Vanishing Loss Effect on the Effective ac Conductivity behavior for 2D Composite Metal-Dielectric Films At The Percolation Threshold

We study the imaginary part of the effective $ac$ conductivity as well as its distribution probability for vanishing losses in 2D composites. This investigation showed that the effective medium theory provides only informations about the average conductivity, while its fluctuations which correspond to the field energy in this limit are neglected by this theory.Comment: 6 pages, 2 figures, submitted to Phys.Rev.

Theoretical study of the structural stability, electronic and magnetic properties of XVSb (X == Fe, Ni, and Co) half-Heusler compounds

The structural, electronic and magnetic properties of half-Heusler compounds XVSb (X $=$ Fe, Co and Ni) are investigated by using the density functional theory with generalized gradient approximation (GGA), and Tran-Blaha modified Becke-Johnson (TB-mBJ) exchange potential approximation. It is found that the half-metallic gaps are generally reasonably widened by mBJ as compared to the GGA approximation. The magnetic proprieties of XVSb (X $=$ Fe, Co and Ni) are well defined within mBJ with an exact integer value of magnetic moment. The band gaps given by TB-mBJ are in good agreement with the available theoretical data. The FeVSb exhibits a semiconductor nature. The CoVSb and NiVSb present half-metallic behaviour with total magnetic moment of $1\mu_\text{B}$ and $2\mu_\text{B}$ in good agreement with Slater-Pauling rule. These alloys seem to be a potential candidate of spintronic devices.Comment: 9 pages, 5 figure

Sociophysics Simulations III: Retirement Demography

This third part of the lecture series deals with the question: Who will pay for your retirement? For Western Europe the answer may be ``nobody'', but for Algeria the demography looks more promising.Comment: For 8th Granada seminar (AIP Conf. Proc.); 8 pages including 3 figure

REFORM OF IRRIGATION MANAGEMENT AND INVESTMENT POLICY IN AFRICAN DEVELOPMENT

This paper examines the reform of water and irrigation management in Africa and compares it with similar reforms in Asia. Several things are evident from the review. First, Sub-Saharan Africa (SSA) is at an earlier stage of irrigation development and reform than Asia. Second, the articulated need for reform is much stronger in Asia than it is in SSA. Third, the productivity of small-scale irrigated farms is significantly lower in SSA compared to Asia. Thus any irrigation investment strategy in SSA should be different from Asia and focus on increasing small-farm productivity as well as small-scale irrigation projects. Finally, all direct government irrigation investments should be done jointly with decisions regarding the type of project management.Resource /Energy Economics and Policy,

REFORM OF IRRIGATION MANAGEMENT AND INVESTMENT POLICY IN AFRICAN DEVELOPMENT

This paper examines the reform of water and irrigation management in Africa and compares it with similar reforms in Asia. Several things are evident from the review. First, Sub-Saharan Africa (SSA) is at an earlier stage of irrigation development and reform than Asia. Second, the articulated need for reform is much stronger in Asia than it is in SSA. Third, the productivity of small-scale irrigated farms is significantly lower in SSA compared to Asia. Thus any irrigation investment strategy in SSA should be different from Asia and focus on increasing small-farm productivity as well as small-scale irrigation projects. Finally, all direct government irrigation investments should be done jointly with decisions regarding the type of project management.International Development, Resource /Energy Economics and Policy,