1,721,032 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
Imaging-guided interventions modulating portal venous flow: Evidence and controversies
Full text linkPortal hypertension is defined by an increase in the portosystemic venous gradient. In most cases, increased resistance to portal blood flow is the initial cause of elevated portal pressure. More than 90% of cases of portal hypertension are estimated to be due to advanced chronic liver disease or cirrhosis. Transjugular intrahepatic portosystemic shunts, a non-pharmacological treatment for portal hypertension, involve the placement of a stent between the portal vein and the hepatic vein or inferior vena cava which helps bypass hepatic resistance. Portal hypertension may also be a result of extrahepatic portal vein thrombosis or compression. In these cases, percutaneous portal vein recanalisation restores portal trunk patency, thus preventing portal hypertension-related complications. Any portal blood flow impairment leads to progressive parenchymal atrophy and triggers hepatic regeneration in preserved areas. This provides the rationale for using portal vein embolisation to modulate hepatic volume in preparation for extended hepatic resection. The aim of this paper is to provide a comprehensive evidence-based review of the rationale for, and outcomes associated with, the main imaging-guided interventions targeting the portal vein, as well as to discuss the main controversies around such approaches. (c) 2022 The Authors. Published by Elsevier B.V. on behalf of European Association for the Study of the Liver (EASL). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/ licenses/by-nc-nd/4.0/)
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
“FREE AIR” IS NOT AN INDICATION FOR EMERGENCY SURGERY IN HAEMODYNAMICALLY STABLE PATIENTS PRESENTING WITH ACUTE DIVERTICULITIS: RE-THINKING THE APPROACH BASED ON CT FINDINGS.
No full textChallenging a classic myth: pneumoperitoneum associated with acute diverticulitis is not an indication for open or laparoscopic emergency surgery in hemodynamically stable patients. A 10-year experience with a nonoperative treatment.
No full textBackground
In patients presenting with acute diverticulitis (AD) and signs of acute peritonitis, the presence of extradigestive air (EDA) on a computer tomography (CT) scan is often considered to indicate the need for emergency surgery. Although the traditional management of “perforated” AD is open sigmoidectomy, more recently, laparoscopic drainage/lavage (usually followed by delayed elective sigmoidectomy) has been reported. The aim of this retrospective study is to evaluate the results of nonoperative management of emergency patients presenting with AD and EDA.
Methods
The outcomes of 39 consecutive hemodynamically stable patients (23 men, mean age = 54.7 years) who were admitted with AD and EDA and were managed nonoperatively (antibiotic and supportive treatment) at a tertiary-care university hospital between January 2001 and June 2010 were retrospectively collected and analyzed. These included morbidity (Clavien-Dindo) and treatment failure (need for emergency surgery or death). A univariate analysis of clinical, radiological, and laboratory criteria with respect to treatment failure was performed. Results of delayed elective laparoscopic sigmoidectomy were also analyzed.
Results
There was no mortality. Thirty-six of the 39 patients (92.3%) did not need surgery (7 patients required CT-guided abscess drainage). Mean hospital stay was 8.1 days. Duration of symptoms, previous antibiotic administration, severe sepsis, PCR level, WBC concentration, and the presence of abdominal collection were associated with treatment failure, whereas “distant” location of EDA and free abdominal fluid were not. Five patients had recurrence of AD and were treated medically. Seventeen patients (47.2%) underwent elective laparoscopic sigmoidectomy for which mean operative time was 246 min (range = 100–450) and the conversion rate was 11.8%. Mortality was nil and the morbidity rate was 41.2%. Mean postoperative stay was 7.1 days (range = 4–23).
Conclusions
Nonoperative management is a viable option in most emergency patients presenting with AD and EDA, even in the presence of symptoms of peritonitis or altered laboratory tests. Delayed laparoscopic sigmoidectomy may be useless in certain cases and its results poorer than expected
SYNCHRONOUS PYOGENIC LIVER ABSCESS AND ACUTE CHOLECYSTITIS: HOW TO RECOGNIZE IT, WHAT TO DO (EMERGENCY CHOLECYSTOSTOMY FOLLOWED BY DELAYED LAPAROSCOPIC CHOLECYSTECTOMY).
No full textBackground
The treatment of synchronous pyogenic liver abscess (PLA) and acute cholecystitis (AC) may be challenging. Moreover, because of the similarity of symptoms and the suboptimal accuracy of ultrasound (US), PLA(s) may be undetected, unless a computer tomography (CT) scan is performed. The aims of this study were (1) to evaluate the results of emergency cholecystostomy (CS) and late laparoscopic cholecystectomy (LC) in such a population and (2) to identify the criteria for selecting patients with AC and a high risk of having synchronous PLA(s) for referral for a CT scan.
Methods
A retrospective analysis of the outcome of 12 patients with AC and PLA(s) treated by emergency CS followed by delayed LC from January 1996 through May 2010 at a tertiary-care university hospital was performed. Clinical, laboratory, and radiological data of patients with synchronous AC and PLA(s) are compared with those of 66 patients with “simple” AC.
Results
The association of age >55 years, temperature >38°C, WBC count >12,000/ml, and ASAT >50 UI/l and/or ALAT >75 UI/l allows for the selection of patients at high risk of PLA to undergo a CT scan (sensitivity: 100%; specificity: 86%). All treated patients had a sudden improvement within 24 h following CS. PLA was treated in 10/12 patients (83%). Hospital stay lasted 21.5 ± 3.5 days. Ten patients underwent elective LC 12 ± 4 weeks after CS with no conversion and 30% perioperative morbidity. Operating time was 91 min. Hospital stay was 1.7 days [7 patients (70%) underwent surgery as an outpatient].
Conclusions
A simple algorithm is presented for the selection of patients with AC to undergo a CT scan to identify synchronous PLA. Emergency CS followed by delayed LC is a viable, first-line treatment option for synchronous PLA and AC
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