131 research outputs found
Flux density measurements of GPS candidate pulsars at 610 MHz using interferometric imaging technique
We conducted radio interferometric observations of six pulsars at 610 MHz
using the Giant Metrewave Radio Telescope (GMRT). All these objects were
claimed or suspected to be the gigahertz-peaked spectra (GPS) pulsars. For a
half of the sources in our sample the interferometric imaging provides the only
means to estimate their flux at 610 MHz due to a strong pulse
scatter-broadening. In our case, these pulsars have very high dispersion
measure values and we present their spectra containing for the first time
low-frequency measurements. The remaining three pulsars were observed at low
frequencies using the conventional pulsar flux measurement method. The
interferometric imaging technique allowed us to re-examine their fluxes at 610
MHz. We were able to confirm the GPS feature in the PSR B182313 spectrum and
select a GPS candidate pulsar. These results clearly demonstrate that the
interferometric imaging technique can be successfully applied to estimate flux
density of pulsars even in the presence of strong scattering.Comment: 7 pages, 3 tables, 5 figures, accepted for publication in MNRA
Gigahertz-peaked spectra pulsars and thermal absorption model
We present the results of our radio interferometric observations of pulsars
at 325 MHz and 610 MHz using the Giant Metrewave Radio Telescope (GMRT). We
used the imaging method to estimate the flux densities of several pulsars at
these radio frequencies. The analysis of the shapes of the pulsar spectra
allowed us to identify five new gigahertz-peaked spectra (GPS) pulsars. Using
the hypothesis that the spectral turnovers are caused by thermal free-free
absorption in the interstellar medium, we modeled the spectra of all known
objects of this kind. Using the model, we were able to put some observational
constrains on the physical parameters of the absorbing matter, which allows us
to distinguish between the possible sources of absorption. We also discuss the
possible effects of the existence of GPS pulsars on future search surveys,
showing that the optimal frequency range for finding such objects would be from
a few GHz (for regular GPS sources) to possibly 10 GHz for pulsars and
radio-magnetars exhibiting very strong absorption.Comment: Accepted for publication in ApJ, 28 pages, 8 figure
Flux-density spectral analysis for several pulsars and two newly-identified gigahertz-peaked spectra
In this paper we present results from flux density measurements for 21
pulsars over a wide frequency range, using the Giant Metrewave Radio Telescope
(GMRT) and the Effelsberg telescope. Our sample was a set of mostly newly
discovered pulsars from the selection of candidates for gigahertz-peaked
spectra (GPS) pulsars. Using the results of our observations along with
previously published data, we identify two new GPS pulsars. One of them, PSR
J1740+1000, with dispersion measure of 24 pc cm, is the first GPS pulsar
with such a low DM value.We also selected several strong candidates for objects
with high frequency turnover in their spectra which require further
investigation.We also revisit our source selection criteria for future searches
for GPS pulsars.Comment: 10 pages, 2 tables, 9 figures, accepted for publication in MNRA
Modelling of the radio spectrum evolution in the binary pulsar B125963
In this paper we give the first attempt to model the evolution of the
spectrum of PSR B125963 radio emission while the pulsar orbits the companion
Be star. As suggested by Kijak et al. (Mon. Not. R. Astron. Soc. 418:L114,
2011a) this binary system can be useful in understanding the origin of the
gigahertz-peaked spectrum of pulsars. The model explains, at least
qualitatively, the observed alterations of the spectral shape depending on the
orbital phases of this pulsar. Thus, our results support the hypothesis that
the external factors have a significant impact on the observed radio emission
of a pulsar. The model can also contribute to our understanding of the origin
of some non-typical spectral shapes(e.g. flat or broken spectra).Comment: 9 pages, 2 tables, 3 figure
О нормотворческой функции языка СМИ (на примере названий женщин по профессии, должности и званию)
The author considers process to increase the quantity of vocational feminine forms in contemporary Russian language, especially in Russian press. This paper presents Russian vocational feminine forms with feminine suffixes (e.g., -ка, -ша, -иха)
Stereotyp kobiety w skrzydlatych słowach języka rosyjskiego
В настоящей статье даётся короткий анализ крылатых слов как одного из источников языковых стереотипов, касающихся женщины в русском языке.
Исходной точкой анализа является само понятие языкового стереотипа
и крылатого выражения. Стереотип женщины обсуждается здесь на основе избранных (наиболее известных носителям языка) крылатых выражений русского языка, которые могут давать так положительную, как и отрицательную характеристику женщины.
Языковые проблемы указаны на фоне общественной ситуации в современной России, особенно - на фоне проблемы дискриминации женщин
Spectroscopic Characterization of i-motif Forming c-myc Derived Sequences Double-Labeled with Pyrene
In current studies we use the oligonucleotides based on c-myc sequence: CCC CAC CCT CCC CAC CCT CCC C (cmyc22) and CCC CAC CCT CCC CAC CCT CCC CA (cmyc22A) functionalized by pyrene moieties at both termini. Results of the circular dichroism (CD), UV absorption melting experiments, and steady-state fluorescence measurements of pyrene-modified i-motifs as well as their unlabeled precursors are presented and discussed here. The pyrene labels have a remarkable influence on i-motif stability which was deduced from CD spectra and confirmed by UV melting experiments. Both probes emit fluorescence band of pyrene monomer with intensity decreasing upon pH lowering. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10895-013-1184-z) contains supplementary material, which is available to authorized users
Zjawisko kontaminacji jako jeden z aspektów badawczych języka reklamy (na przykładzie języka rosyjskiego)
The author considers phenomenon of blending in modern Russian, especially in commercial language.
In this paper the term blending is explained and the author describes reasons for using blends in commercial language on the basis of Russian linguistic material. The starting point is definition of the blend as a word formed from parts of two or more other words.
The author presents kinds of blends in commercial slogans, e.g.: the beginning of one word is added to the end of the other (Бисплатно: Билайн + бесплатно) or the end of one word is overlapped at the beginning of the other (музыкайф: музыка + кайф).
The illustrative material was taken from Russian press and Internet
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