On Z-graded loop Lie algebras, loop groups, and Toda equations

Toda equations associated with twisted loop groups are considered. Such equations are specified by Z-gradations of the corresponding twisted loop Lie algebras. The classification of Toda equations related to twisted loop Lie algebras with integrable Z-gradations is discussed.Comment: 24 pages, talk given at the Workshop "Classical and Quantum Integrable Systems" (Dubna, January, 2007

Role of magnetic degrees of freedom in a scenario of phase transformations in steel

The diversity of mesostructures formed in steel at cooling from a high-temperature austenite ("gamma") phase is determined by the interplay of shear reconstructions of crystal lattice and diffusion of carbon. Combining first-principles calculations with large-scale phase-field simulations we demonstrate a decisive role of magnetic degrees of freedom in the formation of energy relief along the Bain path of "gamma"-"alpha" transformation and, thus, in this interplay. We show that there is the main factor, namely, the magnetic state of iron and its evolution with temperature which controls the change in character of the transformation. Based on the computational results we propose a simple model which reproduces, in good agreement with experiment, the most important curves of the phase transformation in Fe-C, namely, the lines relevant to a start of ferrite, bainite, and martensite transformations. Phase-field simulations within the model describe qualitatively typical patterns at these transformations

Free Energy of the Eight Vertex Model with an Odd Number of Lattice Sites

We calculate the bulk contribution for the doubly degenerated largest eigenvalue of the transfer matrix of the eight vertex model with an odd number of lattice sites N in the disordered regime using the generic equation for roots proposed by Fabricius and McCoy. We show as expected that in the thermodynamic limit the result coincides with the one in the N even case.Comment: 11 pages LaTeX New introduction, Method change

Dependent coordinates in path integral measure factorization

The transformation of the path integral measure under the reduction procedure in the dynamical systems with a symmetry is considered. The investigation is carried out in the case of the Wiener--type path integrals that are used for description of the diffusion on a smooth compact Riemannian manifold with the given free isometric action of the compact semisimple unimodular Lie group. The transformation of the path integral, which factorizes the path integral measure, is based on the application of the optimal nonlinear filtering equation from the stochastic theory. The integral relation between the kernels of the original and reduced semigroup are obtained.Comment: LaTeX2e, 28 page

Luminescence of LaBr3:Ce,Hf scintillation crystals under UV-VUV and X-ray excitation

The present study was carried out by means of the low temperature time-resolved luminescence UV–VUV spectroscopy as well as the optical and thermally activation spectroscopy. The Ce3+ centers in regular lattice sites and located in the vicinity of the point defects of crystal structure were observed. Spectral and kinetic characteristics of the luminescence of these centers were defined. A photoluminescence of new point defects of the crystal structure are also manifested. We evaluated the energy of the interband transitions as Eg ≈ 6.2 eV in LaBr3. At the excitation energies Eexc>13 eV (higher than 2Eg) the effect of the electronic excitations multiplication was detected

A comparative study of replicative properties of antitumor recombinant vaccinia viruses on human glioblastoma cell culture U87 and monkey kidney cell culture CV-1

In the world of today, virotherapy is one of the rapidly developing areas in the treatment of cancer, and its advantage is selective destruction of cancer cells with minimizing the destructive effect on normal cells of the body. A promising basis for the creation of oncolytic drugs is orthopoxviruses, which have a number of advantages over other viral vectors, and one of these advantages is a large capacity of the genome, which allows genes encoding proteins with antitumor properties to be cloned into their genome. In this study, we compared the replicative properties of ten variants of vaccinia virus (the strain LIVP of VACV) using human glioblastoma cell culture; some of these viruses have additional genes, such as the gene encoding granulocyte-macrophage colony stimulating factor, gene encoding apoptosis-inducing protein TRAIL and gene encoding green fluorescent protein. Furthermore, the virus with five virulence genes deleted (genes encoding hemagglutinin, γ-interferonbinding protein, thymidine kinase, complementbinding protein and Bcl2-like inhibitor of apoptosis), which has significantly lower reactogenicity and neurovirulence compared to the original strain LIVP of VACV, was studied. These data suggest that variants of vaccinia virus with a defective gene encoding thymidine kinase most actively replicate in glioblastoma cell culture

Asymptotics of Toeplitz Determinants and the Emptiness Formation Probability for the XY Spin Chain

We study an asymptotic behavior of a special correlator known as the Emptiness Formation Probability (EFP) for the one-dimensional anisotropic XY spin-1/2 chain in a transverse magnetic field. This correlator is essentially the probability of formation of a ferromagnetic string of length $n$ in the antiferromagnetic ground state of the chain and plays an important role in the theory of integrable models. For the XY Spin Chain, the correlator can be expressed as the determinant of a Toeplitz matrix and its asymptotical behaviors for $n \to \infty$ throughout the phase diagram are obtained using known theorems and conjectures on Toeplitz determinants. We find that the decay is exponential everywhere in the phase diagram of the XY model except on the critical lines, i.e. where the spectrum is gapless. In these cases, a power-law prefactor with a universal exponent arises in addition to an exponential or Gaussian decay. The latter Gaussian behavior holds on the critical line corresponding to the isotropic XY model, while at the critical value of the magnetic field the EFP decays exponentially. At small anisotropy one has a crossover from the Gaussian to the exponential behavior. We study this crossover using the bosonization approach.Comment: 40 pages, 9 figures, 1 table. The poor quality of some figures is due to arxiv space limitations. If You would like to see the pdf with good quality figures, please contact Fabio Franchini at "[email protected]

Effects of radiation and manganese oxide nanoparticles on human glioblastoma cell line U-87 MG glycolysis

Gliomas are the most common type of malignant brain tumors. Standard treatment of gliomas consists of surgical excision of the tumor with subsequent chemotherapy and radiotherapy. Tumor cells are characterized by rapid division with an increased uptake of glucose and its catabolism during glycolysis. To maintain rapid division, the level of glycolysis of the tumor cell is significantly increased, compared with normal cells. It is known that some nanoparticles (NP) have the property of accumulating in tumors. In particular, NPs of manganese oxide can penetrate into the brain and, with considerable accumulation, cause toxic effects. These facts served as a prerequisite for studying the effects of manganese oxide NPs on the viability of glioma cells. The purpose of this work was to study the effects of manganese oxide NPs, as well as their combination with gamma irradiation on the glycolysis of glioma cells. The cells were irradiated using the research radiobiological gamma-installation IGUR-1 based on 137Cs. The level of cell glycolysis was determined using the standard glycolytic stress test on a Seahorse XFp platform. Cell viability was determined using the ViaCount reagent staining of living and dead cells. Their count was performed using flow cytometry. We showed that the glycolysis of U-87 MG glioma cells was significantly reduced when incubated for 48 hours with manganese oxide NPs. Irradiation in combination with NPs or alone did not have significant effects on glycolysis of gliomas. Glioma incubation with manganese oxide NPs for 72 hours led to a significant reduction in cell viability. This study may be useful for the development of new therapies and diagnosis of gliomas