1,720,974 research outputs found
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
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
Laskennallisista inversio-ongelmista - erityisesti tilastollinen lähestymistapa ja sen soveltaminen ilmakehän kaukokartoituksessa
Get PDFTutkielmassa tutustutaan laskennallisten inversio-ongelmien teoriaan kirjallisuuden ja tieteellisten artikkelien perusteella. Laskennallisessa inversio-ongelmassa suora malli kuvaa tuntemattoman tilan ja epäsuorasti mitatun suureen välisen yhteyden. Inversio-ongelmassa taas ratkaistaan suoran mallin määrittämä yhtälö käänteiseen suuntaan, kun olemme saaneet yhtälöstä äärellisen määrän kohinallisia mittauksia. Ratkaisuun liittyvää epävarmuutta voidaan arvioida luonnollisella tavalla käyttäen todennäköisyysteoriaa, jolloin kaikki muuttujat esitetään Lebesguen mitan suhteen absoluuttisesti jatkuvina satunnaismuuttujina. Tällöin määrittelemme inversio-ongelman ratkaisuksi tuntemattoman muuttujan posteriorijakauman määrittämisen. Tutkielmassa keskitytään erityisesti inversio-ongelman tilastolliseen ratkaisemiseen, kun suora malli tunnetaan.
Tutkielman puhtaan matematiikan aiheet johdattelevat lukijan funktionaalianalyysiin sekä mitta- ja todennäköisyysteorioihin, mitkä luovat teoreettisen viitekehyksen inversio-ongelmien esittämiseen. Käytännön sovelluksissa rajoittuminen reaalianalyysiin ja matriisilaskentaan on kuitenkin usein riittävää. Yhtenä keskeisenä esimerkkinä käsittelemmekin lineaarisia inversio-ongelmia euklidisessa avaruudessa.
Epälineaaristen inversio-ongelmien ratkaisumenetelminä esittelemme differentiaalilaskentaan perustuvan Levenbergin-Marquardtin algoritmin (LMA) ja Markovin ketju Monte Carlo (MCMC) -menetelmiä, kuten Metropolisin-Hastingsin (MH) ja adaptiivisen Metropolisin (AM) algoritmit. Näytämme tutkielmassa lisäksi, miten dimension redusointimenetelmiä, kuten pääkomponenttianalyysia (PCA), voidaan soveltaa inversio-ongelman ratkaisemisessa.
Tutkielmassa esitellään kasvihuonekaasujen kaukokartoitusta laskennallisten inversio-ongelmien sovelluksena. Sovellukseen liittyviä simulaatioita ja kehitystyötä voidaan pitää tieteellisesti uutena tutkimuksena. Tutkielmaan liittyvä soveltava osuus on tehty Ilmatieteen laitoksella, Uudet havaintomentelmät -yksikön Ilmakehän kaukokartoitus -ryhmässä, vuosina 2013–2014
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
Geodesic Tomography Problems on Riemannian Manifolds
No full textThis dissertation is concerned with integral geometric inverse problems. The geodesic ray transform is an operator that encodes the line integrals of a function along geodesics. The dissertation establishes many conditions when such information determines a function uniquely and stably. A new numerical model for computed tomography imaging is created as a part of the dissertation. The introduction of the dissertation contains an introduction to inverse problems and mathematical models associcated to computed tomography. The main focus is in definitions of integral geometry problems, survey of the related literature, and introducing the main results of the dissertation. A list of important open problems in integral geometry is given. In the first article of the dissertation, it is shown that a symmetric solenoidal tensor field can be determined uniquely from its geodesic ray transform on Cartan-Hadamard manifolds, when certain geometric decay conditions are satisfied. The studied integral transforms appear in inverse scattering theory in quantum physics and general relativity. In the second article of the dissertation, it is shown that a piecewise constant vector-valued function can be determined uniquely from its geodesic ray transform with a continuous and non-singular matrix weight on Riemannian manifolds that admit a strictly convex function and have a strictly convex boundary. These integral transforms can be used to model attenuated ray transforms and inverse problems for connections and Higgs fields. The third and fourth articles of the dissertation study the geodesic ray transform over closed geodesics on flat tori when the functions have low regularity assumptions. The fourth article studies a generalization of the geodesic ray transform when the integrals of a function are known over lower dimensional isometrically embedded flat tori. New inversion formulas, regularization strategies and stability estimates are proved in the articles. The new results have applications in different computational tomography methods.unknown accessibilityei tietoa saavutettavuudest
Fourier Analysis of Periodic Radon Transforms
No full textWe study reconstruction of an unknown function from its d-plane Radon transform on the flat torus {\mathbb {T}}^n = {\mathbb {R}}^n /{\mathbb {Z}}^n when 1 \le d \le n-1. We prove new reconstruction formulas and stability results with respect to weighted Bessel potential norms. We solve the associated Tikhonov minimization problem on H^s Sobolev spaces using the properties of the adjoint and normal operators. One of the inversion formulas implies that a compactly supported distribution on the plane with zero average is a weighted sum of its X-ray data.peerReviewe
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
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