1,721,012 research outputs found
Chirale Plasmonische Nanostrukturen durch Kolloidale Oberflächenstrukturierung
Full text linkNanophotonic and chiral plasmonics are among nanotechnology’s most intriguing and interdisciplinary fields and on the leap towards commercialisation. Chiral molecules are abundant in nature, our body and can even be found in the universe. The molecular handedness plays a significant role for their functions in many biological systems. Encoding chirality into plasmonics is promising as it can manipulate electromagnetic fields and enhance the sensitivity of chiral molecule detection. Simultaneously, the fields attract scientists from diverse backgrounds, with multiple interests such as physicists studying light-matter interaction, chemists catalysing enantiomer-selective reactions and biologists studying living objects and their mechanisms. However, the current state-of-the-art fabrication of such structures is often complex and requires sophisticated infrastructure. Robust and scalable platforms are therefore needed to provide users with suitable structures to work with in their environment. This doctoral thesis further expands the tool set of colloidal lithography and colloidal templating, as they allow to fabricate plasmonic nanostructures and sensors over large-areas.
Plasmonic resonators focus electromagnetic waves into tiny volumes known as hot-spots, similarly to lenses, but beyond the diffraction limit. These regions govern plasmonic applications since they strongly enhance properties and signals from light-matter interaction. Hence, guiding molecules and particles towards to regions is a key for resilient and sensitive applications. A robust, minimalistic colloidal lithography concept was developed to specifically address these regions of high near-field enhancement on crescent-shaped and other nanoantennas. By employing a material contrast, it was possible to place molecules and nanoparticles in the hot-spot areas with an efficiency of 90%. Crescents are anisotropic and symmetric nanoantennas that also allow the achiral polarization-depended excitation of dipolar and quadrupolar resonances. However, their mirror symmetry prevents an intrinsic chiroptical response. Thus, their mirror symmetry was broken by introducing an intermediate dielectric step within the crescent. Making crescents 3D objects leads to an overlap of induced magnetic and electric dipoles, causing the physical origin of the circular dichroism and making them true chiral objects. The chiral optical activity can be tuned by adjusting the size and position of this edge, which controls the partial overlapping of the dipoles. Placing such chiral metaatoms in specific arrays provides surface lattice resonances (SLRs) with a chiral signature. A sufficient larger separation allows coupling of diffraction modes and localised surface plasmon resonances to surface lattice resonances, showing a reduced linewidth and fewer losses. Using true intrinsic chiral crescents as building blocks leads to chiral lattice modes, i.e. making them selective to the handedness of circularly polarised light at normal incidence. Chiral molecules can also transfer their chirality into localised surface plasmon resonances in achiral nanoantenna, revealing their handedness outside the UV region, where the molecular CD signal typically occurs. This was observed for the first time also in lattice modes of arrays of isotropic and otherwise achiral gold nanoparticles.Zu den faszinierendsten und interdisziplinärsten Feldern im Bereich der Nanotechnologien gehören Nanooptik und chirale Plasmonik, welche vor dem Sprung zur Kommerzialisierung stehen. Chirale Moleküle sind Grundbausteine der Natur und kommen daher im Überfluss in unserem Körper, aber auch in den Unendlichkeiten des Universums vor. Für die Funktion in biologischen Systemen spielt die molekulare Händigkeit eine entscheidende Rolle. Das Einbetten von Chiralität in plasmonische Strukturen ist vielversprechend, denn es kann lokale elektromagnetische Felder beeinflussen, und die Empfindlichkeit für die Detektion chiraler Moleküle erhöhen. Gleichzeitig zieht das Feld Forscher:Innen verschiedenster wissenschaftlicher Hintergründe mit deren ganz verschiedenen Interessen an. Physiker:Innen studieren die Licht-Materie-Interaktion, Chemiker:Innen nutzen es für die katalytische Bevorzugung eines Enantiomers und Biolog:Innen untersuchen lebende Organismen und deren komplexen Mechanismen. Heutige moderne Nanofabrikation solcher chiralen Strukturen ist häufig kompliziert und bedarf einer aufwendigen, teuren und spezialisierten Infrastruktur. Robuste und skalierbare Produktionsplattformen sind daher nötig, um es diesen Anwender:Innen zu ermöglichen Strukturen für ihre spezifischen Zwecke zu fertigen, die gleichzeitig deren Laboranforderungen gerecht werden. Diese Doktorarbeit verfolgt das Ziel, den Instrumentenkoffer von Kolloidlithographie und kolloidaler Oberflächenstrukturierung zu erweitern, da diese die großflächige Herstellung solcher plasmonischer Nanostrukturen und Sensoren ermöglichen.
Plasmonische Resonatoren fokussieren elektromagnetische Wellen in kleinste Bereiche, sogenannten Hotspots. Diese Regionen sind entscheidend für plasmonische Anwendungen, da hier Signale und andere Eigenschaften verstärkt werden die aus der Licht-Materie-Interaktion resultieren. Daher ist es für möglichst wenig anfällige und sensible Anwendungen entscheidend Moleküle und Nanopartikel in genau diese Schlüsselregionen zu bringen. Eine einfache und robuste Erweiterung der Kolloidlithografie wurde entwickelt um diese interessanten Bereiche an plasmonischen Crescents (dt.: Halbmondsicheln) und anderen plasmonischen Nanostrukturen spezifisch zu adressieren. Mit Hilfe eines erzeugten Materialkontrasts war es möglich, Moleküle und Nanopartikel mit einer Effizienz von 90% in diese Hotspot-Bereiche zu platzieren. Crescents sind anisotrope, dabei aber symmetrische Nanoantennen, die die Anregung achiraler polarisationsabhängiger Resonanzen mit dipolarem und quadrupolarem Charakter erlauben. Genau diese Spiegelsymmetrie verbietet jedoch eine intrinsisch chirale optische Antwort. Der Bruch der Spiegelsymmetrie wurde durch das Einziehen einer dielektrischen Stufe innerhalb der Crescents erreicht. Die dadurch erreichte Dreidimensionalität erzielt das partielle Überlappen von induzierten magnetischen und elektrischen Dipolen, welche die physikalische Ursache für den hervorgerufenen Zirkulardichroismus ist, und damit Crescents zu echten chiralen Objekten macht. Position und Dicke der dielektrischen Stufe kontrollieren genau dieses dipolare Überschneiden, und damit die optische Aktivität. Werden solche chiralen Metaatome gezielt in spezifische zweidimensionale Gitterkristalle platziert, erreicht man plasmonische Gitterresonanzen mit chiralen
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optischen Eigenschaften. Sind Crescents ausreichend voneinander entfernt, können Bragg-Moden und lokalisierte Partikelplasmonen miteinander koppeln, was zu plasmonischen Gitterresonanzen mit reduzierter Linienbreite und weniger Verlusten führt. Benutzt man hingegen die tatsachlich intrinsischen chiralen Crescents als Bausteine, erreicht man chirale plasmonische Gitterresonanzen. Das bedeutet, man erzielt ihre Selektivität zur Händigkeit des zirkular polarisierten Lichts bei normalem Einfallswinkel. Chirale Moleküle sind ebenfalls in der Lage ihre Chiralität in lokalisierten Partikelplasmonen achiraler Nanopartikel zu übertragen, wodurch diese die Händigkeit der Moleküle offenbaren, welche typischerweise Zirkulardichroismus im UV Bereich aufzeigen. Erstmalig wurde nachgewiesen, dass es ebenfalls möglich ist diese molekulare Chiralität in plasmonischen Gitterresonanzen von achiralen, isotropen Goldnanopartikeln zu übertragen
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
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