Testing some f(R,T) gravity models from energy conditions

We consider $f(R, T)$ theory of gravity, where $R$ is the curvature scalar and $T$ the trace of the energy momentum tensor. Attention is attached to the special case, $f(R, T)= R+2f(T)$ and two expressions are assumed for the function $f(T)$, $\frac{a_1T^n+b_1}{a_2T^n+b_2}$ and $a_3\ln^{q}{(b_3T^m)}$, where $a_1$, $a_2$, $b_1$, $b_2$, $n$, $a_3$, $b_3$, $q$ and $m$ are input parameters. We observe that by adjusting suitably these input parameters, energy conditions can be satisfied. Moreover, an analyse of the perturbations and stabilities of de Sitter solutions and power-law solutions is performed with the use of the two models. The results show that for some values of the input parameters, for which energy conditions are satisfied, de Sitter solutions and power-law solutions may be stables.Comment: 25 pages, 6 figures. Accepted for publication in Journal of Modern Physcis (JMP

Tracing the Bioavailability of Three-Dimensional Graphene Foam in Biological Tissues

This is the final version of the article. Available from MDPI via the DOI in this record.Graphene-based materials with a three-dimensional (3D) framework have been investigated for a variety of biomedical applications because of their 3D morphology, excellent physiochemical properties, volume stability, and their controllable degradation rate. Current knowledge on the toxicological implications and bioavailability of graphene foam (GF) has major uncertainties surrounding the fate and behavior of GF in exposed environments. Bioavailability, uptake, and partitioning could have potential effects on the behavior of GF in living organisms, which has not yet been investigated. Here, we report a pilot toxicology study on 3D GF in common carps. Our results showed that GF did not show any noticeable toxicity in common carps, and the antioxidant enzymatic activities, biochemical and blood parameters persisted within the standard series. Further histological imaging revealed that GF remained within liver and kidney macrophages for 7 days without showing obvious toxicity. An in vivo study also demonstrated a direct interaction between GF and biological systems, verifying its eco-friendly nature and high biocompatibility.This work was supported by EPSRC Centre for Doctoral Training in Metamaterials, XM2 (Grant No. EP/L015331/1) University of Exeter EX4 4QF, United Kingdom

ETUDE DE L’INFLUENCE DES ADDITIONS MINERALES ACTIVES SUR LE COMPORTEMENT MECANIQUE DES CIMENTS ET MORTIERS

L’étude consiste à optimiser une composition d’un ciment en utilisant comme ajouts actifs la pouzzolane, le laitier, ou le silexen proportion variable, en étudiant les propriétés physico-chimiques et l’influence sur le comportement mécanique desmortiers, et bétons, afin d’aboutir à quelques améliorations concernant : l’économie, les propriétés physiques, le comportementmécanique, la durabilité.L’utilisation de ces ajouts naturels actifs a pour effet de diminuer l’énergie nécessaire à la production de ciment (l’ajout étantajouté après refroidissement de clinker) et d’augmenter la durabilité des bétons obtenus.L’emploi des ciments composés est intéressant pour les constructions immergées dans l’eau douce, constructions souterraineset aussi, pour les ouvrages marins en béton et en béton armé dans les cas ou les bétons doivent satisfaire à des conditionsd’étanchéité et de résistance aux eaux agressives

Biodiversity and Status of Cetaceans in Benin, West Africa: an Initial Assessment

No published literature is available on the whales and dolphins of Benin. A first insight in the cetacean biodiversity based on stranding, capture and sighting records, as well as a preliminary assessment of status, is provided. Seven species were authenticated: humpback whale Megaptera novaeangliae, common bottlenose dolphin Tursiops truncatus, Atlantic spotted dolphin Stenella frontalis, false killer whale Pseudorca crassidens, shortfinned pilot whale Globicephala macrorhynchus, Cuvier’s beaked whale Ziphius cavirostris and sperm whale Physeter macrocephalus. Two additional taxa were confirmed at genus level, i.e. common dolphin Delphinus sp. and minke whale Balaenoptera sp. All reported species also occur in Ghana or Togo. Concern is expressed that in Benin, as in some other western African nations, coastal communities increasingly exploit stranded and by-caught cetaceans to supply a thriving, albeit illegal, marine bushmeat trade. Small cetaceans were also taken intentionally in the absence of efficient controls of landings or other management measures. Although presently at subsistence scale, the threat of wider commercialization exists. In view of the limited number of validated species, voucher specimens and scarce biological baseline information, opportunistic sampling must be expanded to include more systematic and dedicated research, in particular, ship-based marine mammal surveys. It is recommended that graduate students at Benin’s universities play a central role

Zootechnical study of breeding modes of Somba cattle in Benin

The Somba cattle (Bos Taurus brachyceros sp), located in Benin and Togo, has a severe reduction of its livestock in recent decades. The aim of this study was to determine the causes of this phenomenon, in order to propose new approaches of conservation. The study consisted of surveys with targeted farmers and cattle. The results indicate that Somba cattle are not cared for both in terms of food and health, justifying its low performance and high mortality rate. The parameters covered by the study vary from one mode of farming to another. For individual parameters, entrusted farming is more interesting. In more than 80% of the farms of this mode, age at first calving is around 36 months, whereas it is of 42 months in the home farming, and have an inter calving period of 14 months which is also less than 24 months in the second case. Demographic parameters seem more interesting than home farming. Then, the mortality rate is 13.46% in home farming against 16.61% in entrusted farming. Regarding to external factors, health monitoring is lax in both modes. Food is a great concern especially during the dry season. The absorption by zebu was often mentioned as the main cause of the decrease of Somba cattle livestock. The present study shows that high mortality due to an absence of health monitoring is the basis of the sharp decline in the number of Somba cattle. The influence of zebu is currently marginal because 96.22% of cattle at the farm level respondents are Somba breed.Keywords: Parameters, individuals, demographic, livestock, conservation, mortalit

Increase in susceptibility to insecticides with aging of wild \u3ci\u3eAnopheles gambiae\u3c/i\u3e mosquitoes from Côte d’Ivoire

Background: Appropriate monitoring of vector insecticide susceptibility is required to provide the rationale for optimal insecticide selection in vector control programs. Methods: In order to assess the influence of mosquito age on susceptibility to various insecticides, field-collected larvae of An. gambiae s.l. from Tiassalé were reared to adults. Females aged 1, 2, 3, 5 and 10 days were exposed to 5 insecticides (deltamethrin, permethrin, DDT, malathion and propoxur) using WHO susceptibility test kits. Outcome measures included the LT50 (exposure time required to achieve 50% knockdown), the RR (resistance ratio, i.e. a calculation of how much more resistant the wild population is compared with a standard susceptible strain) and the mortality rate following 1 hour exposure, for each insecticide and each mosquito age group. Results: There was a positive correlation between the rate of knockdown and mortality for all the age groups and for all insecticides tested. For deltamethrin, the RR50 was highest for 2 day old and lowest for 10 day old individuals. Overall, mortality was lowest for 2 and 3 day old individuals and significantly higher for 10 day old individuals (P \u3c 0.05). With permethrin, the RR50 was highest for 1 to 3 day old individuals and lowest for 10 day old individuals and mortality was lowest for 1 to 3 day old individuals, intermediate for 5 day old and highest for 10 day old individuals. DDT did not display any knockdown effect and mortality was low for all mosquito age groups (\u3c7%). With malathion, the RR50 was low (1.54 - 2.77) and mortality was high (\u3e93%) for all age groups. With propoxur, no knockdown effect was observed for 1, 2 and 3 day old individuals and a very low level of mortality was observed (\u3c 4%), which was significantly higher for 5 and 10 day old individuals (30%, P \u3c 0.01). Conclusion: Results indicate that for An. gambiae s.l. adults derived from wild-collected larvae, there was an influence of age on insecticide susceptibility status, with younger individuals (1 to 3 days old) more resistant than older mosquitoes. This indicates that the use of 1 – 2 day old mosquitoes in susceptibility assays as recommended by the WHO should facilitate detection of resistance at the stage where the highest rate of the resistance phenotype is present

Variabilidade genética para caracteres de frutos em genótipos de maracujazeiro

Recursos Genético

SIMULATION DU CLIMAT FUTUR ET DES RENDEMENTS AGRICOLES EN REGION SOUDANO-SAHELIENNE\ua0 EN REPUBLIQUE DU BENIN

Climate change is unequivocal and affects biophysical systems. Predicting the future effects of climate change is a prerequisite for the development of adaptation and mitigation strategies. This study was carried out to determine the future yields of the main agricultural crops in the Sudano-Sahelian region of West Africa, and especially using Banikoara district of Republic of Benin, for the period up to 2050. The methodology adopted combined the collection of long term agricultural and meteorological data, the calculation of agro-climatic indexes and simulation of crop yields using DSSAT (Decision Support System for Agrotechnology Transfert) and Crop-Model. Results revealed that the temperatures of Sudano-Sahelian region will increase in temperature by about 1 to 3 \ub0C compared to the reference period 1971-2010. The rainfall of the agricultural season will decline under the assumption of an increase in mean temperature (of 1, 1.5 and 2\ub0C). Apart from sorghum of which the simulated yield will increase about 9,3%, other crops will be characterised by a decline by 2050 of projected yields. The greatest decline in simulated yield was recorded for cassava; while yam showed the lowest decline in yield. Indeed, if cassava has particular affection for hot climates, it requires a certain soil moisture that is no longer guaranteed due to climate change. The shift of agricultural calendar and especially the adaptation of the sowing date to the observed climatic disturbances is urgently needed to ascertain food security insurance in the Sudano-Sahelian region of Benin.Le changement climatique est sans \ue9quivoque et affecte les syst\ue8mes biophysiques. La pr\ue9diction des effets futurs du changement climatique constitue un pr\ue9alable indispensable dans l\u2019\ue9laboration des strat\ue9gies d\u2019adaptation et d\u2019att\ue9nuation. La pr\ue9sente \ue9tude a \ue9t\ue9 initi\ue9e pour d\ue9terminer les caract\ue9ristiques des rendements des principales sp\ue9culations agricoles de la r\ue9gion soudano-sah\ue9lienne de l\u2019Afrique de l\u2019Ouest et plus particuli\ue8rement la Commune de Banikoara \ue0 l\u2019horizon 2050. La m\ue9thodologie adopt\ue9e regroupe la collecte des statistiques agricoles et des donn\ue9es m\ue9t\ue9orologiques sur le long terme, le calcul d\u2019indices agro-climatiques et la simulation des rendements au moyen de DSSAT (Decision Support System for Agrotechnology Transfert) et Crop-Model. Des r\ue9sultats, il appara\ueet que les temp\ue9ratures de la r\ue9gion soudano-sah\ue9lienne connaitront une hausse comprise entre 1\ub0 et 3\ub0C en r\ue9f\ue9rence aux valeurs de la p\ue9riode 1971-2010. La pluviom\ue9trie de la saison agricole baissera par rapport \ue0 la p\ue9riode de r\ue9f\ue9rence selon les sc\ue9narios d\u2019augmentation de la temp\ue9rature moyenne (de 1\ub0C, 1,5\ub0C et 2\ub0C). Outre le sorgho pour lequel une am\ue9lioration de 9,3% du rendement a \ue9t\ue9 observ\ue9e, les rendements des sp\ue9culations agricoles baisseront \ue0 l\u2019horizon 2050. Le plus fort niveau de baisse de rendement simul\ue9 a \ue9t\ue9 enregistr\ue9 pour le manioc tandis que l\u2019igname a affich\ue9 la baisse de rendement le plus faible. En effet, si le manioc affectionne les climats chauds, il exige une certaine humidit\ue9 qui n\u2019est plus assur\ue9e compte tenu du changement climatique. La modification du calendrier agricole et plus pr\ue9cis\ue9ment l\u2019adaptation des p\ue9riodes de semis aux perturbations climatiques constat\ue9es appara\ueet comme une n\ue9cessit\ue9 urgente pour garantir la s\ue9curit\ue9 alimentaire dans la r\ue9gion soudano-sah\ue9lienne