1,720,965 research outputs found
Dielectric Properties as a Function of Conductive Particle Size Measured for Mixtures of Conductive and Silica Particles Wetted with Na2SO4
Get PDF4 electrode impedance spectroscopy measurements are applied to a system of conducting coke breeze particles in a nonconducting silica sphere background wetted with Na2SO4 solution. Based on a method used in geological field work, it is known that this type of system exhibits a peak in the phase response as a function of frequency. We vary the size of the conducting particles, the concentration of the electrolytic solution and the volume fraction of conducting particles to verify theoretical predictions about the behavior of this system. The frequency of the phase peak is confirmed to vary roughly as the inverse of the square of the conducting particle radius for particles with radii between 95 and 166 microns, and linear relations are found for the frequency of the phase peak and the electrolytic concentration and the amplitude of the phase peak and conducting particle
volume fraction. Conductivity and dielectric measurements are also explored.Bachelor of Scienc
AC Measurements of Graphene-Superconductor Devices
No full textThe field of quantum transport studies electron motion at low temperatures in nanos-tructures. Exciting electron phenomenon can be engineered by combining device
designs like quantum dots, Josephson junctions, and interferometers with materials
which host physics such as various quantum Hall effects and superconductivity. Com-
binations of these ingredients can be mixed to design a device which is then cooled
down and has its I ́ V curves measured while tuning key physical parameters, such
as magnetic field, temperature, and gate electrode voltages.
These time independent (DC) measurements can provide a wealth of information,
but ultimately they can only access highly averaged physical properties. Fortunately,
this is not a fundamental constraint. By measuring the emission of and response to
higher frequency signals, we are able to access additional properties of our devices.
This dissertation explores two projects related to time oscillating (AC) measure-
ments of graphene devices with superconducting contacts. The first project is related
to the measurement of “Shapiro steps” in graphene based Josephson junctions. By
applying a gigahertz drive to the junction, it becomes possible to probe the dynamics
of the phase difference of the junction. The work presented here explores the effects
of the RF environment on the Shapiro step pattern, and on a bistability observed in
this system.
The second project addresses the noise measured downstream of a superconduct-
ing contact for a device in the quantum Hall regime. Recent work has observed the
coupling of superconductivity to a quantum Hall edge, a promising test-bed for mix-
ing superconductivity with topological physics. However, the signal in real devices
remains fairly small compared to the ideal limit. Noise measurements should allow
us to probe the microscopics in these devices, but we find indications that signals
seemingly related to contact heating obscure the desired signal. Additional devices
which should show a tunable signal amplitude show only very small signal variation,
opening questions about what physical phenomena may be suppressing this noise.</p
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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