1,356,979 research outputs found
Gap junctions, dendrites and resonances : a recipe for tuning network dynamics
No full textGap junctions, also referred to as electrical synapses, are expressed along the entire central nervous system and are important in mediating various brain rhythms in both normal and pathological states. These connections can form between the dendritic trees of individual cells. Many dendrites express membrane channels that confer on them a form of sub-threshold resonant dynamics. To obtain insight into the modulatory role of gap junctions in tuning networks of resonant dendritic trees, we generalise the “sum-over-trips” formalism for calculating the response function of a single branching dendrite to a gap junctionally coupled network. Each cell in the network is modelled by a soma connected to an arbitrary structure of dendrites with resonant membrane. The network is treated as a single extended tree structure with dendro-dendritic gap junction coupling. We present the generalised “sum-over-trips” rules for constructing the network response function in terms of a set of coefficients defined at special branching, somatic and gap-junctional nodes. Applying this framework to a two-cell network, we construct compact closed form solutions for the network response function in the Laplace (frequency) domain and study how a preferred frequency in each soma depends on the location and strength of the gap junction
Computational convergence of the path integral for real dendritic morphologies
No full textNeurons are characterised by a morphological structure unique amongst biological cells, the core of which is the dendritic tree. The vast number of dendritic geometries, combined with heterogeneous properties of the cell membrane, continue to challenge scientists in predicting neuronal input-output relationships, even in the case of sub-threshold dendritic currents. The Green’s function obtained for a given dendritic geometry provides this functional relationship for passive or quasi-active dendrites and can be constructed by a sum-over-trips approach based on a path integral formalism. In this paper, we introduce a number of efficient algorithms for realisation of the sum-over-trips framework and investigate the convergence of these algorithms on different dendritic geometries. We demonstrate that the convergence of the trip sampling methods strongly depends on dendritic morphology as well as the biophysical properties of the cell membrane. For real morphologies, the number of trips to guarantee a small convergence error might become very large and strongly affect computational efficiency. As an alternative, we introduce a highly-efficient matrix method which can be applied to arbitrary branching structures
HACIA LA DESCRIPCIÓN METAPRAGMÁTICA DEL SIGNIFICADO LOCUCIONAL
No full textEl estudio de las locuciones -y de las unidades fraseológicas en general- sigue suscitando un gran interés, tanto desde la perspectiva teórica como desde los diversos ámbitos aplicados. Este trabajo busca ofrecer un acercamiento teórico coherente al análisis del significado locucional, enfocado este desde su naturaleza inherentemente pragmática, pero con características idiosincrásicas (Dobrovol'skij & Piirainen, 2005; Timofeeva-Timofeev, 2012). Por ello, la cuestión se plantea como una reflexión metalingüística (Verschueren, 1999; 2000) en torno al papel comunicativo de las locuciones. Tal marco general nos lleva a proponer un modelo metapragmático del significado locucional en dos niveles cuyo propósito es la sistematización de la descripción del comportamiento discursivo de las locuciones atendiendo a su complejidad semántica (cfr. Telija, 1996; Timofeeva-Timofeev, 2012). El modelo propuesto puede resultar útil en su aplicación a diversos ámbitos, tales como la traductología, la enseñanza de lenguas, la adquisición del lenguaje figurado o la lingüística clínica, entre otros
Hacia la descripción metapragmática del significado locucional
No full textIdioms constitute one of the most interesting and fascinating linguistic phenomena, the study of which continues to bring new findings from different theoretical and applied perspectives. This paper aims to provide a comprehensive approach to idiom meaning conceived as an eminently pragmatic matter with some idiosyncratic traits (Dobrovol'skij & Piirainen, 2005; Timofeeva-Timofeev, 2012). For this reason, the focus adopted is a metalinguistic reflection (Verschueren, 1999; 2000) on the communicative role of idioms. This general framework leads us to propose a two-level metapragmatic idiom meaning model, whose purpose is to systematically depict the discursive behavior of idioms according to their inherent semantic complexity (cfr. Telija, 1996; Timofeeva-Timofeev, 2012). Such an approach can prove useful in a variety of applied fields including, amongst others, translation studies, foreign language learning and teaching, figurative language acquisition and clinical linguistics.El estudio de las locuciones -y de las unidades fraseológicas en general- sigue suscitando un gran interés, tanto desde la perspectiva teórica como desde los diversos ámbitos aplicados. Este trabajo busca ofrecer un acercamiento teórico coherente al análisis del significado locucional, enfocado este desde su naturaleza inherentemente pragmática, pero con características idiosincrásicas (Dobrovol'skij & Piirainen, 2005; Timofeeva-Timofeev, 2012). Por ello, la cuestión se plantea como una reflexión metalingüística (Verschueren, 1999; 2000) en torno al papel comunicativo de las locuciones. Tal marco general nos lleva a proponer un modelo metapragmático del significado locucional en dos niveles cuyo propósito es la sistematización de la descripción del comportamiento discursivo de las locuciones atendiendo a su complejidad semántica (cfr. Telija, 1996; Timofeeva-Timofeev, 2012). El modelo propuesto puede resultar útil en su aplicación a diversos ámbitos, tales como la traductología, la enseñanza de lenguas, la adquisición del lenguaje figurado o la lingüística clínica, entre otros.This paper is part of the ongoing research projects The Development of Figurative Awareness during the Primary School Period: Humor and Phraseology (FFI2016-76047-P, AEI-FEDER/EU) and Metapragmatics of Children's Humor: Acquisition, Gender Perspective and Applications (GRE14-19, University of Alicante)
Effect of some inhibitors on the passivation of galvanized rebars embedded in concrete
No full textL’uso di barre d’acciaio zincate a caldo è uno dei metodi più comuni per prevenire il deterioramento delle strutture in calcestruzzo armato. La corrosione attiva dello zinco, che avviene subito dopo l’immersione dell’acciaio galvanizzato nel calcestruzzo, è accompagnata dallo sviluppo di idrogeno, che causa la perdita di adesione tra il rivestimento di zinco e la pasta di cemento non ancora indurita. I composti di cromo VI sono forti ossidanti naturalmente presenti nei cementi che riducono il tempo della passivazione e la quantità d’idrogeno sviluppato. La Direttiva 2003/53/ CE obbliga a mantenere il contenuto di cromo VI idrosolubile nel cemento al di sotto di 2 ppm sul peso totale a secco del cemento. Gli obiettivi di questo lavoro sono stati: trovare un sostituto per i composti di cromo VI attraverso lo studio del meccanismo di passivazione dell'acciaio zincato nel calcestruzzo in presenza di cromo VI e confrontare diversi ossidanti generici per la loro efficacia come inibitori di corrosione dello zinco. E’ stato inoltre studiato L'effetto dell’ossigeno sulla passivazione dello zinco. L'indagine è stata effettuata nel calcestruzzo e in soluzione satura di idrossido di calcio, mediante misure del potenziale di corrosione, della densità di corrente di corrosione e prove di impedenza. Per studiare gli strati di passivazione sono state utilizzate la microscopia SEM-EDX e la diffrattometria a raggi X. I risultati ottenuti indicano che la passivazione dell’acciaio zincato nel calcestruzzo in presenza di cromati avviene in più fasi con meccanismi diversi e che la presenza di ossigeno disciolto è importante per accelerare la passivazione. Tra gli ossidanti generici studiati, il nitrito sembra l’inibitore più promettente, sia nel calcestruzzo che in soluzione satura di idrossido di calcio. Gli sviluppi futuri si concentreranno sullo studio approfondito dell'effetto dei nitriti e sull'ulteriore ricerca di inibitori di corrosione a basso impatto ambientale
Phraseodidactics: phraseology for didactics
No full textIn this article it is offered a different view of the role of phraseology in the foreign language class. Considering the holistic nature of language, phraseological units are conceived as inherent elements in the verbal communication, which confirms its importance in the formation process of the communicative competence in a foreign language. With attention to the modular conceptions of the communicative competence (Canale 1983) and of the phraseological meaning (Timofeeva 2012), it is proposed conceiving the phraseology as a starting point for developing the different parts of communicative competence. As it is explained, phraseological meaning is conformed by several informational chunks articulated in two levels, the semantic and the pragmatic. The connexions between these chunks and the parts of communicative competence allow to use more effectively the phraseological contents for the foreign language learning and teaching
Timofeeva, Olga. 2022. Sociolinguistic Variation in Old English. Records of Communities of People. Advances in Historical Sociolinguistics. Amsterdam: John Benjamins. Pp. xv + 204. ISBN 9789027211347.
No full textBook review of Timofeeva, Olga. 2022. Sociolinguistic Variation in Old English. Records of Communities of People. Advances in Historical Sociolinguistics. Amsterdam: John Benjamins. Pp. xv + 204. ISBN 9789027211347
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Editorial for special issue on neurodynamics
No full text“Neurodynamics” is an interdisciplinary area of mathematics where dynamical systems theory (deterministic and stochastic) is the primary tool for elucidating the fundamental mechanisms responsible for the behaviour of neural systems (whether biological or synthetic). A meeting on this topic was held at the International Centre for Mathematical Sciences in Edinburgh from March 5–7 in 2012. In this special issue, we have invited seven of the main contributors to this event to expand on their presentations and highlight the use of mathematics in understanding the dynamics of neural systems
Variations on the Author
No full text“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
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