1,721,134 research outputs found
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
Biomedical ultrasonics, cavitation, and sonoporation
Get PDFThis thesis treats biomedical ultrasonics, cavitation and sonoporation. Focussed ultrasound surgery can heat tissue to a temperature that causes protein denaturation and coagulative necrosis. For high-resolution focused ultrasound microsurgery, high working frequencies are necessary. We manufactured a highfrequency, high-intensity focussed ultrasound transducer, using lithium niobate as the active element. The transducer was capable of creating 2.5×3.4 (mm)2 lesions without affecting surrounding tissue. Such disruptive effects of ultrasound also have applications outside medicine. Since cyanobacteria contain gas vesicles, we hypothesised that these can be disrupted with the aid of ultrasound. During 1-hour sonication in the clinical diagnostic range, we forced blue-green algae to sink, thus promoting natural decay. In medical diagnostics, ultrasound contrast agents are added to the blood stream to differentiate between blood and other tissue types. We injected such lipid-shelled microbubbles into a synthetic capillary and sonicated using continuous ultrasound. The microbubbles formed clusters at a quarter wavelength apart owing to radiation forces. We observed cluster coalescence and translation towards the capillary wall. To study acoustic cavitation, we designed and built a scientific instrument combining a pulsed laser and a high-intensity focussed ultrasound transducer, capable of nucleating at precise locations. The cavitation dynamics were recorded using highspeed cameras. At high acoustic intensities, interacting cavitation clouds were formed. Microbubbles under sonication have been observed to create transient pores in adjacent cell membranes. This so called sonoporation has been associated with highly non-linear bubble phenomena. We observed lipid-shelled microbubbles near cancer cells under quasi-continuous low-amplitude sonication. Typically within a second of sonication, microbubbles were seen to enter the cells and dissolve. This new explanation of sonoporation was verified using high-speed photography and confocal fluorescence microscopy. If drug and genes can be successfully coupled to acoustically active vehicles, sonoporation might revolutionise non-invasive therapy as we know it
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
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
On CEUS and sonoporation
No full textNational audienceUltrasonic imaging is becoming the most popular medical imaging modality, owing to the low price per examination and its safety. A B-mode ultrasound scan shows contrasted regions from transitions in acoustic impedance, i.e., transitions in tissue type, in the form of brighter pixels. However, blood is a poor scatterer of ultrasound waves at clinical diagnostic transmit frequencies, which lie between 1 and 40 MHz. For perfusion imaging, markers have been designed to enhance the contrast in B-mode imaging. These so-called ultrasound contrast agents consist of microscopically small gas bubbles encapsulated by biodegradable shells. Contrast-enhanced ultrasound (CEUS) represents a significant advancement in the evaluation of angiogenesis in digestive cancers. Particularly, for the study of focal liver lesions, CEUS has been widely used for detection and characterisation of malignancy. The unique feature of CEUS of noninvasive assessment in real-time liver perfusion throughout the vascular phases has led to a great improvement in diagnostic accuracy of ultrasound, but also in guidance and evaluation of responses to therapy. It has been proven by numerous groups, that the cellular uptake of drugs and genes is increased, when the region of interest is under sonication, and even more so when a contrast agent is present. This increased uptake has been attributed to the formation of transient porosities in the cell membrane, which are big enough for the transport of drugs into the cell. The transient permeabilisation and resealing of a cell membrane is called sonoporation. In this presentation, the physical principles of ultrasound contrast agent microbubble behaviour and their adjustments for imaging and drug delivery including sonoporation are described
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