Lack of assortative mating might explain reduced phenotypic differentiation where two grasshopper species meet

Hybridization is an evolutionary process with wide-ranging potential outcomes, from providing populations with important genetic variation for adaptation to being a substantial fitness cost leading to extinction. Here, we focussed on putative hybridization between two morphologically distinct species of New Zealand grasshopper. We collected Phaulacridium marginale and Phaulacridium otagoense specimens from a region where mitochondrial introgression had been detected and where their habitat has been modified by introduced mammals eating the natural vegetation and by the colonization of many non-native plant species. In contrast to observations in the 1970s, our sampling of wild pairs of grasshoppers in copula provided no evidence of assortative mating with respect to species. Geometric morphometrics on pronotum shape of individuals from areas of sympatry detected phenotypically intermediate specimens (putative hybrids), and the distribution of phenotypes in most areas of sympatry was found to be unimodal. These results suggest that hybridization associated with anthropogenic habitat changes has led to these closely related species forming a hybrid swarm, with random mating. Without evidence of hybrid disadvantage, we suggest a novel hybrid lineage might eventually result from the merging of these two species.fals

Development and Simulation of a Structure Based on CuIn1-xGaxSe2 Semiconductors Alloys for a New Generation of Photovoltaic Cells

AbstractThe aim of our study is the development and simulation of thin films structure based on CuIn1-xGaxSe2 semiconductors alloys to improve the conversion efficiency of solar cells. We studied and simulated the variation effect of the Gallium concentration on some physical and electrical properties (lattice parameter, strain, energy gap, refractive index, absorption coefficient and J (V) characteristic), this in order to optimize the best possible performances for solar cells. Then, we studied the influence of surface state density and temperature on solar devices characteristics. For better performance of our structure based on CuIn1-xGaxSe2, the concentration of gallium must be less than 40% and this to avoid the lattice mismatch with CdS buffer layer. We have demonstrated by simulation models the possibility for efficiency to reach 22% in the case of CuIn1-xGaxSe2 thin films solar cells

Design and Simulation of Cd1-xZnxTe Thin Films Epitaxied on CdTe Substrate for Photovoltaic Devices Applications

AbstractThis work concerns the study and the simulation of a structure containing II-VI semiconductor for photovoltaic application. We studied the influence of the zinc concentration on the various parameters of the alloy Cd1-xZnxTe epitaxied on a CdTe substrate. Indeed, the insertion of zinc increases the band gap of the alloy, which is not ideal to absorb the maximum of the solar spectrum, but for low concentrations of zinc the Cd1-xZnxTe ternary material becomes attractive in the photovoltaic field. We have shown that for a Zinc composition (x) = 5%, the band gap is 1.52eV. And if x = 20%, the gap is 1.62eV.Our simulation studies have demonstrated that by an introduction of a specific Zinc concentration, we successfully simulated the achieving of 19% efficiency for solar devices

Study of Graded Ultrathin CIGS/Si Structure for Solar Cell Applications

International audienceThis paper aims to improve the performance of graded ultrathin CIGS-based solar cells using the one-dimensional simulation program (SCAPS-1D). In this context, we have assessed the effect of the graded bandgap and the thickness of the absorber layer (CIGS) on solar cell performance. We have also examined the impact of different graded bandgap profiles by varying the gallium concentration. Notably, the increase of the gallium concentration (xGa) and the CIGS thickness (dCIGS) have degraded the conversion efficiency η. The optimization of these parameters gives a considerable solar yield when dCIGS = 1 μm and xGa in the range 0.1–0.3. For the graded cell, we have mentioned that the double-graded profile improves significantly the conversion efficiency up to 22.21% compared to the uniform profile with η = 21.43%

Continuously variable phase-shift for phase array antennas

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Intérêt d'un anneau hybride dans la réalisation d'un déphaseur variable, commandé optiquement

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