1,720,981 research outputs found
Studio delle relazioni ambientali e relative connessioni con patologie respiratorie per la città di Roma
No full textA microscale hybrid modelling system to assess the air quality over a large portion of a large European city
No full textThe role of atmospheric dispersion models is becoming increasingly relevant to assess air pollution urban population exposure for epidemiological studies. Estimating urban air quality is challenging, because of the intrinsic characteristics of cities atmospheric structure, such as high density of primary emissions and presence of local dispersion processes, that produce strong concentration gradients. Therefore, very high spatial resolution simulations may often be required to improve the accuracy of estimations.
The objective of this study is developing a microscale hybrid modelling system (HMS) to carry out, in a reasonable computational time, long-term simulations providing hourly concentration fields at building-resolving scale in extended urban areas in order to calculate annual indicators to evaluate exposure. The proposed system couples two atmospheric dispersion models suited for different scales: a Eulerian chemical transport model, FARM (Flexible Air quality Regional Model), accounting for dispersion phenomena due to regional and local emission sources, and a Lagrangian particle micro-scale dispersion model, PMSS (Parallel Micro Swift Spray), used to compute concentrations induced by vehicular traffic inside the city. The HMS has been applied on 12 × 12 km2 domain in Rome with a horizontal resolution of 4 m for calculating NO2 and PM10 concentrations for all year 2015. This study has been carried out in the frame of project BEEP (Big data in Environmental and occupational Epidemiology), that is an Italian research project in epidemiological field.
Results show that the combined use of the two models reproduces the spatial and temporal variability of the observed atmospheric pollutants with a good agreement. The statistical analysis performed on daily average concentrations proves that the HMS suits the standard acceptance criteria for urban dispersion model evaluation, with a FAC2 of 0.92 and 0.80 and a Fractional Bias of −0.03 and −0.2 for NO2 and PM10 respectively.
Furthermore, the implementation of an innovative kernel method to calculate concentrations in PMSS has made possible to reduce the computational time by 80%, leading to an average computational time of 3 h per simulated day on an HPC (High Performance Computing) system with 180 cores
PAHs urban concentrations maps using support vector machines
No full textAir pollution health effects studies are based on data collected by
monitoring stations. Pollutant exposure maps greatly improve the evaluation of
health effects. The study of exposure to polycyclic aromatic hydrocarbons
(PAHs) in urban areas is one of the goals of the EXPAH LIFE+ Project. An
integrated approach has been applied to simulate PAHs levels in the urban area
of Rome. In particular, support vector machines (SVMs) were applied to
reconstruct PAHs urban concentrations. Starting from PAHs results provided
by a chemical transport model (CTM) FARM and observed data collected in
field campaigns of PM2.5 with PAHs content between June 2011 and May
2012, SVM methods were applied to build a model able to forecast PAHs
exposure. The SVM has shown excellent results in reproduction of
experimental data, improving those achieved by the FARM model. Finally, the
SVM has produced very congruent PAHs exposure maps
PAHs urban concentrations maps using support vector machine
No full textThe studies about health effects are often based on data inferred by monitoring stations. For this purpose, pollutants exposure maps are crucial for evaluating health effects. Studying the Polycyclic Aromatic Hydrocarbons (PAHs) and the Benzo(a)Pyrene (BaP) exposure in urban areas is the major goal of the EXPAH LIFE+ Project. An integrated approach, based on measurements and modeling techniques, was applied to simulate PAHs and BaP levels in the Rome metropolitan area. Field campaigns of PM2.5 with PAHs content were performed for the period June 2011 - May 2012, and a chemical transport model (FARM) was applied to reconstruct PAHs urban concentrations. In this work, Machine Learning methods have been applied to forecast atmospheric pollution, trying also to improve the results achieved by FARM. In particular, Support Vector Machines (SVMs) have been used. They represent one of the most common approaches among Machine Learning methods. Starting from the experimental data, SVM methods have been applied to build models able to forecast PAHs and BaP exposure. The SVM models seem to show excellent results in the reproduction of experimental data and in generalization, improving those achieved by FARM. Finally, the SVM models have produced very congruent PAHs and BaP exposure maps
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
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