230 research outputs found
Application of support vector machines on the basis of the first Hungarian bankruptcy model
In our study we rely on a data mining procedure known as support vector machine (SVM) on the database of the first Hungarian bankruptcy model. The models constructed are then contrasted with the results of earlier bankruptcy models with the use of classification accuracy and the area under the ROC curve. In using the SVM technique, in addition to conventional kernel functions, we also examine the possibilities of applying the ANOVA kernel function and take a detailed look at data preparation tasks recommended in using the SVM method (handling of outliers). The results of the models assembled suggest that a significant improvement of classification accuracy can be achieved on the database of the first Hungarian bankruptcy model when using the SVM method as opposed to neural networks
The cultural and geopolitical dimensions of nation-building in the Ukraine
Ukraine belongs among those young countries where the beginnings of democratisation and nation-building approximately coincided. While the development of nation states in Central Europe was usually preceded by the development of nations, the biggest dilemma in the Ukraine is whether a nation-state programme — parallel to the aim of state-building — is able to bring unfinished nation-building to completion. Ukraine sways between the EU and Russia with enormous amplitude. The alternating orientation between the West and the East can be ascribed to superpower ambitions reaching beyond Ukraine. Eventually, internal and external determinants are intertwined and mutually interact with one another. The aim of the paper is to explain the dilemmas arising from identity problems behind the Ukraine’s internal and external orientation
Spectral density asymptotics for Gaussian and Laguerre -ensembles in the exponentially small region
The first two terms in the large asymptotic expansion of the
moment of the characteristic polynomial for the Gaussian and Laguerre
-ensembles are calculated. This is used to compute the asymptotic
expansion of the spectral density in these ensembles, in the exponentially
small region outside the leading support, up to terms . The leading form
of the right tail of the distribution of the largest eigenvalue is given by the
density in this regime. It is demonstrated that there is a scaling from this,
to the right tail asymptotics for the distribution of the largest eigenvalue at
the soft edge.Comment: 19 page
Zeros of the i.i.d. Gaussian power series: a conformally invariant determinantal process
Consider the zero set of the random power series f(z)=sum a_n z^n with i.i.d.
complex Gaussian coefficients a_n. We show that these zeros form a
determinantal process: more precisely, their joint intensity can be written as
a minor of the Bergman kernel. We show that the number of zeros of f in a disk
of radius r about the origin has the same distribution as the sum of
independent {0,1}-valued random variables X_k, where P(X_k=1)=r^{2k}. Moreover,
the set of absolute values of the zeros of f has the same distribution as the
set {U_k^{1/2k}} where the U_k are i.i.d. random variables uniform in [0,1].
The repulsion between zeros can be studied via a dynamic version where the
coefficients perform Brownian motion; we show that this dynamics is conformally
invariant.Comment: 37 pages, 2 figures, updated proof
Diclofenac Prolongs Repolarization in Ventricular Muscle with Impaired Repolarization Reserve
Background: The aim of the present work was to characterize the electrophysiological effects of the non-steroidal anti-
inflammatory drug diclofenac and to study the possible proarrhythmic potency of the drug in ventricular muscle.
Methods: Ion currents were recorded using voltage clamp technique in canine single ventricular cells and action potentials
were obtained from canine ventricular preparations using microelectrodes. The proarrhythmic potency of the drug was
investigated in an anaesthetized rabbit proarrhythmia model.
Results: Action potentials were slightly lengthened in ventricular muscle but were shortened in Purkinje fibers by diclofenac
(20 mM). The maximum upstroke velocity was decreased in both preparations. Larger repolarization prolongation was
observed when repolarization reserve was impaired by previous BaCl 2 application. Diclofenac (3 mg/kg) did not prolong
while dofetilide (25 mg/kg) significantly lengthened the QT c interval in anaesthetized rabbits. The addition of diclofenac
following reduction of repolarization reserve by dofetilide further prolonged QT c . Diclofenac alone did not induce Torsades
de Pointes ventricular tachycardia (TdP) while TdP incidence following dofetilide was 20%. However, the combination of
diclofenac and dofetilide significantly increased TdP incidence (62%). In single ventricular cells diclofenac (30 mM) decreased
the amplitude of rapid (I Kr ) and slow (I Ks ) delayed rectifier currents thereby attenuating repolarization reserve. L-type calcium
current (I Ca ) was slightly diminished, but the transient outward (I to ) and inward rectifier (I K1 ) potassium currents were not
influenced.
Conclusions: Diclofenac at therapeutic concentrations and even at high dose does not prolong repolarization markedly and
does not increase the risk of arrhythmia in normal heart. However, high dose diclofenac treatment may lengthen
repolarization and enhance proarrhythmic risk in hearts with reduced repolarization reserve
Reduced Estradiol-Induced Vasodilation and Poly-(ADP-Ribose) Polymerase (PARP) Activity in the Aortas of Rats with Experimental Polycystic Ovary Syndrome (PCOS)
Polycystic ovary syndrome (PCOS) is a complex endocrine disorder characterized by hyperandrogenism and insulin resistance, both of which have been connected to atherosclerosis. Indeed, an increased risk of clinical manifestations of arterial vascular diseases has been described in PCOS. On the other hand endothelial dysfunction can be detected early on, before atherosclerosis develops. Thus we assumed that vascular dysfunction is also related directly to the hormonal imbalance rather than to its metabolic consequences. To detect early functional changes, we applied a novel rodent model of PCOS: rats were either sham operated or hyperandrogenism was achieved by implanting subcutaneous pellets of dihydrotestosterone (DHT). After ten weeks, myograph measurements were performed on isolated aortic rings. Previously we described an increased contractility to norepinephrine (NE). Here we found a reduced immediate relaxation to estradiol treatment in pre-contracted aortic rings from hyperandrogenic rats. Although the administration of vitamin D3 along with DHT reduced responsiveness to NE, it did not restore relaxation to estradiol. Poly-(ADP-ribose) polymerase (PARP) activity was assessed by poly-ADP-ribose immunostaining. Increased PAR staining in ovaries and circulating leukocytes from DHT rats showed enhanced DNA damage, which was reduced by concomitant vitamin D3 treatment. Surprisingly, PAR staining was reduced in both the endothelium and vascular smooth muscle cells of the aorta rings from hyperandrogenic rats. Thus in the early phase of PCOS, vascular tone is already shifted towards vasoconstriction, characterized by reduced vasorelaxation and vascular dysfunction is concomitant with altered PARP activity. Based on our findings, PARP inhibitors might have a future perspective in restoring metabolic disorders in PCOS
Effects of inosine on reperfusion injury after cardiopulmonary bypass
Objective: Inosine, a break-down product of adenosine has been recently shown to exert inodilatory and anti-inflammatory properties. Furthermore inosine might be a key substrate of pharmacological post-conditioning. In the present pre-clinical study, we investigated the effects of inosine on cardiac function during reperfusion in an experimental model of cardioplegic arrest and extracorporal circulation. Methods: Twelve anesthetized dogs underwent hypothermic cardiopulmonary bypass. After 60 minutes of hypothermic cardiac arrest, reperfusion was started after application of either saline vehicle (control, n = 6), or inosine (100 mg/kg, n = 6). Left ventricular end-systolic pressure volume relationship (ESPVR) was measured by a combined pressure-volume-conductance catheter at baseline and after 60 minutes of reperfusion. Left anterior descendent coronary blood flow (CBF), endothelium-dependent vasodilatation to acetylcholine (ACh) and endothelium-independent vasodilatation to sodium nitroprusside (SNP) were also determined. Results: The administration of inosine led to a significantly better recovery (given as percent of baseline) of ESPVR 90 ± 9% vs. 46 ± 6%, p < 0.05. CBF and was also significantly higher in the inosine group (56 ± 8 vs. 23 ± 4, ml/min, p < 0.05). While the vasodilatatory response to SNP was similar in both groups, ACh resulted in a significantly higher increase in CBF (58 ± 6% vs. 25 ± 5%, p < 0.05) in the inosine group. Conclusions: Application of inosine improves myocardial and endothelial function after cardiopulmonary bypass with hypothermic cardiac arrest
Potential electrophysiological impacts of supra-physiological testosterone level : investigation of the effects of testosterone-undecanoate administration chronically in a large animal model : [abstract]
Integration of new and revised chronological data to constrain the terrace evolution of the Danube River (Gerecse Hills, Pannonian Basin)
Terrace ages deduced from diverse geochronological records yielded inconsistent data in the Danube valley in
Hungary. The problem of discrepancies in the different chronological datasets has to be resolved before the Quaternary
tectonic and climatic processes leading to valley incision and terrace formation may be properly evaluated.
To establish a more robust chronology of the Danube valley in Hungary, new cosmogenic nuclide- (10Be depth
profiles, 26Al/10Be burial durations and burial depth profile) and luminescence-based (pIRIR290) terrace ages
were acquired and compared to revised paleontological and published U/Th and magnetostratigraphic data. All
the applied geo-chronometers led to concordant terrace ages, with the exception of the U/Th method applied on
travertine deposits covering terraces. U/Th ages predating the last interglacial manifest a bias towards younger
ages, and so they were ignored in relation to the quantification of terrace ages. As a result, terrace ages from
the Late Pliocene to Late Pleistocene were settled. With regard to data from the Middle Pleistocene onwards, the
combination of diverse methodologies led to a tighter bracketing of terrace ages than would be possible using
a single dating method. The modelling of cosmogenic 26Al and 10Be concentrations enabled to derive surface
denudation rates and their combination with paleontological data also allowed us to decide between diverse
landscape evolution scenarios
Cardiac remodeling accompanied by increased arrhythmia susceptibility in a dog model of chronic high-intensity endurance training : [abstract]
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