1,720,972 research outputs found
The spatial dimension of competition among airports at the worldwide level: a spatial stochastic frontier analysis
No full textThis paper analyses the potential impact of airport competition on technical efficiency by applying the spatial stochastic frontier approach (SSFA) rather than the traditional model (SFA). The SSFA allows for isolating the cross-sectional spatial dependence and evaluating the role of intangible factors in influ- encing an airport’s economic performance through the inclusion of the distance matrix and the shared destinations matrix calibrated for different distances. By analysing the statistical differences between the traditional and the spatial model, it is possible to identify the competition effects. This study includes 206 airports at the worldwide level. The results show the existence of the spatial component: we detected a different influence of airports’ efficiency levels according to the geographical distances. This could have not been captured by the traditional SFA. We conclude that when incorporating spatial spillover effects into the airport efficiency analysis, the efficiency dynamics are strongly dependent on the spatial distance among airports
Environmentally Sustainable Air Transport: A Focus on Airline Productivity
No full textTackling air transport’s environmental externalities represents one of the
key challenges facing the industry. Airlines, airport operators, aircraft
manufacturers, air navigation service providers, and regulators are
increasingly coming to the realization that environmental impacts are key
constraints on growth, and that sound environmental and commercial
business practices are not necessarily mutually exclusive.
Like many other sectors, the framing of environmental protection
measures in air transport is generally couched in terms of conforming
to the guiding principles of sustainability, which is the long-held idea of policies balancing environmental, social, and economic priorities in
a way that meets the needs of present-day societies without jeopardizing
the ability of future societies to do likewise. Sustainable practices are
considered to be those that reduce or limit the environmental impacts of
a process or practice, while at the same time creating financial benefits
and social opportunities. Collectively, these aspects of sustainability are
known as the ‘triple bottom line’ (see Fig. 1).
While the environmental impacts of aviation have long been understood
(see Lee et al. 2009), political debates surrounding aviation’s
impact on the environment remain contested and contentious. Such
debates are relevant in a global context due largely to the significant predicted
near-to-medium-term growth in the global air transport market
and the knock-on impacts this will have in terms of the environment.
ICAO (International Civil Aviation Organization) forecasts a near tripling
of the global commercial aircraft fleet, rising from just under
20,000 aircraft in 2010 to 56,500 in 2040, with accompanying increases
in the passenger and air cargo markets (ICAO 2016). Concurrently,
international aviation CO2 emissions are forecasted to grow, under the
‘baseline growth scenario including fleet renewal, from around 500 Mt
in 2010 to nearly 2000 Mt in 2040’ (ICAO 2016). Our work aims to build on this important area of research by estimating
the trend in airline productivity when considering both the economic
and environmental aspects of air transport. We apply a data envelopment
analysis based on the productivity index to estimate the economic evolution
of the major global airlines. More precisely, we adopt a biennial
Malmquist–Luenberger index (BML), which is an indicator of productivity
that changes over time
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
Spatial competition and efficiency : an investigation in the airport sector
Get PDFThis paper analyses the potential impact of airport competition on technical efficiency by applying the spatial stochastic frontier approach (SSFA) rather than traditional model (SFA). The SSFA allows to isolate the cross-sectional spatial dependence and to evaluate the role of intangible factors in influencing the airport economic performance, through the inclusion of the distance matrix and the shared destinations matrix, calibrated for different distances. By analysing statistical differences between the traditional and the spatial model, it is possible to identify the competition effects. This study includes 206 airports at worldwide level. First, the results show the existence of the spatial component, that could not be otherwise captured by the traditional SFA. Moreover, airport competition is found to affect the efficiency level with either a positive or a negative effect, depending on the distance considered in the spatial model
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
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