Search results for "bundle"

Andreklassingers arbeid med problemløsningsoppgaver : Et semiotisk perspektiv

2019

Masteroppgave matematikkdidaktikk MA502 – Universitetet i Agder 2019 This master thesis presentsaqualitative case study whichexplore year 2 students work with problem solving tasks, in a semiotic perspective. In the study, three small groups were observed while working with problem solving tasks. The aim of the observations where to getaninsight into which semiotic resources the students used while working onthe problem solving tasks. Video recordings from the observations make up the empirical data material of this study. This study is placed in the socio-cultural learning perspective. The aim of this study is to explore which semiotic resources the students use while working onproblem sol…

Theta-characteristics on singular curves

2007

On a smooth curve a theta–characteristic is a line bundle L with square that is the canonical line bundle ω. The equivalent conditionHom(L, ω) ∼= L generalizes well to singular curves, as applications show. More precisely, a theta–characteristic is a torsion–free sheaf F of rank 1 with Hom(F , ω) ∼= F . If the curve has non ADE–singularities then there are infinitely many theta–characteristics. Therefore, theta–characteristics are distinguished by their local type. The main purpose of this article is to compute the number of even and odd theta–characteristics (i.e. F with h(C,F) ≡ 0 resp. h(C,F) ≡ 1 modulo 2) in terms of the geometric genus of the curve and certain discrete invariants of a …

A method for quantifying atrial fibrillation organization based on wave-morphology similarity

2002

A new method for quantifying the organization of single bipolar electrograms recorded in the human atria during atrial fibrillation (AF) is presented. The algorithm relies on the comparison between pairs of local activation waves (LAWs) to estimate their morphological similarity, and returns a regularity index (/spl rho/) which measures the extent of repetitiveness over time of the detected activations. The database consisted of endocardial data from a multipolar basket catheter during AF and intraatrial recordings during atrial flutter. The index showed maximum regularity (/spl rho/=1) for all atrial flutter episodes and decreased significantly when increasing AF complexity as defined by W…

Big Vector Bundles on Surfaces and Fourfolds

2019

The aim of this note is to exhibit explicit sufficient criteria ensuring bigness of globally generated, rank-$r$ vector bundles, $r \geqslant 2$, on smooth, projective varieties of even dimension $d \leqslant 4$. We also discuss connections of our general criteria to some recent results of other authors, as well as applications to tangent bundles of Fano varieties, to suitable Lazarsfeld-Mukai bundles on four-folds, etcetera.

Rivestimenti di varietà algebriche contenuti in fibrati di piani proiettivi

The Itô Integral

2014

The Ito integral allows us to integrate stochastic processes with respect to the increments of a Brownian motion or a somewhat more general stochastic process. We develop the Ito integral first for Brownian motion and then for generalized diffusion processes (so called Ito processes). In the third section, we derive the celebrated Ito formula. This is the chain rule for the Ito integral that enables us to do explicit calculations with the Ito integral. In the fourth section, we use the Ito formula to obtain a stochastic solution of the classical Dirichlet problem. This in turn is used in the fifth section in order to show that like symmetric simple random walk, Brownian motion is recurrent …

Lithium and GSK3-β promoter gene variants influence white matter microstructure in bipolar disorder

2013

Lithium is the mainstay for the treatment of bipolar disorder (BD) and inhibits glycogen synthase kinase 3-beta (GSK3-beta). The less active GSK3-beta promoter gene variants have been associated with less detrimental clinical features of BD. GSK3-beta gene variants and lithium can influence brain gray matter structure in psychiatric conditions. Diffusion tensor imaging (DTI) measures of white matter (WM) integrity showed widespred disruption of WM structure in BD. In a sample of 70 patients affected by a major depressive episode in course of BD, we investigated the effect of ongoing long-term lithium treatment and GSK3-beta promoter rs334558 polymorphism on WM microstructure, using DTI and …

The Dawning of Computational Psychoanalysis

2014

In this paper, the author wishes first to highlight, within the general cultural context, some possible elementary computational psychoanalysis formalizations concerning Matte Blanco's bi-logic components through certain very elementary mathematical tools and notions drawn from theoretical physics and algebra. Afterwards, on the basis of recent work of Giampaolo Sasso (1999; 2005; 2011), relying on the crucial crossroad between neurosciences and psychoanalysis, it will be possible to identify some hints for further formalization attempts turned toward a computational psychoanalysis outlook. Lastly, possible interesting relationships with cognitive informatics are also outlined.

Right ventricular dysfunction in hemodynamically stable patients with acute pulmonary embolism

2013

Abstract Background Echocardiography for risk stratification in hemodynamically stable patients with pulmonary embolism (PE) is well-established. Right ventricular dysfunction (RVD) is associated with an elevated mortality and adverse outcome. The aim of our study was to compare RVD criteria and investigate the role of elevated systolic pulmonary artery pressure (sPAP) in the diagnosis of RVD. Methods We retrospectively analyzed the echocardiographic and laboratory data of all hemodynamically stable patients with confirmed PE (2006-2011). The data were compared with three different definitions of RVD: Definition 1: RV dilatation, abnormal motion of interventricular septum, RV hypokinesis or…

Elevation of striatal urate in experimental models of Parkinson's disease: a compensatory mechanism triggered by dopaminergic nigrostriatal degenerat…

2014

Epidemiological studies have indicated an inverse association between high uricemia and incidence of Parkinson's disease (PD). To investigate the link between endogenous urate and neurotoxic changes involving the dopaminergic nigrostriatal system, this study evaluated the modifications in the striatal urate levels in two models of PD. To this end, a partial dopaminergic degeneration was induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) in mice, while a severe dopaminergic degeneration was elicited by unilateral medial forebrain bundle infusion of 6-hydroxydopamine (6-OHDA) in rats. Urate levels were measured by in vivo microdialysis at 7 or 14 days from toxin exposure. The resu…