Uncertainties and standardization in the absolute reference frame

International audienceMass spectrometric methods for clumped isotopes have evolved considerably over the past decade, in large part because of the need to correct for various “nonlinearities”, which may be negligible in conventional analysis of singly-substituted isotopologues but manifest as large bias in clumped isotope measurements. In the case of CO2 and carbonates, correcting for these nonlinearities yields Δ47 values expressed in the "absolute" reference frame of Dennis et al. (2011). There is, however, no precise consensus regarding the actual implementation of these various corrections, including the use of in-lab and international standards. We propose that a useful way forward is to quantitatively assess the statistical uncertainties associated with the various corrections we all perform in one form or another. Comparing the merits and limitations of various standardization strategies illustrates how the optimal one will vary between laboratories, and highlights the critical need for one to three reliable international carbonate standards. Although several of these strategies are already used, more or less formally, we believe that this comparison exercise provides a good starting point for discussion

High-precision laser spectroscopy of H 2 S for simultaneous probing of multiple-sulfur isotopes

The simultaneous monitoring of the triple stable S-isotopes ( 32 S, 33 S and 34 S) of hydrogen sulfide has been conducted with a VCOF-CRDS set-up (a V-shaped cavity for optical feedback coupled to a cavity ring down spectrometer)

Assessing the potential of brachiopod shell geochemistry as a recorder of past sea-water temperatures and oxygen isotope composition.

International audienc

Assessing the potential of brachiopod shell geochemistry as a recorder of past sea-water temperatures and oxygen isotope composition.

International audienc

Polar sea temperature and δ18Osw during the Toarcian Oceanic Anoxic Event.

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Polar sea temperature and δ18Osw during the Toarcian Oceanic Anoxic Event.

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Croissance et signal géochimique chez les bivalves : quels enseignements pour les reconstitutions paléoenvironnementales ?

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InterCarb: A Community Effort to Improve Interlaboratory Standardization of the Carbonate Clumped Isotope Thermometer Using Carbonate Standards

Increased use and improved methodology of carbonate clumped isotope thermometry has greatly enhanced our ability to interrogate a suite of Earth-system processes. However, interlaboratory discrepancies in quantifying carbonate clumped isotope (Δ47) measurements persist, and their specific sources remain unclear. To address interlaboratory differences, we first provide consensus values from the clumped isotope community for four carbonate standards relative to heated and equilibrated gases with 1,819 individual analyses from 10 laboratories. Then we analyzed the four carbonate standards along with three additional standards, spanning a broad range of δ47 and Δ47 values, for a total of 5,329 analyses on 25 individual mass spectrometers from 22 different laboratories. Treating three of the materials as known standards and the other four as unknowns, we find that the use of carbonate reference materials is a robust method for standardization that yields interlaboratory discrepancies entirely consistent with intralaboratory analytical uncertainties. Carbonate reference materials, along with measurement and data processing practices described herein, provide the carbonate clumped isotope community with a robust approach to achieve interlaboratory agreement as we continue to use and improve this powerful geochemical tool. We propose that carbonate clumped isotope data normalized to the carbonate reference materials described in this publication should be reported as Δ47 (I-CDES) values for Intercarb-Carbon Dioxide Equilibrium Scale

Non-IgE mediated mast cell activation

International audienceMast cells (MCs) are innate immune cells that are scattered in tissues throughout the organism being particularly abundant at sites exposed to the environment such as the skin and mucosal surfaces. Generally known for their role in IgE-mediated allergies, they have also important functions in the maintenance of tissue integrity by constantly sensing their microenvironment for signals by inflammatory triggers that can comprise infectious agents, toxins, hormones, alarmins, metabolic states, etc. When triggered their main function is to release a whole set of inflammatory mediators, cytokines, chemokines, and lipid products. This allows them to organize the ensuing innate immune and inflammatory response in tight coordination with resident tissue cells, other rapidly recruited immune effector cells as well as the endocrine and exocrine systems of the body. To complete these tasks, MCs are endowed with a large repertoire of receptors allowing them to respond to multiple stimuli or directly interact with other cells. Here we review some of the receptors expressed on MCs (ie, receptors for Immunoglobulins, pattern recognition receptors, nuclear receptors, receptors for alarmins, and a variety of other receptors) and discuss their functional implication in the immune and inflammatory response focusing on non-IgE-mediated activation mechanisms.© 2018 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd