373 research outputs found
Extraction of Inclusive Cross Sections of Charged Pions Produced in Proton-Proton Collisions from the NA49 Experiment
A survey of backward proton and pion production in p+C interactions at beam momenta from 1 to 400 GeV/c
New data on proton and pion production in p+C interactions from the CERN PS
and SPS accelerators are used in conjunction with other available data sets to
perform a comprehensive survey of backward hadronic cross sections. This survey
covers the complete backward hemisphere in the range of lab angles from 10 to
180 degrees, from 0.2 to 1.4 GeV/c in lab momentum and from 1 to 400 GeV/c in
projectile momentum. Using the constraints of continuity and smoothness of the
angular, momentum and energy dependences a consistent description of the
inclusive cross sections is established which allows the control of the
internal consistency of the nineteen available data sets.Comment: 52 pages 47 figure
Serological monitoring of avian influenza and Newcastle disease in the Russian Federation in 2020
Within the framework of the Rosselkhoznadzor measures aimed at control of highly dangerous diseases and development of timely recommendations for disease prevention and control, 36,986 serum samples to be tested for the presence of avian influenza virus antibodies and 30,325 serum samples to be tested for the presence of Newcastle disease virus antibodies were submitted to the FGBI “ARRIAH” Reference Laboratory for Avian Viral Diseases in 2020. The samples were collected from domestic, wild and synanthropic birds in 60 Subjects of the Russian Federation. As a result of the laboratory diagnosis, antibodies against type A influenza virus were found in vaccinated chickens from two poultry farms in the Primorsky Krai. Typing of sample sera using hemagglutination inhibition test showed that the detected antibodies were specific to the haemagglutinin subtype of the vaccine antigen (A/H9). Antibodies to the H9 subtype avian influenza virus were detected in sera of non-vaccinated geese from two poultry farms in the Kurgan Oblast and from one poultry farm in the Republic of Bashkortostan. As for the backyards where scheduled vaccination against avian influenza A/H5 is carried out, a low level of immunity was seen in the Republics of Adygea and Chechnya (0 and 15%, respectively), while a high immunity level was observed in the Rostov Oblast (74%). High seroprevalence of Newcastle disease virus was found in adult poultry in indoor industrial farms, which was associated with mass vaccination against the disease. In broiler chickens, post-vaccination antibodies were observed, on average, in 44% of the tested sera samples. The antibodies against Newcastle disease virus and avian influenza virus subtype H5 detected in wild and synanthropic birds indicate the circulation of these viruses in the Russian Federation. The insufficient level of post-vaccination antibodies suggests that the risk of epidemic among poultry in industrial poultry farms and backyards remains
Testing of chickens experimentally infected with A/H9N2 avian influenza virus isolates for their immune responses
Data on tests of chickens for their immune responses to infection with low pathogenic А/Н9N2 avian influenza virus isolates belonging to Y-280 and G1 genetic lines are presented in the paper. CD4⁺/CD8⁺ ratios were determined with flow cytometry for initial immune status examination and for detection of apparent immune system disorders. Quantitative analysis of peripheral blood lymphocyte subpopulations in chickens revealed changes characteristic of the immune suppression. Analysis of dynamics of T- and B-lymphocyte levels in blood of the infected chickens revealed decrease in relative T-lymphocyte counts and increase in relative B-lymphocyte counts. T-lymphocyte subpopulation composition expressed as CD4⁺/CD8⁺ ratio (%) changed after the infection: CD4⁺ cell proportion was found to decrease whereas CD8⁺ cell proportion increased. According to literature data, immune response activated by vaccination induces the reverse dynamics towards to increase in CD4⁺/CD8⁺ ratio. Both cell-mediated immunity and humoral immunity play role in development of the immune response in chickens infected with avian influenza viruses. Apparent humoral immune response was detected by serological tests of sera taken from chickens on day 14 after infection. Mean specific anti-A/H9N2 AIV antibody titre in all groups of test chickens infected with low pathogenic avian influenza virus isolates was higher than 6 log₂ . High level of specific antibodies to avian influenza virus was indicative of postvaccinal humoral immune response development
Infectious bursal disease virus: identification of the novel genetic group and reassortant viruses
The results of the phylogenic analysis of the nucleotide sequence of the IBDV A and B genome segments have been presented. Traditionally the IBDV isolates are classified based on the phylogenic analysis of the hypervariable region of the VP2 gene. The analysis of the VP2 gene segments of the isolates detected in the Russian Federation demonstrated that most of them belong to the genetic group comprising highly virulent IBDV isolates. However, not all isolates belonging to one genetic group have the same phenotypic characteristics. This is related to the fact that the virulence is determined not only based on the characteristics of the VP2 gene (A segment) but on the characteristics of the VP1 gene (B segment) as well. The IBDV genome segmentation allows formation of reassortant viruses which can be identified as a result of the genome segment analysis. The phylogenic analysis of the nucleotide sequences of VP2 and VP1 genes of 28 IBDV isolates detected at RF, Ukrainian and Kazakh poultry establishments in 2007 and 2019 showed that 15 of them are reassortant viruses. Different combinations of the genome segments have been identified among these reassortant viruses. Detection of different combinations of IBDV genome segments is indicative of the fact that the heterogeneous virus population circulates on the poultry farms. Pathogenicity studies of the three IBDV isolates showed that the most virulent was an isolate having two genome segments characteristic of the highly virulent virus. Two reassortant viruses having only one genome segment A or B, characteristic of the infectious bursal disease, demonstrated less pronounced virulent properties
Phase-space dependence of particle-ratio fluctuations in Pb+Pb collisions from 20A to 158A GeV beam energy
A novel approach, the identity method, was used for particle identification
and the study of fluctuations of particle yield ratios in Pb+Pb collisions at
the CERN Super Proton Synchrotron (SPS). This procedure allows to unfold the
moments of the unknown multiplicity distributions of protons (p), kaons (K),
pions () and electrons (e). Using these moments the excitation function of
the fluctuation measure [A,B] was measured, with A and
B denoting different particle types. The obtained energy dependence of
agrees with previously published NA49 results on the related
measure . Moreover, was found to depend
on the phase space coverage for [K,p] and [K,] pairs. This feature most
likely explains the reported differences between measurements of NA49 and those
of STAR in central Au+Au collisions
Measurement of event-by-event transverse momentum and multiplicity fluctuations using strongly intensive measures and in nucleus-nucleus collisions at the CERN Super Proton Synchrotron
Results from the NA49 experiment at the CERN SPS are presented on
event-by-event transverse momentum and multiplicity fluctuations of charged
particles, produced at forward rapidities in central Pb+Pb interactions at beam
momenta 20, 30, 40, 80, and 158 GeV/c, as well as in systems of
different size (, C+C, Si+Si, and Pb+Pb) at 158 GeV/c. This publication
extends the previous NA49 measurements of the strongly intensive measure
by a study of the recently proposed strongly intensive measures of
fluctuations and . In the explored kinematic
region transverse momentum and multiplicity fluctuations show no significant
energy dependence in the SPS energy range. However, a remarkable system size
dependence is observed for both and , with the
largest values measured in peripheral Pb+Pb interactions. The results are
compared with NA61/SHINE measurements in collisions, as well as with
predictions of the UrQMD and EPOS models.Comment: 12 pages, 14 figures, to be submitted to PR
Production of deuterium, tritium, and He in central Pb+Pb collisions at 20A, 30A, 40A, 80A, and 158A GeV at the CERN SPS
Production of , , and He nuclei in central Pb+Pb interactions was
studied at five collision energies ( 6.3, 7.6, 8.8, 12.3, and
17.3 GeV) with the NA49 detector at the CERN SPS. Transverse momentum spectra,
rapidity distributions, and particle ratios were measured. Yields are compared
to predictions of statistical models. Phase-space distributions of light nuclei
are discussed and compared to those of protons in the context of a coalescence
approach. The coalescence parameters and , as well as coalescence
radii for and He were determined as a function of transverse mass at
all energies.Comment: 22 pages, 29 figures, 8 tables, for submission to Phys. Rev.
Status and Plans of the NA49 pp and pA Programme
Short memorandum in context of the presentation of the status and plans of the NA49 pp and pA Programme at the SPSC-83 open session
Antideuteron and deuteron production in mid-central Pb+Pb collisions at 158 GeV
Production of deuterons and antideuterons was studied by the NA49 experiment
in the 23.5% most central Pb+Pb collisions at the top SPS energy of
=17.3 GeV. Invariant yields for and were measured
as a function of centrality in the center-of-mass rapidity range .
Results for together with previously published
measurements are discussed in the context of the coalescence model. The
coalescence parameters were deduced as a function of transverse momentum
and collision centrality.Comment: 9 figure
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