1,721,281 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
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
Serial assessment by intracoronary ultrasound bioresorbable coronary scaffold eluting with novolimus DESolveTM
No full textINTRODUÇÃO: Os suportes vasculares bioabsorvíveis (SVB) surgiram com a finalidade de aumentar a segurança tardia das intervenções coronárias percutâneas (ICP). Estes dispositivos liberam o fármaco antiproliferativo no local da obstrução e são absorvidos com o passar do tempo. A utilização do ultrassom intracoronário (USIC) pode ajudar na avaliação do processo de absorção deste dispositivo. OBJETIVOS: Primário: avaliar e comparar, pelo USIC, o volume e a área da luz, do vaso e do SVB imediatamente após o implante da prótese, e, tardiamente, aos 6 e 18 meses. Objetivos secundários: avaliar e comparar, pelo USIC, o volume e área da placa imediatamente após o implante da prótese, e, tardiamente, aos 6 e 18 meses e os diâmetros do vaso, lúmen e SVB após ICP e no seguimento. Percentual de estenose e perda tardia do lúmen pela angiografia no seguimento e incidência de eventos cardíacos adversos maiores (ECAM) até os 18 meses. MÉTODO: Trata-se de um estudo prospectivo, não randomizado com a inclusão de 20 pacientes que foram submetidos ao implante do SVB DESolve®. Foi realizado o USIC após o procedimento e aos 6 e 18 meses de seguimento. RESULTADOS: Dos 20 pacientes selecionados, um paciente recusou realizar o USCI aos 6 meses e dois não realizaram o exame aos 18 meses, sendo excluídos do estudo. Totalizando 17 pacientes analisados. A idade média foi de 58,59 ± 8,73 anos e 70,6% eram do sexo masculino. O quadro clínico predominante era de angina estável. A via de acesso preferencial foi a radial, todos os pacientes foram submetidos à pré e pós-dilatação e o sucesso angiográfico ocorreu em todos os casos. No seguimento, houve aumento significativo na área (6,41 ± 1,35 mm2 vs. 7,35 ± 1,53 mm2, p < 0,002), volume (101,19 ± 20,9 mm3 vs. 118,51 ± 26,6 mm3, p = 0,001) e diâmetros do dispositivo, pelo USIC, aos 6 meses quando comparado ao procedimento índice. Não houve alteração significativa nas áreas, nos volumes e nos diâmetros do vaso e lúmen, em qualquer comparação no seguimento. A perda tardia foi de 0,22 ± 0,30 mm aos 6 e de 0,33 ± 0,44 mm aos 18 meses. Não houve nenhum caso de reestenose angiográfica e trombose do dispositivo. No seguimento, não houve casos de ECAM. CONCLUSÕES: A ICP com a utilização do SVB DESolve® para o tratamento da doença arterial coronária não complexa demonstrou resultados promissores. Houve aumento do volume e área do dispositivo aos 6 meses e uma supressão eficaz da hiperplasia intimal sem ECAM no seguimento.INTRODUCTION: The bioresorbable vascular scaffolds (BVS) emerged in order to increase late safety of percutaneous coronary interventions (PCI). These devices release the antiproliferative drug to the site of obstruction and are absorbed over time. The use of intravascular ultrasound (IVUS) can help in the evaluation of this device absorption process. OBJECTIVES: The primary endpoint was to evaluate and compare, through IVUS, the volume and the area of the lúmen, the vessel and the device immediately after its implantation, and later at 6 and 18 months. The secondary endpoints were to evaluate and compare, through IVUS, the volume and the area of the plaque immediately after its implantation, and later at 6 and 18 months and diameters of the vessel, lúmen and BVS after PCI and at follow-up. Percentage of stenosis and late lúmen loss by angiography and incidence of major adverse cardiac events (MACE) up to 18 months. METHOD: This is a prospective, non-randomized study, with the inclusion of 20 patients who underwent implantation of DESolveTM. IVUS was performed after the procedure and at 6 and 18 months of follow-up. RESULTS: Of the 20 patients selected, one patient refused to perform the USCI at 6 months and two did not undergo the exam at 18 months and were excluded from the study. In total, 17 patients were analyzed. The average age was 58.59 ± 8.73 years and 70,6% were male. The most common clinical presentation was stable angina. The preferred vascular acess was to radial, all patients underwent pre- and post-dilation and angiographic success occurred in all cases. At follow-up there was a significant increase in area (6,41 ± 1,35 mm2 vs. 7,35 ± 1,53 mm2, p < 0,002), volume (101,19 ± 20,9 mm3 vs. 118,51 ± 26,6 mm3, p = 0,001) and diameters of the device, by IVUS, at 6 months when compared to the index procedure. There was no significant change in the areas, volumes and diameters of the vessel and lúmen, in any comparison at follow-up. The late loss was 0,22 ± 0,30 mm at 6 and 0,33 ± 0,44 mm at 18 months. There were no cases of restenosis and scaffold thrombosis. During follow-up there was no case of MACE. CONCLUSIONS: PCI with the use of DESolve scaffold for the treatment of non-complex coronary artery disease has shown promising results. There was an increase in the volume and area of the device at 6 months and an effective suppression of intimal hyperplasia without MACE at follow-up
Randomized comparison of percutaneous coronary interventions guided by optical coherence versus intravascular ultrasound versus angiography: iSIGHT randomized trial
No full textIntrodução: Por possibilitar melhor expansão dos stents e maiores áreas luminais finais, intervenção coronária percutânea (ICP) guiada por ultrassom intracoronário (USIC) associou-se com menor ocorrência de eventos cardíacos adversos maiores (ECAM) do que ICP guiada apenas por angiografia. Recentemente introduzida, a tomografia de coerência óptica (TCO) possui resolução 10 vezes maior do que o USIC; possui maior precisão em quantificar dimensões vasculares, melhores sensibilidade/especificidade para caracterizar o ateroma e aspectos de vulnerabilidade, e maior sensibilidade para avaliar a interação stent-vaso. Estudos iniciais, com uso subótimo da TCO, sugeriram que esta é inferior ao USIC para guia da ICP. Estudos randomizados, propondo protocolos dedicados para ICP guiada por TCO ainda são esparsos. Objetivos: Avaliar a não inferioridade da ICP guiada por TCO em comparação com a ICP guiada por USIC quanto a expansão dos stent ao final do procedimento. O objetivo secundário é avaliar o papel adicional da ICP com métodos de imagem invasivos em comparação com um protocolo bastante otimizado de ICP guiada por angiografia. Métodos: Pacientes com >= 1 lesão em >= 1 coronária com diâmetros entre 2,25 a 4,0 mm, foram randomizados 1:1:1, em blocos de 9, para ICP guiada por TCO, USIC ou angiografia. Desenvolvemos algoritmo específico para guia da ICP por TCO. Protocolos pré-definidos e otimizados para guia dos procedimentos com USIC e angiografia foram adotados. Todas as modalidades de imagem foram realizadas ao final dos procedimentos em todos os pacientes. Angiografias, USIC e TCO foram analisadas, de forma cega quanto ao grupo de randomização, em um laboratório de análise central. A margem de não inferioridade para a expansão dos stents na ICP guiada por TCO versus USIC foi estabelecida em 6,85%. Caso a não inferioridade fosse alcançada, testamos a superioridade da ICP guiada por TCO versus angiografia e da ICP guiada por USIC versus angiografia, para o mesmo desfecho. Resultados: Entre 2015 e 2016, randomizamos 151 pacientes para ICP guiada por TCO (n=51 pacientes; 51 lesões), USIC (n=51 pacientes, 51 lesões) e angiografia (n=49 pacientes, 53 lesões). A expansão dos stents foi 98,01 ± 16,14% nas ICP guiadas por TCO, 91,69 ± 15,75% nas guiadas por USIC e 90,53 ± 14,84% nas guiadas por angiografia (p=0,035). A expansão dos stents sob guia da TCO foi não inferior à obtida com USIC (diferença TCO - USIC: 7,00; IC 95% unicaudal: -0,39, p= 1 lesion in >= 1 coronary artery with reference vessel diameter ranging between 2.25 to 4.0 mm were randomized 1:1:1, in blocks of 9, to PCI guided by OCT, IVUS or angiography. We developed a specific algorithm for OCT-guided PCI. Specific pre-defined optimized guidance protocols were also used to guide PCI by IVUS and angiography. All imaging modalities were performed in all groups at the end of the procedures. All angiography, IVUS and OCT images were analyzed in an independent core laboratory, by analysts blinded to the randomization groups. The estimated non inferiority margin for stent expansion was 6.85%. If OCT-guided PCI reached the non-inferiority criteria, we tested, in a hierarchical manner, the superiority of OCT guided PCI versus angiography-guided PCI and IVUS-guided PCI versus angiography-guided PCI for the same endpoint. Results: Between 2015 and 2016, we randomized 151 patients to OCT-guided PCI (n=51 patients; 51 lesions), IVUS guided PCI (n=51 patients, 51 lesions) and angiography-guided (n=49 patients, 53 lesions). Stent expansion was 98.01 ± 16.14% in the OCT-guided PCI, 91.69 ± 15.75% IVUS-guided PCI and 90.53 ± 14.84% in the angiography-guided PCI (p=0,035). Stent expansions obtained by OCT guidance were non-inferior to those obtained by IVUS (estimated difference between OCT and IVUS: 7.00; one-sided 95% CI: -0.39, p<0.001), and superior to those obtained by angiography (p=0.024). No significant differences were seen in the stent expansions obtained by IVUS- and angiography-guided PCI. There were no significant differences among the three groups regarding the rates of stent edge dissection (OCT: 15.7% vs. IVUS: 11.7% vs. angiography: 18.9%, p=0.623), and periprocedural complications. MACE rates at a median follow-up of 2,5 years were low and comparable across the three groups (OCT: 7.8% vs. IVUS: 4.0% vs. angiography: 6.1%, p=0.772). Conclusions: By using a specific protocol for OCT-guided PCI stent expansions were non-inferior to those obtained by IVUS guidance and superior to an optimized and aggressive protocol of angiography-guided PCI, without increase in the rates of procedural complications. The clinical impact of such results should be investigated in future, adequately powered trials
Quantitative flow ratio (QFR) in assessing the functional significance of coronary artery stenoses: comparative analysis with myocardial perfusion scintigraphy
No full textIntrodução: A razão de fluxo quantitativo (QFR) demonstrou ser uma ferramenta valiosa para a avaliação da isquemia coronariana específica do vaso e para orientar a intervenção coronária percutânea (ICP). Por outro lado, o significado prognóstico da isquemia coronariana não invasiva tem sido questionado em estudos recentes. Poucos estudos tentaram estabelecer uma relação entre o QFR e exames de perfusão miocárdica não invasivos. Objetivo: Avaliar os fatores relacionados à concordância/discordância do QFR e da cintilografia de perfusão miocárdica (CPM) regional. Adicionalmente, pretendemos avaliar o impacto prognóstico de diferentes índices relacionados à carga isquêmica e aterosclerótica. Métodos: Avaliamos retrospectivamente pacientes consecutivos submetidos à angiografia coronária invasiva (ACI) eletiva e CPM em um intervalo máximo de 3 meses. Os valores off-line do QFR foram calculados e a porcentagem do defeito de perfusão na CPM foi determinada por paciente e por território vascular. A concordância e discordância entre os valores de QFR e a presença ou ausência de defeitos de perfusão na CPM foram avaliadas. Os territórios vasculares foram considerados concordantes se QFR0,80 e o summed stress score (SSS) 4 ou se QFR>0,80 e SSS0.80 and SSS<4 on MPS. Conversely, vascular territories were considered discordant if QFR 0.80 and SSS0.80 and SSS4 on MPS. Patients were classified into four groups according to the concordance between the three coronary territories. In addition, the following prognostic indices were evaluated: Leaman score, functional Leaman score and perfusion defect on MPS. Results: A total of 670 patients, 2010 coronary territories were analyzed by both, QFR and MPS. The mean age was 61.9±10.8 years old and 40.9% had diabetes. The concordance between the two methods was the following: total concordance (n=348, 51.9%), partial concordance (n=226, 33.8%), poor concordance (n=79, 11.8%) and total discordance (n=17, 2,5%). According to the ICA, 35.7% had non-obstructive coronary artery disease (CAD). The vast majority of total concordance occurred in patients with no CAD/single-vessel disease (83.3%) and vascular territories predominantly without perfusion defects on MPS (90.7%). In the multivariate analysis, previous PCI (OR: 2.62, 95%CI: 1.544.42, p<0.01), left ventricular ejection fraction (OR: 0.98, 95%CI: 0.970.99, p=0.03), and the presence of two-vessel CAD (OR:8.65, 95%CI: 4.0618.40, p<0.01) and three-vessel CAD (OR:12.72, 95%CI: 5.6128.90; p<0.01) were identified as independent predictors of poor concordance/total discordance between QFR and MPS. After 1400 days (median follow-up time) the QFR-based Functional Leaman Score terciles provided the best risk stratification for all-cause death and myocardial infarction (Log-rank p=0.0056, HR 2.86: 1.43-5.72). The purely anatomical Leaman score and perfusion defects on MPS did not show significant differences among terciles. Conclusions: In this comparison between vessel-specific (QFR) versus regional ischemia (MPS), total concordance occurred slightly more than half of the patients. The predictors of discordance were related to a high-risk profile, including multivessel disease, previous PCI, and LVEF. Our findings suggest that QFR-based functional assessment combined with myocardial at risk (QFR-based Leaman Score) provides the best risk stratification for all-cause death and myocardial infarction. These findings suggest that QFR and MPS may provide distinct information on prognostic discriminatio
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