Importance of sampling across an assemblage of glacial landforms for interpreting cosmogenic ages of deglaciation

Deglaciation chronologies for some sectors of former ice sheets are relatively poorly constrained because of the paucity of features or materials traditionally used to constrain the timing of deglaciation. In areas without good deglaciation varve chronologies and/or without widespread occurrence of material that indicates the start of earliest organic radiocarbon accumulations suitable for radiocarbon dating, typically only general patterns and chronologies of deglaciation have been deduced. However, mid-latitude ice sheets that had warm-based conditions close to their margins often produced distinctive deglaciation landform assemblages, including eskers, deltas, meltwater channels and aligned lineation systems. Because these features were formed or significantly altered during the last glaciation, boulder or bedrock samples from them have the potential to yield reliable deglaciation ages using terrestrial cosmogenic nuclides (TCN) for exposure age dating. Here we present the results of a methodological study designed to examine the consistency of TCN-based deglaciation ages from a range of deglaciation landforms at a site in northern Norway. The strong coherence between exposure ages across several landforms indicates great potential for using TCN techniques on features such as eskers, deltas and meltwater channels to enhance the temporal resolution of ice-sheet deglaciation chronologies over a range of spatial scales

Türkiye Bilimler Akademisi arkeoloji dergisi : TÜBA-AR

The century-long debate over the origins of inner gorges that were repeatedly covered by Quaternary glaciers hinges upon whether the gorges are fluvial forms eroded by subaerial rivers, or subglacial forms cut beneath ice. Here we apply cosmogenic nuclide exposure dating to seven inner gorges along ~500 km of the former Fennoscandian ice sheet margin in combination with a new deglaciation map. We show that the timing of exposure matches the advent of ice-free conditions, strongly suggesting that gorges were cut by channelized subglacial meltwater while simultaneously being shielded from cosmic rays by overlying ice. Given the exceptional hydraulic efficiency required for meltwater channels to erode bedrock and evacuate debris, we deduce that inner gorges are the product of ice sheets undergoing intense surface melting. The lack of postglacial river erosion in our seven gorges implicates subglacial meltwater as a key driver of valley deepening on the Baltic Shield over multiple glacial cycles

662 adult acute myeloid leukemia (AML) cases characterized on the Affymetrix Human Genome U133 Plus 2.0 Microarray

The pretreatment karyotype of leukemic blasts is currently the key determinant in therapy decision-making in acute myeloid leukemia (AML). However, approximately fifty percent of AML patients, often carrying a normal karyotype, are currently unclassifiable based these established methods. Gene expression profiling has proven to be valuable for risk stratification of AML. This is a repository of 662 adult AML cases characterized on gene expression microarrays and used for different studies investigating the mechanisms underlying leukemogenesis. Bone marrow aspirates or peripheral blood samples of three independent representative cohorts of de novo AML patients, comprising 277, 256 and 129 cases respectively, were collected at diagnosis. Gene expression profiling was performed on 662 adult AML patients who have been treated according to Dutch-Belgian Hemato-Oncology Cooperative Group and the Swiss Group for Clinical Cancer Research (HOVON/SAKK) AML-04, -04A, -29, -32, -42, -42A, -43 and -92 protocols (available at http://www.hovon.nl). All patients provided written informed consent in accordance with the Declaration of Helsinki, and the study was approved by all participating institutional review boards. Blast cell purification and RNA isolation were performed as previously described (Valk et al., Prognostically Useful Gene-Expression Profiles in Acute Myeloid Leukemia, New England Journal of Medicine, 2004)

662 adult acute myeloid leukemia (AML) cases characterized on the Affymetrix Human Genome U133 Plus 2.0 Microarray

The pretreatment karyotype of leukemic blasts is currently the key determinant in therapy decision-making in acute myeloid leukemia (AML). However, approximately fifty percent of AML patients, often carrying a normal karyotype, are currently unclassifiable based these established methods. Gene expression profiling has proven to be valuable for risk stratification of AML. This is a repository of 662 adult AML cases characterized on gene expression microarrays and used for different studies investigating the mechanisms underlying leukemogenesis. Bone marrow aspirates or peripheral blood samples of three independent representative cohorts of de novo AML patients, comprising 277, 256 and 129 cases respectively, were collected at diagnosis. Gene expression profiling was performed on 662 adult AML patients who have been treated according to Dutch-Belgian Hemato-Oncology Cooperative Group and the Swiss Group for Clinical Cancer Research (HOVON/SAKK) AML-04, -04A, -29, -32, -42, -42A, -43 and -92 protocols (available at http://www.hovon.nl). All patients provided written informed consent in accordance with the Declaration of Helsinki, and the study was approved by all participating institutional review boards. Blast cell purification and RNA isolation were performed as previously described (Valk et al., Prognostically Useful Gene-Expression Profiles in Acute Myeloid Leukemia, New England Journal of Medicine, 2004)