Pork Value Chains: A Comparison of Catalonia, Spain and Manitoba, Canada

The purpose of this paper is to provide a comparative analysis of pork value chains in Catalonia, Spain and Manitoba, Canada. Intensive hog production models were implemented in Catalonia in the 1960s as a result of agriculture crises and fostered by feedstuffs factories. The expansion of the hog sector in Manitoba is more recent (in the 1990s) and brought about in large part by the opening of the Maple Leaf Meats processing plant in Brandon, Manitoba. This plant is capable of processing 90,000 hogs per week. Both hog production models ‐ the ‘older’ one in Catalonia (Spain) and the ‘newer’ in Manitoba‐ have been, until recently, examples of success. Inventories and production have been increasing substantially and both regions have proven to have great export potential. Recently, however, tensions have been developing with the hog production models of both regions, particularly as they relate to environmental concerns. The purpose of the paper is to compare the value chains with respect to their origins (e.g. supply a growing demand for pork, ensure farm profitability) and present states (e.g. environmental concerns, profitability). Keywords: pork value chain, hog farms, agri‐food studies. JEL: Q10, Q13, O57

Implementació dels codis de Golay en el paquet matemàtic SAGE

La motivació del present treball va sorgir de la necessitat de descodificar els codis de Golay, un tipus de codis lineals perfectes, en el paquet matemàtic Sage. Sage és un paquet software de lliure distribució i en actual desenvolupament i popularització destinat a aglutinar les funcionalitats de part dels paquets d'anàlisi matemàtic, calculadors simbòlics i manipuladors algebraics propietaris com Mathematica, Matlab, Maple, Magma. En el document es descriurà la implementació realitzada, destacant-ne els aspectes més rellevants. Per a tal efecte, es donarà una introducció als codis lineals i als seus aspectes matemàtics tant des de la vessant de la definició com de les propietats; i al paquet Sage.

Norbert Elias : una proposta d’intellectual portrait vint anys després de la seva mort

L’estiu de 1990 moria a Amsterdam un dels sociòlegs més preeminents del segle XX, l’alemany Norbert Elias. La seva vida i la seva obra, profundament imbricades, són un reflex de la complexitat, de les llums i les ombres del segle passat. Amb aquesta proposta de retrat intel·lectual pretenem per una banda commemorar l’efemèride dels 20 anys de la mort d’un sociòleg poc reconegut i poc emprat. I d’altra banda, oferir una introducció a un personatge i una obra que, per la seva magnitud i originalitat, mereixen estar entre les més rellevants de la sociologia. Com a fil conductor de l’article proposem una combinació de llocs físics i simbòlics que van marcar la seva trajectòria.

Hydrology, light and the use of organic and inorganic materials as structuring factors of biological communities in Mediterranean streams

Hydrological disturbances, light availability and nutrients are the most relevant factors determining the structure of the biological communities in Mediterranean rivers. While some hydrological disturbances are able to induce catastrophic effects, which may cause a complete reset in physical and biological conditions, continued enrichment or changes in light availability are factors leading to the progressive shift in the communities of autotrophs and heterotrophs in the systems. Primary production in Mediterranean streams shows relevant seasonal changes which mainly follows the variations in light availability. In most forested streams, the algal community is shade-adapted. Nutrient enrichment (especially phosphorus) leads to marked increases in primary production, but this increase is not lineal and there is a saturation of algal biomass even in the most enriched systems. The heterotrophs (bacteria, fungi) are related to the pattern of DOC availability (which most depends on the seasonal discharge and leaf fall dynamics) and to the available substrata in the stream. It has been repeatedly observed that shorttime increases of extracellular enzyme activities are related to the accumulation of autochthonous (algal) and/or allochthonous (leaves) organic matter on the streambed during spring and summer, this being more remarkable in dry than in wetter years. Flow reduction favours detritus concentration in pools, and the subsequent increase in the density and biomass of the macroinvertebrate community. In Mediterranean streams collectors are accounting for the highest density and biomass, this being more remarkable in the least permanent systems, in accordance with the effect of floods on the organic matter availability. Nutrients, through the effect on the primary producers, also affect the trophic food web in the streams by favouring the predominance of grazers