High Survivability of Micrometeorites on Mars: Sites With Enhanced Availability of Limiting Nutrients

NASA's strategy in exploring Mars has been to follow the water, because water is essential for life, and it has been found that there are many locations where there was once liquid water on the surface. Now perhaps, to narrow down the search for life on a barren basalt‐dominated surface, there needs to be a refocusing to a strategy of “follow the nutrients.” Here we model the entry of metallic micrometeoroids through the Martian atmosphere, and investigate variations in micrometeorite abundance at an analogue site on the Nullarbor Plain in Australia, to determine where the common limiting nutrients available in these (e.g., P, S, Fe) become concentrated on the surface of Mars. We find that dense micrometeorites are abundant in a range of desert environments, becoming concentrated by aeolian processes into specific sites that would be easily investigated by a robotic rover. Our modeling suggests that micrometeorites are currently far more abundant on the surface of Mars than on Earth, and given the far greater abundance of water and warmer conditions on Earth and thus much more active weather system, this was likely true throughout the history of Mars. Because micrometeorites contain a variety of redox sensitive minerals including FeNi alloys, sulfide and phosphide minerals, and organic compounds, the sites where these become concentrated are far more nutrient rich, and thus more compatible with chemolithotrophic life than most of the Martian surface

Recreating the OSIRIS-REx Slingshot Manoeuvre from a Network of Ground-Based Sensors

Optical tracking systems typically trade-off between astrometric precision and field-of-view. In this work, we showcase a networked approach to optical tracking using very wide field-of-view imagers that have relatively low astrometric precision on the scheduled OSIRIS-REx slingshot manoeuvre around Earth on September 22nd, 2017. As part of a trajectory designed to get OSIRIS-REx to NEO 101955 Bennu, this flyby event was viewed from 13 remote sensors spread across Australia and New Zealand to promote triangulatable observations. Each observatory in this portable network was constructed to be as lightweight and portable as possible, with hardware based off the successful design of the Desert Fireball Network. Over a 4 hour collection window, we gathered 15,439 images of the night sky in the predicted direction of the OSIRIS-REx spacecraft. Using a specially developed streak detection and orbit determination data pipeline, we detected 2,090 line-of-sight observations. Our fitted orbit was determined to be within about 10~km of orbital telemetry along the observed 109,262~km length of OSIRIS-REx trajectory, and thus demonstrating the impressive capability of a networked approach to SSA

Erratum to: Methods for evaluating medical tests and biomarkers

[This corrects the article DOI: 10.1186/s41512-016-0001-y.]

Evidence synthesis to inform model-based cost-effectiveness evaluations of diagnostic tests: a methodological systematic review of health technology assessments

Background: Evaluations of diagnostic tests are challenging because of the indirect nature of their impact on patient outcomes. Model-based health economic evaluations of tests allow different types of evidence from various sources to be incorporated and enable cost-effectiveness estimates to be made beyond the duration of available study data. To parameterize a health-economic model fully, all the ways a test impacts on patient health must be quantified, including but not limited to diagnostic test accuracy. Methods: We assessed all UK NIHR HTA reports published May 2009-July 2015. Reports were included if they evaluated a diagnostic test, included a model-based health economic evaluation and included a systematic review and meta-analysis of test accuracy. From each eligible report we extracted information on the following topics: 1) what evidence aside from test accuracy was searched for and synthesised, 2) which methods were used to synthesise test accuracy evidence and how did the results inform the economic model, 3) how/whether threshold effects were explored, 4) how the potential dependency between multiple tests in a pathway was accounted for, and 5) for evaluations of tests targeted at the primary care setting, how evidence from differing healthcare settings was incorporated. Results: The bivariate or HSROC model was implemented in 20/22 reports that met all inclusion criteria. Test accuracy data for health economic modelling was obtained from meta-analyses completely in four reports, partially in fourteen reports and not at all in four reports. Only 2/7 reports that used a quantitative test gave clear threshold recommendations. All 22 reports explored the effect of uncertainty in accuracy parameters but most of those that used multiple tests did not allow for dependence between test results. 7/22 tests were potentially suitable for primary care but the majority found limited evidence on test accuracy in primary care settings. Conclusions: The uptake of appropriate meta-analysis methods for synthesising evidence on diagnostic test accuracy in UK NIHR HTAs has improved in recent years. Future research should focus on other evidence requirements for cost-effectiveness assessment, threshold effects for quantitative tests and the impact of multiple diagnostic tests

Erratum to: Methods for evaluating medical tests and biomarkers

[This corrects the article DOI: 10.1186/s41512-016-0001-y.]

GRADE Guidelines: 16. GRADE evidence to decision frameworks for tests in clinical practice and public health

Objectives: To describe the grading of recommendations assessment, development and evaluation (GRADE) interactive evidence to decision (EtD) frameworks for tests and test strategies for clinical, public health, or coverage decisions. Study Design and Setting: As part of the GRADE Working Group's DECIDE project, we conducted workshops, user testing with systematic review authors, guideline developers and other decision makers, and piloted versions of the EtD framework. Results: EtD frameworks for tests share the structure, explicitness, and transparency of other EtD frameworks. They require specifying the purpose of the test, linked or related management, and the key outcomes of concern for different test results and subsequent management. The EtD criteria address test accuracy and assessments of the certainty of the additional evidence necessary for decision making. When there is no direct evidence of test effects on patient-important outcomes, formal or informal modeling is needed to estimate effects. We describe the EtD criteria based on examples developed with GRADEpro (www.gradepro.org), GRADE's software that also allows development and dissemination of interactive summary of findings tables. Conclusion: EtD frameworks for developing recommendations and making decisions about tests lay out the sequential steps in reviewing and assessing the different types of evidence that need to be linked. (C) 2016 Elsevier Inc. All rights reserve

GRADE Guidelines : 16. GRADE evidence to decision frameworks for tests in clinical practice and public health

Objectives To describe the grading of recommendations assessment, development and evaluation (GRADE) interactive evidence to decision (EtD) frameworks for tests and test strategies for clinical, public health, or coverage decisions. Study Design and Setting As part of the GRADE Working Group's DECIDE project, we conducted workshops, user testing with systematic review authors, guideline developers and other decision makers, and piloted versions of the EtD framework. Results EtD frameworks for tests share the structure, explicitness, and transparency of other EtD frameworks. They require specifying the purpose of the test, linked or related management, and the key outcomes of concern for different test results and subsequent management. The EtD criteria address test accuracy and assessments of the certainty of the additional evidence necessary for decision making. When there is no direct evidence of test effects on patient-important outcomes, formal or informal modeling is needed to estimate effects. We describe the EtD criteria based on examples developed with GRADEpro (www.gradepro.org), GRADE's software that also allows development and dissemination of interactive summary of findings tables. Conclusion EtD frameworks for developing recommendations and making decisions about tests lay out the sequential steps in reviewing and assessing the different types of evidence that need to be linked

GRADE Guidelines : 16. GRADE evidence to decision frameworks for tests in clinical practice and public health

Objectives To describe the grading of recommendations assessment, development and evaluation (GRADE) interactive evidence to decision (EtD) frameworks for tests and test strategies for clinical, public health, or coverage decisions. Study Design and Setting As part of the GRADE Working Group's DECIDE project, we conducted workshops, user testing with systematic review authors, guideline developers and other decision makers, and piloted versions of the EtD framework. Results EtD frameworks for tests share the structure, explicitness, and transparency of other EtD frameworks. They require specifying the purpose of the test, linked or related management, and the key outcomes of concern for different test results and subsequent management. The EtD criteria address test accuracy and assessments of the certainty of the additional evidence necessary for decision making. When there is no direct evidence of test effects on patient-important outcomes, formal or informal modeling is needed to estimate effects. We describe the EtD criteria based on examples developed with GRADEpro (www.gradepro.org), GRADE's software that also allows development and dissemination of interactive summary of findings tables. Conclusion EtD frameworks for developing recommendations and making decisions about tests lay out the sequential steps in reviewing and assessing the different types of evidence that need to be linked

Recreating the OSIRIS-REx slingshot manoeuvre from a network of ground-based sensors

Optical tracking systems typically trade off between astrometric precision and field of view. In this work, we showcase a networked approach to optical tracking using very wide field-of-view imagers that have relatively low astrometric precision on the scheduled OSIRIS-REx slingshot manoeuvre around Earth on 22 Sep 2017. As part of a trajectory designed to get OSIRIS-REx to NEO 101955 Bennu, this flyby event was viewed from 13 remote sensors spread across Australia and New Zealand to promote triangulatable observations. Each observatory in this portable network was constructed to be as lightweight and portable as possible, with hardware based off the successful design of the Desert Fireball Network. Over a 4-h collection window, we gathered 15 439 images of the night sky in the predicted direction of the OSIRIS-REx spacecraft. Using a specially developed streak detection and orbit determination data pipeline, we detected 2 090 line-of-sight observations. Our fitted orbit was determined to be within about 10 km of orbital telemetry along the observed 109 262 km length of OSIRIS-REx trajectory, and thus demonstrating the impressive capability of a networked approach to Space Surveillance and Tracking.This work was funded by the Australian Research Council as part of the Australian Discovery Project scheme, with funding from the Australian Government and the Government of Western Australia. This work was also supported by an Australian Government Research Training Program (RTP) Scholarship. This research made use of Astropy, a communitydeveloped core Python package for Astronomy (The Astropy Collaboration et al. 2013). Some figures in this work were generated using Matplotlib, another community-developed Python package (Hunter 2007)