1,720,979 research outputs found
'Galileo Galilei' flight experiment on the equivalence principle with field emission electric propulsion
No full textAn experiment to test the equivalence of inertial to gravitational (passive) mass in space offers two main advantages: a signal about a factor of a thousand larger than on Earth and the possibility of exploiting the absence of weight. 'Galileo Galilei' (GG) is a small satellite mission currently under study in Italy with the financial support of ASI (Agenzia Spaziale Italiana). The mission concerns a small, low Earth satellite (similar or equal to 150 kg total mass, similar or equal to 520 km altitude) with two objectives. One is scientific, in the field of fundamental physics, and the other technological within the framework of spacecraft propulsion and drag compensation. The scientific goal is to test the equivalence principle to one part in 10(16), four orders of magnitude better than the best ground results. The technological goal is a full, comprehensive test of PEEP (field emission electric propulsion) thrusters for accurate drag compensation, a technology developed in Europe by the ESA (European Space Agency) which is likely to become an essential component of all space experiments which require measurement of small forces. The GG experiment is based on novel concepts and does not require low temperatures
TEST OF THE EQUIVALENCE PRINCIPLE IN A NON-DRAG-FREE SPACECRAFT
No full textIn a near Earth orbit the driving force of a possible violation of the equivalence principle is a factor 500 larger than it is on the ground. A passive attenuator allows one to reduce the high acceleration noise of the space structure, hence to perform the experiment in a non-dedicated, non-drag-free spacecraft. By means of piezoelectric rotating sensors, with frictionless diamagnetic bearings, it is possible to test the equivalence principle at room temperature to 3 x 10(-15), about three orders of magnitude better than achieved so far
'Galileo Galilei' on the ground (GGG)
No full textGGG is a supercritical rotor to test, on the ground, the equivalence principle to one part in 10(13) and to prepare for the space experiment
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
Systematic Numerical Study of the Propagation of Monochromatic Radiation through a Stationary Atmosphere in a Model of Plane-Parallel Layers
No full textIn this paper, the authors compare the security bounds for different quantum communication protocols with the numerically evaluated losses in the transmission channel, due to the interaction between the atmosphere and the photon, which is the information carrier. The analysis is carried out using a free-source library, which can solve the radiative transfer equation for a parallel-plane atmospher
- …
