In the opening pages of Marilou Awiakta’s Selu: Seeking the Corn-Mother’s Wisdom, the author offers a metacommentary on her delightfully hybrid text, likening it to a “double-woven basket (Cherokee-style).” The image resonates on many levels with the author’s tribal traditions and thus serves to foreshadow the text’s wealth of material on Cherokee culture and history, but readers soon discover that Awiakta actually integrates the design of the double-woven basket into the very form of her text. In so doing she produces a book that through its combination of circularity and quadratic symmetry resists the linearity of traditional Western narrative and challenges many of the epistemological assumptions that follow from that tradition. My reading of Selu builds on a recognition and appreciation of the form of the text by examining a less explicit but, I argue, equally significant manner in which the double-weave basket structure serves as a metaphor for the text’s complex autobiographical dimensions. In particular, the double-weave design of traditional Cherokee basketry is replicated not only in Awiakta’s affirmation of both her Celtic-Appalachian and Eastern Band Cherokee roots but also in her simultaneous expression of a collective tribal identity and an individualistic artistic identity. Throughout Selu Awiakta demonstrates her ability to weave back and forth between autoethnography, on the one hand, in which her representation of selfhood is collective, virtually inseparable from her insider’s explanations of Cherokee myths, history, and cultural practices, and conventional Western autobiography, on the other hand, in which she gives a narrative account of the development of an autonomous, in this case artistic, identity. This autobiographical double-weave of relational and autonomous modes of subjectivity, of identification and individuation, underscores Mick McAllister’s observation that “an American Indian autobiography is by its nature a bicultural document.” It also serves as a good example of what Arnold Krupat has called, in a different context, a cosmopolitan critical perspective, in which American Indians and members of other historically marginalized groups are negotiating with increasing deftness competing socially constructed definitions of selfhood to find discursive freedom in the cultural borderlands.

Kinetic calcium isotope effects can be used as growth-rate proxies for volcanic and subvolcanic minerals. Here, we analyze Ca isotopic compositions in experimental and natural samples and confirm that large kinetic effects (>2‰) can occur during magmatic plagioclase crystallization. Experiments confirm theoretical predictions that disequilibrium isotope effects depend mainly on the rates for crystal growth relative to liquid phase Ca diffusivity (R/D). Plagioclase phenocrysts from the 1915 Mount Lassen rhyodacite eruption, the ∼650-y-old Deadman Creek Dome eruption, and several mafic subvolcanic orbicules and plagioclase comb layers from Northern California have disequilibrium Ca isotopic compositions that suggest rapid crystal growth rates (>1 cm/y to 15 cm/y). The Ca isotope results, combined with complementary crystal-size distribution analyses, suggest that magmatic rejuvenation (and eruption) events, as reflected in crystal growth times, can be as short as ∼10^-3 y. Although mafic systems are predicted to have shorter magmatic rejuvenation periods, we find similarly short timescales in both mafic and silicic systems. These results are consistent with a growing body of evidence suggesting that dominantly crystalline volcanic magma reservoirs can be rapidly reactivated by the injection of fresh magma prior to eruption. By focusing on a common mineral such as plagioclase, this approach can be applied across all major magmatic compositions, suggesting that Ca isotopes can be used as a tool for investigating the dynamics and timing of volcanic eruptions.

Abstract: Foraminifera are unicellular organisms that inhabit the oceans. They play an important role in the global carbon cycle and record valuable paleoclimate information through the uptake of trace elements such as strontium into their calcitic shells. Understanding how foraminifera control their internal fluid composition to make calcite is important for predicting their response to ocean acidification and for reliably interpreting the chemical and isotopic compositions of their shells. Here, we model foraminiferal calcification and strontium partitioning in the benthic foraminifera Cibicides wuellerstorfi and Cibicidoides mundulus based on insights from inorganic calcite experiments. The numerical model reconciles inter-ocean and taxonomic differences in benthic foraminifer strontium partitioning relationships and enables us to reconstruct the composition of the calcifying fluid. We find that strontium partitioning and mineral growth rates of foraminiferal calcite are not strongly affected by changes in external seawater pH (within 7.8–8.1) and dissolved inorganic carbon (DIC, within 2100–2300 μmol/kg) due to a regulated calcite saturation state at the site of shell formation.

The Cedars ultramafic block hosts alkaline springs (pH > 11) in which calcium carbonate forms upon uptake of atmospheric CO2 and at times via mixing with surface water. These processes lead to distinct carbonate morphologies with “floes” forming at the atmosphere-water interface, “snow” of fine particles accumulating at the bottom of pools and terraced constructions of travertine. Floe material is mainly composed of aragonite needles despite CaCO3 precipitation occurring in waters with low Mg/Ca (<0.01). Precipitation of aragonite is likely promoted by the high pH (11.5–12.0) of pool waters, in agreement with published experiments illustrating the effect of pH on calcium carbonate polymorph selection. The calcium carbonates exhibit an extreme range and approximately 1:1 covariation in δ13C (−9 to −28‰ VPDB) and δ18O (0 to −20‰ VPDB) that is characteristic of travertine formed in high pH waters. The large isotopic fractionations have previously been attributed to kinetic isotope effects accompanying CO2 hydroxylation but the controls on the δ13C-δ18O endmembers and slope have not been fully resolved, limiting the use of travertine as a paleoenvironmental archive. The limited areal extent of the springs (∼0.5 km2) and the limited range of water sources and temperatures, combined with our sampling strategy, allow us to place tight constraints on the processes involved in generating the systematic C and O isotope variations. We develop an isotopic reaction–diffusion model and an isotopic box model for a CO2-fed solution that tracks the isotopic composition of each dissolved inorganic carbon (DIC) species and CaCO3. The box model includes four sources or sinks of DIC (atmospheric CO2, high pH spring water, fresh creek water, and CaCO3 precipitation). Model parameters are informed by new floe Δ44Ca data (−0.75 ± 0.07‰), direct mineral growth rate measurements (4.8 to 8 × 10−7 mol/m2/s) and by previously published elemental and isotopic data of local water and DIC sources. Model results suggest two processes control the extremes of the array: (1) the isotopically light end member is controlled by the isotopic composition of atmospheric CO2 and the kinetic isotope fractionation factor (KFF (‰) = (α − 1) × 1000) accompanying CO2 hydroxylation, estimated here to be −17.1 ± 0.8‰ (vs. CO2(aq)) for carbon and −7.1 ± 1.1‰ (vs. ‘CO2(aq) + H2O’) for oxygen at 17.4 ± 1.0 °C. Combining our results with revised CO2 hydroxylation KFF values based on previous work suggests consistent KFF values of −17.0 ± 0.3‰ (vs. CO2(aq)) for carbon and −6.8 ± 0.8‰ for oxygen (vs. ‘CO2(aq) + H2O’) over the 17–28 °C temperature range. (2) The isotopically heavy endmember of calcium carbonates at The Cedars reflects the composition of isotopically equilibrated DIC from creek or surface water (mostly HCO3-, pH = 7.8–8.7) that occasionally mixes with the high-pH spring water. The bulk carbonate δ13C and δ18O values of modern and ancient travertines therefore reflect the proportion of calcium carbonate formed by processes (1) and (2), with process (2) dominating the carbonate precipitation budget at The Cedars. These results show that recent advances in understanding kinetic isotope effects allow us to model complicated but common natural processes, and suggest ancient travertine may be used to retrieve past meteoric water δ18O and atmospheric δ13C values. There is evidence that older travertine at The Cedars recorded atmospheric δ13C that predates large-scale combustion of fossil fuels.

The authors regret that in the original article, the kinetic fractionation factors (KFFs) related to the CO2 hydroxylation reaction (CO2(aq) + OH– → HCO3–) were calculated using atmospheric δ18OCO2 values of 0.0 ± 0.5 ‰ (VPDB) while the correct values are 10.25 ± 0.5 ‰ (VPDB). We erroneously employed the atmospheric δ18OCO2 values from the NOAA CO2 global network (Trolier et al., 1996) by not converting atmospheric δ18OCO2 from the VPDB-CO2 scale to the VPDB scale through the following expression (e.g. Srivastava and Verkouteren, 2018): [Formula presented] This correction affects the reported oxygen isotope KFFs for CO2 hydroxylation to form HCO3– prior to CaCO3 precipitation. We have corrected Table 7 and Fig. 13 accordingly (see below). The composition of atmospheric CO2 was also incorrectly plotted on the VPDB scale in Figs. 1, 8 and 15 of our original manuscript based on previous works (Fig. 8 in Clark and Fontes, 1990; Fig. 2 in Clark et al., 1992). Importantly, the modelling outputs and main conclusions of the original article are not affected by these corrections. Nevertheless, the updated KFFs resolve an apparent discrepancy between the laboratory and field studies in our original article. Moreover, the oxygen isotope KFF for CO2 hydroxylation now displays a positive temperature dependence over the 4–28 °C range, which was not statistically significant in the original article (Fig. 13c, r2 = 0.86, n = 10, p-value <0.01): [Formula presented]where T is in °C, the uncertainty represents one standard error, and KFF* is the oxygen isotope kinetic fractionation factor between the HCO3– product and ‘CO2(aq) + H2O’ expressed as the per mil deviation from unity: [Formula presented] Here and in the original article, the KFF is expressed relative to the weighted sum ‘CO2(aq) + H2O’ rather than ‘CO2(aq) + OH–’ (i.e. the reactants) to avoid the uncertainty on the OH––H2O fractionation factor (Zeebe, 2020; Bajnai and Herwartz, 2021). δ18O and oxygen KFF values in bold have been corrected by converting atmospheric δ18OCO2 values from the VPDB-CO2 scale to the VPDB scale using Eq. (1). The authors apologize for any inconvenience caused.

The Cedars is an area in Northern California with a chain of highly alkaline springs resulting from CO2-charged meteorological water interacting with a peridotite body. Serpentinization resulting from this interaction at depth leads to the sequestration of various carbonate minerals into veins accompanied by a release of Ca2+ and OH– enriched water to the surface, creating an environment which promotes rapid precipitation of CaCO3 at surface springs. This environment enables us to apply the recently developed Δ47-Δ48 dual clumped isotope analysis to probe kinetic isotope effects (KIEs) and timescales of CO2 transformation in a region with the potential for geological CO2 sequestration. We analyzed CaCO3 recovered from various localities and identified significant kinetic fractionations associated with CO2 absorption in a majority of samples, characterized by enrichment in Δ47 values and depletion in Δ48 values relative to equilibrium. Surface floes exhibited the largest KIEs (ΔΔ47: 0.163‰, ΔΔ48: −0.761‰). Surface floe samples begin to precipitate out of solution within the first hour of CO2 absorption, and the dissolved inorganic carbon (DIC) pool requires a residence time of >100 h to achieve isotopic equilibria. The Δ48/Δ47 slope of samples from the Cedars (−3.223 ± 0.519) is within the range of published theoretical values designed to constrain CO2 hydrolysis-related kinetic fractionation (−1.724 to −8.330). The Δ47/δ18O slope (−0.009 ± 0.001) and Δ47/δ13C slope (−0.009 ± 0.001) are roughly consistent with literature values reported from a peridotite in Oman of −0.006 ± 0.002 and −0.005 ± 0.002, respectively. The consistency of slopes in the multi-isotope space suggests the Δ47-Δ48 dual carbonate clumped isotope framework can be applied to study CO2-absorption processes in applied systems, including sites of interest for geological sequestration.

Objective

Disagreement exists between rheumatology and primary care societies regarding gout management. This paper describes a formal process for gathering input from stakeholders in the planning of a trial to compare gout management strategies.

Methods

We recruited patients, nurses, physician assistants, primary care clinicians, and rheumatologists to participate in a modified Delphi panel (mDP) to provide input on design of a trial focused on optimal management for primary care patients with gout. The 16 panelists received a plain-language briefing document that discussed the rationale for the trial, key clinical issues in gout, and aspects of trial design. The panelists also received information and considerations on nine voting questions (VQs), judged to be the key design questions. Cognitive interviews with panelists ensured that the VQs were understood by the range of panelists involved in the mDP. Panelists were asked to score all VQs from 1 (definitely no) to 9 (definitely yes). Two voting rounds were conducted-round 1 by email and round 2 by video conference.

Results

The VQs were modified through the cognitive interviews. The round 1 voting resulted in consensus on eight items, with consensus defined as median voting score in the same tercile (1-3, 4-6 or 7-9). Re-voting at the meeting (round 2) reached consensus on the remaining item.

Conclusion

An mDP with various stakeholders facilitated consensus on the design of a trial of different management strategies for chronic gout. This method may be useful for designing trials of clinical questions with substantial disagreement across stakeholders.

Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives.