1,720,959 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
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
Mathematical model of aldol addition of dihydroxyacetone to N-Cbz-glycinal in the batch reactor
Get PDFU radu je opisana reakcija aldolne adicije dihidroksiacetona na N-Cbz-glicinal u kotlastom reaktoru koja je katalizirana s D-fruktoza-6-fosfat aldolazom (FSA) dobivenom iz E. coli. Ispitana su tri potencijalna enzima kao katalizatora ove reakcije: FSA A129S, FSA A129S/A165G i FSA A129N. Odabran je enzim FSA A129N koji je dao najveću konverziju reaktanta u najkraćem vremenu u reakciji aldolne adicije. Kinetika ove reakcije je ispitana metodom početnih reakcijskih brzina. Ispitan je utjecaj komponenti reakcijskog sustava na početnu brzinu reakcije. Na temelju procijenjenih kinetičkih parametara i sheme reakcije razvijen je matematički model procesa u kotlastom reaktoru. U provedenim reakcijama aldolne adicije dihidroksiacetona na N-Cbz-glicinal u kotlastom reaktoru postignuta je maksimalna konverzija od 88%.This work deals with the reaction of aldol addition of dihydroxyacetone on N-Cbz-glycinal catalyzed by D-fructose-6-phosphate aldolase (an enzyme produced by E. coli) in the batch reactor. Three potential enymes were tested as catalysts for this reaction: FSA A129S, FSA A129S/A165G and FSA A129N. The chosen enzyme was the one that gave the best conversion in the shortest time in the reaction of aldol addition. The reaction kinetics were tested with the initial reaction rate method. The influence of the reaction components on the initial reaction rate is also presented in this work. The mathematical model of the process was developed on the basis of reaction scheme and estimated kinetic parameters. The maximum achieved conversion in the conducted experiments of aldol additions of dihydroxyacetone on N-Cbz-glycinal in the batch reactor was 88%
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
Relevant aspects of integrated RES systems
No full textU ovome diplomskom radu obrađuje se tema relevantnih aspekata integriranog sustava obnovljivih izvora energije koji uključuje integraciju reverzibilne hidroelektrane (RHE) i sustava fotonaponskih kolektora (PV). Integracija je potrebna kako bi se nadomjestili tehnološki i energetski nedostaci pojedinačnih neintegriranih sustava (sustavi koji koriste energiju vjetra, solarnu energiju) kao što su interminiranost i stohastičnost proizvodnje električne energije. Obrađuju se sve sastavnice ovog integriranog sustava, njihove pojedinosti, njihova integracija, te i problematika skladištenja energije. Provedeno je svojevrsno početno projektiranje i dimenzioniranje sustava na odabranoj stvarnoj lokaciji na otoku Visu. Sustav je dimenzioniran i projektiran prema jedinim dostupnim podacima za potrošnju električne energije za otok Vis iz 2007. godine. Dobivena potrebna snaga iznosi 25.1 MW u koju su uračunati potrebni viškovi (+50% od potrebne) zbog energetskih gubitaka, mogućnosti budućih proširenja postrojenja i rasta energetske potražnje. Dobivena je i površina fotonaponskih kolektora od 156875 m^2 i volumen spremnika vode koji iznosi 3,8 hm^3. Ovakav sustav proizvodnje električne energije koji proizvodi električnu energiju za realnu primjenu isključivo iz obnovljivih izvora energije, bez nedostataka koji imaju „klasični“ pojedinačni neintegrirani sustavi obnovljivih izvora energije (energija sunca, vjetra itd.), mogao bi otok Vis učiniti energetski neovisnim o kopnu.This thesis is covering the subject of relevant aspects of integrated renewable energy sources (RES) systems which include the integration of pumped storage hydroelectric (PSH) and photovoltaic systems (PV). This particular integration is needed to supersede the technological and energetic shortcomings of singular (individual) unintegrated systems (like wind or solar energy systems) which are intermittency and stochasticity of electric energy production. In the thesis the components of this integrated system are individually covered including their particular details, the way they are integrated into the system as a whole, and the issue of energy storage. Preliminary projecting and sizing was conducted for a real life location on the island Vis using the only available electric energy consumption data from the year 2007. The calculated required power production capacity is 25.1 MW which includes an extra of +50% power because of energy losses, future system expansions and the growth of energy demand. The required surface of the PV and the volume of the reservoir have been also calculated and they are 156875 m^2 and 3.8 hm^3. An energy production system, like this one, which produces energy only from RES, without the limitations of “usual” individual unintegrated RES systems would make the island Vis energetically independent from the coast
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
Synthesis and application of nanostructured titania thin films and their composites with barium titanate
No full textU ovom doktorskom radu istražen je utjecaj uvjeta pripreme na strukturna i optoelektrična svojstva tankih filmova usmjerenih nanocjevčica titanijeva dioksida i kompozita s barijevim titanatom, te optimizacija njihovih svojstva za primjenu u fotokatalizi i kao slojevi za prijenos elektrona u perovskitnim solarnim ćelijama. Kombinacijom fizikalnih i kemijskih sintetskih metoda, te optimizacijom uvjeta sinteze pripremili su se homogeni, transparentni tankoslojni uzorci nanocjevčica s optimalnom širinom i duljinom pora. U prvom koraku metodom magnetronskog rasprašenja najprije su naneseni tanki filmovi titanija na podlogu stakla prekrivenog prozirnim vodljivim oksidom. U drugom koraku elektrokemijskom anodizacijom slojeva titanija i naknadnom termalnom obradom pripremljeni su tanki filmovi vertikalno usmjerenih nanocjevčica titanijeva dioksida. U trećem koraku ispitala se priprema kompozitnih materijala nanocjevčica s barijevim titanatom hidrotermalnom sintezom, rotacijskim oblaganjem otopina barijevog hidroksida, sol-gel sintezom i magnetronskim rasprašivanjem. Uvjeti pripreme kao npr. trajanje depozicije titanijeva sloja magnetronskim rasprašenjem, sastav elektrolita i napon kod elektrokemijske anodizacije, koncentracija otopina prekursora mijenjani su u širokom rasponu i detaljno je analiziran njihov utjecaj na svojstva tankih filmova nanocjevčica titanijeva dioksida. Sol-gel sinteza i magnetronsko rasprašivanje barijevog titanata pokazale su se neprikladnima za sintezu slojeva barijevog titanata na titanijevom dioksidu budući da je za kristalizaciju tih slojeva potrebna previsoka temperaturna obrada koja bi narušila strukturna, optička i električna svojstva titanijeva dioksida i podloge. U doktorskom radu pokazano je da čiste, odnosno nemodificirane nanocjevčice imaju veliki potencijal za primjenu u fotokatalizi, pogotovo u slučaju razgradnje diklofenaka. Efikasnost fotokatalize ispitivala se praćenjem promjene koncentracije onečišćujuće tvari diklofenaka u vremenu. Modificiranjem rotacijskim oblaganjem površine nanocjevčica s barijevim hidroksidom uzrokovalo je povećanje efikasnosti fotokatalize za 28 % što je rezultiralo fotokatalitičkom razgradnjom ≈ 90 % diklofenaka unutar 60 min. Međutim pripremom kompozitnog materijala hidrotermalnom reakcijom rezultiralo je smanjenjem efikasnosti fotokatalize uslijed narušavanja optičkih i električnih svojstava nanocjevčica i smanjivanja specifične površine nanocjevčica titanijeva dioksida nastankom sloja barijevog titanata. Tanki filmovi nanocjevčica titanijeva dioksida su također uspješno primijenjeni kao sloj za prijenos elektrona u perovskitnim solarnim ćelijama sa standardnom konfiguracijom. Pri tome je najveća postignuta efikasnost konverzije perovskitnih solarnih ćelija s ugrađenim slojem nanocjevčica titanijeva dioksida iznosila 13,5 %. Za daljnje poboljšanje efikasnosti solarnih ćelija potrebno je provesti optimizaciju i ostalih slojeva perovskitne solarne ćelije, što prelazi okvire ovog doktorskog rada i predmet je budućih istraživanja. Kompozitni slojevi pripremljeni u sklopu ovog doktorskog rada su se također ispitali za primjenu u perovskitnim solarnim ćelijama kao slojevi za prijenos elektrona. Korištenje kompozitnog materijala pripremljenog hidrotermalnom reakcijom rezultiralo je smanjenjem efikasnosti i padom parametara solarnih ćelija uslijed smanjenja specifične površine pokrivanjem pora nanocjevčica, rasta električnog otpora i smanjenja transmisije rastom sloja barijevog titanata. Zaključno, tanki filmovi titanatnih nanocjevčica pripremljeni u sklopu ovog doktorskog rada imaju veliki potencijal za daljnji razvoj i primjenu, pogotovo u području primjene sunčeve energije kao npr. za fotokatalizu i solarne ćelije. Međutim, kompozitni materijali barijevog titanata i tankih filmova vertikalno usmjerenih nanocjevčica zahtijevaju daljnja detaljna istraživanja te optimizaciju svojstava i postupaka pripreme kako bi bili uspješno iskorišteni u raznim primjenama.This doctoral dissertation investigates the influences of different preparation conditions on structural and optoelectrical properties of vertically oriented titania nanotube thin films and their composites with barium titanate, and also the optimisation of the materials’ properties for uses in photocatalysis and as electron transport layers in perovskite solar cells. Transparent thin film titania nanotubes with optimal pore length and thickness were prepared by implementing optimised physical and chemical methods of synthesis. Using magnetron sputtering, titanium thin films were deposited onto conductive oxide glass substrates. The titanium thin films were converted into vertically oriented titania nanotube thin films through electrochemical anodization followed by thermal annealing. In the last step, the composite materials were prepared by hydrothermal reactions, by spin coating barium hydroxide solutions or sol-gel mixtures, and by magnetron sputtering of barium titanate targets. The preparation conditions (e.g. sputtering duration of titanium thin films, electrolyte composition, anodization voltage, barium titanate precursor concentration) have been varied in a wide range and their influence on the properties of the titania nanotube thin films has been thoroughly analysed. Sol-gel and magnetron sputtering methods used for depositing barium titanate films have been proven to be incompatible because of the necessary high temperature processing needed to prepare crystalline barium titanate which would be detrimental to the structural, optical and electrical properties of titanium dioxide and the substrate. In this doctoral dissertation it has been shown that pure, unmodified titania nanotube thin films have great potential in photocatalysis, especially in the case of diclofenac degradation. Photocatalytic degradation has been investigated by tracking the change in diclofenac concentration during photocatalysis experiments. Composite materials prepared by spin coating solutions of barium hydroxide resulted in an increase in photocatalysis rates by 28 % and with the degradation of ≈ 90 % diclofenac under 60 min. However, the composite materials prepared by hydrothermal reactions with barium hydroxide showed a decrease in photocatalytic capabilities due to negative effects on optical and electrical properties of the nanotubes and due to the decrease in the specific surface of the nanotubes with the growth of the barium titanate layer. Titania nanotube thin films were also successfully implemented as an electron transport layer in perovskite solar cells with a standard layer configuration. The highest obtained solar conversion efficiency was 13,5 % for the solar cells containing titania nanotube thin films. To further increase the efficiency of the perovskite solar cells it would require the optimization of other layers which is above the scope of this dissertation, and will be investigated in future research. However, implementing composite electron transport layers in the perovskite solar cells showed a decrease in solar energy conversion efficiencies and solar cell parameters due to the coverage of nanotube pores with barium titanate, increases in electrical resistance, and decreases in transmittances correlated with the growth of the barium titanate layer. Overall, this transparent thin film nanotube technology is a promising new material with great potential for future uses and technological improvements, especially in the field of solar energy conversion such as photocatalysis and solar cells. On the other hand, the barium titanate and vertically oriented titania nanotube composite material requires further detailed research and optimization to fine-tune its properties to be successfully implemented in different use cases
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