1,720,955 research outputs found
Utilisation de résonateurs plasmoniques achiraux pour l’optimisation de la détection de molécules chirales
No full textChirality is a geometric property found widely in nature, including at the molecular level. A molecule is chiral if it cannot be superimposed on its mirror image; the molecule and its mirror image are then called enantiomers. The accurate detection of chiral molecules is a major challenge in chemistry, biology, and pharmacology, as their enantiomers can possess radically different properties. Circular Dichroism (CD), while effective for characterizing chirality through the differential absorption of left and right circularly polarized light, faces a significant limitation: it requires substantial amounts of material. This thesis proposes an innovative approach to overcome this limitation. It relies on the use of achiral plasmonic nano-apertures, engraved in a gold layer, which are capable of locally generating "superchiral" light. This phenomenon significantly amplifies the interaction between light and chiral molecules. A key advantage of these structures is their intrinsic achirality, which should minimize parasitic dichroism during CD measurements. To validate this technique, a new-generation micro-spectropolarimeter was developed and characterized specifically for CD measurements using these nano-apertures. Measurements conducted with this device, combined with numerical simulations (using the Fourier Modal Method), revealed the existence of residual dichroism originating from the antennas themselves. These parasitic signals are attributed to subtle, systematic shape asymmetries, imperceptible to the naked eye. Experiments performed on allophycocyanin (APC) in contact with these nano-apertures demonstrated a significant amplification of the CD signal compared to traditional methods. This work thus opens promising perspectives for more sensitive and precise measurements, even with extremely limited quantities of chiral molecules, down to femtoliter volumes. However, it's important to note that it's not always straightforward to deconvolute the spectral response of the nano-apertures from the CD signal of the molecules of interest.La chiralité est une propriété géométrique très présente dans la nature, y compris à l'échelle moléculaire. Une molécule est chirale si elle n'est pas superposable à son image dans un miroir ; la molécule et son image sont alors des énantiomères. La détection précise des molécules chirales est un enjeu majeur en chimie, biologie et pharmacologie, car leurs énantiomères peuvent avoir des propriétés radicalement différentes. Le dichroïsme circulaire (CD), bien qu'efficace pour caractériser la chiralité via l'absorption différentielle de la lumière polarisée circulairement gauche et droite, souffre d'une contrainte majeure : il exige des quantités significatives de matière. Cette thèse propose une approche novatrice pour dépasser cette limitation. Elle repose sur l'utilisation de nano-ouvertures plasmoniques achirales, gravées dans une couche d'or, qui sont capables de générer localement une lumière « superchirale ». Ce phénomène amplifie considérablement l'interaction entre la lumière et les molécules chirales. Un avantage clé de ces structures est leur achiralité intrinsèque, qui minimiserait les dichroïsmes parasites dans la mesure du CD. Pour valider cette technique, un micro-spectropolarimètre de nouvelle génération a été développé et caractérisé spécifiquement pour des mesures de CD avec ces nano-ouvertures. Les mesures réalisées avec ce dispositif, combinées à des simulations numériques (Méthode Modale de Fourier), ont révélé l'existence de dichroïsmes résiduels provenant des antennes elles-mêmes. Ces signaux parasites sont attribués à de subtiles asymétries systématiques de forme, imperceptibles à l'œil nu. Les expériences menées sur l'allophycocyanine (APC) en contact avec ces nano-ouvertures ont démontré une amplification significative du signal de CD comparé aux méthodes traditionnelles. Ce travail ouvre ainsi des perspectives prometteuses pour des mesures plus sensibles et précises, même avec des quantités extrêmement limitées de molécules chirales, avec des volumes de l'ordre du femtolitre. Il faut cependant noter qu'il n'est pas toujours évident de déconvoluer la réponse spectrale des nano-ouvertures du CD des molécules d'intérêt
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
- …
