1,720,969 research outputs found
The Role Of Topology In Neuroscience
No full textThe study of higher-order structures in complex networks has become an increasingly important topic recently for applications in neuroscience, where traditional methods based on graph theory - often limited to pairwise interactions - fail to capture the full richness of neural connectivity. Topological data analysis (TDA) offers an alternative framework, providing tools to extract quantitative local descriptors which help us to understand global structural features such as loops and voids in data. Traditional spectral methods use the graph Laplacian, but recently, the Hodge Laplacian has been used for uncovering topological and spectral properties across multiple scales. In this thesis, we examine the spectral decomposition of the Hodge Laplacian using alpha-filtrations on simplicial complexes derived from a point cloud. We classify the resulting eigenvectors into harmonic, gradient and curl spaces and compare these structural features with the dynamical behaviour of the system. The work is built on the framework by Vincent P. Grande and Michael T. Schaub, where, unlike traditional eigenvalue-based clustering methods, an approach to explicitly track eigenvectors across different steps of filtration is used. This gives a better insight into the structural properties of the simplicial complexes. To represent the dynamics of the system we are interested in, we implement the Kuramoto model, a well-studied model of a network of coupled oscillators. Our results establish a connection between the Hodge spectral properties observed and the synchronization dynamics, revealing that spectral topological features have a notable correlation with the synchronization behaviour of the system. This study provides a framework for comparing spectral topology with nonlinear dynamics of a network.Mathematical SciencesMaster of Science (MS
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Integrative Omic Analyses Reveal Activated Microglial Signatures in Response to HSV1 Brain Infections
No full textViruses have been well-documented to invade and proliferate within the brain, precipitating neurodegeneration and functional impairment in affected regions. Microglia are the brain's primary immune cells essential for maintaining neuronal homeostasis and defending against pathogenic infiltration. In their homeostatic state, microglia ensure neuronal and glial integrity, facilitate blood vessel formation, and aid in debris clearance. However, microglial activation occurs in response to neuronal damage or pathogen detection. Prolonged or excessive activation can lead to a cascade of neuroinflammation characterized by sustained release of proinflammatory mediators, contributing to neurodegeneration and subsequent diseases. Therefore, understanding the regulatory mechanisms of microglia is crucial for mitigating their overactivation and preserving brain health. In this study, we employed a multiscale genetic analysis to elucidate regulatory changes in virally activated microglia. We first utilized spatial transcriptomics and spatial proteomics alongside high-resolution imaging on one Mock mouse brain and HSV-1 infected mouse brain. Analysis revealed region-specific expression of inflammatory response proteins/genes such as Ifit and Irf genes upregulated. To further classify virally activated microglia, we performed 10X Chromium single-cell multiome sequencing in microglia isolated from HSV-1-infected and Mock mice. snRNAseq identified marker genes per cluster via differential analysis, revealing microglial population heterogeneity. Within-cluster analysis pinpointed differentially expressed genes between Mock and HSV1 cells, some of which overlapped with the differentially express genes from the spatial omic analysis such as Sp100, Ifit, and Irf genes. scATACseq unveiled unique peaks between clusters, reinforcing cellular diversity and indicating differential region accessibility across Mock and HSV-1 cells. Integrating scATACseq and snRNAseq together showed differential regulon enrichment between clusters and cluster-specific regulatory landscapes. Regulons in virus-activated microglia were Sp100, Irf7, Irf1, and Klf13. Broadly, this project furthers our understanding of the regional immune system responses to HSV-1 infection of the brain. Additionally, we have shown differential regulon enrichment between mock and HSV-1 cells and across cell state clusters, providing a novel TF-gene regulatory network characterization for microglial heterogeneity and activation signatures induced by HSV-1 infection.Complex Systems and Data ScienceMaster of Science (MS
Variations on the Author
Get PDF“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
Get PDFWe 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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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