Local Extinction in the Bird Assemblage in the Greater Beijing Area from 1877 to 2006

Recent growth in industrialization and the modernization of agricultural activities, combined with human population growth, has greatly modified China’s natural environment, particularly in the vicinity of large cities. We compared avifauna checklists made between 1877 and 1938 with current checklists to determine the extent of local bird extinctions during the last century in the greater Beijing area. Our study shows that of the 411 bird species recorded from 1877–1938, 45 (10.9%) were no longer recorded from 2004–2006. Birds recorded as ‘rare’ in 1938 were more likely to have disappeared in subsequent years. Migrant status also influenced the probability of local bird extinction with winter migrants being the most affected class. Moreover, larger birds were more likely to have disappeared than smaller ones, potentially explained by differential ecological requirements and anthropogenic exploitation. Although our habitat descriptions and diet classification were not predictors of local bird extinction, the ecological processes driving local bird extinction are discussed in the light of historical changes that have impacted this region since the end of the 1930 s. Our results are of importance to the broader conservation of bird wildlife

Genomic architecture and introgression shape a butterfly radiation

We use twenty de novo genome assemblies to probe the speciation history and architecture of gene flow in rapidly radiating Heliconius butterflies. Our tests to distinguish incomplete lineage sorting from introgression indicate that gene flow has obscured several ancient phylogenetic relationships in this group over large swathes of the genome. Introgressed loci are underrepresented in low recombination and gene-rich regions, consistent with the purging of foreign alleles more tightly linked to incompatibility loci. We identify a hitherto unknown inversion that traps a color pattern switch locus. We infer that this inversion was transferred between lineages via introgression and is convergent with a similar rearrangement in another part of the genus. These multiple de novo genome sequences enable improved understanding of the importance of introgression and selective processes in adaptive radiation

The diversity and evolution of pollination systems in large plant clades: Apocynaceae as a case study

Background and Aims Large clades of angiosperms are often characterized by diverse interactions with pollinators, but how these pollination systems are structured phylogenetically and biogeographically is still uncertain for most families. Apocynaceae is a clade of >5300 species with a worldwide distribution. A database representing >10 % of species in the family was used to explore the diversity of pollinators and evolutionary shifts in pollination systems across major clades and regions. Methods The database was compiled from published and unpublished reports. Plants were categorized into broad pollination systems and then subdivided to include bimodal systems. These were mapped against the five major divisions of the family, and against the smaller clades. Finally, pollination systems were mapped onto a phylogenetic reconstruction that included those species for which sequence data are available, and transition rates between pollination systems were calculated. Key Results Most Apocynaceae are insect pollinated with few records of bird pollination. Almost three-quarters of species are pollinated by a single higher taxon (e.g. flies or moths); 7 % have bimodal pollination systems, whilst the remaining approx. 20 % are insect generalists. The less phenotypically specialized flowers of the Rauvolfioids are pollinated by a more restricted set of pollinators than are more complex flowers within the Apocynoids + Periplocoideae + Secamonoideae + Asclepiadoideae (APSA) clade. Certain combinations of bimodal pollination systems are more common than others. Some pollination systems are missing from particular regions, whilst others are over-represented. Conclusions Within Apocynaceae, interactions with pollinators are highly structured both phylogenetically and biogeographically. Variation in transition rates between pollination systems suggest constraints on their evolution, whereas regional differences point to environmental effects such as filtering of certain pollinators from habitats. This is the most extensive analysis of its type so far attempted and gives important insights into the diversity and evolution of pollination systems in large clades

A Novel 5-GHz SPDT Switch Using Semiconductor Distributed Doped Areas

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Novel Method Based on Spin-Coating for the Preparation of 2D and 3D Si-Based Anodes for Lithium Ion Batteries

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Switchable DBR Filters Using Semiconductor Distributed Doped Areas (ScDDAs)

International audienceThis paper presents a novel way to switch dual-behavior resonator (DBR) filters without any additional active surface-mount components. By using a semiconductor substrate, we were able to simultaneously co-design the filters and semiconductor distributed doped areas (ScDDAs) with integrated N + PP + junctions as active elements. These ScDDAs act as electrical vias in the substrate, which makes it possible to have an open-circuited resonator in the OFF state and a short-circuited resonator in the ON state, and, consequently, to control the transmission zeroes of the filters. This method offers degrees of freedom as the dimensions and positions of these doped areas can be chosen to obtain the best performances. In this study, four filters were simulated and fabricated to spotlight different possibilities for the dimensions and positions of the ScDDA to control the lowor high-frequency transmission zero of the filters. The simulations were in very good agreement with the measured results. All the filters present insertion losses lower than 2 dB in the OFF and ON states, a great flexibility in the frequency choice, and good agility compared with the state of the art

Hydrostratigraphic characterization of glaciofluvial deposits underlying an infiltration basin using ground penetrating radar.

14 pagesInternational audienceAn understanding of the heterogeneity of quaternary gravelly deposits is required to predict flow and contaminant transfer through these formations. In such deposits, preferential flow paths can lead to contamination at depths greater than predicted under the assumption of a homogeneous medium. The difficulties in characterizing their complex structure with conventional methods represent an obstacle for this prediction. In this study, we developed an approach relying on the use of ground penetrating radar (GPR) for the detection of sedimentary depositional units. A genetic interpretation of the radar stratigraphy allowed us to construct a distribution model of lithofacies. The study was conducted on glaciofluvial deposits underlying a stormwater infiltration basin. Two main system tracts were characterized: a top stratum (50–80 cm deep) corresponding to massive gravel and open-framework gravel, and a base stratum corresponding to trough-fill structures with associated sandy, open-framework, massive, and matrix-rich gravelly lithofacies. The knowledge of the hydraulic properties linked to each lithofacies led us to propose a hydrostratigraphic model. Based on this model, we formulated a hypothesis about the hydraulic behavior of the deposit during stormwater infiltration. Open-framework gravels can act, during complete saturation, as preferential flow paths, and capillary barrier effects may occur under variably saturated conditions. These hypotheses were tested by measuring water content variations (using time domain reflectometry probes) at three depths (0, −0.5, and −1.15 m). Experimental data show infiltration behavior that can be explained by a capillary barrier effect between the two lower probes. These results suggest that our hypothesis about hydraulic behavior is reasonable

Intégration de zones dopées distribuées pour la réalisation d’un Switch SPDT à 5 GHz

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Intégration de zones dopées distribuées pour la réalisation d'un switch SPDT à 5 GHz

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