Mateille T.,IRD Montpellier |
Dabire K.R.,Center Muraz |
Fould S.,British Petroleum |
Diop M.T.,University Of Thies
Soil Biology and Biochemistry | Year: 2010
Nematodes belonging to the genus Meloidogyne are the most ubiquitous and widespread plant-parasitic nematodes. They occur worldwide, are polyphagous and can parasitize most cultivated plants leading to reduced crop yields. They are especially harmful in developing countries because of the lack of suitable and feasible management strategies. Among all the control practices (chemicals, physical techniques, cultural practices, resistance), the use of natural enemies as biological control agents is the most recently developed. Pasteuria penetrans which is an obligate Gram-positive, endospore-forming bacterium, is perhaps the most promising plant-parasitic nematode biocontrol agent. Despite much research conducted on prey-predator interactions (host-parasite specificity, mechanisms of attachment, field efficacy), the influence of the soil environment on host-parasite interactions is poorly understood even when the soil appears to be the key factor. Beyond common studies on the influence of climatic conditions on the attachment of endospores of P. penetrans to nematodes, more knowledge about the systemic interactions between plants, soil water dynamics, soil texture and structure, and other biota on the parasitism of nematodes by P. penetrans would improve their utilization as biological control agents. The aim of this review is to analyze the literature dealing with the influence of the soil on nematode - P. penetrans interactions in order to suggest a helpful conceptual model based on partitioning the Pasteuria population in sub-populations according to their soil habitat (dispersible and non-dispersible aggregates, microporosity, macroporosity), not all of them being available for attachment and infection on nematodes. Such concerns should be taken into account by epidemiologists for improving biological management strategies based on the use of this bacterium. © 2010 Elsevier Ltd.
Lekpa F.K.,Center for Gerontology and Geriatrics |
Ndongo S.,Center for Gerontology and Geriatrics |
Ndongo S.,Cheikh Anta Diop University |
Ka O.,Center for Gerontology and Geriatrics |
And 6 more authors.
European Journal of Pain (United Kingdom) | Year: 2013
Data on characteristics of neuropathic pain (NP) in sub-Saharan Africa are scarce, especially in the elderly. We conducted this study to appreciate the socio-demographic and clinical profile of chronic pain (CP) with neuropathic characteristics in sub-Saharan African elderly with musculoskeletal pain. From January to December 2011, we performed a cross-sectional study in all Rheumatology outpatients over 60 years at the Center for Gerontology and Geriatrics, Dakar, Senegal. In this study, we included patients who experienced musculoskeletal pain for 3 months or longer (CP) and with a DN4 score ≥ 4 (NP). A complete clinical examination was performed to make the diagnosis of NP 'definite' or 'probable', and to identify the aetiologies of NP. During the study period, 698 outpatients were examined. There were 394 out of the 549 patients over 60 years who reported CP. Among them, 28 patients (7.1%) scored ≥4 on the DN4 questionnaire. Female patients, low educational attainment, manual professions, non-workers and diabetes were associated with NP (p < 0.05). The symptoms described by patients with NP, often intricate, were lumboradiculalgia (n = 9), cervico-brachial neuralgia (n = 3), polyneuropathy (n = 12) and mononeuropathy (n = 6). The presumed aetiologies in patients with NP were: chronic spine diseases (n = 14), painful diabetic peripheral neuropathy (n = 8), Sjögren's syndrome (n = 1), tarsal tunnel syndrome in rheumatoid arthritis (n = 1) and bone metastasis (n = 1). No aetiology was identified among three patients. Chronic spine diseases associated with radiculopathies and diabetic neuropathy are the main causes of NP, well detected by DN4 questionnaire and clinical examination in Senegalese sub-Saharan African elderly. © 2012 European Federation of International Association for the Study of Pain Chapters.
Sarr C.,University Of Thies |
International Journal of Parallel, Emergent and Distributed Systems | Year: 2014
In this study, we present a new analytic model for evaluating average end-to-end delay in IEEE 802.11 multihop wireless networks. Our model gives closed expressions for the end-to-end delay in function of arrivals and service time patterns. Each node is modelled as a G/G/1/K queue from which we can derive expressions for service time via queueing theory. By combining this delay evaluation with different admission controls, we design a protocol called DEAN (Delay Estimation in Ad hoc Networks). DEAN is able to provide delay guarantees for quality of service applications in function of the application level requirements. Through extensive simulations, we compare the performance evaluation of DEAN with other approaches. © 2013 Taylor & Francis.
Voumbo M.L.,Marien Ngouabi University |
Wereme A.,Institute Of Recherche En Science Appliquees Et Technologies Irsat |
Gaye S.,University Of Thies |
Adj M.,Cheikh Anta Diop University |
Sissoko G.,Cheikh Anta Diop University
Research Journal of Applied Sciences, Engineering and Technology | Year: 2010
This research report to the thermophysical characterization of the kapok and the kapok-plaster mixture. To carry out this characterization, we used the method off limp in permanent given to mode the conductivity and also the Degiovanni model. This study shows that the kapok's conductivity dregs between 0.03 and 0.04 W/m.°K for density which varies between 5 and 40 kg/m3. Taking also into account year average diffusivity of 17.1×10-7 m2/s, kapok has good heat insulator. Associated with the plaster, it makes it possible to improve the thermophysical characteristics off the plaster. © Maxwell Scientific Organization, 2010.
Camara M.,University Of Thies |
Mbaye A.A.,Center Pour Le Developpement Of Lhorticulture Cdh |
Noba K.,Cheikh Anta Diop University |
Samb P.I.,University Of Thies |
And 2 more authors.
Crop Protection | Year: 2013
Plant viral diseases are the most important pathogen attack tomato particularly of which is Tomato yellow leaf curl virus (TYLCV). Obtaining stable and durable resistances seems the most effective solution for controlling the disease. In this context, a breeding programme with two steps was conducted in the Niayes ecological area of Senegal: i) 41 tomato varieties from different origins were screened to assess their reaction to TYLCV disease, ii) 12 resistant varieties and two susceptible were tested in an experimental field. The first step was a preliminary trial in unreplicated plots, to identify promising varieties. However, disease assessments (incidence and severity) were done three times and we used longitudinal data analyses to classify the varieties for resistance. Yields in t/ha were also measured for the different varieties. Among our accessions, Roma VF and Xina known for their susceptibility, and Nadira known for its tolerance, were used as controls. Our results revealed 12 resistant varieties, 16 tolerant varieties and 8 susceptible varieties. The yield values were well correlated to the resistance measured by both incidence and by severity right from the second date of symptom observations, at the time of flowering. TYLCV disease is thus one of the main factors limiting tomato-growing the Niayes agro-ecological area. The second step of the selection process was done in a complete block design with three replications. This trial allowed a confirmation of the 12 resistant varieties. The final selection of the varieties took into account the other traits, like yield and traits related to the fruit characters. © 2012.