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Junior E.L.B.,Federal University of Para | Rodrigues M.E.,Federal University of Para | Houndjo M.J.S.,Institute Of Mathematiques Et Of Science Physiques Imsp | Houndjo M.J.S.,University of Parakou
Journal of Cosmology and Astroparticle Physics | Year: 2015

We seek to obtain a new class of exact solutions of regular black holes in f(T) Gravity with non-linear electrodynamics material content, with spherical symmetry in 4D. The equations of motion provide the regaining of various solutions of General Relativity, as a particular case where the function f(T)=T. We developed a powerful method for finding exact solutions, where we get the first new class of regular black holes solutions in the f(T) Theory, where all the geometrics scalars disappear at the origin of the radial coordinate and are finite everywhere, as well as a new class of singular black holes. © 2015 IOP Publishing Ltd and Sissa Medialab srl . Source


Junior E.L.B.,Federal University of Para | Rodrigues M.E.,Federal University of Para | Houndjo M.J.S.,Institute Of Mathematiques Et Of Science Physiques Imsp | Houndjo M.J.S.,University of Parakou
Journal of Cosmology and Astroparticle Physics | Year: 2015

We investigate f(T) theory coupled with a nonlinear source of electrodynamics, for a spherically symmetric and static spacetime in 4D. We re-obtain the Born-Infeld and Reissner-Nordstrom-AdS solutions. We generalize the no-go theorem for any content that obeys the relationship 00=11 for the energy-momentum tensor and a given set of tetrads. Our results show new classes of solutions where the metrics are related through b(r)=-Na(r). We do the introductory analysis showing that solutions are that of asymptotically flat black holes, with a singularity at the origin of the radial coordinate, covered by a single event horizon. We also reconstruct the action for this class of solutions and obtain the functional form f(T)=f0(-T)(N+3)/[2(N+1)] and NED=0(-F)(N+3)/[2(N+1)]. Using the Lagrangian density of Born-Infeld, we obtain a new class of charged black holes where the action reads f(T)=-16βBI[1-1+(T/4βBI)]. © 2015 IOP Publishing Ltd and Sissa Medialab srl. Source


Rodrigues M.E.,Federal University of Para | Salako I.G.,Institute Of Mathematiques Et Of Science Physiques Imsp | Houndjo M.J.S.,Institute Of Mathematiques Et Of Science Physiques Imsp | Houndjo M.J.S.,University of Parakou | Tossa J.,Institute Of Mathematiques Et Of Science Physiques Imsp
International Journal of Modern Physics D | Year: 2014

We study the locally rotational symmetry Bianchi type-I dark energy model in the framework of f(T) theory of gravity, where T denotes the torsion scalar. A viable cosmological model is undertaken and the isotropization of this latter is checked, yielding a result that reflects the real evolution of our universe. Moreover, still in the anisotropic optic, a more complicated f(T) model is obtained from the cosmological reconstruction scheme and the analysis shows that the universe is more anisotropic at the beginning if the terms of higher order in T are not considered. This means that the nonlinear model should be favored by observational data. © World Scientific Publishing Company. Source


De Longueville F.,University of Namur | Hountondji Y.-C.,University of Parakou | Henry S.,University of Namur | Ozer P.,University of Liege
Science of the Total Environment | Year: 2010

This study aims to compare, on the one hand, the geographical distribution of the desert dust source areas, their contribution to quantities emitted into the atmosphere, the trajectories and the quantities deposited, with on the other hand the areas of research interest focused on the desert dust impacts on air quality and/or human health. Based on a systematic review of the literature using the ISI Web of Knowledge database, we found 231 articles published over the last decade on the desert dust impacts on air quality. Of these, 48% concerned Asian dust and 39% Saharan dust, with the remaining 13% divided between the other dust source areas. However, only one of these studies addressed the worsening air pollution in West Africa, even though it is very close to the Sahara, the greatest contributor to the global dust budget. Moreover, there have been very few studies (41) looking at the direct links between desert dust and human health; in this context too, no interest has been shown in West Africa. Yet this region is also among the areas in which morbidity rates have been noted to be far higher than those found in other regions of the world, and where respiratory infections alone account for more than 20% of the causes of infant mortality. This survey highlights a clear imbalance between those areas most exposed to dust and the most studied areas in terms of dust impacts. Given these findings and the often alarming results published about other regions of the world, we advocate a revival of interest in research on West Africa in order to achieve a better understanding of the desert dust impacts on air quality and health among the populations of this region. © 2010 Elsevier B.V. Source


Tachie-Obeng E.,U.S. Environmental Protection Agency | Akponikpe P.B.I.,University of Parakou | Adiku S.,University of Ghana
Environmental Development | Year: 2013

As a contribution to guide policy planning, effective climate change adaptation options to enhance maize production in Ghana were examined. The Agricultural Production Systems Simulator crop model, coupled with statistical downscaled climate scenarios of 9 general circulation models (GCMs) and farmer practices, were used to device adaptation options in the near future (NF) period of 2046-2065 based on IPCC A2 emission scenario at local scale level in Wa and Wenchi agricultural areas of Ghana. Results from the single-maize cropping season at Wa, in the savanna zone indicate that, a 6-week delay in sowing from 1961 to 2000 baseline date of 1st May to 15th June, was the most appropriate way to offset the negative effects of potential climate change resulting in a yield increase of 8.2%. In the forest-savanna transitional zone of Wenchi, a 4-week delay in the major season sowing date from 15th March to 15th April and no change in the minor season sowing date of 15th August resulted in a slight yield increase of 3.9%. On the other hand, a second adaptation option of using a medium heat-tolerant maize variety produced substantial gains in crop yield of 30.1% and 30.5% in savanna and forest-savanna transitional zones respectively with a longer grain-formation period under NF climate change when compared to delaying sowing dates. Effective adaptation options can thus reduce negative impacts of climate change in the NF, but require enabling policy to support its implementation. © 2012 Elsevier B.V. Source

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