1,721,008 research outputs found
Cavitands As Selective Materials For Qmb Sensors For Nitrobenzene And Other Aromatic Vapors
No full textGrowing of Supramolecular Thin Films for Enviromental Monitoring
No full textGrowing of Supramolecular Thin Films for Enviromental Monitorin
Breath Test in Lung Cancer Patients
No full textThe Breath Test is based on the analysis of the exhaled breath which is largely composed of nitrogen, oxygen, carbon dioxide, water and inert gases. Trace components, volatile substances that are generated in the body or absorbed by the environment, present in the nmol/l-pmol/l range, make up the rest of the breath. The volatile compounds can be exogenous, originate from many solvents and petroleum based products; and endogenous, generated by the cellular biochemical processes of the body. There is a growing literature on the analysis of volatile organic compounds (VOCs) in the exhaled breath for the diagnosis of lung cancer.
Recently, gaseous chemical sensing and identification devices have been developed that are able to detect a single or patterns of odorant molecules such as VOCs.
These devices have used a variety of sensor arrays including conductive/nonconductive polymers, quartz microbalance sensors coated with metallo-porphirins, polymer coated surface acoustic wave devices. The premise with most of these systems is that absorption of gases onto the sensor system causes a change in the conductivity,mass,vibration, or color of the sensor, thus altering its’ output.
The systems generally consist of an array of sensors, which can be tuned to their task.
The composite output of the array requires multivariate statistical tecniques to analyze the patterns of output produced (a “smellprint”).
The sensitivities of these devices to various chemical groups and concentrations vary with the particular sensing technology
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
Molecular-level devices
No full textIn everyday life we make extensive use of macroscopic devices. A macroscopic device is an assembly of components designed to achieve a specific function. Each component of the device performs a simple act, while the entire device performs a more complex function, characteristic of the assembly. For example, the function performed by a hairdryer (production of hot wind) is the result of acts performed by a switch, a heater, and a fan, suitably connected by electric wires and assembled in an appropriate framework. The concept of device can be extended to the molecular level. A molecular–level device can be defined as an assembly of a discrete number of molecular components (that is, a supramolecular structure) designed to achieve a specific function. Each molecular component performs a single act, while the entire supramolecular structure performs a more complex function, which results from the cooperation of the various molecular components. The extension of the concept of device to the molecular level is of interest not only for basic research, but also for the growth of nanoscience and the development of nanotechnology [4]. Looking at supramolecular chemistry from the viewpoint of functions with references to devices of the macroscopic world is a very interesting exercise that helps the development of chemistry by introducing new concepts
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