1,721,038 research outputs found
Towards a Reproducible Pan-European Soil Erosion Risk Assessment - RUSLE
Get PDFSoil is a valuable, non-renewable natural resource that offers a multitude of ecosystems goods and services. Given the increasing threat of soil erosion in Europe and the implications this has on future food security and water quality, it is important that land managers and decision makers are provided with accurate and appropriate information on the areas more prone to erosion phenomena. The present study shows an attempt to locate, at regional scale, the most sensitive areas and to highlight any changes of soil erosion trends with climate change. The choice of the input datasets is crucial as they have to offer the most homogeneous and complete covering at the pan-European level and to allow the produced information to be harmonized and easily validated. The model is based on available datasets (HWSD, SGDBE, SRTM, CLC and E-OBS) and The Revised Universal Soil Loss Equation (RUSLE) is used because of its flexibility and least data demanding. A significant effort has been made to select the better simplified equations to be used when a strict application of the RUSLE model was not possible. In particular for the computation of the Rainfall Erosivity factor a validation based on measured precipitation time series (having a temporal resolution of 10-15 minutes) has been implemented to be easily reproducible. The validation computational framework is available as free software. Designing the computational modeling architecture with the aim to ease as much as possible the future reuse of the model in analyzing climate change scenarios has also been a challenging goal of the research
Role of humic acids in the TiO(2)-photocatalyzed degradation of tetrachloroethene in water
No full textThe effect of humic acids on the TiO(2)-mediated photocatalytic degradation of tetrachloroethene (PCE) was kinetically investigated at different pH and initial substrate concentrations. The pro cess occurs through two parallel paths: a major oxidative route leading to mineralization and a reductive route leading to the formation of dichloroacetic acid (DCAA), also undergoing photodegradation. The rate of PCE decomposition was found to decrease in the presence of humic acids adsorbed on the semiconductor surface, while the concentration of the intermediate dichloroacetic acid increased. This is a consequence of the scavenging action bf humic acids toward photoproduced surface oxidant species, which makes conduction band electrons more easily available for interface reactions. Kinetic studies on the effect of humic acids in the TiO(2)-mediated photodegradation of dichloroacetic acid showed that the progressively greater accumulation of this highly toxic intermediate, observed with increasing humic acids content, was a consequence of both an increase in the rate of its production from PCE and a decrease in the rate of its oxidative photodegradation. (C) 1999 Elsevier Science Ltd. All rights reserved
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
Consumo di suolo e sicurezza alimentare: alcuni dati sulle tendenze europee
No full textIl suolo è una risorsa multifunzionale, limitata, non rinnovabile. Con la progressiva affermazione del concetto di servizi ecosistemici al suolo vengono riconosciute non solo funzioni di supporto alla produzione di biomasse (alimenti, fibre, etc.), ma anche altre fondamentali funzioni, tra le quali la regolazione del ciclo dell’acqua, la regolazione della fertilita’ del suolo e di molti cicli biogeochimici, il supporto fisico alle attivita’ dell’uomo, etc.
Se tuttavia consideriamo queste funzioni da un punto di vista utilitaristico ed antropocentrico, la produzione di biomassa, e quella di alimenti in particolare, costituiscono la funzione piu’ importante. Sia sufficiente pensare che oltre il 95 % degli alimenti necessari a sostenere l’umanita’ sono prodotti, direttamente o indirettamente, dal suolo (elaborazioni Dati Annuario Statistico Fao 2007-2008). Se consideriamo poi la progressiva, preoccupante riduzione degli stock ittici, che presso alcune popolazioni costituiscono una importante integrazione della dieta, e’ evidente che il contributo del suolo, quale mezzo per la produzione di alimenti, sia destinato ad aumentare.
Tra molte di tali funzioni esiste la possibilita’ di coesistenza e cioè l’utilizzazione e la massimizzazione di una certa funzione (es. produzione di biomassa), non preclude la possibilita’ di assolvere ad altre funzioni (es. regolazione del ciclo dell’acqua, riserva di carbonio, riserva di biodiversità). Esistono dei trade-off tra queste funzioni, che tuttavia non comportano necessariamente una completa esclusione di alcune di esse. Vi è tuttavia un’unica funzione che preclude tutte le altre, ed e’ l’utilizzazione del suolo come supporto fisico delle strutture create dall’uomo. Per utilizzare un termine piu’ chiaro ed immediato, i processi di urbanizzazione (in senso lato), che comportano l’impermeabilizzazione di aree piu’ o meno vaste, la frammentazione del territorio, l’alterazione del clima e del ciclo dell’acqua, si ripercuotono a loro volta sulla capacita’ di sostenere le produzioni agricole.JRC.H.5 - Land Resources Managemen
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
Towards the reproducibility in soil erosion modeling: a new pan-European soil erosion map
Get PDFSoil erosion by water is a widespread phenomenon throughout Europe and has the potentiality, with his on-site and off-site effects, to affect water quality, food security and floods. Despite the implementation of numerous and different models for estimating soil erosion by water in Europe, there is still a lack of harmonization of assessment methodologies.
Often, different approaches result in soil erosion rates significantly different. Even when the same model is applied to the same region the results may differ. This can be due to the way the model is implemented (i.e. with the selection of different algorithms when available) and/or to the use of datasets having different resolution or accuracy. Scientific computation is emerging as one of the central topic of the scientific method, for overcoming these problems there is thus the necessity to develop reproducible computational method where codes and data are available.
The present study illustrates this approach. Using only public available datasets, we applied the Revised Universal Soil loss Equation (RUSLE) to locate the most sensitive areas to soil erosion by water in Europe.
A significant effort was made for selecting the better simplified equations to be used when a strict application of the RUSLE model is not possible. In particular for the computation of the Rainfall Erosivity factor (R) the reproducible research paradigm was applied. The calculation of the R factor was implemented using public datasets and the GNU R language. An easily reproducible validation procedure based on measured precipitation time series was applied using MATLAB language. Designing the computational modelling architecture with the aim to ease as much as possible the future reuse of the model in analysing climate change scenarios is also a challenging goal of the research
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
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