Robotised program conducting out laboratory works of chemistry

In a message addressed the conditions necessary and sufficient for creating robotised program for laboratory work in chemistry as an element of innovation-axiological approach in educationВ сообщении рассмотрены условия необходимые и достаточные для создания роботизированной программы проведения лабораторных работ по химии как элемента инновационно-аксиологического подхода в образовани

Weakly Interacting, Dilute Bose Gases in 2D

This article surveys a number of theoretical problems and open questions in the field of two-dimensional dilute Bose gases with weak repulsive interactions. In contrast to three dimensions, in two dimensions the formation of long-range order is prohibited by the Bogoliubov-Hohenberg theorem, and Bose-Einstein condensation is not expected to be realized. Nevertheless, first experimental indications supporting the formation of the condensate in low dimensional systems have been recently obtained. This unexpected behaviour appears to be due to the non-uniformity, introduced into a system by the external trapping potential. Theoretical predictions, made for homogeneous systems, require therefore careful reexamination. We survey a number of popular theoretical treatments of the dilute weakly interacting Bose gas and discuss their regions of applicability. The possibility of Bose-Einstein condensation in a two-dimensional gas, the validity of perturbative t-matrix approximation and diluteness condition are issues that we discuss in detail.Comment: Survey, 25 pages RMP style, revised version, refs added, some changes made, accepted for publication in Rev. Mod. Phy

The twisted XXZ chain at roots of unity revisited

The symmetries of the twisted XXZ spin-chain (alias the twisted six-vertex model) at roots of unity are investigated. It is shown that when the twist parameter is chosen to depend on the total spin an infinite-dimensional non-abelian symmetry algebra can be explicitly constructed for all spin sectors. This symmetry algebra is identified to be the upper or lower Borel subalgebra of the sl_2 loop algebra. The proof uses only the intertwining property of the six-vertex monodromy matrix and the familiar relations of the six-vertex Yang-Baxter algebra.Comment: 10 pages, 2 figures. One footnote and some comments in the conclusions adde

Technical constraints on interstellar interferometry and spatially resolving the pulsar magnetosphere

Scintillation of pulsar radio signals caused by the interstellar medium can in principle be used for interstellar interferometry. Changes of the dynamic spectra as a function of pulsar longitude were in the past interpreted as having spatially resolved the pulsar magnetosphere. Guided by this prospect we used VLBI observations of PSR B1237+25 with the Arecibo and Green Bank radio telescopes at 324 MHz and analyzed such scintillation at separate longitudes of the pulse profile. We found that the fringe phase characteristics of the visibility function changed quasi-sinusoidally as a function of longitude. Also, the dynamic spectra from each of the telescopes shifted in frequency as a function of longitude. Similar effects were found for PSR B1133+16. However, we show that these effects are not signatures of having resolved the pulsar magnetosphere. Instead the changes can be related to the effect of low-level digitizing of the pulsar signal. After correcting for these effects the frequency shifts largely disappeared. Residual effects may be partly due to feed polarization impurities. Upper limits for the pulse emission altitudes of PSR B1237+25 would likely be well below the pulsar light cylinder radius. In view of our analysis we think that observations with the intent of spatially resolving the pulsar magnetosphere need to be critically evaluated in terms of these constraints on interstellar interferometry.Comment: 19 pages, 11 figures, published in The Astrophysical Journa

Peculiarities and variations in the optical spectrum of the post-AGB star V448Lac=IRAS22223+4327

Repeated observations with high spectral resolution acquired in 1998-2008 are used to study the temporal behavior of the spectral line profiles and velocity field in the atmosphere and circumstellar envelope of the post-AGB star V448Lac. Asymmetry of the profiles of the strongest absorption lines with low-level excitation potentials less 1eV and time variations of these profiles have been detected, most prominently the profiles of the resonance lines of BaII, YII, LaII, SiII. The peculiarity of these profiles can be explained using a superposition of stellar absorption line and shell emission lines. Emission in the (0;1) 5635A Swan band of the C2 molecule has been detected in the spectrum of V448Lac for the first time. The core of the Halpha line displays radial velocity variations with an amplitude ~8 km/s. Radial velocity variations displayed by weakest metallic lines with lower amplitudes, 1-2 km/s, may be due to atmospheric pulsations. Differential line shifts, 0 -- 8 km/s, have been detected on various dates. The position of the molecular spectrum is stationary in time, indicating a constant expansion velocity of the circumstellar shell, Vexp=15.2 km/s, as derived from the C2 and NaI lines.Comment: 19 pages, 8 figures, 1 tabl

Application of stem cells in guided bone regeneration

Modern medicine allows us to study and develop materials and methods of restorative treatment that would be based on the immunological mechanisms of bone repair. One of the promising directions in guided bone regeneration is the use of mesenchymal stem cells. Interest in MSCs is associated with their ability to regulate the inflammatory process, and directly participate in the formation of new bone structures, thereby providing a physiological repair process. The effector impact of MSCs on the inflammatory process due to their ability to form a specific microenvironment. Low expression of MHC-II and CD80/CD86, the production of PGE2 and NO determines their low immunoconflict, and the production of TGF-b1, IDO and IL-10 has an immunomodulating effect. The ability of MSCs to differentiate into an osteogenic phenotype is accompanied with the synthesis of ALP, BSP and, subsequently, Gla-protein and OPN determine the synthesis of the extracellular matrix and its subsequent mineralization. This process is provided by the action of Runx2, which activates the differentiation of MSCs along the osteogenic pathway. These effects of MSCs were taken as the basis for the development of a new method for the treatment of bone atrophy. To accomplish the task set, a model of bone tissue atrophy and a drug containing MSCs was developed, and an experimental study was conducted to evaluate the effectiveness of the developed methodology. As the main criteria, data from clinical and laboratory studies were taken. Visual changes in the studied area were taken into account, compared with a similar area in the developed model of atrophy, the parameters of the complete blood count (CBC) were evaluated. The performed study allows us to determine the developed treatment method as capable of fully recreating the conditions of bone repair processes, taking into account the optimization of the body’s immune reactions and repair processes, without additional external influence, to obtain predictable and controllable results