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AbstractPrevious work has shown that African elephants Loxodonta africana will avoid African honeybees Apis mellifera scutellata. Here we present results from a pilot study conducted to evaluate the concept of using beehives to mitigate elephant crop depredation. In Laikipia, Kenya, we deployed a 90‐m fence‐line of nine inter‐connected hives, all empty, on two exposed sides of a square two‐acre farm that was experiencing high levels of elephant crop depredation. Compared with a nearby control farm of similar status and size, our experimental farm experienced fewer raids and consequently had higher productivity. Socioeconomic indicators suggest that not only was the concept of a beehive fence popular and desired by the community but also that it can pay for its construction costs through the sale of honey and bee products. We are calling for experiments testing this concept of a ‘guardian beehive‐fence’ to be conducted rigorously and scientifically in as wide a range of agricultural settings as possible to evaluate jointly its effectiveness and efficiency.

Unmanned aerial vehicles (UAVs) flown by adversaries are an emerging asymmetric threat to homeland security and the military. To help address this threat, we developed and tested a computationally efficient UAV detection algorithm consisting of horizon finding, motion feature extraction, blob analysis, and coherence analysis. We compare the performance of this algorithm against two variants, one using the difference image intensity as the motion features and another using higher-order moments. The proposed algorithm and its variants are tested using field test data of a group 3 UAV acquired with a panoramic video camera in the visible spectrum. The performance of the algorithms was evaluated using receiver operating characteristic curves. The results show that the proposed approach had the best performance compared to the two algorithmic variants.

We developed spatiotemporal fusion techniques for improving target detection and automatic target recognition. We also investigated real IR (infrared) sensor clutter noise. The sensor noise was collected by an IR (256 x 256) sensor looking at various scenes (trees, grass, roads, buildings, etc.). More than 95% of the sensor pixels showed near-stationary sensor clutter noise that was uncorrelated between pixels as well as across time frames. However, in a few pixels (covering the grass near the road) the sensor noise showed nonstationary properties (with increasing or decreasing mean across time frames). The natural noise extracted from the IR sensor, as well as the computer-generated noise with Gaussian and Rayleigh distributions, was used to test and compare different spatiotemporal fusion strategies. Finally, we proposed two advanced detection schemes: the double-thresholding the reverse-thresholding techniques. These techniques may be applied to complicated clutter situations (e.g., very-high clutter or nonstationary clutter situations) where the traditional constant-false-alarm-ratio technique may fail.

A pulsed dual-wavelength dual-CO2-laser differential-absorption lidar (DIAL) system has been developed which permits simultaneous heterodyne and direct detection of the same lidar returns. This system has been used to make an experimental comparison of the SNRs and statistical and temporal characteristics of the DIAL returns from several topographic targets. These results were found to be in general agreement with theory and were used to quantify the relative merits of the two detection techniques. The measured parameter values were applied to an analytical treatment to predict system trade-offs for the remote sensing of atmospheric species, with application to both path-averaged and range-resolved measurements.

The infrared emission limb sounder MIPAS (Michelson Interferometer for Passive Atmospheric Sounding) will be operated as an ESA core instrument on the ENVISAT-1 satellite. Near real time retrieval of pressure, temperature (p,T) and volume mixing ratio (VMR) of five key species (O-3, H2O, N2O, CH4, and HNO3) from calibrated spectra will be performed in the Level 2 processor of the ENVISAT Payload Data Segment. In order to develop an optimized (with respect to speed and accuracy) retrieval algorithm suitable for the implementation in MIPAS Level 2 processor, an ESA supported study is being carried out. In the framework of this study, an optimized forward / retrieval code based on the global fit approach was implemented. In this approach all the spectra of a limb-scanning sequence are simultaneously fitted, so that error propagation in the altitude domain is avoided.The attained accuracy performances of the retrieval code are the following:Temperature error < 2 K at all the altitudes covered by the standard MIPAS scan (8-53 km)Tangent pressure error: < 3%Error on the retrieved VMR of the key species: < 5 % at most of the altitudes of scientific interest covered by the standard MIPAS scan.The run-time required to perform p,T and VMR retrieval of the five MIPAS target species from a limb-scanning sequence of 16 limb-views is less than 6 minutes on a SUN SPARCstation 20. The most effective code optimizations were implemented in the radiative transfer model and in the computation of the jacobian of the retrieval.

This article deals with modelling the simultaneous uptake of water and highly buffered nutrient, such as phosphate, by root branching structures from partially saturated soil. We use the simultaneous water and nutrient uptake model to investigate the effect that water movement has on nutrient uptake. With the aid of this model we are also able to show that the previous models by Barber (Soil Nutrient Bioavailability. A Mechanistic Approach, Wiley-Interscience, New York) and Tinker and Nye (Solute Movement in the Rhizosphere, Oxford University Press, Oxford) systematically underestimated the phosphate uptake, due to the oversimplified approach in dealing with root branching structure. In this article we show how this discrepancy can be remedied and the root branching structure included in the models of plant nutrient uptake. We will also discuss the differences in the results for continuous and spot fertilization combined with variable rainfall.

Two contrasting models are proposed to account for an operator's performance during an insertion task using a teleoperated robot arm in which, in addition to haptic feedback, visual guidance is provided via a computer-generated display of the workspace. In the first model, the operator's internal aim is formulated as one of maximising the amount of information available, and in the second as one of minimising variance. Experimental measurements of the times to complete such a task are made, with various degrees of noise added to the pose of objects and different smoothing applied before generating the display. The observations appear inconsistent with the first performance model, suggesting that the operator prefers to use partial information rapidly, rather than to suffer the delay associated with extracting full information. The observations are more consistent with the operator as a minimiser of variance, an idea used successfully (albeit embodied in a different controller) by others in the modelling of human eye and arm trajectories, and in the prediction of the empirical Fitts' law found in reaching and touching tasks. It is found that under relatively high noise, the operator performs best when pose is low-pass-filtered with a cut-off frequency comparable with the natural frequency at which the operator interacts with the environment. © 2004 Elsevier B.V. All rights reserved.

Abstract The importance of measuring inequalities in sustainable development is reflected in the requirement to disaggregate national data for the Sustainable Development Goals (SDGs). In this paper, piped water access, water use and water stress are mapped and reported at national, provincial, district, municipal, town and ward levels, and urban and rural areas. The results show that although 45% of the population has water access in their dwelling this ranges from 0.07% to 100% at ward level, with a high level of inequality (Gini index of 0.36). National per capita water use is 208 litres per person per day (l/c/d) but ranges from 8 l/c/d to 2,414 l/c/d at town level, with a Gini index of 0.27. The analysis shows that social factors, such as water access and income, and not natural factors, such as rainfall or runoff, have the greatest influence on per capita water use. The paper provides the first in-depth analysis of per capita water use at the local level across South Africa and suggests new water indicators that could support equitable allocation of water resources and SDG reporting.