1,721,056 research outputs found
Nanostructured polyelectrolyte-based system as a toolbox for metal ions detection
No full textThe capability of certain heavy metal ions to induce fluorescence decrease by a quenching mechanism suggested us to design and build a sensor potentially tunable for different ions at different concentrations. We propose a quenching-based sensor exploiting a nanostructured architecture in which fluorescent molecules (the sensing probe) are entrapped to recognize a specific analyte (heavy metal ions) through an optical transduction. The polyelectrolyte nanostructured system, named nanocapsule, improves the fluorophore-ion quenching sensitivity allowing a micromolar detection. Furthermore we couple our sensor with an electrical device in order to refine the sensing procedure: the electric field created allows a metal ions spatial gradient, necessary to detect a specific element on a single sample solution, avoiding a comparative analysis with an intensity reference value. Results obtained will show the advantages and the potentialities of our system as a smart toolbox for metal ions detectio
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
Combined effect of polishing on surface morphology and elastic properties of a commercial dental restorative composite
No full textAnnular pupil filter under shot-noise condition for linear and non linear microscopy
No full textThe imaging performances of multiphoton excitation and confocal laser scanning microscopy are herby considered: in typical experimental imaging conditions, a small finite amount of photon reaches the detector giving shot-noise fluctuations which affects the signal acquired. A significant detriment in the high frequencies transmission capability is obtained. In order to partially recover the high frequencies information lost, the insertion of a pupil plane filter in the microscope illumination light pathway on the objective lens is proposed. We demonstrate high-frequency and resolution enhancement in the case of linear and non linear fluorescence microscope approach under shot-noise condition
Nanocapsules: Coating for living cells
No full textOne of the most promising tools for future applications in science and medicine is the use of nanotechnologies. Especially self-assembly systems, e.g., polyelectrolyte (PE) capsules prepared by means of the layer-by-layer technique with tailored properties, fulfill the requirements for nano-organized systems in a satisfactory manner. The nano-organized shells are suitable as coating for living cells or artificial tissue to prevent immune response. With these shells, material can be delivered to predefined organs. In this paper, some preliminary results are presented, giving a broad overview over the possibilities to use nano-organized capsules. Based on the observations that the cells while duplicating break the capsule a mutant yeast strain (Saccharomyces cerevisiae), which express GFP-tubulin under galactose promotion, was investigated by means of confocal laser scanning microscopy. The measurements reveal an increased surface charge in the region of buds developed prior encapsulation. In order to test the used PE pair for cytotoxicity, germinating conidia of the fungi Neurospora crassa were coated. The investigation with fluorescence microscopy shows a variation in the surface charge for the growing region and the conidium poles. The capsules exhibit interesting properties as valuable tool in science and a promising candidate for application in the field of medicine
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
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