On biosignatures for Mars

In this work, we address the difficulty of reliably identifying traces of life on Mars. Several independent lines of evidence are required to build a compelling body of proof. In particular, we underline the importance of correctly interpreting the geological and mineralogical context of the sites to be explored for the presence of biosignatures. We use as examples to illustrate this, ALH84001 (where knowledge of the geological context was very limited) and other terrestrial deposits, for which this could be properly established. We also discuss promising locations and formations to be explored by ongoing and future rover missions, including Oxia Planum, which, dated at 4.0 Ga, is the most ancient Mars location targeted for investigation yet

Habitability on Early Mars and the Search for Biosignatures with the ExoMars Rover

The second ExoMars mission will be launched in 2020 to target an ancient location interpreted to have strong potential for past habitability and for preserving physical and chemical biosignatures (as well as abiotic/prebiotic organics). The mission will deliver a lander with instruments for atmospheric and geophysical investigations and a rover tasked with searching for signs of extinct life. The ExoMars rover will be equipped with a drill to collect material from outcrops and at depth down to 2 m. This subsurface sampling capability will provide the best chance yet to gain access to chemical biosignatures. Using the powerful Pasteur payload instruments, the ExoMars science team will conduct a holistic search for traces of life and seek corroborating geological context information. Key Words: Biosignatures—ExoMars—Landing sites—Mars rover—Search for life. Astrobiology 17, 471–510

Characterizing Rock Abundance At ExoMars Landing Site Candidates

We present preliminary work to characterize surface rock abundance at ExoMars Rover landing site candidates. A challenge in quantifying the abundance of surface rocks is using the population of large (≳1 m) rocks that are resolved in orbital images to infer the size of the smaller, unresolved rock population. This is particularly relevant for the ExoMars Rover mission, where the Landing Module’s clearance of 35 cm makes it necessary to know the probability of encountering rocks where 0.35 < D < 1 m. ‘Float rocks’ are individual fragments of rock not associated with a continuous outcrop or body of rock —e.g. transported rocks or impact debris. These can be identified in Mars Reconnaissence Orbiter HiRISE images, where the mid-afternoon local solar time, dictated by MROs’ orbit, causes float rocks to appear as bright sunlit features adjacent to strong shadows. However, the smallest features resolvable in HiRISE images occupy around 3-4 pixels, corresponding to ~1-m sized rocks. This inherently limits the ability to directly identify from orbit the small, but potentially hazardous rock population. ‘Outcrop’ is defined as continuous expanses of bedrock or surficial deposits exposed at the surface. Both float rocks and outcrop can contribute to slopes that may constitute a hazard for landed missions. We present rock counts at ExoMars Rover landing site candidates and assess approaches to constrain the morphological characteristics of Mars’ surface that are relevant to rover and lander safety

Trivial centralizers for Axiom A diffeomorphisms

We show there is a residual set of non-Anosov $C^{\infty}$ Axiom A diffeomorphisms with the no cycles property whose elements have trivial centralizer. If $M$ is a surface and $2\leq r\leq \infty$, then we will show there exists an open and dense set of of $C^r$ Axiom A diffeomorphisms with the no cycles property whose elements have trivial centralizer. Additionally, we examine commuting diffeomorphisms preserving a compact invariant set $\Lambda$ where $\Lambda$ is a hyperbolic chain recurrent class for one of the diffeomorphisms.Comment: 18 page

Direct comparison of B-Type Natriuretic Peptide (BNP) and amino-terminal proBNP in a large population of patients with chronic and symptomatic heart failure: the Valsartan Heart Failure (Val-HeFT) data

Background: The B-type or brain natriuretic peptides (BNP) and the amino-terminal probrain natriuretic peptide (NT-proBNP) are good markers of prognosis and diagnosis in chronic heart failure (HF). It is unclear, however, whether differences in their biological characteristics modify their clinical correlates and prognostic performance in HF. This work aimed to provide a direct comparison of the prognostic value of BNP and NTproBNP in patients with chronic and stable HF. Methods: We measured BNP and NT-proBNP at baseline in 3916 patients enrolled in the Valsartan Heart Failure Trial. To identify the variables associated with both peptides, we conducted simple and multivariable linear regression analyses. We used Cox multivariable regression models to evaluate the independent prognostic value for all-cause mortality, mortality and morbidity, and hospitalization for HF. Prognostic performance was assessed by pairwise comparisons of the area under the curve of receiver-operator characteristic curves. Results: NT-proBNP and BNP had similar relationships with age, left ventrical ejection fraction, and internal diameter and creatinine clearance. Either peptide ranked as the first independent predictor of outcome after adjustment for major confounding clinical characteristics. ROC curves were almost superimposable for all-cause mortality (area under the curve (SE): BNP 0.665 (0.011) vs NT-proBNP 0.679 (0.011); P 0.0734), but NT-proBNP was superior to BNP for predicting mortality and morbidity (P 0.032) or hospitalization for HF (P 0.0143). Overall sensitivity and specificity ranged from 0.590 to 0.696. Conclusions: The natriuretic peptides BNP and NTproBNP showed subtle differences in their relation to clinical characteristics and prognostic performance in a large population of patients with chronic and stable HF. They were the most powerful independent markers of outcome in HF

Contemplative Practices and Mental Training: Prospects for American Education

This article draws on research in neuroscience, cognitive science, developmental psychology, and education, as well as scholarship from contemplative traditions concerning the cultivation of positive development, to highlight a set of mental skills and socioemotional dispositions that are central to the aims of education in the 21st century. These include self‐regulatory skills associated with emotion and attention, self‐representations, and prosocial dispositions such as empathy and compassion. It should be possible to strengthen these positive qualities and dispositions through systematic contemplative practices, which induce plastic changes in brain function and structure, supporting prosocial behavior and academic success in young people. These putative beneficial consequences call for focused programmatic research to better characterize which forms and frequencies of practice are most effective for which types of children and adolescents. Results from such research may help refine training programs to maximize their effectiveness at different ages and to document the changes in neural function and structure that might be induced.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/92125/1/cdep240.pd

2018 MAX-C/ExoMars Mission: The Orleans Mars-Analogue Rock Collection for Instrument Testing

International audienceIn order to reply to the exobiological goals of the 2018 MAX-C/ExoMars mission, the Orléans-OSUC analogue rock collection and database contains well characterised Mars analogue rocks and minerals for use in instrument testing and in situ missions