Biomarker and Geochemical Assay Validation in Mars Analog Sites: Lessons from the FELDSPAR (Field Exploration and Life Detection Sampling for Planetary Analog Research) Project

Missions looking for signs of life on other worlds can often only take a few samples once they arrive. Making sense of these "few and far between" observations is easier if we know what a "normal" level of variation for that kind of planet is. Recent eruption sites in Iceland are good places to learn about this, because they have very little life present and the same types of rocks as many places on Mars. We have visited several of these sites in Iceland and tested many different kinds of measurements: the energy available for life, the amount of DNA (an important biological molecule) present, the relative amounts of different kinds of micro-organisms, and the specific minerals that make up the rocks and ground. In addition to recommendations for future expeditions, we have also shown that using early on-site measurements to choose later on-site sample sites is very helpful in reducing the number of sample sites needed

Characterizing Habitable Environments on Mars Using Infrared Spectroscopy from Orbit

Thesis (Ph.D.)--University of Washington, 2017-03Until recently, the search for habitable environments on Mars has mostly been driven by the motto “follow the water”, as water is thought to be one of the fundamental requirements for life. Over the last several decades, there has been abundant geomorphic and mineralogical evidence for surface and near-surface liquid water early in Mars’ history, increasing the potential for past habitable environments. However, it has becoming progressively clear that there are several more requirements, in addition to liquid water, that make an environment habitable including a source of energy for biochemical processes, major and trace elements to form macromolecules (e.g., CHNOPS), as well as clement physicochemical conditions (e.g., pH, salinity, temperature). The search for habitable environments on Mars has now become more refined, searching for locales that show evidence for not only liquid water, but these other important constraints. This dissertation first focuses on the Nili Fossae region of Mars, an area that shows extensive evidence for aqueous alteration with a diverse range of hydrated minerals. This work views the region through the lens of both bulk surface composition and secondary alteration minerals, in particular with respect to minerals that would indicate not only liquid water but an energy source and a means for creating organic materials, such as with serpentinization. The study ultimately uses what is learned in Nili Fossae to better understand the global distribution of mineralogical evidence for serpentinizing systems detectable from available orbital data. The studies presented here rely on near-infrared (~1.0-3.0 µm) reflectance and thermal-infrared (~5-50 µm) emissivity measurements of both the martian surface and terrestrial analog materials to best describe the composition of surfaces exposed in Nili Fossae. Chapter Two uses a complementary approach for looking at near- and thermal-infrared measurements of the surfaces in Nili Fossae to identify elevated bulk-silica exposures that imply increased aqueous alteration of a capping unit that was previously considered unaltered. This extends aqueous alteration to all three major stratigraphic units in the area. Chapter Three uses near- and thermal-infrared laboratory measurements of rocks from the Lost City Hydrothermal Field on Earth to better constrain the geochemical and astrobiological environment that formed similar minerals in Nili Fossae, Mars. This work identified a suite of spectral types and minerals (serpentine, Mg-carbonate, and talc/saponite) associated with low-temperature serpentinizing systems on Earth and compared them to what was observed in Nili Fossae. This resulted in an additional identification of serpentine within the region, and additional evidence for a sustained habitable serpentinizing system in Nili Fossae. This framework was used to search for similar sites across Mars in Chapter Four. This produced a global map of the distribution of spectral types associated with low-temperature serpentinizing systems. This study resulted in new identifications of serpentine across the southern highlands, predominately in isolated exposures in crater and valley walls, crater ejecta and ancient knobby terrains. Additionally, it found that serpentine was much more pervasive in the Nili Fossae region than previously thought, making it an increasingly compelling site for future detailed surface investigations with respect to habitability

The surgical safety checklist and patient outcomes after surgery: a prospective observational cohort study, systematic review and meta-analysis

© 2017 British Journal of Anaesthesia Background: The surgical safety checklist is widely used to improve the quality of perioperative care. However, clinicians continue to debate the clinical effectiveness of this tool. Methods: Prospective analysis of data from the International Surgical Outcomes Study (ISOS), an international observational study of elective in-patient surgery, accompanied by a systematic review and meta-analysis of published literature. The exposure was surgical safety checklist use. The primary outcome was in-hospital mortality and the secondary outcome was postoperative complications. In the ISOS cohort, a multivariable multi-level generalized linear model was used to test associations. To further contextualise these findings, we included the results from the ISOS cohort in a meta-analysis. Results are reported as odds ratios (OR) with 95% confidence intervals. Results: We included 44 814 patients from 497 hospitals in 27 countries in the ISOS analysis. There were 40 245 (89.8%) patients exposed to the checklist, whilst 7508 (16.8%) sustained ≥1 postoperative complications and 207 (0.5%) died before hospital discharge. Checklist exposure was associated with reduced mortality [odds ratio (OR) 0.49 (0.32–0.77); P\u3c0.01], but no difference in complication rates [OR 1.02 (0.88–1.19); P=0.75]. In a systematic review, we screened 3732 records and identified 11 eligible studies of 453 292 patients including the ISOS cohort. Checklist exposure was associated with both reduced postoperative mortality [OR 0.75 (0.62–0.92); P\u3c0.01; I2=87%] and reduced complication rates [OR 0.73 (0.61–0.88); P\u3c0.01; I2=89%). Conclusions: Patients exposed to a surgical safety checklist experience better postoperative outcomes, but this could simply reflect wider quality of care in hospitals where checklist use is routine

Prospective observational cohort study on grading the severity of postoperative complications in global surgery research

Background The Clavien–Dindo classification is perhaps the most widely used approach for reporting postoperative complications in clinical trials. This system classifies complication severity by the treatment provided. However, it is unclear whether the Clavien–Dindo system can be used internationally in studies across differing healthcare systems in high- (HICs) and low- and middle-income countries (LMICs). Methods This was a secondary analysis of the International Surgical Outcomes Study (ISOS), a prospective observational cohort study of elective surgery in adults. Data collection occurred over a 7-day period. Severity of complications was graded using Clavien–Dindo and the simpler ISOS grading (mild, moderate or severe, based on guided investigator judgement). Severity grading was compared using the intraclass correlation coefficient (ICC). Data are presented as frequencies and ICC values (with 95 per cent c.i.). The analysis was stratified by income status of the country, comparing HICs with LMICs. Results A total of 44 814 patients were recruited from 474 hospitals in 27 countries (19 HICs and 8 LMICs). Some 7508 patients (16·8 per cent) experienced at least one postoperative complication, equivalent to 11 664 complications in total. Using the ISOS classification, 5504 of 11 664 complications (47·2 per cent) were graded as mild, 4244 (36·4 per cent) as moderate and 1916 (16·4 per cent) as severe. Using Clavien–Dindo, 6781 of 11 664 complications (58·1 per cent) were graded as I or II, 1740 (14·9 per cent) as III, 2408 (20·6 per cent) as IV and 735 (6·3 per cent) as V. Agreement between classification systems was poor overall (ICC 0·41, 95 per cent c.i. 0·20 to 0·55), and in LMICs (ICC 0·23, 0·05 to 0·38) and HICs (ICC 0·46, 0·25 to 0·59). Conclusion Caution is recommended when using a treatment approach to grade complications in global surgery studies, as this may introduce bias unintentionally

Critical care admission following elective surgery was not associated with survival benefit:prospective analysis of data from 27 countries

Purpose: As global initiatives increase patient access to surgical treatments, there is a need to define optimal levels of perioperative care. Our aim was to describe the relationship between the provision and use of critical care resources and postoperative mortality. Methods: Planned analysis of data collected during an international 7-day cohort study of adults undergoing elective in-patient surgery. We used risk-adjusted mixed-effects logistic regression models to evaluate the association between admission to critical care immediately after surgery and in-hospital mortality. We evaluated hospital-level associations between mortality and critical care admission immediately after surgery, critical care admission to treat life-threatening complications, and hospital provision of critical care beds. We evaluated the effect of national income using interaction tests. Results: 44,814 patients from 474 hospitals in 27 countries were available for analysis. Death was more frequent amongst patients admitted directly to critical care after surgery (critical care: 103/4317 patients [2%], standard ward: 99/39,566 patients [0.3%]; adjusted OR 3.01 [2.10–5.21]; p < 0.001). This association may differ with national income (high income countries OR 2.50 vs. low and middle income countries OR 4.68; p = 0.07). At hospital level, there was no association between mortality and critical care admission directly after surgery (p = 0.26), critical care admission to treat complications (p = 0.33), or provision of critical care beds (p = 0.70). Findings of the hospital-level analyses were not affected by national income status. A sensitivity analysis including only high-risk patients yielded similar findings. Conclusions: We did not identify any survival benefit from critical care admission following surgery