1,720,955 research outputs found
MAGNETIC INTERACTION OF SELF-FOCUSING CHANNELS AND FLUXES OF ELECTROMAGNETIC-RADIATION - THEIR COALESCENCE, THE ACCUMULATION OF ENERGY, AND THE EFFECT OF EXTERNAL MAGNETIC-FIELDS ON THEM
No full textA new effect has been observed in a numerical simulation of relativistic self-focusing and filamentation of light beams: a coalescence of channels. The reason for the interaction of the chemicals is identified: an attraction of currents which arise in the self-focusing channels. It is demonstrated that external magnetic fields affect the channels, causing them to bend. These effects cast new light on the phenomenon of self-focusing. They raise the possibility of combining the energy from several channels into one. A mechanism for the generation of ultrastrong quasistatic magnetic fields is identified. Corresponding force effects are possible for other mechanisms for generating drive currents: radiation pressure; thermoelectric and thermionic-emission currents in laser discharges, laser beams, and intense microwave fields. (C) 1994 American Institute of Physics
NONLINEAR EVOLUTION OF ULTRASTRONG LASER-PULSES IN A PLASMA - NEW PHENOMENA OF MAGNETIC INTERACTION BETWEEN STRONG ELECTROMAGNETIC BEAMS
No full textResults of numerical simulations and analytical description of the propagation of two-dimensional, short relativistically strong laser pulses in an underdense plasma are presented. The relativistic self-focusing and filamentation of a laser pulse are demonstrated. The influence of asymmetry of the pulse shape is studied. It is shown that the merging of self-focusing channels occurs due to attraction of the electric currents produced by fast particle motion inside the channels. It is found that external magnetic fields can bend the channels. These effects extend the range of the self-focusing phenomena because they allow the energy of several channels to accumulate in one channel. Pulses that are shorter than the plasma wave but with a transverse size larger than the wavelength of the plasma wave excite the regular wake wave whose electric field accelerates the charged particles. The specific structure of the wake plasma wave makes it possible for electromagnetic radiation to be focused by this wave
Magnetic interaction of ultrashort high-intensity laser pulses in plasmas
No full textA review of our theoretical studies and computer simulations with PIC codes of the interaction of ultrashort, high-intensity laser pulses with plasmas is presented. The mutual attraction of the currents inside the self-focused channels, arising from the pulse filamentation, makes them interact magnetically and coalesce into a single channel with strongly enhanced electromagnetic energy density. Pulses of finite length and width propagate in the shape of a 'bullet' and produce a wake consisting of magnetic dipoles correlated with an electron vortex row behind the pulse. The vortices evolve into an antisymmetric configuration which is shown to be stable when the distance between its vortices is greater than the electron skin depth
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
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
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