1,720,996 research outputs found
Systematic Assessment Of Airborne Sun-Induced Fluorescence Maps By The Application Of Quality Criteria
No full textWhen plants absorb light, not all energy is converted by photosynthesis, but excess energy is released as heat or emitted as sun-induced chlorophyll fluorescence (F). This signal, related to the photosynthetic efficiency of plants, has been intensively studied and measured from ground, airborne and satellite. However, retrieving sun-induced fluorescence (F) from remote sensing data is challenging because accurate modeling of atmospheric influences is required.. The advent of the airborne imaging spectrometer HyPlant made possible to produce F maps in high-spatial resolution (1-3 meters), which is a valuable tool to better understand F at relevant ecosystem scale. Currently, two different algorithms are used routinely to retrieve red and far-red F from HyPlant. Both methods are based on the O 2 absorption bands, but while iFLD method employs a semi-empirical atmospheric correction (i.e., bare-soils), the SFM makes use of a physically-based atmospheric modeling (MODTRAN5 code). A common method of testing the reliability of a remotely sensed F product (in this study airborne F maps) is the comparison with “ground truth” data where the atmosphere can be neglected. In this work we tested another possibility of assessing the quality of the airborne F maps, which does not require ground reference measurements. For this purpose we have developed so-called ’quality criteria’, which should help to find errors and artefacts that have arisen during F retrieval. This method was used to test the quality of the airborne F maps of 2016 campaign. By applying the quality criteria, clear differences in the performance of two retrievals were found. Although it was shown that both retrievals performed well in F 760 retrieval, even at places with changes from vegetated to non-vegetated sites on pixel scale, iFLD was more robust for retrieving correct absolute values for F 760 and F 687 , while SFM performed less accurate in this term, over- and underestimating F values. Furthermore, previously reported problems with image pre-processing (deconvolution for correcting PSF) of SFM became clear here. This was causing strong artefacts in F 687 retrievals from SFM. However, SFM proved to be the more suitable method for identifying small differences on pixel scale. Moreover, this algorithm did not show systematic variations over entire flight lines as observed by the use of iFLD. The physically-based approach of atmospheric correction used with SFM thus provided more interference-free F maps than the semi-empirical correction using non-fluorescent surfaces as in iFLD retrieval. Testing F retrievals on vegetation under different illumination conditions showed the necessity to calculate F yield for quantification of photosynthesis rates. The application of the proposed quality features proved to be a valuable tool for assessing the performance of F retrieval on airborne maps. Therefore we propose to use the quality criteria even when sufficient ground references are available, because even if the quality criteria do not replace ground-truth data, they provide important additional information about the quality of the F product of the respective retrieval method
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
Quality assessment of Sun-Induced Fluorescence maps from the airborne imaging spectrometer HyPlant
No full textThe ability to investigate the Earth’s environment will be greatly improved by hyperspectral satellite data. The FLuorescence EXplorer (FLEX) will be the first hyperspectral mission designed to monitor the photosynthetic activity of the terrestrial vegetation layer by using a completely novel technique measuring the sun-induced chlorophyll fluorescence (SIF) signal that originates from the core of the photosynthetic machinery. In preparation of the upcoming FLEX satellite mission that will be launched in 2022 a large field campaign, namely FLEXSense, was conducted in summer 2018 including representative study sites at several locations in middle and south Europe as well as North America.During the different/various field activities, airborne data was acquired with the hyperspectral airborne imager HyPlant, whichthat consists of two sensor heads. The DUAL module is a line-imaging push-broom sensor, which providinges contiguous spectral information from 370 to 2500 nm. The vegetationchlorophyll fluorescence signal is measured with a separate push-broom sensor, the FLUO module, which produces data at high spectral resolution (0.25 nm) in the spectral region of the two oxygen absorption bands covering a range from 670 to 780 nm. Currently, two different algorithms are used routinely to retrieve red (SIF680) and far-red SIF (SIF760) from HyPlant data. Both methods are based on the oxygen absorption bands., but wWhile the improved Fraunhofer Line Depth (iFLD) method employs a semi-empirical atmospheric correction (i.e., bare-soils), the Spectral Fitting method (SFM) makes useis based onof a physically-based atmospheric modeling (MODTRAN5 code). A common method of testing the reliability of remotely-sensed SIF (in this study airborne maps) is the comparison with “ground truth” data. In many cases, however, ground measurements of SIF are not available or are too work-intensive to be measured at regional level. For that reason we developedwant to present an alternative approach how the quality of airborne SIF maps can be assessed. For this purpose we applyhave developed so-called ’quality criteria’, which should help to find errors and artefacts that have arisen during the SIF retrieval. This method was applied to determine the quality of individual SIF maps derived from HyPlant images acquired during the 2018 FLEXSense campaign. The application of the proposed quality features proved to be a valuable tool for assessing the quality of SIF maps derived from HyPlant airborne data. Therefore, we propose to apply the different criteria even in the case of a with sufficient number of ground reference measurements are available, as because they provide important additional information about the quality of spatial SIF products is provided, especially when comparing the outputs of different retrieval 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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