Quantitative morphometry analysis of the fetal brain using clinical MR imaging

In vivo fetal magnetic resonance imaging provides aunique approach for the study of early human braindevelopment [1]. In utero cerebral morphometry couldpotentially be used as a marker of the cerebralmaturation and help to distinguish between normal andabnormal development in ambiguous situations. However,this quantitative approach is a major challenge becauseof the movement of the fetus inside the amniotic cavity,the poor spatial resolution provided by very fast MRIsequences and the partial volume effect. Extensiveefforts are made to deal with the reconstruction ofhigh-resolution 3D fetal volumes based on severalacquisitions with lower resolution [2,3,4]. Frameworkswere developed for the segmentation of specific regionsof the fetal brain such as posterior fossa, brainstem orgerminal matrix [5,6], or for the entire brain tissue[7,8], applying the Expectation-Maximization MarkovRandom Field (EM-MRF) framework. However, many of theseprevious works focused on the young fetus (i.e. before 24weeks) and use anatomical atlas priors to segment thedifferent tissue or regions. As most of the gyraldevelopment takes place after the 24th week, acomprehensive and clinically meaningful study of thefetal brain should not dismiss the third trimester ofgestation. To cope with the rapidly changing appearanceof the developing brain, some authors proposed a dynamicatlas [8]. To our opinion, this approach however faces arisk of circularity: each brain will be analyzed /deformed using the template of its biological age,potentially biasing the effective developmental delay.Here, we expand our previous work [9] to proposepost-processing pipeline without prior that allow acomprehensive set of morphometric measurement devoted toclinical application. Data set & Methods: Prenatal MRimaging was performed with a 1-T system (GE MedicalSystems, Milwaukee) using single shot fast spin echo(ssFSE) sequences (TR 7000 ms, TE 180 ms, FOV 40 x 40 cm,slice thickness 5.4mm, in plane spatial resolution1.09mm). For each fetus, 6 axial volumes shifted by 1 mmwere acquired under motherâeuro?s sedation (about 1min pervolume). First, each volume is segmentedsemi-automatically using region-growing algorithms toextract fetal brain from surrounding maternal tissues.Inhomogeneity intensity correction [10] and linearintensity normalization are then performed. Brain tissues(CSF, GM and WM) are then segmented based on thelow-resolution volumes as presented in [9]. Ahigh-resolution image with isotropic voxel size of 1.09mm is created as proposed in [2] and using B-splines forthe scattered data interpolation [11]. Basal gangliasegmentation is performed using a levet setimplementation on the high-resolution volume [12]. Theresulting white matter image is then binarized and givenas an input in FreeSurfer software(http://surfer.nmr.mgh.harvard.edu) to providetopologically accurate three-dimensional reconstructionsof the fetal brain according to the local intensitygradient. References: [1] Guibaud, Prenatal Diagnosis29(4) (2009). [2] Rousseau, Acad. Rad. 13(9), 2006. [3]Jiang, IEEE TMI 2007. [4] Warfield IADB, MICCAI 2009. [5]Claude, IEEE Trans. Bio. Eng. 51(4) 2004. [6] Habas,MICCAI 2008. [7] Bertelsen, ISMRM 2009. [8] Habas,Neuroimage 53(2) 2010. [9] Bach Cuadra, IADB, MICCAI2009. [10] Styner, IEEE TMI 19(39 (2000). [11] Lee, IEEETrans. Visual. And Comp. Graph. 3(3), 1997. [12] BachCuadra, ISMRM 2010.

Use of anisotropic modelling in electrical impedance tomography: description of method and preliminary assessment of utility in imaging brain function in the adult human head.

Electrical Impedance Tomography (EIT) is an imaging method which enables a volume conductivity map of a subject to be produced from multiple impedance measurements. It has the potential to become a portable non-invasive imaging technique of particular use in imaging brain function. Accurate numerical forward models may be used to improve image reconstruction but, until now, have employed an assumption of isotropic tissue conductivity. This may be expected to introduce inaccuracy, as body tissues, especially those such as white matter and the skull in head imaging, are highly anisotropic. The purpose of this study was, for the first time, to develop a method for incorporating anisotropy in a forward numerical model for EIT of the head and assess the resulting improvement in image quality in the case of linear reconstruction of one example of the human head. A realistic Finite Element Model (FEM) of an adult human head with segments for the scalp, skull, CSF, and brain was produced from a structural MRI. Anisotropy of the brain was estimated from a diffusion tensor-MRI of the same subject and anisotropy of the skull was approximated from the structural information. A method for incorporation of anisotropy in the forward model and its use in image reconstruction was produced. The improvement in reconstructed image quality was assessed in computer simulation by producing forward data, and then linear reconstruction using a sensitivity matrix approach. The mean boundary data difference between anisotropic and isotropic forward models for a reference conductivity was 50%. Use of the correct anisotropic FEM in image reconstruction, as opposed to an isotropic one, corrected an error of 24 mm in imaging a 10% conductivity decrease located in the hippocampus, improved localisation for conductivity changes deep in the brain and due to epilepsy by 4-17 mm, and, overall, led to a substantial improvement on image quality. This suggests that incorporation of anisotropy in numerical models used for image reconstruction is likely to improve EIT image quality.

Suotautuneen massakakun irtoamisominaisuudet

Tässä työssä tutkittiin suotautuneen massakakun adheesiota teräspinnalle. Muuttujina käytettiin tyypillisiä pesuprosessin arvoja. Lisäksi tutkittiin teollisessa pesulaitteessa massakakun irrotuksessa käytettävän paineilmapulssin käyttäytymistä. Kirjallisuusosassa tarkasteltiin suotautuneen massakakun muodostumista, adheesiota ja adheesioon vaikuttavia tekijöitä massakakun irrotuksen kannalta. Lisäksi massakakun irrotuksessa käytettävän paineilman virtaustatarkasteltiin adiabaattisena virtauksena. Kokeellisen osan irrotuskokeissa tutkittiin suotautuneen massakakun adheesiovoimia teräksisen kartion laitoihin ja reikälevyyn. Kokeissa tutkittiin tyypillisten prosessi-muuttujien kuten lämpötilan, pH:n ja kuiva-ainepitoisuuden vaikutusta tarvittavaan kakun irrotusvoimaan. Lisäksi tutkittiin myös kartion kulman ja pinnanlaadun vaikutusta. Adheesiokokeiden perusteella pystyttiin laskemaan massakakun irrotukseen tarvittava rajapaine teollisen pesulaitteen lokeron suodoskanavassa. Kokeellisen osan paineilmakokeissa tutkittiin irrotuksessa käytettävän paineilman painevaikutusta ja virtausta teollisen pesulaitteen lokerossa ja näihin vaikuttavia rakenteellisten ja prosessiteknisten parametrien vaikutusta. Lisäksi tutkimusta täydennettiin videokuvauksen avulla tutkimalla paineaallon etenemistä merkkiaineen avulla.

An Image Enhancement Technique using MTF of Human eye

Image filtering is a highly demanded approach of image enhancement in digital imaging systems design. It is widely used in television and camera design technologies to improve the quality of an output image to avoid various problems such as image blurring problem thatgains importance in design of displays of large sizes and design of digital cameras. This thesis proposes a new image filtering method basedon visual characteristics of human eye such as MTF. In contrast to the traditional filtering methods based on human visual characteristics this thesis takes into account the anisotropy of the human eye vision. The proposed method is based on laboratory measurements of the human eye MTF and takes into account degradation of the image by the latter. This method improves an image in the way it will be degraded by human eye MTF to give perception of the original image quality. This thesis gives a basic understanding of an image filtering approach and the concept of MTF and describes an algorithm to perform an image enhancement based on MTF of human eye. Performed experiments have shown quite good results according to human evaluation. Suggestions to improve the algorithm are also given for the future improvements.

Electrical source imaging for presurgical focus localization in epilepsy patients with normal MRI.

PURPOSE: Patients with magnetic resonance (MR)-negative focal epilepsy (MRN-E) have less favorable surgical outcomes (between 40% and 70%) compared to those in whom an MRI lesion guides the site of surgical intervention (60-90%). Patients with extratemporal MRN-E have the worst outcome (around 50% chance of seizure freedom). We studied whether electroencephalography (EEG) source imaging (ESI) of interictal epileptic activity can contribute to the identification of the epileptic focus in patients with normal MRI. METHODS: We carried out ESI in 10 operated patients with nonlesional MRI and a postsurgical follow-up of at least 1 year. Five of the 10 patients had extratemporal lobe epilepsy. Evaluation comprised surface and intracranial EEG monitoring of ictal and interictal events, structural MRI, [(18)F]fluorodeoxyglucose positron emission tomography (FDG-PET), ictal and interictal perfusion single photon emission computed tomography (SPECT) scans. Eight of the 10 patients also underwent intracranial monitoring. RESULTS: ESI correctly localized the epileptic focus within the resection margins in 8 of 10 patients, 9 of whom experienced favorable postsurgical outcomes. DISCUSSION: The results highlight the diagnostic value of ESI and encourage broadening its application to patients with MRN-E. If the surface EEG contains fairly localized spikes, ESI contributes to the presurgical decision process.

Sulpun kuvantaminen painelajittelussa

Painelajittelussa sellusta poistetaan epäpuhtauksia. Painelajittimien suunnittelussa on tärkeää ymmärtää lajittimessa tapahtuvia ilmiöitä. Työn tavoitteena oli kehittää kuvaamiseen perustuva mittausjärjestelmä kuitujen liikkeiden mittaamista varten. Mittauksen kohteena ovat sellusulpun kuitujen ja epäpuhtauksien nopeudet. Kuvaamisessa käytetyllä kaksoisvalotuksella pystytään mittaamaan kuitujen ja roskien nopeuksia. Nopeuksien mittaamiseen kuvista kehitettiin järjestelmä ja tutkittiin mahdollisuutta automatisoida mittaaminen. Yksittäisten kuitujen havaitsemiseen sellumassasta käytettiin optisella kirkasteella kirkastettuja kuituja ja UV-valoa. Kuituja värjättiin myös mustiksi ja kuvattiin näkyvällä valolla. Kaksoisvalotukseen käytettiin kahta stroboskooppia. Prosessin kuvaamisessa käytettiin ulkoisella herätteellä ohjattavaa kameraa. Kuvan tuomiseen kameralle ja kohteen valaistukseen käytettiin boroskooppia. Saatujen kuvien käsittelyä ja nopeuksien mittausta varten tehtiin tietokoneohjelma. Käytetyn boroskoopin valovoima ei ollut riittävä kuvausten suorittamiseen, mutta muilta osin laitteisto havaittiin toimivaksi. Kuitujen ja roskien nopeuksia pystyttiin laskemaan ohjelmalla kuvista, joita otettiin ilman boroskooppia. Mittaustiedon hankinnan automatisointi näyttää mahdolliselta tekemällä muutoksia kuvauslaitteistoon.

FDG PET and MR imaging in patients with liver metastases from uveal melanoma : results from a pilot study

Le présent travail a eu comme but la comparaison de la performance de deux méthodes d'imagerie diagnostique pour la détection de métastases hépatiques du mélanome uvéal : la tomographie d'émission par positons au F-18-fluorodésoxyglucose (TEP FDG) couplée à la tomodensitométrie (TDM) et l'imagerie par résonance magnétique (IRM). Dans cette étude rétrospective, nous avons analysé les données radiologiques de patients inclus dans une étude multicentrique randomisée de phase III de l'Uveal Melanoma Group of the European Organization for Research and Treatment of Cancer (EORTC). L'IRM s'est révélée nettement plus sensible que le FDG-PET/CT pour mettre en évidence les métastases hépatiques notamment de taille infra-centimétrique. Néanmoins, l'analyse des changements de l'accumulation du traceur métabolique par les métastases hépatiques au cours du traitement suggère la possibilité d'évaluer, de manière précoce, la réponse des métastases hépatiques à la chimiothérapie. Le nombre de cas étudiés est trop faible pour déterminer la précision et la valeur clinique d'une telle évaluation mais les résultats obtenus dans cette étude pilote justifient une étude plus étendue.

Investigation of discrete imaging models and iterative image reconstruction in differential X-ray phase-contrast tomography.

Differential X-ray phase-contrast tomography (DPCT) refers to a class of promising methods for reconstructing the X-ray refractive index distribution of materials that present weak X-ray absorption contrast. The tomographic projection data in DPCT, from which an estimate of the refractive index distribution is reconstructed, correspond to one-dimensional (1D) derivatives of the two-dimensional (2D) Radon transform of the refractive index distribution. There is an important need for the development of iterative image reconstruction methods for DPCT that can yield useful images from few-view projection data, thereby mitigating the long data-acquisition times and large radiation doses associated with use of analytic reconstruction methods. In this work, we analyze the numerical and statistical properties of two classes of discrete imaging models that form the basis for iterative image reconstruction in DPCT. We also investigate the use of one of the models with a modern image reconstruction algorithm for performing few-view image reconstruction of a tissue specimen.

Comparaison objective de systèmes d'imagerie conventionnelle et numérique en mammographie

L'objectif de ce travail est le développement d'une méthode de caractérisation objective de la qualité d'image s'appliquant à des systèmes de mammographie analogique, utilisant un couple écran-film comme détecteur, et numérique, basé sur une technologie semi-conductrice, ceci en vue de la comparaison de leurs performances. La méthode développée tient compte de la gamme dynamique du détecteur, de la détectabilité de structures de haut contraste, simulant des microcalcifications, et de structures de bas contraste, simulant des opacités (nodules tumoraux). La méthode prend également en considération le processus de visualisation de l'image, ainsi que la réponse de l'observateur. Pour réaliser ceci, un objet-test ayant des propriétés proches de celles d'un sein comprimé, composé de différents matériaux équivalents aux tissus, allant du glandulaire à l'adipeux, et comprenant des zones permettant la simulation de structures de haut et bas contraste, ainsi que la mesure de la résolution et celle du bruit, a été développé et testé. L'intégration du processus de visualisation a été réalisée en utilisant une caméra CCD mesurant directement les paramètres de qualité d'image, à partir de l'image de l'objet-test, dans une grandeur physique commune au système numérique et analogique, à savoir la luminance arrivant sur l'oeil de l'observateur. L'utilisation d'une grandeur synthétique intégrant dans un même temps, le contraste, le bruit et la résolution rend possible une comparaison objective entre les deux systèmes de mammographie. Un modèle mathématique, simulant la réponse d'un observateur et intégrant les paramètres de base de qualité d'image, a été utilisé pour calculer la détectabilité de structures de haut et bas contraste en fonction du type de tissu sur lequel celles-ci se trouvent. Les résultats obtenus montrent qu'à dose égale la détectabilité des structures est significativement plus élevée avec le système de mammographie numérique qu'avec le système analogique. Ceci est principalement lié au fait que le bruit du système numérique est plus faible que celui du système analogique. Les résultats montrent également que la méthodologie, visant à comparer des systèmes d'imagerie numérique et analogique en utilisant un objet-test à large gamme dynamique ainsi qu'une caméra, peut être appliquée à d'autres modalités radiologiques, ainsi qu'à une démarche d'optimisation des conditions de lecture des images.<br/><br/>The goal of this work was to develop a method to objectively compare the performance of a digital and a screen-film mammography system in terms of image quality and patient dose. We propose a method that takes into account the dynamic range of the image detector and the detection of high contrast (for microcalcifications) and low contrast (for masses or tumoral nodules) structures. The method also addresses the problems of image visualization and the observer response. A test object, designed to represent a compressed breast, was constructed from various tissue equivalent materials ranging from purely adipose to purely glandular composition. Different areas within the test object permitted the evaluation of low and high contrast detection, spatial resolution, and image noise. All the images (digital and conventional) were captured using a CCD camera to include the visualization process in the image quality assessment. In this way the luminance reaching the viewer?s eyes can be controlled for both kinds of images. A global quantity describing image contrast, spatial resolution and noise, and expressed in terms of luminance at the camera, can then be used to compare the two technologies objectively. The quantity used was a mathematical model observer that calculates the detectability of high and low contrast structures as a function of the background tissue. Our results show that for a given patient dose, the detection of high and low contrast structures is significantly better for the digital system than for the conventional screen-film system studied. This is mainly because the image noise is lower for the digital system than for the screen-film detector. The method of using a test object with a large dynamic range combined with a camera to compare conventional and digital imaging modalities can be applied to other radiological imaging techniques. In particular it could be used to optimize the process of radiographic film reading.

Development of a hepatocyte hollow fiber bioreactor for the study of contrast agents by magnetic resonance imaging

Thanks to the continuous progress made in recent years, medical imaging has become an important tool in the diagnosis of various pathologies. In particular, magnetic resonance imaging (MRI) permits to obtain images with a remarkably high resolution without the use of ionizing radiation and is consequently widely applied for a broad range of conditions in all parts of the body. Contrast agents are used in MRI to improve tissue discrimination. Different categories of contrast agents are clinically available, the most widely used being gadolinium chelates. One can distinguish between extracellular gadolinium chelates such as Gd-DTPA, and hepatobiliary gadolinium chelates such as Gd-BOPTA. The latter are able to enter hepatocytes from where they are partially excreted into the bile to an extent dependent on the contrast agent and animal species. Due to this property, hepatobiliary contrast agents are particularly interesting for the MRI of the liver. Actually, a change in signal intensity can result from a change in transport functions signaling the presence of impaired hepatocytes, e.g. in the case of focal (like cancer) or diffuse (like cirrhosis) liver diseases. Although the excretion mechanism into the bile is well known, the uptake mechanisms of hepatobiliary contrast agents into hepatocytes are still not completely understood and several hypotheses have been proposed. As a good knowledge of these transport mechanisms is required to allow an efficient diagnosis by MRI of the functional state of the liver, more fundamental research is needed and an efficient MRI compatible in vitro model would be an asset. So far, most data concerning these transport mechanisms have been obtained by MRI with in vivo models or by a method of detection other than MRI with cellular or sub-cellular models. Actually, no in vitro model is currently available for the study and quantification of contrast agents by MRI notably because high cellular densities are needed to allow detection, and no metallic devices can be used inside the magnet room, which is incompatible with most tissue or cell cultures that require controlled temperature and oxygenation. The aim of this thesis is thus to develop an MRI compatible in vitro cellular model to study the transport of hepatobiliary contrast agents, in particular Gd-BOPTA, into hepatocytes directly by MRI. A better understanding of this transport and especially of its modification in case of hepatic disorder could permit in a second step to extrapolate this knowledge to humans and to use the kinetics of hepatobiliary contrast agents as a tool for the diagnosis of hepatic diseases.

GIS and geodatabases application to global scale plate tectonics modelling

Les reconstructions palinspastiques fournissent le cadre idéal à de nombreuses études géologiques, géographiques, océanographique ou climatiques. En tant qu?historiens de la terre, les "reconstructeurs" essayent d?en déchiffrer le passé. Depuis qu?ils savent que les continents bougent, les géologues essayent de retracer leur évolution à travers les âges. Si l?idée originale de Wegener était révolutionnaire au début du siècle passé, nous savons depuis le début des années « soixante » que les continents ne "dérivent" pas sans but au milieu des océans mais sont inclus dans un sur-ensemble associant croûte « continentale » et « océanique »: les plaques tectoniques. Malheureusement, pour des raisons historiques aussi bien que techniques, cette idée ne reçoit toujours pas l'écho suffisant parmi la communauté des reconstructeurs. Néanmoins, nous sommes intimement convaincus qu?en appliquant certaines méthodes et certains principes il est possible d?échapper à l?approche "Wégenerienne" traditionnelle pour enfin tendre vers la tectonique des plaques. Le but principal du présent travail est d?exposer, avec tous les détails nécessaires, nos outils et méthodes. Partant des données paléomagnétiques et paléogéographiques classiquement utilisées pour les reconstructions, nous avons développé une nouvelle méthodologie replaçant les plaques tectoniques et leur cinématique au coeur du problème. En utilisant des assemblages continentaux (aussi appelés "assemblées clés") comme des points d?ancrage répartis sur toute la durée de notre étude (allant de l?Eocène jusqu?au Cambrien), nous développons des scénarios géodynamiques permettant de passer de l?une à l?autre en allant du passé vers le présent. Entre deux étapes, les plaques lithosphériques sont peu à peu reconstruites en additionnant/ supprimant les matériels océaniques (symbolisés par des isochrones synthétiques) aux continents. Excepté lors des collisions, les plaques sont bougées comme des entités propres et rigides. A travers les âges, les seuls éléments évoluant sont les limites de plaques. Elles sont préservées aux cours du temps et suivent une évolution géodynamique consistante tout en formant toujours un réseau interconnecté à travers l?espace. Cette approche appelée "limites de plaques dynamiques" intègre de multiples facteurs parmi lesquels la flottabilité des plaques, les taux d'accrétions aux rides, les courbes de subsidence, les données stratigraphiques et paléobiogéographiques aussi bien que les évènements tectoniques et magmatiques majeurs. Cette méthode offre ainsi un bon contrôle sur la cinématique des plaques et fournit de sévères contraintes au modèle. Cette approche "multi-source" nécessite une organisation et une gestion des données efficaces. Avant le début de cette étude, les masses de données nécessaires était devenues un obstacle difficilement surmontable. Les SIG (Systèmes d?Information Géographiques) et les géo-databases sont des outils informatiques spécialement dédiés à la gestion, au stockage et à l?analyse des données spatialement référencées et de leurs attributs. Grâce au développement dans ArcGIS de la base de données PaleoDyn nous avons pu convertir cette masse de données discontinues en informations géodynamiques précieuses et facilement accessibles pour la création des reconstructions. Dans le même temps, grâce à des outils spécialement développés, nous avons, tout à la fois, facilité le travail de reconstruction (tâches automatisées) et amélioré le modèle en développant fortement le contrôle cinématique par la création de modèles de vitesses des plaques. Sur la base des 340 terranes nouvellement définis, nous avons ainsi développé un set de 35 reconstructions auxquelles est toujours associé un modèle de vitesse. Grâce à cet ensemble de données unique, nous pouvons maintenant aborder des problématiques majeurs de la géologie moderne telles que l?étude des variations du niveau marin et des changements climatiques. Nous avons commencé par aborder un autre problème majeur (et non définitivement élucidé!) de la tectonique moderne: les mécanismes contrôlant les mouvements des plaques. Nous avons pu observer que, tout au long de l?histoire de la terre, les pôles de rotation des plaques (décrivant les mouvements des plaques à la surface de la terre) tendent à se répartir le long d'une bande allant du Pacifique Nord au Nord de l'Amérique du Sud, l'Atlantique Central, l'Afrique du Nord, l'Asie Centrale jusqu'au Japon. Fondamentalement, cette répartition signifie que les plaques ont tendance à fuir ce plan médian. En l'absence d'un biais méthodologique que nous n'aurions pas identifié, nous avons interprété ce phénomène comme reflétant l'influence séculaire de la Lune sur le mouvement des plaques. La Lune sur le mouvement des plaques. Le domaine océanique est la clé de voute de notre modèle. Nous avons attaché un intérêt tout particulier à le reconstruire avec beaucoup de détails. Dans ce modèle, la croûte océanique est préservée d?une reconstruction à l?autre. Le matériel crustal y est symbolisé sous la forme d?isochrones synthétiques dont nous connaissons les âges. Nous avons également reconstruit les marges (actives ou passives), les rides médio-océaniques et les subductions intra-océaniques. En utilisant ce set de données très détaillé, nous avons pu développer des modèles bathymétriques 3-D unique offrant une précision bien supérieure aux précédents.<br/><br/>Palinspastic reconstructions offer an ideal framework for geological, geographical, oceanographic and climatology studies. As historians of the Earth, "reconstructers" try to decipher the past. Since they know that continents are moving, geologists a trying to retrieve the continents distributions through ages. If Wegener?s view of continent motions was revolutionary at the beginning of the 20th century, we know, since the Early 1960?s that continents are not drifting without goal in the oceanic realm but are included in a larger set including, all at once, the oceanic and the continental crust: the tectonic plates. Unfortunately, mainly due to technical and historical issues, this idea seems not to receive a sufficient echo among our particularly concerned community. However, we are intimately convinced that, by applying specific methods and principles we can escape the traditional "Wegenerian" point of view to, at last, reach real plate tectonics. This is the main aim of this study to defend this point of view by exposing, with all necessary details, our methods and tools. Starting with the paleomagnetic and paleogeographic data classically used in reconstruction studies, we developed a modern methodology placing the plates and their kinematics at the centre of the issue. Using assemblies of continents (referred as "key assemblies") as anchors distributed all along the scope of our study (ranging from Eocene time to Cambrian time) we develop geodynamic scenarios leading from one to the next, from the past to the present. In between, lithospheric plates are progressively reconstructed by adding/removing oceanic material (symbolized by synthetic isochrones) to major continents. Except during collisions, plates are moved as single rigid entities. The only evolving elements are the plate boundaries which are preserved and follow a consistent geodynamical evolution through time and form an interconnected network through space. This "dynamic plate boundaries" approach integrates plate buoyancy factors, oceans spreading rates, subsidence patterns, stratigraphic and paleobiogeographic data, as well as major tectonic and magmatic events. It offers a good control on plate kinematics and provides severe constraints for the model. This multi-sources approach requires an efficient data management. Prior to this study, the critical mass of necessary data became a sorely surmountable obstacle. GIS and geodatabases are modern informatics tools of specifically devoted to store, analyze and manage data and associated attributes spatially referenced on the Earth. By developing the PaleoDyn database in ArcGIS software we converted the mass of scattered data offered by the geological records into valuable geodynamical information easily accessible for reconstructions creation. In the same time, by programming specific tools we, all at once, facilitated the reconstruction work (tasks automation) and enhanced the model (by highly increasing the kinematic control of plate motions thanks to plate velocity models). Based on the 340 terranes properly defined, we developed a revised set of 35 reconstructions associated to their own velocity models. Using this unique dataset we are now able to tackle major issues of the geology (such as the global sea-level variations and climate changes). We started by studying one of the major unsolved issues of the modern plate tectonics: the driving mechanism of plate motions. We observed that, all along the Earth?s history, plates rotation poles (describing plate motions across the Earth?s surface) tend to follow a slight linear distribution along a band going from the Northern Pacific through Northern South-America, Central Atlantic, Northern Africa, Central Asia up to Japan. Basically, it sighifies that plates tend to escape this median plan. In the absence of a non-identified methodological bias, we interpreted it as the potential secular influence ot the Moon on plate motions. The oceanic realms are the cornerstone of our model and we attached a particular interest to reconstruct them with many details. In this model, the oceanic crust is preserved from one reconstruction to the next. The crustal material is symbolised by the synthetic isochrons from which we know the ages. We also reconstruct the margins (active or passive), ridges and intra-oceanic subductions. Using this detailed oceanic dataset, we developed unique 3-D bathymetric models offering a better precision than all the previously existing ones.

Studies on the characterization of dental whitening process by using both hyperspectral imaging and colorimeter techniques

A beautiful smile is directly related with white teeth. Nowadays oral care has increased and developed processes for beautiful smiles. Dental bleaching is frequently used in odontology, not just for health care also for aesthetic treatment. With the possibility of teeth bleaching, now the importance is in, how white the tooth is? Because color is relate to an individual perception. In order to assets teeth correct color identification has been developed many color guides, models, spaces and analytical methods. Spite all of these useful tools the color interpretation depends on environmental factors, position of the sample in the data acquisition and most importantly the instrument sensitivity. The commons methods have proved to be useful. They are easy to handle, some are portable but they do not have a high sensitivity. The present work is based on the integration of a new analytical technique for color acquisition. High spectral Image (HSI) is able to performed image analysis with high quality and efficiency. HSI is used in many fields and we used it for color image analysis within the bleaching process. The main comparison was done with the HSI and the colorimeter through the processes of two different bleaching protocols. The results showed that HSI has higher sensitivity than the colorimeter. During the analysis the dental surface with the HSI we were able to notice surface changes. These changes were analyzed by roughness studies.

Transfer entropy reconstruction and labeling of neuronal connections from simulated calcium imaging

Neuronal dynamics are fundamentally constrained by the underlying structural network architecture, yet much of the details of this synaptic connectivity are still unknown even in neuronal cultures in vitro. Here we extend a previous approach based on information theory, the Generalized Transfer Entropy, to the reconstruction of connectivity of simulated neuronal networks of both excitatory and inhibitory neurons. We show that, due to the model-free nature of the developed measure, both kinds of connections can be reliably inferred if the average firing rate between synchronous burst events exceeds a small minimum frequency. Furthermore, we suggest, based on systematic simulations, that even lower spontaneous inter-burst rates could be raised to meet the requirements of our reconstruction algorithm by applying a weak spatially homogeneous stimulation to the entire network. By combining multiple recordings of the same in silico network before and after pharmacologically blocking inhibitory synaptic transmission, we show then how it becomes possible to infer with high confidence the excitatory or inhibitory nature of each individual neuron.