1,720,963 research outputs found
Gauge blocks measurements by mechanical comparison: aspects of the uncertainty budget through the analysis of an interlaboratory comparison
No full text"VOC and wall surface interactions in sampling lines: Experiment Design"
No full textPresentation in SESSION C. ANALYTICAL APPLICATIONS of GAS2015 about quantification of VOC losses due to wall interactions in sampling line
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
Development of a primary diffusion source of organic vapors for gas analyzer calibration
No full textVariations 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
Solid silica nanoparticles as carriers of fluorescent squaraine dyes in aqueous media: Toward a molecular engineering approach
Full text linkHybrid squaraine-SiO 2 nanoparticles extremely homogeneous in size (50 ± 2 nm), and with photoluminescent emission in the optical tissue window, were prepare by using the reverse microemulsion technique. Three different high quantum-yield squaraine dyes were used and the photophysical behavior of the prepared samples were qualitatively and quantitatively studied, by steady state and time-resolved photoluminescence, in order to establish structure-property relationships useful for the optimization of the preparation method. These squaraine dyes are insoluble in water and suffer a severe decrease of quantum yield if derivatized with polar groups. The role of the hydrophilicity of the dye-APTS adduct in ruling its dispersion in the nascent silica matrix was confirmed, and the possibility to improve the tuning of the process by properly administration of the adduct with the co-surfactant was demonstrated
Preparation of standard VOC mixtures for climate monitoring
No full textEuropean legislation regulates ambient concentrations of VOC key compounds relevant for indoor air monitoring and for air quality and climate monitoring programmes, e.g., the Global Atmosphere Watch (GAW) programme of the WMO. Data Quality Objectives refer to an expanded uncertainty lower than 10% for VOC measurement at concentration lower than 100 nmol/mol. Traceable and accurate standards and standardised dilution methods for VOC concentration are thus essential for the reliability and harmonisation of the measurement data provided. International research projects are ongoing to develop dynamic dilution systems from several sources (static cylinders and dynamic generation) to prepare standards at 1 - 100 nmol/mol VOC concentration with an uncertainty < 2-7 %. The uncertainty sources for VOC mixtures prepared by a single stage dynamic dilutor are here analyzed. Dilution flow rate, purity of the dilution gas, VOC losses and concentration variability due to imperfect gas mixing, wall-adsorption effects and leaks were considered as influence quantities. The dynamic dilutor performance was described by material balances on which a uncertainty budget was redacted. Mixing performances, wall interactions and leak tests were considered to design the dilutor. Design criteria for the dynamic dilutor and design specification for the air purification system were developed. This work contribute to develop standardized dilution methods for a better calibration of monitoring GAW instruments, it will helps to reduce uncertainty in climate change forecasting model
Cell elasticity change as a biomarker for cancer detection: An AFM metrological approach
No full textThe cancer diagnosis relies on morphological examination of human cells or tissue samples: This is considered the 'gold standard' for the diagnosis of malignancy in any organ system. However, diagnosis based on morphological examination can be difficult, recent studies recognized the cell elasticity changes as a marker for cancer detection. A metrological characterized AFM can be used to make reproducible elasticity measurements on biological samples. In this paper a method to accurately measure a cell elasticity change based on measurement of a stable and homogeneous material is proposed. Nanoindenter characteristics (nanoindenter with pyramidal tip and triangular shape) and indentation parameters (0.1 V as approaching point, 5 um/s as indentation speed and indentation load of 0.4 V) were found feasible for all tested samples. A modal cell elastic modulus of 0.5 kPa for lung tumor cell and a limit AFM measurement reproducibility of 4% was obtained
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