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Silicon isotopic signatures of granitoids support increased weathering of subaerial land 3.7 billion years ago
No full textThe weathering and erosion of emerged land profoundly influences the Earth system, including the composition of the atmosphere and the type of nutrients delivered to the oceans. The emergence of land allowed for the formation of lakes and continental shelves, important habitats for the origin and evolution of life. Recent studies indicate a difference in silicon isotopes between Archean granitoids and their modern counterparts, which is explained by the incorporation of seawater-derived silica in the melting sources of the former. We show that this signature changed rapidly around 3.6 billion years ago, and that this shift is likely linked to an increase in the dissolved silicon flux from terrestrial weathering. Modeling suggests that the amount of oceanic silicon derived from terrigenous sources increased from near zero to around 32 ± 15% between 3.8 and 3.6 billion years ago. This indicates that, from this point onward, continental weathering feedbacks were established, and mass flux from land became an important source in the chemical budget of seawater, changes that likely exerted positive effects on the evolution of life
ZnH<sub>2</sub> as a precursor to catalytically active Ru–ZnH heterometallic complexes
No full textReaction of [Ru(IPr)2(CO)H][BArF4] (1; IPr = 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene; BArF4 = B{3,5(CF3)2C6H3}4) with an excess of ZnH2 in THF gives the structurally characterized neutral Ru(ZnH) complex [Ru(IPr)2(CO)(ZnH)H3] (6) and Ru(ZnH)2 salt [Ru(IPr)2(CO)(ZnH)2H3][BArF4] (5). Crystallographic and computational analyses show the presence of both bridging Ru–H–Zn hydrides and terminal Ru-hydrides in the two products. Calculations also identify a low-energy H/ZnH exchange pathway that rationalizes the experimentally observed (EXSY) fluxionality of the hydrides in 5. At room temperature, this compound undergoes stoichiometric exchange with ZnMe2 to give [Ru(IPr)2(CO)(ZnMe)2H3][BArF4] (7), and also proves to be catalytically active for the hydrogenation of 1-hexene and 5-hexene-2-one
Fertility differences across immigrant generations in the United Kingdom
No full textBackground: Previous studies have investigated immigrant fertility in various European countries, but only a few have compared the fertility rates of women who migrated as children (1.5 Generation), women born in the host society to foreign-born parents (2 Generation), and women born in the host society with one foreign-born and one native-born parent (2.5 Generation).Objective: This study examines the first-, second-, and third-birth rates of three migrant generation groups in the United Kingdom – 1.5G, 2G, and 2.5G. The study investigates the role of sociocultural factors in shaping their fertility behaviour.Methods: Event history analysis is applied to longitudinal individual-level data (N = 24,228) from the UK Household Longitudinal Study (2009–2021).Results: Pakistani and Bangladeshi women who arrived in the United Kingdom as children exhibit elevated fertility at all birth orders, partly consistent with socialization theory. No clear convergence emerges among women born in the United Kingdom with one immigrant parent and one UK-born parent (2.5G) across all groups from different migrant-origin backgrounds. Instead, certain 2.5G groups show distinct fertility patterns. The influence of sociocultural factors on fertility varies by birth order and migrant generation, highlighting the need for a detailed approach that considers both cultural and socioeconomic dimensions.Contribution: This study is one of the first to differentiate the fertility behaviours of 1.5G, 2G, and 2.5G women in the United Kingdom. It reveals important variations in childbearing behaviour, which have implications for understanding intergenerational differences and the influence of sociocultural factors on migrant fertility
Inclusion of patient-centered, non-microbiological endpoints and biomarkers in tuberculosis drug trials
No full textTuberculosis drug trials are primarily designed to identify antibiotic regimens with the strongest potency to kill Mycobacterium tuberculosis. However, microbiologic cure is not synonymous with improved health and recovery. Beyond antimicrobial efficacy, parameters such as morbidity and mortality related to lung function, cardiovascular health, and cancer should be prioritized. This narrative review emphasizes the critical need to emphasize clinical outcomes as much, if not more, than microbiological endpoints. We examine the underlying pathophysiological mechanisms and determinants of non-microbiological outcomes in tuberculosis, providing a synthesis of current knowledge. While there is growing evidence for some biomarkers to risk stratify TB patients for risk of all-cause mortality, relapse, or lung damage, no evidence was found on TB-associated cancer or cardiovascular disease. In addition to monitoring microbiologic outcomes, clinical trials and treatment cohorts need to capture patient-centered health dimensions more broadly. Finally, we highlight key research gaps and opportunities to evaluate non-microbiological biomarkers, aiming to improve patient monitoring and enable stratified approaches to tuberculosis management
Biological nitrogen cycling within terrestrial hot springs:a Mars analogue system
No full textNoachian-age (4.1–3.7Ga) hot spring deposits have been identified on Mars, in addition to fixed nitrogen compounds within Martian surface materials, yet the planet’s nitrogen cycle remains enigmatic and implicates the plausibility of a Martian biosphere. On Earth’s surface, nitrogen is cycled almost exclusively by biological processes which create distinctive isotopic fractionations. We combine geochemical and metagenomic analysis to investigate biological nitrogen cycling within four Mars analogue geothermal systems in Iceland ranging in temperature from 37.8 to 57.1 °C, and propose the geochemical parameters that control biological nitrogen fixation as the primary source of nitrogen into the microbial communities present. We find complete nitrogen fixation and ammonium assimilation gene clusters at all sites, which are also the most abundant nitrogen-cycling genes present. Isotopic fractionations (Δ15 N) of ∼6 ‰ between locally dissolved N2 gas and biomass are most parsimoniously explained by organisms relying on Mo-independent nitrogenases for fixation of dinitrogen (N2). This hypothesis is supported by the presence of genes encoding these enzymes in three out of four sites included in this study, in addition to the more commonly used MoFe nitrogenase. Finally, we find that molybdenum availability is low in the Icelandic hot springs investigated, and potentially therefore in Martian hot springs. This may inhibit conventional Mo-dependent nitrogen fixation in such settings and highlights the influence of wider geological conditions on local biochemistry
Disease landscapes beyond the “Spanish flu” pandemic:temporal patterns, re-centered narratives (1889-1970s)
No full text“C'est par l'accent que l'histoire met sur le changement et sur les différences ou écarts affectant les changements qu'elle se distinguish des autres social sciences et principalement de la sociologie”, argued Paul Ricoeur in his classic study La mémoire, l'histoire, l'oubli . We could add to this that change—the passage from one collective situation or circumstance to another—would constitute not only the most specific object of history, but also a major impetus for historians to do research and, in general, for the development of historical science. As Reinhart Koselleck pointed out in Future Pasts. On the semantics of historical time , changes produce a “penetration [rupture] of the horizon of expectations” (taking these as “the future made present”) that inevitably leads to a “restructuring of the space of experiences” (taking these as “the past made present”). Each generation of historians would, thus, feel compelled from the changes occurring in its present to rewrite history in order to re-imagine collective destiny (and vice versa)
Digital worker inquiry and the critical potential of participatory worker data science for on‐demand platform workers
No full textThe knowledge that workers have of the systems they work under is an outcome of strategic choices by platforms and by workers themselves. Based on three initiatives undertaken by food distribution workers in Scotland, this article explores the obstacles that platform workers face when conducting inquiries into their systems of control, and investigates the potential for workers to overcome these obstacles through collaborative research projects. By drawing analogies from the history of workers' inquiries into changing labour processes, the article evaluates these three initiatives in light of previous efforts by workers to monitor complex and concealed management structures. It offers a new concept of ‘worker data science’ to describe the techniques, skills and methods that workers require to arrive at answers to questions that emerge through their inquiries, and concludes that such purposive science has the potential to equip workers to support one another and to resist and challenge some of the commands and calculations that emerge from platforms' hidden algorithmic systems
Superpower graphs of finite groups
No full textFor a finite group G, the superpower graph S(G) of G is an undirected simple graph with vertex set G and two vertices are adjacent in S(G) if and only if the order of one divides the order of the other in G. The aim of this paper is to provide tight bounds for the vertex connectivity, discuss Hamiltonian-like properties of superpower graph of finite non-abelian groups having an element of exponent order.We also give some general results about superpower graphs and their relation to other graphs such as the Gruenberg–Kegel graph
