Temperature, pressure and density of Venus' atmosphere according to measurement data of the AIS Venera-4

Atmospheric temperature, pressure, and density of Venus according to measurements obtained by AIS Venera-

K*-couplings for the antidecuplet excitation

We estimate the coupling of the K* vector meson to the N-->Theta+ transition employing unitary symmetry, vector meson dominance, and results from the GRAAL Collaboration for eta photoproduction off the neutron. Our small numerical value for the coupling constant is consistent with the non-observation of the Theta+ in recent CLAS searches for its photoproduction. We also estimate the K*-coupling for the N-->Sigma* excitation, with Sigma* being the Sigma-like antidecuplet partner of the Theta+-baryon.Comment: 9 pages, 1 figure. Minor changes in text and abstract, references added; version to appear in Phys. Rev.

Таємниця одного адміністратора

Провінційний чиновник, особливо дореформених часів, – і досі рідкісний гість на сторінках вітчизняних наукових монографій, дисертаційних досліджень, ба, навіть, статей у спеціалізованих періодичних виданнях. Поясненням цього феномену є, мабуть, сформована ще класичною російською літературою і діяча-ми доби Великих Реформ слава більшості миколаївських чиновників чи то як «сірості», посередності (стор. 73), чи то як хабарників і крадіїв [1]. З іншого боку, тривалій відразі до студій з адміністративної історії прислужилася логіка т.зв. «національного наративу», за якою місцевий представник імперської адміністра-ції видавався своєрідним «чужинцем» – колоніалістом чи колабораціоністом. Втім, останні десять років досі так само національно орієнтовані англо- і російськомовна історіографії демонструють тенденцію до «імперського пово-роту» («imperial turn»), зокрема, актуалізуючи і переосмислюючи проблематику адміністрування Російської імперії [2]. Вкупі зі зростаючою від часів Великих Реформ кількістю поодиноких праць із історії місцевого управління [3], зокре-ма, і біографічного спрямування [4], це дозволяє очікувати і вітчизняного рене-сансу студій у царині адміністративної історії

Extraction of radiative decay width for the non-strange partner of Theta^+

Using the results of the GRAAL collaboration on the \eta photoproduction from the neutron target, we attempt to extract the partial radiative width of the possible new nucleon resonance N^*(1675). The obtained estimates support this resonance to be a very attractive candidate for the non-strange member of the exotic antidecuplet of baryons -- a partner of the \Theta^+ pentaquark. Our phenomenological value for the transition magnetic moment \mu(n^* n), appears to be in good agreement with predictions of the Chiral Quark Soliton Model.Comment: 4 pages, v2 corresponds to the journal publicatio

Formation of singularities on the surface of a liquid metal in a strong electric field

The nonlinear dynamics of the free surface of an ideal conducting liquid in a strong external electric field is studied. It is establish that the equations of motion for such a liquid can be solved in the approximation in which the surface deviates from a plane by small angles. This makes it possible to show that on an initially smooth surface for almost any initial conditions points with an infinite curvature corresponding to branch points of the root type can form in a finite time.Comment: 14 page

Two-parameter nonsmooth grazing bifurcations of limit cycles: classification and open problems

This paper proposes a strategy for the classification of codimension-two grazing bifurcations of limit cycles in piecewise smooth systems of ordinary differential equations. Such nonsmooth transitions (C-bifurcations) occur when the cycle interacts with a discontinuity boundary of phase space in a non-generic way. Several such codimension-one events have recently been identified, causing for example period-adding or sudden onset of chaos. Here, the focus is on codimension-two grazings that are local in the sense that the dynamics can be fully described by an appropriate Poincaré map from a neighbourhood of the grazing point (or points) of the critical cycle to itself. It is proposed that codimension-two grazing bifurcations can be divided into three distinct types: either the grazing point is degenerate, or the the grazing cycle is itself degenerate (e.g. non-hyperbolic) or we have the simultaneous occurrence of two grazing events. A careful distinction is drawn between their occurrence in systems with discontinuous states, discontinuous vector fields, or that have discontinuity in some derivative of the vector field. Examples of each kind of bifurcation are presented, mostly derived from mechanical applications. For each example, where possible, principal bifurcation curves characteristic to the codimension-two scenario are presented and general features of the dynamics discussed. Many avenues for future research are opened.

Field induced evolution of regular and random 2D domain structures and shape of isolated domains in LiNbO₃ and LiTaO₃

The shapes of isolated domains produced by application of the uniform external electric field in different experimental conditions were investigated experimentally in single crystalline lithium niobate LiNbO3 and lithium tantalate LiTaO3. The study of the domain kinetics by computer simulation and experimentally by polarization reversal of the model structure using two-dimensional regular electrode pattern confirms applicability of the kinetic approach to explanation of the experimentally observed evolution of the domain shape and geometry of the domain structure. It has been shown that the fast domain walls strictly oriented along X directions appear after domain merging

Dynamics of the Free Surface of a Conducting Liquid in a Near-Critical Electric Field

Near-critical behavior of the free surface of an ideally conducting liquid in an external electric field is considered. Based on an analysis of three-wave processes using the method of integral estimations, sufficient criteria for hard instability of a planar surface are formulated. It is shown that the higher-order nonlinearities do not saturate the instability, for which reason the growth of disturbances has an explosive character.Comment: 19 page