Very-high energy gamma-ray astronomy: A 23-year success story in high-energy astroparticle physics

Very-high energy (VHE) gamma quanta contribute only a minuscule fraction - below one per million - to the flux of cosmic rays. Nevertheless, being neutral particles they are currently the best "messengers" of processes from the relativistic/ultra-relativistic Universe because they can be extrapolated back to their origin. The window of VHE gamma rays was opened only in 1989 by the Whipple collaboration, reporting the observation of TeV gamma rays from the Crab nebula. After a slow start, this new field of research is now rapidly expanding with the discovery of more than 150 VHE gamma-ray emitting sources. Progress is intimately related with the steady improvement of detectors and rapidly increasing computing power. We give an overview of the early attempts before and around 1989 and the progress after the pioneering work of the Whipple collaboration. The main focus of this article is on the development of experimental techniques for Earth-bound gamma-ray detectors; consequently, more emphasis is given to those experiments that made an initial breakthrough rather than to the successors which often had and have a similar (sometimes even higher) scientific output as the pioneering experiments. The considered energy threshold is about 30 GeV. At lower energies, observations can presently only be performed with balloon or satellite-borne detectors. Irrespective of the stormy experimental progress, the success story could not have been called a success story without a broad scientific output. Therefore we conclude this article with a summary of the scientific rationales and main results achieved over the last two decades.Comment: 45 pages, 38 figures, review prepared for EPJ-H special issue "Cosmic rays, gamma rays and neutrinos: A survey of 100 years of research

metaRE R Package for Meta-Analysis of Transcriptome Data to Identify the cis-Regulatory Code behind the Transcriptional Reprogramming

At the molecular level, response to an external factor or an internal condition causes reprogramming of temporal and spatial transcription. When an organism undergoes physiological and/or morphological changes, several signaling pathways are activated simultaneously. Examples of such complex reactions are the response to temperature changes, dehydration, various biologically active substances, and others. A significant part of the regulatory ensemble in such complex reactions remains unidentified. We developed metaRE, an R package for the systematic search for cis-regulatory elements enriched in the promoters of the genes significantly changed their transcription in a complex reaction. metaRE mines multiple expression profiling datasets generated to test the same organism’s response and identifies simple and composite cis-regulatory elements systematically associated with differential expression of genes. Here, we showed metaRE performance for the identification of low-temperature-responsive cis-regulatory code in Arabidopsis thaliana and Danio rerio. MetaRE identified potential binding sites for known as well as unknown cold response regulators. A notable part of cis-elements was found in both searches discovering great conservation in low-temperature responses between plants and animals

Determining the Electromagnetic Field Parameters to Kill Flies at Livestock Facilities

We have considered the electromagnetic method to kill the larvae of flies ‒ agricultural pests. To address the task, a problem on the distribution of electromagnetic fields in their body was solved. The solution is based on the Maxwell's equations in the integral form, which automatically take into consideration the boundary conditions at the surface of the larvae. Since we propose the electromagnetic radiation whose wavelength is much larger than the linear sizes of insects, the derived integral equations were solved in the approximation of quasi-statics. That made it possible to convert them into a system of inhomogeneous linear algebraic equations whose solution is the components of electric field inside the larvae of flies. The study was conducted for the single-layer and two-layer insects of an ellipsoidal shape. The obtained fields provide a possibility to determine the magnitudes of potentials that occur at the larva cover, as well as to find out which of these values lead to breaking this cover with the ensuing death of the fly larva.To construct a dependence that would relate the number of imago from the larvae of flies to the parameters of electromagnetic radiation in the presence of an additive disturbance of a random character, we employed a full-factorial second-order planning. Electromagnetic radiation was applied to the fly larvae at the end of the second age. The exposure of fly larvae to the electromagnetic radiation was carried out in a frequency range of 10.2–9.8 GHz, a power flux density of 0.62‒038 mW/cm2 and an exposure of 2‒12 s. The development of larvae was observed until the formation and release of an adult insect.Based on a multifactor experiment, we derived the optimal values for the frequencies of radiation, power flux density, and exposure. To suppress insects at livestock facilities, starting from the larval stage and up until the release of imago, the electromagnetic radiation is needed with the following parameters: frequency is 10.2 GHz; power flux density is 0.37 mW/cm2; relative instability of the generator frequency is 10-8, exposure is 6 s. The release of imago from the pupae of fly larvae at livestock premises, irradiated with electromagnetic radiation, was less than 5 %.The experiment with piglets showed that when the chemical method for treating the premises was applied, a gain in the live weight amounted to 7.2 %; when the electromagnetic method was used, it was 9.2 %. A smaller increase in the live weight upon chemical treatment is due to the fact that a chemical solution exerts a negative impact not only on flies and their larvae, but also on animals. The study that we conducted could be used to create industrial installations to kill the larvae of flies at livestock facilities