1,720,963 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
Photothermal investigation of magnesium oxysulfate cement
No full textThe effect of polyvinyl acetate polymer (PVAc) on thermal performance and compressive
strength of magnesium oxysulfate cement has been investigated. The PVAc polymer was added to the
cement matrix of 0%, 5%, 10%, 15% and 20% of MOS weight. The thermal properties of MOS cement
were determined by Photothermal Deflection Technique (PTD). Thermal properties such as thermal
conductivity and thermal diffusivity is measured by fitting the experimental curves of photothermal signal
to the best corresponding theoretical curves. The results revealed that the incorporation of PVAc polymer
enhance the thermal insulation and reduce the compressive strength of MOS cement. The addition of 10%
PVAc polymer has been improved the thermal performance of cement compared to others specimens. The
key to reducing properties is the size and amount of air bubbles formed in the cement matrix
Investigation on the thermal properties of magnesium oxychloride cement prepared with glass powder
No full textThe objective of this study was to investigate the thermal property of magnesium oxychloride cement (MOC) using
glass powder as a substitute. Glass powder by proportion 0%, 5%, 10%, 15% and 20% of cement’s weight was added to
specimens. At the end of a drying time of 28 days, thermal properties, compressive strength and bulk density of samples were
determined. Thermal property is measured by Photothermal Deflection Technique by comparing the experimental of
normalized amplitude and the phase curves of the photothermal signal to the corresponding theoretical ones. The findings
indicate that incorporation of glass powder decreases the thermal properties of MOC
The effect of the incorporation of glass powder into cement sorel
No full textThe work concerns thermo-mechanical properties of cement Sorel mixed with different proportions of glass powder.
Five specimens were developed. Four different glass powder mixtures were developed 5%, 10%, 15% and 20% with one control
sample without glass powder. The research presented in this study focused on evaluating the effects of replacing portion of
glass powder with various percentages of cement Sorel. The influence of the glass powder on the thermal conductivity, thermal
diffusivity, bulk density and compressive strength of the cement Sorel at 28 days of curing were determined. The thermal
property of cement was measured by using Photothermal deflection technique PTD. The results revealed that the glass powder
additive affected greatly on the thermal properties of the cement
Investigation of thermal properties of cement Sorel by photothermal deflection technique
No full textPhotothermal deflection PTD is a non destructive Technique. PTD is based on the photothermal
phenomenon, in which a modulated incident light on the specimen is transformed into heat and
detected as a tension by using a position photodetecor linked to a lock in amplifier. The signal depends
directly on the thermal properties (Thermal conductivity, thermal diffusivity) of the specimen [1]. In
this work we investigated the thermal property of cement Sorel (CS). Nowadays, the development of
composite construction materials with low thermal properties will be an interesting alternative that
would solve energy concerns. In this context, we investigate the effect of replacing Sorel cement with
polymer PVAc [2]. The thermal properties are measured using the Photothermal Deflection Technique
(PTD) by comparing the experimental curves of normalized amplitude and phase of photothermal
signal versus square root modulation frequency to the corresponding theoretical ones. The
experimental investigation revealed that the addition of the PVAc reduces the Thermal conductivity
and thermal diffusivity of the cement and yield a lightweight. The thermal insulating effect of PVAc is
attractive and indicates a high and promising potential for development
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
Thermal lens spectrometric detection of ▫▫ in aqueous solutions
No full textManganese (Mn2+) is an essential trace element required for normal body functions, but high levels can
be toxic to organs as it can damage liver and heart or introduce disorders to fetus and cause
disfuntionality of reproductive system [1]. Thus, it is of high importance to monitor its amounts in the
environment. In the work the thermal lens spectrometry (TLS) was applied to detect the trace amounts
of Mn2+ in water [2]. The detection is based on the adsorption of Mn²⁺ ions onto the surface of silver
nanoparticles (Ag0 NPs), which were synthesized by the reduction of Ag⁺ ions to Ag0 using BH4- as a
reducing agent and a stabilizer. Manganese solutions with concentrations ranging from 0.5 µM to 10 µM
were prepared. The calibration curve showed good linearity over the examined concentration range (Fig.
1). The obtained limit of detection (LOD) and limit of quantification (LOQ) were 20 and 68 nM,
respectively and confirmed high sensitivity of the method. Furthermore, the method shows both good
repeatability and reproducibility, as well as high precision and accurcy with RSD not exceeding 3%. The
maximum contamination level (MCL) of Mn2+ in water is 0.91 µM (0.05 mg/L), wich indicates values
higher than LOD [3]. The results indicate that the proposed TLS-based method is a simple and reliable
technique for determination of metal ions in water
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
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