Seismic stratigraphy records the deglacial history of Jakobshavn Isbrae, West Greenland

Jakobshavn Isbræ is one of the largest ice streams in the Greenland Ice Sheet, presently draining c. 6.5% of the Inland Ice. Here we present high-resolution Chirp and Sparker sub-bottom profiles from a seismic survey conducted just outside of the Jakobshavn Isfjord, which provides detailed insight into the glacimarine sedimentary history of the Jakobshavn ice stream during the Holocene. We observe acoustically stratified and homogeneous sediments that drape an irregular substratum and were deposited between ∼10 and c. 7.6k cal a BP. The stratified lower units are interpreted as the product of ice-proximal glacimarine sedimentation deposited rapidly when the grounded ice margin was located close to depositional basins on topographic highs. The upper acoustically homogenous units reflect suspension settling of fine-grained material and gravitational flows that were extruded from an increasingly unstable ice margin as the ice retreated into the fjord. Proximity to the ice margin and bedrock topography were the dominant controls on sediment accumulation during deglaciation although the 8.2-ka cooling event probably influenced the position of the ice margin at the fjord mouth. The post-glacial sedimentary record is characterized by glacimarine and hemipelagic rainout with an increased ice-rafted detritus fraction that records sedimentation following ice stream retreat into Jakobshavn Isfjord sometime after c. 7.8k cal a BP

Disjunctive Logic Programming: A Survey And Assessment

We describe the elds of disjunctive logic programming and disjunctive deductive databases from the time of their inception to the current time. Contributions with respect to semantics, implementations and applications are surveyed

Novos registros de Hyphomycetes decompositores para o Estado da Bahia, Brasil

Folhas mortas de Clusia melchiorii Gleason e C. nemorosa G. Mey. foram coletadas bimestralmente na Serra da Jibóia, Bahia, no período de outubro/2005 a junho/2006. As folhas foram lavadas em água corrente e mantidas em câmara-úmida durante 30 dias. As estruturas fúngicas foram coletadas e montadas em lâminas permanentes. São apresentadas descrições e ilustrações de sete novos registros de Hyphomycetes para o Estado da Bahia [Beltrania querna Harkn., Clonostachys compactiuscula (Sacc.) D. Hawksw. & W. Gams, Dictyosporium elegans Corda, Gyrothrix verticiclada (Goid.) S. Hughes & Piroz., Pseudobotrytis terrestris (Timonin) Subram., Sporendocladia bactrospora (W.B. Kendr.) M.J. Wingf. e Stachybotrys parvispora S. Hughes]