617 research outputs found

    Terminal Base Pairs of Oligodeoxynucleotides: Imino Proton Exchange and Fraying

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    Segmentation and along-strike asymmetry of the passive margin in Socotra, eastern Gulf of Aden: Are they controlled by detachment faults?

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    International audienceOn the island of Socotra, the southern passive margin of the Gulf of Aden displays along its strike two different types of asymmetric structures. Western Socotra is made up of a series of southward tilted blocks bounded by consistently northward dipping normal faults. Eastern Socotra consists of a broad asymmetric anticline with a steep northern limb and a gently dipping southern limb. A zone of NE-SW striking strike- slip and normal faults separates the two areas. The overall structure is interpreted as representing two rift segments separated by a transfer zone. The along-strike juxtaposition of crustal-scale asymmetric structures on the southern margin of the Gulf of Aden is complemented by the asymmetry of the conjugate margins on either side of the gulf. Whereas the western Socotra margin is narrow and characterized by oceanward dipping normal faults, the conjugate Oman margin is broader and dominated by horsts and graben. Considering that asymmetric structures in the upper crust are often associated with synthetic shear zones at deeper ductile levels, we propose that the western and eastern Socotra margin segments were controlled at depth by two detachment faults with opposite dips and senses of shear. The normal faults of western Socotra would sole out into a top-to-the-north ductile shear zone, whereas the asymmetric anticline of eastern Socotra would be associated with a top-to-the-south detachment fault

    Rapid coupling of Surface Plasmon Resonance (SPR and SPRi) and ProteinChip™ based mass spectrometry for the identification of proteins in nucleoprotein interactions

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    We compared coupling approaches of SPR to LC-MS and ProteinChip™-based mass spectrometry (SELDI™) as a means of identifying proteins captured on DNA surfaces. The approach we outline has the potential to allow multiple, quantitative analysis of macromolecular interactions followed by rapid mass spectrometry identification of retained material

    Which Ocular Dominance Should Be Considered for Monocular Augmented Reality Devices?

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    A monocular augmented reality device allows the user to see information that is superimposed on the environment. As it does not stimulate both eyes in the same way, it creates a phenomenon known as binocular rivalry. The question therefore arises as to whether monocular information should be displayed to a particular eye and if an ocular dominance test can determine it. This paper contributes to give a better understanding of ocular dominance by comparing nine tests. Our results suggest that ocular dominance can be divided into sighting and sensorial dominance. However, different sensorial dominance tests give different results, suggesting that it is composed of distinct components that are assessed by different tests. There is a need for a comprehensive test that can consider all of these components, in order to identify on which eye monocular information should be directed to when using monocular augmented reality devices

    Analogue model of rift linkage and inversion with application to the Western Alps

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    Along-strike segmentation of orogens raises questions because its causes may predate orogeny in relation to structural inheritance. Here we focus on rift/margin linkage domains and their inversion by using analogue models with image analysis to extract the 3D strain field. Extensional models document, depending on the strike-perpendicular offset and the brittle-crust thickness, three types of rift linkage modes: (1) oblique linkage with early T-fault, (2) strongly-oblique linkage with R-fault network and, (3) transfer-linkage with late Y-strike-slip fault. Analogue model of inverted rift basins is used to analyse the misunderstood tectonic evolution of transition zones in the segmented Western Alpine belt

    Correlations between urinary excretion of catecholamines and electrocardiographic parameters of vagal hyperreactivity in infants with fainting spells. Implication of sympathetic hypotonia?

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    SummaryBackgroundVagal hyperreactivity (VHR) is a frequent etiology of infant fainting spells; but it is sometimes difficult to diagnose. A biochemical test would therefore be useful, especially as the oculocardiac reflex (OCR) test innocuity is not absolute.AimsTo evaluate urinary excretions of norepinephrine, epinephrine and dopamine as markers for vagal hyperreactivity.MethodsDuring check-up of 55 infants from 0.5 to 11months of age, for discomfort episodes, including OCR and Holter recording, 24h urinary assays of total norepinephrine, epinephrine and dopamine were carried out to evaluate sympathetic activity.ResultsEpinephrine and norepinephrine urinary excretions were negatively correlated with VHR intensity, as measured by the OCR ECG parameters: RRmax, % cardiac deceleration and minimal frequency; dopamine excretion was not. When RRmaxOCR was greater or equal to 800ms, epinephrine urinary excretion tended to be less or equal to 9nmol/mmol creatinine and norepinephrine excretion less or equal to 190nmol/mmol creatinine.ConclusionA delay in maturation of the sympathetic system and/or adrenomedullary glands with low secretion of norepinephrine and epinephrine inducing a desequilibrium of the sympathetic/parasympathetic balance may contribute to the fainting spells observed with VHR. Epinephrine and norepinephrine urinary excretions may provide informative complementary noninvasive markers for VHR

    Crustal structure of the rifted volcanic margins and uplifted plateau of Western Yemen from receiver function analysis

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    International audienceWe analyse P-wave receiver functions across the western Gulf of Aden and southern Red Sea continental margins in Western Yemen to constrain crustal thickness, internal crustal structure and the bulk seismic velocity characteristics in order to address the role of magmatism, faulting and mechanical crustal thinning during continental breakup. We analyse teleseismic data from 21 stations forming the temporary Young Conjugate Margins Laboratory (YOCMAL) network together with GFZ and Yemeni permanent stations. Analysis of computed receiver functions shows that (1) the thickness of unextended crust on the Yemen plateau is ∼35km; (2) this thins to ∼22km in coastal areas and reaches less than 14km on the Red Sea coast, where presence of a high-velocity lower crust is evident. The average Vp/Vs ratio for the western Yemen Plateau is 1.79, increasing to ∼1.92 near the Red Sea coast and decreasing to 1.68 for those stations located on or near the granitic rocks. Thinning of the crust, and by inference extension, occurs over a ∼130-km-wide transition zone from the Red Sea and Gulf of Aden coasts to the edges of the Yemen plateau. Thinning of continental crust is particularly localized in a <30-km-wide zone near the coastline, spatially co-incident with addition of magmatic underplate to the lower crust, above which on the surface we observe the presence of seaward dipping reflectors (SDRs) and thickened Oligo-Miocene syn-rift basaltic flows. Our results strongly suggest the presence of high-velocity mafic intrusions in the lower crust, which are likely either synrift magmatic intrusion into continental lower crust or alternatively depleted upper mantle underplated to the base of the crust during the eruption of the SDRs. Our results also point towards a regional breakup history in which the onset of rifting was synchronous along the western Gulf of Aden and southern Red Sea volcanic margins followed by a second phase of extension along the Red Sea margin

    Post-rift uplift of the Dhofar margin (Gulf of Aden)

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    International audienceAn investigation of the sedimentation pattern along the Dhofar margin allows us to describe its late-stage evolution. After the accumulation of a thick post-rift sedimentary succession, two debris flow events occurred at the foot of the slope. The first event, affecting a wide area of the margin, marks a major change in sedimentation. The second event is associated with a shift of sedimentary deposition from the slope toward the basin. This latter debris flow was caused by an uplift phase, and highlights two distinct deformational styles in the eastern and western part of the Dhofar margin. Both events occurred very late in the history of the margin, at least 7.6 Ma after the end of the rifting phase (35-17.6 Ma)

    Continental break-up history of a deep magma-poor margin based on seismic reflection data (northeastern Gulf of Aden margin, offshore Oman)

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    International audienceRifting between Arabia and Somalia started around 35 Ma followed by spreading at 17.6 Ma in the eastern part of the Gulf of Aden. The first-order segment between Alula-Fartak and Socotra-Hadbeen fracture zones is divided into three second-order segments with different structure and morphology. Seismic reflection data were collected during the Encens Cruise in 2006 on the northeastern margin. In this study, we present the results of Pre-Stack Depth Migration of the multichannel seismic data from the western segment, which allows us to propose a tectono-stratigraphic model of the evolution of this segment of the margin from rifting to the present day. The chronological interpretation of the sedimentary sequences is mapped out within relation to the onshore observations and existing dating. After a major development of syn-rift grabens and horsts, the deformation localized where the crust is the thinnest. This deformation occurred in the distal margin graben (DIM) at the northern boundary of the ocean-continent transition (OCT) represented by the OCT ridge. At the onset of the OCT formation differential uplift induced a submarine landslide on top of the deepest tilted block and the crustal deformation was restricted to the southern part of the DIM graben, where the continental break-up finally occurred. Initial seafloor spreading was followed by post-rift magmatic events (flows, sills and volcano-sedimentary wedge), whose timing is constrained by the analysis of the sedimentary cover of the OCT ridge, correlated with onshore stratigraphy. The OCT ridge may represent exhumed serpentinized mantle intruded by post-rift magmatic material, which modified the OCT after its emplacement
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