On fundamental groups related to the Hirzebruch surface F_1

Given a projective surface and a generic projection to the plane, the braid monodromy factorization (and thus, the braid monodromy type) of the complement of its branch curve is one of the most important topological invariants, stable on deformations. From this factorization, one can compute the fundamental group of the complement of the branch curve, either in C^2 or in CP^2. In this article, we show that these groups, for the Hirzebruch surface F_{1,(a,b)}, are almost-solvable. That is - they are an extension of a solvable group, which strengthen the conjecture on degeneratable surfaces.Comment: accepted for publication at "Sci. in China, ser. Math"; 22 pages, 11 figure

A characterization of compact complex tori via automorphism groups

We show that a compact Kaehler manifold X is a complex torus if both the continuous part and discrete part of some automorphism group G of X are infinite groups, unless X is bimeromorphic to a non-trivial G-equivariant fibration. Some applications to dynamics are given.Comment: title changed, to appear in Math. An

Generic coverings of plane with A-D-E-singularities

We generalize results of the paper math.AG/9803144, in which Chisini's conjecture on the unique reconstruction of f by the curve B is investigated. For this fibre products of generic coverings are studied. The main inequality bounding the degree of a covering in the case of existence of two nonequivalent coverings with the branch curve B is obtained. This inequality is used for the proof of the Chisini conjecture for m-canonical coverings of surfaces of general type for $m\ge 5$.Comment: 43 pages, 20 figures; to appear in Izvestiya Mat

The mediating role of perceived motor competence in the relationship between actual motor competence and physical activity in children

This study aimed to investigate the mediating role of perceived motor competence in the relationship between motor competence and physical activity in children as hypothesized by Stodden and colleagues (2008) in their conceptual model of motor competence. A total of 207 children aged 8-13 years (58.9% girls) took part in the study. Actual and perceived motor competence (i.e., overall competence, and competence in locomotor and object control skills) were measured using the Test of Gross Motor Development, 3rd Edition, and the Perceived Motor Competence questionnaire in Childhood, respectively. Physical activity was assessed using a self-report questionnaire. Mediation analyses revealed that the relationship between actual motor competence and physical activity was mediated by perceived motor competence. Specifically, a significant indirect effect of actual competence on physical activity through perceived competence was observed for overall competence (β = 0.168) and object control skills (β = 0.178). The present study provides evidence towards mechanisms underlying the relationship between motor competence and physical activity as postulated by Stodden et al. (2008). Moreover, findings indicate that perceived motor competence is important for physical activity promotion during childhood. As such, fostering perceived motor competence should be considered a key outcome in physical education and youth sport programs