Luminescence date and archaeological ages: An epistemology of the luminescence dating

International audienceThermoluminescence is based on the ratio between the accumulated dose and the annual dose rate. It thus acts with the physical meaning of a method of absolute dating, which contains in itself its own calibration. But, because of the high number of parameters, their probabilistic nature, there cannot be single dating. There are only representations that the chronologist has of the true date. That leads us to think of the exact nature of a dating and its place with respect to the true date. So that the dating can be received in a critical way by the archaeologists and be integrated into their own set of knowledge. Mots-clefs : datation par luminescence, équation d'âge, incertitudeLa thermoluminescence utilise le rapport entre la dose accumulée et la dose reçue annuellement. Il s'agit donc au sens physique d'une méthode de datation absolue, qui contient en elle-même sa propre calibration. Mais, du fait du nombre élevé de paramètres, de leurs natures essentiellement probabilistes, il ne peut y avoir de datation unique. Il n'y a que des représentations que le chronologiste a de la date réelle. Cela nous conduit à réfléchir à la nature exacte d'une datation et sa place vis-à-vis de la date réelle. De manière que les datations puissent être reçues de façon critique par les archéologues et s'intégrer à leurs propres corpus de connaissances

Evidence for Sequential and Increasing Activation of Replication Origins along Replication Timing Gradients in the Human Genome

Genome-wide replication timing studies have suggested that mammalian chromosomes consist of megabase-scale domains of coordinated origin firing separated by large originless transition regions. Here, we report a quantitative genome-wide analysis of DNA replication kinetics in several human cell types that contradicts this view. DNA combing in HeLa cells sorted into four temporal compartments of S phase shows that replication origins are spaced at 40 kb intervals and fire as small clusters whose synchrony increases during S phase and that replication fork velocity (mean 0.7 kb/min, maximum 2.0 kb/min) remains constant and narrowly distributed through S phase. However, multi-scale analysis of a genome-wide replication timing profile shows a broad distribution of replication timing gradients with practically no regions larger than 100 kb replicating at less than 2 kb/min. Therefore, HeLa cells lack large regions of unidirectional fork progression. Temporal transition regions are replicated by sequential activation of origins at a rate that increases during S phase and replication timing gradients are set by the delay and the spacing between successive origin firings rather than by the velocity of single forks. Activation of internal origins in a specific temporal transition region is directly demonstrated by DNA combing of the IGH locus in HeLa cells. Analysis of published origin maps in HeLa cells and published replication timing and DNA combing data in several other cell types corroborate these findings, with the interesting exception of embryonic stem cells where regions of unidirectional fork progression seem more abundant. These results can be explained if origins fire independently of each other but under the control of long-range chromatin structure, or if replication forks progressing from early origins stimulate initiation in nearby unreplicated DNA. These findings shed a new light on the replication timing program of mammalian genomes and provide a general model for their replication kinetics

Photography-based taxonomy is inadequate, unnecessary, and potentially harmful for biological sciences

The question whether taxonomic descriptions naming new animal species without type specimen(s) deposited in collections should be accepted for publication by scientific journals and allowed by the Code has already been discussed in Zootaxa (Dubois & Nemésio 2007; Donegan 2008, 2009; Nemésio 2009a–b; Dubois 2009; Gentile & Snell 2009; Minelli 2009; Cianferoni & Bartolozzi 2016; Amorim et al. 2016). This question was again raised in a letter supported by 35 signatories published in the journal Nature (Pape et al. 2016) on 15 September 2016. On 25 September 2016, the following rebuttal (strictly limited to 300 words as per the editorial rules of Nature) was submitted to Nature, which on 18 October 2016 refused to publish it. As we think this problem is a very important one for zoological taxonomy, this text is published here exactly as submitted to Nature, followed by the list of the 493 taxonomists and collection-based researchers who signed it in the short time span from 20 September to 6 October 2016

BLOOM: A 176B-Parameter Open-Access Multilingual Language Model

Large language models (LLMs) have been shown to be able to perform new tasks based on a few demonstrations or natural language instructions. While these capabilities have led to widespread adoption, most LLMs are developed by resource-rich organizations and are frequently kept from the public. As a step towards democratizing this powerful technology, we present BLOOM, a 176B-parameter open-access language model designed and built thanks to a collaboration of hundreds of researchers. BLOOM is a decoder-only Transformer language model that was trained on the ROOTS corpus, a dataset comprising hundreds of sources in 46 natural and 13 programming languages (59 in total). We find that BLOOM achieves competitive performance on a wide variety of benchmarks, with stronger results after undergoing multitask prompted finetuning. To facilitate future research and applications using LLMs, we publicly release our models and code under the Responsible AI License

Apports de la spectrométrie par thermoluminescence à la datation et à la caractérisation.

Usually to avoid black body emission in the red-infrared, thermoluminescence (TL) measurements are monitored only in "UV-Blue" spectral range. However, the development of TL spectrometer readers have shown that the TL spectra are generally complex, with several emissions from UV to near IR. Each emission has its own characteristics, and is more or less suitable to dating. A good choice of spectral ranges investigated provide lot of new informations, and open perspectives to further studies. Hence in the feldspars, the 720-nm emission appears more stable than the others. For the meteorites, the spectral investigations showed a difference in the decay rates between the 420 nm-emission and the 540 nm-emission. This difference could give new informations about terrestrial ages of meteorites.Habituellement les mesures de thermoluminescence (TL) sont effectuées dans le domaine spectrale 'UV-bleu' afin que le signal ne soit pas masqué par l'émission du corps noir dans le rouge et l'infrarouge. Toutefois le développement des appareils de spectrométrie TL a montré que les spectres de thermoluminescence sont composés de plusieurs émissions de l'UV au proche infrarouge. Chacune ayant ses caractéristiques propres, plus ou moins adaptées aux problèmes de la datation, un choix judicieux des domaines spectraux étudiés apporte de nouvelles informations et ouvre des perspectives pour de futures études. Ainsi pour les feldspaths, l'émission à 720 nm apparaît plus stable que les autres. Dans le cas des météorites, les mesures spectrales montrent une cinétique de vidage des pièges différente selon les émissions à 420 mm et 540 mm. Cette différence pourrait apporter de nouveaux renseignements sur l'âge terrestre des météorites.Zink Antoine J. C. Apports de la spectrométrie par thermoluminescence à la datation et à la caractérisation.. In: Revue d'Archéométrie, n°23, 1999. pp. 157-162

Wanderings of a terracotta in the gardens of the Château de Chantilly (Oise, France) Bearded Jupiter, after Michel Anguier (1612-1686)

International audienceThe Musée Condé in Chantilly has a large-scale terracotta sculpture of Jupiter, after Michel Anguier (1612-1686), classified as a historic monument. Restored in 2012 after being damaged by a falling tree, it has been listed in the inventories since June 1822 in the castle park, first at the end of Enghien terrace and then in Sylvie park. It could be identified with the "10-foot terracotta Neptune" preserved in the 18th century in the vertugadin of the Menagerie (Picouleau, 2021). To test this hypothesis, a luminescence dating was requested.As the sculpture is large and executed in two parts, it was not possible to move it in our laboratory, so it was decided to take the sample on site, in a room on the ground floor where it could be easily darkened (doors, shutters, etc.). During the same mission, dose rate measurements were made in different locations that have potentially hosted this artwork since the 18th century. The average annual dose rate was estimated at 130 (13) mGy/a.We carried out measurements by optically stimulated blue luminescence (BL-OSL), as well as by thermoluminescence (TL). We did not observe any infrared emission. The date of the last heating is (with a confidence level of 67%) between 1630 AD and 1720 AD, consistent with a 17th century production. Picouleau F. (2021) La ménagerie de Chantilly (XVIe-XIXe siècles). Editions Faton, 160 p

Le Grand Khorasan : Datation par des méthodes physico-chimiques (carbone 14 et luminescence)

International audienc

Paléocours du delta du Zerafshan (oasis de Boukhara, Ouzbékistan) : premières datations par luminescence

International audienceUne étude en cours sur le delta du Zerafshan qui forme aujourd'hui l'oasis double de Boukhara et Qaraqöl, permet de comprendre l'évolution urbaine en milieu semi-aride en lien avec la gestion des ressources en eau. Afin de fixer la chronologie des paléocours, une première série de datations par OSL a été entreprise. A l'exception d'une branche datant du dernier maximum glaciaire, les autres ont été actives du Néolithique au début de l'âge du bronze, avec un déplacement général du nord-est vers le sud-ouest