Colonic perforation by a transmural and transvalvular migrated retained sponge: Multi-detector computed tomography findings.

Transmural migrated retained sponges usually impact at the level of the ileo-cecal valve leading to a small bowel obstruction. Once passed through the ileo-cecal valve, a retained sponge can be propelled forward by peristaltic activity and eliminated with feces. We report the case of a 52-year-old female with a past surgical history and recurrent episodes of abdominal pain and constipation. On physical examination, a generalized resistance was observed with tenderness in the right flank. Contrast-enhanced multi-detector computed tomography findings were consistent with a perforated right colonic diverticulitis with several out-pouchings at the level of the ascending colon and evidence of free air in the right parieto-colic gutter along with an air-fluid collection within the mesentery. In addition, a ring-shaped hyperdense intraluminal material was also noted. At surgery, the ascending colon appeared irregularly thickened and folded with a focal wall interruption and a peri-visceral abscess at the level of the hepatic flexure, but no diverticula were found. A right hemi-colectomy was performed and on dissection of the surgical specimen a retained laparotomy sponge was found in the bowel lumen

Experimental study on the rheological behaviour of debris flow

A model able to describe all the processes involved in a debris flow can be very complex owing to the sudden changing of the material that turns from solid into liquid state. The two phases of the phenomenon are analysed separately referring to soil mechanics procedures with regard to the trigger phase, and to an equivalent fluid for the postfailure phase. The present paper is devoted to show the experimental results carried out to evaluate the behaviour assumed by a pyroclastic-derived soil during the flow. A traditional fluid tool has been utilized: a standard rotational rheometer equipped with two different geometries. The soils tested belong to deposits that cover the slopes of the Campania region, Italy, often affected by debris flows. The influence of solid concentration Cv and grain size distribution was tested: the soils were destructurated, sieved and mixed with water starting from the in situ porosity. All material mixtures showed a non-Newtonian fluid behaviour with a yield stress y that increases with a solid volumetric concentration and decreases for an increase of sand fraction. The experimental data were fitted with standard model for fluids. A simple relation between Cv and y was obtained. The yield stress seems to be a key parameter for describing and predicting the post-failure behaviour of debris flows. These results suggest that in the field a small change in solid fraction, due to rainfall, will cause a slight decrease of the static yield stress, readily inducing a rapid flow which will stop only when the dynamic yield stress is reached, namely on a much smoother slope. This can explain the in situ observed post-failure behaviour of debris flows, which are able to flow over very long distances even on smooth slopes

Numerical modeling of a debris flow event occurred in Campania region, southern Italy: consideration on the rheological model parameters on the run-out

In the past, the most widely used model for the analysis of rapid landslides and similar phenomena has been the so-called “lumped mass” model, i.e. a model based on the dynamics of a rigid block sliding over an inclined plane. In recent years, the “lumped mass” model has been put aside in favour of more complex numerical models based on the continuum mechanics theory. The theories set to the continuum are able to describe both the evolution of a limited granular mass and the velocity distribution associated with a landslide on an inclined surface, applying the De Saint Venant equations to the analysis of the granular mass run-out. One of the most critical aspects of such a model is the choice of a representative and adequate constitutive model for the granular-fluid mixture. In order to analyze this aspect, we referred to the catastrophic debris flow event of Pozzano (Napoli), occurred in 1997, which is extensively documented in literature. We applied the two-dimensional code DAN –W (largely used in back analysis of debris flows occurred in Campania region). The constitutive model used is the Bingham ones with three different pair of parameters for the yield stress and Bingham viscosity. The numerical model was then used in order to highlight the differences between the numerical results with the three pairs of parameters adopted on the base of extensive laboratory investigation (e.g., model A), in situ observations (e.g., model B) and a hybrid procedure proposed (e.g., model C). The proposed procedure try to take into account the scale effect between the laboratory experiments (model) and the real events (prototype)

Natural Hazards and Earth System Sciences Experimental study on the rheological behaviour of debris flow

A model able to describe all the processes involved in a debris flow can be very complex owing to the sudden changing of the material that turns from solid into liquid state. The two phases of the phenomenon are analysed separately referring to soil mechanics procedures with regard to the trigger phase, and to an equivalent fluid for the postfailure phase. The present paper is devoted to show the experimental results carried out to evaluate the behaviour assumed by a pyroclastic-derived soil during the flow. A traditional fluid tool has been utilized: a standard rotational rheometer equipped with two different geometries. The soils tested belong to deposits that cover the slopes of the Campania region, Italy, often affected by debris flows. The influence of solid concentration Cv and grain size distribution was tested: the soils were destructurated, sieved and mixed with water startin

Criteri di valutazione ecografica nella diagnostica del melanoma e dell’epitelioma basocellulare

Il melanoma e l’epitelioma basocellulare rappresentano due tumori cutanei maligni la cui diagnosi precoce è di fondamentale importanza per una corretta gestione terapeutica. Con l’ultrasonografia è oggi possibile analizzare il pattern di tali neoformazioni e distinguere il melanoma dalle lesioni benigne; inoltre, è possibile effettuare la determinazione pre-operatoria del loro spessore; identificare i margini di escissione per guidare correttamente l’intervento chirurgico. L’ultrasonografia permette anche, di valutare la vascolarizzazione delle lesioni mediante color-power Doppler. Lo scopo del nostro studio è stato quello di analizzare le caratteristiche ecografiche di melanoma (27 casi) ed epitelioma basocellulare (7 casi) utilizzando una sonda lineare ad elevata risoluzione (17 MHz) con color-power Doppler, per evidenziare le differenze e valutare le dimensioni e la vascolarizzazione. Gli Autori riportano la loro esperienza su 34 casi esaminati