1,720,967 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Studies of reactions of ions with water molecules in the gaseous phase for trace gas analysis
No full textChemical ionization mass spectrometry (CI-MS) is a powerful analytical technique, capable to detect trace levels of organic molecules diluted in air samples in real-time. Processes leading to ionization of organic molecules, necessary for their detection and identification, are however often strongly affected by the presence of water vapours in form of sample humidity. In the present work, I studied the influence of water vapours on ion chemistry and, subsequently, the respective influence on sensitivity and selectivity of CI-MS techniques. Studies were carried out using several soft chemical ionization mass spectrometry instruments, including Selected Ion Flow Tube Mass Spectrometry (SIFT-MS), Proton Transfer Reaction Mass Spectrometry (PTR-MS) and Selected Ion Flow-Drift Tube Mass Spectrometry (SIFDT-MS). Experimental studies were also supplemented by theoretical simulation of proposed ion chemistry using the Kinetic of Ion-Molecular Interaction simulator (KIMI), developed by the author. In this thesis, I present a study of formaldehyde, glyoxal and phthalates ion chemistry with H3O+ , NO+ and O2 + reagent ions, focusing on secondary reactions with water vapours. Additionally, I also studied secondary reactions of protonated hydrated acetic acid with acetone. Finally, I have carried out..
Variations on the Author
Get PDF“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
Get PDFWe 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
Studium reakcí iontů s molekulami vody v plynné fázi pro stopovou analýzu
No full textChemical ionization mass spectrometry (CI-MS) is a powerful analytical technique, capable to detect trace levels of organic molecules diluted in air samples in real-time. Processes leading to ionization of organic molecules, necessary for their detection and identification, are however often strongly affected by the presence of water vapours in form of sample humidity. In the present work, I studied the influence of water vapours on ion chemistry and, subsequently, the respective influence on sensitivity and selectivity of CI-MS techniques. Studies were carried out using several soft chemical ionization mass spectrometry instruments, including Selected Ion Flow Tube Mass Spectrometry (SIFT-MS), Proton Transfer Reaction Mass Spectrometry (PTR-MS) and Selected Ion Flow-Drift Tube Mass Spectrometry (SIFDT-MS). Experimental studies were also supplemented by theoretical simulation of proposed ion chemistry using the Kinetic of Ion-Molecular Interaction simulator (KIMI), developed by the author. In this thesis, I present a study of formaldehyde, glyoxal and phthalates ion chemistry with H3O+ , NO+ and O2 + reagent ions, focusing on secondary reactions with water vapours. Additionally, I also studied secondary reactions of protonated hydrated acetic acid with acetone. Finally, I have carried out...Metoda hmotnostní spektrometrie pomocí chemické ionizace je účinná analytická technika, umožňující detekovat v reálném čase stopová množství organických těkavých látek přítomné ve vzduchu. Procesy vedoucí k ionizaci organických molekul, nutné k jejich detekci a následnou identifikaci, jsou bohužel často ovlivněné přítomností vodní páry. V představené práci jsem studoval vliv vodní páry na chemii iontů a její následní vliv na citlivost a selektivitu metod hmotnostní spektrometrie pomocí chemické ionizace. Pro studium jsme využili několik hmotnostně-spektrometrických přístrojů, mimo jiné techniku hmotnostní spektrometrie v proudové trubici s vybranými ionty (SIFT-MS), techniku hmotnostní spektrometre pomocí reakce přenosu protonu (PTR-MS) a techniku hmotnostní spektrometrie v proudově-driftové trubice s vybranými ionty (SIFDT-MS). Experimentální stude je doplněná teoretickými simulacemi studovaných procesů pomocí autorem vytvořeným simulačním programem KIMI. V disertační práci prezentuji výsledky zkoumání iontové chemie molekul formaldehydu, glyoxalu a ftalátů pomocí H3O+ , NO+ and O2 + reakčních iontů, přičemž se zaměřuji na pochopení sekundárních reakci iontových produktů s vodní párou. Následně jsem také studoval sekundární reakce protonovaných a hydratovaných molekul kyseliny mravenčí s...Department of Surface and Plasma ScienceKatedra fyziky povrchů a plazmatuFaculty of Mathematics and PhysicsMatematicko-fyzikální fakult
Studium reakcí iontů s molekulami vody v plynné fázi pro stopovou analýzu
Get PDFChemical ionization mass spectrometry (CI-MS) is a powerful analytical technique, capable to detect trace levels of organic molecules diluted in air samples in real-time. Processes leading to ionization of organic molecules, necessary for their detection and identification, are however often strongly affected by the presence of water vapours in form of sample humidity. In the present work, I studied the influence of water vapours on ion chemistry and, subsequently, the respective influence on sensitivity and selectivity of CI-MS techniques. Studies were carried out using several soft chemical ionization mass spectrometry instruments, including Selected Ion Flow Tube Mass Spectrometry (SIFT-MS), Proton Transfer Reaction Mass Spectrometry (PTR-MS) and Selected Ion Flow-Drift Tube Mass Spectrometry (SIFDT-MS). Experimental studies were also supplemented by theoretical simulation of proposed ion chemistry using the Kinetic of Ion-Molecular Interaction simulator (KIMI), developed by the author. In this thesis, I present a study of formaldehyde, glyoxal and phthalates ion chemistry with H3O+ , NO+ and O2 + reagent ions, focusing on secondary reactions with water vapours. Additionally, I also studied secondary reactions of protonated hydrated acetic acid with acetone. Finally, I have carried out...Metoda hmotnostní spektrometrie pomocí chemické ionizace je účinná analytická technika, umožňující detekovat v reálném čase stopová množství organických těkavých látek přítomné ve vzduchu. Procesy vedoucí k ionizaci organických molekul, nutné k jejich detekci a následnou identifikaci, jsou bohužel často ovlivněné přítomností vodní páry. V představené práci jsem studoval vliv vodní páry na chemii iontů a její následní vliv na citlivost a selektivitu metod hmotnostní spektrometrie pomocí chemické ionizace. Pro studium jsme využili několik hmotnostně-spektrometrických přístrojů, mimo jiné techniku hmotnostní spektrometrie v proudové trubici s vybranými ionty (SIFT-MS), techniku hmotnostní spektrometre pomocí reakce přenosu protonu (PTR-MS) a techniku hmotnostní spektrometrie v proudově-driftové trubice s vybranými ionty (SIFDT-MS). Experimentální stude je doplněná teoretickými simulacemi studovaných procesů pomocí autorem vytvořeným simulačním programem KIMI. V disertační práci prezentuji výsledky zkoumání iontové chemie molekul formaldehydu, glyoxalu a ftalátů pomocí H3O+ , NO+ and O2 + reakčních iontů, přičemž se zaměřuji na pochopení sekundárních reakci iontových produktů s vodní párou. Následně jsem také studoval sekundární reakce protonovaných a hydratovaných molekul kyseliny mravenčí s...Faculty of Mathematics and PhysicsMatematicko-fyzikální fakult
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
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