1,720,972 research outputs found
Microwave microscopy and spectroscopy techniques with applications in nanotechnology and biology
No full textUn Microscopio a Scansione di sonda a Microonde e’ stato sviluppato e applicato in vari contesti. Esso lavora attraverso l’interazione di campo vicino a microonde tra una sonda emittente e il campione in analisi. La sua applicazione principale e’ la misura delle proprieta’ elettromagnetiche su scale estremamente piccole. Modelli con circuiti a parametri concentrati e distribuiti consentono di ottenere dati quantitativi dalle misure. Tali modelli diventano piu’ complessi se si considerano ambienti diversi. Questo e’ fondamentale per analizzare campioni biologici (in vitro o in vivo). Durante questo lavoro sono state fatte sia applicazioni a campioni biologici sia analisi “in-liquido”.
Un’ulteriore potenzialita’ del microscopio a microonde e’ la spettroscopia a livello atomico/molecolare. Uno degli argomenti di questa ricerca, affrontato presso la University of Maryland, e’ stato lo sviluppo di uno strumento, che lavorasse in ambiente criogenico, per la spettroscopia a microonde di materiali superconduttori ad alta temperature. La risoluzione atomica sarebbe stata utile per investigare i fenomeni non-lineari sulla nanoscala.
Un’ulteriore tematica e’ stata la detection di Risonanze di Spin Elettronico a microonde. Il microscopio e’ stato modificato per effettuare spettroscopie, con campioni immerse in flussi di campo magnetico.
Inoltre, un’esaustiva descrizione della risoluzione del microscopio e’ essenziale. Quindi, indagini riguardo la penetrazione “in-profondita’” del campo evanescente sono qui presentate. Questa capacita’ e’ estremamente interessante per ottenere una tomografia “a corto raggio” di campioni complessi (es.: cellule). E’ stata applicata una conversione nel dominio del tempo dei dati in frequenza a microonde.
Infine, il Microscopio a Scansione di sonda a Microonde e’ stato impiegato per creare pattern riproducibili sul grafene. Questo tipo di pattern e’ stato osservato sperimentalmente, e quindi e’ stato oggetto di studi teorici e numerici. Questa parte della ricerca e’ stata sviluppata in collaborazione con gli Oak Ridge National Laboratories che hanno fornito anche i campioni
Nanoscale Investigation of Electromagnetic Properties of Cells through Near-Field Scanning Microwave Microscopy
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High Resolution Imaging of Nanoscale Structures by Near-Field Scanning Microwave Microscopy
No full textHigh resolution imaging of few-layer graphene by Near-Field Scanning Microwave Microscopy
No full textIn this work, we describe the application of an in-house system performing simultaneously Scanning Tunneling Microscopy (STM) and wide-band Near Field Scanning Microwave Microscopy (wide-band SMM) to a few-layer graphene sample. This sample is produced by mechanical exfoliation of bulk highly oriented graphite and deposited on a substrate of conductive glass. By introducing the time-domain conversion of frequency domain data, we show that it is possible to achieve nanometric resolution
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
Full electromagnetic simulation of a scanning microwave microscope for quantitative estimation of material properties
No full textAn essential step for studying and efficiently exploiting microwave fields in materials processing is the dielectric characterization of the samples to be treated. The dielectric behavior of a material determines the degree of interaction with the electromagnetic field, and then the intrinsic efficiency of the processing. From this information it is possible to design and optimize a proper microwave applicator
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
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