Radio-Frequency Measurements of Coherent Transition and Cherenkov Radiation: Implications for High-Energy Neutrino Detection

We report on measurements of 11-18 cm wavelength radio emission from interactions of 15.2 MeV pulsed electron bunches at the Argonne Wakefield Accelerator. The electrons were observed both in a configuration where they produced primarily transition radiation from an aluminum foil, and in a configuration designed for the electrons to produce Cherenkov radiation in a silica sand target. Our aim was to emulate the large electron excess expected to develop during an electromagnetic cascade initiated by an ultra high-energy particle. Such charge asymmetries are predicted to produce strong coherent radio pulses, which are the basis for several experiments to detect high-energy neutrinos from the showers they induce in Antarctic ice and in the lunar regolith. We detected coherent emission which we attribute both to transition and possibly Cherenkov radiation at different levels depending on the experimental conditions. We discuss implications for experiments relying on radio emission for detection of electromagnetic cascades produced by ultra high-energy neutrinos.Comment: updated figure 10; fixed typo in equation 2.2; accepted by PR

Some features of electromagnetic field of charged particle revolving about dielectric ball

A relativistic electron uniformly rotating along an equatorial orbit around a dielectric ball may generate Cherenkov radiation tens of times more intense as that in case of revolution of a particle in a continuous, infinite and transparent medium. The root-mean-square values of electric and magnetic field strengths of particle are practically not localized in the central part of the equatorial plane of ball and close to the poles of ball.Comment: 6 pages, 3 figures, contribution to Proceedings of International Symposium RREPS-2009, 07-11 September, 2009, Zvenigorod, Russi

The Necessary Product in the System of Socialist Reproduction

The necessary product is the objective foundation of the real incomes of workers employed in the sphere of material production.

A new species of the Daphnia sinevi group (Crustacea: Cladocera: Daphniidae) from Sakhalin Island, Russian Far East

Garibian, Petr G., Kotov, Alexey A. (2020): A new species of the Daphnia sinevi group (Crustacea: Cladocera: Daphniidae) from Sakhalin Island, Russian Far East. Zootaxa 4820 (3): 485-505, DOI: https://doi.org/10.11646/zootaxa.4820.3.

A new species of Pseudochydorus Fryer, 1968 (Cladocera: Anomopoda: Chydoridae) from South-East Asia

Sinev, Artem Y., Garibian, Petr G., Gu, Yangliang (2016): A new species of Pseudochydorus Fryer, 1968 (Cladocera: Anomopoda: Chydoridae) from South-East Asia. Zootaxa 4079 (1): 129-139, DOI: http://doi.org/10.11646/zootaxa.4079.1.

The Role of Old Relicts in Structuring the Boreal/Tropical Transitional Zone: The Case of East Asian Planktonic Cladocera (Crustacea)

Previous studies provided evidence of the mixing of boreal–tropical cladocerans (Crustacea) in the Far East of Eurasia, as well as the presence of numerous pre-Pleistocene relict endemics. In this study, we hypothesize that the colonization history is reflected in the proportions of endemic/boreal/tropical taxa among different habitat types within this region. We analyzed 442 qualitative samples collected from seven sub-regions of the Far East of Russia and South Korea along a latitudinal transect of approximately 2200 km, where we identified 101 Cladocera species. Our results showed a significantly higher proportion of endemic taxa in the plankton compared to the littoral and benthic zones. The proportions of endemic/boreal/tropical taxa in the permanent and temporary waters were similar. We observed a distinct shift in dominance in benthos and littoral zone across our transect: boreal taxa were prevalent in the northern sub-regions (1–4), while tropical taxa were prevalent in the southern sub-regions (5–7), with a pronounced boreal–tropical transition zone (sub-regions 4–5). Our findings suggest that this pattern arose due to the unhindered dispersion of the two faunas in a latitudinal direction until they met at the boundary during their arrival in the Late Pleistocene. In contrast, the proportions of the boreal and tropical taxa in plankton did not exceed 16% in any of the studied sub-regions, and the proportion of boreal taxa decreased from 16% to 10%, while that of the tropical taxa increased from 0% to 10% from north to south. We propose that the lower proportions and the absence of mixing of fauna in the plankton can be explained by the strong presence (sometimes dominance) of relics that occupy these water bodies before the arrival of colonizers from the north and south. Our findings highlight the significant role of biotic interactions in the formation of biogeographic boundaries, which was previously underestimated

FIGURE 4 in A new species of Pseudochydorus Fryer, 1968 (Cladocera: Anomopoda: Chydoridae) from South-East Asia

FIGURE 4. Pseudochydorus bopingi sp. nov. from the type locality, roadside pond in Hunan province, China, thoracic limbs of parthenogenetic female. A, limb I. B, IDL and ODL of limb I. C, IDL setae of limb I. D, limb II. E, exopodite and scraping spine 1 of limb II. F, exopodite of limb III. G–H, inner portion of limb III. I, exopodite of limb IV. J–K, inner portion of limb IV, seta b–d not shown on J. L, limb V

A redescription of the Mediterranean endemic cladoceran Daphnia chevreuxi Richard, 1896 (Cladocera: Daphniidae)

The Mediterranean area is a biodiversity and endemism hotspot. "Circum-Mediterranean"taxa are known among different hydrobionts, including the water fleas. Some Mediterranean endemic cladoceran taxa have been described or redescribed according to modern taxonomical standards, but accurate drawings are missing for others. Here we redescribe the Mediterranean endemic Daphnia chevreuxi Richard, 1896 (Crustacea: Cladocera) and briefly review available data on its distribution and ecology. The species is confirmed to be a typical inhabitant of the temporary ponds of the central Mediterranean area, whereas its populations from the eastern Balkans and the Middle East should be studied in order to check for their actual identity. We conclude that the Mediterranean area is an example of a well-studied region as Cladocera are concerned, but the study of other regions is necessary in order to understand better the cladoceran diversity and distribution patterns in Eurasia