1,720,975 research outputs found
Regional land cover mapping in the humid tropics using combined optical and SAR satellite data - A case study from Central Sulawesi, Indonesia
No full textThe frequent mapping of the spatial extent of land cover and its change from satellite data at the regional level provides essential input to spatially explicit land use analysis and scenario modelling. The accuracy of a land cover map is the key factor describing the quality of a map, and hence affecting the results of land use modelling. In tropical regions, land cover mapping from optical satellites is hampered by cloud coverage and thus alternative data sources have to be evaluated. In the present study, data from Landsat-ETM+ and Envisat-ASAR satellite sensors were tested for their ability to assess small scaled landscape patterns in a tropical environment. A focus was on the detection of intensively managed perennial and intra-annual cropping systems (cocoa, rice). The results confirm previous knowledge about the general potential and advantages of multi-temporal SAR data compared to mono-temporal SAR-based mapping but also show the limitations of different polarization modes in SAR analysis for land cover mapping. In the present case study, cross-polarized data from Envisat-ASAR did not yield notable profit for tropical land cover mapping compared to common, co-polarized time series of ASAR data. However, the general outcome of the study underlines the synergy of optical and radar satellite data for land cover mapping in tropical regions
Rainforest conversion in Central Sulawesi, Indonesia: Recent development and consequences for river discharge and water resources - An integrated remote sensing and hydrological modelling approach
No full textThe present land cover of humid tropical catchment areas mainly regulates the flow of vapour to the atmosphere. Therefore land use decisions play an important role for the water balance of a tropical catchment. Studies that relate land cover changes with river discharge changes for humid tropical catchment areas at the mesoscale level are rare. This article applies an integrated remote sensing and hydrological modelling approach to analyse the impact of land cover changes on the water resources of a mesoscale humid tropical catchment. First, a change detection analysis of Landsat/ETM+ satellite images was carried out to quantify land cover changes of the mesoscale Gumbasa River catchment in Central Sulawesi, Indonesia. Thereafter the distributed hydrological model WASIM-ETH was calibrated and validated for the current Landsat/ETM+, scene. The historical Landsat/ETM+ scene was integrated for the hydrological model application as a historical land cover scenario. Further hypothetical total-change scenarios were carried out. The results of the hydrological model scenario application clearly demonstrate a strong relationship between deforestation rates and increasing discharge variability. Especially a significant increase of high water discharges was simulated for the applied scenarios. With regard to the high deforestation rates of the research catchment, one can expect further changes of the water balance
From global to regional scale: Remote sensing-based concepts and methods for mapping land-cover and land-cover change in tropical regions
No full textA great number of studies have been dealing with land-cover mapping of tropical regions using earth remote sensing technology recently. This is partly due to a growing number of operational sensor systems for both scientific and commercial use and also because of an increasing demand for land-cover information relevant to global environmental issues and international policy instruments (e.g. the Kyoto protocol). Within this context, the present article discusses the state of the art of data processing and analysis for the assessment of broad scale land-cover and land-cover change in tropical regions. Current global scale land-cover maps are compared with regional satellite mapping products (Landsat/ETM+) for a test region in the humid tropics of Central Sulawesi, Indonesia. The paper suggests the land cover classification system (LCCS) to be used as the conceptual basis for future land-cover analysis in Sulawesi because it delivers a consistent and comparable scale-independent class structure for satellite image-based land-cover mapping and monitoring. The results of the comparative analysis of land-cover and land-cover change document the inhomogeneity, inconsistency and hence high uncertainty of existing estimates. The outcome of the harmonized and generalized land-cover products for two base years (1992 and 2000) indicates considerable disagreements in area estimates and spatial distributions of land-cover classes for a single date that in some cases exceed the detectable changes between years. Future work aiming at a long-scale operational land-cover mapping of tropical environments has to account for (a) a further harmonization of existing and planned land-cover definitions and products, (b) the regional validation of products and (c) the implementation of a multi-level standardized technical and conceptual classification workflow for ecosystem mapping and monitoring in tropical regions
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
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