1,720,974 research outputs found
NMR spectrocopic analysis of rat brain development:in vitro proton and carbon studies of whole tissue and its phospholipid fraction
No full textThe developmental patterns of the rat brain at several postnatal time points were investigated in Folch (chloroform-methanol) extracts. The chloroform- (lipid-containing) and water-soluble (cytosolic) fractions of whole-tissue extracts and the phospholipid fraction separated from the organic fraction by chromatography were analysed by means of high-resolution1H and 13C nuclear magnetic resonance (NMR) spectroscopy. Analysis of the cytosolic fraction showed the changing patterns of several brain metabolites during postnatal maturation, in full agreement with data obtained from perchloric acid extracts. 1H NMR spectroscopy of the phospholipid fraction allowed for quantitative evaluation of fatty acid acyl chain length, mean unsaturation and mean polyunsaturation. It was found that both mean unsaturation and polyunsaturation are lower in adult brain phospholipids than during the first 3 postnatal weeks. 13C NMR spectroscopy of the same fraction showed that the molar percentage of C18 fatty acids (oleic, linoleic, linolenic) in brain phospholipids is similar at all the investigated time points. These results indicate that the combination of Folch extraction with simple chromatographic procedures and NMR analysis yields useful data to define the chemical maturation of the brain. Copyright © 2001 S. Karger AG, Basel
Optimized determination of clobazam in human plasma with extraction and high-performance liquid chromatography analysis
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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
Impact of Residual Setup Error on Parotid Gland Dose in Intensity-Modulated Radiation Therapy with or without Planning Organ-at-Risk Margin
No full textPurpose: To estimate the dosimetric impact of residual setup errors on parotid sparing in head-and-neck (H&N) intensity-modutated treatments and to evaluate the effect of employing an PRV (planning organ-at-risk volume) margin for the parotid gland. Patients and Methods: Ten patients treated for H&N cancer were considered. A nine-beam intensity-modutated radiotherapy (IMRT) was planned for each patient. A second optimization was performed prescribing dose constraint to the PRV of the parotid gland. Systematic setup errors of 2 mm, 3 mm, and 5 mm were simulated. The dose-volume histograms of the shifted and reference plans were compared with regard to mean parotid gland dose (MPD), normal-tissue complication probability (NTCP), and coverage of the clinical target volume (V(95%) and equivalent uniform dose [EUD]); the sensitivity of parotid sparing on setup error was evaluated with a probability-based approach. Results: MPD increased by 3.4%/mm and 3.0%/mm for displacements in the craniocaudal and lateral direction and by 0.7%/mm for displacements in the anterior-posterior direction. The probability to irradiate the parotid with a mean dose > 30 Gy was > 50%, for setup errors in cranial and lateral direction and < 10% in the anterior-posterior direction. The addition of a PRV margin improved parotid sparing, with a relative reduction in NTCP of 14%. The PRV margin compensates for setup errors of 3 mm and 5 mm (MPD <= 30 Gy in 87% and 60% of cases), without affecting clinical target volume coverage (V(95%) and EUD variations < 1% and < 1 Gy). Conclusion: The parotid gland is more sensitive to craniocaudal and lateral displacements. A setup error of 2 mm guarantees an MPD : 30 Gy in most cases, without adding a PRV margin. If greater displacements are expected/accepted, an adequate PRV margin could be used to meet the clinical parotid gland constraint of 30 Gy, without affecting target volume coverage
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
Biogenic amines in the taste organ
No full textThe presence and content of biogenic amines in taste disk-bearing fungiform papillae of the frog, Rana esculenta, the only available model of an isolated taste organ, were verified by means of HPLC. Fungiform papillae were found to contain measurable amounts of serotonin, epinephrine and norepinephrine. The amounts of serotonin and epinephrine were significantly higher in fungiform papillae than in the general mucosa of the tongue. Moreover, the epinephrine content of fungiform papillae was found to differ across the tongue, in accordance with previous physiological studies showing an inhomogeneous response of different tongue regions to taste stimuli. Ultrastructural and histochemical investigations confirmed the presence of catecholamine and serotonin. The latter was found to be contained mainly in the basal cells of the frog taste disk. These results extend previous qualitative data on the presence of biogenic amines in taste chemoreceptors
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