88 research outputs found
Analysis of antigenic relationships among influenza virus strains using a taxonomic cluster procedure. Comparison of three kinds of antibody preparations.
Hemagglutination inhibiting (HI) monoclonal antibody preparations (MA) were raised against six influenza A (H3N2) strains from the period 1977-1982. Twenty-three hybridomas were selected and titrated in HI assays against these strains and against 18 influenza A (H3N2) viruses isolated in The Netherlands during the seasons 1981-1982 and 1982-1983. Similar HI tests were performed with conventional post-infection ferret antisera and with ferret antisera adsorbed with heterologous strains of influenza A (H3N2) virus. The resulting serological data were subjected to a computerized taxonomic cluster procedure based on the Euclidean distance between viruses. With respect to the degree of separation between clusters the unadsorbed ferret antisera were inferior to the adsorbed antisera whereas the MA were superior to both. Our results demonstrate that computer programs based on numerical taxonomy can be helpful in processing large numbers of serological data and that MA are indispensable in epidemiological and diagnostic influenza studies
The peak-flux of GRB 221009A measured with GRBAlpha
The brightest gamma-ray burst ever observed, long-duration GRB 221009A, was
detected by GRBAlpha nano-satellite without saturation. We present light curves
of the prompt emission in 13 energy bands, from 80 keV to 950 keV, and perform
a spectral analysis to calculate the peak flux and peak isotropic-equivalent
luminosity. Since the satellite's attitude information is not available for the
time of this GRB, more than 200 incident directions were probed in order to
find the median luminosity and its systematic uncertainty. We found that the
peak flux in the keV range (observer frame) was
ph cms or
erg cms
and the fluence in the same energy range of the first GRB episode lasting 300
s, which was observable by GRBAlpha, was erg
cm or erg cm for
the extrapolated range of keV. We infer the isotropic-equivalent
released energy of the first GRB episode to be
erg in the
keV band (rest frame at ). The peak isotropic-equivalent luminosity in
the keV range (rest frame) was
erg s and the
bolometric peak isotropic-equivalent luminosity was
erg s (4 s
scale) in the keV range (rest frame). The peak emitted energy is
keV. Our measurement of
is consistent with the Yonetoku relation. It is
possible that, due to the spectral evolution of this GRB and orientation of
GRBAlpha at the peak time, the true values of peak flux, fluence,
, and are even higher. [abridged]Comment: 7 pages, 7 figures, 1 table, accepted for publication in Astronomy &
Astrophysic
Immuno-Regulating Peptides, I. Synthesis and Structure-Activity Relationships of Thymopentin Analogs
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