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Sökning: WFRF:(Vlad A.) > (2020-2024)

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  • Murari, A., et al. (författare)
  • A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
  • 2024
  • Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
  • Tidskriftsartikel (refereegranskat)abstract
    • The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
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  • Pucella, G., et al. (författare)
  • Overview of the FTU results
  • 2022
  • Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 62:4
  • Forskningsöversikt (refereegranskat)abstract
    • Since the 2018 IAEA FEC Conference, FTU operations have been devoted to several experiments covering a large range of topics, from the investigation of the behaviour of a liquid tin limiter to the runaway electrons mitigation and control and to the stabilization of tearing modes by electron cyclotron heating and by pellet injection. Other experiments have involved the spectroscopy of heavy metal ions, the electron density peaking in helium doped plasmas, the electron cyclotron assisted start-up and the electron temperature measurements in high temperature plasmas. The effectiveness of the laser induced breakdown spectroscopy system has been demonstrated and the new capabilities of the runaway electron imaging spectrometry system for in-flight runaways studies have been explored. Finally, a high resolution saddle coil array for MHD analysis and UV and SXR diamond detectors have been successfully tested on different plasma scenarios.
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  • Belay, Mulugeta, et al. (författare)
  • Detection of Mycobacterium tuberculosis complex DNA in CD34-positive peripheral blood mononuclear cells of asymptomatic tuberculosis contacts : an observational study
  • 2021
  • Ingår i: The Lancet Microbe. - 2666-5247. ; 2:6, s. 267-275
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: Haematopoietic stem cells expressing the CD34 surface marker have been posited as a niche for Mycobacterium tuberculosis complex bacilli during latent tuberculosis infection. Our aim was to determine whether M tuberculosis complex DNA is detectable in CD34-positive peripheral blood mononuclear cells (PBMCs) isolated from asymptomatic adults living in a setting with a high tuberculosis burden. Methods: We did a cross-sectional study in Ethiopia between Nov 22, 2017, and Jan 10, 2019. Digital PCR (dPCR) was used to determine whether M tuberculosis complex DNA was detectable in PBMCs isolated from 100 mL blood taken from asymptomatic adults with HIV infection or a history of recent household or occupational exposure to an index case of human or bovine tuberculosis. Participants were recruited from HIV clinics, tuberculosis clinics, and cattle farms in and around Addis Ababa. A nested prospective study was done in a subset of HIV-infected individuals to evaluate whether administration of isoniazid preventive therapy was effective in clearing M tuberculosis complex DNA from PBMCs. Follow-up was done between July 20, 2018, and Feb 13, 2019. QuantiFERON-TB Gold assays were also done on all baseline and follow-up samples. Findings: Valid dPCR data (ie, droplet counts >10 000 per well) were available for paired CD34-positive and CD34-negative PBMC fractions from 197 (70%) of 284 participants who contributed data to cross-sectional analyses. M tuberculosis complex DNA was detected in PBMCs of 156 of 197 participants with valid dPCR data (79%, 95% CI 74–85). It was more commonly present in CD34-positive than in CD34-negative fractions (154 [73%] of 197 vs 46 [23%] of 197; p<0·0001). Prevalence of dPCR-detected M tuberculosis complex DNA did not differ between QuantiFERON-negative and QuantiFERON-positive participants (77 [78%] of 99 vs 79 [81%] of 98; p=0·73), but it was higher in HIV-infected than in HIV-uninfected participants (67 [89%] of 75 vs 89 [73%] of 122, p=0·0065). By contrast, the proportion of QuantiFERON-positive participants was lower in HIV-infected than in HIV-uninfected participants (25 [33%] of 75 vs 73 [60%] of 122; p<0·0001). Administration of isoniazid preventive therapy reduced the prevalence of dPCR-detected M tuberculosis complex DNA from 41 (95%) of 43 HIV-infected individuals at baseline to 23 (53%) of 43 after treatment (p<0·0001), but it did not affect the prevalence of QuantiFERON positivity (17 [40%] of 43 at baseline vs 13 [30%] of 43 after treatment; p=0·13). Interpretation: We report a novel molecular microbiological biomarker of latent tuberculosis infection with properties that are distinct from those of a commercial interferon-γ release assay. Our findings implicate the bone marrow as a niche for M tuberculosis in latently infected individuals. Detection of M tuberculosis complex DNA in PBMCs has potential applications in the diagnosis of latent tuberculosis infection, in monitoring response to preventive therapy, and as an outcome measure in clinical trials of interventions to prevent or treat latent tuberculosis infection. Funding: UK Medical Research Council.
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  • Mariani, A., et al. (författare)
  • First-principle based predictions of the effects of negative triangularity on DTT scenarios
  • 2024
  • Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 64:4
  • Tidskriftsartikel (refereegranskat)abstract
    • Plasmas with negative triangularity (NT) shape have been recently shown to be able to achieve H-mode levels of confinement in L-mode, avoiding detrimental edge localised modes. Therefore, this plasma geometry is now studied as a possible viable option for a future fusion reactor. Within this framework, an NT option is under investigation for the full power scenario of the Divertor Tokamak Test (DTT) facility, under construction in Italy, with δ t o p = − 0.32 / δ b o t t o m ≃ 0.02 top/bottom triangularity values at the separatrix. The transport properties of this scenario are studied in this work. Gyrokinetic GENE simulations and integrated modelling using ASTRA with the quasi-linear trapped gyro-Landau fluid (TGLF) model have been performed. The emerging picture from the ASTRA-TGLF runs with boundary conditions at ρ t o r = 0.94 is that, in the L-mode NT option, the larger peaking of the kinetic profiles in the edge region is not sufficient to recover the loss of the PT H-mode pedestal, and reach similar central temperature values. Two additional shapes are also considered, obtained by flipping the triangularity of the scenarios, to single out the effect of the triangularity sign. A negligible ‘direct’ effect of the triangularity is found for the L-mode, while a small beneficial effect is observed for the H-mode. The ASTRA-TGLF results are validated by GENE and TGLF stand-alone at two selected radii. GENE shows ITG dominant micro-instability and explains the small beneficial effect of the NT for the H-mode as due to a strong reduction of the heat fluxes, when reversing the triangularity, with a relatively high T i stiffness. An improvement of the predicted performances of the NT DTT scenario could come from ρ tor ≳ 0.9 , as indicated by some recent experiments at the tokamak à configuration variable (TCV) and ASDEX Upgrade.
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  • Chioncel, Ovidiu, et al. (författare)
  • Epidemiology, pathophysiology and contemporary management of cardiogenic shock - a position statement from the Heart Failure Association of the European Society of Cardiology
  • 2020
  • Ingår i: European Journal of Heart Failure. - : WILEY. - 1388-9842 .- 1879-0844. ; 22:8, s. 1315-1341
  • Tidskriftsartikel (refereegranskat)abstract
    • Cardiogenic shock (CS) is a complex multifactorial clinical syndrome with extremely high mortality, developing as a continuum, and progressing from the initial insult (underlying cause) to the subsequent occurrence of organ failure and death. There is a large spectrum of CS presentations resulting from the interaction between an acute cardiac insult and a patients underlying cardiac and overall medical condition. Phenotyping patients with CS may have clinical impact on management because classification would support initiation of appropriate therapies. CS management should consider appropriate organization of the health care services, and therapies must be given to the appropriately selected patients, in a timely manner, whilst avoiding iatrogenic harm. Although several consensus-driven algorithms have been proposed, CS management remains challenging and substantial investments in research and development have not yielded proof of efficacy and safety for most of the therapies tested, and outcome in this condition remains poor. Future studies should consider the identification of the new pathophysiological targets, and high-quality translational research should facilitate incorporation of more targeted interventions in clinical research protocols, aimed to improve individual patient outcomes. Designing outcome clinical trials in CS remains particularly challenging in this critical and very costly scenario in cardiology, but information from these trials is imperiously needed to better inform the guidelines and clinical practice. The goal of this review is to summarize the current knowledge concerning the definition, epidemiology, underlying causes, pathophysiology and management of CS based on important lessons from clinical trials and registries, with a focus on improving in-hospital management.
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  • Lukhtanov, Vladimir A., et al. (författare)
  • Incomplete Sterility of Chromosomal Hybrids : Implications for Karyotype Evolution and Homoploid Hybrid Speciation
  • 2020
  • Ingår i: Frontiers in Genetics. - : Frontiers Media SA. - 1664-8021. ; 11
  • Tidskriftsartikel (refereegranskat)abstract
    • Heterozygotes for major chromosomal rearrangements such as fusions and fissions are expected to display a high level of sterility due to problems during meiosis. However, some species, especially plants and animals with holocentric chromosomes, are known to tolerate chromosomal heterozygosity even for multiple rearrangements. Here, we studied male meiotic chromosome behavior in four hybrid generations (F1-F4) between two chromosomal races of the Wood White butterfly Leptidea sinapis differentiated by at least 24 chromosomal fusions/fissions. Previous work showed that these hybrids were fertile, although their fertility was reduced as compared to crosses within chromosomal races. We demonstrate that (i) F1 hybrids are highly heterozygous with nearly all chromosomes participating in the formation of trivalents at the first meiotic division, and (ii) that from F1 to F4 the number of trivalents decreases and the number of bivalents increases. We argue that the observed process of chromosome sorting would, if continued, result in a new homozygous chromosomal race, i.e., in a new karyotype with intermediate chromosome number and, possibly, in a new incipient homoploid hybrid species. We also discuss the segregational model of karyotype evolution and the chromosomal model of homoploid hybrid speciation.
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  • Marto, João Pedro, et al. (författare)
  • Safety and Outcome of Revascularization Treatment in Patients With Acute Ischemic Stroke and COVID-19: The Global COVID-19 Stroke Registry.
  • 2023
  • Ingår i: Neurology. - 1526-632X. ; 100:7
  • Tidskriftsartikel (refereegranskat)abstract
    • COVID-19-related inflammation, endothelial dysfunction, and coagulopathy may increase the bleeding risk and lower the efficacy of revascularization treatments in patients with acute ischemic stroke (AIS). We aimed to evaluate the safety and outcomes of revascularization treatments in patients with AIS and COVID-19.This was a retrospective multicenter cohort study of consecutive patients with AIS receiving intravenous thrombolysis (IVT) and/or endovascular treatment (EVT) between March 2020 and June 2021 tested for severe acute respiratory syndrome coronavirus 2 infection. With a doubly robust model combining propensity score weighting and multivariate regression, we studied the association of COVID-19 with intracranial bleeding complications and clinical outcomes. Subgroup analyses were performed according to treatment groups (IVT-only and EVT).Of a total of 15,128 included patients from 105 centers, 853 (5.6%) were diagnosed with COVID-19; of those, 5,848 (38.7%) patients received IVT-only and 9,280 (61.3%) EVT (with or without IVT). Patients with COVID-19 had a higher rate of symptomatic intracerebral hemorrhage (SICH) (adjusted OR 1.53; 95% CI 1.16-2.01), symptomatic subarachnoid hemorrhage (SSAH) (OR 1.80; 95% CI 1.20-2.69), SICH and/or SSAH combined (OR 1.56; 95% CI 1.23-1.99), 24-hour mortality (OR 2.47; 95% CI 1.58-3.86), and 3-month mortality (OR 1.88; 95% CI 1.52-2.33). Patients with COVID-19 also had an unfavorable shift in the distribution of the modified Rankin score at 3 months (OR 1.42; 95% CI 1.26-1.60).Patients with AIS and COVID-19 showed higher rates of intracranial bleeding complications and worse clinical outcomes after revascularization treatments than contemporaneous non-COVID-19 patients receiving treatment. Current available data do not allow direct conclusions to be drawn on the effectiveness of revascularization treatments in patients with COVID-19 or to establish different treatment recommendations in this subgroup of patients with ischemic stroke. Our findings can be taken into consideration for treatment decisions, patient monitoring, and establishing prognosis.The study was registered under ClinicalTrials.gov identifier NCT04895462.
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  • Oskyrko, Oleksandra, et al. (författare)
  • Unravelling the origin of the common wall lizards (Podarcis muralis) in south-eastern Europe using mitochondrial evidence
  • 2022
  • Ingår i: Biodiversity Data Journal. - 1314-2836. ; 10
  • Tidskriftsartikel (refereegranskat)abstract
    • The origin of the common wall lizards (Podarcis muralis) populations in south-eastern Europe (namely in Bulgaria and Romania), representing the north-eastern range border of this species, was addressed using mitochondrial DNA. We compared cytochrome b sequences from Bulgaria and Romania with those from the contiguous range in Central Europe that are available from previous studies. We recorded five main haplogroups in Bulgaria and Romania, belonging to the Central Balkan clade. However, haplogroup III was recorded in more localities than previously found. Additionally, signs of haplotype admixture were identified in several populations along the Danube River. The presence of the Southern Alps haplotype in one population from Otopeni, Bucharest (Romania) and its close phylogenetic relationships to north Italy populations suggests human-mediated introductions of this wall lizard clade in Romania. Our results confirm that P.
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  • Trahan, Alexis C., et al. (författare)
  • Results of the Swedish spent fuel measurement field trials with the Differential Die-Away Self-Interrogation Instrument
  • 2020
  • Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : ELSEVIER. - 0168-9002 .- 1872-9576. ; 955
  • Tidskriftsartikel (refereegranskat)abstract
    • Differential Die-Away Self-Interrogation (DDSI) is a method by which the characteristic die-away of neutrons from spontaneous and induced fissions is used to characterize a spent nuclear fuel assembly. A nondestructive assay (NDA) instrument was built at Los Alamos National Laboratory to implement and test the DDSI method. The DDSI instrument contains He-3 detectors which measure thermal neutrons, and the time and location of detection of each neutron is recorded via list-mode data acquisition. The instrument was sent to the Clab interim storage facility in Sweden for measurement and characterization of 50 spent pressurized water reactor (PWR) and boiling water reactor (BWR) fuel assemblies. The result was over 40 h of neutron list-mode data from a wide variety of fuel assemblies with high enough efficiency to perform neutron coincidence counting, i.e. detection of time-correlated neutrons from fission. Analysis algorithms for characterization of the fuel assemblies were tested on the Swedish spent fuel dataset. Using the measured data, multiplication, fissile mass, initial enrichment, burnup, and total plutonium mass were determined in the 50 assemblies with root mean square errors ranging from 1.5% for PWR multiplication to 11.4% for BWR fissile mass. The results in this work demonstrate that the DDSI concept is capable of characterizing spent power reactor fuel with levels of accuracy that are compatible with the requirements and objectives of various applications such as safeguards verification or facility material control and accounting.
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  • Vali, Yasaman, et al. (författare)
  • Biomarkers for staging fibrosis and non-alcoholic steatohepatitis in non-alcoholic fatty liver disease (the LITMUS project) : a comparative diagnostic accuracy study
  • 2023
  • Ingår i: The Lancet Gastroenterology & Hepatology. - : Elsevier Ltd. - 2468-1253. ; 8:8, s. 714-725
  • Tidskriftsartikel (refereegranskat)abstract
    • Background: The reference standard for detecting non-alcoholic steatohepatitis (NASH) and staging fibrosis—liver biopsy—is invasive and resource intensive. Non-invasive biomarkers are urgently needed, but few studies have compared these biomarkers in a single cohort. As part of the Liver Investigation: Testing Marker Utility in Steatohepatitis (LITMUS) project, we aimed to evaluate the diagnostic accuracy of 17 biomarkers and multimarker scores in detecting NASH and clinically significant fibrosis in patients with non-alcoholic fatty liver disease (NAFLD) and identify their optimal cutoffs as screening tests in clinical trial recruitment. Methods: This was a comparative diagnostic accuracy study in people with biopsy-confirmed NAFLD from 13 countries across Europe, recruited between Jan 6, 2010, and Dec 29, 2017, from the LITMUS metacohort of the prospective European NAFLD Registry. Adults (aged ≥18 years) with paired liver biopsy and serum samples were eligible; those with excessive alcohol consumption or evidence of other chronic liver diseases were excluded. The diagnostic accuracy of the biomarkers was expressed as the area under the receiver operating characteristic curve (AUC) with liver histology as the reference standard and compared with the Fibrosis-4 index for liver fibrosis (FIB-4) in the same subgroup. Target conditions were the presence of NASH with clinically significant fibrosis (ie, at-risk NASH; NAFLD Activity Score ≥4 and F≥2) or the presence of advanced fibrosis (F≥3), analysed in all participants with complete data. We identified thres holds for each biomarker for reducing the number of biopsy-based screen failures when recruiting people with both NASH and clinically significant fibrosis for future trials. Findings: Of 1430 participants with NAFLD in the LITMUS metacohort with serum samples, 966 (403 women and 563 men) were included after all exclusion criteria had been applied. 335 (35%) of 966 participants had biopsy-confirmed NASH and clinically significant fibrosis and 271 (28%) had advanced fibrosis. For people with NASH and clinically significant fibrosis, no single biomarker or multimarker score significantly reached the predefined AUC 0·80 acceptability threshold (AUCs ranging from 0·61 [95% CI 0·54–0·67] for FibroScan controlled attenuation parameter to 0·81 [0·75–0·86] for SomaSignal), with accuracy mostly similar to FIB-4. Regarding detection of advanced fibrosis, SomaSignal (AUC 0·90 [95% CI 0·86–0·94]), ADAPT (0·85 [0·81–0·89]), and FibroScan liver stiffness measurement (0·83 [0·80–0·86]) reached acceptable accuracy. With 11 of 17 markers, histological screen failure rates could be reduced to 33% in trials if only people who were marker positive had a biopsy for evaluating eligibility. The best screening performance for NASH and clinically significant fibrosis was observed for SomaSignal (number needed to test [NNT] to find one true positive was four [95% CI 4–5]), then ADAPT (six [5–7]), MACK-3 (seven [6–8]), and PRO-C3 (nine [7–11]). Interpretation: None of the single markers or multimarker scores achieved the predefined acceptable AUC for replacing biopsy in detecting people with both NASH and clinically significant fibrosis. However, several biomarkers could be applied in a prescreening strategy in clinical trial recruitment. The performance of promising markers will be further evaluated in the ongoing prospective LITMUS study cohort. Funding: The Innovative Medicines Initiative 2 Joint Undertaking. © 2023 The Author(s). Published by Elsevier Ltd. This is an Open Access article under the CC BY 4.0 license
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