Scaling up orange-fleshed sweetpotato through agriculture and nutrition (SUSTAIN) in Mozambique

SUSTAIN is a 5-year partnership (2013-2018), coordinated by CIP and financed by the UK Department for International Development, to scale up the nutrition benefits of biofortified orange-fleshed sweetpotato (OFSP). The goal is to reach 1.2 million households with under-5 year old children in Kenya, Malawi, Mozambique, and Rwanda. SUSTAIN supports integrated interventions in agriculture, nutrition, utilization, and marketing to strengthen production and consumption of OFSP. This flyer captures the work in Mozambique during the period June 2014 - July 2015

Notes on simplicial rook graphs

The simplicial rook graph ${\rm SR}(m,n)$ is the graph of which the vertices are the sequences of nonnegative integers of length $m$ summing to $n$, where two such sequences are adjacent when they differ in precisely two places. We show that ${\rm SR}(m,n)$ has integral eigenvalues, and smallest eigenvalue $s = \max (-n, -{m \choose 2})$, and that this graph has a large part of its spectrum in common with the Johnson graph $J(m+n-1,n)$. We determine the automorphism group and several other properties

Finite size effects and localization properties of disordered quantum wires with chiral symmetry

Finite size effects in the localization properties of disordered quantum wires are analyzed through conductance calculations. Disorder is induced by introducing vacancies at random positions in the wire and thus preserving the chiral symmetry. For quasi one-dimensional geometries and low concentration of vacancies, an exponential decay of the mean conductance with the wire length is obtained even at the center of the energy band. For wide wires, finite size effects cause the conductance to decay following a non-pure exponential law. We propose an analytical formula for the mean conductance that reproduces accurately the numerical data for both geometries. However, when the concentration of vacancies increases above a critical value, a transition towards the suppression of the conductance occurs. This is a signature of the presence of ultra-localized states trapped in finite regions of the sample.Comment: 5 figures, revtex

Voltage-probe and imaginary potential models for dephasing in a chaotic quantum dot

We compare two widely used models for dephasing in a chaotic quantum dot: The introduction of a fictitious voltage probe into the scattering matrix and the addition of an imaginary potential to the Hamiltonian. We identify the limit in which the two models are equivalent and compute the distribution of the conductance in that limit. Our analysis explains why previous treatments of dephasing gave different results. The distribution remains non-Gaussian for strong dephasing if the coupling of the quantum dot to the electron reservoirs is via ballistic single-mode point contacts, but becomes Gaussian if the coupling is via tunneling contacts.Comment: 9 pages, RevTeX, 6 figures. Mistake in Eq. (35) correcte

Intensity distribution of scalar waves propagating in random media

Transmission of the scalar field through the random medium, represented by the system of randomly distributed dielectric cylinders is calculated numerically. System is mapped to the problem of electronic transport in disordered two-dimensional systems. Universality of the statistical distribution of transmission parameters is analyzed in the metallic and in the localized regimes.In the metallic regime the universality of the transmission statistics in all transparent channels is observed. In the band gaps, we distinguish the disorder induced (Anderson) localization from the tunneling through the system due to the gap in the density of states. We show also that absorption causes rapid decrease of the mean conductance, but, contrary to the localized regime, the conductance is self-averaged with a Gaussian distribution

Large stroke three degree-of-freedom spherical flexure joint

Multi degree of freedom flexure joints are often limited to small deflection angles, because of their strong loss of stiffness in support directions when deflected, or they have a large range of motion but are initially already compliant also in the intended support directions. In this paper, an innovative design for a high performance large stroke spherical flexure joint is presented which can maintain a high level of support stiffness over its full range of motion. A series of flexural topologies are optimized and compared which resulted in a flexure joint design which can achieve a support stiffness of almost 100N/mm at a tilt angle of 30 degrees. Experimental validations have been conducted in order to validate the results and confirm this high level of support stiffness at large tilt angles

Theory of the spin-torque-driven ferromagnetic resonance in a ferromagnet/normal-metal/ferromagnet structure

We present a theoretical analysis of current driven ferromagnetic resonance in a ferromagnet/normal-metal/ferromagnet tri-layer. This method of driving ferromagnetic resonance was recently realized experimentally by Tulapurkar et al. [Nature 438, 339 (2005)] and Sankey et al. [Phys. Rev. Lett. 96, 227601 (2006)]. The precessing magnetization rectifies the alternating current applied to drive the ferromagnetic resonance and leads to the generation of a dc voltage. Our analysis shows that a second mechanism to generate a dc voltage, rectification of spin currents emitted by the precessing magnetization, has a contribution to the dc voltage that is of approximately equal size for the thin ferromagnetic films used in the experiment.Comment: 6 pages, 1 figure, final version. Changed title, updated references, added discussions in section I