Population status of Bupleurum aureum (Apiaceae), a Critically Endangered plant species in a region of European Russia

Protected Areas are considered as an important and widely applied tool for biodiversity conservation. They are especially relevant for conservation of threatened species populations. This paper presents study aimed to investigate population status and suitability of habitat conditions of a regionally Critically Endangered plant species, Bupleurum aureum (Apiaceae). Our research has been conducted in National Park “Smolny” (European Russia). The field studies were carried out in 2008, 2013–2018 in two study sites (Plot1, Plot2). In each study sites, square plots (1×1 m) were established to cover the most number of B. aureum individuals. The population status was assessed on the basis of the morphometric traits of individuals (height of generative individuals, number of umbellulas per umbella, number of schizocarpiums per umbellula), number of individuals per population, age structure of populations, composition of accompanying flora. We analysed relationships between environmental conditions (shadiness, soil moisture, salt regime of soil, soil nitrogen, soil pH, soil moisture variability) and morphometric and population traits of B. aureum to reveal the most influencing environmental factors. We found that at the north-western limit of the range, B. aureum has relatively low abundance and height of individuals in compare to available data from other parts of its range. The population age structure indicated higher habitat suitability in Plot1 due to presence of both vegetative and generative individuals. At the same time, in Plot2, B. aureum population is under serious threat due to a lack of vegetative individuals noted during almost whole study period. We suppose a forthcoming threat of probable loss of this B. aureum population. Environment data obtained in both habitats of B. aureum populations in National Park “Smolny” (Russia) indicated high relationships between soil moisture and the number of inflorescences formed by plants. We suppose a threat of extinction of the B. aureum population due to the building activity of Castor fiber inhabiting the small river Bakhmustika located nearby of study area. If the small river will be dammed, it could lead to decrease in B. aureum population in both studied sites due to the increase in ground water level

Coulomb tunneling for fusion reactions in dense matter: Path integral Monte Carlo versus mean field

We compare Path Integral Monte Carlo calculations by Militzer and Pollock (Phys. Rev. B 71, 134303, 2005) of Coulomb tunneling in nuclear reactions in dense matter to semiclassical calculations assuming WKB Coulomb barrier penetration through the radial mean-field potential. We find a very good agreement of two approaches at temperatures higher than ~1/5 of the ion plasma temperature. We obtain a simple parameterization of the mean field potential and of the respective reaction rates. We analyze Gamow-peak energies of reacting ions in various reaction regimes and discuss theoretical uncertainties of nuclear reaction rates taking carbon burning in dense stellar matter as an example.Comment: 13 pages, 7 figures, to appear in Phys. Rev.

SU(2) Skyrme Vortices

A regular method for constructing vortex-like solutions with cylindrical symmetry to the equations of the SU(2) Skyrme chiral model is proposed. A numerical estimate for the length density of mass is given

Some problems in the study of the chronology of the ancient nomadic cultures in Eurasia (9th - 3rd centuries BC)

This research is focused on the chronological investigations of ancient nomads belonging to the Scythian cultures which occupied the steppe and forest-steppe zones of Eurasia during the 9th-3rd centuries BC. The 14C dates for the pre-scythian and early scythian time in both Europe and Asia are presented and compared to their chronological position based on archaeological evidence. The first 14C dates have been produced for the Scythian time monuments located in the Lower Volga River basin, Urals and Transurals regions. Their chronological positions are compared with the position of the monuments of Southern Siberia and Central Asia. It was shown that the nomadic cultures belonging to the Scythian culture began to exist over the wide territory of Eurasia from the 9th-8th centuries cal BC and there are some monuments which may be synchronous to the Arzhan royal barrow (the oldest monument known). A list of new 14C dates and a map of the monuments are presented

A chronology of the Scythian antiquities of Eurasia based on new archaeological and C-14 data

The paper is compares the chronology of the monuments of the Scythian epoch located in the east and west of the Eurasian steppe zone on the basis of both archaeological and radiocarbon data. The lists of C-14 dates for the monuments located in different parts of Eurasia are presented according to the periods of their existence. Generally, the C-14 dates are confirmed the archaeological point of view and allow us to compare the chronological position of the European and Asian Scythian monuments on the united C-14 time scale

Large collection of astrophysical S-factors and its compact representation

Numerous nuclear reactions in the crust of accreting neutron stars are strongly affected by dense plasma environment. Simulations of superbursts, deep crustal heating and other nuclear burning phenomena in neutron stars require astrophysical S-factors for these reactions (as a function of center-of-mass energy E of colliding nuclei). A large database of S-factors is created for about 5000 non-resonant fusion reactions involving stable and unstable isotopes of Be, B, C, N, O, F, Ne, Na, Mg, and Si. It extends the previous database of about 1000 reactions involving isotopes of C, O, Ne, and Mg. The calculations are performed using the Sao Paulo potential and the barrier penetration formalism. All calculated S-data are parameterized by an analytic model for S(E) proposed before [Phys. Rev. C 82, 044609 (2010)] and further elaborated here. For a given reaction, the present S(E)-model contains three parameters. These parameters are easily interpolated along reactions involving isotopes of the same elements with only seven input parameters, giving an ultracompact, accurate, simple, and uniform database. The S(E) approximation can also be used to estimate theoretical uncertainties of S(E) and nuclear reaction rates in dense matter, as illustrated for the case of the 34Ne+34Ne reaction in the inner crust of an accreting neutron star.Comment: 13 pages, 2 figures, Phys. Rev. C, accepte