1,721,018 research outputs found
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
Electron-spin resonance oximetry in cellular systems and in vivo
No full textIn this thesis, techniques of electron spin resonance (ESR) were developed and applied to measurement of oxygen concentrations in cellular suspensions as well as in vivo systems.ESR oximetry was used to measure extracellular and intracellular oxygen concentrations in suspensions of CHO cells. No difference was noted between the extracellular and intracellular values of cells in their baseline state. However, when cellular respiration was stimulated with an uncoupler of oxidative phosphorylation, significant oxygen gradients developed, and these gradients increased as the cellular oxygen consumption rate increased. Attempts to fit these data to standard models of oxygen diffusion and consumption were largely unsuccessful, even when oxygen diffusion barriers at the plasma membrane were invoked.A technique for measuring the concentration of extracellular oxygen using liposome-encapsulated nitroxides was developed, and it is shown that this method yields results which are similar to those obtained using other well established ESR oximetric techniques. The liposome system was used to measure extracellular oxygen in environments where free nitroxides are rapidly reduced, and it was then applied to measure intracellular and extracellular oxygen concentrations simultaneously in the same sample. The simultaneous technique was applied to suspensions of rapidly respiring myoblast cells, and significant oxygen gradients are demonstrated in unstimulated cells.In vivo oxygen concentration measurements can be performed with a low frequency (1.1 GHz) ESR spectrometer and surface probe. Liposomes containing the oxygen-sensitive nitroxide d-Cat\sb1 were injected into mouse skeletal muscle, and changes in the local oxygen tension were measured as the fraction of inspired oxygen was varied.Finally, two novel ESR oxygen probes, fusinite and lithium phthaloryanine, were characterized and then applied to the measurement of in vivo skeletal muscle oxygen tensions. Again, the fraction of inspired oxygen was varied, and changes in tissue pO\sb2 noted. The results of the three in vivo methods were compared, and issues of accuracy, calibration, and oxygen sensitivity discussed.Made available in DSpace on 2011-05-07T14:27:47Z (GMT). No. of bitstreams: 2
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Previous issue date: 1991Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T15:06:58Z
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Mapping viability and oxygen concentration in spheroids: A noninvasive approach with EPR imaging
No full textThe multicellular spheroid embodies many of the physiological and anatomical characteristics of in vivo tumors and provides an appropriate context for investigating the phenomenon of reoxygenation and the interplay of local (O\sb2) and cellular viability in the response of tumors to various therapeutic regimens. There are, however, certain limitations of the methodology currently used to measure local (O\sb2) and viability in spheroids. The goal of this thesis was to overcome these limitations by developing a single noninvasive technique, based on Electron Paramagnetic Resonance Imaging (EPRI), which would provide simultaneous measurements of the distribution of (O\sb2) and viability. The approach is based on (1) the homogeneous distribution throughout the spheroid of an aqueous nitroxide with a lineshape (linewidth) responsive to local (O\sb2); and (2) the selective exclusion from cells with intact plasma membranes (viable cells) of a contrast agent which broadens the lineshape of the nitroxide. Therefore, it is necessary to recover from the net EPR signal the narrow lineshape (or relevant spectral parameters) for each respective region in the spheroid. Two independent approaches were developed to accomplish the spectral localization--4D spectral-spatial imaging and projection based modeling (PBM). Based on the results of feasibility tests, it was decided to pursue to completion only PBM. This technique employs a highly constrained downhill simplex method to minimize \chi\sp2 for two parameter spaces, characterizing, respectively, the viability and (O\sb2). One-dimensional projections, collected at 2\sp\circC and 37\sp\circC, are required experimental output functions for step (space) 1 and step 2 minimizations, respectively. Experimental results for step 1 confirm the capability to quantitate morphology and viability. Step 2, however, was unsuccessful due most likely to toxicity of the nitroxide and (or) contrast agent at higher temperatures.As a preface to the more specific theoretical and experimental work in Chapters 3-6, Chapters 1 and 2 provide instructional discussion on projection reconstruction in conjunction with a complete software package for 2-4D image reconstruction documented in the Appendices.Made available in DSpace on 2011-05-07T12:36:25Z (GMT). No. of bitstreams: 2
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Previous issue date: 1991Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:43:14Z
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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
Identification and biophysical characterization of two intralysosomal pigments with free-radical properties and their synthetic models: Human neuromelanin and the minocycline-induced thyroid pigment
No full textMelanins are complex, incompletely understood polymeric pigments which uniquely contain a stable population of organic free radicals amenable to study by electron paramagnetic resonance (EPR, or equivalently, electron spin resonance, ESR) spectroscopy. In contrast to the usual histochemical tests, a set of EPR criteria has been established for the unambiguous identification of melanin; however, their practical application often is hampered by a lack of standardized materials and methods. A standardized EPR test for melanin therefore has been developed, tested successfully, and used to identify and characterize two intralysosomal pigments with paramagnetic properties: human neuromelanin, a natural pigment of the substantia nigra presumed to derive from the neurotransmitter dopamine (DA), and a pigment induced in human and canine thyroids by administration of the tetracycline antibiotic minocycline. Using bovine eye melanin as a control, neuromelanin is found to be an atypical melanin that is poorly modeled by synthetic DA melanin, whereas the thyroid pigment does not qualify as a melanin but is similar to a pigment formed by autooxidation of minocycline in vitro. Other results show that these two natural pigments contain bound paramagnetic metal ions in situ and that incubation in strong acid at room temperature during the purification of natural pigments is well-suited for EPR purposes in general. Using synthetic DOPA melanin as a control, several new methodological approaches involving X-band EPR also have been used in comprehensive characterizations of synthetic DA melanin and the synthetic minocycline pigment. Many of the nonparamagnetic and paramagnetic properties of synthetic melanins and related pigments have been explained by postulating that they have a partial tertiary structure in solution. Compared to DOPA melanin, DA melanin is fundamentally similar but has several differences which have been attributed mainly to its larger fraction of uncyclized subunits. By contrast, the minocycline pigment is fundamentally unique, appears to be a heterogeneous copolymer of native minocycline and its oxidation products, and has distinctive paramagnetic properties which have been accounted for by postulating the coexistence of stable subpopulations of semiquinone imines and more typical semiquinones. Finally, based on the known reactivities of melanin with O\sb2 and its reduced forms in vitro, a general hypothesis is presented for a new category of pathophysiologic phenomena involving the deposition and potential cytotoxicity of intralysosomal pigments with paramagnetic properties. This supports recent suggestions that neuromelanin has a role in the pathogenesis of Parkinson's disease and indicates that the minocycline-induced thyroid pigment may not be innocuous.Made available in DSpace on 2011-05-07T12:54:14Z (GMT). No. of bitstreams: 2
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Previous issue date: 1992Item marked as restricted to the 'UIUC Users [automated]' Group (id=2) by Howard Ding ([email protected]) on 2011-05-07T14:47:32Z
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Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
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