1,720,961 research outputs found
Simultaneous determination of free mycophenolic acid and its glucuronide in serum of patients under mycophenolate mophetil therapy by ion-pair reversed-phase liquid chromatography with diode array UV detection.
No full textLiquid chromatographic determination of urinary 5-methyl-2'-deoxycytidine and pseudouridine as potential biological markers for leukaemia.
No full textChemical signature of colorectal cancer: case–control study for profiling the breath print
Full text linkBackground: Effective screening for colorectal cancer can reduce mortality by early detection of tumours
and colonic polyps. An altered pattern of volatile organic compounds (VOCs) in exhaled breath has been
proposed as a potential non-invasive diagnostic tool for detection of cancer. The aim of this study was
to evaluate the reliability of breath-testing for colorectal cancer screening and early diagnosis using an
advanced breath sampler.
Methods: The exhaled breath of patients with colorectal cancer and non-cancer controls with negative
findings on colonoscopy was collected using the ReCIVA® Breath Sampler. This portable device is
able to capture the alveolar breath fraction without environmental contamination. VOCs were desorbed
thermally and analysed by gas chromatography–mass spectrometry. The discriminatory ability of VOCs
in detecting colorectal cancer was evaluated by receiver operating characteristic (ROC) curve analysis for
each VOC, followed by cross-validation by the leave-one-out method, and by applying stepwise logistic
regression analysis.
Results: The study included 83 patients with colorectal cancer and 90 non-cancer controls. Fourteen
VOCs were found to have significant discriminatory ability in detecting patients with colorectal cancer.
The model with the diagnosis of cancer versus no cancer resulted in a statistically significant likelihood
of discrimination of 173⋅45 (P <0⋅001), with an area under the ROC curve of 0⋅979. Cross-validation of
the model resulted in a true predictive value for colorectal cancer of 93 per cent overall. Reliability of the
breath analysis was maintained irrespective of cancer stage.
Conclusion: This study demonstrated that analysis of exhaled VOCs can discriminate patients with
colorectal cancer from those without. This finding may eventually lead to the creation of a smart online
sensory device, capable of providing a binary answer (cancer/no cancer) and directing to further screening
Chemical signature of colorectal cancer: case-control study for profiling the breath print
No full textBackground: Effective screening for colorectal cancer can reduce mortality by early detection of tumours and colonic polyps. An altered pattern of volatile organic compounds (VOCs) in exhaled breath has been proposed as a potential non-invasive diagnostic tool for detection of cancer. The aim of this study was to evaluate the reliability of breath-testing for colorectal cancer screening and early diagnosis using an advanced breath sampler.
Methods: The exhaled breath of patients with colorectal cancer and non-cancer controls with negative findings on colonoscopy was collected using the ReCIVA® Breath Sampler. This portable device is able to capture the alveolar breath fraction without environmental contamination. VOCs were desorbed thermally and analysed by gas chromatography-mass spectrometry. The discriminatory ability of VOCs in detecting colorectal cancer was evaluated by receiver operating characteristic (ROC) curve analysis for each VOC, followed by cross-validation by the leave-one-out method, and by applying stepwise logistic regression analysis.
Results: The study included 83 patients with colorectal cancer and 90 non-cancer controls. Fourteen VOCs were found to have significant discriminatory ability in detecting patients with colorectal cancer. The model with the diagnosis of cancer versus no cancer resulted in a statistically significant likelihood of discrimination of 173·45 (P < 0·001), with an area under the ROC curve of 0·979. Cross-validation of the model resulted in a true predictive value for colorectal cancer of 93 per cent overall. Reliability of the breath analysis was maintained irrespective of cancer stage.
Conclusion: This study demonstrated that analysis of exhaled VOCs can discriminate patients with colorectal cancer from those without. This finding may eventually lead to the creation of a smart online sensory device, capable of providing a binary answer (cancer/no cancer) and directing to further screening
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
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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