1,806 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
funkdigen
No full textA generator of functional digraphs up to isomorphism
Based on Antonio E. Porreca, Ekaterina Timofeeva, Polynomial-delay generation of functional digraphs up to isomorphism, arXiv:2302.13832, 2023, https://doi.org/10.48550/arXiv.2302.13832
usage: funkdigen.py [-h] [-c] [-t] size
Generate all functional digraphs up to isomorphism
positional arguments:
size number of vertices
options:
-h, --help show this help message and exit
-c, --connected, --component
only generate components (connected digraphs)
-t, --time measure time without printing the generated digraph
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
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
Studio sull’azione passivante prodotta dal Cr VI sull’acciaio zincato nel calcestruzzo
No full textE’ stato studiato l’effetto della presenza di Cr VI nel calcestruzzo sulla corrosione attiva dello zinco. Lo studio è stato effettuato monitorando il potenziale di libera corrosione delle barre zincate nel calcestruzzo e dello zinco in soluzione satura di Ca(OH)2. I risultati indicano che il Cr VI promuove la passivazione dello zinco e dell’acciaio zincato per il suo effetto inibitore sulla corrosione dello zinco. Più è alta la concentrazione di Cr VI, più breve è il tempo necessario per la passivazione dello zinco. La passivazione avviene immediatamente dopo l’immersione quando la concentrazione del Cr VI raggiunge 15 ppm rispetto al peso del cemento. Questa accelerazione evita una perdita di adesione delle barre dovuta allo sviluppo di idrogeno durante il primo periodo di immersione delle barre nel calcestruzzo, quando la pasta cementizia non è ancora indurita. Con concentrazioni di Cr VI 6 ppm, in calcestruzzo è stata osservata una riattivazione dell’acciaio zincato, seguita da una nuova passivazione; questo comportamento non avviene in soluzione satura di Ca(OH)2. Il massimo contenuto di Cr VI nel cemento permesso dalla direttiva europea 53/2003/EEC (2 ppm) non appare sufficiente ad accelerare la passivazione delle barre zincate
Metapragmatics of children’s humour
No full textEl número monográfico Metapragmática del humor infantil busca contribuir al desarrollo de una vía de investigación todavía poco explorada en España. Se trata del estudio de humor infantil desde la perspectiva lingüística. Las contribuciones que conforman el volumen abordan el análisis de generadores lingüísticos del humor –marcas e indicadores según la nomenclatura del grupo GRIALE (cfr. Ruiz Gurillo 2012: 78-86)– que aparecen en las narraciones escritas de niños y niñas de 8, 10 y 12 años procedentes de cinco colegios de la provincia de Alicante. Estas 448 redacciones de tema humorístico constituyen el germen del corpus CHILDHUM, actualmente en construcción al amparo de varios proyectos de investigación (https://dfelg.ua.es/griale). El humor es concebido en el marco de esta investigación como una habilidad metapragmática cuyo desarrollo a lo largo de la etapa de 8 a 12 años –correspondiente al periodo de educación primaria en el sistema educativo español– tiene su reflejo en los comportamientos humorísticos verbales de los escolares. La determinación de las pautas y las pistas lingüísticas que emplean los niños y las niñas de nuestro estudio en sus creaciones en formato escrito permite establecer patrones madurativos en relación con la competencia humorística, lo cual tiene importantes consecuencias aplicadas. La atención a las diversas variables lingüísticas, psicológicas y sociales en el análisis de la evolución metapragmática del humor durante el periodo estudiado constituye, a su vez, otro valor importante del presente trabajo colectivo.The special issue Metapragmatics of children’s humour seeks to contribute to the development of a research area which is still scarcely explored in Spain. In general terms, it is concerned with the study of children’s humour from a linguistic perspective. Contributions which constitute this volume cover the analysis of linguistic sources of humour – markers and indicators following the nomenclature provided by the GRIALE research group (crf. Ruiz Gurillo, 2012: 78-86) – which appear in the stories written by 8,10 and 12-year-olds from five schools located in the province of Alicante. These 448 humorous essays constitute the seeds of CHILDHUM corpus, which is currently under construction and supported by several research projects (https://dfelg.ua.es/griale). Humour is understood in the theoretical framework of this research as a metapragmatic ability whose development throughout the age range from 8 to 12 years – parallel to the stage of primary school in the Spanish education system – has its reflection in the humorous verbal behaviour of the schoolchildren. The determination of the criteria and linguistic clues utilized by the boys and girls of our study in their written productions permits to establish metapragmatic maturation patterns in relation to humour competence, which has some important applied outcomes. The attention to the diverse linguistic, psychological and social variables in the analysis of the metapragmatics of humour evolution during the studied period constitutes, in turn, another important value of the present collective work.Las investigaciones recogidas en este volumen colectivo se llevan a cabo al amparo de los siguientes proyectos de investigación: Metapragmática del humor infantil: adquisición, perspectiva de género y aplicaciones (GRE14-19, Universidad de Alicante. IP Larissa Timofeeva Timofeev); La formación de la conciencia figurativa en la etapa de Educación Primaria: el humor y la fraseología (FFI2016-76047-P, AEI/FEDER, UE. IP Larissa Timofeeva Timofeev); Género, humor e identidad: desarrollo, consolidación y aplicabilidad de mecanismos lingüísticos en español (FFI2015-64540-C2-1-P, MINECO/FEDER. IP Leonor Ruiz Gurillo); El discurso metalingüístico en la prensa española (1940-hoy). Análisis multidimensional y caracterización genérica (FFI2015-65917-P, MINECO/FEDER. IP Carmen Marimón Llorca); Humor de género: observatorio de la identidad de mujeres y hombres a través del humor (PROMETEO/2016/052, Generalitat Valenciana. IP Leonor Ruiz Gurillo)
Interaction of HIV Reverse Transcriptase with Oligonucleotide Derivatives Containing 5’-Terminal Aromatic Polycycles
No full textStructures of the conformational isomers and polymorph modifications of N-substituted 2,6-(E,E)-bis(ferrocenylidene)piperid-4-ones: photo- and electrochemically induced E/Z isomerization
No full textFour N-substituted 2,6-(E,E)-bis(ferrocenylidene)piperid-4-ones (NH 1, NMe 2, NEt 3, NCH2Ph 4) were prepared by aldol condensation between ferrocenecarbaldehyde and two equivalents of N-substituted piperid-4-ones with high yields. The N-protonated compounds were obtained by reaction with HBF4·Et2O acid. The molecular structures of compounds 2, 3, 2·HBF4 and 4·HBF4 were confirmed by X-ray diffraction analysis and three types of conformational isomers were elucidated. Two polymorph modifications were found for compound 2·HBF4. The electron transfer properties of the complexes were examined by electrochemical and spectroelectrochemical techniques. Complexes 1-4 undergo a reversible process of two-electron oxidation and partially reversible one-electron reduction. The photo- and electrochemically induced E/Z isomerisation of the complexes was monitored by UV-vis and 1H NMR spectroscopy
Humor markers and indicators in 8, 10 and 12-years-olds’ stories written in Spanish: A typological approach
No full textEste trabajo presenta una propuesta tipológica de marcas e indicadores humorísticos (Ruiz-Gurillo 2012, 78–86) que actúan como soportes empíricos en la investigación en torno al humor verbal infantil. Nuestra clasificación se fundamenta en el análisis de 448 narraciones humorísticas, escritas por escolares de 8, 10 y 12 años procedentes de 5 centros educativos de la provincia de Alicante (Timofeeva-Timofeev 2017). Asimismo, es la base del etiquetaje pragmático del corpus CHILDHUM, actualmente en construcción, compuesto por estas y otras narraciones procedentes de diversas partes de España. La observación en el corpus de cómo evoluciona el uso de marcas e indicadores humorísticos a lo largo de las franjas etarias examinadas revela pautas de desarrollo de la competencia humorística y la metalingüística, aportando datos empíricos nuevos que no son accesibles desde la perspectiva íntegramente psicológica.This paper presents a typology of humor markers and indicators (Ruiz-Gurillo 2012, 78–86) which acts as an empirical ‘underpinning’ for children’s verbal humor research. This typology is based on the analysis of 448 humorous stories written by schoolchildren aged 8, 10 and 12 from 5 educational centers located in the Spanish province of Alicante (Timofeeva-Timofeev 2017). Furthermore, this supports the tagging system for the corpus CHILDHUM – currently under construction – which is comprised of these and other stories written by children from different parts of Spain. The observation, within the corpus, of how the use of humor markers and indicators evolves throughout the age bands under examination, brings to light some patterns of the humor competence and the metalinguistic development. Such empirical data are relevant since they are not completely accessible from the psychological perspective.Este trabajo forma parte de la investigación llevada a cabo en el marco de los siguientes proyectos de investigación financiados por diversos organismos nacionales y autonómicos: Metapragmática del humor infantil: adquisición, perspectiva de género y aplicaciones (GRE14-19, Universidad de Alicante), La formación de la conciencia figurativa en la etapa de Educación Primaria: el humor y la fraseología (FFI2016-76047-P, AEI/FEDER, UE), El humor interaccional en español. Géneros orales, escritos y tecnológicos (PID2019-104980GB-I00, MICIU, AEI) y Humor de género: observatorio de la identidad de mujeres y hombres a través del humor (PROMETEO/2016/052, Generalitat Valenciana)
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