1,720,952 research outputs found
Hybrid ray-tracing/Fourier optics method to analyze multilayer diffractive optical elements
No full textThe performance (paraxial phase delay) of conventional diffractive optical elements is generally analyzed using the analytical scalar theory of diffraction, based on thin-element approximation (TEA). However, the high thickness of multilayer diffractive optical elements (MLDOEs) means that TEA yields inaccurate results. To address this, we tested a method based on ray-tracing simulations in mid-wave and long-wave infrared wave bands and for multiple f -numbers, together with the effect of MLDOE phase delay on a collimated on-axis beam with an angular spectrum method. Thus, we accurately generate optical figures of merit (point spread function along the optical axis, Strehl ratio at the "best"focal plane, and chromatic focal shift) and, by using a finite-difference timedomain method as a reference solution, demonstrate it as a valuable tool to describe and quantify the longitudinal chromatic aberration ofMLDOEs.Green Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Spaceborne Instrumentatio
The mediation of mathematical learning through the use of pedagogical tools: a sociocultural analysis
No full textA sociocultural analysis suggests that pedagogical artifacts employed in the teaching and learning of mathematics both enable and constrain learning. This paper summarises three classroom studies of mathematics learning that have utilised a sociocultural approach. Each of the studies indicates how insight can be gained into the ways in which students attempt to make sense of the mathematics they encounter
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
Cello techniques and performing practices in the nineteenth and early twentieth centuries
Get PDFThis thesis comprises a study of cello performance practices throughout the nineteenth century and into the early decades of the twentieth. It is organised in terms of the increasing complexity of the concepts which it examines, as they are to be found in printed and manuscript music, instrumental methods and larger treatises, early recordings, concert reviews and pictures. Basic posture is considered along with different ways of holding the
bow. The development of the tail-pin shows that even when it was widely used, the older posture was still referred to as a model. Some implications for tone quality and tonal
projection are considered in the light of the shape of the arms. Some connections between the cellist's posture and that recommended by etiquette books are explored. The
functionality of the left hand and arm, and the development of modem scale fingerings, show that there was a considerable period of overlap between newer and older practices, with modern scale fingerings evolving over a long period of time. Similarly, views on the function of the right wrist in bowing are shown to change gradually, moving towards a more active upper arm movement with less extreme flexibility of the wrist. Two central expressive techniques especially associated with string playing arc considered in the context of the cello, namely vibrato and portamento. These topics are examined in the light of written indications in music, recommendations in cello treatises, and the practices evidenced in early recordings. The sources for this study can be brought into an overall
framework of a constant dialogue between `theory', as expressed in verbal instructions to the learner, or general a priori reflections about the cello, and `practice', manifested in performing editions and early recordings, or in individual acts of reception. A wide divergence is noted, both between theory and practice in general, and in terms of different styles of playing observable at any one time. It is suggested that tensions between practice
and critical disapproval can be resolved in terms of Lacanian discourse. Several test cases are used in order to compare several different recordings of the same works. The question of the musical character of the cello is discussed in terms of widespread assumptions about its gendered identity. A wide range of sources suggest that this moved from a straightforwardly `masculine' identity expressed through a controlling, elevated eloquence to a less clearly defined one, incorporating the 'feminine', with a greater stress on uninhibited emotional expression. Some performance implications for this change of view are pursued with respect to specific repertoires. Broad conclusions stress the importance of the diversity of performance practices as opposed to unifying generalisations
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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