98 research outputs found
Aconitum lasiocarpum and A. variegatum (Ranunculaceae) populations near the eastern limits of their ranges in the lowlands of Ukraine
The study of the ranges, habitats and current state of rare and threatened species of plants is a relevant task of ecological research. The paper presents the results of the study of habitats and current state of populations of two rare species of Ukrainian flora Aconitum lasiocarpum (Rchb.) Gáyer and A. variegatum L. (Ranunculaceae) in the lowlands of Ukraine. These species are members of the mountain element of the flora of lowlands of Ukraine and glacial relics, which descended from the Carpathians Mountains to the lowlands of Ukraine during glaciation. Aconitum lasiocarpum is a rare species of European flora, included to the Red Data Books of the Czech Republic and Slovakia, Poland and Ukraine. Unlike the well studied A. lasiocarpum populations in the main part of the range in the Carpathian Mountains, local populations of this species near the eastern limit of the range in the lowlands of Ukraine remain undescribed. In these exclaves of the range in the lowlands of Ukraine A. lasiocarpum is a glacial relic. Here it grows in alder forests Ribo nigri-Alnetum ordo Alnion glutinosa alliance. Lowland A. lasiocarpum populations consist of 1000–10000 adults with a significant number of young individuals. In the past lowland A. lasiocarpum populations occupied a much large area. Deforestation and drainage melioration led to reduction of the populations. Taking into account the low number of glacial relic populations at the eastern limit of the range of A. lasiocarpum, all localities of this species in the lowland part of the range in Ukraine must be taken under protection in situ. Aconitum variegatum L. grows in wet alder and oak forest and in areas with hazel shrubs. The populations of this species in lowlands of Ukraine occupy a very small area and are characterized by low numbers of individuals. In the past populations of this species in the lowlands of Ukraine occupied a larger area. As a rare species of the Ukrainian flora A. variegatum deserves to be included to the Red Data Book of Ukraine. We propose to protect the unique population of A. variegatum near Susk village in Rivne region as a botanical reserve
Magnetohydrodynamic equilibria of a cylindrical plasma with poloidal mass flow and arbitrary cross section shape
The equilibrium of a cylindrical plasma with purely poloidal mass flow and
cross section of arbitrary shape is investigated within the framework of the
ideal MHD theory. For the system under consideration it is shown that only
incompressible flows are possible and, conscequently, the general two
dimensional flow equilibrium equations reduce to a single second-order
quasilinear partial differential equation for the poloidal magnetic flux
function , in which four profile functionals of appear. Apart from
a singularity occuring when the modulus of Mach number associated with the
Alfv\'en velocity for the poloidal magnetic field is unity, this equation is
always elliptic and permits the construction of several classes of analytic
solutions. Specific exact equlibria for a plasma confined within a perfectly
conducting circular cylindrical boundary and having i) a flat current density
and ii) a peaked current density are obtained and studied.Comment: Accepted to Plasma Physics & Controlled Fusion, 14 pages, revte
About possibility to locate an EQ epicenter using parameters of ELF/ULF preseismic emission
A relation between parameters of preseismic ULF/ELF emissions and EQ is studied. The magnetic data measured at Karymshino station (Kamchatka, Russia) along with data on local seismic activity during eight years of observations (2001–2008) are taken for the analysis. Source azimuth is detected in different techniques, based on the analysis of the total field and its polarized pulsed component. The latter technique shows a better accuracy in the source azimuth detection. The errors of the method are associated with existence of non-seismic sources and with use of one-point observation. The second error can be eliminated by development of multi-point observations
The astrometric Gaia-FUN-SSO observation campaign of 99 942 Apophis
Astrometric observations performed by the Gaia Follow-Up Network for Solar
System Objects (Gaia-FUN-SSO) play a key role in ensuring that moving objects
first detected by ESA's Gaia mission remain recoverable after their discovery.
An observation campaign on the potentially hazardous asteroid (99 942) Apophis
was conducted during the asteroid's latest period of visibility, from
12/21/2012 to 5/2/2013, to test the coordination and evaluate the overall
performance of the Gaia-FUN-SSO . The 2732 high quality astrometric
observations acquired during the Gaia-FUN-SSO campaign were reduced with the
Platform for Reduction of Astronomical Images Automatically (PRAIA), using the
USNO CCD Astrograph Catalogue 4 (UCAC4) as a reference. The astrometric
reduction process and the precision of the newly obtained measurements are
discussed. We compare the residuals of astrometric observations that we
obtained using this reduction process to data sets that were individually
reduced by observers and accepted by the Minor Planet Center. We obtained 2103
previously unpublished astrometric positions and provide these to the
scientific community. Using these data we show that our reduction of this
astrometric campaign with a reliable stellar catalog substantially improves the
quality of the astrometric results. We present evidence that the new data will
help to reduce the orbit uncertainty of Apophis during its close approach in
2029. We show that uncertainties due to geolocations of observing stations, as
well as rounding of astrometric data can introduce an unnecessary degradation
in the quality of the resulting astrometric positions. Finally, we discuss the
impact of our campaign reduction on the recovery process of newly discovered
asteroids.Comment: Accepted for publication in A&
Geophysical Observatory in Kamchatka region for monitoring of phenomena connected with seismic activity
Regular monitoring of some geophysical parameters in association with seismicity has been carried out since last year at the Japan-Russian Complex Geophysical Observatory in the Kamchatka region. This observatory was organized in connection with the ISTC project in Russia and was motivated by the results of the FRONTIER/RIKEN and FRONTIER/NASDA research projects in Japan. The main purpose of the observations is to investigate the electromagnetic and acoustic phenomena induced by the lithosphere processes (especially by seismic activity). The seismicity of the Kamchatka area is analyzed and a description of the observatory equipment is presented. At present, the activity of the observatory includes the seismic (frequency range ∆F = 0.5 – 40 Hz) and meteorological recordings, together with seismo-acoustic (∆F = 30 – 1000 Hz) and electromagnetic observations: three-component magnetic ULF variations ( ∆F = 0.003 – 30 Hz), three-component electric potential variations ( ∆F <u><</u> 1.0 Hz), and VLF transmitter’s signal perturbations ( ∆F ~ 10 – 40 kHz)
Study of electromagnetic emissions associated with seismic activity in Kamchatka region
International audienceA review of data processing of electromagnetic emission observation collected at the Complex Geophysical Observatory Karimshino (Kamchatka peninsula) during the first 5 months (July?November, 2000) of its operation is given. The main goal of this study addresses the detection of the phenomena associated with Kamchatka seismic activity. The following observations have been conducted at CGO: variations of ULF/ELF magnetic field, geoelectric potentials (telluric currents), and VLF signals from navigation radio transmitters. The methods of data processing of these observations are discussed. The examples of the first experimental results are presented
Hodograph method to estimate the latitudinal profile of the field-line resonance frequency using the data from two ground magnetometers
Polarization and spectral energy distribution in OJ 287 during the 2016/17 outbursts
We report optical photometric and polarimetric observations of the blazar OJ 287 gathered during 2016/17. The high level of activity, noticed after the General Relativity Centenary flare, is argued to be part of the follow-up flares that exhibited high levels of polarization and originated in the primary black hole jet. We propose that the follow-up flares were induced as a result of accretion disk perturbations, travelling from the site of impact towards the primary SMBH. The timings inferred from our observations allowed us to estimate the propagation speed of these perturbations. Additionally, we make predictions for the future brightness of OJ 287. © 2017 by the authors
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