1,721,052 research outputs found
High Q-factor photonic cavities as new transducers for photothermal spectroscopy
Get PDFSpectroscopic sensors represent a significant type of device designed to study the distinct fingerprint absorption spectrum of molecules. Photothermal spectroscopy (PTS) stands out as a highly sensitive and selective method, enabling the indirect measurement of the optical absorption of specific materials. In PTS, accurate measurement of refractive index changes is crucial. Therefore, suitable transducers for measuring such changes in gaseous and liquid samples are required. While excellent results have been achieved, the system remains bulky. The refractive index sensitivity and real-time measurement capabilities of integrated photonics make them ideal for interfacing with PTS systems. Integrated photonics enable the implementation of compact devices that facilitate efficient light-matter interaction. Among these devices, high-quality factor resonators can significantly enhance their performance by allowing light to circulate within the device for extended periods. Furthermore, they can be engineered to cover a wide range of refractive indices, making them versatile for various gaseous and liquid samples. Additionally, combining photonics with on-chip components such as microfluidics opens the possibilities for fully integrated lab-on-a-chip systems, providing comprehensive solutions for sample handling and analysis. In this thesis, various types of integrated photonic resonators have been designed and numerically studied for using as new refractive index transducers in PTS. The computational work conducted for this research required access to high-performance computing infrastructure provided by CINECA in Italy and Politecnico di Bari, Italy. Commercial solver RSOFT, and flexible open-source tools like MEEP and MPB, were employed. A combination of 2D and 3D-Finite Difference Time Domain simulations, as well as Rigorous Coupled Wave Analysis (RCWA) and other solvers, were used to simulate the proposed resonant structures. The combination of a reduced thermo-optic coefficient and low two-photon absorption has established Silicon Nitride as the primary platform for the devices proposed in this thesis. Photonic cavities with high Q-factors and small modal volumes offer increased sensitivity and lower detection limits. Consequently, this study prioritized the design of photonic crystal nanobeam cavities (PhCNC) and Micro Ring Resonators (MRR). MRRs are characterized by their Free Spectral Range (FSR), while PhCNCs can be optimized to support single-mode operation, which is particularly relevant for demonstrating a Hybrid External Cavity Laser (HECL). Fano resonances are a specific interference phenomenon observed in the scattering of waves. They are characterized by a spectral shape with an asymmetric line profile. The steep profile of Fano resonances can lead to more significant signal changes when a transducer interacts with samples. To achieve Fano resonance lineshapes, a photonic crystal nanobeam was sidecoupled to a MRR. Three variations of PhCNCs were investigated. The design with angled sidewalls demonstrated high tunability of the Q-factor, favoring more asymmetric cladding configurations. In the case of elliptical nanopillar design, there was a reduction in the impact of fabrication errors on the Q-factor. The Silicon-based slotted configuration exhibited a significant enhancement in the Q-factor through sidewall engineering. Furthermore, by side-coupling a S-bent waveguide to the PhCNCs, nearly single-mode operation was achieved. Conversely, the designs of circularhole and rectangular-slot Fano resonators exhibited Fano lineshapes consistently. Furthermore, the ability to tune these asymmetric shapes was successfully demonstrated. Additionally, metasurfaces for Silicon on Si3N4 membranes operating in Mid-IR wavelength range are explored. Near-field enhancement and Fano-like features were examined. Based on the simulations conducted, the optimal and most rugged geometries that can be fabricated in a single etching process were found. The fabrication was carried out by our consortium partners at Tyndall National Institute and the Centre of Advanced Photonics & Process Analytics (CAPPA), Ireland. The fabrication was led by Simone Iadanza and Artem Vorobev. Initial characterization of the fabricated devices and some of the experiments were conducted in collaboration with the CAPPA lab, including the demonstration of the HECLbased PhCNC sensor. The fabrication of metasurfaces is an ongoing process. At TU Wien, Vienna an experimental setup for the characterization of the fabricated Photonic integrated circuits was built from scratch. The experimental measurements exhibited agreement with the trends observed in simulations. Nevertheless, certain discrepancies are noted and discussed. To enhance stability and enable the measurement of small refractive index changes, thermal stabilization control into the setup was incorporated. Furthermore, advancements in the integration of liquid handling through microfluidics are demonstrated. The collaboration with the Dipl.-Ing. Silvia Schobesberger, a member of the Cell Chip group at TU Wien, allows the realization of a reliable microfluidic cell. The implemented microfluidic cell on the refractive index transducer Si3N4 surface was tested with aqueous glucose solutions showing an almost linear response. Thus, this transducer can now be used as a refractive index detector in liquid chromatography and in flow injection analysis. On the other hand, ongoing efforts on Photo Thermal Spectroscopy concerns about the refractive index transducers presented here. Therefore, further improvements toward an integrated PTS sensor could build upon the results discussed in this thesis
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
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
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
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