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Search Results: 1 - 10 of 187 matches for " Demba Ndao Niang "
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Intra-Seasonal and Annual Variation of Aerosols and Their Radiative Impact in the Sahelian Zone of Burkina Faso  [PDF]
Bado Nébon, Mamadou Simina Dramé, Saidou Moustapha Sall, Korgo Bruno, Demba Ndao Niang, Kieno P. Florent, Bathiebo Dieudonné Joseph
Atmospheric and Climate Sciences (ACS) , 2019, DOI: 10.4236/acs.2019.91004
Abstract: This paper deals with the characterization of aerosols in the Sahelian zone, particularly in Burkina Faso based on MODIS observations and in situ measurements of the AERONET network on the Ouagadougou site (12.2°N, 1.4°W). Thus, a seasonal spatial distribution of aerosols made over the period from 2001 to 2016 gives a very great variability of aerosols in Burkina Faso, whose maxima are encountered in Spring, characterized by winds from the North East. This seasonality of aerosols is also shown by the annual cycles of optical, radiative and microphysical parameters measured by AERONET between 1999 and 2006. Moreover, an analysis of these parameters shows the prevalence of mineral dusts characterized by low values of the Angstrom coefficient (α440-870 < 0.5) associated with the maxima of AOT with high intensity in March. These dusts are confirmed by their scattering nature (SSA > 0.9) and the cooling noticed in the bottom of atmosphere (BOA) and at the top of the atmosphere (TOA). Also, the climatology of the volume size distribution of aerosols shows a very great variability of particles in terms of size influenced by the thin and coarse pattern where most sizes are between 1 and 10 μm.
Chronic infection during placental malaria is associated with up-regulation of cycloxygenase-2
Demba Sarr, Delphine Aldebert, Laurence Marrama, Emilie Frealle, Alioune Gaye, Hamoud O Brahim, Makhtar Niang, Jean Dangou, Odile Mercereau-Puijalon, Jean Lehesran, Ronan Jambou
Malaria Journal , 2010, DOI: 10.1186/1475-2875-9-45
Abstract: Placental biopsies were collected at delivery for mRNA isolation and quantification, using real time PCR.COX-2 and IL-10 mRNAs increased mainly during chronic infections (nine- and five-times, respectively), whereas COX-1 transcripts remained constant. COX-2 over-expression was associated with a higher birth weight of the baby, but with a lower rate of haemoglobin of the mother. It was associated with a macrophage infiltration of the placenta and with a low haemozoin infiltration. In the opposite way, placental infection was associated with lower expression of 15-LOX mRNA. A high degree of haemozoin deposition correlates with low birth weight and decreased expression of COX-2.These data provide evidence that COX-2 and IL-10 are highly induced during chronic infection of the placenta, but were not associated with preterm delivery or low birth weight. The data support the involvement of COX-2 in the recovery phase of the placental infection.In Africa, most of the malaria mortality and morbidity is borne by children and pregnant women with an estimate 200,000 infant deaths each year as a result of malaria infection in pregnancy [1]. During placental malaria (PM) parasites accumulate in the placenta with an increased risk of low birth weight (LBW) [2]. This accumulation can be related to low blood flow through the placenta and to specific adhesion of infected red blood cells (IRBCs) on syncytiotrophoblast. This adhesion is mediated by chondroitin sulphate A and specific var antigens. Monocytes also accumulate in the intervillous space of the placenta [3] mostly attracted by release of MIF [4,5]. Pro-inflammatory cytokine release also associates with this accumulation of parasites, pigment, and monocytes in the tissue [6,7].Decreased blood flow in the placenta is the major factor triggering LBW, which had previously been linked to a modulation of placental cytokine expression [7]. In this context, prostaglandins (PGs) are important modulators of vascular perfusion and fe
Diagnosis of Parasitic Diseases: Old and New Approaches
Momar Ndao
Interdisciplinary Perspectives on Infectious Diseases , 2009, DOI: 10.1155/2009/278246
Abstract: Methods for the diagnosis of infectious diseases have stagnated in the last 20–30 years. Few major advances in clinical diagnostic testing have been made since the introduction of PCR, although new technologies are being investigated. Many tests that form the backbone of the “modern” microbiology laboratory are based on very old and labour-intensive technologies such as microscopy for malaria. Pressing needs include more rapid tests without sacrificing sensitivity, value-added tests, and point-of-care tests for both high- and low-resource settings. In recent years, research has been focused on alternative methods to improve the diagnosis of parasitic diseases. These include immunoassays, molecular-based approaches, and proteomics using mass spectrometry platforms technology. This review summarizes the progress in new approaches in parasite diagnosis and discusses some of the merits and disadvantages of these tests.
Assessment of Trade Potential of Senegal and Morocco  [PDF]
Birahim Bouna Niang
Modern Economy (ME) , 2016, DOI: 10.4236/me.2016.71004
Abstract: Senegal and Morocco have significant advantages to develop bilateral trade. Trade between the two countries is in favor of Morocco. The estimation of the trade potential of the two countries based on an augmented gravity model reveals that this potential is underexploited vis-à-vis African trade partners and other parts of the World (Europe, Asia, and Latin America). The trade performances of Senegal and Morocco should be improved through the implementation of a supply policy and targeted support to exporting firms.
AN ALGORITHMIC APPROACH TO DATABASE NORMALIZATION
M. Demba
International Journal of Digital Information and Wireless Communications , 2013,
Abstract: When an attempt is made to modify tables that have not been sufficiently normalized undesirable side-effects may follow. This can be further specified as an update, insertion or deletion anomaly depending on whether the action that causes the error is a row update, insertion or deletion respectively. Most of the recent works on database normalization use a restricted definition of normal forms where only the primary key is taken into account and ignoring the rest of candidate keys. In this paper, we propose an algorithmic approach for database normalization up to third normal form by taking into account all candidate keys, including the primary key. The effectiveness of the proposed approach is evaluated on many real world examples.
Decomposable and Indecomposable Algebras of Degree 8 and Exponent 2
Demba Barry
Mathematics , 2013,
Abstract: We study the decomposition of central simple algebras of exponent 2 into tensor products of quaternion algebras. We consider in particular decompositions in which one of the quaternion algebras contains a given quadratic extension. Let $B$ be a biquaternion algebra over $F(\sqrt{a})$ with trivial corestriction. A degree 3 cohomological invariant is defined and we show that it determines whether $B$ has a descent to $F$. This invariant is used to give examples of indecomposable algebras of degree 8 and exponent 2 over a field of 2-cohomological dimension 3 and over a field $\mathbb M(t)$ where the $u$-invariant of $\mathbb M$ is 8 and $t$ is an indeterminate. The construction of these indecomposable algebras uses Chow group computations provided by A. S. Merkurjev in Appendix.
Involutions on tensor products of quaternion algebras
Demba Barry
Mathematics , 2015,
Abstract: We study possible decompositions of totally decomposable algebras with involution, that is, tensor products of quaternion algebras with involution. In particular, we are interested in decompositions in which one or several factors are the split quaternion algebra $M_2(F)$, endowed with an orthogonal involution. Using the theory of gauges, developed by Tignol-Wadsworth, we construct examples of algebras isomorphic to a tensor product of quaternion algebras with $k$ split factors, endowed with an involution which is totally decomposable, but does not admit any decomposition with $k$ factors $M_2(F)$ with involution. This extends an earlier result of Sivatski where the algebra considered is of degree $8$ and index $4$, and endowed with some orthogonal involution.
Power-Central Elements in Tensor Products of Symbol Algebras
Demba Barry
Mathematics , 2013,
Abstract: Let A be a central simple algebra over a field F. Let k_1,\ldots, k_r be cyclic extensions of F such that k_1\otimes_F\cdots \otimes_F k_r is a field. We investigate conditions under which A is a tensor product of symbol algebras where each k_i is in a symbol F-algebra factor of the same degree as k_i. As an application, we give an example of an indecomposable algebra of degree 8 and exponent 2 over a field of 2-cohomological dimension 4.
Evaluation of the Prognostic Value of IFN-γ Release Assay and Tuberculin Skin Test in Household Contacts of Infectious Tuberculosis Cases in Senegal
Christian Lienhardt,Katherine Fielding,Abdoul A. Hane,Aliou Niang,Cheikh T. Ndao,Farba Karam,Helen Fletcher,Fatou Mbow,Jules-Fran?ois Gomis,Roger Diadhiou,Maxime Toupane,Tandakha Dieye,Souleymane Mboup
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0010508
Abstract: Chemoprophylaxis of contacts of infectious tuberculosis (TB) cases is recommended for TB control, particularly in endemic countries, but is hampered by the difficulty to diagnose latent TB infection (LTBI), classically assessed through response to the Tuberculin Skin Test (TST). Interferon-gamma release assays (IGRA) are proposed new tools to diagnose LTBI, but there are limited data on their ability to predict the development of active TB disease. To address this, we investigated the response to TST and IGRA in household contacts of infectious TB cases in a TB high-burden country and the potential correlation with development of TB.
Les associations en milieu urbain dakarois: classification et capacités développantes
Abdoulaye Niang
Africa Development , 2000,
Abstract: In Senegal, urban associations are extremely evolutionary in concept and practice and pervade every aspect of urban space. They shift and adjust, in both their forms and objectives, to the social and institutional demands of their ever-changing environment, as well as to the new opportunities provided by same. Urban associations in Senegal offer solutions that increasingly meet individual and collective needs, which makes them appear as efficient local development tools, especially when members and communities strongly identify themselves with their native homeland. Résumé Les associations en milieu urbain sont évolutives et manifestent une grande tendance à la totalisation : leurs formes et leurs objectifs changent pour s'adapter aux exigences sociales et institutionnelles de leur environnement en constante transformation, ainsi qu'aux opportunités nouvelles que celui-ci leur offre. De ce point de vue, les associations offrent des solutions de plus en plus en adéquation avec les besoins individuels et collectifs, ce qui fait d'elles des instruments efficaces du développement local surtout si les membres et la collectivité s'identifient fortement à leur terroir. (Africa Development: 2000 25(1&2): 99-160)
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