187 research outputs found

    Towards a consolidation of worldwide journal rankings - A classification using random forests and aggregate rating via data envelopment analysis

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    AbstractThe question of how to assess research outputs published in journals is now a global concern for academics. Numerous journal ratings and rankings exist, some featuring perceptual and peer-review-based journal ranks, some focusing on objective information related to citations, some using a combination of the two. This research consolidates existing journal rankings into an up-to-date and comprehensive list. Existing approaches to determining journal rankings are significantly advanced with the application of a new classification approach, ‘random forests’, and data envelopment analysis. As a result, a fresh look at a publication׳s place in the global research community is offered. While our approach is applicable to all management and business journals, we specifically exemplify the relative position of ‘operations research, management science, production and operations management’ journals within the broader management field, as well as within their own subject domain

    Contrasting styles of (U)HP rock exhumation along the Cenozoic Adria-Europe plate boundary (Western Alps, Calabria, Corsica)

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    Since the first discovery of ultrahigh pressure (UHP) rocks 30 years ago in the Western Alps, the mechanisms for exhumation of (U)HP terranes worldwide are still debated. In the western Mediterranean, the presently accepted model of synconvergent exhumation (e.g., the channel-flow model) is in conflict with parts of the geologic record. We synthesize regional geologic data and present alternative exhumation mechanisms that consider the role of divergence within subduction zones. These mechanisms, i.e., (i) the motion of the upper plate away from the trench and (ii) the rollback of the lower plate, are discussed in detail with particular reference to the Cenozoic Adria-Europe plate boundary, and along three different transects (Western Alps, Calabria-Sardinia, and Corsica-Northern Apennines). In the Western Alps, (U)HP rocks were exhumed from the greatest depth at the rear of the accretionary wedge during motion of the upper plate away from the trench. Exhumation was extremely fast, and associated with very low geothermal gradients. In Calabria, HP rocks were exhumed from shallower depths and at lower rates during rollback of the Adriatic plate, with repeated exhumation pulses progressively younging toward the foreland. Both mechanisms were active to create boundary divergence along the Corsica-Northern Apennines transect, where European southeastward subduction was progressively replaced along strike by Adriatic northwestward subduction. The tectonic scenario depicted for the Western Alps trench during Eocene exhumation of (U)HP rocks correlates well with present-day eastern Papua New Guinea, which is presented as a modern analog of the Paleogene Adria-Europe plate boundary

    Distribution of trace elements in altered pyroclastites from Monte Vulture volcano (southern Italy)

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    9 pages, 4 figures, 4 tables.[EN] Three pyroclastic deposits from Monte Yulture volcanic area (Potenza, southern Italy) looking like paleosols in the field were investigated in a previous study for mineralogy and major elements to estimate the stage of the weathering. Here is dealt with the behaviour of sorne trace elements (Ce, La, Ba, Ni, Cr, Y, Rb, Sr, Y, Zr and Nb) in the same deposits to give a comprehensive geochemical picture. The distribution of the chemical elements within the whole rock and after its attack with Na-pyrosulfate (residue + solute) has been considered. Ba and Sr, as well as their distribution, appear to be controlled by the residual crystals in each of the deposits; La, Ce, Y and Nb are more concentrated in the solute that once was represented by vitric component, allophane, and Fe-Si-Al gels, biotite, carbonates and analcite; Y, Cr, and Ni show similar trends in whole rock and in solute. In particular La, Ce, Y, Y, Cr and Ni in the lowermost unit increase with the depth, as well as the contents of gels and allophane. Probably this behaviour was superimposed by the fluctuation of the water tables, as documented by the occurrence of a carbonate level upon the unit lies. It is concluded that the earliest stage of weathering did not affect the trace element distribution and that interpretations about chemical changes in deeply altered pyroclastic rocks should be always the outcome of careful accurate analyses.[ES] En un trabajo previo se estudiaron tres depósitos piroclásticos, considerados como paleosuelos, del área volcánica del Monte Yulture (Potenza, Italia) para deducir su grado de meteorización. En el presente trabajo se estudia el comportamiento de algunos elementos traza (Ce, La, Ba, Ni, Cr, Y, Rb, Sr, Y, Zr, Nb) en esos depósitos para intentar obtener una imagen geoquímica más completa. Se ha estudiado la distribución de elementos traza en la roca total y después de un ataque con pirosulfato-Na (residuo + solución). Ba y Sr parecen estar controlados por los cristales del residuo (piroxenos, feldespatos, anfíboles y accesorios); La, Ce, Y y Nb se concentran más en la solución, es decir en los componentes vítreos, alofana, geles Fe-SiAl, biotita carbonatos y analcima; Y, Cr y Ni no muestran ninguna tendencia a concentrarse en una fracción concreta. Hay que resaltar que La, Ce, Y, Y, Cr y Ni aumentan con la profundidad en la unidad inferior, junto con el contenido en geles y en alofana. Este comportamiento puede ser debido a fluctuaciones del nivel freático, como se deduce por la presencia de un nivel calcáreo en la unidad superior. Se concluye que los estados precoces de meteorización no afectan prácticamente a la distribución de los elementos traza, y que las interpretaciones sobre los cambios químico sufridos por las rocas piroclásticas deben hacerse sólo después de un detallado análisis.The work was financially supported by Consiglio Nazionale delle Ricerche (lta1y) and by Junta de Andalucía, Grupo 4049 (Spain).Peer reviewe

    Archeologia Aerea. Studi di Aerotopografia Archeologica

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    Collana finalizzata alla raccolta di contributi miscellanei di carattere aerotopografic
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