112 research outputs found

    Scaling up index insurance for smallholder farmers: Recent evidence and insights

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    This report explores evidence and insights from five case studies that have made significant recent progress in addressing the challenge of insuring poor smallholder farmers and pastoralists in the developing world. In India, national index insurance programmes have reached over 30 million farmers through a mandatory link with agricultural credit and strong government support. In East Africa (Kenya, Rwanda and Tanzania), the Agriculture and Climate Risk Enterprise (ACRE) has recently scaled to reach nearly 200,000 farmers, bundling index insurance with agricultural credit and farm inputs. ACRE has built on strong partnerships with regional initiatives such as M-PESA mobile banking. In Ethiopia and Senegal, the R4 Rural Resilience Initiative has scaled unsubsidized index insurance to over 20,000 poor smallholder farmers who were previously considered uninsurable, using insurance as an integral part of a comprehensive risk management portfolio. With strong public and private sector support, the Mongolia Index-Based Livestock Insurance Project (IBLIP) insures more than 15,000 nomadic herders and links commercial insurance with a government disaster safety net. Finally, the Index-Based Livestock Insurance (IBLI) project in Kenya and Ethiopia demonstrates innovative approaches to insuring poor nomadic pastoralists in challenging circumstances. A few common features appear to have contributed to recent progress within these case studies: explicitly targeting obstacles to improving farmer income; integration of insurance with other development interventions; giving farmers a voice in the design of products; investing in local capacity; and investing in science-based index development. Evidence from these case studies can inform the ongoing debate about the viability of scaling up index-based insurance for vulnerable smallholder farmers in the developing world. The rapid progress observed in recent years suggests that index insurance has the potential to benefit smallholder farmers at a meaningful scale, and suggests the need to reassess arguments that lack of demand and practical implementation challenges prevent index-based insurance from being a useful tool to reduce rural poverty

    On Predicting Mössbauer Parameters of Iron-Containing Molecules with Density-Functional Theory

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    The performance of six frequently used density functional theory (DFT) methods (RPBE, OLYP, TPSS, B3LYP, B3LYP*, and TPSSh) in the prediction of Mössbauer isomer shifts(δ) and quadrupole splittings (ΔEQ) is studied for an extended and diverse set of Fe complexes. In addition to the influence of the applied density functional and the type of the basis set, the effect of the environment of the molecule, approximated with the conducting-like screening solvation model (COSMO) on the computed Mössbauer parameters, is also investigated. For the isomer shifts the COSMO-B3LYP method is found to provide accurate δ values for all 66 investigated complexes, with a mean absolute error (MAE) of 0.05 mm s–1 and a maximum deviation of 0.12 mm s–1. Obtaining accurate ΔEQ values presents a bigger challenge; however, with the selection of an appropriate DFT method, a reasonable agreement can be achieved between experiment and theory. Identifying the various chemical classes of compounds that need different treatment allowed us to construct a recipe for ΔEQ calculations; the application of this approach yields a MAE of 0.12 mm s–1 (7% error) and a maximum deviation of 0.55 mm s–1 (17% error). This accuracy should be sufficient for most chemical problems that concern Fe complexes. Furthermore, the reliability of the DFT approach is verified by extending the investigation to chemically relevant case studies which include geometric isomerism, phase transitions induced by variations of the electronic structure (e.g., spin crossover and inversion of the orbital ground state), and the description of electronically degenerate triplet and quintet states. Finally, the immense and often unexploited potential of utilizing the sign of the ΔEQ in characterizing distortions or in identifying the appropriate electronic state at the assignment of the spectral lines is also shown

    The Evolution of the Engine Noise Problem

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    RUTHENIUM-99 MÖSSBAUER STUDY OF THE PEROVSKITE PHASES LaxSr1-xRuO3 AND LaxCa1-xRuO3

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    Les propriétés magnétiques, électroniques et structurales de solution solide LaxSr1-xRuO3 et LaxCa1-xRuO3 ont été étudiées par spectrométrie Mössbauer de 99Ru et par d'autres techniques. L'existence de phases LaxCa1-xRuO3 est démontrée pour la première fois à partir de diagrammes de poudre R. X. qui permettent de les identifier à des pérovskites distordues en structures orthorhombiques. Des mesures de résistivité électrique sur des poudres frittées montrent que toutes les phases sont métalliques avec ρ ≈ 10-3 ohm. cm. La substitution progressive de Sr2+ par La3+ dans le composé ferromagnétique SrRuO3 conduit à une rapide disparition du champ hyperfin à 4,2 K. Pour x = 0,25 certains ions Ru sont encore porteurs de moment, mais pour 0,4 ≤ x ≤ 0,75, on n'observe plus que des raies étroites de résonance, ce qui est caractéristique de la disparition du ferromagnétisme et la présence d'un état moyen d'oxydation de Ru dans chaque phase, soit Lax3+ Sr2+1-x Ru(4-x)+O3 plutôt que Lax3+Sr2+1-xRU3+x+Ru4+1-xO3 LaRuO3 et CaRuO3 donne essentiellement des spectres à une seule raie à 4,2 K, ce qui montre que le Ru dans les oxydes ne sont pas soumis à un ordre antiferromagnétique mais sont probablement paramagnétiques. Les solutions solides LaxCa1-xRuO3(0 < x ≤ 0,6) donnent une raie unique très étroite avec un déplacement isomérique qui varie progressivement depuis la valeur caractéristique de Ru4+ jusqu'à celle de Ru3+ (— 0,303 mm s-1 et — 0,557 mm s-1 par rapport à Ru métal), ce qui confirme bien l'existence d'états d'oxydation intermédiaires, également dans ces phases.The magnetic, electronic, and structural properties of the solid solutions LaxSr1-xRuO3 and LaxCa1-xRuO3 have been studied by 99Ru Mössbauer spectroscopy and other techniques. The LaxCa1-xRuO3 phases are reported for the first time and have been shown by powder X-ray diffraction measurements to be orthorhombically distorted perovskites. Electrical resistivity measurements on compacted powders show that all the phases are metallic with ρ ~ 10-3 ohm cm. Progressive substitution of Sr2+ by La3+ in ferromagnetic SrRuO3 leads to a rapid collapse of the magnetic hyperfine splitting at 4.2 K. For x = 0.25 some ruthenium ions still experience magnetic flux densities but for 0.4 ≤ x ≤ 0.75 only single, narrow resonance lines are observed, consistent both with the complete removal of the ferromagnetism and with the presence of an averaged ruthenium oxidation state in each phase, i. e. La3+xS2+1-x Ru(4-x)+O3 rather than La3+xSr2+1-xRu3+x Ru4+1-xO3. LaRuO3 and CaRuO3 both give essentially single-line spectra at 4.2 K, indicating that the ruthenium ions in these oxides are not involved in long-range antiferromagnetic order but are probably paramagnetic. The solid solutions LaxCa1-xRuO3 (0 < x ≤ 0.6) each give a sharp symmetrical singlet with a chemical isomer shift which moves progressively from the value characteristic of Ru4+ towards the value for Ru3+ (— 0.303 mm s-1 and — 0.557 mm s-1 respectively relative to Ru-metal), consistent with the presence of intermediate ruthenium oxidation States in these phases also. These results will be discussed together with those obtained recently on other related ruthenium oxide systems

    A Domino Ring-Opening/Epoxidation of 1,2-Dioxines

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    When allowed to react with alkaline hydrogen peroxide, monocyclic 1,2-dioxines ring-open to their isomeric 'y'-hydroxyenone intermediates which are rapidly epoxidized to afford 'trans'-4-hydroxy-2,3-epoxyketones in 21-81% yield. In the case of 'meso'-1,2-dioxines, Co(II) complex catalyzed asymmetric ring-opening of the 1,2-dioxine may be employed to furnish enantioenriched epoxides
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