1,720,956 research outputs found
Optomechatronics Design and Control for Confocal Laser Scanning Microscopy
No full textConfocal laser scanning microscopy (CLSM) is considered as one of the major advancements in microscopy in the last century and is widely accepted as a 3D fluorescence imaging tool for biological studies. For the emerging biological questions CLSM requires fast imaging to detect rapid biological processes and aberration-corrected imaging to localize the targeted biomolecule precisely through optical disturbances by specimen. In this thesis, optomechatronics design and control are discussed for improving this temporal and spatial resolution of CLSM to respond the needs in biological research. To improve temporal resolution of CLSM imaging, the scanning speed has to be improved. For galvanometer scanners as the most popular scanner of commercial CLSM, iterative learning control (ILC) is proposed to achieve a high speed, linear, and accurate bidirectional scanning control. Two stable inversion methods of zero phase shifts and phase fitting by input delays are used for designing stable ILCs enabling a wide control bandwidth. Experimental results verify the benefits of ILCs allowing a faster scanning over 2000 lines per second with high accuracy without a phase lag and a gain mismatch, achieving up to a 73 times smaller root mean square (RMS) error than a conventional feedback controller. Although the encoder measurements follow the reference signal by the developed ILC, actual beam trajectories can have errors at high scanning rates due to non-collocation sensing by the encoder. A transformation-based iterative learning control is proposed to improve the accuracy of fast beam scanning with the non-collocated galvanometer scanner. The proposed ILC is extended from the previous ILC design by adding a reference transformation filter, which is based on the transfer functions between the mirror and the encoder. An error analysis in theory shows that the proposed ILC can reduce the error of the actual mirror angle, especially for the image scanning applications. Experimental results with the proposed transformation based ILC show up to 7.5 times better beam accuracy as compared to the previous ILC. To improve spatial resolution in CLSM, the spherical aberrations induced by coverslip thickness mismatch have to be corrected. An automated adjustment of the coverslip correction collar is proposed to compensate for the spherical aberrations by means of motorization of the collar with a correction algorithms. An axial image model is derived to suppress noise of the measured axial image and to analyze of the influence of the spherical aberrations by the coverslip thickness mismatch. To search for the best correction collar adjustment, axial scans of the coverslip reflection are recorded, processed, and evaluated by correction quality measures such as the maximum intensity, sharpness, and entropy. The benefits of the proposed automated correction are demonstrated with various coverslips with biological specimens. The Imaging examples illustrate the improved resolution with sharp and accurate multicolor images of the confocal microscope. For the general aberration correction in the deep tissue imaging, an adaptive optics (AO) is developed for the commercial CLSM to verify its concept. The AO system consists of a piezoelectric deformable mirror and a Shack Hartmann wavefront sensor (SH-WFS), which measures the wavefront of the fluorescence from the specimen. The wavefront sensor is equipped with an adjustable pinhole for confocal wavefront sensing (CWFS) to confine the optical thickness of wavefront measurements. Using the adjustable pinhole, a referencing method of the SH-WFS and the evaluation of the AO correction quality, pinhole intensity ratio, are proposed. Experimental results with fluorescence beads on the coverslip and 40?m deep in a sphere cell cluster show that the developed AO system and proposed algorithms with adjustable pinhole can improve the measured full width at half maximum (FWHM). The proposed pinhole intensity ratio using the adjustable pinhole can also show the improvement of imaging quality by the proposed AO. For CWFS, a small pinhole is desirable for rejecting out-of-focus light while it can degrade the wavefront measurement qualities. A wavefront reconstruction technique is proposed to recover the degraded phase information by the finite size of pinhole. The aberration modification by the pinhole can be modeled as a 2D convolution of the pupil function in complex domain, i.e. phase and intensity of the beam. Based on the Fresnel approximation, the 2D deconvolution problem can be simplified to the 1D deconvolution, which also allows retrieval from multiple measurements by diversified pinhole sizes. With the verified model by experimental results, the simulation results of various pinhole sizes show that the distortion of the output pupil functions by the finite pinhole can be recovered by the proposed retrieval technique, reducing the RMS phase error up to 46 %. The proposed retrieval technique is evaluated for arbitrary aberrations generated from statistics of the wavefront measurements of a biological specimen. Simulation results show that about the wavefront errors level with 3 airy unit (AU) can be achieved by the recovery algorithm and the pupil measurement with 1.5 AU pinhole, allowing an accurate wavefront sensing with higher optical sectioning ability.Delft Center for Systems and ControlMechanical, Maritime and Materials Engineerin
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
- …
