World Bank Independence: A Model and Statistical Analysis of U.S. Influence

This paper develops a model to test whether World Bank lending caters to U.S. interests. We use country-level panel data to examine the geographic distribution of World Bank lending to 110 countries from 1968 to 2002. After controlling for country characteristics expected to influence the distribution of lending in a manner consistent with the World Bank’s charter and stated allocation mechanisms, we introduce variables reflecting U.S. interests. The empirical results are consistent with a significant U.S. influence, but one which varies across presidential administrations. These findings have important implications because donor influence may reduce the credibility, and hence the development effectiveness, of multilateral aid organizations.

How Do Political Changes Influence U.S. Bilateral Aid Allocations? Evidence from Panel Data

This paper examines the role of U.S. domestic politics in the allocation of foreign aid using panel data on aid to 119 countries from 1960 to 1997. Employing proxies for four aid allocation criteria (development concerns, strategic importance, commercial importance, and the degree of democratization), we find evidence that each influences aid allocation, although the evidence is stronger for some criteria (development concerns, commercial importance) than for others (strategic importance, degree of democratization). Furthermore, the allocation pattern depends on the composition of the U.S. government. When the president and Congress are liberal, development concerns receive more weight in the allocation process than when the president and/or Congress are more conservative. When the Congress is more conservative, commercial concerns have more weight than when the Congress is liberal. These findings have practical importance in light of current attempts to overhaul the allocation of both bilateral and multilateral aid.

Compressive behavior and failure mechanisms of freestanding and composite 3D graphitic foams

Open-cell graphitic foams were fabricated by chemical vapor deposition using nickel templates and their compressive responses were measured over a range of relative densities. The mechanical response required an interpretation in terms of a hierarchical micromechanical model, spanning 3 distinct length scales. The power law scaling of elastic modulus and yield strength versus relative density suggests that the cell walls of the graphitic foam deform by bending. The length scale of the unit cell of the foam is set by the length of the struts comprising the cell wall, and is termed level I. The cell walls comprise hollow triangular tubes, and bending of these strut-like tubes involves axial stretching of the tube walls. This length scale is termed level II. In turn, the tube walls form a wavy stack of graphitic layers, and this waviness induces interlayer shear of the graphitic layers when the tube walls are subjected to axial stretch. The thickness of the tube wall defines the third length scale, termed level III. We show that the addition of a thin, flexible ceramic Al2O3 scaffold stiffens and strengthens the foam, yet preserves the power law scaling. The hierarchical model gives fresh insight into the mechanical properties of foams with cell walls made from emergent 2D layered solids.We acknowledge funding from EPSRC (Grant No. EP/K016636/1, GRAPHTED) and the ERC (Grant No. 279342, InsituNANO; Grant No. 669764, MULTILAT). A.I.A. acknowledges the 2014 Green Talents Research Stay program from The German Federal Ministry of Education and Research (BMBF) and the EU Marie Sklodowska-Curie (Grant No. 645725, FRIENDS2). K.N. acknowledges funding from the EPSRC Cambridge NanoDTC (Grant No. EP/G037221/1)

How do political changes influence U.S. bilateral aid allocations? Evidence from panel data

This paper examines the role of U.S. domestic politics in the allocation of foreign aid using panel data on aid to 119 countries from 1960 to 1997. Employing proxies for four aid allocation criteria (development concerns, strategic importance, commercial importance, and the degree of democratization), we find evidence that each influences aid allocation, although the evidence is stronger for some criteria (development concerns, commercial importance) than for others (strategic importance, degree of democratization). Furthermore, the allocation pattern depends on the composition of the U.S. government. When the president and Congress are liberal, development concerns receive more weight in the allocation process than when the president and/or Congress are more conservative. When the Congress is more conservative, commercial concerns have more weight than when the Congress is liberal. These findings have practical importance in light of current attempts to overhaul the allocation of both bilateral and multilateral aid

World Bank independence: A model and statistical analysis of U.S. influence

This paper develops a model to test whether World Bank lending caters to U.S. interests. We use country-level panel data to examine the geographic distribution of World Bank lending to 110 countries from 1968 to 2002. After controlling for country characteristics expected to influence the distribution of lending in a manner consistent with the World Bank’s charter and stated allocation mechanisms, we introduce variables reflecting U.S. interests. The empirical results are consistent with a significant U.S. influence, but one which varies across presidential administrations. These findings have important implications because donor influence may reduce the credibility, and hence the development effectiveness, of multilateral aid organizations

Tablet for two: How do children collaborate around single player tablet games?

Tablet computers are increasingly used in school classrooms. However, despite the fact that these devices are conceived as single-user devices, and most games or apps developed for them are designed for single-users, pairs or groups of students usually use these devices. Surprisingly little research has been done to explore the ways in which these devices support or not children’s collaboration – instead research has focused on larger tabletop computers, or on collaboration around configurations of multiple tablet computers. In this paper we present a case-study analysis of pairs of children playing single player tablet games together. We use a combination of temporal video analysis and the Collaborative Learning Mechanisms (CLM) framework previously developed to understand collaboration around surfaces. This analysis aims to unpack collaborative interactions around these devices and identify ways in which successful and less successful collaborations occur. A comparison of our findings to previous studies of interactions around larger tabletop surfaces reveals some of the ways interactions around tablets differ to these. We use these understandings to begin to outline some of the issues to take into consideration when facilitating and designing for children’s collaboration around single tablet computer

The Influence of Strut Waviness on the Tensile Response of Lattice Materials

Abstract Recent advances in additive manufacturing methods make it possible, for the first time, to manufacture complex micro-architectured solids that achieve desired stress versus strain responses. Here, we report experimental measurements and associated finite element (FE) calculations on the effect of strut shape upon the tensile response of two-dimensional (2D) lattices made from low-carbon steel sheets. Two lattice topologies are considered: (i) a stretching-dominated triangular lattice and (ii) a bending-dominated hexagonal lattice. It is found that strut waviness can enhance the ductility of each lattice, particularly for bending-dominated hexagonal lattices. Manufacturing imperfections such as undercuts have a small effect on the ductility of the lattices but can significantly reduce the ultimate tensile strength. FE simulations provide additional insight into these observations and are used to construct design maps to aid the design of lattices with specified strength and ductility.</jats:p

Regulation of notch sensitivity of lattice materials by strut topology

We propose a local reinforcement technique for lattices in the vicinity of a stress-raiser such as a notch, in order to elevate the macroscopic strength and ductility. A spatially non-uniform waviness distribution of sinusoidally-shaped struts is assumed in the vicinity of the notch, and the sensitivity of macroscopic tensile response to strut waviness distribution is studied by finite element analysis. Optimized lattice structures are determined in order to maximise the macroscopic tensile strength or ductility from these various strut waviness distributions. Both hexagonal and triangular lattices are studied as these geometries are representative of bending-dominated and stretching-dominated lattices, respectively

Spectroscopy of doubly charmed baryons: Ξcc+\Xi_{cc}^{+} and Ξcc++\Xi_{cc}^{++}

Using the quark-diquark approximation in the framework of Buchm\" uller-Tye potential model, we investigate the spectroscopy of doubly charmed baryons: $\Xi_{cc}^{++}$ and $\Xi_{cc}^{+}$. Our results include the masses, parameters of radial wave functions of states with the different excitations of both diquark and light quark-diquark system. We calculate the values of fine and hyperfine splittings of these levels and discuss some new features, connected to the identity of heavy quarks, in the dynamics of hadronic and radiative transitions between the states of these baryons.Comment: 10 pages, Latex file, 1 fig, corrected some typo

Quark-Meson Coupling Model for a Nucleon

The quark-meson coupling model for a nucleon is considered. The model describes a nucleon as an MIT bag, in which quarks are coupled to scalar and vector mesons. A set of coupled equations for the quark and the meson fields are obtained and are solved in a self-consistent way. It is shown that the mass of a nucleon as a dressed MIT bag interacting with sigma- and omega-meson fields significantly differs from the mass of a free MIT bag. A few sets of model parameters are obtained so that the mass of a dressed MIT bag becomes the nucleon mass. The results of our calculations imply that the self-energy of the bag in the quark-meson coupling model is significant and needs to be considered in doing the nuclear matter calculations.Comment: 3 figure