8,083 research outputs found

    Nuclear magnetic octupole moment and the hyperfine structure of the 5D3/2,5/25D_{3/2,5/2} states of the Ba+^+ ion

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    The hyperfine structure of the long-lived 5D3/25D_{3/2} and 5D5/25D_{5/2} levels of Ba+^+ ion is analyzed. A procedure for extracting relatively unexplored nuclear magnetic moments Ω\Omega is presented. The relevant electronic matrix elements are computed in the framework of the ab initio relativistic many-body perturbation theory. Both the first- and the second-order (in the hyperfine interaction) corrections to the energy levels are analyzed. It is shown that a simultaneous measurement of the hyperfine structure of the entire 5DJ5D_J fine-structure manifold allows one to extract Ω\Omega without contamination from the second-order corrections. Measurements to the required accuracy should be possible with a single trapped barium ion using sensitive techniques already demonstrated in Ba+^+ experiments.Comment: Phys Rev A in pres

    Introduction of vocational standards: are there alternative ways?

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    The purpose of this article is to analyze approaches to the development of vocational standards abroad. The authors consider the most alternative approaches of a number of the countries that traditionally have no vocational standards; compare advantages and shortcomings of different approaches in the description of skill standards; show advantages of the use of vocational standards or equivalent documents in different countries; disclose the reasons behind various approaches to labor standardization. The article uses the comparative study method based on the review of home experience of qualifications system development in Soviet and foreign practices. The authors have used the methods of collecting empirical information on approaches to qualifications characteristics in modern vocational standards, URSG, UJEC and in documents of a number of European states; methods of conceptual and terminological analysis, interpretation and modelling, problem method that have yielded the following results: identification of peculiarities of the method of the development of Russian vocational standards, description of arising risks oftheir application and planning the ways to overcome them. Science novelty of the work consists in consistent justification of possibilities and limitations in the application of foreign experiences in Russia. Practical importance consists in justification of advantages of the application of vocational standards in Russia and abroad.Keywords: national qualification system; vocational standards; professional education and trainin

    Optical polarisation variability of radio loud narrow line Seyfert 1 galaxies. Search for long rotations of the polarisation plane

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    Narrow line Seyfert 1 galaxies (NLSy1s) constitute the AGN subclass associated with systematically smaller black hole masses. A few radio loud ones have been detected in MeV -- GeV energy bands by Fermi and evidence for the presence of blazar-like jets has been accumulated. In this study we wish to quantify the temporal behaviour of the optical polarisation, fraction and angle, for a selected sample of radio loud NLSy1s. We also search for rotations of the polarisation plane similar to those commonly observed in blazars. We have conducted R-band optical polarisation monitoring of a sample of 10 RL NLSy1s 5 of which have been previously detected by Fermi. The dataset includes observations with the RoboPol, KANATA, Perkins and Steward polarimeters. In the cases where evidences for long rotations of the polarisation plane are found, we carry out numerical simulations to assess the probability that they are caused by intrinsically evolving EVPAs instead of observational noise. Even our moderately sampled sources show indications of variability, both in polarisation fraction and angle. For the four best sampled objects in our sample we find multiple periods of significant polarisation angle variability. In the two best sampled cases, namely J1505+0326 and J0324+3410, we find indications for three long rotations. We show that although noise can induce the observed behaviour, it is much more likely that the apparent rotation is caused by intrinsic evolution of the EVPA. To our knowledge this is the very first detection of such events in this class of sources. In the case of the largest dataset (J0324+3410) we find that the EVPA concentrates around a direction which is at 49.3\degr to the 15-GHz radio jet implying a projected magnetic field at an angle of 40.7\degr to that axis.Comment: Accepted for publication in section 2. Astrophysical processes of Astronomy and Astrophysic

    Measurement of Lande g factor of 5D5/2 state of BaII with a single trapped ion

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    We present the first terrestrial measurement of the Lande g factor of the 5D5/2 state of singly ionized barium. Measurements were performed on single Doppler-cooled 138Ba+ ions in a linear Paul trap. A frequency-stabilized fiber laser with nominal wavelength 1.762 um was scanned across the 6S1/25D5/2 transition to spectroscopically resolve transitions between Zeeman sublevels of the ground and excited states. From the relative positions of the four narrow transitions observed at several different values for the applied magnetic field, we find a value of 1.2020+/-0.0005 for g of 5D5/2.Comment: 3 figure

    Coherent Excitation of the 6S1/2 to 5D3/2 Electric Quadrupole Transition in 138Ba+

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    The electric dipole-forbidden, quadrupole 6S1/2 5D3/2 transition in Ba+ near 2051 nm, with a natural linewidth of 13 mHz, is attractive for potential observation of parity non-conservation, and also as a clock transition for a barium ion optical frequency standard. This transition also offers a direct means of populating the metastable 5D3/2 state to measure the nuclear magnetic octupole moment in the odd barium isotopes. Light from a diode-pumped, solid state Tm,Ho:YLF laser operating at 2051 nm is used to coherently drive this transition between resolved Zeeman levels in a single trapped 138Ba+ ion. The frequency of the laser is stabilized to a high finesse Fabry Perot cavity at 1025 nm after being frequency doubled. Rabi oscillations on this transition indicate a laser-ion coherence time of 3 ms, most likely limited by ambient magnetic field fluctuations.Comment: 5 pages, 5 figure

    2-aminoaethanesulfonic acid compounds possess protective property in reperfusion-induced heart jnjury

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    The study aim was to explore pharmacological effects of 2-aminoaethansulfonic acid compounds in reperfusion-induced heart injury. The study was performed on rats and dogs of both sexes, isolated rats’ hearts. Two compounds of 2-aminoethanesulfonic acid, magnesium-containing (LBK-527) and phenylacetamide-containing (LKhT-317) were investigate

    Radio jet emission from GeV-emitting narrow-line Seyfert 1 galaxies

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    We studied the radio emission from four radio-loud and gamma-ray-loud narrow-line Seyfert 1 galaxies. The goal was to investigate whether a relativistic jet is operating at the source, and quantify its characteristics. We relied on the most systematic monitoring of such system in the cm and mm radio bands which is conducted with the Effelsberg 100 m and IRAM 30 m telescopes and covers the longest time-baselines and the most radio frequencies to date. We extract variability parameters and compute variability brightness temperatures and Doppler factors. The jet powers were computed from the light curves to estimate the energy output. The dynamics of radio spectral energy distributions were examined to understand the mechanism causing the variability. All the sources display intensive variability that occurs at a pace faster than what is commonly seen in blazars. The flaring events show intensive spectral evolution indicative of shock evolution. The brightness temperatures and Doppler factors are moderate, implying a mildly relativistic jet. The computed jet powers show very energetic flows. The radio polarisation in one case clearly implies a quiescent jet underlying the recursive flaring activity. Despite the generally lower flux densities, the sources appear to show all typical characteristics seen in blazars that are powered by relativistic jets.Comment: Accepted for publication in 4 - Extragalactic astronomy of Astronomy and Astrophysic

    Search for AGN counterparts of unidentified Fermi-LAT sources with optical polarimetry: Demonstration of the technique

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    The third Fermi-LAT catalog (3FGL) presented the data of the first four years of observations from the Fermi Gamma-ray Space Telescope mission. There are 3034 sources, 1010 of which still remain unidentified. Identifying and classifying gamma-ray emitters is of high significance with regard to studying high-energy astrophysics. We demonstrate that optical polarimetry can be an advantageous and practical tool in the hunt for counterparts of the unidentified gamma-ray sources (UGSs). Using data from the RoboPol project, we validated that a significant fraction of active galactic nuclei (AGN) associated with 3FGL sources can be identified due to their high optical polarization exceeding that of the field stars. We performed an optical polarimetric survey within 3σ3\sigma uncertainties of four unidentified 3FGL sources. We discovered a previously unknown extragalactic object within the positional uncertainty of 3FGL J0221.2+2518. We obtained its spectrum and measured a redshift of z=0.0609±0.0004z=0.0609\pm0.0004. Using these measurements and archival data we demonstrate that this source is a candidate counterpart for 3FGL J0221.2+2518 and most probably is a composite object: a star-forming galaxy accompanied by AGN. We conclude that polarimetry can be a powerful asset in the search for AGN candidate counterparts for unidentified Fermi sources. Future extensive polarimetric surveys at high galactic latitudes (e.g., PASIPHAE) will allow the association of a significant fraction of currently unidentified gamma-ray sources.Comment: accepted to A&
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