1,721,101 research outputs found
On finite generation in magnitude (co)homology and its torsion
Full text linkThe aim of this paper is to apply the framework developed by Sam and Snowden to study structural properties of graph homologies, in the spirit of Ramos, Miyata and Proudfoot. Our main results concern the magnitude homology of graphs introduced by Hepworth and Willerton, and we prove that it is a finitely generated functor (on graphs of bounded genus). More precisely, for graphs of bounded genus, we prove that magnitude cohomology, in each homological degree, has rank which grows at most polynomially in the number of vertices, and that its torsion is bounded. As a consequence, we obtain analogous results for path homology of (undirected) graphs
On reachability categories, persistence, and commuting algebras of quivers
No full textFor a finite quiver Q, we study the reachability category ReachQ. We in-vestigate the properties of ReachQ from both a categorical and a topological viewpoint. In particular, we compare ReachQ with PathQ, the category freely generated by Q. As a first application, we study the category algebra of ReachQ, which is isomorphic to the commuting algebra of Q. As a consequence, we recover, in a categorical framework, previous results obtained by Green and Schroll; we show that the commuting algebra of Q is Morita equivalent to the incidence algebra of a poset, the reachability poset. We further show that commuting algebras are Morita equivalent if and only if the reacha-bility posets are isomorphic. As a second application, we define persistent Hochschild homology of quivers via reachability categories
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
On the Homotopy Type of Multipath Complexes
Full text linkA multipath in a directed graph is a disjoint union of paths. The multipath complex of a directed graph (Formula presented.) is the simplicial complex whose faces are the multipaths of (Formula presented.). We compute Euler characteristics, and associated generating functions, of the multipath complexes of directed graphs from certain families, including transitive tournaments and complete bipartite graphs. We show that if (Formula presented.) is a linear graph, polygon, small grid or transitive tournament, then the homotopy type of the multipath complex of (Formula presented.) is always contractible or a wedge of spheres. We introduce a new technique for decomposing directed graphs into dynamical regions, which allows us to simplify the homotopy computations
Observation of carbidic and graphitic carbon formation from CO in the 10-5 Torr range on Ru(101)
No full textGroup I mGluRs coupled to G proteins are regulated by tyrosine kinase in dopamine neurons of the rat midbrain
No full textGroup I mGluRs coupled to G proteins are
regulated by tyrosine kinase in dopamine neurons of the rat midbrain.
J Neurophysiol 85: 2490–2497, 2001. Metabotropic glutamate receptors
(mGluRs) modulate neuronal function via different transduction
mechanisms that are either dependent or independent on G-protein
function. Here we investigated, using whole cell patch-clamp recordings
in combination with fluorimetric measurements of intracellular
calcium concentration ([Ca21]i), the metabolic pathways involved in
the responses induced by group I mGluRs in dopamine neurons of the
rat midbrain. The inward current and the [Ca21]i increase caused by
the group I mGluR agonist (S)-3,5-dihydroxyphenylglycine (DHPG,
100 mM) were permanently activated and subsequently abolished in
cells loaded with the nonhydrolizable GTP-analogue GTP-g-S (600
mM). In addition, when GDP-b-S (600 mM) was dialyzed into the
cells to produce the blockade of the G proteins, the DHPG-dependent
responses were reduced. When the tissue was bathed with the phospholipase
C inhibitor 1-[6[[(17b)-3-methoxyestra-1,3,5(10)-trien-17-
yl]amino]exyl]-1H-pyrrole-2,5-dione (10 mM), the DHPG-induced
calcium transients slightly diminished but the associated inward currents
were not affected. Interestingly, a substantial depression of the
DHPG-induced inward current and transient increase of [Ca21]i was
caused by the protein tyrosine kinase inhibitors tyrphostin B52 (40
mM) and 49,5,7-trihydroxyisoflavone (genistein; 40 mM), whereas
genistein’s inactive analogue 49,5,7-trihydroxyisoflavone-7-glucoside
(40 mM) was ineffective. The blockade of the Src family of tyrosine
kinase by 4-amino-5-(4-methylphenyl)-7-(t-butyl)pyrazolo[3,4-d]-
pyrimidine (20 mM), mitogen-activated protein kinase by 29-amino-39
methoxyflavone (50 mM), and protein kinase C by staurosporine (1
mM) had no effect on the cellular responses caused by DHPG. The
mGluR5-selective antagonist 2-methyl-6-(phenylethynyl)-pyridine
(10–100 mM) did not affect the actions of DHPG. Thus our results
indicate that the responses, mainly mediated by mGluRs1 in dopamine
neurons, are activated by intracellular mechanisms coupled to G
proteins and regulated by tyrosine kinases
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