1,720,958 research outputs found
Mechanical weed control in onion seed production
No full textTwo field experiments with onion (Allium cepa L.) cultivated by the “seed-to-seed” and “bulb-to-seed” methods for the organic seed production were carried out in central Italy in order to evaluate the effects of some mechanical methods (harrowing, hoeing, hoeing-ridging, split-hoeing, finger-weeding, manual weeding) on: i) weed control; ii) selectivity to the onion; iii) onion seed production. The results showed that the choice of the seed production method and then the mechanical treatments require to be managed very carefully in order to maximize the weed control, reducing seed yield losses. The seed-to-seed method seemed to be not advisable in the Mediterranean areas, because there were great difficulties to control weeds by mechanical method mainly owing to the long crop cycle with more fluxes of weed emergence, the very low competitiveness of onion at the early growth stages and the weather conditions during the crop cycle that has greatly affected the timeliness, repeatability and effectiveness of mechanical control. In these conditions, competition of uncontrolled weeds caused heavy seed yield losses or the crop failure and only manual weeding ensured a satisfactory weed control and seed yield, although with a very high hand labour. The bulb-to-seed method was the only advisable for onion seed production because allowed to control weeds by mechanical methods, obtaining good levels of seed yield. In particular, combined intra and inter-row methods, such as hoeing-ridging or split-hoeing + finger-weeding, allowed a high effectiveness against weeds (ranged from 63% to 92%) and a good selectivity to the crop, reducing weed-crop competition and assuring satisfactory onion seed production. Unlike seed yield, seed quality was not affected by weed competition: weight, moisture and germinability of onion seeds were always over of the standard levels required for commercialization, regardless of weed competition levels
Monitoring nitrogen status of vegetable crops and soils for optimal nitrogen management
Full text linkOptimal crop nitrogen (N) management is required to minimize N losses to the environment in vegetable crop production. There are several approaches based on soil and plant monitoring that can assist to improve N management. These include soil monitoring, destructive (tissue N analysis, petiole sap nitrate (NO3−) analysis) and non-destructive (optical sensors) crop-based methods, and portable rapid analysis systems. The most promising optical sensors for guiding N management in vegetable production, considering performance and practicality, are chlorophyll meters and canopy reflectance sensors. The crop-based methods are generally sensitive indicators of crop N status in a wide range of vegetable crops. However, they tend to have reduced sensitivity when N supply is excessive. A notable feature of soil monitoring methods (e.g. the Dutch 1:2 soil-water extract method, soil solution monitoring) is that they can detect excess N supply. The combination of crop and soil monitoring will provide vegetable growers with tools to detect crop N deficiency and excess N supply. The selection of the best monitoring approach for a given farm will depend on factors such as crop and farm characteristics, the farmer's technical level, technical support, and economic considerations. Soil and crop monitoring approaches could form part of improved management packages that include Decision Support Systems (DSS), to determine crop N and/or irrigation requirements, and monitoring of soil water status. The use of such packages, when combined with fertigation and drip irrigation, is key for very efficient N management of vegetable crops with reduced N loss to the environment
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
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
Comparison of actual evapotranspiration simulated by SWAP and Penman-Monteith models in tomato crop
No full text- …
