1,721,022 research outputs found
Curvature-driven positioning of Turing patterns in phase-separating curved membranes
No full textWe introduce a new finite difference scheme to study the dynamics of Turing patterns of a two-species activator-inhibitor system embedded on a phase-separating curved membrane, modelling for instance a lipid bilayer. We show that the underlying binary fluid can strongly affect both the dynamical and the steady state properties of the ensuing Turing patterns. Furthermore, geometry plays a key role, as a large enough local membrane curvature can both arrest the coarsening of the lipid domains and position the patterns selectively at areas of high or small local curvature. The physical phenomena we observe are due to a minimal coupling, between the diffusivity of the Turing components and the local membrane composition. While our study is theoretical in nature, it can provide a framework within which to address intracellular pattern formation in systems of interacting membrane proteins. © 2016 The Royal Society of Chemistry
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
Symmetry Breaking in Cells and Tissues
Get PDF“Symmetry Breaking in Cells and Tissues” presents a collection of seventeen reviews, opinions and original research papers contributed by theoreticians, physicists and mathematicians, as well as experimental biologists, united by a common interest in biological pattern formation and morphogenesis. The contributors discuss diverse manifestations of symmetry breaking in biology and showcase recent developments in experimental and theoretical approaches to biological morphogenesis and pattern formation on multiple scales
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
Ca²⁺/Calmodulin signalling during colony initiation in Neurospora crassa
No full textThe primary research aims of this thesis were to analyse the mechanism of
Ca²⁺/calmodulin (CaM) signalling during conidial germination and conidial
anastomosis tube (CAT)-mediated fusion in Neurospora crassa. Ca²⁺ is an ubiquitous
signalling molecule that regulates many important processes in filamentous fungi
including spore germination, hyphal growth, mechanosensing, stress responses,
circadian rhythms, and the virulence of pathogens. Transient increases in cytosolic
free calcium ([Ca²⁺]c) act as intracellular signals. As the primary intracellular Ca²⁺
receptor, calmodulin (CaM) converts these Ca²⁺ signals into responses by regulating
the activities of numerous target proteins. Ca²⁺-free medium, antagonists of L-type
Ca²⁺ channels, CaM and calcineurin were found to inhibit CAT fusion. In addition, my
results showed that CAT chemotropism is dependent on extracellular Ca²⁺.
65 genes were identified as likely components of the Ca²⁺ signalling machinery
of N. crassa based on a comparative genomic analysis of S. cerevisiae, A. fumigatus
and C. albicans. Deletion mutants of 29 of these genes were characterized in relation
to their possible roles during colony initiation and development. Four of these
mutants (Δcna-1, Δcnb-1, Δcamk-1, Δplc-2, and Δrgs-1), which were homokaryons,
exhibited strong morphological phenotypes associated with CAT fusion.
To identify the protein machinery involved in Ca²⁺/CaM signalling during colony
initiation, proteins that directly or indirectly interacted with CaM were isolated from
germlings by immunoprecipitation and analyzed by mass spectroscopy. A total of 286
putative Ca²⁺/CaM-interacting proteins were identified in this way and 30 of these
proteins contained CaM-binding motifs. This proteomics analysis provided evidence
for Ca²⁺/CaM signalling playing a role in regulating the activity of a wide range of
proteins including MAP kinases in the cell integrity pathway, Ras/Rho signalling
pathway, and microtubule and actin cytoskeletal proteins.
GFP labelled CaM localized as dynamic spots associated with the plasma
membrane and cytoplasm in both germ tubes and CATs. Significant CaM
accumulation was observed in the tips of CATs growing towards each other, around
fusion pores at sites of CAT fusion, and at developing septa in germ tubes. CaM
localization was influenced by the actin and microtubule cytoskeleton during the
colony initiation. Inhibition of F-actin polymerization with latrunculin-A suppressed
the pronounced accumulation of CaM at growing germ tube and CAT tips. The
movement of CaM associated with spindle pole bodies was prevented by treatment
with the microtubule polymerization inhibitor benomyl. The absence of myo-5
resulted in reduced CAT fusion and the lack recruitment of CaM at growing tips
indicating a role for the motor protein, myosin-5, in these processes.
Finally, by expressing the genetically encoded Ca²⁺ sensor GCaMP6s under the
control of tef-1 promoter in N. crassa, I have been able to image [Ca²⁺]c dynamics in
this fungus for the first time. Using this I have been able to detect localized [Ca²⁺]c
spikes and waves in conidia, germ tubes and CATs. However, I obtained no clear
evidence for localized [Ca²⁺]c changes being associated with CAT chemotropism or
fusion
- …
