Déformation et métamorphisme dans la partie centrale de la chaine de Ngovayang (Sud-Cameroun)

La chaine de Ngovayang fait partie des formations tectoniques majeures de l’unité du Nyong au sud du Cameroun. Son histoire tectonique est caractérisée par trois phases de déformation qui se sont développées de l’archéen au début du panafricain. La phase D1 est responsable du plissement P1 et de la foliation S1. La phase D2, considérée comme phase majeure de déformation, est syntectonique. Elle a mis en place une schistosité S2 globalement NE-SW à pendage NW, plan axial des plis P2 et porteuse d’une linéation L2. Quant à la déformation D3, elle est assez tardive et discontinue. La principale empreinte métamorphique est liée à la phase de déformation D2, caractérisée par un métamorphisme de haut degré (faciès des amphibolites supérieures au faciès des granulites).Mots-clés : phase de déformation, chaine de Ngovayang, tectonique, métamorphisme, Nyong, Cameroun.Deformation and metamorphism in the central part of the Ngovayang chain (SouthCameroon)The Ngovayang chain forms part of the major tectonic unit of the Nyong Series in southern Cameroon. Its tectonic history is characterized by three phases of deformation that developed during the Archean to early Panafrican period. The D1 phase is responsible for the S1 foliation and the P1 fold. Phase D2, considered as the major phase of deformation, is syntectonic. It generated an S2 schistosity with a general NE-SW direction and NW dip. The S2 schistosity has a fold axial plane P2 and bears a lineation L2. The D3 deformation on the other hand is post tectonic and discontinuous. The main metamorphic imprint is related to the D2 deformation phase, characterized by a high grade of metamorphism (upper amphibolites to granulite facies).Keywords : deformation phase, Ngovayang chain, tectonic, metamorphism, Nyong, Cameroon

Errors in quantum optimal control and strategy for the search of easily implementable control pulses

We introduce a new approach to assess the error of control problems we aim to optimize. The method offers a strategy to define new control pulses that are not necessarily optimal but still able to yield an error not larger than some fixed a priori threshold, and therefore provide control pulses that might be more amenable for an experimental implementation. The formalism is applied to an exactly solvable model and to the Landau-Zener model, whose optimal control problem is solvable only numerically. The presented method is of importance for applications where a high degree of controllability of the dynamics of quantum systems is required.Comment: 13 pages, 3 figure

A mid-infrared Mueller ellipsometer with pseudo-achromatic optical elements

The purpose of this article is to present a new broadband Mueller ellipsometer designed to work in the mid-infrared range, from 3 to 14 microns. The Mueller ellipsometer, which can be mounted in reflection or in transmission configuration, consists of a polarization state generator (PSG), a sample holder, and a polarization state analyzer (PSA). The PSG consists in one linear polarizer and a retarder sequentially rotated to generate a set of four optimal polarization states. The retarder consists in a bi-prism made of two identical Fresnel rhombs disposed symmetrically and joined by optical contact, giving the ensemble a "V" shape. Retardation is induced by the four total internal reflections that the beam undergoes when it propagates through the bi-prism. Total internal reflection allows to generate a quasi-achromatic retardation. The PSA is identical to the PSG, but with its optical elements mounted in reverse order. After a measurement run, the instrument yields a set of sixteen independent values, which is the minimum amount of data required to calculate the Mueller matrix of the sample. The design of the Mueller ellipsometer is based on the optimization of an objective criterion that allows minimizing the propagation of errors from raw data to the Mueller matrix of the sample. The pseudo-achromatic optical elements ensure a homogeneous quality of the measurements for all wavelengths. The performance of the Mueller ellipsometer in terms of precision, and accuracy, is discussed and illustrated with a few examples

Spatial Division Multiplexing for Multiplex Coherent Anti-Stokes Raman Scattering

We demonstrate how a narrowband pump and a broadband spectrum can be spatially multiplexed by selective coupling them in two distinct modes of a few-mode microstructure fiber. The first mode carries most of the input pump energy, and experiences spectral broadening. Whereas the second mode preserves the narrow bandwidth of the remaining part of the pump. Bimodal propagation, with a power unbalance strongly in favor of the fundamental mode, is naturally obtained by maximizing coupling into the fundamental mode of the fiber. At the fiber output, the nearly monochromatic beam and the supercontinuum carried by the two different modes are combined by a microscope objective, and used as a pump and a Stokes wave for self-referenced multiplex coherent anti-Stokes Raman scattering micro-spectroscopy. The spectral resolution, the signal-to-noise-ratio, and the possible amplification of the remaining pump beam are discussed.Comment: 10 pages, 9 figure

Designing and implementing interventions to change clinicians' practice in the management of uncomplicated malaria: lessons from Cameroon.

BACKGROUND: Effective case management of uncomplicated malaria is a fundamental pillar of malaria control. Little is known about the various steps in designing interventions to accompany the roll out of rapid diagnostic tests (RDTs) and artemisinin-based combination therapy (ACT). This study documents the process of designing and implementing interventions to change clinicians' practice in the management of uncomplicated malaria. METHODS: A literature review combined with formative quantitative and qualitative research were carried out to determine patterns of malaria diagnosis and treatment and to understand how malaria and its treatment are enacted by clinicians. These findings were used, alongside a comprehensive review of previous interventions, to identify possible strategies for changing the behaviour of clinicians when diagnosing and treating uncomplicated malaria. These strategies were discussed with ministry of health representatives and other stakeholders. Two intervention packages - a basic and an enhanced training were outlined, together with logic model to show how each was hypothesized to increase testing for malaria, improve adherence to test results and increase appropriate use of ACT. The basic training targeted clinicians' knowledge of malaria diagnosis, rapid diagnostic testing and malaria treatment. The enhanced training included additional modules on adapting to change, professionalism and communicating effectively. Modules were delivered using small-group work, card games, drama and role play. Interventions were piloted, adapted and trainers were trained before final implementation. RESULTS: Ninety-six clinicians from 37 health facilities in Bamenda and Yaounde sites attended either 1-day basic or 3-day enhanced training. The trained clinicians then trained 632 of their peers at their health facilities. Evaluation of the training revealed that 68% of participants receiving the basic and 92% of those receiving the enhanced training strongly agreed that it is not appropriate to prescribe anti-malarials to a patient if they have a negative RDT result. CONCLUSION: Formative research was an important first step, and it was valuable to engage stakeholders early in the process. A logic model and literature reviews were useful to identify key elements and mechanisms for behaviour change intervention. An iterative process with feedback loops allowed appropriate development and implementation of the intervention. TRIAL REGISTRATION: ClinicalTrials.gov: NCT01350752

Universities and community-based research in developing countries: community voice and educational provision in rural Tanzania

The main focus of recent research on the community engagement role of universities has been in developed countries, generally in towns and cities and usually conducted from the perspectives of universities rather than the communities with which they engage. The purpose of this paper is to investigate the community engagement role of universities in the rural areas of developing countries, and its potential for strengthening the voice of rural communities. The particular focus is on the provision of primary and secondary education. The paper is based on the assumption that in order for community members to have both the capacity and the confidence to engage in political discourse for improving educational capacity and quality, they need the opportunity to become involved and well-versed in the options available, beyond their own experience. Particular attention is given in the paper to community-based research (CBR). CBR is explored from the perspectives of community members and local leaders in the government-community partnerships which have responsibility for the provision of primary and secondary education in rural Tanzania. The historical and policy background of the partnerships, together with findings from two case studies, provide the context for the paper

MycoRRdb: A Database of Computationally Identified Regulatory Regions within Intergenic Sequences in Mycobacterial Genomes

The identification of regulatory regions for a gene is an important step towards deciphering the gene regulation. Regulatory regions tend to be conserved under evolution that facilitates the application of comparative genomics to identify such regions. The present study is an attempt to make use of this attribute to identify regulatory regions in the Mycobacterium species followed by the development of a database, MycoRRdb. It consist the regulatory regions identified within the intergenic distances of 25 mycobacterial species. MycoRRdb allows to retrieve the identified intergenic regulatory elements in the mycobacterial genomes. In addition to the predicted motifs, it also allows user to retrieve the Reciprocal Best BLAST Hits across the mycobacterial genomes. It is a useful resource to understand the transcriptional regulatory mechanism of mycobacterial species. This database is first of its kind which specifically addresses cis-regulatory regions and also comprehensive to the mycobacterial species. Database URL: http://mycorrdb.uohbif.in

Emerging viral threats in Gabon: health capacities and response to the risk of emerging zoonotic diseases in Central Africa

Emerging infectious diseases (EID) are currently the major threat to public health worldwide and most EID events have involved zoonotic infectious agents. Central Africa in general and Gabon in particular are privileged areas for the emergence of zoonotic EIDs. Indeed, human incursions in Gabonese forests for exploitation purposes lead to intensified contacts between humans and wildlife thus generating an increased risk of emergence of zoonotic diseases. In Gabon, 51 endemic or potential endemic viral infectious diseases have been reported. Among them, 22 are of zoonotic origin and involve 12 families of viruses. The most notorious are dengue, yellow fever, ebola, marburg, Rift Valley fever and chikungunya viruses. Potential EID due to wildlife in Gabon are thereby plentiful and need to be inventoried. The Gabonese Public Health system covers geographically most of the country allowing a good access to sanitary information and efficient monitoring of emerging diseases. However, access to treatment and prevention is better in urban areas where medical structures are more developed and financial means are concentrated even though the population is equally distributed between urban and rural areas. In spite of this, Gabon could be a good field for investigating the emergence or re-emergence of zoonotic EID. Indeed Gabonese health research structures such as CIRMF, advantageously located, offer high quality researchers and facilities that study pathogens and wildlife ecology, aiming toward a better understanding of the contact and transmission mechanisms of new pathogens from wildlife to human, the emergence of zoonotic EID and the breaking of species barriers by pathogens

Safety and immunogenicity of radiation-attenuated PfSPZ vaccine in equatoguinean infants, children, and adults

The radiation-attenuated Plasmodium falciparum sporozoites (PfSPZ) Vaccine has demonstrated safety and immunogenicity in 5-month-old to 50-year-old Africans in multiple trials. Except for one, each trial has restricted enrollment to either infants and children or adults /= 0.17). There were no significant differences between vaccinees and controls with respect to the rates or severity of unsolicited AEs or laboratory abnormalities. Development of antibodies to P. falciparum circumsporozoite protein occurred in 67/69 vaccinees (97%) and 0/15 controls. Median antibody levels were highest in infants and 1-5-year-olds and declined progressively with age. Antibody responses in children were greater than in adults protected against controlled human malaria infection. Robust immunogenicity, combined with a benign AE profile, indicates children are an ideal target for immunization with PfSPZ Vaccine

Neonatal mortality: an invisible and marginalised trauma

Neonatal mortality is a major health problem in low and middle income countries and the rate of improvement of newborn survival is slow. This article is a review of the PhD thesis by Mats Målqvist, titled ‘Who can save the unseen – Studies on neonatal mortality in Quang Ninh province, Vietnam,’ from Uppsala University. The thesis aims to investigate structural barriers to newborn health improvements and determinants of neonatal death. The findings reveal a severe under-reporting of neonatal deaths in the official health statistics in Quang Ninh province in northern Vietnam. The neonatal mortality rate (NMR) found was four times higher than what was reported to the Ministry of Health. This underestimation of the problem inhibits adequate interventions and efforts to improve the survival of newborns and highlights the invisibility of this vulnerable group