Shady business: understanding the spatial ecology of exophilic Anopheles mosquitoes

Background: Understanding the ecology of exophilic anophelines is a key step toward developing outdoor control strategies to complement existing indoor control tools against malaria vectors. This study was conducted to assess the movement pattern of exophilic Anopheles mosquitoes between blood meal sources and resting habitats, and the landscape factors dictating their resting habitat choice. Results: Resting clay pots were placed at 5 m, 25 m, 50 m, 75 m and 100 m away from isolated focal houses, radiating from them in four directions. The locations of the clay pots represent heterogeneous land cover types at a relatively fine spatial scale in the landscape. The effect of the landscape characters on the number of both female and male anophelines caught was modelled using zero-inflated negative binomial regression with a log link function. A total of 420 Anopheles mosquitoes (353 females and 67 males) belonging to three species; Anopheles arabiensis, Anopheles pharoensis, and Anopheles tenebrosus were caught in the resting clay pots, with An. arabiensis being the dominant species. Canopy cover, distance from the house, and land cover type were the significant landscape characters influencing the aggregation of resting mosquitoes. Both the count and binary models showed that canopy cover was the strongest predictor variable on the counts and the presence of Anopheles mosquitoes in the clay pots. Female Anopheles were most frequently found resting in the pots placed in banana plantations, and at sampling points that were at the greater distances (75 m and 100 m) from the focal house. Conclusions: This study showed that exophilic Anopheles mosquitoes tend to rest in shaded areas some distance away from human habitation. These findings are important when targeting mosquitoes outdoors, complementing the existing effort being made to control malaria vectors indoors

Characterization of polycrystalline diamond films grown by Microwave Plasma Enhanced Chemical Vapor Deposition (MWPECVD) for UV radiation detection

Photodetectors based on polycrystalline diamond (PCD) films are of great interest to many researchers for the attractive electronic, mechanical, optical and thermal properties. PCD films are grown using the Microwave Plasma Enhanced Chemical Vapor Deposition (MWPECVD) method. First, we characterized films by means of structural and morphological analysis (Raman spectroscopy and scanning electron microscopy), then we evaporated a pattern of coplanar interdigitated Cr/Au contacts with an inter-electrode spacing of 100 mu m in order to perform the electrical characterization. We carried out measurements of dark current and impedance spectroscopy to investigate the film properties and conduction mechanisms of films and the effects of post-growth treatments. Finally we developed a charge sensing pre-amplifier to read-out the signal produced by UV photons in the detector. (C) 2009 Elsevier B.V. All rights reserved

Preliminary study on polycrystalline diamond films suitable for radiation detection

The microwave plasma enhanced chemical vapor deposition technique has been employed to grow polycrystalline diamond films on p-doped Si (100) substrates starting from highly diluted (1% CH 4 in H 2) gas mixtures. Coplanar interdigitated Cr/Au contacts have been thermally evaporated on two samples about 8 μm thick having different grain size. Dark current-voltage (I-V) measurements and impedance characterization have been found to be dependent on the grain size and on the quality of the examined samples