Mutational analysis-inspired algorithms for cells self-organization towards a dynamic under viability constraints

International audienceIn biology, recent techniques in confocal mi- croscopy have produced experimental data which highlights the importance of cellular dynamics in the evolution of biolog- ical shapes. Thus, to understand the mechanisms underlying the morphogenesis of multi-cellular organisms, we study this cellular dynamic system in terms of its properties: cell multi- plication, cell migration, and apoptosis. Besides, understanding the convergence of the system toward a stable form, involves local interactions between cells. Indeed, the way that cells self- organize through these interactions determines the resulting form. Along with the mechanisms of convergence highlighted above, the dynamic system also undergoes controls established by the nature on the organisms growth. Hence, to let the system viable, the global behavior of cells has to be assessed at every state of their developement and must satisfy the constraints. Otherwise, the whole system self-adapts in regard to its global behavior. Thus, we must be able to formalize in a proper metric space a metaphor of cell dynamics in order to find conditions (decisions, states) that would make cells to self-organize and in which cells self-adapt so as to always satisfy operational constraints (such as those induced by the tissue or the use of resources). Therefore, the main point remains to find conditions in which the system is viable and maintains its shape while renewing. The aim of this paper is to explain the mathematical foundations of this work and describe a simulation tool to study the morphogenesis of a virtual organism

Génératrice à réluctance variable connectée au réseau alternatif monophasé pour une application éolienne

Nous avons présenté dans ce travail le contrôle de la Génératrice à Réluctance Variable (GRV) connectée au réseau alternatif monophasé pour une application éolienne. La régulation de la vitesse de rotation est assurée par le convertisseur coté génératrice et le couple est imposé par la machine à courant continu utilisée ici pour simuler la turbine éolienne. La connexion de la génératrice au réseau est réalisée par un convertisseur DC-AC qui assure le maintien de la tension du bus DC par un correcteur PI. Un correcteur résonant est utilisé pour suivre la consigne de courant sinusoïdale.Peer ReviewedPostprint (published version

Characterization of strains of Aspergillus flavus and A. parasiticus isolated from groundnut (Arachis hypogea), rice (Oryza sativa) and maize (Zea mays) in Senegal

The contamination of certain food crop with aflatoxin poses a real public health problem for consumers and causes many market losses for exporters. Thus, several research works are oriented in the direction of developing methods to combat aflatoxinogenic fungus. This study aimed at identifying and characterizing strains of Aspergillus flavus and A. parasiticus on groundnut, maize and rice seeds grown or imported into Senegal. Four species (A. niger, A. tamarii, A. flavus and A. parasiticus) were isolated from the seeds with incidences ranging from 0 to 100% depending on the samples and their provenance. Six strains of A. flavus and 3 strains of A. parasiticus have been identified and characterized on CYA and G25N culture media. The characterization focused on the morphological characteristics (color and appearance, mycelial growth) of the colonies on the different culture media, and on some microscopic characteristics such as the density of sporulation (production of conidia) and the appearance of the conidiophore. Strains of A. flavus were more frequent on groundnuts and isolates with the same traits were also identified from rice and maize samples, hence the 3 strains of A. parasiticus were isolated

Mesure de l’efficacité technique des riziculteurs du bassin du fleuve Sénégal

Ce travail a pour objectif de mesurer l’efficacité technique des riziculteurs du bassin du fleuve Sénégal et d’analyser les déterminants de leur inefficacité. Les estimations ont montré que, s’il avait été efficace, le riziculteur moyen aurait pu accroître sa production actuelle de 30 % sans inputs additionnels, contre une marge de progrès potentielle de 86 % pour le riziculteur le moins performant. Les facteurs qui impactent significativement l’efficacité sont le lieu de résidence, le genre, la taille du ménage, le niveau d’instruction, l’ethnie, la distance entre la maison et la parcelle, et le nombre de parcelles cultivées.This article aims at investigating whether rice producers in Senegal have reached their maximal production regarding their available inputs and what are the determinants of their inefficiency. The estimations show that, if he were efficient, the mean producer would increase his actual output by 30% without further inputs while the less performant producer would record a potential margin of progress of 86%. The efficiency determinants are mainly the place of residence, the gender, the household size, the level of education, the ethnicity, the walking distance between the house and the plot and the number of plots farmed

Evaluation of determinants of the use of health mutuals by the population of the Ziguinchor region in Senegal

Access to health services is a concern around the world. Different strategies were developed, but Africa’s rate remains the lowest. This article aims to contribute to the population's access to healthcare, and to assess the determinants of the use of mutual health insurance by the population of the Ziguinchor region in Senegal.    Methods: The study is transversal and descriptive, carried out from July to August 2018. Through the quota method we defined the number of patients to be interviewed. Thus, by a geographic stratification according to the departments and a second-degree stratification taking into account the staff of the different hospital departments, 392 patients were selected.   Results: 73% at the Regional Hospital Center and 27% at the Regional Peace Hospital. Response rate: 97%, women 60% and men 40%. The enrollment for women (24%) is slightly higher than that for men (21%). Socio-economic factors. The rate of adherence is the highest of for patients with university level, followed by high school; income:  the highest rate for patients with a monthly income between 200,000 and 500,000 FCFA, followed by patients with an income monthly between 100,000 and 200,000 FCFA. Factors linked to the provision of care: the rate of Mutual Health Insurance adherence follows distances from patients' homes. Concerning the relation to satisfaction, education, distance and information are more determining than adherence rate.    Recommendations: 1) State: actions on education and distance; 2) Sensitizing the population on mutual health insurance; 3) Urging healthcare providers to reduce waiting times and respect schedules as well as appointments.&nbsp

Long-Term Intrapatient Evolution During HIV-2 Infection

HIV-2 disease progression and transmission is attenuated compared to HIV-1, yet prospective studies examining HIV-2 intrapatient evolution have been limited. We examined viral sequence evolution in the C2V3C3 region of the viral env gene in 8 HIV-2 infected individuals from Dakar, Senegal, over the course of approximately 10 years. To compare results to HIV-1 infection, we reanalyzed data from our previous study that examined intrapatient evolution in HIV-1 infected individuals from the same population. HIV-2 sequences from early and late timepoints were phylogenetically intermixed for all subjects, and no distinct trends were observed in terms of increases or decreases in fragment size or number of N-linked glycosylation sites. In homologous env C2V3 sequence, rates of viral divergence and diversification were slower in individuals infected with HIV-2 than individuals with HIV-1. This data indicates that viral evolution occurs slowly in HIV-2 infection, which is consistent with the slow disease progression observed in HIV-2 infection, and supports the notion that viral evolution may be a relevant correlate for disease progression

An Exhaustive, Non-Euclidean, Non-Parametric Data Mining Tool for Unraveling the Complexity of Biological Systems – Novel Insights into Malaria

Complex, high-dimensional data sets pose significant analytical challenges in the post-genomic era. Such data sets are not exclusive to genetic analyses and are also pertinent to epidemiology. There has been considerable effort to develop hypothesis-free data mining and machine learning methodologies. However, current methodologies lack exhaustivity and general applicability. Here we use a novel non-parametric, non-euclidean data mining tool, HyperCube®, to explore exhaustively a complex epidemiological malaria data set by searching for over density of events in m-dimensional space. Hotspots of over density correspond to strings of variables, rules, that determine, in this case, the occurrence of Plasmodium falciparum clinical malaria episodes. The data set contained 46,837 outcome events from 1,653 individuals and 34 explanatory variables. The best predictive rule contained 1,689 events from 148 individuals and was defined as: individuals present during 1992–2003, aged 1–5 years old, having hemoglobin AA, and having had previous Plasmodium malariae malaria parasite infection ≤10 times. These individuals had 3.71 times more P. falciparum clinical malaria episodes than the general population. We validated the rule in two different cohorts. We compared and contrasted the HyperCube® rule with the rules using variables identified by both traditional statistical methods and non-parametric regression tree methods. In addition, we tried all possible sub-stratified quantitative variables. No other model with equal or greater representativity gave a higher Relative Risk. Although three of the four variables in the rule were intuitive, the effect of number of P. malariae episodes was not. HyperCube® efficiently sub-stratified quantitative variables to optimize the rule and was able to identify interactions among the variables, tasks not easy to perform using standard data mining methods. Search of local over density in m-dimensional space, explained by easily interpretable rules, is thus seemingly ideal for generating hypotheses for large datasets to unravel the complexity inherent in biological systems

Cancer de la prostate au Centre Hospitalier Universitaire Aristidie Le Dantec de Dakar : aspects épidemiologiques sur les cinq dernières années: Prostate cancer in Aristide Le Dantec hospital of Dakar: epidemiological aspects over the last five years

Context and objective. Prostate cancer represents a major public health issue, but data from sub-Saharan Africa are scarce. This study aimed to describe the epidemiological aspects of prostate cancer during the last five years in Aristide Le Decantec hospital of Dakar. Methods. it’s a retrospective and descriptive study involving 5 last years including all patients with histologically confirmed prostate cancer. The studied parameters were: prevalence, incidence, age, clinical stage, lethality and death rate. Results. Two hundred and thirty-three patients were enrolled. The prevalence of prostate cancer during the study period was 0.8%. Depending on the stage, metastatic cancer was the most common form with 45.9% of cases. The new cases were 199 with an average of 39.8 per year. The total incidence of prostate cancer over the study period was 0.7%. The mean age of the patients at the diagnosis time was 68.6 ± 9.2 years. The lethality was 0.5%. The global death rate was 0.9 ‰. The specific death rate was 0.9‰. The annual mortality rate was higher in 2017 (36.4%) compared to other years. Depending on the stage, the death rate was higher in metastatic stages patients. Conclusion. The incidence of prostate cancer is increasing in our medical center. Metastatic forms remain more common with higher death rate. Early detection campaigns for prostate cancer should be considered. Contexte et objectif. Le cancer de la prostate représente un enjeu majeur de santé publique et mais il reste très peu documenté en Afrique subsaharienne. L’objectif de cette étude était d’évaluer les aspects épidémiologiques du cancer de la prostate sur les 5 dernières années dans notre centre. Méthodes. Il s’agissait d’une étude documentaire et descriptive sur 5 ans ayant colligé les dossiers de tous les patients avec cancer de la prostate histologiquement confirmé. Les paramètres étudiés étaient : la prévalence, l’incidence, l’âge, le stade clinique, la létalité et la mortalité. Résultats. Deux cent trente-trois patients ont été retenus. La prévalence du cancer de la prostate durant la période étudiée était de 0,8%. En fonction du stade, le stade de cancer métastatique était prépondérant (45,9%). Les nouveaux cas étaient de 199, soit une moyenne de 39,8 nouveaux cas par an. L’incidence totale du cancer de la prostate sur la période étudiée était de 0,7%. L’âge moyen des patients au moment du diagnostic était de 68,6 ± 9,2 ans. Le taux létalité était de 0,5%. La mortalité globale était de 0,9‰. Le taux de mortalité annuelle était plus important en 2017 (36,4%) en comparaison aux autres années étudiées. En fonction du stade, le taux de mortalité était plus important pour les stades métastatiques. Conclusion. L’incidence du cancer de la prostate est en augmentation dans notre centre. Les formes métastatiques restent prédominantes assombrissant le pronostic vital. Des campagnes de dépistage précoce du cancer de la prostate sont à envisager