Stochastic Uncertainty Quantification of the Conductivity in EEG Source Analysis by Using Polynomial Chaos Decomposition

in IEEE Transactions on Magnetics (2010), 46(8), 3457-3460

The electroencephalogram (EEG) is one of the techniques used for the non-invasive diagnosis of patients suffering from epilepsy. EEG source localization identifies the neural activity, starting from ... [more ▼]

The electroencephalogram (EEG) is one of the techniques used for the non-invasive diagnosis of patients suffering from epilepsy. EEG source localization identifies the neural activity, starting from measured EEG. This numerical localization procedure has a resolution, which is difficult to determine due to uncertainties in the EEG forward models. More specifically, the conductivities of the brain and the skull in the head models are not precisely known. In this paper, we propose the use of a non-intrusive stochastic method based on a polynomial chaos decomposition for quantifying the possible errors introduced by the uncertain conductivities of the head tissues. The accuracy and computational advantages of this non-intrusive method for EEG source analysis is illustrated. Further, the method is validated by means of Monte Carlo simulations. [less ▲]

Stockage de bois chablis sous bâche

in Infos de RND (Les) (2013, March), (1er semestre), 3-5

Le samedi 24 janvier 2009, la tempête Klaus traverse le sud-ouest de la France. Tempête la plus dévastatrice depuis 1999, la forêt des Landes et ses pins maritimes paient un lourd tribut à ce phénomène ... [more ▼]

Le samedi 24 janvier 2009, la tempête Klaus traverse le sud-ouest de la France. Tempête la plus dévastatrice depuis 1999, la forêt des Landes et ses pins maritimes paient un lourd tribut à ce phénomène extrême: 60% de la superficie est touchée, environ 40 millions de m3 de bois sont à terre, quatre fois la récolte annuelle. Il faudra attendre plusieurs mois avant que les aires de stockage par aspersion soient opérationnelles. Trop tard, le pin maritime montre déjà des signes de bleuissement de son bois, il est invendable sur les marchés à forte valeur ajoutée, là où l’esthétisme prime. Écarté des meilleurs débouchés, le lambris et le plancher, le manque à gagner est énorme. Un tel scénario catastrophe, notre région s’y prépare depuis 2005, tirant les enseignements des expériences étrangères et fondant son action sur les spécificités de notre forêt, de notre filière. C’est dans ce cadre que le 28 février dernier, à Eupen, des grumes d’épicéa stockées depuis presque cinq ans ont été extraites des bâches hermétiques qui les protégeaient. Comment le bois est-il ressorti de cette épreuve? Que penser de cette méthode alternative de stockage? Quelle place lui réserver ? Benoit Jourez du Laboratoire de Technologie du Bois du DEMNA (Département de l’Étude du milieu naturel et agricole) nous a apporté son éclairage et nous a conviés à l’ouverture de la poche étanche. Entre supputations et réalité des bois extraits après cinq ans, suspense… [less ▲]

Stockage de carbone et flux de gaz à effet de serre en prairie (synthèse bibliographique)

in Biotechnologie, Agronomie, Société et Environnement = Biotechnology, Agronomy, Society and Environment [=BASE] (2013), 17(1), 103-117

Grassland carbon (C) sequestration can play an important role in mitigating total greenhouse gas (GHG) emissions of livestock production systems. An accurate inventory of livestock production system ... [more ▼]

Grassland carbon (C) sequestration can play an important role in mitigating total greenhouse gas (GHG) emissions of livestock production systems. An accurate inventory of livestock production system contribution to GHG emissions requires to think in terms of global budget, by considering both the GHG sources and the mitigation potential trough grassland soil carbon sequestration. There is a huge variability in C and GHG balances of grasslands that is mainly due to management practices and climatic conditions. The present article shows that, to reduce the uncertainties of the results, long term measurements at the field scale are necessary. Also, it shows the importance of taking the fluxes of the three main GHGs (carbon dioxide, nitrous oxide, methane) into account when calculating the GHG budget. This article also highlights the need for a better understanding of the mechanisms driving the fluxes, in relation to environmental factors and management practices, in order to propose mitigation strategies able to enhance soil carbon sequestration in soils and to reduce methane and nitrous oxide emissions. [less ▲]

Le stockage post-récolte : une étape clé du processus de production.

in Troupeaux et Cultures des Tropiques (2004), 4

Le stockage thermique par chaleur latente

in Nouvelles de la Science et des Technologies (1988), 6

L'article présente le principe du stockage d'énergie par transformation de phase ainsi que les matériaux employés (composés organiques, sels hydratés et matériaux à transformation solide-solide) et les ... [more ▼]

L'article présente le principe du stockage d'énergie par transformation de phase ainsi que les matériaux employés (composés organiques, sels hydratés et matériaux à transformation solide-solide) et les différents types d'échangeurs. [less ▲]

Stocks and fluxes of metals in a Luvisol of a contaminated suburban field.

Poster (2003, June)

Stomatal regulation in greenhouse crops

in Acta Horticulturae (1989), 248

We study the impact of the stomatal opening variations on the transpiration of the entire canopy in protected crops cultivation. Three effects contribute to a reduction of this impact: a damping effect ... [more ▼]

We study the impact of the stomatal opening variations on the transpiration of the entire canopy in protected crops cultivation. Three effects contribute to a reduction of this impact: a damping effect due to the boundary layer adhering to the leaf, a thermal negative feedback effect linked to the energy balance and a hydric negative feedback effect linked to the water balance. Summing up these effects gives a coupling factor between the relative stomatal conductance changes and the relative transpiration rate modifications. Detailed expression of the coupling factor is established in the frame of a dynamic greenhouse climatic model (GGDM) and its value is calculated for typical days of a temperate climate. The results show that large stomatal conductances are poorly effective in the control of the canopy transpiration (coupling factor =.1 ). Significant values of the coupling factor are only obtained for very small stomatal conductances (gST < 10-3 ) . These values are independant of the climatic conditions but are strongly affected by the development stage of the vegetation. [less ▲]

Stone tool hafting in the Middle Palaeolithic as viewed through the microscope

in Proceedings of the Use-wear conference at Faro, Portugal (in press)

Stop, look and listen: The need for philosophical phenomenological perspectives on auditory verbal hallucinations

in Frontiers in Human Neuroscience (in press)

Storage Iron Kinetics. VII. A biologic Model for Reticulo-Endothelial Iron Transport

in Journal of Clinical Investigation (1974), 53

The processing of erythrocyte iron by the reticuloendothelial cell has been characterized by kinetic measurements of blood radioactivity made after the intravenous injection of heat-damaged erythrocytes ... [more ▼]

The processing of erythrocyte iron by the reticuloendothelial cell has been characterized by kinetic measurements of blood radioactivity made after the intravenous injection of heat-damaged erythrocytes labeled with 59Fe and of transferrin-bound 55Fe. The early reticuloendothelial release of iron, a matter of hours, was calculated from the plasma turnover rate of 55Fe and the plasma reappearance of 59Fe. Late release was calculated from the ratio of the cumulative incorporation of both tracers into the circulating red cell mass over a period of 2wk. There was an initial processing period within the reticuloendothelial cell, after which radioiron either rapidly returned to circulation (t 34 min) or was transferred to a slowly exchanging pool of storage iron within the reticuloendothelial cell (t release to plasma of 7 days). These pathways were of equal magnitude in the normal dog. Reticuloendothelial release of iron was largely independent of the pre-existing plasma iron level or transferrin saturation. Diurnal fluctuations in the plasma iron level were shown to be the result of a variable partitioning of iron between the early and late release phases. Acute inflammation resulted in a prompt and marked increase in the fraction of iron stored (late phase), whereas depletion of iron stores resulted in a marked increase in early release. [less ▲]