491 research outputs found
On extending actions of groups
Problems of dense and closed extension of actions of compact transformation
groups are solved. The method developed in the paper is applied to problems of
extension of equivariant maps and of construction of equivariant
compactifications
Isovariant extensors and the characterization of equivariant homotopy equivalences
We extend the well-known theorem of James–Segal to the case of an arbitrary family F of conjugacy classes of closed subgroups of a compact Lie group G: a G-map f : X ! Y of metric EquivF-ANE-spaces is a G-homotopy equivalence if and only if it is a weak G-F-homotopy equivalence. The proof is based on the theory of isovariant extensors, which is developed in this paper and enables us to endow F-classifying G-spaces with an additional structure
On Palais universal G-spaces and isovariant absolute extensors
We develop the theory of isovariant absolute extensors which were earlier introduced by R.Palais. The existence of injective objects of the isovariant category is proved and their properties are studied
The Covering Homotopy Extension Problem for Compact Transformation Groups
It is shown that the orbit space of universal (in the sense of Palais) G-spaces classifies G-spaces. Theorems on the extension of covering homotopy for G-spaces and on a homotopy representation of the isovariant category ISOV are proved
Preserving -sets by Dranishnikov's resolution
We prove that Dranishnikov's -dimensional resolution is a UV-divider of Chigogidze's -dimensional resolution .
This fact implies that preserves -sets. A further development of
the concept of UV-dividers permits us to find sufficient conditions for
to be homeomorphic to the N\"{o}beling space or the
universal pseudoboundary . We also obtain some other applications
Spectral multiplicity for powers of weakly mixing automorphisms
We study the behavior of maximal multiplicities for the powers of
a weakly mixing automorphism . For some special infinite set we show the
existence of a weakly mixing rank-one automorphism such that
and for all . Moreover, the cardinality
of the set of spectral multiplicities for is not bounded. We have
and , , . We
also construct another weakly mixing automorphism with the following
properties: for but ,
all powers have homogeneous spectrum, and the set of limit points of
the sequence is infinite
Nucleon Resonances and Quark Structure
A pedagogical review of the past 50 years of study of resonances, leading to
our understanding of the quark content of baryons and mesons. The level of this
review is intended for undergraduates or first-year graduate students. Topics
covered include: the quark structure of the proton as revealed through deep
inelastic scattering; structure functions and what they reveal about proton
structure; and prospects for further studies with new and upgraded facilities,
particularly a proposed electron-ion collider.Comment: 21 pages, 15 figure
Nonpolyhedral proof of the Michael finite-dimensional selection theorem
Предложен новый метод доказательства конечномерной селекционной теоремы Майкла. С его помощью получен ряд новых селекционных теорем
A new approach to calculate the gluon polarization
We derive the Leading-Order master equation to extract the polarized gluon
distribution G(x;Q^2) = x \deltag(x;Q^2) from polarized proton structure
function, g1p(x;Q^2). By using a Laplace-transform technique, we solve the
master equation and derive the polarized gluon distribution inside the proton.
The test of accuracy which are based on our calculations with two different
methods confirms that we achieve to the correct solution for the polarized
gluon distribution. We show that accurate experimental knowledge of g1p(x;Q^2)
in a region of Bjorken x and Q^2, is all that is needed to determine the
polarized gluon distribution in that region. Therefore, to determine the gluon
polarization \deltag /g,we only need to have accurate experimental data on
un-polarized and polarized structure functions (F2p (x;Q^2) and g1p(x;Q^2)).Comment: 12 pages, 5 figure
Influence of the focused ion beam parameters on the etching of planar nanosized multigraphene/SiC field emitters
The equipment of the Collective Usage Center “Nanotechnologies” and the Research and Educational Center "Nanotechnologies" of Southern Federal University was used for this study. This work was funded by Internal grant of Southern Federal University No. VnGr-07/2017-26
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