297 research outputs found

    Sideritis arborescens Salzm. ex Bentham y Sideritis x gaditana Rouy en Andalucía Occidental

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    It is described at the report the taxonomicous characters of the different subespecies of Sideritis arborescens Salzm. ex Bentham and of Sideritis x gaditana Rouy. It is also included for each taxon, type, distribution and material studied from West Andalucia.Se describen los caracteres taxonómicos de las distintas subespecies de Sideritis arborescens Salzm. ex Bentham y de Sideritis x gaditana buy. Se incluye además para cada taxon, tipo, distribución y material estudiado en Andalucia Occidental

    Large Deformation Effects in the N = Z 44Ti Compound Nucleus

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    The N = Z 44Ti* nucleus has been populated in Fusion Evaporation process at very high excitation energies and angular momenta using two entrance channels with different mass-asymmetry. The deformation effects in the rapidly rotating nuclei have been investigated through the energy distribution of the alpha-particle combined to statistical-model calculations. In the case of low-multiplicity events, the ratio between first particle emitted has been measured and shows significant disagreement with the predictions of the statistical-model. This may explain The large discrepancies observed in proton energy spectra measured in previous experiments performed in the same mass region.Comment: Proceeding of the 10th International Conference on Nuclear Reaction Mechanisms, Varenna Italy, June 9-13 2003. 10 pages, 6 figures, 1 tabl

    Binary reaction decays from 24Mg+12C

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    Charged particle and gamma decays in 24Mg* are investigated for excitation energies where quasimolecular resonances appear in 12C+12C collisions. Various theoretical predictions for the occurence of superdeformed and hyperdeformed bands associated with resonance structures with low spin are discussed within the measured 24Mg* excitation energy region. The inverse kinematics reaction 24Mg+12C is studied at E_lab(24Mg) = 130 MeV, an energy which enables the population of 24Mg states decaying into 12C+12C resonant break-up states. Exclusive data were collected with the Binary Reaction Spectrometer in coincidence with EUROBALL IV installed at the VIVITRON Tandem facility at Strasbourg. Specific structures with large deformation were selectively populated in binary reactions and their associated gamma decays studied. Coincident events associated with inelastic and alpha-transfer channels have been selected by choosing the excitation energy or the entry point via the two-body Q-values. The analysis of the binary reaction channels is presented with a particular emphasis on 24Mg-gamma, 20Ne-gamma and 16O-gamma coincidences. New information (spin and branching ratios) is deduced on high-energy states in 24Mg and 16O, respectively.Comment: 27 pages, 8 figures, 1 tabl

    Synthesis of Porous and Mechanically Compliant Carbon Aerogels Using Conductive and Structural Additives

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    We report the synthesis of conductive and mechanically compliant monolithic carbon aerogels prepared by sol-gel polycondensation of melamine-resorcinol-formaldehyde (MRF) mixtures by incorporating diatomite and carbon black additives. The resulting aerogels composites displayed a well-developed porous structure, confirming that the polymerization of the precursors is not impeded in the presence of either additive. The aerogels retained the porous structure after etching off the siliceous additive, indicating adequate cross-linking of the MRF reactants. However, the presence of diatomite caused a significant fall in the pore volumes, accompanied by coarsening of the average pore size (predominance of large mesopores and macropores). The diatomite also prevented structural shrinkage and deformation of the as-prepared monoliths upon densification by carbonization, even after removal of the siliceous framework. The rigid pristine aerogels became more flexible upon incorporation of the diatomite, favoring implementation of binderless monolithic aerogel electrodes

    Reaction mechanisms in 24Mg+12C and 32S+24Mg

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    The occurence of "exotic" shapes in light N=Z alpha-like nuclei is investigated for 24Mg+12C and 32S+24Mg. Various approaches of superdeformed and hyperdeformed bands associated with quasimolecular resonant structures with low spin are presented. For both reactions, exclusive data were collected with the Binary Reaction Spectrometer in coincidence with EUROBALL IV installed at the VIVITRON Tandem facility of Strasbourg. Specific structures with large deformation were selectively populated in binary reactions and their associated γ\gamma-decays studied. The analysis of the binary and ternary reaction channels is discussed.Comment: 7 pages, 4 figures, Paper presented at the Fusion08 International Conference on New Aspects of Heavy Ion Collisions Near the Coulomb Barrier, Chicago. Proceedings to be published by AIP Conference Proceedings Illinois, USA, September 22-26, 200

    Clusters in Light Nuclei

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    A great deal of research work has been undertaken in the alpha-clustering study since the pioneering discovery, half a century ago, of 12C+12C molecular resonances. Our knowledge of the field of the physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. In this work, the occurence of "exotic" shapes in light N=Z alpha-like nuclei is investigated. Various approaches of superdeformed and hyperdeformed bands associated with quasimolecular resonant structures are presented. Results on clustering aspects are also discussed for light neutron-rich Oxygen isotopes.Comment: 12 pages, 5 figures. Invited Talk presented by C. Beck at the Zakopane Conference on Nuclear Physics "Extremes of the Nuclear Landscape" XLV in the series of Zakopane Schools of Physics - International Symposium - Zakopane, Poland, August 30 - September 5, 2010.To be publihed in Acta Physica Polonica B42 no 3, March 201

    A quasi-experimental study of impacts of Tanzania’s Wildlife Management Areas on rural livelihoods and wealth

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    Since the 2000s, Tanzania’s natural resource management policy has emphasised Wildlife Management Areas (WMAs), designed to promote wildlife and biodiversity conservation, poverty alleviation and rural development. We carried out a quasi-experimental impact evaluation of social impacts of WMAs, collecting data from 24 villages participating in 6 different WMAs across two geographical regions, and 18 statistically matched control villages. Across these 42 villages, we collected participatory wealth ranking data for 13,578 households. Using this as our sampling frame, we conducted questionnaire surveys with a stratified sample of 1,924 household heads and 945 household heads’ wives. All data were collected in 2014/15, with a subset of questions devoted to respondents’ recall on conditions that existed in 2007, when first WMAs became operational. Questions addressed household demographics, land and livestock assets, resource use, income-generating activities and portfolios, participation in natural resource management decision-making, benefits and costs of conservation. Datasets permit research on livelihood and wealth trajectories, and social impacts, costs and benefits of conservation interventions in the context of community-based natural resource management
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