A convective model of a roton

A convective model describing the nature and structure of the roton is proposed. According to the model, the roton is a cylindrical convective cell with free horizontal boundaries. On the basis of the model, the characteristic geometric dimensions of the roton are estimated, and the spatial distribution of the velocity of the helium atoms and the perturbed temperature inside are described. It is assumed that the spatial distribution of rotons has a horizontally multilayer periodic structure, from which follows the quantization of the energy spectrum of rotons. The noted quantization allows us to adequately describe the energy spectrum of rotons. The convective model is quantitatively confirmed by experimental data on the measurement of the density of the normal component of helium II, the scattering of neutrons and light by helium II. The use of a convective model for describing the scattering of light by Helium II made it possible to estimate the dipole moment of the roton, as well as the number of helium atoms participating in the formation of the roton.Comment: 17 pages, 6 figure

Tkachenko modes as sources of quasiperiodic pulsar spin variations

We study the long wavelength shear modes (Tkachenko waves) of triangular lattices of singly quantized vortices in neutron star interiors taking into account the mutual friction between the superfluid and the normal fluid and the shear viscosity of the normal fluid. The set of Tkachenko modes that propagate in the plane orthogonal to the spin vector are weakly damped if the coupling between the superfluid and normal fluid is small. In strong coupling, their oscillation frequencies are lower and are undamped for small and moderate shear viscosities. The periods of these modes are consistent with the observed ~100-1000 day variations in spin of PSR 1828-11.Comment: 7 pages, 3 figures, uses RevTex, v2: added discussion/references, matches published versio

Energy losses of fast heavy-ion projectiles in dense hydrogen plasmas

It has been recently shown that the Bethe-Larkin formula for the energy losses of fast heavy-ion projectiles in dense hydrogen plasmas is corrected by the electron-ion correlations [Phys. Rev. Lett. \textbf{101}, 075002 (2008)]. We report numerical estimates of this correction based on the values of $g_{ei}(0)$ obtained by numerical simulations in [Phys. Rev. E \textbf{61}, 3470 (2000)]. We also extend this result to the case of projectiles with dicluster charge distribution. We show that the experimental visibility of the electron-ion correlation correction is enhanced in the case of dicluster projectiles with randomly orientated charge centers. Although we consider here the hydrogen plasmas to make the effect physically more clear, the generalization to multispecies plasmas is straightforward.Comment: 5 pages, 1 figure. International Conference on Strongly Coupled Coulomb Systems 2008, Camerino (Italy). To appear in J. Phys.

The significance of angiogenesis in tumorigenesis and prognosis of prostate cancer

Angiogenesis is a key factor in tumor growth, invasion, and metastasis. The aim of the present study is to investigate the diagnostic and predictive value of prostatic cancer (PC) angiogenesis by immunohistochemically examination of CD34, VEGF and Ki-67 in40 cases of PC, 8 cases of nodular hyperplasia and 8 cases of intraepithelial neoplasia. It was found that the density of microvessels and intensity data of stroma but not epithelium VEGF staining in PC more than in benign pathology, and increased with risk of recurrence and as the differentiation of cancer was reduced. Results indicate that the vascularization is a sign of growth and progression of PC and may be used as predictor of the disease

Influence of equation of state on interpretation of electrical conductivity measurements in strongly coupled tungsten plasma

We study the influence of equation-of-state (EOS) model on the interpretation of electrical conductivity measurements in strongly coupled plasma of tungsten by Korobenko et al. (2002 Plasma Physics Reports 28(12) 1008--1016). Three different semiempirical EOS models for tungsten are used. Discrepancies in obtained thermodynamic parameters and specific resistivity values as compared with calculation results of Korobenko et al. are analysed.Comment: 11 pages, 5 Postscript figures, accepted for publication in J. Phys. A: Math. Ge

«Forgotten Shadow» Panteleymon Kulish

У статті розглянуто роль і місце Ганни Барвінок в історії української літератури другої половини ХІХ ст. та її місію у творчій біографії П. Куліша.In the article Hanna Barvinok’s role and place in the history of Ukrainian literature of the second half of the nineteenth century are considered and her mission in creative activity of

Multiple Local σ-aromaticity of Nonagermanide Clusters

Nonagermanide clusters are widely used in inorganic synthesis and are actively studied by experimentalists and theoreticians. However, chemical bonding of such versatile species is still not completely understood. In our work we deciphered a bonding pattern for various experimentally obtained nonagermanide species. We localized the electron density via the AdNDP algorithm for the model structures ([Ge9]4−, [Ge9{P(NH2)2}3]−, Cu[Ge9{P(NH2)2}3] and Cu(NHC)[Ge9{P(NH2)2}3]) and obtained a simple and chemically intuitive bonding pattern which can explain the variety of active sites and the existence of both D3h and C4v geometries for such clusters. Moreover, the [Ge9]4− core is found to be a unique example of an inorganic Zintl cluster with multiple local σ-aromaticity