Electron Spin Resonance (ESR) Dating of Hominid-Bearing Deposits in the Caverna delle Fate, Ligure, Italy

Stalagmitic floors interstratified with Mousterian deposits from the Caverna delle Fate (Italy) have been dated by the electron spin resonance (ESR) method. Three samples dated fall between 60,000 and 74,000 yr and indicate the age of the Mousterian deposits. They are in good agreement with eges determined by nondestructive "y-ray spectrometry of the human remains from 231Pa/235U and 230Th/234U ratios, which are, respectively, 75,000+21000 -14000 and 82,000 +36000 - 25000 These dates are consistent with the morphological characteristics of the bones as Neanderthal remains

Datation absolue des planchers stalagmitiques de la Grotte du Vallonnet à Roquebrune-Cap-Martin (Alpes-Maritimes) France, par la résonnance de spin électronique (ESR)

International audienceAbsolute dating of thé stalagmitic floors of Vallonnet Cave at Roquebrune-Cap-Martin (Alpes-Maritimes) France, by thé electronic spin résonance method (ESR). Two of Vallonnet Cave's stalagmitic floors are dated by thé electronic spin résonance method (ESR) for thé purpose of dating thé deposit of this cave. For thé base of thé closing stalagmitic floor an âge of 910 000 ± 60 000 years is obtained. For thé top of thé lower stalagmitic floor, an âge of 1 370 000 ±120 000 years is obtained. Given that thé entire deposit of this cave is included between thèse two stalagmitic layers, thé âge of thé continental deposit which contains lithic industry and fauna is between 910 000 ± 60 000 and 1 370 000 ±120 000 years. Thèse âges agrée with thé âges estimated from thé fauna and paleomagnetism.Dans le but de dater le remplissage de la grotte du Vallonnet, deux planchers stalagmitiques de cette grotte ont été datés par la méthode de la résonance de spin électronique (ESR). Pour la base du plancher de fermeture, un âge de 910 000 ± 60 000 ans a été obtenu. Pour le sommet du plancher stalagmitique inférieur, un âge de 1 370 000 ±120 000 ans a été obtenu. Etant donné que tout le remplissage de cette grotte se trouve entre ces deux planchers stalagmitiques, l'âge du remplissage continental qui renferme l'industrie lithique et la faune est compris entre 910 000 ± 60 000 ans et 1 370 000 ±120 000 ans. Ces âges sont en accord avec les âges estimés par la faune et le paléomagnétisme

Production de tritium dans le thorium par des protons de 135 MeV

We have measured the cross-section of tritium production by bombardement of thorium by 135 MeV protons in the Orsay synchro-cyclotron. The tritium was separated from the targets by heating in a graphite crucible with a high-frequency generator, under hydrogen gas pressure. Tritiated water was synthetised and the tritium was measured with liquid scintillator. A value of 19.5 ± 0.05 mbarns was obtained for the tritium-cross section and ten percent of tritons have energies higher than 35 MeV. This large cross-section is attributed to a double pick-up process.On a mesuré la section efficace de production de tritium après bombardment de thorium par des protons de 135 MeV accélérés au synchro-cyclotron d'Orsay. Le tritium était extrait des cibles par chauffage, dans un creuset de graphite, par courants H. F. sous atmosphère d'hydrogène. L'hydrogène tritié était ensuite transformé en eau tritiée et le tritium mesuré au moyen de scintillateur liquide. La section efficace obtenue est de 19,5 ± 0,5 mbarns et dix pour cent des tritons ont une énergie supérieure à 35 MeV. On attribue cette production à un processus de double pick-up

Phylogenomic Reconstruction of the Neotropical Poison Frogs (Dendrobatidae) and Their Conservation

The evolutionary history of the Dendrobatidae, the charismatic Neotropical poison frog family, remains in flux, even after a half-century of intensive research. Understanding the evolutionary relationships between dendrobatid genera and the larger-order groups within Dendrobatidae is critical for making accurate assessments of all aspects of their biology and evolution. In this study, we provide the first phylogenomic reconstruction of Dendrobatidae with genome-wide nuclear markers known as ultraconserved elements. We performed sequence capture on 61 samples representing 33 species across 13 of the 16 dendrobatid genera, aiming for a broadly representative taxon sample. We compare topologies generated using maximum likelihood and coalescent methods and estimate divergence times using Bayesian methods. We find most of our dendrobatid tree to be consistent with previously published results based on mitochondrial and low-count nuclear data, with notable exceptions regarding the placement of Hyloxalinae and certain genera within Dendrobatinae. We also characterize how the evolutionary history and geographic distributions of the 285 poison frog species impact their conservation status. We hope that our phylogeny will serve as a backbone for future evolutionary studies and that our characterizations of conservation status inform conservation practices while highlighting taxa in need of further study

Évaluation des capacités mellifères de différentes variétés de sarrasin

il s'agit d'un type de produit dont les métadonnées ne correspondent pas aux métadonnées attendues dans les autres types de produit : DISSERTATIONÉvaluation des capacités mellifères de différentes variétés de sarrasi

ESR dating of palaeolithic calcite: A comparison between powder and monocrystal spectra with thermal annealing

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L\u27histoire g\ue9n\ue9rale des Batraciens, et la description des cinquante-deux genres et des cent soixante-trois esp\ue8ces des deux premiers sous-ordres: les P\ue9rom\ue8les qui n\u27ont pas de membres, et les Anoures qui sont priv\ue9s de la queue

Volume: 8Start Page: 1End Page: 79

ESR dating of palaeolithic calcite: Fundamental studies

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