364 research outputs found
How to test SME with space missions ?
In this communication, we focus on possibilities to constrain SME
coefficients using Cassini and Messenger data. We present simulations of
radioscience observables within the framework of the SME, identify the linear
combinations of SME coefficients the observations depend on and determine the
sensitivity of these measurements to the SME coefficients. We show that these
datasets are very powerful for constraining SME coefficients.Comment: Presented at the Sixth Meeting on CPT and Lorentz Symmetry,
Bloomington, Indiana, June 17-21, 2013. 4 pages, 1 figur
Developement dynamics of organic farming : elements for debate
Synthetic overview of the third workshop : development dynamics of organic farming
Agroecology: Polysemy, Pluralism And Controversies
In recent years, a growing number of actors and institutions, in different countries, have begun using the notion of Agroecology, which has led to an expansion of its polysemy and its controversies. Taking this into account, this paper analyzes, based on the Brazilian and French experiences, the peculiarities of Agroecology in four different fields: science, social movements, government policies, and education. It also discusses three other issues: the analytical, programmatic and normative discourses; the different definitions, in the fields of science and education, of the object of study of Agroecology; and the different formulations regarding its fundamental principles. It is argued that, in this new context, recognition of this pluralism and the controversies acquires a central role in the construction of knowledge in the various fields linked to Agroecology.19312
Testing Gravitation in the Solar System with Radio Science experiments
The laws of gravitation have been tested for a long time with steadily
improving precision, leading at some moment of time to paradigmatic evolutions.
Pursuing this continual effort is of great importance for science. In this
communication, we focus on Solar System tests of gravity and more precisely on
possible tests that can be performed with radio science observations (Range and
Doppler). After briefly reviewing the current tests of gravitation at Solar
System scales, we give motivations to continue such experiments. In order to
obtain signature and estimate the amplitude of anomalous signals that could
show up in radio science observables because of modified gravitational laws, we
developed a new software that simulates Range/Doppler signals. We present this
new tool that simulates radio science observables directly from the space-time
metric. We apply this tool to the Cassini mission during its cruise from
Jupiter to Saturn and derive constraints on the parameters entering alternative
theories of gravity beyond the standard Parametrized Post Newtonian theory.Comment: proceedings of SF2A 2011 - minor changes (typos corrected -
references updated
Analysis of transition forms towards more ecologically-oriented farming: the case of organic farming and integrated crop protection
Interdisciplinary approaches developed concerning the conversion to organic farming show that the types of conversion trajectories can be differentiated on the basis of the progression of crop protection changes within a larger framework where relationships to other âobjectsâ are transformed â the soil, products, rotations, work organisation, marketing, social networks and knowledge acquisition. In the case of integrated plant production, the extent of changes depends on the degree of recomposition of agronomic practices. This transition implies major knowledge acquisition that relies on the support and contribution of advisors and on the group dynamics that develop within a group of farmers. Transitions towards integrated crop protection are, by their nature, more reversible and therefore more fragile than the conversion to organic farming. This is due to the fact that they are not stabilised by a certification or by the market, and analysis shows that their sustainability is linked in part to their integration within a group dynamics
[Generalized Telegraph equation with fractional -Laplacian
The purpose of this paper is devoted to \textcolor{red}{discussing} the
existence of solutions for a generalized fractional telegraph equation
involving a class of -Hilfer fractional with -Laplacian
differential equation.Comment: 14 page
Alternative Food Networks And New Producer-consumer Relations In France And In Brazil
This paper presents an analysis about agroecological alternative food networks and new producer-consumer relationships in France and Brazil. The investigation method is based on descriptive and qualitative research about 20 cases (qualitative interviews), selected with stakeholders (farmers, traders, consumers and food experts) in France and Southern Brazil. A typology about the characteristics and organization to short circuits trade is provided. The results show that alternative food networks are very diverse and dynamic, being a social, economic and environmental option to family farming, strengthening local markets and reconnecting producers and consumers. In these countries, the successful initiatives of alternative networks occur in places where there is coordination between food networks stakholders such as the government, NGOs, private enterprises, farmers and consumers' organizations.19212
Ultimate decoherence border for matter-wave interferometry
Stochastic backgrounds of gravitational waves are intrinsic fluctuations of
spacetime which lead to an unavoidable decoherence mechanism. This mechanism
manifests itself as a degradation of the contrast of quantum interferences. It
defines an ultimate decoherence border for matter-wave interferometry using
larger and larger molecules. We give a quantitative characterization of this
border in terms of figures involving the gravitational environment as well as
the sensitivity of the interferometer to gravitational waves. The known level
of gravitational noise determines the maximal size of the molecular probe for
which interferences may remain observable. We discuss the relevance of this
result in the context of ongoing progresses towards more and more sensitive
matter-wave interferometry.Comment: 4 page
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