Étude de la variabilité agromorphologique de la collection nationale de mils locaux du Sénégal

Objectif : Le mil est la première culture vivrière au Sénégal. Il joue un rôle capital dans la vie des populations rurales qui en dépendent pour leur survie (STAT/FAO/SENEGAL, 2010). Il est cultivé sur plus 60% des terres arables. Les variétés locales étaient les plus utilisées mais depuis quelques années leur survie est menacée par l'introduction des variétés améliorées.Methodology et application des résultats : Pour éviter l'érosion génétique, des missions de collecte ont été organisées en 1994 et 2006 dans les principales zones de culture du mil. Le matériel collecté est caractérisé pour faciliter leur utilisation dans les programmes de création variétale. L'objectif du présent travail est caractériser le germoplasme national mil du Sénégal pour les rendre utilisables par les sélectionneurs pour la création de nouvelles variétés hautement productives pour l'augmentation de la production céréalière et l'atteinte de la sécurité alimentaire. Pour caractériser les accessions, 12 variables sélectionnées à partir du Descripteur du mil IPGRI/ICRISAT, 1993 ont été utilisées. Un dispositif expérimental en blocs complets randomisés avec 3 répétitions a été choisi et les sites d'essais étaient Bambey, Nioro et Darou pendant les hivernages 2011 et 2012. Les analyses descriptives ou qualitatives ; statistiques simples (ANOVA) ; de la diversité (phénologique ; génétique avec la méthode de la classification ascendante (CAH), avec les composantes principales (ACP) et l'analyse factorielle discriminante (AFD)) ont été réalisées avec les logiciels Genstat Discovery4 et R. Les analyses descriptives ont montré l'existence d'une grande variabilité entre les accessions pour les caractères qualitatifs comme l'architecture de l'épi et la couleur des grains. Les analyses statistiques simples (ANOVA) ont montré qu'il existe une différence hautement significative entre les entrées et les sites. Cependant, les interactions étaient non significatives à l'exception de la floraison, de l'indice de récolte et des rendements en grains et en matière sèche. Les analyses de la diversité phénologique a permis de classer les variétés en trois groupes selon le cycle végétatif (G1 des variétés extra-précoces, G2 des cycles courts et G3 des cycles longs). La classification ascendante hiérarchique (CAH) suivant la méthode de Ward a permis d'identifier la valeur des axes et les compositions des 3 groupes y découlant (le groupe G1 compte 106 accessions, le G2 compte 129 accessions et le G3 compte 8 accessions) et de tracer le dendrogramme de filiations. L'analyse de la diversité génétique par les composantes principales (ACP) a permis de déterminer la position des accessions par rapport aux axes expliquant les variabilités inter-accessions. L'analyse de la diversité génétique par la méthode factorielle discriminante a permis de déterminer la structuration de la diversité agromorphologique et la représentation graphique des accessions suivant un plan factoriel. Les groupes ainsi formés seront convertis en des entités hétérotiques constituées de pools de gènes différents où les sélectionneurs et autres scientifiques vont puiser pour créer des variétés hautement productives et résistantes aux stress bio et abiotiques afin de nourrir les populations et de lutter contre la faim et la malnutrition

Quantifying Stock Price Response to Demand Fluctuations

We address the question of how stock prices respond to changes in demand. We quantify the relations between price change $G$ over a time interval $\Delta t$ and two different measures of demand fluctuations: (a) $\Phi$, defined as the difference between the number of buyer-initiated and seller-initiated trades, and (b) $\Omega$, defined as the difference in number of shares traded in buyer and seller initiated trades. We find that the conditional expectations $<G >_{\Omega}$ and $_{\Phi}$ of price change for a given $\Omega$ or $\Phi$ are both concave. We find that large price fluctuations occur when demand is very small --- a fact which is reminiscent of large fluctuations that occur at critical points in spin systems, where the divergent nature of the response function leads to large fluctuations.Comment: 4 pages (multicol fomat, revtex

Effect of the Equivalence Between Topological and Electric Charge on the Magnetization of the Hall Ferromagnet

The dependence on temperature of the spin magnetization of a two-dimensional electron gas at filling factor unity is studied. Using classical Monte Carlo simulations we analyze the effect that the equivalence between topological and electrical charge has on the the behavior of the magnetization. We find that at intermediate temperatures the spin polarization increases in a thirty per cent due to the Hartree interaction between charge fluctuations.Comment: 4 pages. Submitted to Phys.Rev.

Role of bound pairs in the optical properties of highly excited semiconductors: a self consistent ladder approximation approach

Presence of bound pairs (excitons) in a low-temperature electron-hole plasma is accounted for by including correlation between fermions at the ladder level. Using a simplified one-dimensional model with on-site Coulomb interaction, we calculate the one-particle self-energies, chemical potential, and optical response. The results are compared to those obtained in the Born approximation, which does not account for bound pairs. In the self-consistent ladder approximation the self-energy and spectral function show a characteristic correlation peak at the exciton energy for low temperature and density. In this regime the Born approximation overestimates the chemical potential. Provided the appropriate vertex correction in the interaction with the photon is included, both ladder and Born approximations reproduce the excitonic and free pair optical absorption at low density, and the disappearance of the exciton absorption peak at larger density. However, lineshapes and energy shifts with density of the absorption and photoluminescence peaks are drastically different. In particular, the photoluminescence emission peak is much more stable in the ladder approximation. At low temperature and density a sizeable optical gain is produced in both approximations just below the excitonic peak, however this gain shows unphysical features in the Born approximation. We conclude that at low density and temperature it is fundamental to take into account the existence of bound pairs in the electron-hole plasma for the calculation of its optical and thermodynamic properties. Other approximations that fail to do so are intrinsically unphysical in this regime, and for example are not suitable to address the problem of excitonic lasing.Comment: 14 pages, 12 figure

Understanding Interpretations of and Responses to Childhood Fever in the Chikhwawa District of Malawi

Background Universal access to, and community uptake of malaria prevention and treatment strategies are critical to achieving current targets for malaria reduction. Each step in the treatment-seeking pathway must be considered in order to establish where opportunities for successful engagement and treatment occur. We describe local classifications of childhood febrile illnesses, present an overview of treatment-seeking, beginning with recognition of illness, and suggest how interventions could be used to target the barriers experienced. Methods Qualitative data were collected between September 2010 and February 2011. A total of 12 Focus Group Discussions and 22 Critical Incident Interviews were conducted with primary caregivers who had reported a recent febrile episode for one of their children. Findings and Conclusion The phrase ‘kutentha thupi’, or ‘hot body’ was used to describe fever, the most frequently mentioned causes of which were malungo (translated as ‘malaria’), mauka, nyankhwa and (m)tsempho. Differentiating the cause was challenging because these illnesses were described as having many similar non-specific symptoms, despite considerable differences in the perceived mechanisms of illness. Malungo was widely understood to be caused by mosquitoes. Commonly described symptoms included: fever, weakness, vomiting, diarrhoea and coughing. These symptoms matched well with the biomedical definition of malaria, although they also overlapped with symptoms of other illnesses in both the biomedical model and local illness classifications. In addition, malungo was used interchangeably to describe malaria and fever in general. Caregivers engaged in a three-phased approach to treatment seeking. Phase 1—Assessment; Phase 2—Seeking care outside the home; Phase 3—Evaluation of treatment response. Within this paper, the three-phased approach is explored to identify potential interventions to target barriers to appropriate treatment. Community engagement and health promotion, the provision of antimalarials at community level and better training health workers in the causes and treatment of non-malarial febrile illnesses may improve access to appropriate treatment and outcomes

Assessment of the genetic diversity and pattern of relationship of West African sorghum accessions using microsatellite markers

An understanding of the extent, distribution and patterns of genetic variation is useful for estimation of any possible loss of genetic diversity and assessment of genetic variability and its potential use in breeding programs, including establishment of heterotic groups. This study assessed patterns of genetic diversity and relationships among 30 West African sorghum accessions using 22 microsatellite markers. Population structure and within population genetic diversity was also assessed using the same markers. Genotypic data was generated using the ABI Prism 3730 and alleles called and sized using genemapper software version 3.7. Molecular data was analyzed using DARwin 4.0, powermarker 3.0 and Arlequin version 3.11. The average marker quality index was 0.27 while a mean PIC of 0.54 was observed across the 22 SSR markers. Among the 30 accessions, the markers detect a total of 146 alleles with an average of 6.6 alleles per marker. Results from the various statistical analyses performed revealed a wide range of polymorphism from 22.7 to 86.4%. The mean heterozygosity was relatively low at 0.28 while the average Nei’s genetic diversity among the 30 populations was 0.57. The within population Nei’s genetic diversity assessed from 49 individuals in 10 populations was lower at 0.54 and the average heterozygosity was also lower at 0.21. Cluster and principal coordinate analysis of the 30 populations revealed two distinct groups independent of their geographic origins The examination of the hierarchical partitioning of genetic variation by AMOVA demonstrated that genetic differentiation was significant at P &lt; 0.00. Of the total diversity, 8.9% was attributed to country differences, 54.11% was attributed to population differences within the countries while 36.99% was attributed to differences within populations. The FST value (0.63) indicated a very high genetic differentiation as expected for selfing species. This study demonstrates the utility of SSR markers in detecting polymorphism, estimating genetic diversity and establishment of genetic clusters for heterotic studies.Keywords: Genetic diversity, heterozygosity, SSR microsatellites, heterotic grouping, alleles, polymorphismAfrican Journal of Biotechnology, Vol 13(14), 1503-151

Religion and health care in east africa: Lessons from uganda, mozambique and ethiopia

What social factors contribute to the tragic state of health care in Africa? Focusing on East African societies, this book is the first to investigate what role religion plays in health care in African cultures. Taking into account the geopolitical and economic environments of the region, the authors examine the roles played by individual and group beliefs, government policies, and pressure from the Millennium Development Goals in affecting health outcomes. Informed by existing related studies, and on-the-ground interviews with individuals and organizations in Uganda, Mozambique and Ethiopia, this interdisciplinary book will form an invaluable resource for scholars seeking to better understand the links between society, multi-level state instruments, and health care in East Africa

Assessment of the genetic diversity and pattern of relationship of West African sorghum accessions using microsatellite markers

An understanding of the extent, distribution and patterns of genetic variation is useful for estimation of any possible loss of genetic diversity and assessment of genetic variability and its potential use in breeding programs, including establishment of heterotic groups. This study assessed patterns of genetic diversity and relationships among 30 West African sorghum accessions using 22 microsatellite markers. Population structure and within population genetic diversity was also assessed using the same markers. Genotypic data was generated using the ABI Prism 3730 and alleles called and sized using genemapper software version 3.7. Molecular data was analyzed using DARwin 4.0, powermarker 3.0 and Ariequin version 3.11. The average marker quality index was 0.27 while a mean PIC of 0.54 was observed across the 22 SSR markers. Among the 30 accessions, the markers detect a total of 146 alleles with an average of 6.6 alleles per marker. Results from the various statistical analyses performed revealed a wide the average Nei's genetic diversity among the 30 population was lower at 0.54 and the average heterozygosity was also lower at 0.21. Cluster and principal cooridinate analysis of the 30 populations revealed two distinct groups independent of their geographic origins The examination of the hierarchical partitioning of genetic variation by AMOVA demonstrated that genetic differentiation was siginficant at P<0.00. Of the total diversity, 8.9% was attributed to country difference, 54.11% was attributed to population differences within the countries while 36.99% was attributed to differences within populations. The Fst value (0.63) indicated a very high genetic differentiation as expected for selfing species. This study demonstrates the utility of SSR markers in detecting polymorphism, estimating genetic diversity and establishment of genetic clusters for heterotic studie