117 research outputs found
Solar activity beyond the disk and variations of the cosmic ray gradient
Part of galactic cosmic rays (CR) observed near the Earth and on the Earth come from beyond-disk regions of circumsolar space. But CR of those energies which undergo substantial modulation cover too large a path across the lines of force of the interplanetary magnetic field (IMF) in order that they could provide an effective transfer of information about beyond-disk solar activity. And if it is still possible, the most probable channel for transferring such information must be a neutral layer of heliomagnetosphere in which the transverse CR transport is facilitated by their drift in an inhomogeneous magnetic field. A simple diffusion model for an expected CR variation in a neutral layer near the Earth is discussed. It is of importance that variations of the CR gradient are not at all always accompanied by considerable variations of IMF and solar wind velocity at the point of observation
The Phantom Bounce: A New Oscillating Cosmology
An oscillating universe cycles through a series of expansions and
contractions. We propose a model in which ``phantom'' energy with
grows rapidly and dominates the late-time expanding phase. The universe's
energy density is so large that the effects of quantum gravity are important at
both the beginning and the end of each expansion (or contraction). The bounce
can be caused by high energy modifications to the Friedmann equation, which
make the cosmology nonsingular. The classic black hole overproduction of
oscillating universes is resolved due to their destruction by the phantom
energy.Comment: Four pages, one figure. V3: version to appear in JCA
Correlation effects during liquid infiltration into hydrophobic nanoporous mediums
Correlation effects arising during liquid infiltration into hydrophobic
porous medium are considered. On the basis of these effects a mechanism of
energy absorption at filling porous medium by nonwetting liquid is suggested.
In accordance with this mechanism, the absorption of mechanical energy is a
result expenditure of energy for the formation of menisci in the pores on the
shell of the infinite cluster and expenditure of energy for the formation of
liquid-porous medium interface in the pores belonging to the infinite cluster
of filled pores. It was found that in dependences on the porosity and,
consequently, in dependences on the number of filled pores neighbors, the
thermal effect of filling can be either positive or negative and the cycle of
infiltration-defiltration can be closed with full outflow of liquid. It can
occur under certain relation between percolation properties of porous medium
and the energy characteristics of the liquid-porous medium interface and the
liquid-gas interface. It is shown that a consecutive account of these
correlation effects and percolation properties of the pores space during
infiltration allow to describe all experimental data under discussion
Space weather and space anomalies
A large database of anomalies, registered by 220 satellites in different orbits over the period 1971-1994 has been compiled. For the first time, data from 49 Russian Kosmos satellites have been included in a statistical analysis. The database also contains a large set of daily and hourly space weather parameters. A series of statistical analyses made it possible to quantify, for different satellite orbits, space weather conditions on the days characterized by anomaly occurrences. In particular, very intense fluxes (>1000 pfu at energy >10 MeV) of solar protons are linked to anomalies registered by satellites in high-altitude (>15000 km), near-polar (inclination >55°) orbits typical for navigation satellites, such as those used in the GPS network, NAVSTAR, etc. (the rate of anomalies increases by a factor ~20), and to a much smaller extent to anomalies in geostationary orbits, (they increase by a factor ~4). Direct and indirect connections between anomaly occurrence and geomagnetic perturbations are also discussed
Identification of Genovariants of Yersinia pestis Strains Belonging to Main Subspecies Using PCR with Hybridization-Fluorescent Registration of Results
For the first time ever developed has been the method of identification of genovariants in Yersinia pestis strains belonging to the main subspecies using PCR with hybridization-fluorescent registration of results. A complex of DNA-targets, the most of which are newly detected ones, have been utilized to differentiate between genovariants of antique (0.ANT, 1.ANT, 2.ANT, 4.ANT), medievalis (2.MED, 2.MED0), and orientalis (1.ORI) biovars. Application of these targets in PCR with hybridization-fluorescent registration of results provides for a rapid, effective and reliable classifying of the strains of the genovariants, circulating in various geographical regions. Efficacy of the method has been validated via analysis of 110 Y. pestis strains, isolated in the territory of the Russian Federation, neighboring countries and beyond, including 37 strains of antique, 53 strains of medievalis, and 20 strains of orientalis biovars
Gamma Ray Bursts from the Evolved Galactic Nuclei
A new cosmological scenario for the origin of gamma ray bursts (GRBs) is
proposed. In our scenario, a highly evolved central core in the dense galactic
nucleus is formed containing a subsystem of compact stellar remnants (CSRs),
such as neutron stars and black holes. Those subsystems result from the
dynamical evolution of dense central stellar clusters in the galactic nuclei
through merging of stars, thereby forming (as has been realized by many
authors) the short-living massive stars and then CSRs. We estimate the rate of
random CSR collisions in the evolved galactic nuclei by taking into account,
similar to Quinlan & Shapiro (1987), the dissipative encounters of CSRs, mainly
due to radiative losses of gravitational waves, which results in the formation
of intermediate short-living binaries, with further coalescence of the
companions to produce GRBs. We also consider how the possible presence of a
central supermassive black hole, formed in a highly evolved galactic nucleus,
influences the CSR binary formation. This scenario does not postulate ad hoc a
required number of tight binary neutron stars in the galaxies. Instead, it
gives, for the most realistic parameters of the evolved nuclei, the expected
rate of GRBs consistent with the observed one, thereby explaining the GRB
appearance in a natural way of the dynamical evolution of galactic nuclei. In
addition, this scenario provides an opportunity for a cosmological GRB
recurrence, previously considered to be a distinctive feature of GRBs of a
local origin only. We also discuss some other observational tests of the
proposed scenario.Comment: 25 pages, LATEX, uses aasms4.sty, accepted by Ap
Phantom scalar emission in the Kerr black hole spacetime
We study the absorption probability and Hawking radiation spectra of a
phantom scalar field in the Kerr black hole spacetime. We find that the
presence of the negative kinetic energy terms modifies the standard results in
the greybody factor, super-radiance and Hawking radiation. Comparing with the
usual scalar particle, the phantom scalar emission is enhanced in the black
hole spacetime.Comment: 11 pages, 6 figures, a revised version accepted for publication in
CQ
Caspian Sandy Natural Focus: Phylogenetic History and Origin of <i>Yersinia pestis</i> Strains
The purpose of the work was to analyze the phylogenetic relations and origin of Yersinia pestis strains isolated in different periods of epizootic activity of the Caspian sandy natural focus (CSNF) of plague in the XX–XXI centuries.Materials and methods. We used 40 Y. pestis strains from CSNF and adjacent plague foci, isolated in 1922–2015. Carried out was whole genome sequencing of 19 Y. pestis strains from CSNF. Phylogenetic analysis was performed using whole genome SNP analysis based on 1914 identified SNPs. The search for marker SNPs was conducted using the Snippy 4.6 software. The phylogenetic tree was constructed using the Maximum Likelihood algorithm, the GTR nucleotide substitution model.Results and discussion. The whole genome SNP analysis has revealed that Y. pestis strains of the medieval biovar from CSNF belong to 2.MED1 phylogenetic lineage and fall into two major branches. One of them circulated in the focus in the first half of the XX century, and the other – in the second half of the XX – early XXI centuries. It is shown that strains of the first branch were the cause of outbreaks and individual cases of plague in the CSNF in the first half of the XX century. They are closely related to strains from the Caspian North-Western steppe and Volga-Ural sandy natural plague foci, which caused numerous outbreaks with high mortality rate in the same period. Y. pestis strains from the CSNF of the second half of the XX and early XXI centuries belong to the second phylogenetic branch of the 2.MED1 line, at the node of which the strains from the Northern Aral Sea region of 1945 lay. The latter were the predecessors of all strains isolated in the CSNF after a long inter-epizootic period that occurred in the middle of the XX century. There can also be traced a genetic relation between the strains from CSNF and the Dagestan plain-foothill focus
Variability of <i>pgm</i>‑Region Genes in <i>Yersinia pestis</i> Strains from the Caspian Sandy and Adjacent Plague Foci
The aim of the study was to compare the nucleotide sequences of pgm‑region genes in Yersinia pestis strains isolated on the territory of the Caspian sandy and adjacent plague foci in 1925–2015. Materials and methods. 65 Y. pestis strains from the Caspian sandy and adjacent plague foci were used in the work. DNA isolation was performed using the PureLink Genomic DNA Mini Kit. Whole genome sequencing was conducted in Ion S5 XL System (Thermo Fischer Scientific). Data processing was carried out using Ion Torrent Suite software package 3.4.2 and NewblerGS Assembler 2.6. To compare the obtained sequences with the NCBI GenBank database, the Blast algorithm was used. The phylogenetic analysis was performed according to the data of whole genome SNP analysis based on 1183 identified SNPs. The search for marker SNPs was performed using the Snippy 4.6 program. The phylogenetic tree was constructed using the Maximum Likelihood algorithm, the GTR nucleotide substitution model. Results and discussion. The nucleotide sequences of pgm‑region genes of 65 Y. pestis strains from the Caspian sandy and adjacent plague foci have been assessed. Single nucleotide substitutions have been identified in Y. pestis strains from the Caspian sandy and Kobystan plain-foothill foci in the hmsR, astB, ybtS, ypo1944, ypo1943, ypo1936 genes, as well as a deletion of 5 bp in the ypo1945 gene, which is characteristic of strains of one of the phylogenetic lines of Y. pestis from the foci of Caucasus and Transcaucasia, isolated in 1968–2001. The data obtained can be used to differentiate Y. pestis strains from the Caspian sandy focus, as well as to establish the directions of microevolution of the plague pathogen in this region and adjacent foci
Detection of symptom-related coronary arteries in patients with coronary artery disease using real-time three-dimensional stress echocardiography with adenosine triphosphate
Aim 1) To develop normative values of global and regional left ventricular longitudinal deformation (LVLD) during real time three-dimensional stress echocardiography with adenosine triphosphate (ATP) and utilization of automated function imaging technology (4D Stress-Echo + LVLD with ATP); 2) to compare the effectiveness of detection of symptom-related coronary arteries during 4D Stress-Echo with ATP using: a) traditional visual assessment of regional myocardial contractility and b) step-by-step analysis of segmental LVLD.Material and Methods 15 healthy subjects and 32 patients with coronary artery disease (CAD) were examined after coronary angiography. All individuals underwent 4D Stress-Echo + LVLD with ATP (Vivid E95, General Electric).Results The normative values of global LVLD at three stages of the pharmacological stress-test (before, during and after ATP infusion) were –19.5 (95% CI: -20.4 – -19.0), –21.6 (95% CI: -22.8 – -20.4) and –19.5 (95% CI: -20.3 – -18.6), respectively; the values of LVLD in each of the 17 segments of left ventricular myocardium in healthy subjects were also determined. In patients with CAD visual control of contractility during stress test revealed dynamic decrease in local thickening of the myocardium, appearance of new zones of contractility disorders and expansion of previously noted in 31.2% of cases, while analysis of deformation detected the appearance of new zones of deformation disturbances and expansion of previously found – in 68.7% (р = 0.0055). Stress-induced worsening of myocardial deformation during ATP infusion in the zones of blood supply of left anterior descending coronary artery, circumflex artery and right coronary artery (with presence of hemodynamically significant stenoses and occlusions detected during coronary angiography) were found in 28.0, 77.7 and 65.2% respectively (р1-3 = 0.0194; р1-2 = 0.0019; р2-3 = 0.2864).Conclusion The normal values of global and segmental LVLD for each stage of 4D Stress-Echo + LVLD with ATP were determined. 4D Stress-Echo + LVLD with ATP can significantly increase the effectiveness of symptom-related coronary arteries identification in patients with CAD in comparison with traditional Stress-Echo with visual assessment of local myocardial contractility
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