid for both anisotropic and isotropic three-dimensional peat deformations. The capability of the proposed SSC to accurately describe the deformation dynamics has been assessed by comparison against a set of laboratory experimental results recently published. The constitutive relationship has been implemented into a Richards' equation\u2013based numerical code and applied for the simulation of the peat soil dynamics as observed in a peatland south of the Venice Lagoon, Italy, in an ad hoc field experiment where the relevant parameters are continuously measured. The modeling results match well a large set of field data encompassing a period of more than 50 days and demonstrate that the proposed approach allows for a reliable reproduction of the soil vertical displacement dynamics as well as the hydrological behavior in terms of, for example, water flow, moisture content, and suction

Two dimensional hydrological simulation in elastic swelling/shrinking peat soils

Peatlands respond to natural hydrologic cycles of precipitation and evapotranspiration with reversible deformations due to variations of water content in both the unsaturated and saturated zone. This phenomenon results in short-term vertical displacements of the soil surface that superimpose to the irreversible long-term subsidence naturally occurring in drained cropped peatlands because of bio-oxidation of the organic matter. The yearly sinking rates due to the irreversible process are usually comparable with the short-term deformation (swelling/shrinkage) and the latter must be evaluated to achieve a thorough understanding of the whole phenomenon. A mathematical model describing swelling/shrinkage dynamics in peat soils under unsaturated conditions has been derived from simple physical considerations, and validated by comparison with laboratory shrinkage data. The two-parameter model relates together the void and moisture ratios of the soil. This approach is implemented in a subsurface flow model describing variably saturated porous media flow (Richards' equation), by means of an appropriate modification of the general storage term. The contribution of the saturated zone to total deformation is considered by using information from the elastic storage coefficient. Simulations have been carried out for a drained cropped peatland south of the Venice Lagoon (Italy), for which a large data set of hydrological and deformation measurements has been collected since the end of 2001. The considered domain is representative of a field section bounded by ditches, subject to rainfall and evapotranspiration. The comparison between simulated and measured quantities demonstrates the capability of the model to accurately reproduce both the hydrological and deformation dynamics of peat, with values of the relevant parameters that are in good agreement with the literature