16,220 research outputs found

    The support of the logarithmic equilibrium measure on sets of revolution in R3\R^3

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    For surfaces of revolution BB in R3\R^3, we investigate the limit distribution of minimum energy point masses on BB that interact according to the logarithmic potential log⁑(1/r)\log (1/r), where rr is the Euclidean distance between points. We show that such limit distributions are supported only on the ``out-most'' portion of the surface (e.g., for a torus, only on that portion of the surface with positive curvature). Our analysis proceeds by reducing the problem to the complex plane where a non-singular potential kernel arises whose level lines are ellipses

    Similarity Measure Development for Case-Based Reasoning- A Data-driven Approach

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    In this paper, we demonstrate a data-driven methodology for modelling the local similarity measures of various attributes in a dataset. We analyse the spread in the numerical attributes and estimate their distribution using polynomial function to showcase an approach for deriving strong initial value ranges of numerical attributes and use a non-overlapping distribution for categorical attributes such that the entire similarity range [0,1] is utilized. We use an open source dataset for demonstrating modelling and development of the similarity measures and will present a case-based reasoning (CBR) system that can be used to search for the most relevant similar cases

    Eta Carinae across the 2003.5 Minimum: Analysis in the visible and near infrared spectral region

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    We present an analysis of the visible through near infrared spectrum of Eta Carinae and its ejecta obtained during the "Eta Carinae Campaign with the UVES at the ESO VLT". This is a part of larger effort to present a complete Eta Carinae spectrum, and extends the previously presented analyses with the HST/STIS in the UV (1240-3159 A) to 10,430 A. The spectrum in the mid and near UV is characterized by the ejecta absorption. At longer wavelengths, stellar wind features from the central source and narrow emission lines from the Weigelt condensations dominate the spectrum. However, narrow absorption lines from the circumstellar shells are present. This paper provides a description of the spectrum between 3060 and 10,430 A, including line identifications of the ejecta absorption spectrum, the emission spectrum from the Weigelt condensations and the P-Cygni stellar wind features. The high spectral resolving power of VLT/UVES enables equivalent width measurements of atomic and molecular absorption lines for elements with no transitions at the shorter wavelengths. However, the ground based seeing and contributions of nebular scattered radiation prevent direct comparison of measured equivalent widths in the VLT/UVES and HST/STIS spectra. Fortunately, HST/STIS and VLT/UVES have a small overlap in wavelength coverage which allows us to compare and adjust for the difference in scattered radiation entering the instruments' apertures. This paper provides a complete online VLT/UVES spectrum with line identifications and a spectral comparison between HST/STIS and VLT/UVES between 3060 and 3160 A.Comment: 13 pages, 11 figures + atlas. The paper accepted for the ApJS and is accompanied with an atlas in the online edition pape

    Spectroscopic and photometric oscillatory envelope variability during the S Doradus outburst of the Luminous Blue Variable R71

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    To better understand the LBV phenomenon, we analyze multi-epoch and multi-wavelength spectra and photometry of R71. Pre-outburst spectra are analyzed with the radiative transfer code CMFGEN to determine the star's fundamental stellar parameters. During quiescence, R71 has an effective temperature of Teff=15 500Β KT_\mathrm{{eff}} = 15\,500~K and a luminosity of log(Lβˆ—/LβŠ™)(L_*/L_{\odot}) = 5.78 and is thus a classical LBV, but at the lower luminosity end of this group. We determine its mass-loss rate to 4.0Γ—10βˆ’6Β MβŠ™Β 4.0 \times 10^{-6}~M_{\odot}~yrβˆ’1^{-1}. We present R71's spectral energy distribution from the near-ultraviolet to the mid-infrared during its present outburst. Mid-infrared observations suggest that we are witnessing dust formation and grain evolution. Semi-regular oscillatory variability in the star's light curve is observed during the current outburst. Absorption lines develop a second blue component on a timescale twice that length. The variability may consist of one (quasi-)periodic component with P ~ 425/850 d with additional variations superimposed. During its current S Doradus outburst, R71 occupies a region in the HR diagram at the high-luminosity extension of the Cepheid instability strip and exhibits similar irregular variations as RV Tau variables. LBVs do not pass the Cepheid instability strip because of core evolution, but they develop comparable cool, low-mass, extended atmospheres in which convective instabilities may occur. As in the case of RV Tau variables, the occurrence of double absorption lines with an apparent regular cycle may be due to shocks within the atmosphere and period doubling may explain the factor of two in the lengths of the photometric and spectroscopic cycles.Comment: 18 pages, 14 figures, submitted to A&

    Extended Magnetic Dome Induced by Low Pressures in Superconducting FeSe1-x_\mathrm{1\text{-}x}Sx_\mathrm{x}

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    We report muon spin rotation (ΞΌ\muSR) and magnetization measurements under pressure on Fe1+Ξ΄_{1+\delta}Se1-x_\mathrm{1\text{-}x}Sx_\mathrm{x} with x β‰ˆ0.11\approx 0.11.Above pβ‰ˆ0.6p\approx0.6 GPa we find microscopic coexistence of superconductivity with an extended dome of long range magnetic order that spans a pressure range between previously reported separated magnetic phases. The magnetism initially competes on an atomic scale with the coexisting superconductivity leading to a local maximum and minimum of the superconducting Tc(p)T_\mathrm{c}(p). The maximum of TcT_\mathrm{c} corresponds to the onset of magnetism while the minimum coincides with the pressure of strongest competition. A shift of the maximum of Tc(p)T_\mathrm{c}(p) for a series of single crystals with x up to 0.14 roughly extrapolates to a putative magnetic and superconducting state at ambient pressure for x β‰₯0.2\geq0.2.Comment: 10 pages, 6 figures, including supplemental materia

    Influence of Grazing on Soil Microbial Communities on a Mixed Grass Prairie Ecosystem

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    The grazing of ungulates is the predominant use for much of the world\u27s semiarid rangelands. Grazing these lands can result in significant changes not only in the vegetation community but also in the soil physical, chemical and biological properties. Changes in soil physical and chemical properties and the plant community can potentially lead to changes in soil microbial communities which may have long-term ramifications for nutrient cycling and carbon (C) sequestration. The objective of this research was to ascertain the influence of three long-term grazing treatments on soil microbial communities

    Discovery and quantitative spectral analysis of an Ofpe/WN9 (WN11) star in the Sculptor spiral galaxy NGC 300

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    We have discovered an Ofpe/WN9 (WN11 following Smith et al.) star in the Sculptor spiral galaxy NGC 300, the first object of this class found outside the Local Group, during a recent spectroscopic survey of blue supergiant stars obtained at the ESO VLT. The light curve over a five-month period in late 1999 displays a variability at the 0.1 mag level. The intermediate resolution spectra (3800-7200 A) show a very close resemblance to the Galactic LBV AG Car during minimum. We have performed a detailed non-LTE analysis of the stellar spectrum, and have derived a chemical abundance pattern which includes H, He, C, N, O, Al, Si and Fe, in addition to the stellar and wind parameters. The derived stellar properties and the He and N surface enrichments are consistent with those of other Local Group WN11 stars in the literature, suggesting a similar quiescent or post-LBV evolutionary status.Comment: 9 pages, 4 figures, 2 tables. Accepted for publication in the Astrophysical Journal Letter

    Rankings as a comprehensive model to assess innovation and investment development of mesolevel economic systems (case of Tomsk region)

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    ΠΠΊΡ‚ΡƒΠ°Π»ΡŒΠ½ΠΎΡΡ‚ΡŒ опрСдСляСтся растущим интСрСсом Π·Π°Ρ€ΡƒΠ±Π΅ΠΆΠ½Ρ‹Ρ… ΠΈ отСчСствСнных исслСдоватСлСй ΠΈ ΠΏΡ€Π°ΠΊΡ‚ΠΈΠΊΠΎΠ² ΠΊ Ρ€Π΅ΠΉΡ‚ΠΈΠ½Π³Π°ΠΌ ΠΊΠ°ΠΊ комплСксному ΠΌΠ΅Ρ‚ΠΎΠ΄Ρƒ ΠΎΡ†Π΅Π½ΠΊΠΈ инновационно‐инвСстиционого развития Ρ€Π΅Π³ΠΈΠΎΠ½ΠΎΠ². ΠŸΡ€ΠΈ этом Π½Π΅Ρ‚ Сдинства ΠΌΠ½Π΅Π½ΠΈΠΉ ΠΏΠΎ ΠΌΠ΅Ρ‚ΠΎΠ΄ΠΈΠΊΠ°ΠΌ формирования Ρ€Π΅ΠΉΡ‚ΠΈΠ½Π³ΠΎΠ², ΠΎΡ‚Π±ΠΎΡ€Π° ΠΏΠΎΠΊΠ°Π·Π°Ρ‚Π΅Π»Π΅ΠΉ ΠΈ ΠΌΠ΅Ρ‚ΠΎΠ΄ΠΎΠ² расчСта. ЦСль Ρ€Π°Π±ΠΎΡ‚Ρ‹: исслСдованиС ΠΈ Π°Π½Π°Π»ΠΈΠ· Ρ€Π΅ΠΉΡ‚ΠΈΠ½Π³ΠΎΠ² ΠΊΠ°ΠΊ ΠΌΠΎΠ΄Π΅Π»ΠΈ комплСксной ΠΎΡ†Π΅Π½ΠΊΠΈ ΠΈΠ½Π½ΠΎΠ²Π°Ρ†ΠΈΠΎΠ½Π½ΠΎΠ³ΠΎ ΠΈ инвСстиционного развития экономичСских систСм мСзоуровня. ΠœΠ΅Ρ‚ΠΎΠ΄Ρ‹ исслСдования: ΠΌΠ΅Ρ‚ΠΎΠ΄Ρ‹ ΡΡ€Π°Π²Π½ΠΈΡ‚Π΅Π»ΡŒΠ½ΠΎΠ³ΠΎ, логичСского Π°Π½Π°Π»ΠΈΠ·Π°, Π°Π½Π°Π»ΠΈΠ· ΠΈ синтСз, систСмный ΠΏΠΎΠ΄Ρ…ΠΎΠ΄. Π Π΅Π·ΡƒΠ»ΡŒΡ‚Π°Ρ‚Ρ‹. ΠŸΡ€Π΅Π΄ΡΡ‚Π°Π²Π»Π΅Π½ сравни‐ Ρ‚Π΅Π»ΡŒΠ½Ρ‹ΠΉ Π°Π½Π°Π»ΠΈΠ· российских инновационно‐инвСстиционных Ρ€Π΅ΠΉΡ‚ΠΈΠ½Π³ΠΎΠ²; рассмотрСны ΠΌΠ΅Ρ‚ΠΎΠ΄ΠΈΠΊΠΈ ΠΈΡ… составлСния ΠΈ ΠΈΡΠΏΠΎΠ»ΡŒΠ·ΡƒΠ΅ΠΌΡ‹Π΅ систСмы ΠΏΠΎΠΊΠ°Π·Π°Ρ‚Π΅Π»Π΅ΠΉ. Π‘Ρ„ΠΎΡ€ΠΌΡƒΠ»ΠΈΡ€ΠΎΠ²Π°Π½Ρ‹ ограничСния Ρ€Π΅ΠΉΡ‚ΠΈΠ½Π³Π° ΠΊΠ°ΠΊ ΠΌΠΎΠ΄Π΅Π»ΠΈ комплСксной ΠΎΡ†Π΅Π½ΠΊΠΈ Π² Ρ†Π΅Π»ΠΎΠΌ, Π΄Π°Π½Π° характСристика ΠΊΠ°ΠΆΠ΄ΠΎΠ³ΠΎ ΠΎΡ‚Π΄Π΅Π»ΡŒΠ½ΠΎΠ³ΠΎ Ρ€Π΅ΠΉΡ‚ΠΈΠ½Π³Π°. Π’ качСствС ΠΏΡ€ΠΈΠΌΠ΅Ρ€ΠΎΠ² ΠΏΡ€ΠΈΠ²Π΅Π΄Π΅Π½Ρ‹ ΠΏΠΎΠ·ΠΈΡ†ΠΈΠΈ Ρ€Π΅Π³ΠΈΠΎΠ½ΠΎΠ² Бибирского Ρ„Π΅Π΄Π΅Ρ€Π°Π»ΡŒΠ½ΠΎΠ³ΠΎ ΠΎΠΊΡ€ΡƒΠ³Π° Π² пяти российских Ρ€Π΅ΠΉΡ‚ΠΈΠ½Π³Π°Ρ….The relevance of the topic is determined by the growing interest of foreign and domestic researchers and practitioners in ratings as a comprehensive method for assessing the innovative and investment development of the regions. At the same time there is no unity of opinion on the methods of rating formation, selection of indicators and calculation methods. The aim of the study is to research and analyze ratings as a model for integrated assessment of innovation and investment development of meso‐level economic systems. Methods of research: methods of comparative, logical analysis, analysis and synthesis, systematic approach. Results. The paper introduces the comparative analysis of Russian innovation and investment ratings, considers the methods of their compilation and the system of indicators. The rating constraints are formulated as a model of integrated assessment in general, and the characteristics of each individual rating are given. The authors give the positions of the regions of the Siberian Federal District in five Russian rankings as an example

    Chandra HETGS Multi-Phase Spectroscopy of the Young Magnetic O Star theta^1 Orionis C

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    We report on four Chandra grating observations of the oblique magnetic rotator theta^1 Ori C (O5.5 V) covering a wide range of viewing angles with respect to the star's 1060 G dipole magnetic field. We employ line-width and centroid analyses to study the dynamics of the X-ray emitting plasma in the circumstellar environment, as well as line-ratio diagnostics to constrain the spatial location, and global spectral modeling to constrain the temperature distribution and abundances of the very hot plasma. We investigate these diagnostics as a function of viewing angle and analyze them in conjunction with new MHD simulations of the magnetically channeled wind shock mechanism on theta^1 Ori C. This model fits all the data surprisingly well, predicting the temperature, luminosity, and occultation of the X-ray emitting plasma with rotation phase.Comment: 52 pages, 14 figures (1 color), 6 tables. To appear in the Astrophysical Journal, 1 August 2005, v628, issue 2. New version corrects e-mail address, figure and table formatting problem
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