Detailed Analysis of the Intra-Ejecta Dark Plains of Caloris Basin, Mercury

The Caloris basin on Mercury is floored by light-toned plains and surrounded by an annulus of dark-toned material interpreted to be ejecta blocks and smooth, dark, ridged plains. Strangely, preliminary crater counts indicate that these intra-ejecta dark plains are younger than the light-toned plains within the Caloris basin. This would imply a second, younger plains emplacement event, possibly involving lower albedo material volcanics, which resurfaced the original ejecta deposit. On the other hand, the dark plains may be pre-Caloris light plains covered by a thin layer of dark ejecta. Another alternative to the hypothesis of young, dark volcanism is the possibility that previous crater counts have not thoroughly distinguished between superposed craters (fresh) and partly-buried craters (old) and therefore have not accurately determined the ages of the Caloris units. This abstract outlines the tasks associated with a new mapping project of the Caloris basin, intended to improve our knowledge of the geology and geologic history of the basin, and thus facilitate an understanding of the thermal evolution of this region of Mercury

Sourdough bread enriched with soluble fibres: development, characterisation and nutritional aspects of a functional food product

The application of sourdough in breadmaking has multiple technological and nutritional benefits. However, the use of soluble fibres in sourdough technology is a currently understudied area. Given that the UK fibre intakes (at average of 14g/d for adults) fall short of government recommendations, the aim of this PhD was to develop soluble fibre-enriched sourdough bread with a low glycaemic index (GI). The PhD comprised three key phases: 1) product development, 2) physico-chemical and sensory characterisation, and 3) GI analysis of the fibre-enriched sourdough breads. After undertaking a product development trial, the physico-chemical properties of five sourdoughs and the resultant breads were assessed using pH measurements, Chen-Hoseney dough stickiness rig and rapid viscosity analysis (RVA). Bread volume, texture analysis, C-Cell image analysis, fibre and resistant starch determination were also conducted. Consumer acceptability of the developed breads was assessed using an untrained sensory panel (n = 100). The content of lactic acid and ethanol was studied using high-performance liquid chromatography (HPLC) analysis. The glycaemic and satietogenic properties of sourdough bread enriched with soluble fibre (XG/GA/Pec), control sourdough bread and white wheat bread (WWB) were tested in a cross-over study using 11 healthy participants (mean age 35 ± 10 years, BMI 23.7 ± 2.86 kg/m2), a standard seven-point protocol and Satiety Labelled Intensity Magnitude (SLIM) scale. The results of this study showed a negative correlation between the value of pH and the dough stickiness for control sourdough bread (R2 = 0.618) and for control sourdough bread with added wheat bran (R2 = 0.532). The RVA results showed that the addition of 10% of soluble significantly influenced the gelatinisation and properties of starch in flour pastes. The research showed that the addition of 10% soluble and insoluble fibre (wheat bran) to sourdough bread significantly (p 0.05). The values of GI obtained in the intervention study were 66 for control sourdough bread (p = 0.03) and 59 for XG/GA/Pec (p = 0.006) when compared to glucose reference food. The subjects reported greater satiety after consumption of bread with iii XG/GA/Pec than after consuming white wheat bread (p = 0.036). These results show that sourdough bread enriched with soluble fibres played a role in reducing glycaemia and in increasing the perception of satiety following ingestion. This PhD makes contribution to knowledge by applying high amounts of soluble fibres, which are routinely used in much lower concentrations in food industry. The research described within this thesis provides a formula and processing conditions for the production of a functional food product. This study adds to the existing knowledge of food science and human nutrition. Within this thesis it is demonstrated that sourdough and soluble fibre may act simultaneously on the gastrointestinal tract and jointly exert effects on postprandial blood glucose concentration and satiety. By demonstrating prolonged satiety of bread characterised by lower GI, this PhD makes a contribution to the debate on the satietogenic properties of dietary carbohydrates. Further research is now needed to explore the hormonal and metabolic effects after ingestion of soluble fibre-enriched sourdough bread. Future studies of the fermentability of these breads by colonic microflora could also provide insight into their prebiotic properties

Sustainable Management of Water Resources

The Dawn spacecraft arrived at dwarf planet Ceres in spring 2015 and imaged its surface from four successively lower polar orbits at ground sampling dimensions between ∼1.3 km/px and ∼35 m/px. To understand the geological history of Ceres a mapping campaign was initiated to produce a set of 15 quadrangle-based geological maps using the highest-resolution Framing Camera imagery. Here we present the geological map of the Ac-10 Rongo Quadrangle, which is located at the equator encompassing the region from 22°N to 22°S and 288° to 360°E. The total relief within the quadrangle is 11.1 km with altitudes ranging from about −7.3 km to +3.8 km. We identified nine geological units based on surface morphology and surface textural characteristics. The dominant and most widespread unit is the cratered terrain (crt) representing ancient reworked crustal material. Its consistent formation age across the quadrangle is 1.8 Ga. Two edifices (unit th), Ahuna Mons and an unnamed tholus within Begbalel Crater, are interpreted to be of (cryo)volcanic origin. The southwest portion of the quadrangle is dominated by ejecta material (Ye) emplaced during the formation of the 260-km diameter Yalode impact basin at about 580 Ma. Rayed crater ejecta material (cr) is dominant in the eastern part of the quadrangle but also occurs in isolated patches up to a distance of 455 km from the 34 km diameter source crater Haulani. The remaining five geological units also represent impact crater materials: degraded rim (crdeg), bright crater (cb), hummocky floor (cfh), talus (ta), and crater (c) materials. Widespread Yalode and Haulani ejecta materials can potentially be utilised as stratigraphic markers. Therefore, it is essential to consistently map their full areal extent and to date their formations using impact crater statistics

NASA Planetary Mission Concept Study: Assessing: Dwarf Planet Ceres' past and Present Habitability Potential

The Dawn mission revolutionized our understanding of Ceres during the same decade that has also witnessed the rise of ocean worlds as a research and exploration focus. We will report progress on the Planetary Mission Concept Study (PMCS) on the future exploration of Ceres under the New Frontiers or Flagship program that was selected for NASA funding in October 2019. At the time this writing, the study was just kicked off, hence this abstract reports the study plan as presented in the proposal

The varied sources of faculae-forming brines in Ceres’ Occator crater emplaced via hydrothermal brine effusion

Before acquiring highest-resolution data of Ceres, questions remained about the emplacement mechanism and source of Occator crater's bright faculae. Here we report that brine effusion emplaced the faculae in a brine-limited, impact-induced hydrothermal system. Impact-derived fracturing enabled brines to reach the surface. The central faculae, Cerealia and Pasola Facula, postdate the central pit, and were primarily sourced from an impact-induced melt chamber, with some contribution from a deeper, pre-existing brine reservoir. Vinalia Faculae, in the crater floor, were sourced from the laterally extensive deep reservoir only. Vinalia Faculae are comparatively thinner and display greater ballistic emplacement than the central faculae because the deep reservoir brines took a longer path to the surface and contained more gas than the shallower impact-induced melt chamber brines. Impact-derived fractures providing conduits, and mixing of impact-induced melt with deeper endogenic brines, could also allow oceanic material to reach the surfaces of other large icy bodies. The second extended phase of the Dawn mission provided high resolution observations of Occator crater of the dwarf planet Ceres. Here, the authors show that the central faculae were sourced in an impact-induced melt chamber, with a contribution from the deep brine reservoir, while the Vinalia Faculae were sourced by the deep brine reservoir alone

Mass Movement on Vesta at Steep Scarps and Crater Rims

The Quadrangles Av-11 and Av-12 on Vesta are located at the northern rim of the giant Rheasilvia south polar impact basin. The primary geologic units in Av-11 and Av-12 include material from the Rheasilvia impact basin formation, smooth material and different types of impact crater structures (such as bimodal craters, dark and bright crater ray material and dark ejecta material). Av-11 and Av-12 exhibit almost the full range of mass wasting features observed on Vesta, such as slump blocks, spur-and-gully morphologies and landslides within craters. Processes of collapse, slope instability and seismically triggered events force material to slump down crater walls or scarps and produce landslides or rotational slump blocks. The spur-and-gully morphology that is known to form on Mars is also observed on Vesta; however, on Vesta this morphology formed under dry conditions

Crack-Like Processes Governing the Onset of Frictional Slip

We perform real-time measurements of the net contact area between two blocks of like material at the onset of frictional slip. We show that the process of interface detachment, which immediately precedes the inception of frictional sliding, is governed by three different types of detachment fronts. These crack-like detachment fronts differ by both their propagation velocities and by the amount of net contact surface reduction caused by their passage. The most rapid fronts propagate at intersonic velocities but generate a negligible reduction in contact area across the interface. Sub-Rayleigh fronts are crack-like modes which propagate at velocities up to the Rayleigh wave speed, VR, and give rise to an approximate 10% reduction in net contact area. The most efficient contact area reduction (~20%) is precipitated by the passage of slow detachment fronts. These fronts propagate at anomalously slow velocities, which are over an order of magnitude lower than VR yet orders of magnitude higher than other characteristic velocity scales such as either slip or loading velocities. Slow fronts are generated, in conjunction with intersonic fronts, by the sudden arrest of sub-Rayleigh fronts. No overall sliding of the interface occurs until either of the slower two fronts traverses the entire interface, and motion at the leading edge of the interface is initiated. Slip at the trailing edge of the interface accompanies the motion of both the slow and sub-Rayleigh fronts. We might expect these modes to be important in both fault nucleation and earthquake dynamics.Comment: 19 page, 5 figures, to appear in International Journal of Fractur