17 research outputs found

    Classification of (1,2)(1{,}2)-reflective anisotropic hyperbolic lattices of rank 44

    Get PDF
    A hyperbolic lattice is called \textit{(1,2)(1{,}2)-reflective} if its automorphism group is generated by 11- and 22-reflections up to finite index. In this paper we prove that the fundamental polyhedron of a Q\mathbb{Q}-arithmetic cocompact reflection group in the three-dimensional Lobachevsky space contains an edge such that the distance between its framing faces is small enough. Using this fact we obtain a classification of (1,2)(1{,}2)-reflective anisotropic hyperbolic lattices of rank 44.Comment: 17 pages, 5 figures, 1 table. arXiv admin note: text overlap with arXiv:1610.0614

    Arithmetic trialitarian hyperbolic lattices are not LERF

    Full text link
    A group is LERF (locally extended residually finite) if all its finitely generated subgroups are separable. We prove that the trialitarian arithmetic lattices in PSO7,1(R)\mathbf{PSO}_{7,1}(\mathbb{R}) are not LERF. This result, together with previous work by the third author, implies that all arithmetic lattices in POn,1(R)\mathbf{PO}_{n,1}(\mathbb{R}), n>3n>3, are not LERF.Comment: 8 pages, 1 figur

    Arithmeticity of ideal hyperbolic right-angled polyhedra and hyperbolic link complements

    Full text link
    In this paper we provide a generalized construction of nonarithmetic hyperbolic orbiifolds in the spirit of Gromov and Piatetski-Shapiro. Nonarithmeticity of such orbifolds is based on recently obtained results connecting a behaviour of the so-called fc-subspaces (totally geodesic subspaces fixed by finite order elements of the commensurator) with arithmetic properties of hyperbolic orbifolds and manifolds. As an application, we verify arithmeticity of some particular class of ideal hyperbolic right-angled 33-polyhedra and hyperbolic link complements.Comment: 7 pages, 3 figure

    OPERATION MODES AND CHARACTERISTICS OF PLASMA DIPOLE ANTENNA

    Get PDF
    Existence modes of  surface electromagnetic wave on a plasma cylinder, operating modes and characteristics of the plasma antenna were studied in this paper. Solutions of the dispersion equation of surface wave were obtained for a plasma cylinder with finite radius for different plasma density values. Operation modes of the plasma asymmetric dipole antenna with finite length and radius were researched by numerical simulation. The electric field distributions of  the plasma antenna in near antenna field and the radiation pattern were obtained. These characteristics were compared to characteristics of the similar metal antenna. Numerical models verification was carried out by comparing of the counted and measured metal antenna radiation patterns

    Computer Simulation of a Plasma Vibrator Antenna

    Get PDF
    The use of new plasma technologies in antenna technology is widely discussed nowadays. The plasma antenna must receive and transmit signals in the frequency range of a transceiver. Many experiments have been carried out with plasma antennas to transmit and receive signals. Due to lack of experimental data and because experiments are difficult to carry out, there is a need for computer (numerical) modeling to calculate the parameters and characteristics of antennas, and to verify the parameters for future studies. Our study has modeled plasma vibrator (dipole) antennas (PDA) and metal vibrator (dipole) antennas (MDA), and has calculated the characteristics of PDAs and MDAs in the full KARAT electro-code. The correctness of the modeling has been tested by calculating a metal antenna using the MMANA program

    KORTES Mission for Solar Activity Monitoring Onboard International Space Station

    Full text link
    peer reviewedWe present a description of the recent advances in the development of the KORTES assembly—the first solar oriented mission designed for the Russian segment of the International Space Station. KORTES consists of several imaging and spectroscopic instruments collectively covering a wide spectral range extending from extreme ultraviolet (EUV) wavelengths to X-rays. The EUV telescopes inside KORTES will trace the origin and dynamics of various solar phenomena, e.g., flares, CMEs, eruptions etc. EUV spectra provided by grazing-incidence spectroheliographs will enable precise DEM-diagnostics during these events. The monochromatic X-ray imager will observe the formation of hot plasma in active regions and outside them. The SolpeX module inside KORTES will offer an opportunity to measure fluxes, Doppler shifts and polarization of soft X-ray emission both in lines and continuum. SolpeX observations will contribute to studies of particle beams and chromospheric evaporation. The instrumentation of KORTES will employ a variety of novel multilayer and crystal optics. The deployment of KORTES is planned for 2024

    Cancer Stem Cells: Emergent Nature of Tumor Emergency

    Get PDF
    A functional analysis of 167 genes overexpressed in Krebs-2 tumor initiating cells was performed. In the first part of the study, the genes were analyzed for their belonging to one or more of the three groups, which represent the three major phenotypic manifestation of malignancy of cancer cells, namely (1) proliferative self-sufficiency, (2) invasive growth and metastasis, and (3) multiple drug resistance. 96 genes out of 167 were identified as possible contributors to at least one of these fundamental properties. It was also found that substantial part of these genes are also known as genes responsible for formation and/or maintenance of the stemness of normal pluri-/multipotent stem cells. These results suggest that the malignancy is simply the ability to maintain the stem cell specific genes expression profile, and, as a consequence, the stemness itself regardless of the controlling effect of stem niches. In the second part of the study, three stress factors combined into the single concept of “generalized cellular stress,” which are assumed to activate the expression of these genes, were defined. In addition, possible mechanisms for such activation were identified. The data obtained suggest the existence of a mechanism for the de novo formation of a pluripotent/stem phenotype in the subpopulation of “committed” tumor cells

    Kleinian sphere packings, reflection groups, and arithmeticity

    Full text link
    In this paper we study crystallographic sphere packings and Kleinian sphere packings, introduced first by Kontorovich and Nakamura in 2017 and then studied further by Kapovich and Kontorovich in 2021. In particular, we solve the problem of existence of crystallographic sphere packings in certain higher dimensions posed by Kontorovich and Nakamura. In addition, we present a geometric doubling procedure allowing to obtain sphere packings from some Coxeter polyhedra without isolated roots, and study "properly integral" packings (that is, ones which are integral but not superintegral).Comment: 18 pages, 3 figures; ancillary files available on Github https://github.com/sashakolpakov/crystallographic-packing
    corecore