1,720,969 research outputs found
Image simulation for biological microscopy : microlith
Get PDFAuthor Posting. © Optical Society, 2014. This article is posted here by permission of Optical Society for personal use, not for redistribution. The definitive version was published in Biomedical Optics Express 5 (2014): 1822-1838, doi:10.1364/BOE.5.001822.Image simulation remains under-exploited for the most widely used biological phase microscopy methods, because of difficulties in simulating partially coherent illumination. We describe an open-source toolbox, microlith (https://code.google.com/p/microlith), which accurately predicts three-dimensional images of a thin specimen observed with any partially coherent imaging system, as well as images of coherently illuminated and self-luminous incoherent specimens. Its accuracy is demonstrated by comparing simulated and experimental bright-field and dark-field images of well-characterized amplitude and phase targets, respectively. The comparison provides new insights about the sensitivity of the dark-field microscope to mass distributions in isolated or periodic specimens at the length-scale of 10nm. Based on predictions using microlith, we propose a novel approach for detecting nanoscale structural changes in a beating axoneme using a dark-field microscope.This study was funded by National Institutes of Health grant RO1 EB00258
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
Polarized light imaging of birefringence and diattenuation at high resolution and high sensitivity
Get PDFAuthor Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of IOP Publishing for personal use, not for redistribution. The definitive version was published in Journal of Optics 15 (2013): 094007, doi:10.1088/2040-8978/15/9/094007.Polarized light microscopy provides unique opportunities for analyzing the molecular order in manmade
and natural materials, including biological structures inside living cells, tissues, and whole organisms.
20 years ago, the LC-PolScope was introduced as a modern version of the traditional polarizing
microscope enhanced by liquid crystal devices for the control of polarization, and by electronic imaging
and digital image processing for fast and comprehensive image acquisition and analysis. The LCPolScope
is commonly used for birefringence imaging, analyzing the spatial and temporal variations of
the differential phase delay in ordered and transparent materials. Here we describe an alternative use of
the LC-PolScope for imaging the polarization dependent transmittance of dichroic materials. We explain
the minor changes needed to convert the instrument between the two imaging modes, discuss the relationship
between the quantities measured with either instrument, and touch on the physical connection
between refractive index, birefringence, transmittance, diattenuation, and dichroism.This work was supported by a fellowship of the Human Frontiers Science Program awarded to SM and a
grant from the National Institute of Biomedical Imaging and Bioengineering (grant Nr. R01EB002045)
awarded to RO. MS acknowledges support from the National Institute of General Medical Sciences/NIH
(grant R01-GM101701).2014-09-1
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
Three-level filter for increased depth of focus and Bessel beam generation
Get PDFAuthor Posting. © Optical Society of America, 2012. This article is posted here by permission of Optical Society of America for personal use, not for redistribution. The definitive version was published in Optics Express 20 (2012): 27212-27221, doi:10.1364/OE.20.25.027212.A novel axially-symmetric filter for increasing focal depth and generating an approximation to a Bessel beam is proposed. It consists of an array of rings of strength –1,0 and 1. The design is based on an analytic solution, and combines high resolution in the transverse direction with good efficiency. One presented design increases the depth of focus compared with a standard lens by more than 30 times, with a very flat axial intensity distribution over this range. Effects of discretization are discussed. Various different approaches to increasing depth of focus are compared, to put the new design into perspective.Support from the Singapore-MIT Alliance for Research and Technology (SMART) Program
is acknowledged. SM acknowledges a post-doctoral fellowship from Human Frontier Science
Program (HFSP)
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