545 research outputs found
Interplanetary scintillation observations of the solar wind close to the Sun and out of the ecliptic
A brief review is given of recent developments in the observation of the solar wind by the method of interplanetary scintillation. The emphasis is on observations of the velocity structure, the electron density and the effect of propagating disturbances in the interplanetary medium as detected principally by intensity and phase scintillation and by spectral broadening
Role of small-scale trees plantation and farmersâ attitude and skill toward propagation of indigenous and exotic trees: The case of Sidama, Ethiopia
The tree land cover in Ethiopia is declining due to deforestation, agricultural land expansion, overgrazing, firewood use and construction. Farm tree plantation has a potential to improve tree cover and the country's vision towards reducing greenhouse gases (GHG) emission by 2030. This study was conducted in Sidama of Ethiopia to assess the role of small-scale tree plantations, and the attitudes and skills of farmers in propagating and conserving indigenous trees as compared to exotic ones, and to identify major impediments for exotic and indigenous tree plantation. By using stratified random sampling, 149 household heads were selected and interviewed, and the tree plantation practices of 46 randomly selected farmers were observed. Advice and support given to farmers concerning tree plantation and nursery care were collected from 16 Woreda Rural Development Experts. During the study a total of 46 tree species were identified, and 92% of the trees on the farmland were exotic. The percentage composition of the five most dominant tree species were Eucalyptus spp. (79.6%), Cupressus spp (8.5%), Cordia africana (4.8%), Grevillea robusta (3.3%), and Millettia ferruginea (1.8%). The trees provide several direct and indirect socioeconomic and ecological importance (construction, fuel, income, medicinal value, fencing, asset for present and next generation, fodder for livestock, garden shade, aesthetic, recreation, spiritual value, improve soil fertility and environmental impact remediation). The majority of farmers prefer exotic trees due to their fast growth, ease of nursery preparation and fast establishment, and higher income generation in shorter period. Though farmers like to plant indigenous trees for their ecological services such as improving soil fertility, producing durable household utensils, shading and other ecological values; land shortage and lack of knowledge on plant biology, nursery preparation and propagation method constrained its plantation. Therefore, introduction of appropriate technologies to the existing farming system is required for sustainable indigenous tree plantation in the study area
Editorial: Roles and mechanisms of parasitism in aquatic microbial communities
International audienc
Correlation between some environmental variables and abundance of Almophrya mediovacuolata (Ciliophora: Anoplophryidae) endocommensal ciliate of an anecic earthworms (Oligochaeta: Annelida) in Bambui (North-West Cameroon)
This study was devoted to accessing the influence of some soil physico-chemical parameters on the abundance of Almophrya mediovacuolata Ngassam, 1983, astome ciliate of the digestive tract of earthworms (EW) of the species Alma nilotica collected along âFaâa ntsaâ stream in Bambui. The survey primarily involved soil samples collection from the same spots of EW collection and preparation for physico-chemical analysis; evaluation in situ of the volumic density (VD) of worms (number /dm3 soil), their dissection, isolation and counting of ciliates with respect to different portion of EWâs gut (fore, mid and hindgut). Furthermore, correlation analysis between soil physico-chemical parameters and biological responses (EW volumic density and ciliate abundance) were performed. The results reveal that EW abundance was positively and significantly correlated with the following physico-chemical parameters: Cation Exchange Capacity CEC (p <0.01) and Mg2+ (p <0.05). A positive and significant correlation was found between Almophrya mediovacuolata and the pH of KCl in the foregut and midgut (p <0.01) while a negative and significant correlation was found between the abundance of Almophrya mediovacuolata and Ca2+ in the foregut (p <0.05). Almophrya mediovacuolata were found mostly in the foregut. This result shows that each portion of the digestive tract of Alma nilotica can be considered as a set of natural microhabitat in which a number of physico-chemical factors generate ecological niches suitable for the survival of different species of microorganisms among which ciliated protozoa. The fore and midgut was noticed to be the preferential zones of Almophrya mediovacuolata.Keywords: Biotic parameters, ciliated protozoa, microhabitat, soil physico-chemical parameters
Mapping and modelling the geographical distribution and environmental limits of podoconiosis in Ethiopia
BACKGROUND
Ethiopia is assumed to have the highest burden of podoconiosis globally, but the geographical distribution and environmental limits and correlates are yet to be fully investigated. In this paper we use data from a nationwide survey to address these issues.
METHODOLOGY
Our analyses are based on data arising from the integrated mapping of podoconiosis and lymphatic filariasis (LF) conducted in 2013, supplemented by data from an earlier mapping of LF in western Ethiopia in 2008-2010. The integrated mapping used woreda (district) health offices' reports of podoconiosis and LF to guide selection of survey sites. A suite of environmental and climatic data and boosted regression tree (BRT) modelling was used to investigate environmental limits and predict the probability of podoconiosis occurrence.
PRINCIPAL FINDINGS
Data were available for 141,238 individuals from 1,442 communities in 775 districts from all nine regional states and two city administrations of Ethiopia. In 41.9% of surveyed districts no cases of podoconiosis were identified, with all districts in Affar, Dire Dawa, Somali and Gambella regional states lacking the disease. The disease was most common, with lymphoedema positivity rate exceeding 5%, in the central highlands of Ethiopia, in Amhara, Oromia and Southern Nations, Nationalities and Peoples regional states. BRT modelling indicated that the probability of podoconiosis occurrence increased with increasing altitude, precipitation and silt fraction of soil and decreased with population density and clay content. Based on the BRT model, we estimate that in 2010, 34.9 (95% confidence interval [CI]: 20.2-51.7) million people (i.e. 43.8%; 95% CI: 25.3-64.8% of Ethiopia's national population) lived in areas environmentally suitable for the occurrence of podoconiosis.
CONCLUSIONS
Podoconiosis is more widespread in Ethiopia than previously estimated, but occurs in distinct geographical regions that are tied to identifiable environmental factors. The resultant maps can be used to guide programme planning and implementation and estimate disease burden in Ethiopia. This work provides a framework with which the geographical limits of podoconiosis could be delineated at a continental scale
Investigating the 8.2 ka event in northwestern Madagascar: Insight from dataâmodel comparisons
The 8.2 ka event is a well-known cooling event in the Northern Hemisphere, but is poorly understood in Madagascar. Here, we compare paleoclimate data and outputs from paleoclimate simulations to better understand it. Records from Madagascar suggest two distinct sub-events (8.3 ka and 8.2 ka), that seem to correlate with records from northern high latitude. This could indicate causal relationships via changes in the Atlantic Meridional Overturning Circulation (AMOC) with changes in moisture source's ÎŽ18O, and changes in the mean position of the Inter-Tropical Convergence Zone (ITCZ), as climate modelling suggests. These two sub-events are also apparent in other terrestrial records, but the climatic signals are different. The prominent 8.2 ka sub-event records a clear antiphase relationship between the northern and southern hemisphere monsoons, whereas such relationship is less evident during the first 8.3 ka sub-event. Dataâmodel comparison have also shown a mismatch between the paleoclimate data and the model outputs, the causes of which are more or less understood and may lie in the proxies, in the model, or in both data and model. Knowing that paleoclimate proxies and climate models produce different sets of variables, further research is needed to improve the dataâmodel comparison approach, so that both paleoclimate data and paleoclimate models will better predict the likely climate status of a region during a specified time in the past with minimal uncertainties
Snow petrel stomach-oil deposits as a new biological archive of Antarctic sea ice
Where snow petrels forage is predominantly a function of sea ice. They spit stomach oil in defence, and accumulated deposits at nesting sites are providing new opportunities to reconstruct their diet, and, in turn, the sea-ice environment over past millennia
Hygroregulation, a key ability for eusocial insects: Native Western European honeybees as a case study
Sociality has brought many advantages to various hymenoptera species, including their ability
of regulating physical factors in their nest (e.g., temperature). Although less studied,
humidity is known to be important for egg, larval and pupal development, and also for nectar
concentration. Two subspecies of Apis mellifera of the M evolutionary lineage were used as
models to test the ability of a superorganism (i.e. honeybee colony) to regulate the humidity
in its nest (i.e. âhygroregulation hypothesisâ) in four conservation centers: two in France (A.
m. mellifera) and two in Portugal (A. m. iberiensis). We investigated the ability of both subspecies
to regulate the humidity in hives daily, but also during the seasons for one complete
year. Our data and statistical analysis demonstrated the capacity of the bees to regulate
humidity in their hive, regardless of the day, season or subspecies. Furthermore, the study
showed that humidity in beehives is stable even during winter, when brood is absent, and
when temperature is known to be less stable in the beehives. These results suggest that
humidity is important for honeybees at every life stage, maybe because of the âimprintâ of the
evolutionary history of this hymenopteran lineage.This work was supported in part by the
research project BEEHOPE funded by the European
call for projects 2013-2014 BiodivERsA / FACCEJPI
from research agencies of France (ANR-14-
EBID-0001), Spain (PCIN-2014-090) and Portugal
(BiodivERsA /0002/2014). I. Eouzan is financed by
a doctoral grant from the Ministry of National Education, Higher Education and Research (France).info:eu-repo/semantics/publishedVersio
Assessment of the potential effect of some streams properties on the isolated Aeromonas hydrophila strains susceptibility against some ĂĆœĂÂČ-Lactams and Sulfamids
The isolation and characterization of A. hydrophila strains were carried out a given stream located in the equatorial zone in Cameroon (Central Africa), during the mild rainy season and the mild dry season. The water physicochemical parameters measured were temperature, pH, electrical conductivity, color, turbidity and suspended solids. It has been noted that bacterial abundances as well as the values of physicochemical parameters undergoes temporal variations. Antimicrobial susceptibility tests showed that the means diameters of inhibition with Oxacillin, Ceftriazone, Penicellin, Sulfamethoxazol-trimethoprim, Chloramphenicol, Imipenem, Amoxicillin-Clavulanic acid and Cefazolin were 6.44, 21, 6.63, 9.58, 15.37, 22.18, 14.29 and 10.26 mm respectively. 100% of strains tested were resistant to Penicillin, 89.47 % resistant to Oxacillin, 68.42% resistant to Sulphamethoxazole-trimetroprim and 63.15% were resistant to Cefazolin. There were 54.60% cases of antibiotic resistance, 24.34 % of intermediate sensitivity and 21.05% of sensitive strains against the tested antibiotics. The encoded redundancy analysis indicates that the percentage of the variation explained on the canonical axes is of 47.8% for the F1 axis and 25.9% for the F2 axis, for an accumulated percentage of 73.7%. The suspended solids, the Ceftriazon and Chloramphenicol are correlated to the F1 axis in positive coordinates, and the Temperature and Amoxicillin-Clavulanic acid in negative coordinates. The correlation test between the water physicochemical characteristics and the inhibition diameters of antibiotics showed some significant correlations (P<0.05). The regulation of bacterial genes would be regulated by complex mechanisms. Although many factors implied are linked to the bacterial cell, others may belong to the closed environment
Growth factor restriction impedes progression of wound healing following cataract surgery: identification of VEGF as a putative therapeutic target
Secondary visual loss occurs in millions of patients due to a wound-healing response, known as posterior capsule opacification (PCO), following cataract surgery. An intraocular lens (IOL) is implanted into residual lens tissue, known as the capsular bag, following cataract removal. Standard IOLs allow the anterior and posterior capsules to become physically connected. This places pressure on the IOL and improves contact with the underlying posterior capsule. New open bag IOL designs separate the anterior capsule and posterior capsules and further reduce PCO incidence. It is hypothesised that this results from reduced cytokine availability due to greater irrigation of the bag. We therefore explored the role of growth factor restriction on PCO using human lens cell and tissue culture models. We demonstrate that cytokine dilution, by increasing medium volume, significantly reduced cell coverage in both closed and open capsular bag models. This coincided with reduced cell density and myofibroblast formation. A screen of 27 cytokines identified nine candidates whose expression profile correlated with growth. In particular, VEGF was found to regulate cell survival, growth and myofibroblast formation. VEGF provides a therapeutic target to further manage PCO development and will yield best results when used in conjunction with open bag IOL designs
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