Formation and evolution of carbonaceous asteroid Ryugu: Direct evidence from returned samples.

Samples of the carbonaceous asteroid Ryugu were brought to Earth by the Hayabusa2 spacecraft. We analyzed 17 Ryugu samples measuring 1 to 8 millimeters. Carbon dioxide-bearing water inclusions are present within a pyrrhotite crystal, indicating that Ryugu's parent asteroid formed in the outer Solar System. The samples contain low abundances of materials that formed at high temperatures, such as chondrules and calcium- and aluminum-rich inclusions. The samples are rich in phyllosilicates and carbonates, which formed through aqueous alteration reactions at low temperature, high pH, and water/rock ratios of <1 (by mass). Less altered fragments contain olivine, pyroxene, amorphous silicates, calcite, and phosphide. Numerical simulations, based on the mineralogical and physical properties of the samples, indicate that Ryugu's parent body formed ~2 million years after the beginning of Solar System formation.

The surface composition of asteroid 162173 Ryugu from Hayabusa2 near-infrared spectroscopy.

The near-Earth asteroid 162173 Ryugu, the target of the Hayabusa2 sample-return mission, is thought to be a primitive carbonaceous object. We report reflectance spectra of Ryugu's surface acquired with the Near-Infrared Spectrometer (NIRS3) on Hayabusa2, to provide direct measurements of the surface composition and geological context for the returned samples. A weak, narrow absorption feature centered at 2.72 micrometers was detected across the entire observed surface, indicating that hydroxyl (OH)-bearing minerals are ubiquitous there. The intensity of the OH feature and low albedo are similar to thermally and/or shock-metamorphosed carbonaceous chondrite meteorites. There are few variations in the OH-band position, which is consistent with Ryugu being a compositionally homogeneous rubble-pile object generated from impact fragments of an undifferentiated aqueously altered parent body.

A Field Guide to Finding Fossils on Mars.

The Martian surface is cold, dry, exposed to biologically harmful radiation and apparently barren today. Nevertheless, there is clear geological evidence for warmer, wetter intervals in the past that could have supported life at or near the surface. This evidence has motivated National Aeronautics and Space Administration and European Space Agency to prioritize the search for any remains or traces of organisms from early Mars in forthcoming missions. Informed by (1) stratigraphic, mineralogical and geochemical data collected by previous and current missions, (2) Earth's fossil record, and (3) experimental studies of organic decay and preservation, we here consider whether, how, and where fossils and isotopic biosignatures could have been preserved in the depositional environments and mineralizing media thought to have been present in habitable settings on early Mars. We conclude that Noachian-Hesperian Fe-bearing clay-rich fluvio-lacustrine siliciclastic deposits, especially where enriched in silica, currently represent the most promising and best understood astropaleontological targets. Siliceous sinters would also be an excellent target, but their presence on Mars awaits confirmation. More work is needed to improve our understanding of fossil preservation in the context of other environments specific to Mars, particularly within evaporative salts and pore/fracture-filling subsurface minerals.

Redox stratification of an ancient lake in Gale crater, Mars.

In 2012, NASA's Curiosity rover landed on Mars to assess its potential as a habitat for past life and investigate the paleoclimate record preserved by sedimentary rocks inside the ~150-kilometer-diameter Gale impact crater. Geological reconstructions from Curiosity rover data have revealed an ancient, habitable lake environment fed by rivers draining into the crater. We synthesize geochemical and mineralogical data from lake-bed mudstones collected during the first 1300 martian solar days of rover operations in Gale. We present evidence for lake redox stratification, established by depth-dependent variations in atmospheric oxidant and dissolved-solute concentrations. Paleoclimate proxy data indicate that a transition from colder to warmer climate conditions is preserved in the stratigraphy. Finally, a late phase of geochemical modification by saline fluids is recognized.

The stratigraphy and evolution of lower Mount Sharp from spectral, morphological, and thermophysical orbital data sets.

We have developed a refined geologic map and stratigraphy for lower Mount Sharp using coordinated analyses of new spectral, thermophysical, and morphologic orbital data products. The Mount Sharp group consists of seven relatively planar units delineated by differences in texture, mineralogy, and thermophysical properties. These units are (1-3) three spatially adjacent units in the Murray formation which contain a variety of secondary phases and are distinguishable by thermal inertia and albedo differences, (4) a phyllosilicate-bearing unit, (5) a hematite-capped ridge unit, (6) a unit associated with material having a strongly sloped spectral signature at visible near-infrared wavelengths, and (7) a layered sulfate unit. The Siccar Point group consists of the Stimson formation and two additional units that unconformably overlie the Mount Sharp group. All Siccar Point group units are distinguished by higher thermal inertia values and record a period of substantial deposition and exhumation that followed the deposition and exhumation of the Mount Sharp group. Several spatially extensive silica deposits associated with veins and fractures show that late-stage silica enrichment within lower Mount Sharp was pervasive. At least two laterally extensive hematitic deposits are present at different stratigraphic intervals, and both are geometrically conformable with lower Mount Sharp strata. The occurrence of hematite at multiple stratigraphic horizons suggests redox interfaces were widespread in space and/or in time, and future measurements by the Mars Science Laboratory Curiosity rover will provide further insights into the depositional settings of these and other mineral phases.

How is an international public health threat advanced in Canada? The case of antimicrobial resistance.

On September 21, 2016, the United Nations General Assembly held a high-level meeting on antimicrobial resistance (AMR). Participating political leaders committed to coordinate action across the human and animal health, agriculture and environmental sectors and to work at national, regional and international levels with the public sector, private sector, civil society and all other relevant actors, including the public. The objective of this article is to outline how the Public Health Agency of Canada (PHAC) has been working to address AMR in Canada. PHAC has used a One Health approach and has been working at the federal level with other government departments and nationally with the provinces, territories, professional organizations and other key players to address AMR. To date, the federal response has focused on surveillance, stewardship and innovation across multiple sectors, including human health, animal health, regulatory actions and research. PHAC is currently working with the provinces and territories as well as key experts in the field to develop a pan-Canadian AMR Framework and subsequent action plan that will outline best practices and approaches to AMR across human and animal health. The Framework will build on previous work done by PHAC and the federal/provincial/territorial Pan-Canadian Public Health Network Council, and recognizes the research expertise in Canada, the need to ensure actions are based on evidence, and to combat AMR through infection prevention and control. The three articles in this issue are examples of the foundational work that has been done federally by PHAC, in developing the Canadian AMR Surveillance System (CARSS), and nationally, through task groups of the Public Health Network Council, in identifying where to strengthen human surveillance of AMR and best practices for stewardship in the human health care system. While we remain in an early stage of national, coordinated AMR action, momentum is building to ensure Canada can respond to this global health threat with a One Health approach involving multiple sectors at local, national and international levels that are all well-aligned with the World Health Organization Global Action Plan.

Deposition, exhumation, and paleoclimate of an ancient lake deposit, Gale crater, Mars.

The landforms of northern Gale crater on Mars expose thick sequences of sedimentary rocks. Based on images obtained by the Curiosity rover, we interpret these outcrops as evidence for past fluvial, deltaic, and lacustrine environments. Degradation of the crater wall and rim probably supplied these sediments, which advanced inward from the wall, infilling both the crater and an internal lake basin to a thickness of at least 75 meters. This intracrater lake system probably existed intermittently for thousands to millions of years, implying a relatively wet climate that supplied moisture to the crater rim and transported sediment via streams into the lake basin. The deposits in Gale crater were then exhumed, probably by wind-driven erosion, creating Aeolis Mons (Mount Sharp).

A habitable fluvio-lacustrine environment at Yellowknife Bay, Gale crater, Mars.

The Curiosity rover discovered fine-grained sedimentary rocks, which are inferred to represent an ancient lake and preserve evidence of an environment that would have been suited to support a martian biosphere founded on chemolithoautotrophy. This aqueous environment was characterized by neutral pH, low salinity, and variable redox states of both iron and sulfur species. Carbon, hydrogen, oxygen, sulfur, nitrogen, and phosphorus were measured directly as key biogenic elements; by inference, phosphorus is assumed to have been available. The environment probably had a minimum duration of hundreds to tens of thousands of years. These results highlight the biological viability of fluvial-lacustrine environments in the post-Noachian history of Mars.

In situ radiometric and exposure age dating of the martian surface.

We determined radiogenic and cosmogenic noble gases in a mudstone on the floor of Gale Crater. A K-Ar age of 4.21 ± 0.35 billion years represents a mixture of detrital and authigenic components and confirms the expected antiquity of rocks comprising the crater rim. Cosmic-ray-produced (3)He, (21)Ne, and (36)Ar yield concordant surface exposure ages of 78 ± 30 million years. Surface exposure occurred mainly in the present geomorphic setting rather than during primary erosion and transport. Our observations are consistent with mudstone deposition shortly after the Gale impact or possibly in a later event of rapid erosion and deposition. The mudstone remained buried until recent exposure by wind-driven scarp retreat. Sedimentary rocks exposed by this mechanism may thus offer the best potential for organic biomarker preservation against destruction by cosmic radiation.

Mineralogy of a mudstone at Yellowknife Bay, Gale crater, Mars.

Sedimentary rocks at Yellowknife Bay (Gale crater) on Mars include mudstone sampled by the Curiosity rover. The samples, John Klein and Cumberland, contain detrital basaltic minerals, calcium sulfates, iron oxide or hydroxides, iron sulfides, amorphous material, and trioctahedral smectites. The John Klein smectite has basal spacing of ~10 angstroms, indicating little interlayer hydration. The Cumberland smectite has basal spacing at both ~13.2 and ~10 angstroms. The larger spacing suggests a partially chloritized interlayer or interlayer magnesium or calcium facilitating H2O retention. Basaltic minerals in the mudstone are similar to those in nearby eolian deposits. However, the mudstone has far less Fe-forsterite, possibly lost with formation of smectite plus magnetite. Late Noachian/Early Hesperian or younger age indicates that clay mineral formation on Mars extended beyond Noachian time.

Hydrated silicate minerals on Mars observed by the Mars Reconnaissance Orbiter CRISM instrument.

Phyllosilicates, a class of hydrous mineral first definitively identified on Mars by the OMEGA (Observatoire pour la Mineralogie, L'Eau, les Glaces et l'Activitié) instrument, preserve a record of the interaction of water with rocks on Mars. Global mapping showed that phyllosilicates are widespread but are apparently restricted to ancient terrains and a relatively narrow range of mineralogy (Fe/Mg and Al smectite clays). This was interpreted to indicate that phyllosilicate formation occurred during the Noachian (the earliest geological era of Mars), and that the conditions necessary for phyllosilicate formation (moderate to high pH and high water activity) were specific to surface environments during the earliest era of Mars's history. Here we report results from the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) of phyllosilicate-rich regions. We expand the diversity of phyllosilicate mineralogy with the identification of kaolinite, chlorite and illite or muscovite, and a new class of hydrated silicate (hydrated silica). We observe diverse Fe/Mg-OH phyllosilicates and find that smectites such as nontronite and saponite are the most common, but chlorites are also present in some locations. Stratigraphic relationships in the Nili Fossae region show olivine-rich materials overlying phyllosilicate-bearing units, indicating the cessation of aqueous alteration before emplacement of the olivine-bearing unit. Hundreds of detections of Fe/Mg phyllosilicate in rims, ejecta and central peaks of craters in the southern highland Noachian cratered terrain indicate excavation of altered crust from depth. We also find phyllosilicate in sedimentary deposits clearly laid by water. These results point to a rich diversity of Noachian environments conducive to habitability.

Giant lipoma of the breast.

Lipomas of the breast are usually small, benign neoplasms which can be treated by simple excision. Diagnosis of these masses, however, can be difficult because of the normal fatty composition of the breast. A number of radiological manoeuvres have been described for diagnosing deep lipomas in the breast, yet the clinical and radiographic identification of these masses remains challenging. We present a case of giant lipoma of the breast which was not appreciated on initial clinical and radiographic evaluation, and which was later found to comprise most of the mass of the breast. Following resection, the deformed breast was reconstructed using folded dermoglandular flaps from the areas expanded by the lipoma with excellent results. This case is an excellent illustration of the difficulties associated with diagnosis of these tumours and the reconstructive options available following excision.

Rotating shaft avulsion amputations of the thumb.

In a three-year period twenty-nine patients were treated for rotating shaft avulsion amputations of the thumb. Twenty-three thumbs were considered suitable for replantation. A staged approach, consisting of primary replantation and secondary nerve grafting and tendon reconstruction, was used because of concern that survival rates would be low. Survival was achieved in nineteen of twenty-three replantations. At mean follow-up of 20.5 months grip strength was 94.6% of the unaffected side and key pinch was 77.1%. Five patients achieved a two-point discrimination less than five millimeters. Success was better anticipated and now a full reconstruction is carried out in a single-stage procedure.

Functional restoration in the upper extremity using free muscle transplantation.

Since 1973, fourteen free muscle transfers for functional upper limb reconstruction have been performed in twelve patients at the Ralph K. Davies Medical Center in San Francisco. All of the patients in this series had lost finger flexion, extension, and/or thumb opposition and were not candidates for simpler methods of reconstruction because of weakness or traumatic loss of balancing musculature. The 12 patients have been followed for one to 9 years. All muscles were successfully transferred without flap loss. Evaluation of the EMG data has shown evidence of reinnervation beginning at approximately two months with fibrillation potentials decreasing and recruitment of increasing numbers of motor units over two to three years. Eleven of the 14 muscles attained movement against resistance; two had movement against gravity and one regained only a flicker of motion. In our experience, the use of free muscle transplantation to restore function is not only technically feasible, but moreover, has resulted in a relatively high degree of patient satisfaction.

Potential ocular damage from microwave exposure during electrosurgery: dosimetric survey.

A dosimetric survey of microwave radiation emitted by electrosurgical units used in operating rooms indicated that surgeons expose themselves to levels that may be hazardous, and that ocular exposures are especially high: 20 cm from the active lead, electric field strength at the eye/forehead position was 9.0 X 10(6) V2/M2 for the monopolar unit; and magnetic field strength at this position reached a magnitude of 3.5 A2/M2. These electric and magnetic fields exceeded the TLVs of the American National Standards Institute. The authors concluded that the high levels of microwave radiation generated by electrosurgery devices should receive immediate attention to assess health effects associated with such exposures.

Correlation between thiopental induction dose and the volume of distribution of caffeine in human subjects.

The correlation between the apparent volume of distribution (aVd) of caffeine and the induction dose of thiopental was studied in 23 patients. Caffeine, which has an effective partition coefficient that approaches that of thiopental, was used as an indicator substance to estimate the immediate volume of distribution of thiopental. The immediate volume of distribution is critical in determining thiopental induction dose. The aVd of caffeine was determined noninvasively from serial saliva samples after consumption of caffeine, which was given to the patients as coffee. A strong correlation (r = .69; P less than .01) was found between the aVd of caffeine and the anesthetic induction dose of thiopental when the loss of eyelid reflex was used as the end point. The correlation between thiopental induction dose and body weight for the same individuals (r = .188) was not statistically significant.