1,720,967 research outputs found
Plastic solar cells: where the current begins: Ultrafast exciton-to-charge conversion in organic photovoltaics
Full text linkStel je voor : een wereld met overal gratis energie. Je hoeft geen telefoon oplader mee te nemen – je rugzak zorgt voor de energie. Je huis heeft geen elektriciteitsaansluiting nodig – de muren en ramen produceren de energie. En hoewel dit klinkt als science-fiction, is deze wereld veel dichter bij de realiteit dan je zou denken : onze zon levert meer dan genoeg energie voor wat de mensheid nodig heeft. Nu al gebruiken mensen met succes zonne-energie door het met silicium zonnecellen om te zetten naar elektriciteit. Dit soort zonnecellen zijn echter vrij zwaar en omvangrijk, wat hun toepassingsgebied beperkt. Als alternatief kunnen zonnecellen ook worden gemaakt van speciale kunststoffen – en deze zonnecellen kunnen vouwbaar, semi-transparant, lichtgewicht, van elke vorm en draagbaar zijn – zodat hun mogelijk toepassingsgebied oneindig lijkt. Helaas zijn op dit moment de efficiënties van dit soort zonnecellen nog steeds twee maal zo laag als de efficiënties van hun silicium tegenhangers. Om de efficiëntie van kunststof zonnecellen te verbeteren moeten we alle foto-fysica achter de licht-naar-elektriciteit conversie begrijpen. Vele cruciale processen hierin gebeuren sneller dan een miljardste van een seconde, maar hebben toch een grote invloed op de algehele prestatie van zo’n kunststof zonnecel. In dit proefschrift gebruiken we laser spectroscopie om belangrijke processen te onthullen, die van invloed zijn op de ‘licht-stroom’ van zonnecellen op deze ongelofelijk snelle tijdsschalen, als ook mogelijke verliezen die de efficiëntie van deze zonnecellen verlagen. Gewapend met dit begrip doen we voorstellen voor trajecten om de efficiëntie van licht-naar-elektriciteit te maximaliseren, zodat, naar wij geloven, deze Droomwereld een stukje dichterbij komt
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
Ultrafast dynamics of intra- and intermolecular interactions in liquids and films
Full text linkUltrafast Dynamics of Intra- and Inter-molecular Interactions in Liquids and Films Evgeniia Salamatova Intra- and inter-molecular interactions determine many dynamical properties in bio- and energy-related materials such as energy transfer, vibrational relaxation and exciton diffusion. An understanding of such processes is very helpful for predicting more complex properties (e.g. hydrogen bonding and structural organization) as well as for designing new materials. In this thesis, the dynamical properties of liquids and solid films are studied by ultrafast spectroscopy. We show that the molecules with a single peptide bond (-CONH-) form atypical for liquids well-organized structures, which promote intermolecular energy transfer. If such molecules are dissolved in water, the energy migration between molecules is not largely affected but the molecules begin to experience a hydrophobic collapse. Similarly, spectroscopy on diluted alcohols demonstrates that the dynamical properties of the bulk alcohols are determined by intermolecular interactions while the intramolecular ones play a minor role. In contrast, for solid films of organic photovoltaic materials, both intra- and intermolecular interactions are crucial for energy transfer and exciton dynamics. The current thesis forms a convenient basis for predicting dynamical and structural properties of (bio)molecular systems with natural extension to e.g. DNA and proteins. The obtained results are also instrumental for designing new molecules for organic electronics applications
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
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
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