Agricultural research for resource-poor farmers: the farmer-first-and-last model

Rural poverty is much less a problem of total food availability than of who produces the food and who has the income to buy it. A high priority is therefore to enable the tens of millions of resource-poor farm families to increase their production and improve its stability. The normal transfer-of- technology (TOT) model for agricultural research has built-in biases which favour resource-rich farmers whose conditions resemble those of research stations. TOT approaches have been modified through on-farm trials and demonstrations but the basic model and approach remain the same. A second emerging model is farmer-first-and-last (FFL). This starts and ends with the farm family and the farming system. It begins with holistic and interdisciplinary appraisal of farm families' resources, needs and problems, and continues with on-farm and with-farmer R and D, with scientists, experiment stations and laboratories in a consultancy and referral role. FFL fits the needs and opportunities of resource-poor farm families better than TOT, but there are obstacles to its development and introduction. These can be tackled step-by-step, through combinations of methodological innovation, interdisciplinarity, including the social sciences, and provision of suitable resources, rewards and training. FFL approaches promise a greater contribution from agricultural research to the eradication of rural poverty

Effect of column base strength on steel portal frames in fire

In the UK, the design of steel portal frame buildings in fire is based on the Steel Construction Institute (SCI) design method, in which fire protection needs only be provided to the columns, provided that the column bases are designed to resist an overturning moment, M_OTM, calculated in accordance with the SCI design method. In this paper, a non-linear elastic-plastic implicit dynamic finite element model of a steel portal frame building in fire is described and used to assess the adequacy of the SCI design method. Both 2-D and 3-D models are used to analyse a building similar to the Exemplar frame described in the SCI design guide. Using the 2-D model, a parametric study comprising 27 frames is conducted. It is shown that the value of the overturning moment, calculated in accordance with the SCI design method, may not be sufficient to prevent collapse of the frame before 890 °C

Agroforestry: a complex system for resource-poor farmers

Paper for the Indian Society of Tree Scientists Satellite Session on Agroforestry, Birla Institute of Technology, Ranchi, Bihar, 2 January 1984 and for the Ford FoundationAgroforestry has potential as a technology for resource-poor farmers. Like modern high-yield intercropping systems, agroforestry has several characteristics of interest: (1) complexity, .(2) productivity, (3) risk; and (4) investment. Each characteristic has potential advantages and disadvantages for the poor which can be manipulated and improved with applied research

Design of top-hat purlins for cold-formed steel portal frames

This paper considers the use of cold-formed steel top-hat sections for purlins in the UK, as an alternative to conventional zed-sections. The use of such top-hat sections could be viable for cold-formed steel portal framing systems, where both the frame spacing and purlin span may be smaller than that of conventional hot-rolled steel portal frames. Furthermore, such sections are torsionally stiffer than zed-sections, and so have a greater resistance to lateral-torsional buckling. They also do not require the installation of anti-sag rods. The paper describes a combination of full-scale laboratory tests and non-linear elasto plastic finite element analyses. The results of twenty-seven tests on four different top-hat sections are presented. In terms of stiffness, good agreement between the experimental and finite element results is shown. The finite element model is then used for a parametric study to investigate the effect of different thicknesses and steel grades. Design recommendations are provided in the form of charts. The use of the finite element method in this way exploits modern computational techniques for an otherwise difficult structural design problem and reduces the need for an expensive and time consuming full laboratory study, whilst maintaining realistic and safe coverage of the important structural design issues

45CaCl2 autoradiography in brain from rabbits with encephalopathy from acute liver failure or acute hyperammonemia

In experimental hepatic encephalopathy and hyperammonemia, extracellular levels of glutamate are increased in hippocampus and cerebral cortex. It has been suggested that overstimulation of glutamate receptors causes a pathological entry of calcium into neurons via receptor-operated (NMDA- and AMPA-type) or voltage-dependent calcium channels leading to calcium overload and cell death. Neurodegeneration as a result of exposure to excitotoxins, including glutamate, can be localized and quantified using45CaCl2 autoradiography. This approach was used to study cerebral calcium accumulation in rabbits with acute liver failure and acute hyperammonemia. Acute liver failure was induced in 6 rabbits, acute hyperammonemia in 4 rabbits; 4 control rabbits received sodium-potassium-acetate. At the start of the experiment 500 µCi45CaCl2 was given intravenously. After development of severe encephalopathy, the animals were killed by decapitation. All rabbits with acute liver failure or acute hyperammonemia developed severe encephalopathy, after 13.2±1.7 and 19.3±0.5 hours respectively (mean±SEM). Plasma ammonia levels were 425±46 and 883±21 µmol/l, respectively (p<0.05). Control rabbits maintained normal plasma ammonia levels (13±5 µmol/l), demonstrated normal behaviour throughout the study and were sacrificed after 16 hours.45Ca2+-autoradiograms of 40 µm brain sections were analyzed semiquantitatively using relative optical density and computerized image analysis. As compared to background levels45Ca was not increased in hippocampus or any other brain area of rabbits with severe encephalopathy from acute liver failure or acute hyperammonemia. This suggests that, despite increased extracellular brain glutamate levels in these conditions, glutamate neurotoxicity was not important for the development of encephalopathy in these rabbits

1,8-Naphthalimide based fluorescent sensors for enzymes

Fluorescent probes have long been valuable tools in the study of biological systems. With the ever-expanding range of known enzymatic biomarkers for disease, it has never been more important to develop synthetically facile, sensitive, selective, and robust methods for the detection of these analytes. The 1,8-naphthalimide fluorophore presents an ideal scaffold on which to design a range of fluorescent probes for an unknowable diversity of biomarkers. With tuneable photophysical properties, synthetic versatility, photostability and a large Stokes shift, the 1,8-naphthalimide has, and continues to be, exploited for the detection of a wide range of enzymatic conversions. This review will outline the recent progress towards the design and synthesis of 1,8-naphthalimide fluorophores for the detection of selected enzymatic conversions