1,721,342 research outputs found
A new interpretation of the far-infrared – radio correlation and the expected breakdown at high redshift
No full textContext. Observations of galaxies up to z ∼ 2 show a
tight correlation between far-infrared and radio continuum emission, suggesting a relation
between star formation activity and magnetic fields in the presence of cosmic rays.
Aims. We explain the far-infrared – radio continuum correlation by
relating star formation and magnetic field strength in terms of turbulent magnetic field
amplification, where turbulence is injected by supernova explosions from massive stars. We
assess the potential evolution of this relation at high redshift, and explore the impact
on the far-infrared – radio correlation.
Methods. We calculate the expected amount of turbulence in galaxies
based on their star formation rates, and infer the expected magnetic field strength due to
turbulent dynamo amplification. We calculate the timescales for cosmic ray energy losses
via synchrotron emission, inverse Compton scattering, ionization and bremsstrahlung
emission, probing up to which redshift strong synchrotron emission can be maintained.
Results. We find that the correlation between star formation rate and
magnetic field strength in the local Universe can be understood as a result of turbulent
magnetic field amplification. The ratio of radio to far-infrared surface brightness is
expected to increase with total field strength. A continuation of the correlation is
expected towards high redshifts. If the typical gas density in the interstellar medium
increases at high z, we expect an increase of the magnetic field strength
and the radio emission, as indicated by current observations. Such an increase would imply
a modification, but not a breakdown of the far-infrared – radio correlation. We expect a
breakdown at the redshift when inverse Compton losses start dominating over synchrotron
emission. For a given star formation surface density, we calculate the redshift where the
far-infrared – radio correlation will break down, yielding z ∼ (ΣSFR / 0.0045 M⊙ kpc-2 yr-1)1 / (6 − α / 2).
In this relation, the parameter α describes the evolution of the
characteristic ISM density in galaxies as
(1 + z)α. We note that observed frequencies
of 1−10 GHz are particularly well-suited to explore this relation, as bremsstrahlung
losses could potentially dominate at low frequencies.
Conclusions. Both the possible raise of the radio emission at high
redshift and the final breakdown of the far-infrared – radio correlation at a critical
redshift will be probed by the Square Kilometre Array (SKA) and its pathfinders, while the
typical ISM density in galaxies will be probed with ALMA. The combined measurements will
thus allow a verification of the model proposed here
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Surface-induced vibrational energy redistribution in methane/surface scattering depends on catalytic activity
No full textRecent state-to-state experiments of methane scattering from Ni(111) and graphene-covered Ni(111) combined with quantum mechanical simulations suggest an intriguing correlation between the surface-induced vibrational energy redistribution (SIVR) during the molecule/surface scattering event and the catalytic activity for methane dissociation of the target surface (Werdecker, Phys. Rev. Res., 2020, 2, 043251). Herein, we report new quantum state and angle-resolved measurements for methane scattering from Ni(111) and Au(111) probing the extent of ν 3 → ν 1 antisymmetric-to-symmetric conversion of methane stretching motion for two surfaces with different catalytic activities. Consistent with the expectations, the extent of SIVR occurring on the more catalytically active Ni(111) surface, as measured by the ν 1 : ν 3 scattered population ratio, is found to be several times stronger than that on the more inert Au(111) surface. We also present additional insights on the rovibrational scattering dynamics contained in the angle- and state-resolved data. The results together highlight the power of state-resolved scattering measurements as a tool for investigating methane–surface interactions
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