Characteristics, Origins, and Biosignature Preservation Potential of Carbonate-Bearing Rocks Within and Outside of Jezero Crater

Carbonate minerals have been detected in Jezero crater, an ancient lake basin that is the landing site of the Mars 2020 Perseverance rover, and within the regional olivine-bearing (ROB) unit in the Nili Fossae region surrounding this crater. It has been suggested that some carbonates in the margin fractured unit, a rock unit within Jezero crater, formed in a fluviolacustrine environment, which would be conducive to preservation of biosignatures from paleolake-inhabiting lifeforms. Here, we show that carbonate-bearing rocks within and outside of Jezero crater have the same range of visible-to-near-infrared carbonate absorption strengths, carbonate absorption band positions, thermal inertias, and morphologies. Thicknesses of exposed carbonate-bearing rock cross-sections in Jezero crater are ∼75-90 m thicker than typical ROB unit cross-sections in the Nili Fossae region, but have similar thicknesses to ROB unit exposures in Libya Montes. These similarities in carbonate properties within and outside of Jezero crater is consistent with a shared origin for all of the carbonates in the Nili Fossae region. Carbonate absorption minima positions indicate that both Mg- and more Fe-rich carbonates are present in the Nili Fossae region, consistent with the expected products of olivine carbonation. These estimated carbonate chemistries are similar to those in martian meteorites and the Comanche carbonates investigated by the Spirit rover in Columbia Hills. Our results indicate that hydrothermal alteration is the most likely formation mechanism for non-deltaic carbonates within and outside of Jezero crater.

Synergistic Ground and Orbital Observations of Iron Oxides on Mt. Sharp and Vera Rubin Ridge

Visible/short-wave infrared spectral data from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) show absorptions attributed to hematite at Vera Rubin ridge (VRR), a topographic feature on northwest Mt. Sharp. The goals of this study are to determine why absorptions caused by ferric iron are strongly visible from orbit at VRR and to improve interpretation of CRISM data throughout lower Mt. Sharp. These goals are achieved by analyzing coordinated CRISM and in situ spectral data along the Curiosity Mars rover's traverse. VRR bedrock within areas that have the deepest ferric absorptions in CRISM data also has the deepest ferric absorptions measured in situ. This suggests strong ferric absorptions are visible from orbit at VRR because of the unique spectral properties of VRR bedrock. Dust and mixing with basaltic sand additionally inhibit the ability to measure ferric absorptions in bedrock stratigraphically below VRR from orbit. There are two implications of these findings: (1) Ferric absorptions in CRISM data initially dismissed as noise could be real, and ferric phases are more widespread in lower Mt. Sharp than previously reported. (2) Patches with the deepest ferric absorptions in CRISM data are, like VRR, reflective of deeper absorptions in the bedrock. One model to explain this spectral variability is late-stage diagenetic fluids that changed the grain size of ferric phases, deepening absorptions. Curiosity's experience highlights the strengths of using CRISM data for spectral absorptions and associated mineral detections and the caveats in using these data for geologic interpretations and strategic path planning tools.

Spectrum of advice and curbside consultations of infectious diseases specialists

OBJECTIVES

Curbside consultation (CC) of infectious diseases specialists for advice is very frequent but the corresponding workload has rarely been assessed. This activity is mostly oral (phone or direct contact) and poorly quantifiable because it is not charged. We had for aim to evaluate this activity in a French teaching hospital.

METHODS

We recorded all CCs given during a 2.5-year period, from mid-2011 to the end of 2013.

RESULTS

During the study period, 6789 CCs were recorded (2715 per year), or slightly more than 10 per day. These CCs were divided in 676 travel recommendations and 6113 for other reasons. They were mostly given by phone (77.4%). Most demands came from our hospital (61.4%), followed by community family physicians and specialist (27.1%), other local hospitals (6.5%) and clinics (4.3%). All the departments in our hospital consulted us for advice at least once and answers were mainly given by phone (70.1%) and at bedside (30.5%). The answers were principally advice (50.8%), modification of antibiotic prescription (22.9%), initiation of antibiotic course (14.8%), maintaining the same treatment (6.2%), and stopping antibiotics (4.3%). CCs accounted for 20% of clinical work for 1 physician. If the CCs in our hospital had been paid, our department would have received an additional 77,000€ in revenue.

CONCLUSION

This curbside activity is very important and time-consuming for infectious diseases specialists, but it is currently not acknowledged or rewarded.

Soil diversity and hydration as observed by ChemCam at Gale crater, Mars

The ChemCam instrument, which provides insight into martian soil chemistry at the submillimeter scale, identified two principal soil types along the Curiosity rover traverse: a fine-grained mafic type and a locally derived, coarse-grained felsic type. The mafic soil component is representative of widespread martian soils and is similar in composition to the martian dust. It possesses a ubiquitous hydrogen signature in ChemCam spectra, corresponding to the hydration of the amorphous phases found in the soil by the CheMin instrument. This hydration likely accounts for an important fraction of the global hydration of the surface seen by previous orbital measurements. ChemCam analyses did not reveal any significant exchange of water vapor between the regolith and the atmosphere. These observations provide constraints on the nature of the amorphous phases and their hydration.

[Community-acquired meningitis due to methicillin susceptible Staphylococcus aureus]

Meningitis due to Staphylococcus aureus is infrequent. MRSA is mainly found after neurosurgery, but MSSA may be involved in community-acquired meningitis. However, this kind of infection is not widely reported, despite its severity.

METHODS

We describe the characteristics of five patients hospitalized in our ward over a period of 18 months who presented with community-acquired meningitis due to MSSA.

RESULTS

The patients were three men and two women with a mean age of 62 years. One patient was immunosuppressed. Neurological signs were present at the onset for only two patients. In all cases, there were extraneurological localizations of the infection, mainly in bones (spondylodiscitis, epidural abscess, arthritis) but also lung infection. Three patients with meningeal inflammation also presented with confusion. CSF analysis revealed less than 950 white blood cells, hyper-CSF-proteins, and hypo-CSF-glucose. Bacteraemia was present in all patients. The source of infection was never determined. The evolution was good for all patients with a prolonged antibiotic course. The analysis of genetic determinants for three strains revealed the presence of TSST-1 which could account for the severity of the disease.

CONCLUSION

Community-acquired MSSA meningitis is a serious infection, occurring in patients without risk factors. Hematogenous dissemination leads to multiple tissue infection. A long course of antibiotics, with high doses, is needed to treat meningitis but also extraneurological localizations. The role of TSST-1 needs to be confirmed in other patients.

Global Mineralogical and Aqueous Mars History Derived from OMEGA/Mars Express Data

Global mineralogical mapping of Mars by the Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activité (OMEGA) instrument on the European Space Agency's Mars Express spacecraft provides new information on Mars' geological and climatic history. Phyllosilicates formed by aqueous alteration very early in the planet's history (the "phyllocian" era) are found in the oldest terrains; sulfates were formed in a second era (the "theiikian" era) in an acidic environment. Beginning about 3.5 billion years ago, the last era (the "siderikian") is dominated by the formation of anhydrous ferric oxides in a slow superficial weathering, without liquid water playing a major role across the planet.

Phyllosilicates on Mars and implications for early martian climate

The recent identification of large deposits of sulphates by remote sensing and in situ observations has been considered evidence of the past presence of liquid water on Mars. Here we report the unambiguous detection of diverse phyllosilicates, a family of aqueous alteration products, on the basis of observations by the OMEGA imaging spectrometer on board the Mars Express spacecraft. These minerals are mainly associated with Noachian outcrops, which is consistent with an early active hydrological system, sustaining the long-term contact of igneous minerals with liquid water. We infer that the two main families of hydrated alteration products detected-phyllosilicates and sulphates--result from different formation processes. These occurred during two distinct climatic episodes: an early Noachian Mars, resulting in the formation of hydrated silicates, followed by a more acidic environment, in which sulphates formed.

[The homeopathy or the myth of pure experience]

Hahnemann and homeopaths have always hold that the origine of homeopathy was essentially experimental. The Hippocrate's method of observation, the experience with quinquina carried out by Hahnemann in 1790, and furthermore a similar experimental thought than the C. Bernard's one, are constantly put forward. The alchemist origins of homeopathy, in particular Paracelse, that old authors had found, have been scathingly denied. It stands yet to reason that the rôle of the paracelsian philosophy, through the german philosophy at the Hahnemann's time and the medical vitalism at its acme at that time, was crucial. Nevertheless, the direct part of contemporary physicians, specially english ones, as Nugent, J. Hunter and Cullen has been disregarded. Hahnemann, proudly, said nothing about his most important springs. The history of his ideas, the theorical and conceptual problems involved by the principle of similitude and not only the infinitesimality, show that homeopathy arises, not so much from experience as from theoretical ideas, and mind of system so current before C. Bernard. It can be easily showed that C. Bernard's epistemology, which is prevailing in biology today, is a logical obstacle to homeopathy.