6,179 research outputs found
Estimates for parameters and characteristics of the confining SU(3)-gluonic field in an -meson
The confinement mechanism proposed earlier by the author is applied to
estimate the possible parameters of the confining SU(3)-gluonic field in an
-meson. For this aim the electric form factor of an
-meson is nonperturbatively computed in an explicit analytic form.
The estimates obtained are also consistent with the width of the
electromagnetic decay . The corresponding estimates of
the gluon concentrations, electric and magnetic colour field strengths are also
adduced for the mentioned field at the scales of the meson under consideration.Comment: 20 pages, LaTe
Some estimates on the space scales of vortex pairs emitted from river mouths
International audienceTwo-dimensional vortex pairs are frequently observed in geophysical conditions, for example, in a shelf zone of the ocean near river mouths. The main aims of the work are to estimate the space scales of such vortex structures, to analyze possible scenarios of vortex pair motion and to give the qualitative classification of their trajectories. We discuss some features of the motion of strong localized vorticity concentrations in a given flow in the presence of boundaries. The analyses are made in the framework of a 2D point vortex mo-del with an open polygonal boundary. Estimations are made for the characteristic parameters of dipole vortex structures emitted from river mouths into the open ocean
Present state of power electronics circuitry and perspectives of its development
This paper is devoted mainly to the circuitry, because element base is a big independent issue. Let us say a few words about terminology. A modern converter can be rarely represented as a simple device like “rectifier”, “inverter” etc. It usually consists of the combination of several units, performing elementary functions. For such multistage units it makes sense to use a definition of converter “technology”, keeping in mind some actions with electric current for a certain purpose. It is similar to the step activities in chemistry: to take a substance, to heat it etc. After the formulation of a goal and a number of necessary actions it is possible to present a corresponding structure circuit. According to described above we tried to mention basic technologies used in modern power electronics. The perspectives of the electronics in the nearest future are connected with the further improvement of basic technologies, because their combination allows for developing new technologies. In our opinion, there are four such technologies.Стаття присвячена проблемам схемотехніки у сучасній енергетиці. Розглянуто декілька напрямків розробок електроприводів, відмічено їхні переваги та недоліки. Описано сучасні схемотехнічні можливості та перспективні напрямки їхнього подальшого розвитку в Україні
Quantum and Classical Orientational Ordering in Solid Hydrogen
We present a unified view of orientational ordering in phases I, II, and III
of solid hydrogen. Phases II and III are orientationally ordered, while the
ordering objects in phase II are angular momenta of rotating molecules, and in
phase III the molecules themselves. This concept provides quantitative
explanation of the vibron softening, libron and roton spectra, and increase of
the IR vibron oscillator strength in phase III. The temperature dependence of
the effective charge parallels the frequency shifts of the IR and Raman
vibrons. All three quantities are linear in the order parameter.Comment: Replaced with the final text, accepted for publication in PRL. 1 Fig.
added. Misc. text revision
Asymptotic normalization coefficients for mirror virtual nucleon decays in a microscopic cluster model
It has been suggested recently (Phys. Rev. Lett. 91, 232501 (2003)) that
charge symmetry of nucleon-nucleon interactions relates the Asymptotic
Normalization Coefficients (ANCs) of proton and neutron virtual decays of
mirror nuclei. This relation is given by a simple analytical formula which
involves proton and neutron separation energies, charges of residual nuclei and
the range of their strong interaction with the last nucleon. Relation between
mirror ANCs, if understood properly, can be used to predict astrophysically
relevant direct proton capture cross sections using neutron ANCs measured with
stable beams. In this work, we calculate one-nucleon ANCs for several light
mirror pairs, using microscopic two-, three- and four-cluster models, and
compare the ratio of mirror ANCs to the predictions of the simple analytic
formula. We also investigate mirror symmetry between other characteristics of
mirror one-nucleon overlap integrals, namely, spectroscopic factors and
single-particle ANCs.Comment: 12 pages, submitted to Phys. Rev.
Renormalization group equations in curved space-time with non-trivial Topology
Renormalization group equations for massless GUT's in curved space-time with
non-trivial topology are formulated. The asymptotics of the effective action
both at high and low energies are obtained. It is shown that the Casimir energy
contribution at high curvature (early Universe) becomes non-essential in the
effective action.Comment: 7 Page
On the 160th anniversary of Ivan V. Michurin’s birth
October 2015 marks the 160th anniversary of the birth of Ivan V. Michurin. As a scientist and plant breeder, he made a significant improvement of many varieties of fruit, berry, and flowers. He developed methods of plant breeding, promoted gardening to the north and east of Russia, including Siberia. He introduced some new berry species as Actinidia and black chokeberry and was the first in the country who used dwarf and semi dwarf stocks of apples. Michurin initiated the mass movement of fancier gardeners and horticulture experimenters in USSR who changed and significantly extended the species and geographic ranges of fruit and berry cultivation in Russia. He not only made a vast collection of species and varieties of fruit plants from around the world but also organized their involvement and widespread use in the breeding by hybridization, including interspecific crosses. He created some new artificial interspecific hybrids such as Cerapadus (cherry and bird cherry hybrid), and others. Michurin created 132 cultivars. Eleven of them are not only cultivated but also included in the “National Register of Protected Plant breeding Achievements of the Russian Federation”. Michurin, having lived a long productive life, did not come to the time when he was not only declared “the great nature transformer”, but also “appointed” creator of “Michurin’s theory”, so-called “Creative Darwinism”. However, thirty years later, scientists, though rarely, but still tried to separate his name from Lysenkoism and rehabilitate the scientist
Uncovering a pressure-tuned electronic transition in BiSrYCu2O8 using Raman scattering and x-ray diffraction
We report pressure tuned Raman and x-ray diffraction data of
Bi1.98Sr2.06Y0.68Cu2O8 revealing a critical pressure at 21 GPa with anomalies
in six physical quantities: electronic Raman background, electron-phonon
coupling, spectral weight transfer from high to low frequency, density
dependent behaviour of phonon and magnon frequencies, and a compressibility
change in the c-axis. For the first time in a cuprate, mobile charge carriers,
lattice, and magnetism all show anomalies at a distinct critical pressure in
the same experimental setting. Furthermore, the Raman spectral changes are
similar to that seen traversing the superconducting dome with doping,
suggesting that the critical pressure at 21 GPa is related to the much
discussed critical point at optimal doping.Comment: 5 pages, 4 figures, submitted to PR
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