1,721,057 research outputs found
Myocardial histopathology in late-repaired and unrepaired adults with tetralogy of Fallot
No full textAccelerated whole-heart MR angiography using a variable-density poisson-disc undersampling pattern and compressed sensing reconstruction
No full textTo accelerate whole-heart three-dimension MR angiography (MRA) by using a variable-density Poisson-disc undersampling pattern and a compressed sensing (CS) reconstruction algorithm, and compare the results with sensitivity encoding (SENSE)
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
Disfunção vascular nos doentes com coarctação da aorta tratada
Full text linkRESUMO: As cardiopatias congénitas (CC) afetam aproximadamente 1% dos recémnascidos
e são responsáveis pela maior proporção de mortalidade infantil nos países
desenvolvidos. A coarctação da aorta (CoA), a 6ª CC mais frequente, consiste numa estenose
da aorta descendente proximal. Se não for tratada, tem uma história natural desfavorável.
A cirurgia, dilatação com balão e a implantação de stent são atualmente técnicas que
podem atingir o objetivo de uma remoção eficaz e duradoura da estenose ístmica, sendo
a decisão baseada na idade doente, anatomia da CoA e preferência do operador ou da
instituição. Contudo, um bom resultado anatómico não evita morbilidade e mortalidade
de longo prazo, apresentando cerca de metade dos doentes hipertensão arterial
(HTA), e registando-se mortalidade precoce, maioritariamente devido a complicações
cardiovasculares e acidentes vasculares cerebrais. O perfil tensional anómalo sugere que
os resultados subótimos possam ser secundários a disfunção vascular, cuja existência
foi bem documentada em doentes com CoA tratada. Existem anomalias intrínsecas da
estrutura arterial e função, alterações da sensibilidade neuro-hormonal ou da regulação
endócrina, e fatores adquiridos, como a idade do tratamento, que contribuem para esta
disfunção vascular. Os maus resultados a longo prazo podem resultar igualmente do tipo
de tratamento efetuado, que provavelmente impactam de modo diverso a rigidez do istmo
aórtico e potencialmente comprometem as funções da aorta. Este efeito da modalidade
terapêutica não foi até ao momento estudado. A CoA não é uma simples doença mecânica
que fica resolvida quando é removido o obstáculo.
Objetivos e Hipóteses: O objetivo deste estudo é comparar a função vascular entre diferentes
modalidades terapêuticas de CoA. A hipótese principal é a de que os doentes submetidos
a dilatação com balão têm melhor função vascular que os doentes submetidos a cirurgia
ou implantação de stent, pois aquela modalidade terapêutica tem menor potencial para
danificar a integridade e propriedades biomecânicas da parede da aorta do que estas.
Métodos: Avaliação prospetiva da função vascular usando múltiplas modalidades não
invasivas, de modo a comparar os resultados de três grupos de doentes com CoA, tratados
com dilatação com cirurgia, balão ou implantação de stent, após controle das variáveis de
confusão. Em doentes com CoA tratada com sucesso, comparámos prospectivamente a
rigidez da aorta com tonometria de aplanação e ressonância magnética cardíaca; função
endotelial com tonometria arterial periférica endotelial; analise da onda de pulso com
tonometria de aplanação e tonometria arterial periférica endotelial; massa ventricular
esquerda e anatomia do arco aórtico com ressonância magnética cardíaca; marcadores séricos de função endotelial, inflamação, função da parede arterial e matriz extracelular; e
saúde cardiovascular ideal. A análises estatística incluiu ajuste para as variáveis de confusão.
Resultados: O estudo foi realizado em sete grandes centros, de Portugal e Estados Unidos da
América. Foram incluídos 75 doentes, tratado por cirurgia (n=28), dilatação com balão (n=23)
e implantação de stent (n=24). Os grupos tiveram idade semelhante à data de inclusão,
gravidade da CoA, gradiente residual e perfil metabólico, mas eram diferentes quanto à
idade à data do tratamento. A HTA, rigidez da aorta, função endotelial e massa ventricular
eram semelhantes entre os grupos. Contudo, o grupo da dilatação com balão tinha mais
distensibilidade regional da aorta ascendente, menor tensão arterial (TA) sistólica durante
o exercício, menos alteração da variação noturna da TA, e dose menor de biomarcadores
inflamatórios. Os resultados permaneceram inalterados após ajuste das potenciais variáveis
de confusão, incluindo idade à data do tratamento.
Conclusões: A modalidade terapêutica não estava associada à presença de HTA, rigidez
arterial global e função endotelial. Contudo, os doentes com dilatação com balão tinham um
perfil de função vascular mais favorável, caracterizado por maior distensibilidade da aorta
ascendente, TA noturna mais baixa, menor resposta hipertensiva no esforço e menores
marcadores séricos de inflamação. São necessários mais estudos para confirmar se os nossos
resultados poderão contribuir para o refinamento do paradigma de tratamento da CoA, ao
adicionar ao objetivo de remoção da estenose, a preservação da função vascular, quando
dois ou mais tratamentos são aplicáveis.ABSTRACT: Introduction: Congenital heart disease (CHD) affects approximately 1% of liveborns and
accounts for the largest proportion of infant mortality in developed countries. Coarctation of
the aorta (CoA), the 6th most common CHD, consists of a narrowing of the proximal descending
aorta. If left untreated, it has an unfavorable natural history. Surgery, balloon dilation (BD) or
stent implantation are all current treatments that can achieve a successful long-term removal
of the stenosis, and the choice is based on age, CoA anatomy, and personal or institutional
preference. Coarctation is not a mere mechanical disease that is treated by removing the
increased afterload. In fact, a good anatomic result does not avoid long-term cardiovascular
(CV) morbidity and mortality, with late systemic hypertension (HTN) in approximately half of
the patients, and reduced life expectancy, mostly due to CV complications and stroke. The
abnormal blood pressure (BP) phenotype suggests that the suboptimal results are likely due
to abnormal vascular function, which has been well documented in patients with repaired
CoA. There are inherent changes in the arterial structure and function, impaired neuronal
sensitivity or endocrinal auto-regulation, and acquired features, such as age at treatment,
that contribute to vascular dysfunction in CoA. The poor long-term vascular outcome
may also be impacted by the different types of repair, which likely have differing effects
on the stiffness of the repaired segment and potentially compromise both the conduit and
cushioning functions of the aorta. The effects of treatment modality on long-term vascular
function remain uncharacterized.
Aims and Hypothesis: The goal of this study is to assess vascular function in this patient
population for comparison among the treatment modalities. The central hypothesis of
this study was that patients who have undergone successful BD will have better vascular
function than patients who have undergone successful surgical repair or stenting since
this modality is least likely to damage the integrity and biomechanical properties of the
aortic wall.
Methods: Prospective assessment of vascular function using multiple non-invasive modalities,
and compare the results among the three groups of CoA patients previously treated using
surgery, BD or stent implantation after frequency matching for confounding variables. In
successfully repaired CoA patients, we prospectively compared aortic stiffness by applanation
tonometry and cardiac magnetic resonance (CMR); endothelial function by endothelial pulse
amplitude testing; pulse waveform analysis by applanation tonometry and endothelial pulse
amplitude testing; BP phenotype by office BP, ambulatory BP monitoring, and BP response
to exercise; left ventricular (LV) mass and aortic morphometrics by CMR; blood biomarkers of endothelial function, inflammation, vascular wall function, and extracellular matrix; and
ideal cardiovascular health. In the statistical analysis, we adjusted for potential confounders.
Results: This study was done in seven, large volume centers from Portugal and the United
States of America. Participants included 75 patients treated with surgery (n=28), BD (n=23),
or stent (n=24). Groups had similar age at enrollment, CoA severity, residual gradient, and
metabolic profile but differed by age at treatment. Systemic HTN, aortic stiffness, endothelial
function, and LV mass were similar among groups. However, BD had more distensible
ascending aortas, lower peak systolic BP during exercise, less impairment in diurnal BP
variation, and lower inflammatory biomarkers. The results were unchanged after adjustment
for potential confounders, including age at treatment.
Conclusions: Treatment modality was not associated with major vascular outcomes such
as systemic HTN, global aortic stiffness, and endothelial function. However, BD patients had
a better vascular phenotype profile characterized by higher ascending aorta distensibility,
lower night-time BP, lower peak exercise BP and lower levels of inflammatory markers.
Further studies are required to confirm if our results may contribute to refining the CoA
treatment paradigm by adding to the goals of therapy the preservation of vascular function when two or more treatment techniques are applicable
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
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