1,721,068 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
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
Light hydrocarbons as redox and temperature indicators in the geothermal field of El Tatio (northern Chile)
No full textEl Tatio (northern Chile), one of the largest geothermal fields of South America, is presently undergoing a new program
of geothermal exploration, after the failure of the first exploration phase in the early 1970s. The geochemical features of the
fluid discharges characterizing this system mainly consist of boiling pools and fumaroles, and represent the result of a complex
mixing process involving 3 main components: (i) hydrothermal; (ii) atmospheric; (iii) magmatic. Chemical reactions
involving light hydrocarbons equilibrate at higher temperature than those directly measured in the geothermal wells and
calculated on the basis of the composition of the inorganic gas species. This suggests that in the deeper parts of the hydrothermal
system temperatures higher than 300 C may be achieved. Such results can have a strong impact for the evaluation
of the potential resources of this geothermal system. Moreover, the chemical characteristics of the organic gas fraction
allow the assessment of the chemical–physical conditions governing the geochemical processes acting on geothermal fluids
at depth
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
Non-methane Volatile Organic Compounds (VOCs) at El Chichón volcano (Chiapas, México):Geochemical features, origin and behavior
Full text linkSe presenta un estudio de las características geoquímicas de la fracción orgánica en las fumarolas del volcán Chichón (Estado de Chiapas, México) para obtener información sobre el origen de los compuestos orgánicos volátiles exceptuando el metano (VOCs) y los procesos que rigen su comportamiento. Los VOCs en fumarolas y pozas burbujeantes consisten principalmente de alcanos (C2-C5) cuya abundancia total tiene un orden de magnitud menor que el metano, y concentraciones altas de aromáticos (benceno y tolueno) y C2-C3 alquenos (principalmente propano e iso-butano). Se encontraron también concentraciones significativas de compuestos de azufre substituidos que en su mayoría pertenecen al grupo de los heterocíclicos. Esta composición, similar a la de las emisiones gaseosas relacionadas a sistemas geotérmicos, sugiere que la producción de gases orgánicos en el volcán El Chichón es principalmente debida a procesos termogénicos. La abundancia total de VOCs es relativamente baja en comparación con la composición típica de fluidos hidrotermales, lo que podría estar relacionado a una contribución importante de fluidos de origen magmático al reservorio que alimenta las emisiones termales del cráter. Sin embargo, la ausencia de compuestos de O-substituidos parece indicar que la composición de los fluidos hidrotermales no es afectada por el aporte de especies orgánicas producidas en profundidades someras por la descomposición de material vegetal reciente, como aquél sepultado por los productos de la erupción de 1982.
doi: https://doi.org/10.22201/igeof.00167169p.2009.48.1.10
Gas Chromatographic-Mass Spectrometric Analysis of Hydrocarbons and other Neutral Organic Compounds in Volcanic Gases using SPME for Sample Preparation
Full text linkKnowledge of the chemical composition of volcanic exhalation is important in providing information on volcanic feeding systems and on the characteristics of the gaseous compounds emitted into the atmosphere. This paper reports a novel analytical method that makes use of capillary gas chromatography coupled to mass spectrometry, preceded by solid-phase micro extraction for sample enrichment. Such an approach enables considerable expansion of the number of neutral organic compounds that can be positively identified in volcanic exhalation. Data obtained from analysis of real samples are also reported
Myopic shift during control of the deviation in intermittent exotropia: a study with the Plusoptix 12R photoscreener
No full textPurpose: To assess refraction changes under binocular viewing conditions dur-ing the control of the deviation for near fixation in intermittent exotropia (XT) patients.
Methods: 20 (XT) patients aged 4 to 26 years were enrolled in the study. The four patterns of divergent strabismus were present in the study group: divergence excess, basic exodeviation, convergence insufficiency, and simulated divergence excess. All the patients exhibited random dot stereopsis. The refraction and pupillary diameter were measured by infrared video retinos-copy and pupillometry with the Plusoptix A12 photoscreener (Nuernberg, Germany) under ei-ther monocular or binocular viewing conditions at 1 meter distance. The accommodation con-vergence to accommodation (AC/A) ratio was measured in all patients with the gradient method.
Results: A myopic shift (mean 0.44, SD 0.422) was recorded under binocular viewing condi-tions during the control of the deviation. No hyperopic shift was detected turning from monocu-lar to binocular viewing conditions in any patient. No change in pupil diameter was recorded passing from monocular to binocular fixation. The mean AC/A ratio resulted 5.61. When con-sidering the sub-groups, it ranged from 8.7 in the divergence excess group, to 5.6 in the basic exodeviation group and 3.4 in the convergence insufficiency group.
Conclusions: The myopic shift occurring under binocular viewing conditions during the con-trol of the deviation at near fixation could be explained by the increased vergence demand in (XT) patients. Fusional vergence through convergence accommodation to convergence ratio ra-ther than accommodation through AC/A ratio seems to be the main compensatory mechanism for the deviation in (XT)
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