1,721,111 research outputs found
Inertial confinement fusion with advanced ignition schemes: Fast ignition and shock ignition
No full textEssential ingredients of inertial confinement fusion (ICF) are fuel compression to very high density and hot spot ignition. In the conventional approach to ICF both fuel compression and hot spot formation are produced by the implosion of a suitable target driven by a time-tailored pulse of laser light or X-rays. This scheme requires an implosion velocity of 350-400 km/s. In advanced ignition schemes, instead, the stages of compression and hot spot heating are separated. First, implosion at somewhat smaller velocity produces a compressed fuel assembly. The hot spot is then generated by a separate mechanism in the pre-compressed fuel. The reduced implosion velocity relaxes issues concerning hydrodynamic instabilities, laser-plasma instabilities and preheat control. In addition, it can lead to higher target energy gain (ratio of fusion energy to driver energy). Fast ignition and shock ignition are promising advanced ignition schemes. In fast ignition the hot spot is created by either relativistic electrons or multi-MeV protons or light-ions, produced by a tightly focused ultra-intense laser beam. In shock ignition, intense laser pulses drive a converging shock wave that helps creating a hot spot at the centre of the fuel. These advanced schemes are illustrated in the present chapter. Motivation, potential advantages and issues are described. Research needs and perspective are also briefly discussed
Burning plasma surprise
No full textIn a burning plasma, fusion-born α particles
are the dominant source of heating. In such
conditions, the deuterium and tritium
ion energy distribution deviates from the
expected thermal Maxwellian distribution
Efficacia e tollerabilità di nilotinib in terza linea in un paziente anziano con LMC = Efficacy and safety of nilotinib as third-line therapy in an elderly patient with CML
No full textA GPU based 3D raytracing algorithm for DUED laser fusion code
No full textThese days, graphical processing units (GPUs) deliver performance comparable to that of hundreds of CPU cores. This level of performance allows certain classes of simulations to be run in-house on a standard consumer workstation, eliminating the need for a cluster. In this paper, it is shown that medium-resolution, 2D radiation hydrodynamics simulations for laser-driven inertial confinement fusion with realistic 3D laser raytracing can now be conducted on a single consumer device. A novel raytracing module has indeed been developed for the 2D Lagrangian radiation-hydro-nuclear code DUED (Atzeni 1986 Comput. Phys. Commun. 43 107–24; Atzeni et al 2005 Comput. Phys. Commun. 169 153–9) to leverage the computational power of GPUs. By employing 3D raytracing, more realistic investigations of laser-driven plasmas become feasible, with a particular focus on perturbations resulting from non-uniform laser irradiation
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
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