1,721,301 research outputs found
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
Idrocarburi policiclici aromatici cancerogeni urinari : confronto tra soggetti con e senza esposizione occupazionale
No full textAn automatic SPME/GCMS assay to measure mono and dihydrohy naphthalenes in human urine
No full textDue to its toxicological relevance and its large presence in working and living environments the need for a specific biological monitoring of naphthalene exposure is recognize. The traditional assay to measure naphthalene metabolites in urine employs time consuming sample preparation, typically performed by liquid-liquid or solid phase extraction, followed by chromatographic analysis. Aim of this work was to set a simple and automatic assay to measure naphthalene mono and dihydroxy metabolites in human urine and to test its applicability in biological monitoring.
Solid phase microextraction (SPME) with on-fiber derivatization was chosen for sample preparation. Optimization was carried on using several fiber coatings and different silylating agents. Stability of the samples was obtained by addition of an antioxidant solution. Separation and detection of the analytes was obtained by GC/MS. The presence of naphthalene metabolites in subjects with different exposures was assayed.
A novel and automatic SMPE GC/MS assay in which 1- and 2-naphthol, and 1,2-, 1,4-, 1,7- and 2,6- dihydroxynaphthols were directly sampled from urine and derivatized by immersion of a PDMS-DVB fiber in silylating agent vapours, was set. Preliminary results obtained analyzing urine samples of non-smoking and smoking not occupationally exposed subjects, and coke oven workers showed levels in the range of those obtained using a traditional approach.
The developed assay is simple, and time and reagent saving. It opens interesting perspectives to enlarging biomonitoring of naphthalene exposure in human
Self-collected urine sampling to study the kinetics of urinary toluene (and o-cresol) and define the best sampling time for biomonitoring
No full textPurpose To study the excretion kinetics of urinary toluene,
TOL-U, and o-cresol, o-C, following occupational
exposure to toluene in order to define the best time for
sample collection, to apply a non-invasive approach based
on self-collected urine sampling.
Methods Five rotogravure printing workers exposed to
uncontrolled levels of toluene collected spot urine samples
over three consecutive working days and the following day
of rest. In each sample TOL-U and o-C were measured and
kinetics of excretion evaluated.
Results Toluene exposure ranged from 48.3 to 75.3 mg/
m3; TOL-U and o-C ranged from 1.4 to 34.6 lg/L and from
0.013 to 1.012 mg/L. A time course trend was obtained:
TOL-U and o-C increased during the shift and peaked at
the end of exposure and up to 2 h later, respectively;
afterwards they rapidly decreased following apparent first
order kinetics. Considering TOL-U, the elimination halflife
for the first fast phase was 79 (±35 standard error) min,
and for the second slow phase was 1,320 (±1,162) min. For
o-C the elimination half-life for the first fast phase was 231
(±48) min. Considering a toluene uptake of 86%, TOL-U
and o-C excreted in urine were about 0.0067 and 0.18% of
the up taken.
Conclusion Our results support the use of end shift TOLU
as a short term biomarker of occupational exposure to
toluene and show the feasibility of self-collected urine
sampling to investigate the elimination kinetics of industrial
toxics in humans
Development of a gas chromatography/mass spectrometry method to quantify several urinary monohydroxy metabolites of polycyclic aromatic hydrocarbons in occupationally exposed subjects
No full textThe aim of this studywas the development of a method for the determination of 12 urinary monohydroxy metabolites of PAHs, namely 1-hydroxynaphthalene, 2-hydroxynaphthalene, 2-hydroxyfluorene, 9-hydroxyfluorene,
1-hydroxyphenanthrene,2-hydroxyphenanthrene, 3-hydroxyphenanthrene, 4-hydroxyphenanthrene,
9-hydroxyphenanthrene, 1-hydroxypyrene,6-hydroxychrysene, and 3-hydroxybenzo[a]pyrene. Analytes were determined in the presence of deuterated analogues as internal standards, by GC/MS operating in the electron impact mode. Sample preparationwas performed by enzymatic
hydrolysis of glucoronate and sulphate conjugates of hydroxy metabolites of PAHs, liquid–liquid extraction with n-hexane, and derivatization with a silylating reagent. The method is very specific, limits of quantification are in the range 0.1–1.4 μg/l, and range of linearity is from limit of detection to 208 μg/l.Within- and between-run precision, expressed as coefficient of variation, are <20%; accuracy for most analytes is within 20% of the theoretical value. An application of the proposed method to the analysis of 10 urine samples from coke-oven workers shows that 1-hydroxynaphthalene and 2-hydroxyfluorene
were the most abundant compounds (median 61.4 and 69.7 μg/l, respectively), while 6-hydroxychrysene,and 3-hydroxybenzo[a]pyrene were always below the quantification limit
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