1,720,958 research outputs found
Analisi delle caratteristiche ottiche della copertura vegetale di pomodoro da industria come strumento per una gestione eco-compatibile della concimazione
Full text linkConsidering the positive effects of fertilization on the yield of processed tomato and the emerging environmental risks due to heavy use of those productive factors beside the increasing market price, it would be better advised to use management systems and distribution technologies able to improve the efficiency of those important production factors. Previous experimental trials showed the efficacy of some optical tools in the management of nitrogen fertilization in processed tomato and on the base of those results it is supposed the chance of using the same tools to optimize even the other two macro-nutrients, phosphate and potassium, for a non-destructive evaluation of crop nutritional status. The aim of the research is to evaluate the modification induced by the deficiency of phosphorus and potassium on tomato canopy using the Multispectral Radiometer Cropscan MSR-87. A three year trial was set up to detect, between the available indices, the ones useful to the estimate the effects of different levels of fertilization and to confirm the preliminary results. During the first year tomato plants have been fertilized with nutrient solution deficient of one of the elements and compared to a complete nutrient solution. This preliminary trial allowed to identify few indices suitable for the purpose. Those indices have been used during the second and third year to determine their effectiveness in detecting the induced deficient status in open field cultivation using the previous nutrient solutions. Beside the open field trial, an increasing doses trial was set up to verify if the indices could detect different levels of deficiency or excess. The first trial confirmed the suitability of NIR/Green index in detecting nitrogen deficiency. It showed that the low availability of potassium is identify by the optical tool as a non-deficient status and on the other side that the phosphate deficiency is detected by the tool as a nitrogen deficiency. Using the NIR/760 and the 1/Ref. Norm (560), in controlled condition, it is possible to distinguish the nitrogen treatment by the phosphate one. In the open field trial it has been difficult to reach an evident deficient status even supplying the same nutrient solution used in the previous trial. In this case the indices were not able to distinguish the treatments and only the NIR/Green showed the nitrogen deficiency as was stated in previous trials. The indices were able to detect the different levels of deficiency during the third trial conducted in a greenhouse using different doses of elements but when the same index was used to compare the same dose of different elements, no distinction between treatments was showed. The management of fertilization in processed tomato using optical tools is possible for nitrogen application but it is still to be confirmed for the other two macronutrients
Effetto degli stress nutrizionalisulla ripartizione dei nutrienti in piante di pomodoro da industria
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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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