Essais de colonnes en BLC sous feux naturels incluant la phase de refroidissement

peer reviewedThis paper presents the data and the results of seven fire tests performed on glue laminated timber columns in a compartment built especially for the tests and in which timber wood cribs created a so-called natural fire. These tests are part of a research programme titled “burnout resistance” to establish a new methodology to better describe performance of structural elements during the whole duration of a fire. Comparisons with similar tests made in a fire resistance furnace allow comparing charring rates observed in standard conditions and in natural fires

Dissecting the Shared Genetic Architecture of Suicide Attempt, Psychiatric Disorders, and Known Risk Factors

Background Suicide is a leading cause of death worldwide, and nonfatal suicide attempts, which occur far more frequently, are a major source of disability and social and economic burden. Both have substantial genetic etiology, which is partially shared and partially distinct from that of related psychiatric disorders. Methods We conducted a genome-wide association study (GWAS) of 29,782 suicide attempt (SA) cases and 519,961 controls in the International Suicide Genetics Consortium (ISGC). The GWAS of SA was conditioned on psychiatric disorders using GWAS summary statistics via multitrait-based conditional and joint analysis, to remove genetic effects on SA mediated by psychiatric disorders. We investigated the shared and divergent genetic architectures of SA, psychiatric disorders, and other known risk factors. Results Two loci reached genome-wide significance for SA: the major histocompatibility complex and an intergenic locus on chromosome 7, the latter of which remained associated with SA after conditioning on psychiatric disorders and replicated in an independent cohort from the Million Veteran Program. This locus has been implicated in risk-taking behavior, smoking, and insomnia. SA showed strong genetic correlation with psychiatric disorders, particularly major depression, and also with smoking, pain, risk-taking behavior, sleep disturbances, lower educational attainment, reproductive traits, lower socioeconomic status, and poorer general health. After conditioning on psychiatric disorders, the genetic correlations between SA and psychiatric disorders decreased, whereas those with nonpsychiatric traits remained largely unchanged. Conclusions Our results identify a risk locus that contributes more strongly to SA than other phenotypes and suggest a shared underlying biology between SA and known risk factors that is not mediated by psychiatric disorders.Peer reviewe

Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19

IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19. Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19. DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 non–critically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022). INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (n = 257), ARB (n = 248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; n = 10), or no RAS inhibitor (control; n = 264) for up to 10 days. MAIN OUTCOMES AND MEASURES The primary outcome was organ support–free days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes. RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ support–free days among critically ill patients was 10 (–1 to 16) in the ACE inhibitor group (n = 231), 8 (–1 to 17) in the ARB group (n = 217), and 12 (0 to 17) in the control group (n = 231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ support–free days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively). CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570

Fire dynamics in compartments with struktural fire load

Die Muster-Holzbaurichtlinie ermöglicht die teilweise ungeschützte Ausbildung von Massivholzbauteilen, die - im Vergleich zu nichtbrennbaren oder geschützten Bauteilen - als strukturelle Brandlast eine, zusätzliche Brandlast darstellt. In der vorliegenden Arbeit wird untersucht, in welchem Maß die Branddynamik in Räumen aufgrund des Beitrags der strukturellen Brandlast beeinflusst wird. Des Weiteren werden Ansätze zur Abbildung der zusätzlichen Brandleistung aus der strukturellen Brandlast in vereinfachten und allgemeinen Brandmodellen erarbeitet. Einführend erfolgt eine detaillierte Beschreibung des Brandverhaltens von Holz sowie veröffentlichte Ansätze zur Abbildung der strukturellen Brandlast in vereinfachten und allgemeinen Brandmodellen aus der Literatur. Diese bilden die Grundlage für die folgenden experimentellen und numerischen Untersuchungen im Rahmen dieser Arbeit. Eine umfangreiche Erörterung der Branddynamik im Raum ohne und mit Berücksichtigung des Beitrags der strukturellen Brandlast zeigt eine teilweise signifikante Beeinflussung dieser. Eine Auswertung von Versuchsdaten aus der Literatur sowie von eigenen Raumbrandversuchen bestätigt die Beeinflussung in Abhängigkeit verschiedener Parameter, wie z. B. den Ventilationsbedingungen, der Fläche der strukturellen Brandlast oder der Brandlastdichte. Die Beeinflussung spiegelt sich deutlich in der Wärmefreisetzungsrate respektive der Brandraumtemperatur, dem Flashoverzeitpunkt, der Branddauer sowie dem vermehrt ventilationsgesteuerten Brandregime wider. Zur Abbildung des Beitrags der strukturellen Brandlast in einem allgemeinen Brandmodell erfolgt die Erarbeitung drei unterschiedlicher Modellierungsansätze. Durch eine Validierung der Modellierungsansätze an Brandversuchen im Mittleren- und Großmaßstab kann eine hinreichend genaue Übereinstimmung gezeigt werden. Mit der Auswertung der Validierungsberechnungen konnten Anwendungsgrenzen der erarbeiteten Modellierungsansätze identifiziert werden. Die Erweiterung eines vereinfachten Brandmodells nach DIN EN 1991-1-2/NA - Anhang AA hinsichtlich der Berücksichtigung der strukturellen Brandlast wird auf Basis der experimentellen und numerischen Erkenntnisse durchgeführt. Mittels experimenteller Ergebnisse aus verschiedenen Raumbrandversuchen mit struktureller Brandlast erfolgt eine Validierung des erweiterten vereinfachten Brandmodells. Die Ergebnisse einer durchgeführten Parameterstudie sowie der Modellvalidierung werden zur Ermittlung von Anwendungsgrenzen herangezogen.The model timber building guideline allows the partially exposed design of mass timber components, which, as a structural fire load, represents an additional fire load compared to non-combustible or protected components. In the present work, the extent to which the enclosure fire dynamics are affected due to the contribution of the structural fire load is investigated. Furthermore, approaches to represent the additional fire load from the exposed timber components in simplified and general fire models are developed. Introductory to this work is a detailed description of the reaction to fire of wood as well as published approaches to model the additional structural fire load in simplified and general fire models from the literature. These form the basis for the following experimental and numerical investigations within the scope of this work. An extensive discussion of the enclosure fire dynamics without and with consideration of the contribution of the structural fire load shows a partially significant influence of this. An evaluation of test data from the literature as well as from own room fire tests confirms the influence depending on various parameters, such as the ventilation conditions, the area of the structural fire load or the fire load density. The influence is clearly reflected in the heat release rate or the gase temperature inside the compartment, the flashover time, the total fire duration and the increasingly ventilation-controlled fire regime. Three different modeling approaches are developed to represent the contribution of structural fire load in a general fire model. By validating the modeling approaches in medium and large scale fire tests, a sufficient agreement can be shown. With the evaluation of the validation calculations, application limits of the developed modeling approaches could be identified. The extension of a simplified fire model according to DIN EN 1991-1-2/NA - annex AA with regard to the consideration of the structural fire load is carried out on the basis of the experimental and numerical findings. By means of experimental results from different compartment fire tests with structural fire load, a validation of the extended simplified fire model is performed. The results of a performed parameter study as well as the model validation are used to determine application limits

Recherches expérimentales concernant la ruine structurelle durant la phase de refroidissement d'un incendie: colonnes en bois

peer reviewedThis paper describes fire tests on loaded glued laminated timber columns in which the structural response was measured during the heating and cooling phases. Identical columns with 280 280 mm2 cross-section and 3.7 m length were tested under various heating durations in a standard furnace to investigate integrity to full burnout. Two of the columns were subjected to ISO 834 heating until failure and their measured fire resistance was 55 and 58 min, respectively. Two columns were subjected to 15 min of ISO 834 heating followed by controlled cooling; these columns failed during the cooling phase, respectively after 98 and 153 min. Flame selfextinction occurred after approximately 40 min while smoldering continued locally. Two columns tested under 10 min of ISO 834 heating both survived the defined heating–cooling exposure. Thermocouples inside the columns show sustained temperature increases for hours after the end of the heating phase. These full-scale furnace experiments show that timber columns may fail during the cooling phase after exposure to standard heating for about 25% of the standard fire resistance duration. These results, in line with previous numerical predictions, highlight the need for further investigation into fire safety until full burnout for timber structures.BURNOU

Experimental investigation of structural failure during the cooling phase of a fire : Concrete columns

Structures may collapse during the cooling phase of a fire, yet standard furnace tests only measure the response under heating. There lacks experimental test protocols and design methods to assess resistance until burnout. This paper describes a new experimental approach for burnout resistance evaluation, reports experimental data on loaded reinforced concrete columns in furnace tests with cooling down phases, and presents numerical models of the tests. The test results show that columns designed for a standard fire resistance of 60 min exhibited a fire resistance of 83 min in the furnace but failed during the cooling phase when the burners were shut off after 72 min while the load was maintained. Two other specimens survived exposure to heating of 45 and 55 min, respectively, and their residual capacity was measured. Finite element analyses show agreement with the tests, showing applicability of numerical methods for evaluating burnout resistance of concrete columns. These findings demonstrate experimentally that delayed thermal-mechanical effects can jeopardize structural stability in real fires, and provide a framework to measure these effects. Moving beyond fire resistance to quantify the response until burnout will support designs for safety of occupants and firefighters throughout the fire and promote repairability and resilience

Additional file 2: of The impairment of small nerve fibers in severe sepsis and septic shock

Nerve conduction studies. Amplitudes of compound potentials in motor and sensory nerves are considerably decreased, and conduction velocity is marginally impaired. Note that nerve conduction studies detect critical illness polyneuropathy early in the course of sepsis, but amplitudes do not change considerably over the course of the disease. Horizontal lines show the normative values of the measurements. (PDF 340 kb