12 research outputs found

    Homotopy types of stabilizers and orbits of Morse functions on surfaces

    Full text link
    Let MM be a smooth compact surface, orientable or not, with boundary or without it, PP either the real line R1R^1 or the circle S1S^1, and Diff(M)Diff(M) the group of diffeomorphisms of MM acting on C∞(M,P)C^{\infty}(M,P) by the rule h⋅f↦f∘h−1h\cdot f\mapsto f \circ h^{-1}, where h∈Diff(M)h\in Diff(M) and f∈C∞(M,P)f \in C^{\infty}(M,P). Let f:M→Pf:M \to P be a Morse function and O(f)O(f) be the orbit of ff under this action. We prove that πkO(f)=πkM\pi_k O(f)=\pi_k M for k≥3k\geq 3, and π2O(f)=0\pi_2 O(f)=0 except for few cases. In particular, O(f)O(f) is aspherical, provided so is MM. Moreover, π1O(f)\pi_1 O(f) is an extension of a finitely generated free abelian group with a (finite) subgroup of the group of automorphisms of the Reeb graph of ff. We also give a complete proof of the fact that the orbit O(f)O(f) is tame Frechet submanifold of C∞(M,P)C^{\infty}(M,P) of finite codimension, and that the projection Diff(M)→O(f)Diff(M) \to O(f) is a principal locally trivial S(f)S(f)-fibration.Comment: 49 pages, 8 figures. This version includes the proof of the fact that the orbits of a finite codimension of tame action of tame Lie group on tame Frechet manifold is a tame Frechet manifold itsel

    Peculiarities of forming radioactive contamination of higher aquatic plants from Kyiv reservoir

    No full text
    Peculiarities of forming radioactive contamination of higher aquatic plants from Kyiv reservoir in 2010 was studied. For the first time the levels of content 137Cs and 90Sr in plants from different parts of reservoir was ana-lyzed. Content of 137Cs in plants was registered on the level from 5 to 588 Bq/kg, 90Sr – from 0,5 to 50 Bq/kg. Levels of radioactive contamination of higher aquatic plants depended on peculiarities of radionuclides migra-tion in water area of the reservoir with water masses
    corecore