Rôle of contrast media viscosity in altering vessel wall shear stress and relation to the risk of contrast extravasations

Iodinated contrast media (CM) are the most commonly used injectables in radiology today. A range of different media are commercially available, combining various physical and chemical characteristics (ionic state, osmolality, viscosity) and thus exhibiting distinct in vivo behaviour and safety profiles. In this paper, numerical simulations of blood flow with contrast media were conducted to investigate the effects of contrast viscosity on generated vessel wall shear stress and vessel wall pressure to elucidate any possible relation to extravasations. Five different types of contrast for Iodine fluxes ranging at 1.5–2.2 gI/s were modelled through 18 G and 20 G cannulae placed in an ideal vein at two different orientation angles. Results demonstrate that the least viscous contrast media generate the least maximum wall shear stress as well as the lowest total pressure for the same flow rate. This supports the empirical clinical observations and hypothesis that more viscous contrast media are responsible for a higher percentage of contrast extravasations. In addition, results support the clinical hypothesis that a catheter tip directed obliquely to the vein wall always produces the highest maximum wall shear stress and total pressure due to impingement of the contrast jet on the vessel wall

comparison of severity of sepsis, delay of anti-infective therapy and ESBL genotype

Infektionen mit extended-spectrum Betalaktamase-produzierenden Enterobacteriaceae (ESBL-E) sind assoziiert mit einer erhöhten Mortalität. Die Unterschiede im klinischen Bild, die den verschiedenen Spezies der ESBL-E oder ESBL-Genotypen geschuldet sind, wurden noch nicht ausreichend untersucht. Wir führten eine Kohortenstudie zur Bewertung der Risikofaktoren für Sterblichkeit in Fällen mit einer ESBL-E-Bakteriämie (K. pneumoniae oder E. coli) und zur Bewertung der Risikofaktoren für Sepsis mit Organversagen durch. Eingeschlossen wurden alle Patienten unserer Institution mit einer ESBL-E-Bakteriämie in der Zeit von 2008 bis 2011. Epidemiologische Basisdaten, zugrundeliegende Komorbiditäten, Ursprung der Bakteriämie, Schweregrad der Sepsis und Daten zur zeitlichen Verzögerung bis zu Beginn der adäquaten antibiotischen Therapie wurden gesammelt. Die Isolate wurden mittels PCR auf das Vorhandensein von ESBL-Genen und plasmidvermittelten AmpC β-Laktamasen untersucht. Wir führten eine Cox Regressionsanalyse zur Mortalität und eine multivariable logische Regression zu den Risikofaktoren für eine Sepsis mit Organversagen durch. Insgesamt wurden 219 Fälle in die Analyse eingeschlossen: 71,3% mit E. coli, 26,9% mit K. pneumoniae. Wir fanden keine signifikanten Unterschiede bei der Krankenhaussterblichkeit (ESBL-E. coli 23.8% vs. ESBL-K. pneumoniae 27.1%, p=0.724). Bakteriämien mit K. pneumoniae (OR 4.5, p<0.001), Lebererkrankungen (OR 3.4, p=0.004) oder Nierenerkrankungen (OR 6.8, p<0.001) waren mit einem erhöhten Risiko einer Sepsis mit Organversagen vergesellschaftet. Wir fanden signifikante Unterschiede im klinischen Bild zwischen ESBL-E Bakteriämien mit K. pneumoniae und Bakteriämien mit E. coli. Bakteriämien mit K. pneumoniae bieten ein weitaus schwerwiegenderes klinisches Bild und sind mit anderen Risikofaktoren vergesellschaftet als Bakteriämien mit E. coli. Behandlungs- und Präventionsstrategien sollten dementsprechend angepasst werden.Infections with extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-E) are associated with increased mortality. Outcome differences due to various species of ESBL-E or ESBL genotypes are not well investigated. We conducted a cohort study to assess risk factors for mortality in cases of ESBL-E bacteremia (K. pneumoniae or E. coli) and the risk factors for sepsis with organ failure. All consecutive patients of our institution from 2008 to 2011 with bacteremia due to ESBL-E were included. Basic epidemiological data, underlying comorbidities, origin of bacteremia, severity of sepsis and delay of appropriate anti-infective treatment were collected. Isolates were PCR- screened for the presence of ESBL genes and plasmid-mediated AmpC β-lactamases. Cox proportional hazard regression on mortality and multivariable logistic regression on risk factors for sepsis with organ failure was conducted. 219 cases were included in the analysis: 73.1% due to E. coli, 26.9% due to K. pneumoniae. There was no significant difference in hospital mortality (ESBL-E. coli, 23.8% vs. ESBL-K. pneumoniae 27.1%, p=0.724). However, the risk of sepsis with organ failure was associated in cases of K. pneumoniae bacteremia (OR 4.5, p<0.001) and patients with liver disease (OR 3.4, p=0.004) or renal disease (OR 6.8, p<0.001). We found significant differences in clinical presentation of ESBL-E bacteremia due to K. pneumoniae compared to E. coli. As K. pneumoniae cases showed a more serious clinical presentation as E. coli cases and were associated with different risk factors, treatment and prevention strategies should be adjusted accordingly

Grid Metadata Lifetime Control in ActOn

In the Semantic Grid, metadata, as first class citizens, should be maintained up to-date in a cost-effective manner. This includes maxi missing the automation of different aspects of the metadata lifecycle, managing the evolution and change of metadata in distributed contexts, and synchronizing adequately the evolution of all these related entities. In this paper, we introduce a semantic model and its operations which is designed for supporting dynamic metadata management in Active Ontology (Act On), a semantic information integration approach for highly dynamic information sources. Finally, we illustrate the Act On-based metadata lifetime control by EGEE examples

A Practical Hardware Implementation of Systemic Computation

It is widely accepted that natural computation, such as brain computation, is far superior to typical computational approaches addressing tasks such as learning and parallel processing. As conventional silicon-based technologies are about to reach their physical limits, researchers have drawn inspiration from nature to found new computational paradigms. Such a newly-conceived paradigm is Systemic Computation (SC). SC is a bio-inspired model of computation. It incorporates natural characteristics and defines a massively parallel non-von Neumann computer architecture that can model natural systems efficiently. This thesis investigates the viability and utility of a Systemic Computation hardware implementation, since prior software-based approaches have proved inadequate in terms of performance and flexibility. This is achieved by addressing three main research challenges regarding the level of support for the natural properties of SC, the design of its implied architecture and methods to make the implementation practical and efficient. Various hardware-based approaches to Natural Computation are reviewed and their compatibility and suitability, with respect to the SC paradigm, is investigated. FPGAs are identified as the most appropriate implementation platform through critical evaluation and the first prototype Hardware Architecture of Systemic computation (HAoS) is presented. HAoS is a novel custom digital design, which takes advantage of the inbuilt parallelism of an FPGA and the highly efficient matching capability of a Ternary Content Addressable Memory. It provides basic processing capabilities in order to minimize time-demanding data transfers, while the optional use of a CPU provides high-level processing support. It is optimized and extended to a practical hardware platform accompanied by a software framework to provide an efficient SC programming solution. The suggested platform is evaluated using three bio-inspired models and analysis shows that it satisfies the research challenges and provides an effective solution in terms of efficiency versus flexibility trade-off

Technical developments for computed tomography on the CENBG nanobeam line

The use of ion microbeams as probes for computedtomography has proven to be a powerful tool for the three-dimensional characterization of specimens a few tens of micrometers in size. Compared to other types of probes, the main advantage is that quantitative information about mass density and composition can be obtained directly, using specific reconstruction codes. At the Centre d’Etudes Nucléaires de Bordeaux Gradignan (CENBG), this technique was initially developed for applications in cellular biology. However, the observation of the cell ultrastructure requires a sub-micron resolution. The construction of the nanobeamline at the Applications Interdisciplinaires des Faisceaux d’Ions en Region Aquitaine (AIFIRA) irradiation facility has opened new perspectives for such applications. The implementation of computedtomography on the nanobeamline of CENBG has required a careful design of the analysis chamber, especially microscopes for precise sample visualization, and detectors for scanning transmission ion microscopy (STIM) and for particle induced X-ray emission (PIXE). The sample can be precisely positioned in the three directions X, Y, Z and a stepper motor coupled to a goniometer ensures the rotational motion. First images of 3D tomography were obtained on a reference sample containing microspheres of certified diameter, showing the good stability of the beam and the sample stage, and the precision of the motion

Morphological description of the southeastern Cyprus outer shelf and slope regions (eastern Mediterranean)

We present here the first results of the analysis and interpretation of the swath bathymetry and side scan sonar data collected along the southeastern outer shelf and upper slope regions of the Cyprus insular margin (offshore Cape Greco). The resultant bathymetric model and the derivatives (e.g.: slope, aspect, benthic position index) are presented and analyzed in order to describe the morphology of the seabed and the main geomorphological features through quantitative indicators including morphometric indexes and statistical descriptors. The presence of deep sea coral communities (Dendrophylia ramea) in a particular location of the surveyed area is also discussed and tentatively related to the landscape morphology where the colonies are settle

A BDI agent architecture for the GAMA modeling and simulation platform

International audienceWith the increase of computing power and the development of user-friendly multi-agent simulation frameworks, social simulations have become increasingly realistic. However, most agent architectures in these simulations use simple reactive models. Indeed, cognitive agent architectures face two main obstacles: their complexity for the field-expert modeler, and their computational cost. In this paper, we propose a new cognitive agent architecture based on the BDI (Belief-Desire-Intention) paradigm integrated into the GAMA modeling platform and its GAML modeling language. This architecture was designed to be simple-to-use for modelers, flexible enough to manage complex behaviors, and with low computational cost. An experiment carried out with different profiles of end-users shows that the architecture is actually usable even by modelers who have little knowledge in programming and in Artificial Intelligence