Investigating episodic mass loss in evolved massive stars: II. Physical properties of red supergiants at subsolar metallicity

Mass loss during the red supergiant (RSG) phase plays a crucial role in the evolution of an intermediate massive star, however, the underlying mechanism remains unknown. We aim to increase the sample of well-characterized RSGs at subsolar metallicity, by deriving the physical properties of 127 RSGs in nine nearby, southern galaxies presented by Bonanos et al. For each RSG, we provide spectral types and used \textsc{marcs} atmospheric models to measure stellar properties from their optical spectra, such as the effective temperature, extinction, and radial velocity. By fitting the spectral energy distribution, we obtained the stellar luminosity and radius for 97 RSGs, finding $\sim 50\%$ with log$(L/ \rm L_{\odot}) \geq 5.0$ and 6 RSGs with $R \gtrsim 1400 \,\ \rm R_{\odot}$. We also find a correlation between the stellar luminosity and mid-IR excess of 33 dusty, variable sources. Three of these dusty RSGs have luminosities exceeding the revised Humphreys-Davidson limit. We then derive a metallicity-dependent $J-K_s$ color versus temperature relation from synthetic photometry and two new empirical $J-K_s$ color versus temperature relations calibrated on literature TiO and $J$-band temperatures. To scale our derived, cool TiO temperatures to values in agreement with the evolutionary tracks, we derive two linear scaling relations calibrated on $J$-band and $i$-band temperatures. We find that the TiO temperatures are more discrepant as a function of the mass-loss rate and discuss future prospects of the TiO bands as a mass-loss probe. Finally, we speculate that 3 hot, dusty RSGs may have experienced a recent mass ejection ($12\%$ of the K-type sample) and indicate them as candidate Levesque-Massey variables.Comment: 22 pages, 18 figures, submitted to A&

Hydromechanical reactivation of natural discontinuities: mesoscale experimental observations and DEM modeling

Fracture interaction mechanisms and reactivation of natural discontinuities under fluid pressurization conditions can represent critical issues in risk assessment of caprock integrity. A field injection test, carried out in a damage fault zone at the decameter scale, i.e., mesoscale, has been studied using a distinct element model. Given the complex structural nature of the damage fault zone hydraulically loaded, the contribution of fracture sets on the bulk permeability has been investigated. It has been shown that their orientation for a given in situ stress field plays a major role. Based on these results, a simpler model with a fluid-driven fracture intersecting a second fracture has been set up to perform a sensitivity analysis. It is in presence of a minimum differential stress value with a minimum angle with the maximum principal stress that the second fracture could be both, hydraulically and mechanically reactivated. Results also showed that in the vicinity of the fluid-driven fracture, a natural fracture will offer contrasted hydromechanical responses on each side of the intersection depending on the stress conditions and its orientation with respect to the stress field. In this case, we show that a hydromechanical decoupling can occur along the same plane. These results provide insights into fracture-controlled permeability of fault zones depending on the properties of the fractures and their hydromechanical interactions for a given in situ stress field

Hydromechanical reactivation of natural discontinuities: mesoscale experimental observations and DEM modeling

Fracture interaction mechanisms and reactivation of natural discontinuities under fluid pressurization conditions can represent critical issues in risk assessment of caprock integrity. A field injection test, carried out in a damage fault zone at the decameter scale, i.e., mesoscale, has been studied using a distinct element model. Given the complex structural nature of the damage fault zone hydraulically loaded, the contribution of fracture sets on the bulk permeability has been investigated. It has been shown that their orientation for a given in situ stress field plays a major role. Based on these results, a simpler model with a fluid-driven fracture intersecting a second fracture has been set up to perform a sensitivity analysis. It is in presence of a minimum differential stress value with a minimum angle with the maximum principal stress that the second fracture could be both, hydraulically and mechanically reactivated. Results also showed that in the vicinity of the fluid-driven fracture, a natural fracture will offer contrasted hydromechanical responses on each side of the intersection depending on the stress conditions and its orientation with respect to the stress field. In this case, we show that a hydromechanical decoupling can occur along the same plane. These results provide insights into fracture-controlled permeability of fault zones depending on the properties of the fractures and their hydromechanical interactions for a given in situ stress field

Dengue Virus Replication Is Associated with Catecholamine Biosynthesis and Metabolism in Hepatocytes

Previously, the association between the catecholamine biosynthetic enzyme L-Dopa decarboxylase (DDC) and Dengue virus (DV) replication was demonstrated in liver cells and was found to be mediated at least by the interaction between DDC and phosphoinositide 3-kinase (PI3K). Here, we show that biogenic amines production and uptake impede DV replication in hepatocytes and monocytes, while the virus reduces catecholamine biosynthesis, metabolism, and transport. To examine how catecholamine biosynthesis/metabolism influences DV, first, we verified the role of DDC by altering DDC expression. DDC silencing enhanced virus replication, but not translation, attenuated the negative effect of DDC substrates on the virus and reduced the infection related cell death. Then, the role of the downstream steps of the catecholamine biosynthesis/metabolism was analyzed by chemical inhibition of the respective enzymes, application of their substrates and/or their products; moreover, reserpine, the inhibitor of the vesicular monoamine transporter 2 (VMAT2), was used to examine the role of uptake/storage of catecholamines on DV. Apart from the role of each enzyme/transporter, these studies revealed that the dopamine uptake, and not the dopamine-signaling, is responsible for the negative effect on DV. Accordingly, all treatments expected to enhance the accumulation of catecholamines in the cell cytosol suppressed DV replication. This was verified by the use of chemical inducers of catecholamine biosynthesis. Last, the cellular redox alterations due to catecholamine oxidation were not related with the inhibition of DV replication. In turn, DV apart from its negative impact on DDC, inhibits tyrosine hydroxylase, dopamine beta-hydroxylase, monoamine oxidase, and VMAT2 expression. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

Strain and Flow Pathways in a Shale Fault Zone: An In-Situ Test of Fault Seal Integrity

International audienceA series of small scale (decametric) injection tests were performed in a small fault at IRSN Tournemire underground laboratory in Toarcian shales. Pressure, induced strains and flow rate were monitored at the injection borehole. Monitoring systems comprising strain sensors and a resistivity streamer were installed in observation boreholes within the fluid invaded zone. A micro-seismic network was also deployed. This experiment shows complex interactions between flow and strain as both appear to be distributed between major discontinuities and the fracture network in the damage and core zones. Permeability variations can be approximated as exponential functions of fluid pressure, with different coefficients below and above a threshold, defining the Fracture Opening Pressure. Hydraulic opening is typically associated with dilatant shearing of fractures. However, the associated strain appears small and largely reversible. Rupture on the main fault plane is triggered after several hours of injection, resulting in a permanent change of flow pathways and flow rate. Numerical modeling based on these experimental results suggest fluid channeling along a fault zone could occur in the subcritical Coulomb regime without fault activation at the larger scale

Perioperative antimicrobial prophylaxis in adult patients: The first multicenter clinical practice audit with intervention in Greek surgical departments

Objective: To audit clinical practice and implement an intervention to promote appropriate use of perioperative antimicrobial prophylaxis (PAP). Design: Prospective multicenter before-And-After study. Setting: This study was conducted in 7 surgical departments of 3 major Greek hospitals. Methods: Active PAP surveillance in adults undergoing elective surgical procedures was performed before and after implementation of a multimodal intervention. The surveillance monitored use of appropriate antimicrobial agent according to international and local guidelines, appropriate timing and duration of PAP, overall compliance with all 3 parameters and the occurrence of surgical site infections (SSIs). The intervention included education, audit, and feedback. Results: Overall, 1,447 patients were included: 768 before and 679 after intervention. Overall compliance increased from 28.2% to 43.9% (P =.001). Use of antimicrobial agents compliant to international guidelines increased from 89.6% to 96.3% (P =.001). In 4 of 7 departments, compliance with appropriate timing was already >90%; an increase from 44.3% to 73% (P =.001) and from 20.4% to 60% (P =.001), respectively, was achieved in 2 other departments, whereas a decrease from 64.1% to 10.9% (P =.001) was observed in 1 department. All but one department achieved a shorter PAP duration, and most achieved duration of ~2 days. SSIs significantly decreased from 6.9% to 4% (P =.026). After the intervention, it was 2.3 times more likely for appropriate antimicrobial use, 14.7 times more likely to administer an antimicrobial for the appropriate duration and 5.3 times more likely to administer an overall appropriate PAP. Conclusion: An intervention based on education, audit, and feedback can significantly contribute to improvement of appropriate PAP administration; further improvement in duration is needed. © 2021 Infection Control and Hospital Epidemiology. All rights reserved

A national study of antibiotic use in Greek pediatric hematology oncology and bone marrow transplant units

Objective: We surveyed antimicrobials used in Greek pediatric hematology-oncology (PHO) and bone marrow transplant (BMT) units before and after an intervention involving education regarding the 2017 clinical practice guidelines (CPG) for the management of febrile neutropenia in children with cancer and hematopoietic stem-cell transplant recipients. Design: Antibiotic prescribing practices were prospectively recorded between June 2016 and November 2017. Intervention: In December 2017, baseline data feedback was provided, and CPG education was provided. Prescribing practices were followed for one more year. For antibiotic stewardship, days of therapy, and length of therapy were calculated. Setting: Five of the 6 PHO units in Greece and the single pediatric BMT unit participated. Participants: Admitted children in each unit who received the first 15 new antibiotic courses each month. Results: Administration of ≥4 antibiotics simultaneously and administration of antibiotics with overlapping activity for ≥2 days were significantly more common in PHO units in general hospitals compared to children's hospitals. Use of at least 1 antifungal was recorded in ∼47% of the patients before and after the intervention. De-escalation and/or discontinuation of antibiotics on day 6 of initial treatment increased significantly from 43% to 53.5% (P =.032). Although the number of patients requiring intensive care support for sepsis did not change, a significant drop was noted in all-cause mortality (P =.008). Conclusions: We recorded the antibiotic prescribing practices in Greek PHO and BMT units, we achieved improved prescribing with a simple intervention, and we identified areas in need of improvement. © The Author(s), 2022

Central line-associated bloodstream infections in pediatric patients: Results from a national nosocomial infections surveillance program

ΟBJECTIVE To provide updated data on the rates of central line-associated bloodstream infections (CLABSI) in Greek neonatal intensive care units (NICUs), pediatric intensive care units (PICUs) and pediatric oncology units (PONCs), and to describe pathogen distribution and antimicrobial resistance patterns for CLABSIs. METHOD Active surveillance for CLABSI was conducted from June 2016 to December 2019 (43 months). A consortium of 14 NICUs, 3 PICUs, and 6 PONCs participated in the program. Surveillance definitions of central line (CL), central line utilization (CLU) ratio, CLABSI event, and CLABSI rate were based on the 2014 National Healthcare Safety Network criteria of the US Centers for Disease Control and Prevention (CDC). Medical records were assessed daily for calculation of CL-days, pa-tient-days, and susceptibility to isolated organisms. RESULTS A total of 519 CLABSI episodes were recorded in the 43 months. Mean CLABSI rates were 7.15 in NICUs, 5.19 in PICUs, and 2.20, per 1,000 CL-days in PONCs. A higher mean CLU ratio was reported in PONCs (0.83) and a lower mean ratio was found in NICUs (0.15). A total of 567 pathogens were isolated, the most common of which were Enterobacterales (42.1%), followed by Gram-positive cocci (29%), non-fermenting Gram-negative bacteria (14.6%), and fungi (11.5%). Among 239 (63.1%) Enterobacterales isolated, 151 were multidrug resistant. Overall, 14.8% of Gram-negative pathogens were resistant to third generation ceph-alosporins and 23.7% to carbapenems. CONCLUSIONS The rates of CLABSI and antibiotic resistance among organ-isms causing CLABSI are high in high-risk hospitalized children. These data highlight the significance of this problem and emphasize the need for implementation of infection prevention interventions. The methodology used for this surveillance program could be applied in other pediatric or adult units across Greece. © Athens Medical Society

Reducing duration of antibiotic use for presumed neonatal early-onset sepsis in greek nicus. A “low-hanging fruit” approach

Antibiotics are commonly prescribed in Neonatal Intensive Care Units (NICU), where stewardship interventions are challenging. Lowering antibiotic consumption is desperately needed in Greece, a country with high antibiotic resistance rates. We sought to assess the effectiveness of a low-cost and-resource intervention to reduce antibiotic use in Greek NICUs implementing a “low-hanging fruit” approach. A prospective quasi-experimental study was conducted in 15/17 public NICUs in Greece (9/2016–06/2019). The intervention selected was discontinuation of antibiotics within 5 days for neonates with gestational age ≥ 37 weeks, no documented signs or symptoms of sepsis, CRP ≤ 10 mg/L and negative cultures within 3 days of antibiotic initiation. Impact was evaluated by the percentage of discontinued regimens by day 5, length of therapy (LOT) and stay. Trends of antibiotic consumption were assessed with days of therapy (DOT) per 1000 patient-days. Overall, there was a 9% increase (p = 0.003) of antibiotic discontinuation in ≤5 days. In total, 7/13 (53.8%) units showed a ≥10% increase. Overall, 615 days on antibiotics per 1000 patients were saved. Interrupted time-series analysis established a declining trend in DOT/1000 patient-days relative to the pre-intervention trend (p = 0.002); a monthly decrease rate of 28.96 DOT/1000 patient-days (p = 0.001, 95%CI [−45.33, −12.60]). The intervention had no impact on antibiotic choice. Antibiotic use was successfully reduced in Greek NICUs using a “low-hanging fruit” approach. In resource-limited settings, similar targeted stewardship interventions can be applied. © 2021 by the authors. Licensee MDPI, Basel, Switzerland