1,721,056 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Get PDF“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
Get PDFWe 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
Heart-rate adaptive match filter based procedure for automatic detection of T-wave alternans from 24-hour ECG recordings: Issues related to filter implementation
No full textTwenty-four hour T-wave alternans (TWA) analysis is a promising approach for risk stratification, which still remains unpractical because TWA identification algorithms are complex and require long computation time (CT). The aim of the present study was to test the applicability to 24-hour ECG recordings of our heart-rate adaptive match filter (AMF) which allows TWA detection by submitting ECG data to a band-pass filter centered at the TWA fundamental frequency fTWA, equal to a half heart rate. Two implementations are possible: 1) the passing-band is adapted to a varying f TWA value (FA-AMF), and 2) the filter band is fixed while conditioning the ECG data (SA-AMF). Simulated ECG tracings, characterized by no TWA or by different kinds of TWA, and 24-hour ECG recordings from healthy subjects and coronary artery disease patients were used to identify the fastest of these two implementations. Our results yielded the conclusions that the CT of our AMF-based procedure is independent of the amount of TWA present in the tracing, but depends on ECG sample length and filter implementation. If filter-design tools are available while performing ECG analysis, the FA-AMF implementation is to be preferred because its CT is about one third of SA-AMF CT
EFFETTO DELLA VELOCITÀ DI ASSUNZIONE DI CIBO E DELLA PALATABILITA¿ SULLA SECREZIONE DI PEPTIDI GASTROINTESTINALI NELL¿ OBESITA¿ SEMPLICE E GENETICA.
Get PDFAnorexigenic gastrointestinal hormones as peptide YY (PYY), glucagon-like peptide 1 (GLP-1) and orexigenic hormone ghrelin influence the activity of the arcuate nucleus (ARC) neurons in the hypothalamous. The ARC plays a crucial role in the regulation of food intake and energy homeostasis. In contrast, the mesolimbic dopamine system encodes subjective ‘liking’ and ‘wanting’ of palatable foods, which is subjected to modulation by the hindbrain and the hypothalamic homeostatic circuits and by satiety and adiposity hormones.
Reportedly, obesity reflects an energy imbalance in which genetically susceptible individuals become increasingly vulnerable to an ‘obesogenic’ environment. Dietary and behavioral approaches to severe obesity are frequently associated with limited persistent success over the time rendering bariatric surgery one of the more promising therapy for “super-obese” patients. Laparoscopic sleeve gastrectomy (LSG) is a purely “restrictive” operation applied in patients with body mass index (BMI) <50 kg/m2. Although early enthusiastic results on weight loss after LSG have been published, the underlying mechanism(s) of weight loss is still unknown and it could involve pos-LSG alterations of gastrointestinal hormones.
Nowadays the number of overweight and obese people in the world are roughly 2 billion in 2013. The lifestyle of the modern civilization facilitates diffusion of fast feeding and, consequently, high energy intake. At the same time hedonic hunger may powerfully stimulate food intake in an environment where highly palatable foods are omnipresent and contribute to the diffusion of overweight and obesity. Therefore, understanding the physiological mechanisms underlying these eating behaviors may help to contrast it.
The anorexigenic action of PYY is preserved in obese patients, although the circulating level of the peptide is low during fast and postprandial phase. obese individuals actually display low circulating ghrelin levels that could suggest greater sensitivity to the hormone. A pathogenic role for ghrelin has been suggested in individuals with genomic obesity as Prader–Willi syndrome, where hyperghrelinism precedes the development of obesity. On the contrary, only few studies have investigated postprandial GLP-1 and PYY in PWS, besides reporting conflicting results.
Since the critical rule of gastrointestinal hormones in homeostatic and hedonic regulation of food intake and in the physiophatology of obesity we decided to study dynamically their secretion in association with eating behavior involved with the development of obesity.
Particularly we conducted three studies:
Study 1: evaluation of post-prandial anorexigenic gut peptide, appetite and glucometabolic responses at different eating rates in obese patients undergoing laparoscopic sleeve gastrectomy.
Aim of this study was to determine whether eating the same meal at different rates (fast vs. slow feeding) evokes different post-prandial anorexigenic gut peptide responses in ten obese patients undergoing LSG. Circulating levels of GLP-1, PYY, glucose, insulin and triglycerides were measured before and 3 months after LSG. Visual analog scales were used to evaluate the subjective feelings of hunger and satiety.
Irrespective of the operative state, either fast or slow feeding did not stimulate GLP-1 release (vs. 0 min); plasma levels of PYY were increased (vs. 0 min) by fast and slow feeding only after LSG. There were no differences in post-prandial levels of GLP-1 when comparing fast to slow feeding or pre- to post-operative state. Plasma levels of PYY after fast or slow feeding were higher in post- than preoperative state, with no differences when comparing PYY release after fast and slow feeding. Hunger and satiety were decreased and increased, respectively, (vs. 0 min) by food intake. Fast feeding evoked a higher satiety than slow feeding in either preor post-operative state, with no differences in hunger. In pre- or post-operative state there were similar responses for hunger and satiety after food intake. Finally, LSG improved insulin resistance after either fast or slow feeding.
These (negative) findings would suggest a negligible contribution of the anorexigenic gut peptide responses in LSG-induced weight loss.
Study 2: anticipatory and consummatory effects of (hedonic) chocolate intake on PYY, GLP-1, ghrelin and endocannabinoid secretion in obese adults previously satiated.
To explore the role of some gastrointestinal orexigenic and anorexigenic peptides and endocannabinoids (and some related congeners) in chocolate consumption, we measured changes in circulating levels of ghrelin, glucagon-like peptide 1 (GLP-1), peptide YY (PYY), anandamide (AEA), 2-AG, palmitoylethanolamide (PEA), and oleoylethanolamide (OEA) in 10 satiated severely obese subjects after consumption of chocolate and, on a separate day, of a non-palatable isocaloric food with the same bromatologic composition. Evaluation of hunger and satiety was also performed by visual analogic scale.
The anticipatory phase and the consumption of food for pleasure were associated with increased circulating levels of ghrelin, AEA, 2-AG, and OEA. In contrast, the levels of GLP-1, PYY, and PEA did not differ before and after the exposure/ingestion of either chocolate or non-palatable foods. Hunger and satiety were higher and lower, respectively, in the hedonic session than in the non-palatable one.
When motivation to eat is generated by exposure to, and consumption of, chocolate a peripheral activation of specific endogenous rewarding chemical signals, including ghrelin, AEA, and 2-AG, is observed in obese subjects. Although preliminary, these findings predict the effectiveness of ghrelin and endocannabinoid antagonists in the treatment of obesity.
Study 3: evaluation of post-prandial anorexigenic gut peptide, appetite and glucometaboplic responses at different eatin rates in adult PWS patients
The effect of eating rate on the release of anorexigenic gut peptides in Prader-Willi syndrome (PWS), a neurogenetic disorder clinically characterized by hyperphagia and excessive obesity, has not been investigated so far.Postprandial PYY and GLP-1 levels to fast (5 min) and slow (30 min) ice cream consumption were measured in PWS adult patients and age-matched patients with simple obesity and normal-weighted subjects. Visual analog scales (VASs) were used to evaluate the subjective feelings of hunger and satiety.
Fast ice cream consumption stimulated GLP-1 release in normal subjects, a greater increase being observed with slow feeding. Fast or slow feeding did not change circulating levels of GLP-1 in obese patients, while, unexpectedly, fast feeding (but not slow feeding) stimulated GLP-1 release in PWS patients. Plasma PYY concentrations increased in all groups, irrespective of the eating rate. Slow feeding was more effective in stimulating PYY release in normal subjects, while fast feeding was more effective in PWS patients. Slow feeding evoked a lower hunger and higher satiety compared with fast feeding in normal subjects, this finding being not evident in obese patients. Unexpectedly, fast feeding evoked a lower hunger and higher satiety in PWS patients in comparison with slow feeding.
Fast feeding leads to higher concentrations of anorexigenic gut peptides and favours satiety in PWS adult patients, this pattern being not evident in age-matched patients with simple obesity, thus suggesting the existence of a different pathophysiological substrate in these two clinical conditions
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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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