Global structural mapping of high-resolution Cassini images of Enceladus reveals a richly varied surface. Most notable are three main regions of deformation each containing multiple structural units. In addition to the well known "South Polar Terrain" (SPT), there are two other large regions of deformation that we term "Leading Hemisphere Terrain" (LHT) and "Trailing Hemisphere Terrain" (THT). Each of these three terrains includes a circumferential belt that encloses one or more other structurally deformed units. Areal extents range from about 80,000 km 2 (SPT) to 195,000 km 2 (LHT) or 160 to 250 km equivalent circular radius.Based on relative crater densities, the THT is inferred to be older than the LHT; the geologically active SPT is the youngest. The overall similarities in shape and dimension of the three tectonized terrains suggest similar formational processes, plausibly related to broad loading of a thin elastic shell. A viable scenario is that each tectonized terrain formed above a large-scale region of warm upwelling ice, with subsequent downwarping triggered by cooling and/or subsurface melting. However, differences in morphological detail suggest that the specific evolution of each tectonized terrain has been different.

Aims:  A general protocol was derived for optimizing the production of pure, high concentration Clostridium endospore suspensions. Methods and Results:  Two sporulation methods were developed that yielded high concentrations of notably pure Clostridium sporogenes, C. hungatei and C. GSA‐1 (Greenland ice core isolate) spore suspensions (10 ml of 109 spores ml−1 with >99% purity each). Each method was derived by evaluating combinations of three sporulation conditions, including freeze drying of inocula, heat shock treatment of cultures, and subsequent incubation at suboptimal temperatures that yielded the highest percentage of sporulation. Pure spore suspensions were characterized in terms of dipicolinic acid content, culturability, decimal reduction time (D) value for heat inactivation (100°C) and hydrophobicity. Conclusions:  While some Clostridium species produce a high percentage of spores with heat shock treatment and suboptimal temperature incubation, other species require the additional step of freeze drying the inocula to achieve a high percentage of sporulation. Significance and Impact of the Study:  Pure Clostridium spore suspensions are required for investigating species of medical and environmental importance. Defining the conditions for optimal spore production also provides insight into the underlying mechanisms of Clostridium sporulation.

No abstract

This article posits border abolition as a radical alternative to the Anthropocene. It convenes a group of eleven activists, organizers, scholars, practitioners, educators, and storytellers to discuss their work building cross-border solidarities along the US-Mexico border and in US immigration detention, Puerto Rico, Ghana, and the Bengal Delta. Participants provide critical analysis of the origins of environmental injustice and border violence and discuss how a confluence of ecological crisis, environmental racism, and border militarization since the 1980s disproportionately impacts BIPOC and queer/trans communities and exacerbates migrant precarity and displacement worldwide. Participants share ways they have built alternatives to border and ecological violence through migrant accompaniment, legal and policy advocacy, divestment activism, storytelling, education, and sustainability projects. The discussion is organized around three key themes: environmental injustice, racism, and borders; strategies adopted by organizers to build environmental and migrant justice; and visions of border abolition.