1,721,005 research outputs found
Chemical evolution of primary and formation of secondary biomass burning aerosols during daytime and nighttime
Full text linkOrganic matter (OM) can constitute more than half of
fine particulate matter (PM) and affect climate and
human health. Natural and man-made biomass burning
is an important contributor to primary and secondary
OM (POA and SOA) with an increasing trend.
Aerosol mass spectrometry (AMS) and Fourier
transform infrared spectroscopy (FTIR) are two
complementary methods of identifying the complex
chemical composition of OM in terms of mass fragments
and functional groups, respectively. AMS offers a
relatively higher temporal resolution compared to FTIR
(performed on PTFE filters). However, the interpretation
of AMS mass spectra remains complicated due to the
extensive molecular fragmentation.
In this study, we used collocated AMS and FTIR
measurements to better understand the evolution of
biomass burning POA and SOA due to different
mechanisms of chemical aging (e.g., homogeneous gasphase
oxidation and heterogeneous reactions). Primary
emissions from wood and pellet stoves were injected
into a 10 m3 environmental chamber located at the
Center for Studies of Air Qualities and Climate Change (CSTACC)
at ICE-HT/FORTH. Primary emissions were aged
using hydroxyl and nitrate radicals with atmospherically
relevant exposures. PM1 was analyzed by a highresolution
time-of-flight (HR-ToF) and was also collected
on PTFE filters over 20-minute periods before and after
aging for off-line FTIR analysis.
AMS and FTIR measurements agreed well with
regards to the concentration of OM and some biomass
burning tracers (levoglucosan and lignin; Yazdani A.,
2020b) and the OM:OC ratio. Chamber wall loss rates
were estimated using AMS OM concentration and were
used to split the contribution of POA and SOA. The
estimated FTIR and AMS spectra of SOA produced by
reactions of biomass burning volatile organic compounds
(VOCs) with OH were found to have prominent acid
signatures. Organonitrates, on the other hand, appeared
to be important for SOA produced by the nitrate radical.
We found that with continued aging, SOA evolves and
becomes similar to the oxygenated OA (OOA) in the
atmosphere. We also found that POA composition also
evolves with aging. Our estimates show that up to 10 %
of POA mass undergoes aging. Biomass burning tracers
such as lignin and levoglucosan in addition to
hydrocarbons are among the POA compounds that are
lost the most in biomass burning POA (up to 6 times more
than OM decrease due to chamber wall losses; Fig. 1).
This diminution is observed for both semi-volatile
(levoglucosan and hydrocarbons) and non-volatile
(lignin) POA species, implying the importance of gasparticle
partitioning, heterogeneous reactions, and
photolysis for POA evolution in the atmosphere. This
result can be important since chemical transport models
usually do not consider POA heterogeneous reactions.
Figure 1. Trends of individual AMS mass fragments (with
contribution to OM> 0.3 %) during aging with UV
(starting from time zero). All mass fragments have been
normalized by their concentration before the with start
of aging and corrected for the chamber wall losses.
Important mass fragments are shown in color.
This work was supported by the project PyroTRACH (ERC-
2016-COG) funded from H2020-EU.1.1. - Excellent
Science - European Research Council (ERC), project ID
726165 and funding from the Swiss National Science
Foundation (200021_172923).
References
Yazdani, A., Dudani, N., Takahama, S., Bertrand, A.,
Prévôt, A. S. H., El Haddad, I., and Dillner, A. M.:
Characterization of Primary and Aged Wood Burning and
Coal Combustion Organic Aerosols in Environmental
Chamber and Its Implications for Atmospheric Aerosols,
Atmospheric Chemistry and Physics Discussions, pp. 1–
32
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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