1,720,955 research outputs found
Il contributo di sorgenti locali sull'impatto ambientale da Diossine e Furani
No full textPolychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are ubiquitous contaminants, mainly released into the environment during combustion processes (point sources), but also from other sources (traffic, waste incinerators, uncontrolled combustion). This Ph.D. thesis is aimed to investigate the contribution of a steel plant in NW Italy (700 000 tons of steel/year) to the air concentrations and the deposition fluxes of PCDDs/PCDFs at local level, through the analysis of measured, modelled and literature data. The investigation on PCDD/F air concentration was carried out in an area of 600 km2, using air quality data measured by the institutional monitoring network, data obtained from AERMOD simulations and literature data. The measured air concentrations were consistent with literature values for similar areas, and both the homologue profiles and PCA analyses showed a clear distinction between the monitoring stations and the source profiles. All the previous results were also confirmed by the air dispersion model (AERMOD), that predicted PCDD/F air concentrations due to the steel plant from four to two orders of magnitude lower than those measured in the monitoring stations, highlighting the presence of other sources. AERMOD is one of the most used models for estimating ambient air pollution concentrations; it is a steady-state, plume dispersion model developed by the US Environmental Protection Agency (EPA). The investigation on PCDD/F deposition fluxes was carried out in an area of a 420 km2 area surrounding the plant. Total measured deposition fluxes of PCDD/Fs were consistent with other studies carried out in Italy in urban and suburban areas and in rural European areas; while these were lower than those measured in other European urban/suburban areas or in sites influenced by industrial sources. Furthermore, the measured deposition fluxes were also compared with the pattern of PCDD/Fs in ambient air sampled at the same sites in the previous part of the study. This comparison showed a similarity between air concentration and deposition patterns and a clear distinction from the source. The study was completed with AERMOD simulations, that calculated deposition fluxes of two or three orders of magnitude lower than those measured in two of the three monitoring points; while the model was not able to calculate the deposition fluxes in the most distant monitoring station, because they were under the limit of sensitivity of the model itself . This results confirmed that the unexposed sampling site was not subject to emissions from the steel plant. In conclusion, this study outlines the limited influence of the source in the local PCDD/F both air concentrations and deposition fluxes and at the same time the usefulness of a joint analysis of measured, literature and calculated data to correctly evaluate the role of a source to the local pollution. The study also highlights the usefulness of AERMOD as a complementary tool to define the correct placement of monitoring stations and to locate those areas expected to have the highest air concentrations deriving from a sourc
Deposition fluxes of PCDD/Fs in the area surrounding a steel plant in northwest Italy
No full textThe paper aims at investigating the contribution
of a steel plant located in a rural area in northwestern
Italy (700,000 tons of steel/year) to the deposition
fluxes of Polychorinated Dibenzo-p-dioxins and
Polychorinated dibenzofurans (PCDD/PCDFs) at local
level through the analysis of sampling data, literature
data, and air dispersion model (AERMOD)output data.
Total measured deposition fluxes of PCDD/PCDFs in
three monitoring stations were consistent with other
studies carried out in Italy in urban and suburban areas
and in rural European areas; while these were lower than
those measured in other European urban/suburban areas
or in sites influenced by industrial sources. Furthermore,
the measured fluxes were also compared with the pattern
of PCDD/Fs in ambient air sampled at the same sites in a
previous study. This comparison showed a similarity
between air concentration and deposition patterns of the
samples collected at the three monitoring stations and a
clear distinction of these from the source. The study was
completed with AERMOD simulations, conducted with a
mass mean particle diameter of 0.5 μm, according to the
particle size distribution of the samples collected at the
source. AERMOD calculated deposition fluxes of two to
three orders of magnitude lower than those measured in
two monitoring points; while in the most distant monitoring
station, the deposition fluxes were too low to be calculated by the model. The simulations confirmed that
the most distant monitoring station was not subject to
emissions from the steel plant. The analysis highlighted
the limited influence of the source in the local PCDD/F
deposition fluxes
The role of a steel plant in north-west Italy to the local air concentrations of PCDD/Fs
No full textPolychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) are ubiquitous contaminants, mainly released into the environment during combustion processes (point sources), but also from other sources (traffic, uncontrolled combustion).This study aims at investigating the contribution of a steel plant in NW Italy (700000tons of steelyear-1) to the air concentrations of PCDDs/PCDFs at local level, through the analysis of measured, modelled and literature data. The study was carried out in an area of 600km2, using air quality data measured by the institutional monitoring network, data obtained from AERMOD simulations and literature data.The measured air concentrations were consistent with literature values for similar areas, and both the homologue profiles and PCA analyses showed a clear distinction between the monitoring stations and the source profiles.All the previous results were confirmed by the air dispersion model (AERMOD), that predicted PCDD/F air concentrations due to the steel plant from four to two orders of magnitude lower than those measured in the monitoring stations, highlighting the presence of other sources.This study outlines the limited influence of the source in the local PCDD/F air concentrations and at the same time the usefulness of a joint analysis of measured, literature and calculated data to correctly evaluate the role of a source to the local pollution. The study also highlights the usefulness of AERMOD as a complementary tool to define the correct placement of monitoring stations and to locate those areas expected to have the highest air concentrations deriving from a sourc
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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