Dynamics of energetic spectrum of solar-diurnal variations of cosmic rays in 19-24 solar activity cycles

The anisotropic angular distribution of cosmic rays (CR) in the interplanetary medium manifests itself on Earth as periodic diurnal intensity variations. Ground-based detectors of CRs have different energy sensitivity to the primary CR radiation and, therefore, the amplitude and phase recorded by them are also different. This fact makes it possible to study the energy spectrum of the variations when using a sufficient number of detectors. In this work, the results of the investigation of the energy spectrum of solar-diurnal variations of CRs obtained by a network of neutron monitors and muon telescopes are presented. The network allows measuring CRs with median energies from units to hundreds of GeV. The expected values of the amplitude and phase of the daily CR variations at the selected ground-based stations for different types of the energy spectrum are shown. The calculated data are compared with experimental data for 19-24 solar activity cycles

Two subforms of eukaryotic topoisomerase I Purification and structure-function relationships

AbstractA new method for isolation of eukaryotic topoisomerase 1 from calf thymus and from Jurkat-1 cells using HPLC has been developed. The method allows quantitative purification of high molecular weight topo I and of two low molecular weight fractions differing by their isoelectric points. It has been suggested that these fractions be characterized as two subforms of the enzyme possessing structural and functional differences. The differences in their specific activities, sensitivity to camptothecin and in their proteolytic digestion maps have been demonstrated for the two enzymes

NMDB database and global survey method

The method of a global survey developed in the 1970s allows using a world-wide network of neutron monitor stations as a single multidirectional device. Wherein, receiving characteristics of each device, which reflects their geometries and geographical positions, are taken into account. Such an approach makes it possible to define the first two angular moments of the distribution function of cosmic rays in the interplanetary space at each hour of observation. With the creation in 2008/2009 and subsequent development of an international database of neutron monitors NMDB, for the first time it appeared an opportunity to use the global survey method in real-time mode. Such a situation creates a unique possibility to use the results not only for scienti- fic researches but also for space weather forecasting. To use the data of the world-wide network of neutron monitors it is necessary to carry preliminary preparations. Thereby, in the current work, the main attention is attracted to a solution to some practical questions that arise when using the NMDB in real-time

NMDB and space weather forecasting

From the creation of NMDB in 2007 and through the growth in the number of stations and the data accumulation, the ShICRA SB RAS group continuously have used its facilities. For the last years we have created a method for short-term forecasting of intense geomagnetic storms with an advance time 1-2 days. The probability of forecasting is around 80%. We have reported about the method in the previous NMDB: virtual symposium on cosmic ray studies with neutron detectors in 2020. The method is based on the global survey method that was developed in Yakutsk in 1960s and uses the world network of neutron monitors as a single multidirectional device. The method is intended to estimate hourly dynamics of cosmic ray anisotropy in free-space. Note that only with the NMDB creation we managed to implement it in real time mode. Now we started work on creating another method for space weather forecasting by measurements of cosmic ray fluctuations. For this purpose, we use 1-min data of NMDB. In the current report we present the first results of our investigation on forecasting of intense geomagnetic storms with Dst < -50 nT. The results obtained indicate the possibility of developing and implementing in real time a method for predicting strong geophysical manifestations of space weather on the basis of ground-based cosmic ray measurements

Cosmic ray angular distribution dynamics during Forbush decrease in 3-4 November 2021

On November 3-4, 2021, there was a coronal ejection of the solar mass into the interplanetary medium. According to direct observations of the interplanetary magnetic field and the solar wind, the ejection was accompanied by a magnetic cloud. During the event, neutron monitors of the NMDB network registered a two-stage Forbush decrease with a total amplitude of up to 15%. A preliminary analysis of the NMDB data shows that the first step was due to the cosmic ray decrease behind the shock wave front, while the second step was due to the cosmic ray anisotropy formed in the magnetic cloud. This work was undertaken to study the dynamics of the angular distribution of cosmic rays in this event. The cosmic ray distribution was determined using the global survey method developed at the ShICRA in the 1960s. The method makes it possible to use the worldwide network of neutron monitors as a single multidirectional instrument and to determine the hourly dynamics of CR distribution. It is shown that unidirectional and bidirectional anisotropies of significant amplitude are observed inside the magnetic cloud. The results obtained are discussed in the framework of modern theories of the formation of magnetic clouds. The temporal dynamics of the spatial-angular distribution of cosmic rays during the Forbush decrease on November 3–4, 2021 was determined. The presence of cosmic ray anisotropy with an amplitude comparable to the magnitude of the density decrease itself was found

On features of crystal structure of semiconductor-ferroelectric Ag₃AsS₃

The temperature dependences of the unit cell parameters a(T) and c(T) of Ag₃AsS₃ were measured by the X-ray dilatometry method with high precision within the temperature range 100 to 300 K in the dark mode and under laser irradiation (λ = 532 nm). It was found that the parameter c increases almost linear with decreasing the temperature from 300 down to 100 K for samples in the dark. At the same time, for samples that were exposed during cooling to laser irradiation, the increase of the parameter с by the value ∆c ≈ (0.002…0.003) Å is observed at temperatures Tp = 145…147 K. This leap is typical for systems in which a phase transition of the first order occurs. Furthermore, there were investigated temperature dependences of the integral relative intensity I(T) of main structural maxima of Ag₃AsS₃ both in the dark mode and under laser irradiation. It was established the character of the dependence I(T) for these reflexes was changed significantly by laser irradiation

Electronic properties and phase transitions in low-dimensional semiconductors

We present the first review of the current state of the literature on electronic properties and phase transitions in TlX and TlMX2 (M = Ga, In; X = Se, S, Te) compounds. These chalcogenides belong to a family of the low-dimensional semiconductors possessing chain or layered structure. They are of significant interest because of their highly anisotropic properties, semi- and photoconductivity, non-linear effects in their I-V characteristics (including a region of negative differential resistance), switching and memory effects, second harmonic optical generation, relaxor behavior and potential applications for optoelectronic devices. We review the crystal structure of TlX and TlMX2 compounds, their transport properties under ambient conditions, experimental and theoretical studies of the electronic structure, transport properties and semiconductor-metal phase transitions under high pressure, and sequences of temperature-induced structural phase transitions with intermediate incommensurate states. Electronic nature of the ferroelectric phase transitions in the above-mentioned compounds, as well as relaxor behavior, nanodomains and possible occurrence of quantum dots in doped and irradiated crystals is discussed.Comment: 70 pages, 38 figure