1,721,007 research outputs found
Computational Patient-Specific Models Based on 3D Ultrasound Data to Quantify Uterine Arterial Flow during Pregnancy.
No full textInformation on uterine blood flow rate during pregnancy would widely improve our knowledge on feto-placental patho-physiology. Ultrasonographic flow rate evaluation requires the knowledge of the spatial velocity profiles throughout the investigated vessel; these data may be obtained from hemodynamic simulations with accurate computational models. Recently, computational models of superficial vessels have been created using 3-D ultrasound data; unfortunately, common reconstruction methods are unsuitable for the uterine arteries due to the low quality achievable of imaged deep vessels. In this paper a simplified spline-based technique was applied to create computational models for patient-specific simulations of uterine arterial heamodynamics. Moreover, a novel method to quantify the uterine flow rates was developed based on echo-Doppler measurements and computational data. Preliminary results obtained for four patients indicated a quite narrow range for the blood flow rate through the main uterine artery with large variability in the flow split between corporal and cervical branches. Furthermore, parabolic-like velocity profiles were obtained in the branching region of the different patients, suggesting a clinical use of averaged, not patient-specific, spatial velocity distribution coefficients for the blood flow rate calculation. The developed reconstruction method based on 3-D ultrasound imaging is efficient for creating realistic custom models of the uterine arteries. The results of the fluid dynamic simulations allowed us to quantify the uterine arterial flow and its repartition in normal pregnancies
Evaluation of fetal growth and fetal well-being
No full textThis article reviews the actual knowledge and future developments of ultrasound techniques for the evaluation of fetal growth and well-being. Sonography allows the visualization of the fetus in utero and is utilized worldwide for the evaluation of fetal growth and well-being. Fetal biometry assessment is performed in the second half of pregnancy when deviations of fetal growth can be best recognized through alterations of fetal abdominal circumference growth. Doppler velocimetry of utero-placental vessels identifies alterations of placental perfusion and is valuable in the assessment of fetal brain, heart, and liver perfusion, thus being utilized in the timing of delivery. Recently, three-dimensional ultrasound evaluation of fetal organs and placenta is being developed
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
Estimation of fetal oxigen uptake in human term pregnancies
No full textOBJECTIVE: Umbilical oxygen (O(2)) uptake is a parameter of basic physiologic interest. It has been extensively studied in chronically catheterized animals but very few data have been obtained acutely in humans. Recent developments in ultrasound technology allow the estimation of umbilical venous blood flow in utero.
METHODS: In all, 26 normal term pregnancies were studied at the time of elective cesarean section in order to evaluate fetal O(2) uptake as the product of umbilical blood flow and umbilical O(2) veno-arterial difference. An ultrasound evaluation was performed within 1 h from delivery: umbilical vein area and flow velocity were recorded to calculate umbilical vein volume flow (Q(umb)). Blood samples from the umbilical vein (uv) and artery (ua) were obtained at the time of fetal extraction for respiratory gases and acid-base evaluation.
RESULTS: Umbilical O(2) uptake was calculated as Q(umb) • (uv-ua)O(2) content: an average value of 0.84 ± 0.40 mmol/min was obtained. Umbilical O(2) uptake per kg was 0.25 ± 0.12 mmol/kg/min, significantly related to fetal O(2) delivery.
CONCLUSIONS: We estimated umbilical blood flow by ultrasound and we measured umbilical O(2) uptake at term obtaining a value of umbilical O(2) uptake/kg similar to what previously reported in human pregnancies and chronically catheterized animal
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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