1,720,984 research outputs found
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
Development of Activated Carbon Web from Acrylic Fibrous Waste
No full textAktivní uhlíková vlákna získala značnou pozornost v posledních desetiletích v důsledku mimořádných adsorpčních vlastností vůči těžkým kovům, toxickým plynům, barvivům a dalším nebezpečným chemikáliím. Vedle vysoké adsorpční kapacity jsou hnací sílou vývoje aktivních uhlíkatých vláken také aplikace proti tepelnému, elektrickému a elektromagnetickému stínění. Různé prekurzory používané pro přípravu těchto vláken jsou na celulózové bázi, bázi polyakrylonitrilu, dehtu, polyimidu, fenolových pryskyřic a polyetylenu. Výzkumní pracovníci se věnují hledání různých materiálů a metod pro snížení nákladů na aktivní uhlíková vlákna. V této práci je využíván odpad akrylových vláken společně s novou metodou jednostupňové karbonizace a fyzikální aktivace pod vrstvou dřevěného uhlí. Pro přeměnu vstupního materiálu na aktivní uhlíkové vlákno je vstupní materiál stabilizován a následně karbonizován při vysoké teplotě. Rychlost ohřevu, čas prodlevy a konečná teplota pyrolýzy hrají významnou roli v získání požadovaných hodnot elektrické vodivosti (povrchová a objemová vodivost), lepší účinnosti elektromagnetického stínění (ESE) a relativní plochy povrchu. Tato pracovní optimalizace parametrů pro získání větší plochy povrchu a elektrické vodivosti byla realizována s měnícím se počtem kroků, časy prodlevy (0, 30 a 60 minut), rychlostmi ohřevu (150, 300 a 400 °C/hod) a konečnými teplotami pyrolýzy (800, 1000 a 1200 °C). Bylo zjištěno, že rychlost ohřevu 300 °C/hod, čas prodlevy 0 minut a finální teplota pyrolýzy 1200 °C s dvoufázovým postupem jsou optimální parametry pro získání dobré plochy povrchu a elektrické vodivosti. Později byl odpad z akrylových vláken přeměněn na kompaktní struktury netkaných pásů pomocí mykání a vpichováním. Netkané pásy byly převedeny vysokými teplotami pece po stabilizaci a karbonizaci na finální parametry. Výtěžek a smrštění aktivních uhlíkových pásů při různých teplotách byl zjišťován pomocí měření hmotnosti před a po karbonizaci a změny rozměrů byly zjišťovány rovněž před a po karbonizaci. Podobně flexibilita nebo tuhost a prášivost aktivních uhlíkových pásů byly měřeny podle principů měření Cantilever testem a odíráním pásů proti opotřebí Taber Wear and Abrasion Testerem. Povrchová morfologie a chemická struktura aktivních uhlíkových pásů byla měřena pomocí rastrovacího elektronového mikroskopu (SEM), energetické disperzní rentgenové mikroskopie (EDX), rentgenové difrakce (XRD) a metodou izotermy Brunauer-Emmet-Teller (BET). Elektrická vodivost a účinnost elektromagnetického stínění aktivních uhlíkových pásů byla stanovena pomocí paralelní a soustředné elektrody a pomocí metody coaxial transmission line. Ukázalo se, že v důsledku vyšší orientace řetězců, kompaktnosti řetězců a vyššímu obsahu krystalinity při vyšší teplotě pás připravený při vysoké teplotě dává lepší výsledky elektrické vodivosti a účinnosti stínění. Adsorpční schopnosti aktivních uhlíkových pásů stejně jako železem impregnovaných aktivních uhlíkových pásů byly stanoveny adsorpcí použitím metylenové modři při různých parametrech jako například různé koncentrace barviva, adsorpční dávce, rychlosti míchání či pH. Výsledky byly ověřeny pomocí adsorpčních izoterm (Freundlichova a Langmuirova) a reakční kinetiky (pseudo-prvního a druhého řádu).Activated carbon fibers have gained significant attention since the last decade due to their extra-ordinary adsorption characteristics towards heavy metals, different poisonous gases, dyes and other hazardous chemicals. Besides high adsorption capacity, the thermal and electrical conductive properties of activated carbon fibers are driving forces towards thermal, electrical and electromagnetic shielding applications. Different precursors used for formation of activated carbon fibers are cellulosic based, polyacrylonitrile, pitch based, polyimides, phenolic resins and polyethylene based materials. However, researchers are inquest to find out different precursor materials and methods for reducing the cost of activated carbon fibers. In this context, use of acrylic fibrous waste together with a novel method of single stage carbonization and activation by using physical activation under the layer of charcoal was explored in this study. For converting precursor material into activated carbon fiber, firstly the material was stabilized then carbonized at high temperature. Heating rate, holding time and final pyrolysis temperature played very important role in getting good values of electrical conductivity (surface and volume conductivity), better electromagnetic shielding effectiveness (ESE) and surface area. In this work optimization of parameters for getting higher surface area and electrical conductivity has been achieved by varying number of steps, holding time (0, 30 and 60 minutes), heating rate (150, 300 and 450 C hr-1) and final pyrolysis temperature (800, 1000 and 1200 C). It was found that heating rate 300 C hr-1 , holding time zero minute, final pyrolysis temperature 1200 C with two step approach were the optimized parameters for getting good surface area and electrical conductivity. Later the waste of acrylic fibers was converted into a compact structure of non-woven web by using roller carding and needle punching machine. The non-woven web was transferred to high temperature furnace for stabilization and carbonization on parameters finalized. The yield and shrinkage of activated carbon webs prepared at different temperatures were determined by measuring weight and change in dimensions before and after carbonization respectively. Likewise the flexibility or stiffness and dusting properties of activated carbon webs was measured by following the principle of cantilever bending and by rubbing the web on taber wear and tester. The surface morphology and chemical characterization of activated carbon webs was measured by using Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) and Brunauer emmett teller (BET). The electrical conductivity and electromagnetic shielding effectiveness of AC webs was determined by using parallel electrode and concentric electrode and by using wave guide method and coaxial transmission line method. It showed that due to more orientation of chains, crystallinity, compactness of chains and higher crystalline content at higher temperature, the web prepared at high temperature gave better results of electrical conductivity and shielding effectiveness. The adsorption performance of AC web as well as iron impregnated AC web was checked by using methylene blue at different parameters like different concentrations of dye, adsorbent dosage, stirring speed and pH. Later the results were verified by using adsorption isotherms (Freundlich and Langmuir) and kinetics (pseudo 1st and 2nd order) of reaction. It was found that metal impregnation increased surface area hence more adsorption of dye molecules
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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
- …
