Competencia internacional y etica de produccion : la agricultura ecologica, un caso aparte?

La agricultura ecológica conoce un gran desarollo en numerosos países del Mundo. Los productos ecológicos forman parte de los intercambios comerciales a nivel internacional. Estos flujos pueden ser dificultados por la creación de barreras comerciales basadas en criterios técnicos tal como las normativas de producción. Esta contribución constituye una reflexión sobre el movimiento actual de armonización de los métodos de producción, a nivel mundial. Los autores muestran que esta tendencia se confronta a dos obstáculos importantes: por una parte, existen múltiples definiciones de la agricultura ecológica; por otra parte, los métodos de control del respeto de las normativas de producción difieren de un país a otro. Esta situación resulta de la disparidad en los niveles de desarrollo económico de los países implicados en el comercio de productos ecológicos: esta disparidad es responsable de la gran variabilidad de las preocupaciones de los ciudadanos y de los responsables políticos. Para los países en desarrollo, el modelo de agricultura de bajos insumos que representa la agricultura ecológica puede contribuir de forma significativa al abastecimiento de la población. Una normativa exigente y un control estricto de los métodos de producción constituyen potentes obstáculos al desarrollo. Sin embargo, cuando estos mismos países intentan exportar su produccíon hacía paises desarrollados, se confrontan, por parte de sus clientes, a la ausencia de reconocimiento de su normativa de producción. En conclusion, la problematica de los obstáculos técnicos al comercio internacional de los productos ecológicos es un tema de gran actualidad, del cual las organizaciones del sector deben preocuparse

Is it easy for producers to market organic beef meat ? The case of Biobourgogne Viande (France).

This contribution aims to present the results of a French case-study analysis - BioBourgogne Viande - carried up by members of three research teams in the framework of the European Program OMIaRD (Organic Marketing Initiatives and Rural Development) . In a first part, after a brief description of the region where the O.M.I is located, we present the main features of the development of BioBourgogne Viande, from its origins to the present day. In a second part, the motivations, cohesion and competencies are analysed in the structure of a SWOT (opportunities, threats, strengths and weaknesses), identifying organisational learning processes through the past ten year

The spectroscopic impedance of cellophane

Paper presented at the Fifth International Conference on Electromagnetic Wave Interaction with Water and Moist Substances, 2003, Rotorua, N. Z.The electrical impedance of cellophane has been measured as a function of moisture content and temperature in the frequency range 10⁻³ – 10⁵ Hz. The data show a very strong dependence on moisture content, which is a typical characteristic of hygroscopic solids, and at low frequencies, remarkable constant phase angle spectra were obtained. Making use of the hopping model of conduction in non-crystalline solids, we explain the measured spectra. The model treats absorbed water as an impurity in the cellophane and conduction is predicted to occur by temperature-activated proton hopping between water molecules. We also propose that this model is widely applicable to prediction of the low frequency dielectric properties of hygroscopic solids

Aeronautic Instruments. Section IV : Direction Instruments

Part one points out the adequacy of a consideration of the steady state gyroscopic motion as a basis for the discussion of displacements of the gyroscope mounted on an airplane, and develops a simple theory on this basis. Principal types of gyroscopic inclinometers are described and requirements stated. Part two describes a new type of stabilizing gyro mounted on top of a spindle by means of a universal joint, the spindle being kept in a vertical position by supporting it as a pendulum of which the bob is the driving motor. Methods of tests and the difficulties in designing a satisfactory and reliable compass for aircraft use in considered in part three. Part four contains a brief general treatment of the important features of construction of aircraft compasses and description of the principal types used

Aeronautic Instruments. Section V : Power Plant Instruments

Part 1 gives a general discussion of the uses, principles, construction, and operation of airplane tachometers. Detailed description of all available instruments, both foreign and domestic, are given. Part 2 describes methods of tests and effect of various conditions encountered in airplane flight such as change of temperature, vibration, tilting, and reduced air pressure. Part 3 describes the principal types of distance reading thermometers for aircraft engines, including an explanation of the physical principles involved in the functioning of the instruments and proper filling of the bulbs. Performance requirements and testing methods are given and a discussion of the source of error and results of tests. Part 4 gives methods of tests and calibration, also requirements of gauges of this type for the pressure measurement of the air pressure in gasoline tanks and the engine oil pressure on airplanes. Part 5 describes two types of gasoline gauges, the float type and the pressure type. Methods of testing and calibrating gasoline depth gauges are given. The Schroeder, R. A. E., and the Mark II flowmeters are described

Present-day deformation of the Pyrenees revealed by GPS surveying and earthquake focal mechanisms until 2011

The Pyrenean mountain range is a slowly deforming belt with continuous and moderate seismic activity. To quantify its deformation field, we present the velocity field estimated from a GPS survey of the Pyrenees spanning 18 yr. The PotSis and ResPyr networks, including a total of 85 GPS sites, were installed and first measured in 1992 and 1995 1997, respectively, and remeasured in 2008 and 2010. We obtain a deformation field with velocities less than 1 mm yr−1 across the range. The estimated velocities for individual stations do not differ significantly from zero with 95 per cent confidence. Even so, we estimate a maximum extensional horizontal strain rate of 2.0 ± 1.7 nanostrain per year in a N S direction in the western part of the range. We do not interpret the vertical displacements due to their large uncertainties. In order to compare the horizontal strain rates with the seismic activity, we analyse a set of 194 focal mechanisms using three methods: (i) the 'r' factor relating their P and T axes, (ii) the stress tensors obtained by fault slip inversion and (iii) the strain-rate tensors. Stress and strain-rate tensors are estimated for: (i) the whole data set, (ii) the eastern and western parts of the range separately, and (iii) eight zones, which are defined based on the seismicity and the tectonic patterns of the Pyrenees. Each of these analyses reveals a lateral variation of the deformation style from compression and extension in the east to extension and strike-slip in the west of the range. Although the horizontal components of the strain-rate tensors estimated from the seismic data are slightly smaller in magnitude than those computed from the GPS velocity field, they are consistent within the 2σ uncertainties. Furthermore, the orientations of their principal axes agree with the mapped active faults

Certificação de produtos orgânicos: obstáculos à implantação de um sistema participativo de garantia na Andaluzia, Espanha.

O trabalho analisa o processo de organização de produtores orgânicos da Andaluzia que estiveram envolvidos em uma tentativa de implantação de um sistema participativo de garantia. Esta iniciativa foi liderada pela administração dessa comunidade autônoma espanhola entre 2006 e 2008. O estudo baseia-se em entrevistas realizadas com atores sociais que estiveram implicados nesse processo, identificando os obstáculos políticos e organizativos que impediram que essa proposta pudesse avançar