We present atmospheric radiocarbon concentrations in CO2 integrated samples taken between January 2019 and December 2021 in the Mexico City Metropolitan Area (MCMA) and explain the variations in terms of changes in emission sources associated with the COVID-19 lockdown restrictions imposed from March 2020. Δ14C values for samples collected during 2019 range between –44.15‰ and –13.17‰, with lower values during months with higher fossil fuels consumption and air stagnation, whereas higher values were found for periods with high number of fires around MCMA or wet months with higher contribution of heterotrophic respiration. For samples collected during 2020, Δ14C values range between –17.7‰ and 2.25‰, with an increasing trend immediately after the initial lockdown and higher values obtained for samples collected during lockdown phases 2 and 3 and the period of extremely high epidemic risk. This agrees with the 38% and 52% decrease in gasoline and diesel sales. Once essential activities gradually opened from July 2020, Δ14C follow a decreasing trend as vehicle traffic started to increase again. Δ14C values for samples collected during 2021 range from –32.89‰ to –10.27‰, with the higher value obtained during a period of extremely high epidemic risk with a 30% reduction in gasoline and diesel consumption. Despite the complexity of emission sources in MCMA, from Δ14C variations it was possible to identify changes in fossil CO2 emissions resulting from the significant reduction in vehicle traffic due to the COVID-19 lockdown and the restrictions imposed to control transmission of the disease.

Let $\mathfrak{A}$ be a finite abelian group. In this paper, we classify harmonic $\mathfrak{A}$-covers of a tropical curve $\Gamma$ (which allow dilation along edges and at vertices) in terms of the cohomology group of a suitably defined sheaf on $\Gamma$. We give a realisability criterion for harmonic $\mathfrak{A}$-covers by patching local monodromy data in an extended homology group on $\Gamma$. As an explicit example, we work out the case $\mathfrak{A}=\mathbb{Z}/p\mathbb{Z}$ and explain how realisability for such covers is related to the nowhere-zero flow problem from graph theory.

We begin by proving that any Presburger-definable image of one or more sets of powers has zero natural density. Then, by adapting the proof of a dichotomy result on o-minimal structures by Friedman and Miller, we produce a similar dichotomy for expansions of Presburger arithmetic on the integers. Combining these two results, we obtain that the expansion of the ordered group of integers by any number of sets of powers does not define multiplication.

Negative maternal mental health during pregnancy increases the risk of psychiatric problems in children, but research on the potential benefits of positive maternal mental health during pregnancy is scarce. We investigated associations between positive maternal mental health composite score, based on reports of maternal positive affect, curiosity, and social support during pregnancy, and children’s psychiatric problems (Child Behavior Checklist) at ages 1.9−5.9 and 7.1−12.1 years among 2636 mother–child dyads of the Prediction and Prevention of Preeclampsia and Intrauterine Growth Restriction study. For each standard deviation higher positive maternal mental health score during pregnancy, total psychiatric problems were 1.37 (95% confidence interval (CI) −1.79,−0.95) t-scores lower in early childhood and 1.75 (95% CI −2.24,−1.26) t-scores lower in late childhood. These associations were independent of covariates and of negative maternal mental health. Total psychiatric problems remained stably lower from early childhood to late childhood in children of mothers with higher positive mental health during pregnancy, whereas they increased in children of mothers with lower positive mental health. Positive maternal mental health in child’s late childhood partially mediated the effects of positive maternal mental health during pregnancy on children’s psychiatric problems. Supporting positive maternal mental health may benefit mothers and children.

In the aftermath of the 2022 Italian legislative elections, but also during the entire electoral campaign, several claims were made that much of the electoral support for the Five Star Movement had been triggered by the ‘Reddito di cittadinanza’ – the welfare policy introduced in 2019 by the yellow–green government. This research note first distinguishes between distributive politics and policy voting, and then explores the empirical relationship between the geographical provision at the municipal level of the citizenship income and the vote for the party led by Giuseppe Conte. While traditional multivariate analyses fail to reveal any spurious relationship, matching techniques help highlight the absence of any causal relationship between the two variables.

A complete embedding is a symplectic embedding $\iota :Y\to M$ of a geometrically bounded symplectic manifold $Y$ into another geometrically bounded symplectic manifold $M$ of the same dimension. When $Y$ satisfies an additional finiteness hypothesis, we prove that the truncated relative symplectic cohomology of a compact subset $K$ inside $Y$ is naturally isomorphic to that of its image $\iota (K)$ inside $M$. Under the assumption that the torsion exponents of $K$ are bounded, we deduce the same result for relative symplectic cohomology. We introduce a technique for constructing complete embeddings using what we refer to as integrable anti-surgery. We apply these to study symplectic topology and mirror symmetry of symplectic cluster manifolds and other examples of symplectic manifolds with singular Lagrangian torus fibrations satisfying certain completeness conditions.