1,721,283 research outputs found
UV Written Blazed Chirped Bragg Grating Spectrometers
No full textMonolithic integrated spectrometers are ideal for use in portable testing equipment, however current research tends to focus on high-resolution platforms at near-infrared wavelengths. This thesis investigates a dispersive spectrometer platform based on blazed chirped Bragg gratings which has high resolution, large bandwidth, and low cost. As such it is suitable for portable Raman spectroscopy and optical coherence tomography.Blazed chirped Bragg gratings diffract and focus light, with the angle of diffraction dependent on the wavelength of the input light. As such, the detected intensity distribution along a detector array can be used to measure the light spectrum. This thesis shows flexible fabrication and characterisation of these devices using small-spot direct UV writing, as well as methods of efficiently modelling their output intensity distribution.Focussing aberrations of blazed chirped Bragg gratings are investigated and an ideal chirp function is derived to eliminate such aberrations. This is experimentally verified, enabling a device which operates over the 1440 nm to 1640 nm wavelength range. The device exhibited a peak resolution of 1.8 nm at 1560 nm and a typical resolution of 2.6 nm across a 100 nm range.Scalar diffraction modelling was used to investigate the bandwidth of devices, showing 3 dB bandwidths of greater than 210 nm for devices operating at 1550 nm using a novel 45° detector mounting scheme. This mounting scheme also flattens the resolution response with wavelength, resulting in greater spectral resolution further from the design wavelength.Finally a blazed chirped Bragg grating with variable blaze angle was demonstrated to offset fabrication effects and further increase device resolution and sensitivity. To our knowledge this is the first example of Bragg gratings with varying blaze angle along their length. Devices operating at wavelengths close to 780 nm achieved measured resolutions of 0.4 nm to 0.5 nm, though it is suspected that this is limited by aberrations inside the characterisation system. Modelling shows that fully optimised devices operating at 780 nm should achieve resolutions of 0.3 nm, as well as bandwidths exceeding 100 nm.<br/
Removable prosthodontics at a glance
No full textRemovable Prosthodontics at a Glance provides a comprehensive and accessible guide to the practical elements of complete and partial denture provision. It serves as the perfect illustrated guide for learners, and a handy revision guide for subsequent undergraduate and postgraduate studies.
Following the familiar, easy to use at a Glance format, each topic is presented as a double page spread with text accompanied by clear colour diagrams and clinical photographs to support conceptual understanding. Key concepts such as patient assessment, material handling, denture design, making impressions, and much more are explained and superbly illustrated enabling the reader to visualise the intended clinical endpoint.
Removable Prosthodontics at a Glance is a valuable resource for students studying dentistry and clinical dental technology, and those preparing for further studies in Prosthodontics
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
Zinc indiffused PPLN ridge waveguides
No full textWe demonstrate zinc-indiffused PPLN ridge waveguides with insertion losses of 1.8 dB in 3.4 cm long devices with standard telecommunication fiber butt coupling. Low insertion losses are critical for enabling compact, high-efficiency 780 nm wavelength converted laser sources for space-based Rubidium atom cooling systems. Our low insertion losses are attributed to sub-nanometer waveguide sidewall surface roughness produced by ultra precision ductile mode dicing. Surface roughnesses of 0.29 nm have been measured, demonstrating an order of magnitude reduction compared to prior art. We will present our latest work on zinc-indiffused PPLN ridge waveguides and report on ultra precision ductile mode dicing for PPLN ridge waveguide fabrication
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