8,330 research outputs found
Recommended from our members
The normalisation of Food Aid: What happened to feeding people well?
In the UK, food poverty has increased in the last 15 years and the food aid supply chain that has emerged to tackle it is now roughly 10 years old. In this time, we have seen the food aid supply chain grow at a rate that has astounded many.  Recently that growth has been aided by a grant of £20m from a large supermarket chain. It appears institutionalisation is just around the corner, if not already here. It also appears that there is far greater emphasis on dealing with the symptoms as opposed to solving the root causes of the problem. As an opinion piece, this paper reflects on some of the prevalent issues, and suggests some ways forward
Geodesics on the Ellipsoid and Monodromy
The equations for geodesic flow on the ellipsoid are well known, and were
first solved by Jacobi in 1838 by separating the variables of the
Hamilton-Jacobi equation. In 1979 Moser investigated the case of the general
ellipsoid with distinct semi-axes and described a set of integrals which
weren't know classically. After reviewing the properties of geodesic flow on
the three dimensional ellipsoid with distinct semi-axes, we investigate the
three dimensional ellipsoid with the two middle semi-axes being equal,
corresponding to a Hamiltonian invariant under rotations. The system is
Liouville-integrable and thus the invariant manifolds corresponding to regular
points of the energy momentum map are 3-dimensional tori. An analysis of the
critical points of the energy momentum maps gives the bifurcation diagram. We
find the fibres of the critical values of the energy momentum map, and carry
out an analysis of the action variables. We show that the obstruction to the
existence of single valued globally smooth action variables is monodromy.Comment: 24 pages, 7 figure
Phase equilibrium modeling for high temperature metallization on GaAs solar cells
Recent trends in performance specifications and functional requirements have brought about the need for high temperature metallization technology to be developed for survivable DOD space systems and to enhance solar cell reliability. The temperature constitution phase diagrams of selected binary and ternary systems were reviewed to determine the temperature and type of phase transformation present in the alloy systems. Of paramount interest are the liquid-solid and solid-solid transformations. Data are being utilized to aid in the selection of electrical contact materials to gallium arsenide solar cells. Published data on the phase diagrams for binary systems is readily available. However, information for ternary systems is limited. A computer model is being developed which will enable the phase equilibrium predictions for ternary systems where experimental data is lacking
Double non-equivalent chain structure on vicinal Si(557)-Au surface
We study electronic and topographic properties of the vicinal Si(557)-Au
surface using scanning tunneling microscopy and reflection of high energy
electron diffraction technique. STM data reveal double wire structures along
terraces. Moreover behavior of the voltage dependent STM tip - surface distance
is different in different chains. While the one chain shows oscillations of the
distance which are sensitive to the sign of the voltage bias, the oscillations
in the other chain remain unchanged with respect to the positive/negative
biases. This suggests that one wire has metallic character while the other one
- semiconducting. The experimental results are supplemented by theoretical
calculations within tight binding model suggesting that the observed chains are
made of different materials, one is gold and the other one is silicon chain.Comment: 9 pages, 12 figures, accepted for publication in Phys. Rev.
Jet substructure as a new Higgs search channel at the LHC
It is widely considered that, for Higgs boson searches at the Large Hadron
Collider, WH and ZH production where the Higgs boson decays to b anti-b are
poor search channels due to large backgrounds. We show that at high transverse
momenta, employing state-of-the-art jet reconstruction and decomposition
techniques, these processes can be recovered as promising search channels for
the standard model Higgs boson around 120 GeV in mass.Comment: 4 pages, 3 figure
- …