401 research outputs found

    Stability and covergence properties of Bergman Kernel methods for numerical conformal mapping

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    In this paper we study the stability and convergence properties of Bergman kernel methods, for the numerical conform al mapping of simply and doubly- connected domains. In particular, by using certain well-known results of Carleman, we establish a characterization of the level of instability in the methods, in terms of the geometry of the domain under consideration. We also explain how certain known convergence results can provide some theoretical justification of the observed improvement in accuracy which is achieved by the methods, when the basis set used contains functions that reflect the main singular behaviour of the conformal map

    Pole type singularities and the numerical conformal mapping of doubly-connected domains

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    Let f be the function which maps conformally a given doubly-connected domain onto a circular annulus, and let Ω H(z) = f '(z) / f(z) - 1/z . In this paper we consider the problem of determining the main singularities of the function H in compl)(Ω∂∪Ω. Our purpose is to provide information regarding the location and nature of such singularities, and to explain how this information can be used to improve the efficiency of certain expansion methods for numerical conformal mapping

    Staged Percutaneous Coronary Intervention (PCI) for Multivessel STEMI Patients?

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    Primary percutaneous coronary intervention (PCI) is the treatment of choice for patients with ST-elevation myocardial infarction (STEMI) since it results in greater patency of the infarct-related artery (IRA) and lower rates of re-infarction, stroke and death when compared with fibrinolysis alone. Multivessel disease (MVD) occurs in 40% to 65% of patients with STEMI. Is it possible for an aggressive multivessel percutaneous revascularization strategy to afford advantages in greater myocardial salvage and avoidance of staged procedures, with subsequent savings in compounded procedural risks? ...(excerpt

    ANALYSIS OF PRIESTLEY-TAYLOR METHOD FOR THE ASSESSMENT OF REFERENCE EVAPOTRANSPIRATION IN GREECE

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    Στόχος της εργασίας είναι η εύρεση του εποχιακού σφάλματος στην εκτίμηση της εξατμισοδιαπνοής καλλιέργειας αναφοράς ΕΤο με τη μέθοδο Priestley-Taylor (P-T) και ο επαναπροσδιορισμός του συντελεστή μεταγωγής apt χρησιμοποιώντας τη μέθοδο Penman-Monteith κατά ASCE. Η ανάλυση έγινε για όλο τον ελλαδικό χώρο με χρήση GIS και μέσα μηνιαία κλιματικά δεδομένα της περιόδου 1950-2000. Η ανάλυση σφάλματος για το θερινό εξάμηνο Απριλίου-Σεπτεμβρίου έδειξε ότι η μέθοδος P-T παρουσιάζει αποδεκτές τιμές στο 75.3%, ενώ για το χειμερινό εξάμηνο Οκτωβρίου-Μαρτίου στο 20.2% της ελληνικής επικράτειας. Ο επαναπροσδιορισμός της μέσης τιμής του apt για το χειμερινό και θερινό εξάμηνο έδειξε ότι η χωρική μεταβλητότητά του παρουσιάζει συσχέτιση της τάξεως του ~94% με το έλλειμμα πίεσης κορεσμού υδρατμών. Από την ανάλυση της εποχιακής μεταβολής του συντελεστή apt εκτιμήθηκε η μέση τιμή του σε 1.29 και 1.51 για τη θερινή και χειμερινή περίοδο, αντίστοιχα.The aim of the study is to estimate the seasonal error in the assessment of reference crop evapotranspiration ΕΤο using the Priestley-Taylor (P-T) method and to revise the advection coefficient apt using as a base the ASCE standardized Penman-Monteith method. Analysis was performed for the Greek territory using GIS and gridded data which cover the mean monthly values of climatic parameters for the period 1950-2000. The analysis of seasonal error showed that P-T presents acceptable values in the 73.5% and 20.2% coverage of the greek territory for the dry-warm season (April-September) and the cold-wet season (October-March), respectively. Recalculation of apt for both seasons showed that its spatial variation is described at ~94% level by the vapor pressure deficit. The mean values of apt for the dry-warm season and the cold wet season were found to be 1.29 και 1.51, respectively

    Adjuvant Chemoradiation Therapy in Gastric Cancer: Critically Reviewing the Past and Visualizing the Next Step Forward

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    none9Gastric cancer remains one of the most common malignancies worldwide. Despite the significant advances in surgical treatment and multimodality strategies, prognosis has modestly improved over the last two decades. Locoregional relapse remains one of the main issues and the combined chemoradiation treatment seems to be one of the preferred approaches. However, more than ten years after the hallmark INT-0116 trial, minimal progress has been made both in terms of effectiveness and toxicity. Moreover, new regimens added to combined therapy failed to prove favourable results. Herein, we attempt a thorough literature review comparing pros and cons of all relative studies and potential bias, targeting well-designed future approaches.openPapadimitriou K.; Antoniou G.; Rolfo C.; Russo A.; Bronte G.; Vassiliou V.; Papamichael D.; Peeters M.; Kountourakis P.Papadimitriou, K.; Antoniou, G.; Rolfo, C.; Russo, A.; Bronte, G.; Vassiliou, V.; Papamichael, D.; Peeters, M.; Kountourakis, P

    A 3-dimensional Bergman Kernel method with applications to rectangular domains

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    In this paper we revisit the so-called Bergman kernel method - BKM - for solving conformal mapping problems and propose a generalized BKM-approach to extend the theory to 3-dimensional mapping problems. A special software package for quaternions was developed for the numerical experiments.Fundação para a Ciência e a Tecnologia (FCT
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