432 research outputs found

    Allocation of Foreign Aid in a Segmented International Context

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    Research on the topic of distribution of foreign aid among recipients is regaining momentum. This is understandable in the light of the knowledge that presently the richest 40 percent of the developing world receives twice as much aid per capita as the poorest 40 percent [UNDP (1994)], while once upon a time foreign aid was sought to accomplish exactly the opposite. The distribution of official development assistance (ODA) is conventionally studied in terms of two models: the ‘recipient needs’ model and the ‘donor interest’ model. In the first, foreign aid flows are seen to satisfy the socio-economic needs of the recipient countries. In the second, national interests of donors, whether these are military, political or commercial, are seen to determine the direction and size of the foreign aid. Empirical studies were made to ascertain and understand whether, on balance, foreign aid is motivated by recipient need or donor interest. There is one class of studies, for example, Mcgillivray (1989), which estimates for donors a compound measure of their allocation bias. The other class of studies, i.e., Maizels and Nissanke (1984) and Grilli and Riess (1992), employs regression analysis to explain allocation of foreign aid by representative variables of recipient need and donor interest. Because the primary pursuit of these studies was to give an overall judgement on foreign aid motivations, insufficient attention was given to differentiations among donors, between recipients, and over time. The allocation policies of donors can be observed to differ between large donors and small donors, whereby the two types of donors are often tied to different groups of recipient countries. Moreover, other arguments than recipient need and donor interest, such as historic and geographical ties and the changing world political order, play important roles.

    Economic Growth of Rich and Poor Countries: A Social Accounting Matrix Approach

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    Many recent empirical studies on comparative growth focus on the supply side determinants of growth. This paper highlights the insights to be gained from employing a demand-determined growth model. A modelling framework along the Social Accounting Matrix, empirically analysed for a group of sixteen countries at different stages of economic development, gives support to the convergence thesis.

    Bcc 4^4He as a Coherent Quantum Solid

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    In this work we investigate implications of the quantum nature of bcc 4^{4}% He. We show that it is a unique solid phase with both a lattice structure and an Off-Diagonal Long Range Order of coherently oscillating local electric dipole moments. These dipoles arise from the local motion of the atoms in the crystal potential well, and oscillate in synchrony to reduce the dipolar interaction energy. The dipolar ground-state is therefore found to be a coherent state with a well defined global phase and a three-component complex order parameter. The condensation energy of the dipoles in the bcc phase stabilizes it over the hcp phase at finite temperatures. We further show that there can be fermionic excitations of this ground-state and predict that they form an optical-like branch in the (110) direction. A comparison with 'super-solid' models is also discussed.Comment: 12 pages, 8 figure

    Z^* Resonances: Phenomenology and Models

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    We explore the phenomenology of, and models for, the Z^* resonances, the lowest of which is now well established, and called the Theta. We provide an overview of three models which have been proposed to explain its existence and/or its small width, and point out other relevant predictions, and potential problems, for each. The relation to what is known about KN scattering, including possible resonance signals in other channels, is also discussed.Comment: 29 pages, uses RevTeX4; expanded version (published form

    Chiral perturbation theory calculation for pn -> dpipi at threshold

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    We investigate the reaction pn -> dpipi in the framework of Chiral Perturbation Theory. For the first time a complete calculation of the leading order contributions is presented. We identify various diagrams that are of equal importance as compared to those recognized in earlier works. The diagrams at leading order behave as expected by the power counting. Also for the first time the nucleon-nucleon interaction in the initial, intermediate and final state is included consistently and found to be very important. This study provides a theoretical basis for a controlled evaluation of the non-resonant contributions in two-pion production reactions in nucleon-nucleon collisions.Comment: 24 pages, 3 figures, 3 table

    Theory of Coexistence of Superconductivity and Ferroelectricity : A Dynamical Symmetry Model

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    We propose and investigate a model for the coexistence of Superconductivity (SC) and Ferroelectricity (FE) based on the dynamical symmetries su(2)su(2) for the pseudo-spin SC sector, h(4)h(4) for the displaced oscillator FE sector, and su(2)⊗h(4)su(2) \otimes h(4) for the composite system. We assume a minimal symmetry-allowed coupling, and simplify the hamiltonian using a double mean field approximation (DMFA). A variational coherent state (VCS) trial wave-function is used for the ground state: the energy, and the relevant order parameters for SC and FE are obtained. For positive sign of the SC-FE coupling coefficient, a non-zero value of either order parameter can suppress the other (FE polarization suppresses SC and vice versa). This gives some support to "Matthias' Conjecture" [1964], that SC and FE tend to be mutually exclusive. For such a Ferroelectric Superconductor we predict: a) the SC gap Δ\Delta (and TcT_c ) will increase with increasing applied pressure when pressure quenches FE as in many ferroelectrics, and b) the FE polarization will increase with increaesing magnetic field up to HcH_c . The last result is equivalent to the prediction of a new type of Magneto-Electric Effect in a coexistent SC-FE material. Some discussion will be given of the relation of these results to the cuprate superconductors.Comment: 46 page

    High-dimensional interior crisis in the Kuramoto-Sivashinsky equation

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    An investigation of interior crisis of high dimensions in an extended spatiotemporal system exemplified by the Kuramoto-Sivashinsky equation is reported. It is shown that unstable periodic orbits and their associated invariant manifolds in the Poincaré hyperplane can effectively characterize the global bifurcation dynamics of high-dimensional systems.A. C.-L. Chian, E. L. Rempel, E. E. Macau, R. R. Rosa, and F. Christianse
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