Present-day Mars' seismicity predicted from 3-D thermal evolution models of interior dynamics

©2018. American Geophysical UnionThe Interior Exploration using Seismic Investigations, Geodesy and Heat Transport mission, to be launched in 2018, will perform a comprehensive geophysical investigation of Mars in situ. The Seismic Experiment for Interior Structure package aims to detect global and regional seismic events and in turn offer constraints on core size, crustal thickness, and core, mantle, and crustal composition. In this study, we estimate the present‐day amount and distribution of seismicity using 3‐D numerical thermal evolution models of Mars, taking into account contributions from convective stresses as well as from stresses associated with cooling and planetary contraction. Defining the seismogenic lithosphere by an isotherm and assuming two end‐member cases of 573 K and the 1073 K, we determine the seismogenic lithosphere thickness. Assuming a seismic efficiency between 0.025 and 1, this thickness is used to estimate the total annual seismic moment budget, and our models show values between 5.7 × 1016 and 3.9 × 1019 Nm

Rock size‐frequency distributions on Mars and implications for Mars Exploration Rover landing safety and operations

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95449/1/jgre1686.pd

Effect of separate pod and root zone temperatures on yield and seed composition of three Spanish cultivars of groundnut (Arachis hypogaea L)

The effect of separate pod and root temperature regimes (all four combinations of 28/22 and 40/34 °C day/night temperature), imposed from the time of peg penetration until harvest, on yield and seed composition of three Spanish genotypes of groundnut (Arachis hypogaea L) was investigated. A decrease in pod temperature from 40/34 to 28/22 °C increased yield and oil, starch and protein mass per plant irrespective of root temperature. Additionally, a reduction in pod temperature decreased protein concentration and increased the sum of oil and starch concentration at a root temperature of 28/22 °C, whereas at a root temperature of 40/34 °C a decrease in pod temperature increased protein concentration. Root temperature reduction diminished oil concentration of genotypes AH 6179 and TMV 2 at a pod temperature of 40/34 °C. A decline in pod temperature affected fatty acid composition through a decrease in palmitic acid irrespective of root temperature and an increase in linoleic acid at a root temperature of 28/22 °C. A root temperature effect on fatty acid composition was not detected. It is concluded that field management practices and choice of genotype can influence groundnut yield and seed composition through effects on pod and root temperatur

The Degradational History of Endeavour Crater, Mars

Endeavour crater (2.28 deg S, 354.77 deg E) is a Noachian-aged 22 km-diameter impact structure of complex morphology in Meridiani Planum. The degradation state of the crater has been studied using Mars Reconnaissance Orbiter and Opportunity rover data. Exposed rim segments rise approximately 10 m to approximately 100 m above the level of the embaying Burns Formation and the crater is 200-500 m deep with the southern interior wall exposing over approximately 300 m relief. Both pre-impact rocks (Matijevic Formation) and Endeavour impact ejecta (Shoemaker Formation) are present at Cape York, but only the Shoemaker crops out (up to approximately 140 m) along the rim segment from Murray Ridge to Cape Tribulation. Study of pristine complex craters Bopolu and Tooting, and morphometry of other martian complex craters, enables us to approximate Endeavour's pristine form. The original rim likely averaged 410 m (+/-)200 m in elevation and a 250-275 m section of ejecta ((+/-)50-60 m) would have composed a significant fraction of the rim height. The original crater depth was likely between 1.5 km and 2.2 km. Comparison between the predicted original and current form of Endeavour suggests approximately 100-200 m rim lowering that removed most ejecta in some locales (e.g., Cape York) while thick sections remain elsewhere (e.g., Cape Tribulation). Almost complete removal of ejecta at Cape York and minimal observable offset across fractures indicates current differences in rim relief are not solely due to original rim relief. Rim segments are embayed by approximately 100-200 m thickness of plains rocks outside the crater, but thicker deposits lie inside the crater. Ventifact textures confirm ongoing eolian erosion with the overall extent difficult to estimate. Analogy with degraded Noachian-aged craters south of Endeavour, however, suggests fluvial erosion dominated rim degradation in the Noachian and was likely followed by approximately 10s of meters modification by alternate processes. Such degradation is consistent with 1) the interpretation of a pediment on the rim flanks of Endeavour, 2) the formation of features such as Marathon Valley, 3) the nearly complete removal of ejecta at Cape York, 4) preservation of a thicker section of ejecta at Cape Tribulation and perhaps, 5) the origin of some gaps in the rim around the crater. A paucity of debris shed from the rim indicates most degradation occurred prior to embayment by the plains rocks

Degradation of Endeavour Crater, Mars

The Opportunity rover has traversed portions of two western rim segments of Endeavour, a 22 km-diameter crater in Meridiani Planum, for the past three years. The resultant data enables the evaluation of the geologic expression and degradation state of the crater. Endeavour is Noa-chian-aged, complex in morphology, and originally may have appeared broadly similar to the more pristine 20.5 km-diameter Santa Fe complex crater in Lunae Palus (19.5degN, 312.0degE). By contrast, Endeavour is considerably subdued and largely buried by younger sulfate-rich plains. Exposed rim segments dubbed Cape York (CY) and Solander Point/Murray Ridge/Pillinger Point (MR) located approximately1500 m to the south reveal breccias interpreted as remnants of the ejecta deposit, dubbed the Shoemaker Formation. At CY, the Shoemaker Formation overlies the pre-impact rocks, dubbed the Matijevic Formation

Geology of McLaughlin Crater, Mars: A Unique Lacustrine Setting with Implications for Astrobiology

McLaughlin crater is a 92-kmdiameter Martian impact crater that contained an ancient carbonate- and clay mineral-bearing lake in the Late Noachian. Detailed analysis of the geology within this crater reveals a complex history with important implications for astrobiology [1]. The basin contains evidence for, among other deposits, hydrothermally altered rocks, delta deposits, deep water (>400 m) sediments, and potentially turbidites. The geology of this basin stands in stark contrast to that of some ancient basins that contain evidence for transient aqueous processes and airfall sediments (e.g. Gale Crater [2-3])

Opportunity In Situ Geologic Context of Aqueous Alteration Along Offsets in the Rim of Endeavour Crater

Mars Exploration Rover Opportunity traversed 7.9 km and 27 degrees of arc along the rim of the 22 km-diameter Noachian "Endeavour" impact crater since its arrival 1200 sols ago. Areas of aqueous and low-grade thermal alteration, and changes in structure, attitude, and macroscopic texture of outcrops are notable across several discontinuities between segments of the crater rim. The discontinuities and other post-impact joints and fractures coincide with sites of apparent deep fluid circulation processes responsible for thermal and chemical alteration of local outcrops

Sleep diplomacy alone will widen sleep disparities - Authors' reply.

Timothy Daly argues that preexisting sleep disparities according to socioeconomic status will make behavioural approaches and lifestyle advice widen sleep disparities. Although we fully agree that strong public policy measures must be implemented to reduce socioeconomic status inequalities in brain health,1 and in particular those that might impact sleep problems, there is good evidence reporting the success of behavioural interventions to improve sleep conditions in different populations.2 Specific interventions have been proposed in lowsocioeconomic status populations, which should also be included in our sleep diplomacy3 category.Fil: Golombek, Diego Andres. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de San Andrés; ArgentinaFil: Booi, Laura. Trinity College; Irlanda. Leeds Beckett University; Reino UnidoFil: Campbell, Dominic. Trinity College; IrlandaFil: Dawson, Walter D.. Trinity College; Irlanda. University of California; Estados Unidos. Global Brain Health Institute; Estados Unidos. Oregon Health and Science University; Estados Unidos. Portland State University; Estados UnidosFil: Eyre, Harris. University of California; Estados Unidos. Rice University; Estados UnidosFil: Lawlor, Brian. Trinity College; IrlandaFil: Ibañez, Agustin Mariano. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad de San Andrés; Argentina. Trinity College; Irlanda. University of California; Estados Unidos. Global Brain Health Institute; Estados Unidos. Universidad Adolfo Ibañez; Chil

Intramolecular Structural Heterogeneity altered by Long-range Contacts in an Intrinsically Disordered Protein

Short-range interactions and long-range contacts drive the 3D folding of structured proteins. The proteins' structure has a direct impact on their biological function. However, nearly 40% of the eukaryotes proteome is composed of intrinsically disordered proteins (IDPs) and protein regions that fluctuate between ensembles of numerous conformations. Therefore, to understand their biological function, it is critical to depict how the structural ensemble statistics correlate to the IDPs' amino acid sequence. Here, using small-angle x-ray scattering (SAXS) and time-resolved F\"orster resonance energy transfer (trFRET), we study the intra-molecular structural heterogeneity of the neurofilament low intrinsically disordered tail domain (NFLt). Using theoretical results of polymer physics, we find that the Flory scaling exponent of NFLt sub-segments correlates linearly with their net charge, ranging from statistics of ideal to self-avoiding chains. Surprisingly, measuring the same segments in the context of the whole NFLt protein, we find that regardless of the peptide sequence, the segments' structural statistics are more expanded than when measured independently. Our findings show that while polymer physics can, to some level, relate the IDP's sequence to its ensemble conformations, long-range contacts between distant amino acids play a crucial role in determining intra-molecular structures. This emphasizes the necessity of advanced polymer theories to fully describe IDPs ensembles with the hope it will allow us to model their biological function