In this work, a vision-based guidance algorithm for interception of an aerial manoeuvring target is proposed. Vision-based aerial engagement in 3D space in an outdoor environment is challenging due to uncertainty in estimating the target location. The vision-based guidance algorithm proposed here generates the desired velocity commands for the interceptor drone based on the orientation of the target pixel in the image plane. The desired velocity at the centre of gravity of the interceptor is calculated such that the velocity at the camera centre is aligned towards the line joining the target pixel and the camera centre. It is shown that the proposed guidance strategy forces the target pixel towards the centre of the image plane and leads to low miss distance. The algorithm developed is first tested in the ROS-Gazebo platform and then implemented in field experiments.

Invasive winter annual grass infestations on rangeland accumulate large quantities of litter on the soil surface, as plants senesce yearly and decompose slowly. It has been speculated that winter annual grass litter can adsorb soil-active herbicides and reduce overall performance. Three experiments were conducted from 2017 to 2018 at the Colorado State University Weed Research Laboratory to evaluate interception and subsequent desorption of herbicides applied to litter from three invasive winter annual grass species with simulated rainfall. Imazapic, rimsulfuron, and indaziflam were applied to medusahead [Taeniatherum caput-medusae (L.) Nevski], ventenata [Ventenata dubia (Leers) Coss.], and downy brome (Bromus tectorum L.) litter at two amounts (equivalent to 1,300 and 2,600 kg ha−1). Rainfall was simulated at 3, 6, 12, and 24 mm at 0, 1, and 7 d after herbicide application. Herbicide concentration from the collected rainfall was measured using liquid chromatography–tandem mass spectrometry. At 2,600 kg ha−1, B. tectorum herbicide interception was 84.3%, while V. dubia and T. caput-medusae averaged 76% herbicide interception. There were no differences in desorption among the three litter types. Simulated rainfall at 0 d after application recovered 100% of the intercepted rimsulfuron and imazapic from B. tectorum litter, while recovery decreased to 65% with rainfall at 1 or 7 d after application. Only 54% of indaziflam could be recovered at 0 d, and recovery decreased to 33% when rainfall was applied at 1 or 7 d after application. Applying soil-active herbicides before forecasted rain or tank mixing with a POST herbicide to provide initial control could potentially increase the amount of herbicide reaching the soil and provide more consistent invasive winter annual grass control.

Wild oat control options are limited in western Canada due to resistance to most common herbicides. Control of wild oat with pyroxasulfone, a soil-applied, very-long-chain fatty-acid inhibitor, was investigated. A series of greenhouse and field experiments were conducted to isolate the effects of vertical seed position, site of herbicide interception, and tillage on wild oat control with pyroxasulfone in comparison with triallate. In greenhouse experiments, wild oat shoot length (soil surface to leaf tip) was reduced (P<0.05) in shallow-seeded wild oat compared with deep-seeded wild oat with pyroxasulfone (6.2 and 9.8 cm, respectively) and triallate (3.7 and 13.2 cm, respectively). Soil-applied pyroxasulfone remained in the top 2.5 cm of the soil with or without a simulated rainfall event. Pyroxasulfone was most effective if either the seed or the shoot 1 cm above the seed intercepted the herbicide layer. If a wild oat emerges from deeper in the soil profile, the sensitive part of the seedling may not intercept an effective rate of pyroxasulfone in the soil. In field experiments comparing deep- and shallow-seeded wild oat treated with pyroxasulfone and triallate in fields with and without tillage, there were no significant effects of tillage alone on wild oat shoot length. Deep-seeded wild oat emerged early, and while herbicides reduced shoot growth, shoots were >10 cm. Shallow-seeded wild oat had delayed emergence, possibly due to reduced soil moisture, and herbicides reduced shoot growth to <10cm. Pyroxasulfone is likely to be more effective in no-till fields where wild oat seeds are not located deep in the soil.

Epiphytes and their associated decomposing litter and arboreal soils (herein, epiphytic material, EM) are ubiquitous features of tropical montane cloud forests (TMCF) and play important roles in ecosystem function. EM intercepts water and nutrients from the atmosphere and from intercepted host tree sources, and may contribute significant inputs of these resources to the forest floor. Despite the importance of EM in the TMCF, a systematic review of the ecosystem roles of EM has not been compiled before. We have synthesized the literature that documents functions of EM in undisturbed TMCFs and discuss how these roles may be affected by disturbances, including changes in climate and land use. The range of EM biomass and water storage in the TMCF varies greatly across sites, with different amounts associated with stand age and microclimate. EM is important as habitat and food for birds and mammals, with over 200 species of birds documented as using EM in the Neotropics. Given its sensitivity to moisture, projected shifts in cloud base heights or precipitation due to changes in climate will likely have a large impact on this community and changes in EM diversity or abundance may have cascading impacts on the ecosystem function of the TMCF.

This article offers a series of justifications for early interceptive treatment as opposed to later treatment that might necessarily involve the extraction of permanent teeth. The biological responses of the membranous sutures, of the periosteum, of the periodontal ligaments, and of the condylar cartilages but also of the potential for growth in stature, well before the pre-pubertal growth spurt and the administration of effective treatments, are also reasons that support an early phase of treatment, in the early mixed dentition, even in the primary dentition!

Some early orthodontic or orthopedic treatments and their appliances such as buccal screens, myofunctional trainers, occlusal splints or sectional expansion plates and other maxillary expansion and protraction appliances are useful for correcting deformities or severe under-developments that are already in place.

But myofunctional re-education, when carried out according to a structured and prioritized program, is perhaps the most important because these etiopathogenic treatments used to both suppress the causes of the deformations and to restore balanced function, make it possible to re-establish a normal growth pattern and perhaps consequently, to avoid the need for extraction of permanent teeth.

This article presents efficient and practical methods for path planning of optimal interceptions on two-dimensional grids with obstacles, such as raster charts or non-distorted digital maps. The proposed methods search for optimal paths from sources to multiple moving-targets by a novel higher geometry wave propagation scheme in the grids, instead of the traditional vector scheme in the graphs. By introducing a time-matching scheme, the optimal interception paths from sources to all the moving-targets are obtained among the combinations with linear time and space complexities. Two optimal path planning methods for multiple one-to-one interceptions, the MIN-MAX and MIN-AVG, are applied to emulate the real routing.

Throughfall volume and interception of bulk precipitation events were measured during individual rain events of differing magnitudes in a primary wet tropical forest at La Selva Biological Station, Costa Rica. The relationship between canopy structure and throughfall were examined to identify key sources of spatial variation. Geostatistical analyses were also used to examine the spatial variation in throughfall, spatial autocorrelation and to determine minimum distances for independence of collectors. Throughfall volume was collected from 56 ground-based (funnel-style) collectors. Throughfall was collected for 26 separate precipitation events during July and August 1998. Per cent cover, distance to nearest tree, distance to nearest leaf were also estimated for each collection point. A weak relationship was found with per cent cover (r2 = 0.11). No relationship was found between throughfall and distance to the nearest leaf above the collector. Estimated interception was 1.88 mm (r2 = 0.94) with increased variance as bulk precipitation increased. A range distance of 45 m was estimated from variograms, strongly suggesting that large tree canopies and gaps are the source of much of the spatial variance in throughfall volume. Interception was reduced by 19% if only spatially independent collectors were used.

The results of a series of experiments to study the physical processes governing the evaporation from upland vegetation in Scotland, i.e. coniferous forest, heather and grass, are described. Particular attention is given to the interception process occurring in heather, one of the dominant indigenous species in Scottish upland catchments. Attention is also given to the interception of snow precipitation which in the Scottish uplands is a significant proportion of the total precipitation. A comparison of the parameters describing the efficiency of the transport process of water vapour for coniferous forest and heather indicates that the process is more efficient than predicted by classical diffusion theory: additional transport mechanisms are considered. A simple model, based upon the results of the process studies, was applied to data from the Monachyle catchment (Balquhidder) and the model predictions compared with observations. This study, in conjunction with recent results from the Balquhidder catchment experiment, illustrates the necessity of further investigations to give a fuller understanding of the evaporation from high altitude grassland.