1,721,129 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
Correlation between manometric morphology of small hiatal hernia and gastroesophageal reflux.
No full textHiatal hernia (HH) plays a prominent role in the pathogenesis of GERD. A
rapid pull through (RPT) technique during esophageal manometry discloses
various pressure profiles of HH, based on the identification of two
high pressure zones: the crural diaphragm (CD) and the lower esophageal
sphincter (LES). Our aim was to correlate the different profiles of HH with
frequency of reflux episodes in patients with GERD. Methods: We included
69 patients with GERD and small «3cm) and reducible HH
diagnosed endoscopically. In all subjects esophageal manometry and 24
pH-metry were performed on two successive days. The RPT (1 ern/sec)
was performed in end-inspiration apnoea using a three-lumen (radial opentips)
catheter. The procedure was repeated ten times, obtaining 30 pressure
traces in each patient. The CD and LES provoke either distinct pressure
peaks: diaphragm peak (DP) and sphincter peak (SP) respectively or
distinct small pressure deflections: diaphragm deflection (DD) and sphincter
deflection (SD). The various combinations of peak and/or deflection
identified four manometric HH profiles: A (DD-SP), B (DP-SD), C (DPSP)
and D (DD-SD). The overlapping of CD and LES, that is consistent
with HH reducibility, determines a fifth pressure profile (E) characterised
by a single peak. Patients were divided in 5 groups according to the
prevalence of one of the pressure profiles (A n=4; B n=2; C n=30; D
n= 18; En= 15). Twenty four hours pH-metry in distal esophagus was also
performed to calculate the number of reflux events during total, upright,
recumbent and postprandial periods. Statistical analysis comparison was
performed among the different patients groups using Mann-Whitney test.
Groups A and B were excluded from analysis because of the small number
of patients. Results: The frequency of reflux events during total and upright
periods was significantly higher in the D group (240±37 and 180±33) than
in the C group (120±19 and 95±18 respectively). No significant differences
were found during recumbent and postprandial periods. In conclusion,
patients with small hiatal hernia with a double-deflection pressure
profile (absence of pressure peaks) have the highest frequency of reflux
events reinforcing the concept that both CD and LES pressure peaks are
necessary for the continence of esophagogastric junction. Finally, the
manometric study of esophagogastric junction by RPT technique represents
an useful approach to understand pathogenetic mechanisms of
GER
Mechanisms underlying duodeno-gastric reflux in man.
No full textRecent studies suggest that duodeno-gastro-oesophageal reflux (DGER) contributes to the occurrence of reflux oesophagitis and Barrett's oesophagus. The mechanisms underlying duodeno-gastric reflux (DGR), a prerequisite for DGER, are poorly understood. AIMS: To study the occurrence of DGR in relation to interdigestive and postprandial gastroduodenal motility. SUBJECTS AND METHODS: Ten healthy subjects underwent stationary gastroduodenal manometry with simultaneous duodenal and antral Bilitec recording 4 h before and 5 h after ingestion of a liquid meal. Eight volunteers underwent the same study, with administration of erythromycin postprandially. RESULTS: During the interdigestive phase II, all volunteers had short DGR episodes. Postprandially, DGR occurred in all subjects, on average 39 +/- 28 min after the start of the meal, and was cleared from the stomach after 242 +/- 23 min. Induction of increased antral motility and of a premature phase III, by administration of erythromycin, was associated with faster gastric DGR clearance. However, there was no direct temporal relationship between erythromycin-induced gastric phase III and erythromycin-induced DGR clearance. CONCLUSION: In healthy subjects, duodenogastric reflux occurs sporadically in the interdigestive state and is a normal phenomenon in the postprandial period. Erythromycin induces faster clearance of DGR from the stomach, which depends on enhanced antral contractile activity rather than premature phase III
Episode-level reflux characteristics: How experienced reviewers differentiate true reflux from artifact on pH-impedance studies
No full textBackground: Accurate reflux episode identification is crucial for pH-impedance interpretation. Individual reflux episode characteristics associated with inter-reviewer concordance are incompletely understood. Methods: Ambulatory pH-impedance studies from 19 GERD patients (median age 52 years, 78.9% F) were analyzed by 5 reviewers. Metadata from pH-impedance studies were exported to a dedicated software tool designed to compare episode-by-episode identification between reviewers within a ±7.5 s window. Patient position, acidic vs. nonacidic episodes, acid clearance time (ACT), bolus clearance time (BCT), and proximal extent of reflux episodes were compared between episodes identified by all reviewers against those identified by automated analysis, and one to four reviewers, respectively. Results: Automated analysis identified 1644 episodes (median 78 episodes per patient, IQR 64-108), of which 84.9% were identified by ≥3 reviewers and 57.1% by all reviewers; 339 unique episodes were added by at least 1 reviewer. Characteristics defining 5 reviewer concordance included acid reflux episodes (88.9%), upright episodes (88.4%), high proximal extent (median 17 cm, IQR 15-17 cm), and longer acid clearance times (67.0 s, IQR 29.0-146.0 s) (P < 0.001 compared to 1-4 reviewer concordance for each). In contrast, 1 reviewer-identified episodes were 69.8% acidic, 76.9% upright, and limited to the distal esophagus. Using 5-reviewer concordance, designation of GERD evidence changed from automated analysis in 16%-19% of patients. Conclusions: Acidic episodes with high proximal extent in the upright position and longer acid clearance times on pH-impedance studies have the highest concordance for identification by expert reviewers. Reflux episode identification may be influenced by reviewer opinion despite availability of established criteria
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
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