379 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
Have Pentaquark States Been seen?
The status of the search for pentaquark baryons is reviewed in light of new
results from the first two dedicated experiments from CLAS at Jefferson Lab and
of new analyses from several laboratories on the . Evidence for
and against two heavier pentaquark states is also discussed.Comment: Added some references, corrected typo
Spin and orbital angular momentum of the proton
Since the announcement of the proton spin crisis by the European Muon
Collaboration there has been considerable progress in unravelling the
distribution of spin and orbital angular momentum within the proton. We review
the current status of the problem, showing that not only have strong upper
limits have been placed on the amount of polarized glue in the proton but that
the experimental determination of the spin content has become much more
precise. It is now clear that the origin of the discrepancy between experiment
and the naive expectation of the fraction of spin carried by the quarks and
anti-quarks in the proton lies in the non-perturbative structure of the proton.
We explain how the features expected in a modern, relativistic and chirally
symmetric description of nucleon structure naturally explain the current data.
The consequences of this explanation for the presence of orbital angular
momentum on quarks and gluons is reviewed and comparison made with recent
results from lattice QCD and experimental data.Comment: Lectures at Aligarh University (4th DAE-BRNS Workshop on Hadron
Physics, Feb 18-21, 200
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
The Assessment of Light Environment with the First Generation Leds
The article describes experimental studies on the effectiveness of lighting installations (LI) with light-emitting diodes (LEDs). It is established that LED-based lighting does not cause a negative impact on the organ of vision and the human body as a whole. The changes in the functional parameters of the organ of sight, which occur during the visual performance has the corresponding limits of physiological fluctuations and are reversible. The integral indicators of the efficiency of LED-based lighting were estimated. The practical significance of the results was shown
Efficacy of liposomal dosage forms and hyperosmolar salines in experimental pharmacotherapy of acute lung injury
Hypertonic sodium chloride solutions and liposomal drugs with pulmotropic effect are of great interest for the treatment of acute lung injury (ALI). For the experiment, liposomes with dexamethasone, N-acetylcysteine (NAC), aprotinin and dye Cyanine-7 (Cy-7) were obtained. A liposome analysis was performed by means of spectrophotometry. ALI was modeled in rats by the administration of the damaging agents into the trachea. All the studied therapeutic agents increased the survival rate of the laboratory animals with ALI. The most effective experimental agent was liposomal dexamethason
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
Effect of thickness on the piezoelectric properties of LiNbO3 films
The results were obtained using the equipment of Research and Education Center and the Center of collective use “Nanotechnology” of Southern Federal University
Study of growth temperature effect on wetting layer during In/GaAs droplet epitaxy
This work was supported by the Russian Science Foundation Grant No. 15-19-10006. The results were obtained using the equipment of the Research and Education Center and Center for Collective Use "Nanotechnologies" of Southern Federal University
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