The possibility of a rice green revolution in large-scale irrigation schemes in Sub-Saharan Africa

This paper investigates the potential of and constraints to a rice Green Revolution in Sub-Saharan Africa's large-scale irrigation schemes, using data from Uganda, Mozambique, Burkina Faso, Mali, Niger, and Senegal. The authors find that adequate irrigation, chemical fertilizer, and labor inputs are the key to high productivity. Chemical fertilizer is expensive in Uganda and Mozambique and is barely used. This is aggravated when water access is limited because of the complementarities between fertilizer and irrigation. Meanwhile, in the schemes located in four countries in West Africa's Sahel region, where water access is generally good and institutional support for chemical fertilizer exists, rice farmers achieve attractive yields. Some countries'wage rate is high and thus mechanization could be one solution for this constraint. Improvement of credit access also facilitates the purchase of expensive fertilizer or the employment of hired labor.Crops&Crop Management Systems,Irrigation and Drainage,Water Supply and Systems,Regional Economic Development,Water and Industry

Quasiparticle properties of a single alpha particle in cold neutron matter

Light clusters such as alpha particles and deuterons are predicted to occur in hot nuclear matter as encountered in intermediate-energy heavy-ion collisions and protoneutron stars. To examine the in-medium properties of such light clusters, we consider a much simplified system in which like an impurity, a single alpha particle is embedded in a zero-temperature, dilute gas of non-interacting neutrons. By adopting a non-selfconsistent ladder approximation for the effective interaction between the impurity and the gas, which is often used for analyses of Fermi polarons in a gas of ultracold atoms, we calculate the quasiparticle properties of the impurity, i.e., the energy shift, effective mass, quasiparticle residue, and damping rate.Comment: 19 pages, 3 figures, version accepted for PRC: discussions on p-wave contributions and the validity range of the model were adde

Optimal intertemporal risk allocation applied to insurance pricing

We present a general approach to the pricing of products in finance and insurance in the multi-period setting. It is a combination of the utility indifference pricing and optimal intertemporal risk allocation. We give a characterization of the optimal intertemporal risk allocation by a first order condition. Applying this result to the exponential utility function, we obtain an essentially new type of premium calculation method for a popular type of multi-period insurance contract. This method is simple and can be easily implemented numerically. We see that the results of numerical calculations are well coincident with the risk loading level determined by traditional practices. The results also suggest a possible implied utility approach to insurance pricing.Comment: 20 pages, 3 figure

Intersections of ultracold atomic polarons and nuclear clusters: How is a chart of nuclides modified in dilute neutron matter?

Neutron star observations, as well as experiments on neutron-rich nuclei, used to motivate one to look at degenerate nuclear matter from its extreme, namely, pure neutron matter. As an important next step, impurities and clusters in dilute neutron matter have attracted special attention. In this paper, we review in-medium properties of these objects on the basis of the physics of polarons, which have been recently realized in ultracold atomic experiments. We discuss how such atomic and nuclear systems are related to each other in terms of polarons. In addition to the interdisciplinary understanding of in-medium nuclear clusters, it is shown that the quasiparticle energy of a single proton in neutron matter is associated with the symmetry energy, implying a novel route toward the nuclear equation of state from the neutron-rich side.Comment: 28 pages, 2 figure

Design and fabrication of Ti–Zr-Hf-Cr-Mo and Ti–Zr-Hf-Co-Cr-Mo high-entropy alloys as metallic biomaterials

Novel TiZrHfCr0.2Mo and TiZrHfCo0.07Cr0.07Mo high-entropy alloys for metallic biomaterials (bio-HEAs) were developed based on the combination of Ti–Nb–Ta–Zr–Mo alloy system and Co–Cr–Mo alloy system as commercially-used metallic biomaterials. Ti–Zr-Hf-Cr-Mo and Ti–Zr-Hf-Co-Cr-Mo bio-HEAs were designed using (a) a tree-like diagram for alloy development, (b) empirical alloy parameters for solid-solution-phase formation, and (c) thermodynamic calculations focused on solidification. The newly-developed bio-HEAs overcomes the limitation of classical metallic biomaterials by the improvement of (i) mechanical hardness and (ii) biocompatibility all together. The TiZrHfCr0.2Mo and TiZrHfCo0.07Cr0.07Mo bio-HEAs showed superior biocompatibility comparable to that of commercial-purity Ti. The superior biocompatibility, high mechanical hardness and low liquidus temperature for the material processing in TiZrHfCr0.2Mo and TiZrHfCo0.07Cr0.07Mo bio-HEAs compared with the Ti–Nb–Ta–Zr–Mo bio-HEAs gave the authenticity of the application of bio-HEAs for orthopedic implants with multiple functions.Nagase T., Iijima Y., Matsugaki A., et al. Design and fabrication of Ti–Zr-Hf-Cr-Mo and Ti–Zr-Hf-Co-Cr-Mo high-entropy alloys as metallic biomaterials. Materials Science and Engineering C, 107, 110322. https://doi.org/10.1016/j.msec.2019.110322