Assessing the ecological soundness of organic and conventional agriculture by means of life cycle assessment (LCA) - a case study of leek production

Purpose – Sustainable agriculture implies the ability of agro-ecosystems to remain productive in the long-term. It is not easy to point out unambiguously whether or not current production systems meet this sustainability demand. A priori thinking would suggest that organic crops are environmentally favourable, but may ignore the effect of reduced productivity, which shifts the potential impact to other parts of the food provision system. The purpose of this paper is to assess the ecological sustainability of conventional and organic leek production by means of life cycle assessment (LCA). Design/methodology/approach – A cradle-to-farm gate LCA is applied, based on real farm data from two research centres. For a consistent comparison, two functional units (FU) were defined: 1ha and 1?kg of leek production. Findings – Assessed on an area basis, organic farming shows a more favourable environmental profile. These overall benefits are strongly reduced when the lower yields are taken into account. Related to organic farming it is therefore important that solutions are found to substantially increase the yields without increasing the environmental burden. Related to conventional farming, important potential for environmental improvements are in optimising the farm nutrient flows, reducing pesticide use and increasing its self-supporting capacity. Research limitations/implications – The research is a cradle-to-farm gate LCA, future research can be expanded to comprise all phases from cradle-to-grave to get an idea of the total sustainability of our present food consumption patterns. The research is also limited to the case of leek production. Future research can apply the methodology to other crops. Originality/value – To date, there is still lack of clear evidence of the added value of organic farming compared to conventional farming on environmental basis. Few studies have compared organic and conventional food production by means of LCA. This paper addresses these issues

Local vs. long-range infection in unidimensional epidemics

We study the effects of local and distance interactions in the unidimensional contact process (CP). In the model, each site of a lattice is occupied by an individual, which can be healthy or infected. As in the standard CP, each infected individual spreads the disease to one of its first-neighbors with rate $\lambda$, and with unitary rate, it becomes healthy. However, in our model, an infected individual can transmit the disease to an individual at a distance $\ell$ apart. This step mimics a vector-mediated transmission. We observe the host-host interactions do not alter the critical exponents significantly in comparison to a process with only L\'evy-type interactions. Our results confirm, numerically, early field-theoretic predictions.Comment: 8 pages, 6 figures, to appear on Frontiers in Physic

Environmental Variations Drive Polyploid Evolution In Neotropical Eugenia Species (myrtaceae)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Polyploidy is one of the most important mechanisms of speciation and diversification in plant evolution. Polyploidy results in genetic variation among individuals of the same species and even between populations, and may be responsible for differences in environmental tolerance between populations of the same species. This study determined chromosome numbers of Eugenia L. (Myrtaceae, x = 11) for 26 populations of 14 species by conventional cytogenetic techniques. Nine species (13 populations) were diploid (2n = 2x = 22), but diploid and/or polyploid cytotypes were found in the other five species (13 populations), with 2n = 33, 2n = 44, and 2n = 55. Data on chromosome number/ploidy level for other Eugenia species/populations analysis. For each collection point (32 species and 62 populations), environmental variables were recorded using georeferencing techniques through the DIVA-GIS v.7.5 program. Environmental variables such as temperature, altitude, rainfall, solar radiation, soil type, and vegetation were analyzed with the R program, using Mann-Whitney and chi-square tests, principal component analysis, and graphic analyses, such as scatterplots, boxplots, and barplot. Polyploid and diploid populations had different spatial distribution patterns and were found in areas subjected to different environmental conditions. Polyploid individuals were collected from locations with more adverse environmental conditions, usually at higher elevations than the diploid individuals. Polyploidy allows species to occur at locations with varying environmental conditions. As diploidy and polyploidy occur under different environmental conditions, species with cytotypes exhibit wide environmental tolerance.154CAPESCNPq - Conselho Nacional de Desenvolvimento Cientifico e tecnologicoFUNCAP - Fundacao Cearense de Apoio ao Desenvolvimento Cientifico e Tecnologico [10582430-5]CNPq [479263/2011-6, 471065/2004-8]FAPESP - Fundacao de Amparo a Pesquisa do Estado de Sao Paulo [04/13041-8, 01/13169-6]Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

SIMULATION OF THE TEMPERATURE PROFILE OF A PECTIN SOLUTION IN A PLATE HEAT EXCHANGER: A NON-LINEAR SYSTEM APPROACH FOR CONTROL

Experimental measurement can be made only of inlet and outlet global temperature of plate heat exchanger (PHE), therefore the temperature profile along of a PHE is hardly ever known. The goal of this work was to evaluate the influence of a non-Newtonian behavior of pectin solution in the temperature response curves along of the PHE. The results were obtained using a simulation codified in Matlab 6.1 software. The response curves resulted from the simulations were fitted to models for identification and characterization of the system linearity. The result shows a clear non-linear behavior of the response curves along the PHE