Beyond divide and rule : weak dictators, natural resources and civil conflict

We propose a model where an autocrat rules over an ethnically divided society. The dictator selects the tax rate over domestic production and the nation’s natural resources to maximize his rents under the threat of a regime-switching revolution. We show that a weak ruler may let the country plunge in civil war to increase his personal rents. Inter-group fighting weakens potential opposition to the ruler, thereby allowing him to increase fiscal pressure. We show that the presence of natural resources exacerbates the incentives of the ruler to promote civil conflict for his own profit, especially if the resources are unequally distributed across ethnic groups. We validate the main predictions of the model using cross-country data over the period 1960-2007, and show that our empirical results are not likely to be driven by omitted observable determinants of civil war incidence or by unobservable country-specific heterogeneity.

Trace elements biogeochemistry in high mountain lake catchments: identifying anthropogenic versus natural components from the atmospheric contamination legacy in remote natural areas

Human activities have been interfering with the natural biogeochemical cycles of trace elements since the ancient civilizations. Although they are inaccessible and remote, high mountain lake catchments are irrefutably trace-element contaminated by anthropogenic emissions, which can travel by long-range atmospheric transport before they are deposited. This has been revealed by several natural archives. High mountain lake catchments are thus excellent sentinels of long-range contamination. Continuous accumulation can lead to a build up of potentially toxic trace elements in these remote, or relatively remote, ecosystems. The thesis focuses on the biogeochemistry of a suite of trace elements of environmental concern (Ni, Cu, Zn, As, Se, Cd and Pb) in Pyrenean lake catchments, with special emphasis on discerning the “natural” components from the “anthropogenic” contributions. Five other metallic elements (Al, Fe, Ti, Mn and Zr) have also been studied to trace natural fluxes and biogeochemical processes within the lake catchment systems.

A biopolítica e o paradoxo da objectividade jornalística : um estudo de caso sobre os conflitos Israel-Palestina

O propósito desta investigação é identificar e analisar, a partir de um estudo de caso, o paradoxo com que se confrontam os media de referência ocidentais na cobertura dos conflitos Israel-Palestina: um trabalho jornalístico dividido entre a retórica da objectividade e a necessidade de conviver, de se apoiar e, via de regra, reproduzir o paradigma da biopolítica - à luz do qual se justifica a necessidade de controlo e subjugação dos corpos, por questões de segurança e de prevenção do terrorismo. A partir do entendimento clássico de que a objectividade - mesmo sendo uma utopia - é factor desejável e figura como componente basilar no ritual estratégico da produção jornalística, busca-se aqui remontar as origens dessa conceituação, mostrando que ela emerge numa altura da história imediatamente posterior àquela em que Michel Foucault localiza o nascimento do sistema biopolítico. Uma análise foucaultiana de discurso permitiu identificar pontos de cristalização desse paradigma em um grupo de notícias extraídas de dois jornais de referência portugueses. As teorias de Hannah Arendt e de Giogio Agamben sobre a condição humana na Modernidade surgem, então, como chaves alinhadas ao pensamento de Foucault e subsidiam as reflexões conclusivas acerca dos quadros discursivos identificados neste trabalho.

Conical sedimentary structures, trace fossils or not? Observations, experiments, and review

Conical sedimentary structures are widespread in the geological column. Those that are mediated by organisms (or organic matter) can be attributed to seven principal processes, which are investigated by experiment and/or field observations: (1) sand collapse into a cavity (decomposed body, open shaft, or gallery), (2) upward (escape) or downward locomotion by an organism through the sediment, (3) upward adjustment (equilibration), (4) casting of coelenterates' excavations, (5) organism-mediated soft-sediment deformation in heterolithic sediment, (6) biodeformational small and large excavations by organisms, and (7) fluid (gas or liquid) escape structures. Footprint loading may also be included. Criteria are given to distinguish between these processes. Dewatering pipes are best recognized by a zone of deformed and fluidized sediment at the base, and association with non-life (lethal) facies. Care must be used in assigning specimens to ichnotaxa, and it is generally necessary to slab, and also to carry out stratinomic investigation in the field.

Distribution and mobility of trace elements in soils and vegetation around the mining and smelting areas of Tharsis, Riotinto and Huelva, Iberian Pyrite Belt, SW Spain

Trace elements may present an environmental hazard in the vicinity of mining and smelting activities. However, the factors controlling their distribution and transfer within the soil and vegetation systems are not always well defined. Total concentrations of up to 15,195 mg center dot kg (-1) As, 6,690 mg center dot kg(-1) Cu, 24,820 mg center dot kg(-1) Pb and 9,810 mg center dot kg(-1) Zn in soils, and 62 mg center dot kg(-1) As, 1,765 mg center dot kg(-1) Cu, 280 mg center dot kg(-1) Pb and 3,460 mg center dot kg (-1) Zn in vegetation were measured. However, unusually for smelters and mines of a similar size, the elevated trace element concentrations in soils were found to be restricted to the immediate vicinity of the mines and smelters (maximum 2-3 km). Parent material, prevailing wind direction, and soil physical and chemical characteristics were found to correlate poorly with the restricted trace element distributions in soils. Hypotheses are given for this unusual distribution: (1) the contaminated soils were removed by erosion or (2) mines and smelters released large heavy particles that could not have been transported long distances. Analyses of the accumulation of trace elements in vegetation (median ratios: As 0.06, Cu 0.19, Pb 0.54 and Zn 1.07) and the percentage of total trace elements being DTPA extractable in soils (median percentages: As 0.06%, Cu 15%, Pb 7% and Zn 4%) indicated higher relative trace element mobility in soils with low total concentrations than in soils with elevated concentrations.

Trace element partitioning and soil particle characterisation around mining and smelting areas at Tharsis, Riotinto and Huelva, SW Spain

Trace elements may present an environmental hazard in the vicinity of mining and smelting activities. However, the factors controlling trace element distribution in soils around ancient and modem mining and smelting areas are not always clear. Tharsis, Riotinto and Huelva are located in the Iberian Pyrite Belt in SW Spain. Tharsis and Riotinto mines have been exploited since 2500 B.C., with intensive smelting taking place. Huelva, established in 1970 and using the Flash Furnace Outokumpu process, is currently one of the largest smelter in the world. Pyrite and chalcopyrite ore have been intensively smelted for Cu. However, unusually for smelters and mines of a similar size, the elevated trace element concentrations in soils were found to be restricted to the immediate vicinity of the mines and smelters, being found up to a maximum of 2 kin from the mines and smelters at Tharsis, Riotinto and Huelva. Trace element partitioning (over 2/3 of trace elements found in the residual immobile fraction of soils at Tharsis) and soil particles examination by SEM-EDX showed that trace elements were not adsorbed onto soil particles, but were included within the matrix of large trace element-rich Fe silicate slag particles (i.e. 1 min circle divide at least 1 wt.% As, Cu and Zn, and 2 wt.% Pb). Slag particle large size (I mm 0) was found to control the geographically restricted trace element distribution in soils at Tharsis, Riotinto and Huelva, since large heavy particles could not have been transported long distances. Distribution and partitioning indicated that impacts to the environment as a result of mining and smelting should remain minimal in the region. (c) 2006 Elsevier B.V. All rights reserved.

A preliminary investigation into mining and smelting impacts on trace element concentrations in the soils and vegetation around Tharsis, SW Spain

Toxic trace elements present an environmental hazard in the vicinity of mining and smelting activities. However. the processes of transfer of these elements to groundwater and to plants are not always clear. Tharsis mine. in the Iberian pyrite belt (SW Spain), has been exploited since 2500 BC, with extensive smelting, taking place front the 1850S until the 1920s. Sixty four soil (mainly topsoils) and vegetation samples were collected in February 2001 and analysed by ICP-AES for 23 elements. Concentrations are 6-6300 mg kg(-1) As and 14-24800 mg kg(-1) Pb in soils, and 0.20-9 mg kg(-1) As and 2-195 mg Pb in vegetation. Trace element concentrations decrease rapidly away from the mine. with As and Pb concentrations in the range 6-1850 mg kg(-1) (median 22 mg kg(-1)) and 14-31 mg, kg(-1) (median 43 mg, kg(-1)), respectively, 1 km away from the mine. These concentrations are low when compared to other well-studied mining and smelting areas (e.g. 600 mg kg(-1) As at 8 km from Yellowknife smelter, Canada; >100 mg kg(-1) Pb over 270 km(2) around the Pb-Zn Port Pirie smelter. South Australia: mean of 1419 mg kg(-1) Pb around Aberystwyth smelter, Wales, UK). The high metal content of the vegetation and the low soil pH (mean pH 4.93) indicate the potential for trace element mobility which Could explain the relatively low concentration of metals in Tharsis topsoils and cause threats to plans to redevelop the Tharsis area as an orange plantation.

Factors affecting distribution and mobility of trace elements (Cu, Pb, Zn) in a perennial grapevine (Vitis vinifera L.) in the Champagne region of France

Soil and Vitis vinifera L (coarse and fine roots, leaves, berries) concentration and geochemical partitioning of Cu, Pb and Zn were determined in a contaminated calcareous Champagne plot to assess their mobility and transfer. Accumulation ratios in roots remained low (0.1-0.4 for Cu and Zn, <0.05 for Pb). Differences between elements resulted from vegetation uptake strategy and soil partitioning. Copper, significantly associated with the oxidisable fraction (27.8%), and Zn with the acid soluble fraction (33.3%), could be mobilised by rhizosphere acidification and oxidisation, unlike Pb, essentially contained in the reducible fraction (72.4%). Roots should not be considered as a whole since the more reactive fine roots showed higher accumulation ratios than coarse ones. More sensitive response of fine roots, lack of correlation between chemical extraction results and vegetation concentrations, and very limited translocation to aerial parts showed that fine root concentrations should be used when assessing bioavailability. (C) 2008 Elsevier Ltd. All rights reserved.

Spatangoid-produced ichnofabrics (Bateig Limestone, Miocene, Spain) and the preservation of spatangoid trace fossils

A spatangoid-produced ichnofabric is described from the Miocene Bateig Limestone, SE Spain. This ichnofabric is characterized by the dominant presence of large meniscate burrows (Bichordites) produced by irregular echinoids. This constitutes an unusual mode of occurrence for spatangoid bioturbation, as their traces are most typically preserved in bases and tops of sandstone event beds. In fact, despite their important role as burrowers in modern settings (that can be extended back to the Early Cretaceous based on their body fossil record), spatangoid trace fossils (Scolicia and Bichordites) are comparatively rare. Several factors play an important role in their preservation: mechanism of burrowing, sediment characteristics, early diagenesis and presence/absence of deep-tier burrowers. Spatangoid-produced ichnofabrics, such as those from the Bateig Limestone, characterize depositional settings with intermittent deposition of event beds where there is an absence of deeper-tier bioturbation. (C) 2008 Elsevier B.V. All rights reserved

Trace fossils and pseudofossils from the Wealden strata (non-marine Lower Cretaceous) of southern England

The trace fossils of the Wealden (non-marine Lower Cretaceous) of southern England are described. Sixteen invertebrate ichnotaxa include Agrichnium fimbriatus, Beaconites antarcticus, B. barretti, Cochlichnus anguineus, Diplichnites triassicus, Diplocraterion parallelum, Lockeia siliquaria, L. serialis, Monocraterion cf. tentaculum, Palaeophycus striatus, P. tubularis, Planolites montanus, Protovirgularia rugosa, Rhizocorallium isp., Scoyenia cf. gracilis, Unisulcus minutus, insect and root traces. Tetrapod tracks and trackways include tridactyl Iguanodontipus burreyi and other ornithopods, theropod, and tetradactyl sauropod (or possibly ankylosaur), together with extensive dinosaur tramplings. Coprolites are referred to two broad types: spiral, with or without included fish scales (attributable to sharks), and elongate and irregular (possibly produced by reptiles). A skinprint and two types of pseudofossil are also included. Five environmental associations are recognised: (1) lacustrine/lagoonal; (2) brackish incursions (flooding events) into the lacustrine/lagoonal environment; (3) a marginal lacustrine association with fluvial input; (4) a fluvial (lacustrine delta) association; (5) floodplain sediments (seasonal wetlands). These associations are assigned to the fluvial-lacustrine Scoyenia Ichnofacies and the incursions to Glossifungites lchnofacies. (c) 2005 Elsevier Ltd. All rights reserved.