Agri-food qualification and certification process as an interface between exchange marketing and reciprocity

Ce texte mobilise la théorie de la réciprocité en anthropologie économique pour analyser les processus de qualification des produits de l'agriculture familiale au Brésil. Tout processus de qualification qui garantit l'origine, la spécificité, la qualité d'un produit peut réduire les effets de concurrence et de spéculation spécifiques à l'échange capitaliste. Je fais l'hypothèse que les processus de qualification peuvent contribuer à établir une relation de réciprocité symétrique entre producteur et consommateur. Ils peuvent également concourir à engendrer une structure de partage (de la qualité) au sein d'un groupe de producteurs. Mais, les mécanismes de qualification et certification peuvent également introduire l'exclusion, car en dehors du groupe et des produits certifiés ce sont les lois de l'échange qui régulent le marché. C'est pourquoi on a besoin d'une forme d'interface ou d'articulation entre production et marché. L'interface offerte par les mécanismes de certification de la qualification permet de réintroduire la dimension de la réciprocité économique dans le système du marché d'échange capitaliste. Ce texte repose sur la comparaison de trois systèmes de certification de produits agro-écologiques au Brésil : la certification externe de groupes, la certification participative et la cocertification. (Résumé d'auteur

Time-dependent patterns in quasivertical cylindrical binary convection

This paper reports on numerical investigations of the effect of a slight inclination a on pattern formation in a shallow vertical cylindrical cell heated from below for binary mixtures with a positive value of the Soret coefficient. By using direct numerical simulation of the three-dimensional Boussinesq equations with Soret effect in cylindrical geometry, we show that a slight inclination of the cell in the range a˜0.036rad=2° strongly influences pattern selection. The large-scale shear flow (LSSF) induced by the small tilt of gravity overcomes the squarelike arrangements observed in noninclined cylinders in the Soret regime, stratifies the fluid along the direction of inclination, and produces an enhanced separation of the two components of the mixture. The competition between shear effects and horizontal and vertical buoyancy alters significantly the dynamics observed in noninclined convection. Additional unexpected time-dependent patterns coexist with the basic LSSF. We focus on an unsual periodic state recently discovered in an experiment, the so-called superhighway convection state (SHC), in which ascending and descending regions of fluid move in opposite directions. We provide numerical confirmation that Boussinesq Navier-Stokes equations with standard boundary conditions contain the essential ingredients that allow for the existence of such a state. Also, we obtain a persistent heteroclinic structure where regular oscillations between a SHC pattern and a state of nearly stationary longitudinal rolls take place. We characterize numerically these time-dependent patterns and investigate the dynamics around the threshold of convection.Postprint (author's final draft

Temporal regularity effects on pre-attentive and attentive processing of deviance

Temporal regularity allows predicting the temporal locus of future information thereby potentially facilitating cognitive processing. We applied event-related brain potentials (ERPs) to investigate how temporal regularity impacts pre-attentive and attentive processing of deviance in the auditory modality. Participants listened to sequences of sinusoidal tones differing exclusively in pitch. The inter-stimulus interval (ISI) in these sequences was manipulated to convey either isochronous or random temporal structure. In the pre-attentive session, deviance processing was unaffected by the regularity manipulation as evidenced in three event-related-potentials (ERPs): mismatch negativity (MMN), P3a, and reorienting negativity (RON). In the attentive session, the P3b was smaller for deviant tones embedded in irregular temporal structure, while the N2b component remained unaffected. These findings confirm that temporal regularity can reinforce cognitive mechanisms associated with the attentive processing of deviance. Furthermore, they provide evidence for the dynamic allocation of attention in time and dissociable pre-attentive and attention-dependent temporal processing mechanisms

A Radio Census of Binary Supermassive Black Holes

Using archival VLBI data for 3114 radio-luminous active galactic nuclei, we searched for binary supermassive black holes using a radio spectral index mapping technique which targets spatially resolved, double radio-emitting nuclei. Only one source was detected as a double nucleus. This result is compared with a cosmological merger rate model and interpreted in terms of (1) implications for post-merger timescales for centralisation of the two black holes, (2) implications for the possibility of "stalled" systems, and (3) the relationship of radio activity in nuclei to mergers. Our analysis suggests that the binary evolution of paired supermassive black holes (both of masses >= 1e8 Msun) spends less than 500 Myr in progression from the merging of galactic stellar cores to within the purported stalling radius for supermassive black hole pairs. The data show no evidence for an excess of stalled binary systems at small separations. We see circumstantial evidence that the relative state of radio emission between paired supermassive black holes is correlated within orbital separations of 2.5 kpc.Comment: 11 Pages, 7 figures, accepted for publication in MNRA

Machine-Part cell formation through visual decipherable clustering of Self Organizing Map

Machine-part cell formation is used in cellular manufacturing in order to process a large variety, quality, lower work in process levels, reducing manufacturing lead-time and customer response time while retaining flexibility for new products. This paper presents a new and novel approach for obtaining machine cells and part families. In the cellular manufacturing the fundamental problem is the formation of part families and machine cells. The present paper deals with the Self Organising Map (SOM) method an unsupervised learning algorithm in Artificial Intelligence, and has been used as a visually decipherable clustering tool of machine-part cell formation. The objective of the paper is to cluster the binary machine-part matrix through visually decipherable cluster of SOM color-coding and labelling via the SOM map nodes in such a way that the part families are processed in that machine cells. The Umatrix, component plane, principal component projection, scatter plot and histogram of SOM have been reported in the present work for the successful visualization of the machine-part cell formation. Computational result with the proposed algorithm on a set of group technology problems available in the literature is also presented. The proposed SOM approach produced solutions with a grouping efficacy that is at least as good as any results earlier reported in the literature and improved the grouping efficacy for 70% of the problems and found immensely useful to both industry practitioners and researchers.Comment: 18 pages,3 table, 4 figure

Leading Communities of Practice in Social Work. Groupwork or management?

Social work in the UK has undergone a period of momentous change in the last decade with the introduction of a ‘modernising agenda’ that has increased managerial approaches to the organisation, development and delivery of services. Whilst posing a threat to some, these approaches are embedded and social workers must find ways of working within them to synthesise appropriate responses that promote the values and cultural heritage of social work within the new context. This paper considers the possibilities offered by communities of practice to develop learning organisations in which a managed and participatory approach to social care can be generated. A super-ordinate model of contending cultures is developed and practice that draws on and is predicated by groupwork principles is presented as a potential way forward

The Evidence of Buyer Bargaining Power in The Stockholm Residential Real Estate Market

The objective is to investigate whether uninformed buyers pay higher prices for single-family houses than do other buyers and test whether the bargaining power increases with information. We examine data on real estate prices and attributes, as well as household characteristics and buying process from Stockholm. Our results show that uninformed buyers seem to pay a higher price than informed buyers do. Bargaining power is not weaker for a first-time buyer but is weaker if the household has participated in several biddings and lost. Repeated bidding-and-losing households are more willing to increase their reservation price and pay a higher overall price compared to other households.