1,720,973 research outputs found
Rapid quantitation of cocaine and benzoylecgonine in urine by "on column" capillary gas chromatography after "Extrelut" extraction
No full textCocaine (I) [50-36-2] and its principal metabolite in man, benzoylecgonine [519-09-5], were detd. in urine by on column capillary gas chromatog. equipped with an NP detector. Isopropylbenzoylecgonine was used as the internal std. The extn. procedure was carried out with Extrelut. CH2N2 was utilized for derivatizing benzoylecgonine. The procedure was applied to a no. of urine samples received from a quality control program; the relative errors were 11.7% and 7.5% for I and benzoylecgonine, resp
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
Linee guida per i laboratori di analisi delle droghe d'abuso con finalità medico-legali : commissione del Gruppo Tossicologi Forensi (GTF) presso il Ministero della Salute
No full textMorte per uso voluttuario di butano ed etanolo: caratterizzazione nei distretti tissutali del butano di una bomboletta di gas da campeggio
No full textDispelling 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
Disposition of morphine and codeine in blood and in brain samples in cases of fatal heroin overdose
No full textWhen fatal heroin overdose is suspected, blood samples are traditionally analyzed by GC/MS, after extraction and derivatization, to determine the active metabolites 6-MAM and morphine. This method allows also to perform a so known “generic investigation” of the basic compounds, including impurities and cutting agents of “street heroin”, such as acetylcodeine and its metabolite codeine.
The concentration of morphine in blood is usually the most important analytical result for the interpretation of the cause of death [1]. However, a number of overdose fatalities show relatively low blood concentrations of morphine, i.e. below or similar to those of living consumers or intoxicated heroin users [2]. This could be due to a variety of reasons, such as the relationship between lethal dose and current individual tolerance [3], the complexity of heroin metabolism, the presence of systemic dysfunction and the contemporary use of other drugs of abuse. Moreover, post-mortem redistribution or drug instability can affect the concentration of drugs in blood [4].
In post-mortem forensic toxicology the analysis of brain specimens may be also useful. Indeed, the sites of action of heroin and its main metabolites are primarily located in the central nervous system, so that concentrations in post-mortem brain samples are close or equal to those responsible for the toxic effects which caused death.
Brain distribution pattern of “street” heroin metabolites (morphine and codeine) was investigated in two fatalities due to “acute narcotism” [5]. A suitable sample pretreatment prior to solid-phase-extraction was developed to achieve a good recovery of the analytes and to eliminate interfering species. After derivatization with MSTFA, samples were analyzed by GC/MS. Specificity, accuracy, precision and linearity of the method were evaluated. This method was applied to the analysis of six brain areas (hippocampus, frontal lobe, occipital lobe, nuclei, bulb and pons) coming from the two cases of heroin-related deaths. No evidence of accumulation of metabolites in a specific brain region was found, so bulb, which is the specimen that is usually taken during an autopsy, can be considered as representative of the drug concentration in the whole brain.
Subsequently, the concentration of morphine and codeine in brain was investigated in fourteen samples belonging to cases of suspected fatal heroin overdose. Results were compared to those coming from the analysis of blood specimens. No correlation was found between the concentrations of morphine and codeine in blood and brain, but a higher ratio between codeine and morphine was found in brain, suggesting an accumulation and/or a slower metabolism of this more hydrophobic derivative in that compartment
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