262,928 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
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
Development of Movement Skills in Children with the Down Syndrome on Classes in Adaptive Physical Training
No full textAnnually in Ekaterinburg and the Sverdlovsk region, 40–50 children are born each year with this genetic anomaly. The problem of development and correction of motor disorders in children with Down’s syndrome remains topical. The developed method of adaptive physical education, based on the game method of TEACCH, will help children with Down syndrome improve motor skills, emotional and volitional sphere, which in the future will contribute to successful socialization in society.Ежегодно в Екатеринбурге и Свердловской области рождаются 40–50 детей с синдромом Дауна. Актуальной остается проблема развития и коррекции нарушений двигательной сферы детей с данной генетической мутацией. Разработанная методика адаптивного физического воспитания, основанная на игровом методе TEACCH, поможет детям с синдромом Дауна улучшить двигательные навыки и эмоционально-волевую сферу, что в будущем будет способствовать их успешной социализации
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
Lithuania 1967
No full text"B-1072."; Includes table of "Administrativnoe delenie Litovskoĭ SSR." Shabad Collection.Color1:600,00
Stichotvorenie V. Krivulina‚ Čto rifmovalos'; (1990), refleksija krizisa neoficial'noj kul'tury.
No full textNel olume dedicato all'emblematico anno 1990 in Urss e ai prodromi culturali della Russia post-sovietica, si inserisce uno studio analitico di un testo di Viktor Krivulin, poeta e grande promotore della cultura non conformista sin dagli anni Settanta, che descrive la fine di una esperienza culturale indipendente nata dal rapporto dialettico e con quella ufficiale sovietica
Country community of Russia in A. I. Chupro's works
No full text© Timofeeva et al. Purpose: The relevance of the studied problem is caused by the need for deep studying of the history of Russian economic science at the end of XIX – the beginning of the 20th century. It is possible to reach a result only through research of certain representatives’ heritage. A.I. Chuprov's activity was aimed at studying a number of questions of economic and social development of Russia. The important place was given to issues of country community reforming. A.I. Chuprov belonged to a number of consecutive opponents of the agrarian reform undertaken by P.A. Stolypin. The concept of country community development presented in the works of A.I. Chuprov is explained in the paper. Methodology: The leading methods of the research are the system analysis that has allowed submitting A.I. Chuprov’s communal concept and also the dialectic method opening his logic of interrelation of economic views and public beliefs. Result: The main results of the article allow presenting A.I. Chuprov's views of agrarian reform at the beginning of the 20th century and a way of modernization of social and economic situation in a village. Materials of the article can be used during the formation of lecture courses for students studying a wide range of socio-humanistic educational programs. Applications: This research can be used for universities, teachers, and students
Interaction of HIV Reverse Transcriptase with Oligonucleotide Derivatives Containing 5’-Terminal Aromatic Polycycles
No full textProtecting Animals 36: Author Witi Ihimaera
No full textIn this very special episode of Knowing Animals I am joined by beloved New Zealand author Witi Ihimaera. Witi has written many books featuring nonhuman animals. He offers us a non-colonial lens through which to think about the human/nonhuman relationship
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