1,720,992 research outputs found
Functional residual capacity and respiratory mechanics as indicators of aeration and collapse in experimental lung injury
No full textIncreased functional residual capacity (FRC) and compliance
are two desirable, but seldom measured, effects of
positive end-expiratory pressure (PEEP) in mechanically
ventilated patients. To assess how these variables reflect
the morphological lung perturbations during the evolution
of acute lung injury and the morphological changes
from altered PEEP, we correlated measurements of FRC
and respiratory system mechanics to the degree of lung
aeration and consolidation on computed tomography
(CT).Weused a porcine oleic acid model with FRC determinationsbysulfur
hexafluoride washin-washoutandrespiratory
system mechanics measured during an inspiratory
hold maneuver. Within the first hour, during
constant volume-controlled ventilation with PEEP 5 cm
H2O, FRC decreased by 45%15% (P0.005) and compliance
decreased by 35% 12% (P 0.005). Resistance
increased by 60% 62% (P 0.005). Only the FRC
changes correlated significantly to the decreased aeration
(R20.56;P0.01)andthe increased consolidation (R2
0.43; P 0.04) on CT. When the PEEP was changed to
either 10 or 0 cm H2O, there were larger changes in FRC
than in compliance. We conclude that, in our model, FRC
was a more sensitive indicator of PEEP-induced aeration
and recruitment of lung tissue and thatFRCmaybe a useful
adjunct to Pao2 monitoring
Oleic acid lung injury: a morphometric analysis using computed tomography
No full textBackground: The oleic acid-induced lung injury (OAI) model
is considered to represent the early phase of acute respiratory
distress syndrome (ARDS). Its inherent properties are important
for the design and the interpretation of interventional
studies. The aim of this study was to describe the evolution
of morphometric lung changes during OAI using computed
tomography (CT) analysis. Furthermore, the effect of a temporary
change in positive end-expiratory pressure (PEEP) was
evaluated.
Methods: Fifteen anaesthetized pigs were ventilated in
volume-controlled mode with a baseline PEEP of 5 cm H2O.
Helical CT scans were taken at baseline and 1 h after oleic acid
injection. The PEEP was then either increased to 10 cm H2O
(n1⁄45), decreased to 0 cm H2O (n1⁄45) or kept constant (n1⁄45)
for 30min. For the next 30min, the baseline PEEP level was
applied in all animals before the final CT scans 2 h after the
induction of OAI. Dimensional and volumetric changes were
determined from radiographical attenuation values.
Results: There was a major decrease in gas volume and an
increase in tissue volume within the first hour. A net increase
in total lung volume, with a larger transverse area but no
displacement of the diaphragm, was manifest after 2 h. A minor
increase in volume of non-aerated lung, located to the caudal
region, was observed during the second hour. The tidal volume
was redistributed to the middle and apical regions. The temporary
change in PEEP did not influence the morphological
progress of OAI.
Conclusion: Decreased gas volume and increased tissue
volume are the dominating morphometric characteristics of
oleic acid lung injury, occurring mainly within the first hour.
With these changes manifest, the course of injury is not affected
by a limited period of moderately changed PEEP during the
second hour. The net increase of total lung volume suggests a
predominance of oedema formation over airway and alveolar
collapse
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
Assessment of respiratory system mechanics by artificial neural networks: an exploratory study
No full textVariations 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
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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