22 research outputs found
Hilbert property for double conic bundles and del Pezzo varieties
In this paper we prove that, over a Hilbertian ground field, surfaces with
two conic fibrations whose fibres have non-zero intersection product have the
Hilbert property. We then give an application of this result, namely the
verification of the Hilbert property for certain del Pezzo varieties.Comment: 9 page
Weak approximation and the Hilbert property for Campana points
We study weak approximation and the Hilbert property for Campana points, both
of importance in recent work on a Manin-type conjecture by Pieropan, Smeets,
Tanimoto and Varilly-Alvarado. We show that weak weak approximation implies the
Hilbert property for Campana points, and we exploit this to exhibit Campana
orbifolds whose sets of Campana points are not thin.Comment: 23 pages, minor revisions, comments welcom
Semi-integral Brauer-Manin obstruction and quadric orbifold pairs
We study local-global principles for two notions of semi-integral points,
termed Campana points and Darmon points. In particular, we develop a
semi-integral version of the Brauer-Manin obstruction interpolating between
Manin's classical version for rational points and the integral version
developed by Colliot-Th\'el\`ene and Xu. We determine the status of
local-global principles, and obstructions to them, in two families of orbifolds
naturally associated to quadric hypersurfaces. Further, we establish a
quantitative result measuring the failure of the semi-integral Brauer-Manin
obstruction to account for its integral counterpart for affine quadrics.Comment: 39 page
Weak weak approximation and the Hilbert property for degree-two del Pezzo surfaces
We prove that del Pezzo surfaces of degree over a field satisfy weak
weak approximation if is a number field and the Hilbert property if is
Hilbertian of characteristic zero, provided that they contain a -rational
point lying neither on any of the exceptional curves nor on the
ramification divisor of the anticanonical morphism. This builds upon results of
Manin, Salgado--Testa--V\'arilly-Alvarado, and Festi--van Luijk on the
unirationality of such surfaces, and upon work of the first two authors
verifying weak weak approximation under the assumption of a conic fibration.Comment: 22 pages, minor edits, comments welcom
International Veterinary Epilepsy Task Force consensus proposal: Medical treatment of canine epilepsy in Europe
In Europe, the number of antiepileptic drugs (AEDs) licensed for dogs has grown considerably over the last years. Nevertheless, the same questions remain, which include, 1) when to start treatment, 2) which drug is best used initially, 3) which adjunctive AED can be advised if treatment with the initial drug is unsatisfactory, and 4) when treatment changes should be considered. In this consensus proposal, an overview is given on the aim of AED treatment, when to start long-term treatment in canine epilepsy and which veterinary AEDs are currently in use for dogs. The consensus proposal for drug treatment protocols, 1) is based on current published evidence-based literature, 2) considers the current legal framework of the cascade regulation for the prescription of veterinary drugs in Europe, and 3) reflects the authors’ experience. With this paper it is aimed to provide a consensus for the management of canine idiopathic epilepsy. Furthermore, for the management of structural epilepsy AEDs are inevitable in addition to treating the underlying cause, if possible
Quantifying the effect of uncertainty in input parameters in a simplified bidomain model of partial thickness ischaemia
Reduced blood flow in the coronary arteries can lead to damaged heart tissue (myocardial ischaemia). Although one method for detecting myocardial ischaemia involves changes in the ST segment of the electrocardiogram, the relationship between these changes and subendocardial ischaemia is not fully understood. In this study, we modelled ST-segment epicardial potentials in a slab model of cardiac ventricular tissue, with a central ischaemic region, using the bidomain model, which considers conduction longitudinal, transverse and normal to the cardiac fibres. We systematically quantified the effect of uncertainty on the input parameters, fibre rotation angle, ischaemic depth, blood conductivity and six bidomain conductivities, on outputs that characterise the epicardial potential distribution. We found that three typical types of epicardial potential distributions (one minimum over the central ischaemic region, a tripole of minima, and two minima flanking a central maximum) could all occur for a wide range of ischaemic depths. In addition, the positions of the minima were affected by both the fibre rotation angle and the ischaemic depth, but not by changes in the conductivity values. We also showed that the magnitude of ST depression is affected only by changes in the longitudinal and normal conductivities, but not by the transverse conductivities