1,721,006 research outputs found
On the correction of errors in some multiple particle tracking experiments
No full textA common source of error in particle tracking experiments is identified, and a theoretical model for the magnitude of the error is offered. In many cases, the error is small, but in systems where only a few particles are being tracked, the measured mean squared displacement can be up to 50% smaller than the actual value. The theoretical model predictions are confirmed using numerical simulations and experimental observations of polystyrene microspheres in water.National Institutes of Health (U.S.) (9P41EB015871-26A1)National Institutes of Health (U.S.) (R01-EX017656)National Institutes of Health (U.S.) (5R01NS051320)National Institutes of Health (U.S.) (4R44EB012415-02)National Science Foundation (U.S.). Chemical, Bioengineering, Enviromental, and Transport Systems (CBET-0939511)Singapore-MIT Alliance. BioSystems and Micromechanics (BioSyM) Inter-Disciplinary Research GroupMIT Skoltech InitiativeMassachusetts Institute of Technology. Postdoctoral Research Fellowship. Wellcome Trust (093831/Z/10/Z
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
Application of multiphoton microscopy in dermatological studies: A mini-review
No full textThis review summarizes the historical and more recent developments of multiphoton microscopy, as applied to dermatology. Multiphoton microscopy offers several advantages over competing microscopy techniques: there is an inherent axial sectioning, penetration depths that compete well with confocal microscopy on account of the use of near-infrared light, and many two-photon contrast mechanisms, such as second-harmonic generation, have no analogue in one-photon microscopy. While the penetration depths of photons into tissue are typically limited on the order of hundreds of microns, this is of less concern in dermatology, as the skin is thin and readily accessible. As a result, multiphoton microscopy in dermatology has generated a great deal of interest, much of which is summarized here. The review covers the interaction of light and tissue, as well as the various considerations that must be made when designing an instrument. The state of multiphoton microscopy in imaging skin cancer and various other diseases is also discussed, along with the investigation of aging and regeneration phenomena, and finally, the use of multiphoton microscopy to analyze the transdermal transport of drugs, cosmetics and other agents is summarized. The review concludes with a look at potential future research directions, especially those that are necessary to push these techniques into widespread clinical acceptance. Keywords: Multiphoton microscopy; skin; cancer; aging and regenerationNational Institutes of Health (U.S.) (Grant 9P41EB015871-26A1)National Institutes of Health (U.S.) (Grant R01-EX017656)National Institutes of Health (U.S.) (Grant 5R01NS051320)National Institutes of Health (U.S.) (Grant 4R44EB012415-02)National Science Foundation (U.S.) (Grant CBET-0939511
Parallel super-resolution imaging
Get PDFMassive parallelization of scanning-based super-resolution imaging allows fast imaging of large fields of view
6 Principles and applications of temporal-focusing wide-field two-photon microscopy
No full textTemporal focusing allows for rapid optically sectioned two-photon widefield microscopy. Depth sectioning is provided in a wide-field manner, without spatial focusing, by controlling the temporalwidth of femtosecond laser pulses near the focal plane. This spatial control of the temporal pulse width is achieved by diffracting the light off a grating resulting in spectral component separation and temporal broadening; these spectral components are only recombined at the focal plane to reproduce short, femtosecond pulses. Applications include (i) high speed functional imaging in the brain, (ii) fast FLIM and PLIM, (iii) cell-selective optogenetic excitation, and (iv) temporal focusing photodynamic therapy that may allow selective killing of cancer cells
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
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