1,720,961 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
INDIRECT PHOTOCHEMICAL FORMATION OF COS AND CS2 IN NATURAL WATERS: KINETICS AND REACTION MECHANISMS
No full textCOS and CS2 are sulfur compounds that are formed
in natural waters. These compounds are also volatile, which leads them move
into the atmosphere and serve as critical precursors to sulfate aerosols.
Sulfate aerosols are known to counteract global warming by reflecting solar
radiation. One major source of COS and CS2 stems from the ocean. While
previous studies have linked COS and CS2 formation in these waters to the
indirect photolysis of organic sulfur compounds, much of the chemistry behind
how this occurs remains unclear. This study examined this chemistry by
evaluating how different organic sulfur precursors, water quality constituents,
and temperature affected COS and CS2 formation in natural waters.
In the first part of this thesis (chapters 2 and 3), nine natural
waters ranging in salinity were spiked with various organic sulfur precursors
(e.g. cysteine, cystine, dimethylsulfide (DMS) and methionine) exposed to
simulated sunlight over varying exposures. Other water quality conditions
including the presence of O2, CO and temperature were also varied. Results
indicated that COS and CS2 formation increased up to 11× and 4×,
respectively, after 12 h of sunlight while diurnal cycling exhibited varied
effects. COS and CS2 formation were also strongly affected by the DOC
concentration, organic sulfur precursor type, O2 concentration, and
temperature while salinity differences and CO addition did not play a
significant role.
To then specifically evaluate the role of DOM in cleaner matrices,
COS and CS2 formation was examined in synthetic waters (see chapters 4 and
5). In this case, synthetic waters were spiked with different types of DOM
isolates ranging from freshwater to ocean water along with either cysteine or
DMS and exposed to simulated sunlight for up to 4 h. Surprisingly, CS2 was
not formed under any of the tested conditions, indicating that other water
quality constituents, aside from DOM, were responsible for its formation.
However, COS formation was observed. Interestingly, COS formation with cysteine
was fairly similar for all DOM types, but increasing DOM concentration actually
decreased formation. This is likely due to the dual role of DOM on
simultaneously forming and quenching the reactive intermediates (RIs).
Additional experiments with quenching agents to RIs (e.g. 3DOM* and ·OH)
further indicated that ·OH was not involved in COS formation
with cysteine but 3DOM* was involved. This result differed with DMS
in that ·OH and 3DOM* were both found to be involved. In
addition, treating DOM isolates with sodium borohydride (NaBH4) to reduce
ketone/aldehydes to their corresponding alcohols increased COS formation, which
implied that the RIs formed by these functional groups in DOM were not
involved. The alcohols formed by this process were not likely to act as quenching
agents since they have been shown to low in reactivity. Since ketones are known
to form high-energy-triplet-states of DOM while quinones are known to form
low-energy-triplet-states of DOM, removing ketones from the system further
supported the role of low-energy-triplet-states on COS formation. This was
initially hypothesized by findings from the testes on DOM types. In the
end there are several major research contributions from this thesis. First,
cysteine and DMS have different mechanisms for forming COS. Second, adding O2 decreased
COS formation, but it did not stop it completely, which suggests that further
research is required to evaluate the role of RI in the presence of O2. Lastly,
considering the low formation yields of COS and CS2 formation from the
organic sulfur precursors tested in this study, it is believed that some other
organic sulfur precursors are missing which are likely to generate these
compounds to higher levels and this needs to be investigated in future
research. </p
Indirect Photochemical Formation of COS and CS2 in Natural Waters: Kinetics and Reaction Mechanisms
No full textCOS and CS2 are sulfur compounds that are formed in natural waters. These compounds are also volatile, which leads them move into the atmosphere and serve as critical precursors to sulfate aerosols. Sulfate aerosols are known to counteract global warming by reflecting solar radiation. One major source of COS and CS2 stems from the ocean. While previous studies have linked COS and CS2 formation in these waters to the indirect photolysis of organic sulfur compounds, much of the chemistry behind how this occurs remains unclear. This study examined this chemistry by evaluating how different organic sulfur precursors, water quality constituents, and temperature affected COS and CS2 formation in natural waters.In the first part of this thesis (chapters 2 and 3), nine natural waters ranging in salinity were spiked with various organic sulfur precursors (e.g. cysteine, cystine, dimethylsulfide (DMS) and methionine) exposed to simulated sunlight over varying exposures. Other water quality conditions including the presence of O2, CO and temperature were also varied. Results indicated that COS and CS2 formation increased up to 11× and 4×, respectively, after 12 h of sunlight while diurnal cycling exhibited varied effects. COS and CS2 formation were also strongly affected by the DOC concentration, organic sulfur precursor type, O2 concentration, and temperature while salinity differences and CO addition did not play a significant role.To then specifically evaluate the role of DOM in cleaner matrices, COS and CS2 formation was examined in synthetic waters (see chapters 4 and 5). In this case, synthetic waters were spiked with different types of DOM isolates ranging from freshwater to ocean water along with either cysteine or DMS and exposed to simulated sunlight for up to 4 h. Surprisingly, CS2 was not formed under any of the tested conditions, indicating that other water quality constituents, aside from DOM, were responsible for its formation. However, COS formation was observed. Interestingly, COS formation with cysteine was fairly similar for all DOM types, but increasing DOM concentration actually decreased formation. This is likely due to the dual role of DOM on simultaneously forming and quenching the reactive intermediates (RIs). Additional experiments with quenching agents to RIs (e.g. 3DOM* and OH) further indicated that OH was not involved in COS formation with cysteine but 3DOM* was involved. This result differed with DMS in that OH and 3DOM* were both found to be involved. In addition, treating DOM isolates with sodium borohydride (NaBH4) to reduce ketone/aldehydes to their corresponding alcohols increased COS formation, which implied that the RIs formed by these functional groups in DOM were not involved. The alcohols formed by this process were not likely to act as quenching agents since they have been shown to low in reactivity. Since ketones are known to form high-energy-tripletstates of DOM while quinones are known to form low-energy-triplet-states of DOM, removing ketones from the system further supported the role of low-energy-triplet-states on COS formation. This was initially hypothesized by findings from the testes on DOM types. In the end there are several major research contributions from this thesis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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