1,720,990 research outputs found
Arsac G., Chevallard Y., Martinand J.-L., Tiberghien A. (Eds) (1994). La transposition didactique à l’épreuve. Grenoble, La Pensée Sauvage
No full textde Bueger-Van der Borght Cécile. Arsac G., Chevallard Y., Martinand J.-L., Tiberghien A. (Eds) (1994). La transposition didactique à l’épreuve. Grenoble, La Pensée Sauvage. In: Didaskalia, n°7, 1995. Enseignement des sciences et des techniques à l'école élémentaire. pp. 161-162
Static and dynamic components of esophageal and central venous pressure during intra-abdominal hypertension
No full textOBJECTIVE: To investigate the effects of intra-abdominal hypertension on esophageal and central venous pressure considering values obtained at end-expiration (i.e., in static conditions) and during tidal volume delivery (i.e., in dynamic conditions). DESIGN: Retrospective (pigs) and prospective, randomized, controlled (rats) trial. SETTING: Animal laboratory of a university hospital. SUBJECTS: Six female pigs and 15 Sprague Dawley male rats. INTERVENTIONS: During anesthesia and paralysis, animals' abdomens were inflated with helium. MEASUREMENTS AND MAIN RESULTS: Abdominal pressure was measured by intraperitoneal catheter. In pigs, esophageal pressure and central venous pressure were continuously measured while inflating the abdomen together with hemodynamic assessment. In rats, the abdomen was inflated after the random application of three levels of positive end-expiratory pressure. Data are shown as mean ± sd. At end-expiration, esophageal pressures were similar before and after abdominal inflation (p = .177). In contrast, the dynamic component significantly rose after intra-abdominal hypertension, from 3.2 ± 0.7 cm H2O to 10.0 ± 2.3 cm H2O (p < .001), and was correlated with peritoneal pressure (linear regression, R = .708, p < .001). Positive end-expiratory pressure significantly influenced static esophageal pressure during intra-abdominal hypertension (p = .002) but not dynamic pressures.Static central venous pressure rose with intra-abdominal hypertension from 4.1 ± 1.5 cm H2O to 6.7 ± 1.8 cm H2O (p = .043), more so the dynamic component (from 2.9 ± 0.8 cm H2O to 9.3 ± 3.1 cm H2O, p = .02). Dynamic changes of esophageal pressures correlated with dynamic changes of central venous pressure (linear regression, R = .679, p < .001). Mean values of central venous pressure significantly increased with intra-abdominal hypertension from 7.7 ± 1.5 cm H2O to 12.7 ± 2.6 cm H2O (p = .006), whereas transmural central venous pressure and intrathoracic blood volume did not change significantly. CONCLUSIONS: Dynamic changes of esophageal pressure occurred during intra-abdominal hypertension, whereas end-expiratory pressure was affected by high positive end-expiratory pressure levels. Provided that central venous pressure changes reflect esophageal pressure, central venous pressure itself cannot be relied on to guide resuscitation in patients with intra-abdominal hypertension, particularly when abdominal pressures are changing over short periods of time
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
Lactate as a marker of energy failure in critically ill patients : hypothesis
No full textLactate measurement in the critically ill has been traditionally used to stratify patients with poor outcome. However, plasma lactate levels are the result of a finely tuned interplay of factors that affect the balance between its production and its clearance. When the oxygen supply does not match its consumption, organisms such as man who are forced to produce ATP for their integrity adapt in many different ways up to the point when energy failure occurs. Lactate, being part of the adaptive response, may then be used to assess the severity of the supply/demand imbalance. In such a scenario, the time to intervention becomes relevant: early and effective treatment may allow the cell to revert to a normal state, as long as the oxygen machinery (i.e. mithocondria) is intact. Conversely, once the mithocondria are deranged, energy failure occurs even in the presence of normoxia. The lactate increase in critically ill patients may therefore be viewed as an early marker of a potentially reversible state
Non-invasive ventilation in postoperative patients: A systematic review
No full textBackground: Postoperative pulmonary complications, generally defined as any pulmonary abnormality occurring in the postoperative period, are still a significant issue in clinical practice increasing hospital length of stay, morbidity and mortality. Non-invasive ventilation (NIV), primarily applied in cardiogenic pulmonary edema, decompensated COPD and hypoxemic pulmonary failure, is nowadays also used in perioperative settings. Objective: Investigate the application and results of preventive and therapeutic NIV in postsurgical patients. Design: A systematic review. Data sources: Medical literature databases were searched for articles about "clinical trials," "randomized controlled trials" and "meta-analyses." The keywords "cardiac surgery," "thoracic surgery," "lung surgery," "abdominal surgery," "solid organ transplantation," "thoraco-abdominal surgery" and "bariatric surgery" were combined with any of these: "non-invasive positive pressure ventilation," "continuous positive airway pressure," "bilevel ventilation," "postoperative complications," "postoperative care," "respiratory care," "acute respiratory failure," "acute lung injury" and "acute respiratory distress syndrome." Results: Twenty-nine articles (N = 2,279 patients) met the inclusion criteria. Nine studies evaluated NIV in post-abdominal surgery, three in thoracic surgery, eight in cardiac surgery, three in thoraco-abdominal surgery, four in bariatric surgery and two in post solid organ transplantation used both for prophylactic and therapeutic purposes. NIV improved arterial blood gases in 15 of the 22 prophylactic and in 4 of the 7 therapeutic studies, respectively. NIV reduced the intubation rate in 11 of the 29 studies and improved outcome in only 1. Conclusions: Despite these limited data and the necessity of new randomized trials, NIV could be considered as a prophylactic and therapeutic tool to improve gas exchange in postoperative patients. © 2011 jointly held by Springer and ESICM
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
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