1,721,197 research outputs found
Multi-dimensional microwave sensing using graphene waveguides
Get PDFThis paper presents an electrolytically gated broadband microwave sensor
where atomically-thin graphene layers are integrated into coplanar waveguides
and coupled with microfluidic channels. The interaction between a solution
under test and the graphene surface causes material and concentration-specific
modifications of graphene's DC and AC conductivity. Moreover, wave propagation
in the waveguide is modified by the dielectric properties of materials in its
close proximity via the fringe field, resulting in a combined sensing mechanism
leading to an enhanced S-parameter response compared to metallic microwave
sensors. The possibility of further controlling the graphene conductivity via
an electrolytic gate enables a new, multi-dimensional approach merging chemical
field-effect sensing and microwave measurement methods. By controlling and
synchronizing frequency sweeps, electrochemical gating and liquid flow in the
microfluidic channel, we generate multidimensional datasets that enable a
thorough investigation of the solution under study. As proof of concept, we
functionalize the graphene surface in order to identify specific
single-stranded DNA sequences dispersed in phosphate buffered saline solution.
We achieve a limit of detection of ~1 attomole per litre for a perfect match
DNA strand and a sensitivity of ~3 dB/decade for sub-pM concentrations. These
results show that our devices represent a new and accurate metrological tool
for chemical and biological sensing
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
Conducting Polymer Devices for in vitro Electrophysiology
No full textLa bioélectronique est un domaine émergent qui vise à combiner les mondes de la biologie et de l'électronique. Les matériaux organiques présentent un ensemble de caractéristiques uniques qui les rendent candidats idéaux pour répondre aux contraintes spécifiques de ce domaine. Leur flexibilité leur donne une meilleure stabilité mécanique, tandis que leur nature de conducteurs ioniques et électroniques leur permet d’interférer parfaitement entre un tissu vivant et un dispositif électronique. En outre, ils présentent des interfaces non oxydées pour des interactions biologiques plus efficaces. Il est également possible de modifier chimiquement ces matériaux afin de les fonctionnaliser. Ces idées, ainsi que les différentes approches de fabrication des dispositifs organiques sont présentées au chapitre 1.L’électrode est le principal outil expérimental pour l’électrophysiologie in vitro. Les principes physiques du fonctionnement de l’électrode sont donc tout d’abord présentés au chapitre 2. Dans les chapitres 3 et 4, les connaissances acquises à partir de la modélisation de l’électrode sont mises en applications sur des mesures biologiques réelles. Le chapitre 3 présente des enregistrements d'activité de cellules hippocampiques de culture et le chapitre 4 de cellules pancréatiques.Le chapitre 5 introduit un autre dispositif, le transistor électrochimique organique (OECT) et présent une carte électronique de conversion qui pourrait faciliter l’usage d’OECT dans futures applications d’électrophysiologie. Le chapitre 6 clôture cette thèse en décrivant des mesures effectuées sur des astrocytes à l’aide d’OECT.Bioelectronics is an emerging field that is aiming to combine the worlds of biology and electronics. Among all the other materials, organics present a unique set of features that renders them ideal candidates for this new field. Their soft nature gives better mechanical stability, while the fact that they can conduct both electrically and ionically makes them ideal candidates to bridge the gap between electronic devices and living tissue. In addition they provide oxide free interfaces that could interact more efficiently with biology and allow chemically modification that increase biological functionality. These ideas, together with the organic devices fabrication approaches are presented in Chapter 1.Electrodes are the main experimental tool for electrophysiology and this is why Chapter 2 presents the main physics principle behind them. Chapters 3 and 4 implement the knowledge obtained from the electrode modeling to real biological measurements. Chapter 3 presents activity recordings from Hippocampal cell cultures and Chapter 4 form pancreatic cells. Chapter 5 introduces us to a different device as it presents the Organic electrochemical transistor (OECT) and presents a read out circuit board that could facilitate OECT electrophysiological recordings. Chapter 6 closes this thesis with an application of OECT on astrocyte recordings
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
Inkjet printed organic electronic devices for biomedical diagnosis
No full textDe nos jours, le domaine biomédical est en pleine croissance avec le développement de dispositifs thérapeutiques innovants, bas coût, pour le diagnostic, le traitement ou la prévention de maladies chroniques ou cardiovasculaires. Ces dernières années ont connu l’émergence des polymères semi-conducteurs, alternative intéressante aux matériaux inorganiques, présentant des propriétés uniques de conduction ionique et électronique. Tout d’abord, j’ai axé mes travaux de recherche sur le développement et l’optimisation d’une encre conductrice à base de PEDOT:PSS, parfait candidat comme matériau, pour la transduction des signaux biologiques en signaux électriques, compatible avec le process jet d’encre, pour la réalisation de dispositifs imprimés. Puis mes travaux se sont orientés vers la conception et l’étude d’électrodes imprimées sur supports papiers, tatous et textiles permettant des enregistrements long termes d’électrocardiogrammes (ECG) ou électromyogrammes (EMG), présentant des performances similaires aux électrodes commerciales, utilisant un système d’acquisition spécifique pour la mesure d’activités électriques de tissus musculaires. Puis dans un second temps, je me suis penchée sur l’impression sur support papier, de transistors organiques électrochimiques (OECTs) fonctionnalisés, afin de permettre la détection d’éléments biologiques ou chimiques comme l’alcool. Ces travaux proposent une nouvelle voie pour la conception de dispositifs innovants biomédicaux à bas couts, imprimés, permettant la personnalisation des produits pouvant être intégrés dans des dispositifs biomédicaux portables ou dans des vêtements « intelligents ».With the evolution of microelectronics industry and their direct implementation in the biomedical arena, innovative tools and technologies have come to the fore enabling more reliable and cost-effective treatment. In this thesis I focus on the integration of the conducting polymer PEDOT:PSS with printing technologies toward the realization of performant biomedical devices. In the first part, I focus on the optimization of the conducting ink formulation. Following, I emphasize on the fabrication of inkjet printed PEDOT:PSS based biopotential electrodes on a wide variety of substrates (i.e., paper, textiles, tattoo paper) for use in electrophysiological applications such as electrocardiography (ECG) and electromyography (EMG). Printed electrodes on paper and printed wearable electrodes were fabricated and investigated for long-term ECG recordings. Then, conformable printed tattoo electrodes were fabricated to detect the biceps activity during muscle contraction and the conventional wiring was replaced by a simple contact between the tattoo and a similarly ink-jet printed textile electrode.In the last part, I present the potentiality of inkjet printing method for the realization of organic electrochemical transistor (OECTs) as high performing biomedical devices. A disposable breathalyzer comprised of a printed OECT and modified with alcohol dehydrogenase was used for the direct alcohol detection in breath, enabling future integration with wearable devices for real-time health monitoring. Their compatibility with printing technologies allows the realization of low-cost and large area electronic devices, toward next-generation fully integrated smart biomedical devices
- …
