2,038 research outputs found
Practical book on medical biology
BIOLOGY MEDICALPRACTICAL BOOKБИОЛОГИЯБИОЛОГИЯ МЕДИЦИНСКАЯПРАКТИЧЕСКИЕ ПОСОБИЯIn the practical book the main divisions and aims of biology are described
2-elementary subgroups of the space Cremona group
We give a sharp bound for orders of elementary abelian 2-groups of birational
automorphisms of rationally connected threefolds
The Kodaira dimension of the moduli of K3 surfaces
The moduli space of polarised K3 surfaces of degree 2d is a quasi-projective
variety of dimension 19. For general d very little has been known about the
Kodaira dimension of these varieties. In this paper we present an almost
complete solution to this problem. Our main result says that this moduli space
is of general type for d>61 and for d=46,50,54,58,60.Comment: 47 page
Properties and Structural Transformations of Mgb2-tapes under the Action of Plasma Shock Waves
The current-carrying properties (
Spin pumping in YIG-Pt structures: the role of the van Hove singularities
Spin pumping by surface and backward volume magnetostatic waves in YIG/Pt
structures is experimentally studied and analyzed. It is shown that at
frequencies corresponding to van Hove singularities in the density of states of
the spin wave spectrum, an increase in the efficiency of electron-magnon
scattering and spin current generation takes place. The obtained results are
important for spin wave-based spintronic devices development
K3-fibered Calabi-Yau threefolds I, the twist map
A construction of Calabi-Yaus as quotients of products of lower-dimensional
spaces in the context of weighted hypersurfaces is discussed, including
desingularisation. The construction leads to Calabi-Yaus which have a fiber
structure, in particular one case has K3 surfaces as fibers. These Calabi-Yaus
are of some interest in connection with Type II -heterotic string dualities in
dimension 4. A section at the end of the paper summarises this for the
non-expert mathematician.Comment: 31 pages LaTeX, 11pt, 2 figures. To appear in International Journal
of Mathematics. On the web at
http://personal-homepages.mis.mpg.de/bhunt/preprints.html , #
Symplectic involutions on deformations of K3^[2]
Let X be a Hyperk\"{a}hler variety deformation equivalent to the Hilbert
square on a K3 surface and let f be an involution preserving the symplectic
form. We prove that the fixed locus of f consists of 28 isolated points and 1
K3 surface, moreover the anti-invariant lattice of the induced involution on
H^2(X,Z) is isomorphic to E_8(-2). Finally we prove that any couple consisting
of one such variety and a symplectic involution on it can be deformed into a
couple consisting of the Hilbert square of a K3 surface and the involution
induced by a Nikulin involution on the K3 surface.Comment: Final version, to appear on Central European Journal of Mathematic
Lagrangian fibrations of holomorphic-symplectic varieties of K3^[n]-type
Let X be a compact Kahler holomorphic-symplectic manifold, which is
deformation equivalent to the Hilbert scheme of length n subschemes of a K3
surface. Let L be a nef line-bundle on X, such that the 2n-th power of c_1(L)
vanishes and c_1(L) is primitive. Assume that the two dimensional subspace
H^{2,0}(X) + H^{0,2}(X), of the second cohomology of X with complex
coefficients, intersects trivially the integral cohomology. We prove that the
linear system of L is base point free and it induces a Lagrangian fibration on
X. In particular, the line-bundle L is effective. A determination of the
semi-group of effective divisor classes on X follows, when X is projective. For
a generic such pair (X,L), not necessarily projective, we show that X is
bimeromorphic to a Tate-Shafarevich twist of a moduli space of stable torsion
sheaves, each with pure one dimensional support, on a projective K3 surface.Comment: 34 pages. v3: Reference [Mat5] and Remark 1.8 added. Incorporated
improvement to the exposition and corrected typos according to the referees
suggestions. To appear in the proceedings of the conference Algebraic and
Complex Geometry, Hannover 201
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