1,176 research outputs found

    Policies and joint activities

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    The development potential of Organic Sectors in a concrete context heavily depends on the policies and frameworks provided by local or national Governments. Legal production requirements, subsidies, land tenure rights, security issues, participation options, market infrastructure, available institutions, education and training, innovation/knowledge management etc. strongly influence the likelihood that organic production, processing and trade will emerge and/or expand

    A Rewriting-Logic-Based Technique for Modeling Thermal Systems

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    This paper presents a rewriting-logic-based modeling and analysis technique for physical systems, with focus on thermal systems. The contributions of this paper can be summarized as follows: (i) providing a framework for modeling and executing physical systems, where both the physical components and their physical interactions are treated as first-class citizens; (ii) showing how heat transfer problems in thermal systems can be modeled in Real-Time Maude; (iii) giving the implementation in Real-Time Maude of a basic numerical technique for executing continuous behaviors in object-oriented hybrid systems; and (iv) illustrating these techniques with a set of incremental case studies using realistic physical parameters, with examples of simulation and model checking analyses.Comment: In Proceedings RTRTS 2010, arXiv:1009.398

    Test of Sum Rules in Nucleon Transfer Reactions

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    The quantitative consistency of nucleon transfer reactions as a probe of the occupancy of valence orbits in nuclei is tested. Neutron-adding, neutron-removal, and proton-adding transfer reactions were measured on the four stable even Ni isotopes, with particular attention to the cross section determinations. The data were analyzed consistently in terms of the distorted wave Born approximation to yield spectroscopic factors. Valence-orbit occupancies were extracted, utilizing the Macfarlane-French sum rules. The deduced occupancies are consistent with the changing number of valence neutrons, as are the vacancies for protons, both at the level of <5%. While there has been some debate regarding the true “observability” of spectroscopic factors, the present results indicate that empirically they yield self-consistent results

    Chemostratigraphy of Neoproterozoic carbonates: implications for 'blind dating'

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    The delta C-13(carb) and Sr-87/Sr-86 secular variations in Neoproteozoic seawater have been used for the purpose of 'isotope stratigraphy' but there are a number of problems that can preclude its routine use. In particular, it cannot be used with confidence for 'blind dating'. The compilation of isotopic data on carbonate rocks reveals a high level of inconsistency between various carbon isotope age curves constructed for Neoproteozoic seawater, caused by a relatively high frequency of both global and local delta C-13(carb) fluctuations combined with few reliable age determinations. Further complication is caused by the unresolved problem as to whether two or four glaciations, and associated negative delta C-13(carb) excursions, can be reliably documented. Carbon isotope stratigraphy cannot be used alone for geological correlation and 'blind dating'. Strontium isotope stratigraphy is a more reliable and precise tool for stratigraphic correlations and indirect age determinations. Combining strontium and carbon isotope stratigraphy, several discrete ages within the 590-544 Myr interval, and two age-groups at 660-610 and 740-690 Myr can be resolved

    Valence nucleon populations in the Ni isotopes

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    Measurements of neutron-adding, neutron-removing, and proton-adding reactions were carried out for the four stable even Ni isotopes. Particular attention was paid to obtaining precise values of the cross sections at the peaks of the angular distributions. Tests with sum rules for the neutron data indicate that the results are self-consistent at the level of a few tenths of a nucleon. Data on proton-adding reactions were also obtained and analyzed with a slightly different method—while these data are also consistent, the ambiguities are larger. The occupancies of the neutron orbits derived from the data, the proton vacancies, and the energy centroids of the neutron, neutron-hole, and proton single-particle excitations are obtained. The data also provide some estimate about the closure of the 0f7/2 shell. The results are compared to shell-model calculations and may serve as a reference point for future exploration

    Enhancement of low-mass dileptons in heavy-ion collisions

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    Using a relativistic transport model for the expansion stage of S+Au collisions at 200 GeV/nucleon, we show that the recently observed enhancement of low-mass dileptons by the CERES collaboration can be explained by the decrease of vector meson masses in hot and dense hadronic matter.Comment: 12 pages, RevTeX, 3 figures available from [email protected]

    Current constraints on Cosmological Parameters from Microwave Background Anisotropies

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    We compare the latest observations of Cosmic Microwave Background (CMB) Anisotropies with the theoretical predictions of the standard scenario of structure formation. Assuming a primordial power spectrum of adiabatic perturbations we found that the total energy density is constrained to be Ωtot=1.03±0.06\Omega_{tot}=1.03\pm0.06 while the energy density in baryon and Cold Dark Matter (CDM) are Ωbh2=0.021±0.003\Omega_bh^2=0.021\pm0.003 and Ωcdmh2=0.12±0.02\Omega_{cdm}h^2=0.12\pm0.02, (all at 68% C.L.) respectively. The primordial spectrum is consistent with scale invariance, (ns=0.97±0.04n_s=0.97\pm0.04) and the age of the universe is t0=14.6±0.9t_0=14.6\pm0.9 Gyrs. Adding informations from Large Scale Structure and Supernovae, we found a strong evidence for a cosmological constant ΩΛ=0.700.05+0.07\Omega_{\Lambda}=0.70_{-0.05}^{+0.07} and a value of the Hubble parameter h=0.69±0.07h=0.69\pm0.07. Restricting this combined analysis to flat universes, we put constraints on possible 'extensions' of the standard scenario. A gravity waves contribution to the quadrupole anisotropy is limited to be r0.42r \le 0.42 (95% c.l.). A constant equation of state for the dark energy component is bound to be wQ0.74w_Q \le -0.74 (95% c.l.). We constrain the effective relativistic degrees of freedom Nν6.2N_\nu \leq 6.2 and the neutrino chemical potential 0.01ξe0.18-0.01 \leq \xi_e \leq 0.18 and ξμ,τ2.3|\xi_{\mu,\tau}|\leq 2.3 (massless neutrinos).Comment: The status of cosmological parameters before WMAP. In press on Phys. Rev. D., Rapid Communication, 6 pages, 5 figure

    International multidisciplinary collaboration toward an annotated definition of arthrogryposis multiplex congenita

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    Arthrogryposis multiplex congenita (AMC) has been described and defined in thousands of articles, but the terminology used has been inconsistent in clinical and research communities. A definition of AMC was recently developed using a modified Delphi consensus method involving 25 experts in the field of AMC from 8 countries. Participants included health care professionals, researchers, and individuals with AMC. An annotation of the definition provides more in‐depth explanations of the different sentences of the AMC definition and is useful to complement the proposed definition. The aim of this study was to provide an annotation of the proposed consensus‐based AMC definition. For the annotation process, 17 experts in AMC representing 10 disciplines across 7 countries participated. A paragraph was developed for each sentence of the definition using an iterative process involving multiple authors with varied and complementary expertise, ensuring all points of view were taken into consideration. The annotated definition provides an overview of the different topics related to AMC and is intended for all stakeholders, including youth and adults with AMC, their families, and clinicians and researchers, with the hopes of unifying the understanding of AMC in the international community

    Backward pion-nucleon scattering

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    A global analysis of the world data on differential cross sections and polarization asymmetries of backward pion-nucleon scattering for invariant collision energies above 3 GeV is performed in a Regge model. Including the NαN_\alpha, NγN_\gamma, Δδ\Delta_\delta and Δβ\Delta_\beta trajectories, we reproduce both angular distributions and polarization data for small values of the Mandelstam variable uu, in contrast to previous analyses. The model amplitude is used to obtain evidence for baryon resonances with mass below 3 GeV. Our analysis suggests a G39G_{39} resonance with a mass of 2.83 GeV as member of the Δβ\Delta_{\beta} trajectory from the corresponding Chew-Frautschi plot.Comment: 12 pages, 16 figure
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