Roots and tubers for the 21st century: trends, projections and policy options

"...The assessment of past trends, future prospects, and policy options reported here stems from the tradition of joint studies of roots and tubers in developing countries by the Consultative Group on International Agricultural Research (CGIAR). This report builds on that previous collaboration and represents the first intercenter effort to produce future projections of demand and supply for these crops and represents the empirical foundation of a broader effort aimed at documenting not just trends and projections but also describing research activities and organizations with the overall objective of providing a vision for research on roots and tubers in the CGIAR. Gregory J. Scott, Mark W. Rosegrant, and Claudia Ringler have synthesized a significant amount of data and information on roots and tubers in order to provide a clearer vision of their past, present,a nd future roles in the food systems of developing countries. How the production and use of these commodities have changed and will continue to change over time are all the more important to understand because of the contribution they make to the diets and income-generating activities of the rural and urban poor in Asia, Africa, and Latin America. This paper provides a fuller understanding of the prospects of roots and tubers for food, feed, and other uses in developing countries in the decades ahead. " (excerpted from Forward by Per Pinstrup-Andersen and Hubert Zandstra)Tubers Economic aspects Developing countries., Root-crops Economic aspects Developing countries., Agricultural economics and policies., Food supply Developing countries Forecasting., Assessment,

Mixed finite elements for numerical weather prediction

We show how two-dimensional mixed finite element methods that satisfy the conditions of finite element exterior calculus can be used for the horizontal discretisation of dynamical cores for numerical weather prediction on pseudo-uniform grids. This family of mixed finite element methods can be thought of in the numerical weather prediction context as a generalisation of the popular polygonal C-grid finite difference methods. There are a few major advantages: the mixed finite element methods do not require an orthogonal grid, and they allow a degree of flexibility that can be exploited to ensure an appropriate ratio between the velocity and pressure degrees of freedom so as to avoid spurious mode branches in the numerical dispersion relation. These methods preserve several properties of the C-grid method when applied to linear barotropic wave propagation, namely: a) energy conservation, b) mass conservation, c) no spurious pressure modes, and d) steady geostrophic modes on the $f$-plane. We explain how these properties are preserved, and describe two examples that can be used on pseudo-uniform grids: the recently-developed modified RT0-Q0 element pair on quadrilaterals and the BDFM1-\pdg element pair on triangles. All of these mixed finite element methods have an exact 2:1 ratio of velocity degrees of freedom to pressure degrees of freedom. Finally we illustrate the properties with some numerical examples.Comment: Revision after referee comment

Raices y tuberculos para el siglo 21: tendencias, projecciones y opciones de politica

La gran importancia de las raices y tuberculos como fuente de ingresos para los agricultores pobres y como fuente de alimento para la poblacion de escasos recursos, tanto rural como urbana, es muchas veces ignorada en el debate sobre el mejoramiento de la seguridad alimentaria y la erradicacion de la pobreza en los paises en desarrollo. Es de esperarse que los analisis del presente informe, preparados en forma conjunta por el Centro Internacional de la Papa (CIP) y el Instituto Internacional de Investigaciones sobre Politicas Alimentarias (IFPRI), ayudaran a que estos cultivos sean considerados apropiadamente en las deliberaciones futuras sobre el sistema global de alimentos a nivel nacional e internacional, locual aumentaria los esfuerzos para asegurar la seguridad alimentaria e ingresos para todos los habitantes del mundo... Gregory J.Scott, Mark W.Rosegrant, y Claudia Ringler han sintetizado una cantidad significativa de datos sobre raices y tuberculos, en un esfuerzo para brindar una vision mas clara de su pasado, su presente y su papel futuro en los sistemas de alimentos de los paises en desarrollo. Resulta de vital importancia comprender como han cambiado y como cambiaran en el futuro la produccion y el uso de estos productos primarios a lo largo del tiempo, debido justamente a su contribucion en las dietas y en las actividades generadoras de ingresos de la poblacion pobre, rural y urbana en Asia, Africa y America Latina.Tubers Economic aspects Developing countries., Root-crops Economic aspects Developing countries., Food supply Developing countries., tuberculo, plantas de raices comestibles, economia agricola,

Lizards lack speed-accuracy trade-offs in a quantitative foraging task when unable to sample the reward.

To make decisions, animals gather information from the environment in order to avoid costs (e.g., reduced survival) and increase benefits (e.g., foraging success). When time is limited or information is insufficient, most animals face a speed-accuracy trade-off (SAT) - they have to balance the benefits of making quick decisions against the costs of inaccurate decisions. Here, we investigated the relationship between decision accuracy and decision speed in gidgee skinks (Egernia stokesii) performing a food-based spontaneous quantity discrimination task. Rather than a SAT we found a speed-accuracy alignment; lizards made decisions that were fast and accurate, rather than inaccurate. Furthermore, we found only within-, but no between-individual, differences in decision making indicating behavioural plasticity in the absence of individual decision styles. Finally, latency to choice was highly repeatable, more so than choice accuracy. Previous work has shown that learning, the costs of a bad decision and task difficulty frequently result in SATs. The lack of a SAT in our lizards might be a direct consequence of our simple testing methodology which prevented learning by not allowing lizards to consume the chosen quantity. To fully understand how SATs develop, different methodologies that control the costs and benefits of decisions should be compared

Seasonal variation in maternal dietary diversity is reduced by small-scale irrigation practices: a longitudinal study

Some agricultural practices, such as irrigation, have the potential to buffer seasonal dietary gaps and through increased production and consumption improve diets, particularly of the rural poor relying on subsistence farming but also for rural and urban households purchasing irrigated produce on local markets. The study aimed to evaluate the effect of seasonality and irrigation on women's diet in rural Ethiopia. Using a longitudinal study design, three rounds of surveys were conducted among women of reproductive age (15–49 years). Data on socioeconomic status, food consumption and haemoglobin concentration was collected. Energy and nutrient intakes were estimated using an interviewer-administered multiple-pass 24-h recall. Women's dietary diversity score (WDDS), the proportion of women meeting the minimum dietary diversity for women (MDDW), haemoglobin concentration, the prevalence of anaemia and energy and nutrients intakes were compared between irrigators and nonirrigators and by season. Associations between MDDW/WDDS and irrigation status were assessed using fixed-effect models, after adjusting for covariates. WDDS was low (3–4 out of 10 food groups) and exhibited high seasonal variability (p < 0.05). Diets were predominantly cereal-based, with little consumption of nutrient-dense foods like fruits and animal source foods. High seasonal variability in energy, protein, vitamin C, calcium, iron and zinc intakes were observed (p < 0.01). Irrigators were more likely to meet the MDDW than women from non-irrigating households (p < 0.05). No cases of malaria were reported from the three rounds of screening. There is a high seasonal variation in women's diet, but this could be partly offset by irrigation practices

Numerical wave propagation on the hexagonal C-grid

Copyright © 2008 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Computational Physics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Computational Physics, Vol. 227, Issue 11 (2008), DOI: 10.1016/j.jcp.2008.02.010Inertio-gravity mode and Rossby mode dispersion properties are examined for discretizations of the linearized rotating shallow water equations on a regular hexagonal C-grid in planar geometry. It is shown that spurious non-zero Rossby mode frequencies found by previous authors in the f-plane case can be avoided by an appropriate discretization of the Coriolis terms. Three generalizations of this discretization that conserve energy even for non-constant Coriolis parameter are presented. A quasigeostrophic ββ-plane analysis is carried out to investigate the Rossby mode dispersion properties of these three schemes. The Rossby mode dispersion relation is found to have two branches. The primary branch modes are good approximations, in terms of both structure and frequency, to corresponding modes of the continuous governing equations, and offer some improvements over a quadrilateral C-grid scheme. The secondary branch modes have vorticity structures approximating those of small-scale modes of the continuous governing equations, suggesting that the hexagonal C-grid might have an advantage in terms of resolving extra Rossby modes; however, the frequencies of the secondary branch Rossby modes are much smaller than those of the corresponding continuous modes, so this potential advantage is not fully realized

A unified approach to energy conservation and potential vorticity dynamics for arbitrarily-structured C-grids

Copyright © 2010 Elsevier. NOTICE: this is the author’s version of a work that was accepted for publication in Journal of Computational Physics. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Computational Physics, Vol. 229, Issue 9 (2010), DOI: 10.1016/j.jcp.2009.12.007A numerical scheme applicable to arbitrarily-structured C-grids is presented for the nonlinear shallow-water equations. By discretizing the vector-invariant form of the momentum equation, the relationship between the nonlinear Coriolis force and the potential vorticity flux can be used to guarantee that mass, velocity and potential vorticity evolve in a consistent and compatible manner. Underpinning the consistency and compatibility of the discrete system is the construction of an auxiliary thickness equation that is staggered from the primary thickness equation and collocated with the vorticity field. The numerical scheme also exhibits conservation of total energy to within time-truncation error. Simulations of the standard shallow-water test cases confirm the analysis and show convergence rates between 1st1st- and 2nd2nd-order accuracy when discretizing the system with quasi-uniform spherical Voronoi diagrams. The numerical method is applicable to a wide class of meshes, including latitude–longitude grids, Voronoi diagrams, Delaunay triangulations and conformally-mapped cubed-sphere meshes

The role of water in transforming food systems

The United Nations Food Systems Summit aimed to chart a path toward transforming food systems toward achieving the Sustainable Development Goals. Despite the essentiality of water for food systems, however, the Summit has not sufficiently considered the role of water for food systems transformation. This focus is even more important due to rapidly worsening climate change and its pervasive impacts on food systems that are mediated through water. To avoid that water "breaks" food systems, key food systems actors should 1) Strengthen efforts to retain water-dependent ecosystems, their functions and services; 2) Improve agricultural water management; 3) Reduce water and food losses beyond the farmgate; 4) Coordinate water with nutrition and health interventions; 5) Increase the environmental sustainability of food systems; 6) Explicitly address social inequities; and 7) Improve data quality and monitoring for water-food system linkages