1,720,984 research outputs found
Computational fluid dynamics as a means of assessing the influence of aerodynamic forces on the mean contact force acting on a pantograph
No full textThis paper discusses the possibility of using computational fluid dynamics (CFD) to assess the influence of aerodynamic
forces (aerodynamic uplift) on the mean contact force acting between a pantograph and the contact wire. The analysis
consists of experimental tests and CFD simulations, performed in both wind tunnel and on-track scenarios. A method
for the computation of the aerodynamic uplift and for the assessment of the contact force imbalance between the leading
and trailing collectors is proposed. The method is based on the virtual work principle, and exploits both the numerical
forces resulting from CFD analysis, and the Jacobian terms obtained from a kinematic analysis of the pantograph. The
proposed model takes into account stationary phenomena, and it is fully validated by means of experimental results
Is there a limit to transanal endoscopic surgery? A comparative study between standard and technically challenging indications among 168 consecutive patients
No full textAIM:
To assess the surgical outcome of transanal endoscopic surgery (TES) for rectal neoplasms in technically challenging indications.
METHOD:
All patients who underwent TES for a rectal neoplasm from 2007 to 2014 were included. Technically challenging indications included a tumour with (i) diameter ≥ 5 cm, (ii) involving ≥ 50% of the rectal circumference and (iii) located ≥ 10 cm from the anal verge. Patients were divided into three groups according to how many of these features they had, as follows: Group 1, none; Group 2, one; Group 3, two or more.
RESULTS:
Of the 168 patients (80 benign and 88 malignant tumours) included in the study, 73 (44%) were in Group 1, 46 (27%) in Group 2 and 49 (29%) in Group 3. There was no difference between Group 1 and Group 2 with regard to peritoneal perforation (P = 0.210), severe postoperative morbidity (P = 0.804), length of hospital stay (P = 0.444), incomplete resection (P = 0.441), piecemeal resection (P = 0.740), locoregional recurrence (P = 0.307) and long-term symptomatic rectal stenosis (P = 0.076). Conversely Group 3 showed significantly impaired results compared with Group 1 with regard to peritoneal perforation (P = 0.003), piecemeal resection (P = 0.005), incomplete resection (P = 0.025), locoregional recurrence (P = 0.035) and long-term symptomatic rectal stenosis (P < 0.001), but no difference in severe postoperative morbidity (P = 0.328).
CONCLUSION:
Transanal endoscopic surgery for rectal neoplasms appears to be safe and effective, even in patients presenting with a technically challenging tumours. Although the short- and long-term outcomes after TES are worse in patients with highly challenging tumours, nevertheless the technique should still be considered in patients at high risk of requiring a proctectomy
Peritoneal perforation is less a complication than an expected event during transanal endoscopic microsurgery. experience from 194 consecutive cases
No full textBackground: Indications for transanal endoscopic microsurgery (TEM) have been extended to technically challenging tumors, which may be associated with an increased risk of peritoneal perforation (PP). The aim of the present study was to investigate the occurrence, management and outcome of PP in patients having TEM. Methods: All the patients who had TEM for rectal adenoma or adenocarcinoma in our unit were included. Patients in whom PP occurred (Group A) were compared to those without PP (Group B). Results: From 2007 to 2015, 194 TEM (116 men, median age 66 [range 21–100] years) were divided into Groups A (n = 28, 14%) and B (n = 166). The latter group included four patients, in whom a laparoscopy did not confirm suspicion of PP made during TEM. In 2 of 28 patients (7%), the diagnosis of PP was made postoperatively during reoperation for peritonitis. For the 26 other patients (93%), routine exploratory laparoscopy was performed with suture of the peritoneal defect on the pouch of Douglas in 24 cases and a rectal suture alone in 2 cases. Independent predictive factors for PP were: distance from the anal verge >10 cm (OR = 3.6), circumferential tumor (OR = 3.0) and anterior location (OR = 2.7). Hospital stay was significantly longer in Group A (7.5 [3–31] days) than in Group B (4 [1–38] days; p < 0.0001), whereas there was no significant difference regarding postoperative morbidity and recurrence rate. Conclusions: Our results suggested that PP is not a very rare event during TEM, especially in anterior, circumferential and/or high rectal tumors. Laparoscopic treatment of PP is feasible and safe. The occurrence of PP is not associated with poor oncologic results
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
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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