1,721,168 research outputs found
The theory and EPR spectra of linear free radicals
No full textThis dissertation is concerned mainly with the theory needed to explain the gas-phase electron paramagnetic resonance spectra of linear free radicals.The Hamiltonian operator describing the system is obtained by transforming the Pauli-Schrodinger form of the Breit equation from a space-fixed to a molecule-fixed axis system. From this an effective Hamiltonian, operating in just the ground vibronic state is derived. This is then used to interpret the e.p.r, spectra of NS and CF. We obtain the electric dipole moment and information on the hyperfine parameters of these radicals.The theory applicable to the energy levels of linear triatomic molecules is derived and the effects of the bending vibration on the e.p.r. spectra are obtained. Finally, the effects of case (c) coupling on the spectra of diatomic molecules are discussed; it is proposed that these are the cause of the discrepancies observed in the spectra of certain heavy molecules
Thermochemical hydrogen production from the sulphur-iodine cycle powered by solar or nuclear sources
No full textSince mankind's adoption of fossil fuels as its primary energy carrier for heating, elec-
tricity and transportation, the release of greenhouse gases into the atmosphere has
increased constantly . A potential replacement energy carrier is hydrogen. Current
industrial techniques for dissociating hydrogen from its common substances are con-
ventionally reliant on fossil fuels and thus greenhouse gases are still released. As a
mechanism to develop a hydrogen economy current industrial techniques will suffice;
however, a long-term sustainable solution to hydrogen mass production that does not
release greenhouses gases is desired. The United States of America Government be-
lieves that the Sulphur-Iodine thermochemical hydrogen production cycle, thermally
powered by a nuclear source, is the most likely long-term solution. A critical part
of the Sulphur-Iodine cycle is the point of interaction between the thermal source
and sulphuric acid used within the cycle. A novel bayonet heat exchanger made
from silicon carbide is theoretically applied to the point of interaction. Through a
combination of experiments and theoretical modelling, the bayonet heat exchanger is
characterised. The bayonet model is then modified to simulate the intended nuclear
reactor favoured by the United States Department of Energy. In addition, the bayo-
net heat exchanger is analysed for a solar thermal application. An advanced design
of the bayonet is also presented and theoretically analysed for its increased thermal
efficiency
High resolution spectroscopy of open shell clusters
Full text linkThe microwave spectrum of the open-shell van der Waals complex NO-HF has been recorded in the region 6-20GHz using a pulsed nozzle Fourier transform microwave spectrometer. This is the first observation of the microwave spectrum of a open-shell van der Waals complex between two molecules. The spectrum exhibits a rich hyperfine structure with the observation of intermolecular hyperfine interactions in an isolated system providing a sensitive probe of electron transfer in the complex.The spectrum consists of four fine structure transitions 5/2(e)-3/2(e), 3/2(e)-1/2(e), 5/2(f)-3/2(f), 3/2(f)-1/2(f) which have been fitted to a semi-rigid Hamiltonian developed to include the effects of the orbital and spin angular momenta of the unpaired electron on NO. A new treatment to account for the intermolecular hyperfine interaction was developed. The structure of the complex has been determined and is significantly bent with an angle of between 37 degrees and 49 degrees between the NO internuclear axis and the a-axis of the complex. The Renner-Teller parameter, epsilon 2, is very large and negative having the value of -10 449.32(4)GHz indicating that configuration with the unpaired electron in the plane of the complex is more stable.The analysis of the hyperfine interactions of the hydrogen and fluorine nuclei uses two constants for each nucleus, one for the spatial relationship between the magnetic moments of the unpaired electron and the nuclear magnetic moment and a Fermi-contact term.The Fermi-contact term for hydrogen is the first strong evidence of intermolecular charge transfer in an isolated van der Waals molecule
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
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
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