1,721,115 research outputs found
Vantaggi ed inconvenienti dell'uso degli antibiotici a scopo profilattico e terapeutico negli allevamenti
No full textIncidenza degli anticorpi inibenti l'emoagglutinazione da Myxovirus Parainfluenza-3 nei sieri di persone della città di Napoli
No full textThermogravimetric technique for volatiles detection in planetary and space environments
Full text linkIntroduction. The PhD work has been performed at Institute of Astrophysics and Space Planetology (IAPS-INAF) in the framework of the two projects VISTA (Volatile In-Situ Thermogravimeter Analyser) and CAM (Contamination Assessment Microbalance), funded by Italian Space Agency and European Space Agency, respectively, both aiming at developing a microbalance sensor for space mission applications, i.e. to study the minor bodies of Solar System (i.e., ESA-M5 Missions Call, MarcoPolo-M5, Akon, JEM and Castalia) by measuring in-situ volatiles material of scientific interest (VISTA project) and to assess the contamination issue (CAM project).
VISTA is a miniaturized thermogravimeter (composed by Piezoelectric Crystal Microbalance and the related Proximity Electronics), based on Thermogravimetric Analysis (TGA), i.e. a widely used technique to monitor the processes involving compounds, i.e. absorption/desorption and evaporation/sublimation. Thanks to the variation in the microbalance oscillation frequency it is possible to estimate the sample mass loss/deposited from thermal cycles. VISTA is composed of two sensor heads, i.e. the Sensor Head 1 (SH1) for in-orbit contamination measurements from outgassing processes and Sensor Head 2 (SH2) for planetary in-situ measurements, respectively. The breadboard and the Engineering Model of VISTA SH1 have been developed for ESA Project, i.e. CAM, an Invitation to Tender of European Space Agency (EMITS-ESA) aiming at developing a thermogravimeter for contamination measurements in space, leaded by IAPS-INAF and developed by a consortium of three Italian institutes and one Industry. The VISTA SH2 breadboard has been developed in the framework of MarcoPolo-R Mission, where VISTA was part of the scientific payload.
Objectives. In this work, the VISTA capability to monitor the contamination processes in space environment and for the study of planetary surfaces and atmospheres has been demonstrated as well as the good capability of sensor heads to monitoring and to characterizing a contaminant source and organic compounds by realizing TGA cycles and Effusion Method (EM) to obtain the vapor pressures and enthalpy of sublimation.
Material and Method. The first phase of the work was based on the study of Volatile Organic Compounds (VOCs): 1) in planetary atmospheres including their physical-chemical properties and their connections with the atmospheric aerosol sources (biogenic and anthropogenic); 2) in space, coming from outgassing processes of materials exposed to space environment, and the related instrumentation issues. Thus, organic compounds (found in Carbonaceous Chondrite meteorites and in Earth's VOCs) have been selected to perform deposition processes and TGA cycles obtaining a complete characterization with SH1 and SH2. The vapor pressures and enthalpy of sublimation were identified as those thermochemical parameters able to characterize a kinetics process regarding VOCs in planetary atmosphere and in space. Thus, a laboratory activity was planned and divided in a first design and development phase of two laboratory setup and in a second calibration phase of VISTA sensor heads. A third phase was devoted at performing different tests for contamination study in space (using a contaminant source and SH1 breadboard) and for VOCs characterization in atmosphere (using five dicarboxylic acids and SH2 breadboard). Results. The breadboards of VISTA instrument SH1 and SH2 have been developed to monitor the contamination in space (SH1) and to characterize organic compounds (SH2). The main results reached in the PhD work with VISTA SH1 have been: 1) to monitor contamination processes in vacuum chamber simulating the space environment (between 5x10-9 to 7x10-4 g/cm2); 2) the contaminant source characterization by means of TGA cycles (ΔTmax~60°C) and retrieval of vapour pressure of compounds (Pi) and the enthalpy of sublimation (ΔHsub) by using the Langmuir and Clausius-Clapeyron relations; 3) the sensor regeneration by means of thermal cycles by using the integrated heaters on crystal surface (with an accuracy within 0.1°C). On the other hand, the main scientific objectives reached with VISTA SH2 have been: 1) the volatiles material measurement deposited on the sensor surface at different temperatures by using the Effusion Method simulating the asteroidal/cometary environment; 2) the characterization of VOCs, i.e. dicarboxylic acids, by calculating the enthalpy of sublimation (ΔHsub) with Van't Hoff relation. Conclusion. In this work, the VISTA SH1 and SH2 Breadboards have been designed and developed as well as two different laboratory set-up to verify the capability of SH1 and SH2 to monitor a contamination process and to characterize a pure organic compound, respectively, using TGA cycles and EM. The enthalpies of sublimation results obtained with SH1 from one contaminant source (adipic acid) using TGA and EM, are in agreement within 3.5% while the enthalpies of sublimation obtained for five dicarboxylic acids and using EM, are in agreement within 6% (oxalic, succinic and adipic acids) and 11% (azelaic and suberic acids) with previous works. These results demonstrate the capability of SH1 and SH2 Breadboards to detect organic contaminant and to characterize different organic compounds presents in VOCs terrestrial atmosphere obtaining a good characterization for a pure compound
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
- …
