171 research outputs found
EDQNM closure: A homogeneous simulation to support it. A quasi-homogeneous simulation to disprove it
It is known that two-point closures are useful tools for understanding and predicting turbulence. Among the various closures, the Eddy Damped Quasi-Normal Markovian (EDQNM) approach is one of the simplest and, at the same time, most useful. Direct numerical simulations (DNS) can provide information that can be used to test the validity of two-point theories. It is the purpose of the present work to use DNS to validate, or improve upon, EDQNM. A case was selected for which EDQNM is known to give satisfactory results: homogeneous isotropic turbulence. Quantities were then evaluated which may be used to test the assumptions of two-point closure approximations: spectral Lagrangian time scales. The goal was to make a careful and refined study to validate the EDQNM theory. A reference case was built for which EDQNM is likely to give poor results. An attempt to generate a quasi-homogeneous turbulent field containing organized structures, was built by artifically injecting them in the initial conditions. The results of direct simulations using such initial conditions are expected to provide a challenge for EDQNM since this kind of field is simple enough to allow comparisons with two-point theories, but at the same time contains coherent structures which cannot be expected to be accurately accounted for by closures based on expansions about Gaussianity
High Curie temperature Mn 5 Ge 3 thin films produced by non-diffusive reaction
Polycrystalline Mn 5 Ge 3 thin films were produced on SiO 2 using magnetron
sputtering and reactive diffusion (RD) or non-diffusive reaction (NDR). In situ
X-ray diffraction and atomic force microscopy were used to determine the layer
structures, and magnetic force microscopy, superconducting quantum interference
device and ferromagnetic resonance were used to determine their magnetic
properties. RD-mediated layers exhibit similar magnetic properties as MBE-grown
monocrystalline Mn 5 Ge 3 thin films, while NDR-mediated layers show magnetic
properties similar to monocrystalline C-doped Mn 5 Ge 3 C x thin films with
NDR appears as a CMOS-compatible efficient method to
produce good magnetic quality high-curie temperature Mn 5 Ge 3 thin films
Te homogeneous precipitation in Ge dislocation loop vicinity
International audienceHigh resolution microscopies were used to study the interactions of Te atoms with Ge dislocation loops, after a standard n-type doping process in Ge. Te atoms neither segregate nor precipitate on dislocation loops, but form Te-Ge clusters at the same depth as dislocation loops, in contradiction with usual dopant behavior and thermodynamic expectations. Atomistic kinetic Monte Carlo simulations show that Te atoms are repulsed from dislocation loops due to elastic interactions, promoting homogeneous Te-Ge nucleation between dislocation loops. This phenomenon is enhanced by coulombic interactions between activated Te2Ăľ or Te1Ăľ ions
Inertial range scaling of the scalar flux spectrum in two-dimensional turbulence
Two-dimensional statistically stationary isotropic turbulence with an imposed
uniform scalar gradient is investigated. Dimensional arguments are presented to
predict the inertial range scaling of the turbulent scalar flux spectrum in
both the inverse cascade range and the enstrophy cascade range for small and
unity Schmidt numbers. The scaling predictions are checked by direct numerical
simulations and good agreement is observed
The new educational project Televascular Games during the Coronavirus Disease 2019 pandemic
Objective: To report methodology and first-year results of a new educational project called Televascular Games,” which took place during coronavirus disease 2019 pandemic. Methods: Complex aneurysmal aortic disease was discussed during a 2-hour competition webinar, according to three modalities. (1) Planning case competition (PCC): Two to four preoperative computed tomography angiography (CTA) scans of an already performed selected case were submitted for the competition. CTA scans were uploaded anonymously, without any reference to the center or the surgeon who performed the case. The competitor had to prepare a presentation of how he or she would have diagnosed, sized, planned, treated, and followed up the case, of the medical therapy and of the bail-out maneuvers. (2) Challenging case competition (CCC): The competitor elaborates a presentation of an already treated case concerning an aortic topic and discusses sizing, planning, treatment, possible bail-out maneuvers and obtained results. For the CCC and PCC, the competitors with the best score were preselected to present and discuss their plan during the webinars. (3) Quiz competition: Two to six CTA scans of already performed selected aortic cases were submitted for the competition. A quiz with multiple choice questions was answered by the competitors. The top four competitors were selected for the webinars and then they discussed the cases during the webinar. Finally, at the end of the case discussion, the effective case resolution and follow-up were shown. A final winner was voted via televoting, based on six preestablished criteria. The project was endorsed by different national and international societies. Results: Between October 2020 and December 2021, there were 12 Italian and 1 international webinars with 1695 participants overall (mean, 130; range, 86-177). Competitors were 54 years of age (mean, 27 years; range, 22-38 years). Two editions were CCCs, two quiz competitions, and nine PCCs. The reliability of the interobserver sizing of competitors was κ = 0.43 and κ = 0.62 for the proximal and distal sealing measurements respectively and very good (κ = 0.88-0.95) in the evaluation of orientation of the vessels, presence of angulations, calcifications, and thrombus. The sizing discrepancy resulted in a significant variability of the planning (κ = 0.45). The project ranked 9.6 on a 10-point rating scale by all the participants and competitors. Conclusions: The formula of gaming and collegial discussion of aortic cases herein reported has proved valid and attractive during coronavirus disease 2019 pandemic period. The variability of the results on sizing and planning suggested to confer with a second opinion, especially for less experienced surgeons
Gathering patients and rheumatologists' perceptions to improve outcomes in idiopathic inflammatory myopathies
Objective: Therapeutic targets in Idiopathic Inflammatory Myopathies (IIM) are based on the opinions of physicians/specialists, which may not reflect the main concerns of patients. The authors, therefore, assessed the outcome concerns of patients with IIM and compared them with the concerns of rheumatologists in order to develop an IIM outcome standard set.
Methods: Ninety-three IIM patients, 51 rheumatologists, and one physiotherapist were invited to participate. An open questionnaire was initially applied. The top 10 answers were selected and applied in a multiple-choice questionnaire, inquiring about the top 3 major concerns. Answers were compared, and the agreement rate was calculated. Concerns were gathered in an IIM outcome standard set with validated measures.
Results: The top three outcome concerns raised by patients were medication side effects/muscle weakness/prevention functionality loss. The top three concerns among rheumatologists were to prevent loss of functionality/to ensure the quality of life/to achieve disease remission. Other's outcomes concerns only pointed out by patients were muscle pain/diffuse pain/skin lesions/fatigue. The agreement rate between both groups was 41%. Assessment of these parameters guided the development of an IIM standard set which included Myositis Disease Activity Assessment Visual Analogue Scale/Manual Muscle Testing/fatigue and pain Global Visual Analogue Scale/Health Assessment Questionnaire/level of physical activity.
Conclusion: The authors propose a novel standard set to be pursued in IIM routine follow-up, which includes not only the main patients/rheumatologist outcome concerns but also additional important outcomes only indicated by patients. Future studies are necessary to confirm if this comprehensive approach will result in improved adherence and ultimately in better assistance
Peri-Operative Management of Patients Undergoing Fenestrated-Branched Endovascular Repair for Juxtarenal, Pararenal and Thoracoabdominal Aortic Aneurysms: Preventing, Recognizing and Treating Complications to Improve Clinical Outcomes
The advent and refinement of complex endovascular techniques in the last two decades has revolutionized the field of vascular surgery. This has allowed an effective minimally invasive treatment of extensive disease involving the pararenal and the thoracoabdominal aorta. Fenestrated-branched EVAR (F/BEVAR) now represents a feasible technical solution to address these complex diseases, moving the proximal sealing zone above the renal-visceral vessels take-off and preserving their patency. The aim of this paper was to provide a narrative review on the peri-operative management of patients undergoing F/BEVAR procedures for juxtarenal abdominal aortic aneurysm (JAAA), pararenal abdominal aortic aneurysm (PRAA) or thoracoabdominal aortic aneurism (TAAA). It will focus on how to prevent, diagnose, and manage the complications ensuing from these complex interventions, in order to improve clinical outcomes. Indeed, F/BEVAR remains a technically, physiologically, and mentally demanding procedure. Intraoperative adverse events often require prolonged or additional procedures and complications may significantly impact a patient’s quality of life, health status, and overall cost of care. The presence of standardized preoperative, perioperative, and postoperative pathways of care, together with surgeons and teams with significant experience in aortic surgery, should be considered as crucial points to improve clinical outcomes. Aggressive prevention, prompt diagnosis and timely rescue of any major adverse events following the procedure remain paramount clinical needs
COVID-19 vaccine-readiness for anti-CD20-depleting therapy in autoimmune diseases
Although most autoimmune diseases are considered to be CD4 T cell- or antibody-mediated, many respond to CD20-depleting antibodies that have limited influence on CD4 and plasma cells. This includes rituximab, oblinutuzumab and ofatumumab that are used in cancer, rheumatoid arthritis and off-label in a large number of other autoimmunities and ocrelizumab in multiple sclerosis. Recently, the COVID-19 pandemic created concerns about immunosuppression in autoimmunity, leading to cessation or a delay in immunotherapy treatments. However, based on the known and emerging biology of autoimmunity and COVID-19, it was hypothesised that while B cell depletion should not necessarily expose people to severe SARS-CoV-2-related issues, it may inhibit protective immunity following infection and vaccination. As such, drug-induced B cell subset inhibition, that controls at least some autoimmunities, would not influence innate and CD8 T cell responses, which are central to SARS-CoV-2 elimination, nor the hypercoagulation and innate inflammation causing severe morbidity. This is supported clinically, as the majority of SARS-CoV-2-infected, CD20-depleted people with autoimmunity have recovered. However, protective neutralizing antibody and vaccination responses are predicted to be blunted until naive B cells repopulate, based on B cell repopulation kinetics and vaccination responses, from published rituximab and unpublished ocrelizumab (NCT00676715, NCT02545868) trial data, shown here. This suggests that it may be possible to undertake dose interruption to maintain inflammatory disease control, while allowing effective vaccination against SARS-CoV-29, if and when an effective vaccine is available
Fenestrated and Branched Endografts for Post-Dissection Thoraco-Abdominal Aneurysms: Results of a National Multicentre Study and Literature Review
Objective: Fenestrated and branched endografting (F/B-EVAR) has been proposed as an endovascular solution for chronic post-dissection thoraco-abdominal aneurysms (PD-TAAAs). The aim of this study was to analyse the experience of four high volume centres nationwide and the current available literature. Methods: Data on patients undergoing F/B-EVAR in four Italian academic centres between 2008 and 2019 were collected, and those from patients with PD-TAAAs were analysed retrospectively. Peri-operative morbidity and mortality were assessed as early outcomes. Survival, freedom from re-intervention (FFR), target visceral vessel (TVV) patency, and aortic remodelling were assessed as follow up outcomes. A MEDLINE search was performed for studies published from 2008 to 2020 reporting on F/B-EVAR in PD-TAAAs. Results: Among 351 patients who underwent F/B-EVAR for TAAAs, 37 (11%) had PD-TAAAs (Crawford's extent I–III: 35% – 95%). Overall, 135 TVVs (from true lumen 120; false lumen seven; both true and false lumen eight) were accommodated by fenestrations (96% – 71%) and branches (39% – 29%). Technical success (TS) was achieved in 34 (92%) cases with three failures due to endoleaks (Ia: 1; Ic: 1; III: 1). There were no 30 day deaths. No cases of permanent spinal cord ischaemia (SCI) were recorded and six (16%) patients suffered from transient deficits. Renal function worsening (eGFR < 30% than baseline) and pulmonary complications were reported in two (5%) and four (11%) cases, respectively. From the Kaplan–Meier analysis, three year survival, FFR, and TVV patency were 81%, 66%, and 97%, respectively. Radiological imaging was available for 30 (81%) patients at 12 months with complete false lumen thrombosis in 26 (87%). Two hundred and fifty-six patients were reported in seven published papers with TS, 30 day mortality, and SCI ranging from 99% to 100%, 0 to 6%, and 0 to 16%, respectively. The mean follow up ranged from 12 to 26 months, with estimated two year survival between 81% and 90% and a re-intervention rate between 19% and 53%. Conclusion: F/B-EVAR is effective to treat PD-TAAAs. A high re-intervention rate is necessary to complete the aneurysm exclusion and promote aortic remodelling successfully
Outcomes of “Anterior Versus Posterior Divisional Branches of the Hypogastric Artery as Distal Landing Zone for Iliac Branch Devices”: The International Multicentric R3OYAL Registry
Objective: The aim of this multicentric registry was to assess the outcomes of “anteRior versus posteRior divisional bRanches Of the hYpogastric artery as distAl landing zone for iLiac branch devices (R3OYAL).” Methods: The main exposure of interest for the purpose of this study was the internal iliac artery (IIA) divisional branch (anterior vs posterior) that was used as distal landing zone. Early endpoints included technical success and adverse events. Late endpoints included survival, primary/secondary IIA patency, and IIA branch instability. Results: A total of 171 patients were included in the study, of which 50 received bilateral implantation of iliac branch devices (IBDs). This resulted in a total of 221 incorporated IIAs included in the final analysis, of which 40 were anterior divisional branches and 181 were posterior divisional branches. Technical success was high in both groups (anterior division: 98% vs posterior division: 100%, P =.18). Occurrence of any adverse event was noted in 14% of patients in both groups (P = 1.0). The overall rate of freedom from the composite IBD branch instability did not show significant differences between patients receiving distal landing in the anterior or posterior division of the IIA at 3 years (79% vs 87%, log-rank test =.215). The 3-year estimates of IBD patency were significantly lower in patients who received distal landing in the anterior divisional branch than those who received distal landing in the posterior divisional branch (primary patency: 81% vs 96%, log-rank test =.009; secondary patency: 81% vs 97%, log-rank test <.001). Conclusions: The use of the anterior or posterior divisional branches of the IIA as distal landing zone for IBD implantation shows comparable profiles in terms of immediate technical success, perioperative safety, and side-branch instability up to 3 years. However, IBD patency at 3 years was higher when the distal landing zone was achieved within the posterior divisional branch of the IIA. Clinical Impact: The results from this large multicentric registry confirm that use of the anterior or posterior divisional branches of the internal iliac artery (IIA) as distal landing zone for implantation of iliac branch devices (IBD) shows comparable profiles of safety and feasibility, thereby allowing to extend the indications for endovascular repair of aorto-iliac aneurysms to cases with unsuitable anatomy within the IIA main trunk. Although mid-term rates of device durability and branch instability seem to be similar, the rates of primary and secondary IBD patency at three years was favored when the distal landing zone was achieved in the posterior divisional branch of the IIA
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