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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
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
The Potential of Clay Poultices as Sorbents for Medieval Plaster:A Comparative Study Using the Pressure Plate Method and Dye
No full textFive clay poultices used in built heritage, stone, and wall painting conservation were examinedfor their potential to extract impurities from medieval lime-rich wall painting plaster. Since themost efficient extraction is achieved by capillary advection, this evaluation compared the poresize distribution of the clay poultices with that of medieval plaster. The pore size distributionwas measured using the pressure plate method, a method with a long history of use in soil andbuilding science. The present study demonstrates for the first time a successful application ofthis method in the evaluation of clay poultices for conservation. In addition, the retentivecapacities of the five poultices were examined by measuring lateral migration andpenetration depths as a function of time, using customised plaster samples and a blue dyeto facilitate migration measurements. Of the five poultices, bentonite showed the leastpromising pore size range and was estimated to have little or no effect as a drying poulticefor medieval wall painting plaster. The remaining four poultices showed promising results,although with various shortcomings that might influence the results of the intervention, asthe best fit is dependent on the aim of the poulticing. For a cleaning poultice, where dirt isto be extracted solely from the surface of the plaster, attapulgite and PANGEL® S1500seemed to be best suited due to their high retention. The pore size distribution andmigration pattern of PANGEL® S9 and sepiolite indicated that they could be suitable aspoultices for desalination
Learning from the Past:Creating Reliable Replicas for Wall Painting Conservation Studies
No full textFør nye materialer og metoder tages i brug inden for konservering af kulturarvsgenstande, er det normal procedure først at efterprøve materialerne og metoderne på replikaer af de pågældende kulturarvsgenstande. Ved at benytte replikaer er det muligt at undersøge de nye materialer og metoders egenskaber og eventuelle skadelige virkninger i et kontrolleret miljø – helt uden risiko for de originale genstande. Det er dog essentielt for disse undersøgelsers relevans, at replikaerne har samme fysiske og kemiske egenskaber som de kulturarvsgenstande, de simulerer. Dette er især vigtigt, hvis man beskæftiger sig med porøse genstande såsom vægmalerier. I sådanne tilfælde har genstandens fysiske egenskaber, som for eksempel dens vandsugningsevne, en signifikant betydning for de resultater, der opnås ved konserveringsbehandlinger som eksempelvis afrensning og afsaltning. Hovedformålet med denne ph.d.-afhandling er at vise, hvorfor brugen af akkurate puds-replikaer er af største vigtighed for forskningen inden for vægmalerikonservering og tager udgangspunkt i den hvidtekalkede kalkpuds, der danner bund for de gotiske kalkmalerier i danske middelalderkirker. Afhandlingen er opdelt i tre sektioner. DEL I omfatter dels en undersøgelse af dansk, gotisk kalkpuds, dels et studie af hvorvidt det er muligt at genskabe den meget kalkrige middelalderpuds og dels en undersøgelse af ny-producerede replikaers mikrostrukturelle lighed med middelalderpuds (Artikel I-II). DEL II undersøger replikaernes vandopsugningsevner i forhold til middelalderpudsen. På baggrund af målinger af vandabsorptionshastighed granskes betydningen af henholdsvis bindemiddel/aggregat ratioen og hvidtekalken for replikaernes kapillære egenskaber (Artikel III). DEL III demonstrerer hvorfor forventede resultater af konserveringsindgreb potentielt set kan være forkerte, hvis der i konserveringsforsøgene er benyttet replikaer med en manglende mikrostrukturel lighed til den originale puds (Artikel IV). DEL I: Kompositionen og strukturen af dansk, gotisk kalkpuds blev bestemt med blandt andet følgende analysemetoder: Polarisationsmikroskopi, røntgen-diffraktionsanalyse, kviksølvs-porøsimetri og scannings-elektronmikroskopi. Disse analyser viser, at den kompakte, gotiske puds består af ikke-hydraulisk kalk og aggregater, og at pudsen er meget kalkrig, da det gennemsnitlige bindemiddel til aggregat ratio ligger på 2:1. I flere af prøverne findes desuden en stor andel af porøse kalkinklusioner. Prøverne har alle en høj, åben porøsitet med en unimodal porestørrelsesfordeling i poreområdet 0,4-5 μm. Ved brug af SEM-analyser ses det, at den gotiske puds består af en luftig matrix af små calcit-krystaller. I afhandlingen bliver det påvist, at den gotiske puds i de danske middelalderkirker højst sandsynligt blev produceret ved brug af varmlæsket mørtel – og ikke ved brug af kulekalksmørtel, som man hidtil har gået ud fra. Denne vurdering hviler dels på sammenligninger mellem mikrostrukturen af gotisk puds og mikrostrukturen af ny-fremstillede kalkpuds-replikaer – produceret af enten kulekalksmørtel eller af varmlæsket mørtel (læskemørtel). Derudover er vurderingen baseret dels på undersøgelser af historiske dokumenter, dels på nyere forskningsresultater og dels på praktiske betragtninger omkring mørtelfremstilling i middelalderen. I undersøgelsen af hvorvidt det i dag er muligt at fremstille en puds identisk med gotisk kalkpuds, blev graden af lighed mellem gotiske kalkpuds og replikaer undersøgt. Forskellige blandingsforhold og forskellige typer af hvidtekalk blev studeret med mikrostruktur og kapillære egenskaber som omdrejningspunkter. På baggrund af denne undersøgelse fastslås det, at det er muligt at rekonstruere dansk middelalderpuds i en tilfredsstillende grad. Afhandlingen viser, at de bedste matches til dansk gotisk puds, er replikaer udført af en varmlæsket mørtel blandet af én del brændt kalk til én del aggregat (1:1 replika). Bedste erstatning for den gotiske hvidtekalk, blev bestemt til at være en hvidtekalk fremstillet af en kulekalk lagret i mere end 67 år.DEL II: Studier af vandabsorptionshastighed ved brug af ’contact sponge’-metoden afslørede, at mens 1:1 replikaerne matchede middelalderpudsens vandabsorptionsevner, så viste replikaer produceret af én del kulekalk til tre dele aggregat (1:3 replika) et helt anderledes absorptionsmønster. I studiet sås det, at 1:3 pudsen opsuger vand 4-5 gange langsommere end den gotiske puds (og 1:1 replikaerne). Dermed kunne det også konstateres, at mørtelkompositionen på 1:3, som ellers ofte benyttes inden for konserveringsstudier af vægmaleri og arkitektur (og som reparationsmørtel), har meget lille lighed med dansk middelalderpuds. Dette tydeliggør, hvorfor brugen af unøjagtige replikaer kan være meget problematisk. Konserveringsforsøg, hvori der bruges replikaer med et lavere kalkindhold end den originale puds, kan ende med meget upræcise prognoser for udfaldet af konserveringsindgreb som for eksempel vådrensning. I sammenligning med 1:3 replikaerne vil den originale, gotiske puds absorbere væsentligt større mængder væske i samme givne tidsrum, og dermed vil der potentielt blive transporteret en større mængde rensevæske ind i den gotiske puds end forventet ud fra de indledende forsøg.DEL III: Vigtigheden af at benytte akkurate replikaer i konserveringsstudier understreges yderligere i DEL III set i forhold til kompatibel mikrostruktur og kapillære egenskaber. Det undersøges, hvorvidt forskellige lertyper er egnet som kompresmateriale til brug for konservering af dansk, gotisk puds. Lerkompressernes egnethed vurderes ud fra deres porestørrelsesfordeling sammenholdt med porestørrelsesfordelingen i middelalderpudsen (begge målt med ’pressure plate’-metoden) samt ud fra deres retentionsevne (målt ved migrationsmønstre aflæst ved hjælp af et blåt farvestof). Studiet demonstrerer, sammen med yderligere migrationsstudier præsenteret i afhandlingen, vigtigheden af at benytte replikaer med sammenlignelige egenskaber og med en porestørrelsesfordeling, der svarer til den man finder i den originale puds. Hvis replikaer med en mindre lighed benyttes, risikerer man, at der drages fejlagtige konklusioner på konserveringsstudier. Sådanne fejlbehæftede konklusioner gør i bedste fald indledende konserveringsundersøgelser mindre anvendelige for praktisk konservering. I værste fald gør de ligefrem skade, hvis de fejlagtige konklusioner betyder, at man implementerer potentielt set ødelæggende konserveringsbehandlinger.Afhandlingen viser, at det er muligt at kopiere mikrostrukturen af gotisk puds i en tilfredsstillende grad, og at de bedst egnede replikaer kan betragtes som pålidelige stand-ins for gotisk puds, da de viser nærved identiske vandopsugende egenskaber. Afhandlingen påviser imidlertid også forskelle i mikrostrukturen mellem de bedst egnede replikaer og middelalderpudsen. Derfor foreslår afhandlingen afslutningsvis ændringer for den fremtidige replika-produktion, så der dermed forhåbentligt kan opnås et endnu bedre match med middelalderpudsen. Disse forslag til ændringer inkorporerer den akkumulerede viden, der er opnået i løbet af dette ph.d.-forløb, og som er baseret på praktisk erfaring med replika-produktion, analyser af prøver og talrige litteraturstudier. Blandt de væsentligste forslag til forbedringer er følgende: At der bør bruges en større mængde kalk, benyttes brændt stykkalk frem for pulveriseret brændt kalk, at varmlæsketeknikken bør ændres fra våd-læskning til sandlæskning, og at udvælgelsen af basen til replikaerne bør fokusere på at finde et materiale med samme vandsugende egenskaber som de sten eller tegl, man finder som bund for dansk middelalderpuds. Alt imens ph.d.-afhandlingen fokuserer på at undersøge dansk, gotisk vægmaleripuds, genskabelsen af denne puds og betydningen af at bruge pålidelige replikaer til vægmalerikonserveringsstudier, inspirerede arbejdet med afhandlingen også til nye tanker om kalkmørtel og til ideer om fremtidige studier. For eksempel afslørede undersøgelserne af vandopsugningsevnen og den langt hurtigere vandsugningshastighed i puds med højt kalkindhold, at der er et presserende behov for en undersøgelse af den reparationsmørtel, der i dag anvendes til reparation af dansk, gotisk puds. Undersøgelserne viser tydeligt, at den 1:3 mørtel der i dag oftest benyttes ved arkitektur og vægmalerikonservering i Danmark, ikke følger grundprincipperne inden for konservering i forhold til brugen af reparationsmaterialer, der er kompatible og med samme egenskaber som de originale materialer. Da det er muligt, at brugen af mindre kalkrige reparationsmørtler som 1:3 kalkmørtlen har den konsekvens, at den primære del af fugttransporten i pudsen ledes igennem den originale puds, grundet dennes større vandabsorptionsevne, bør brugen af denne mørtel til reparationsarbejde på dansk, gotisk puds revurderes. Derudover viser afhandlingen, at der er et stort behov for yderligere undersøgelser af middelalderpuds, varmlæsket mørtel og den gotiske hvidtekalk og dennes genskabelse. Så der er ingen tvivl om, at der stadig er et stort arbejde tilbage, inden vi kan genskabe den hvidtekalkede, danske, gotiske puds til brug for replikaer og som reparationsmateriale. Using laboratory-produced replicas of cultural heritage objects to examine the benefits or possible detrimental effects of novel materials and methods before applying them to original objects is considered a fundamentally important procedure in the field of conservation. The use of replicas allows for the examination of methods and materials in a controlled environment and without risking any damage to the original cultural heritage objects. However, for these studies to be relevant, it is of utmost importance that the replicas match the chemical and physical characteristics of the original objects. This is of particular significance when working with porous objects such as wall paintings, where the physical properties, e.g., the hygric behaviour, can significantly influence the outcome of conservation procedures such as cleaning and desalination.The main objective of the present PhD dissertation is to show the importance of using accurate plaster replicas when conducting wall painting conservation research - with a particular focus on limewashed Danish medieval wall painting plaster from the Gothic period. The studies in the dissertation are divided into three sections. PART I examines the lime-rich plaster constituting the support for Gothic wall paintings in Denmark, presents an approach for the replication of this plaster and examines the replicas’ microstructural resemblance to the medieval limewashed plaster (Papers I-II). Part II examines the replicas’ hygric resemblance to medieval plaster and the influence of binder to aggregate ratio as well as type of limewash on hygric properties (Paper III). Part III demonstrates how the use of replicas with a low microstructural resemblance to the original plaster can result in inaccurate predictions of the outcome of conservation procedures (Paper IV).PART I: With the use of different analytical techniques such as polarisation microscopy, x-ray diffraction analysis, mercury intrusion porosimetry and scanning electron microscopy, the studies show that Danish medieval plaster has a compact structure consisting of a non-hydraulic lime binder and aggregates with an average ratio of 2:1, often with an abundance of lime inclusions. It has a high open porosity with a unimodal pore size distribution in the range of 0.4–5 μm and an airy lime matrix consisting of small calcite crystals. By comparing these analytical results with analyses of plaster produced from lime putty plaster and hot-mixed mortar, and supplementing information gleaned from these comparisons with historical documents, recent research studies and practical considerations, the studies of Danish medieval plaster also revealed that this plaster, with a high probability, was produced from hot-mixed mortar and not from lime putty mortar as commonly presumed. Replicas of different compositions were assessed for their resemblance to medieval plaster in terms of microporosity and hygric properties. This comparison established that it is possible to replicate the microstructure and the hygric properties of limewashed Gothic plaster to an acceptable degree. The best match to the medieval plaster was achieved in replicas produced from a hot-mixed mortar consisting of one part quicklime to one part aggregate. The best match to the Gothic limewash, characterised by its great thickness, was achieved by a limewash produced from a more than 67-year-old lime putty.PART II: Measurements of water absorption rate by the contact sponge method revealed that while 1:1 hot-mixed replicas were a good match to medieval plaster in terms of hygric behaviour, replicas made from a mortar mix of one part lime putty to three parts aggregate were, on the contrary, a poor match. The studies showed that replicas made from this often-used mortar composition (for wall painting and built heritage studies) have little resemblance to that of lime-rich medieval plaster, as they absorb water at a four to five times slower rate than medieval plaster. This exemplifies why the use of inaccurate replicas can be very problematic. The predictability of the outcome of a test procedure involving wet cleaning, for example, will be very skewed if using replicas with a lower lime content than the original plaster. A more lime-rich plaster will absorb substantially greater amounts of liquid in the same given time period than less lime-rich plaster, thus potentially transporting a larger volume of cleaning agents into the plaster than expected.PART III. The importance of using accurate replicas in terms of compatible microstructure and hygric properties is further supported in Part III by a study examining five clay poultices’ suitability as sorbents applied to medieval wall painting plaster. The study compares the pore size distribution of the medieval plaster with that of the wet/drying clay poultices (measured by pressure plate) and measures migration of liquid from the clay poultices into the plaster, documented with the help of blue dye. The immense importance of the compatibility between the medieval plaster and the replicas in terms of pore size distribution and hygric behaviour was shown. This study, together with additional migration studies presented in the dissertation, once again demonstrate that using replicas with low resemblance to the original plaster involves the risk of drawing erroneous conclusions in conservation studies. Such studies will thereby lack relevance due to their imprecise predictions or, at worst, can result in the implementation of harmful conservation treatments.Although the studies showed that it is possible to replicate the microstructure and the hygric properties of Gothic plaster to an acceptable degree, and that the best-suited replicas, confirmed by the experiments on hygric behaviour, could be considered reliable stand-ins for medieval plaster, differences were also detected in the microstructure of the best-suited replicas and the medieval plaster. Therefore, the dissertation also provides suggestions for future replica productions, aiming to improve the match to medieval plaster. These suggestions embody the accumulated knowledge obtained in the course of this PhD and are based on practical experience in replica production, analyses of samples and numerous literature studies. Among the most significant suggestions for improvements are the following: using a larger volume of lime, using lump quicklime instead of powdered quicklime, changing the hot-mixing technique from wet-slake to sand-slake and prioritising a careful selection of the substrate for the replicas (to ensure correct hygric behaviour).While the studies in the PhD dissertation set out to examine Danish Gothic wall painting plaster, its replication and the significance of using reliable replicas for wall painting conservation studies, they also inspired new ideas for future studies. For example, the studies on the hygric properties of plaster revealed a need for a study on the repair mortar used for lime-rich plaster in wall painting and built heritage conservation. Especially in light of the fact that the studies in this dissertation clearly showed that the use of 1:3 mortar, which is the most common mortar composition used for repair mortar in wall painting conservation in Denmark, does not comply with the principal tenets of modern conservation regarding compatibility and the use of like-for-like materials for repair and reconstruction work when dealing with lime-rich medieval plaster. Hence, the use of this mortar for repair work on Danish Gothic plaster should be re-evaluated. <br/
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
Measuring Water Absorption in Replicas of Medieval Plaster Assessing their Reliability as Models for Conservation Trials
No full textUsing reconstructions or laboratory models in wall painting conservation research requires sufficient chemical and physical resemblance to the original object to make the tests on the models relevant. This study applies the contact sponge method comparing the water absorption rate of limewashed medieval wall painting plaster with replicated mortar samples of varying binder-to-aggregate ratios produced by the hot-mix technique and with lime putty mortar. Different types of limewashes are also examined. Based on this comparison, the study evaluates the samples’ suitability as models for wall painting conservation research. Moreover, the study explores the validity of the contact sponge method for measuring highly porous mortars.The experiment demonstrates that the contact sponge method can be used for measuring the water absorption rate of highly porous mortar samples, and that the fastest water absorption rates are found in the mortar samples with the highest lime content. Moreover, the closer the sample’s binder-to-aggregate ratio is to the historical plaster, the more similar the values are. The poorest correlations are found for lime putty mortar samples with a 1:3 ratio heretofore used in conservation trials. Furthermore, the absorption rate is significantly influenced by the type of limewash on the samples
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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