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Although a growing literature highlights sex differences in autism spectrum disorder clinical presentation, less is known about female variants at the neural level. We investigated sex-related patterns of functional connectivity within and between functional networks in children and adolescents with autism spectrum disorders, compared to typically developing peers. Resting-state functional magnetic resonance imaging data for 141 children and adolescents (7-17 years) selected from an in-house sample and four sites contributing to the Autism Brain Imaging Database Exchange (ABIDE I and II) were submitted to group independent component analysis to generate resting-state functional networks. Functional connectivity was estimated by generating resting-state functional network correlation matrices, which were directly compared between males and females, and autism spectrum disorder and typically developing groups. Results revealed greater connectivity within the default mode network in typically developing girls as compared to typically developing boys, while no such sex effect was observed in the autism spectrum disorder group. Correlational analyses with clinical indices revealed a negative relationship between sensorimotor connectivity and history of early autism symptoms in girls, but not in boys with autism spectrum disorder. A lack of neurotypical sex differentiation in default mode network functional connectivity observed in boys and girls with autism spectrum disorder suggests that sex-related differences in network integration may be altered in autism spectrum disorder.

Uranium (U) concentrations and activity ratios (δ234U) of authigenic carbonates are sensitive recorders of different fluid compositions at submarine seeps of hydrocarbon-rich fluids (“cold seeps”) at Hydrate Ridge, off the coast of Oregon, USA. The low U concentrations (mean: 1.3 ± 0.4 μg/g) and high δ234U values (165–317‰) of gas hydrate carbonates reflect the influence of sedimentary pore water indicating that these carbonates were formed under reducing conditions below or at the seafloor. Their 230Th/234U ages span a time interval from 0.8 to 6.4 ka and cluster around 1.2 and 4.7 ka. In contrast, chemoherm carbonates precipitate from marine bottom water marked by relatively high U concentrations (mean: 5.2 ± 0.8 μg/g) and a mean δ234U ratio of 166 ± 3‰. Their U isotopes reflect the δ234U ratios of the bottom water being enriched in 234U relative to normal seawater. Simple mass balance calculations based on U concentrations and their corresponding δ234U ratios reveal a contribution of about 11% of sedimentary pore water to the bottom water. From the U pore water flux and the reconstructed U pore water concentration a mean flow rate of about 147 ± 68 cm/a can be estimated. 230Th/234U ages of chemoherm carbonates range from 7.3 to 267.6 ka. 230Th/234U ages of two chemoherms (Alvin and SE-Knoll chemoherm) correspond to time intervals of low sealevel stands in marine isotope stages (MIS) 2, 4, 5, 6, 7 and 8. This observation indicates that fluid flow at cold seep sites sensitively reflects pressure changes of the hydraulic head in the sediments. The δ18OPDB ratios of the chemoherm carbonates support the hypothesis of precipitation during glacial times. Deviations of the chemoherm δ18O values from the marine δ18O record can be interpreted as to reflect temporally and spatially varying bottom water and/or vent fluid temperatures during carbonate precipitation between 2.6 and 8.6°C. [Copyright &y& Elsevier]