935 research outputs found
Minimalist design of a robust real-time quantum random number generator
We present a simple and robust construction of a real-time quantum random
number generator (QRNG). Our minimalist approach ensures stable operation of
the device as well as its simple and straightforward hardware implementation as
a stand-alone module. As a source of randomness the device uses measurements of
time intervals between clicks of a single-photon detector. The obtained raw
sequence is then filtered and processed by a deterministic randomness
extractor, which is realized as a look-up table. This enables high speed
on-the-fly processing without the need of extensive computations. The overall
performance of the device is around 1 random bit per detector click, resulting
in 1.2 Mbit/s generation rate in our implementation
Symplectic geometries on supermanifolds
Extension of symplectic geometry on manifolds to the supersymmetric case is
considered. In the even case it leads to the even symplectic geometry (or,
equivalently, to the geometry on supermanifolds endowed with a non-degenerate
Poisson bracket) or to the geometry on an even Fedosov supermanifolds. It is
proven that in the odd case there are two different scalar symplectic
structures (namely, an odd closed differential 2-form and the antibracket)
which can be used for construction of symplectic geometries on supermanifolds.Comment: LaTex, 1o pages, LaTex, changed conten
BRST structure of non-linear superalgebras
In this paper we analyse the structure of the BRST charge of nonlinear
superalgebras. We consider quadratic non-linear superalgebras where a
commutator (in terms of (super) Poisson brackets) of the generators is a
quadratic polynomial of the generators. We find the explicit form of the BRST
charge up to cubic order in Faddeev-Popov ghost fields for arbitrary quadratic
nonlinear superalgebras. We point out the existence of constraints on structure
constants of the superalgebra when the nilpotent BRST charge is quadratic in
Faddeev-Popov ghost fields. The general results are illustrated by simple
examples of superalgebras.Comment: 15 pages, Latex, references added, misprints corrected, comments
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The selection pressure on the neuraminidase gene of influenza viruses isolated in Ukraine from 2009 to 2015
A broad range of naturally occurring antigenic variants of the influenza virus is caused by its rapid evolutionary variability. The survival of viable influenza virus variants occurs through natural selection. The treatment of influenza infection with modern antiviral drugs β neuraminidase (NA) inhibitors β leads to the occurrence of mutations in the NA gene, which thereby result in the emergence of virus resistance to these drugs. The goal of this study was to determine the selection pressure on the NA protein of influenza viruses isolated in Ukraine from 2009 to 2015. The main method for assessing the selection pressure on proteins is to quantify the ratio of substitution rates at nonsynonymous (dN) and synonymous (dS) sites. With the help of this method, we showed that only a few codons in the NA gene were under positive selection resulting in mutations at the following sites: for influenza A viruses of the A(H1N1)pdm09 subtype β site 40, for viruses of the A(H3N2) subtype β sites 93 and 402, for Influenza B viruses of the B/Yamagata lineage β sites 74, 99, and 268, and for the viruses of the B/Victoria lineage β sites 358, 288, and 455. These sites are not associated with the NA active site, transmembrane domain, or the antigenic sites of this protein. We concluded that NA inhibitors are not a significant factor in the process of selection of the influenza viruses in Ukraine because the sites associated with the resistance of influenza viruses to NA inhibitors were not affected by positive selection. This finding could be explained by the limited use of NA inhibitors for the treatment of influenza infections in Ukraine.Β A broad range of naturally occurring antigenic variants of the influenza virus is caused by its rapid evolutionary variability. The survival of viable influenza virus variants occurs through natural selection. The treatment of influenza infection with modern antiviral drugs β neuraminidase (NA) inhibitors β leads to the occurrence of mutations in the NA gene, which thereby result in the emergence of virus resistance to these drugs. The goal of this study was to determine the selection pressure on the NA protein of influenza viruses isolated in Ukraine from 2009 to 2015. The main method for assessing the selection pressure on proteins is to quantify the ratio of substitution rates at nonsynonymous (dN) and synonymous (dS) sites. With the help of this method, we showed that only a few codons in the NA gene were under positive selection resulting in mutations at the following sites: for influenza A viruses of the A(H1N1)pdm09 subtype β site 40, for viruses of the A(H3N2) subtype β sites 93 and 402, for Influenza B viruses of the B/Yamagata lineage β sites 74, 99, and 268, and for the viruses of the B/Victoria lineage β sites 358, 288, and 455. These sites are not associated with the NA active site, transmembrane domain, or the antigenic sites of this protein. We concluded that NA inhibitors are not a significant factor in the process of selection of the influenza viruses in Ukraine because the sites associated with the resistance of influenza viruses to NA inhibitors were not affected by positive selection. This finding could be explained by the limited use of NA inhibitors for the treatment of influenza infections in Ukraine.
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