1,721,011 research outputs found
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
The role of copper ions and lipid membranes in Tau protein aggregation linked to neurodegenerative diseases
Get PDFThe tau protein, which is normally enriched in the neuron, is an intrinsically
disordered protein without a fixed structure. Physiologically, tau regulates the
dynamics of microtubules in the neuronal axon. Pathologically, the aggregation
of tau is a universally acknowledged phenomenon in Alzheimer’s disease.
There are two proposed risk factors of our interest to induce tau aggregation,
which are cupric ion (Cu2+) and lipid membranes. The presence of a high
concentration of Cu2+ in tau tangles has been verified through numerous post mortem assays. Previous studies indicated copper-dependent induction of
aggregates, suggesting the active role of copper ions. Reactive oxygen species
might be produced via Cu
2+/Cu+
redox cycling. On the other hand, lipid
membranes might template tau folding and aggregation.
Based on this background, I focus on the role of Cu2+ and lipid membrane in tau
aggregation and associated toxicity. In this thesis, I describe an investigation into
tau binding to Cu2+ in the concentration range of nanomolar and on the timescale
of milliseconds to tens of seconds by stopped flow kinetics. The binding affinity
was determined to be in the nanomolar regime. Cu2+ bound tau was also found
more prone to form toxic oligomers than tau alone via Thioflavin T assay.
In terms of the role of lipid membranes, the affinity between tau and two
physiological model lipid membrane systems is characterized. The affinity
between tau and lipid membranes is relatively high at acidic pH, suggesting that
the binding occurs in the lumen of vesicles. Tau could assemble on the diseased
lipid membrane and form a ring-like structure. The overnight incubation between
tau and lipid vesicles disrupts the integrity of membranes irreversibly.
These results may help decipher the early event of tau aggregation in the brain
and support therapeutic intervention against copper and lipid membranes as a
viable option.Open Acces
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
Probing the Interactions of Intrinsically Disordered Protein with Metal Ions and Lipid Membranes by Fluorescence Spectroscopy
Get PDFAmyloid-β (Aβ) and α-synuclein (αSyn) are intrinsically disordered proteins (IDPs) with limited knowledge of normal functions. Their properties of interacting with metal ions and lipid membranes could possess physiological significance, but they may also induce pathological effects such as aggregation and reactive oxygen species (ROS) generation, thereby leading to the development of Alzheimer’s disease (AD) and Parkinson’s disease (PD). This thesis aims to unveil the molecular mechanisms of the interactions of Aβ and αSyn with Cu2+ and neuronal membranes, thus providing new information about the physiological and pathological roles of Aβ and αSyn, as well as Cu2+ and synaptic vesicle in neuronal synapses.
An introduction of Aβ and αSyn, as well as their interactions with Cu2+ and lipid membranes is described in Chapter 1. Subsequently, in Chapter 2, the methods and materials used in this work are introduced.
The main results of this thesis are presented from Chapter 3, in which the kinetic interactions of Cu2+ with phosphorylated serine residue 8 Aβ (pS8-Aβ) and N-truncated Aβ4-16 are presented. In this Chapter, the rate constants of Cu2+ binding to pS8-Aβ and N-truncated Aβ4-16 were both determined to be ~108 M-1 s-1 , which are comparable to that of wild type (WT) Aβ16. However, the binding affinity of Cu2+ to Aβ4-16 is much tighter (~103 - 104 times) than those of pS8-Aβ and WT-Aβ16. An interaction mechanism was proposed to describe the hierarchical binding of Cu2+ to Aβ4-16.
The thesis then moves onto the study of αSyn. In Chapter 4, the production protocol of various fluorescently labelled and unlabelled αSyn samples is described first. The produced αSyn samples were then used in the work of Chapter 5 and Chapter 6 for investigating αSyn-Cu2+ interactions and αSyn-lipid interactions, respectively. In Chapter 5, the binding affinities and modes of Cu2+ to WT-αSyn and N-terminally
acetylated (NAc) αSyn are presented. It was found that WT-αSyn shows around four orders of magnitude stronger binding affinity to Cu2+ than NAc-αSyn. Nevertheless, as described in Chapter 6, WT-αSyn shows weaker binding affinity with 50 nm synapticlike small unilamellar vesicle (SUV) than NAc-αSyn. In addition, the binding conformation of WT-αSyn on SUV was found to be mixed extended, curved or antiparallel helical structures when single αSyn binds to one SUV. However, if there are multiple αSyn molecules on one SUV, they tend to adopt the curved helical structure for association.
In Chapter 7, SUV is shown to be able to bind Cu2+ as well, with a high affinity (Kd = 0.7(1) nM) which is even stronger than those of Aβ and αSyn. Such strong interaction is due to the constituent DOPS. In addition, the SUV-Cu(II) complex was found to be reduction-inert for ascorbate, but reactive for glutathione. Finally, in
Chapter 8, the interactions among αSyn, Cu2+ and lipid membranes were investigated. Based on these results, a systematic hypothesis describing how αSyn, Cu2+ and synaptic vesicle collaboratively work in neurotransmission has been proposed.
Overall, this thesis investigates how specified IDPs (Aβ and αSyn), Cu2+ and lipid membranes interact with each other from both kinetic and structural points of view. The results lead to a new hypothesis about the physiological functions of these elements, which may provide new reference points for underpinning the inner working of such an intertwined interacting network which potentially plays a significant role in neurotransmission and governs copper homeostasis in the synapse.Open Acces
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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