Anticorrelation between Ion Acceleration and Nonlinear Coherent Structures from Laser-Underdense Plasma Interaction

In laser-plasma experiments, we observed that ion acceleration from the Coulomb explosion of the plasma channel bored by the laser, is prevented when multiple plasma instabilities such as filamentation and hosing, and nonlinear coherent structures (vortices/post-solitons) appear in the wake of an ultrashort laser pulse. The tailoring of the longitudinal plasma density ramp allows us to control the onset of these insabilities. We deduced that the laser pulse is depleted into these structures in our conditions, when a plasma at about 10% of the critical density exhibits a gradient on the order of 250 {\mu}m (gaussian fit), thus hindering the acceleration. A promising experimental setup with a long pulse is demonstrated enabling the excitation of an isolated coherent structure for polarimetric measurements and, in further perspectives, parametric studies of ion plasma acceleration efficiency.Comment: 4 pages, 5 figure

Cattle ticks population and prevalence of Babesia spp amongst it vector: Rhipicephalus (Boophilus) microplus in a zone of Ivory Coast

The aim of this survey is to evaluate prevalence of Babesia spp in Rhipicephalus (Boophilus) microplus and the importance of ticks species existing in Bingerville area. In this cross sectional study, thirty six cattlefrom 6 farms have been sampled in Bingerville area (Ivory coast Southeast). From 511 ticks collected, 102 Ambyomma spp (19.97%) and 409 Rhipicephalus (Boophilus) microplus (80.03%) were identified. Then, theprevalence of Babesia spp parasites amongst Rhipicephalus (Boophilus) microplus was focused. With 120 engorged females of Rhipicephalus (Boophilus) microplus, 24 pools of 5 ticks each were done. The Giemsastain test had shown prevalences of 8.33% and 1.73% of Babesia spp respectively in pool and individual levels

Récente recomposition des populations de tiques prévalent en Côte d’Ivoire

Une étude transversale a été conduite dans 5 villes des régions centre, est, ouest et nord de la Côte d’Ivoire au cours des mois de septembre, octobre et novembre 2011. Le but était de savoir si Rhipicephalus (Boophilus) microplus était présente dans d’autres régions hormis le  sud-ouest, et la nouvelle composition des populations de tiques infestant les bovins dans ces régions. Au cours de cette étude, des tiques ont été récoltées sur un échantillon de 6 animaux dans chacun des 25 élevages répartis dans les quatre régions : centre, ouest, est et nord. Six espèces de tiques appartenant à trois genres ont été identifiées. Ce sont: Amblyomma variegatum (toutes les régions) ; Rhipicephalus (Boophilus) microplus (toutes les régions), Rhipicephalus (Boophilus) decoloratus(région est seulement), Hyalomma truncatum (régions nord, est et ouest), Rhipicephalus sanguineus (centre et nord) et Rhipicephalus senegalensis (région centre seulement). L’espèce la plus dominante, observée pendant la période d’étude, a été Rhipicephalus (Boophilus) microplus. En effet, elle est non seulement présente dans toutes les régions, mais aussi  majoritaire. La répartition géographique de ces espèces de tiques,  parasites des bovins, a donc été établie.Mots clés : Tiques, bovin, régions, Côte d’Ivoire

Investigation of rodent reservoirs of emerging pathogens in Côte d'Ivoire, West Africa

Background: One of the main health problems in West Africa remains upsurge of emerging pathogens. Ebola virus disease outbreak occurred in 2014 in Liberia, Guinea and Sierra Leone, Monkeypox virus in Nigeria in 2017 and most recently Lassa virus in Nigeria, Togo and Benin in 2018.  These pathogens have animal reservoirs as vectors for transmission. Proper investigation of the pathogens in their rodent vectors could help  reduce and manage their emergence and spread. Methodology: This study was conducted with an approval from the Côte d’Ivoire Bioethics Community. Small mammal trappings were carried out in  9 sites within three zones namely, peri-urban, peri-rural and protected areas. Liver, lung and kidney tissues from trapped small mammals were  sampled in accordance with the recommended conditions of biosafety and bioethics. The organs were transported in liquid nitrogen to the  laboratory. Molecular tests were used to detect pathogens. Orthopoxviruses and Monkeypox virus were detected in the organs by PCR using  consensus primers targeting the virus surface membrane haemagglutinin (HA) genes, while Leptospira species were detected by PCR using primers  targeting the rrs and lfb1 genes. Results: Out of 4930 night-traps, 256 (5.19%) small mammals were trapped including Crocidura, Rattus, Lophuromys, Praomys, Mus and Mastomys.  Leptospira species were detected in 6 genera from 7 study sites and the infected small mammals accounted for 13.3%. Leptospira sp was detected  mainly in the rodent vector genera Rattus (32.3%), Lophuromys (29.0%), and Praomys (16.1%). Three species of Leptospira were detected and  Leptospira interrogans was the most common frequent species (74.2%). Monkeypox virus was not detected from studied small mammals. Conclusion: The initial data from our investigation indicates the presence of Leptospira sp in rodent vectors, Rattus, Lophuromys and Praomys,  which are the potential small mammalian reservoirs of this pathogen in Cote d’Ivoire

A bremsstrahlung gamma-ray source based on stable ionization injection of electrons into a laser wakefield accelerator

Laser wakefield acceleration permits the generation of ultra-short, high-brightness relativistic electron beams on a millimeter scale. While those features are of interest for many applications, the source remains constraint by the poor stability of the electron injection process. Here we present results on injection and acceleration of electrons in pure nitrogen and argon. We observe stable, continuous ionization-induced injection of electrons into the wakefield for laser powers exceeding a threshold of 7 TW. The beam charge scales approximately linear with the laser energy and is limited by beam loading. For 40 TW laser pulses we measure a maximum charge of almost 1 nC per shot, originating mostly from electrons of less than 10 MeV energy. The relatively low energy, the high charge and its stability make this source well-suited for applications such as non-destructive testing. Hence, we demonstrate the production of energetic radiation via bremsstrahlung conversion at 1 Hz repetition rate. In accordance with Geant4 Monte-Carlo simulations, we measure a gamma-ray source size of less than 100 microns for a 0.5 mm tantalum converter placed at 2 mm from the accelerator exit. Furthermore we present radiographs of image quality indicators

Two-Photon absorption cross-section measurement by thermal lens and nonlinear transmission methods in organic materials at 532 nm and 1064 nm laser excitations

Experimental results concerning two-photon absorption (TPA) cross-section measurement using nonlinear transmission (NLT) method and a new pump-probe mode-mismatched thermal lens (TL) scheme, in picosecond regime are reported. Both methods are used in a prospect of comparison. Values of the TPA coefficient and cross-section in three common solvents (Chloroform, Benzene and Nitrobenzene) and new synthesized perylenediimide derivatives (PDI) at 532nm and 1064nm wavelengths are given