1,721,194 research outputs found
The non-Gaussian characteristics of Seismic S-Coda Waves on Mars in terms of Tsallis Statistics
No full textΣτην παρούσα πτυχιακή δοκιμάζεται μια προσέγγιση μη-εκτεταμένης στατιστικής μηχανικής (NESM) για τη σεισμικότητα του Άρη. Σε αυτή την έρευνα εξετάζουμε τα κύματα S-coda από τη σκοπιά της μη-εκτατικής στατιστικής μηχανικής και με σκοπό να ορίσουμε τις εντροπικές παραμέτρους q που βρέθηκαν στα κύματα coda τα οποία καταγράφονται από έναν μόνο σεισμολογικό σταθμό στον Άρη. Η μέθοδος αυτή χρησιμοποιείται για τα σεισμικά γεγονότα που περιλαμβάνονται στον κατάλογο V6 των σεισμών του Άρη που βασίζεται στην αποστολή InSight της NASA. Οι ετερογένειες στη γη (ρωγμές, ρήγματα, ανωμαλίες ταχύτητας ή/και πυκνότητας κ.λπ.) ερμηνεύουν τα σήματα coda ως διάσπαρτα σεισμικά κύματα. Χρησιμοποιούμε την προσέγγιση NESM για να εξετάσουμε τις συναρτήσεις κατανομής πιθανότητας (PDF) των προσαυξήσεων των σεισμικών κυμάτων S-coda που παράγονται από σεισμικά γεγονότα που καταγράφονται στον Άρη, λόγω της φύσης της κατανομής αυτών των σκεδαστών. Η κατανομή των κυμάτων S-Coda μελετάται για διάφορους τύπους και ποιότητες των δεδομένων των σεισμικών γεγονότων στον Άρη. Τα αποτελέσματα της παρούσας εργασίας υποδηλώνουν ότι οι προσαυξήσεις των σεισμικών κυμάτων coda αποκλίνουν από το γκαουσιανό σχήμα (την κατανομή Gauss) και η αντίστοιχη σχετική συνάρτηση πυκνότητας p(x) μπορεί να περιγραφεί επαρκώς από μια q-γκαουσιανή (q Gaussian) με εντροπικές τιμές q. Ως αποτέλεσμα η παρούσα εργασία παρέχει την απόδειξη ότι ο θεμελιώδης δυναμικός μηχανισμός της δημιουργίας των αρειανών σεισμών μπορεί να εξηγηθεί από ένα είδος μη-γραμμικής μνήμης, όπως ακριβώς συμβαίνει και με τους σεισμούς της Γης.The last decades a lot of progress has been made in studying planetary Physics based on the science of complexity and the application of generalized formalisms of statistical physics and entropy. The results of the present work suggests that the seismic S-coda waves recorded on Mars by NASA’s InSight Mission station, present increments that deviate from the Gaussian shape and their respective probability density function could be adequately described by a q-Gaussian. This observation implies that seismic S-coda wave complexity originating by multiscattering effects, can be described by Tsallis entropy terms (Tsallis, 2019, Tsallis and Brigatti, 2004). Investigation of the dynamical features of seismic waves is of fundamental importance since they could provide information on the statistical properties of the scatterers in the wave propagation path. The non-extensive statistical mechanics (NESM) seems to be a promising framework for studying complex earthquake systems that exhibit long-range interactions and memory effects. In this work, S-coda waves recorded on Mars are studied from the point of view of non- extensive statistical mechanics. Our aim is to demonstrate the applicability of non-extensive statistical mechanics to the fluctuations of S-coda amplitudes and to define the entropic q parameters obtained in the S-coda waves recorded by seismological station on Mars (Clinton et al. 2021). We defined the increment function X(t)=V(t+1) −Vt, where V(t) is the measured ground velocity. We proceed by analyzing the normalized increments X(t) constructing the probability density function PDF p(x), where x =(X−<X>)/σX, σX being the standard deviation of X(t) and <X> the observed mean value on the same data set. The observed probability density function deviates from the standard Gaussian shape due to the existence of heavy tails and can be rather described by the q-Gaussian function of the form: p(x)= A[1+B(q-1)x^2]^(-1/q-1) (1) The results of the present work suggest that the seismic S-coda waves increments deviate from the Gaussian shape and their respective probability density function p(x), could be adequately described by a q-Gaussian and thus presenting power-law tails with slope −2/ (q − 1). This observation implies that seismic S-coda wave complexity originating by multiscattering effects on Mars, can be described by Tsallis entropy, with the same way as it was discovered for Earth (Koutalonis et al., 2019)
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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