1,721,145 research outputs found
Role of hedgerows in intercepting spray drift: Evaluation and modelling of the effects
No full textWhen a pesticide is applied a proportion of the sprayed solution may become a cause of pollution in the surrounding environment, with
ecotoxicological implications and phytotoxicity to other crops. In many countries buffer zones along field edges are recommended to shield
surface waters, and hedgerows can play an important role in reducing pesticide risk. This study focuses on droplet drift, with the aim of
evaluating the hedgerow efficacy in reducing drift from broadcast air-assisted sprayers and then to construct a simple model for estimating the
spray drift level in surrounding fields. Three experiments were conducted in North-East Italy in 2004 and 2005, in winter, summer and autumn
to obtain suitable optical porosity values in order to evaluate their effects. Three study situations (no hedgerow, single, double hedgerow) and
two sprayer–hedgerow interaction scenarios (sprayer working perpendicular to or parallel with the hedgerow) were considered. Hedgerows
were 7–8 m in height, while spray release height ranged from 1 to 2 m. The sampling method proved to be effective, with more than 73% of
total amount sprayed being intercepted. Where there was at least one hedgerow, off-site spray reductions ranged from 82.6 (with optical
porosity of 74.7%) to 97% (with optical porosity of 10.8%). The presence of a double hedgerow did not produce a higher interception rate.
Analysis of the spatial pattern of drift showed that where there is a hedgerow with an optical porosity of 74–75%, the aerial drift caused by
common broadcast air-assisted sprayers becomes negligible at a distance of 6–7 m. Hedgerows thus proved to be effective in intercepting
spray drift leaving cultivated fields. In particular, low optical porosities provided high interception rates, even with very dense canopies, as no
spray bypass was recorded. Spray drift profile was then modelled taking into account the effect of wind and optical porosity of a nearby
hedgerow. A negative-exponential model is proposed. The model fits the experimental data quite satisfactorily and may be used to estimate
spray drift magnitude in relation to wind speed and optical porosity of any hedgerow crossed by a droplets cloud spray drift
To feed or not to feed in ICU: evidence-based medicine versus physiology-based medicine.
No full text
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
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