Rapid Na, Cu exchange between synthetic fluid inclusions and external aqueous solutions: evidence from LA-ICP-MS analysis

Three sets of equilibration experiments (Set 1 to Set 3) were performed in cold-seal pressure vessels to investigate the compositional modification of quartz-hosted fluid inclusions after entrapment. Each set of experiment consisted of two stages. In a pre-run, fluid inclusions containing 5–10 wt% NaCl and selected trace elements were synthesized at 700°C/140–200 MPa. These samples were then loaded into new capsules together with Cu-bearing solutions and some mineral buffers, and re-equilibrated at 600–800°C and 70–140 MPa for 6–8 days. LA-ICP-MS analysis of individual fluid inclusions reveals that in re-equilibration experiments in which the outer fluid was composed of KCl (±FeCl₂) up to 83% of the original Na content of pre-existing fluid inclusions were lost, and up to 5660 ppm Cu were gained. Other elements with larger ionic radii (i.e. K, Fe, Ba, Sr) were not exchanged, demonstrating that the inclusions remained physically intact and that Na and Cu were transported through quartz by diffusion. The observed Na loss from pre-existing fluid inclusions correlates positively with Cu gain, with about 1 Cu atom being gained per 10 Na atoms lost. Thus, Na and Cu (plus probably H) were exchanged by interdiffusion. Remarkably, this processes resulted in up to 10 times higher Cu concentrations in re-equilibrated inclusions than were present in the outer fluid, i.e. Cu diffused 'uphill'. Large variations of Cu concentrations relative to the concentration of other elements are common also in natural fluid inclusion assemblages. However, no evidence for a correlation between Cu content and Na content was found so far, suggesting that Cu diffusion in natural samples may be dominated by processes other than Na–Cu interdiffusion.     

À propos du colloque « The Machine as Model and Metaphor » Max-Planck-Institut für Wissenschaftsgeschichte Berlin,novembre 2006

Sans résumé ? Lève la peau, dissèque: ici commencent les machines. Puis, tu te perds dans une substance inexplicable, étrangère à tout ce que tu sais et qui est pourtant l’essentielle. ? Paul Valéry, Tel quel, Cahier B 1910 Ses recherches portent sur l’épistémologie, l’histoire des sciences et l’histoire de la philosophie à l’age classique (xvi ^e-xvii ^e siècles). Elle a notamment dirigé avec Walter Roy Laird, Mechanics and Natural Philosophy before the Scientific Revolution (Dortrecht/Boston/Londres, Kluwer Academic Publishers, 2007), puis, en collaboration avec Massimo Bucciantini et Michele Camerota, Mechanics and Cosmology in the Medieval and Early Modern Period (Florence, Olschki, 2007).     

Relating the Ancient Ona Culture to the Wider Northern Horn: Discerning Patterns and Problems in the Archaeology of the First Millennium BC

Archaeological research carried out between 1998 and 2003 on the Asmara Plateau of Eritrea has provided new insights concerning the development of early-to-mid first millennium BC settled agropastoral communities in the northern Horn of Africa. The settlement, subsistence, and material culture of these communities in the greater Asmara area, referred to as the “Ancient Ona culture,” bear both unique qualities and striking similarities to coeval communities in Tigray, Ethiopia. This article provides an overview of regional settlement data and ceramic and lithic traditions from the greater Asmara area, drawing comparisons to other contexts of this period in the archaeology of the wider northern Horn. It is argued that we can see among the Ancient Ona sites distinct localized cultural expressions and development as well as strong links to a wider first millennium BC macro-cultural identity.     

The First Millennium <Emphasis Type="SmallCaps">bc</Emphasis> in the Highlands of Northern Ethiopia and South–Central Eritrea: A Reassessment of Cultural and Political Development

An overview is offered of the development of research—both archaeological and epigraphic—on the inhabitants of the northern Horn during the first millennium bc. Initially, reconstructions of this period placed considerable emphasis on links with southern Arabia and tended to group those into a single cultural category that was designated ‘Pre-Aksumite’. It is now argued that long-distance contacts were much less pervasive, being largely restricted to the élite, and that other aspects of life—including much material culture and subsistence economy—displayed strong local continuity from earlier times. Similarly, it is argued that interpretation of the epigraphic evidence as indicating a single ‘Pre-Aksumite’ state called D'MT is unjustified.     

Mycobacterium leprae genotype amplified from an archaeological case of lepromatous leprosy in Central Asia

We have amplified Mycobacterium leprae DNA from the skeleton of an adult human female exhibiting signs of lepromatous leprosy (LL). The remains were excavated from the site of Devkesken 6 on the Ustyurt plateau of Uzbekistan and date to between the 1st and 4th centuries AD. Recovered DNA was fragmented but of sufficient quality and quantity to allow a series of biomolecular genotyping methods to be applied. These methods included variable nucleotide tandem repeat (VNTR) typing of two microsatellite and one minisatellite regions and also single-nucleotide polymorphism (SNP) typing for nine informative loci.Genotyping showed that the causative strain of M. leprae exhibited a SNP-type 3 profile, characteristic of cases associated geographically with Europe and North Africa. Further SNP sub-typing was performed and the data obtained from the Uzbek leper was compared with the same loci amplified from a case of LL recovered from Blackfriars, Ipswich, UK dating to between the 13th and 16th centuries AD. Unique group 3 subtypes were found in both the Uzbek case and Ipswich 1914. These appear to be ancestral to recent type 3 strains. Mycolic acid analysis confirmed the presence of M. leprae in the Uzbek samples. Phylogenetically informative SNPs and other polymorphic loci will contribute to the study of human migrations, as well as the origin and spread of leprosy.     

Biomolecular archaeology of ancient tuberculosis: response to “Deficiencies and challenges in the study of ancient tuberculosis DNA” by Wilbur et al. (2009)

It is sixteen years since the first detection of Mycobacterium tuberculosis DNA in archaeological specimens, yet the validity of findings continues to be questioned. Rigorous scientific scrutiny and debate is valuable and has led to a coalescence of procedures and precautions amongst those actively engaged in this work. It is disappointing that these good practices are not recognised by certain scientists whose primary expertise is in the related fields of archaeology, palaeopathology, and eukaryote ancient DNA. There is a danger that by constant repetition, disputable and inadequately justified concerns will assume the status of self-perpetuating myths and misunderstandings. We discuss these issues with reference to a recent article in this journal, in which clear peer-reviewed scientific data were specifically targeted as part of a general critique of the field of the palaeomicrobiology of tuberculosis. We believe we have given sufficient evidence and cogent argument to persuade the unbiased reader that the views in the critique by Wilbur et al. are unjustified.