The Cosmology of Extra Dimensions and Varying Fundamental Constants

I briefly present the Organizing Committee's and my own motivation for organizing this workshop, and I suggest a few key questions for which we will try to find possible answers in the coming days. This revised version was published online in July 2006 with corrections to the Cover Date.     

A seasonal climate model of the atmospheres of the giant planets at the voyager encounter time: I. Saturn's stratosphere

A radiative seasonal model which incorporates a multilayer radiative transfer treatment at wave-lengths longward of 7 μm is presented and applied to Saturn's stratosphere. Opacities due to H₂-He, CH₄, C₂H₂, and C₂H₆ are included. Season-dependent insolation is shown to produce a strong hemispheric asymmetry decreasing with depth at the Voyager encounter times, and seasonal amplitudes of 30°K at the poles are predicted in the high stratosphere. The ring-modulated dependence of the insolation and the orbital eccentricity are shown to have a significant effect. Calculations agree closely with the Voyager 1 and 2 radio occultation ingress profiles recorded at 76°S and 36.5°S for CH₄/H₂ = 3.5 + 1.4/? 1.0 × 10^?3;the estimated errors include modeling systematic errors and uncertainties in the occultations profiles. The possible role of aerosols in the stratospheric heating is analyzed. The Voyager 2 egress profile recorded at 31°S cannot be reproduced by calculations. Some constraints on the C₂H₂ and C₂H₆ abundances are derived. The upper portion of the occultation profiles (p < 3mbar) can be matched for C₂H₂/H₂ = 1.0 + 1.3/?0.6 × 10^?7, C₂H₆/H₂ = 1.5 + 1.8/?0.9 × 10^?6 at 76°S and C₂H₂/H₂ = 4 + 6/?4 × 10^?8, C₂H₆/H₂ = 6 + 9/?6 × 10^?7 at 36.5°N. At the northern occultation latitude, the discrepancy with the concentrations derived from analysis of IRIS spectra by R. Courtin, D. Gautier, A. Marten, B. Bézard, and R. Hanel (1984, Astrophys. J.287) can be explained by a sharp variation of the mixing ratios of these gases with altitude in the upper stratosphere. Other interpretations are discussed.     

Lithium Abundances in the Atmospheres of SLR C-Giants WZ Cas and WX Cyg from Resonance and Subordinate Li I Lines

Lithium abundances in the atmospheres of the super Li-rich C-giants WZ Cas and WX Cyg are derived by the spectral synthesis technique using the Li I resonance line at λ670.8 nm and three subordinate lines at λλ 812.6, 610.4 and 497.2 nm. The differences between the Li abundances derived from the λ670.8 nm line and the λλ 497.2, 812.6 nm lines do not exceed ±0.5 dex. The lithium line at λ610.4 nm provides typically lower abundances than the resonance line (by ≈ 1 dex). The mean LTE and NLTE Li abundances from three Li I lines (excluding λ610.4 nm) are 4.7, 4.9 for WZ Cas, and 4.6, 4.8 for WX Cyg, respectively. This revised version was published online in July 2006 with corrections to the Cover Date.     

SARG: The High Resolution Spectrograph of TNG

SARG is a cross dispersed echelle spectrograph in operation since late spring 2000 at the Italian Telescopio Nazionale Galileo (TNG) 3.5 m telescope, La Palma. SARG offers both single object and long slit (up to 26 arcsec) observing modes covering a spectral range from λ = 0.37 up to1 μm, with resolution ranging from R = 29,000 up to R = 164,000. Cross dispersion is provided by means of a selection of four grisms; interference filters may be used for the long slit mode (up to 26 arcsec). A dioptric camera images the cross dispersed spectra onto a mosaic of two 2048 × 4096 EEV CCDs (pixel size: 13.5 μm) allowing complete spectral coverage at all resolving power for λ < 0.8 μm. In order to reach a high wavelength calibration precision an iodine-absorbing cell is provided. A Distributed Active Temperature Control System (DATCS) maintains constant the temperature of all spectrograph components at a preset value. Early results show that SARG works according to original specifications in terms of wavelength coverage, efficiency (measured peak efficiency is about 13%),resolution (maximum resolution R = 164,000 using a 0.3 arcsec slit, R ∼144,000 using an image slicer), and stability (preliminary estimates of radial velocity accuracy is ∼3 m/s using the iodine cell and ±150 m/s without the iodine cell). This revised version was published online in July 2006 with corrections to the Cover Date.     

Late Hercynian–Mesozoic thinning in the Alboran domain: metamorphic data from the northern Rif, Morocco

In the Alboran domain, two crustal-thickening late-orogenic extension cycles are superposed. The importance of the late Alpine thinning of the Alpujarride-Sebtide crustal section on top of the Beni Bousera peridotites is discussed here in metamorphic petrological terms. The Alpine metamorphism operated first under a HP–LT gradient, and reached the eclogite facies in the Permian–Triassic phyllites, before retrogression under a high geothermal gradient. A contrasting, higher temperature metamorphism characterizes the pre-Permian section, reaching the HP-granulite facies at the bottom of the crustal section. By reference to the western European setting, the granulites relate to the Hercynian orogeny, as supported by the isotopic ages of the enclosed, armoured monazite crystals. Thus, thinning of an overthickened crust might have occurred there during the late Hercynian extension and Tethyan opening, before being reactivated during the late Oligocene.     

Detailed <Superscript>40</Superscript>Ar/<Superscript>39</Superscript>Ar dating of geologic events associated with the Mantos Blancos copper deposit,northern Chile

The ⁴⁰Ar/³⁹Ar geochronological method was applied to date magmatic and hydrothermal alteration events in the Mantos Blancos mining district in the Coastal Cordillera of northern Chile, allowing the distinction of two separate mineralization events. The Late Jurassic Mantos Blancos orebody, hosted in Jurassic volcanic rocks, is a magmatic-hydrothermal breccia-style Cu deposit. Two superimposed mineralization events have been recently proposed. The first event is accompanied by a phyllic hydrothermal alteration affecting a rhyolitic dome. The second mineralization event is related to the intrusion of bimodal stocks and sills inside the deposit. Because of the superposition of several magmatic and hydrothermal events, the obtained ⁴⁰Ar/³⁹Ar age data are complex; however, with a careful interpretation of the age spectra, it is possible to detect complex histories of successive emplacement, alteration, mineralization, and thermal resetting. The extrusion of Jurassic basic to intermediate volcanic rocks of the La Negra Formation is dated at 156.3 ± 1.4 Ma (2σ) using plagioclase from an andesitic lava flow. The first mineralization event and associated phyllic alteration affecting the rhyolitic dome occurred around 155–156 Ma. A younger bimodal intrusive event, supposed to be equivalent to the bimodal stock and sill system inside the deposit, is probably responsible for the second mineralization event dated at ca. 142 Ma. Other low-temperature alteration events have been dated on sericitized plagioclase at ca. 145–146, 125, and 101 Ma. This is the first time that two distinct mineralization events have been documented from radiometric data for a copper deposit in the metallogenic belt of the Coastal Cordillera of northern Chile. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Development and morphometry of sinkholes in coastal plains of Apulia, southern Italy. Preliminary sinkhole susceptibility assessment

Evolution of coastlines in karst areas may be strongly controlled by dissolution processes which favour the development of surface and subsurface landforms. The generation of caves in these environments is commonly favoured by the mixing between fresh and brackish waters. The sinkholes resulting from the upward propagation of the caves may interfere with the anthropogenic environment and cause damage to human elements (property and activities). To highlight the often underestimated importance of karst phenomena in coastal areas, we have analyzed a coastal stretch of Apulia, in southern Italy. The study area, covering an extension of about 6 km², is situated in the Ionian coast, and presents several interesting karst landforms that are generally connected to caves. Tens of sinkholes were mapped through field surveys, multi-year aerial-photographs (dating back to the 1940s) and archival research. We have performed a morphometric analysis of the sinkholes. The analysis describes the main parameters of the sinkholes (area, length, width, and depth), and the control exerted by the main discontinuity systems in the area. The detrimental effects derived from interaction between human environment and these karst landforms is also under consideration. A sinkhole susceptibility map, which may provide useful information for planners, developers and the insurance industry has eventually been produced through application of a decision tree model.     

Formation of Zn–Ca phyllomanganate nanoparticles in grass roots

It is now well established that a number of terrestrial and aquatic microorganisms have the capacity to oxidize and precipitate Mn as phyllomanganate. However, this biomineralization has never been shown to occur in plant tissues, nor has the structure of a natural Mn(IV) biooxide been characterized in detail. We show that the graminaceous plant Festuca rubra (red fescue) produces a Zn-rich phyllomanganate with constant Zn:Mn and Ca:Mn atomic ratios (0.46 and 0.38, respectively) when grown on a contaminated sediment. This new phase is so far the Zn-richest manganate known to form in nature (chalcophanite has a Zn:Mn ratio of 0.33) and has no synthetic equivalent. Visual examination of root fragments under a microscope shows black precipitates about ten to several tens of microns in size, and their imaging with backscattered and secondary electrons demonstrates that they are located in the root epidermis. In situ measurements by Mn and Zn K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray diffraction (XRD) with a micro-focused beam can be quantitatively described by a single-phase model consisting of Mn(IV) octahedral layers with 22% vacant sites capped with tetrahedral and octahedral Zn in proportions of 3:1. The layer charge deficit is also partly balanced by interlayer Mn and Ca. Diffracting crystallites have a domain radius of 33 Å in the ab plane and contain only 1.2 layers (8.6 Å) on average. Since this biogenic Mn oxide consists mostly of isolated layers, basal 00l reflections are essentially absent despite its lamellar structure. Individual Mn layers are probably held together in the Mn–Zn precipitates by stabilizing organic molecules. Zinc biomineralization by plants likely is a defense mechanism against toxicity induced by excess concentrations of this metal in the rhizosphere.     

The pathway of mercury in contaminated waters determined by association with organic carbon (Tagus Estuary,Portugal)

Reactive dissolved Hg (Hg_R), non-reactive dissolved Hg (Hg_NR), particulate Hg (Hg_P), dissolved organic C (DOC), particulate organic C (POC), salinity and other interpretative parameters were determined in water samples collected in the North Channel and in adjacent areas of the Tagus estuary (Portugal). Higher concentrations of both dissolved and particulate Hg in the North Channel indicate a pollution source and raise the possibility of Hg escaping to adjacent areas by tidal action. This transport was confirmed by the increase of Hg_R with salinity and Hg_NR with DOC, along a longitudinal axis paralleling the North Channel. Apparently, Hg leaving this channel is progressively complexed by inorganic and organic ligands. Near the mouth of the estuary, values decreased reflecting dilution with seawater. Moreover the Hg_P:POC ratio also increased seaward, suggesting mixing with Hg enriched particles that escaped the North Channel, or incorporation of dissolved Hg species in river-derived particles. These results suggest that the pathway of anthropogenic Hg in contaminated waters may be identified by their enrichment in organic matter, both in the dissolved and particulate fraction.     

Effectiveness of sulfate-reducing passive bioreactors for treating highly contaminated acid mine drainage: I. Effect of hydraulic retention time

Sulfate-reducing passive bioreactors have proved to be an effective technology for the treatment of acid mine drainage (AMD) contaminated waters over relatively short periods of time (1–5 a). However, long-term efficiency can be limited by several factors including problems related to the hydraulic properties of the reactive mixture. In this study, the effect of two hydraulic retention times (HRTs) of 7.3 d and 10 d on the performance of passive bioreactors was evaluated over an 11-month period for the treatment of a highly contaminated AMD. Evolution of the porosity and hydraulic conductivity of the reactive mixture was also evaluated during the 15-month operation of two bioreactors. Results indicated that bioreactors were effective at both HRTs for increasing the pH and alkalinity of contaminated water and for SO₄ and metal removal (60–82% for Fe and up to 99.9% for Cd, Ni and Zn). Although the quality of treated effluent was significantly improved with the 10 d HRT compared to the 7.3 d HRT, results showed that the higher HRT reduced the porosity and the permeability of the reactive mixture which might lead to hydraulic related problems and, eventually, to limited efficiency in long-term operation compared to a shorter HRT. The choice of HRT for a passive bioreactor must therefore consider both the desired quality of treated effluent and the potential for deterioration of hydraulic properties in the reactive mixture.