Light induced self-written waveguides interactions in photopolymer media

We present experimental and theoretical study of the interaction of Light Induced Self-Written (LISW) waveguides in photopolymers. We show that the diffusion of the monomer controls the refractive index distribution. Consequently it influences the interaction between the LISW channels allowing the observation of anti-crossing behavior or the propagation of an array of non interacting LISW waveguides

Polarization state studies in second harmonic generation signals to trace atherosclerosis lesions

We have performed multi-photon image reconstructions as well as polarization state analyses inside an artery wall affected by atherosclerosis to investigate the changes in collagen structure. Mice, either healthy or affected by spontaneous atherosclerosis, have been used for this purpose. A two-photon imaging system has been used to investigate atherosclerotic lesions in the ascending aorta of mice. Second harmonic imaging has been performed alternatively on healthy samples and on affected region. The reconstructed images show that the spatial distribution of the collagen network seems disorganized by the disease. The polarization state studies reveal however that the apparent disorganization of the collagen is related to its spatially diffuse distribution and that the internal structure of the collagen fibers is not affected by the disease. In addition, a theoretical simulation of the second harmonic polarization states shows that they are consistent with the known 3D structure of the collagen network

Solvent-free fluidic organic dye lasers

We report on the demonstration of liquid organic dye lasers based on 9-(2-ethylhexyl)carbazole (EHCz), so-called liquid carbazole, doped with green-and red-emitting laser dyes. Both waveguide and Fabry-Perot type microcavity fluidic organic dye lasers were prepared by capillary action under solvent-free conditions. Cascade Forster-type energy transfer processes from liquid carbazole to laser dyes were employed to achieve color-variable amplified spontaneous emission and lasing. Overall, this study provides the first step towards the development of solvent-free fluidic organic semiconducting lasers and demonstrates a new kind of optoelectronic applications for liquid organic semiconductors

The burden of neglected tropical diseases in Ethiopia, and opportunities for integrated control and elimination

Background: Neglected tropical diseases (NTDs) are a group of chronic parasitic diseases and related conditions that are the most common diseases among the 2·7 billion people globally living on less than US$2 per day. In response to the growing challenge of NTDs, Ethiopia is preparing to launch a NTD Master Plan. The purpose of this review is to underscore the burden of NTDs in Ethiopia, highlight the state of current interventions, and suggest ways forward. Results: This review indicates that NTDs are significant public health problems in Ethiopia. From the analysis reported here, Ethiopia stands out for having the largest number of NTD cases following Nigeria and the Democratic Republic of Congo. Ethiopia is estimated to have the highest burden of trachoma, podoconiosis and cutaneous leishmaniasis in sub-Saharan Africa (SSA), the second highest burden in terms of ascariasis, leprosy and visceral leishmaniasis, and the third highest burden of hookworm. Infections such as schistosomiasis, trichuriasis, lymphatic filariasis and rabies are also common. A third of Ethiopians are infected with ascariasis, one quarter is infected with trichuriasis and one in eight Ethiopians lives with hookworm or is infected with trachoma. However, despite these high burdens of infection, the control of most NTDs in Ethiopia is in its infancy. In terms of NTD control achievements, Ethiopia reached the leprosy elimination target of 1 case/10,000 population in 1999. No cases of human African trypanosomiasis have been reported since 1984. Guinea worm eradication is in its final phase. The Onchocerciasis Control Program has been making steady progress since 2001. A national blindness survey was conducted in 2006 and the trachoma program has kicked off in some regions. Lymphatic Filariasis, podoconiosis and rabies mapping are underway. Conclusion: Ethiopia bears a significant burden of NTDs compared to other SSA countries. To achieve success in integrated control of NTDs, integrated mapping, rapid scale up of interventions and operational research into co implementation of intervention packages will be crucial

The evolving SARS-CoV-2 epidemic in Africa: Insights from rapidly expanding genomic surveillance

INTRODUCTION Investment in Africa over the past year with regard to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) sequencing has led to a massive increase in the number of sequences, which, to date, exceeds 100,000 sequences generated to track the pandemic on the continent. These sequences have profoundly affected how public health officials in Africa have navigated the COVID-19 pandemic. RATIONALE We demonstrate how the first 100,000 SARS-CoV-2 sequences from Africa have helped monitor the epidemic on the continent, how genomic surveillance expanded over the course of the pandemic, and how we adapted our sequencing methods to deal with an evolving virus. Finally, we also examine how viral lineages have spread across the continent in a phylogeographic framework to gain insights into the underlying temporal and spatial transmission dynamics for several variants of concern (VOCs). RESULTS Our results indicate that the number of countries in Africa that can sequence the virus within their own borders is growing and that this is coupled with a shorter turnaround time from the time of sampling to sequence submission. Ongoing evolution necessitated the continual updating of primer sets, and, as a result, eight primer sets were designed in tandem with viral evolution and used to ensure effective sequencing of the virus. The pandemic unfolded through multiple waves of infection that were each driven by distinct genetic lineages, with B.1-like ancestral strains associated with the first pandemic wave of infections in 2020. Successive waves on the continent were fueled by different VOCs, with Alpha and Beta cocirculating in distinct spatial patterns during the second wave and Delta and Omicron affecting the whole continent during the third and fourth waves, respectively. Phylogeographic reconstruction points toward distinct differences in viral importation and exportation patterns associated with the Alpha, Beta, Delta, and Omicron variants and subvariants, when considering both Africa versus the rest of the world and viral dissemination within the continent. Our epidemiological and phylogenetic inferences therefore underscore the heterogeneous nature of the pandemic on the continent and highlight key insights and challenges, for instance, recognizing the limitations of low testing proportions. We also highlight the early warning capacity that genomic surveillance in Africa has had for the rest of the world with the detection of new lineages and variants, the most recent being the characterization of various Omicron subvariants. CONCLUSION Sustained investment for diagnostics and genomic surveillance in Africa is needed as the virus continues to evolve. This is important not only to help combat SARS-CoV-2 on the continent but also because it can be used as a platform to help address the many emerging and reemerging infectious disease threats in Africa. In particular, capacity building for local sequencing within countries or within the continent should be prioritized because this is generally associated with shorter turnaround times, providing the most benefit to local public health authorities tasked with pandemic response and mitigation and allowing for the fastest reaction to localized outbreaks. These investments are crucial for pandemic preparedness and response and will serve the health of the continent well into the 21st century

Contrôle de l'indice de réfraction dans des matériaux photopolymérisables pour la formation de guides (2 + \,+\,1) D

La possibilité d'inscrire des circuits optiques dans des matériaux photopolymérisables offre des perspectives d'applications multiples très stimulantes. C'est ainsi que la propriété particulière “d'auto-développement” des guides optiques créés dans ces matériaux permet de réaliser des structures guidantes sans recours à des techniques sophistiquées comme la microlithographie. Cependant, l'absence de connaissance de l'évolution de la valeur de l'indice de réfraction du système en cours de polymérisation constituait jusqu'alors un obstacle de taille dans la maîtrise de l'élaboration de guides photoinduits. Nous avons résolu ce problème et nous pouvons à présent modéliser numériquement l'évolution des guides en fonction de l'intensité lumineuse excitatrice et réaliser expérimentalement des guides permanents dans des composés photopolymérisables

Profil de l’hemogramme au cours de l’acces palustre simple a Plasmodium falciparum chez les enfants de 6 mois a 5 ans au Togo.

Objectifs : Cette étude avait pour but de décrire l’hémogramme au cours l’accès palustre simple à Plasmodium falciparum. Patients et méthodes : Une NFS a été réalisée chez 267 enfants âgés de moins de 5ans dans deux villes à faciès épidémiologique différent au Togo d’août à décembre 2007. Résultats : Le taux d’hémoglobine moyen était de 10,0±2,4g/dl. L’anémie notée chez 71,9% des enfants (n=192) était hypochrome normocytaire et hypochrome microcytaire respectivement dans 27,3% (n=73) et 31,8% (n=85) des cas. Le nombre moyen de plaquettes était de 162468±94700 plaquettes/mm3. La thrombopénie a été notée chez 42,7% des enfants inclus (n=114). La leucocytose moyenne était de 9014±4163 leucocytes/mm3. La leucopénie et l’hyperleucocytose ont été retrouvées respectivement dans 0,7% et 9,7% des cas. Le nombre moyen des polynucléaires neutrophiles était de 5416±3154 PNN/mm3. La neutropénie et la polynucléose neutrophile étaient retrouvées dans respectivement 4,1% (n=11) et 24,7% des cas (n=66). La lymphocytose moyenne était de 3453±2249 lymphocytes/mm3 ; on notait 15,4% de lymphopénie (n=41) et 9,4% d’hyperlymphocytose (n=25). Le nombre de PNE, de PNB et des monocytes était normal chez la presque totalité des enfants avec des moyennes respectives de 115/mm3, 0,2/mm3 et 29/mm3. La densité parasitaire était faiblement corrélée avec la leucocytose (p=0,042) et négativement avec le taux d’hémoglobine (p=0,015) et le nombre de plaquettes (p=0,031). Conclusion : Le paludisme à Plasmodium falciparum est cause d’anémie et de thrombopénie chez l’enfant.Mots clés: enfant, hémogramme, paludisme, pédiatrie