1,721,143 research outputs found
Development of the polarization modulator and multi-mode receivers for the search of CMB polarization
No full textThe most ambitious challenge in Experimental Cosmology today is the accurate measurement of the polarized signal of the Cosmic Microwave Background (CMB). This paper is focused on two of the critical instrumental challenges in the polarization measurement which forthcoming experiments like LSPE/SWIPE and LiteBIRD will deal with: the receivers and the polarization modulation system. SWIPE is one of the two instruments of the Large Scale Polarization Explorer (LSPE) which aims to measure the CMB polarization at large angular scale with a goal of tensor to scalar ratio r = 0.01. The detection of this tiny signal requires a very large array of polarization-sensitive detectors coupled to an imaging optical system to obtain a wide field of view. The development and testing status of a multi-mode pixel assembly is presented. In the second part of the paper we present the status of the polarization modulator. This system offers a solution to disentangle the polarized signal of interest from these unpolarized foregrounds and a rapidly-rotating half-wave plate is the most promising scheme. The LSPE/SWIPE polarization modulator unit operates at 1.6 K and is based on magnetic levitation which can significantly reduce the friction. A large number of tests were performed on a room temperature mockup and the optimized configuration is presented. A polarization modulator similar to the LSPE/SWIPE one will be used in the LiteBIRD mission, the next generation satellite mission planned to be operative in ∼ 10 years, which will map CMB polarization 20 times deeper than Planck, with a total error of δr < 0.001. The development of the two polarization modulator units is more challenging than for SWIPE due to the spacecraft requirements and the Technology Readiness Level (TRL) required
Polarization Modulator Unit Harness Thermal Design for the Mid- and High-Frequency Telescopes of the LiteBIRD Space Mission
No full textPolarization modulator units (PMUs) represent a critical and powerful component in CMB polarization experiments to suppress the 1/f noise component and mitigate systematic uncertainties induced by detector gain drifts and beam asymmetries. The LiteBIRD mission (expected launch in the late 2020 s) will be equipped with 3 PMUs, one for each of the 3 telescopes, and aims at detecting the primordial gravitational waves with a sensitivity of δr< 0.001. Each PMU is based on a continuously rotating transmissive half-wave plate held by a superconducting magnetic bearing in the 5 K environment. To achieve and monitor the rotation a number of subsystems is needed: clamp and release system and motor coils for the rotation; optical encoder, capacitive, Hall and temperature sensors to monitor its dynamic stability. In this contribution, we present a preliminary thermal design of the harness configuration for the PMUs of the mid- and high- frequency telescopes. The design is based on both the stringent system constraint for the total thermal budget available for the PMUs (≲ 4 mW at 5 K) and on the requirements for different subsystem: coils currents (up to 10 mA), optical fibers for encoder readout, 25 MHz bias signal for temperature and levitation monitors
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
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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