PALAEONTOLOGICAL (RADIOLARIAN) LATE JURASSIC AGE CONSTRAINT FOR THE STEPANAVAN OPHIOLITE (LESSER CAUCASUS, ARMENIA)

Η χρονολόγηση με βάση μικροπαλαιοντολογικά δεδομένα, των ιζηματογενών καλυμμάτων των οφιολίθων είναι ιδιαίτερης σημασίας για την κατανόηση της παλαιογεωγραφικής και γεωδυναμικής εξέλιξης των περιοχών της Τηθύος. Η οφιολιθική ακολουθία του Stepanavan στη Βόρεια Αρμενία συνίσταται από περιδοτίτες, γάββρους, πλαγιογρανίτες και λάβες και ιζηματογενή καλύματα ραδιολαριτών. Θεωρείται ως η βόρεια επέκταση της οφιολιθικής ζώνης Sevan Akera και η ανατολική επέκταση της ζώνης Izmir-Ankara. Αντιπροσωπεύει κατάλοιπο μιας βραδέως εκτεινόμενης μεσο-ωκεάνιας ράχης, που ήταν ενεργή μεταξύ της Ευρασίας και του νότιου Αρμενικού τεμάχους γκοντβανικής προέλευσης. Τα ραδιολάρια που εξετάστηκαν από τους ραδιολαρίτες στην περιοχή της οφιολιθικής ακολουθίας του Stepanavan πιστοποιούν για πρώτη φορά ηλικία Ανώτερου Ιουρασικού (ανώτερο Κιμμερίδιο έως κατώτερο Τιθώνιο) προσδίδοντας ηλικία για αυτό το τμήμα του ωκεάνιου φλοιού της Τηθύος που παρατηρείται στο Lesser Caucasus.Micropalaeontological age evidence for the sedimentary cover of ophiolites is important to understand the palaeogeographic and geodynamic evolution of Tethyan realms. The Stepanavan ophiolitic suite of Northern Armenia consists of peridotites, gabbros, plagiogranite and lavas with a radiolarite sedimentary cover. It is regarded as the northern extension of the Sevan Akera ophiolitic zone and may be considered as the eastern extension of the Izmir-Ankara suture zone. It represents the relics of a slow-spreading mid oceanic ridge that was active between Eurasia and the South-Armenian Block of Gondwanian origin. Radiolaria extracted from radiolarites of the Stepanavan ophiolite provide for the first time a Late Jurassic (late Kimmeridgian to early Tithonian) age constraint for this part of Tethyan oceanic crust preserved in Lesser Caucasus

Antibunched photons emitted by a dc-biased Josephson junction

We show experimentally that a dc biased Josephson junction in series with a high-enough-impedance microwave resonator emits antibunched photons. Our resonator is made of a simple microfabricated spiral coil that resonates at 4.4 GHz and reaches a 1.97kΩ characteristic impedance. The second order correlation function of the power leaking out of the resonator drops down to 0.3 at zero delay, which demonstrates the antibunching of the photons emitted by the circuit at a rate of 6×10^7 photons per second. Results are found in quantitative agreement with our theoretical predictions. This simple scheme could offer an efficient and bright single-photon source in the microwave domain

Deglaciation history at the Alpine-Mediterranean transition (Argentera-Mercantour, SW Alps) from 10Be dating of moraines and glacially polished bedrock

International audienceEstimating the extent and age of the last glacial maxima as well as the chronology of glacial recessions in various environmental contexts is key to source-to-sink studies and paleoclimate reconstructions. The Argentera-Mercantour massif being located at the transition between the Alps and the Mediterranean Sea, its deglaciation chronology can be compared to the sediment budget of the Var River marine delta. In this paper, the deglaciation is constrained by 13 new and 22 reassessed Cosmic-Ray Exposure (CRE) 10Be datings of moraines and polished crystalline bedrocks. These data allow for the first time to fully reconstruct the deglaciation history at the scale of the entire massif, in agreement with a major glacier recession at ca. 15 ka, at the onset of Bølling transition. This contribution reveals a glacier–climate relationship more sensitive to warming phases in the southern Alps highlighted by a major decrease of glaciers after ca. 15 ka. This major deglaciation is correlated with a 2.5 fold decrease of sediment discharge of rivers into the Mediterranean Sea. Main deglaciation of the massif upper slopes (2,700-2,800 m a.s.l.) occurred after the LGM at 20.8-18.6 ka, followed by the lower slopes (2,300 m a.s.l.) at 15.3-14.2 ka. Finally, the flat polished surfaces above 2,600 m a.s.l. and the zones confined within narrow lateral valleys were likely affected by progressive ice melting of remaining debris covered glaciers and moraine erosion following the Younger Dryas re-advance stage between 12 and 8-9 ka. At lower elevations, a sediment core in the Vens Lake located at 2,300 m a.s.l., shows onset of lake sedimentation at ca. 14 ka and a transition towards a vegetated environment after 8 ka. Final stabilization of moraines occurred at 5 ka, which might reflect denudation acceleration during the Holocene humid phase

Entrapment and traumatic neuropathies of the elbow and hand: An imaging approach

AbstractUltrasound and magnetic resonance imaging currently offer a detailed analysis of the peripheral nerves. Compressive and traumatic nerve injuries are the two main indications for imaging investigation of nerves with several publications describing the indications, technique and diagnostic capabilities of imaging signs. Investigation of entrapment neuropathies has three main goals, which are to confirm neuronal distress, search for the cause of nerve compression and exclude a differential diagnosis on the entire nerve. For traumatic nerve injuries, imaging, predominantly ultrasound, occasionally provides essential information for management including the type of nerve lesion, its exact site and local extension

Nutrients

Vitamin K participates in brain physiology. This study aimed to determine whether using vitamin K antagonists (VKAs), which interfere with the vitamin K cycle, were (i) cross-sectionally associated with altered cognitive performance, and (ii) independent predictors of cognitive changes in older adults over 24 months. Information was collected on the use of VKAs (i.e., warfarin, acenocoumarol, and fluindione) among 378 geriatric outpatients (mean, 82.3 +/- 5.6 years; 60.1% female). Global cognitive performance and executive functions were assessed with Mini-Mental State Examination (MMSE) and Frontal Assessment Battery (FAB) scores, respectively, at baseline and after 12 and 24 months of follow-up. Age, gender, body mass index, mean arterial pressure, disability, gait speed, comorbidities, atrial fibrillation, stroke, carotid artery stenosis, leukoaraiosis grade on computed tomography (CT) scan, psychoactive drugs, antidementia drugs, blood-thinning drugs (i.e., anticoagulants other than VKAs, antiplatelet medications), serum creatinine levels, and vitamin B12 concentrations were considered as potential confounders. Using VKAs was associated with lower (i.e., worse) FAB score at baseline (adjusted beta = -2.1, p = 0.026), and with a decrease in FAB score after 24 months (adjusted beta = -203.6%, p = 0.010), but not after 12 months (p = 0.659). Using VKAs was not associated with any change in MMSE score at baseline (p = 0.655), after 12 months (p = 0.603), or after 24 months (p = 0.201). In conclusion, we found more severe executive dysfunction at baseline and incident executive decline over 24 months among geriatric patients using VKAs, when compared with their counterparts

Pattern fluctuations in transitional plane Couette flow

In wide enough systems, plane Couette flow, the flow established between two parallel plates translating in opposite directions, displays alternatively turbulent and laminar oblique bands in a given range of Reynolds numbers R. We show that in periodic domains that contain a few bands, for given values of R and size, the orientation and the wavelength of this pattern can fluctuate in time. A procedure is defined to detect well-oriented episodes and to determine the statistics of their lifetimes. The latter turn out to be distributed according to exponentially decreasing laws. This statistics is interpreted in terms of an activated process described by a Langevin equation whose deterministic part is a standard Landau model for two interacting complex amplitudes whereas the noise arises from the turbulent background.Comment: 13 pages, 11 figures. Accepted for publication in Journal of statistical physic

Higher vitamin D dietary intake is associated with lower risk of alzheimer's disease: a 7-year follow-up

BACKGROUND: Hypovitaminosis D is associated with cognitive decline among older adults. The relationship between vitamin D intakes and cognitive decline is not well understood. Our objective was to determine whether the dietary intake of vitamin D was an independent predictor of the onset of dementia within 7 years among women aged 75 years and older.METHODS: Four hundred and ninety-eight community-dwelling women (mean, 79.8 3.8 years) free of vitamin D supplements from the EPIDemiology of OSteoporosis Toulouse cohort study were divided into three groups according to the onset of dementia within 7 years (ie, no dementia, Alzheimer\u27s disease [AD], or other dementias). Baseline vitamin D dietary intakes were estimated from self-administered food frequency questionnaire. Age, body mass index, initial cognitive performance, education level, physical activity, sun exposure, disability, number of chronic diseases, hypertension, depression, use of psychoactive drugs, and baseline season were considered as potential confounders. RESULTS: Women who developed AD (n = 70) had lower baseline vitamin D intakes (mean, 50.3 19.3 mug/wk) than nondemented (n = 361; mean intake = 59.0 29.9 mug/wk, p = .027) or those who developed other dementias (n = 67; mean intake = 63.6 38.1 mug/wk, p = .010). There was no difference between other dementias and no dementia (p = .247). Baseline vitamin D dietary intakes were associated with the onset of AD (adjusted odds ratio = 0.99 [95% confidence interval = 0.98-0.99], p = .041) but not with other dementias (p = .071). Being in the highest quintile of vitamin D dietary intakes was associated with a lower risk of AD compared with the lower 4 quintiles combined (adjusted odds ratio = 0.23 [95% confidence interval = 0.08-0.67], p = .007). CONCLUSIONS: Higher vitamin D dietary intake was associated with a lower risk of developing AD among older women

Analytical ultracentrifugation and preliminary X-ray studies of the chloroplast envelope quinone oxidoreductase homologue from Arabidopsis thaliana.

International audienceQuinone oxidoreductases reduce a broad range of quinones and are widely distributed among living organisms. The chloroplast envelope quinone oxidoreductase homologue (ceQORH) from Arabidopsis thaliana binds NADPH, lacks a classical N-terminal and cleavable chloroplast transit peptide, and is transported through the chloroplast envelope membrane by an unknown alternative pathway without cleavage of its internal chloroplast targeting sequence. To unravel the fold of this targeting sequence and its substrate specificity, ceQORH from A. thaliana was overexpressed in Escherichia coli, purified and crystallized. Crystals of apo ceQORH were obtained and a complete data set was collected at 2.34 Å resolution. The crystals belonged to space group C2221, with two molecules in the asymmetric unit