From sprawl to compactness and back: population dynamics (1848–2011) and the economic structure of a Mediterranean city

In the recent decades southern European cities experienced morphological changes and a demographic transition towards zero (or negative) growth and aging. Population dynamics shifted from the impressive growth of the post-industrial period into recent de-concentration processes determining the spillover of commercial and residential settlements across the surrounding rural areas. Based on long-term demographic data, the present study hypothesizes that urban expansion did not follow a one-way linear path from compactness to dispersion while reflecting differentiated growth patterns based on the specific socioeconomic context at the local scale. Along a sufficiently long time period non-linear expansion waves alternating settlement densification and scattering are expected to be found especially in complex urban contexts such as those developed in the Mediterranean region. This hypothesis was tested for a paradigmatic case study in southern Europe (Athens, Greece) using demographic data covering 160 years (1848–2011). Urban growth in Athens was assessed through the analysis of long-term census data made available on a district level. These data provide information on the spatial distribution of resident population and characterize distinct expansion waves according to the dominant socioeconomic context. Results of the study were discussed in the light of the debate on future development of the Mediterranean cities and the (changing) economic relations with the surrounding region.     

The Calabrian Stage redefined

The name Calabrian was introduced in the geological literature by the French stratigrapher Maurice Gignoux in 1910, and later described in his important monograph （633 pages） ＂Les formations marines pliocknes et quaternaires de l＇ltalie du sud et de la Sicile ＂published in 1913. Detailed data were provided on several sections （Santa Maria di Catanzaro, Caraffa, Monasterace, Palermo） and on their fossil content. The Calabrian Stage has commonly been used for over fifty years as the oldest subdivision of the Qua- ternary, notably in the time scales of Berggren ＆ van Cou- vering （1974） and Haq ＆ Eysinga （1987）. However, after the GSSP for the Pliocene/Pleistocene boundary （P/P） was approved by INQUA in 1982 and ratified by lUGS in 1984 at the Vrica section of Calabria, there was a decline in the usage of the stage name, and an increasing tendency by many Quaternary workers to question the boundary stratotype. This was because there was increasing evidence that it did not correspond to the beginning of the ＂ice age＂. In doing so, they were not complying with the recommendations presented at the 18th International Geological Congress （IGC） in London, 1948 （Oakley, 1950）.     

XMM-Newton observations of the isolated neutron star 1RXS J214303.7+065419/RBS1774

We report XMM-Newton observations of the isolated neutron star RBS1774 and confirm its membership as an XDINS. The X-ray spectrum is best fit with an absorbed blackbody with temperature kT=101 eV and absorption edge at 0.7 keV. No power law component is required. An absorption feature in the RGS data at 0.4 keV is not evident in the EPIC data, but it is not possible to resolve this inconsistency. The star is not seen in the UV OM data to m _AB ∼21. There is a sinusoidal variation in the X-ray flux at a period of 9.437 s with an amplitude of 4%. The age as determined from cooling and magnetic field decay arguments is 10⁵–10⁶ yr for a neutron star mass of 1.35–1.5 M_⊙.      

A Fe K-edge XAS study of amethyst

An X-ray absorption spectroscopy (XAS) study of the Fe local environment in natural amethyst (a variety of α-quartz, SiO₂) has been carried out. Room temperature measurements were performed at the Fe K-edge (7,112 eV), at both the X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) regions. Experimental results were then compared with DFT calculations. XANES experimental spectra suggest Fe to occur mainly in the trivalent state, although a fraction of Fe²⁺ is identified. EXAFS spectra, on the other hand, reveal an unusual short distance for the first coordination shell:  = 1.78(2) Å, the coordination number being 2.7(5). These results allow to establish that Fe replaces Si in its tetrahedral site, and that numerous local distortions are occurring as a consequence of the presence of Fe³⁺ variably compensated by protons and/or alkaline ions, or uncompensated. The formal valence of Fe, on the basis of both experimental and DFT structural features, can be either 4+ or 3+. Taking into account the XANES evidences, we suggest that Fe mainly occurs in the trivalent state, compensated by protons, and that a minor fraction of Fe⁴⁺ is stabilised by the favourable local structural arrangement.     

Groundwater flow systems in turbidites of the Northern Apennines (Italy): natural discharge and high speed railway tunnel drainage

Turbidites crop out extensively in the Northern Apennine mountains (Italy). The huge amounts of groundwater drained by tunnels, built for the high speed railway connection between Bologna and Florence, demonstrate the aquifer-like behaviour of these units, up to now considered as aquitards. A conceptual model of groundwater flow systems (GFS) in fractured aquifers of turbidites is proposed, taking into account both system natural state and the perturbation induced by tunnel drainage. Analysis of hydrological data (springs, streams and tunnel discharge), collected over 10 years, was integrated with analysis of hydrochemical and isotopic data and a stream-tunnel tracer test. Hydrologic recession analysis of undisturbed conditions is a key tool in studying turbiditic aquifer hydrogeology, permitting the discrimination of GFS, the estimation of recharge relative to the upstream reach portion and the identification of springs most vulnerable to tunnel drainage impacts. The groundwater budgeting analysis provides evidence that the natural aquifer discharge was stream-focused through GFS, developed downslope or connected to main extensional tectonic lineaments intersecting stream beds; now tunnels drain mainly active recharge groundwater and so cause a relevant stream baseflow deplenishment (approximately two-thirds of the natural value), possibly resulting in adverse effects on local ecosystems.     

Chromium solubility in MgSiO3 ilmenite at high pressure

The crystal structure and chemical composition of crystals of (Mg_1?x Cr _x )(Si_1?x Cr _x )O₃ ilmenite (with x = 0.015, 0.023 and 0.038) synthesized in the model system Mg₃Cr₂Si₃O₁₂–Mg₄Si₄O₁₂ at 18–19 GPa and 1,600 °C have been investigated. Chromium was found as substitute for both Mg at the octahedral X site and Si at the octahedral Y site, according to the reaction Mg²⁺ + Si⁴⁺ = 2Cr³⁺. Such substitutions cause a shortening of the <X–O> and a lengthening of the <Y–O> distances with respect to the values typically observed for pure MgSiO₃ ilmenite and eskolaite Cr₂O₃. Although no high Cr contents are considered in the pyrolite model, Cr-bearing ilmenite may be the host for chromium in the Earth’s transition zone. The successful synthesis of ilmenite with high Cr contents and its structural characterization are of key importance because the study of its thermodynamic constants combined with the data on phase relations in the lower-mantle systems can help in the understanding of the seismic velocity and density profiles of the transition zone and the constraining composition and mineralogy of pyrolite in this area of the Earth.     

Towards new applications of underwater photogrammetry for investigating coral reef morphology and habitat complexity in the Myeik Archipelago,Myanmar

Photogrammetry represents a non-destructive, cost-effective tool for coral reef monitoring, able to integrate traditional remote sensing techniques and support researchers’ work. However, its application to submerged habitats is still in early stage. We present new ways to employ Structure from Motion techniques to infer properties of reef habitats. In particular, we propose the use of Digital Surface Models and Digital Terrain Models for assessing coral colonies extension and height and discriminating between seabed and coral cover. Such information can be coupled with digital rugosity estimates to improve habitat characterization. DTM, DSM and orthophotos were derived and used to compute a series of metrics like coral morphologies, reef topography, coral cover and structural complexity. We show the potentialities offered by underwater photogrammetry and derived products to provide useful basic information for marine habitat mapping, opening the possibility to extend these methods for large-scale assessment and monitoring of coral reefs.     

Assessment of coastal flooding hazard along the Emilia Romagna littoral,IT

Aim of this paper is to develop simple tools for mapping — at regional and local scale — coastal areas exposed at flooding risk. A two-step simplified procedure for coastal management purposes is presented and is applied to Emilia Romagna (Italy), whose low and sandy coast faces the relatively mild Northern Adriatic Sea. The procedure is composed by a 1D conceptual model to determine flooding probability along wide coastal stretches and by a more detailed 2D Level II reliability method, that provides local quantitative statistical maps of inland flooding propagation. Qualitative maps obtained by literature approaches and quantitative results of flooding probability along the littoral show a good agreement. A coastal flood state indicator is proposed to rapidly assess coastal hazard.