1,720,984 research outputs found
Nanomaterials as Soil Pollutants
Get PDFThis chapter covers how engineered nanomaterials (ENMs) may enter soils, how they behave in soils, the exposure dynamics this presents to soil organisms, and resulting issues for uptake and food-chain transfer. Special attention is given to summarizing the main issues and the current state of the art for the most important elements of how ENMs act as pollutants in soil, namely: The routes and consequent forms of entry of ENMs from nanoenabled products into soils; the fate and transformations ENMs undergo in soil systems; ENM bioavailability to and interactions with soil biology, including exposure and hazard assessment, toxicokinetics, and trophic transfer
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
Organic contaminants in urban soils: major inputs and potential risks
Get PDFDoutoramento em QuímicaUrban soil quality may be severely affected by hydrophobic organic
contaminants (HOCs), impairing environmental quality and human health. A
comprehensive study was conducted in two contrasting Portuguese urban
areas (Lisbon and Viseu) in order to assess the levels and potential risks of
these contaminants, to identify sources and study their behaviour in soils. The
concentrations of HOCs were related to the size of the city, with much higher
contamination levels observed in Lisbon urban area. Source apportionment
was performed by studying the HOCs profiles, their relationship with potentially
toxic elements and general characteristics of soil using multivariate statistical
methods. Lisbon seems to be affected by nearby sources (traffic, industry and
incineration processes) whereas in Viseu the atmospheric transport may be
playing an important role. In a first tier of risk assessment (RA) it was possible
to identify polycyclic aromatic hydrocarbons (PAHs) in Lisbon soils as a
potential hazard. The levels of PAHs in street dusts were further studied and
allowed to clarify that traffic, tire and pavement debris can be an important
source of PAHs to urban soils. Street dusts were also identified as being a
potential concern regarding human and environmental health, especially if
reaching the nearby aquatic bodies. Geostatistical tools were also used and
their usefulness in a RA analysis and urban planning was discussed.
In order to obtain a more realistic assessment of risks of HOCs to environment
and human health it is important to evaluate their available fraction, which is
also the most accessible for organisms. Therefore, a review of the processes
involved on the availability of PAHs was performed and the outputs produced
by the different chemical methods were evaluated. The suitability of chemical
methods to predict bioavailability of PAHs in dissimilar naturally contaminated
soils has not been demonstrated, being especially difficult for high molecular
weight compounds. No clear relationship between chemical and biological
availability was found in this work. Yet, in spite of the very high total
concentrations found in some Lisbon soils, both the water soluble fraction and
the body residues resulting from bioaccumulation assays were generally very
low, which may be due to aging phenomena. It was observed that the
percentage of soluble fraction of PAHs in soils was found to be different among
compounds and mostly regulated by soil properties. Regarding
bioaccumulation assays, although no significant relationship was found
between soil properties and bioavailability, it was verified that biota-to-soil
bioaccumulation factors were sample dependent rather than compound
dependent. In conclusion, once the compounds of potential concern are
targeted, then performing a chemical screening as a first tier can be a simple
and effective approach to start a RA. However, reliable data is still required to
improve the existing models for risk characterization.A qualidade dos solos urbanos pode ser afetada por contaminantes orgânicos
hidrofóbicos (HOCs), prejudicando a saúde ambiental e humana. Este trabalho
consistiu em estudar duas áreas urbanas contrastantes (Lisboa e Viseu), com
o objetivo de avaliar os níveis de HOCs nos solos e os seus potenciais riscos
para a saúde humana e para o ambiente. Pretendia-se ainda identificar as
fontes e estudar o comportamento destes contaminantes no solo. Foi possível
relacionar as concentrações de HOCs com o tamanho da cidade, sendo os
níveis de contaminação muito mais elevados em Lisboa. A identificação das
fontes destes contaminantes foi feita através do estudo dos respetivos perfis e
da relação com elementos potencialmente tóxicos, utilizando métodos
estatísticos multivariados. Lisboa parece ser afetada por fontes próximas
(tráfego, indústria e incineração) enquanto em Viseu o transporte atmosférico
aparenta ter um papel mais importante. Num primeiro nível da avaliação de
risco (RA), foi possível identificar os hidrocarbonetos aromáticos policíclicos
(PAHs) nos solos de Lisboa como um perigo potencial. Os níveis de PAHs em
poeiras das ruas de Lisboa foram também estudados e permitiram clarificar
que o tráfego e os detritos de pneus e de pavimento podem também ser uma
importante fonte destes compostos. Utilizaram-se e discutiram-se ferramentas
de geoestatística assim como a respetiva utilidade em RA e em planeamento
urbano. De modo a obter uma avaliação mais realista dos riscos de HOCs é
importante avaliar a fração disponível, que é também a mais acessível para os
organismos. Deste modo, foi feita uma avaliação dos processos envolvidos na
disponibilidade de PAHs e também dos resultados obtidos pelos diferentes
métodos químicos. A adequação dos métodos químicos para prever a
biodisponibilidade de PAHs em solos naturalmente contaminados ainda não foi
demonstrada, sendo especialmente difícil para os compostos de elevado peso
molecular. No presente trabalho também não foi possível estabelecer uma
relação significativa entre a disponibilidade química e a biodisponibilidade. No
entanto, apesar das elevadas concentrações totais encontradas em alguns
solos de Lisboa, tanto a fração solúvel em água como os resíduos acumulados
nos ensaios de bioacumulação foram, em geral, muito baixos, o que estará
relacionado com os fenómenos de envelhecimento destes contaminantes nos
solos. Observou-se que a fração solúvel de PAHs depende do composto em
causa e é regulada pelas propriedades do solo. Apesar de não se terem
observado correlações entre as propriedades do solo e a biodisponibilidade,
observou-se que os fatores de bioacumulação dependem mais da amostra do
que do composto. Em conclusão: após a identificação dos contaminantes de
interesse uma avaliação química baseada nos teores totais pode ser uma
abordagem eficaz no primeiro nível da RA, mas no entanto é necessário
melhorar os modelos existentes para a caracterização do risco
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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