New Kinds of Acoustic Solitons

We find that the modified sine-Gordon equation belonging to the class of the soliton equations describes the propagation of extremely short transverse acoustic pulses through the low-temperature crystal containing paramagnetic impurities with effective spin S=1/2 in the Voigt geometry case. The features of nonlinear dynamics of strain field and effective spins, which correspond to the different kinds of acoustic solitons, are studied.Comment: 9 pages, 1 figur

Radiation Properties of Synthesized under Different Conditions Hydroxyapatite

The aim of the study is investigating of the formation mechanisms of radiation paramagnetic defects in synthesized carbonized hydroxyapatite. The response to ionizing radiation exposure was studied by the electron paramagnetic resonance method.Исследование частично поддерживалось госзаданием «Спин» Г.р. № 122021000036-3

A new species of Todites [Pteridophyta] with in situ spores from the Upper Permian of Pechora Cis-Urals [Russia]

Todites lobulatus sp.nov.is described from the lowermost Upper Permian (Ufimian) of the Pechora basin.The fossil remains preserved as compressions and impressions, were collected from near−shore lake deposits of the Intinskian Formation.The species belongs to protoleptosporangiate ferns (Pteridophyta) of the Osmundaceae, and is characterized by tripinnate fertile fronds with deeply dissected lobate pinnules with round apexes.Sporangia are round or ovoid, free, and located on the abaxial leaf surface.A group of specialized thick−walled cells is located on the top or side part of the sporangia.The species is the most ancient representative of Osmundaceae. Spores of Osmundacidites−type, preserved in situ, are characterized

Plants of the First Terrestrial Ecosystems

© 2019, Pleiades Publishing, Ltd. Abstract: The preconditions of an ecosystem for and major phases of colonization of land by higher plants are considered. The most important finds of higher plants in pre-Silurian deposits are discussed. A new plant, Volkhoviella primitiva Naug., Gen. et sp. nov., from Ordovician deposits of Leningrad oblast is described. General questions of the early evolution of land vegetation are considered