Scientific access into Mercer Subglacial Lake: scientific objectives, drilling operations and initial observations

The Subglacial Antarctic Lakes Scientific Access (SALSA) Project accessed Mercer Subglacial Lake using environmentally clean hot-water drilling to examine interactions among ice, water, sediment, rock, microbes and carbon reservoirs within the lake water column and underlying sediments. A ~0.4 m diameter borehole was melted through 1087 m of ice and maintained over ~10 days, allowing observation of ice properties and collection of water and sediment with various tools. Over this period, SALSA collected: 60 L of lake water and 10 L of deep borehole water; microbes >0.2 μm in diameter from in situ filtration of ~100 L of lake water; 10 multicores 0.32–0.49 m long; 1.0 and 1.76 m long gravity cores; three conductivity–temperature–depth profiles of borehole and lake water; five discrete depth current meter measurements in the lake and images of ice, the lake water–ice interface and lake sediments. Temperature and conductivity data showed the hydrodynamic character of water mixing between the borehole and lake after entry. Models simulating melting of the ~6 m thick basal accreted ice layer imply that debris fall-out through the ~15 m water column to the lake sediments from borehole melting had little effect on the stratigraphy of surficial sediment cores.

Single-Entry Models in Surgical Services

In the health care system, common elements of SEMs include pooled referrals and waiting lists, centralized intake through a single-entry point, and triage for urgency and appropriateness. Four programs including the use of SEMs from the Canadian context were examined: the Winnipeg Central Intake System for hip and knee replacements, the British Columbia Surgical Strategy, the Nova Scotia Hip and Knee Action Plan, and the Saskatchewan Surgical Initiative. SEMs were generally implemented as 1 element of broader strategies to reduce surgical waits and enhance quality and safety of surgical services.Key success factors for implementation of SEMs included: Concurrent investments in surgical capacity and health system resources. The establishment of standardized clinical pathways to reduce care variation. Strong leadership, including a focus on change management and use of clinician champions. Standardized data collection and public reporting on key performance indicators. Concurrent focus on quality improvement and patient-centred care. Challenges for implementation of SEMs included: Effectively managing change and resistance to change. Challenges in other areas of the health system that could impact wait times. Maintaining strategic focus and predictable funding, especially in the face of external shocks.

Nondestructive Tree Stem and Crown Volume Allometry in Hybrid Poplar Plantations Derived from Terrestrial Laser Scanning

Accurate and frequently updated tree volume estimates are required for poplar plantations, which are characterized by fast growth rate and short rotation. In this study, we tested the potential of terrestrial laser scanning (TLS) as a reliable method for developing nondestructive tree volume allometries in poplar plantations. The trial was conducted in Italy, where 4- to 10-year-old hybrid plantations were sampled to develop tree crown volume allometry in leaf-on conditions, tree stem volume, and height-diameter allometries in leaf-off conditions. We tested one-entry models based on diameter and two-entry models based on both diameter and height. Model performance was assessed by residual analysis. Results indicate that TLS can provide accurate models of tree stem and crown volume, with percentage of root-mean-square error of about 20 percent and 15 percent, respectively. The inclusion of height does not bring relevant improvement in the models, so that only diameter can be used to predict tree stem and crown volume. The TLS-measured stem volume estimates agreed with an available formula derived from harvesting. We concluded that TLS is a reliable method for developing nondestructive volume allometries in poplar plantations and holds great potential to enhance conventional tree inventory and monitoring. Study Implications: Terrestrial laser scanning (TLS) is a technique that allows nondestructive measurement of the three-dimensional structure of a tree with high precision and low cost. The ability of TLS to measure both tree crown volume and tree position can be effective to test optimal spacing requirements and also to test innovative schemes such as mixed or polycyclic poplar plantations. The spatially explicit nature of TLS measurements allows better integration with different remotely sensed sensors, which can be used in combination with TLS, enabling a multiscale assessment of poplar plantation structure with different levels of detail, enhancing conventional tree inventory and supporting effective management strategies.

Kinetics of White Soft Minerals (WSMs) Decomposition under Conditions of Interest for Astrobiology: A Theoretical and Experimental Study

In this paper, the thermal decomposition kinetics of a class of minerals that we call White Soft Minerals (WSMs) is studied by means of theoretical and experimental methods, in connection to the transport of extraterrestrial organic matter to Earth and the possible use of the decomposition reaction in the characterization of these minerals in space. WSMs include, under a single denomination, carbonates and sulphates of Mg, Fe, and Ca. To improve the present knowledge of the properties of such materials, we use the following techniques: kinetic models for chemical decomposition, atmospheric entry models, spectroscopy, and gravimetric analyses. Model results show that the atmospheric entry of WSM grains is strongly affected by their thermal decomposition. The decomposition reaction, being strongly endothermic, tends to significantly lower the grain temperature during the atmospheric entry, especially at high altitudes and for grazing entries. A previously proposed infrared spectroscopic technique to evaluate the degree of advancement of the reaction is found to be in good agreement with gravimetric measurements for calcium carbonate. The numerical model developed for the atmospheric entry scenarios is used to interpret experimental results. These main findings show that an additional contribution to the reaction enthalpy is needed to reproduce the experimental results, suggesting that the present theoretical model needs improvements such as the account of gas diffusion in the materials.

Improving access to health services in Canada

The Commonwealth Fund 2017 report ranked Canada’s healthcare system low in access to care and last among all 11 counties studied in terms of timeliness of care. While long wait times for certain elective surgical procedures appear to be emblematic of Canadian Medicare, they are not inevitable. Wait times could be improved by focusing on public awareness and measurement of wait times and improving the appropriateness, efficiency (eg, with implementation of single-entry models for surgical referrals and greater use of ambulatory surgery), and productivity of surgical care (eg, by activity-based funding for surgical procedures and by reducing the cost of perioperative care). Ideas on how physician leaders can build on recent accomplishments are provided.