Estimating herbaceous aboveground biomass in Sahelian rangelands using structure from motion data collected on the ground and by UAV

1.Herbaceous aboveground biomass (HAB) is a key indicator of grassland vegetation and indirect estimation tools, such as remote sensing imagery, increase the potential for covering larger areas in a timely and cost-efficient way. Structure from motion (SfM) is an image analysis process that can create a 3D model from a set of images. 2: Computed from UAV and ground camera measurements, the SfM potential to estimate the herbaceous aboveground biomass in Sahelian rangelands was tested in this study. Both UAV and ground camera recordings were used at three different scales: temporal, landscape and national (across Senegal). All images were processed using PIX4D software and were used to extract vegetation indices and heights. 3: A random forest algorithm was used to estimate the HAB and the average estimation errors were around 150 g.m-² for fresh mass (20% relative error) and 60 g.m-² for dry mass (around 25% error). A comparison between different datasets revealed that the estimates based on camera data were slightly more accurate than those from UAV data. 4:It was also found that combining datasets across scales for the same type of tool (UAV or camera) could be a useful option for monitoring HAB in Sahelian rangelands or in other grassy ecosystem.

On the seismicity and tectonic activity Of the Bengal basin

The tectonic activity of the Bengal basin for years 1850-1988 of seismicity and 16 years (1970-1985) of P-wave first motion data have been studied. The seismicity studies reveal three seismic belts such as Dhubri fault (striking N-S), Calcutta hinge zone (striking NE-SW) and the central region of the Bengal basin (striking NW-SE). Dauki fault is comparatively less seismically active than Dhubri fault. The seismicity of Dhubri fault and Calcutta hinge zone are confined to limited extension. The seismic activity along the central portion of the Bengal basin is extending from the Himalayan region (27°N, 88.5°E) to eastern plate margin (23.8°N, 92°E). .This appears to be a tectonic belt and is associated with the northeast drifting of Indian plate. The focal, mechanism studies reveal thrust faulting showing the stresses to be perpendicular to the proposed belt.

Prediction of Flooded Compartment Damage Locations in Ships by Using Spectrum Analysis of Ship Motions in Waves

Considering the nature of marine accidents, even a single accident can result in significant damage to the environment and property, as well as loss of life. Therefore, the initial response should be rapid and accurate, and various decision support systems have been developed to achieve this. Research on simulating progressive flooding on board immediately after an accident is being actively conducted, but this requires high levels of computing power. In this study, a methodology for converting simulated ship motion data into a ship motion database is presented. The model of a training ship from the Korea Institute of Maritime and Fisheries Technology and KRISO in-house code SMTP was used for ship motion computations. The short-time Fourier transform was used to convert time-series motion data into a spectrogram motion database. A methodology for deriving a predicted location of the damage center is presented. The candidate locations of the damage centers were obtained by comparing the root mean square error values of the ship motion database from the simulation and real-time ship motion data. Finally, a probability function was suggested to confirm the predicted location of the damage center. Using 100 randomly selected test cases, our method showed 95% accuracy.

Functional Hand-Based Splint in the Treatment of Metacarpal Fractures

Background: Post-treatment stiffness remains a significant hurdle following treatment for displaced or minimally displaced metacarpal fractures. Treatment goals should focus on a stable and acceptable reduction, minimal patient morbidity, and optimal mobility. Methods: A retrospective review of all non-operative metacarpal fractures over a five-month period at a tertiary center hand clinic treated with a hand-based splint were reviewed for radiologic and clinical stability. The splint allowed metacarpophalngeal joint, interphalangeal joint, and radiocarpal joint motion. Data collected included age, handedness, type and location of fracture, occupation, and ability to continue working. Radiologic images were reviewed by a radiologist not otherwise involved in patient care. Results: Thirty-three patients were reviewed with a total of 39 fractures of the second, third, fourth, and fifth metacarpals. Nine patients had nondominant hand fractures while 24 were dominant hand injuries. Twenty out of 24 patients employed pre-injury were able to continue working without missing any days. Three patients were lost to the final follow-up. The average splint duration was 24 days. Twenty-seven of 30 patients showed no change in alignment from start of splinting to end, while three showed some change but remained within non-operative criteria. Conclusion: A hand-based functional splint for metacarpal fractures allows for excellent maintenance of fracture reduction, early or immediate return to pre-injury activities, low patient morbidity, and maintains functional motion throughout treatment. It can be applied to any non-operative fracture of the second through the fifth metacarpal.

NGA-Subduction research program

This article summarizes the Next Generation Attenuation (NGA) Subduction (NGA-Sub) project, a major research program to develop a database and ground motion models (GMMs) for subduction regions. A comprehensive database of subduction earthquakes recorded worldwide was developed. The database includes a total of 214,020 individual records from 1,880 subduction events, which is by far the largest database of all the NGA programs. As part of the NGA-Sub program, four GMMs were developed. Three of them are global subduction GMMs with adjustment factors for up to seven worldwide regions: Alaska, Cascadia, Central America and Mexico, Japan, New Zealand, South America, and Taiwan. The fourth GMM is a new Japan-specific model. The GMMs provide median predictions, and the associated aleatory variability, of RotD50 horizontal components of peak ground acceleration, peak ground velocity, and 5%-damped pseudo-spectral acceleration (PSA) at oscillator periods ranging from 0.01 to 10 s. Three GMMs also quantified “within-model” epistemic uncertainty of the median prediction, which is important in regions with sparse ground motion data, such as Cascadia. In addition, a damping scaling model was developed to scale the predicted 5%-damped PSA of horizontal components to other damping ratios ranging from 0.5% to 30%. The NGA-Sub flatfile, which was used for the development of the NGA-Sub GMMs, and the NGA-Sub GMMs coded on various software platforms, have been posted for public use.

Ranking and Selection of Earthquake Ground-Motion Models Using the Stochastic Area Metric

We introduce the cumulative-distribution-based area metric (AM)—also known as stochastic AM—as a scoring metric for earthquake ground-motion models (GMMs). The AM quantitatively informs the user of the degree to which observed or test data fit with a given model, providing a rankable absolute measure of misfit. The AM considers underlying data distributions and model uncertainties without any assumption of form. We apply this metric, along with existing testing methods, to four GMMs in order to test their performance using earthquake ground-motion data from the Preston New Road (United Kingdom) induced seismicity sequences in 2018 and 2019. An advantage of the proposed approach is its applicability to sparse datasets. We, therefore, focus on the ranking of models for discrete ranges of magnitude and distance, some of which have few data points. The variable performance of models in different ranges of the data reveals the importance of considering alternative models. We extend the ranking of GMMs through analysis of intermodel variations of the candidate models over different ranges of magnitude and distance using the AM. We find the intermodel AM can be a useful tool for selection of models for the logic-tree framework in seismic-hazard analysis. Overall, the AM is shown to be efficient and robust in the process of selection and ranking of GMMs for various applications, particularly for sparse and small-sized datasets.

Postural Instability after Stepping on a Stair in Older Adults: A Pilot Study

This study aimed to examine how older adults (OA) control their postural stability after stepping on a stair in comparison to young adults (YA). Ten OA and 10 YA participated in this study. Participants ascended a single stair (15 cm high by 30 cm wide) which was secured atop one of the force plates. Ground reaction forces (GRFs) and center of pressure (COP) motion data were obtained from the force plate under the stair. After standing on the stair with both feet, GRFs and COP data for a 3 s duration were analyzed to assess postural variables, including time to stabilization (TTS), COP velocity (COPVEL), and COP sway area (COPSWAY). A significant difference in TTS in the anterior–posterior direction between OA and YA (p = 0.032) was observed, indicating that OA had difficulty stabilizing their body posture after the stair ascent compared to YA. For COP postural variables, no significant differences in COPVEL (p = 0.455) and COPSWAY (p = 0.176) were observed between OA and YA. Study findings indicate that older adults have less capacity to regain postural stability compared to young adults following a challenging dynamic movement.