123 research outputs found
Erratum to: Blood pressure response to catheter-based renal sympathetic denervation in severe resistant hypertension: data from the Greek Renal Denervation Registry (Clin Res Cardiol, 10.1007/s00392-016-1056-z)
No full textThe original version of this article unfortunately contained a mistake. The author name E. Skalidis was misspelled. The correct information is given in the authorline. The original article has been corrected. © 2017, Springer-Verlag Berlin Heidelberg
A three-step approach to reliably estimate magnetic field strengths in star-forming regions
No full textContext. The magnetic field has been shown to play a crucial role in star formation. Dust polarization is one of the most effective tools for probing the properties of the magnetic field, yet it does not directly trace its strength. To bridge this gap, several methods have been developed, combining polarization and spectroscopic data, to estimate the strength of the magnetic field. The most widely applied method was developed by Davis (1951, Phys. Rev., 81, 890) and Chandrasekhar & Fermi (1953, ApJ, 118, 113), hereafter DCF, and relates the polarization angle dispersion to magnetic field strength under the assumption of Alfvénic turbulence. Skalidis & Tassis (2021, A&A, 647, A186), hereafter ST, relaxed this assumption to account for the compressible modes, and derived more accurate estimates of the magnetic field strength than the DCF in clouds with no self-gravity. The accuracy of these methods in self-gravitating regions is poorly explored. Aims. We aim to evaluate the accuracy of these magnetic-field estimation methods in star-forming regions and propose a systematic approach for calculating the key observational parameters they involve: the velocity dispersion (δv), the polarization angle dispersion (δθ), and the cloud density (ρ). Methods. We used a three-dimensional magnetohydrodynamic chemo-dynamical simulation of a turbulent collapsing molecular cloud. We generated synthetic observations for seven different inclination angles with respect to the mean component of the magnetic field, which encompass a comprehensive set of observables, including emission line spectra, Stokes parameters, and column density maps. We employed various approaches for estimating the parameters δv, δθ, and ρ, and identified the best approach that most effectively probes the plane-of-sky (POS) component of the magnetic field. Results. We find that the approach used to calculate the parameters δv, δθ, and ρ plays a crucial role in estimating the magnetic field strength, regardless of the specific method used (i.e., the DCF or the ST methods). We show that the value probed by both methods corresponds to the median of the molecular-species–weighted POS component of the magnetic field. We also find that ST outperforms DCF. The magnetic field strength values derived with the ST method accurately follow the expected cosine trend with respect to the inclination angle of the magnetic field and consistently remain within 1σ of the median component of the magnetic field strength. In self-gravitating clouds, we propose the following approach to accurately constrain the intrinsic parameters involved in the magnetic field estimation methods: ρ using radiative transfer analysis, δv using the second moment maps, and δθ by fitting Gaussians to the polarization angle distributions to remove the contribution of the hourglass morphology.SCI-SB-P
Mapping interventional cardiology in Europe: the European Association of Percutaneous Cardiovascular Interventions (EAPCI) Atlas Project
No full textThis is a pre-copyedited, author-produced version of an article accepted for publication in European Heart Journal, following peer review. The version of record: Emanuele Barbato, Marko Noc, Andreas Baumbach, Dariusz Dudek, Matjaz Bunc, Emmanouil Skalidis, Adrian Banning, Jacek Legutko, Nils Witt, Manuel Pan, Hans-Henrik Tilsted, Holger Nef, Giuseppe Tarantini, Dzianis Kazakiewicz, Radu Huculeci, Stephane Cook, Ahmed Magdy, Walter Desmet, Guillaume Cayla, Dragos Vinereanu, Michiel Voskuil, Omer Goktekin, Panos Vardas, Adam Timmis, Michael Haude, Mapping interventional cardiology in Europe: the European Association of Percutaneous Cardiovascular Interventions (EAPCI) Atlas Project, European Heart Journal, Volume 41, Issue 27, 14 July 2020, Pages 2579–2588, https://doi.org/10.1093/eurheartj/ehaa475
is available online at: https://doi.org/10.1093/eurheartj/ehaa47
Real-World Use and Predictors of Response to Disopyramide in Patients with Obstructive Hypertrophic Cardiomyopathy
No full textBackground: Although disopyramide has been widely used to reduce left ventricular outflow obstruction (LVOTO) and to improve symptoms in patients with obstructive hypertrophic cardiomyopathy (oHCM), its use in real world as well as patient characteristics associated with a positive treatment response are still unclear. Methods: From 1980 to 2021, 1527 patients with HCM were evaluated and 372 (23%) had a LVOTO with active follow-up. The efficacy and safety of disopyramide were assessed systematically during 12 months (2-, 6-, and 12-month visits). Responders were patients with a final NYHA = I and a LVOTO < 30 mmHg; incomplete responders were those patients with NYHA > I and a LVOTO < 30 mmHg; and non-responders were symptomatic patients with no change in functional class NYHA and a LVOT gradient > 30 mmHg. Results: Two-hundred-fifty-four (66%) patients were in functional class NYHA I/II and 118 (34%) in NYHA III/IV. A total of 118/372 (32%, 55 ± 16 years) underwent disopyramide therapy. Twenty-eight (24%) patients responded to therapy, 39 (33%) were incomplete responders, and 51 (43%) did not respond. Responder were mainly patients in functional NYHA class I/II (24/28, 86%), whereas incomplete responders and non-responders were more often in functional NYHA class III/IV (50/54 (93%)). An independent predictor of response to disopyramide treatment was the presence of NYHA I/II at the initiation of therapy (HR 1.5 (95% CI 1.1–4.5), p = 0.03). No major life-threatening arrhythmic events or syncope occurred, despite 19 (16%) patients showing reduced QTc from baseline, 19 (16%) having no difference, while 80 (69%) patients had prolonged QTc interval. Thirty-one (26%) patients experienced side effects, in particular, 29 of the anticholinergic type. Conclusions: Disopyramide was underused in oHCM but effective in reducing LVOTO gradients and symptoms in slightly symptomatic patients with less severe disease phenotype with a safe pro-arrhythmic profile
Local Bubble contribution to the 353-GHz dust polarized emission
No full textIt has not been shown so far whether the diffuse Galactic polarized emission at frequencies relevant for cosmic microwave background (CMB) studies originates from nearby or more distant regions of our Galaxy. This questions previous attempts that have been made to constrain magnetic field models at local and large scales. The scope of this work is to investigate and quantify the contribution of the dusty and magnetized local interstellar medium to the observed emission that is polarized by thermal dust. We used stars as distance candles and probed the line-of-sight submillimeter polarization properties by comparing the emission that is polarized by thermal dust at submillimeter wavelengths and the optical polarization caused by starlight. We provide statistically robust evidence that at high Galactic latitudes (|b| ≥ 60°), the 353 GHz polarized sky as observed by Planck is dominated by a close-by magnetized structure that extends between 200 and 300 pc and coincides with the shell of the Local Bubble. Our result will assist modeling the magnetic field of the Local Bubble and characterizing the CMB Galactic foregrounds
Polarized Light from Massive Protoclusters (POLIMAP). I. Dissecting the Role of Magnetic Fields in the Massive Infrared Dark Cloud G28.37+0.07 [Elektronisk resurs]
No full textMagnetic fields may play a crucial role in setting the initial conditions of massive star and star cluster formation. To investigate this, we report SOFIA-HAWC+ 214 μm observations of polarized thermal dust emission and high-resolution GBT-Argus C18O(1-0) observations toward the massive Infrared Dark Cloud (IRDC) G28.37+0.07. Considering the local dispersion of B-field orientations, we produce a map of the B-field strength of the IRDC, which exhibits values between ∼0.03 and 1 mG based on a refined Davis-Chandrasekhar-Fermi method proposed by Skalidis & Tassis. Comparing to a map of inferred density, the IRDC exhibits a B-n relation with a power-law index of 0.51 ± 0.02, which is consistent with a scenario of magnetically regulated anisotropic collapse. Consideration of the mass-to-flux ratio map indicates that magnetic fields are dynamically important in most regions of the IRDC. A virial analysis of a sample of massive, dense cores in the IRDC, including evaluation of magnetic and kinetic internal and surface terms, indicates consistency with virial equilibrium, sub-Alfvénic conditions, and a dominant role for B-fields in regulating collapse. A clear alignment of magnetic field morphology with the direction of the steepest column density gradient is also detected. However, there is no preferred orientation of protostellar outflow directions with the B-field. Overall, these results indicate that magnetic fields play a crucial role in regulating massive star and star cluster formation, and therefore they need to be accounted for in theoretical models of these processes
Τεχνολογίες εικονικής αξιολόγησης κλασματικής εφεδρείας ροής
No full textPart One. Introduction: Non-invasive methods for assessing fractional flow reserve (FFR) are being actively studied to overcome the limitations of conventional invasive assessment, which requires the use of an intra-arterial pressure wire and administration of hyperemic agents such as adenosine. Angiography-derived FFR (FFRangio) has already demonstrated its diagnostic performance in the context of stable coronary artery disease. However, its application in the setting of non-ST-elevation myocardial infarction (NSTEMI) has not been investigated. Methods: We conducted a prospective, single-center, double-blind study comparing FFR calculated from FFRangio with invasively measured FFR in patients with NSTEMI. FFR was measured in all angiographically intermediate lesions (30%-70% stenosis) and then compared to FFRangio calculated at the same sites. The primary endpoints were the sensitivity and specificity of FFRangio for measuring FFR using a threshold value of ≤0.80. Results: Among 100 NSTEMI patients, 46 patients with 60 vessels were included in the study. The mean FFR was 0.83±0.3 with 22 (36%) being ≤0.80, while the mean FFRangio was 0.82±0.1 with 22 (36%) being ≤0.80. FFRangio demonstrated a sensitivity of 95.5%, specificity of 97.4%, and diagnostic accuracy of 96.7%. Conclusion: FFRangio can accurately and non-invasively assess FFR in NSTEMI and may play a role in guiding treatment decisions related to intermediate coronary lesions in this patient population .Part Two. Introduction: FFRangio and quantitative flow ratio (QFR) are non-invasive methods for assessing FFR, and to date, no comparative study between them in the same patient population has been reported in the literature. Methods: This study is a subset of a larger prospective multicenter single-arm study that included patients diagnosed with NSTEMI, in whom coronary stenosis of 30-70% was evaluated with FFR. FFRangio and QFR were calculated by two different operators and compared with FFR. The two primary endpoints were the comparison of Pearson correlation coefficients between FFRangio and QFR with FFR and the comparison of inter-observer variability. Results: Among the 134 NSTEMI patients screened, 59 patients with 84 vessels underwent FFR measurements and were included in this study. The mean FFR was 0.82±0.40 with 32 (38%) being ≤0.80. The mean FFRangio was 0.82±0.20, and the mean QFR was 0.82±0.30, with 27 (32%) and 25 (29%) being ≤0.80, respectively. The Pearson correlation coefficient was significantly better for FFRangio compared to QFR, with R values of 0.76 and 0.61, respectively (p=0.01). Inter-observer agreement was also significantly better for FFRangio compared to QFR (0.86 vs. 0.79, p < 0.05). FFRangio had a sensitivity of 91%, specificity of 100%, and accuracy of 96.8%, whereas QFR showed a sensitivity of 86.4%, specificity of 98.4%, and accuracy of 93.7%.Conclusion: In NSTEMI patients, both FFRangio and QFR demonstrated excellent diagnostic performance. FFRangio appears to have a better correlation with invasive FFR compared to QFR.Πρώτο Μέρος. Εισαγωγή: Μη επεμβατικές μέθοδοι εκτίμησης της κλασματικής εφεδρείας ροής (FFR) μελετώνται ενεργά, με στόχο να ξεπεράσουν τα προβλήματα της επεμβατικής συμβατικής εκτίμησης που απαιτεί τη χρήση ενδοαρτηριακού σύρματος μέτρησης πίεσης και τη χορήγηση φαρμάκων που προκαλούν υπεραιμία όπως η αδενοσίνη. Το FFR που προκύπτει από την αγγειογραφία με μη επεμβατικό τρόπο (FFRangio) έχει ήδη επιδείξει τη διαγνωστική του απόδοση στο πλαίσιο της σταθερής στεφανιαίας νόσου. Ωστόσο, η δεν έχει μελετηθεί στο πλαίσιο του οξέος εμφράγματος του μυοκαρδίου χωρίς ανάσπαση του διαστήματος ST (NSTEMI). Μέθοδοι: Διεξήγαμε μια προοπτική, μονοκεντρική, διπλά τυφλή μελέτη συγκρίνοντας το FFR που υπολογίζεται από το FFRangio με το επεμβατικά μετρημένο FFR σε ασθενείς με NSTEMI. Το FFR μετρήθηκε σε όλες τις αγγειογραφία ενδιάμεσες βλάβες (30%-70% στένωση) και στη συνέχεια συγκρίθηκε με το FFRangiο που υπολογίστηκε στην ίδια θέση. Οι κύριοι στόχοι ήταν η ευαισθησία και η ειδικότητα του FFRangio για την μέτρηση του FFR χρησιμοποιώντας ένα κατώτατο όριο τιμής ≤0.80. Αποτελέσματα: Ανάμεσα σε 100 ασθενείς με NSTEMI που προσήλθαν, 46 ασθενείς με 60 αγγεία συμπεριλήφθηκαν στη μελέτη. Η μέση τιμή του FFR ήταν 0,83±0,3 με 22 (36%) να είναι ≤0.80, ενώ η μέση τιμή του FFRangiο ήταν 0,82±0,1 με 22 (36%) να είναι ≤0.80. Το FFRangio επέδειξε ευαισθησία 95,5%, ειδικότητα 97,4% και διαγνωστική ακρίβεια 96,7%. Συμπέρασμα: Το FFRangio μπορεί με ακρίβεια και μη επεμβατικά να εκτιμήσει το FFR σε NSTEMI και μπορεί να έχει ρόλο στην καθοδήγηση των αποφάσεων θεραπείας που σχετίζονται με ενδιάμεσες στεφανιαίες βλάβες στον συγκεκριμένο πληθυσμό ασθενών. Δεύτερο Μέρος. Εισαγωγή: Τα FFRangio και QFR είναι μη επεμβατικές μέθοδοι εκτίμησης του FFR και δεν έχει αναφερθεί μέχρι σήμερα στην βιβλιογραφία καμία συγκριτική μελέτη μεταξύ τους στον ίδιο πληθυσμό ασθενών. Μέθοδοι: Η μελέτη αυτή αποτελεί υποσύνολο μιας μεγαλύτερης προοπτικής πολυκεντρικής μελέτης με ενιαίο βραχίονα που περιλάμβανε ασθενείς που διαγνώστηκαν με NSTEMI, στους οποίους η στεφανιαία στένωση 30-70% αξιολογήθηκε με FFR. Το FFRangio και το QFR υπολογίστηκαν από 2 διαφορετικούς χειριστές και συγκρίθηκαν με το FFR. Τα δύο κύρια καταληκτικά σημεία ήταν η σύγκριση του συντελεστή συσχέτισης Pearson μεταξύ FFRangio και QFR με το FFR και η σύγκριση της μεταβλητότητας μεταξύ των παρατηρητών τους.Αποτελέσματα: Από τους 134 ασθενείς με NSTEMI που ελέγχθηκαν, 59 ασθενείς με 84 αγγεία υποβλήθηκαν σε μετρήσεις FFR και συμπεριλήφθηκαν σε αυτήν τη μελέτη. Η μέση τιμή FFR ήταν 0,82±0,40 με 32 (38%) να είναι ≤0,80. Η μέση τιμή FFRangio ήταν 0,82±0,20 και η μέση τιμή QFR ήταν 0,82±0,30, με 27 (32%) και 25 (29%) να είναι ≤0,80 αντίστοιχα. Ο συντελεστής συσχέτισης Pearson ήταν σημαντικά καλύτερος για το FFRangio σε σύγκριση με το QFR, με τιμές R 0,76 και 0,61 αντίστοιχα (p=0,01). Η συμφωνία μεταξύ των παρατηρητών ήταν επίσης σημαντικά καλύτερη για το FFRangio σε σύγκριση με το QFR (0,86 έναντι 0,79, p < 0,05). Το FFRangio είχε ευαισθησία 91%, ειδικότητα 100% και ακρίβεια 96,8%, ενώ το QFR εμφάνισε ευαισθησία 86,4%, ειδικότητα 98,4% και ακρίβεια 93,7%. Συμπέρασμα: Σε ασθενείς με NSTEMI, τα FFRangio και QFR επέδειξαν εξαιρετική διαγνωστική απόδοση. Το FFRangio φαίνεται να έχει καλύτερη συσχέτιση με το επεμβατικό FFR σε σύγκριση με το QFR
Polarized Light from Massive Protoclusters (POLIMAP). I. Dissecting the Role of Magnetic Fields in the Massive Infrared Dark Cloud G28.37+0.07
No full textMagnetic fields may play a crucial role in setting the initial conditions of massive star and star cluster formation. To investigate this, we report SOFIA-HAWC+ 214 μm observations of polarized thermal dust emission and high-resolution GBT-Argus C18O(1-0) observations toward the massive Infrared Dark Cloud (IRDC) G28.37+0.07. Considering the local dispersion of B-field orientations, we produce a map of the B-field strength of the IRDC, which exhibits values between ∼0.03 and 1 mG based on a refined Davis-Chandrasekhar-Fermi method proposed by Skalidis & Tassis. Comparing to a map of inferred density, the IRDC exhibits a B-n relation with a power-law index of 0.51 ± 0.02, which is consistent with a scenario of magnetically regulated anisotropic collapse. Consideration of the mass-to-flux ratio map indicates that magnetic fields are dynamically important in most regions of the IRDC. A virial analysis of a sample of massive, dense cores in the IRDC, including evaluation of magnetic and kinetic internal and surface terms, indicates consistency with virial equilibrium, sub-Alfvénic conditions, and a dominant role for B-fields in regulating collapse. A clear alignment of magnetic field morphology with the direction of the steepest column density gradient is also detected. However, there is no preferred orientation of protostellar outflow directions with the B-field. Overall, these results indicate that magnetic fields play a crucial role in regulating massive star and star cluster formation, and therefore they need to be accounted for in theoretical models of these processes
Bright-Moon sky as a wide-field linear Polarimetric flat source for calibration
No full textContext. Next-generation wide-field optical polarimeters such as Wide-Area Linear Optical Polarimeters (WALOPs) have a field of view (FoV) of tens of arcminutes. Wide-field polarimetric flat sources are essential to the efficient and accurate calibration of these instruments. However, no established wide-field polarimetric standard or flat sources exist at present. Aims. This study tests the feasibility of using the polarized sky patches of the size of around 10 × 10 arcminutes2, at a distance of up to 20 from the Moon, on bright-Moon nights as a wide-field linear polarimetric flat source. Methods. We observed 19 patches of the sky adjacent to the bright-Moon with the RoboPol instrument in the SDSS-r broadband filter. These patches were observed on five nights within two days of the full-Moon across two RoboPol observing seasons. Results. We find that for 18 of the 19 patches, the uniformity in the measured normalized Stokes parameters q and u is within 0.2%, with 12 patches exhibiting uniformity within 0.07% or better for both q and u simultaneously, making them reliable and stable wide-field linear polarization flats. Conclusions. We demonstrate that the sky on bright-Moon nights is an excellent wide-field linear polarization flat source. Various combinations of the normalized Stokes parameters q and u can be obtained by choosing suitable locations of the sky patch with respect to the Moon
Analytic characterization of sub-Alfv\'enic turbulence energetics
No full textMagnetohydrodynamic (MHD) turbulence is a cross-field process relevant to
many systems. A prerequisite for understanding these systems is to constrain
the role of MHD turbulence, and in particular the energy exchange between
kinetic and magnetic forms. The energetics of strongly magnetized and
compressible turbulence has so far resisted attempts to understand them.
Numerical simulations reveal that kinetic energy can be orders of magnitude
larger than fluctuating magnetic energy. We solve this lack-of-balance puzzle
by calculating the energetics of compressible and sub-Alfv\'enic turbulence
based on the dynamics of coherent cylindrical fluid parcels. Using the MHD
Lagrangian, we prove analytically that the bulk of the magnetic energy
transferred to kinetic is the energy stored in the coupling between the ordered
and fluctuating magnetic field. The analytical relations are in striking
agreement with numerical data, up to second order terms.Comment: accepted for publication in A&
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