1,720,970 research outputs found
Atmospheric transport modelling of time resolved 133Xe emissions from the isotope production facility ANSTO, Australia
No full textAtmospheric transport modelling of 133Xe: a case study of the emissions from the isotope production facility ANSTO, Australia
No full text
Unprecedented xenon collection and separation from air on silver-exchanged zeolites
No full textLow level measurements of atmospheric radioxenon, such as for the verification of the Comprehensive Nuclear-Test-Ban Treaty, require complex collection, separation and detection systems. The collection and separation of Xe in this context is particularly challenging owing to its very low natural abundance in air (i.e. 87 ppb) and its inertness. For the detection part, the collected Xe gas needs also to be depleted of Rn to minimize interferences on the radioxenon detection. Historically, the collection and separation of atmospheric radioxenon has been performed with a complex succession of adsorptive columns using molecular sieves and activated carbons. In this work, we demonstrate the potential of two silver-exchanged zeolites to collect and separate Xe directly from dry air in a single adsorptive column. These two silver-exchanged zeolites show unprecedented Xe adsorption capacities in air (> 3 cm³SATP/kg) and Xe selectivities in air (> 1000). They also allow to efficiently separate Xe from Rn and thermally recover Xe with a high purity. However, the moisture content of the gas stream can have a negative effect on the xenon adsorption properties in these adsorbents. The results are compared to a typical activated carbon, used in this context, but also to two metal-organic frameworks with promising properties for Xe/Kr separation
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
Unprecedented xenon collection and separation from air on silver-exchanged zeolites
No full textLow level measurements of atmospheric radioxenon, such as for the verification of the Comprehensive Nuclear-Test-Ban Treaty, require complex collection, separation and detection systems. The collection and separation of Xe in this context is particularly challenging owing to its very low natural abundance in air (i.e. 87 ppb) and its inertness. For the detection part, the collected Xe gas needs also to be depleted of Rn to minimize interferences on the radioxenon detection. Historically, the collection and separation of atmospheric radioxenon has been performed with a complex succession of adsorptive columns using molecular sieves and activated carbons. In this work, we demonstrate the potential of two silver-exchanged zeolites to collect and separate Xe directly from dry air in a single adsorptive column. These two silver-exchanged zeolites show unprecedented Xe adsorption capacities in air (> 3 cm³SATP/kg) and Xe selectivities in air (> 1000). They also allow to efficiently separate Xe from Rn and thermally recover Xe with a high purity. However, the moisture content of the gas stream can have a negative effect on the xenon adsorption properties in these adsorbents. The results are compared to a typical activated carbon, used in this context, but also to two metal-organic frameworks with promising properties for Xe/Kr separation
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