1,721,054 research outputs found
Continuous Simultaneous Recording of Brachial Artery Distension and Wall Shear Rate: a New Boost for Flow-Mediated Vasodilation
Full text linkVascular ultrasound has been extensively applied in the clinical setting to noninvasively assess endothelial function by means of the so-called brachial artery flow mediated dilation (FMD). Despite the usefulness in large-scale epidemiological studies, this approach has revealed some pitfalls for assessing vascular physiology and health in individual subjects. Mainly, a reliable FMD examination should be based on the simultaneous and reliable measurement of both the stimulus, i.e. the wall shear rate (WSR), and the response, i.e. the diameter change. However, multiple technical, practical, and methodological challenges must be faced to meet this goal. In this work, we present the technical developments needed to implement a system to enable extensive and reliable clinical ultrasound FMD examination. It integrates both a hardware, i.e. an upgraded version of the ultrasound advanced open platform (ULA-OP), and a software part, i.e. a signal processing and data analysis platform. The system was applied for a two-center pilot clinical study on 35 young and healthy volunteers. Therefore, we present here the results of a statistical analysis on magnitude, time-course and kinetic parameters of WSR and diameter trends that allowed us to accurately explore the vasodilatory response to the dynamic wall shear rate changes. Our observations demonstrate that a direct and accurate estimation of WSR stimulus by multigate spectral Doppler allows understanding brachial artery vasodilatory response to reactive hyperemia. Drawing inferences on WSR stimulus from the diameter response along with an inaccurate estimation of WSR may cause further uncertainties for the accurate interpretation of the FMD response
Deep Brain Stimulation of Subgenual Cingulate Region for Treatment of an Early-Onset Conversion Disorder with Psychogenic Non-Epileptic Seizures and Prolonged Catatonia: Preliminary Results in One Patient
No full textConversion disorder (CD) with psychogenic non-epileptic
seizures (PNES) and catatonia are considered “network
pathologies” of cortico-striato-thalamo-cortical
loops, in which subgenual cingulate region (SGC) plays a
hub role in the modulation of motivational and cognitive
functions involved in motor control [1, 2]. SGC, previously
selected as Deep Brain Stimulation target for depression
disorders [3], shows a PET/CT scan hypermetabolism
also in patients with CD. We report a case of an
18-year-old female patient with severe, early-onset (12
years old) CD with PNES and prolonged catatonia. Because
of daily episodes of PNES, prolonged catatonia (1
episode continued over 4 months with nasogastric feeding
necessity) and consequent hospitalizations, development
acquisitions were hindered, and intellectual deterioration
was observed. A brain PET/CT scan analysis revealed
a significant increase (p value <0.01 evaluated with
a Statistical Parametric Software) of the regional cerebral
metabolic rate on glucose consumption in bilateral putamen
and caudate nuclei, bilateral prefrontal and orbitofrontal
cortex, and subgenual cingulate gyrus, similar to
patients with depression submitted to SGC DBS [3].
Due to the severe clinical impact of related symptoms
on her life quality and therapeutic failures, the Paediatric
Ethical Committee and legal guardian informed consent
approved the SGC DBS application and the publication of
this case. At 18 years old (July 2018), a bilateral DBS of the
SGC was performed under general anesthesia using a
frame-based (Leksell, Elekta Instruments®, Sweden) technique
coupled with a robotic system for stereotactic neurosurgery
(Neuromate®; Renishaw-Mayfield SA, Nyon,
Switzerland). Two bilateral avascular trajectories were assigned
to the anatomical targets located in a white matte
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
Développement et validation de nouvelles méthodes d'imagerie du flux par ultrasons
No full textUltrasound is widely used for blood flow imaging because of the considerable advantages for the clinician, in terms of performance, costs, portability, and ease of use, and for the patient, in terms of safety and rapid checkup. The undesired limitations of conventional methods (1-D estimations and low frame-rate) are widely overtaken by new vector approaches that offer detailed descriptions of the flow for a more accurate diagnosis of cardiovascular system diseases. This PhD project concerns the development of novel methods for blood flow imaging. After studying the state-of-the-art in the field, a few approaches have been examined in depth up to their experimental validation, both in technical and clinical environments, on a powerful ultrasound research platform (ULA-OP). Real-time novel vector methods implemented on ULA-OP were compared to standard Doppler methods in a clinical study. The results attest the benefits of the vector methods in terms of accuracy and repeatability. Plane-wave transmissions were exploited to improve the transverse oscillation imaging method. Double oscillating fields were produced in large regions and exploited for the vectorial description of blood flow at high frame rates. Blood flow maps were obtained by plane waves coupled to a novel velocity estimation algorithm operating in the frequency domain. The new method was demonstrated capable of high accuracy and reduced computational load by simulations and experiments (also in vivo). The investigation of blood flow inside the common carotid artery has revealed the hemodynamic details with unprecedented quality. A software solution implemented on a graphic processing unit (GPU) board was suggested and tested to reduce the computational time and support the clinical employment of the methodL'échographie est largement utilisée pour l'imagerie du flux sanguin pour ses nombreux avantages tels que son inocuité, son cout réduit, sa facilité d'utilisation et ses performances. Cette thèse a pour objectif de proposer de nouvelles méthodes ultrasonores d'imagerie du flux sanguin. Après une étude bibliographique, plusieurs approches ont été étudiées en détail jusqu'à leur implémentation sur l'échographe de recherche ULA-OP développé au sein du laboratoire et ont été validées en laboratoire et en clinique. La transmission d'ondes planes a été proposée pour améliorer la technique d'imagerie utilisant les oscillations transverses. Des champs de pression ultrasonores présentant des oscillations transverses sont générés dans de larges régions et exploités pour l'estimation vectorielle du flux sanguin à une haute cadence d'imagerie. Des cartes du flux sanguin sont obtenues grâce à une technique s'appuyant sur la transmission d'ondes planes couplées à un nouvel algorithme d'estimation de la vitesse dans le domaine fréquentiel. Les méthodes vectorielles implémentées en temps réel dans le ULA-OP ont été comparées à la méthode Doppler classique lors d'une étude clinique. Les résultats ont montré le bénéfice des méthodes vectorielles en termes de précision et de répétabilité. La nouvelle méthode proposée a démontré sa grande précision ainsi que son gain en termes de temps de calcul aussi bien en simulations qu'en acquisitions en laboratoire ou lors d'essais in vivo. Une solution logicielle temps réel implémentée sur une carte GPU a été proposée et testée afin de réduire encore le temps de calcul et permettre l'emploi de la méthode en cliniqu
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