Axions with an energy of 8.4 keV emitted in the
М
1 transition in
169
Tm nuclei in the Sun are sought in the
→
169
Tm* →
(8.4 keV) reaction of resonant absorption by
169
Tm nuclei on the Earth using ...a
thulium garnet crystal as a bolometric detector. The flux of monochromatic 8.4‑keV axions has been calculated. New constraints on the axion–nucleon coupling constants have been obtained and, as a result, new upper bounds on the axion mass
eV and
eV have been obtained at 90% C.L. in the KSVZ and DFSZ models, respectively.
Precise measurement of beta spectra was always of great importance in some fundamental problems, including those of neutrino physics. The results obtained by measuring the spectrum of a
Ce–
Pr source ...with setups of two types to a precision substantially improved in relation to earlier investigations are presented. The correctness of a theoretical fit is tested using the shape of the
Pr (0
)
Nd (1
) allowed beta transition.
Summary Enzyme linked immunosorbent assay (ELISA) has been widely used to measure antibody titers for evaluating the immunogenicity of a vaccine. However, there is as yet no generally accepted way of ...expressing the ELISA results in the case of experimental vaccines, since there is usually no uniform standard. Both end point and single dilution methods have significant disadvantages. In this paper, we obtained reproducible data with fewer dilutions of samples by addition of serially diluted standard serum to each ELISA plate. Since this ELISA method gives reliable antibody titer with less labor than other methods, it can strongly support vaccine development.
The resonant excitation of the
83
Kr first excited nuclear level (
E
= 9.4 keV) by solar axions whose fluxes depend on the axion–electron coupling constant
g
Ae
is sought. The γ- and X-ray photons ...and the conversion and Auger electrons from the excited-level relaxation are detected with a gas proportional counter of a low-background detector in the underground Baksan Neutrino Observatory (Institute for Nuclear Research, Russian Academy of Sciences). As a result, a new constraint
≤ 1.50 × 10
–17
(90% C.L.) has been obtained for the axion–electron and axion–nucleon coupling constants, which corresponds to new constraints on the axion mass
m
A
≤ 320 eV and
m
A
≤ 4.6 eV in the KSVZ and DFSZ axion models, respectively.
Resonance excitation of the
83
Kr first nuclear level (
E
= 9.4 keV) by solar axions formed via the Primakoff mechanism is sought. The γ- and X-ray photons and the conversion and Auger electrons ...arising from the excited-level relaxation are detected with a gas proportional counter of a low-background detector in the underground Baksan Neutrino Observatory. The following experimental constraint is obtained for the product of the axion–photon coupling constant and the axion mass:|
g
A
γ
×
m
A
| ≤ 6.3 × 10
-17
In the framework of the hadronic-axion model, this corresponds to a new axion-mass constraint of
m
A
≤ 12.7 eV at 95% C.L.
A search for resonant absorption of solar axions by
169
Tm
nuclei was carried out. A newly developed approach involving low-background cryogenic bolometer based on
Tm
3
Al
5
O
12
crystal was used ...that allowed for significant improvement of sensitivity in comparison with previous
169
Tm
based experiments. The measurements performed with 8.18 g crystal during 6.6 days exposure yielded the following limits on axion couplings:
|
g
A
γ
(
g
AN
0
+
g
AN
3
)
≤
1.44
×
10
-
14
GeV
-
1
and
|
g
Ae
(
g
AN
0
+
g
AN
3
)
≤
2.81
×
10
-
16
.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Mosquito stage malaria vaccines are designed to induce an immune response in the human host that will block the parasite's growth in the mosquito and consequently block transmission of the parasite. ...A mosquito membrane-feeding assay (MFA) is used to test transmission-blocking activity (TBA), but in this technique cannot accommodate many samples. A clear understanding of the relationship between antibody levels and TBA may allow ELISA determinations to be used to predict TBA and assist in planning vaccine development.
Rabbit anti-Pfs25 sera and monkey anti-Pvs25 sera were generated and the antibody titers were determined by a standardized ELISA. The biological activity of the same sera was tested by MFA using Plasmodium gametocytes (cultured Plasmodium falciparum or Plasmodium vivax from malaria patients) and Anopheles mosquitoes.
Anti-Pfs25 and anti-Pvs25 sera showed that ELISA antibody units correlate with the percent reduction in the oocyst density per mosquito (Spearman Rank correlations: 0.934 and 0.616, respectively), and fit a hyperbolic curve when percent reduction in oocyst density is plotted against antibody units of the tested sample. Antibody levels also correlated with the number of mosquitoes that failed to become infected, and this proportion can be calculated from the reduction in oocyst numbers and the distribution of oocysts per infected mosquito in control group.
ELISA data may be used as a surrogate for the MFA to evaluate transmission-blocking vaccine efficacy. This will facilitate the evaluation of transmission-blocking vaccines and implementation of this malaria control strategy.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
We discuss the physics case for and the concept of a medium-scale axion helioscope with sensitivities in the axion-photon coupling a few times better than CERN Axion Solar Telescope (CAST). Search ...for an axion-like particle with these couplings is motivated by several persistent astrophysical anomalies. We present early conceptual design, existing infrastructure, projected sensitivity and timeline of such a helioscope (Troitsk Axion Solar Telescope Experiment, TASTE) to be constructed in the Institute for Nuclear Research, Troitsk, Russia. The proposed instrument may be also used for the search of dark-matter halo axions.
Abstract
Deterioration of the operation parameters of p-type Si surface-barrier detector and Si(Li) p-i-n detector upon irradiation by alpha-particles was investigated. The detectors were irradiated ...at room temperature up to a total number of the registered α-particles
N
α
equal to 6 × 10
9
. Prolonged irradiation has resulted in a deterioration of the detectors energy resolution ability and it was found that the increase of α-peaks broadening can be described by a linear function of
N
α
with a slope Δσ/Δ
N
α
∼ (1.4–1.8) × 10
–9
keV/α for both detectors. Resolution deterioration was associated with the increase of the detectors leakage current, which proceeds linearly with the number of absorbed α-particles with the slope ΔI/Δ
Nα
∼ (7-17) × 10
-17
A/α. The increase of the detectors reverse current was related with appearance of radiation-induced defect level at 0.56 eV above the valence band.
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