On the Kramers-Kronig transform with logarithmic kernel for the reflection phase in the Drude model

We use the Kramers-Kronig transform (KKT) with logarithmic kernel to obtain the reflection phase and, subsequently, the complex refractive index of a bulk mirror from reflectance. However, there remains some confusion regarding the formulation for this analysis. Assuming the damped Drude model for the dielectric constant and the oblique incidence case, we calculate the additional terms: phase at zero frequency and Blashke factor and we propose a reformulated KKT within this model. Absolute reflectance in the s-polarization case of a gold film is measured between 40 and 350 eV for various glancing angles using synchrotron radiation and its complex refractive index is deduced using the reformulated KKT that we propose. The results are discussed with respect to the data available in the literature.Comment: 18 pages, piblished in j. Mod. Opt. 57, 1504 (2010

Cr/Sc multilayer radiator for parametric EUV radiation in "water-window" spectral range

The results of experimental investigation of parametric radiation generated by 5.7 MeV electrons in a multilayer structure consisting of 100 Cr/Sc bi-layers deposited on a Si3N4 membrane are presented. The multilayer structure was specially created for generation of parametric radiation with photon energy in "water-window" spectral rang

Investigation of the thermal stability of Mg/Co periodic multilayers for EUV applications

We present the results of the characterization of Mg/Co periodic multilayers and their thermal stability for the EUV range. The annealing study is performed up to a temperature of 400\degree C. Images obtained by scanning transmission electron microscopy and electron energy loss spectroscopy clearly show the good quality of the multilayer structure. The measurements of the EUV reflectivity around 25 nm (~49 eV) indicate that the reflectivity decreases when the annealing temperature increases above 300\degreeC. X-ray emission spectroscopy is performed to determine the chemical state of the Mg atoms within the Mg/Co multilayer. Nuclear magnetic resonance used to determine the chemical state of the Co atoms and scanning electron microscopy images of cross sections of the Mg/Co multilayers reveal changes in the morphology of the stack from an annealing temperature of 305\degreee;C. This explains the observed reflectivity loss.Comment: Published in Applied Physics A: Materials Science \& Processing Published at http://www.springerlink.com.chimie.gate.inist.fr/content/6v396j6m56771r61/ 21 page

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

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

Thermal, mechanical and viscoelastic properties of citric acid-crosslinked starch/cellulose composite foams

In this work, biodegradable starch/cellulose composite foams were fabricated at 220 °C by compression moulding gelatinised starch containing cellulose fibres as a reinforcing agent and citric acid as a cross-linking agent. It was found that the stiffness, tensile strength, flexural strength, and hydrophobicity of the starch/cellulose composite foams increased, and water absorption capacity decreased with an increase in the concentration of citric acid. The tensile strength increased from 1.76 MPa for 0 % citric acid to 2.25 MPa for the starch/cellulose composite foam crosslinked with 5 % (w/w) citric acid. Similarly, the flexural modulus also increased from 445 MPa to 601.1 MPa, and the flexural strength from 3.76 MPa to 7.61 MPa, for the composite foam crosslinked with 5 % (w/w) citric acid. The crosslinked composite foams showed better thermal stability compared to the non-crosslinked composite foam. The resulting composite foams could be used as a biodegradable alternative to expanded polystyrene packaging

Thermo-mechanical, morphological and water absorption properties of thermoplastic starch/cellulose composite foams reinforced with PLA

Expanded polystyrene foams are lightweight and cheap, but they have excellent strength and insulation properties. However, their inability to biodegrade in traditional landfill situations makes their disposal problematic. Starch, a polysaccharide, has the potential to replace synthetic thermoplastics for some applications but starch-based foams are hydrophilic, which limits their applications. In this work, polylactide (PLA), a sustainably derived and industrially compostable polymer, was added to starch/cellulose composite foams to enhance their water barrier properties. PLA powder at various weight % was mixed with moistened starch and cellulose mixture, and composite foams were prepared by compression moulding at 220 °C. The thermomechanical and viscoelastic properties of the produced foam materials were analysed by thermogravimetric analysis, dynamic mechanical thermal analysis, mechanical testing, and also by the 3-point compressive mechanical quasi-static testing. It was found that the tensile strength of the composite foams increased with an increase in the PLA loading, which increased from 2.50 MPa for 0% PLA to 3.27 MPa for 9.72% PLA loading. The flexural strength also increased from 345.91 kPa for the 0% PLA to 378.53 kPa for the composite foam containing 4.86% PLA; beyond which the flexural strength started decreasing with an increase in PLA loading. Similarly, the stiffness of the starch/cellulose composite also increased with an increase in PLA loading up to 4.86%, and further increase in PLA loading decreased the stiffness. The flexural modulus of the composite foams increased from 522 MPa for 0% PLA loading to 542.85 MPa for the 4.86% PLA loading. The thermal stability of the starch/cellulose composite foams also increased and the water absorbency decreased with the increased PLA loading