The Deglaciation of Maine, USA

The glacial geology of Maine records the northward recession of the Late Wisconsinan Laurentide Ice Sheet, followed by development of a residual ice cap in the Maine-Québec border region due to marine transgression of the St. Lawrence Lowland in Canada. The pattern of deglaciation across southern Maine has been reconstructed from numerous end moraines, deltas and submarine fans deposited during marine transgression of the coastal lowland. Inland from the marine limit, a less-detailed sequence of deglaciation is recorded by striation patterns, meltwater channels, scattered moraines and waterlain deposits that constrain the trend of the ice margin. There is no evidence that the northern Maine ice cap extended as far south-west as the Boundary Mountains and New Hampshire border. Newly-obtained radiocarbon ages from marine and terrestrial ice-proximal environments have improved the chronology of glacial recession in Maine. Many of these ages were obtained by coring late-glacial sediments beneath ponds and lakes. Data from this study show that the state was deglaciated between about 14.5 and 11.0 ka BP (14C years). The coastal moraine belt in southern Maine was deposited by oscillatory ice-margin retreat during the cold pre-Bølling time. Rapid ice recession to northern Maine then occurred between 13 and 11 ka BP, during the warmer Bølling/Allerød chronozones. Radiocarbon-dated pond sediments in western and northern Maine show lithologic evidence of Younger Dryas climatic cooling and persistence of the northern ice cap into Younger Dryas time. A large discrepancy still exists between radiocarbon ages of deglaciation in coastal south-western Maine and the timing of ice retreat indicated by New England varve records in areas to the west. Part of this problem may stem from the uncertainty of reservoir corrections applied to the radiocarbon ages of marine organics

Capturing MSO with One Quantifier

International audienceWe construct a single Lindström quantifier Q such that FO(Q), the extension of first-order logic with Q has the same expressive power as monadic second-order logic on the class of binary trees (with distinct left and right successors) and also on unranked trees with a sibling order. This resolves a conjecture by ten Cate and Segoufin. The quantifier Q is a variation of a quantifier expressing the Boolean satisfiability problem

An alternative application to the portuguese agro-industrial residue : wheat straw

The effects of alkaline treatments of the wheat straw with sodium hydroxide were investigated. The optimal condition for extraction of hemicelluloses was found to be with 0.50 mol/l sodium hydroxide at 55 °C for 2 h. This resulted in the release of 17.3% of hemicellulose (% dry starting material), corresponding to the dissolution of 49.3% of the original hemicellulose. The yields were determined by gravimetric analysis and expressed as a proportion of the starting material. Chemical composition and physico-chemical properties of the samples of hemicelluloses were elucidated by a combination of sugar analyses, Fourier transform infrared (FTIR), and thermal analysis. The results showed that the treatments were very effective on the extraction of hemicelluloses from wheat straw and that the extraction intensity (expressed in terms of alkali concentration) had a great influence on the yield and chemical features of the hemicelluloses. The FTIR analysis revealed typical signal pattern for the hemicellulosic fraction in the 1,200–1,000 cm−1 region. Bands between 1,166 and 1,000 cm−1 are typical of xylans.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo a Pesquisa do Estado de São Paulo/Brazil (FAPESP)Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BPD/26156/2005, SFRH/BPD/26108/200