16 research outputs found
Algebraic description of spacetime foam
A mathematical formalism for treating spacetime topology as a quantum
observable is provided. We describe spacetime foam entirely in algebraic terms.
To implement the correspondence principle we express the classical spacetime
manifold of general relativity and the commutative coordinates of its events by
means of appropriate limit constructions.Comment: 34 pages, LaTeX2e, the section concerning classical spacetimes in the
limit essentially correcte
Spacetime topology from the tomographic histories approach I: Non-relativistic Case
The tomographic histories approach is presented. As an inverse problem, we
recover in an operational way the effective topology of the extended
configuration space of a system. This means that from a series of experiments
we get a set of points corresponding to events. The difference between
effective and actual topology is drawn. We deduce the topology of the extended
configuration space of a non-relativistic system, using certain concepts from
the consistent histories approach to Quantum Mechanics, such as the notion of a
record. A few remarks about the case of a relativistic system, preparing the
ground for a forthcoming paper sequel to this, are made in the end.Comment: 19 pages, slight chang in title and corrected typos in second
version. To appear to a special proceedings issue (Glafka 2004) of the
International Journal of Theoretical Physic
Peculiarities of the influenza viruses circulation and their properties during 2018-2019 epidemic season in Russia and countries of the Northern Hemisphere
Objective. To identify the drift variability of influenza viruses during the period of epidemic rise in the incidence of acute respiratory viral infections in the period 2018-2019. The biological and molecular-genetic properties of epidemic strains isolated in certain territories of the Russian Federation were studied and compared with data from the countries of the Northern Hemisphere. Materials and methods. A range of laboratory diagnostic methods has been applied, including immune fluorescence, RT-PCR, sequencing, methods for determining sensitivity to influenza drugs and receptor specificity. Results and discussion. The proportion of influenza viruses was as follows: A (H1N1) pdm09 - 53 %, A (H3N2) - 46 %, B - about 1 %. Cases of severe acute respiratory infections have most often been associated with influenza A(H1N1) pdm09 virus. According to antigenic properties, isolated strains corresponded to the properties of vaccine viruses (A/Michigan/45/2015 - by 99.6 % and A/Singapore INFIMH-16-0019/2016 - by 86 %). The heterogeneity of influenza A virus strains population was revealed as regards individual mutations in hemaglutinin. The influenza B virus population was equally represented by both evolutionary lines (B/Victoria and B/Yamagata-like). Receptor specificity was favorable for the course and outcome of the disease. Among 70 studied epidemic strains, no strains resistant to anti-neuraminidase drugs, oseltamivir and zanamivir, were detected. The article presents WHO recommendations on the composition of influenza vaccines for the countries of the Northern Hemisphere for 2019-2020, provides data on cases of human infection with avian influenza viruses A(H5N1), A(H5N6), A(H7N9) and A(H9N2)