Modelling of till microstructure development during subglacial deformation using ring shear experiments

Micromorphology has become a principal tool in glacial sedimentology providing a wealth of data on the geometry and kinematics of deformation histories and aiding our understanding of progressive and polyphase deformation. This approach has been applied to the detailed microstructural analysis of fabric development in nine samples of experimentally deformed till subjected to simple shear in a ring shear apparatus in order to model the progressive microfabric development during simulated subglacial deformation. Thin section analysis revealed that the relative strength and complexity of the clast microfabrics increases with increasing cumulative shear distance (0–1152 cm) and cumulative shear strain (0–549), whereas microfabric strength increases rapidly during the initial stages of shearing (cumulative strain up to ∼20) and remains relatively stable at higher cumulative strain (>200). In addition microfabric development is heterogeneous reflecting the partitioning of deformation at a microscale. A conjugate pattern of clast long axis alignment identified in the un-sheared sample taken at the start of the experiment formed during the initial consolidation and draining of the till. This emphasises that water-rich unconsolidated tills have the potential to be highly responsive to any applied stress even at very low strains. This un-sheared fabric was overprinted at a very early stage of the experiment when cumulative shear strains were below 5. The complex microfabrics formed during simple shear record the progressive development of up-shear dipping P-shears, down-shear dipping R-shears, and subhorizontal Y-shears. Sigmoidal fabric geometries, comparable to S–C and ECC-type fabrics, associated with the Riedel shears record a consistent sinistral sense of shear, i.e. the direction of shear imposed by the rotating plate of the ring shear. Observed changes in the relationships between these microfabrics record the switching between the localised imposition of a compressional fabric and P-shear formation, to subhorizontal shear and the formation of Y-shears accompanied by extension and the growth of low-angle R-shears, and back again. This process may potentially lead to alternating phases of “stick” (compression) and “slip” (subhorizontal shear) recognised as a key feature of glacier motion occurring in response to soft-sediment bed deformation. Multiple cycles of microstructure overprinting and rejuvenation pose a major challenge on determining the cumulative strain of subglacially deformed tills of unknown history from micromorphological signatures alone

A cross-validated three-dimensional model of an englacial and subglacial drainage system in a High-Arctic glacier

The project was supported by the Danish Geological Society and the Arctic Research and Technology Society.Recent speleological surveys of meltwater drainage systems in cold and polythermal glaciers have documented dynamic englacial and in some cases subglacial conduits formed by the ‘cut-and-closure’ mechanism. Investigations of the spatial distribution of such conduits often require a combination of different methods. Here, we studied the englacial drainage system in the cold glacier Longyearbreen, Svalbard by combining speleological exploration of a 478 m long meltwater conduit with a high-resolution ground penetrating radar (GPR) survey with two different centre-frequencies (25 and 100 MHz). The results yielded a 3-D documentation of the present englacial drainage system. The study shows that the overall form of englacial conduits can be detected from velocity−depth converted GPR data, and that the 3-D model can facilitate a method to pinpoint the reflections in a radargram corresponding with the englacial drainage system, although fine detail cannot be resolved. Visible reflections approximately parallel to the mapped englacial water drainage system likely result from sediment incorporated in the ice or from abandoned parts of the englacial drainage system.Publisher PDFPeer reviewe

Glazialtektonik weichselzeitlicher Ablagerungen in Zentral-Fünen, Dänemark

Die glazialen Sedimente des Untersuchungsgebietes im zentralen Teil der dänischen Insel Fünen sind durch intensive Deformation geprägt. In den mächtigen glazifluviatilen Sedimentfolgen treten vor allem Überschiebungen, stark deformierte Faltenstrukturen und Zungenfalten auf. Da die Einmessung dieser Strukturen bis zu drei Deformationsrichtungen ergibt, müssen verschiedene Eisbewegungsrichtungen auf die Sedimente eingewirkt haben. Mit Hilfe sedimentologischer Untersuchungen des im Hangenden aufgeschlossenen Tills ist die Bildung eines großen Teils der Deformationsstrukturen mit dem Hauptvorstoß der Weichselzeit aus Nordosten und dem darauffolgenden jungbaltischen Vorstoß aus südöstlicher Richtung zu korrelieren. Die nahezu gleichmäßige Verteilung der verschiedenen Deformationsrichtungen lässt sich auf unterschiedliche Scherfestigkeiten der einzelnen Profilteile zurückführen, die z.T. eine Überprägung der bereits vorhandenen Deformationsstrukturen verhinderten. Es gibt keinen Zusammenhang zwischen der Eisvorstoßdynamik und bestimmten glazialtektonischen Strukturen, deren Stil vielmehr durch rheologische Eigenschaften des Sedimentes bestimmt ist. Die hohe Geschwindigkeit des jungbaltischen, als Eisstrom ausgebildeten Vorstoßes war z.T. durch Verformung des weichen, wasserübersättigten Untergrundes begünstigt.researc

Measurement of psychological entitlement in 28 countries

This article presents the cross-cultural validation of the Entitlement Attitudes Questionnaire, a tool designed to measure three facets of psychological entitlement: active, passive, and revenge entitlement. Active entitlement was defined as the tendency to protect individual rights based on self-worthiness. Passive entitlement was defined as the belief in obligations to and expectations toward other people and institutions for the fulfillment of the individual’s needs. Revenge entitlement was defined as the tendency to protect one’s individual rights when violated by others and the tendency to reciprocate insults. The 15-item EAQ was validated in a series of three studies: the first one on a general Polish sample (N = 1,900), the second one on a sample of Polish students (N = 199), and the third one on student samples from 28 countries (N = 5,979). A three-factor solution was confirmed across all samples. Examination of measurement equivalence indicated partial metric invariance of EAQ for all national samples. Discriminant and convergent validity of the EAQ was also confirmed

Repetitive Late Pleistocene soft‐sediment deformation by seismicity‐induced liquefaction in north‐western Lithuania

Liquefaction can cause deformation of unconsolidated sediment, but specific processes involved and the trigger mechanisms often remain obscured. This study describes multiple deformed sediment layers in a succession of lacustrine sand, silt and clay deposited during the Marine Isotope Stage 5d in north-western Lithuania. The deformation structures (load casts, pseudonodules, ball-and-pillow structures, broken-up laminae and injections) are embedded in ten separate layers of fine-grained, laterally continuous sediments. Detailed mesoscale sedimentological analyses suggest that each deformation event consisted of numerous successive stages of sediment advection facilitated by liquefaction. Low-permeability fine-grained laminae contributed to localized pore-water pressure build-up and lowering of sediment strength. Erosional top surfaces that truncate layers with soft-sediment deformation structures suggest that at least seven deformation events were separated by successive periods of initial erosion and then uninterrupted deposition in the lake. The most likely trigger of the deformation was recurrent palaeoseismic activity possibly linked to a late glacial isostatic adjustment following the Scandinavian Ice Sheet melting after the Saalian glaciation. This study emphasizes the potential role of seismic processes in shaping the sedimentary record of the intraplate region of north-eastern Europe and contributes to constraining the depth of liquefaction, regardless of the actual trigger mechanism

Formal ratification of subseries for the Pleistocene Series of the Quaternary System

The Pleistocene Series/Epoch of the Quaternary System/Period has been divided unofficially into three subseries/subepochs since at least the 1870s. On 30 January, 2020, the Executive Committee of the International Union of Geological Sciences ratified two proposals approved by the International Commission on Stratigraphy formalizing: 1) the Lower Pleistocene Subseries, comprising the Gelasian Stage and the superjacent Calabrian Stage, with a base defined by the GSSP for the Gelasian Stage, the Pleistocene Series, and the Quaternary System, and currently dated at 2.58 Ma; and 2) the term Upper Pleistocene, at the rank of subseries, with a base currently undefined but provisionally dated at ~129 ka. Defining the Upper Pleistocene Subseries and its corresponding stage with a GSSP is in progress. The Middle Pleistocene Subseries is defined by the recently ratified GSSP for the Chibanian Stage currently dated at 0.774 Ma. These ratifications complete the official division of the Pleistocene into three subseries/subepochs, in uniformity with the similarly subdivided Holocene Series/Epoch

Progressive ductile shearing during till accretion within the deforming bed of a palaeo-ice stream

This paper presents the results of a detailed microstructural study of a thick till formed beneath the Weichselian (Devensian) Odra palaeo-ice stream, west of Środa Wielkopolska, Poland. This SE-flowing ice stream was one of a number of corridors of faster flowing ice which drained the Scandinavian Ice Sheet in the Baltic region. Macroscopically, the massive, laterally extensive till which formed the bed of this ice stream lacks any obvious evidence of glaciotectonism (thrusting, folding). However, microscale analysis reveals that bed deformation was dominated by foliation development, recording progressive ductile shearing within a subhorizontal subglacial shear zone. Five successive generations of clast microfabric (S1 to S5) have been identified defining a set of up-ice and down-ice dipping Riedel shears, as well as a subhorizontal shear foliation coplanar to the ice-bed interface. Cross-cutting relationships between the shear fabrics record temporal changes in the style of deformation during this progressive shear event. Kinematic indicators (S-C and ECC-type fabrics) within the till indicate a consistent SE-directed shear sense, in agreement with the regional ice flow pattern. A model of bed deformation involving incremental progressive simple shear during till accretion is proposed. The relative age of this deformation was diachronous becoming progressively younger upwards, compatible with subglacial shearing having accompanied till accretion at the top of the deforming bed. Variation in the relative intensity of the microfabrics records changes in the magnitude of the cumulative strain imposed on the till and the degree of coupling between the ice and underlying bed during fast ice flow

Standardized postnatal management of infants with congenital diaphragmatic hernia in Europe: The CDH EURO Consortium Consensus - 2015 Update

In 2010, the congenital diaphragmatic hernia (CDH) EURO Consortium published a standardized neonatal treatment protocol. Five years later, the number of participating centers has been raised from 13 to 22. In this article the relevant literature is updated, and consensus has been reached between the members of the CDH EURO Consortium. Key updated recommendations are: (1) planned delivery after a gestational age of 39 weeks in a high-volume tertiary center; (2) neuromuscular blocking agents to be avoided during initial treatment in the delivery room; (3) adapt treatment to reach a preductal saturation of between 80 and 95% and postductal saturation >70%; (4) target PaCO2 to be between 50 and 70 mm Hg; (5) conventional mechanical ventilation to be the optimal initial ventilation strategy, and (6) intravenous sildenafil to be considered in CDH patients with severe pulmonary hypertension. This article represents the current opinion of all consortium members in Europe for the optimal neonatal treatment of CDH

Genetic Analysis of Fin Development in Zebrafish Identifies Furin and Hemicentin1 as Potential Novel Fraser Syndrome Disease Genes

Using forward genetics, we have identified the genes mutated in two classes of zebrafish fin mutants. The mutants of the first class are characterized by defects in embryonic fin morphogenesis, which are due to mutations in a Laminin subunit or an Integrin alpha receptor, respectively. The mutants of the second class display characteristic blistering underneath the basement membrane of the fin epidermis. Three of them are due to mutations in zebrafish orthologues of FRAS1, FREM1, or FREM2, large basement membrane protein encoding genes that are mutated in mouse bleb mutants and in human patients suffering from Fraser Syndrome, a rare congenital condition characterized by syndactyly and cryptophthalmos. Fin blistering in a fourth group of zebrafish mutants is caused by mutations in Hemicentin1 (Hmcn1), another large extracellular matrix protein the function of which in vertebrates was hitherto unknown. Our mutant and dose-dependent interaction data suggest a potential involvement of Hmcn1 in Fraser complex-dependent basement membrane anchorage. Furthermore, we present biochemical and genetic data suggesting a role for the proprotein convertase FurinA in zebrafish fin development and cell surface shedding of Fras1 and Frem2, thereby allowing proper localization of the proteins within the basement membrane of forming fins. Finally, we identify the extracellular matrix protein Fibrillin2 as an indispensable interaction partner of Hmcn1. Thus we have defined a series of zebrafish mutants modelling Fraser Syndrome and have identified several implicated novel genes that might help to further elucidate the mechanisms of basement membrane anchorage and of the disease's aetiology. In addition, the novel genes might prove helpful to unravel the molecular nature of thus far unresolved cases of the human disease

Immune cells lacking Y chromosome show dysregulation of autosomal gene expression

Funder: Kjell och Märta Beijers Stiftelse (SE)Funder: Hjärnfonden; doi: http://dx.doi.org/10.13039/501100003792Funder: Cancerfonden; doi: http://dx.doi.org/10.13039/501100002794Funder: Vetenskapsrådet; doi: http://dx.doi.org/10.13039/501100004359Funder: Alzheimerfonden; doi: http://dx.doi.org/10.13039/501100008599Funder: Konung Gustaf V:s och Drottning Victorias Frimurarestiftelse (SE)Funder: Science for Life Laboratory (SE)Funder: Fundacja na rzecz Nauki Polskiej (PL)Funder: Uppsala UniversityAbstract: Epidemiological investigations show that mosaic loss of chromosome Y (LOY) in leukocytes is associated with earlier mortality and morbidity from many diseases in men. LOY is the most common acquired mutation and is associated with aberrant clonal expansion of cells, yet it remains unclear whether this mosaicism exerts a direct physiological effect. We studied DNA and RNA from leukocytes in sorted- and single-cells in vivo and in vitro. DNA analyses of sorted cells showed that men diagnosed with Alzheimer’s disease was primarily affected with LOY in NK cells whereas prostate cancer patients more frequently displayed LOY in CD4 + T cells and granulocytes. Moreover, bulk and single-cell RNA sequencing in leukocytes allowed scoring of LOY from mRNA data and confirmed considerable variation in the rate of LOY across individuals and cell types. LOY-associated transcriptional effect (LATE) was observed in ~ 500 autosomal genes showing dysregulation in leukocytes with LOY. The fraction of LATE genes within specific cell types was substantially larger than the fraction of LATE genes shared between different subsets of leukocytes, suggesting that LOY might have pleiotropic effects. LATE genes are involved in immune functions but also encode proteins with roles in other diverse biological processes. Our findings highlight a surprisingly broad role for chromosome Y, challenging the view of it as a “genetic wasteland”, and support the hypothesis that altered immune function in leukocytes could be a mechanism linking LOY to increased risk for disease