1,720,987 research outputs found
Factors determining the occurrence and characteristics of new particle formation events - A study over a continent
Full text linkNew Particle Formation (NPF) events, an important source of ultrafine particles in the atmosphere, were studied in multiple sites across Europe. Apart from the importance of meteorological conditions and atmospheric composition variables and compounds, such as the solar radiation intensity, the relative humidity or the condensation sink in the occurrence and development of the events, the importance of the origin of the incoming air masses and the specific characteristics that come with them is underlined. The increased formation rate of particles of 10 nm diameter calculated in the present study (being at a greater size than that of the initial particle formation occurring at about 1.5 nm and thus affected as a metric by the growth of the particles) and growth rates observed within the urban environment are associated with the increased presence of condensable species found in such environments, regardless of the geographical location within the European continent.
The NPF process is also studied according to the different aspects that define it, the frequency of the events, the formation and growth rates of the particles, and the specific role of each one of the atmospheric variables was calculated throughout Europe using the large dataset available, providing an insight of the effect of these variables on the NPF mechanisms. Finally, the range of the effect of these events on the ultrafine particle composition in each area was studied and the importance of the events in the air quality of a given area is displayed
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
NPF UK Data
No full textNew Particle Formation (NPF) events have different patterns of development depending on the conditions of the area in which they occur. In this study, NPF events occurring at three sites of differing characteristics (rural Harwell (HAR), urban background North Kensington (NK), urban roadside Marylebone Road (MR), London, UK) were studied (seven years of data). The different atmospheric conditions in each study area not only have an effect on the frequency of the events, but also affect their development. The frequency of NPF events is similar at the rural and urban background locations (about 7% of days), with a high proportion of events occurring at both sites on the same day (45%). The frequency of NPF events at the urban roadside site is slightly less (6% of days), and higher particle growth rates (average 5.5 nm h-1 at MR compared to 3.4 nm h-1 and 4.2 nm h-1 at HAR and NK respectively) must result from rapid gas to particle conversion of traffic-generated pollutants. A general pattern is found in which the condensation sink increases with the degree of pollution of the site, but this is counteracted by increased particle growth rates at the more polluted location. A key finding of this study is that the role of the urban environment leads to an increment of 20% in N16-20nm in the urban background compared to that of the rural area in NPF events occurring at both sites. The relationship of the origin of incoming air masses is also considered and an association of regional events with cleaner air masses is found. Due to lower availability of condensable species, NPF events that are associated with cleaner atmospheric conditions have lower growth rates of the newly formed particles. The decisive effect of the condensation sink in the development of NPF events and the survivability of the newly formed particles is underlined, and influences the overall contribution of NPF events to the number of ultrafine particles in an area. The other key factor identified by this study is the important role that urban pollution plays in new particle formation events
Airgradient data from 6 sites in Kampala, Uganda
No full textAirgradient data from 6 sites in Kampala, Ugand
Data for the mobile source apportionment campaign
No full textLow-cost sensor air quality data collected in Selly Oak. Additionally, research grade meteorological and air quality for the same period collected at the Birmingham Air Quality Supersit
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
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