Seeing the Past from Nowhere: Images and Science in Archaeology

Between 1968 and 1975, international and multidisciplinary rescue excavations were undertaken in Eastern Turkey before the construction of the Keban Dam. This article focuses on three specific visual techniques (the artifact typology, the trench shot, and the gridded map) found in the site reports of this salvage project, in order to analyze the way archaeology visually defines its object(s) of study. While scientific excavations make discoveries of the past visible, their representations in the discipline’s final publications conceal the human agents responsible for them. In other words, as tools of visualization foreground archaeological knowledge, the conditions of its production are concurrently sidelined. By relegating the messy process of “digging” to the background, archaeology’s techniques of visualization allow its practitioners to see the past, and all of its objects, from a distant present located “nowhere.

The impact of ocean acidification on the functional morphology of foraminifera

This work was supported by the NERC UK Ocean Acidification Research Programme grant NE/H017445/1. WENA acknowledges NERC support (NE/G018502/1). DMP received funding from the MASTS pooling initiative (The Marine Alliance for Science and Technology for Scotland). MASTS is funded by the Scottish Funding Council (grant reference HR09011) and contributing institutions.Culturing experiments were performed on sediment samples from the Ythan Estuary, N. E. Scotland, to assess the impacts of ocean acidification on test surface ornamentation in the benthic foraminifer Haynesina germanica. Specimens were cultured for 36 weeks at either 380, 750 or 1000 ppm atmospheric CO2. Analysis of the test surface using SEM imaging reveals sensitivity of functionally important ornamentation associated with feeding to changing seawater CO2 levels. Specimens incubated at high CO2 levels displayed evidence of shell dissolution, a significant reduction and deformation of ornamentation. It is clear that these calcifying organisms are likely to be vulnerable to ocean acidification. A reduction in functionally important ornamentation could lead to a reduction in feeding efficiency with consequent impacts on this organism’s survival and fitness.Publisher PDFPeer reviewe

Devenir, former, recruter un géomaticien : Petit guide pratique de la géomatique à destination des employeurs, des candidats et des formateurs

Document pdf disponible sur le site de l'AFIGEOPublié à l'occasion du Colloque national " Métiers et compétences en géomatique : des formations aux emplois " le 14 novembre 2013 au CNAM, ce guide est le fruit d'une réflexion collective menée au sein du Pôle Formation-Recherche de l'AFIGEO. S'appuyant sur de nombreuses ressources (issues des résultats d'une enquête métier réalisée en 2013 avec GeoRezo et le GDR Magis, d'analyse de fiches de poste, de l'observatoire des GeoFormations, de la démarche de reconnaissance des métiers), il s'organise autour de 4 chapitres : - QU'EST-CE QUE LA GEOMATIQUE ? - A QUOI SERT UN GEOMATICIEN ? - SE FORMER A LA GEOMATIQUE ? - RECRUTER UN GEOMATICIEN ? En s'adressant aux étudiants, formateurs, recruteurs, géomaticiens débutants ou plus expérimentés, ce guide vise à apporter un éclairage pédagogique, concret sur le vaste monde de la géomatique, sur les spécificités des compétences, des métiers et des formations associés. Pour recevoir la version numérique du Guide, nous vous remercions de compléter le formulaire de demande suivant : https://docs.google.com/forms/d/1MYxjzslEeLd4VwsdOKwtxJyZwVLaLNv7d_lBj_mPGlM/viewfor

Li/Mg systematics in scleractinian corals: Calibration of the thermometer

We show that the Li/Mg systematics of a large suite of aragonitic coral skeletons, representing a wide range of species inhabiting disparate environments, provides a robust proxy for ambient seawater temperature. The corals encompass both zooxanthellate and azooxanthellate species (Acropora sp., Porites sp., Cladocora caespitosa, Lophelia pertusa, Madrepora oculata and Flabellum impensum) collected from shallow, intermediate, and deep-water habitats, as well as specimens cultured in tanks under temperature-controlled conditions. The Li/Mg ratios observed in corals from these diverse tropical, temperate, and deep-water environments are shown to be highly correlated with temperature, giving an exponential temperature relationship of: Li/Mg (mmol/mol) = 5.41 exp (−0.049 * T) (r² = 0.975, n = 49). Based on the standard error of the Li/Mg versus temperature correlation, we obtain a typical precision of ±0.9 °C for the wide range of species analysed, similar or better than that of other less robust coral temperature proxies such as Sr/Ca ratios.The robustness and species independent character of the Li/Mg temperature proxy is shown to be the result of the normalization of Li to Mg, effectively eliminating the precipitation efficiency component such that temperature remains as the main controller of coral Li/Mg compositions. This is inferred from analysis of corresponding Li/Ca and Mg/Ca ratios with both ratios showing strong microstructure-related co-variations between the fibrous aragonite and centres of calcification, a characteristic that we attribute to varying physiological controls on growth rate. Furthermore, Li/Ca ratios show an offset between more rapidly growing zooxanthellate and azooxanthellate corals, and hence only an approximately inverse relationship to seawater temperature. Mg/Ca ratios show very strong physiological controls on growth rate but no significant dependence with temperature, except possibly for Acropora sp. and Porites sp. A strong positive correlation is nevertheless found between Li/Ca and Mg/Ca ratios at similar temperatures, indicating that both Li and Mg are subject to control by similar growth mechanisms, specifically the mass fraction of aragonite precipitated during calcification, which is shown to be consistent with a Rayleigh-based elemental fractionation model.The highly coherent array defined by Li/Mg versus temperature is thus largely independent of coral calcification mechanisms, with the strong temperature dependence reflecting the greater sensitivity of the KdLi/Ca partition coefficient relative to KdMg/Ca. Accordingly, Li/Mg ratios exhibit a highly coherent exponential correlation with temperature, thereby providing a more robust tool for reconstructing paleo-seawater temperatures

Impact of seawater sulfate concentration on sulfur concentration and isotopic composition in calcite of two cultured benthic foraminifera

Marine sediments can be used to reconstruct the evolution of seawater [SO42-] and δ34S over time, two key parameters that contribute to refine our understanding of the sulfur cycle and thus of Earth's redox state. δ34S evolution can be measured from carbonates, barites and sulfate evaporites. [SO42-] variations can be reconstructed using fluid inclusions in halites, a method that only allows a low-resolution record. Reconstruction of the past sulfur cycle could be improved if carbonates allowed the tracking of both seawater δ34S and [SO42-] variations in a sole, continuous sedimentary repository. However, most primary carbonates formed in the ocean are biogenic, and organisms tend to overprint the geochemical signatures of their carbonates through a combination of processes often collectively referred to as vital effects. Hence, calibrations are needed to allow seawater δ34S and [SO42-] reconstructions based on biogenic carbonates. Because foraminifera are important marine calcifiers, we opted to focus on calcite synthesized by individuals of rosalinid benthic foraminifera cultured in the laboratory under controlled conditions, with varying seawater [SO42-] (ranging from 0 to 180 mM). Our experimental design allowed us to obtain foraminiferal asexual reproduction over several generations. We measured bulk carbonate-associated sulfate (CAS) content and sulfur isotopic composition (δ34SCAS) on samples of tens to hundreds of specimens from a selection of culture media, where [SO42-] varied from 5 to 60 mM. Increasing or decreasing [SO42-] with respect to modern-day seawater concentration (28 mM) impacted foraminiferal population size dynamics and the total amount of bioprecipitated carbonate. Foraminiferal CAS concentration increased proportionally with [SO42-] concentration from 5 mM up to 28 mM and then showed a plateau from 28 to 60 mM. The existence of a threshold at 28 mM is interpreted as the result of a control on the precipitation fluid chemistry that foraminifera exert on the carbonate precipitation loci. However, at high seawater sulfate concentrations (&gt; 40 mM) the formation of sulfate complexes with other cations may partially contribute to the non-linearity of the CAS concentration in foraminiferal tests at high increases in [SO42-]. Yet, despite the significant effect of seawater [SO42-] on foraminiferal reproduction and on CAS incorporation, the isotopic fractionation between CAS and seawater remains stable through varying seawater [SO42-]. Altogether, these results illustrate that CAS in biogenic calcite could constitute a good proxy for both seawater [SO42-] and δ34S and suggests that sulfate likely plays a role in foraminiferal biomineralization and biological activity.</p

Evolution of hypoxia and hypoxia-inducible factor asparaginyl hydroxylase regulation in chronic kidney disease

Background The roles of hypoxia and hypoxia inducible factor (HIF) during chronic kidney disease (CKD) are much debated. Interventional studies with HIF-α activation in rodents have yielded contradictory results. The HIF pathway is regulated by prolyl and asparaginyl hydroxylases. While prolyl hydroxylase inhibition is a well-known method to stabilize HIF-α, little is known about the effect asparaginyl hydroxylase factor inhibiting HIF (FIH). Methods We used a model of progressive proteinuric CKD and a model of obstructive nephropathy with unilateral fibrosis. In these models we assessed hypoxia with pimonidazole and vascularization with three-dimensional micro-computed tomography imaging. We analysed a database of 217 CKD biopsies from stage 1 to 5 and we randomly collected 15 CKD biopsies of various severity degrees to assess FIH expression. Finally, we modulated FIH activity in vitro and in vivo using a pharmacologic approach to assess its relevance in CKD. Results In our model of proteinuric CKD, we show that early CKD stages are not characterized by hypoxia or HIF activation. At late CKD stages, some areas of hypoxia are observed, but these are not colocalizing with fibrosis. In mice and in humans, we observed a downregulation of the HIF pathway, together with an increased FIH expression in CKD, according to its severity. Modulating FIH in vitro affects cellular metabolism, as described previously. In vivo, pharmacologic FIH inhibition increases the glomerular filtration rate of control and CKD animals and is associated with decreased development of fibrosis. Conclusions The causative role of hypoxia and HIF activation in CKD progression is questioned. A pharmacological approach of FIH downregulation seems promising in proteinuric kidney disease

An evaluation of staining techniques for marking daily growth in scleractinian corals

Author Posting. © The Author(s), 2012. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Journal of Experimental Marine Biology and Ecology 440 (2013): 126-131, doi:10.1016/j.jembe.2012.12.003.In situ skeletal markers have been widely used to quantify skeletal growth rates of scleractinian corals on sub-annual time-scales. Nevertheless, an evaluation of different techniques, both in terms of their efficacy and potential impacts on the growth process itself, has not been undertaken. Here the effects of exposure to four different dyes (alizarin, alizarin complexone, calcein, oxytetracycline) and isotope spikes (Ba and Sr) on the growth rates of scleractinian corals are compared. Oxytetracycline increased coral growth. Alizarin, alizarin complexone, calcein, and Sr and Ba isotope spikes had no significant effect on coral growth, but polyp extension appeared reduced during exposure to alizarin and alizarin complexone. Calcein provided a more intense fluorescent mark than either alizarin or alizarin complexone. Isotope spikes were challenging to locate using isotope ratio analysis techniques. Thus, calcein appears best suited for marking short-term calcification increments in corals, while a combination of alizarin or alizarin complexone and calcein may be useful for dual labeling experiments as there is little overlap in their fluorescence spectra.Funding for this work was provided by a Lizard Island Doctoral Fellowship, the Ocean Life Institute, NSF OCE-1041106, and an International Society for Reef Studies / Ocean Conservancy Fellowship. This material is based upon work supported under a National Science Foundation Graduate Research Fellowship and a National Science Foundation International Post-Doctoral Fellowship

Temperature calibration of Mg/Ca ratios in the intermediate water benthic foraminifer Hyalinea balthica

Author Posting. © American Geophysical Union, 2011. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry Geophysics Geosystems 12 (2011): Q04003, doi:10.1029/2010GC003333.Core top samples from Indonesian and northeast Atlantic depth transects were used to calibrate Mg/Ca and δ18O in tests of the calcitic benthic foraminifer Hyalinea balthica to bottom water temperature between 4°C and 13°C. This shallow infaunal species is primarily abundant in neritic to upper bathyal sediments (<600 m). Both linear and exponential calibrations suggest a temperature sensitivity of ~12% per °C that is ~4 times higher than observed in other species of deep-sea benthic foraminifera. Culture experiments support the core top calibration. We find no discernible effect of salinity and saturation on Mg/Ca. Comparison between the measured benthic foraminiferal δ18O and predicted equilibrium values suggests that on average H. balthica δ18O is 0.64‰ ± 0.13‰ lower than predicted from the equilibrium composition. To test the reliability of using paired H. balthica Mg/Ca and δ18O measurements for reconstructing seawater δ18Osw and salinity, we apply this calibration to another depth transect from Cape Ghir off NW Africa, which was not included in the calibration. Based on error analysis of the calibration data and this validation test, we show that the uncertainty of reconstructing bottom water temperature and salinity from paired Mg/Ca and δ18O measurements of H. balthica is better than ±0.7°C and ±0.69 practical salinity scale, respectively. The small uncertainties allow for the reconstruction of seawater density to better than 0.3σθ units, which is precise enough for the identification of specific water masses and reconstruction of changes in their properties. We propose that the relatively high Mg content and temperature sensitivity of H. balthica might be due to minor, biologically mediated contribution of high-Mg calcite to the primarily low Mg calcite test, which is influenced by the ambient temperature. This hypothesis, if correct, suggests that benthic species with relatively high Mg/Ca may be better suited for deepwater temperature reconstructions than species that have thus far been more commonly used.This project was funded by NSF Awards OCE 02‐20922 and 09‐02977 to YR, OCE 09‐28607 to MK, OCE02‐20776 to DWO, and DFG priority program INTERDYNAMIK to AM