A divergent heritage for complex organics in Isheyevo lithic clasts

Primitive meteorites are samples of asteroidal bodies that contain a high proportion of chemically complex organic matter (COM) including prebiotic molecules such as amino acids, which are thought to have been delivered to Earth via impacts during the early history of the Solar System. Thus, understanding the origin of COM, including their formation pathway(s) and environment(s), is critical to elucidate the origin of life on Earth as well as assessing the potential habitability of exoplanetary systems. The Isheyevo CH/CBb carbonaceous chondrite contains chondritic lithic clasts with variable enrichments in 15N believed to be of outer Solar System origin. Using transmission electron microscopy (TEM-EELS) and in situ isotope analyses (SIMS and NanoSIMS), we report on the structure of the organic matter as well as the bulk H and N isotope composition of Isheyevo lithic clasts. These data are complemented by electron microprobe analyses of the clast mineral chemistry and bulk Mg and Cr isotopes obtained by inductively coupled plasma and thermal ionization mass spectrometry, respectively (MC-ICPMS and TIMS). Weakly hydrated (A) clasts largely consist of Mg-rich anhydrous silicates with local hydrated veins composed of phyllosilicates, magnetite and globular and diffuse organic matter. Extensively hydrated clasts (H) are thoroughly hydrated and contain Fe-sulfides, sometimes clustered with organic matter, as well as magnetite and carbonates embedded in a phyllosilicate matrix. The A-clasts are characterized by a more 15N-rich bulk nitrogen isotope composition (δ15N = 200–650‰) relative to H-clasts (δ15N = 50–180‰) and contain extremely 15N-rich domains with δ15N 15N-rich domains show that the lithic clast diffuse organic matter is typically more 15N-rich than globular organic matter. The correlated δ15N values and C/N ratios of nanoglobules require the existence of multiple organic components, in agreement with the H isotope data. The combined H and N isotope data suggest that the organic precursors of the lithic clasts are defined by an extremely 15N-poor (similar to solar) and D-rich component for H-clasts, and a moderately 15N-rich and D-rich component for A-clasts. In contrast, the composition of the putative fluids is inferred to include D-poor but moderately to extremely 15N-rich H- and N-bearing components. The variable 15N enrichments in H- and A-clasts are associated with structural differences in the N bonding environments of their diffuse organic matter, which are dominated by amine groups in H-clasts and nitrile functional groups in A-clasts. We suggest that the isotopically divergent organic precursors in Isheyevo clasts may be similar to organic moieties in carbonaceous chondrites (CI, CM, CR) and thermally recalcitrant organic compounds in ordinary chondrites, respectively. The altering fluids, which are inferred to cause the 15N enrichments observed in the clasts, may be the result of accretion of variable abundances of NH3 and HCN ices. Finally, using bulk Mg and Cr isotope composition of clasts, we speculate on the accretion regions of the various primitive chondrites and components and the origin of the Solar System’s N and H isotope variability

The Formation and Evolution of Virgo Cluster Galaxies - II. Stellar Populations

We use a combination of deep optical and near-infrared light profiles for a morphologically diverse sample of Virgo cluster galaxies to study the radially-resolved stellar populations of cluster galaxies over a wide range of galaxy structure. We find that, in the median, the age gradients of Virgo galaxies are either flat (lenticulars and Sa-Sb spirals) or positive (ellipticals, Sbc+Sc spirals, gas-rich dwarfs, and irregulars), while all galaxy types have a negative median metallicity gradient. Comparison of the galaxy stellar population diagnostics (age, metallicity, and gradients thereof) against structural and environmental parameters also reveals that the ages of gas-rich systems depend mainly on their atomic gas deficiencies. Conversely, the metallicities of Virgo gas-poor galaxies depend on their concentrations, luminosities, and surface brightnesses. The stellar population gradients of all Virgo galaxies exhibit no dependence on either their structure or environment. We interpret these stellar population data for Virgo galaxies in the context of popular formation and evolution scenarios, and suggest that gas-poor giants grew hierarchically (through dissipative starbursts), gas-poor dwarfs have descended from at least two different production channels (e.g., environmental transformation and merging), while spirals formed inside-out, but with star formation in the outskirts of a significant fraction of the population having been quenched due to ram pressure stripping. (Abridged)Comment: 54 pages, 16 figures, 3 tables, re-submitted to MNRAS (edited to reflect the referee's suggestions

Global economic burden of unmet surgical need for appendicitis

Background: There is a substantial gap in provision of adequate surgical care in many low-and middle-income countries. This study aimed to identify the economic burden of unmet surgical need for the common condition of appendicitis. Methods: Data on the incidence of appendicitis from 170 countries and two different approaches were used to estimate numbers of patients who do not receive surgery: as a fixed proportion of the total unmet surgical need per country (approach 1); and based on country income status (approach 2). Indirect costs with current levels of access and local quality, and those if quality were at the standards of high-income countries, were estimated. A human capital approach was applied, focusing on the economic burden resulting from premature death and absenteeism. Results: Excess mortality was 4185 per 100 000 cases of appendicitis using approach 1 and 3448 per 100 000 using approach 2. The economic burden of continuing current levels of access and local quality was US $92 492 million using approach 1 and$73 141 million using approach 2. The economic burden of not providing surgical care to the standards of high-income countries was $95 004 million using approach 1 and$75 666 million using approach 2. The largest share of these costs resulted from premature death (97.7 per cent) and lack of access (97.0 per cent) in contrast to lack of quality. Conclusion: For a comparatively non-complex emergency condition such as appendicitis, increasing access to care should be prioritized. Although improving quality of care should not be neglected, increasing provision of care at current standards could reduce societal costs substantially

Cohort Profile: Burden of Obstructive Lung Disease (BOLD) study

The Burden of Obstructive Lung Disease (BOLD) study was established to assess the prevalence of chronic airflow obstruction, a key characteristic of chronic obstructive pulmonary disease, and its risk factors in adults (≥40 years) from general populations across the world. The baseline study was conducted between 2003 and 2016, in 41 sites across Africa, Asia, Europe, North America, the Caribbean and Oceania, and collected high-quality pre- and post-bronchodilator spirometry from 28 828 participants. The follow-up study was conducted between 2019 and 2021, in 18 sites across Africa, Asia, Europe and the Caribbean. At baseline, there were in these sites 12 502 participants with high-quality spirometry. A total of 6452 were followed up, with 5936 completing the study core questionnaire. Of these, 4044 also provided high-quality pre- and post-bronchodilator spirometry. On both occasions, the core questionnaire covered information on respiratory symptoms, doctor diagnoses, health care use, medication use and ealth status, as well as potential risk factors. Information on occupation, environmental exposures and diet was also collected