Données préliminaires sur l’écologie des chauves-souris frugivores de la commune du Plateau (Abidjan, Côte d’Ivoire)

La communauté de chauves-souris frugivores de la Commune du Plateau à Abidjan a été étudiée d’août 2005 à juillet 2006. Cette étude a été réalisée en procédant à des observations directes et des comptages aux pieds d’arbres en vue de connaître les espèces présentes, leur effectif et d’établir leur préférence d’habitat. Les résultats indiquent que cette commune héberge deux espèces de Mégachiroptères, la chauve-souris paillée, Eidolon helvum (Kerr, 1792) représentée par une très forte colonie et la chauve-souris à tête de marteau, Hypsignathus monstrosus H. Allen, 1861, observée pour la première fois et représentée par quelques individus. L’effectif de la population de chauves-souris paillées est en moyenne de 185 049 ± 1291,5 individus. Les effectifs ont varié selon le site et la saison. Les chauves-souris paillées ont une préférence d’habitat marquée pour les sites dortoirs à Mangifera indica L. (Anacardiaceae).Mots clés : Chauves-souris frugivores, inventaire, habitat, milieu urbain

A Compact Dual-Band Notch Antenna for Wireless Multistandard Terminals

International audienceA compact planar dual-band notch antenna for wireless multistandard handset terminals is designed and experimentally demonstrated. The design technique is detailed first in the ideal case of a notch antenna loaded with a lumped capacitance and fed through an ideal matching network. Next, the implementation on an FR4 substrate with a finite ground plane compatible with a handset is presented. The simulated and experimental performances demonstrate a dual-band response (815-1010 and 1680-3600 MHz) corresponding to the main cellular and short-range standards (GSM-900, DCS-1800, IMT-2000, LTE, WiFi-802.11b/g/n , and WiMAX) with a total efficiency greater than 60%

Enhanced-efficiency front-end module with multi-standard impedance-tunable antenna

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Q-factor investigation of antennas over metamaterials substrates

International audienceIn this article, antennas over metamaterials substrates are investigated with the radiating Q factor determined by using a time‐domain method.The main objective is to illustrate the electromagnetic behavior of this kind of complex structure by calculating its energy budget (stored and radiated energies). An example of a patch antenna using such materials is analyzed and experimental results are presented

Entomological drivers of uneven malaria transmission in urban lowland areas in Bouaké, Côte d’Ivoire

Abstract Background The use of urban lowlands for agriculture contributes to the food security of city- dwellers, but promotes malaria transmission. The objective of the study was to characterize the entomological drivers of malaria transmission in two lowlands (N’Gattakro and Odiennekourani) in the city of Bouaké, Côte d’Ivoire. Methods The human landing catch technique was used to capture mosquitoes in houses located at the edge of two lowlands in Bouaké from February to December 2019. Cultivated surfaces were calculated monthly in both lowlands for each crop type (rice and market gardening) using images acquired by a drone. The different mosquito species were identified morphologically and by PCR analysis for the Anopheles gambiae complex. Anopheles infection by Plasmodium parasites was assessed by quantitative PCR. Mosquito diversity, biting behaviour and rhythmicity, and malaria transmission were determined in each lowland and compared. Results Anopheles gambiae sensu lato (s.l.) was predominant in N’Gattakro and Culex quinquefasciatus in Odiennekourani. Four Anopheles species were identified: An. gambiae s.l. and Anopheles funestus s.l. in both lowlands, Anopheles pharoensis in N’Gattakro, and Anopheles ziemanni in Odiennekourani. Within the An. gambiae complex, three species were caught: An. gambiae sensu stricto (s.s.), Anopheles coluzzii, and Anopheles arabiensis for the first time in Côte d’Ivoire (30.1%, 69.9% and 0% in N’Gattakro, and 45.1%, 52.6% and 2.4% in Odiennekourani, respectively). Anopheles gambiae s.l. species exhibited a significant exophagic behaviour in N’Gattakro (77.1% of outdoor bites versus 52.2% in Odiennekourani). In N’Gattakro, 12.6% of captures occurred before bedtime (09.00 pm) and after waking up (05.00 am), 15.1% in Odiennekourani. The mean human biting rate was higher in N’Gattakro than in Odiennekourani (61.6 versus 15.5 bites per person per night). Overall, Anopheles infection rate was 0.68%, with 0.539 and 0.029 infected bites per person per night in N’Gattakro and Odiennekourani, respectively. Conclusion The risk of malaria in urban agricultural lowland areas is uneven. The role of agricultural developments and irrigation patterns in the production of larval habitat should be explored. The exophagic behaviour of Anopheles vectors raises the question of the residual transmission that needs to be assessed to implement appropriate control strategies

Polymer (PDMS-Fe3O4) magneto-dielectric substrate for a MIMO antenna array

This paper presents the design of a 2 × 4 multiple-input multiple-output (MIMO) antenna array fabricated on a nanocomposite magneto-dielectric polymer substrate. The 10-nm iron oxide (Fe3O4) nanoparticles and polydimethylsiloxane (PDMS) composite is used as substrate to enhance the performance of a MIMO antenna array. The measured results showed up to 40.8 % enhancement in terms of bandwidth, 9.95 dB gain, and 57 % of radiation efficiency. Furthermore, it is found that the proposed magneto-dielectric (PDMS-Fe3O4) composite substrate provides excellent MIMO parameters such as correlation coefficient, diversity gain, and mutual coupling. The prototype of the proposed antenna is transparent, flexible, lightweight, and resistant against dust and corrosion. Measured results indicate that the proposed antenna is suitable for WLAN and ultra-wideband biomedical applications within frequency range of 5.33–7.70 GHz