The populist eruption and the urban question

Generalizing the recent experience of the United States, the common wisdom associates today’s ‘populist explosion’ with a deepening urban-rural divide, in which small towns and rural regions are seen as reservoirs of populist anger while large cities in the most prosperous areas are portrayed as strongholds of multicultural coexistence and liberal democracy. In challenging this representation, this paper underlines the ‘urban roots’ of today’s populist phenomenon in Western societies, using Italy as illustrative evidence. It is argued that cities – far from being pacified enclaves of happiness and democracy – are central to the contradictions of contemporary societies and their degenerations, reflecting an ambivalent relationship with the nation-state: potential sites of post-national democracy, on the one hand, but also spaces contributing to the current populist-white-revanchist wave sweeping Western societies, on the other hand. In doing so, the paper shows how the intersected housing and refugee crises have fomented impulses of ethnic-majority revanchism within Italy’s cities and towns in a context of late neoliberalism.     

A semi-analytic algorithm for constructing lower dimensional elliptic tori in planetary systems

We adapt the Kolmogorov’s normalization algorithm (which is the key element of the original proof scheme of the KAM theorem) to the construction of a suitable normal form related to an invariant elliptic torus. As a byproduct, our procedure can also provide some analytic expansions of the motions on elliptic tori. By extensively using algebraic manipulations on a computer, we explicitly apply our method to a planar four-body model not too different with respect to the real Sun–Jupiter–Saturn–Uranus system. The frequency analysis method allows us to check that our location of the initial conditions on an invariant elliptic torus is really accurate.     

On the Stochasticity of the Asteroid Belt

The study of the stochasticity of the asteroid belt requires the analysis of a large number of orbits. We detect the dynamical character of a set of 5 400 asteroids using the Fast Lyapunov Indicator, a method of analysis closely related to the computation of the Lyapunov Characteristic Exponents, but cheaper in computational time. For both regular and chaotic orbits we try to associate the motion to the underlying resonances network. For it we consider different methods of classification of rational numbers proposed by number theory, and we choose the one which seems to be strictly related to the dynamical behaviour of a system. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of enhanced loads of nutrients on epiphytes on leaves and rhizomes of Posidonia oceanica

The increase of anthropogenic activities has severely altered both terrestrial and aquatic systems. Urbanisation, excessive use of agricultural fertilisers, organic runoff and climate change have caused an increase of nutrients in coastal waters, altering the diversity and food-web structure of benthic assemblages. The aims of the present paper were to text if an experimentally increased availability of nutrients, primarily nitrogen and phosphorous, in an oligotrophic basin, would affect epiphytic assemblages on leaves and rhizomes of P. oceanica and whether this could change rates of consumption of the plant by herbivores. In particular, we tested the hypothesis i) that changes to species composition and abundance of epiphytic assemblages generated by nutrients enrichment would vary between leaves and rhizomes and that ii) alterations to epiphytic assemblages on leaves might, in turn, modify feeding rates of herbivorous fish. After two years, the structure of both leaf and rhizome epiphytic assemblages responded to changes in nutrient concentrations before the occurrence of drastic alterations to the host plant, but only the former showed significant changes in terms of species composition. Moreover, a larger intensity of grazing on P. oceanica leaves was documented in experimentally enriched areas than in controls. The present findings and conclusions are applicable to other systems where patterns of biodiversity depend on changes in the availability of nutrients due to natural or anthropogenic events, likely interacting with biological processes, such as competition and grazing.     

A chronology for the long pollen record from Lake Wangoom,western Victoria (Australia) as derived from uranium/thorium disequilibrium dating

The chronology of a long pollen record from Lake Wangoom, one of the few long palaeoenvironmental records from southeastern Australia, is discussed in light of the acquisition of new uranium/thorium disequilibrium (UTD) dates. Of crucial importance has been the estimation of ages for two major pre‐Holocene phases of forest expansion recorded in the sequence, with implications for the timing of periods of high effective precipitation in the region. The new UTD ages indicate that the oldest forest phase falls within the Penultimate Interglacial whereas the later phase corresponds with the Last Interglacial. This is older than indicated by previously reported UTD and radiocarbon dates, but confirms a chronology based on direct correlation with the pollen record from marine core E55‐6. The new chronology of the Lake Wangoom sequence provides evidence that phases of sustained forest development in southeast Australia relate to interglacial periods. In comparison, interstadial periods appear to be characterised by only minor arboreal development. Marked differences in the pattern of vegetation development evident in each of the interglacials are thought to reflect varying climatic and anthropogenic influences. Copyright © 2002 John Wiley & Sons, Ltd.     

Three-body planetary problem: study of KAM stability for the secular part of the Hamiltonian

The Hamiltonian representing the average over the mean-motion angles (i.e. the secular part) of the three-body planetary problem is considered. An efficient algorithm constructing invariant tori for the trajectories in phase space is provided. To give a possible practical application, we consider a toy-model including the main terms of the secular part of a hypothetic Sun-Jupiter-Saturn system having eccentricities and inclinations equal to 1/20 of the true ones. The scheme of a KAM proof of the stability of the model is sketched. The proof is “computer assisted”.     

Atmospheric C variations derived from tree rings during the early Younger Dryas

Atmospheric radiocarbon variations over the Younger Dryas interval, from 13,000 to 11,600 cal yr BP, are of immense scientific interest because they reveal crucial information about the linkages between climate, ocean circulation and the carbon cycle. However, no direct and reliable atmospheric ¹⁴C records based on tree rings for the entire Younger Dryas have been available. In this paper, we present (1) high-precision ¹⁴C measurements on the extension of absolute tree-ring chronology from 12,400 to 12,560 cal yr BP and (2) high-precision, high-resolution atmospheric ¹⁴C record derived from a 617-yr-long tree-ring chronology of Huon pine from Tasmania, Australia, spanning the early Younger Dryas. The new tree-ring ¹⁴C records bridge the current gap in European tree-ring radiocarbon chronologies during the early Younger Dryas, linking the floating Lateglacial Pine record to the absolute tree-ring timescale. A continuous and reliable atmospheric ¹⁴C record for the past 14,000 cal yr BP including the Younger Dryas is now available. The new records indicate that the abrupt rise in atmospheric Δ¹⁴C associated with the Younger Dryas onset occurs at 12,760 cal yr BP, 240 yrs later than that recorded in Cariaco varves, with a smaller magnitude of 40‰ followed by several centennial Δ¹⁴C variations of 20–25‰. Comparing the tree-ring Δ¹⁴C to marine-derived Δ¹⁴C and modelled Δ¹⁴C based on ice-core ¹⁰Be fluxes, we conclude that changes in ocean circulation were mainly responsible for the Younger Dryas onset, while a combination of changes in ocean circulation and ¹⁴C production rate were responsible for atmospheric Δ¹⁴C variations for the remainder of the Younger Dryas.     

Chronology of Vesuvius’ activity from A.D. 79 to 1631 based on archeomagnetism of lavas and historical sources

The activity of Vesuvius between A.D. 79 and 1631 has been investigated by means of precise archaeomagnetic dating of primary volcanic deposits and taking into account the stratigraphy of lavas and tephra, historical written accounts, archaeological evidence related to the developing urbanisation, and radiocarbon ages. We found that the historical records are highly useful in constraining the timing of the main events, even if the data are often too scarce and imprecise for ascertaining the details of all phases of activity, especially their magnitude and emplacement of all the deposit types. In addition, some eruptions that took place in the 9^th and 10^th centuries appear to be unnoticed by historians. The archaeomagnetic study involved 26 sites of different lavas and 2 pyroclastic deposits. It shows that within the 15 centuries which elapsed between A.D. 79 and 1631, the effusive activity of Vesuvius clustered in the relatively short period of time between A.D. 787 and 1139 and was followed by a 5-century-long repose period. During this time Vesuvius prepared itself for the violent explosive eruption of 1631. The huge lavas shaping the morphology of the coast occurred largely through parasitic vents located outside the Mount Somma caldera. One of these parasitic vents is located at low elevation, very close to the densely inhabited town of Torre Annunziata. Among the various investigated lavas, a number of which were previously attributed to the 1631 eruption, none is actually younger than the 12^th century. Therefore it is definitively concluded that the destructive 1631 event was exclusively explosive.Editorial handling: J. McPhie     

Beyond the Anglo-American hegemony in human geography: a European perspective

Over the past five years or so, Anglo-American hegemony in human geography has been widely debated. This debate has highlighted the obstacles put in the way of the building of a more international geographical discipline. In this paper, we reflect on the possibilities and also the limitations of Europe as a context for the experimentation with a more cross-national discipline. In doing so, we notice on the one hand the increasing attention towards the Europeanisation of human geography, particularly at an institutional level, but on the other hand we also notice the lack of some basic forms and tools of communication and exchange that might facilitate the mobilisation of scholars around the ‘European project’. The paper tries to offer a contribution to this issue by discussing the ways in which a European journal of human geography might be conceived and also concretely organised. In this respect the paper takes into account issues of language, access to scientific knowledge and recognition of cultural and academic diversities.