Spatial soil zinc content distribution from terrain parameters: A GIS-based decision-tree model in Lebanon

Heavy metal contamination has been and continues to be a worldwide phenomenon that has attracted a great deal of attention from governments and regulatory bodies. In this context, our study proposes a regression-tree model to predict the concentration level of zinc in the soils of northern Lebanon (as a case study of Mediterranean landscapes) under a GIS environment. The developed tree-model explained 88% of variance in zinc concentration using pH (100% in relative importance), surroundings of waste areas (90%), proximity to roads (80%), nearness to cities (50%), distance to drainage line (25%), lithology (24%), land cover/use (14%), slope gradient (10%), conductivity (7%), soil type (7%), organic matter (5%), and soil depth (5%). The overall accuracy of the quantitative zinc map produced (at 1:50.000 scale) was estimated to be 78%. The proposed tree model is relatively simple and may also be applied to other areas.     

Echolocation beam shape in emballonurid bats, Saccopteryx bilineata and Cormura brevirostris

The shape of the sonar beam plays a crucial role in how echolocating bats perceive their surroundings. Signal design may thus be adapted to optimize beam shape to a given context. Studies suggest that this is indeed true for vespertilionid bats, but little is known from the remaining 16 families of echolocating bats. We investigated the echolocation beam shape of two species of emballonurid bats, Cormura brevirostris and Saccopteryx bilineata, while they navigated a large outdoor flight cage on Barro Colorado Island, Panama. C. brevirostris emitted more directional signals than did S. bilineata. The difference in directionality was due to a markedly different energy distribution in the calls. C. brevirostris emitted two call types, a multiharmonic shallowly frequency-modulated call and a multiharmonic sweep, both with most energy in the fifth harmonic around 68?kHz. S. bilineata emitted only one call type, multiharmonic shallowly frequency-modulated calls with most energy in the second harmonic (~46?kHz). When comparing same harmonic number, the directionality of the calls of the two bat species was nearly identical. However, the difference in energy distribution in the calls made the signals emitted by C. brevirostris more directional overall than those emitted by S. bilineata. We hypothesize that the upward shift in frequency exhibited by C. brevirostris serves to increase directionality, in order to generate a less cluttered auditory scene. The study indicates that emballonurid bats are forced to adjust their relative harmonic energy instead of adjusting the fundamental frequency, as the vespertilionids do, presumably due to a less flexible sound production.     

Use of optical scatter sensors for measurement of visibility

A study on the measurement of visibility by the use of light scattering has been carried out. The basis for the research was the optical forward-scatter sensor, Mira visibility sensor, developed and produced by Aanderaa Instruments. The focus of the study was on how to measure correct visibility at different weather situations (e.g. fog, rain, haze and snow) and how a sensor can provide information on the type of particles/drops which are causing reduced visibility. Optical scatter measurement of airborne dust was also investigated. The work includes theoretical calculations and experimental work. The correlations between scatter measurements and both visibility and the concentration of airborne dust are studied. A short introduction to the subject of visibility measurement is also included.