1,720,958 research outputs found
Deep Change Vector Analysis to Map Bark Beetle Outbreaks in Open Sentinel-2 Data
No full textOpen remote sensing science has been recently
boosted by the free availability of Sentinel-2 images of planet
Earth acquired with the Copernicus programme. In particular,
processing open Sentinel-2 images with Artificial Intelligence (AI)
techniques holds great potential for revolutionizing data science
applications in many domains of Earth sciences. In this paper,
we explore the potential of an unsupervised learning method
designed to process Sentinel-2 images of Earth’s forest scenes
and automate the inventory of forest tree dieback caused by
bark beetle outbreaks. Specifically, we describe PHANTASM: a
method to identify forest tree dieback patches performing the
Change Vector Analysis (CVA) of bi-temporal Sentinel-2 images
of forest scenes. While the traditional CVA strategy is based
on the analysis of pixel-wise differences in spectral values, we
enrich the Sentinel-2 spectrum with both a selection of Spectral
Vegetation Indexes and a Spectral-Spatial Deep Embedding.
The Spectral Vegetation Indexes are pre-defined combinations
of spectral bands commonly designed to enhance the accuracy
of semantic segmentation models trained to map bark beetle
stress in spectral data. The Deep Embedding is a spectralspatial representation of Sentinel-2 pixels trained with a deep
neural network. In particular, we use a pre-trained, semantic
segmentation U-Net to obtain the Deep Embedding that models
the spatial relationship among neighbouring spectral pixels. We
assess the effectiveness of the proposed method in a case study
regarding bark beetle outbreaks in Sentinel-2 images of forest
scenes in the Czech Republi
Potential of Spectral-Spatial Analysis to Map Forest Tree Dieback Due to Bark Beetle Hotspots in Sentinel-2 Images
No full textForest tree dieback inventory plays a crucial role to improve forest management strategies. In this study, we explore the performance of a spectral-spatial machine learning approach used to analyse Sentinel-2 images to detect forest tree dieback events due to bark beetle infestation. We analyse the performance of classification models trained with Random Forest, XGBoost and Multi-Layer Perceptron, as well as semantic segmentation models trained with U-Net by accounting for both spectral and spatial information contained in the remote sensing data. We consider a set of Sentinel-2 images acquired in non-overlapping forest scenes from a region located in the Northeast of France. The selected scenes host bark beetle infestation hotspots originated from the mass reproduction of the bark beetle in the 2018 infestation. Results show that the U-Net model, trained accounting for spectral and spectral-spatial data, achieves the best performance. However, the simpler Random Forest model achieves competitive results with respect to the more complex one, namely U-Net
An Attention-Based CNN Approach to Detect Forest Tree Dieback Caused by Insect Outbreak in Sentinel-2 Images
No full textForests play a key role in maintaining the balance of ecosystems, regulating climate, conserving biodiversity, and supporting various ecological processes. However, insect outbreaks, particularly bark beetle outbreaks, pose a significant threat to European spruce forest health by causing an increase in forest tree mortality. Therefore, developing accurate forest disturbance inventory strategies is crucial to quantifying and promptly mitigating outbreak diseases and boosting effective environmental management. In this paper, we propose a deep learning-based approach, named AVALON, that implements a CNN to detect tree dieback events in Sentinel-2 images of forest areas. To this aim, each pixel of a Sentinel-2 image is transformed into an imagery representation that sees the pixel within its surrounding pixel neighbourhood. We incorporate an attention mechanism into the CNN architecture to gain accuracy and achieve useful insights from the explanations of the spatial arrangement of model decisions. We assess the effectiveness of the proposed approach in two case studies regarding forest scenes in the Northeast of France and the Czech Republic, which were monitored using Sentinel-2 satellite in October 2018 and September 2020, respectively. Both case studies host bark beetle outbreaks in the considered periods
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
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
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