Insights on the carbon footprint of radiotherapy in France.

The French healthcare system is responsible for 8% of the national footprint. Achieving a net zero emissions scenario will require a 4-5 fold decrease of carbon emissions in the coming years. The carbon footprint of radiation therapy has not been specifically studied to date. In this review we summarize the content of the carbon footprint dedicated session at the annual meeting of the French society of radiation oncology (SFRO). We discuss the French healthcare system carbon footprint and its major drivers and our work on the estimation of the carbon footprint of external beam radiation therapy in the French setting. We developed a dedicated methodology to estimate the carbon footprint related to radiation therapies, and describe the main drivers of emissions based on a single centre as an example, namely patient's rides, accelerators acquisition and maintenance and data storage. Based on the carbon footprint calculated in our centres, we propose mitigation strategies and an estimation of their respective potential. Our results may be extrapolated to other occidental settings by adapting emission factors (kilograms of carbon per item or euro) to other national settings. External beam radiation therapy has a major carbon footprint that may be mitigated in many ways that may impact how radiation therapy treatments are delivered, as well as the national organization of the radiotherapy sector. This needs to be taken into account when thinking about the future of radiotherapy.

Osteoporosis prevention: where are the barriers to improvement in a French general population? A qualitative study.

We conducted a qualitative study with French men and women in order to provide insight into individuals' experiences, behaviors, and perceptions about osteoporosis (OP) and OP care. The data showed that both sexes, but especially men, were unfamiliar with OP, did not always feel concerned, and mistrusted pharmacological treatments. INTRODUCTION: To engage actively in osteoporosis (OP) prevention, people need to have basic knowledge about the disease. The aim of this qualitative study was to explore knowledge and representations of OP care and prevention among both men and women. METHODS: Focus groups were conducted in the Rhône-Alpes Region, France, with women aged 50-85 years and men aged 60-85 years, with or without a history of fragility fracture and/or an OP diagnosis (respectively referred to as "aware" or "unaware"). A total of 45 women (23 "aware" and 22 "unaware" in 5 and 4 focus groups, respectively) and 53 men (19 "aware" and 34 "unaware" in 3 and 4 focus groups, respectively) were included. A thematic analysis of transcripts was performed to explore knowledge and representations about OP, risk factors, prevention, and treatment. RESULTS: The data showed that both sexes, but especially men, had limited knowledge of OP and considered it as a natural aging process not related to fragility fractures. They generally did not feel concerned by OP and no important difference was observed between "aware" and "unaware" patients. Women expressed their fear of the disease, associated with aging and the end of life, while men considered it to be a women's disease only. Both sexes were aware of OP risk factors, but were suspicious towards treatments because of the associated side effects. CONCLUSION: Understanding people's representation of OP might help to provide patients with relevant information in order to optimize their preventive behavior and decrease the burden of the disease.

Formation of stromatolite lamina at the interface of oxygenic-anoxygenic photosynthesis.

In modern stromatolites, mineralization results from a complex interplay between microbial metabolisms, the organic matrix, and environmental parameters. Here, we combined biogeochemical, mineralogical, and microscopic analyses with measurements of metabolic activity to characterize the mineralization processes and products in an emergent (<18 months) hypersaline microbial mat. While the nucleation of Mg silicates is ubiquitous in the mat, the initial formation of a Ca-Mg carbonate lamina depends on (i) the creation of a high-pH interface combined with a major change in properties of the exopolymeric substances at the interface of the oxygenic and anoxygenic photoautotrophic layers and (ii) the synergy between two major players of sulfur cycle, purple sulfur bacteria, and sulfate-reducing bacteria. The repetition of this process over time combined with upward growth of the mat is a possible pathway leading to the formation of a stromatolite.

Patterns of metal distribution in hypersaline microbialites during early diagenesis: Implications for the fossil record.

The use of metals as biosignatures in the fossil stromatolite record requires understanding of the processes controlling the initial metal(loid) incorporation and diagenetic preservation in living microbialites. Here, we report the distribution of metals and the organic fraction within the lithifying microbialite of the hypersaline Big Pond Lake (Bahamas). Using synchrotron-based X-ray microfluorescence, confocal, and biphoton microscopies at different scales (cm-µm) in combination with traditional geochemical analyses, we show that the initial cation sorption at the surface of an active microbialite is governed by passive binding to the organic matrix, resulting in a homogeneous metal distribution. During early diagenesis, the metabolic activity in deeper microbialite layers slows down and the distribution of the metals becomes progressively heterogeneous, resulting from remobilization and concentration as metal(loid)-enriched sulfides, which are aligned with the lamination of the microbialite. In addition, we were able to identify globules containing significant Mn, Cu, Zn, and As enrichments potentially produced through microbial activity. The similarity of the metal(loid) distributions observed in the Big Pond microbialite to those observed in the Archean stromatolites of Tumbiana provides the foundation for a conceptual model of the evolution of the metal distribution through initial growth, early diagenesis, and fossilization of a microbialite, with a potential application to the fossil record.

Stromatolitic knobs in Storr's Lake (San Salvador, Bahamas): a model system for formation and alteration of laminae.

The initial lamination in young, metabolically active Scytonema knobs developing in Storr's Lake (Bahamas) results from the iterative succession of two different stages of microbial growth at the top of this microbialite. Stage 1 is dominated by vertically oriented cyanobacterial filaments and is characterized by a high porosity of the fabric. Stage 2 shows a higher microbial density with the filaments oriented horizontally and with higher carbonate content. The more developed, dense microbial community associated with Stage 2 of the Scytonema knobs rapidly degrades extracellular organic matter (EOM) and coupled to this, precipitates carbonate. The initial nucleation forms high-Mg calcite nanospheroids that progressively replace the EOM. No precipitation is observed within the thick sheath of the Scytonema filaments, possibly because of strong cross-linking of calcium and EOM (forming EOM-Ca-EOM complexes), which renders Ca unavailable for carbonate nucleation (inhibition process). Eventually, organominerals precipitate and form an initial lamina through physicochemical and microbial processes, including high rates of photosynthetic activity that lead to (13) C-enriched DIC available for initial nucleation. As this lamina moves downward by the iterative production of new laminae at the top of the microbialite, increased heterotrophic activity further alters the initial mineral product at depth. Although some rare relic preservation of 'Stage 1-Stage 2' laminae in subfossil knobs exists, the very fine primary lamination is considerably altered and almost completely lost when the knobs develop into larger and more complex morphologies due to the increased accommodation space and related physicochemical and/or biological alteration. Despite considerable differences in microstructure, the emerging ecological model of community succession leading to laminae formation described here for the Scytonema knobs can be applied to the formation of coarse-grained, open marine stromatolites. Therefore, both fine- and coarse-grained extant stromatolites can be used as model systems to understand the formation of microbialites in the fossil record.

Inside the alkalinity engine: the role of electron donors in the organomineralization potential of sulfate-reducing bacteria.

Mineral precipitation in microbial mats may have been the key to their preservation as fossil stromatolites, potentially documenting evidence of the earliest life on Earth. Two factors that contribute to carbonate mineral precipitation are the saturation index (SI) and the presence of nucleation sites. Both of these can be influenced by micro-organisms, which can either alter SI through their metabolisms, or produce and consume organic substances such as extracellular polymeric substances (EPS) that can affect nucleation. It is the balance of individual metabolisms within the mat community that determines the pH and the dissolved inorganic carbon concentration, thereby potentially increasing the alkalinity and consequently the SI. Sulfate-reducing bacteria (SRB) are an important component of this 'alkalinity engine.' The activity of SRB often peaks in layers where CaCO(3) precipitates, and mineral precipitation has been demonstrated in SRB cultures; however, the effect of their metabolism on the alkalinity engine and actual contribution to mineral precipitation is the subject of controversy. Here, we show through culture experiments, theoretical calculations, and geochemical modeling studies that the pH, alkalinity, and organomineralization potential will vary depending on the type of electron donor. Specifically, hydrogen and formate can increase the pH, but electron donors like lactate and ethanol, and to a lesser extent glycolate, decrease the pH. The implication of this for the lithification of mats is that the combination of processes supplying electron donors and the utilization of these compounds by SRB may be critical to promoting mineral precipitation.

The role of microbes in accretion, lamination and early lithification of modern marine stromatolites.

For three billion years, before the Cambrian diversification of life, laminated carbonate build-ups called stromatolites were widespread in shallow marine seas. These ancient structures are generally thought to be microbial in origin and potentially preserve evidence of the Earth's earliest biosphere. Despite their evolutionary significance, little is known about stromatolite formation, especially the relative roles of microbial and environmental factors in stromatolite accretion. Here we show that growth of modern marine stromatolites represents a dynamic balance between sedimentation and intermittent lithification of cyanobacterial mats. Periods of rapid sediment accretion, during which stromatolite surfaces are dominated by pioneer communities of gliding filamentous cyanobacteria, alternate with hiatal intervals. These discontinuities in sedimentation are characterized by development of surface films of exopolymer and subsequent heterotrophic bacterial decomposition, forming thin crusts of microcrystalline carbonate. During prolonged hiatal periods, climax communities develop, which include endolithic coccoid cyanobacteria. These coccoids modify the sediment, forming thicker lithified laminae. Preservation of lithified layers at depth creates millimetre-scale lamination. This simple model of modern marine stromatolite growth may be applicable to ancient stromatolites.