1,721,027 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
Thermal oxidation of cholesterol: preliminary evaluation of 2-methyl-6-heptanone and 3-methylbutanal as volatile oxidation markers
No full textCholesterol oxidation in food and model systems is usually monitored by evaluating cholesterol oxidation
products, but the analysis is time-consuming and expensive. Therefore, the determination of volatile
compounds deriving from cholesterol thermoxidation could be valuable to identify other possible oxidation
markers. Cholesterol alone and in the presence of a triacylglycerol mixture (tripalmitin, tristearin,
and triolein) were thermoxidized at 170 °C for 15 min. In both model systems, the total volatile compounds
increased three times when oxidation time rose from 5 to 15 min. The main classes of volatile
compounds were aldehydes, ketones, alcohols and hydrocarbons, displaying a similar behavior in both
systems. After 5 min of oxidation, 2-methyl-6-heptanone was the main volatile compound, followed
by 3-methylpentane, 2,3-dimethyl-1-pentene and 3-methylbutanal. To verify if 2-methyl-6-heptanone
could be used as volatile marker of cholesterol oxidation, data were compared with the total cholesterol
oxidation products content of each system. A significant correlation between total cholesterol oxidation
products content and 2-methyl-6-heptanone amount was found when cholesterol was oxidized alone
(r2 = 0.994) and in presence of triacylglycerols (r2 = 0.998). When egg yolk was thermoxidized at 80 °C
for 6 h, 3-methylbutanal was the volatile compound that better explained the oxidative trend in this food
system, showing a significant correlation with cholesterol oxidation rate (r = 0.91). In conclusion, 2-
methyl-6-heptanone and 3-methylbutanal could represent an easy and cheaper strategy for monitoring
cholesterol oxidation in model systems and food samples, respectively; however, a deeper investigation
on the amount and type of volatile compounds generated from cholesterol oxidation according to the
food matrix, should be carried out
Energy Use and Economic Evaluation of a Three Year Crop Rotation for Conservation and Organic Farming in NE Italy
No full text[Pediatric non-alcoholic fatty liver disease: recent advances and challenges].
No full textNon-alcoholic fatty liver disease (NAFLD) encompasses a range of liver histology severity and outcomes in the absence of chronic alcohol use. The mildest form is simple steatosis in which triglycerides accumulate within hepatocytes. A more advanced form of NAFLD, non-alcoholic steatohepatitis (NASH), includes inflammation and liver cell injury, progressive to cryptogenic cirrhosis. Although prevalence in children is very difficult to establish, NAFLD is probably the most common cause of liver disease in preadolescent and adolescent groups. Over the last two decades the rise in the prevalence rates of overweight and obesity likely explains the NAFLD epidemic worldwide. NAFLD is strongly associated with abdominal obesity, type 2 diabetes, and dyslipidemia, and most patients have evidence of insulin resistance. Thus, NAFLD shares many features of the metabolic syndrome, a highly atherogenic condition, and its presence could signify a substantial cardiovascular risk. Accurate diagnosis and staging of NAFLD requires liver biopsy. The development of non-invasive surrogate markers and the advancement in imaging technology will aid in the screening of large populations at risk for NAFLD. While the optimal treatment has yet to be determined, lifestyle modification through diet and exercise should be attempted in children diagnosed with NAFLD. This review outlines current understanding, recent advances and challenges on pediatric NAFLD for both clinicians and researchers. Key words: Fatty liver
Thermal oxidation of cholesterol: preliminary evaluation of 2-methyl-6-heptanone as volatile marker
No full textCholesterol oxidation in food and model systems is usually monitored by evaluating cholesterol oxidation products (COPs), but the analysis is time-consuming and expensive. Therefore, the determination of volatile compounds deriving from cholesterol thermoxidation could be valuable to identify a possible marker of its oxidative status. Cholesterol alone and in the presence of triacylglycerols (TAG) (tripalmitin (29%); tristearin (12%) triolein (53%); cholesterol (6%)), were thermoxidized at 170 °C for 15 min. In both model systems, the total volatile compounds increased three times when oxidation time rose from 5 to 15 min. The main volatile compounds were aldehydes, ketones, alcohols and hydrocarbons and they displayed a similar behavior in both systems. After 5 min of oxidation, 2-methyl-6-heptanone was the main volatile compound, followed by 3-methylpentane, 2,3-dimethyl-1-pentene and 3-methylbutanale. All these volatile compounds increased with similar ratio in both model systems, but only a significant effect (p≤ 0.05) of cholesterol oxidation on 2-methyl-6-heptanone formation was found. To confirm that 2-methyl-6-heptanone could be suggested as possible volatile marker of cholesterol oxidative status, the 2-methyl-6-heptanone data were compared with the COPs content of each system. COPs formation was faster when cholesterol was heated alone than in presence of TAGs. The most abundat COPs was 7alfa-hydroxycholesterol, followed by 7-ketocholesterol, 7beta-hydroxycholesterol, beta-epoxycholesterol, alfa-epoxycholesterol, and 25-hydroxycholesterol. A significant correlation between the total COPs content and 2-methyl-6-heptanone amount was found when cholesterol was oxidized alone (R2=0.994) and in presence of TAG (R2=0.998). In conclusion, 2-methyl-6-heptanone could represent an easy and cheaper strategy for monitoring the oxidation of cholesterol; however, a deeper investigation on the relationship between volatile compounds and cholesterol oxidation in food matrices should be carried out
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
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