1,720,969 research outputs found
Continuous flow dielectrophoretic sorting and Coulter counting of yeast cells for sample viability assessment
No full textCell Viability Assessment By Flow Cytometry Using Yeast As Cell Model
No full textThis paper reports the new combination of cell sorting and counting capabilities on a single device. Most state-of-the-art devices combining these technologies use optical techniques requiring complicated experimental setups and labeled samples. The use of a label-free, electrical device significantly decreases the system complexity and makes it more appropriate for use in point-of-care diagnostics. Living and dead yeast cells are separated by dielectrophoretic forces and counted using coulter counters. The combination of these two methods allows the determination of the percentage of living and dead cells for viability studies of cell samples. The device could further be used for sorting and counting of blood cells in applications such as diagnosis of insufficient cell concentrations, identification of cell deficiencies or bacterial contamination. The use of dielectrophoresis (DEP) as sorting principle allows to separate cells based on their dielectric properties in the place of size-based separation, enabling sorting of large panels of cells and separation of infected and non-infected cells of the same type.LMIS
Continuous-flow electrical lysis device with integrated control by dielectrophoretic cell sorting
Full text linkWe present a device capable of electrical cell lysis and evaluation of lysis efficiency in continuous flow using dielectrophoretic cell sorting. We use a combination of AC electrical fields and so-called liquid electrodes to avoid bubble creation at the electrode surface. The electrical field distribution is calculated in different electrode configurations by numerical simulations. Cell sorting shows high lysis efficiency, 99% of yeast cells sorted after lysis featuring dielectric properties similar to dead cells. A study of the potential device throughput is performed.LMIS
Multiple-frequency impedance measurements in continuous flow for the evaluation of electrical lysis of yeast cells
No full textAbstractThis paper reports on an electrical lysis device with integrated cell counting and evaluation of the lysis efficiency by multiplefrequency impedance measurements. Conventional techniques use chemical reagents to lyse cells, causing unwanted interference with possible intracellular content analysis downstream. Electrical lysis is quite simple to implement but optical observation of the lysis is difficult in the case of yeast cells, as lysis induces no visual difference. Counting the lysed cells is also essential for analysis downstream to provide an estimate of the analyte concentration per cell. Although cell counting can be performed by impedance measurement at one single frequency, multiple-frequency measurements allow the differentiation between living and dead cells and the evaluation of the lysis efficiency in continuous flow. The presented device could further be used for the evaluation of the lysis of other cell types, such as bacteria or mammalian cells
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
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