Combining multi-dimensional scaling and cluster analysis to describe the diversity of rural households

Capturing agricultural heterogeneity through the analysis of farm typologies is key with regard to the design of sustainable policies and to the adoptability of new technologies. An optimal balance needs to be found between, on the one hand, the requirement to consider local stakeholder and expert knowledge for typology identification, and on the other hand, the need to identify typologies that transcend the local boundaries of single studies and can be used for comparisons. In this paper, we propose a method that supports expert-driven identification of farm typologies, while at the same time keeping the characteristics of objectivity and reproducibility of statistical tools. The method uses a range of multivariate analysis techniques and it is based on a protocol that favours the use of stakeholder and expert knowledge in the process of typology identification by means of visualization of farm groups and relevant statistics. Results of two studies in Zimbabwe and Kenya are shown. Findings obtained with the method proposed are contrasted with those obtained through a parametric method based on latent class analysis. The method is compared to alternative approaches with regard to stakeholder-orientation and statistical reliability. (Résumé d'auteur

Pulsars as Fantastic Objects and Probes

Pulsars are fantastic objects, which show the extreme states of matters and plasma physics not understood yet. Pulsars can be used as probes for the detection of interstellar medium and even the gravitational waves. Here I review the basic facts of pulsars which should attract students to choose pulsar studies as their future projects.Comment: Invited Lecture on the "First Kodai-Trieste Workshop on Plasma Astrophysics", Kodaikanal Obs, India. Aug.27-Sept.7th, 2007. In: "Turbulence, Dynamos, Accretion Disks, Pulsars and Collective Plasma Processes". Get a copy from: http://www.springerlink.com/content/978-1-4020-8867-

An environmental-economic framework to support multi-objective policy-making

Keywords: environmental accounting, environmental indicators, farming systems, sustainability, organic farming, ecological-economic modelling, spatial analysis, multi-objective policy-making, opportunity cost.There is a growing awareness in present-day society of the potential of sustainable farming systems to enhance wildlife and the landscape and to decrease environmental harm caused by farming practices. EU commitment to integrate environmental considerations into agricultural political agenda has resulted in the adoption of environmental cross-compliance and agri-environment support schemes. Sustainability can only be achieved through multi-objective policy tools. Furthermore, more insight is needed into the environmental-economic tradeoffs of farming systems to direct policy interventions towards sustainable development of rural areas. The main objective of the present research is to provide an environmental-economic framework for the design and evaluation of agricultural policy schemes aimed at the operationalisation of sustainability in agricultural areas. The research involved designing and applying (1) an environmental accounting information system (EAIS), and (2) an integrated ecological-economic model to evaluate sustainability of farming systems. First, the EAIS together with a set of economic indicators was applied to three case study farms representing organic, integrated and conventional farming systems. Results showed that organic farming systems have the potential to improve the efficiency of many environmental indicators in addition to being remunerative. Environmental performances of all farming systems analysed were consistently affected by pedo-climatic factors on a regional as well as on a site scale. Subsequently, the EAIS indicators were integrated with farm records from one of the case studies and were used as a data source for the construction of an integrated ecological-economic model. The model was first used to evaluate the impact of current (Agenda 2000) and previous (MacSharry reform) agro-environment regimes on sustainability of organic farming systems. Then, the model was used to analyse the impact of Agenda 2000 common market organisation and agri-environment schemes on conventional and organic farming systems. Results indicated that the level of sustainability achieved with organic farming was satisfactory under both the MacSharry reform and the Agenda 2000 regulations. Optimising the model under different policy scenarios confirmed that organic farming systems are environmentally more beneficial than conventional farming systems. Combining the model with sensitivity and scenario analyses enabled an evaluation of the opportunity costs incurred by farmers to supply environmental amenities. Finally, the use of such information to back policy decisions is discussed

Evaluation of sustainability of organic, integrated and conventional farming systems: a farm and field-scale analysis

Agricultural researchers widely recognise the importance of sustainable agricultural production systems and the need to develop appropriate methods to measure sustainability. The principal purpose of this paper is to evaluate the financial and environmental aspects of sustainability of organic, integrated and conventional farming systems (OFS, IFS and CFS, respectively) at farm level and on more detailed spatial scales. This was achieved by applying an integrated economic-environmental accounting framework to three case study farms in Tuscany (Italy) covering different farming systems (FSs) and different spatial scales. The environmental performances of the FSs were measured through the application of an environmental accounting information system (EAIS) at field, site and farm level. The EAIS indicators were then integrated with: (1) a set of financial indicators to evaluate the economic and environmental trade-offs between different FSs and (2) with information on the regional and site-specific soil and climate conditions to study the impact of different pedo-climates on the environmental performances of the FSs. The gross margins of steady-state OFSs were found to be higher than the corresponding CFS gross margins. The OFSs perform better than IFSs and CFSs with respect to nitrogen losses, pesticide risk, herbaceous plant biodiversity and most of the other environmental indicators. However, on hilly soils, erosion was found to be higher in OFSs than in CFSs. The pesticide and the nitrogen indicators in this study showed a similar environmental impact caused by integrated and conventional farming practices. Regional pedo-climatic factors were found to have a considerable impact on nutrient losses, soil erosion, pesticide risk and herbaceous plant biodiversity, site-specific: factors on nutrient losses and soil erosion. Results at field level suggest that herbaceous plant biodiversity and crop production are not always conflicting variables. Results of the case study farms are discussed and compared with environmental sustainability thresholds reported from EU Directives on nitrate and pesticides in groundwater and the literature. (C) 2002 Elsevier Science B.V. All rights reserved

The EU's agenda 2000 reformand the sustainability of organic farming in Tuscany: ecological-econmic modelling at field and farm level

Sustainability has become a central issue in the agricultural sector, both for researchers, producers and policy-makers. The two main objectives of this paper are: (1) to present an holistically designed ecological-economic model to evaluate farm and field-level environmental-economic tradeoffs with special reference to multi-objective policy-making and (2) to evaluate the impact of the Agenda 2000 reform on sustainability of organic farming. The model was implemented for the case of organic dairy farming in northern Tuscany (Italy). Minor differences were found between the environmental and technical results of the model under the MacSharry and Agenda 2000 reforms. However, gross margins under the Agenda 2000 regulations were considerably higher. The spatial detail of the model proved particularly useful in the evaluation of the impact of environmental sustainability thresholds. Sensitivity analysis indicated the weak environmental points of the farming system (in this case mainly soil erosion) and the feasible levels of the various environmental aspects and their associated socio-economic costs. The application of the model for alternative policy scenarios provided insights into ways in which the cost economic efficiency of the Agenda 2000 agri-environment support scheme could be improved. The paper concludes with suggestions for further model research to contribute to the design of cost-efficient agri-environment payment schemes. (C) 2003 Elsevier Ltd. All rights reserved

Simulating soil fertility management effects on crop yield and soil nitrogen dynamics in field trials under organic farming in Europe

Soil fertility building measures should be explored at the short and long-term for an adequate evaluation of their impact on sustaining yields and of its environmental consequences in crop rotations under organic farming. For such a purpose, process-based crop models are potential useful tools to complement and upscale field observations under a range of soil and climatic conditions. Organic rotations differ in soil fertility dynamics in comparison to conventional farming but very few modelling studies have explicitly considered this specific situation. Here, we evaluate the FASSET model to predict the effects of different fertility management options in organic crop rotations on dry matter (DM) and nitrogen (N) yield, and soil N dynamics, including N2O emissions. For that, we used data from seven short and long-term field experiments in different agro-climatic environments in Europe (Norway, Denmark, Poland, Switzerland, Italy and Spain) including climate, soil and management data. Soil fertility building measures covered fertilization type, green manures, cover crops, tillage, crop rotation composition and management (organic or conventional). Model performance was evaluated by comparing observed and simulated values of crop DM and N yield, soil mineral N and nitrous oxide (N2O) emissions using five complementary statistical indices. The model closely reproduced most observed DM and N yield trends and effects of soil fertility building measures in arable crops, particularly in cereals. Contrary, yields of grass-clover, especially N, were generally reproduced with low degree of accuracy. Model performance for simulating soil mineral N depended on site and the availability of soil and management information. Although high uncertainty was associated to the simulation of soil N dynamics, differences of cumulative N2O emissions between fertility building measures were reflected in model outputs. Aspects for modelling improvement include cover crop growth and decomposition, biological N fixation (BNF) or weed and pest soil-crop interactions. It is concluded that FASSET can be successfully used to investigate the impact of fertilization type, green manures, tillage and management (organic or conventional) on crop productivity and to a certain extent on soil N dynamics including soil N2O emissions at different soils and climates in organic farming in Europe

Plasma clearance rate of 51Cr-EDTA provides a precise and convenient technique for measurement of glomerular filtration rate in diabetic humans

It has not yet been fully clarified whether the plasma or renal clearance approach is the most reliable to investigate GFR in humans. The study presented here aimed to compare plasma decay with renal clearance of 51Cr-EDTA in 27 diabetic patients with patterns of renal function broadly dispersed in a wide range of values. Moreover, the comparison was also performed with renal clearance of nonlabeled iothalamate in a subgroup of 17 patients. A biexponential function was found to fulfill statistical and heuristic criteria for the modeling analysis of plasma 51Cr-EDTA decay with 19 samples after bolus intravenous 51Cr-EDTA injection. Individual GFR values from 51Cr-EDTA plasma clearance highly correlated with those from renal clearance (r2 = 0.977, P < 0.0001), but resulted on average about 2.5 mL.min-1.1.73 m-2 higher (66.8 +/- 6.5 mL.min-1.1.73 m-2 (mean +/- SE) versus 64.3 +/- 6.4, P < 0.02). This difference remained relatively constant from patients with normal renal function to those with impaired renal function, suggesting that the plasma clearance is slightly less accurate than renal clearance approach because of a constant extrarenal clearance rate. In the subgroup studied, a similar difference was found between GFR values from 51Cr-EDTA plasma clearance (84.7 +/- 7.3) and renal clearance of iothalamate (82.8 +/- 7.3), although not statistically significant (P = 0.4). Individual GFR values well correlated (r2 = 0.913, P < 0.0001). The precision and reproducibility of the experimental approaches were assessed by comparing three coefficients of variation: (1) CVb of the bolus injection, because of measurement errors; (2) CVc of the continuous infusion, which additionally includes errors of urine volume measurement and physiological variability in the same day; and (3) CVr of repeated measurements by using bolus injection, which also accounts for physiological variability in different days. CVc of iothalamate and 51Cr-EDTA infusions were 7.5 +/- 1.9% and 7.4 +/- 1.2% respectively. CVb and CVr of bolus injection of 51Cr-EDTA were 2.6 +/- 0.3% and 3.5 +/- 0.8% respectively. CVb and CVr of bolus injection of 51Cr-EDTA, but not CVc of iothalamate and 51Cr-EDTA infusions were twofold to tenfold lower than the percent yearly change reported in IDDM and NIDDM patients. More particularly, CVr was significantly less than CVc. In order to make the test less cumbersome, a reduced sampling schedule with seven samples was designed and validated. GFR measured with seven samples was 66.1 +/- 6.4 (P = 0.1 when compared with the full 19-sample schedule) with a CVb of 3.5 +/- 0.5%. This seven-sample protocol was not different from that obtained with the previously described simplified method of Br\uf8chner-Mortensen (63.9 +/- 6.8, P = 0.16), yet yielding a statistically more accurate estimate (coefficient of variation for Br\uf8chner-Mortensen method = 12.1 +/- 2.9, P = 0.004). Moreover, only bolus injection, along with modeling analysis of plasma clearance rate, allows the accurate measurement of the extracellular fluid volume, an important parameter in diabetic patients. It was concluded that the reduced seven-plasma sample protocol is able to detect as small as 4 to 5% changes per year in a single patient. Moreover, it provides precise and accurate estimate of GFR in diabetic patients with hyperfiltration, who are postulated to be at higher risk to develop renal damag