Percolation transition in the porous structure of latex-templated silica monoliths

International audiencePorous sol-gel silica monoliths are prepared using PMMA nanoparticles, 60 nm in diameter, as sacrificial templates. The pore-structure of the calcined pellets is investigated through nitrogen adsorption to assess the evolution of the porosity when varying the amount of porogen. The latex templated monoliths present a well defined spherical extrinsic porosity and an intrinsic microporosity due to preparation process. As a result of a careful analysis of the adsorption hysteresis, we identify a percolation threshold of the spherical porosity around 30% volume fraction. This phenomenon, similar to the percolation previously observed in latex-templated silica films, opens the way to the use of latex-templated porous silica monoliths with a tailorable and reliable pore structure

Mesoporous silica films with varying porous volume fraction: direct correlation between ortho-positronium annihilation decay and escape yield into vacuum

accepted for publication in Applied Physics LettersThe behavior of ortho-positronium (o-Ps) in mesoporous silica films implanted with low–energy positrons has been studied as a function of the film porous volume fraction. A lifetime spectrometer allowed determination of o-Ps annihilation decay both inside and outside of the film. A kinetic model is introduced that permits the determination of the yield and rate of escape of o-Ps into vacuum as well as the annihilation decay rate of the trapped o-Ps in the film. It is shown that these undergo a sudden change at a threshold porous volume fraction, above which the o-Ps escape rate to vacuum varies linearly with volume fraction

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome associated with COVID-19: An Emulated Target Trial Analysis.

RATIONALE: Whether COVID patients may benefit from extracorporeal membrane oxygenation (ECMO) compared with conventional invasive mechanical ventilation (IMV) remains unknown. OBJECTIVES: To estimate the effect of ECMO on 90-Day mortality vs IMV only Methods: Among 4,244 critically ill adult patients with COVID-19 included in a multicenter cohort study, we emulated a target trial comparing the treatment strategies of initiating ECMO vs. no ECMO within 7 days of IMV in patients with severe acute respiratory distress syndrome (PaO2/FiO2 <80 or PaCO2 ≥60 mmHg). We controlled for confounding using a multivariable Cox model based on predefined variables. MAIN RESULTS: 1,235 patients met the full eligibility criteria for the emulated trial, among whom 164 patients initiated ECMO. The ECMO strategy had a higher survival probability at Day-7 from the onset of eligibility criteria (87% vs 83%, risk difference: 4%, 95% CI 0;9%) which decreased during follow-up (survival at Day-90: 63% vs 65%, risk difference: -2%, 95% CI -10;5%). However, ECMO was associated with higher survival when performed in high-volume ECMO centers or in regions where a specific ECMO network organization was set up to handle high demand, and when initiated within the first 4 days of MV and in profoundly hypoxemic patients. CONCLUSIONS: In an emulated trial based on a nationwide COVID-19 cohort, we found differential survival over time of an ECMO compared with a no-ECMO strategy. However, ECMO was consistently associated with better outcomes when performed in high-volume centers and in regions with ECMO capacities specifically organized to handle high demand. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/)

TWiki: A Collaborative Space of Internal Documentation, an Efficient Way to Work Together

International audienceThe documentalists at Strasbourg astronomical Data Center (CDS) mine publications in order to update the SIMBAD and VizieR databases with astronomical data. The process of mining publications is quite complex and, over time, the databases and tools used evolve as the field of astronomy evolves. The ingest process needs to be agreed upon, well described, and shared by all involved. This requires specific knowledge and mutual support among the documentalists in interaction with computer engineers and astronomers. The documentalists at CDS have therefore organized and enriched their internal documentation; the wiki collaborative tool is an efficient framework to do so. For more than a decade, the CDS has been developing a "TWiki" collaborative space. Recently, we have created a working group to refurbish the collaborative space and it is now better structured and clearer and this provides new functionality, giving the user a better experience

A New Bibliographical Feature for SIMBAD: Highlighting the Most Relevant Papers for One Astronomical Object

International audienceThe number of bibliographical references attached to an astronomical object in SIMBAD is has been growing continuously over the years. It is important for astronomers to retrieve the most relevant papers, those that give important information about the object of study. This is not easy since there can be many references attached to one object. For instance, in 2014, more than 15,000 objects had been attached to more than 50 references. The location of the object's citations inside the paper and its number of occurrences are important criteria to extract the most relevant papers. Since 2008, because of the DJIN application (a semi-automatic tool to search for object names in full text) this information has been collected. For each article associated with an astronomical object, we know where it is cited and how many times and with which name it appears. Since September 2013, the users of SIMBAD web site can choose to retrieve the most relevant references for an astronomical object depending on its location in the publication. A new formula to sort references by combining all locations, number of occurrences, total number of objects studied, citation count, and year is presented in this paper

How Documentalists Update SIMBAD

International audienceThe Strasbourg astronomical Data Center (CDS) was created in 1972 and has had a major role in astronomy for more than forty years. CDS develops a service called SIMBAD that provides basic data, cross-identifications, bibliography, and measurements for astronomical objects outside the solar system. It brings to the scientific community an added value to content which is updated daily by a team of documentalists working together in close collaboration with astronomers and IT specialists. We explain how the CDS staff updates SIMBAD with object citations in the main astronomical journals, as well as with astronomical data and measurements. We also explain how the identification is made between the objects found in the literature and those already existing in SIMBAD. We show the steps followed by the documentalist team to update the database using different tools developed at CDS, like the sky visualizer Aladin, and the large catalogues and survey database VizieR. As a direct result of this teamwork, SIMBAD integrates almost 10.000 bibliographic references per year. The service receives more than 400.000 queries per day

Working Together at CDS: The Symbiosis Between Astronomers, Documentalists, and IT Specialists

International audienceSince the CDS (Centre de Données astronomiques de Strasbourg) began a little more than forty years ago, astronomers, documentalists, and information technology (IT) specialists have been working together. The synergy between these three professional groups support the core of the work and is becoming more and more crucial with the increasing volume and complexity of data handled. The astronomers use their understanding of the subject and of users' needs to help to maintain the accuracy and the relevance of data. The computer engineers enhance these data by maintaining the database framework and continuing to add useful tools to retrieve and reuse this content. Finally, the documentalists, by definition, manage the content. They do so with the help of IT tools developed at CDS; they analyze the publications, extract the relevant information, verify the data, make comparisons with existing data, add the useful information in VizieR and SIMBAD, and confer with astronomers to make corrections, if needed. After an historical review of the evolution in data and the way data have been provided at CDS, we will further discuss the fundamental roles of the three professional groups to support the mission of the CDS

Extracorporeal Membrane Oxygenation for Severe Acute Respiratory Distress Syndrome Associated with COVID-19: An Emulated Target Trial Analysis

International audienc

Characteristics, management, and prognosis of elderly patients with COVID-19 admitted in the ICU during the first wave: insights from the COVID-ICU study

International audienceBackground: The COVID-19 pandemic is a heavy burden in terms of health care resources. Future decision-making policies require consistent data on the management and prognosis of the older patients (&gt; 70 years old) with COVID-19 admitted in the intensive care unit (ICU). Methods: Characteristics, management, and prognosis of critically ill old patients (&gt; 70 years) were extracted from the international prospective COVID-ICU database. A propensity score weighted-comparison evaluated the impact of intubation upon admission on Day-90 mortality. Results: The analysis included 1199 (28% of the COVID-ICU cohort) patients (median [interquartile] age 74 [72–78] years). Fifty-three percent, 31%, and 16% were 70–74, 75–79, and over 80 years old, respectively. The most frequent comorbidities were chronic hypertension (62%), diabetes (30%), and chronic respiratory disease (25%). Median Clinical Frailty Scale was 3 (2–3). Upon admission, the PaO2/FiO2 ratio was 154 (105–222). 740 (62%) patients were intubated on Day-1 and eventually 938 (78%) during their ICU stay. Overall Day-90 mortality was 46% and reached 67% among the 193 patients over 80 years old. Mortality was higher in older patients, diabetics, and those with a lower PaO2/FiO2 ratio upon admission, cardiovascular dysfunction, and a shorter time between first symptoms and ICU admission. In propensity analysis, early intubation at ICU admission was associated with a significantly higher Day-90 mortality (42% vs 28%; hazard ratio 1.68; 95% CI 1.24–2.27; p &lt; 0·001). Conclusion: Patients over 70 years old represented more than a quarter of the COVID-19 population admitted in the participating ICUs during the first wave. Day-90 mortality was 46%, with dismal outcomes reported for patients older than 80 years or those intubated upon ICU admission