Carlos Marques

Methodological aspects of a mathematical programming model to evaluate soil tillage technologies in a risky environment

Abstract In this work we develop a methodology for the economic evaluation of soil tillage technologies, in a risky environment, and to capture the influence of farmer behaviour on his technology choice. The model has short-term activities, that change with the type of year, and long-term activities, in which sets of traction investment activities are included. Although these activities do not change with the type of year, they lead to different availability of resources for each type of year, since the same tractor has different available fieldwork days under different weather conditions. We prove that the model is sensitive to the greater income variability resulting from the use of alternative technologies and to the balance between income and risk, accounting for the probability of occurrence of each state of nature and giving an investment solution that considers the best production plan for each type of year.

A competitividade do regadio em Portugal no contexto da Nova Política Agrícola Comum: o caso de uma exploração agrícola no Alentejo

The 2003 Common Agricultural Policy (CAP) reform consti-tutes a reinforcement of the main objectives of the previous reforms of 1992 and of 2000, namely the promotion of the agricultural competitive-ness, the multiple functions of the rural and agricultural areas and the sustainable resource exploitation. The direct production aids in the most Common Market Organizations are replaced by an only payment for each farm, subject to echo-conditionality and limits on the agricultural systems changes. This article evaluates the impacts of 2003 CAP reform on the Portugal irrigation competitiveness in the Alentejo region farms. The effects of the only payment in the agricultural returns, the main changes in the crop patterns and in the agricultural incomes were studied. They are also appraised direct social economic and environmental impacts of the adjustments produced with the 2003 CAP reform. The followed methodology is a discreet stochastic programming model. This model maximizes the expected income and minimizes the risk at the farm level. It was used to assess the crop patterns and the farm inco-me in the short and in the long term, in the scenarios of the 2000 CAP and the of the 2003 CAP.

Avaliação económica de tarifas de água no uso agrícola: um estudo de caso no Sul de Portugal

This paper evaluates the effects of water tariffs in irrigation, in terms of water consumption, land irrigated, farm income, water cost recovery and agricultural investment. The methodology is based on a multiperiod mathematical programming model, which was applied to the specific characteristics of a representative farm in southern Portugal. The main aspects analyzed were: the fix tariff per area benefited, the volumetric tariff per cubic meter of water consumed, the mix tariff and the increasing block tariff. For the simulations, it was considered a traditional productive scenario and an alternative scenario, which include value added crops.

The xenobiotic sensor PXR in a marine flatfish species (Solea senegalensis): Gene expression patterns and its regulation under different physiological conditions

The pregnane X receptor (PXR) is a nuclear receptor belonging to the NR1I sub-family and a known master regulator of xenobiotic metabolism. New roles have been recently proposed in mammals through its activation by vitamin K (VK) such as regulation of glucose metabolism, bone homeostasis, reproduction, neuronal development and cognitive capacities. In marine fish species little is known about PXR and its potential roles. Here, expression patterns of pxr transcripts and conservation of protein domains were determined in the Senegalese sole (Solea senegalensis), a marine flatfish model species in aquatic ecotoxicology. In addition to a full coding sequence transcript (sspxr1), two variants lacking DNA and/or ligand binding domains (sspxr2 and sspxr3) were also identified. The expression of sspxr1 during early development and in adult tissues was ubiquitous, but highest levels were observed in liver, intestine and skin. Expression was also detected by in situ hybridization in chondrocytes and cells from the granular and inner nuclear layers in three month old fish. Finally, sspxr1 expression was shown to be differentially regulated under physiological conditions related with fasting, VK and warfarin metabolism. The present work provides new and basic knowledge regarding pxr sequence and expression patterns in a marine flatfish species to unveil the potential impact of xenobiotics on marine fish physiology, and will allow a better and more ecosystemic environmental risk assessment of different pollutants over the marine environments with the development of reporter assays using PXR sequences from evolutionary distantly marine species (such as vertebrate and invertebrate marine species).

Efficiency in the European agricultural sector: environment and resources

This article intends to compute agriculture technical efficiency scores of 27 European countries during the period 2005–2012, using both data envelopment analysis (DEA) and stochastic frontier analysis (SFA) with a generalized cross-entropy (GCE) approach, for comparison purposes. Afterwards, by using the scores as dependent variable, we apply quantile regressions using a set of possible influencing variables within the agricultural sector able to explain technical efficiency scores. Results allow us to conclude that although DEA and SFA are quite distinguishable methodologies, and despite attained results are different in terms of technical efficiency scores, both are able to identify analogously the worst and better countries. They also suggest that it is important to include resources productivity and subsidies in determining technical efficiency due to its positive and significant exerted influence.