1,721,130 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
Implementing light elements detection and quantification in aluminosilicate materials using a Low-Z total-reflection X-ray fluorescence spectrometer
Full text linkTotal-reflection X-ray fluorescence (TXRF) is a well-established atomic spectroscopy technique used for the elemental characterization of different kinds of matrixes in several fields. Previous works demonstrated its applicability for the elemental quantification of aluminosilicates and, in particular, clays. However, one of the limits of the previously developed methods was the detection and quantification of light elements, in particular for those elements with an atomic number (Z) below 13 (Al). In the present work a new TXRF-based analytical method for the quantification of light elements in aluminosilicate materials is described, using an in-house built Low-Z TXRF spectrometer equipped with a Cr source, a multilayer monochromator, an SDD detector equipped with an ultrathin Si3N4 window and a vacuum chamber. Samples were prepared as simple slurries (dispersing 50 mg of powder into 2.5 mL of 1%-Triton X-100 water solution and adding Ag as internal standard) and 10 μL were deposited onto a quartz carrier and dried before the analysis. Light elements such as F, Na and Mg were quantified with a limit of detection of 682, 260 and 133 mg/kg, respectively. Carbon and oxygen could also be detected. The new method allowed a complete analysis of major elements in aluminosilicates from F to Fe. The method showed a good accuracy in the range of 80–120% and the results agreed with the data obtained with a commercial TXRF spectrometer (for elements >13) and WDXRF, employed as reference methods. Despite a lower precision in respect to WDXRF, in some samples the quantification of F was possible only by using the Low-Z TXRF spectrometer. Finally, the method demonstrated to be suitable for the analysis of aluminosilicates, in particular when low amounts of sample (few milligrams) are available
Low-Z TXRF spectrometer: a new strategy for the quantification of light elements in clays
No full textClay minerals are a very important constituent of soils which influence several bulk properties such
as water retention and cation exchange capacity. Moreover, they are used in many environmental
fields (i.e. landfill isolation, water depuration, soil remediation, etc) due to their properties and
capability to adsorb potentially toxic elements and pollutant. Both in soil science and environmental
studies the full characterization of the clay fraction should be performed for the whole comprehension
of the soil behavior and/or for the assessment of remediation strategies. Together with mineralogical
and physical investigations, chemical analysis of clays is a crucial step in their study and
characterization. Elemental analysis is usually performed by ICP-AES, ICP-MS, after complete
mineralization of the sample, or by EDXRF and WDXRF, using 1 - 5 g of material. However, in
some soils the clay fraction is not very abundant and the procurement of the suitable quantity of
sample can led to very high time-consuming sedimentation procedure. Also in sorption studies, where
a very few amount of sample is usually tested, the procurement of the suitable amount of clay sample
can be a problem. Total-reflection X-ray fluorescence spectroscopy proved to be a valuable method
for the analysis of these very small samples. A method for the elemental analysis of clays using TXRF
was already developed [1] but light elements like Na and Mg could not be quantified due to the
limitations of commercially available spectrometers for the analysis of light elements. However, the
quantification of these two elements is very important for an exhaustive chemical characterization of
aluminosilicates.
For this reason, in the present work, a new strategy for the analysis of light elements in clays is
presented. The study was carried out using a Low-Z TXRF spectrometer [2] equipped with a Cr
source (30 kV, 10 mA), an Atominstitut TXRF Vacuum Chamber (1 mbar), a W/C multilayer
monochromator and a SDD with an ultrathin Si3N4 window [3]. A set of six different aluminosilicaterock reference materials was used for calibration and other three reference materials were used for
validation. Samples were prepared as suspension using Ag as internal standard. In this way, all the
elements from F to Ti were detected and quantified with good accuracy (80 - 120%). Moreover, Fe
was also quantified using Lα lines. The obtained results will be discussed on both the analytical and
applicative point of view, with the aim of identifying the best equipment and condition for a full
elemental characterization of aluminosilicate
Direct analysis of light elements in aluminosilicates using a Low-Z TXRF spectrometer
No full textAluminosilicates are the most abundant minerals on the earth and are widely studied and exploited for both research and industrial purposes. Together with mineralogical and physical investigations, chemical analysis of aluminosilicates is a crucial step in their study and characterization. Due to their abundance, sample procurement is not a problem and elemental analysis is usually performed by ICP-AES, ICP-MS, after complete mineralization of the sample, or by EDXRF and WDXRF, using 1-5 g of material. However, in some fields of research (i.e. ceramic archaeometry, material synthesis, catalysis, sorption studies, clays extraction from sediments and soils, etc.) only a very few amount of sample is usually available, and a method which could allow a reliable chemical analysis and preserve the sample as much as possible is required. A method for the elemental analysis of clays using TXRF was already developed[1] but light elements like Na and Mg could not be quantified due to the limitations of commercially available spectrometers for the analysis of light elements. However, the quantification of these two elements is very important for an exhaustive chemical characterization of aluminosilicates.
For this reason, in the present work, a new strategy for the analysis of light elements in aluminosilicates is presented. The study was carried out using a Low-Z TXRF spectrometer equipped with a Cr source (30 kV, 10 mA), an Atominstitut TXRF Standard Vacuum Chamber (1 mbar), a W/C multilayer monochromator and a SDD with an ultrathin polymer window[2]. A set of six different aluminosilicate-rock reference materials was used for calibration and other three reference materials were used for validation. Samples were prepared as suspension using Ag as internal standard. In this way, all the elements from F to Ti were detected and quantified with good accuracy (80-120%). Moreover, Fe was also quantified using Lα lines. The obtained results will be discussed on both the analytical and technological point of view, with the aim of identifying the best equipment and condition for a full elemental characterization of aluminosilicates
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
- …
