Technique and indications of percutaneous cholecystostomy in the management of cholecystitis in 2014

The gold standard in treatment of acute cholecystitis is cholecystectomy associated with antibiotics. In certain circumstances, percutaneous cholecystostomy is an interventional alternative. Percutaneous cholecystostomy is usually performed under local anesthesia by the radiologist using ultrasonographic or CT guidance. A drain can be inserted either through a trans-hepatic or a trans-peritoneal approach. Complications occur in nearly 10% of cases including hemorrhage, hemobilia, pneumothorax or bile leaks, depending on whether the approach was trans-hepatic or trans-peritoneal. The main indications for percutaneous cholecystostomy are resistance to medical treatment or severely-ill patients in intensive care. Drains should be maintained 3 to 6 weeks before removal. In patients with good general condition (ASA score I-II), secondary cholecystectomy can be recommended to avoid recurrence

Impact of recycling and lateral sediment input on grain size fining trends – implications for reconstructing tectonic and climate forcings in ancient sedimentary systems

Grain size trends in basin stratigraphy are thought to preserve a rich record of the climatic and tectonic controls on landscape evolution. Stratigraphic models assume that over geological timescales, the downstream profile of sediment deposition is in dynamic equilibrium with the spatial distribution of tectonic subsidence in the basin, sea level and the flux and calibre of sediment supplied from mountain catchments. Here, we demonstrate that this approach in modelling stratigraphic responses to environmental change is missing a key ingredient: the dynamic geomorphology of the sediment routing system. For three large alluvial fans in the Iglesia basin, Argentine Andes we measured the grain size of modern river sediment from fan apex to toe and characterise the spatial distribution of differential subsidence for each fan by constructing a 3D model of basin stratigraphy from seismic data. We find, using a self-similar grain size fining model, that the profile of grain size fining on all three fans cannot be reproduced given the subsidence profile measured and for any sediment supply scenario. However, by adapting the self-similar model, we demonstrate that the grain size trends on each fan can be effectively reproduced when sediment is not only sourced from a single catchment at the apex of the system, but also laterally, from tributary catchments and through fan surface recycling. Without constraint on the dynamic geomorphology of these large alluvial systems, signals of tectonic and climate forcing in grain size data are masked and would be indecipherable in the geological record. This has significant implications for our ability to make sensitive, quantitative reconstructions of external boundary conditions from the sedimentary record

Evidence for self-similar bedload transport on Andean alluvial fans, Iglesia basin, south Central Argentina

Self‐similar downstream grain‐size fining trends in fluvial deposits are being increasingly used to simplify equilibrium sediment transport dynamics in numerical models. Their ability to collapse time‐averaged behavior of a depositional system into a simple mass balance framework makes them ideal for exploring the sensitivity of sediment routing systems to their climatic and tectonic boundary conditions. This is important if we want to better understand the sensitivity of landscapes to environmental change over timescales >102 years. However, the extent to which self‐similarity is detectable in the deposits of natural rivers is not fully constrained. In transport‐limited rivers, stored sediment can be remobilized or “recycled” and this behavior has been highlighted as a mechanism by which externally forced grain‐size fining trends are distorted. Here we evaluate evidence of self‐similarity in surface gravel‐size distributions on three geomorphically diverse alluvial fans in the Iglesia basin, south Central Argentine Andes. We find that size distributions are self‐similar, deviating from that condition only when significant variability occurs in the coarse tails of the distributions. Our analysis indicates a strong correlation between the degree of sediment recycling and the proportion of coarse clasts present on the bed surface. However, by fitting a relative mobility transfer function, we demonstrate that size‐selectivity alone can explain the bulk size distributions observed. This strengthens the application of self‐similar grain size fining models to solving problems of mass balance in a range of geomorphic settings, with an aim for reconstructing environmental boundary conditions from stratigraphy

Control of geomorphic processes on Be-10 concentrations in individual clasts : complexity of the exposure history in Gobi-Altay range (Mongolia)

The dating of alluvial landforms by cosmogenic nuclides requires distinguishing the pre-deposition inheritance from the post-deposition history of the clasts in the studied marker. Moreover, estimating catchment-scale erosion rates from the concentrations of cosmogenic nuclides in active alluvia requires a good knowledge of the local/regional relationships between rock exhumation and transport through space and time. This is still poorly known for timescales of tens of thousand years. In order to document the evolution of clast exhumation and transport rates through time, we analyze in situ Be-10 concentrations in boulders and cobbles from hillslopes to outlet of an arid mountainous catchment located in Gobi-Altay, Mongolia, strongly affected by global climatic changes during the Pleistocene-Holocene period. Samples were collected on bedrock, abandoned alluvial deposits, active colluvia and alluvia. Our results show a large Be-10 scattering in the active river bed, consistent with a low and discontinuous catchment erosion rate dominated by mass wasting and fluvial incision. On the contrary, pre-exposure signal within abandoned terraces is much more homogeneous, consistent with climatic pulses responsible of strong erosional events on hillslopes and rapid fluvial transport. These results show that exhumation/transport processes at the catchment scale vary in style and intensity through time as a consequence of climatic oscillations. The occurrence of abrupt climatic changes during short periods of time recorded by Be-10 concentrations in abandoned alluvia raise questions about the temporal applicability of catchment erosion rates derived from cosmogenic nuclide concentrations measured in sediments of active rivers. On the other hand, strong and short erosion events limit and homogenize the pre-exposure Be-10 signal in associated deposits like debris-flows, making them particularly suitable markers for dating in active tectonic and paleoclimatic studies

Use of lignin and nanoparticles in flame retarded PLA processed through 3D printing

International audienceNatural fibre reinforced composites arouse a growing interest in many applications due to their low carbon footprint and their interesting mechanical performance. In some sectors, fire specifications are also required and lead to the use of flame retardant additives. Due to the hydrophilic nature of the reinforcement, biocomposites are sensitive to humid ageing [1]. Therefore the question arises: what is the influence of flame retardants on ageing behavior and the final fire performance of these materials? In this study, flax fibre reinforced epoxy composites flame retarded by Aluminium diethyl phosphinate or DOPO were submitted to ageing in different humid atmospheres or by immersion in liquid water. Water sorption kinetics of FR biocomposites were studied and discussed with regard to Fick absorption model [2]. Their fire properties were also studied using cone calorimeter. The influence of ageing is only noticeable at high water content. The effect on the HRR curve depends on the nature of FR and is mainly governed by the way water molecules are absorbed into the materials

Use of lignin and nanoparticles in flame retarded PLA processed through 3D printing

International audienceNatural fibre reinforced composites arouse a growing interest in many applications due to their low carbon footprint and their interesting mechanical performance. In some sectors, fire specifications are also required and lead to the use of flame retardant additives. Due to the hydrophilic nature of the reinforcement, biocomposites are sensitive to humid ageing [1]. Therefore the question arises: what is the influence of flame retardants on ageing behavior and the final fire performance of these materials? In this study, flax fibre reinforced epoxy composites flame retarded by Aluminium diethyl phosphinate or DOPO were submitted to ageing in different humid atmospheres or by immersion in liquid water. Water sorption kinetics of FR biocomposites were studied and discussed with regard to Fick absorption model [2]. Their fire properties were also studied using cone calorimeter. The influence of ageing is only noticeable at high water content. The effect on the HRR curve depends on the nature of FR and is mainly governed by the way water molecules are absorbed into the materials

Initiation and recession of the fluvial knickpoints of the Island of Tahiti (French Polynesia)

In this paper, we study the origin and evolution of the 42 knickpoints spanning the Island of Tahiti, a large extinct shield volcano in the South Pacific Ocean (French Polynesia), by combining DEM analysis and numerical modeling. These knickpoints are located along rivers (107 in total) with a total length exceeding 6 km and with a total drainage of >3 km(2). The knickpoint locations do not correspond to lithology, tributary confluence, or uplift. We argue that these knickpoints have been initiated by a sudden sea level drop of 135 m 20 ky ago, and that the littoral cliffs circling two-thirds of Tahiti are the result of marine erosion that took place 7 ky ago from a stand level that was 5 m higher than now. The head-to-toe height of the knickpoints increases with respect to the knickpoints' distance from the ocean. The major process controlling the knickpoints is plunge-pool incision and the n = 2 stream-power model works well for modeling the profile form. The mean retreat rate of the knickpoints corresponds very well with a drainage-area dependant model with velocities ranging from 0.17 to 1.2 m/y

New experimental setup for continuous mass flux measurement in pervaporation

International audiencePervaporation is a separation process of liquid mixtures through a thin non-porous membrane. In vacuum pervaporation, the global mass flux is classically estimated by weighing the mass of permeate collected in cold traps. In this work, we propose a new experimental setup that allows a continuous measurement of the mass flux. The new mass flux method measurement was validated for single component permeation (ethanol and water) by comparing mass of permeate collected in cold traps with the level decrease of feed liquid measured with a pressure sensor. This new setup can be useful for laboratory studies dealing with the evolution of mass flux according to different parameters of the process as, for example, the permeate side pressure level or temperature of liquid feed

Implementation of a program based on adapted physical activity and recommendations for second cancers prevention for adolescents and young adults with cancer

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