Ancient Siliciclastic-Evaporites as Seen by Remote Sensing Instrumentation with Implications for the Rover-Scale Exploration of Sedimentary Environments on Mars.

Accurate interpretation of the martian sedimentary rock record-and by extension that planet's paleoenvironmental history and potential habitability-relies heavily on rover-based acquisition of textural and compositional data and researchers to properly interpret those data. However, the degree to which this type of remotely sensed information can be unambiguously resolved and accurately linked to geological processes in ancient sedimentary systems warrants further study. In this study, we characterize Mars-relevant siliciclastic-evaporite samples by traditional laboratory-based geological methods (thin section petrography, X-ray diffraction [XRD], backscattered electron imaging, microprobe chemical analyses) and remote sensing methods relevant to martian rover payloads (visible-near-mid infrared reflectance spectroscopy, X-ray fluorescence mapping, XRD). We assess each method's ability to resolve primary and secondary sedimentologic features necessary for the accurate interpretation of paleoenvironmental processes. While the most dominant textures and associated compositions (i.e., bedded gypsum evaporite) of the sample suite are readily identified by a combination of remote sensing techniques, equally important, although more subtle, components (i.e., interbedded windblown silt, meniscus cements) are not resolved unambiguously in bulk samples. However, rover-based techniques capable of coordinating spatially resolved compositional measurements with textural imaging reveal important features not readily detected using traditional assessments (i.e., subtle clay-organic associations, microscale diagenetic nodules). Our findings demonstrate the improved generational capacity of rovers to explore ancient sedimentary environments on Mars while also highlighting the complexities in extracting comprehensive paleoenvironmental information when limited to currently available rover-based techniques. Complete and accurate interpretation of ancient martian sedimentary environments, and by extension the habitability of those environments, likely requires sample return or in situ human exploration. Plain Language Summary Only when correctly translated can the ancient martian sedimentary rock record reveal the environmental evolution of the planet's surface through time. In this case study, we characterize Mars-relevant sedimentary rocks and evaluate the degree to which a comprehensive geological picture can be resolved unambiguously when limited to microscale remote sensing methods relevant to rovers on Mars. While the most dominant textural features and associated compositions of the sample suite are readily identified by a combination of remote sensing techniques, equally important but more subtle components are not resolved unambiguously in bulk samples. However, rover-based techniques capable of coordinating spatially resolved compositional measurements with textural imaging, such as Perseverance Rover's Planetary Instrument for X-Ray Lithochemistry instrument, reveal important features not readily detected by more traditional methods. We demonstrate that rovers have, generationally, improved in their capacity to resolve a true geological picture in ancient sedimentary environments, likely owing to an improved ability to coordinate spatially resolved compositional measurements with textural imaging at the microscale. However, our work also highlights the complexities involved in extracting subtle environmental information when limited to currently available rover-based techniques and suggests that comprehensive interpretation of ancient martian sedimentary systems likely requires sample return or in situ human exploration. Key Points Mars-relevant samples are characterized using both traditional laboratory and microscale rover-based remote sensing techniques to assess each method's ability to recognize features necessary for accurate paleoenvironmental process interpretation. While some key paleoenvironmental processes can reasonably be inferred via remote sensing methods, others cannot be resolved unambiguously. Perseverance Rover's Planetary Instrument for X-Ray Lithochemistry instrument reveals diagenetic features that would otherwise remain unseen by traditional thin section petrography.

Pine savanna restoration on agricultural landscapes: The path back to native savanna ecosystem services.

Restoration of savanna ecosystems within their historic range is expected to increase provision of ecosystem services to resident human populations. However, the benefits of restoration depend on the degree to which ecosystems and their services can be restored, the rate of restoration of particular services, and tradeoffs in services between restored ecosystems and other common land uses. We use a chronosequence approach to infer multi-decadal changes in ecosystem services under management aimed at restoring fire-dependent pine savannas, including the use of frequent prescribed fire, following abandonment of row-crop agriculture in the southeastern U.S. We compare ecosystem services between restored pine savannas of different ages and reference pine savannas as well as other common land uses (row-crop agriculture, improved pasture, pine plantation, unmanaged forest). Our results suggest that restoring pine savannas results in many improvements to ecosystem services, including increases in plant species richness, perennial grass cover, tree biomass, total ecosystem carbon, soil carbon and C:N, reductions in soil bulk density and predicted erosion and sedimentation, shifts from soil fungal pathogens to fungal symbionts, and changes in soil chemistry toward reference pine savanna conditions. However, the rate of improvement varies widely among services from a few years to decades. Compared to row-crop agriculture and improved pasture, restored savannas have lower erosion, soil bulk density, and soil pathogens and a higher percentage of mycorrhizal fungi and ecosystem carbon storage. Compared to pine plantations and unmanaged forests, restored pine savannas have lower fire-prone fuel loads and higher water yield and bee pollinator abundance. Our results indicate that restoration of pine savanna using frequent fire provides a broad suite of ecosystem services that increase the landscape's overall resilience to climate change. These results are likely relevant to other savannas dominated by perennial vegetation and maintained with frequent fire.

Effects of fire frequency and season on resprouting of woody plants in southeastern US pine-grassland communities.

Past studies suggest that rates of woody plant resprouting following a "topkilling" disturbance relate to timing of disturbance because of temporal patterns of below-ground carbohydrate storage. Accordingly, we hypothesized that fire-return interval (1 or 2 years) and season of burn (late dormant or early growing season) would influence the change in resprout growth rate from one fire-free interval to the next (Δ growth rate) for broadleaf woody plants in a pine-grassland in Georgia, USA. Resprout growth rate during one fire-free interval strongly predicted growth rate during the following fire-free interval, presumably reflecting root biomass. Length of fire-free interval did not have a significant effect on mean Δ growth rate. Plants burned in the late dormant season (February-March) had a greater positive Δ growth rate than those burned in the early growing season (April-June), consistent with the presumption that root carbohydrates are depleted and thus limiting during spring growth. Plants with resprout growth rates above a certain level had zero or negative Δ growth rates, indicating an equilibrium of maximum resprout size under a given fire-return interval. This equilibrium, as well as relatively reduced resprout growth rate following growing season fires, provide insight into how historic lightning-initiated fires in the early growing season limited woody plant dominance and maintained the herb-dominated structure of pine-grassland communities. Results also indicate tradeoffs between applying prescribed fire at 1- versus 2-year intervals and in the dormant versus growing seasons with the goal of limiting woody vegetation.

Phenotypic plasticity of leaf shape along a temperature gradient in Acer rubrum.

Both phenotypic plasticity and genetic determination can be important for understanding how plants respond to environmental change. However, little is known about the plastic response of leaf teeth and leaf dissection to temperature. This gap is critical because these leaf traits are commonly used to reconstruct paleoclimate from fossils, and such studies tacitly assume that traits measured from fossils reflect the environment at the time of their deposition, even during periods of rapid climate change. We measured leaf size and shape in Acer rubrum derived from four seed sources with a broad temperature range and grown for two years in two gardens with contrasting climates (Rhode Island and Florida). Leaves in the Rhode Island garden have more teeth and are more highly dissected than leaves in Florida from the same seed source. Plasticity in these variables accounts for at least 6-19% of the total variance, while genetic differences among ecotypes probably account for at most 69-87%. This study highlights the role of phenotypic plasticity in leaf-climate relationships. We suggest that variables related to tooth count and leaf dissection in A. rubrum can respond quickly to climate change, which increases confidence in paleoclimate methods that use these variables.

Acne vulgaris.

Acne vulgaris is a common inflammatory skin condition that presents management difficulties to cosmetic surgeons. Acute management and treatment focuses on early diagnosis as well as treatment with topical agents, oral antibiotics, hormonal therapy,and nonablative chemical peel and laser applications. The treatment of postinflammatory scarring must be individualized to address potential macular dyschromia, cystic lesions,epithelial bridges, or deep pitted scars. A review of interventional options is presented to apply to the spectrum of acne scarring as well as a review of the literature to address objectively published reports on efficacy.

Effect of topical mitomycin on skin wound contraction.

OBJECTIVE: To evaluate the effect of different dosing regimens of mitomycin on skin wound contraction. METHODS: Full-thickness skin wounds were created in 5 groups of hairless mice, which represented different dosing regimens or a sterile water control: A, control; B, mitomycin (0.5 mg/mL) applied immediately after creation of the lesion (day 1); C, mitomycin (1.0 mg/mL) applied on day 1; D, mitomycin (0.5 mg/mL) applied on days 1 and 3; and E, mitomycin (1.0 mg/mL) applied on days 1 and 3. Wound surface area was measured immediately after drug application (day 1), and thereafter every 3 to 5 days until day 29 by means of computer-assisted image analysis. RESULTS: All dosing regimens of mitomycin application resulted in an initially exponential rate of wound contraction that was significantly slower than in the sterile water control group, with a significantly larger wound surface area on day 29. Wound area in the control group contracted approximately 9 times more rapidly than in the treatment groups. No difference was observed among the different dosing regimens. CONCLUSION: Application of mitomycin, at the lowest dose and frequency of application used in this study, resulted in improved outcomes with regard to contraction of full-thickness skin wounds.