1,721,116 research outputs found
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
The chemistry of protostellar jet-disk systems
Full text linkThe birth of a Sun-like star is a complex game played by several participants whose respective roles are not yet entirely clear. On the one hand, the star-to-be accretes matter from a collapsing envelope. The gravitational energy released in the process heats up the material surrounding the protostar, creating warm regions enriched by interstellar complex organic molecules (iCOMs, at least 6 atoms) called hot-corinos. On the other hand, the presence of angular momentum and magnetic fields leads to two consequences: (i) the formation of circumstellar disks; and (ii) substantial episodes of matter ejection, as e.g. collimated jets.
Thanks to the combination of the high-sensitivities and high-angular resolu- tions provided by the advent of new telescopes such as ALMA and NOEMA, it is now possible to image in details the earliest stages of the Sun-like star formation, thus inspecting the inner ( < 50 AU from the protostar) jet. At these spatial scales a proper study of jets has to take into account also the effects connected with the accreting disk. In other words, it is time to study the protostellar jet-disk system as a whole. Several still unanswered questions can be addressed. What is the origin of the chemically enriched hot corinos: are they jet-driven shocked regions? What is the origin of the ejections: are they due to disk or stellar winds? Shocks are precious tool to attack these questions, given they enrich the gas phase with the species deposited onto the dust mantles and/or locked in the refractory dust cores. Basically, we have to deal with two kind of shocks: (i) high-velocity shocks produced by protostellar jets, and (ii) slow accretion shocks located close to the centrifugal barrier of the accretion disks. Both shocks are factories of iCOMs, which can be then efficiently used to follow both the kinematics and the chemistry of the inner protostellar systems. With this in mind, we will discuss recent results obtained in the framework of different observational campaigns at mm and sub-mm wavelengths
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
The GENESIS-SKA project: looking for Solar System analogs
No full textThe recipe to make a habitable planet like our own Earth requires a relatively small rocky planet,
at the right distance from the host star, with a not-too-thick atmosphere which should be rich in volatiles and capable of developing complex organic molecules chemistry. Searches for exoplanets have shown a large degree of diversity among planetary systems, but have left still unanswered the two fundamental questions of how common planetary systems like our own are and of how general are the processes that allow for creating habitable planets. Understanding the formation of planetary
systems and the chemical processing of the volatiles that are going to form their atmospheres is therefore key to understand the origins of the Solar System. Key questions still to be addressed are:
(i) how solids overcome the growth barriers to become rocky cores, (ii) how the formation
of giant planets and their interaction with gas and solids in disks affect the formation of planets,
and (iii) how chemically complex are the volatiles delivered on the pristine planetary atmospheres.
The SKA telescope, and more specifically the GENESIS-SKA project, will allow us to study in detail
the evolution of dust as it evolves into planetesimals and rocky planets and to detect heavy complex
organic molecules that today are beyond the reach of our observing capabilities. The GENESIS-SKA project, supported as PRIN-INAF, is carrying on studies on dust evolution, planet formation, and pre-biotic chemical complexity, in the context of preparation of SKA Key Programmes. More specifically,
we are featuring a brand new synergy (in the INAF framework) between astronomical observational
(e.g. VLA, GBT, ALMA, IRAM, LBT, VLT) and modeling efforts, laboratory experiments, and state-of-the-art quantum-chemical computations
How organics deuteration changes during the formation of a Sun-like star
No full textDeuterated molecules have been detected towards the early stages of Sun-like star formation (prestellar cores, Class 0 objects) as well as towards the Solar System; they are a powerful diagnostic tool for studying physical conditions at the moment of the organics formation. However, observations in intermediate stages (Class I/II objects) are still missing. In the framework of the ASAI-IRAM Large Program, we report here the formaldehyde and methanol deuteration as measured in the Class I object SVS13-A. The deuterium fractionation is found to be 9 × 10-2for HDCO, 5 × 10-3For D2CO, and 4 × 10-3for CH_2DOH, up to one order of magnitude lower than the value measured in Class 0 sources. The present measurements of organics deuteration towards the Class I object SVS13-A contribute to fill in the gap between prestellar cores and protoplanetary disks in the context of deuterium fractionation measurements (see \citet{bia17})
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
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