Combining quantitative and qualitative methods in assessing chronic poverty: the case of Rwanda

This paper addresses the issue of chronic poverty in Rwanda, an issue which has not been addressed specifically in the policy debate, despite the fact that it is likely to be widespread. In part this has reflected lack of available evidence, in that the conventional sources used to analyze chronic poverty are not available. We argue in this paper that by judicious combination of existing qualitative (a high quality nationwide participatory poverty assessment) and quantitative sources (a household survey) it is possible to identify and characterize a clearly distinct group of chronically poor households, whose characteristics are different from the poor as a whole

A model study of enhanced oil recovery by flooding with aqueous surfactant solution and comparison with theory

With the aim of elucidating the details of enhanced oil recovery by surfactant solution flooding, we have determined the detailed behavior of model systems consisting of a packed column of calcium carbonate particles as the porous rock, n-decane as the trapped oil, and aqueous solutions of the anionic surfactant sodium bis(2-ethylhexyl) sulfosuccinate (AOT). The AOT concentration was varied from zero to above the critical aggregation concentration (cac). The salt content of the aqueous solutions was varied to give systems of widely different, post-cac oil–water interfacial tensions. The systems were characterized in detail by measuring the permeability behavior of the packed columns, the adsorption isotherms of AOT from the water to the oil–water interface and to the water–calcium carbonate interface, and oil–water–calcium carbonate contact angles. Measurements of the percent oil recovery by pumping surfactant solutions into calcium carbonate-packed columns initially filled with oil were analyzed in terms of the characterization results. We show that the measured contact angles as a function of AOT concentration are in reasonable agreement with those calculated from values of the surface energy of the calcium carbonate–air surface plus the measured adsorption isotherms. Surfactant adsorption onto the calcium carbonate–water interface causes depletion of its aqueous-phase concentration, and we derive equations which enable the concentration of nonadsorbed surfactant within the packed column to be estimated from measured parameters. The percent oil recovery as a function of the surfactant concentration is determined solely by the oil–water–calcium carbonate contact angle for nonadsorbed surfactant concentrations less than the cac. For surfactant concentrations greater than the cac, additional oil removal occurs by a combination of solubilization and emulsification plus oil mobilization due to the low oil–water interfacial tension and a pumping pressure increase

Power without representation? The House of Lords and social policy

In the past the House of Lords has generally, and arguably for good reasons, been ignored in discussions of the making and scrutiny of welfare. However, it has always played some role in this field, particularly in the scrutiny and passage of legislation, and since the removal of hereditary Peers in 1999, some writers have argued that the House has become more assertive. This article examines the attitudes of Peers, including a comparison with the views of Members of Parliament, and draws a number of conclusions about the role of the upper House in relation to social policy

A review of in-situ loading conditions for mathematical modelling of asymmetric wind turbine blades

This paper reviews generalized solutions to the classical beam moment equation for solving the deflexion and strain fields of composite wind turbine blades. A generalized moment functional is presented to effectively model the moment at any point on a blade/beam utilizing in-situ load cases. Models assume that the components are constructed from inplane quasi-isotropic composite materials of an overall elastic modulus of 42 GPa. Exact solutions for the displacement and strains for an adjusted aerofoil to that presented in the literature and compared with another defined by the Joukowski transform. Models without stiffening ribs resulted in deflexions of the blades which exceeded the generally acceptable design code criteria. Each of the models developed were rigorously validated via numerical (Runge-Kutta) solutions of an identical differential equation used to derive the analytical models presented. The results obtained from the robust design codes, written in the open source Computer Aided Software (CAS) Maxima, are shown to be congruent with simulations using the ANSYS commercial finite element (FE) codes as well as experimental data. One major implication of the theoretical treatment is that these solutions can now be used in design codes to maximize the strength of analogues components, used in aerospace and most notably renewable energy sectors, while significantly reducing their weight and hence cost. The most realistic in-situ loading conditions for a dynamic blade and stationary blade are presented which are shown to be unique to the blade optimal tip speed ratio, blade dimensions and wind speed

Preface to the special issue on selected papers from the Second International Conference on Semiconductor Photochemistry SP-2

This article gives an overview of the Second International Conference on Semiconductor Photochemistry, SP-2

Alignment and Testing for a Freeform Telescope

Currently there is a strong desire to make Earth science less expensive. Freeform optics make these missions less expensive because they allow an optical designer to use fewer mirrors to create roughly the same effect. The main issue with using freeforms is how closely the substrate can be milled to its prescription. Over this summer, our team looked at two freeforms made by Corning Inc. using a brand new process to determine how close these optics are to their set prescriptions and how well NASA could align them

Curves of every genus with many points, II: Asymptotically good families

We resolve a 1983 question of Serre by constructing curves with many points of every genus over every finite field. More precisely, we show that for every prime power q there is a positive constant c_q with the following property: for every non-negative integer g, there is a genus-g curve over F_q with at least c_q * g rational points over F_q. Moreover, we show that there exists a positive constant d such that for every q we can choose c_q = d * (log q). We show also that there is a constant c > 0 such that for every q and every n > 0, and for every sufficiently large g, there is a genus-g curve over F_q that has at least c*g/n rational points and whose Jacobian contains a subgroup of rational points isomorphic to (Z/nZ)^r for some r > c*g/n.Comment: LaTeX, 18 page

Superconformal symmetry and hyperKaehler manifolds with torsion

The geometry arising from Michelson & Strominger's study of N=4B supersymmetric quantum mechanics with superconformal D(2,1;alpha)-symmetry is a hyperKaehler manifold with torsion (HKT) together with a special homothety. It is shown that different parameters alpha are related via changes in potentials for the HKT target spaces. For alpha not 0 or -1, we describe how each such HKT 4m-manifold M is derived from a space N of dimension 4m-4 which is quaternionic Kaehler with torsion and carries an Abelian instanton.Comment: 16 page