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Plasticity as a depinning phase transition
Get PDFCrystalline materials deform in an intermittent way with slip-avalanches that are power-law distributed.
In this work we study plasticity as a pinning-depinning phase transition employing a discrete dislocation
dynamics (DDD) model and a phase eld crystal (PFC) model in two dimensions. Below a critical (
ow)
stress, the dislocations are pinned/jammed within their glide plane due to long-range elastic interactions
and the material exhibits plastic response. Above this critical stress the dislocations are mobile (the depinned/
unjammed phase) and the material constantly
ows.
We employ discrete dislocation dynamics to resolve the temporal pro les of slip-avalanches and extract
the nite-size scaling properties of the slip-avalanche statistics, going beyond gross aggregate statistics of
slip avalanche sizes. We provide a comprehensive set of scaling exponents, including the depinning exponent
. Our work establishes that the dynamics of plasticity, in the absence of hardening, is consistent with the
mean eld interface depinning universality class, even though there is no quenched disorder.
We also use dislocation dynamics and scaling arguments in two dimensions to show that the critical stress
grows with the square root of the dislocation density (Taylor's relation). Consequently, dislocations jam at
any density, in contrast to granular materials, which only jam above a critical density.
Finally, we utilize a phase eld crystal model to extract the size, energy and duration distributions of
the avalanches and show that they exhibit power law behavior in agreement with the mean eld interface
depinning universality class.Item withdrawn by Mark Zulauf ([email protected]) on 2012-03-02T20:35:35Z
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Studies towards the development of label-free AC impedimetric immunosensors for healthcare and food quality control
Get PDFThis thesis describes work focused towards the fabrication and characterisation of
immunosensor platforms for the label-free detection of analytes of importance in the
health and food industries. Due to their low unit cost and ease of fabrication, the
immunosensor market has significantly increased recently, resulting in a constant
demand for new immunosensor applications. Within this thesis, therefore, a novel
fabrication protocol is reported towards the production of immunosensor platforms for
the detection of the antibiotic, ciprofloxacin, the stroke and multiple sclerosis marker,
Myelin Basic Protein (MBP) and the ovarian cancer marker CA-125.
Initial investigations were aimed towards the electrochemical characterization of the
available electrode substrates at the onset of this research project namely, gold sputter
coated, screen-printed gold and carbon electrodes. They showed that only carbon
electrodes provide sufficiently reproducible results and thus these electrodes have
been employed for immunosensor fabrication. Due to the advantages of
microelectrodes over planar electrodes, attempts to fabricate microelectrode arrays
were also made via the ultrasonic ablation of passivated electrode assemblies.
For the site-specific immobilisation of antibodies on polymer modified surfaces
biotin-neutravidin affinity technologies were used. The fabricated immunosensors
were then interrogated upon exposure to antigen solutions utilising the technique of
electrochemical impedance spectroscopy (EIS). Changes in the obtained impedance
spectra were used to plot calibration profiles for the detection of ciprofloxacin in
buffer and in milk. Similar profiles have been plotted for Myelin Basic Protein (MBP)
and the ovarian cancer marker CA-125
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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