1,408 research outputs found
Esquisse d’une morphologie du wolof
La tradition descriptive du wolof admet généralement que les constructions telles que l’inversif, l’inchoatif, le causatif, la nominalisation, etc. sont obtenues en adjoignant un suffixe à un radical. Or, un tel modèle morphologique basée sur le mot, implique le recours à un catalogue de règles phonologiques qui ne sont pas évidentes dans la grammaire du wolof. Notre propos consiste à démontrer que le système morphologique du wolof accorde plus d’importance au squelette-CV qu’à une trame phonétique. L’analyse proposée permet donc d’éliminer un certain nombre de paradoxes découlant de la conception habituelle de la morphologie du wolof, et d’en proposer une image moins complexe, mais plus cohérente.The descriptive tradition of Wolof generally assumes that constructions such as the reversive, the inchoative, the causative, the nominalization, etc., are obtained by attaching a suffix to a stem. However, such a morphological model based on the word implies a set of phonological rules which are not self-evident in the grammar of Wolof. My purpose is to show that the CV-skeleton level is more important than the segmental level in the morphological system of Wolof. The proposed analysis thus allows us to eliminate a certain number of paradoxes resulting from the habitual conception of the morphology of Wolof, and to propose a less complex and more coherent system
Three-dimensional arrangement of β-tricalcium phosphate granules evaluated by microcomputed tomography and fractal analysis.
The macrophysical properties of granular biomaterials used to fill bone defects have rarely been considered. Granules of a given biomaterial occupy three-dimensional (3-D) space when packed together and create a macroporosity suitable for the invasion of vascular and bone cells. Granules of β-tricalcium phosphate were prepared using polyurethane foam technology and increasing the amount of material powder in the slurry (10, 11, 15, 18, 21 and 25g). After sintering, granules of 1000-2000μm were prepared by sieving. They were analyzed morphologically by scanning electron microscopy and placed in polyethylene test tubes to produce 3-D scaffolds. Microcomputed tomography (microCT) was used to image the scaffolds and to determine porosity and fractal dimension in three dimensions. Two-dimensional sections of the microCT models were binarized and used to compute classical morphometric parameters describing porosity (interconnectivity index, strut analysis and star volumes) and fractal dimensions. In addition, two newly important fractal parameters (lacunarity and succolarity) were measured. Compression analysis of the stacks of granules was done. Porosity decreased as the amount of material in the slurry increased but non-linear relationships were observed between microarchitectural parameters describing the pores and porosity. Lacunarity increased in the series of granules but succolarity (reflecting the penetration of a fluid) was maximal in the 15-18g groups and decreased noticeably in the 25g group. The 3-D arrangement of biomaterial granules studied by these new fractal techniques allows the optimal formulation to be derived based on the lowest amount of material, suitable mechanical resistance during crushing and the creation of large interconnected pores
Comparing Rainfall Use Efficiency trends with expert judgments for nation-wide land degradation assessments: the case of Senegal
An Adjustable Gas-Mixing Device to Increase Feasibility of In Vitro Culture of Plasmodium falciparum Parasites in the Field
A challenge to conducting high-impact and reproducible studies of the mechanisms of P. falciparum drug resistance, invasion, virulence, and immunity is the lack of robust and sustainable in vitro culture in the field. While the technology exists and is routinely utilized in developed countries, various factors–from cost, to supply, to quality–make it hard to implement in malaria endemic countries. Here, we design and rigorously evaluate an adjustable gas-mixing device for the in vitro culture of P. falciparum parasites in the field to circumvent this challenge. The device accurately replicates the gas concentrations needed to culture laboratory isolates, short-term adapted field isolates, cryopreserved previously non-adapted isolates, as well as to adapt ex vivo isolates to in vitro culture in the field. We also show an advantage over existing alternatives both in cost and in supply. Furthermore, the adjustable nature of the device makes it an ideal tool for many applications in which varied gas concentrations could be critical to culture success. This adjustable gas-mixing device will dramatically improve the feasibility of in vitro culture of Plasmodium falciparum parasites in malaria endemic countries given its numerous advantages
Progress in HPV vaccination in low- and lower-middle-income countries.
The past 10 years have seen remarkable progress in the global scale-up of human papillomavirus (HPV) vaccinations. Forty-three low- and lower-middle-income countries (LLMICs) have gained experience in delivering this vaccine to young adolescent girls through pilot programs, demonstration programs, and national introductions and most of these have occurred in the last 4 years. The experience of Senegal is summarized as an illustrative country case study. Publication of numerous delivery experiences and lessons learned has demonstrated the acceptability and feasibility of HPV vaccinations in LLMICs. Four areas require dedicated action to overcome remaining challenges to national scaling-up: maintaining momentum politically, planning successfully, securing financing, and fostering sustainability. Advances in policy, programming, and science may help accelerate reaching 30 million girls in LLMICs with HPV vaccine by 2020
The influence of the thickness of the Cds emitter layer on the performance of a CIGS solar cell with acceptor defects
In this work, we simulated a solar cell based on CIGS with simple default acceptor, using software (SCAPS) version 3.302 in order to study certain parameters. In particular, we have varied the thickness of the CdS emitter (0.05 mum, 0.04 mum and 0.03 mum) to study its influence on the performance of the cell. We were able to record that the energy efficiency increased from 16.50% for a thickness of 0.05 mum of the emitter to 16.87% for a thickness of 0.03 mum of the emitter. We also noted an improvement in other parameters, such as the form factor from FF = 79.81% to 80.10%, with the decrease in the thickness of the CdS. And from the Nyquist diagram, we also determined parameters like the series resistance to get an idea on the equivalent electrical circuit of the studied cell
Efficiency of Traditional Maize Storage and Control Methods in Rural Grain Granaries: a Case Study from Senegal
Maize storage and pest control method as practiced in traditional clay granaries in the Kédougou region in eastern Senegal were evaluated under rural conditions during two successive years. Three storage modes, i.e. maize cobs, winnowed and non-winnowed maize grains, were tested in seven granaries where the insecticidal plants Hyptis spicigera or H. suaveolens were either incorporated in the store structure or deposited as layers intermittently with maize. At the beginning of the storage period, all granaries were artificially infested with 7 pairs Tribolium castaneum and Sitophilus zeamais. No damage, losses or live insects were observed during 7 months of storage when maize cobs were placed between layers of H. spicigera. Compared with the control, incorporation of insecticidal plants within the granary bottom had no significant effect on the damage and loss level irrespective of the storage mode. Non-winnowed maize always suffered less damage and losses than the winnowed variant. In all granaries depredation, insect abundance and moisture content were highest toward the end of storage period between June and July
Electron Accumulation and Emergent Magnetism in LaMnO3/SrTiO3 Heterostructures
Emergent phenomena at polar-nonpolar oxide interfaces have been studied
intensely in pursuit of next-generation oxide electronics and spintronics. Here
we report the disentanglement of critical thicknesses for electron
reconstruction and the emergence of ferromagnetism in polar-mismatched
LaMnO3/SrTiO3 (001) heterostructures. Using a combination of element-specific
X-ray absorption spectroscopy and dichroism, and first-principles calculations,
interfacial electron accumulation and ferromagnetism have been observed within
the polar, antiferromagnetic insulator LaMnO3. Our results show that the
critical thickness for the onset of electron accumulation is as thin as 2 unit
cells (UC), significantly thinner than the observed critical thickness for
ferromagnetism of 5 UC. The absence of ferromagnetism below 5 UC is likely
induced by electron over-accumulation. In turn, by controlling the doping of
the LaMnO3, we are able to neutralize the excessive electrons from the polar
mismatch in ultrathin LaMnO3 films and thus enable ferromagnetism in films as
thin as 3 UC, extending the limits of our ability to synthesize and tailor
emergent phenomena at interfaces and demonstrating manipulation of the
electronic and magnetic structures of materials at the shortest length scales.Comment: Accepted by Phys. Rev. Let
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