117,848 research outputs found
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
Aleksej Michajlovič Lipčanskij, Elena Georgievna Timofeeva, Sergej Vladislavovič Lebedev, Petr Viktorovič Kazakov, Stolica preslavnoj provincii. Istorija astrachanskogo gorodskogo obščestvennogo samoupravlenija, Astrachan’: Izd. „Astrachanskij universitet“, 2008
No full textHäfner L. Aleksej Michajlovič Lipčanskij, Elena Georgievna Timofeeva, Sergej Vladislavovič Lebedev, Petr Viktorovič Kazakov, Stolica preslavnoj provincii. Istorija astrachanskogo gorodskogo obščestvennogo samoupravlenija, Astrachan’: Izd. „Astrachanskij universitet“, 2008. Jahrbücher für Geschichte Osteuropas. 2012;60(3):459-460
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
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
Effects of silencing relaxin-3 production in nucleus incertus neurons on food intake, body weight, anxiety-like behaviour and limbic brain activity in female rats
No full textThe neuropeptide, relaxin-3 (RLN3) is part of the insulin-relaxin superfamily, is primarily expressed by neurons in the brainstem nucleus incertus (NI) and is implicated in motivated behaviours and stress responses. The present study was designed to investigate the effects of RLN3 mRNA knockdown in NI RLN3-positive neurons of female rats on body weight, food intake and anxiety-like behaviour. Female rats received a bilateral infusion into the NI of adeno-associated virus encoding microRNA against RLN3 (knockdown) or control. Three weeks after viral injections, food intake and body weight were measured every 24 h. At week 7, rats were subjected to the behavioural tests light/dark box (L/D), elevated plus maze (EPM) and large open-field (LOF) test followed. During week 8, rats were sacrificed, and intra-cardiac blood samples and brains were collected. The targeting and specificity of RLN3 knockdown in NI neurons was assessed using in situ hybridization. The c-fos mRNA expression was analysed in regions involved in stress and feeding. RLN3 mRNA expression in the NI of knockdown rats was significantly suppressed compared to control. Two-way ANOVA revealed significant difference on body weight. Bonferroni’s multiple comparison tests revealed a decrease in body weight of RLN3 knockdown rats from week 2 which persisted until week 7. Food intake was decreased in knockdown group compared to control during week 4. In addition, RLN3 knockdown rats displayed significantly higher anxiety-like behaviour in the LOF, but not in the EPM and L/D compared with virus control rats. After behavioural tests, corticosterone levels were not different between groups for all tests, however basal levels of corticosterone were significantly decreased in knockdown group compared to control. Moreover, c-fos mRNA expression significantly decreased in the paraventricular nucleus of the hypothalamus, bed nucleus of the stria terminalis, and in the lateral hypothalamus area in knockdown rats compared to control, at the basal level. Reduced RLN3 expression in NI neurons induced weight loss associated with an imbalance on food intake, elevated anxiety in environment with no escape, and disrupted the hypothalamic-pituitary adrenal axis in female rats
Letter from unknown writer to Jesse L. Boyce
No full textLetter to Jesse L. Boyce from unknown author (possibly Jack) about the investigation into the powder magazine located in the Grand Canyon. Some personal news is included in the letter such as the writer's marriage to the daughter of C.A. Taylor, former Supervisor of Cochise County
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
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