1,720,975 research outputs found
Analysis of FMRI Exams Through Unsupervised Learning and Evaluation Index
Full text linkIn the last few years, the clustering of time series has seen significant growth and has proven effective in
providing useful information in various domains of use. This growing interest in time series clustering is the
result of the effort made by the scientific community in the context of time data mining.
For these reasons, the first phase of the thesis focused on the study of the data obtained from fMRI exams
carried out in task-based and resting state mode, using and comparing different clustering algorithms: SelfOrganizing map (SOM), the Growing Neural Gas (GNG) and Neural Gas (NG) which are crisp-type
algorithms, a fuzzy algorithm, the Fuzzy C algorithm, was also used (FCM). The evaluation of the results
obtained by using clustering algorithms was carried out using the Davies Bouldin evaluation index (DBI or
DB index).
Clustering evaluation is the second topic of this thesis. To evaluate the validity of the clustering, there are
specific techniques, but none of these is already consolidated for the study of fMRI exams. Furthermore,
the evaluation of evaluation techniques is still an open research field. Eight clustering validation indexes
(CVIs) applied to fMRI data clustering will be analysed. The validation indices that have been used are
Pakhira Bandyopadhyay Maulik Index (crisp and fuzzy), Fukuyama Sugeno Index, Rezaee Lelieveldt Reider
Index, Wang Sun Jiang Index, Xie Beni Index, Davies Bouldin Index, Soft Davies Bouldin Index. Furthermore,
an evaluation of the evaluation indices will be carried out, which will take into account the sub-optimal
performance obtained by the indices, through the introduction of new metrics. Finally, a new methodology
for the evaluation of CVIs will be introduced, which will use an ANFIS model
Resting state fMRI analysis using unsupervised learning algorithms
No full textRS-fMRI data analysis for functional connectivity explorations is a challenging topic in computational
neuroimaging. Several approaches have been investigated to discover whole-brain data features.
Among these, clustering techniques based on Competitive Learning (CL) and Spectral Methods (SM)
have been shown effective in providing useful information in various contexts. We selected three
clustering algorithms and two spectral methods, i.e the clustering algorithm are Self-organising Maps
(SOM), Neural Gas (NG) and Growing Neural Gas (GNG), whereas the spectral methods are the classic
Principal Component Analysis (PCA) and the Nonlinear Robust Fuzzy Principal Component Analysis
(NRFPCA). We validated clustering with Davies–Bouldin Index (DBI) and we selected informative
principal components using Random Matrix Theory (RMT). tools. We adopted these techniques to
study the intrinsic functional properties of images coming from a shared repository of resting state
fMRI experiments (1000 Functional Connectome Project)
Cluster analysis of functional neuroimages using data reduction and competitive learning algorithms
Full text linkIn the present work we use pattern vectors derived from Statistical Parametric Map, generated from a group of artificial and in-house collected fMRI data, to conduct cluster analysis. Two clustering algorithms, self-organizing map (SOM) and growing neural gas (GNG), are selected to explore inherent properties in the brain functional data. As seen in our experimental context, SOM and GNG show comparable behavior, however GNG prevails in the management of large data sets. An exploratory, descriptive analysis is conducted on in-house collected data clustered by GNG and results are detailed in the paper
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Variations on the Author
Full text link“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
Full text linkWe 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
Full text linkWe 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
- …
