431 research outputs found
The Desert Steppes of Eastern Europe: Common Regularities and Specific Features
Desert steppes are formed within the southern subzone of the steppe zone. Some researchers categorize this subzone not as a part of the steppe zone, but as a separate semi-desert zone. The aim of our research is to identify features of the structure of desert steppes and to understand the zonal status of the territory occupied by them. In Eastern Europe, desert steppes are common in the Ergeni Hills and the Caspian Lowland. Research was carried out by the route method. We made about 600 relevés 10 x 10 m2 in size. Plant communities of desert steppes consist of both firm-bunch grasses and dwarf semishrubs. Stipeta sareptanae is a zonal type with light chestnut soils. Communities of dwarf semishrubs (halophytic variations of steppes) grow onsaline soils and occupy quite large areas. A substantial part of the southern subzone of the steppe zone in Eastern Europe is used as pasture and hayfield: this is why modern desert steppes have been considerably modified, and dynamically unstable communities are often dominant.
Keywords: desert steppes, zonal type, ecological variants, peculiarities, Ergeni Hills, Caspian Lowlan
Excitation energies, hyperfine constants, E1, E2, M1 transition rates, and lifetimes of (6s2)nl states in Tl I and Pb II
Energies of np (n=6-9), ns (n=7-9), nd (n=6-8), and nf (n=5-6) states in Tl I
and Pb II are obtained using relativistic many-body perturbation theory.
Reduced matrix elements, oscillator strengths, transition rates, and lifetimes
are determined for the 72 possible electric-dipole transitions.
Electric-quadrupole and magnetic-dipole matrix elements are evaluated to obtain
np(3/2) - mp(1/2) (n,m=6,7) transition rates. Hyperfine constants A are
evaluated for a number of states in 205Tl. First-, second-, third-, and
all-order corrections to the energies and matrix elements and first- and
second-order Breit corrections to energies are calculated. In our
implementation of the all-order method, single and double excitations of
Dirac-Fock wave functions are included to all orders in perturbation theory.
These calculations provide a theoretical benchmark for comparison with
experiment and theory.Comment: twelve tables, no figure
Plastic modeling in design education
The article discusses the role of plastic modeling in training bachelors of professional training specialization «Design of interior»Рассматривается роль пластического моделирования в подготовке бакалавров профессионального обучения профилизации «Дизайн интерьера
State-Dependent Optical Lattices for the Strontium Optical Qubit
We demonstrate state-dependent optical lattices for the Sr optical qubit at
the tune-out wavelength for its ground state. We tightly trap excited state
atoms while suppressing the effect of the lattice on ground state atoms by more
than four orders of magnitude. This highly independent control over the qubit
states removes inelastic excited state collisions as the main obstacle for
quantum simulation and computation schemes based on the Sr optical qubit. Our
results also reveal large discrepancies in the atomic data used to calibrate
the largest systematic effect of Sr optical lattice clocks.Comment: 6 pages, 4 figures + 6 pages supplemental materia
Towards a Mg lattice clock: Observation of the transition and determination of the magic wavelength
We optically excite the electronic state in Mg atoms,
laser-cooled and trapped in a magic-wavelength lattice. An applied magnetic
field enhances the coupling of the light to the otherwise strictly forbidden
transition. We determine the magic wavelength, the quadratic magnetic Zeeman
shift and the transition frequency to be 468.463(207)nm,
-206.6(2.0)MHz/T and 655 058 646 691(101)kHz, respectively. These
are compared with theoretical predictions and results from complementary
experiments. We also developed a high-precision relativistic structure model
for magnesium, give an improved theoretical value for the blackbody radiation
shift and discuss a clock based on bosonic magnesium.Comment: 5 pages, 3 figure
Level-crossing spectroscopy of the 7, 9, and 10D_5/2 states of 133Cs and validation of relativistic many-body calculations of the polarizabilities and hyperfine constants
We present an experimental and theoretical investigation of the
polarizabilities and hyperfine constants of D_J states in 133Cs for J=3/2 and
J=5/2. New experimental values for the hyperfine constant A are obtained from
level-crossing signals of the (7,9,10)D_5/2 states of 133Cs and precise
calculations of the tensor polarizabilities alpha_2. The results of
relativistic many-body calculations for scalar and tensor polarizabilities of
the (5-10)D_3/2 and (5-10)D_5/2 states are presented and compared with measured
values from the literature. Calculated values of the hyperfine constants A for
these states are also presented and checked for consistency with experimental
values.Comment: 12 pages, revtex4, 11 figure file
High-precision calculations of In I and Sn II atomic properties
We use all-order relativistic many-body perturbation theory to study 5s^2 nl
configurations of In I and Sn II. Energies, E1-amplitudes, and hyperfine
constants are calculated using all-order method, which accounts for single and
double excitations of the Dirac-Fock wave functions.Comment: 10 pages, accepted to PRA; v2: Introduction changed, references adde
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