Black Holes and Host Galaxies of NLS1s

Recently, reliable mass estimates for the central black holes in AGN became feasible due to emission-line reverberation techniques. Using this method as a calibrator, it is possible to determine black hole masses for a wide range of AGN, in particular NLS1s. Do NLS1s have smaller black holes than ordinary Seyfert 1 galaxies? Are their black holes smaller compared to the sizes of their host galaxies? Do they have larger L/M ratios? Do NLS1s have hotter accretion disks? I confront these questions with accretion disk theory and with the data, showing that the above may well be the case.Comment: Contributed talk presented at the Joint MPE,AIP,ESO workshop on NLS1s, Bad Honnef, Dec. 1999, to appear in New Astronomy Reviews; also available at http://wave.xray.mpe.mpg.de/conferences/nls1-worksho

Stability of tautological bundles on the Hilbert scheme of two points on a surface

Let (X,H) be a polarized smooth projective surface satisfying H^1(X,O_X)=0 and let F be either a rank one torsion-free sheaf or a rank two {\mu}H-stable vector bundle on X. Assume that c_1(F)/=0. In this article it is shown that the rank two, respectively rank four tautological sheaf F^{[2]} associated with F on the Hilbert square X^{[2]} is {\mu}-stable with respect to a certain polarization.Comment: 14 pages, minors corrections of typos, replaced Lemma 2.2 by Def 2.2 and Prop. 2.3, to appear in Nag. Math.

A stochastic micromixing model based on the turbulent diffusion length scale

A new micromixing model to close probability density function (pdf) models is proposed. The model is based on the proposition that each computational timestep, stochastic particles move within the scalar space (on average) by a distance equal to the turbulent diffusion length scale. At each timestep, the model evaluates the distance in scalar space between all particles. During the timestep, a discrete pdf is computed for the distance between unmixed particles and the cumulative integral for the mean calculated. A filter is applied to retain the lower portion of the distance domain so that the cumulative integral is equal to the average diffusion length required to decrease the scalar variance. A sample (a pair of particles) is chosen from this filtered part of the domain and the particles mixed using Modified Curl's model. The complete interparticle-distance pdf is re-evaluated for each pair to ensure that there is sufficient capacity to mix to meet the variance decay requirements. Preliminary tests show that this model obeys several fundamental properties required of micromixing models, including conservation, correct decay of variance and relaxation to Gaussian pdf

The cluster-based development strategy in Kazakhstan's agro-food sector: A critical assessment from an Austrian perspective

This paper challenges the uselfullness of the cluster-based development strategy to diversify and increase the competitiveness of Kazakhstan's economy, regarding the case of the country's agro-food sector. For this it refers to insights of the Austrian Market Process Theory. It is argued that already the theoretical foundations of the cluster concept suffer from severe difficiencies, because it widely neglects the function of competition as a discovery procedure with alert entrepreuneurs as the driving force. Moreover, it ignores the knowledge requirements and limitations in a modern market economy for any outside third party to identify and promote successful industry structures. The closer examination of the implementation of the cluster development program in Kazakhstan's agro-food sectors shows that cluster facilitation in practice turned out to be another form of social engineering and picking winners. In the light of the Austrian understanding of the market system as an entrepreneurial discovery process the paper suggestes as alternative policy option to concentrate on the establishment of a stable institutional framework for the whole economy that stimulates the entrepreneurial discoveries of profitable businesses. Yet, such an Austrian approach is politically less appealing, for it might bring no quick results due to the prevalence of conflicting informal institutions which in the short run might be difficult to change. -- G E R M A N V E R S I O N: Der Beitrag diskutiert die Eignung der Clusterförderungspolitik zur Diversifizierung und Verbesserung der Wettbewerbsfähigkeit der Volkswirtschaft Kasachstans am Beispiel der Agrar- und Ernährungswirtschaft des Landes. Dazu wird auf Erkenntnisse der Marktprozeßtheorie der Österreichischen Schule zurückgegriffen. Es wird argumentiert, daß allein schon die theoretische Fundierung der Clusterförderungspolitik fraglich ist, weil sie die Funktion des Wettbewerbs als eines Entdeckungsverfahrens mit findigen Unternehmern als treibende Kraft vernachlässigt. Darüber hinaus unterschätzt sie die Anforderungen an das Wissen, das staatliche Akteure und beratende Ökonomen haben müßten, um erfolgversprechende Industrie- und Unternehmensstrukturen identifizieren und fördern zu können. Die Analyse der Umsetzung der Clusterförderungspolitik in Kasachstans Agrar-und Ernährungswirtschaft zeigt, daß sie praktisch nichts anderes ist als eine weitere Form von staatlichem Konstruktivismus und einer Politik der picking winners. Ausgehend vom Verständnis der Österreichischen Schule des Marktsystems als eines von findigen Unternehmern getragenen Entdeckungsverfahrens schlägt der Beitrag als alternative Strategie vor, sich auf den Aufbau von verlässlichen institutionellen Rahmenbedingungen zu konzentrieren, die für alle Sektoren der kasachstanischen Volkswirtschaft gleichermaßen gelten und die geeignet sind, den unternehmerischen Entdeckungsprozeß zu fördern. Aus politischen Gründen dürfte jedoch diese österreichische Politikoption wenig attraktiv sein, da sie langfristig angelegt ist und kurzfristig nicht zuletzt aufgrund des Konflikts zwischen formalen und informalen Institutionen keine sichtbaren Resultate erwarten lässt.Cluster,Kazakhstan,industrial policy,institutional change,Cluster,Kasachstan,Industriepolitik,institutioneller Wandel

Induced automorphisms on irreducible symplectic manifolds

We introduce the notion of induced automorphisms in order to state a criterion to determine whether a given automorphism on a manifold of K3[n]-type is, in fact, induced by an automorphism of a K3 surface, and the manifold is a moduli space of stable objects on the K3. This criterion is applied to the classification of non-symplectic prime order automorphisms on manifolds of K3[2]-type, and we prove that almost all cases are covered. Variations of this notion and the above criterion are introduced and discussed for the other known deformation types of irreducible symplectic manifolds. Furthermore, we provide a description of the picard lattice of several irreducible symplectic manifolds having a lagrangian fibration