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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
Kapljični mikroresonatorji za preučevanje mehkih in bioloških sistemov
No full textDroplet microresonators can support whispering gallery mode (WGM) optical resonances, which are highly dependent on the size and shape of the droplet. Even small perturbations in these two parameters cause distinct changes in the droplet\u27s WGM spectra, providing a precise optomechanical sensing platform. Relying on the spectroscopy of WGMs we developed WGM tensiometry, a method for measuring interfacial tension (IFT) of the interface between the droplet microresonator and the surrounding liquid, and WGM elastometry, a method for measuring local stress and Young\u27s modulus of a soft matrix surrounding the droplet.
WGM tensiometry involves generating a dye-doped microdroplet of an optically clear liquid attached to the end of a glass microcapillary that can support WGMs while submerged in an immiscible continuous liquid phase. The size changes of the droplet are monitored via WGMs while applying finely tunable pressure through the microcapillary. The IFT is determined from the droplet size and the equilibrium pressure. This method allows the use of droplets as small as 8μm, requiring minimal sample volumes. Compared to other tensiometry methods, WGM tensiometry does not require the densities of the two liquids to be known in advance. Additionally, IFT measurements can be performed in non-equilibrium states when the droplet size or the chemical composition of the continuous phase changes over time.
WGM elastometry is based on the elastocapillary interaction between the droplets and the surrounding soft matrix. We used gelatin hydrogel and mouse tissues as examples. The matrix was controllably deformed and the deformation response of the droplets was measured via modification of the WGM spectrum to determine the local anisotropic stresses, which could be as small as a few pN/μm^2. Additionally, Young\u27s modulus of the matrix in the range 1kPa to 35 kPa, which covers most human soft tissues, could be measured.
The developed methods enable precise determination of the mechanical properties of fluids and soft materials, relevant to a wide range of applications, including the study of biological processes.Mikroresonatorji na osnovi kapljic lahko podpirajo ``whispering gallery\u27\u27 (WGM) optične resonance, ki so močno odvisne od velikosti in oblike kapljice. Tudi najmanjše spremembe v teh dveh parametrih povzročijo znatne spremembe v WGM spektru kapljice, kar je osnova za natančno optomehansko senzoriko. Z uporabo WGM spektroskopije smo razvili metodo imenovano WGM tenziometrija, za merjenje površinske napetosti na stiku med kapljičnim mikroresonatorjem in okoliško tekočino, ter metodo, imenovana WGM elastometrija, za merjenje lokalne napetosti in Youngovega modula mehke matrike, ki obdaja kapljico.
WGM tenziometrija vključuje generiranje in kontroliranje velikosti fluorescentno obarvane mikrokapljice narejene iz optično čiste tekočine, ki je pritrjena na konico steklene mikrokapilare in potopljena v okoliško tekočino. Mikrokapljice lahko podpirajo WGM načine, s katerimi spremljamo spreminjanje velikosti kapljice, medtem ko skozi mikrokapilaro apliciramo natančno nastavljiv tlak. Površinsko napetost se določi na podlagi velikosti kapljice in ravnovesnega tlaka. Ta metoda omogoča uporabo kapljic velikih le 8μm in zahteva minimalne količine vzorca. V primerjavi z drugimi metodami tenziometrije pri WGM tenziometriji ni potrebno vnaprej poznati gostote obeh tekočin. Poleg tega se lahko meritve površinske napetosti izvajajo v neravnovesnih stanjih, ko se velikost kapljice ali kemijska sestava okoliške tekočine s časom spreminjata.
WGM elastometrija temelji na elastokapilarni interakciji med kapljicami in okoliško mehko matriko, pri čemer sta bila uporabljena hidrogel iz želatine in mišja tkiva. Matrika je bila nadzorovano deformirana, odziv kapljic pa merjen prek WGM-jev, kar je omogočilo določanje lokalnih anizotropnih napetosti, ki so lahko velikostnega reda le nekaj pN/μm^2. Poleg tega metoda omogoča meritev Youngovega modula matrike v območju 1kPa do 35kPa, kar zajema večino mehkih tkiv pri ljudeh.
Razvite metode omogočajo natančnejšo določitev mehanskih lastnosti tekočin in mehkih materialov, kar je pomembno za širok spekter aplikacij, vključno s preučevanjem bioloških procesov
Remote temperature measurements with cholesteric liquid-crystal 3D microlasers
Get PDFV delu obravnavamo fizikalne lastnosti holesteričnih tekočih kristalov in njihovo uporabo v kapljični geometriji za realizacijo 3D mikrolaserjev. Holesterični tekoči kristali so fotonski material, v katerih obstaja prepovedan pas fotonov v disperzijski enačbi. Tako je za določene valovne dolžine propagacija prepovedanahkrati pa se na robovih prepovedanega fotonskega pasu poveča fotonska gostota stanj, zaradi česar je v takih resonatorjih možno lasersko delovanje pri nizkih pragih. Pri črpanju z ekscitacijskim pulznim laserjem povzročimo obrnjeno zasedenost aktivnega medija, emisija katerega se optično ojača zaradi optičnih lastnosti holesteričnega tekočega kristala. Resonatorji holesteričnih tekočih kristalov so občutljivi na zunanje motnje zaradi katerih se valovna dolžina laserske črte spremeni. Valovna dolžina laserske emisije se spremeni zvezno v območju fluorescence aktivnega medija kot odziv na spreminjanje strukture resonatorja. To omogoča njihovo uporabo za zaznavanje fizikalnih in kemijskih količin v opazovanem sistemu. Z eksperimentom smo realizirali merjenje temperature z opazovanjem premika laserske črte, pri čemer smo mikrolaserje vzbujali in merili odziv na daljavo. Ta metoda omogoča merjenje temperature v majhnem volumnu, ki ni vezan le na površino opazovanega sistema, na razdaljah več deset metrov, v realnem času in z natančnostjo pod stopinjo celzija v nekaj sekundah. V prvem delu predstavimo osnovne pojme in enačbe s področja fizike laserjev in fizike tekočih kristalov. Pri obravnavanju svetlobnih interakcij s tekočimi kristali se poglobimo v mehanizem ojačanja svetlobe v holesteričnih tekočih kristalih ter zajemanje svetlobnega signala z eksperimentalno napravo. Zaradi geometrije kapljic opazimo več načinov laserskega delovanja. Te načine opišem in analiziram njihove spektre, ter proučim kako jih lahko izkoristimo v različnih sistemih. V osrednjem delu opišem optične sisteme, ki sem jih uporabil pri eksperimentalnih meritvah in izdelavo holesteričnih tekoče-kristalnih kapljic. Pokažem rezultate in analiziram eksperimentalne meritve ter ovrednotim možnost uporabe izdelanega optičnega sistema v kombinaciji s 3D mikrolaserskimi senzorji v industriji, medicini in raziskovanju.In this thesis we present physical properties of cholesteric liquid crystals and their usability in spherical geometry as 3D microlasers. Cholesteric liquid crystals are photonic materials in which a band gap in dispersion relation of propagating wave exist. Therefore the propagation for specific wavelengths of light are forbidden inside the structureat the same time as a result of the bandgap, there is an increase of density of states at the edges of the forbbiden band, making low-threshold lasing possible at the edges of the bandgap. The excitation of dye molecules by an external pump laser source creates population inversion in these systems, which results in stimulated laser emission. Since the cholesteric liquid crystal structure acts as a resonator cavity and is sensitive to external stimuli, the lasing wavelength changes in response. Lasing wavelength changes continuously in the region of fluorescent emission of the gain medium for sustained/ever-present stimuli. This enables their use as sensors for measuring physical and chemical properties of the observed system. We demonstrate their sensisivity and usability for remote temperature measurements. This method enables temperature measurements in a very small volume, which is not constrained to the surface of the measured system, at distances up to tens of meters, in real time and with the accuracy below a one degree Celsius in less than a secound. In the first part we present basic concepts and equations from the area of laser physics and physics of liquid crystals. We discuss in depth the interaction of light with cholesteric liquid crystals, which enables laser operation in these stuctures. We also discuss the collection of light with the constructed optics system. The spherical geometry of the cholesteric liquid crystal droplets enables multiple modes of lasing. We describe these modes and analyze their spectra in the experiment. In the main part we describe the optical systems, that were used during the experimentation, the preparation of the samples and show the experimental results. We also discuss the possibility of impoving the optical system as well as the sensors and mention why that could be used in industry, medicine or research
Evaluation of HiSorb Samplers for the Determination of Volatile Organic Compounds
No full textUporaba vzorčevalnikov na osnovi mikroekstrakcije na trdno fazo (SPME) je že utečena pri analizi hlapnih organskih spojin (HOS). Zaradi majhne kapacitete in slabih mehanskih lastnosti so SPME v zadnjih letih za nekatera področja uporabe začeli nadomeščati HiSorb vzorčevalniki. Ti so lahko opremljeni z enakimi sorpcijskimi materiali, a so robustnejši in imajo bistveno večjo kapaciteto. V okviru diplomskega dela sem optimiziral metodo za semi-kvantitativno določanje toluena z uporabo HiSorb vzorčevalnkov. Določil sem optimalen čas vzorčenja ter pripravil umeritveno krivuljo za vzorčenje nadprostora (angl. headspace). Metodo pasivnega vzorčenja s HiSorb vzorčevalniki sem primerjal tudi z aktivnim vzorčenjem na Tenax® TA cevkah. Na koncu sem preveril uporabnost na praktičnem primeru vzorčevanja HOS iz stare knjige. Rezultati kažejo, da so vzorčevalniki sicer primerni za semi-kvantitativno določitev hlapnih organskih analitov, za bolj natančne meritve pa bodo potrebne nadaljne raziskave ter optimizacija metode.The use of solid-phase microextraction (SPME) samplers is already well established for the analysis of volatile organic compounds (VOCs). Due to their low capacity and poor mechanical properties, SPME samplers have in the past years begun to be replaced in certain applications by HiSorb samplers. These can be equipped with the same sorption materials but are more robust and have a significantly higher capacity. As part of my thesis, I optimized a method for the semi-quantitative determination of toluene using HiSorb samplers. I determined the optimal sampling time and constructed a calibration curve for headspace sampling. I also compared the passive sampling HiSorb method to the active sampling on Tenax® TA tubes. Finally, I tested the applicability on a practical example of sampling of VOCs from old book. The results show that while the samplers are suitable for the semi-quantitative determination of volatile organic analytes, further research and method optimization will be needed for more precise measurements
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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