1,721,061 research outputs found
MRSI vs CEST MRI to understand tomato metabolism during fruit development: is there a better contrast?
No full textRaw data supporting the results presented in the paper entitled "MRSI vs CEST MRI to understand tomato metabolism during fruit development: is there a better contrast?"
The files named ExperimentalDetails v2 (xlsx or pdf) describe the datase
Spurious phase correction in rapid metabolic imaging
No full textThis Data file contains experiments used to validate the theory explained in the submitted paper entitled :
Spurious Phase Correction in Rapid Metabolic Imaging
written by :
Nour EL SABBAGH(1,2,3), Carine CHASSAIN(1,2,3), Hélène RATINEY(4), Guilhem PAGES(1,2), Jean-Marie BONNY(1,2).
(1) INRAE, UR QuaPA, F-63122 Saint-Gènes-Champanelle, France
(2) AgroResonance, INRAE, 2018. Nuclear Magnetic Resonance Facility for Agronomy, Food and Health, doi: 10.15454/1.5572398324758228E12
(3) Université Clermont Auvergne, CHU, CNRS, Clermont Auvergne INP, Institut Pascal, F-63000 Clermont-Ferrand, France.
(4) Université Lyon 1, CNRS, Inserm, INSA Lyon, UCBL, CREATIS, UMR5220, U1294, F-69621 Villeurbanne, France
Abstract:
Rapid multi-shot MRSI sequences, like IDEAL spiral, require the acquisition of several datasets using optimized sampling in the time domain to reconstruct metabolite maps. Each unitary scan consists of a selective slice (2D) or slab (3D) excitation followed by an evolution time and then the acquisition of the spatially encoded signal. It is critical that the phase variation during the evolution time for each scan is only dependent on chemical shifts. In this paper, we highlight that the phase may depend on either the excitation (fe) or the reception (fr) frequency depending on where the switch from the first to the second frequency is performed in the pulse sequence. To override this, we propose two types of solutions. The first one is based on post-processing signal correction while the second one consists of performing the frequency switch at an appropriate position in the pulse sequence. In order to illustrate this issue, we used the IDEAL spiral method applied to a 13C phantom.
The first application, which was published in the paper, was a general case for multiple metabolites (multiple spins) :
* 13C Metabolic Imaging using IDEAL spiral.
The second one, which was not published, deals with only 1 metabolite (1 spin) :
* 1H High Resolution B0 map.
Each application has a folder containing:
* a READ ME file for a detailed description,
* a Data folder containing the experiments dataset,
* a Matlab folder containing the script used.
<br
Détermination des volumes morts et des eff ets extra-colonne en chromatographie liquide de partage à polarité de phase inversée
No full textLes notions de volume mort et de temps de rétention nulle sont primordiales en
chromatographie. Elles interviennent dans la détermination des principales grandeurs
chromatographiques, indispensables pour s’assurer de la validité d’un système
chromatographique, décrire des modèles de rétention théoriques, prédire la rétention des
analytes etc. En chromatographie liquide haute performance de partage à polarité de phase
inversée, le concept de volume mort est l’objet de polémiques à cause de l’ambiguïté de sa
défi nition et des diff érentes méthodes expérimentales mises en œuvre pour le déterminer. Nous
avons comparé diff érentes méthodes de mesure des volumes morts totaux et extra-colonne. La
pertinence de chaque méthode étudiée est discutée en fonction des objectifs de l’analyste.Void volume and void time are of the utmost importance in chromatography. They are essential for an accurate
determination of fundamental chromatographic values. These fundamental values are used for system suitability
issues, for theoretical retention descriptions, for prediction of retention of both small and large molecules and for
many other issues. In reversed phase liquid chromatography, void volume concept has proven to be controversial
because of its defi nition ambiguity and the many different methods proposed. The present work deals with the
comparison of the principal methods carried out to determine void volume but also band broadening effect. We
discuss also about the care to take in method selection depending on the objectives of the chromatographers
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
Zones d’écoute personnalisées mobiles par approches adaptatives
No full textThe thesis deals with the creation of mobile sound zones using adaptive approaches. The methods in use for the creation of sound zones aim to jointly resolve the sound reproduction in one zone and the minimisation of the energy of the signal reproduced in the other zone, from an array of loudspeakers. The thesis is divided into two parts: the estimation of impulse responses and moving sound zones. The aim of this thesis is to create two zones in space with a controlled sound field, which can move in space over time. In the first part, the estimation of the system's impulse responses is detailed, a necessary prerequisite for sound zone algorithms. Based on existing adaptive methods for estimating time-varying multi-input, multi-output systems, a new method applied to acoustics and MISO is presented. This method, called MISO-Autostep, makes it possible to estimate impulse responses over time without having to fine-tune any parameters. In the second part, the BACC-PM sound zone algorithm is rewritten in recursive form. This ability to update the filter coefficients over time opens up the possibility of adapting to temporal changes in the system geometry. Finally, preliminary results are presented with the joint use of the two adaptive algorithms in the case of an abrupt change in the system geometry.La thèse aborde la création de sound zones (zones d'écoute personnalisées) mobiles par des approches adaptatives. Les méthodes en usage pour la création de sound zones visent à résoudre conjointement la reproduction sonore dans une zone et la minimisation de l'énergie du signal reproduit dans l'autre zone, à partir d'un réseau de haut-parleurs. La thèse se divise en deux parties : l'estimation des réponses impulsionnelles et les sound zones mobiles. L'objectif de cette thèse est de créer deux zones de l'espace dont le champ acoustique est contrôlé, ces zones pouvant bouger dans l'espace au cours du temps. Dans la première partie, l'estimation des réponses impulsionnelles du système est détaillée, prérequis nécessaire pour les algorithmes de sound zones. A partir des méthodes adaptatives existantes pour l'estimation de systèmes multi-entrées multi-sorties variant dans le temps, une nouvelle méthode appliquée à l'acoustique et MISO est présentée. Cette méthode, appelée MISO-Autostep, permet d'estimer les réponses impulsionnelles au cours du temps sans avoir de paramètres à ajuster finement. Dans la seconde partie, l'algorithme de \sound zones BACC-PM est réécrit sous forme récursive. Cette capacité à mettre à jour les coefficients des filtres au cours du temps ouvre la voie à s'adapter à des changements temporels dans la géométrie du système. Enfin, des résultats préliminaires sont présentés avec l'utilisation conjointe des deux algorithmes adaptatifs dans le cas d'une modification brusque de la géométrie du système
- …
