597 research outputs found
Variations of cosmic rays according to the data of interplanetary probes Zond-3 and Venus-2
Cosmic ray intensity variation measured by Zond 3 and Venus 2 interplanetary probe
Primary chemical composition from simultaneous recording of muons induced cascades and accompanying muon group underground
A new method to estimate the mean atomic number of primary cosmic rays in energy range 10 to the 3rd power to 10 to the 5th power Gev/nucleon is suggested. The Baksan underground scintillation telescope data are used for this analysis. The results of 7500 h run of this experiment are presented
Angular distribution of muons produced by cosmic ray neutrinos in rock
Measurement of the upgoing muons flux, produced by cosmic ray neutrinos is aiming at: (1) search for neutrino oscillation; (2); search for extraterrestrial neutrinos from local sources; and (3); search for any hypothetical neutral penetrating radiation different from neutrinos. Experimental data of the Baksan underground telescope on intensity of upward muons for three years of living time, was analyzed having in mind mainly neutrino oscillation
Interconversion of Anthozoa GFP-like fluorescent and non-fluorescent proteins by mutagenesis
BACKGROUND: Within the family of green fluorescent protein (GFP) homologs, one can mark two main groups, specifically, fluorescent proteins (FPs) and non-fluorescent or chromoproteins (CPs). Structural background of differences between FPs and CPs are poorly understood to date. RESULTS: Here, we applied site-directed and random mutagenesis in order to to transform CP into FP and vice versa. A purple chromoprotein asCP (asFP595) from Anemonia sulcata and a red fluorescent protein DsRed from Discosoma sp. were selected as representatives of CPs and FPs, respectively. For asCP, some substitutions at positions 148 and 165 (numbering in accordance to GFP) were found to dramatically increase quantum yield of red fluorescence. For DsRed, substitutions at positions 148, 165, 167, and 203 significantly decreased fluorescence intensity, so that the spectral characteristics of these mutants became more close to those of CPs. Finally, a practically non-fluorescent mutant DsRed-NF was generated. This mutant carried four amino acid substitutions, specifically, S148C, I165N, K167M, and S203A. DsRed-NF possessed a high extinction coefficient and an extremely low quantum yield (< 0.001). These spectral characteristics allow one to regard DsRed-NF as a true chromoprotein. CONCLUSIONS: We located a novel point in asCP sequence (position 165) mutations at which can result in red fluorescence appearance. Probably, this finding could be applied onto other CPs to generate red and far-red fluorescent mutants. A possibility to transform an FP into CP was demonstrated. Key role of residues adjacent to chromophore's phenolic ring in fluorescent/non-fluorescent states determination was revealed
Energy spectrum of cascades generated by muons in Baksan underground scintillation telescope
Spectrum of cascades generated by cosmic ray muons underground is presented. The mean zenith angle of the muon arrival is theta=35 deg the depth approx. 1000 hg/sq cm. In cascades energy range 700 GeV the measured spectrum is in agreement with the sea-level integral muon spectrum index gamma=3.0. Some decrease of this exponent has been found in the range 4000 Gev
A search for gamma-ray point sources with the Carpet shower array
A search for super-high energy gamma-ray point sources has been carried out. The well known source Cyg X-3 was observed first and preliminary results of data analysis are presented. There is not positive excess of showers from the source region, but phase analysis discovers a small pulse at phase 0.6 which corresponds to the integral flux (6 + or - 3) X 10 to the minus 14th power cm-2 sec-1 at E sub gamma 3x10 to the 14th power eV
Spin-down of neutron stars by neutrino emission
We study the spin-down of a neutron star during its early stages due to the
neutrino emission. The mechanism we consider is the subsequent collisions of
the produced neutrinos with the outer shells of the star. We find that this
mechanism can indeed slow down the star rotation but only in the first tens of
seconds of the core formation, which is when the appropriate conditions of flux
and collision rate are met. We find that this mechanism can extract less than 1
% of the star angular momentum, a result which is much less than previously
estimated by other authors.Comment: 9 pages, 2 eps figures, RevTeX 4-1. The paper was significantly
modified. Now it addresses only the issues of a neutron star spin-down.
Version to be published in Phys. Rev.
Space-Time Evolution of Ultrarelativistic Quantum Dipoles in Quantum Electrodynamics
We discuss space-time evolution of ultrarelativistic quantum dipole in QED.
We show that the space-time evolution can be described, in a certain
approximation, by means of a regularized wave function, whose parameters are
determined by the process of the dipole creation by a local current. We derive
using these wave functions the dipole expansion law, that is found to coincide
parametrically in the leading order with the one suggested by Farrar,
Frankfurt,Liu and Strikman.Comment: 15 page
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