1,720,981 research outputs found
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
Variations on the Author
No full text“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
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
Non-Minimal Dark Matter Scenarios with -Body Simulations and Weak-Lensing Observables
No full textThis thesis investigates several particle dark matter extensions of the CDM model, motivated by an incomplete understanding of the nature of dark matter and by a few longstanding discrepancies within the concordance cosmological model, such as the ~tension or small-scale crisis. First, we investigate two simple channels for dark matter decays, so-called one-body and two-body decaying dark matter. In the next part of this work, we further study the so-called `cold-warm' dark matter, a mixture of standard, collision-less dark matter species and dark matter species possessing thermal velocities. The last studied CDM extension is a temperature-dependent interaction of dark matter and dark radiation. In all of the mentioned scenarios, we perform the fully non-linear modeling of weak-lensing signal, varying cosmological parameters, and accounting for intrinsic alignment and baryonic effects in our analysis. This process requires following the structure formation of the universe within the assumed models using -body simulations and in the next step building fast emulators, evaluating the effects of a given extended dark sector on the large-scale structure, namely on the nonlinear matter power spectrum. These emulators have been made publicly available as a Python package named {\tt DMemu}.
We derive constraints on free parameters of studied models employing weak-lensing observations from \textit{Kilo-Degree Survey} and cosmic microwave background (CMB) data from \textit{Planck} and study the implications of investigated models on the tension. We find that decaying dark matter scenarios are not detected, at least within the stage-III observations, nor can satisfactorily resolve the clustering tension. We conclude that CMB can constrain one-body decays more efficiently than weak-lensing, and obtain limits on the cold-decaying dark matter mixture and the decay rate of dark matter particles in the limit of decay lifetimes comparable to or larger than Hubble time. We also show that for the two-body decays of dark matter, weak-lensing is a more constraining probe than CMB and report the up-to-date most stringent limits on this scenario. We further showcase that for cold-warm dark matter, the upcoming weak-lensing surveys can surpass the constraints from CMB in the specific regions of the dark matter parameter space and conclude only a partial resolution of the ~tension. Finally, we perform a forecast study of all mentioned models in the context of stage-IV \textit{Euclid} survey and showcase the immense potential of this mission to detect or constrain CDM extensions.
One of the important systematic effects of weak-lensing probes is the effects of baryons. In the last part of this work, we study the effects of baryons on the large-scale structure and the distribution of gas and stars inside the dark matter halos with masses ranging from to . We utilize the cosmic shear data from \textit{Dark Energy Survey} and CMB observations from \textit{Planck}. We derive constraints on the matter power spectrum modification due to baryons and on the gas and stellar fractions inside the halos. Furthermore, we use hydrodynamical simulations to validate \textit{baryonification} model, used to describe the baryonic effects in our work and show that it can be used to connect the baryonic effects on the matter power spectrum with the gas density profiles inside galaxy groups and clusters. Finally, we assess the impact of various modeling choices, an actively discussed topic in the context of weak-lensing analysis, on our final results
Gravitační kolaps zmagnetizované hmoty
No full textThe scope of interest of this work is to study the gravitational collapse of magnetized matter. We consider homogeneous, isotropic and ideally conduct- ing star threaded by the test magnetic field. This field is chosen to be a relativistic generalization of dipole field outside the star and homogeneous field under the stellar surface. Dynamics of the collapse is described by Oppenheimer-Snyder solution so we consider the framework in which the motion of stellar matter re- mains unaffected by the magnetic field. In Schwarzschild's coordinates we review the exact solution of Maxwell's equations for electric and magnetic field inside the star and find the evolution equations for both fields outside the star that have to be treated numerically. Then we introduce Novikov coordinates and find the respective fields evolution equations. We test the equations using known exact so- lution for time-dependent magnetic dipole. Finally, we adopt chosen coordinates to become singularity-avoiding and integrate the respective differential equations numerically. 1Hlavním cílem téhle práce je studium gravitačního kolapsu zmagneti- zované hmoty. Uvažujeme homogénní, isotropnou ideálně vodivou hvězdu, kterou na počátku vystavíme magnetickému poli, které zodpovídá relativistickému zo- všeobecnění dipólového pole vně a homogénnímu poli unvitř hvězdy. Dynamika kolapsu je popsána Oppenheimerovým-Snyderovým řešením, tedy uvažujeme si- tuaci, v které není pohyb hvězdné hmoty prítomním magnetickým polem ovlyv- něný. Ve Schwarzschildových souřadnicích pak odvodíme přesné řešení Maxwello- vých rovnic pro elektrické a magneticé pole uvnitř hvězdy a nalezneme evoluční rovnice pro obě pole vně hvězdy, které pak musí být řešené numericky. Následně představíme Novikovovy souřadnice a nalezneme příslušné polní rovnice. Rovnice numericky testujeme pomocí známého přesného řešení pro časově závislý magne- tický dipól. Nakonec přispůsobíme zvolené souřadnice tak, aby počas numerického řešení nezasáhly oblast singularity a integrujeme přislušné diferenciální rovnice numericky. 1Ústav teoretické fyzikyInstitute of Theoretical PhysicsFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult
Gravitational collapse of magnetized matter
No full textThe scope of interest of this work is to study the gravitational collapse of magnetized matter. We consider homogeneous, isotropic and ideally conduct- ing star threaded by the test magnetic field. This field is chosen to be a relativistic generalization of dipole field outside the star and homogeneous field under the stellar surface. Dynamics of the collapse is described by Oppenheimer-Snyder solution so we consider the framework in which the motion of stellar matter re- mains unaffected by the magnetic field. In Schwarzschild's coordinates we review the exact solution of Maxwell's equations for electric and magnetic field inside the star and find the evolution equations for both fields outside the star that have to be treated numerically. Then we introduce Novikov coordinates and find the respective fields evolution equations. We test the equations using known exact so- lution for time-dependent magnetic dipole. Finally, we adopt chosen coordinates to become singularity-avoiding and integrate the respective differential equations numerically.
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
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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