1,721,002 research outputs found
Occupancy and detection of agricultural threats: the case of Philaenus spumarius, European vector of Xylella fastidiosa
No full textOccupancy models estimate presence and detection probability of species of interest of which they provide useful information and also contribute to decision making. In this proof-of-concept, we propose an approach to demonstrate the applicability of occupancy models in insect monitoring having as targets the spittlebug Philaenus spumarius, the main European vector of Xylella fastidiosa, and other spittlebugs. Surveys were performed in two different agricultural settings (olive orchards and vineyards) in Trentino (northern Italy). Philaenus spumarius was present in all surveyed sites and its detectability was significantly influenced by site covariates (i.e., forest and vineyard coverage, hours of sunlight) and plot covariates (i.e., weed height). Site covariates influenced the detection probability of other spittlebugs as well, while the co-occurrence of different species did not affect the P. spumarius occupancy. Our outcomes suggest that occupancy models are valuable tools that should support future studies aimed at estimating the presence and abundance of pest insects, especially when site covariates and/or sampling methods affect the detectability of a specie
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
Object-based image analysis for historic maps classification
Full text linkHeritage maps represent fundamental information for the study of the evolution of a region, especially in terms of landscape and ecologic features. Historical maps present two kinds of hurdle before they can be used in a modern GIS: they must be geometrically corrected to correspond to the datum in use and they must be classified to exploit the information they contain. This study deals the latter problem: the Historical Cadaster Map, created between 1851 and 1861, for the Trentino region in the North of Italy is available as a collection of maps in the ETRS89/UTM 32N datum. The map is a high resolution scan (230 DPI, 24 bit) of the original map and has been used in several ecological studies, since it provides detailed information not only about land property but also about land use. In the past the cadaster map has been manually digitized and for each area a set of attributes has been recorded. Since this approach is time consuming and prone to errors, automatic and semi-automatic procedures have been tested. Traditional image classification techniques, such as maximum likelihood classification, supervised or un-supervised, pixelwise and contextual, do not provide satisfactory results for many reasons: map colors are very variable within the same area, symbols and characters are used to identify cadaster parcels and locations, lines, drawn by hand on the original map, have variable thickness and colors. The availability of FOSS tools for the Object-based Image Analysis (OBIA) has made possible the application of this technique to the cadaster map. This paper describes the use of GRASS GIS and R for the implementation of the OBIA approach for the supervised classification of the historic cadaster map. It describes the determination of the optimal segments, the choice of their attributes and relevant statistics, and their classification. The result has been evaluated with respect to a manually digitized map using Cohens Kappa and the analysis of the confusion matrix. The result of the OBIA classification has also been compared to the classification of the same map using maximum likelihood classification, un-supervised and supervised, both pixelwise and contextual. The OBIA approach has provided very satisfactory results with the ability to automatically remove the background and symbols and characters, creating a ready to be used classified map. This study highlights the effectiveness of the OBIA processing chain available in the FOSS4G ecosystem, and in particular the added value of the interoperability between GRASS GIS and R
Fine spatial scale modelling of Trentino past forest landscape (Trentinoland): a case study of foss application
Full text linkTrentino is an Italian alpine region (about 6200 Km2
) with a forest coverage exceeding 60% of its whole surface. In the past, forest
landscape has changed dramatically, especially in periods of forest over-exploitation.
Previous studies in some Trentino sub-regions (Val di Fassa, Paneveggio) have identified these changes and the current trend of forest
growth at the expenses of open areas, such as pastures and grasslands, due to the abandonment of rural areas. This phenomenon
leads to the rapid Alpine landscape change and profoundly affects the ecological features of mountain ecosystems. To be able to
monitor and to take future actions about this trend it is fundamental to know in detail the historical situation of the progressive
changes on the land use that occurred over Trentino.
The work aims to comprehensively reconstruct the forest cover of whole Trentino at high resolution (5m x 5m pixels) using a series
of maps spanning a long period, consisting in historical maps, aerial images, remote sensed information and historical archives.
The datasets were archived, processed and analyzed using the Free and Open Source Software (FOSS) GIS GRASS and QGIS.
Historical maps include Atlas Tyrolensis (dated 1770), Theresianischer Kataster (dated 1859) and Italian Kingdom Forest Map
(IKFM) of 1936. The aerial imagery dataset includes aerial images taken in 1954, which have been orthorectified during this
research, and orthophotos available for years 1973, 1994, 2000, 2006, 2010 and 2016. Remote sensed information includes Landsat
and recent Lidar data, while historical archives consist mostly in Forest Management Plans available since around 1950.
The versatility of the wide variety of modules supplied from the FOSS GRASS and QGIS enabled to perform a diverse set of
analysis and pre-processing (e.g.:orthorectification) on a heterogeneous dataset of input images. We will focus on the different
strategies and methodologies implemented in the FOSS GIS used to process the various types of geographic data, challenges for
the future of the research and the fundamental role of the FOSS systems in this process.
Quantifying forest change in the time-span of our dataset can be used to perform further analysis on ecosystem services, such as
protection from soil erosion, and on modification of biome diversity and to create future change scenarios
Estimated biomass loss caused by the vaia windthrow in northern italy: Evaluation of active and passive remote sensing options
No full textWindstorms are a major disturbance factor for European forests. The 2018 Vaia storm, felled large volumes of timber in Italy causing serious ecological and financial losses. Remote sensing is fundamental for primary assessment of damages and post‐emergency phase. An explicit estimation of the timber loss caused by Vaia using satellite remote sensing was not yet undertaken. In this investigation, three different estimates of timber loss were compared in two study sites in the Alpine area: pre‐existing local growing stock volume maps based on lidar data, a recent national‐level forest volume map, and an novel estimation of AGB values based on active and passive remote sensing. The compared datasets resemble the type of information that a forest manager might potentially find or produce. The results show a significant disagreement in the different biomass estimates, related to the methods used to produce them, the study areas characteristics, and the size of the damaged areas. These sources of uncertainty highlight the difficulty of estimating timber loss, unless a unified national or regional European strategy to improve preparedness to forest hazards is defined. Considering the frequent impacts on forest resources that occurred in the last years in the European Union, remote sensing‐based surveys targeting forests is urgent, particularly for the many European countries that still lack reliable forest stocks data
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
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