Inbreeding in the coffee berry borer, Hypothenemus hampei (Coleoptera : Scolytidae) estimated from endosulfan resistance phenotype frequencies

An estimate of the inbreeding coefficient, Fis, of the coffee berry borer, #Hypothenemus hampei Ferrari, was calculated from genotype frequencies of endosulfan resistance in beetles collected from berries in 41 fields on the East Coast of New Caledonia. Two different estimates were obtained as a function of sampling date : Fis = 0,491 + ou - 0,059 (s.e.) for samples collected in September, and Fis = 0,215 + ou - 0,108 for samples collected in April. These values of Fis are very high in comparison to those of more insects, but surprisingly low given current understandings of #H. hampei mating patterns. The difference between April and September Fis estimates is discussed in terms of insecticide regimes and seasonal variability of sib inbreeding levels. The high level of inbreeding in the coffee berry borer increases frequencies of homozygotes relative to heterozygotes. Inbreeding will accelerate resistance evolution whenever the fitness of homozygous resistant insects exceeds that of heterozygotes, and will undermine any high - dose strategy to control resistance evolution. (Résumé d'auteur

Mg-Ti-H thin films for smart solar collectors

Mg-Ti-H thin films are found to have very attractive optical properties: they absorb 87% of the solar radiation in the hydrogenated state and only 32% in the metallic state. Furthermore, in the absorbing state Mg-Ti-H has a low emissivity; at 400 K only 10% of blackbody radiation is emitted. The transition between both optical states is fast, robust, and reversible. The sum of these properties highlights the applicability of such materials as switchable smart coatings in solar collector

Past and present distribution, densities and movements of blue whales <i>Balaenoptera musculus</i> in the Southern Hemisphere and northern Indian Ocean

1Blue whale locations in the Southern Hemisphere and northern Indian Ocean were obtained from catches (303 239), sightings (4383 records of =8058 whales), strandings (103), Discovery marks (2191) and recoveries (95), and acoustic recordings.2Sighting surveys included 7 480 450 km of effort plus 14 676 days with unmeasured effort. Groups usually consisted of solitary whales (65.2%) or pairs (24.6%); larger feeding aggregations of unassociated individuals were only rarely observed. Sighting rates (groups per 1000 km from many platform types) varied by four orders of magnitude and were lowest in the waters of Brazil, South Africa, the eastern tropical Pacific, Antarctica and South Georgia; higher in the Subantarctic and Peru; and highest around Indonesia, Sri Lanka, Chile, southern Australia and south of Madagascar.3Blue whales avoid the oligotrophic central gyres of the Indian, Pacific and Atlantic Oceans, but are more common where phytoplankton densities are high, and where there are dynamic oceanographic processes like upwelling and frontal meandering.4Compared with historical catches, the Antarctic (‘true’) subspecies is exceedingly rare and usually concentrated closer to the summer pack ice. In summer they are found throughout the Antarctic; in winter they migrate to southern Africa (although recent sightings there are rare) and to other northerly locations (based on acoustics), although some overwinter in the Antarctic.5Pygmy blue whales are found around the Indian Ocean and from southern Australia to New Zealand. At least four groupings are evident: northern Indian Ocean, from Madagascar to the Subantarctic, Indonesia to western and southern Australia, and from New Zealand northwards to the equator. Sighting rates are typically much higher than for Antarctic blue whales.6South-east Pacific blue whales have a discrete distribution and high sighting rates compared with the Antarctic. Further work is needed to clarify their subspecific status given their distinctive genetics, acoustics and length frequencies.7Antarctic blue whales numbered 1700 (95% Bayesian interval 860–2900) in 1996 (less than 1% of original levels), but are increasing at 7.3% per annum (95% Bayesian interval 1.4–11.6%). The status of other populations in the Southern Hemisphere and northern Indian Ocean is unknown because few abundance estimates are available, but higher recent sighting rates suggest that they are less depleted than Antarctic blue whales.</li

Growth, structural and optical properties of Cu3N films

Thin films of C

Phase identification of iron nitrides and iron oxy-nitrides with Mossbauer spectroscopy

The Mössbauer spectroscopy of all known Fe nitrides is the topic of this paper. Most of the data were accumulated during a study of the growth of the various Fe nitride phases using molecular beam epitaxy of Fe in the presence of a flux of atomic N, or by post-nitriding freshly grown Fe layers also in a flux of atomic N. To get accurate data, most samples were grown with iron enriched in the isotope57Fe. Part of the samples were capped in the ultra-high vacuum (UHV) growth facility before exposure to air. By comparing MS data of samples which were capped with that of uncapped samples, we were able to measure the MS components due to oxidation of the nitrides. Also the oxidation behavior at elevated temperatures was studied. This led to a coherent description of the formation of oxy-nitrides as a function of temperature. The UHV conditions during growth and the capping of samples allowed us also to produce for the first time clean samples of Fe nitrides with a composition close to FeN. The phase formation in this composition range is extensively discussed. A fairly complete set of Mössbauer data for all Fe nitride phases and the phases occurring during their exposure to air is presented. This data set may serve to analyze samples of unknown composition, containing Fe nitrides

Development of epitaxial nitride-based bilayers for magnetic tunnel junctions

This paper reports on the growth and properties of bilayer structures consisting of insulating epitaxial Cu3N films grown on epitaxial ferromagnetic gamma'-Fe4N films. The interface between the layers is successfully probed with Mossbauer spectroscopy. In our fully epitaxial system, no intermixing occurs at the interface. Depending on the growth parameters (gas mixture, deposition temperature), the interface is also free of undesired nitride phases

On the growth of magnetic Fe4N films

Magnetic epitaxy films of Fe4N have been grown by molecular beam epitaxial in a flow of atomic nitrogen from a radio-frequency plasma source. Various mixtures of nitrogen and hydrogen have been used in the source during evaporation of Fe-57 on a MgO(1 0 0) substrate. The admixture of hydrogen leads to an increase of the uptake of nitrogen by iron and it improves the crystalline properties of the films grown. It was found that the increased nitrogen uptake is due to a higher fraction of atomic N in the output of the source plus transport system. The sticking coefficient of N atoms to an iron and a Fe4N surface was found to be equal to unity under the conditions we used. The composition and the morphology of the films was studied with conversion electron Mossbauer spectroscopy, X-ray diffraction, RBS/channeling and atomic force microscopy measurements. The results obtained clarify in part the growth mechanism of the iron nitride layers and the influence of hydrogen. (C) 2002 Elsevier Science B.V. All rights reserved