1,723,221 research outputs found
Highly sensitive biosensing through Silicon Photonics: Ring resonators for early detection of viral infections
Full text linkLa tesi di dottorato indaga i significativi progressi nei dispositivi basati su risonatori ad anello per applicazioni di biosensing, con un particolare focus sulle piattaforme in silicio e nitruro di silicio. La ricerca è organizzata in quattro capitoli, ciascuno dei quali esamina il potenziale e l'efficacia di questa tecnologia, fornendo così preziose intuizioni sulle sue applicazioni pratiche nel dominio del biosensing.
Il primo capitolo offre una panoramica completa sui biosensori, evidenziando il principio di funzionamento dei risonatori ad anello. Sottolinea l'importanza critica delle tecniche di funzionalizzazione che migliorano la sensibilità e la specificità di questi dispositivi, supportata da studi di caso di aziende affermate come SiPhox e Genalyte, che hanno commercializzato con successo tecnologie di biosensing basate su risonatori ad anello.
Il secondo capitolo si concentra sulla fabbricazione e caratterizzazione di risonatori ad anello sviluppati utilizzando la tecnologia Silicon-on-Insulator (SOI) presso SiPhotonIC a Copenaghen, Danimarca. Vengono esplorate quattro configurazioni distinte—ovvero anello con guide strip, anello con guide slot, anello panda e anello con giunzione a “S”—con prestazioni valutate attraverso esperimenti di bulk sensitivity misurati in termini di figure-of-merit. I risultati rivelano che il risonatore ad anello con guide slot mostra una sensibilità superiore.
Nel terzo capitolo, l'attenzione si sposta sui risonatori ad anello in nitruro di silicio fabbricati presso il Nanophotonic Technology Center (NTC), Università Politecnica di Valencia, Spagna. Questo capitolo esamina due configurazioni di risonatori ad anello ottenute con guide d'onda strip e slot, sottoposti ad esperimenti di bulk sensitivity con soluzioni di etanolo a concentrazioni crescenti e ad esperimenti di surface sensitivity utilizzando la coppia BSA-antiBSA. I risultati preliminari suggeriscono che il risonatore ad anello con guide d'onda slot è il più adatto per successive applicazioni nella rilevazione virale.
Il quarto capitolo riassume l'implementazione pratica della configurazione di risonatore più promettente per la rilevazione dei virus, in particolare del SARS-CoV-2. Viene confrontata la capacità di rilevazione della proteina spike attraverso due metodi di funzionalizzazione: in-situ e con l'uso di un microprinter. I risultati sperimentali forniscono stime del limit-of-detection, affermando il potenziale della piattaforma sviluppata nel rispondere a sfide critiche di salute pubblica. Questi risultati non solo evidenziano l'efficacia del design del risonatore ad anello nell'ottenere alta sensibilità, ma dimostrano anche la sua applicabilità nella diagnostica rapida, particolarmente vitale nel contesto delle crisi sanitarie globali.
In conclusione, la tesi fornisce una panoramica dei risonatori ad anello come potenti strumenti di biosensing su piattaforme in silicio e nitruro di silicio. Le analisi comparative tra varie configurazioni, combinate con test pratici per la rilevazione virale, confermano la versatilità e l'efficacia di questi dispositivi in applicazioni reali. Le intuizioni derivanti da questa ricerca pongono le basi per future innovazioni nella tecnologia di biosensing, portando al potenziale sviluppo di strumenti diagnostici più sensibili, specifici e rapidi. È giustificata un'ulteriore esplorazione per ottimizzare i processi di fabbricazione e le strategie di funzionalizzazione, oltre ad espandere le applicazioni oltre la rilevazione virale per comprendere un'ampia gamma di biomarcatori, migliorando significativamente l'impatto dei risonatori ad anello nel monitoraggio clinico e ambientale.The doctoral thesis investigates the significant advancements in ring resonator-based devices for biosensing applications, with a particular focus on silicon and silicon nitride platforms. The research is organized in four chapters, each examining the potential and
efficacy of this technology, thereby providing valuable insights into its practical applications within the biosensing domain.
The first chapter offers a comprehensive overview of biosensors, highlighting the working principle of ring resonators. It emphasizes the critical importance of functionalization techniques that enhance the sensitivity and specificity of these devices, supported by case studies of established companies such as SiPhox and Genalyte, which have successfully commercialized ring resonator-based biosensing technologies. The second chapter focuses on the fabrication and characterization of ring resonators developed using Silicon-on-Insulator (SOI) technology at SiPhotonIC in Copenhagen,
Denmark. Four distinct configurations—namely, single ring, slotted ring, panda ring, and ring with “S” junction—are explored, with performance evaluated through bulk sensitivity experiments measured in terms of figure-of-merit. The findings reveal that the
slotted ring configuration exhibits superior sensitivity, which is crucial for future biosensing applications. In the third chapter, the focus shifts to silicon nitride ring resonators fabricated at the Nanophotonic Technology Center (NTC), Polytechnic University of Valencia, Spain. This chapter examines two configurations of ring resonators obtained with strip and slot waveguides, employing bulk sensitivity measurements with progressively concentrated ethanol solutions, alongside surface sensitivity experiments involving the BSA-antiBSA pair. Preliminary results suggest the ring resonator with slot waveguides as the well-suited for subsequent applications in viral detection. The fourth chapter summarizes the practical implementation of the most promising resonator configuration for the detection of viruses, specifically SARS-CoV-2. It compares the detection capabilities of its spike protein through two functionalization methods: in-situ and with the employment of a microprinter. The experimental results yield estimations of the limit-of-detection, affirming the potential of the developed platform in addressing critical public health challenges. These results not only highlight the efficacy of the ring resonator design in achieving high sensitivity but also demonstrate its applicability in rapid diagnostics, which is particularly vital in the context of global health crises.
In conclusion, the thesis establishes a foundational understanding of ring resonators as powerful biosensing tools on silicon and silicon nitride platforms. The comparative analyses across various configurations, combined with practical testing for viral detection, affirm the versatility and effectiveness of these devices in real-world
applications. The insights gained from this research lay the groundwork for future innovations in biosensing technology, potentially leading to the development of more sensitive, specific, and rapid diagnostic tools. Further exploration is justified to optimize
fabrication processes and functionalization strategies, as well as to expand applications beyond viral detection to encompass a broader range of biomarkers, significantly enhancing the impact of ring resonators in clinical and environmental monitoring
Existence and Concentration of Semiclassical Solutions for Dirac Equations with Critical Nonlinearities
Full text linkWe study the semiclassical ground states of the Dirac equation with critical nonlinearity in R^3. The Dirac operator is unbounded from below and above, and so the associate energy functional is strongly indefinite. We develop
an argument to establish the existence of least energy solutions for small parameters. We also describe the concentration phenomena of the solutions as the parameter goes to zero
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
The role of social support network in e-health services for elderly persons
Full text linkRegardless of the abundant literature on the relationship between social support network and health outcomes of the elderly, there are nearly no studies examining them in the online context. In this paper, we explore the role of social support network in e-health services in the context of a European project, whose aim is to develop a multimedia platform providing social e-services for elderly persons and their social entourage. We collect data in three European countries to examine the relationship among the social network, social support, e-service quality, satisfaction, perceived quality of life and health-promotion behavior. This study contributes to the extension of IS service quality research to the context of social networks, and offers IS practitioners some insights to provide better e-health services
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
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