1,721,225 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
Investigação do efeito de fotocondutividade em poços quânticos de SnTe/PbEuTe
Full text linkIn this work, we study the photoconductivity effect in p-type IV-VI semiconductors
SnTe/P b0,9Eu0,1T e. The samples were grown using molecular beam epitaxy, resulting
in high quality 30 nm-wide structures. Photoconductivity measurements are made for
temperatures below 200 K, with radiation varying from infrared (IR, 940 nm) to ultraviolet
(UV, 398 nm) wavelengths. A positive photoresponse is observed for temperatures greater
than 10 K, with persistent photoconductivity when the light is turned off. Analysis of
the photoconductivity decay curves showed that defect states are present in the energy
band structure of SnTe, and that different defects are activated, as functions of the
radiation energy. For temperatures below 10 K, a transition from positive to negative
photoconductivity is observed when the sample is illuminated by UV light. To explain the
negative effect, Hall measurements were made in order to obtain the carrier concentration
and mobility under light and dark conditions, comparing the variation of these parameters
using UV radiation. With this information, the negative photoconductivity effect is
explained with a classical transport model that predicts the transition for temperatures
below 4 K. Magnetoresistance measurements showed that there is no contribution of the
topological surface states for the electrical transport under illumination. In a second sample,
photoconductivity measurements were conducted for lights ranging from IR, through visible
to UV, in order to verify the dependence of negative photoconductivity on radiation energy.
It was observed that the negative effect indeed manifests only for radiations with energies
greater than 2 eV, starting with yellow. This leads to the conclusion that the negative
photoconductivity is originated from the energy bands above 2 eV.Neste trabalho, são estudados os efeitos de fotocondutividade no poço quântico composto
pelos semicondutores IV-VI do tipo-p SnTe/P b0,9Eu0,1T e. As amostras utilizadas no
trabalho foram crescidas com a técnica de epitaxia por feixe molecular, que resultou em
estruturas de alta qualidade cristalina com espessuras de aproximadamente 30 nm. As
medidas de fotocondutividade são feitas para temperaturas menores que 200 K, para
comprimentos de onda específicos variando desde o infravermelho (IV), com comprimento
de onda de 940 nm, até o ultravioleta (UV), com comprimento de onda de 398 nm. É
observado uma fotorresposta positiva a temperaturas maiores que 10 K, com o efeito de
fotocondutividade persistente presente ao se retirar a iluminação. Em uma análise das
curvas de decaimento, foi possível verificar que a fotocondutividade persistente é devida à
presença de defeitos na estrutura de bandas do SnTe, e que diferentes defeitos são ativados
como funções da energia da radiação incidente. Para temperaturas menores que 10 K,
observa-se uma transição da fotocondutividade positiva para negativa quando a amostra
é iluminada com luz UV. Para explicar o efeito negativo, foram realizadas medições de
efeito Hall para obtenção da concentração e mobilidade de portadores, com e sem luz,
visando quantificar as variações desses parâmetros sob luz UV. Com essas informações,
a fotocondutividade negativa é explicada com base num modelo de transporte clássico
que prevê a transição para o efeito negativo em temperaturas menores que 4 K. Através
de medidas de magnetorresistência, ficou constatado que não há contribuição de estados
topológicos de superfície para o transporte sob iluminação. Numa segunda amostra, as
medidas de fotocondução foram conduzidas para LEDs que variavam do IV, passando
pelo visível até o UV, com o objetivo de verificar a dependência da fotocondutividade
negativa com a energia da radiação. De fato, foi observado que o efeito negativo só se
manifesta para radiações com energias maiores que 2 eV, a partir do amarelo. Isso leva à
conclusão que o aparecimento da fotocondutividade negativa é originada das bandas de
energia localizadas acima de 2 eV
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
Historia en tiempos pandémicos : covid-19 en Latinoamérica
No full textFil: Agostoni, Claudia. Universidad Nacional Autónoma de México. Instituto de Investigaciones Históricas; México.Fil: Ramacciotti, Karina. Universidad Nacional de Quilmes. Departamento de Ciencias Sociales; Argentina.Fil: Lopes, Gabriel. Casa de Oswaldo Cruz. Programa de Pós-Graduação em História das Ciências e da Saúde; Brasil.Teniendo como marco la trágica presencia de covid-19, historiadores de México, Argentina y Brasil realizan reflexiones en este texto sobre el contexto de la pandemia, así como su relación con precariedades sanitarias institucionales, estigmas persistentes y desigualdades sociales pasadas. Sus intervenciones son un registro preliminar del impacto de la pandemia en sus países. Están basadas en intervenciones presentadas en la mesa “História em tempos pandêmicos: reflexões sobre um ano de crises”, realizada en junio de 2021, moderada por Marcos Cueto y organizada por el Departamento de Pesquisa em História das Ciências e da Saúde de la Casa de Oswaldo Cruz, Fiocruz.Con referat
Historia en tiempos pandémicos : covid-19 en Latinoamérica
No full textFil: Agostoni, Claudia. Universidad Nacional Autónoma de México. Instituto de Investigaciones Históricas; México.Fil: Ramacciotti, Karina. Universidad Nacional de Quilmes. Departamento de Ciencias Sociales; Argentina.Fil: Lopes, Gabriel. Casa de Oswaldo Cruz. Programa de Pós-Graduação em História das Ciências e da Saúde; Brasil.Teniendo como marco la trágica presencia de covid-19, historiadores de México, Argentina y Brasil realizan reflexiones en este texto sobre el contexto de la pandemia, así como su relación con precariedades sanitarias institucionales, estigmas persistentes y desigualdades sociales pasadas. Sus intervenciones son un registro preliminar del impacto de la pandemia en sus países. Están basadas en intervenciones presentadas en la mesa “História em tempos pandêmicos: reflexões sobre um ano de crises”, realizada en junio de 2021, moderada por Marcos Cueto y organizada por el Departamento de Pesquisa em História das Ciências e da Saúde de la Casa de Oswaldo Cruz, Fiocruz.Con referat
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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