1,721,068 research outputs found
Iso-acoustic focusing of cells for size-insensitive acousto-mechanical phenotyping
Get PDFMechanical phenotyping of single cells is an emerging tool for cell classification, enabling assessment of effective parameters relating to cells’ interior molecular content and structure. Here, we present iso-acoustic focusing, an equilibrium method to analyze the effective acoustic impedance of single cells in continuous flow. While flowing through a microchannel, cells migrate sideways, influenced by an acoustic field, into streams of increasing acoustic impedance, until reaching their cell-type specific point of zero acoustic contrast. We establish an experimental procedure and provide theoretical justifications and models for iso-acoustic focusing. We describe a method for providing a suitable acoustic contrast gradient in a cell-friendly medium, and use acoustic forces to maintain that gradient in the presence of destabilizing forces. Applying this method we demonstrate iso-acoustic focusing of cell lines and leukocytes, showing that acoustic properties provide phenotypic information independent of size.Swedish Research Council (Grant 2012-6708)Royal Physiographic SocietyHertz Foundatio
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
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
Thermal acoustic flow inside ultrasound resonants
No full textLAUREA MAGISTRALEIl lavoro di tesi qui presentato riguarda l’acustofluidica ed intende investigare l’interazione tra campi acustici e termici in chip microfluidici. Questa applicazione nasce dall’osservazione che inomogeneità nei fluidi sono in grado di influenzare il moto indotto dal suono in un canale micrometrico. È consolidato in letteratura l’uso di gradienti chimici per variare le proprietà termofisiche dei fluidi, così da alterarne densità e comprimibilità. Questo, a seconda delle diverse situazioni, può causare rilocazione o stabilizzazione di fluidi tramite la cosiddetta acoustic body force. Si vuole quindi osservare come questa forza agisca su un fluido sottoposto ad un gradiente di temperatura.
Il progetto è iniziato con il design e la successiva prototipazione di un supporto avente le qualità necessarie a generare e mantenere un gradiente di temperatura nella sezione trasversale di un canale. Poi la piattaforma è stata automatizzata, controllandola tramite interfaccia da PC. In seguito questa è stata testata su un dispositivo microfluidico. Il gradiente di temperatura è stato quindi caratterizzato ed il movimento del fluido è stato studiato tramite l’utilizzo di particelle micrometriche usate come traccianti. Le traiettorie 3D di quest’ultime sono state ottenute grazie al General Defocusing Particle Tracking (GDPT), in grado di fornire informazioni sulla profondità grazie ad un algoritmo di analisi d’immagini. Il tracciamento è stato effettuato in tre condizioni: con solo il gradiente di temperatura, con solo il campo acustico e con la combinazione dei due.
I risultati ottenuti dimostrano la capacità della piattaforma progettata nel generare e mantenere un gradiente di temperatura nella sezione del microcanale. Inoltre, i dati sul moto generato dal campo acustico sono in accordo con la letteratura sull’argomento. Riguardo all’interazione tra i due campi, si è osservata una velocità del fluido molto elevata, con però degli strani fenomeni sviluppatosi nella lunghezza del canale. Il progetto necessita ancora di esperimenti in condizioni più standard per poter dare risposte certe agli interrogativi riguardanti l’interazione tra campo termico e acustico.This thesis aims at investigating the interaction between thermal gradients and acoustic fields in microfluidic devices. In the research branch of acoustofluidics, which bridges together acoustics and fluid dynamics, inhomogeneity in the medium has gained great interest due to the novel physics behind and the potential in manipulating submicrometer particles. Concentration gradients of solute molecules have already been proven in previous studies to be effective means to obtain differences in fluid properties, such as density and compressibility, which induce acoustic body force and heavily affect the acoustic streaming. In this project another approach was taken, i.e. generating the inhomogeneity by thermal fields, to achieve a more stable and smooth variation in the thermophysical properties of the medium across the microchannel.
The thesis work developed mainly in two subsequent phases. Firstly, a set-up which is able to generate and maintain a temperature gradient across a channel cross-section was designed, built, and then automated via software control. Secondly, this platform was tested with a glass-silicon-glass microfluidic chip, recording the fluid motion by tracking micrometric particles via extit{General Defocusing Particle Tracking} (GDPT) technique. This experiment was done for three conditions: only with thermal field, only with acoustic field and with the two combined.
The results validate the effectiveness of the platform in generating and maintaining the thermal field and have a good agreement with literatures, although the acoustic field is undesirable due to the channel geometry flaws. The novelty of the project, i.e. the thermal-acoustic interaction, revealed itself to be quite complex. As predicted, high velocity fields were observed, associated with some unexpected flow behaviours, particularly along the length of the channel. Further measurements using a device with ideal channel geometry, together with a closer collaboration with the theoreticians who are able to explain the underlying physics, are needed to reveal the full picture of this novel phenomenon
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
