Requirements for a global lidar system: spaceborne lidar with wall-to-wall coverage.

Lidar is the optimum technology for measuring bare-Earth elevation beneath, and the structure of, vegetation. Consequently, airborne laser scanning (ALS) is widely employed for use in a range of applications. However, ALS is not available globally nor frequently updated due to its high cost per unit area. Spaceborne lidar can map globally but energy requirements limit existing spaceborne lidars to sparse sampling missions, unsuitable for many common ALS applications. This paper derives the equations to calculate the coverage a lidar satellite could achieve for a given set of characteristics (released open-source), then uses a cloud map to determine the number of satellites needed to achieve continuous, global coverage within a certain time-frame. Using the characteristics of existing in-orbit technology, a single lidar satellite could have a continuous swath width of 300 m when producing a 30 m resolution map. Consequently, 12 satellites would be needed to produce a continuous map every 5 years, increasing to 418 satellites for 5 m resolution. Building 12 of the currently in-orbit lidar systems is likely to be prohibitively expensive and so the potential of technological developments to lower the cost of a global lidar system (GLS) are discussed. Once these technologies achieve a sufficient readiness level, a GLS could be cost-effectively realized.

Hypercoagulability in dogs with chronic enteropathy and association with serum albumin concentration.

BACKGROUND: Dogs with protein-losing enteropathy (PLE) are at risk of developing a hypercoagulable state, but the prevalence of hypercoagulability in dogs with chronic enteropathies (CE) and normal serum albumin concentration is unknown. HYPOTHESIS: Dogs with CE are predisposed to a hypercoagulable state as assessed by thromboelastography (TEG) independent of serum albumin concentration. METHODS: Dogs with chronic gastrointestinal signs from suspected inflammatory CE between 2017 and 2019 were included. Thirty-eight were evaluated; every dog had a CBC, serum biochemistry panel, and abdominal imaging performed. The Canine Inflammatory Bowel Disease Activity Index (CIBDAI) was calculated. Thromboelastography was performed at presentation, and reaction time (R), kinetic time (K), α-angle, maximal amplitude (MA), and global clot strength (G) were recorded. Dogs were considered hypercoagulable if the G value was ≥25% above the reference interval. RESULTS: Seventeen of 38 (44.7%; 95% confidence interval [CI], 28.6-61.7%) dogs with CE were hypercoagulable. The G value did not differ between the 19 dogs with normal (≥28 g/L) serum albumin concentrations (9.05 kdyn/cm2 ; 95% CI, 7.26-10.84; SD 3.71) and 19 dogs with hypoalbuminemia (11.3 kdyn/cm2 ; 95% CI, 9.04-13.6, SD; 4.7; P = .11). The G value was negatively correlated with hematocrit, serum albumin concentration, and duration of signs and positively correlated with age. CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with CE and normal serum albumin concentration can be hypercoagulable as measured by TEG.