1,721,197 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
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
The cycling of sulfur dioxide in the marine boundary layer
No full textThe atmospheric cycling of sulfur dioxide (SO\sb2) is examined through the use of field measurements and photochemical modeling. A question exists as to whether or not SO\sb2 is a major product of dimethylsulfide (DMS) oxidation and subsequently important in the formation of new particles and cloud condensation nuclei (CCN). The relative magnitudes of the different sources and sinks of SO\sb2 in the remote marine boundary layer are looked at using field measurements of SO\sb2, DMS, and hydrogen sulfide (H\sb2S) and a time dependent photochemical box model of an air mass in the marine boundary layer.A new automated technique for measuring SO\sb2 was developed. It enables continuous real-time measurement of SO\sb2 using HPLC/Fluorescence at parts-per-trillion levels. Atmospheric and seawater DMS and atmospheric H\sb2S were also measured during these cruises in order to define the biogenic sources of SO\sb2.The observed SO\sb2 levels in the marine boundary layer are much lower than those predicted by current photochemical models using the measured DMS concentrations. Also, current models predict that SO\sb2 should have a pronounced diel cycle that is anticorrelated to that of DMS, however there is no observable diel cycle in the SO\sb2 data. Using a time-dependent photochemical box model and a model of the aqueous phase sea-salt aerosol chemistry, we examine the role of heterogeneous loss to sea-salt aerosols as a potentially important but previously unaccounted for sink for SO\sb2 in the marine boundary layer. Our results indicate that this is a large sink for SO\sb2 in this region.</p
A study of methanesulfonic acid in ice cores
No full textMethanesulfonic acid (MSA), an oxidation product of DMS, is used as a biogenic sulfur tracer in deposited snow layers to better understand the relative importance of various sulfur inputs (biogenic, volcanic and anthropogenic sulfur) to both polar regions in the past.The ice cores and snowpit samples were collected from the 20D site (Greenland) and the Dominion Range site (Antarctica). A suppressed ion chromatographic method was used to measure MSA in snow and ice. The mean concentration of MSA in the 20D ice core is 3.30 ppb ( = 2.38 ppb, n = 1134). The MSA concentrations have decreased since 1900. The ratios of MSA/total S(VI) in the 20D ice core ranged from 15% before 1900 to 5% after 1900. These results suggest a non-biogenic sulfate source to the Greenland ice sheet at the present time. Based on the assumption that the pre-industrial ratios reflect the biogenic sulfur component in the sulfur burden, we estimate that, at the present time, approximately 80% of sulfur input to Greenland is contributed to non-biogenic sulfur.Seasonal variations of MSA in ice are observed in many but not all years. The seasonality in the 20D ice core is consistent with aerosol MSA data from high latitude stations which confirms that ice records that atmospheric changes. Complications of meterological conditions are believed to be responsible for the lack of seasonality of MSA in ice.The mean concentrations of MSA in the Dominion Range snowpit and ice core are 2.76 ppb ( = 2.36, n = 199) and 0.94 ppb ( = 0.56, n = 258), respectively. The mean MSA/total S(VI) ratio is below 1% at the Dominion Range site. These data confirm that the MSA fraction in the high plateau is considerably lower than in coastal Antarctica and in the low- and the high-latitude marine boundary layer. Possible causes include volcanic sulfate input, long range transport of low-latitude biogenic sulfur, and additional stratospheric sulfate input.In summary, all of the above suggest that transport related sulfur source changes may primarily control the atmospheric chemistry, and consequently the ice chemistry, in both polar regions.</p
Recommended from our members
Biomass Burning Records in Northern High Latitude Ice Cores
Get PDFBiomass burning plays a major role in climate variability, atmospheric chemistry, carbon cycling, and atmospheric dynamics. In order to understand the drivers of biomass burning and how fire activity will change in the future, it is necessary to investigate how it has varied in the past. Proxy records are needed for understanding the forcing and feedbacks related to fire that are required for developing algorithms for biomass burning in Earth System models. Progress in this field has been limited due to a lack of well-dated proxy records documenting regional variability in burning on millennial and centennial time scales. In this dissertation, new ice core proxies are utilized to examine past trends in biomass burning. These proxies are organic chemicals (vanillic and p-hydroxybenzoic acids) produced by the incomplete combustion of lignin and commonly found in biomass burning aerosols. New analytical techniques utilizing high performance liquid chromatography, ion chromatography, and mass spectrometry were developed to measure ultra-trace levels of these compounds in polar ice cores. The abundance of these chemicals was measured in Arctic ice cores from Siberia, Greenland, and Svalbard. The 3,000-year Siberian record shows strong multi-centennial variability in burning with a signal to noise ratio unprecedented in previous proxy burning records. This Siberian ice-core record shows that extended periods of elevated wildfire emissions in Siberia occurred simultaneously with changes in the strength of the Asian Monsoon and the episodic pulsing of ice-rafted debris in the North Atlantic Ocean known as the Bond Events. This is the first clear observational evidence linking wildfire activity to large-scale climate change on millennial timescales. The 1,700-year Greenland and 750-year Svalbard records exhibit levels of these organic compounds that are considerably lower than those in Siberia, likely reflecting greater distance from the source regions. The variability of the two cores is similar, but quite different from the Siberian record. These differences suggest that the Siberian ice core records regional trends in fire, rather than an average across the high latitude northern hemisphere. This study represents the first millennial scale ice core records of these organic aerosol tracers. The results show significant spatial and temporal variability that should add significantly to our understanding of the relationship between biomass burning and climate change. Further work will be needed to understand fully these signals and to use such information to compare these biomass burning signals to Earth system models
- …
