Constraints in the post-harvest processing of cassava at household level in two districts of southern Tanzania

This project, funded by the Overseas Development Administration (ODA), aims to improve rapid cassava processing methods in rural households where a need is evident. The development and adoption of appropriate processing methods will be through participatory research involving, to a high degree, those who will use the technology. The project is being undertaken in partnership with the Tanzania Food and Nutrition Centre, as lead collaborator; Regional Agriculture and Livestock Development Office, Mtwara; Agricultural Research Institute Naliendele, Mtwara; and Rural Integrated Project Support Programme, a FINNIDA funded project in Mtwara and Lindi. This participatory rural appraisal (PRA) study included eight villages in two districts of Southern Tanzania and aimed to: (1) obtain an inventory of existing traditional processing methods; (2) document information on farmers and processors preferences for processed products and situations that influence their choice of processing method, such as varietal preferences, storability, food safety, marketing and indigenous knowledge; (3) identify processing needs and constraints to develop improved processing methods; and (4) learn from the experiences of previous cassava processing technology transfer activities undertaken by the extension services

High-frequency homogenization for periodic media

This article is available open access through the publisher’s website at the link below. Copyright @ 2010 The Royal Society.An asymptotic procedure based upon a two-scale approach is developed for wave propagation in a doubly periodic inhomogeneous medium with a characteristic length scale of microstructure far less than that of the macrostructure. In periodic media, there are frequencies for which standing waves, periodic with the period or double period of the cell, on the microscale emerge. These frequencies do not belong to the low-frequency range of validity covered by the classical homogenization theory, which motivates our use of the term ‘high-frequency homogenization’ when perturbing about these standing waves. The resulting long-wave equations are deduced only explicitly dependent upon the macroscale, with the microscale represented by integral quantities. These equations accurately reproduce the behaviour of the Bloch mode spectrum near the edges of the Brillouin zone, hence yielding an explicit way for homogenizing periodic media in the vicinity of ‘cell resonances’. The similarity of such model equations to high-frequency long wavelength asymptotics, for homogeneous acoustic and elastic waveguides, valid in the vicinities of thickness resonances is emphasized. Several illustrative examples are considered and show the efficacy of the developed techniques.NSERC (Canada) and the EPSRC

Species-specific calcite production reveals Coccolithus pelagicus as the key calcifier in the Arctic Ocean

Through the production and export of their calcite coccoliths, coccolithophores form a key component of the global carbon cycle. Despite this key role, very little is known about the biogeochemical role of different coccolithophore species in terms of calcite production, and how these species will respond to future climate change and ocean acidification. Here, we present the first study to estimate species-specific calcite production, from samples collected in the Arctic Ocean and subarctic Iceland Basin in June 2012. We show that although the coccolithophorid Coccolithus pelagicus comprised only a small fraction of the total community in terms of abundance (2%), our estimates indicate that it was the major calcite producer in the Arctic Ocean and Iceland Basin (57% of total calcite production). In contrast, Emiliania huxleyi formed 27% of the total abundance and was responsible for only 20% of the calcite production. That C. pelagicus was able to dominate calcite production was due to its relatively high cellular calcite content compared with the other species present. Our results demonstrate, for the first time, the importance of investigating the complete coccolithophore community when considering pelagic calcite production, as relatively rare but heavily calcified species such as C. pelagicus can be the key calcite producers in mixed communities. Therefore, the response of C. pelagicus to ocean acidification and climate change has the potential to have a major impact on carbon cycling within the North Atlantic and Arctic Ocean

A Universal Method for Analysing Copolymer Growth

Polymers consisting of more than one type of monomer, known as copolymers, are vital to both living and synthetic systems. Copolymerisation has been studied theoretically in a number of contexts, often by considering a Markov process in which monomers are added or removed from the growing tip of a long copolymer. To date, the analysis of the most general models of this class has necessitated simulation. We present a general method for analysing such processes without resorting to simulation. Our method can be applied to models with an arbitrary network of sub-steps prior to addition or removal of a monomer, including non-equilibrium kinetic proofreading cycles. Moreover, the approach allows for a dependency of addition and removal reactions on the neighbouring site in the copolymer, and thermodynamically self-consistent models in which all steps are assumed to be microscopically reversible. Using our approach, thermodynamic quantities such as chemical work; kinetic quantities such as time taken to grow; and statistical quantities such as the distribution of monomer types in the growing copolymer can be derived either analytically or numerically directly from the model definition.Comment: 24 pages, 11 figure

Tumour-associated immune responses and isolated carcinoembryonic antigen and alpha feto-protein levels related to survival in ovarian cancer patients.

The presence of a tumour-associated immune response in 37 patients with ovarian cancer as assessed by blastogenesis (lymphocyte transformation) evoked by ovarian cancer cell extracts, has been correlated with survival following the test. The difference in these responses is unlikely to be accounted for on the basis of general impairment of cell-mediated immuno-competence. Serum carcinoembryonic antigen (CEA) was also determined in 27 ovarian cancer patients to assess its prognostic significance. Raised CEA levels and absence of blastogenic response to tumour cell extract during relapse are associated with a worse prognosis but neither of these parameters are significant in remission. Possible applications of these findings to the clinical management of ovarian cancer patients are discussed. Serum alpha feto-protein levels measured by radioimmunoassay were not found to be raised in any of the 32 ovarian cancer patients in whom it was measured

Coordination risk and cost impacts on economic development in poor rural areas

This paper addresses issues relevant to a critical problem in economic development: how to get rapid pro-poor economic growth in poor rural areas in Africa and South Asia where most of the world’s dollar a day poor live. It examines constraints to the development of coordinated exchange systems in poor rural areas, focusing on the core problem of thin markets and low density of economic activity in these areas. Transaction cost and risk analysis is integrated into a conventional neoclassical production economics framework to describe the existence of low level equilibrium traps in transactions and supply chains and to generate important insights for development policy