1,720,970 research outputs found
Sink-pulled simulation of the maize crop
No full textCurrent maize simulation models (CORNF and CERES-Maize) are "source-oriented", in which kernel weight is predicted without simulating sink demand of the kernels. The major goal of this research is to develop a physiologically sound model to simulate vegetative and reproductive growth of maize;The objectives of this study are: (1) to develop a subroutine to predict maize vegetative development; (2) to develop mechanisms to calculate silk growth, fertilization of the silk, and kernel set; (3) to address some of the problems that CENTLI has and use it to simulate grain filling period; (4) to develop a mechanism to predict the impact of both temperature and water stresses on maize growth and development; (5) to test the physiological implication of the developed model;Maize-S was validated against field data collected from two locations in Iowa in 1995 and 1996 for two maize hybrids planted at two different planting dates were used. To evaluate accuracy of predictions, the mean root square error and percent error averaged over time were calculated for both Maize-S and CERES-Maize;Maize-S predictions for leaf and stem weight were more accurate than CERES-Maize. CERES-Maize predictions for kernel number were more accurate than Maize-S predictions in four locations. This might be attributed to the method that CERES-Maize uses to calculate kernel number, wherein a stress factor is used to reduce kernel number. Maize-S does not account for any stress during kernel set. CERES-Maize predictions for kernel number were more accurate than Maize-S at two locations;Sensitivity analysis using Maize-S with conditions of +5 or -5°C from observed air temperatures reveals major changes in plant behavior. Maize-S output shows that high temperature cause silking to occur earlier than normal with an average of 3.2 days for each 1°C increase in temperature. A reduction in leaf area, aboveground nongrain and grain weights were also observed. Whereas cool temperature prolongs the growing season, and consequently increasing both aboveground nongrain and grain weights and leaf area;Sensitivity analysis using Maize-S with the condition of 5% increase in solar radiation did not affect number of days to silking, but increase the number of days to maturity by an average of 6 days. Aboveground nongrain and grain weights were also increased, whereas leaf area was not affected;Furthermore, Maize-S output shows that when defoliation occurs on weekly intervals after silking up to three weeks reduced kernel yield, weight per kernel, and kernel number;Further improvement in estimating water stress is recommended. Other improvements would be the capability to simulate prolificacy, and the estimation of nitrogen stress effects on yield.</p
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
Systems approach to water productivity assessment using cropping system Models
No full textIrrigation management of crops in Egypt is characterized by the application of more water than the crops require. In fact, large amounts of water are supplied without any estimates of the soil water content at the root zone. The rationale for doing so is the assumption that more irrigation water means a greater yield. So, eliminating the use of this unnecessary irrigation water could help save the resource, provided that this can be done with low yield losses.
The estimation of soil water reserves in the root zone area is essential for the best irrigation management. This management can be done by modeling water depletion from the root zone under the application of different amounts of irrigation water (Khalil et al., 2007). Models that simulate crop growth and water flow in the root zone can be powerful tools for extrapolating findings and conclusions from field studies to conditions not tested (Smith et al., 2000). Therefore, using these types of models to predict the effect of applying deficit irrigation on the yield of several crops could be an ultimate solution to conserving irrigation water.
Deficit irrigation, while it may result in a yield reduction, in general increases water productivity and has the added benefit that the irrigation water saved can be used in new lands. However, testing these deficit irrigation practices in the field is expensive. Therefore, simulation models could partially substitute for experiments to test different deficit irrigation scenarios and be used to develop recommendations for the conservation of irrigation water and the minimizing of yield losses. Three models were selected for that purpose, CROPWAT, Yield-Stress and CropSyst. Our objective was to use these models to assess the effects of different deficit irrigation scenarios on the yields of crops planted in the field trials
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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