Timing of maternal exposure and fetal sex determine the effects of low-level chemical mixture exposure on the fetal neuroendocrine system in sheep

We have shown that continuous maternal exposure to the complex mixture of environmental chemicals (ECs) found in human biosolids (sewage sludge), disrupts mRNA expression of genes crucial for development and long-term regulation of hypothalamo-pituitary gonadal (HPG) function in sheep. This study investigated whether exposure to ECs only during preconceptional period or only during pregnancy perturbed key regulatory genes within the hypothalamus and pituitary gland and whether these effects were different from chronic (life-long) exposure to biosolid ECs. The findings demonstrate that the timing and duration of maternal EC exposure influences the subsequent effects on the fetal neuroendocrine system in a sex-specific manner. Maternal exposure prior to conception or during pregnancy only, altered the expression of key fetal neuroendocrine regulatory systems such as GnRH and kisspeptin to a greater extent than when maternal exposure was ‘life-long’. Furthermore, hypothalamic gene expression was affected to a greater extent in males than in females, and following EC exposure, male fetuses expressed more “female-like” mRNA levels for some key neuroendocrine genes. This is the first study to show that “real-life” maternal exposure to low levels of a complex cocktail of chemicals prior to conception can subsequently affect the developing fetal neuroendocrine system. These findings demonstrate that the developing neuroendocrine system is sensitive to EC mixtures in a sex-dimorphic manner likely to predispose to reproductive dysfunction in later life

Effect of Initial Disturbance on The Detonation Front Structure of a Narrow Duct

The effect of an initial disturbance on the detonation front structure in a narrow duct is studied by three-dimensional numerical simulation. The numerical method used includes a high resolution fifth-order weighted essentially non-oscillatory scheme for spatial discretization, coupled with a third order total variation diminishing Runge-Kutta time stepping method. Two types of disturbances are used for the initial perturbation. One is a random disturbance which is imposed on the whole area of the detonation front, and the other is a symmetrical disturbance imposed within a band along the diagonal direction on the front. The results show that the two types of disturbances lead to different processes. For the random disturbance, the detonation front evolves into a stable spinning detonation. For the symmetrical diagonal disturbance, the detonation front displays a diagonal pattern at an early stage, but this pattern is unstable. It breaks down after a short while and it finally evolves into a spinning detonation. The spinning detonation structure ultimately formed due to the two types of disturbances is the same. This means that spinning detonation is the most stable mode for the simulated narrow duct. Therefore, in a narrow duct, triggering a spinning detonation can be an effective way to produce a stable detonation as well as to speed up the deflagration to detonation transition process.Comment: 30 pages and 11 figure

The Regenerative Lens: A conceptual framework for regenerative social-ecological systems

Societies must transform their dynamics to support the flourishing of life. There is increasing interest in regeneration and regenerative practice as a solution, but also limited cohered understanding of what constitutes regenerative systems at social-ecological scales. In this perspective we present a conceptual, cross-disciplinary, and action-oriented regenerative systems framework, the Regenerative Lens, informed by a wide literature review. The framework emphasizes that regenerative systems maintain positive reinforcing cycles of wellbeing within and beyond themselves, especially between humans and wider nature, such that “life begets life.” We identify five key qualities needed in systems to encourage such dynamics: an ecological worldview embodied in human action; mutualism; high diversity; agency for humans and non-humans to act regeneratively; and continuous reflexivity. We apply the Lens to an envisioned future food system to illustrate its utility as a reflexive tool and for stretching ambition. We hope that the conceptual clarity provided here will aid the necessary acceleration of learning and action toward regenerative systems