The Evolution of NGC 7027 at Radio Frequencies: A New Determination of the Distance and Core Mass

We present the results of a 25-year program to monitor the radio flux evolution of the planetary nebula NGC7027. We find significant evolution of the spectral flux densities. The flux density at 1465 MHz, where the nebula is optically thick, is increasing at a rate of 0.251+-0.015 % per year, caused by the expansion of the ionized nebula. At frequencies where the emission is optically thin, the spectral flux density is changing at a rate of -0.145+-0.005 % per year, caused by a decrease in the number of ionizing photons coming from the central star. A distance of 980+-100 pc is derived. By fitting interpolated models of post-AGB evolution to the observed changes, we find that over the 25-yr monitoring period, the stellar temperature has increased by 3900+-900 K and the stellar bolometric luminosity has decreased by 1.75+-0.38 %. We derive a distance-independent stellar mass of 0.655+-0.01 solar masses adopting the Bloecker stellar evolution models, or about 0.04 solar masses higher when using models of Vassiliadis & Wood which may provide a better fit. A Cloudy photoionization model is used to fit all epochs at all frequencies simultaneously. The differences between the radio flux density predictions and the observed values show some time-independent residuals of typically 1 %. A possible explanation is inaccuracies in the radio flux scale of Baars et al. We propose an adjustment to the flux density scale of the primary radio flux calibrator 3C286, based on the Cloudy model of NGC7027. We also calculate precise flux densities for NGC7027 for all standard continuum bands used at the VLA, as well as for some new 30GHz experiments.Comment: submitted to the Astrophysical Journa

Perturbation theory for self-gravitating gauge fields I: The odd-parity sector

A gauge and coordinate invariant perturbation theory for self-gravitating non-Abelian gauge fields is developed and used to analyze local uniqueness and linear stability properties of non-Abelian equilibrium configurations. It is shown that all admissible stationary odd-parity excitations of the static and spherically symmetric Einstein-Yang-Mills soliton and black hole solutions have total angular momentum number $\ell = 1$, and are characterized by non-vanishing asymptotic flux integrals. Local uniqueness results with respect to non-Abelian perturbations are also established for the Schwarzschild and the Reissner-Nordstr\"om solutions, which, in addition, are shown to be linearly stable under dynamical Einstein-Yang-Mills perturbations. Finally, unstable modes with $\ell = 1$ are also excluded for the static and spherically symmetric non-Abelian solitons and black holes.Comment: 23 pages, revtex, no figure

The MRAMOR Workstation

Abstract. The paper describes the experience of creating the MRAMOR workstation in 1980-1987, a quality workspace for the publishing business built on a weak element basis. The aim of the work consisted in the creation of hardand-software foundation and a system of workspaces for professional publishers. This accounted for the initially complex approach to the problem, which combined hardware, software, font, and visual design. We produced a pilot batch of forty workspaces, basic program software for the station, and application software for workspaces of professional publishing systems for electronic publication preparation. These convenient and highly effective workspaces went into test operation and they served to produce a large number of publications of high polygraph quality

Stable monopole and dyon solutions in the Einstein-Yang-Mills theory in asymptotically anti-de Sitter Space

A continuum of new monopole and dyon solutions in the Einstein-Yang-Mills theory in asymptotically anti-de Sitter space are found. They are regular everywhere and specified with their mass, and non-Abelian electric and magnetic charges. A class of monopole solutions which have no node in non-Abelian magnetic fields are shown to be stable against spherically symmetric linear perturbations.Comment: 9 pages with 5 figures. Revised version. To appear in Phys Rev Let

Advanced Hough-based method for on-device document localization

The demand for on-device document recognition systems increases in conjunction with the emergence of more strict privacy and security requirements. In such systems, there is no data transfer from the end device to a third-party information processing servers. The response time is vital to the user experience of on-device document recognition. Combined with the unavailability of discrete GPUs, powerful CPUs, or a large RAM capacity on consumer-grade end devices such as smartphones, the time limitations put significant constraints on the computational complexity of the applied algorithms for on-device execution. In this work, we consider document location in an image without prior knowledge of the document content or its internal structure. In accordance with the published works, at least 5 systems offer solutions for on-device document location. All these systems use a location method which can be considered Hough-based. The precision of such systems seems to be lower than that of the state-of-the-art solutions which were not designed to account for the limited computational resources. We propose an advanced Hough-based method. In contrast with other approaches, it accounts for the geometric invariants of the central projection model and combines both edge and color features for document boundary detection. The proposed method allowed for the second best result for SmartDoc dataset in terms of precision, surpassed by U-net like neural network. When evaluated on a more challenging MIDV-500 dataset, the proposed algorithm guaranteed the best precision compared to published methods. Our method retained the applicability to on-device computations.Comment: This is a preprint of the article submitted for publication in the journal "Computer Optics

Porous matrixes based on ion-irradiated polymer as templates for synthesis of nanowires

Irradiation with swift heavy ions is usually used for production of track membranes (nuclear filters). These membranes traditionally used as filters for fine filtration in medicine and biology. Another application is matrixes for so called matrix synthesis. The idea of this technique is to fill pores by any desired material- metal,polymer, semiconductor and so on. This work is devoted to formation of membrane for template synthesis, to investigation of filling process and to study some properties of obtained structures. It was found that filtration track membranes are not the best material for template synthesis –another type of matrixes are needed- with different pores profiles and parallel pores orientation These parameters could be obtained during irradiation. Different types of etching gave possibility to vary by will the shape of the pores and to obtain pores with conical shape. The process of etching in the alkali solution in mixture of water and alcohol was investigated. The main part of the work devoted to fabrication of micro- and nanowires via electrodeposition. Different types of metals-copper, silver, cobalt and nickel were used for galvanic deposition of the pores. Two types of the processes- galvanostatic and potentiostatic were investigated. It was also demonstrated that obtained metallic nanowires could be used as the substrates for deposition of the probe (biological molecules) in mass-spectrometer. The application of such structures in non-linear optic was also described. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/2083

Monopoles, Dyons and Black Holes in the Four-Dimensional Einstein-Yang-Mills Theory

A continuum of monopole, dyon and black hole solutions exist in the Einstein-Yang-Mills theory in asymptotically anti-de Sitter space. Their structure is studied in detail. The solutions are classified by non-Abelian electric and magnetic charges and the ADM mass. The stability of the solutions which have no node in non-Abelian magnetic fields is established. There exist critical spacetime solutions which terminate at a finite radius, and have universal behavior. The moduli space of the solutions exhibits a fractal structure as the cosmological constant approaches zero.Comment: 36 Pages, 16 Figures. Minor typos corrected and one figure modifie

Gravitating sphalerons and sphaleron black holes in asymptotically anti-de Sitter spacetime

Numerical arguments are presented for the existence of spherically symmetric regular and black hole solutions of the EYMH equations with a negative cosmological constant. These solutions approach asymptotically the anti-de Sitter spacetime. The main properties of the solutions and the differences with respect to the asymptotically flat case are discussed. The instability of the gravitating sphaleron solutions is also proven.Comment: 30 pages, LaTeX, 8 Encapsulated PostScript figure

Excitations in the Halo Nucleus He-6 Following The Li-7(gamma,p)He-6 Reaction

A broad excited state was observed in 6-He with energy E_x = 5 +/- 1 MeV and width Gamma = 3 +/- 1 MeV, following the reaction Li-7(gamma,p)He-6. The state is consistent with a number of broad resonances predicted by recent cluster model calculations. The well-established reaction mechanism, combined with a simple and transparent analysis procedure confers considerable validity to this observation.Comment: 3 pages of LaTeX, 3 figures in PostScript, approved for publication in Phys. Rev. C, August, 200

On the topological classification of binary trees using the Horton-Strahler index

The Horton-Strahler (HS) index $r=\max{(i,j)}+\delta_{i,j}$ has been shown to be relevant to a number of physical (such at diffusion limited aggregation) geological (river networks), biological (pulmonary arteries, blood vessels, various species of trees) and computational (use of registers) applications. Here we revisit the enumeration problem of the HS index on the rooted, unlabeled, plane binary set of trees, and enumerate the same index on the ambilateral set of rooted, plane binary set of trees of $n$ leaves. The ambilateral set is a set of trees whose elements cannot be obtained from each other via an arbitrary number of reflections with respect to vertical axes passing through any of the nodes on the tree. For the unlabeled set we give an alternate derivation to the existing exact solution. Extending this technique for the ambilateral set, which is described by an infinite series of non-linear functional equations, we are able to give a double-exponentially converging approximant to the generating functions in a neighborhood of their convergence circle, and derive an explicit asymptotic form for the number of such trees.Comment: 14 pages, 7 embedded postscript figures, some minor changes and typos correcte