1,720,997 research outputs found
Sky Polarization Observatory Project. Calibration Procedure of the Sport radiometers
No full textTechnical Repor
Millimeter wave passive components for polarization measurements
Full text linkThe Stokes parameters of the polarized sky emission are detected by a correlation unit called Hybrid Phase Discriminator (HPD), which uses signals obtained by an Ortho-mode Transducer (OMT). In the millimeter wave range and for rather large bandwidths, heterodyne receivers are not applicable, and the correlation units have to work at the frequency of the radiometer. This contribution deals with a Ka-band prototype of a new configuration of waveguide HPD, which presents a high degree of sensitivity for the detection of linearly polarized radiation
Millimeter Wave Passive Devices for Measurements of the Polarized Sky Emission
No full textThe polarized sky emission can be detected by measuring its Stokes parameters through a correlation unit, usually called Hybrid Phase Discriminator (HPD). In the millimeter wave range and for rather large bandwidths, heterodyne receivers are not applicable, and the correlation units have to work in the frequency band of the radiometer. The SPOrt (Sky Polarization Observatory) project will investigate the polarized radiation by means four radiometers at the frequencies 22, 32, 60 and 90 GHz within a 10% bandwidth. This contribution deals with the study of a new configuration of waveguide HPD’s that will be mounted on these radiometers. The configuration presents a high degree of sensitivity for the detection of linearly polarized radiation and is suitable for those technologies that offer a high degree of accuracy. Moreover, the set up is particularly robust with respect to the mechanical uncertainties, which are more significant in the higher frequency bands
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
Helium abundance and ionization structure in the Orion nebula: radio recombination lines observations
No full textMeasurements of the Cosmic Background-Radiation Temperature at 6.3 Centimeters
No full textNew measurements of the cosmic background radiation (CBR) intensity at 4.75 GHz (6.3 cm), made as a part of a large experiment to measure the CBR spectrum between 2.5 and 90 GHz, are reported. The present result, T(CBR) = 2.70 + or - 0.07 K, agrees with, but is substantially more accurate than, that previously reported by Mandolesi et al. (1984). Careful new observations of the emission from the atmosphere and from the Galaxy are also presented and 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
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