13,893 research outputs found

    Participatory Plant Breeding for Organic Farming in France, the cauliflower experience at the PAIS

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    The availability of organic seeds is a great problem for organic farmers. The private sector of plant breeding meets difficulties to answer to the organic farming (OF) demand, characterized by small quantities and a great diversity of criteria and by breeding methods which respect the natural species characteristics (see IFOAM Draft Standard on organic seeds and plant breeding). So, the organic sector is organizing breeding and seed production by itself In France, since 2001, a Brittany regional organic umbrella (IBB, Inter Bio Bretagne), and some researchers from the national institute for agronomical research (INRA) have initiated a breeding program for organic production and a participatory plant breeding (PPB) program for organic cabbages and cauliflowers in Brittany, from the evaluation of genetic resources of several European gene Banks. In the PPB, the farmers are taking in charge breeding and seed production of open pollinated varieties. Several types were kept and bred, depending on the way of production and commercialization for each farmer. In the northern Brittany, farmers have not forgotten the traditional production of cauliflower seeds. PAIS, the agrobiological experimental station of IBB on the organic site of an agricultural school (Suscinio, Morlaix), is the meeting point for all the involved actors (farmers, traders, trainers, researchers
). There, the farmers and traders can find technical and scientific information, and they can share their experiences from the plant selection to seed production. Today, other French PPB initiatives involve several species and organic farmers groups, to promote biodiversity and a best adaptation to a local production: durum wheat in the Mediterranean area, bread wheat with the “paysan-boulangers”, maize and sunflower in the South-West of the country, tomato in the South-East, radishes, parsnip and summer cauliflower, in Pays de Loire. From these experiences, the PPB for organic farming consists in the constitution of the organic farmers group with the creation of exchange space for researchers and others organic actors, the definition of the priority in matters of crops, the discovering and selection of genetic resources in the farmers fields, the exchange of experiences and genetic resources through formal and informal, regional, national or international, farmer and organic professional meetings (accompanied by researchers and often enlarged to gardeners and trainers). The seed distribution has been depending on the French legislative evolution. By nature, the varieties issued from PPB could not fill the DUS (Distinction, Uniformity, Stability) characteristics for registration. And mainly, by ethics, the organic way of development should enhance the ancestral link between the plant and the farmers, link which needs exchanges to allow the evolution of the crops and the conservation of a living biodiversity

    ProtocadherinX/Y, a Candidate Gene-Pair for Schizophrenia and Schizoaffective Disorder: A DHPLC Investigation of Gonomic Sequence

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    Protocadherin X and Protocadherin Y (PCDHX and PCDHY) are cell-surface adhesion molecules expressed predominantly in the brain. The PCDHX/Y gene-pair was generated by an X-Y translocation approximately 3 million years ago (MYA) that gave rise to the Homo sapiens-specific region of Xq21.3 and Yp11.2 homology. Genes within this region are expected to code for sexually dimorphic human characteristics, including, for example, cerebral asymmetry a dimension of variation that has been suggested is relevant to psychosis. We examined differences in patients with schizophrenic or schizoaffective psychosis in the genomic sequence of PCDHX and PCDHY in coding and adjacent intronic sequences using denaturing high performance liquid chromatography (DHPLC). Three coding variants were detected in PCDHX and two in PCDHY. However, neither the coding variants nor the intronic polymorphisms could be related to psychosis within families. Low sequence variation suggests selective pressure against sequence change in modern humans in contrast to the structural chromosomal and sequence changes including fixed X-Y differences that occurred in this region earlier in hominid evolution. Our findings exclude sequence variation in PCDHX/Y as relevant to the aetiology of psychosis. However, we note the unusual status of this region with respect to X-inactivation. Further investigation of the epigenetic control of PCDHX/Y in relation to psychosis is warran

    Reality and Solutions for the Relationships between Social and Economic Growth in Vietnam

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    Economic growth and social welfare have very important correlation with all countries History has shown that some nations have fast economic growth but weak social welfare or vice versa However there are also economic developments that couple with very strong growth of social welfare Therefore the relationship between economic growth and social welfare is strategically economic - social issue for each country Rhythmic handling the relationship between economic growth and social welfare is a very difficult problem for all countries Thus the study of economic growth and progress social justice has always been one of the requirements and interest

    CO2-C4H10 Mixtures Simulated in Silica Slit Pores: Relation between Structure and Dynamics

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    Equilibrium molecular dynamics simulations were conducted for pure n-butane and for mixtures containing n-butane and carbon dioxide confined in 2 nm wide slit-shaped pores carved out of cristobalite silica. A range of thermodynamic conditions was explored, including temperatures ranging from subcritical to supercritical, and various densities. Preferential adsorption of carbon dioxide near the -OH groups on the surface was observed, where the adsorbed CO2 molecules tend to interact simultaneously with more than one -OH group. Analysis of the simulation results suggests that the preferential CO2 adsorption to the pore walls weakens the adsorption of n-butane, lowers the activation energy for n-butane diffusivity, and consequently enhances n-butane mobility. The diffusion results obtained for pure CO2 are consistent with strong adsorption on the pore walls, as the CO2 self-diffusion coefficient is low at low densities, increases with loading, and exhibits a maximum as the density is increased further because of hindrance effects. As the temperature increases, the maximum in self-diffusion coefficient is narrower, steeper, and shifted to lower loading. The simulation results are also quantified in terms of molecular density profiles for both butane and CO2 and in terms of residence time of the various molecules near the solid substrate. Our results could be useful for designing separation devices and also for better understanding the behavior of fluids in subsurface environments

    A panel error correction approach to explore spatial correlation patterns of the dominant housing market in Australian capital cities

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    Purpose - A panel error correction model has been developed to investigate the spatial correlation patterns among house prices. This paper aims to identify a dominant housing market in the ripple down process. Design/methodology/approach - Seemingly unrelated regression estimators are adapted to deal with the contemporary correlations and heterogeneity across cities. Impulse response functions are subsequently implemented to simulate the spatial correlation patterns. The newly developed approach is then applied to the Australian capital city house price indices. Findings - The results suggest that Melbourne should be recognised as the dominant housing market. Four levels were classified within the Australian house price interconnections, namely: Melbourne; Adelaide, Canberra, Perth and Sydney; Brisbane and Hobart; and Darwin. Originality/value - This research develops a panel regression framework in addressing the spatial correlation patterns of house prices across cities. The ripple-down process of house price dynamics across cities was explored by capturing both the contemporary correlations and heterogeneity, and by identifying the dominant housing market

    Managerial Incentives to Repeatedly Collude: Frequency, Partners and Governance Rules

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    Cartel recidivism has been discovered among many convicted firms and is often perceived as a result of the limited efficiency of competition policy. The incentives for managers to collude have been linked to the firm’s organizational structure, the corporate culture, and the type of executive compensation packages in place. To the extent that undetected cartels differ from detected ones in relevant dimensions, the current empirical results on illegal cartels are biased. To tackle this issue, we use a novel dataset of a population of cartels, which were legal in Sweden up until 1993. We contribute to the current debate on the importance and extent of recidivism, exploiting managers’ willingness to collude (repeatedly), absent law enforcement. This is a particularly important issue in the current climate of (potentially) weak law enforcement in terms of detected cartels and lack of optimal enforcement tools. We illustrate how recidivism is, in a legal setting, a widespread phenomenon. We show that: (i) cartel members tend to be multiple colluders (MCs), i.e., participate in many cartels (up to 63 in a 46-year period); (ii) MCs tend to collude with similar firms, refuse entry and/or exit from the agreement and have less-strict governance rules (fewer meetings, fewer voting mechanisms and a less delineated hierarchy); and (iii) contrary to the current literature, there is no clear trend between the MCs and the involvement of a trade association

    Structural and dynamical properties predicted by reactive force fields simulations for four common pure fluids at liquid and gaseous non-reactive conditions

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    Four common pure fluids were chosen to elucidate the reliability of reactive force fields in estimating bulk properties of selected molecular systems: CH 4 , H 2 O, CO 2 and H 2 . The pure fluids are not expected to undergo chemical reactions at the conditions chosen for these simulations. The ‘combustion’ ReaxFF was chosen as reactive force field. In the case of water, we also considered the ‘aqueous’ ReaxFF model. The results were compared to data obtained implementing popular classic force fields. In the gas phase, it was found that simulations conducted using the ‘combustion’ ReaxFF formalism yield structural properties in reasonable good agreement with classic simulations for CO 2 and H 2 , but not for CH 4 and H 2 O. In the liquid phase, ‘combustion’ ReaxFF simulations reproduce reasonably well the structure obtained from classic simulations for CH 4 , degrade for CO 2 and H 2 , and are rather poor for H 2 O. In the gas phase, the simulation results are compared to experimental second virial coefficient data. The ‘combustion’ ReaxFF simulations yield second virial coefficients that are not sufficiently negative for CH 4 and CO 2 , and slightly too negative for H 2 . The ‘combustion’ ReaxFF parameterisation induces too strong an effective attraction between water molecules, while the ‘aqueous’ ReaxFF yields a second virial coefficient that is in reasonable agreement with experiments. The ‘combustion’ ReaxFF parameterisation yields acceptable self-diffusion coefficients for gas-phase properties of CH 4 , CO 2 and H 2 . In the liquid phase, the results are good for CO 2 , while the self-diffusion coefficient predicted for liquid CH 4 is slower, and that predicted for liquid H 2 is about nine times faster than those expected based on classic simulations. The ‘aqueous’ ReaxFF parameterisation yields good results for both the structure and the diffusion of both liquid and vapour water

    Partial CO₂ Reduction in Amorphous Cylindrical Silica Nanopores Studied with Reactive Molecular Dynamics Simulations

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    It is known that pore confinement affects the structure and transport properties of fluids. It has also been shown that confinement can affect the equilibrium composition of a reactive system. Such effects could be related to the possible abiotic hydrocarbon synthesis in deep-sea hydrothermal vents, especially when the CO2 methanation reaction occurs within nanopores. In an attempt to identify possible rate-limiting steps of such a reaction, we report here molecular dynamics simulations conducted implementing the reactive force field. The reaction is considered within a cylindrical nanopore carved out of amorphous silica. Within the constraints of our simulations, which were conducted for 5 ns, no CH4 molecules were detected in the temperature range of 400–1000 K, suggesting that the silica pore hinders the complete CO2 reduction. This is consistent with the fact that silica is not an effective catalyst for CO2 methanation. Our simulations, in agreement with literature reports, suggest that the silica pore surface facilitates the partial reduction of CO2 to CO, which, within the conditions of our study, is found to be a stable product within the silica nanopores simulated. Analysis of the reaction products suggests that, although C–C bonds did not form, fragments reminiscent of carboxylic acids and formate were observed. Because these compounds are part of the biological Krebs cycle, our results suggest that confinement could provide prebiotic precursors of core metabolic pathways. Our results could be useful for further developing applications in which catalysts are designed to promote CO2 activation, for example, the one-step thermolysis of CO2
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