Search

Surgical risk factors for periprosthetic joint infection (PJI) after total knee arthroplasty (TKA) are the subjects of ongoing research. It is unclear if there are specific locations of the surgical area that might act as a pathogen source. Due to the fact that bacterial replication occurs preferably under humid conditions, it was our aim to investigate if irrigation fluid reservoirs on the surgical covers are subject to bacterial colonization. We prospectively observed 40 patients with scheduled aseptic 1-stage TKA revision. At time intervals of 30 min, irrigation samples were tested for microbiological colonization. Additionally, the suction tip was investigated at the end of surgery. Overall, a bacterial detection rate of 25% was found (57/232 samples). Analysis for any positive microbial detection revealed pathogen findings of irrigation fluid in 41.7% of samples after 30 min with a constant increase up to 77.8% after 90 min. Twenty-three percent of suction tips showed bacterial colonization. Coagulase-negative staphylococci, accounting for the majority of PJI, were the predominant pathogens. After an average follow-up of 17 months, no PJI was confirmed. Despite the substantial bacterial load of irrigation fluid, PJI rates were not elevated. Nevertheless, we recommend that irrigation fluid reservoirs should be prevented and not withdrawn by suction.

The behaviour of nano-scale jets emanating from a reservoir under the action of an external force is studied using Langevin dynamics simulations. The advantage of employing a Langevin thermostat to maintain the temperature of the fluid reservoir is highlighted. The effect of hydrodynamic screening introduced by the Langevin thermostat is considered. It is seen that the nature of thermostat plays a crucial role in simulating the onset of instabilities in the liquid structures. A plunger action has been chosen to initiate jet generation. Langevin dynamics is seen to be able to model the physics of nano-scale jets quite accurately. The study also shows that the Langevin dynamics simulations are capable of capturing the dynamics of nano-scale liquid jets, as the nanojet simulated by this method is found to behave in close agreement with the theoretical predictions for nano-scale jets. � 2014 Elsevier B.V.

This work is a multidisciplinary approach of Precambrian weathering and marine sedimentation in order to look for the proxys of the compositional evolution if the Earth oceans and atmosphere. Archaean BIFs (Carajás, Brazil) result from partial oxidation of dissolved oceanic iron, whereas Palaeoproterozoic pyrite bearing sandstones attest the low oceanic Precambrian sulphate levels. One year long atmosphere experiences of rock weathering under Precambrian conditions, supporting a numerical model, constraint the required time interval for the pCO2 decrease from 300 PAL (or Precambrian Atmospheric Level) to Present-day ones (1 PAL) in the Snowball Earth aftermath at a duration in between 200 000 and 500 000 yrs. The comparison between present-day CO2 consumption data and modelled ones underline the relatively low values for Precambrian times likely due to the lack of terrestrial plants. Finally, modelling of abiotic neoproterozoic cap carbonates precipitation display that enriched CO2 submitted to degassing and/or evaporation can explain their formation at the end of the global glaciations events.; Ce travail multidisciplinaire vise à exploiter les enregistrements de l'évolution des enveloppes fluides terrestres au Précambrien (altération continentale et de la sédimentation marine). Des BIFs archéens (Carajás, Brésil) attestent de l'oxydation incomplète du fer dissous océanique, alors que des grès à pyrites indiquent la pauvreté en sulfates océaniques. Des expériences annuelles d'altération de roches en conditions précambriennes, support d'un modèle numérique, encadrent le temps requis pour que la pCO2 atm diminue de 300 PAL (Present Atmospheric Level) à 1 PAL entre 200 000 et 500 000 ans suite aux glaciations globales néoprotérozoïques. La consommation précambrienne de CO2atm, inférieure à l'Actuel, s'explique par l'absence de végétaux terrestres. Enfin, la modélisation de la précipitation abiotique des cap carbonates néoprotérozoïques montre que le dégazage et/ou l'évaporation d'un océan riche en CO2 expliquent la formation de ces roches au sortir des glaciations globales.

This work is a multidisciplinary approach of Precambrian weathering and marine sedimentation in order to look for the proxys of the compositional evolution if the Earth oceans and atmosphere. Archaean BIFs (Carajás, Brazil) result from partial oxidation of dissolved oceanic iron, whereas Palaeoproterozoic pyrite bearing sandstones attest the low oceanic Precambrian sulphate levels. One year long atmosphere experiences of rock weathering under Precambrian conditions, supporting a numerical model, constraint the required time interval for the pCO2 decrease from 300 PAL (or Precambrian Atmospheric Level) to Present-day ones (1 PAL) in the Snowball Earth aftermath at a duration in between 200 000 and 500 000 yrs. The comparison between present-day CO2 consumption data and modelled ones underline the relatively low values for Precambrian times likely due to the lack of terrestrial plants. Finally, modelling of abiotic neoproterozoic cap carbonates precipitation display that enriched CO2 submitted to degassing and/or evaporation can explain their formation at the end of the global glaciations events.; Ce travail multidisciplinaire vise à exploiter les enregistrements de l'évolution des enveloppes fluides terrestres au Précambrien (altération continentale et de la sédimentation marine). Des BIFs archéens (Carajás, Brésil) attestent de l'oxydation incomplète du fer dissous océanique, alors que des grès à pyrites indiquent la pauvreté en sulfates océaniques. Des expériences annuelles d'altération de roches en conditions précambriennes, support d'un modèle numérique, encadrent le temps requis pour que la pCO2 atm diminue de 300 PAL (Present Atmospheric Level) à 1 PAL entre 200 000 et 500 000 ans suite aux glaciations globales néoprotérozoïques. La consommation précambrienne de CO2atm, inférieure à l'Actuel, s'explique par l'absence de végétaux terrestres. Enfin, la modélisation de la précipitation abiotique des cap carbonates néoprotérozoïques montre que le dégazage et/ou l'évaporation d'un océan riche en CO2 expliquent la formation de ces roches au sortir des glaciations globales.

A combined vertical-incidence and wide-angle seismic study provide strong evidence for the presence of large deep-water fluid reservoirs in Middle Miocene-age sediments with areal extents of more than 50 km2 in the Southern Canary Basin. Pronounced seismic bright spots at 300-800 m below seafloor are well imaged on multichannel reflection seismic sections (MCS) and Ocean-Bottom-Hydrophone (OBH) records, acquired on R/V POSEIDON in 1997 and 1999. Normal incidence reflection coefficients of about -0.4, calculated from MCS shot records, indicate strong negative acoustic impedance contrasts. Mud diapirs, observed in the vicinity of the bright spots, outline vertical sediment migration paths. MCS surveys approaching the deep-water commonly lack sufficient wide-angle reflections. In this study, wide-angle reflections have been imaged on OBH records deployed at the seafloor (3800 m water depth) to constrain the seismic origin of the bright spots. The strong direct water wave, generally masking shallow primary reflections, has successfully be suppressed, enabling the application of semblance based velocity analysis. Results from amplitude-versus-offset analyses and full waveform inversion confirm the presence of a low acoustic impedance zone at the bright spots. However, natural origin of fluids associated with the prominent bright spots remain unresolved. Circumstantial evidences such as occurrence of bright spots within the hydrate-stabilty-zone and existence of large magma volumes in the lower crust and upper mantle, point towards methane or carbon dioxide-rich fluids trapped in the sedimentary sequence.