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The ability to distinguish peatland types at the landscape scale has implications for inventory, conservation, estimation of carbon storage, fuel loading, and postfire carbon emissions, among others. This paper presents a multisensor, multiseason remote sensing approach to delineate boreal peatland types (wooded bog, open fen, shrubby fen, treed fen) using a combination of multiple dates of L-band (24 cm) synthetic aperture radar (SAR) from ALOS PALSAR, C-band (~5.6 cm) from ERS-1 or ERS-2, and Landsat 5 TM optical remote sensing data. Imagery was first evaluated over a small test area of boreal Alberta, Canada, to determine the feasibility of using multisensor SAR and optical data to discriminate peatland types. Then object-based and (or) machine-learning classification algorithms were applied to 3.4 million ha of peatland-rich subregions of Alberta, Canada, and the 4.24 million ha region of Michigan's Upper Peninsula where peatlands are less dominant. Accuracy assessments based on field-sampled sites show high overall map accuracies (93%-94% for Alberta and Michigan), which exceed those of previous mapping efforts. Key words: peatlands, fens, bogs, boreal, synthetic aperture radar, SAR, Landsat, PALSAR, ERS-2, Random Forests, mapping. La capacite de distinguer les types de tourbieres a l'echelle du paysage a des repercussions notamment sur l'inventaire, la conservation, l'estimation de la sequestration du carbone, la charge de combustible et les emissions de carbone apres un feu. Cet article presente une approche de teledetection multi-capteur et multi-saison pour delimiter les differents types de tourbieres boreales (tourbieres ombrotrophes boisees, tourbieres minerotrophes ouvertes, arbustives ou arborees) a l'aide d'une combinaison de donnees de teledetection multi-temporelles du radar a synthese d'ouverture (SAR) en bande L (24 cm) du satellite ALOS PALSAR et en bande C (~5,6 cm) du satellite ERS-1 ou ERS-2 ainsi que de donnees optiques du satellite Landsat 5 TM. L'imagerie a d'abord ete evaluee sur une superficie experimentale limitee dans le nord de l'Alberta, au Canada, pour determiner la faisabilite d'utiliser le SAR multi-capteur et des donnees optiques pour distinguer les types de tourbieres. Ensuite, des algorithmes de classification fondes sur les objets ou l'apprentissage automatique ont ete appliques a 3,4 millions ha de sous-regions de l'Alberta, au Canada, riches en tourbieres et a la region de 4,24 millions ha de la peninsule superieure du Michigan ou les tourbieres sont moins dominantes. Les evaluations de la precision fondees sur les sites echantillonnes au sol montrent des precisions cartographiques globales elevees (93-94 % pour l'Alberta et le Michigan) qui depassent celles des essais anterieurs de cartographies. [Traduit par la Redaction] Mots-cles: tourbieres, tourbieres minerotrophes, tourbieres ombrotrophes, boreal, radar a synthese d'ouverture, (SAR), Landsat, PALSAR, ERS-2, forets aleatoires, cartographie., Introduction Peatlands are defined as having saturated soils, anaerobic conditions, and large accumulations of partially decomposed organic plant material (peat) below the ground. This accumulation is a result of low [...]

We report the results of a multichannel seismic study on eastern Central Atlantic oceanic crust. Unmigrated and migrated sections have been used to identify the main seismic boundaries within the crust. The upper crust generally is seismically transparent except for a 20-km-long continuous reflection, which we interpret as associated with a long-lived normal fault in the basement and with hydrothermal circulation. Short and discontinuous reflections in the upper crust have also been observed. The lower crust is either transparent or variably reflective in form of subhorizontal layered reflection packages and/or dipping reflections. The reflectivity patterns are interpreted as magmatic in origin except for the dipping reflections that affect the whole crust, which are interpreted as expressions of extensional faults. The reflections dipping ridgeward are thought to have acted as detachment surfaces where plate separation took place. The Moho has been identified along most of the length of the seismic profiles either as the base of the reflective lower crust or as a sharp single reflection. The igneous crust shows large variations in thickness sometimes associated with fracture zones in the Cretaceous crust. Fracture zones in the Jurassic crust do not show, in general, a crustal thinning. This may be due to different accretionary processes during Jurassic and Cretaceous times.

Explicit expressions of the Hosoya polynomials of some classes of graphs are known. In this paper we find an explicit expression for the Hosoya polynomial of the multibridge graph. Finally we give some examples of multi-bridge graphs which are chemical graphs. [ABSTRACT FROM AUTHOR]