61 research outputs found
Proximal ischemia is a frequent cause of exercise-induced pain in patients with a normal ankle to brachial index at rest
BACKGROUND: Excluding a vascular origin of exercise-related pain is often difficult in clinical practice. Recent papers have underlined the frequent association of concurrent lumbar spine degenerative disease and peripheral arterial disease. Furthermore, even when suspected, isolated exercise-induced proximal ischemia is difficult to diagnose. Measurement of transcutaneous oxygen pressure (tcpO2) is an interesting and accurate method to differentiate proximal (buttock) from distal (calf) regional blood flow impairment (RBFI) during exercise. OBJECTIVES: We searched for isolated proximal-without-distal RBFI as a possible cause of claudication, in patients with borderline (ABI-b: 0.91 - 0.99) or normal (ABI-n: 1.00 to 1.40) ankle to brachial index at rest. STUDY DESIGN: Retrospective cohort design study. We analyzed patients referred to our laboratory with symptom limiting claudication and an ankle brachial index within normal limits. SETTING: University-based exercise-investigation center. METHODS: Over a 12-year period, we identified 463 patients referred to our laboratory that had their lowest resting ABI between 0.90 and 1.40. The tcpO2 on chest, buttocks, and calves were recorded during treadmill walking tests (3.2 km/h, 10% slope) in 220 ABI-b and 243 ABI-n unique consecutive patients complaining of limiting claudication (each patient\u27s ABI was the lowest of the 2 legs). Limiting claudication was defined as the reported inability to walk 1 kilometer without stopping. A DROP index (limb tcpO2-changes minus chest tcpO2-changes from rest) below -15 mmHg was used to indicate a positive result (i.e. exercise-induced RBFI). RESULTS: Treadmill exercise showed evidence for proximal or distal RBFI, of at least one side, in 128 out of 220 patients (58.2%) and in 86 out of 243 (35.4%) patients with ABI-b and ABI-n, respectively. Isolated proximal-without-distal RBFI was found in 32 out of the 128 (25.0 %) positive tests in ABI-b and 32 out of the 86 (37.2%) positive tests in ABI-n patients. LIMITATIONS: Study limitations include the absence of systematic follow-up of diagnosed patients and absence of systematic search for cardio-respiratory co-morbid conditions. CONCLUSION: Isolated proximal-without distal RBFI is found in approximately one out of 7 patients complaining of symptom limiting claudication with a borderline or normal resting ABI. Exercise-tcpO2 may help to discriminate patients with arterial claudication that could benefit from invasive vascular investigations and procedures
Pre-breakup magmatism on the VĂžring margin: Insight from new sub-basalt imaging and results from Ocean Drilling program hole 642E
Highlights
âą Sub-basalt imaging improvement on the VĂžring Margin
âą Definition of a new seismic facies unit: the Lower Series Flows
âą Significant organic carbon content within the melting crustal segment
âą Apectodinium augustum marker for the PETM is reworked into the Lower Series Flows
âą The Lower Series Flows, early Eocene in age, predate the VĂžring Margin breakup
Abstract
Improvements in sub-basalt imaging combined with petrological and geochemical observations from the Ocean Drilling Program (ODP) Hole 642E core provide new constraints on the initial breakup processes at the VĂžring Margin. New and reprocessed high quality seismic data allow us to identify a new seismic facies unit which we define as the Lower Series Flows. This facies unit is seismically characterized by wavy to continuous subparallel reflections with an internal disrupted and hummocky shape. Drilled lithologies, which we correlate to this facies unit, have been interpreted as subaqueous flows extruding and intruding into wet sediments. Locally, the top boundary of this facies unit is defined as a negative in polarity reflection, and referred as the K-Reflection. This reflection can be correlated with the spatial extent of pyroclastic deposits, emplaced during transitional shallow marine to subaerial volcanic activities during the rift to drift transition. The drilled Lower Series Flows consist of peraluminous, cordierite bearing peperitic basaltic andesitic to dacitic flows interbedded with thick volcano-sedimentary deposits and intruded sills. The peraluminous geochemistry combined with available C (from calcite which fills vesicles and fractures), Sr, Nd, and Pb isotopes data point towards upper crustal rock-mantle magma interactions with a significant contribution of organic carbon rich pelagic sedimentary material during crustal anatexis. From biostratigraphic analyses, Apectodinium augustum was found in the The Lower Series Flows. This species is a marker for the Paleocene â Eocene Thermal Maximum (PETM). However, the absence of very low carbon isotope values (from bulk organic matter), that characterize the PETM, imply that A.augustum was reworked into the early Eocene sediments of this facies unit which predate the breakup time of the VĂžring Margin.
Finally, a plausible conceptual emplacement model for the Lower Series Flows facies unit is proposed. This model comprises several stages: (1) the emplacement of subaqueous peperitic basaltic andesitic flows intruding and/or extruding wet sediments; (2) a subaerial to shallow marine volcanism and extrusion of dacitic flows; (3) a proto-breakup phase with intense shallow marine to subaerial explosive volcanism responsible for pyroclastic flow deposits which can be correlated with the seismic K-Reflection and (4) the main breakup stage with intense transitional tholeiitic MORB-type volcanism and large subsidence concomitant with the buildup of the Seaward Dipping Reflector wedge
Middle Neolithic farming of open-air sites in SE France: new insights from archaeobotanical investigations of three wells found at Les Bagnoles (L'Isle-sur-la-Sorgue, DĂ©pt. Vaucluse, France)
Previous reviews of Middle Neolithic agricultural practice (4400â3500 cal bc) in southern France have highlighted a change in crop assemblages after 4000 cal bc, with a reduction of naked wheat and an increase of emmer and partly of einkorn. The recent investigation of three wells from the site of Les Bagnoles (4250â3800 cal bc) in the periphery of the southern RhĂŽne valley yielded an unprecedented amount of waterlogged uncharred and charred plant macro remains that offer new insights into crop diversity and its changes over time. The results from the wells at Les Bagnoles were compared with other dated sunken features from open-air sites (in contrast to caves and rock shelters), with the aim of identifying patterns sug-gesting changes in the crop spectra between the early (MN1) and late (MN2) Middle Neolithic phases from taphonomically comparable contexts. The results from Les Bagnoles demonstrate that oil crops and pulses are underrepresented in dry sites and that they were a significant part of Middle Neolithic agriculture. They also indicate an increase in the representation of einkorn (instead of emmer) during MN2 that is also visible in other open-air sites. The comparison of the archaeobotani-cal results with silo storage capacity values as a proxy for average production capacity per household leads us to propose a possible drop in naked wheat productivity and opens new questions in factors affecting crop choice at the beginning of the 4th millennium cal bc
Fullerene-grafted block copolymers used as compatibilizer in P3HT/PCBM bulk heterojunctions: morphology and photovoltaic performances
Accounting for success and failure: a discursive psychological approach to sport talk
YesIn recent years, constructionist methodologies such as discursive psychology (Edwards & Potter, 1992) have begun to be used in sport research. This paper provides a practical guide to applying a discursive psychological approach to sport data. It discusses the assumptions and principles of discursive psychology and outlines the stages of a discursive study from choice of data through to transcription and analysis. Finally, the paper demonstrates a discursive psychological analysis on sport data where athletes are accounting for success and failure in competition. The analysis demonstrates that for both success and failure, there is an apparent dilution of personal agency, to either maintain their modesty in the case of success or to manage blame when talking about failure. It is concluded that discursive psychology has much to offer sport research as it provides a methodology for in-depth studies of supporting interactions
Formation and deformation of hyperextended rift systems: Insights from rift domain mapping in the Bay of Biscay-Pyrenees
International audienceThe Bay of Biscay and the Pyrenees correspond to a Lower Cretaceous rift system including both oceanic and hyperextended rift domains. The transition from preserved oceanic and rift domains in the West to their complete inversion in the East enables us to study the progressive reactivation of a hyperextended rift system. We use seismic interpretation, gravity inversion, and field mapping to identify and map former rift domains and their subsequent reactivation. We propose a new map and sections across the system illustrating the progressive integration of the rift domains into the orogen. This study aims to provide insights on the formation of hyperextended rift systems and discuss their role during reactivation. Two spatially and temporally distinct rift systems can be distinguished: the Bay of Biscay-Parentis and the Pyrenean-Basque-Cantabrian rifts. While the offshore Bay of Biscay represent a former mature oceanic domain, the fossil remnants of hyperextended domains preserved onshore in the Pyrenean-Cantabrian orogen record distributed extensional deformation partitioned between strongly segmented rift basins. Reactivation initiated in the exhumed mantle domain before it affected the hyperthinned domain. Both domains accommodated most of the shortening. The final architecture of the orogen is acquired once the conjugate necking domains became involved in collisional processes. The complex 3-D architecture of the initial rift system may partly explain the heterogeneous reactivation of the overall system. These results have important implications for the formation and reactivation of hyperextended rift systems and for the restoration of the Bay of Biscay and Pyrenean domain
ApplicabilitĂ© du GPS dans lâĂ©valuation des limitations Ă la marche des claudications artĂ©rielles
International audienc
The Norway Basin revisited: From continental breakup to spreading ridge extinction
We re-evaluate the structure and spreading evolution of the southeastern Norway Basin (NB) based on a new high resolution aeromagnetic survey (NB-07). The survey covers a complete oceanic spreading segment from the continental-oceanic transition of the MĂžre margin, off Norway to the aborted Aegir Ridge. The new survey documents a transform margin, an orthogonally rifted segment and an oblique-sheared volcanic margin formed during the onset of breakup, observed from the East Jan Mayen Fracture Zone to the Faroe Platform. The detailed fabric of the NB revealed by the new data indicates that two distinct tectonic phases have reshaped the basin before the cessation of seafloor spreading and abortion of the Aegir Ridge in the Late Oligocene. After continental breakup, Phase I (from C24 to C21r, âŒ52 to 49 Ma) marks the earliest phase of spreading, probably initiated in the central and outer part of the MĂžre Basin. During this period, competing oceanic segments led to the formation of overlapping systems and pseudo-fault development. We observe a significant change in the NB's oceanic spreading system in the late Early Eocene and, based on observations from surrounding areas, we suggest that this is a record of a major tectonic event in the Norwegian-Greenland Sea around C21r (49-47.9 Ma). During Phase II (from C21r to C10?, 48 to 28 Ma) of NB's development, spreading rates decreased, spreading direction changed, and the number of faulting with large displacement increased leading to the formation of unexpected N-S oriented oceanic fracture zones. The fan-shaped development of the spreading system initiated around C21r (âŒ49-47.9 Ma) instead of C18-C17 (âŒ40-38 Ma) or C24 (53.3-52.3 Ma) as previously proposed. These new observations were used to re-evaluate the tectonic evolution of the Norwegian-Greenland Sea and discuss some implications on the syn- and post-breakup development of the surrounding continental margins and the evolution of the Jan Mayen microcontinent.</p
Direct Amidation of Carboxylic Acids Catalyzed by <i>ortho</i>-Iodo Arylboronic Acids: Catalyst Optimization, Scope, and Preliminary Mechanistic Study Supporting a Peculiar Halogen Acceleration Effect
The importance of amides as a component of biomolecules
and synthetic products motivates the development of catalytic, direct
amidation methods employing free carboxylic acids and amines that
circumvent the need for stoichiometric activation or coupling reagents. <i>ortho</i>-Iodophenylboronic acid <b>4a</b> has recently
been shown to catalyze direct amidation reactions at room temperature
in the presence of 4A molecular sieves as dehydrating agent. Herein,
the arene core of <i>ortho</i>-iodoarylboronic acid catalysts
has been optimized with regards to the electronic effects of ring
substitution. Contrary to the expectation, it was found that electron-donating
substituents are preferable, in particular, an alkoxy substituent
positioned para to the iodide. The optimal new catalyst, 5-methoxy-2-iodophenylboronic
acid (MIBA, <b>4f</b>), was demonstrated to be kinetically more
active than the parent des-methoxy catalyst <b>4a</b>, providing
higher yields of amide products in shorter reaction times under mild
conditions at ambient temperature. Catalyst <b>4f</b> is recyclable
and promotes the formation of amides from aliphatic carboxylic acids
and amines, and from heteroaromatic carboxylic acids and other functionalized
substrates containing moieties like a free phenol, indole and pyridine.
Mechanistic studies demonstrated the essential role of molecular sieves
in this complex amidation process. The effect of substrate stoichiometry,
concentration, and measurement of the catalyst order led to a possible
catalytic cycle based on the presumed formation of an acylborate intermediate.
The need for an electronically enriched <i>ortho</i>-iodo
substituent in catalyst <b>4f</b> supports a recent theoretical
study (Marcelli, T. <i>Angew. Chem. Int. Ed.</i> <b>2010</b>, <i>49</i>, 6840â6843) with a purported role for
the iodide as a hydrogen-bond acceptor in the orthoaminal transition
state
The Jan Mayen microplate complex and the Wilson cycle
The opening of the North Atlantic region was one of the most important geodynamic events that shaped the present day passive margins of Europe, Greenland and North America. Although well-studied, much remains to be understood about the evolution of the North Atlantic, including the role of the Jan Mayen microplate complex. Geophysical data provide an image of the crustal structure of this microplate and enable a detailed reconstruction of the rifting and spreading history. However, the mechanisms that cause the separation of microplates between conjugate margins are still poorly understood. We assemble recent models of rifting and passive margin formation in the North Atlantic and discuss possible scenarios that may have led to the formation of the Jan Mayen microplate complex. This event was probably triggered by regional plate tectonic reorganizations rejuvenating inherited structures. The axis of rifting and continental break-up and the width of the Jan Mayen microplate complex were controlled by old Caledonian fossil subduction/suture zones. Its length is related to eastâwest-oriented deformation and fracture zones, possibly linked to rheological heterogeneities inherited from the pre-existing Precambrian terrane boundaries
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