177,772 research outputs found

    Appropriate Similarity Measures for Author Cocitation Analysis

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    We 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

    "Closing the R&D Gap, Evaluating the Sources of R&D Spending"

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    Both spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.

    Systemic oxidative alterations are associated with visceral adiposity and liver steatosis in patients with metabolic syndrome

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    Although evidence suggests the link between chronic inflammation and oxidative stress as the main mechanism responsible for endothelial dysfunction and cardiovascular complications in patients with metabolic syndrome, little is known about the determining role of each metabolic syndrome component in such alterations. This study investigated the relation between systemic oxidative alterations and metabolic syndrome features in 41 patients. Compared with control subjects, serum vitamin C and alpha-tocopherol concentrations were lower and those of lipid peroxides [thiobarbituric acid reactive substances (TBARs)] were higher in metabolic syndrome patients (P < 0.001). A linear relation was observed between visceral fat thickness and serum TBARs:cholesterol ratio (r = 0.541, P < 0.001), whereas negative correlations were found between alpha-tocopherol and BMI (r = -0.212, P < 0.05) and the grade of liver steatosis (r = -0.263, P < 0.02). Patients with metabolic syndrome and liver steatosis had higher serum hyaluronate (HA) concentrations (P < 0.001). Serum HA was positively correlated with serum alanine amino transferase (r = 0.715, P < 0.001) and the homeostasis monitoring assessment index (r = 0.248, P < 0.03). The presence of metabolic syndrome was predicted from a linear combination of visceral fat and all oxidative variables. In metabolic syndrome patients, serum nitrosothiols and vitamin C concentrations, which were lower (P < 0.001) than in control subjects, were inversely related to the grade of hypertension (r = -0.645, P < 0.001 and r = -0.415, P < 0.007, respectively). In conclusion, metabolic syndrome patients exhibited decreased antioxidant protection and increased lipid peroxidation. Our results indicate a strong association between increased abdominal fat storage, liver steatosis, and systemic oxidative alterations in metabolic syndrome patients and diminished nitrosothiols and vitamin C concentrations as important factors associated with hypertension in these patient

    Going Beyond Counting First Authors in Author Co-citation Analysis

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    The 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

    Relation of Gallbladder Motility to Viscosity and Composition of Gallbladder Bile in Patients with Cholesterol Gallstones

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    Background/Aims: Increased viscosity and supersaturation of cholesterol in gallbladder bile, as well as an impaired motility of the gallbladder, are considered to be important factors in the pathogenesis of cholesterol gallstones. However, the relation of these parameters has not yet been determined. Material and Methods: Bile viscosity (mPa.s) was measured by rotation viscosimetry and the composition of gallbladder bile was determined using standard methodology. Gallbladder motility was calculated as ejection fraction in percent of total volume 45 min after a test meal using ultrasonography in patients with gallstones prior to elective cholecystectomy. Results: The study included 35 patients with cholesterol gallstones. Viscosity of gallbladder bile ranged between 0.9 and 12.5 mPa.s (median 2.2 mPa.s) and an ejection fraction of the gallbladder of 55.4 +/- 18.3% (mean +/- SD) was determined. No significant correlation (r = 0.19, p < 0.2) between the 2 parameters could be calculated. Analysis of the composition of gallbladder bile revealed a positive correlation of all components to biliary viscosity but not to the motility of the gallbladder, with the exceptions of a negative correlation (r = 0.39, p < 0.02) between mucin concentration and the ejection fraction at 45 min after the test meal. Conclusions: The motility of the gallbladder appears to be unrelated to the viscosity of gallbladder bile or gallbladder bile composition. The negative correlation between the ejection fraction of the gallbladder and mucin concentration of gallbladder bile suggests that chronic inflammation of the gallbladder wall is associated with both an impaired motility of the gallbladder and increased mucin release into gallbladder bile. Copyright (C) 2009 S. Karger AG, Base

    SUSCEPTIBILITY TO CRACKING OF THIRTY SWEET CHERRY CULTIVARS

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    Nowadays, Apulia (Southern Italy) is the most important sweet cherry (Prunus avium L.) producer in Italy. New cultivars are introduced by growers to complement those traditionally grown, often without ascertaining their adaptability to local environmental conditions. Among disregarded characteristics is the susceptibility to rain-induced fruit cracking. The problem is worthy of consideration even if rainfall in Apulia during cherry ripening (May 15-June 20) is not as heavy and frequent as in other world cherry growing districts. The cracking index for 30 cultivars has been evaluated over three years according to Verner's (1957) method, as modified by Christensen (1972). The study confirmed that the susceptibility to cracking is a characteristic linked to genotype. No variety was totally resistant, but some of the little known varieties showed an interesting level of resistance. A susceptibility scale is proposed. (This paper was presented at the 4(th) International Cherry Symposium held 24-29 June 2001 in the USA)
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