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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
Computational analysis of gas-solid interactions in materials for energy storage and conversion
Get PDFDet vidtgående forbrug af fossile brændstoffer er skadeligt for klimaet og levestandarden for verdens befolkning pga. den globale opvarmning og forureningen det medfører. Verdens stigende energibehov, som resultat af forøgelsen i befolkningstallet og velstanden i specielt udviklingslandene, skal altså imødekommes af vedvarende energiproduktion. Vedvarende energikilder, såsom sol eller vindkraft, er ikke konstante og effektive metoder til at omdanne elektricitet til kemisk energi og derefter at lagre de energiholdige materialer er nødvendige.I denne afhandling bliver begge problemstillinger, konvertering og lagring, behandlet. Fokus er specifikt på undersøgelse af katalytiske materialer til elektrokemisk fiksering af CO2 i brændstoffer samt ammoniak lagringsmaterialer, vha. beregningsmæssige metoder byggende på tætheds funktional teori (DFT) and effektiv medie teori (EMT) samt en genetisk algoritme.Nanopartikler af binære legeringer er tidligere vist til at være katalytisk aktive i forbindelse med elektrokemisk fiksering af CO2. Stabiliteten af nanopartiklerne er kritisk for et katalytisk system. Vi har udviklet en metode til at bestemme struktur og sammensætning af nanopartikler under reaktive forhold. Denne metode involverer en genetisk algoritme til hvilken effektive forplantningsoperatorer er blevet udviklet og testet på kobber-nikkel legeringer. Algoritmen er i stand til at forudsige den struktur og sammensætning med den laveste energi for den mest stabile Cu-Ni støkiometri. Ved normale forhold i en ilt atmosfære er partikel overfladen karateriseret ved regioner af kobber i overfladen og regioner med nikkel i overfladen hvortil ilt adsorberer. Fremtidige studier vil forudsige hvilken kobber-nikkel støkiometri der skal til for at producere en katalytisk aktive sammensætning.Metalamin klorider f.eks. Mg(NH3)6Cl2 og Sr(NH3)8Cl2 kan fremvise høj energilagringskapacitet kombineret med hurtig kinetik. Vi har fastslået de termodynamisk stabile strontiumklorid amin faser, inklusive en diamin fase, Sr(NH3)2Cl2, som afhængigt af tryk og temperatur har en lidt højere eller lavere stabilitet i forhold til monoaminen, hvilket forklarer hvorfor diamin fasen kun bliver fundet i nogle eksperimenter. Vi har ydermere bestemt en stabil ammoniak overflade tilstand på SrCl2 aminer og klarlagt dens betydning for ab- og desorptions kinetikken.Metal salte binder ofte ammoniak og vand molekyler i lignende strukurelle koordineringer. Vi har undersøgt den konkurrerende udveksling og diffusionsprocesser for vand og ammoniak i magnesiumklorid hexamin og hexahydrat som en metode til ikke-termisk ammoniak frigivelse. En blandet fase indeholdende både vand og ammoniak er blevet vist til at være stabil i et lille interval omkring stuetemperatur.Det er muligt at skubbe frigivelsestermodynamikken i metalamin salte ved at blande to eller flere materialer, hvilket kan resultere i et blandet metalamin salt med overlegne egenskaber set i forhold til energiindhold og frigivelsestemperatur. Vi har brugt en genetisk algoritme til at forudsige flere stabile blandede metalaminer i model strukturer med frigivelsestemperaturer i et gunstigt område for anvendelser indenfor transportområdet.The extensive use of fossil fuels are harmful to the climate and the general standard of living due to global warming effects and pollution. Thus the rising energy needs in the World caused by an increase in both population and wealth especially in developing countries will have to be met by a renewable energy production. Sustainable energy sources such as solar or wind power are not constant and efficient methods firstly to convert electricity into chemical energy and secondly to store the high energy materials are needed.In this thesis both issues of conversion and storage are treated. The focus is specifically on the investigation of catalytic materials for electrochemical CO2 fixation into fuels as well as ammonia storage materials, using computational methods relying on density functional theory (DFT) and effective medium theory (EMT) calculations as well as a genetic algorithm.Nanoparticles of binary alloys have previously been shown to be catalytically active for electrochemical CO2 fixation. The stability of the nanoparticles is critical for a catalytic system. We have developed a method to determine the structure and composition of nanoparticles under reactive conditions. This method involves a genetic algorithm for which efficient propagation operators have been implemented and tested on the Cu-Ni alloy system. The algorithm is able to predict the lowest energy structure and composition for the most stable Cu-Ni stoichiometry. At standard conditions in an oxygen atmosphere the particle surface is characterized by regions of Cu atoms and regions of Ni atoms with adsorbed oxygen. Future studies will predict which Cu-Ni stoichiometry will produce a catalytically active particle composition.Metal ammine chlorides e.g. Mg(NH3)6Cl2 and Sr(NH3)8Cl2, can display high energy storage capacity combined with fast kinetics. We have determined the thermodynamically stable phases of strontium chloride ammines, including the diammine phase, Sr(NH3)2Cl2, that depending on temperature and pressure has a slightly higher or lower stability than the monoammine, explaining why the diammine is only found in certain experiments. We have furthermore determined a stable surface state of ammonia in SrCl2 ammines and identified its implications on the ab- and desorption kinetics.Metal salts often bind ammonia and water molecules in a similar structural coordination. We have studied the competitive exchange and diffusion processes of water and ammonia in magnesium chloride hexammine and hexahydrate as a method for non-thermal release of ammonia. A mixed phase containing both water and ammonia have been shown to be stable in a small region around room temperature.It is possible to shift the release thermodynamics in metal ammine salts by mixing two or more materials, resulting possibly in a mixed metal ammine salt with superior properties regarding energy content and release temperature. We have used a genetic algorithm to predict several stable mixed metal ammines in model structures with release temperatures in an attractive range for applications in the transport sector
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
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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