Climatic variations on Mars: 2. Evolution of carbon dioxide atmosphere and polar caps

The long-term variations in the atmospheric pressure and the polar cap temperature of Mars resulting from the obliquity oscillations (presented by W. R. Ward, 1974) are discussed. In performing these calculations, the assumption is made that the atmosphere is in equilibrium with perennial CO_2 ice deposits at the north pole, as is proposed by R. B. Leighton and B. C. Murray (1966). If heat transport by the atmosphere is neglected, the temperature of CO_2 ice at the poles ranges from ∼130°K to ∼160°K, the corresponding atmospheric pressure rising from a few tenths of a millibar to ∼30 mbar, respectively. The neglect of atmospheric heat transport probably underestimates the peak pressure. Because the altitude of the south cap is ∼2 km higher than that of the north cap, CO_2 ice is unstable there and will migrate to the north cap at a rate ∼10 g/cm^2 yr, the implication being that the south residual cap is water ice. A simplified model of the annual polar caps and pressure fluctuations is also presented. This indicates that when the obliquity is at its maximum, the annual caps may be greatly enlarged in both mass and maximum coverage. The modifications introduced by including significant atmospheric heat transport are then discussed. Finally, the implications of different past climatic conditions on the mechanism of eolian erosion are briefly considered

Some comparisons of impact craters on Mercury and the Moon

Although the general morphologies of fresh mercurian and lunar craters are remarkably similar, comparisons of ejecta deposits, interior structures, and changes in morphology with size reveal important differences between the two populations of craters. The differences are attributable to the different gravity fields in which the craters were formed and have significant implications for the interpretation of cratering processes and their effects on all planetary bodies

Need and baseline for harmonising nursing education in respiratory care: preliminary results of a global survey

Background: The COVID-19 pandemic confirmed that respiratory nurses are critical healthcare providers. Limited knowledge is available about appropriate education to prepare nurses to deliver high-quality respiratory care. A survey was developed by the International Coalition for Respiratory Nursing (ICRN) group to identify the need for a respiratory nursing core curriculum. Method: A 39-item survey was distributed to 33 respiratory nursing experts in 27 countries. Questions asked about current roles, perception of need, expectations for a core curriculum project and respiratory content in nursing education in their countries. Results: 30 responses from 25 countries were analysed; participants predominantly worked in academia (53.3%, 16/30) and clinical practice (40%, 12/30). In total, 97% (29/30) confirmed a need for a core respiratory nursing curriculum. Post-registration nursing programmes at bachelor (83.3%, 25/30) and masters (63.3%, 19/30) levels include internal/medical nursing care; less than half identified separate respiratory nursing content. The core educational programme developed should include knowledge (70%, 21/30), skills (60%, 18/30), and competencies (50%, 15/30), with separate paediatric and adult content. Conclusion: Survey results confirm a wide variation in nursing education and respiratory nursing education across the world, with many countries lacking any formal educational programmes to prepare nurses capable of providing enhanced quality respiratory care. These findings support the need for a core respiratory curriculum. To advance this significant work the ICRN group plans to conduct a Delphi study to identify core curriculum requirements for respiratory nursing education at pre-registration and advanced educational levels to flexibly meet each country's specific educational requirements for recognition of respiratory nursing speciality practice

Some comparisons of impact craters on Mercury and the Moon

Although the general morphologies of fresh mercurian and lunar craters are remarkably similar, comparisons of ejecta deposits, interior structures, and changes in morphology with size reveal important differences between the two populations of craters. The differences are attributable to the different gravity fields in which the craters were formed and have significant implications for the interpretation of cratering processes and their effects on all planetary bodies

Detailed stratigraphy and bed thickness of the Mars north and south polar layered deposits

The Mars polar layered deposits (PLD) likely hold an extensive record of recent climate during a period of high-amplitude orbit and obliquity cycles. Previous work has detected limited evidence for orbital signatures within PLD stratigraphy, but data from the High Resolution Imaging Science Experiment (HiRISE) permit renewed analysis of PLD stratigraphy at sub-meter scale. Topography derived from HiRISE images using stereogrammetry resolves beds previously detectable only as alternating light and dark bands in visible images. We utilize these data to measure the thickness of individual beds within the PLD, corrected for non-horizontal bed orientation. Stratigraphic columns and bed thickness profiles are presented for two sites within the NPLD, and show several sets of finely bedded units 1–2 m thick; isolated marker beds 3–4 m thick; and undifferentiated sections. Bed thickness measurements for three sites within the SPLD exhibit only one bed type based on albedo and morphology, and bed thicknesses have a larger mean and variance compared to measurements for the NPLD. Power spectra of brightness and slope derived along the measured stratigraphic sections confirm the regularity of NPLD fine bed thickness, and the lack of a dominant SPLD bed thickness. The regularity of fine bed thickness of the NPLD is consistent with quasiperiodic bed formation, albeit with unknown temporal period; the SPLD thickness measurements show no such regularity

Need and baseline for harmonising nursing education in respiratory care: preliminary results of a global survey

Background: The COVID-19 pandemic confirmed that respiratory nurses are critical healthcare providers. Limited knowledge is available about appropriate education to prepare nurses to deliver high-quality respiratory care. A survey was developed by the International Coalition for Respiratory Nursing (ICRN) group to identify the need for a respiratory nursing core curriculum.Method: A 39-item survey was distributed to 33 respiratory nursing experts in 27 countries. Questions asked about current roles, perception of need, expectations for a core curriculum project and respiratory content in nursing education in their countries.Results: 30 responses from 25 countries were analysed; participants predominantly worked in academia (53.3%, 16/30) and clinical practice (40%, 12/30). In total, 97% (29/30) confirmed a need for a core respiratory nursing curriculum. Post-registration nursing programmes at bachelor (83.3%, 25/30) and masters (63.3%, 19/30) levels include internal/medical nursing care; less than half identified separate respiratory nursing content. The core educational programme developed should include knowledge (70%, 21/30), skills (60%, 18/30), and competencies (50%, 15/30), with separate paediatric and adult content.Conclusion: Survey results confirm a wide variation in nursing education and respiratory nursing education across the world, with many countries lacking any formal educational programmes to prepare nurses capable of providing enhanced quality respiratory care. These findings support the need for a core respiratory curriculum. To advance this significant work the ICRN group plans to conduct a Delphi study to identify core curriculum requirements for respiratory nursing education at pre-registration and advanced educational levels to flexibly meet each country's specific educational requirements for recognition of respiratory nursing speciality practice

Seasonal melting and the formation of sedimentary rocks on Mars, with predictions for the Gale Crater mound

A model for the formation and distribution of sedimentary rocks on Mars is proposed. The rate-limiting step is supply of liquid water from seasonal melting of snow or ice. The model is run for a O(10^2) mbar pure CO2 atmosphere, dusty snow, and solar luminosity reduced by 23%. For these conditions snow only melts near the equator, and only when obliquity >40 degrees, eccentricity >0.12, and perihelion occurs near equinox. These requirements for melting are satisfied by 0.01-20% of the probability distribution of Mars' past spin-orbit parameters. Total melt production is sufficient to account for aqueous alteration of the sedimentary rocks. The pattern of seasonal snowmelt is integrated over all spin-orbit parameters and compared to the observed distribution of sedimentary rocks. The global distribution of snowmelt has maxima in Valles Marineris, Meridiani Planum and Gale Crater. These correspond to maxima in the sedimentary-rock distribution. Higher pressures and especially higher temperatures lead to melting over a broader range of spin-orbit parameters. The pattern of sedimentary rocks on Mars is most consistent with a Mars paleoclimate that only rarely produced enough meltwater to precipitate aqueous cements and indurate sediment. The results suggest intermittency of snowmelt and long globally-dry intervals, unfavorable for past life on Mars. This model makes testable predictions for the Mars Science Laboratory rover at Gale Crater. Gale Crater is predicted to be a hemispheric maximum for snowmelt on Mars.Comment: Submitted to Icarus. Minor changes from submitted versio